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OSMANIA
Call No. # 37' #7
Author
This book should be returned on or before the date last marked below.
RADIO: BEAM AND BROADCAST
TO THE INVENTORS OF
RADIO-TELEGRAPHY AND RADIO-TELEPHONY
THIS BOOK IS
HUMBLY DEDICATED
Musical Mistress n/ House (* ' on hospitable thoughts intent "). '* Now, RECOLLECT,
ROBERT, AT A QUARTER TO NINE TUKN ON * Voi CHK SAPHTK' FROM COVKNT
HARDEN; AT TEN LRT IN THE STKINC;I'H QUAKTETTK FROM ST. JAMES'S HAIL;
AND AT KI..EVEN TUKN THK LAST QUAKTKTTK FKOM * Ricioi.KTTo ' FULL ON. BUT
MIND YOU CLOSE ONB TAI- iiKKOKfi Oi'KMNt; THK OTHKK ! " tivttons. 4I YES, MUM !"
Reproduced from the Punch. Almanack for 1878, by kind permission of the Proprietors,
RADIO: BEAM AND
BROADCAST
ITS STORY AND PATENTS
By A. H. MORSE
A.M.I.E.E., MEM. I.R.E. (NEW YORK)
Late Sitpt. Dom de Forest Wireless Telegraph Cv. 9
and United Wireless Telegraph Co.; Engineer,
Marconi's Wireless Telegraph Co. ; Wireless Adviser,
Indo-European Tele^aph Co.; Managing Director,
Marconi Wireless Telegtaph Company of Canada
LONDON; ERNEST BENN LIMITED
8 BOUVERIE STREET, E.C-4
1925 X
The Northumberland Press Ltd., Waterloo House
Thornton, Street, Newcastle-upon-Tync
INTRODUCTION
THE term " Radio " is used herein to connote radio-
telegraphy and radio-telephony, and not merely broad-
casting.
The bibliography of radio is already very extensive, and
while it contains much of a trashy or partisan order, the
balance very well covers the technical aspects of the subject
to date. There should, however, be room for a book which
presents the subject in a novel or more lucid way, or for
one that considers it from a new point of view; and it is
in the latter class that it is hoped that this book will find a
place.
Within the last few years the radio field has been
invaded by many thousands of persons who know nothing
of its evolution, and are therefore sometimes unable to
distinguish between what is new and what is old. The
consequence is that they waste much time and money in
re-inventing old devices, and in evolving others to circum-
vent imagined patents on inventions long since in the
public domain. The case of the spider-web coil may be
cited as an example. This will be found to have been
illustrated and described several years before the Great
War (12), but was heralded as a novelty two or three years
ago. It is one of the author's objects to help to correct
the perspective of these newcomers; and it is hoped that
this book will be of some assistance also to British and
American Patent Agents and Attorneys (new to the art),
Inventors, Experimenters, Journalists, Radio enthusiasts,
and " Whymen " generally, on both sides of the Atlantic.
The evolution of the radio art is traced herein, mainly
through the patent office records of inventions in use
to-day, or their lineal forebears. As a consequence, many
7
8 Radio: Beam and Broadcast
inventions of great merit arid one-time promise receive
little or no mention; and, except in a few cases, where
inventions are cited merely as evidence of the contemporary
knowledge of the art, the selection has been made, not by
the author, but by the test of utility. It may be observed
that this test has proved loo much for some of the most
heralded inventions.
Since so much reference is necessarily made to patents
of invention, it may be well lo warn the reader that an
invention is not always novel, useful or practicable because
it is patented.
While the loose practice of using the words " took out
a patent," instead of " was awarded a patent," is to be
unequivocally condemned, it must be admitted thai the
former often express a near-truth, particularly in con-
nection with a new art, and in certain countries.
Patenl Ofiice Examiners are only human, and when
they accept an application for a patent, it merely means
that they know of, and have succeeded iu tracing, nothing
to upset the inventor's claims. Of course, in large settled
countries, where there are specialist examiners for every
art or branch of an art, a patent has more significance
than it has in a new or undeveloped country, where a few
examiners have to deal with applications for patents in
relation to all the arts. Moreover, it is a fact lhal, until
a few years ago and perhaps they exist to-day there
were administrations which would, and often did, take an
" inventor's " money for a patent on a " perpetual-motion "
or " self-driving " machine. The U.S. Patent Office
requires a working model with such applications, which
is equivalent to refusal.
In any country a patent of invention is merely a " scrap
Introduction 9
of paper" until it has been supported by a law-suit; and it
is a wise inventor who knows whom to sue. Being blind,
Justice is only too liable to be influenced by a cloud of
"expert witnesses," which cosls much money.
If over much attention appears to have been given to
the arc, it is because, by reason of its simplicity and freedom
from patent restrictions, it may continue to have extensive
application; even if its present disabilities are not mitigated,
which is unlikely. 1
In the hope that he may thereby help to correct some
of the misapprehensions to which expression is so
persistently given in the lay press, the author has ventured
to look forward a little, and to hazard some opinions on
the lines of future development.
Wherever the British or American as the case may
be "equivalent" of a patent is known lo the author,
reference is given to it herein. It must not be assumed,
however, that such " equivalent " covers the same patent
protection in the two countries; because, in many cases,
there is a wide discrepancy in this respect. When a
patent number is prefixed (or suffixed) by (?), it means
that the author has not personally verified the reference.
The author is gratefully indebted to the courtesy of the
Commissioner of Patents at Washington, D.G., and to the
Controller of His Majesty's Stationery Office at London, for
permission to reproduce the extracts from American and
British patent specifications respectively, which appear
herein; and to the Director, U.S. Bureau of Standards, for
the photo and diagrams illustrating the chapter on Beam
and Short-wave Radio.
1 There has been some improvement since this was written.
10 Radio: Beam and Broadcast
The author's thanks are also due to Messrs. E. A. B.
Snoaden, H. F. White, H. R. Rivers-Moore, and R. E. H.
Carpenter of London, for assistance in procuring reference
to certain publications, not available in Montreal; and to the
Publishers for their courtesy and kindly advice on the
arrangement of the subject-matter.
MONTREAL,
December, 1924
TABLE OF CONTENTS
CHAP. PAGE
INTRODUCTION ...... 7
I. THE PAST TO IQ12 ..... 17
II. AFTER 1912 ...... 56
III. THE FUTURE ...... 63
IV. THE POULSEN ARC 75
V. BROADCASTING ...... 78
VI. REGENERATION: IN RECEPTION ... 83
VII. THE TRIODE AS A GENERATOR OF RADIO FREQUENCY
ALTERNATING CURRENT ... 86
VIII. BEAM AND SHORT-WAVE RADIO ... 88
IX. CONCLUSION ...... 96
APPENDIX SPECIFICATIONS OF BRITISH AND AMERICAN
PATENTS DESCRIBING THE MORE IMPORTANT STEPS
IN THE EVOLUTION OF RADIO . . . IOI
Means for Detecting- Electric Waves for use in Wire-
less Telegraphy. Ferdinand Braun. 1902. U.S.
No. 744,897 ...... 102
Wireless Signalling- Device. L. de Forest. 1904. U.S.
No. 748,507 ...... 105
Improvements in Wireless Telegraphy and Telephony.
Marconi. 1917. Br. Pat. 105,909 . . . 109
Improvements in Reflectors. Marconi. 1917. Br. Pat.
128,665 . . . . . .no
Transmission of Signals. Marconi. 1896. Br. Pat.
12,039 .116
Improvements in Syntonized Telegraphy without Line
Wires. Lodge. 1897. Br. Pat. 11,575 - - J2 4
Improvements in Telegraphy without Continuous Wires.
Braun. 1899. Br. Pat. 22,020 . . . 132
Improvements in Apparatus. Marconi. 1900. Br. Pat.
7,777 ...... 134
11
12 Contents
Improvements in Production, Regulation and Utilization
of Electric Currents of High Frequency. Tesla.
1896. Br. Pat. 20,981 . . . .138
Improvement in Electrical Indicators. Edison. 1883.
U.S. No. 37,031 ..... 143
Improvements in Instruments for Detecting- and Measuring
Alternating Currents. Fleming. 1905. Br. Pat,
24,850 ...... M4
Device for Amplifying Feeble Electric Currents. Lee de
Forest. 1907. U.S. 841,387 .... 148
Oscillation Detector. L. de Forest. 1908. U.S. 879,532 151
Receiving Arrangement. Gesellschaft fur Drahtlose
Telegraphic. 1913. Br. Pat. 8,821 . . 155
Receivers for Use in Wireless Telegraphy and Telephony.
Marconi and Franklin. 1913. Br. Pat. 13,636 . 158
Wireless Receiving System. Armstrong. 1913. U.S.
1,113,149 ...... 160
Improvements in Receivers. Marconi and Round. 1913.
Br. Pat. 28,413 ..... 167
Relay Arrangements for Alternating Cunents. Von Arco
and Mcissner. 1914. Br. Pat. 252 . . . 168
Method of Producing Alternating Currents. Thomson.
1896. U.S. 500,630 . . . . .175
Means for Conversion of Electric Energy, derived from a
Source of Direct Current into Varying or Alternating
Current. Duddcll. 1901. Br. Pat. 21,629 . . 177
Improvements relating to the Production of Alternating
Currents. Poulsen. 1903. Br. Pat. 15,599 . . 180
INDEX ........ 189
LIST OF ILLUSTRATIONS
PAGE
Frontispiece. Cartoon from Punch, 1877 . . i
Fig. i. Edison's Patent on a Diode for use in the Voltage
Control of Electric Lighting Systems (1885) . 19
Fig. 2 (a, &, c, d). Edison's Inverted and Earthed "L"
Aerial (1885) . . . . .21
Fig. 3. Elihu Thomson's Arc (1892) . . . .23
Fig. 4. Popoff s Receiver (1895) - 2 4
Fig. 5. Tesla's Improvements (1896) . . 2 5
Fig. 6. Lodge's Syntonic Patent (1897) - 2 7
Fig. 7. Lodge's Loud Speaker (1898) . . .28
Fig. 8. Braun's Transmitter (1899) . . . . 29
Fig. 9. Marconi's Syntonic Patent (1900) . . -3
Fig. 10. Poulsen Arc Generator (1903) . . 32
Fig. ii. Fleming's Diode (1904) . . . -33
Fig. 12. Marconi's Inverted " L" Aerial (rgos) . . 35
Fig. 13. Counterpoise Aerial (1905) . . . -36
Fig. 14. De Forest's " B " Battery (1906) . . -37
Fig. 15. De Forest's Triode Amplifier (1906) . . 37
Fig. 16. De Forest's Triode Amplifier (1906) . . 38
Fig. 17. De Forest's Triode Detector (1907) . . 39
Fig. 18. Telephone Transformer, Marconi (1907) . . 42
Fig. 19. The Importance of Non-Magnetic Aids to Naviga-
tion ..... facing 42
Fig. 20. Muirhcad's Aerial Counterpoise (1908) . . 43
Fig. 21. Fessenden's Method of Automatic Recording
(1908) 44
Fig. 22. Fleming's Diode with " B " Battery Effect . 45
Fig. 23. Regenerative Circuit (1912) . . .46
Fig. 24. Befogged : Before the Days of Wireless Direction-
Finders . . . . . -59
Fig. 25. Hall Air-Jet Relay Hot-wire Type . . .64
Fig. 26. Hall Air-Jet Relay Contact Type . . . 65
Fig. 26a. Poulsen Arc Station at Rome . . facing 75
Fig. 27. Telephone Hummer . . . . .86
Fig. 270. Parabolic Reflector for a Wave-Length of 10
metres ..... facing 88
Fig. 28. Hartley Circuit . . . . -90
18
14
List of Illustrations
FAG*
Fig. ap. Illustrating the need of a Wide Aperture to obviate
Leakage . . . . 9 2
Appendix Figures
I. Braun's Parabolic Reflector (1902) . . 103
II. De Forest's Parabolic Reflector (1902) . . 107
Marconi's Parabolic Reflector (1916) . . in
Franklin's Parabolic Reflector (1917) . . 113
Marconi's Transmitter and Receiver (1896) . 117
Marconi's Parabolic Reflector, etc. (1896) . 119
Marconi's Elevated and Earthed Aerial, etc.
(i897) ..... I21
Lodge's Syntonic System (1897) . .129
Lodge's Coupled-circuit Receiver (1898) . 133
Braun's Coupled-circuit Transmitter (1899) . 133
Marconi's Syntonic System (1900) . . 135
Tesla's Synchronous Discharger, etc. (1896) . 141
Edison's Diode (1883) - - *45
Fleming's Diode (1904) .... 146
De Forest's Amplifier (1906) . . . 149
De Forest's Amplifier (1906) . . .150
De Forest's Triode Detector (1907) . . 153
Schloemilch and Von Bronk's Triode Amplifier
and Reflex Circuit (1913) . . 157
Franklin's Regenerative Receiver (1913) . 159
Armstrong's Regenerative Receiver (1913) . 161
Armstrong's Regenerative Receiver (1913) . 163
Armstrong's Regenerative Receiver (1913) . 165
Round's Autodyne (1913) . . .169
Von Arco and Meissner's Relay (1914) . . 171
Von Arco and Meissner's Relay (1914) . . 173
Elihu Thomson's Arc (1892) . . .176
Poulsen's Arc (1903) . . . .181
Poulsen's Arc (1903) , . . -183
III.
IV.
V.
Va.
Vb.
VI.
Via.
VII.
VIII.
IX.
X.
XL
XII.
XIII.
XIV.
XV.
XVI.
XVIa.
XVI6.
XVII.
XVIII.
XVIIIa.
XIX.
XX.
RADIO: BEAM AND BROADCAST
RADIO: BEAM AND BROADCAST
CHAPTER I
THE PAST TO 1912
IN connection with patents of invention, there is a some-
what commonly used metaphor to the effect that one cannot
get a patent on the use of an umbrella to keep off the sun.
This, however, cannot be said to apply to the radio art; for
instance, J. A. Fleming was awarded a perfectly good patent
on the application to radio of a well-known effect and
instrumentality; and H. H. C. Dunwoody secured an
equally good one on the similar application of a hitherto
unsuspected property of carborundum. In each case the
invention was of a high order of commercial utility, since
the former led to one of the greatest developments in the
evolution of the art, while the latter sustained the art
during one of the most needy periods of its application to
commerce, and is still in extensive use. (See pp. 32 and
36 respectively.)
The evolution of radio has been characterized by
comparatively few original inventions of outstanding merit
and commercial utility; and by fewer still that, for one
reason or another, have found any practical application,
until they were about ten years old. Moreover, the
borrowings from other arts have been all too few and tardy.
In this chapter we will endeavour to note in chrono-
logical order th'e discoveries and inventions which are
more or less strictly relevant to the present state of the
art; omitting those which have or had no important
practical application, regardless of their academic merit.
1678
Christian Huygens, a Dutch mathematician and
physicist, propounded the undulatory theory of light (2).
17 B
18 Radio: Beam and Broadcast
1843
Professor Joseph Henry communicated to the American
Society that he had succeeded in magnetizing needles at
a distance of 220 feet (1).
1867
Ruhmkorff perfected the " Ruhmkorff coil " (2), which
thirty-five years later was used almost exclusively in
wireless stations.
James Clerk-Maxwell propoundedxthe electro-magnetic
theory of light (1). This theory confirmed and extended
that of Huygens, and was supported by mathematical
proofs which form the basis of radio-engineering to-day.
1879
Professor D. E. Hughes, of London, gave a private
demonstration of the transmission and reception of radio
signals up to a distance of about sixty feet. 1 Those
present were W. H. Preece, Sir Win. Crookes, Sir W.
Roberts- Austen, Professor W. Grylls Adams, and Mr. W.
Grove. Early in the following year Professor Hughes gave
a similar demonstration to a professor of Cambridge, who
stated that all the phenomena could be explained by known
electro-magnetic induction effects. This so discouraged
Hughes that he decided not to publish the results of his
experiments until he was in a position to prove that he
was making use of hitherto unknown phenomena. Con-
sequently, his experiments were not made public for many
years; meantime the phenomena had been identified by
others, and commercially applied by Marconi. In 1899,
in commenting on Hughes' work, Sir Win. Crookes said,
11 It is a pity that a man who was so far ahead of all other
workers in the field of wireless telegraphy should lose all
the credit due to his great ingenuity and prevision " (1)
1 It is recorded that Hughes succeeded in signalling over several
hundred yards.
The Past to 1912
19
(10a). In later years Hughes might have had recognition
of his work, but he resolutely refused (lOc).
1883
Professor A. E. Dolbear, of Boston, evolved a system
in which he proposed to use an elevated aerial, earthed
through the secondary of a Ruhmkorff coil, having a
telephone transmitter and battery
in series with the primary. He also
proposed in 1886 to elevate his
aerial by means of a kite and to put
a Morse key, instead of a telephone
transmitter, in the primary circuit
(1) (see U.S. Pats. 350,299 and
355,149, which were acquired
by the United Wireless-DeForesl-
Company) (23).
Thomas A. Edison, of New
Jersey, applied for an American patent on a diode for use
in the voltage control of electric lighting systems. (U.S.
Pat. 307,031. See Appendix, p. 143.) This invention
caused considerable scientific interest, but does not seem
to have had much practical application. (See Proc. Royal
Society, London, Vol. xlvii, 1889-90, p. 118, J. A.
Fleming.) (Fig. 1.)
1885.
T. A. Edison proposed the use, in an inductive system
of wireless telegraphy, of an elevated and earthed aerial
for land stations, and an inverted and earthed " L " aerial
for ship stations. (Fig. 2a, 6, c.) (U.S. Pat. 465,971.)
He also proposed the use of balloons covered with conduct-
ing foil and connected through transmitting or receiving
apparatus to earth. (Fig. 2d.) This invention was
acquired by the Marconi Company in 1903 (28).
FIG. i.
Edison's Patent on a Diode
for use in the Voltage
Control of Electric Light-
ing Systems (1885).
20 Radio: Beam and Broadcast
1888
Professor Rudolf Heinrich Hertz, a German, demon-
strated experimentally the possibility of creating electro-
magnetic waves in the ether, and confirmed their identity
with those, which according to Clerk-Maxwell's theory,
were the conveyors of light. Apparently Hertz was
unaware of Hughes' earlier experiments with a microphonic
detector and a telephone, because he (Hertz) used for a
detector a simple metallic loop containing a minute spark
gap. Hertz succeeded not only in detecting the waves,
but in measuring their velocity and length. He also
demonstrated that they were capable of reflection, refrac-
tion and polarization (6).
1890
Professor Edouard Branly, of Paris, found that a
" coherer " was a detector of Hertzian waves. The
" coherer " effect had previously been noted and com-
mented on by others, and it had been used by Hughes in
his unpublished experiments of 1879. Although it was
known at this date that the filings or granules could be
decohered by tapping, no automatic provision seerns yet
to have been made to this end; and it was not until 1897
that Lodge disclosed that when used with a telephone, a
filings "coherer" did not require to bo tapped. 1
It is related that, in the course of some experiments to
ascertain the conductivity of an iron chain under various
degrees of tension, Branly rioted sudden current rises, for
which there was no apparent reason. In the course of
his inquiries for the cause, he discovered that in another
part of the building a person was making simultaneous
experiments with a Ruhmkorff coil, and that as we would
now expect there was a current rise in the chain each
time the coil came into operation. The writer has not
1 See p. 130.
(4)
fig. 2 (a t *, c t <f). Edison'* Inverted and Earthed "L" Aerial (1885).
22 Radio: Beam and Broadcast
been able to verify this story. (Branly received the Nobel
Physics Prize in 1921 for his researches in Radio.)
Professor (now Sir) Oliver Lodge published the results
of his researches and experiments in electrical resonance
or syntony, and explained that a closed oscillatory circuit
was a feeble radiator and a feeble absorber (5). 1
1892
In the course of a paper in the Fortnightly Review, in
February, Sir Wm. Crooks said, " Rays of light will not
pierce through a wall, nor, as we know only too well,
through a London fog; but electrical vibrations of a yard
or more in wave-length will easily pierce such media,
which to them will be transparent. Here is revealed the
bewildering possibility of telegraphy without wires, posts,
cables, or any of our present costly appliances. Granted
a few reasonable postulates, the whole thing comes well
within the realms of possible fulfilment. At present
experimentalists arc able to generate electric waves of any
desired length, and to keep up a succession of such waves
radiating into space in all directions. It is possible, too,
with some of these rays, if not with all, to refract them
through suitably shaped bodies acting as lenses, and so
direct a sheaf of rays in any given direction. Also an
experimentalist at a distance can receive some, if not all,
of these rays on a properly constituted instrument, and by
concerted signals messages in the Morse code can thus pass
from one operator to another. ... At first sight an objec-
tion to this plan would be its want of secrecy. . . . This
could be got over in two ways. If the exact position of
both sending and receiving instruments were known, the
rays could be concentrated with more or less exactness on
the receiver. If, however, the sender and receiver were
moving about, so that the lens could not be adopted, the
1 See also Appendix, p. 126.
The Past to 1912 28
correspondents must attune their instruments to a definite
wave-length, say, for example, fifty yards. . . . Even
now, indeed, telegraphing without wires is possible within
a restricted radius of a few hundred yards, and some years
ago I assisted at experiments where messages were trans-
mitted from one part of a house to another without an
intervening wire by almost the identical means here
described." * (A similar suggestion is reported to have
been previously made by Professor R. Threlfall, of Sydney,
N.S.W.) (1).
Professor Elihu Thomson, of America, applied fop a
D 1
O
Fig. 3. Elihu Thomson (1892).
patent on an arc method of producing high-frequency
currents. His invention incorporated a magnetic blow-
out and other essential features of the arc of to-day, but
the electrodes were of metal and not enclosed in a gas
chamber. (See U.S. Pal. 500,630, Appendix, p. 175.)
(Fig. 3.)
1893
Nikola Tesla lectured before the Institution of Electrical
Engineers in London, on " Experiments with Alternate
Currents of High Potential and High Frequency," wherein
he disclosed ways and means of generating the currents
that were required for radio-telegraphy (4).
1 See p. 18.
24
Radio: Beam and Broadcast
1894
Professor Oliver Lodge transmitted and recorded
signals across a distance of sixty yards (10a).
1895
Professor A. S. Popoff, of Russia, used a coherer in
series with an elevated aerial and ground, with a recorder
in shunt with the coherer,
for the purpose of studying
natural electro-magnetic
wa v es or * ' atmospherics . ' '
His coherer was fitted with
an automatic tapper. Com-
menting upon his experi-
ments (in December, 1895)
he said : " 1 entertain the
hope that when my appar-
atus is perfected it will be
applicable to the transmis-
sion of signals to a distance
by means of rapid electric
vibrations when, in fact, a
sufficiently powerful gener-
ator of these vibrations is
discovered" (1). (Fig. 4.)
1896
In June, Professor Ernest Rutherford, of Cambridge,
succeeded in receiving signals over a distance of half a
mile. In place of a coherer he used a magnetic detector
of his own invention (1).
In the same month Guglielmo Marconi filed an applica-
tion for a patent * (British) on an invention whereby
* P. 116.
Fig-. 4.
Popoff's Receiver (1895).
The Pastto 1912
25
" electrical actions or manifestations are transmitted
through the air, earth, or water by means of electric
oscillations of high frequency." The provisional specifica-
tion which accompanied the application dealt chiefly with
modifications in the Ruhmkorff coil, the coherer and
coherer circuits, and associated tapper. For the " greatest
possible distance " of communication, it recommended the
use of reflectors at the transmitter and receiver.
In September, Nikola Tesla filed an application for a
British patent on " Improvements relating to the Produc-
A.C.
Fig. 5. Testa's Improvements (1896).
Dotted lines indicate application to Radio about a decade later.
lion, Regulation arid Utilization of Electric Currents of
High Frequency, and to Apparatus therefor," the latter of
which included the synchronous rotary discharger. The
application was accepted on the 21st November, where-
upon was disclosed a method of producing radio-frequency
oscillations, which was the most approved for twenty
years. (Br. Pat. 20,981/96.') (Fig. 5.)
(NOTE. In this year, also, Professor C. W. R6ntgen
discovered the X-Rays.)
1 See Appendix, p. 198.
26 Radio: Beam and Broadcast
1897
Marconi filed (in March) the complete specification of
his invention of 1896. The specification is largely taken
up with particulars of modifications in the coherer and
other details, but the part which is of chief interest is
that which refers to the use of an elevated aerial, earthed
at one end. In this connection, the specification says :
" The larger the plates of the receiver and transmitter, and
the higher from the earth the plates are suspended, the
greater is the distance at which it is possible to com-
municate at parity of other conditions." This does not
quite conform with the provisional specification filed in
1896 nine months previously; and, no doubt, it indicates
the results of experiments which had been made in the
interim. Further on, the specification reads : " Balloons
can also be used instead of plates or poles, provided they
carry up a plate or are themselves made conductive by
being covered with tinfoil. As the height to which they
may be sent is great, the distance at which communication
is possible becomes greatly multiplied. Kites may also
be successfully employed if made conductive by means of
tinfoil." The actual use of an aerial, elevated at one end
and earthed at the other an earthed vertical oscillator
marked the beginning of great progress in the art.
(Br. Pat. 12,039/96;' U.S. Pats. 586,193, and re-issue 2
11,913.)
In May, Professor Oliver Lodge filed an application for
a patent on " Improvements in Syntonized Telegraphy
without Line Wires," the main feature of which was the
provision of means whereby the frequency of the trans-
mitter and receiver could " be verified with ease and
certainty." The complete specification was filed on the
1st of February, 1898. This invention was regarded as of
1 See Appendix, p. 116.
* The lire of a " re-issue " terminates with that of the original patent.
The Pastto 1912 27
such outstanding merit that, in 1911, when the British
patent thereon was due to expire, it was (in part and con-
ditionally) extended for a period of seven years a unique
distinction in the history of the art. Upon its extension,
the patent was acquired by the Marconi Company, which
fact was undoubtedly conducive to a more general recogni-
tion of its merits. For instance, in 1916, Fleming says :
" Sir Oliver Lodge stated clearly, in a fundamental patent
applied for in 1897, the right conditions for conducting
syntonic radio-telegraphy
and for isolating stations, f /
and the necessity for the ^ '
employment of trains of
feebly damped waves "
(4). Whereas, in 1907, _____
he said that, "The full . I... i
scientific explanation of s**v 5>
these principles, covering f ^ ^ <^
what is called syntonic f \ \
-o o
telegraphy or the tuning
of electrical circuits, were
fully given long before
the date of Sir Oliver
Lodge's 1897 British
Patent. For example, Fig. 6. Lodge's Patent (1897).
they were fully set out <" A " primarily for charging purptic " )
in two papers published in 1895 in Germany by
Oberbeck (Wiedemann's Annalen, Vol. xxv, p. 63)
and by Bjerknes (Wiedemann's Annalen, Vol. Iv,
p. 21)." Further, in the same early statement, Fleming
tells us that apparatus which he had made in accordance
with Lodge's specification failed to work, " while that
made in accordance with Marconi's worked perfectly/'
The apparatus referred to was being demonstrated in
Germany in 1900 before the officials of the German Patent
28 Radio: Beam and Broadcast
Office by Professor Fleming on behalf of the Marconi
Company (16). If Fleming's citations were relevant to
Lodge's invention of 1897, they must have been even more
so to Marconi's of 1900; moreover, they give a greater
significance to the earlier inventions of Braun. 1
In the same reference, Professor W. II. Eccles has said :
" During the years between 1896 and 1910, Marconi, aided
by Lodge's invention of the tuning coil, carried wireless
telegraphy substantially to its present (1922) form" (10a);
while Professor G. W. O. Howe has said of this invention
that " it shows a remarkably clear insight into the problem
of tuning and selectivity. It constitutes a great advance
on Marconi's patent of the previous year " (lie).
As instancing the basic
nature of the invention, it
may be mentioned that the
British Admiralty have re-
cently been condemned by
Lord Moulton, as Arbitrator,
to pay compensation in the
nature of royalty to the
Fig. 7. patentee thereof, on the
Lodge's Loud Speaker (1898). basig of uger throughout the
whole period of the life of the patent twenty-one years.
This patent, therefore, has the further distinction of being
the earliest British Patent, relating to syntonic radio, to be
so confirmed as of a basic nature. (Br. Pat. ll,575/97; 2
U.S. Pat. 609,154.) (Fig. 6.)
1898
In the complete specification of the invention last
referred to, Lodge pointed out that it was not necessary
to have a spark gap in the aerial circuit. He also disclosed
1 p. 29.
2 Bee Appendix, p. 124.
The Past to 1912 29
or the first time, a receiver inductively coupled to the
serial circuit.
In the same year, Lodge invented a Loud-speaker, using
the now well-known device of a coil connected to a
iiaphragm and floating in a strong magnetic field. (Br.
Pat. 9,712/98). (Fig. 7.)
1899
S. G. Brown obtained a patent on a method of direc-
tional transmission and reception. The method involved
the use of two aerials, a func-
tion of a wave-length apart, V
which aerials might be looped
together. The specification
also disclosed the use of a
rotary interrupter, whereby a
musical note would be ob-
tained. 1 (Br. Pat. 14,449/99.)
Ferdinand Braun obtained
patents on a transmitter de-
signed to radiate longer waves
than those radiated by the
Righi or usual type of oscil-
lator. To this end he pro-
posed a closed oscillatory
circuit, containing Leyden jars
and induction coils, induc-
tively coupled to a radiating
circuit. This use of coupled Fig. 8.
Circuits in the transmitter Braun s Transmitter (1899).
constituted a very important advance, but Braun did not
specifically claim it, or he could have held the whole art
to ransom. (Ferdinand Braun, who shared the Nobel
Prize with Marconi in 1909, died in Brooklyn in 1918.)
1 As it would by Edison'n device of 1885. See p. 21.
30
Radio: Beam and Broadcast
(See Br. Pat. 1,862/99; German 111,578/98; also Br. Pat.
22,020/99. ') (Fig. 8.)
1900
In April, Guglielmo Marconi applied for a patent on
an invention which comprised practically all that was in
the 1897 invention of Lodge
and the later inventions of
Braun, and a little more. At
the transmitter, he employed
separate oscillating and radi-
ating circuits, coupled to
each other; and at the
receiver, separate absorbing
and oscillating circuits
similarly coupled; all cir-
cuits being tuned to the
same frequency or har-
monics of that frequency,
and (inferentially) suffici-
ently loosely coupled to en-
able them to oscillate in
resonance. This patent was
made the basis of several
successful infringement
Fig. 9.
Marconi's Patent (1900).
suits, and when it was strengthened by the acquisition of
Lodge's 1897 patent it gave the Marconi Company for a
time almost a monopoly of syntonic wireless telegraphy
in England and America. (Br. Pat. 7,777/00; 2 U.S.
763,772.) (Fig. 9.)
William Du Bois Duddell, of London, applied for a
patent on a static method of generating alternating currents
from a direct-current supply, which method followed very
1 See Appendix, p. 132.
9 See Appendix, p. 134.
The Past to 1912 81
closely upon the lines of that of Elihu Thomson of 1892.
Duddell suggested electrodes of carbon, but he proposed
no magnetic blow-out. He stated that his invention could
be used for producing oscillations of high frequency and
constant amplitude, which could " be used with advantage
in wireless telegraphy/ 1 especially where it was " required
to tune the transmitter to syntony." Duddell's invention
(Br. Pat. 21,629/00 *) became the basis of the Poulsen Arc,
and also of an interesting transmitter evolved by Von
Lepel.
1902
G. Marconi invented an improved form of magnetic
detector (Br. Pat. 10,245/02). This detector constituted a
great advance on the coherer, and it had a wide application
until the advent of the Fleming Valve (Diode), the Crystal
and Electrolytic Detectors.
R. A. Fcsseiidcn was awarded a patent covering broadly
the voice modulation of " practically " continuous waves.
(U.S. Pat. 706,647; Br. Pat. 17,706/02.)
1903
Valdemar Poulsen, of Copenhagen, successfully applied
for a patent upon a generator, as disclosed by Duddell in
1900, plus the magnetic blow-out proposed by Thomson in
1892, and a hydrogenous vapour in which to immerse the
arc. (Br. Pat. 15,599/03; 2 U.S. Pat. 789,449.) Reference
will be made later 1 to this invention, which was not com-
mercialized for some years. (Fig. 10.)
R. A. Fessenden invented the method of telegraphing
1 See Appendix, p. 177.
a See Appendix, p. 180.
8 See p. 75.
82
Radio: Beam and Broadcast
by changing the frequency of the transmitted wave.
(Br. Pat. 28,290/03.)
1904
On January 15th Dr. A. Wehnelt obtained a German
patent (No. 157,845) on a two-electrode vacuum tube
rectifier of alternating currents. The filament or cathode
of Wehnelt's device was coated with oxide, similar to those
W
v/
JJ.C.
L J .
) ; ijar. 10. Poulsen Arc Generator (1903).
Showing * : coupled circuit," re-introduced in 1924.
incorporated in the inventions of Von Lieben in 1911 l and
Franklin in 1913 2 (15).
On November 16th Professor J. A. Fleming, of London,
applied for a patent on the use, in connection with radio,
of a vacuum valve or diode very similar to that described
by Edison in 1883. According* to his specification,
Fleming had " discovered that if two conductors are
enclosed in a vessel in which a good vacuum is made, one
being heated to a high temperature, the space between the
hot and cold conductors possesses a unilateral electric
J See p. 45.
1 See p. 158.
The Past to 1912
83
conductivity." While it is true that Edison was making
use of the limited rather than the unilateral conductivity
of the gaseous path, there is evidence both in the preamble
and the claims of his specification that he was aware
of the asymmetry of the
conductivity; moreover, the
property had been publicly
discussed long before 1904 by
Fleming and others, including
Elster and Geitel.
As disclosed by Fleming's
specification, the diode was
not a very satisfactory detector.
Its importance lay in the fact
that it was one step in the
evolution of the triode rather
than in its own utility. The
Fig. n.
Fleming's Diode (1904).
patents on the diode became the property of the Marconi
Company, and after the specification of the British Patent
had been amended by disclaimer 1 an unsuccessful attempt
was made to secure an extension. (Br. Pat. 24,850/04; 3
U.S. Pat. 803,684.) (Fig. 11.)
1905
R. A. Fessenden, of America, applied for a patent on a
" beat " or " interference " method of detecting continuous
and other Hertzian waves. The invention provided a
method, rather than an instrumentality, and there being
few, if any, continuous-wave stations then in commercial
operation, little use w r as made of it for some time. Never-
theless, the invention was undoubtedly one of the most
meritorious in the history of radio, and it now has a very
wide application. (U.S. Pals. 1,050,441 and 1,050,728,
1 The U.S. specification was similarly amended.
a See Appendix, pp. 144, 146-7.
84 Radio: Beam and Broadcast
granted in 1913; Br. Pat. 6,203/07. See also U.S. Pat.
1,141,717 to Lee and Hogan in 1915; Br. Pat. 24,458/13.)
G. Marconi applied for a patent on an inverted " L "
aerial. The directional property of this aerial, which,
according to the specification, was equally pronounced in
transmitting and receiving, has been acclaimed by Fleming
and many others. (This, by the way, is not to be con-
fused with the " Marconi Beam.") The specification states,
" This receiver may be used with great advantage to
determine the direction of a transmitter, say, for instance,
on a ship at sea," and explains that if " such an antenna
be swivelled about its detector end in a horizontal plane,
and signals be received with the antenna in a certain
position, the operator will know that the transmitting
station is in the line of the antenna; in other words, that
its tail end is pointing directly aAvay from the transmitting
station."
As to the directivity of this type of aerial for trans-
mission purposes, there seems to be a great conflict of
opinion; and despite what has been said to the contrary,
it appears that when such an aerial is high enough to be
an efficient transmitter, its directivity is negligible, except
perhaps when the ratio of distance to wave-length is very
small.
Such a directive aerial as Marconi claimed this to be,
would be invaluable for long-dislance point-to-point
stations, like those proposed for the British Imperial Chain.
However, the 1922 report of the Wireless Telegraphy Com-
mission (Technical) recommended for these stations
aerials of a symmetrical type (24).
T. L. Eckersley tells us that the directive effect of an
11 L " aerial " is a very small amount " and is almost entirely
destroyed when the earth screen is used (76); while
Professor Fleming states that theory points to the fact that
" any bent oscillator, however arranged, has no asymmetry
The Past to 1912 85
of radiation for very large distances " (3). However, in
The Times Engineering Supplement of March, 1919 (some
years later), Fleming tells us that such a directional aerial
" is now generally employed in long-distance high-power
stations which are intended to communicate with a
corresponding distant power station," and that it radiates
most strongly in its own plane and away from its open
end.
Marconi further points out in his specification that,
while aerials of this type are preferably earthed only at
one end, " they may be connected to earth at their tail ends
Fig. 12. Marconi's Inverted " L" Aerial (1905).
or at other points, and inductances and condensers may be
inserted in these earth connections." (Fig. 12.) This,
as has been pointed out by Mr. E. H. Shaughnessy, of the
British Post Office, constitutes a pretty full disclosure of
the multiply-tuned aerial, which was later patented to
Alexanderson 1 (76); but according to C. S. Franklin (7c)
when " correctly adjusted as regards phase " such an
aerial radiates most strongly in a direction at right angles
to its length, which is not in accord with the Marconi
claims.
In the circumstances, one is not disposed to quarrel
with Professor Howe's statement that the action of this
> Br. Pats. 130,064, 142,610- U,S, Pate. 1,300,167/8,
36
Radio: Beam and Broadcast
Marconi directional aerial is very complex (lie).
(Br. Pat. 14,788/05. See also Br. Pats. 3,127/06 and
20,230/09.)
A British patent was awarded
to W. P. Thompson, as agent
for a German firm, on a flat-top
aerial with duplicate couiiter-
poise. (Br. Pat. 14,221/05.)
(Fig. 13.)
Professor Max Wien, of Ger-
many, invented the quenched gap
discharger 1 (Br. Pat. 5,455/05)
which is now being increasingly
used to replace the rotary dis-
charger of Tesla. (Max Wien
received the INobel Prize for
Fig. 13-
Counterpoise Aerial (1905).
Physics in 1911.)
1906
H. H. C. Dunwoody, of Washington, D.C., invented
the carborundum detector and secured a broad patent
covering the use, as a detector, of a non-metallic crystalline
material. This detector is still very popular, and deserves
to be even more so, as it is by far the most simple and
reliable for local broadcast receivers. Prior to the advent
of the triode, the only serious competitor of carborundum
in commercial use was the electrolytic detector, and the
former was in far greater favour. Even to-day,
carborundum is often used in conjunction with triodes,
and it is very effective for short-distance reception, even
when used without a " B " battery. (U.S. Pat. 837,616;
Br. Pat. 5,332/07.)
G. W. Pickard, of Amesbury, Mass., invented the
silicon detector and an efficient way of mounting all
1 What was practically a quenched gap was patented to T. B. Kin raids
of Boston in 1899. (U.&. Pat. 623,316/99; Br. Pat. 5,518/99.)
The Past to 1912
87
i
Fig-. 14.
De Forest (1906).
"B" Uattery.
crystals. Silicon has one advantage over carborundum,
in that it is used without a " B " battery, but it is less
stable than carborundum. (U.S. Pats. 836,531, 877,451
and 13,798 (re-issue 1914);
Br. Pal. 18,842/07.) The U.S.
re-issue (expired) referred to
above, was especially impor-
tant because it covered the
practice of embedding a recti-
fying member in a readily
fusible metal.
Lee de Forest applied for
a patent on the use of a
" B " battery in connection
with a diode, according to
Fig. 14. (Br. Pat. 5,258,
March 3rd, 1906; U.S. Pat.
824,637.)
In the following October, De Forest applied in America
for another patent on a triode " for amplifying Feeble
Electrical Currents."
Figs. 15 and 16 (redrawn)
are taken from the speci-
fication of this invention,
and represent a received
signal amplifier and an
input telephone amplifier
respectively. (U.S. Pat.
841, 387. ') According to
the specification of this
invention, in which, by
the \vay, is made the first
proposal to use a metal filament, De Forest assumed that
it functioned by reason of the relative movement of the
1 Expired January 15th, 1924. See Appendix, p. 148.
De Forest's Triode Amplifier (1906).
Metal^ Filament.
88 Radio: Beam and Broadcast
electrodes under the influence of the currents to be
magnified. In the course of legal proceedings in 1916,
the American Marconi Company admitted infringement
of this patent (15).
In this year Ferdinand Braun disclosed how a heart-
shaped polar radiation diagram could be obtained by a
combination of aerials (7).
1907
Lee de Forest invented the triode detector (Fig. 17)
(U.S. Pat. 879,532; 1 Br. Pat. 1,427/08), which, like its
thermionic predecessors,
created little interest and
had little bearing on the
art for several years.
Ultimately, however, as is
well known, the applica-
\J lion and development of
Fig. 16. the triode revolutionized
De Forest's Telephone Input Amplifier radio and created a new
technique. It rendered
many other promising inventions more or less abortive,
and caused many thousands of pounds worth of apparatus
to be discarded. On the other hand, it provided an
instrumentality for putting into practical effect other
inventions of importance, such as, for instance, Fesseriden's
" interference " receiver. 2
In 1911 or 1912, when there became due the first
renewal fee on this British de Forest Triode Patent, that
fee was not forthcoming, and the patent lapsed. However,
as proprietors of the diode patent, granted to Fleming, the
British Marconi Company had control of the situation in
1 Expires February 18th, 1925. See Appendix, p. 151.
3 See p. 33.
The Past to 1912 80
the United Kingdom until 1918, and they would have
continued their control had they not been unsuccessful in
their attempt to secure the extension of Fleming's patent.
In 1916 the American Marconi Company admitted
infringement of this patent (U.S. 879,532 to De Forest)
also (15); nevertheless, there has been much controversy
even in some text-books relating to the value of De
Forest's contributions to the evolution of the triode. It
has been said that he did not understand the theory of his
invention; why or how it functioned as it did. There may
Fig. 17. De Forest's Triode Detector (1907).
be some evidence to support this contention, but what does
it signify? With the exception of the specifications of
inventions of men like Lodge, Pupin, Elihu Thomson and
Duddell, there are few, not of a purely mechanical order,
that do not indicate some such lack of understanding.
One prefers not to direct attention to examples, but they
abound in connection with any new art.
It may be pertinent here to quote a few expert and
disinterested opinions on the merit of De Forest's invention.
W. R. Cooper, when editor of The Electrician, London,
said : " In the field of radio-telegraphy Professor Fleming's
valve receiver introduced an important principle. An
40 Radio: Beam and Broadcast
extension of work in this direction by Dr. de Forest led
to the audion receiver, and thence to the audion amplifier.
The latter bids fair to play an important part in telephony,
and has already rendered it possible to transmit speech
across the Atlantic by radio-telephony/' (In the same
publication, in an article devoted to radio-telegraphy,
Professor Fleming concedes that the Fleming valve, " in
certain forms," is more sensitive than the magnetic
detector; and that " much work has been done in the
United States in devising forms of thermionic detectors,
all of which are lineal descendants of the Fleming valve ")
(4). This was published in 1916.
Professor Howe says : " No single invention has done
more to revolutionize radio-telegraphy than that of the
audion. Little did Dr. de Forest imagine, when he placed
a control electrode first on the outside of the bulb of a
Fleming valve and then inside the bulb as a grid between
the anode and cathode, that he was making the most
important step in the whole history of radio-telegraphy,
but such was the case no one can now have the slightest
doubt." This is taken from the (Marconi) Year Book for
1921, in which are biographical notes of both Fleming
and De Forest. Of the former we read that he was
responsible for " a pioneer invention of unusual utility,
and one that has enormously aided the development of
wireless telegraphy," with which we agree; but no inven-
tion is credited to the latter which is hardly fair.
After making some less flattering comments on the
inventions of De Forest, Professor J. H. Morecroft of New
York, writing in the Radio Broadcast of August, 1922,
says : " It is to be pointed out, however, that little as De
Forest contributed to an explanation of his device, the thing
which he actually did, namely the insertion of the third
electrode into a Fleming valve, was a most wonderful
contribution to the radio art. As a matter of fact, in the
The Past to 1912 41
opinion of the writer, this was the most important single
step in the whole development of radio communication.
Let us give De Forest credit for this wonderful achievement,
even though he was so reluctant to give credit to the other
workers in the field, principally Fleming, on whose work
the possibility of the audion depended."
With regard to Professor Morecroft's last statement
quoted above, it appears that there has been some
reciprocity. Moreover, in fairness to De Forest, it should
not be overlooked that he also originated the metal
filament, the essential " B " battery, and the use of a con-
denser in series with the grid for detection. 1 In short, he
may be said to have advanced the Fleming valve as much
as Fleming advanced Edison's device of 1883. The com-
mercial importance of the invention may be judged from
the fact thai, according to a report of the U.S. Federal
Trade Commission, the Radio Corporation of America
received orders for 2,931,262 tubes (triodes) in the first
nine months of 1923.
It is timely and relevant here to note that on the 12th of
January, 1907, C. Marconi filed an application for a patent
on the use of an induction coil (10") as a step-down trans-
former in the plate circuit of a carbon filament Fleming
valve still without a " B " battery. (Br. Pat. 887/07.)
(Fig. 18.) This, Fleming characterized as " one of the best
long-distance receivers for electric waves yet devised," and
added, " This glow lamp detector has been much used by
Lee de Forest, disguised under the name of an audion, and
claimed as his own invention " (3). If the reader will refer
to the specification of De Forest's British Patent 5,258/06,
he will read that, " The present application, therefore, does
not cover broadly the employment of these ionized media
as detectors, but it has been found by the present inventor
1 The simple grid-leak is also credited to De Forest (19). See U.S Pat.
1,377,405; Br. Pat. 100,358(?).
42
Radio: Beam and Broadcast
that in order to obtain satisfactory working it is necessary
that there shall be included in the circuit of the ionized
medium a local E.M.F. . . ." which Marconi's invention
lacked.
Etlore Bellini and Alcssandro Tosi evolved a very simple
and effective system of directional radio, which was of
immense use to Britain and her allies during the Great War.
H. J. Round, who was very largely responsible for its
successful application, says of it: "The Bellini-Tosi idea
was so complete that one might say that all the work after
the original concep-
\/ lion consisted in
carrying out cor-
rectly the idea and in
the improvement of
> the receiving appar-
atus. The sensitive-
ness of the crystal,
although greater
than either the mag-
netic or electrolytic
detectors, still limited
pi l8 the ranges of recep-
Telephone Transformer, Marconi (1907). tion very greatly On
directional aerials " (7). This is also an interesting com-
mentary on the state of the detector art in 1912-14.
Some credit is due to A. Artom, of Italy, for the develop-
ment of the underlying principle of the direction-finder,
as may be gathered from the reference to the specifications
of his numerous patented inventions in connection there-
with.
The original Bellini-Tosi invention (Br. Pat. 21,299/07;
U.S. Pats. 943,960 and 945,440) did riot comprehend a
" sense " quality, which was not disclosed until the follow-
ing year by the same inventors. (Br. Pat. 4,801/09.)
.NOTICE TO MARINERS
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[To /c<: />gr 42.
ILLUSTRATING THE IMPORTANCE OF NON-MAGNETIC AIDS TO NAVIGATION.
The Past to 1912
48
(J. N. Maskelyne was the first to propose a triangular
aerial for directional transmission, but his aerial circuit
contained a spark gap and the secondary of an induction
coil. See Br. Pat. 7,983/00.)
Dr. A. Muirhead proposed some refinements in the use
of the aerial counterpoise, or earth screen, in place of an
"earth" connection. (Br. Pat. 11,271/07.) (Fig. 20.)
The earth screen has come into considerable use in recent
years, but its theory
was well developed over
a decade ago, particu-
larly by Zenncck (12).
British Patent23,090/04
to J. S. Stone is also
relevant.
R. A. Fessemlcn
proposed the dicta-
phone method of auto-
matic recording. This
method has been very
much used in trans-
Atlantic wireless tele-
graphy, and is only m , . , , . !'f* 20 * . , Q ,
to r J ' J M airhead's Aerial Counterpoise (1908).
now being superseded.
(Br. Pat. 20,005/08.) (Fig. 21.)
(NOTE. It was proposed by G. L. Ghisholm in 1908
to use a dictaphone as a line telephone recorder, the scriber
being attached to the telephone diaphragm. See specifica-
tion of Br. Pat. 9,800/08.)
1908
Professor J. A. Fleming filed an application for a
patent on the 25th of June, on a diode having a filament
of tungsten and a cylindrical plate of " copper or other
44
Radio: Beam and Broadcast
metal." On the 10th December following, he modified
this by changing the material of the cylinder to carbon.
He also made provision for the " B " battery effect, and
secured a patent on the combination on April 15th, 1909.
(Br. Pat. 13,518/08; U.S. Pal. 945,619.) (Fig. 22.) Such
a device never came into general use, and one is forced to
the conclusion that, despite the invention of the triode, the
diode at this time was still in an embryonic stage. (It
should be noted here that De Forest's application for a
British Patent 1,427/08 l on a triode having a filament
Fig. 21. Fessenden's Method of Automatic Recording (1908).
" preferably of metal " was accepted on April 30th, 1908,
and he disclosed a filament of platinum or tentalum in the
specification of his U.S. Pat. 841,387 2 of January 15th,
1907.)
1910
Professor R. A. Fessenden invented a two-tone method
of transmitting, whereby dots and dashes could be made
of equal length. As a method of economizing " line-time,"
this invention may yet have considerable application.
(Br. Pat. 2,617/11.)
1 See p. 38.
2 See Appendix, p. 148.
Marconi
m-
balancing-
The Past to 1912 45
1911
R. von Lieben, E. Reisz and S. Strauss demonstrated
that the triode could be used as a proportional relay of
radio-frequency currents. There is little doubt that it was
the reduction to practice of the triode by Von Lieben and
his associates which restarted triode evolution in other
countries. (Br. Pat. 1,482/11; U.S. Pat. 1,038,910.) The
use of a " C " battery effect is disclosed in the specification
of this patent.
G.
vented a
out method of
duplexing spark
stations, which
marked an important
step in the evolution
of spark telegraphy.
(Br. 4 Pat. 13,020/11.)
1912
According to a
judgment of the U.S.
Court of Appeals of
the District of
Columbia, dated May
5th, 1924, Dr. Lee de
Forest is to be credited
with the first inven-
Fig. 22.
Fleming's Diode (1908).
Tungsten Filament. Carbon Anode. " B " Battery Effect.
tion of the regenerative circuit of the triode on August 6th,
1912. The Appeal Court proceedings were on a long-fought
interference and not an infringement issue; and while they
were in progress the invention in question was made the
subject of many issued patents in different countries :
notably to Franklin in England (13,636/13), Armstrong in
America (1,113,149), and Meissner in Germany (291,604,
April 10th, 1913). The regenerative circuit is one that
46
Radio: Beam and Broadcast
involves a certain critical degree of coupling between the
two oscillatory systems of the triode, and this coupling may
be obtained by mutual inductance (as in Fig. 23), mutual
capacity, or mutual impedance, or by combinations thereof.
It is variously termed the regenerative, re-active, feed-back
or tickler circuit.
Fig. 23. Regenerative Circuit (1912).
The following is a copy of the judgment 1 :
" IN THE COURT OF APPEALS OF THE DISTRICT OF COLUMBIA
" . . . Before Smyth, Chief Justice; Robb and Van
Orsdel, Associate Justices.
" VAN ORSDEL, Associate Justice : This interference
comes here on appeal by the parties Langmuir, De Forest,
and Meissner, from the decision of the Commissioner of
Patents awarding priority to Armstrong, also appeals by
De Forest against Meissner and Langrnuir jointly, and
against Langmuir individually, for the invention set forth
in the following counts :
1 See U.S. Patent Office Official Gazette, VoL 324, p. 9&5, July 29th,
1924.
The Past to 1912 47
"'1. Means for producing sustained electrical oscilla-
tions comprising an oscillatory circuit having two
electrodes in an exhausted receptacle and a second circuit
coupled thereto having a conducting body interposed
between said electrodes/
" ' 2. Means for producing sustained electrical oscilla-
tions comprising an oscillatory circuit having two
electrodes, a second circuit coupled thereto having a
conducting body interposed between said electrodes,
and means for varying the frequency of the produced
oscillations/
" 3. The method of producing electrical alternating
currents which consists in causing current to flow in one
of two coupled circuits and varying the flow of current in
the first circuit by impressing the potential induced in the
second circuit upon a conducting body interposed between
two electrodes in the first circuit/
" The invention set forth in each of the applications is
concisely described in the opinion of the Commissioner as
follows : ' All the counts of all the issues involve the setting
up of small current variations in one circuit, creating
thereby corresponding variations in a second circuit, and
feeding back these second circuit variations inductively
into the first circuit to add their effect to the initial
variations, which latter, thus reinforced, create and form
greater variations in the second circuit, and these are, in
turn, also inductively fed back to the first circuit to still
further amplify the variations in such first circuit, and
these still further amplify those in the second circuit, and
so on. The energy of the variations in each circuit re-acts
upon and increases that in the other circuit until a
maximum sustained alternating current is finally produced,
whose frequency can be controlled by varying the electric
constants of the associated circuits/
" The whole case, as here presented, turns upon the
48 Radio: Beam and Broadcast
question of priority to be determined solely as a question
of fact. The Commissioner of Patents, affirming a
decision by the Board of Examiners-in-Chief, awarded
priority to the party Armstrong*. It may be stated at the
outset, that the voluminous record in this case is excep-
tionally free from contradiction or attempted impeachment
of witnesses. Indeed, the whole record may be accepted
as embracing a true statement of the facts involved in each
case.
" Especially are we impressed by the party Armstrong
and his witnesses. We have no doubt but what he
produced the invention at the time alleged, and did all
the things attributed to him by the testimony, as set forth
in this record. His earliest claim to a conception of this
invention is October, 1912, followed by a witnessed sketch
on January 31st, 1913. This date antedates any time
claimed by or available to either the party Meissner or
Langmuir. These parties, therefore, are eliminated from
further consideration.
" This narrows the case to De Forest and Armstrong. It
is clearly shown that De Forest was developing the idea
involved in this invention in the early part of 1912, and
it is claimed that the work culminated in a complete
disclosure of the invention in August of that year. If this
claim is sustained, De Forest must prevail.
" Coming, therefore, to De Forest's case, the Examiner
of Interferences found that in the experiment of August 6th,
1912, the repeating circuit used as an amplifier of
telephonic currents was modified by a connection between
the plate-filament circuit and the grid-filament circuit.
This resulted in the production of ' a beautiful clear tone.'
This, the witnesses have testified, was due to the audion
generating oscillations or alternating current due to the
feed-back action and was understood by them at the time
of the experiment. This, it is believed, establishes the
The Past to 1912 49
fact that De Forest had a conception of the invention at
that time, August 6th, 1912, and that it was disclosed
to others. The Board of Examiners-in-Chief after review-
ing the testimony held that they were ' not fully satisfied
that De Forest really had a conception of his invention in
August, 1912.'
" The Assistant Commissioner reviewing the De Forest
case, and the experiments made in August, 1912, held that
' it must be conceded this circuit diagram of August 6th,
1912, shows such an arrangement, that if the constants
were proper, sustained alternating currents of oscillations
would be produced. It is believed, further, the making
of the diagram and the production of the " beautiful clear
tone " by the apparatus connected up according to such
diagram have been fairly proved by the evidence, and
that, therefore, such apparatus embodied the issue of this
interference. The authenticity of the note-books and
diagrams and the proofs as to their dates, as well as the
production of the beautiful clear tone at the time alleged,
have not been seriously controverted. Clearly the
production of the tone was accidental, but this is not of
moment. Did De Forest understand what was done, that
the tone was due to the feed-back coupling relation, and
could he reproduce the tone at will ? De Forest states that
he understood what was taking place, and both Logwood
and Van Etten corroborate him, but he has introduced no
record to support this oral testimony given many years
afterwards/ He then holds that the failure of De Forest
to proceed after August 6th, 1912, with the feed-back
circuit until after Armstrong had reduced to practice,
entitled Armstrong to priority.
" It will be observed that the Assistant Commissioner
in effect holds that what De Forest did in August, 1912,
amounted to a reduction to practice, but that after reducing
the invention to practice he abandoned it. In patent law
D
50 Radio: Beam and Broadcast
abandonment after reduction to practice is a proposition
somewhat difficult of demonstration. At best, however,
abandonment under such circumstances is a matter of
proof and not of assumption. We think De Forest's
record will neither sustain the charge of abandonment nor
lack of diligence. The Assistant Commissioner attempts
to support his conclusion on the theory that while De Forest
unquestionably made this important discovery he did not
recognize how the effect was obtained nor did he possess
knowledge of how to reproduce it, and that such know-
ledge, accompanied by simultaneous or subsequent utiliza-
tion of it in a manner essential to carry out its intended
function, is necessary to take the production or discovery
out of the class of abandoned experiments.
" De Forest was the inventor of the epoch-marking
invention the audion, which he patented both as an
amplifier and as a detector. Prior to 1912 he had devoted
much of his time to experiments on the audion and to the
various uses to which it might be put. At the time he
discovered the oscillating audion he was investigating
telegraphone recording; the telephone two-way repeater and
the amplifier for wireless work. It appears from his note-
book records that the first discovery of the feed-back circuit
for producing oscillations occurred in connection with his
work on the amplifier for wireless and telephone two-
way repeater work. There is some testimony, principally
from memory, by De Forest and his corroborating wit-
nesses, Van Elten and Logwood, that prior to August, 1912,
the oscillating properties of the audion were discovered. It
is unnecessary, however, to go behind the written records
of August 6th, 1912. This record, with the accompanying
irawing, which was made by Van Etten, who was working
under the direction of De Forest, clearly shows a feed-back
circuit. It also discloses that when connected up it pro-
iuced oscillations evidenced by ' a beautiful clear tone.'
The Past to 1912 51
" The notes and diagrams made by Van Etten on
August 6th, 1912, were not copied into the De Forest
record book, but it was followed by more complete
demonstrations on August 29th, 1912, of which a full and
complete record was made by Van Etten in the De Forest
record book. The notes indicate that the circuit was tested
for amplification with successful results. It is also noted,
that reversing the connection to the secondary winding
(? of the) coil, all sorts of musical notes were produced in
the Brandes phones, and that when the connections are
reversed the musical notes, whistle, etc., disappear, and
the ticks come through as before. There is no question,
both from the disclosure and the testimony of the
witnesses, that the circuit produced oscillations of audio
frequencies evidenced by the tones in the receiver, the
pilch of which could be varied by small changes in the
constants of the circuit. While some question is raised
as to whether the oscillations were produced by coupling
of the circuits of the audion or by means not covered by
the issue, we think there can be no question from the
evidence supporting the disclosure that the oscillations
were produced by coupling of the audion circuits.
" We think the drawing and notes made by Van Etten
in August, 1912, clearly disclose the invention as well as
the results obtained. The notes trace from the diagram
the successful results culminating in the production of
the alternating currents. This is not the character of
invention where one skilled in the art can draw a diagram
and from mere observation theorize a result. No one
could even guess how the audion would act in the circuit.
It contained an undisclosed secret, an undiscovered
phenomenon, which could only be revealed through an
actual test. We think the notes contained a complete
record of the invention in issue as well as the results
obtained. This marvellous invention was not such a thing
52 Radio: Beam and Broadcast
as would likely be forgotten by those who witnessed its
discovery. Nor does the testimony of the witnesses
support either the conclusion that it was cast aside and
forgotten, or that their understanding of it was too meagre
to permit of its reproduction.
41 Indeed, it is conceded, by the opposing parties, that
the circuit arrangement, as shown in the record of August
6th, 1912, is a feed-back circuit. It is further clearly
shown that oscillations were produced and that the
oscillations were produced because of the feed-back circuit.
Van Etten testified that the purpose was ' to demonstrate
that the audion would amplify minute currents and would
be useful primarily in wireless work/ He further testified
that the experiment with the audion as an amplifier was
deliberately made ' with the expectation and intention of
making the audion sing or produce various musical notes
and alternating currents.' He also testified that the work
was done under the general direction of De Forest, and
' that he was acquainted with the progress of the work.'
Speaking of the note-book record, Van Etten said : ' The
write-up indicated that in the course of an experiment
with the audion as an amplifier, I deliberately turned aside
to determine what might be done with the equipment and
circuit then available, to produce musical tones and
alternating currents. 1
" De Forest testifies that in August, 1912, ' the first
arrangement was used and disclosed for producing altern-
ating currents suitable for the production of musical tone.
The principles involved were discussed and explained; the-
circuits were clearly understood and recorded, and many
observations were made covering the arrangements or
changes whereby the pitch and quality of the musical notes
thus produced could be controlled. 1
11 It is generally conceded, indeed as it must be, not
only by the Examiner and Commissioner, but by the
The Past to 1912 59
parties to this action, that the diagram made in August,
1912, as well as the accompanying notes, not only dis-
closed the invention but disclosed it in a clear workable
manner. So clearly was this fixed in the mind of De
Forest that in October, 1912, he returned to New York and
there met the witness Stone at the Arts Club. He told
Stone of his discovery. Stone procured a piece of paper
on which De Forest reproduced the drawing showing the
invention, as it appeared in the disclosure made in August.
So perfectly did this demonstrate the invention, that Stone,
years afterward, when testifying in this case, took a piece
of paper and reproduced the drawing while on the witness
stand, purely from his recollection of what he had seen
in the Arts Club in New York*
" In February, 1913, De Forest returned to California,
and on April 17th following, put into actual practice the
oscillating audion. In May of the same year he returned
to New York, and in June filed an application for a patent
for the amplifier and relay, in the hope of raising sufficient
funds to commercialize the present invention* He
succeeded in September, 1913, in selling to the telephone
company the invention for which he filed in June, and
immediately wired Logwood in California to join him for
the purpose of commercializing the oscillating audion
invention. Logwood came to New York, and in October
started work towards commercializing the invention.
March 12th, 1914, 1 application was filed by De Forest and
Logwood for the oscillating audion invention, and about
the same time apparatus was manufactured and sold
embodying the invention. The present application was
filed by De Forest individually, September 23rd, 1915,
The subject matter here in issue was the sole invention
of De Forest, but it was disclosed in the original joint
application of De Forest and Logwood. The facts relative
1 Author's note. U.S. Pat. 1,170,881 ; Br. Pat. 8,950/15.
54 Radio: Beam and Broadcast
to the activity of De Forest following the discovery of
August, 1912, are not only well proven, but they stand
undisputed in this record, and we think completely
negative any thought of abandonment. They likewise
conclusively answer the charge of lack of diligence, if it be
assumed that the disclosure of August, 1912, amounted to
nothing more than a conception of the invention.
" In this view of the case, it matters little whether the
case be disposed of upon the theory that what was done
in August, 1912, amounted to reduction to practice or
merely conception of the invention. In either event De
Forest must prevail. While we think the work then
accomplished amounted to reduction to practice, the case
can be as readily disposed of upon the ground that De
Forest clearly had at that time a conception of the invention
and made a disclosure of it to others, since there is nothing
to show, under the circumstances disclosed in4his record,
that he was lacking in diligence.
" Attention has been directed to our decision in the
:ase of De Forest v. Miller, 50 App. D.G. 202, where it is
irged that we passed upon the sufficiency of De Forest's
iisclosure of August 6th, 1912. The issue in that case
nvolved a system for producing musical sounds, whereby
,he pitch and intensity could be so controlled as to produce
my note of the musical scale at will, thereby obtaining a
nusical instrument which produced beautiful clear and
weet musical notes. The claim was very different from
lie claim here in issue, which calls for ' means for produc-
ng sustained electrical oscillations.' The development of
,he musical instrument did not occur until 1915 when the
nterference arose between the applications of De Forest
ind Miller. It was not denied by the Patent Office in that
>ase, that the disclosure of De Forest of August 6th, 1912,
imounted to a conception of the invention, but assuming
hat to be true, it was properly held by the tribunals that
The Past to 1912 55
there was a total lack of diligence on his part in developing
the particular invention there in issue. Hence that case
has no bearing upon the present litigation.
" It is insisted, however, that the question of priority
between De Forest and Armstrong was disposed of by the
United States District Court for the southern district of
New York in Armstrong v. De Forest Radio Telephone &
Telegraph Co., 279, Fed. 445. That case involved an
infringement, and the question of priority, so far as the
present interference is concerned, was not there involved.
The Armstrong patent there in suit involved a radio
signalling system and every claim called for a radio
signalling system, and in no respect contemplated the
production of ' sustained electrical oscillations/ We are
not here concerned with the question of whether the pro-
duction of electrical oscillations be of radio or audio
frequencies, or to what particular use they are put. So
remote are the present issues from the claims before the
New York Court, that if De Forest had been accorded
August 6th, 1912, for reduction to practice in that case,
it would not necessarily have anticipated the terms of the
claims of the Armstrong patent. Hence the discussion
of the New York Court, as to what De Forest did in August,
1912, is merely persuasive.
" The decisions of the Commissioner are reversed and
priority awarded De Forest.
" This case was decided prior to the death of the late
Chief Justice.
" JOSIAII A. VAN ORDSDEL,
" 'Associate Justice."
The author has no comment to make on this judg-
riient beyond suggesting that Armstrong's work in radio
is such that, had he no patented or patentable inventions
and he has many he would still rank as one of the fore-
most exponents of the art.
CHAPTER II
AFTER 1912
WITH the discovery that the triode could be made to
function as a generator of alternating current of any
desired frequency, it became apparent that there was a
prospect of evolving a radio transmitter that would
approximate to the ideal. That prospect has now been
realized, and the triode has passed the acid test of
commercial application.
Engineers naturally look with some indulgence upon
the alternator as a radio-frequency generator, because of
its theoretical simplicity; but it seems extremely likely
that the triode and its derivatives will not soon be super-
seded as the keystones of all transmitters of moderate
power. Especially is this likely in view of the fact that
only one basic technique is involved. Moreover, the
triode is quietly revolutionizing the arts of wire telephony
and telegraphy, and must soon find important applications
to the submarine cable: hence it is proving the greatest
factor in bringing about that closer co-operation between
the technicians of the various forms of telegraphy and
telephony, which is so desirable; and which has had such
an enthusiastic advocate in General G. O. Squier.
Technicians appear to have been waiting for the
development of the triode and its use as an oscillator in
order to put into service many of the inventions and dis-
coveries of the previous thirty years; even including some
of those made by Hertz in 1888, such as the use of the
short-wave. (Fig. 28.)
Fessenden's interference receiver (or Heterodyne)
invention found no commercial application until the
triode was available; but at the same time the triode so
simplified amplification that it provided an efficient
alternative method of detecting continuous waves.
Technically, there is nothing now to preclude the
56
After 1912 57
widespread application of guided-wave telephony, by the
use of which most of the benefits of other than graphic
arts may be made available to all whose homes are served
by an electric-lighting system.
Already commercial telegraphy and telephony have, in
many countries, been revolutionized by guided-wave
methods, and the use of the triode. Moreover, these two
agencies have been the means of saving thousands of tons
of copper. Every electrical conductor is now potentially
a telephone or telegraph line or both, and it may be the
conveyor of grand opera. Appropriate receiving methods
are disclosed in the specifications of British Patents
15,718/11 to Erskine Murray; and 3,191/14 to Squier.
Guided-wave telephony, or " wired-wireless," appears
to have been first proposed by Hutin and Leblanc in
1892 (Br. Pat. 23,892/92; U.S. application (?) 510,658),
developed by them as disclosed in the specifications of
their later patents (U.S. 596,017 and 628,246; Br.
2,107/96), and later by Leblanc alone (U.S. Pat. 857,079).*
The idea is also crudely embodied in the specification of
British Patent 1,555 granted to E. G. Foresio in 1900.
In later years the method has been developed by G. O.
Squier. (U.S. Pals. 980,356, 980,357, 980,358, 980,359;
Br. Pat. 30,003/10.)
Guided-wave telegraphy would seem to be the natural
evolution of the harmonic systems disclosed by Pupin and
others many years ago.
While it would be rash to prophesy that there will be
no more startling and valuable inventions in the radio
field,, it is safe to say that, if none are made and vested
interests permit, the development and practical applica-
tion of the art may steadily progress for many years to
come on the basis of present knowledge.
Already speech has been transmitted from a vessel 150
1 See also J. 8. Stone's U.S. Pat. 698,162.
58 Radio: Beam and Broadcast
miles at sea in the Atlantic to an island 30 miles off the
Californian coast in the Pacific being relayed over the
transcontinental telephone wires; and a regular service
part wire and part wireless has been open to the public
since the summer of 1920. 1 (See Proc. I.R.E., June,
1923. H. W. Nichols and Lloyd Espenschied.)
A comparatively recent practical development consists
in the suppression of the carrier-wave 2 and one of the side-
bands 3 in radio-telephony.: In the author's humble
opinion, this marks the culmination of technical advance
during the last ten years, although it has not yet had any
wide application. In view of present hopes and prospects
of dependable, if not continuous, long-distance com-
munication by means of comparatively low-power and
short-waves, it now appears likely that a limited secret
trans-ocean radio-telephone service will soon be available
to the public. (See Proc. I.R.E., October, 1922, and
February, 1923, papers by Lloyd Espenschied and R. V. L.
Hartley, respectively; also a paper by Dr. H. W. Nichols,
Journal I.E.E., London, July, 1923.)
Great inventions, as often as not, arc the result of little
effort; but the development of inventions so that they may
be applied to commercial uses, often entails the closest
study and prolonged effort. A classic example is that of
the Bellini-Tosi Direction Finder, which, although of great
inherent merit, was ten years old before II. J. Round, again
with the aid of the triode, made it of immense value to
Britain and her allies during the Great War. Round's
later work in connection with the development of the
1 It is understood that, since the above was written, a cable has been
substituted for the wireless section.
3 Patents U.S. 14,959 (re-issue) October 19th, 1920, to De Forest; U.S.
1,449.382, Br. 102,603, to J. R. Carson; U.S. 1,449,392, Br. 146,881, to
H. de F. Arnold. Also U.S. Applications 244,839 and 274,288 by
Alexanderson and White, respectively (19).
8 Wave filters. Patents U.S. 1,227,113 and 1,227,114, Br. 142,115, to
O. A. Campbell (19). Much of J. Si. Stone's early work is also relevant
to wav^filtera. See, for instance, Pats. Br. 28,826/04 and 9,422/06; U.&,
714,756,
60 Radio: Beam and Broadcast
valve transmitter, although not characterized by any basic
invention, is historical.
By a stroke of genius somebody discovered that one of
the Bellini-Tosi aerials could be inverted. This meant a
very great advantage on shipboard, where it is convenient
to have the fore-and-aft aerial with its base uppermost,
and the 'thwart-ship aerial with its apex uppermost.
A later development of great importance was an
aperiodic aerial, involving tuning of the search-coil circuit
only, and thus facilitating the essential expedition of
successful direction-finding. (Br. Pat. 149,066 to H. J.
Round and G. M. Wright.)
Efficient modified forms of direction-finding apparatus
which have found wide practical application have been
evolved by J. Robinson in England (Br. Pats. 134,342,
etc.) and by F. A. Roister in the United States (Br. Pat,
138,318), the former being particularly applicable to
aircraft.
A frequent bone of contention in radio patent litiga-
tion is the grid leak. (See Patents, U.S. 1,282,439, Br.
147,148 to Langrnuir; and U.S. 1,377,405 to De Forest.)
In a somewhat lesser degree, questions arise regarding
the " C " battery or the application of a steady voltage to
the grid of a triode. (See Patents, Br. 1,482/11; U.S.
1,038,910 to Von Lieben et al; U.S. 1,231,764 to Lowen-
stein; U.S. 1,282,439 and Br. 147,148 to Langmuir; Br.
13,248/14 to Round; and U.S. 1,426,754 to Mathes.)
The growing use of tuned radio-frequency amplifica-
tion lends a particular interest to British Patent 8,821/13. *
(U.S. Pat. 1,087,892 to Schloemilch and Von Bronk.) This
patent is equally relevant to the modern practice of
" reflexing," or amplifying both audio and radio-frequency
in a single triode.
> See also Patents. U.S. 1,173,079, Br. 147,147, to E. P. W. Alexander-
on, and U.S. 1,882,4&, Br. 147,148, to I. Langmuir. See Appendix* plfl.
After 1912 61
Undoubtedly one of the greatest feats of radio-engineer-
ing within the last few years has been the development of
distortionless modulation over the whole gamut of
orchestral frequencies of energy calculated in kilowatts*
There have been many refinements in receiving
arrangements; mostly involving the basic inventions of the
triode, heterodyne and regeneration , in combination with
directive aerials and note-tuning.
In 1919 Professor L. A. Hazel tine, of the Stevens
Institute of Technology, Hoboken, N.J., evolved the
41 Neutrodyne " method of reception which has become
extremely popular. (U.S. Pats. 1,450,080 and 1,489,228.)'
It has been claimed by those interested, that the following
patents are also relevant to the " Neutrodyne " method,
namely, U.S. 1,183,875 to Hartley; and U.S. 1,334,118,
Br. 119,365 to Rice (19).
Another receiving method which has lately become
very popular, particularly in America, is the Super-
heterodyne. In this method the " beat " is adjusted to
and amplified at a convenient and usually definite super-
sonic frequency. See Patents (British) 133,306, October
1st, 1918, to L. Levy; 135,177, June 18th, 1918, to Siemens
and Co.; and 137,271, December 30th, 1918, to E. H.
Armstrong. The dates are all Convention Dates. 1
Despite the oft-recurring reports of their slaughter,
" atmospherics " are still the bane of Traffic Super-
intendents. Nevertheless, if, as one supposes, they (the
atmospherics) are merely additive, it seems certain that
someone will find a way to avoid their interference with
the signal that is always there. Meantime, by means of
directive aerials, sharp tuning, and proportional recorders,
their effects are greatly mitigated.
Fading is still with us, and its cause remains to be
discovered.
1 See also Br, Pat, 252/14 to von Aroo and Meissner, p. 172.
62 Radio: Beam and Broadcast
Freaks also remain to be explained. Dr. W. H.
Eccles has suggested that they are the equivalent of the
mirage in optics, and that as such, they are a law unto
themselves (7d).
It is appropriate here to note the fact that in 1920
there passed away one of the earliest workers in the field
of wireless telegraphy (lie), in the person of Senator
Augusto Righi, under whom Marconi studied at Bologna.
Apropos of recent short-wave developments, it is recorded
(1) that, over twenty-five years ago, Righi succeeded in
generating Hertzian waves of a length of only 2-5
centimetres.
(The following works of Righi will be found in the
Library of the British Museum in London and in the New
York Public Library : A paper entitled " Sulle oscillazioni
elettriche a piccola lunghezza d'onda, etc.," published in
1894; a book entitled " L'Oltica delle oscillazione elet-
triche/' * published in 1897; and another entitled
" Fenomeni elettro-atomici," published in 1918.)
Some idea of Right's character may be obtained from
the following tribute paid to him by his friend Augustus
Trowbridge : " Righi's friends appear to have been jealous
lest he should fail to receive proper credit for his part in
making wireless communication possible; but not so
Righi himself, who cared little for popular applause and
actually enjoyed a fuller measure of it in his own country
than ordinarily falls to the lot of a pure scientist " (17).
1 In German in New York.
CHAPTER III
THE FUTURE
WHATEVER the future may have in store, it seems unlikely
that there will be any great improvement in results, but
rather in their dependability and the methods of obtaining
them.
Inventive genius will naturally be directed towards
effecting economies in the ether, in connection with which
serious problems are already arising. It is inevitable that
there will be great developments in note-tuning, and it
may be that modulation or " chopping " of telegraph
signals will be effected at the transmitter. In such case,
transmitting stations will be licensed as to both the radio
and audio-frequency characteristics of their signals. 1
Meantime, considerable economics of "line-lime"
could be effected on the congested 600-metre wave in the
North Atlantic, by the elimination of the words " Latitude
North, Longitude West," from the positions which are
signalled to shore, and which constitute a considerable
proportion of the traffic on that wave. "Latitude" is
invariably given first, and most of the ships regularly in
the North Atlantic trade arc never in South Latitude or
East Longitude. A rule might therefore be established
that Latitude will, as now, always be given first, and that
the four words quoted above will be deleted, excepting
when a ship is in South Latitude or East Longitude, where
(except in the North Sea) the ether may be less congested.
There are already available very highly tone-selective
receivers, relays and recorders; and when, as seems likely,
in some cases ships will be required to transmit certain
specified wave-train frequencies only, such devices will
find a wide application. There are numerous methods
electrical, mechanical, acoustic, and their combinations
of adding the refinement of note to wave-tuning; but their
1 The possibility lends a special interest to Br. Pat. 155,854 to W. H.
Eeclee and F. W. Jordan.
63
64
Radio: Beam and Broadcast
applicability, and consequently their development, has
been retarded pending greater stability of note-governing
conditions at the transmitter. The author has seen the
Hall Air-Jet Relay (Figs. 23 and 24) (U.S. Pat. 1,160,072;
Br* Pat. 144,250) satisfactorily operating a recorder,
through jamming which made it almost impossible for a
trained ear to read the desired signals.
Beam signalling will undoubtedly find extended use,
and being presumably free from vital patent restrictions,
is sure of rapid development; particularly for short
distances. It will be especially useful for conversation
Fig. 25. Hall Air-Jet Acoustic Relay.
(Hot Wire Type.)
between ships in sight of each other, at sea; for aids-to-
navigation purposes; and possibly in land warfare.
It has already been proposed to use as a conductor or
aerial a beam of waves of the frequency of ultra-violet
light, and such a beam may come to be utilized to guide
a carrier wave. (Br. Pat. 124,833 to J. Hettinger.)
" So, Engineers, observe a Wave
Hath smaller Waves that on him ride,
And these have smaller Waves to ride 'em,
And so proceed ad infinitum."
So one may paraphrase Dean Swift and epitomize the
technique of radio-telephony.
u
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4-J
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U
bb
66 Radio: Beam and Broadcast
The triode, as we know it, will undoubtedly undergo
considerable evolution. De Forest and others have
proposed various forms of hot cathodes, and it may be
that an arc will come to be used as a cathode in the larger-
powered triodes of the future; in fact, this is suggested in
the specification of De Forest's British Patent 5,258/06.
On the other hand, it has been suggested that the hot
cathode may some day be dispensed with.
There is very much work for the research engineer of
the future in discovering the hidden causes of the many
known phenomena; and for him, as for most of his
predecessors, success is likely to be its own reward.
We have yet to learn why radio waves persistently
ignore certain spots in their great-circle path to others
more distant, where they arrive with no abnormal
attenuation. Cases are too numerous and too well known
to be worth citing. It seems hardly reasonable to suppose
that a " Heaviside Layer " or any other celestial reflector
is sufficiently stable, as regards position and plane, to work
consistently for the benefit or otherwise of certain spots. 1
We do not know the cause of fading. It could be
accounted for by a variation of wave-length due to the
equivalent of winds in the ether; just as the pitch of the
whistle of a passing locomotive will vary with the growth
and decay of the speed (and frequency) of the sound waves,
as their source approaches and recedes; but there is no
proof that fading is so caused. According to Fleming,
" No experiments yet (1921) devised have enabled us to
determine any motion of this hypothetical aether relatively
1 In his 1924 Kelvin Lecture at the Institution of Civil Engineers,
London, Professor Elihu Thomson enunciated the theory that a
" Heaviside Layer " was unnecessary, since all radio waves were
guided by the earth, which was the real conductor; just as was the wire,
in guided-wave telephony or telegraphy. He illustrated his theory by
saying that the ideal condition for radio would be a smooth copper earth
in a vacuum. This theory seems to be well supported by the well-known
fact that much greater distances are possible over water than over
bat it is believed to be unpopular with mathematicians.
The Future 67
to the earth or any other moving matter," and he quotes
Professor Eddington as declaring that "the aether must
now be regarded as an idle hypothesis unsupported by
experiment and giving explanations of nothing " (106).
If one may not postulate ethereal winds, a reflecting
layer, or even an ether, there is only the " passing shadow "
theory to account for fading unaccompanied by freaking; 1
but when fading alternates with freaking, the cause would
seem to be transient interference and co-operation of direct
and diffracted waves, which inevitably bespeaks a layer.
Given adequate power, there is every reason now to
believe that dependable, if not continuous, communication
by radio-telegraphy may be effected between any two points
on the earth's surface; and that between relatively
antipodean stations, communication should be particularly
dependable. In fact, in the near future, there will
probably be an " antipodean " station in every country
almost certainly in every continent. The receiving com-
ponent of each will be equipped with a number of
vertically plane-polarized and " sense " selective aerials,
arranged radially about the operating house; so that
regardless of the direction of approach, or the phase of the
incoming waves, their energy may be'summated in the
received signal. In short, it is not unlikely that the most
dependable, really long-distance, communication of the
future will be effected between stations that are
approximately " poles apart."
Obviously, transmitting stations of such relative location
would be of the " Broadcasting " kind; as any attempt to
use directional transmission would tend to the sacrifice of
the special value of broadcasting for such communication.
Moreover, for highest efficiency, a directional transmitter
would require to be continuously oriented.
There is not yet any ground for supposing that
1 By which is meant the reception of signal* of excessive strength.
68 Radio: Beam and Broadcast
" beam " transmission will ever be practicable or useful
for antipodean or even long-distance communications; but
there is good reason to suppose that the high-powered
long-wave transmitter of the future will be supplemented
by a short-wave comparatively low-powered transmitter
for auxiliary night communication, particularly where the
route of communication has a diurnal all-dark period. It
is perhaps not sufficiently well remembered that no two
spots on the earth's surface are more than 12,500 statute
miles apart; or that two broadcasting stations of this range,
and suitably disposed, could sweep the earth.
Meantime, the cables are not threatened, 1 and where
efficient cable services are available it is very debatable
whether or not it is economically sound to operate wireless,
except as a supplementary or standby measure.
It may transpire that, on account of the uniformity of
conditions of light, long-distance wireless services will
tend to be restricted to longitudinal routes.
The wave-lengths allocated to broadcasting and
amateurs have proved so efficient for night communication
that an attempt may be made to reclaim them for com-
mercial telegraph purposes during the night hours say
from midnight to 6 a.m.; especially is this likely since the
very long waves now in use for telegraphy tend to impose
a limitation upon the speed of transmission. According
to recent reports, the allocation of a band of short waves
to commercial radio-telegraphy seems now to have been
definitely decided upon.
It is unlikely that there will be any wide application of
radio-telephony to public service beyond broadcasting.
The average broadcasting station occupies as much of the
ether as would accommodate ten radio-telegraph stations
possibly more; and the ether is already becoming con-
1 This mav need qualification when exhaustive long-distance tests have
been made with very short waves.
The Future 69
gested. The suppression of the carrier wave and one of
the sidebands would effect an economy of the ether of
about 50 per cent, (and also of transmitting energy), but
stations operating under such economical conditions would
be unintelligible on Ihe broadcast receivers now generally
in use.
In the near future, broadcasting of local urban interest
only will likely be effected over existing wire (lighting or
telephone) systems, and so kept out of the ether. Stations
broadcasting entertainment, etc., of wider interest, will
probably extend their present practice of " tying-in," or
broadcasting the same programme simultaneously from
several stations; with a resultant improvement in the
quality of programme.
Already it is possible to set up an audio-frequency
electro-static field, so that a person may listen to a broad-
cast programme by means of a pair of head-telephones
having no fixed attachment; and may even hear the
programme in any part of a room. (Br. Pat. Application
16,442, 25th June, 1923, Hale and Lyle.) This device
may come into extensive use in private houses, hotels,
restaurants, ships and trains, where " loud-speakers " are
not desired. The electro-static field is set up by a con-
ducting grid which may be in the form of a mat under
a carpet, the metal lathing of a ceiling, or the spring of
a bed or chair, connected to one terminal of an audio-
frequency amplifier, the other terminal of which is con-
nected to earth or a suitably disposed counterpoise or
second grid.
When the " loud-speaker " is more nearly perfected,
there is no doubt that it will be used in hotels and ocean
liners to make orchestral music available in a number
of public rooms. For instance, on a liner, the orchestra
that plays for the first class passengers will be made
audible to those of the second and third class.
70 Radio: Beam and Broadcast
For the last twenty years or so, the ultimate authority
on radio matters has been vested in a league of nations
if one may borrow a term with headquarters at Berne in
Switzerland. For the use of this body a common language
had to be adopted; and, according to precedent, French
was chosen. Obviously, therefore, radio has long been a
factor in social evolution in the broadest sense; and to-day
the practice of " Broadcasting " opens up further new and
wonderful opportunities in this direction. To realize
what a great opportunity radio now affords to people of
good sense and goodwill, one has only to consider that
one station in Europe may provide instruction and enter-
tainment for people of twenty different races, tongues and
religious prejudices. What an opportunity also for the
advocates of Volapuk, Ilo, Esperanto, or other would-be
lingua franca !
There is little doubt that one of the effects of " Broad-
casting " will be the condemning of the spark trans-
mitters now in use on shipboard, because of their inter-
ference. Alternatively, their use within a given number
of miles of a broadcasting station may be forbidden.
At the moment the radio and shipping worlds most
urgently await an automatic distress-call receiver. It
must be one that is acceptable to all nations, and that will
not necessitate expensive or intricate gear at the trans-
mitting station. If it should appear advisable, there is no
doubt that the international distress call-signal would be
modified or materially changed to suit any practicable
device. The question presumably now awaits the
universal adoption of continuous-wave transmitters aboard
ship, or the next International Conference.
In the author's opinion, the ultimate distress-call will
be made up of signals of two or three different notes or
wave-train-frequencies, used either simultaneously or
successively. In such case, the automatic receiver will
The Future 71
Consist of two or three tone-selective switch-closing
elements, inoperable by anything but the distress-call,
and self -resetting.
As an alternative or additional measure, a special wave
may be allotted exclusively to distress-calls, particularly
in busy areas, and a definite number of suitably located
listening stations established to stand-by permanently on
that wave. Each of such " Distress " listening stations
will be equipped with direction-finding gear, so that the
distress-call may be confined to the ship's call letters or
any other signal on the prescribed wave.
If such a scheme were adopted, shipboard transmitters
would have to be designed to provide instantaneous
change-over to the " distress " wave, and for maximum
efficiency thereon. Ships unfurnished with operators
would be permanently tuned to the " distress " wave,
and would be provided with code-wheels or other
suitable automatic transmitters, and explicit directions for
their use.
Upon receipt of a distress-call, the distressed ship's
position having been located by means of cross-bearings,
the controlling coast-stations would be notified immedi-
ately to suspend all traffic on the commercial waves until
definite arrangements had been made for the assistance of
the distressed ship; meantime, certain extra ship or coast-
stations would stand-by on the " distress " wave.
It may be found desirable to have ships' distress radio-
transmitters tied-in to simultaneously operating submarine
sound transmitters, 1 so that (if she were equipped with
apparatus to measure the difference in transit-time of the
two signals) an approaching ship could calculate the
distance of the signal source. That such a method has
often been proposed may be gathered from a reference
1 Borknm Riff Light Vessel, Germany, is now experimentally
equipped in this manner.
72 Radio: Beam and Broadcast
to the specifications of the following British Patents :
12,124/99 to C. F. Kelway (Ether and Air); 10,082/09 to
J. Schiessler; 25,318/10 to E. F. Cassel; 4,352/14 to A.
Stchensnovitch; 7,452/15 to F. L. Sawyer; and 146,125/19
to R. L. Williams.
One very gratifying thought for those who have been
associated with radio for the last two decades or so, is that
it is now practically impossible to lie about it. Of course
there will continue to be exaggerated claims and wild
statements when, in the opinion of some of those con-
cerned, occasion arises. For instance, it is doubtful that
the fetish that radio will supplant conductor systems of
telegraphy and telephony will be allowed to die. The
astonishing thing is that, even in the days of radio's
greatest limitations, anyone ever thought it necessary to
embellish the facts.
The potentialities of short-wave radio appear to be very
great in a limited sphere. In the autumn of 1918, the
author proposed to the British Air Board that the ignition
systems of aircraft should be used for purposes of
telegraphic identification. To this end, every aircraft was
to have a three or four-letter identification signal like a
ship and be provided with a rotable code-wheel in series
with the engine ignition system. This code- wheel would
have appropriate conducting and insulating segments, and
would be normally short-circuited. Upon receipt of a
pre-arranged signal from below preferably a visible
signal the airman would rotate his code-wheel and
thereby signal his identity in two ways; namely, by
Hertzian, and air, or sound, waves. This matter is
brought to mind now by a perusal of C. S. Franklin's
report on his experiments with short waves, in which he
states that the interference he experienced emanated mainly
from the ignition systems of motor-boats and motor-cars
(7c).
The Future 73
It is suggested that by Hie use of very short waves
it may be possible for a**ship to discover its distance from
a signal source, because of the great consistency of the
attenuation of these waves over sea. It is not recorded
that experiments have been made with a view to discover-
ing whether or not this attenuation varies with sunlight
conditions, although it is known that there is a very great
difference between the daylight and dark attenuation of
short waves of the order used in broadcasting.
It has also been suggested recently that short-wave
radio beams may be used between ship and ship as an
aid-to-navigation in fog; and it is possible that with the
instrumentalities noAV available, something along the
lines proposed by A. N. Ilovlaml to this end, in 1901, may
be put into effect. (Br. Pat. 19,170/01.) (See also the
following British Patent specifications : 15,569/03 Ladd;
19,878/06 DC Forest; 27,938/06 De Forest; 18,632/12
Hienicke and Jasper.)
It has been shown that, in radio particularly, there is
often a great distinction between an invention and the
means to carry it out; and it is probably true that a number
of inventions of great potential merit have gone into the
discard, merely for the lack of means (instrumentalities)
to put them into effect. We have seen what the triode has
done for radio receivers, amplifiers, beam and other
transmitters, and direction-finders. May it not be that it
is capable of doing as much for some of the pre-radio
systems of telegraphy without wires? If some of these
systems could be resuscitated, they might now be used to
supplant the present short-distance radio services, and so
be the means of relieving the ether of its growing
congestion on the shorter waves. 1
1 The following British patents have recently been issued on inductive
systems incorporating the triode: 135,50 1, 151,530-1-2-7, to E. C. Hanson;
154,978, to Q. C. A. Cranfurd and L. O. Doughty- Wylio ; and 156,769, to
E. C. Hanson (void).
74 Radio: Beam and Broadcast
There seems always to be a " Last West " beckoning
the radio engineer with a taste and aptitude for pioneer
work. It will certainly be a good thing when his
technique is available to the healing profession, for it
is doubtful that electro-cautery, electro-diathermy, and
perhaps also radiography, have yet been developed to the
limit of the possibilities attainable by the more general
application of the triode, and fuller recourse to the data
available in the radio research laboratory.
It may yet be possible to project vortex ethereal rings,
and thereby secure some results not yet foreseen.
[To face page 75.
POULSEN ARC STATION AT ROME.
CHAPTER IV
THE POULSEN ARC 1
BY reason of its extreme simplicity, the Poulsen Arc still
has a wide application as a generator of radio-frequency
currents of high power and comparatively low frequency.
Unfortunately, however, the radiations are encumbered
with " mush " and harmonics, which must be eliminated
if the arc is to be an important factor in the future. 2
Here again, the invention was old before it found
much application, but in this case the delay was probably
due in large measure to the east wind of interested
criticism.
The refinement of the Arc is very largely due to the
energy and genius of G. F. Elwell (18), who, by the way,
had the unique distinction, during the Great War, of
being commissioned by the Italian Government to build
a long-distance Poulsen station in the neighbourhood of
Rome : a work that he carried out so successfully that he
was made a Knight of Cross of the Grown of Italy. The
Federal Telegraph Company of San Francisco are also
responsible for much development and practical applica-
tion of the Arc.
* As late as December, 1921, the British Wireless
Telegraphy Commission (26) recommended the installa-
tion of arcs in three of the stations of the proposed Imperial
Chain : not because they were thought to be more efficient
than the triode, but because of the advantage of their
fiirriplicity in view of the isolation of the proposed
stations.
The Poulsen Arc began to attract serious attention in
1 See Appendix, p. 180.
a Since the 'above was written, it is understood that great improve-
ment has been effected by the British Post Office Engineers in the radia-
tions of the Arc transmitter at Leafield. This has been done by screening
the transmitter house and installing a " coupled circuit," which latter
was part of Poulsen's original invention. (See Fig. 8 of his " British and
American Specifications," and Fig. 10 herein.)
75
76 Radio: Beam and Broadcast
1912, when the Marconi Company issued the following
circular, dated December 14th, 1912, to its stockholders :
" DEAR SIR (or Madam), Mr. Marconi has recently
returned to London, and has become acquainted with the
statements which have been made in recent weeks and
with the opinions which have been expressed that con-
tinuous waves would in future supersede the spark
system.
" As these statements and opinions are liable to mislead
shareholders and cause them some uneasiness, 1 am
instructed to inform you that Mr. Marconi himself tested
continuous wave systems many years ago, and experi-
mented with them during the greater part of 1907 at the
Poldhu Station. As a result of these experiments he learned
the advantages and disadvantages pertaining to continuous
waves, and eventually arrived at a compromise between
the continuous waves and spark systems, combining the
best points of both. This resulted in material changes
in his system for long distance work, and new and
important improvements were patented by him in 1907,
which are mainly responsible for the progress since made
in long distance wireless telegraphy.
" These inventions, which materially modify the spark
system, seem to be surprisingly little known, notwith-
standing the lectures delivered by Mr. Marconi at the Royal
Institution of Great Britain on March 13th, 1908, and
June 2nd, 1911, the Nobel Prize Lecture at Stockholm in
1909, and the address to the New York Electrical Society
on the 17th of April, 1912, when he made statements
relating to the use he was making of continuous waves,
semi-continuous waves, and the elimination of the spark.
" By Order of the Board,
4< (Signed) HENRY W. ALLEN,
" Secretary."
A few months after the date of this circular, the British
Marconi Company increased its capital in order to acquire
rights to the Goldschmidt Alternator, by means of which
The Poulsen Arc 77
a radio-telegraph service was established between Hanover
in Germany and Tuckertoa in the United States. Mean-
time, the merits of the Poulsen Arc, as compared with
those of other generators then available, became more
widely known and appreciated.
On May 7th, 1913, in his evidence before the British
Select Committee (21), Mr. Marconi said : " It has been
stated in evidence that my company recently endeavoured
to purchase the Poulsen patents. I give an absolute denial
to this statement. My company has had more than one
opportunity of purchasing the Poulsen patents in years
gone by, and it has not purchased them because, in my
opinion, firstly, there was no advantage to my company to
use the system; secondly, had there been, there has never
been any reason Avhy we should not have developed or
used the system, for I believe it is not protected by any
valid patent. In support of my opinion, the German
Patent Courts, for which everybody who has to do with
patents has the highest respect, has declared the Poulsen
master patent to be invalid and has annulled the German
patent " (21). On the same occasion, Mr. Marconi referred
to a lecture by Professor Fleming before the Royal Institu-
tion on May 24th, 1907, wherein the Professor described
an experiment which appeared to prove " inconlestably "
that the Poulsen Arc was not a generator of continuous
waves.
In view of the foregoing, it is worthy of note that in
1920, the British Maivoni Company having become
financially interested in the Poulsen system, an unsuc-
cessful attempt was made to get the British Patent thereon
resuscitated and extended it having expired about three
years previously (9).
Also it is interesting to note that there are now seventy-
eight stations equipped with Poulsen Arcs of 25 kW. and
over (18).
CHAPTER V
BROADCASTING
" And the night shall be filled with music,
And the cares that infest the day
Shall fold their tents, like the Arabs,
And as silently steal away."
Longfellow.
THE paramount question of the moment is the control of
broadcasting. There are the makings of a local broadcast
receiver in almost any scrap heap; therefore there need
be no limitation of the public enjoyment of the radio
programme.
Anyone who has considered the almost complete
prostitution of the cinema as an educational force, and its
unhappy effect on the youth of to-day, cannot fail to
appreciate the vital importance of directing to better ends
the almost equally potent force of radio.
There are indications that radio's potentialities for
insidious propaganda are already appreciated, and the
only safe course seems to lie in Government control,
particularly where there is representative democratic
government, as in Great Britain and the United States.
What could support this latter contention better than the
fact that the British administration is even now engaged
in an attempt to capture and broadcast the song of the
nightingale?
To the slum child of to-day, the nightingale means
about as much as the Phoenix, the Liver or the Dodo; but
to-morrow he may be familiar not only with the songs of
our birds, but, through a purged cinema, with their
appearance and surroundings. If so, the next generation
will undoubtedly be the better for it.
It cannot be too widely known that practically all the
benefits of broadcast reception may be enjoyed by the use
of equipment which need involve no patented invention,
78
Broadcasting 79
and need cost no more than a few pounds; even when well
made and attractively finished. It is only natural that
companies, owning costly patents, should endeavour to
cultivate a public demand for equipment involving their
use, and which can be sold at less competitive prices; but
the fact remains that perfect short-range reception is
accomplished with the simplest apparatus.
There is, or should be, no serious disadvantage in being
limited to the near-by station or stations; in fact the local
programmes are increasingly liable to be of special local
interest and may yet be indispensable. It is likely, there-
fore, that " Broadcatchers " of the future will settle them-
selves into two classes, which may respectively be termed
" stunters " and " utilitarians." The former will demand
equipment whereby they may attain the greatest distances,
and will be less concerned with economy and simplicity;
while the latter will want merely the most dependable and
simple apparatus that will enable them to enjoy the local
programmes. The former class will likely bear about the
same numerical ratio to the latter, as do racing motorists
to those who motor merely for purposes of transportation
or pleasure.
If the foregoing premises are correct, there will be
a large and increasing demand for simple, dependable,
patent-free equipment. Such equipment should be
designed to operate on a single-wire aerial of definite
length, so that the purchaser is not required to experiment.
Preferably, it should be fitted with a readily demountable
" catwhiskerless " crystal detector, and a " variometer "
tuning coil. The latter should be designed for minimum
self-capacity, to which end it should preferably have a
cylindrical stator. Such a set, with an aerial of reasonable
elevation or clearance, should give dependable results up
to six or eight miles from a broadcasting station, and
permit of the use of several pairs of telephones. Moreover,
80 Radio: Beam and Broadcast
an audio-frequency amplifier could be added, should the
user require more volume say for a loud-speaker.
For slightly longer distances and greater selectivity,
there should be a good market for a two-circuit " loose-
coupler," with secondary calibrated in wave-lengths and
preferably having both capacity and inductance variable.
The reason for the latter is that it enables the ratio
" capacity to inductance " to be varied to supply the most
satisfactory signal voltage to the detector: but obviously
the calibration would have to be predicated upon the fixed
position of one of the variables. Provision could readily
be made for the use of any type of detector, and for the
addition of regeneration; and apart from the latter, no
patent need be involved.
The effect that broadcasting may have upon the Press
is still uncertain. It is claimed that since only the bare
facts of the news may be broadcast, the effect will be to
stimulate the demand for newspapers. The author was
once discussing this question with two Canadian news-
paper editors who held this view. By way of illustration,
one said, " Suppose to-day the news is broadcast that
so-and-so has been murdered/' mentioning the name of
a famous British politician then in office; whereupon,
giving way to political prejudice, the other remarked,
"and a nice day for it too." The first speaker went on
to say that, in his opinion, everyone would want to buy
to-morrow's paper to get the details, and he was probably
right. It is certain that the broadcasting of parliamentary
procedure will not find favour. To have to listen to it
is one of the most trying ordeals of parliamentary life,
and to do so gratuitously would be to throw away one's
natural advantage; which reminds one of Gladstone's
comment when he saw a Member of Parliament using an
ear-trumpet.
The most inevitable benefit to be derived from broacl-
Broadcasting 81
casting, and one that is already making itself felt (particu-
larly in Britain) is in the purification of our spoken
language. In America, carrying and intelligible qualities
seem often to be sought in announcer's elocution rather
than general purity so that the American air carries a
variety of interpretations of our Mother tongue. It is not
good that one's children should listen to an address on
the " drayma," however well-informed it may be; and
such a vagary is not explained by the contention that a
certain kind of American English, differs from perfect
English, only in that it is spoken through a different organ.
The author would give an earnest of his lack of
prejudice in the matter by saying that he has the evidence
of his own cars that, in 1924, at least one British " Uncle "
disputed that there was no " k " sound in " indictment."
Nevertheless, it has to be admitted that the beautiful
articulation and usually perfect pronunciation of the
officers of the British Broadcasting Company are
tremendous educational factors, and one that must soon
lead to the extermination of " Coolie " English.
Unquestionably there is much that Britain and America
may learn from each other in the matter of broadcasting,
and it is certain that it would be an advantage if
" announcers " in North America were required to satisfy
a central authority as to the purity and standard quality of
their diction; as they do in Britain. This done, there
would soon be no point in the announcement of the
facetious German shopkeeper, " English spoken, American
understood," and the New York Eastsider might learn to
articulate an " r."
The following U.S. Patents are claimed, by those who
are interested, to be more or less vital to an efficient broad-
casting station in America:
879532 Feb. 18, 1908, De Forest
1129942 Mar. 2, 1915, Arnold
F
82
Radio: Beam and Broadcast
1129943
1137315
1201270
1201272
1218195
1231764
Re. 14380
1314252
1329283
1349252
1377405
1442146
1442147
1452032
Mar. 2,
Apl. 27,
Oct. 17,
Oct. 17,
Mar. 6,
July 3,
Oct. 23,
Aug. 26,
Jan. 27,
Aug. 10,
May 10,
Jan. 16,
Jan. 16,
Apl. 17,
1915, Arnold
1915, Heising
1916, De Forest
1916, De Forect
1917, Logwood
1917, Lowenstein
1917, Colpitts
1919, DC Forest
1920, Arnold
1920, Arnold
1921, De Forest
1923, Heising
1923, Heising
1923, Farrington
CHAPTER VI
BEGENERATION : IN RECEPTION
IN the experimental days of the triode, it was found
that under certain conditions audio-frequency oscillations
were set up, causing singing noises in the telephones.
These noises would disappear (or their pitch would be
varied) when the adjustments were altered; they were a
nuisance and came to be known as the " Canaries." Their
cause and its possible use, seem to have been discovered
almost simultaneously by a number of persons, and there-
after it soon became apparent that a revolution was about
to take place in the art of radio reception.
The singing was a manifestation of a property which
was, in more or less degree, inherent in the triode, and
which could be increased and brought under control for
useful purposes by means which became the subject of
numerous patents to different inventors in various
countries. In some cases one use of the property was
patented, and in other cases another. The consequence is
that the patent situation on this feature is much involved;
particularly in some countries.
In the United States of America, the first invention of
the regenerative use of the triode was, until recently,
credited to E. H. Armstrong, 1 who, according to Professor
J. H. Morecroft, in the Radio Broadcast of August, 1922,
having accidentally placed two coils " much nearer to each
other than they should normally be," heard a strange noise
in the telephones. This was a " beat" note, between the
oscillation frequency set up by his triode or " audion "
and that of an incoming signal which was being
impressed on his aerial circuit. Thus was invented
(if not for the first time) not only triode regeneration,
but the detecting self-heterodyne: the simplest possible
p ' 1CO) U 8> Pat M1M40; Br. Pat. 2
88
84 Radio: Beam and Broadcast
instrumentality to reduce to practice the masterful
invention of Fessenden. 1
The Year Book for 1923, which is published by a
Marconi subsidiary in London, credits the invention of the
self-heterodyne to Meissner of Berlin in 1913, whereas it
was specifically patented to H. J. Round in Britain by
Patent No. 28,413 2 of that year, and Meissner expressly
disclaims it. 3 (Br. Pal. 252/14.) Nevertheless and
despite the further disclaimer of the British patented
inventions of Franklin (13,636/13) and Armstrong
(24,231/14) Meissner's specification carries claims which
appear to cover all three. If the reader is fond of mental
exercise he will enjoy studying the latter (amended)
specification in the light of the others mentioned therein.
The specification of Round's patent makes the follow-
ing clear reference to the inherent capacity for regenera-
tion in the triode : " By suitably adjusting the circuits,
signals produced by continuous waves can be heard in the
telephones. If the capacity between the grid and the
third electrode is insufficient, a small condenser may be
connected across the grid and the third electrode, or the
oscillation circuit may be made to interact with the aerial
or with an intermediate oscillation circuit by so arranging
the circuits that there is mutual inductance between
them."
Precisely the same circuit arrangement was previously
patented in Britain to C. S. Franklin (13,636/13), 4 whose
invention was the use of regeneration to nullify or reduce
the resistance of the receiving system.
An important development of the regenerative
principle in receivers, is the super-regenerative circuit, in
connection with which the following patents and applica-
tions therefor are held to be more or less relevant: Br.
' See p. 33. 'See p 172
9 See Appendix, p. 167, * See Appendix, p. 151.
Regeneration: in Reception 85
182,135, U.S. Serial 807,388 (?), Armstrong; Br. 156,330,
U.S. 1,407,245, Bolitho; Br. 130,408, U.S. Serial (?)
276,856, February 13th, 1919, Turner.
Whether or not the U.S. Patent Office differentiates,
or will differentiate, between the use of the " feed-back "
circuit for the (a) generation of oscillations for transmis-
sion purposes, (6) generation of oscillations for " hetero-
dyne " reception, and (c) amplifying received signals, the
author does not know.
11
CHAPTER VII
THE TRIODE AS A GENERATOR OF RADIO FREQUENCY
ALTERNATING CURRENT
BY causing a telephone receiver to react on a telephone
transmitter, A. S. Hibbard, in 1890, discovered the
principle of the Hummer or Humming Telephone (Fig 27).
Later, Professor Larsen, of Copenhagen, used the same
principle in the production of alternating current from a
direct current source (13). Therefore, the use of reaction
or regeneration, in the production of alternating currents
from a direct-current
source, was well known
when the triode came
into being. Neverthe-
less, it is not recorded
that anyone sought to
duplicate the hummer
phenomenon with the
triode; which latter
Fig. 27. seems to have been
Telephone Hummer. accidentally developed
as a generator, without reference to any prior art.
Since 1913 it appears to have been generally recognized
that under certain conditions, which were only too easily
established, the generating property of the triode was
inherent and inevitable.
In Armstrong's (American) specification 1 we read : " It
will be understood from what has been said that the ratio
of transformation of the transformer should be adjusted
to get the maximum signals without causing the audion to
generate oscillations."
In the specification of his British Patent 13, 636/13, a
Franklin also directs attention to the danger of persistent
oscillations being set up in the triode, and at about the
1 See Appendix, p. 164. a See Appendix, p. 158.
86
The Triode as a Generator 87
same time De Forest, too, had mentioned the precautions
necessary to prevent singing (116).
The first reference in the records of the British Patent
Office to the use of a triode as a useful generator for
transmission purposes, seems to be in the specification of
Br. Pat. 252/14 * to Von Arco and Meissner.
From the foregoing, it would appear that the possibility
of generating radio-frequency alternating currents by
means of a triode, was fairly well known for some time
before anyone suspected that it could be developed for
transmission purposes. The first to use the triode in a
transmitter appear to have been Round in England, and
Von Arco and Meissner in Germany; but such use does
not appear to have been specifically patented anywhere,*
unless, perhaps, in the latter country. 3
1 See Appendix, p. 168.
2 See U.S. Application Serial No. (?) 52,176, September 23rd, 1916.
a Since the above was written, the first invention in America of the
triode or audion as an oscillation generator has been credited to De Forest
by a judgment of the U.S. Court of Appeals of the District of Columbia
dated May 5th, 1924. (See p. 45.)
CHAPTER VIII
BEAM AND SHORT-WAVE RADIO
IN an address to the shareholders of Marconi's Wireless
Telegraph Company Limited, on December 3rd, 1923,
Senator Guglielmo Marconi made the following statement
in reference to beam signalling :
" This system is, I believe, destined to bring about
somewhat of a revolution in the methods hitherto
employed for communicating by wireless with distant
countries. According to this system the electric waves
which carry the messages are projected and propagated in
a beam in any desired direction only, instead of being
allowed to spread around in all directions. The advant-
ages of the new method are at least four-fold, because :
" 1. Due to the better utilization and concentration of
power a much smaller amount of electrical energy need
be employed for a given distance, resulting in a substan-
tial economy in capital and working expenses.
"2. Only stations inside a certain restricted angle or
sector are enabled to receive, and this increases the
privacy and secrecy of communication, besides greatly
reducing the possibility of mutual interference with other
stations.
" 3. Owing to the employment of comparatively short
waves, the speed of transmission and reception can be
several times greater than what is attainable with existing
long-distance systems.
" 4. The disturbance caused by the effects of atmos-
pheric electricity are greatly minimized.
" During the tests which I have already referred to,
communication was successfully carried out on this
system between England and many places abroad, includ-
ing St. Vincent (Cape Verde Islands), up to a distance of
2,250 nautical miles, by the employment of only a fraction
of the electrical energy hitherto found necessary to cover
88
Beam and Short-wave Radio 89
such distances. I am now completing arrangements
which will enable me to give this system a thorough test
between England and the United States of America " (14).
A beam demonstration was given by C. S. Franklin
before the Institution of Electrical Engineers, London, on
the 3rd of May, 1922, and repealed by Senator Marconi
in New York in the following June, arousing much
popular interest. In the circumstances it will be
appropriate here to review the history of this branch of
the art.
It was by means of very short waves and parabolic
reflectors that Hertz carried out his experiments and laid
the foundation of radio; and it is recorded that he produced
waves of 30 centimetres in length, which he concentrated
into a single beam. It is also recorded that Senator Righi
produced waves as short as 2-5 centimetres (1), while
Senator Marconi used waves of ten inches in length in
1896-97. 1
In Marconi's provisional specification of 2nd June,
1896, we read that when it is desired to transmit to the
greatest possible distance and in only one direction, " I
place the oscillation producer at the focus or focal line of
a reflector directed to the receiving station, and I place the
tube or imperfect contact at the receiving instrument in
a similar reflector directed towards the transmitting
instrument; " while in a Marconi (Canadian) prospectus
(undated, but apparently published in 1907 2 ) we
read :
11 Com. Marconi has recently perfected instruments by
means of which he is enabled to so direct the waves of
wireless that they will travel in a direct line from the
point of transmission to the point of receipt, and cannot
1 See Appendix, p. 120.
2 Published over the name of tl Munroe and Mimroe, Agents for the
Marconi Underwriters of America.
00
Radio: Beam and Broadcast
be received at any other station or point than the one at
which they are intended to be received. By this means
wireless waves are conducted through the ether in focal
lines of force exactly as though wires were used.
" Recently a group of war vessels at anchor on the
Mediterranean side of Gibraltar were employed in testing
the new improvement.
" Marconi, from his station in Cornwall, was enabled
to select one of these vessels, and by directing his waves
upon that one vessel, just
as a beam of light might be
focussed upon a given point,
was able to communicate
with her without her sister
ships being aware of the
fact."
The foregoing quotations
tend to create the impres-
sion that the recent develop-
ments in " beam " radio
represent merely the re-
discovery of a lost art. As
a matter of fact, the first
relates to the reduction to
practical use, by means of
instrumentalities only re-
cently available, of inven-
tions and discoveries made
some thirty years ago. Of
Fig. 28.
Hartley Circuit.
Circuit of xo-metre Generating Set.
(By courttsy, U.S. Bureau of Standards.)
the others, while perhaps they are all a little over optimistic,
the last particularly serves to illustrate the temptation to
" paint the (radio) lily " to which so many still succumb.
The practical utility of short-wave " beam " and, in
greater degree, " broadcast " signalling, is now estab-
lished; but on account of the attenuation of short waves
Beam and Short-wave Radio 91
during sunlight, it has yet to be proved that they will
be useful for continuous long-distance communication.
Moreover, the known fluctuations of the apparent path of
signal waves of the length now in use, suggest that beams
will be impracticable for long-distance work, unless they
are very little concentrated, and consequently not beams
at all. It is possible, however, that very short waves may
be found to be more persistent in their direction than the
longer waves.
As to the prospect of energy economy, to which Senator
Marconi refers, there can be no doubt as to the efficacy of
short waves, per se. This has frequently been demon-
strated during the last few years by the performances of
amateurs. In fact, it is gelling to be a commonplace
thing, particularly in the winter months, for these
enthusiasts to engage in two-way telegraph communica-
tion over distances of the order of two thousand miles,
with only one hundred watts of energy. If they used
" reflectors " their performances no doubt would be
credited to the efficacy of the " beam."
Before any opinion can be expressed on the efficacy or
practicability of the " beam " method, as such, over long
distances, it must be demonstrated that, as compared with
what can be accomplished on the same wave without a
reflector, the beam method secures :
(1) Useful economy of the ether.
(2) Useful secrecy.
(3) Any appreciably greater distance, and
(4) Any considerable economy of power.
The first alone will justify the method, if maintenance
costs are not excessive.
There seerns to be little likelihood of the second.
The third is important, and the fourth is likely to be
negligible, except in so far as the operating speed may
be governed by the power used.
92
Radio: Beam and Broadcast
T
M
Having regard to the power-economies which, as is
well known, can be effected by the use of short waves, per
se; and in view of operating- costs and overhead charges
which within certain limits are independent of power
consumption, there appears to be little benefit to be
derived, in terms of power-economy, from the use of
reflectors; even when the latter are developed to perfection.
s If, however, reflectors are
^x' x evolved whereby radiation
,/ is limited to an angle of
even 30, their use will be
amply justified, although
no useful " secrecy " ob-
jective will be attained.
In this connection it must
not be overlooked that a
30 "beam" in trans-
A tlantic communication
would give a wave-front
of approximately 1,500
miles at the receiving
terminal. Even if reflec-
tors prevent only rear-
ward radiation and this
is theoretically possible by
other methods their use
will be amply justified,
since the major problem
to-day is rather how to
effect economies in the ether than in power-consumption.
The generation and radiation of power at very high
frequencies present many difficulties, when twenty or
thirty kilowatts have to be radiated; and herein lies the
chief concern of technicians : moreover, when reflectors
are used, the problem is further complicated.
Fig. 29.
Illustrating the need of a wide aperture
to obviate leakage as at GW.
Principle of reflection of waves from a parabolic
reflector.
(By courtesy, U.S. Bureau of Standards.)
Beam and Short-wave Radio 98
Reference to Fig. 29 will show the importance of wide-
aperture reflectors. For practical purposes Marconi
proposes to use an aperture of eight wave lengths (lOd),
which, for the Canadian stations of the proposed Imperial
Chain (29), will involve reflectors 840 metres wide, since
the said stations arc licensed for waves of from 85 to 105
metres (but with no angular limit, except that imposed
by the British contract). On the other hand; in Marconi's
Society of Arts paper (lOd), there is reference to a new
type of flat aerial and reflector invented by Franklin, which
may indicate that the parabolic form of reflector is losing
favour. The new type suggests the directional radiator
patented (Br. 130,064; U.S. 1,360,167) to Alexanderson,
who claims for it " a directive effect comparable with the
focussing of a beam of light by a lens or mirror. "
It is popularly believed that a radio beam has been
successfully focussed on Sydney, Australia, from Poldhu,
England, and this belief is no doubt due in some measure
to the title of Marconi's recent paper, " Results obtained
over very long distances by short wave directional wireless
telegraphy, more generally referred to as the Beam
System," in which communication with Australia was
mentioned. The paper itself, however, makes it clear that
this is riot so; moreover, the efficacy of such focussing
would need to be proved, not only at the objective, but at
other points outside of the prescribed path of the beam,
as is required, in fact, in the British contract (29).
The practicability and utility of the beam method of
transmission and reception of waves of the order of ten
metres in length appears to be unquestionable; but it is
early yet to form an estimate of the distance that may be
accomplished thereby (30). It has to be borne in mind
that the shorter the wave the greater is the limitation
upon the power that can be radiated : while the longer
the wave the greater are the difficulties of reflection and
94 Radio: Beam and Broadcast
focus until a parabolic reflector becomes out of the
question.
A useful method of precise measurement of short
waves has been evolved by the United States Bureau of
Standards, and is described in a paper by F. W. Dunmore
and F. H. Engel in the Proc. I.R.E. of October, 1923
(Vol. ii, pp. 467-478).
The higher telegraphic speeds that will be possible
with short waves as compared with those now in
general use will, of course, be largely facilitated by the
comparative smallness of the power required : even more
so than by the higher frequency.
It is necessary that there should now be an accepted
scientific definition of a " Radio Beam "; otherwise it would
be well to delete the term from our vocabulary. For the
purpose of the proposed Imperial Chain, it is defined as
having a width of 30, outside of which the strength
of the radiations must not exceed 5 per cent, of that at
the axis (29).
The possibilities of infinitely short electro-magnetic
waves have been demonstrated by the sun since the
creation, and our attention was directed to them by Clerk
Maxwell as long ago as 1867 j 1 moreover, in 1892, Sir
William Crookes foretold the use of longer but still short
electro-magnetic waves, in focussed radio-telegraphy. 3
Therefore it appears to be reasonable to hope that, at last,
the radio beam is to emerge from the stock-prospectus
into the field of practical telegraphy.
1 6eo p. 18. go* p. 33.
1896
12039 1 *
1899
14449
1900
1555
14558
1901
11003
Beam and Short-wave Radio 95
SOME PATENT SPECIFICATIONS RELATING TO BEAM RADIO
British
G. Marconi.
S. G. Brown.
E. G. Foresio.
G. F. R. Blochmann (use of lenses).
G. F. R. Blochmann and C. E. Bichel (use of
lenses).
A. N. Hovland.
II. W. Ladd.
De Forest.
H. Heinicke and M. Jasper.
G. Marconi (void) (reflector).
C. S. Franklin and others (reflector).
C. S. Franklin and others (reception of short
waves).
C. S. Franklin and others (generation of short
waves).
E. F. W. Alexanderson (directional aerial).
C. S. Franklin (reception of short waves).
19170
1903
15569
1906
19878
1912
18632
1916
105909 1
1917
128665 1
128673
1918
128983
130064
134246
744897 1
748597 1
1360167
American
F. Braun (reflector).
De Forest (reflector).
E. F. W. Alexanderson (directional aerial).
1 See Appendix.
2 U.S. Pats. 586,193 and re-issue 11,913.
CHAPTER IX
CONCLUSION
A CONSIDERATION of the cases of Hughes in 1879 and
Marconi in 1896 inevitably reminds one that " A prophet
is not without honour, save in his own country." The
appropriateness of the axiom is not affected by the fact
that Marconi achieved fame in Italy; because he had
first become famous in England.
It is to be regretted that someone did not give to
Hughes the encouragement and facilities for practical
experiment which, nearly twenty years later, the late Sir
William Preece gave to Marconi; but it must not be over-
looked that the need of a wireless telegraph system was
probably riot so urgently felt in 1879 as in 1896.
Prior to 1896, Preece had in operation a system of
inductive wireless telegraphy, and it was just when he
was smarting under the failure of this system to provide
communication with the East Goodwin Lightship, that
Marconi carne to him with a letter of introduction from
Mr. A. A. Campbell-Swinton. Both Lodge and Rutherford
had already shown that wireless telegraphy was practic-
able, and by the same essential method that was used by
Marconi; but apparently they did not see or were not
interested in its commercial potentialities, or were too
much engrossed in other activities to endeavour to exploit
them. This circumstance has, no doubt, contributed to
the fact that to-day the layman regards " Marconi " and
" Wireless " (or " Radio ") as interchangeable terms, while
the credit that is due to Hughes, Lodge, Popoff, Braun,
Fessenden, Stone and others, is in danger of being
forgotten, except by technicians.
There may be much to be said in favour of a monopoly
of a public utility; but if experience of radio teaches any-
thing, it is that there should be no private monopoly of
a public utility, which is based upon an undeveloped art.
96
Conclusion 97
In other words, it is obviously undesirable that a monopoly
should be so constituted that it might be concerned to
defeat or delay the adoption of any invention of merit.
This fact emerges most strongly from British experience,
and even the late Sir William Preece was concerned about
it. In 1907, when asked did he think that the practical
development of wireless telegraphy had been due to the
Marconi Company, he replied : " Not so very much, Sir.
I think myself if the Marconi Company, or Mr. Marconi
himself, had never appeared upon the scene we should
have had wireless telegraphy now." On the same occasion
he also gave it as his opinion that " the whole effect of
the operations of the Marconi Company has been to check
and really stop the growth of wireless telegraphy as a
convenience to navigators as well as a commercial
undertaking " (16).
The American story is somewhat different. Despite
the circus psychology and cavalier financing of its
promoters, the United Wireless Telegraph Company (own-
ing the De Forest patents) built up a very big business and
applied radio to the public service to an extent yet unheard
of in Europe; but by 1912 a situation had been created
which enabled the British Marconi interests to purchase
the assets of the company for $700,000-00 a condition
of the purchase being that the United Wireless Telegraph
Company should admit the validity of certain Marconi
patents, which they did (23).
The assets of the United Wireless Telegraph Company
in so far as they related to the American Company's
territory and the American patents of Sir Oliver Lodge,
were later sold to the American Marconi Company for
$1,488,800-00 in stock of the latter Company at par.
In November, 1919, the American Marconi Company
was absorbed into the Radio Corporation of America.,
which also acquired certain radio properties and rights
M Radio: Beam and Broadcast
from the General Electric Company, The Western Electric
Company, The American Telephone and Telegraph Com-
pany, The Westinghouse Electric and Manufacturing
Company, The International Radio Telegraph Company,
The United Fruit Company, and the Wireless Specialty
Apparatus Company.
Since its inception as a public utility, there have been
two, and only two, distinct waves of technical progress
in radio. The first came with the development of the
uses of the triode, and the Great War, when the art was
relieved of the incubus of private monopoly; and the
second came with the regular broadcasting of entertain-
ment, which started in Canada early in 1920, and led to
the placing of the development and manufacture of radio-
equipment on a more competitive footing.
Obviously there is a need of some legal machinery or
organization which, regardless of vested interests, will
facilitate the adoption of inventions of merit and public
utility, and ensure a fair reward to their authors.
In 1922 an " Australian Inventions Encouragement
Board " was formed, " to stimulate and encourage the
Inventive Spirit of the Nation. 15 If such a Board were
created in every country, and each affiliated with a common
central Board, we might again enjoy a wave of inventive
progress such as characterized the years 1914 to 1918,
without having to wait for another Armageddon.
The story of radio points yet another moral, and it is
that, regardless of prefix or suffix, Telephony is Telephony,
and Telegraphy is Telegraphy.
Radio is already in service as supplementary and
auxiliary to other forms of telephony, and its applica-
tions are extending. On the other hand and with the
exception of the British Post-OlTice-Telegraphs the big
telegraph organizations appear still to regard radio as a
sort of poor and suspected relation, and to be content to
Conclusion 99
leave its exploitation to others. This attitude is no doubt
nourished by the absurd claims of the stock-manipulators
and their " ballyhoos," who have beset radio from its
birth; but in view of the great progress made in the last
few years, its continuance is likely to prove unprofitable,
if not contrary to the public interest.
APPENDIX
THE following specifications of British and American patents, or
extracts therefrom, describe the more important steps in the evolution
of Radio. They are reproduced here by special permission kindly
granted by the Commissioner of Patents, Washington, D.C., and the
Controller of II. M. Stationery Office, London. The British specifica-
tion of Marconi's 1896-7 invention is " out of print," but a full copy
may be seen in Fahie's " History of Wireless Telegraphy " (1), from
which are quoted the extracts of that specification which appear
herein.
Copies of the specifications of American and British patents of
invention may be procured respectively from " The Chief Clerk,
Department of the Interior, United States Patent Office, Washington,
D.C.," and " The Superintendent, Patent Office, Sale Branch,
26 Southampton Buildings, London, W.C.2." The price of the
American is ten cents each, U.S. and Canadian postage free, and
the price of the British is one shilling each, inland postage free.
101
102 Radio: Beam and Broadcast
UNITED STATES PATENT OFFICE
FERDINAND BRAUN, OF STRASSBURG, GERMANY
MEANS FOR DIRECTING ELECTRIC WAVES FOR USE IN WIRELESS
TELEGRAPHY
SPECIFICATION (UNABRIDGED) FORMING PART OF LETTERS PATENT
NO. 744,897, DATED NOVEMBER 24, 1903
Application filed February 19, 1902. Serial /Vo. 94,729. (No model.)
To all whom it may concern:
Be it known that I, FERDINAND BRAUN, a subject of the Emperor
of Germany, residing at Strassburg, Germany, (whose post-office
address is No. 1 Universitatstrasse, Strassburg, Alsace, German Empire,)
have invented new and useful Improvements in Means for Directing
Electric Waves to be Used in Wireless Telegraphy, of which the
following is a specification.
The present invention relates to reflectors adapted for use in
connection with wireless telegraphy for the purpose of imparting to
the electric waves a certain direction of propagation.
It consists principally in a metallic grating of parabolic or similar
form constructed or arranged in a novel manner, hereinafter more
fully described.
The invention is shown in the accompanying drawings, of which
Fig. 1 is a diagrammatic view illustrating the theoretical physical
principle. Fig. 2 is a section of the new reflector. Fig. 3 is a
perspective view, while Fig. 4 represents an improvement of the
reflector by means of deflectors.
It is well known in optics that series of luminous lines located in
one plane and parallel to each other at equal distances apart and
having the same phase and amplitude of oscillation will produce what
is called in optical science a " wave front " which is a plane. These
lines are indicated in Fig. 1 by points A 1 A 2 A 3 A 4 , which represent
sections of the luminous lines making up the wave front normal to
the plane of the drawings. The same effect can also be obtained by
the arrangement of a parabolic mirror. If, for instance, in Fig. 2 F is
the luminous point and A 3 A 2 A 1 A 2 A 3 are parts of a parabolical mirror
of cylindrical shape, W 1 W 2 will indicate the wave front which is a
plane. This method may be employed for wireless telegraphy in the
following manner: A series of parallel rods A 3 A 2 A 1 A 2 A 3 are
arranged at equal distances from each other, so as to produce a
cylindrical parabolical mirror in the form of a grating. Each rod
is connected by a straight wire to a small ball F, set in the focus-line
of the mirror. As shown in Fig. 3, two sets of rods are provided
for, and between the two balls F F 1 set in the focus-line a spark is
generated from time to time by a Ruhmkorff apparatus or an electrical
static machine. (Not shown.) Now it will be evident that as all rods
are excited from the same centre and as the phase difference of the
Wig.
. 3.
i
Fig. 1.
104 Radio: Beam and Broadcast
oscillations of the single rods is determined by the length of the
corresponding wires the set of rods act in such manner as to generate
a wave front which must be in a plane. The wave motion therefore
will be essentially rectilineal. It is obvious that by these means the
greatest amount of the radiating energy will be guided in one
direction. The phenomenon is physically analogous to the ordinary
parabolic mirror and to Hertz's mirror for electric waves. Its
peculiarity, however, is that every rod fulfils its own oscillation,
provided it is tuned by ordinary means, as capacity and self-induction,
to the same periodicity.
The advantage of the new system over the ordinary metallic con-
tinuous parabolic mirror is that much more energy is set in action, as
the energy depends on the capacity of the single rods, which may be
increased by increasing the capacity of the rods and adding, for
instance, condensers to the same. A further advantage may be
secured by suitable additional rods a b c, Fig. 4, or similar bodies as,
for instance, human bodies. These bodies act to prevent lateral
deflection.
What I claim, and desire to secure by Letters Patent of the United
States, is
1. In mirrors for wireless telegraphy the combination of sets of
rods tuned to the same frequency arranged parallel to each other in
a parabolic cylindrical surface, spark-balls for electric disruptive
discharge, and wires connecting the balls and the said rods, sub-
stantially as and for the purpose described.
2. In mirrors for wireless telegraphy, the combination of sets
of rods tuned to the same frequency arranged parallel to each other
in a parabolic cylindrical surface, and spark-balls for electric
disruptive discharge, said balls being arranged in the centre line of
the parabolic cylindrical surface, as set forth.
3. In mirrors for wireless telegraphy, the combination of seta of
rods tuned to the same frequency arranged parallel to each other In
a parabolic cylindrical surface, spark-balJs for electric disruptive
discharge, said balls being arranged in the centre line of the parabolic
cylindrical surface, wires connecting the balls and said rods, and
deflecting rods arranged parallel to the said centre line, substantially
as and for the purpose described.
In testimony whereof I have hereunto set my hand in presence
of two subscribing witnesses.
FERDINAND BRAUN.
Witnesses :
MATHIAS CANTOR,
MARIA SCHORN.
Appendix 105
UNITED STATES PATENT OFFICE
LEE DE FOREST, OF NEW YORK, N. Y.
WIRELESS SIGNALLING DEVICE
SPECIFICATION (UNABRIDGED) FORMING PART OF LETTERS PATENT
NO. 748,597, DATED JANUARY 5, 1904
Application filed December 24, 1902. Serial Wo. 136,435. (No model.)
To all whom it may concern:
Be it known that I, LEE DE FOREST, a citizen of the United States,
and a resident of the city of New York, borough of Manhattan, in
the county and State of New York, have invented certain new and
useful Improvements in Wireless Signalling Devices, of which the
following is a specification.
My invention relates to an improvement in devices for use in
wireless signalling by which the radiated energy may be concentrated
in the direction desired, one feature thereof involving the use of a
reflector of the waves and another feature involving the use of
horizontal directive and concentrating conductors.
My invention comprises the novel features and parts and
combinations thereof, which will be hereinafter described, and
particularly pointed out in the claims.
Fig. 1 represents in perspective a reflector of a peculiar
construction. Fig. 2 shows in perspective another form of apparatus
involving my invention. Fig. 3 shows in plan the same form as
ghown in Fig. 2 except that lag or impedance coils are employed to
enable the antenna being placed near the reflector. Fig. 4 shows in
perspective a further modification, and Figs. 5 and 6 are respectively
plan and elevation of a modified construction.
It has heretofore been proposed to use a reflector for the waves
radiated from a sending-conductor or antenna, the same to consist of
a series of upright conductors which are disposed about the radiating-
antenna in a curved line, more or less corresponding with a segment
of a circle. So far as I am aware the conductors forming such a
reflector have been insulated or not grounded.
In accordance with my present invention I surround the
radiating-antenna A with a series of vertical conductors a, which may
be called " secondary " antenna*, said conductors being disposed
about the antenna A in a curve, which theoretically should be a
parabola having its focus in the antenna A. This theoretical
construction may, however, be departed from by means hereinafter
explained. The conductors forming the reflector are, however, each
grounded, either as in Fig. 1 by a direct ground connection E 1 or,
as is shown in the other figures, by a conductor B, which extends
horizontally in the direction it is desired to transmit the signals and
is there connected with a ground E through a secondary spark gap or
106 Radio: Beam and Broadcast
gaps S 1 . A spark gap S is placed at the base of the antenna A, which
may be charged by any suitable apparatus, a coil G, battery H, and
key I being herein shown for this purpose.
In the form of my device shown in Figs. 2 and 3 the vertical
conductors a, forming the reflector, each have their base connected
with the antenna A by a conductor D and are also each connected with
a conductor B, extending horizontally in the direction it is desired to
transmit the signal. These horizontal conductors are each grounded
at their outer ends through a secondary spark gap S 1 . This ground
connection should be removed from the antenna a distance corres-
ponding to a multiple of a quarter-wave length, preferably a half-wave
length. The secondary radiating-antennae a, forming the reflector,
should preferably be located at such a distance from the main or
primary antenna A that the waves radiated therefrom and travelling
in the direction of the conductors B will be in step or phase with
that part of the wave radiating from the primary antenna A, which
is travelling in the same direction. To secure this, the length of the
conductors connecting each of the reflecting or secondary antennae a
with the main antenna A added to the length of the conductors B,
connected thereto, should be equal to a half -wave length more than
the length of the conductor B, which is connected with the antenna
A. As it would in most instances be undesirable to separate the
primary and secondary antennae to such a distance, the same result
is obtained by interposing lag producing or retarding devices in the
conductors D, connecting the bases of antenna A and reflectors a
such, for instance, as the inductance-coils C. (Shown in Figs. 3
and 4.) The actual length of the conductors B may also be reduced
by inserting therein impedance-coils or other lag producing devices
after the manner usual when such a result is desired.
In Fig. 4 a modification is shown in which the conductors B are
replaced by a sheet of conducting material covering substantially the
same area as the conductors B.
Fig. 5 shows in plan, and Fig. 6 in elevation, a construction which
in the main is like that shown in Figs. 2 and 3. One structural
difficulty attendant upon the use of the rcllecting-conductors is that
their supports present so much surface to the wind and in such an
unsupported form that they are liable to be blown down. To remedy
this, I prefer to continue the supporting structure until its ends meet,
thus forming a complete inclosure, which would most naturally be
of a circular shape or approximating thereto. This structure except
for the reflecting-conductors or secondary antennae should be of such
material as will riot seriously interfere with the free passage of the
electric waves such, for instance, as wood. Such a structure is
shown at F in Figs. 5 and 6. I thus complete the curved form of the
reflector and strengthen it, so as to enable it to better resist the wind-
pressure and in addition do away with the exposed concave side which
catches the wind. Being of wood it offers no obstacle to the passage
of the waves. The horizontal conductors B or B 1 , extending outward
from the base of the antennae, co-operate with the antenna A and the
'** r
nn I
^r\f>
cy?^ '
tfXAUD
'
j^*-^.^
x^-^*
J
V^T^T^
VKM
ctJ \
J^ /S X 4
f
Fig. 3.
ft
Fig. II,
108 Radio: Beam and Broadcast
reflector-conductors or secondary antenna) a to give a directional effect
to the waves, whereby a much larger percentage than usual of the
electrical energy is directed along the plane of said conductors and
being once directed along this plane continues in that direction. I
am thereby enabled to secure a greater range and effect with a given
power.
The above feature is in addition to the reflection caused by the
conductors a and would occur if the conductors a were omitted. This
action is fully set forth and gcnerically claimed in a divisional
application for patent filed by me December 8, 1902, Serial No.
134,312, and is riot, therefore, herein broadly or separately claimed.
Having thus described my invention, what I claim, and desire
to secure by Letters Patent, is
1. In wireless signalling, the combination with an antenna and
means for communicating electric oscillations thereto, of a reflector
for said oscillations and a ground connection therefor containing a
horizontal conductor extending in the direction in which the waves
are reflected.
2. In wireless signalling, the combination with an antenna and
means for communicating electric oscillations thereto, of a reflector
for said oscillations and a ground connection therefor containing
a horizontal conductor extending a half-wave length beyond the
antenna in the direction in which the waves are reflected.
3. In wireless signalling, the combination with an antenna and
means for communicating electric oscillations thereto, of a reflector
comprising vertical conductors which are connected with the base of
the antenna and a conductor connected with the base of each of said
reflector-conductors and extending in the direction in which the waves
are reflected and a ground connection therefor located a half-wave
length beyond the antenna.
4. In wireless signalling, the combination with an antenna and
means for communicating electric oscillations thereto, of a series of
vertical conductors forming secondary antennae disposed about one
side of the primary antenna to form a reflector, a conductor connecting
each conductor of the reflector with the primary antenna, a horizontal
conductor extending from the base of each secondary antenna in the
direction in which the waves are reflected, a ground connection for
said horizontal conductors located at a multiple of a quarter-wave
length from the primary antenna, the length of the connection
between the base of the primary antenna and points in the horizontal
conductors abreast of the primary antenna being equivalent to a
half-wave length.
5. In wireless signalling, the combination with a radiating-
conductor and means for communicating electric oscillations thereto
of a reflector for said waves connected with the said wave-radiating
conductor, said connections containing lag-producing devices adapted
to cause the reflected waves to coincide in phase with the waves
directly radiated from the radiating-conductor and travelling in the
same direction.
Appendix 109
In testimony whereof I have hereunto affixed my signature, this
17th day of December, 1902, in the presence of two witnesses.
LEE DE FOREST.
Witnesses :
H. L. REYNOLDS,
ERNEST KNIGHT SATTERLEE.
SPECIFICATION OF BR. PAT. NO. 105,909 (VOID)
Convention Date (Italy), March 28, 1916
Application Date (in the United Kingdom), March 27, 1917.
No. 4427/17
Complete not accepted
COMPLETE vSPECIFIC'ATION
IMPROVEMENTS IN WIRELESS TELEGRAPHY AND TELEPHONY
I, GUGLIELMO MARCONI, G.C.V.O., of Marconi House, Strand,
London, W.C.2, do hereby declare the nature of this invention and
in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:
This invention relates to an improvement in wireless telegraphy
and telephony and is based on reflection phenomena; by means of it
the waves can be directed and confined to a predetermined direction
and reception can also be limited to waves proceeding from one
direction.
The advantages achieved are as follows:
1. Greater range of transmission.
2. Greater freedom from interference between stations working
in the vicinity of each ether.
3. The possibility of accurately determining the direction in
which a transmitting station lies.
4. A lessening of all disturbances caused by the natural electrical
perturbations of the atmosphere.
According to this invention there is arranged about the usual
antenna of the transmitting or receiving station, a number of parallel
antennae which lie in a parabola of which the focus is the trans-
mitting or receiving antenna. These antennae are tuned to the
length of the waves to be transmitted or received. These additional
antennae act as reflectors of the waves which are thus transmitted and
received in the direction of the axis of the parabola, and when two
stations communicate with one another the axes of their reflecting
parabolas should be coincident.
The invention is illustrated by the accompany ing drawing, 1 in
P. 111.
110 Radio: Beam and Broadcast
which Fig. 1 shows sending and receiving stations, while Fig. 2 shows
a modification.
In Fig. 1, A is a transmitting station and B a receiving station,
a is the generator, b the receiver and c are the reflecting antennae.
In the form shown in Fig. 2, the reflecting antennae consist of
wires e which have inductances inserted in them for the purpose of
tuning and are suspended from a frame d supported by guys /.
The antennae may be earthed or not.
The apertures of the parabolas should be as large as is practically
possible and preferably not less than the length of the waves
employed.
The focal distance of the parabola should be preferably of the
order of J, f, , etc., of the wave length employed. The antennae
of a reflector system may be placed at a distance from each other
equal to ^ of their height. Reflection will be more complete the
greater the number of the antennae.
The antennae of the reflector system may be syntonized by the
ordinary methods; i.e., by the employment of suitable and adjustable
inductances or condensers.
Having now particularly described and ascertained the nature of
my said invention and in what manner the same is to be performed,
I declare that what I claim is:
In radio-telegraphy or radio-telephony, a number of syntonized
antennae arranged in a parabola about the transmitting or receiving
antenna at the focus.
Dated this 27th day of March, 1917.
CARPMAELS & RANSFORD,
Agents for Applicant,
24 Southampton Buildings, London, W.C.2.
SPECIFICATION OF BR. PAT. NO. 128,665
Application Date, August 29, 1917. Wo. 12,441/17
Complete Left, March 26, 1918
Complete Accepted, July 3, 1919
COMPLETE SPECIFICATION (UNA BRIDGED)
IMPROVEMENTS IN REFLECTORS FOR TJSE IN WIRELESS TELEGRAPHY
AND TELEPHONY
We, MARCONI'S WIRELESS TELEGRAPH COMPANY, LIMITED, and
CHARLES SAMUEL FRANKLIN, Electrical Engineers, both of Marconi
House, Strand, London, W.C.2, do hereby declare the nature
of this invention (in part a communication from Guglielmo
Marconi, G.C.V.O., D.Sc., at present at the Hotel Excelsior, Rome,
\a/
**
c-
l\
\
J8
Fig. III. Marconi's British Patent 105,909 (Void). See pp. ioo-no.
112 Radio: Beam and Broadcast
Italy), and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following
statement:
This invention relates to improvements in the use of reflectors
for transmitters and receivers in wireless telegraphy and telephony.
The use of a reflector for directing the energy of a wireless
transmitter in any desired direction has been many times suggested.
The advantages to be expected from thus directing the energy in the
desired direction (such as increase of range, avoidance of interference
of all kinds, and comparative secrecy) are so great, that it is rather
surprising that since the early work of Hertz and Marconi no practical
results have been obtained by the use of reflectors.
Hertz showed that by placing an oscillator in the focus of a
reflector bent in the form of a cylindrical parabola, the energy was
directed sensibly in one direction.
In 1896 Marconi, using his improved coherer, obtained a range
of about three miles with an oscillator placed at the focus of a
reflector, and the receiving conductor also placed at the focus of a
reflector.
In 1901, Braun took out Patents in Germany Nos. 146,302 and
146,303, with a corresponding Patent in America No. 744, 897, l for
a reflector made of two scries of parallel rods arranged above each
other and in the form of a cylindrical parabolic mirror. The nearer
ends of the two sets of rods were connected by means of wires to
spark-balls, placed in the focus of thm mirror. It is stated in the
American patent that " it will be evident that as all the rods are
excited from the same centre and as the phase difference of the
oscillations of the single rods is determined by the length of the
corresponding wires, the sets of rods act in such a manner as to
generate a wave front which must be in a plane. The wave front
therefore will be essentially rectilineal." In fact, the construction
described simply gives a Hertz oscillator of a peculiar shape which
has a wave length much longer than the natural wave length of the
separate rods, and which has practically no directional properties.
In 1902, De Forest applied for a patent in America (granted
in 1904 under No. 748, 597) 2 describing a reflecting system in
combination with a scries of wires extending in the direction in which
it is desired to send the energy and which, it is alleged, helps
concentration in this direction. Fig. 1 of the drawings shows a
system comprising a vertical aerial placed at the focus of a reflecting
system consisting of a number of vertical aerials disposed in a
parabolic curve, all the aerials being grounded. The inventor states
that he believes the grounding of all the aerials to be novel and
describes means for increasing the concentration in the desired
direction by horizontal wires disposed in various ways.
A reflecting system comprising a number of wires or rods
disposed as a cylindrical parabola and all tuned to the s$me warg
1 See p. 102 * See p. 10.
I I I I I I
\ MINN
I
I
I
T
Fig. IV.
H
114 Radio: Beam and Broadcast
length as that of a transmitter placed at the focus thereof is
accordingly not novel, while it is also known that in order that the
reflected waves and the direct waves should unite their effects in the
desired direction, the focal length of the reflector should be /one, three,
or an odd multiple of a quarter wave length. Such a system gives a
certain amount of concentration in the desired direction, and we have
found that this is strongest if the focal length is one-quarter wave
length, weaker if the focal length is three-quarter wave length, and
hardly appreciable if the focal length is five-quarter wave length or
more. At best, with this simple system about 80% is the maximum
increase in range hitherto obtained when using such reflectors both
at the transmitting and receiving ends.
According to this invention, we construct a reflector of two or
more sets of rods (which term includes strips and wires) arranged on
a parabolic surface around the transmitting or receiving aerial as a
focus, each rod being tuned to the aerial and the rods of the different
sets being preferably in line with each other. By this means we are
enabled to increase very largely the efficiency and effect of the
reflector; for example, by making the reflector of three sets of rods
arranged on a parabolic surface and having a focal distance of one-
quarter wave length, we can increase the range from 400% to 600%
as against 80% obtained with the simple reflectors before known.
The reflector may be described in other words as follows:
On a parabolic surface surrounding a transmitter or receiver and
in the correct direction having regard to the polarization of the
transmitted waves, is arranged a number of long wires which are
divided up into elements each in tune with the transmitter. The
length of each element is preferably about half a wave length, but
may be made either greater or less than this by inserting in it either
a condenser or an inductance. The adjacent ends of these elements
may be insulated from each other, or joined by inductance coils or
condensers, the controlling factor being that each element when in
its working position in the reflector, is in tune with the aerial.
In practice we find that some of the elements may be removed
slightly from the true parabolic surface provided that those elements
of the reflector which are nearer the focus than they would be if on
the parabolic surface are tuned to a rather longer wave, and those
elements which are farther to a rather shorter wave.
For very short waves no earth connections are required or
desirable, but for longer waves it is an advantage to earth the aerial
and the lower elements of the reflector.
Very good results can be obtained by arranging the elements on
a cylindrical parabolic surface, but better results can be obtained by
arranging them on a true paraboloid, particularly when using a
reflector having a focal length equal to three-quarter wave length
or more.
Our invention is illustrated by the accompanying drawings.
Fig. 1 is a plan, Fig. 2 a rear view and Fig. 3 a side view of a reflector
constructed in accordance with this invention and having three sets
Appendix 115
of parallel rods arranged on a cylindrical parabolic surface; this
arrangement is for concentrating vertically polarized waves in the
horizontal direction. Figs. 4, 6 and 6 are similar views of an
arrangement for concentrating horizontally polarized waves in the
horizontal direction. Figs. 7, 8 and 9 are similar views of a reflector
having three sets of parallel rods arranged on a true paraboloid
instead of a cylindrical parabola; this will concentrate both vertically
and horizontally polarized waves in the horizontal direction.
These figures illustrate reflectors made with three sets of parallel
rods, or, stated otherwise, reflectors made up of a number of wires
each divided into three elements, each element being in tune with
the transmitted or received wave. As illustrated, each of these
elements should be nearly half a wave length long; alternatively each
of these wires may be divided up into a larger number of elements
connected together by condensers.
Fig. 10 shows one wire divided into three elements each in tune
with the desired wave.
Fig. 11 shows one wire divided into a number of shorter
elements connected together by condensers. The capacity of each
condenser must be such that if joined in circuit with the inductance
of the wire joining it to the next condenser it would form a circuit
in tune with the desired wave.
Having now particularly described and ascertained the nature of
our said invention and in what manner the same is to be performed,
we declare that what we claim is:-
1. In wireless telegraphy, a reflector consisting of two or more
sets of rods arranged on a parabolic surface around a transmitting or
receiving aerial as a focus, each rod being in tune with the aerial,
substantially as described.
2. A modification of the reflector claimed in Claim 1, in which
some of the elements are slightly removed from the parabolic surface,
those which are brought nearer to the aerial being tuned to a longer
wave and those which arc removed further from it being tuned to a
shorter wave.
Dated the 26th day of March, 1918.
CARPMAELS & RANSFORD,
Agents for Applicants,
24 Southampton Buildings, London, W.C.2.
116 Radio: Beam and Broadcast
EXTRACTS FROM THE SPECIFICATIONS OF BR. PAT.
NO. 12,039/1896
Date of Application, 2nd Jane, 1896
Complete Specification Left, 2nd March, 1897
Accepted, 2nd July, 1897
PROVISIONAL SPECIFICATION
I, GUGLIELMO MARCONI, of 71 Hereford Road, Bayswater, in the
county of Middlesex, do hereby declare the nature of this invention
to be as follows :
According to this invention electrical actions or manifestations
arc transmitted through the air, earth or water by means of electric
oscillations of high frequency.
When transmitting through the air, and it is desired that the
signal or electrical action should only be sent in one direction, or
when it is necessary to transmit electrical effects to the greatest
possible distance without wires, I place the oscillation producer at
the focus or focal line of a reflector directed to the receiving station,
and I place the tube or imperfect contact at the receiving instrument
in a similar reflector directed towards the transmitting instrument.
When transmitting through the earlh or water I connect one
end of the tube or contact to earth and the other end to conductors
or plates, preferably similar to each other, in the air and insulated
from earth.
I find it also better to connect the tube or imperfect contact to
the local circuit by means of thin wires or across two small coils of
thin and insulated wire preferably containing an iron nucleus.
Dated this 2nd day of June, 1896.
GUGLIF.LMO MARCONI.
COMPLETE SPECIFICATION
My invention relates to the transmission of signals by means of
electrical oscillations of high frequency, which are set up in space or
in conductors.
In order that my specification may be understood ... I will
describe the simplest form of my invention by reference to Fig. 1.
In this diagram A is the transmitting instrument and B is the
receiving instrument, placed at say J mile apart.
The arrangement A is commonly called a Hertz radiator, and
the effects which propagate through space Hertzian rays. The
receiving instrument B consists of a battery circuit J, which includes
a battery or cell K, a receiving instrument L, and a tube T containing
metallic powder or filings, each end of the column of filings being
- f~l
' i ti&zs?i!3fft i '
\* Vtf
Fig. I.
r
Fig. V.
118 Radio: Beam and Broadcast
also connected to plates or conductors M N of suitable size, so as to be
preferably tuned with the length of wave of the radiation emitted
from the transmitting instruments.
The tube containing the filings may be replaced by an imperfect
electrical contact, such as two unpolished pieces of metal in light
contact, or coherer, etc.
Fig. 4 is a vertical section of the radiator or oscillation producer
mounted in the focal line of a cylindrical parabolic reflector / in
which a side view of the spheres e e of Fig. 3 is given.
My invention relates in great measure to the manner in which
the above apparatus is made and connected together. With some of
these forms I am able to obtain Morse signals*, and to work ordinary
telegraphic instruments and other apparatus; and with modifications
of the above apparatus it is possible to transmit signals riot only
through comparatively small obstacles such as brick walls, trees, etc.,
but also through or across masses of metal, or hills, or mountains,
which may intervene between the transmitting and receiving
instruments.
I will first describe my improvements which are applicable to
the receiving instruments.
My first improvement consists in automatically tapping or
disturbing the powder in the sensitive tube. . . .
A further improvement consists in the mode of construction of
the sensitive tube.
In order to increase the distance at which the receiver can be
actuated by the radiation from the transmitter, I place the receiver
(i.e., the sensitive tube and plates) in the focal line of a cylindrical
parabolic reflector I (Fig. 2), preferably of copper, and directed
towards the transmitting station.
The reflector I (Fig. 2) should be preferably in length and opening
not less than double the length of wave emitted from the transmitting
instrument.
It is slightly advantageous for the focal distance of the reflector
to be equal to one-fourth or three-fourths of the wave-length of the
oscillation transmitted. . . .
A further improvement has for its object to prevent the electrical
disturbances which are set up by the trembler and other apparatus in
proximity or in circuit with the tube from themselves restoring the
conductivity of the sensitive tube immediately after the trembler has
destroyed it, as has been described.
Another improvement consists in a modified form of the plates
connected to the sensitive tube, in order to make it possible to tnount
the receiver in an ordinary circular parabolic reflector. This part of
my invention is illustrated in Fig. 8, in which I is an ordinary
'Oarjf 1
f
Fig. 3.
Fig. 5.
Fig. 6^.
A,/
0X0
% Fig.8.
Fig. Vtf.
V
J
&6
\
Fig. 4.
120 Radio: Beam and Broadcast
concave reflector. In this case the plates k k are curved and
connected at one end to the sensitive tube /, and at the other to a
small condenser formed by two metallic plates fe2 of about one inch
square or more, facing each other with a very thin piece of insulating
material ft3 between them, p is the trembler. The condenser may
be omitted without much altering the effects obtainable.
The receiver should be put in such a position as to intercept the
reflected ring of radiations which exists behind or before the focus of
the reflector, and ought to be preferably tuned with the length of
wave of the oscillation transmitted. . . .
I will now describe my improvements which are applicable to
the transmitting instruments.
My first improvement consists in employing four spheres for
producing the electric oscillations.
>
When it is desired that the signal should only be sent in one
direction, I place the oscillation producer in the focus or focal line of
a reflector directed to the receiving station. / (Fig. 3) and / (Fig. 4)
show the cylindrical parabolic reflector made by bending a metallic
sheet, preferably of brass or copper to form, and fixing it to metallic
or wooden ribs / I (Fig. 3). Other conditions being equal, the
larger the balls the greater is the distance at which it is possible to
communicate. I have generally used balls of solid brass of 4 inches
diameter, giving oscillations of 10 inches length of wave. . . .
Preferably the reflector applied to the transmitter ought to be in
length and opening the double at least of the length of the wave
emitted from the oscillator.
If these conditions are satisfied, and with a suitable receiver, a
transmitter furnished with spheres of 4 inches diameter connected to
an induction coil giving a 10-inch spark will transmit signals to two
miles or more.
A further improvement consists in causing one of the contacts
of the vibrating brake applied to the induction coil to revolve
rapidly.
A further improvement has for its object to facilitate the
focussing of the electric rays. This part of my invention is illustrated
in Fig. 7, in which a view is given of the modified 'oscillation
producer mounted in the focus of an ordinary parabolic reflector /.
It is not essential to have a reflector at the transmitters and
receivers, but in their absence the distance at which one can
communicate is much smaller. Fig. 9 shows another modified form
of transmitter with which one can transmit signals to considerable
distances without using reflectors.
I have observed that, other conditions being equal, the larger the
Fig. 7.
Fig. 8.
r
Fig. 9.
Fig. 10.
Pig. 11.
J
^i
Fig. 12.
C.J5L.
Fig. 13.
Fig. 14.
Fig VA.
122 Radio: Beam and Broadcast
plates at the transmitter and receiver, and the higher they are from
earth, and to a certain extent the farther apart they are, the greater
is the distance at which correspondence is possible.
Where obstacles, such as many houses or a hill or mountains,
intervene between the transmitter and the receiver, I have devised
and adopt the arrangement shown in Figs. 10 and 11.
. . ^ .
At the receiver it is possible to pick up the oscillations from the
earth or water without having the plate w. This may be done by
connecting the terminals of the sensitive tube j to two earths,
preferably at a certain distance from each other and in a line
with the direction from which the oscillations are coming. These
connections must not be entirely conductive, but must contain a
condenser of suitable capacity, say of one square yard surface
(paraffined paper as dielectric).
Balloons can also be used instead of plates on poles, provided
they carry up a plate or are themselves made conductive by being
covered with tinfoil. As the height to which they may be sent is
great, the distance at which communication is possible becomes
greatly multiplied. Kites may also be successfully employed if made
conductive by means of tinfoil.
When working the described apparatus, it is necessary either
that the local transmitter and receiver at each station should be at a
considerable distance from each other, or that they should be screened
from each other by metal plates. It is sufficient to have all the
telegraph apparatus in a metal box (except the reading instrument),
and any exposed part of the circuit of the receiver enclosed in
metallic tubes which are in electrical communication with the box
(of course the part of the apparatus which has to receive the radiation
from the distant station must not be enclosed, but possibly screened
from the local transmitting instrument by means of metallic sheets).
CLAIMS
1. The method of transmitting signals by means of electrical
impulses to a receiver having a sensitive tube or other sensitive form
of imperfect contact capable of being restored with certainty and
regularity to its normal condition substantially as described.
3. A receiving instrument consisting of a sensitive imperfect
contact or contacts, a circuit through the contact or contacts, and
means for restoring the contact or contacts, with certainty and
regularity, to its or their normal condition after the receipt of an
impulse substantially as described.
3. A receiving instrument consisting of a sensitive imperfect
contact or contacts, a circuit through the contact or contacts, and
means actuated by the circuit for restoring with certainty and
Appendix 128
regularity the contact or contacts to its or their normal condition
after the receipt of an impulse.
4. In a receiving instrument such as is mentioned in claims 2
and 3, the use of resistances possessing low self-induction, or other
appliances for preventing the formation of sparks at contacts or other
perturbating effects.
5. The combination with the receivers such as are mentioned in
claims 2 and 3 of resistances or other appliances for preventing the
self-induction of the receiver from affecting the sensitive contact or
contacts substantially as described.
6. The combination with receivers such as herein above referred
to of choking coils substantially as described.
7. In receiving instruments consisting of an imperfect contact
or contacts sensitive to electrical impulses, the use of automatically
working devices for the purpose of restoring the contact or contacts
with certainty and regularity to their normal condition after the
receipt of an impulse substantially as herein described.
8. Constructing a sensitive non-conductor capable of being
made a conductor by electrical impulses of two metal plugs or their
equivalents, and confining between them some substance such as
described.
9. A sensitive tube containing a mixture of two or more powders,
grains, or filings, substantially as described.
10. The use of mercury in sensitive imperfect electrical contacts
substantially as described.
11. A receiving instrument having a local circuit, including a
sensitive imperfect electrical contact or contacts, and a relay operating
an instrument for producing signals, actions, or manifestations
substantially as described.
12. Sensitive contacts in which a column of powder or filings (or
their equivalent) is divided into sections by means of metallic stops or
plugs substantially as described.
13. Receivers substantially as described and shown in Figs. 5
and 8.
14. Transmitters substantially as described and shown at Figs. 6
and 7.
15. A receiver consisting of a sensitive tube or other imperfect
contact inserted in a circuit, one end of the sensitive tube or other
imperfect contact being put to earth whilst the other end is connected
to an insulated conductor.
16. The combination of a transmitter having one end of its
sparking appliance or poles connected to earth, and the other to an
insulated conductor, with a receiver as is mentioned in claim 15.
17. A receiver consisting of a sensitive tube or other imperfect
contact inserted in a circuit, and earth connections to each end of the
sensitive contact or tube through condensers or their equivalent.
18. The modifications in the transmitters and receivers, in which
the suspended plates are replaced by cylinders or the like placed hat-
wise on poles, or by balloons or kites substantially as described.
124 Radio: Beam and Broadcast
19. An induction coil having a revolving make and break
substantially as and for the purposes described.
Dated this 2nd daj of March, 1897.
GUGLIELMO MARCONI.
EXTRACTS FROM SPECIFICATIONS OF BR. PAT. NO. 11,575,
A.D. 1897
Date of Application, May 10, 1897
Complete Specification Left, February 5, 1898
Accepted, August 10, 1898
PROVISIONAL SPECIFICATION
IMPROVEMENTS IN SYNTONIZED TELEGRAPHY WITHOUT LINE WIRES
I, OLIVER JOSEPH LODGE, D.Sc., F.R.S., of 2 Grove Park,
Liverpool, in the County of Lancaster, Professor of Physics, do hereby
ieclare the nature of this invention to be as follows:
The object of niy invention is to enable an operator to transmit
messages across space to any one or more of a number of different
ndividuals in various localities, each of whom is provided with a
mitably arranged receiver.
The method consists in utilizing certain processes and apparatus
or the purpose of producing and detecting rapid electric oscillations,
md in so arranging them that the excitation of a particular frequency
)f oscillation at the sending station may cause a Morse or any other
.elegraphic instrument to respond at a distant station, by reason of
>eing associated, through a relay or otherwise, with a subsidiary
circuit actuated by electric oscillations of that same particular
'requency, or by some multiple or sub-multiple of that frequency.
Another distant station will similarly be made to receive messages by
exciting at the sending station alternations of a different frequency,
md so on; and thus individual messages can be transmitted to
ndividual stations without disturbing the receiving appliances at
>ther stations which are tuned or timed or syntonized to a different
requency. Each station will usually be provided with both sending
ind receiving apparatus, and messages can travel simultaneously
n opposite or in cross directions without the least confusion or
nterference.
The sending apparatus consists of a suitable condenser or Leyden
ar or other electric capacity (large or small) charged by an electrical
nachine or induction coil, or battery, or any other well-known means,
o some considerable potential, and then discharged suddenly with a
park of any required length or shortness, occurring between suitably
rranged and prepared surfaces immersed in a gaseous or a liquid
Appendix 125
medium or in vacua or in ordinary air, through a wire or other local
circuit, or through the gas or water pipes of a town, or through any
other local conductors which may be convenient, having coils of wire
inserted or removed or shifted relatively to each other at will for the
purpose of attaining any desired frequency of electric oscillation.
The frequency can be adjusted either by varying the capacity of the
condenser or jar or other conductor employed as the charged body,
on the one hand, or by varying the number and position of coils or
other portions of the discharge circuit, on the other. By means of
suitable keys I propose to change easily from one rate of oscillation to
another, and thus signal first to one station and then to another,
using the appropriate key for each station, and manipulating it, or
some other key or sending instrument in conjunction with it, so as
to evoke dots and dashes or any other of the known forms of
telegraphic signal at the desired station or set of stations.
The electric oscillations set up by a discharging jar have long
been known to science, arid the fact that such oscillations excite
at a certain distance electric waves which travel through space and
material bodies with the velocity of light was demonstrated by Hertz
in 1888. I propose to employ a special combination of capacities
with conductors or coils so arranged as to give electric oscillations of
any desired frequency, so arranged also as to enable the frequency to
be varied with ease and certainty, and so arranged that their effects
may be transmitted to a distance either through the air or through
the ground or through conductors present for olher purposes or
through any intervening medium whatever.
As a means of receiving or detecting those electric waves or
oscillations, no matter whether the receiving station be within or
beyond the distance at which true simply-progressive waves arise, I
propose to use an instrument based on the " coherer " principle
discovered by myself for metal in 1889 (Journal of the Institute of
Electrical Engineers, Part 87, Vol. XIX, pp. 352-351, re-printed in
" Lightning Conductors and Guards/ 9 pp. 382-384), and by Lord
Rayleigh for liquids many years previously, and applied by Branly
to the detection of electric waves in 1890 (see my book on " The Work
of Hertz and Some of His Successors," pp. 21-24).
The " coherer," for the purpose of this invention, depends on
the property which metals and liquids and other substances possess
of uniting or cohering more readily under slight electric influence
than when brought into mere gentle contact without such influence.
Thus, at the delicately adjusted junction of two metallic or other
substances, a feeble electric current, such as is sufficient to work a
telegraphic relay, finds it easier to pass after the metals have been
subjected to the influence of electric oscillations, e.g., of any distant
electric spark or discharge, than before such influence. The original
greater resistance of the light contact can be restored by a slight
mechanical vibration or shock, which can be maintained automatically
by any convenient means, such as the friction or percussion of clock-
work, or electrical make and break, or any other shaking or
126 Radio: Beam and Broadcast
trembling mechanism, as demonstrated by me before the British
Association at Oxford in 1894 in a communication entitled " an
electric eye and a hypothesis concerning vision " (see the work of
Hertz., etc., p. 27); or, as I prefer in carrying out this invention, by
means of a continuous sound, or sound board, or by means of a
coherer contact on a rotating disc or drum or other moving surface;
or in general any plan whereby metallic or other contacts are
established or improved by electrical means arid broken or impaired
by mechanical means; and whether these contacts be in air or any
other medium, including vacuum.
I have also shown a pair of syntonized electric circuits, whereby
electrical oscillations set up in the one are able to cause another to
respond only when it is exactly " tuned " to the same frequency of
vibration; a very slight change in cither the capacity or the self-
induction of either circuit being sufficient to throw the correspondence
out. This exactitude or approximate exactitude of response depends
on the fact that the total number of oscillations in a suitably arranged
circuit is very great, so that a very feeble impulse is gradually
strengthened until it causes a perceptible effect, on the well-
known principle of sympathetic resonance. See " Modern Views of
Electricity," pp. 338-340, or " Nature," Vol. XL., p. 368, 1890; also
my book on the work of Hertz, etc., pp. 5 and 7.
In carrying out this invention, I propose to associate with a
coherer as above described such a definitely adjusted electric circuit,
to the end that the electric oscillations purposely excited at a distant
station in another syntonized circuit may excite in the first one a
response sufficient to disturb and temporarily alter the resistance of
the coherer associated with it, so as to enable the current of a local
cell or battery to pass more easily, and thereby to give any required
telegraphic signal, whether by means of a relay and auxiliary battery
or otherwise. There will thus be a pair of syntonized circuits, one
associated with a condenser and used as transmitter, the other
associated with a coherer arid used as receiver.
The ordinary Hertz vibrator, and still more the radiating spheres
which I have myself heretofore employed with a receiving coherer,
are powerful radiators, but the vibrations are for this very reason so
rapidly damped that no precision of tuning is possible; and therefore
such apparatus if employed in a system of telegraphy depending on
Hertzian waves is liable to disturb all receivers within range, instead
of an intended selection of them. But if, as in the arrangement I
employ in carrying out this invention, the radiator be partially
enclosed in a metallic box or cylinder of any shape, or if an
arrangement of more electrostatic capacity be employed, then
although the radiation becomes less powerful, the total number of
swings is so much increased that it may be made as ultimately
effective at a distance as the single powerful swing; and it has the
advantage of permitting precise tuning or syntonizing, so that any
desired one of a number of receivers may be affected and not any of
the others. Part of this invention consists therefore in an arrange-
Appendix 127
ment whereby this desideratum becomes practically possible, as
already explained, on the principles here laid down.
Dated this 8th day of May, 1897.
WM. P. THOMPSON & CO.,
6 Lord Street, Liverpool,
Patent Agents for the Applicant.
COMPLETE SPECIFICATION (ABRIDGED)
... In the accompanying drawings which arc diagrammatic
representations,
Fig. 1 shows the simplest arrangement of emitter and receiver
heretofore in use. ..........
In carrying out my invention and referring now to the subsequent
figures of the drawings, I use a definite radiator, consisting of a
conductor, or pair of conductors h h l of large capacity arranged
either as a Leyden jar or preferably spread out separately in space
(one of them being the earth when desired). I join to h and h j
respectively (which I denominate " capacity areas ") a pair of polished
knobs h 2 h 3 (protected by glass from ultra violet light) which form
the adjustable spark gap called the " discharge gap." Between either
capacity area and its knob I place a syntonizing self-inductance coil;
that is a coil of wire or metallic ribbon /i 4 , preferably insulated with
any solid or fluid insulator, as in Fig. 2, or in air, of shape suitable
to attain greatest inductance with a given amount of resistance; the
object of this coil being to prolong the electric oscillations occurring
in the radiator, so as to constitute it a radiator of definite frequency
or pitch, and obtain a succession of true waves emitted, and thereby
to render syntony in a receiver possible, because exactitude of
response depends on the fact that the total number of oscillations in
a suitably arranged circuit is very great, so that a very feeble impulse
is gradually strengthened till it causes a perceptible effect, on the
well-known principle of sympathetic resonance.
I supply the electricity to the radiator from a Buhmkorff or a
Tesla coil or a Wimshurst or other known or suitable high tension
machine a in one of three ways according to circumstances.
On the third plan as indicated in Fig. 4, I interpose in each of
the wires h s leading from the Ruhmkorff coil a to the supply knobs
a Leyden jar or other suitable condenser j able to stand a high
potential, so that the knobs are supplied from the outer that is the
uninsulated coat of each jar, while between the inner coats or coil
terminals I arrange a third spark gap called the starting gap, also
consisting of suitable knobs /i 10 ft. 11 . The outer coats of the jars
must not be insulated from each other, and I usually join them by a
self-inductance coil of fairly thin wire k so as to permit thorough
charging. When the discharge occurs, this wire acts as an alternative
128 Radio: Beam and Broadcast
path or by-pass, but does not prevent the sparks at the supply
gaps.
By both of the means described with reference to Figs. 3 and 4,
I charge the two capacity areas h Ji 1 , which together with the
inductance coil between them constitute the radiator by aerial
disruption or impulsive rush. The advantage of this is that charges
so communicated are left to oscillate free from any disturbance due
to maintained connection with the source of electricity, and therefore
oscillate longer and more simply than when supplied by wires in the
usual way; moreover the capacity areas of a radiator are thus more
conveniently employed as the capacity areas of a receiver without need
of disconnection.
The arrangement described with reference to Fig. 4 illustrates
most completely the method of charging the capacity areas h h l with
an impulsive rush.
The action is as follows:
The Ruhmkorff machine a charges the jars y, whose outer coats
are connected, and discharges them at the starting gap /i 10 . This
spark precipitates a discharge at the supply gaps h 7 h* and suddenly
supplies the capacity areas h h 1 with electric charges, which then
surge through the connecting coil h* (divided into two parts in this
figure) and spark into each other at the discharge gap between the
knobs h 2 h 3 . This last discharge is the chief agent in starting the
oscillations which are the cause of the emitted waves. But it is
permissible in the arrangements of Figs. 3 and 4 to close this last
gap when desired and so leave tho oscillations to be started by the
sparks at the supply gaps only, whose knobs must in that case be
polished and protected from ultra-violet light so as to supply the
electric charge in as sudden a manner as possible.
As charged surfaces or capacity areas, spheres or square plates
or any other metal surfaces may be employed, but I prefer, for the
purpose of combining low resistance with great electrostatic capacity,
cones or triangles or other such diverging surfaces, with the vertices
adjoining and their larger areas spreading out into space. Or a
single insulated surface may be used in conjunction with the earth,
the earth or conductors embedded in the earth constituting the other
oppositely charged surface. Radiation from an oscillator consisting
of a pair of capacity areas is greater in the equatorial than in the
axial direction, and accordingly, when sending in all directions is
desired, it is well to arrange the axis of the emitter vertical. More-
over, radiation polarized in a horizontal plane, that is with its electric
oscillations vertical, is less likely to be absorbed during its passage
over partially conducting earth or water. A pair of insulated capacity
areas arranged for long-distance signalling is shown on the left-hand
side of Fig. 5.
Fig. 6 shows a single insulated capacity area h with the earth
acting as the other surface and leading up to the spark knobs fc a h 5
by a triangular sheet or cone h 1 so as to afford good conductance
even to rapidly alternating currents. The wire h 9 in this case leads
Figr. VI,
130 Radio: Beam and Broadcast
to one terminal of the Ruhmkorff coil a, the other terminal of which
is taken to earth as shown. The capacity area h is insulated as
indicated at h 12
A coherer consists of any arrangement which drops in resistance
on receipt of an electric impulse, and rises to its old resistance on
being subjected to a mechanical impulse such as a tremor or a tap.
A coherer circuit is any known arrangement for observing or
recording effects due to fluctuations in the electrical resistance of a
coherer.
As coherer I may use Branly's arrangement of a pair of
conductors embedded in metallic grains or powder or filings, but I
prefer selected iron filings of uniform size sealed up in a good vacuum
and with the communicating surfaces or electrodes reduced to points
or thin platinum wires fused into the glass and with their ends close
together
Whenever an electric wave or impulse from a distant radiator
arrives and stimulates electric vibrations in the syntonized resonator
or absorber arranged for the purpose, the delicately adjusted junction
of the two metals or of the metallic or other particles which are
connected up to the resonator so as to feel these vibrations suddenly
and greatly changes its electrical resistance, and this diminished
resistance enables a local battery to actuate a relay or a telephone or
other telegraphic instrument in circuit therewith.
To break contact again, or to restore the original greater
resistance, any form of mechanical vibration suffices.
The diminution of resistance takes place instantaneously, and con-
tact is broken again in a very small fraction of a second later. The
instant it is broken the junction is ready to receive a fresh signal.
The rapidity of signalling depends on the quickness of response of
the signalling instrument, and it depends also on the rapidity with
which the mechanical arrangement can break or interrupt the
cohesion directly after the electrical stimulus has established it.
When a telephone is used I find that the coherer restores itself
sufficiently without specially arranged tremor and that a telephone is
the quickest responder that can be used.
As coherer circuit, I usually arrange the coherer in simple series
with a battery (voltaic or thermal) and a galvanometer or other
indicator or recorder of fluctuations of current, and I then connect
the terminals of this series of instruments to the capacity areas of the
receiver close to its self-inductance coil, so that this same coil of wire
completes and forms an essential part of the coherer circuit. The
coherer is thus affected by every electrical disturbance occurring in
the connecting coil or in its capacity areas, and by aid of the battery
at once enables the telegraphic or telephonic instrument to appreciate
and indicate the signals. This plan is shown in Fig. 13. l It is an
improvement on any mode of connection that had previously been
possible without the connecting coil.
In some cases I may, as shown in Fig, H, 1 surround
1 Page 133,
Appendix 181
syntonizing coil of the resonator with another or secondary coil u
(constituting a species of transformer) and make this latter coil part
of the coherer circuit, so that it shall be secondarily affected by the
alternating currents excited in the conductor of the resonator, and
thus the coherer be stimulated by the current in this secondary coil
rather than primarily by the currents in the syntonizing coil itself;
the idea being thus to leave the resonator freer to vibrate electrically
without disturbance from attached wires.
In all cases it is permissible and sometimes desirable to shunt the
coils of the telegraphic instrument by means of a fine wire or other
non-inductive resistance, as shown at w in Fig. 13, in order to
connect the coherer more effectively and closely to the capacity areas
or receiving arrangement whereby it is to be stimulated.
Having now particularly described and ascertained the nature of
my said invention and in what manner the same is to be performed,
I declare that what I claim is:
1. In a system of Hertzian wave telegraphy, the combination
with a pair of capacity areas (of which one may be the earth) of a
self-inductance coil inserted between them electrically, for the purpose
of prolonging any electrical oscillations excited in the system, and
constituting such a system a radiator of definite frequency or pitch.
2. In a system of Hertzian wave telegraphy, the combination with
a pair of capacity areas (of which one may be the earth), of a self-
inductance coil inserted between them electrically for the purpose of
prolonging any electrical oscillations excited in the system and
thereby enabling a distant radiator to act cumulatively if of
corresponding period; thus constituting the system a resonator or
absorber of definite frequency or pitch.
3. In combination, a pair of capacity areas connected by a coil
of wire serving as the radiator in a system of Hertzian wave telegraphy,
means for syntonizing such radiator and means for charging it by
aerial disruption or impulsive rush.
4. In a system of Hertzian wave telegraphy, the combination of
a pair of capacity areas such as h h l , means for syntonizing such
capacity areas, a receiving circuit completed through one or both of
such capacity areas or their adjuncts, and means for bridging over the
discharge gap between such capacity areas when they are to be used
as a receiver whereby such capacity areas are rendered adaptable for
use at will either as a radiator or resonator.
6. In a system of syntonic Hertzian wave telegraphy the
combination with the self-inductance coil of the receiver of a
secondary coil surrounding the same, which secondary coil forms part
of the coherer circuit substantially as and for the purpose set forth.
6. The combination, in the receiving circuit of a system of
Hertzian wave telegraphy, of an adjustable or replaceable self-
inductance coil, connecting the capacity areas, a coherer, a battery, a
telegraphic receiving instrument or a telephone with or without a
shunt across the coils thereof substantially as and for the purpose
set forth. ' r
132 Radio: Beam and Broadcast
7. The construction arrangement and combination of parts
constituting my improved system of syntonic Hertzian wave telegraphy
substantially as set forth and as illustrated in the accompanying
drawings.
Dated this 1st day of February, 1898.
WM. P. THOMPSON & CO.,
Patent Agents,
Of Liverpool, Manchester, Birmingham and London.
AUTHOR'S NOTE. On the 28th day of April, 1911, Mr. Justice
Parker amended this patent by deleting four other claims, and
extended it for seven years, subject to compulsory license.
SPECIFICATION OF BR, PAT. NO. 22,020, A.D. 1899
Date of Application, November 3, 1899
Complete, Specification Left, June, 30, 1900
Accepted, September 22, 1900
[Communicated from abroad by PROFESSOR FERDINAND BRAUN, of
Strassburg, in the Empire of Germany, Doctor of Philosophy.]
COMPLETE SPECIFICATION
IMPROVEMENTS IN OR RELATING TO TELEGRAPHY WITHOUT THE USE OP
CONTINUOUS WIRES
This invention relates to telegraphy without the use of connecting
wires between the receiver and transmitter.
Fig. 1 shows a diagram of the connection of the apparatus, Fig. 2
is a modification thereof.
Hitherto it has been usual in such telegraphy to arrange the
spark gap in the current circuit of the vertical transmitting wire as
has been already set forth by Popoff and induction coils have been
joined in the said circuit. I have found, however, that much better
results are obtainable, if the currents which pass through the spark
gap are not allowed to pass immediately into the transmitting wire,
but are previously transformed. Therefore I provide the spark gap in
the current of the primary coil of a transformer, the secondary coil
of which is connected to the transmitting wire at one end, its other
end being connected to earth or insulated. This method proves to be
specially advantageous if use is made not of the quick waves hitherto
usual, but of slower waves, such as are obtained by the discharge of
Leyden jars. The advantage of using transformed current for
electrical telegraphy is increased if slower vibrations are produced.
To give a theoretical explanation of my invention presents difficulty.
Possibly the sparking gap in the oscillating circuit exercises a
damping effect so that the vibrations soon disappear. There may,
however, be other causes for this effect.
When slower vibrations are made use of, each vibration of the
Jlf
tip*.
,\u
Via. Lodge's Coupled-circuit Receiver (see page 130).
Fig. VII. Braun's Coupled-circuit Transmitter.
184 Radio: Beam and Broadcast
primary current circuit will cause a vibration of the secondary
circuit; in addition to this, however, also the proper vibrations of the
secondary current circuit will be superposed. It appears not
impossible that the reason of the improved transmission may lie in
this peculiar effect. Whether this explanation be the correct one or
not, the fact remains that the electric signals of telegraphy without a
continuous wire arc clearer and plainer than it is ever possible to
obtain with non-transformed vibrations. There is, moreover, another
advantage in that the transmitting wire is not in direct connection
with the high tension, and consequently that a fall of the wire would
not have the same injurious effects which would be caused in the case
of a direct connection. Indeed the said wire can be touched by
persons without injury.
In Fig. 1 a is a Leyden jar which is discharged through the air
at 6 and the primary coil p of transformer T. One end of the
secondary coil s is connected with the earth E, the other with the
transmitting wire /.
In Fig. 2 R means a Ruhmkorff apparatus connected with the
Leyden jars a, the spark gaps c, and the primary and secondary wire
p and s. The connection of the secondary may be effected in the
same manner as before.
The receiving devices (not shown in the figures) are of the usual
type, viz., a coherer, a local battery, a signaller and so on.
Having now particularly described and ascertained the nature of
this invention, and in what manner the same is to be performed, I
declare that what I claim is:
In electric wireless telegraphy the use of transformers the primary
of which is joined in the circuit of the air gap and the secondary of
which is connected with the sending* wire.
Dated the 30th day of June, 1900.
W. P. THOMPSON & CO.,
Of London, Liverpool, Manchester and Birmingham.
EXTRACTS FROM THE SPECIFICATION OF BR. PAT. NO. 7777,
A.D. 1900
Date of Application, April 26, 1900
Complete Specification Left, February 26, 1901
Accepted, April 13, 1901
COMPLETE SPECIFICATION
IMPROVEMENTS IN APPARATUS FOR WIRELESS TELEGRAPHY
We, GUGLIELMO MARCONI, Electrician, and MARCONI'S WIRELESS
TELEGRAPH COMPANY, LIMITED, late of 28 Mark Lane, and now both
of 18 Finch Lane, in the City of London, do herehy declare the nature
. f.
y\
Fi ff . VIII.
186 Radio: Beam and Broadcast
of this invention and in what manner the same is to be performed,
to be particularly described and ascertained in arid by the following
statement:
The object of this invention is not only to increase the efficiency
of the apparatus hitherto employed, but also to so control the action
as to cause intelligible communications to be established with one or
more stations only out of a group of several receiving stations.
In the Specification of a former Patent No. 12,039 of 1896, a
transmitter is described which consists of an induction coil, one
terminal of the secondary circuit being connected to a metal sphere
connected to earth and the other to a similar sphere connected to an
insulated conductor which generally takes the form of a more or less
vertical wire which may or may not terminate in or have attached to
it a metal body of extended surface, giving it increased electrical
capacity.
According to the present invention the vertical wire is connected
to earth through the secondary winding of a transformer of a kind
suitable for the transformation of very rapidly alternating electric
currents and the primary of this transformer is connected to the
spheres or terminals of the sparking appliance.
A condenser of suitable capacity is introduced in series with the
primary or each end of the primary may be connected to one of the
plates of two condensers of suitable capacity, the other plates of which
are connected to the sparking appliance.
This device enables much more energy to be imparted to the
radiator than heretofore, the approximately closed circuit of the
primary being a good conserver and the open circuit of the secondary
a good radiator of wave energy.
The arrangement works as follows:
On pressing the key and actuating the induction coil (in order
to produce a signal) the condenser in circuit with the transformer is
charged and subsequently discharges through the spark gap. If the
capacity, the inductance, and the resistance of the circuit are of
suitable values, the discharge is oscillatory, with the result that
alternating currents of high frequency pass through the primary of
the transformer, and induce similar oscillations in its secondary, these
oscillations being communicated to the elevated conductor.
The circuit of the elevated conductor should be suitably attuned
for this purpose.
The effect of these oscillations in the elevated conductor is to
inductively affect similar distant conductors if the self-induction and
capacity of the said conductors is of a suitable value or values.
At the receiving end a receiver is employed capable of being
actuated by electrical oscillations of high frequency such as are
described in the Specifications Nos. 12,326 of 1898, 6982 of 1899, and
26,186 of 1899.
The four circuits, namely those including the primary and the
secondary of the transformer in the transmitter and the primary and
secondary of the transformer in the receiver, should be so adjusted
Appendix
187
as to make the electric time period the same in each, i.e., the product
of the self-induction multiplied by the capacity is the same in each
case. But in lieu of the time periods being the same in each they
may be harmonics of each other.
In employing this invention to localize the transmission of
intelligence from a station to one only out of several receiving stations
the time period of the circuits at each of these stations is so arranged
as to be the same but different from those of the other receiving
stations. If the time period of the circuits of the transmitting
station are varied until they are in resonance with those; of one of the
receiving stations that one alone out of all the number of receiving
stations will respond, provided that the distance between the
transmitter and receiver is not too small.
The adjustment of the self-induction and capacity of the circuits
can be made in any convenient manner. As a practical guide to
putting the invention in practice we subjoin the arrangements which
we find work best.
Figs. 1 and 2 are diagrams of the transmitter and of the receiver
respectively. ...........
TRANSMITTING STATION.
Tune
Aerial Conductor
Transformer
oT,/i
Inductance
Number of
turns of g
included
Capacity in
microfarads e
Length {
spark in
millimetres
No. 7
Four vertical wires each
No. 4
None
016
6
48-6 metres long con-
nected together at top
and bottom but kept
apart throughout their
length by being sus-
pended from the arms
of a wooden cross each
of which is 4 metres
long.
No. 8
One vertical wire 48 metres
No. 5
None
007
6
long
Tunes Nos. 7 and 8 give very good signals over a distance of
190 miles.
Having now particularly described and ascertained the nature of
our said invention and in what manner the same is to be performed,
we declare that what we claim is:
1. A transmitter for electric wave telegraphy consisting of a
spark producer having its terminals connected through a condenser
with one circuit of a transformer, the other circuit being connected
to a conductor and to earth or a capacity, the time period of electrical
188 Radio: Beam and Broadcast
oscillations in the two circuits being the same or harmonics of each
other.
2. A system of electric wave telegraphy in which both the
transmitter and the receiver contain a transformer, the time period of
electrical oscillations in the four circuits of the two transformers
being the same or harmonics of each other.
3. A system of electrical wave telegraphy in which both the
transmitter and the receiver contain a transformer one circuit of
which is a persistent oscillator and the other a good radiator or
absorber of electrical oscillations, all four circuits having the same
time period or being harmonics of each other substantially as
described.
4. Apparatus for wireless telegraphy substantially as described
and illustrated in the drawings.
Dated this 25th day of February, 1901.
G. MARCONI,
MARCONI'S WIRELESS TELEGRAPH CO., LTD.,
By Carpmael & Co.,
Agents.
EXTRACTS FROM BR. PAT. NO. 20,981, A.D. 1896
Dale of Application, September 22, 1896
Accepted, November 21, 1896
COMPLETE SPECIFICATION
[Communicated from abroad by NIKOLA TESLA, of 46 East Houston
Street, New York, United States of America, Electrician.]
IMPROVEMENTS RELATING TO THE PRODUCTION, REGULATION, AND
UTILIZATION OF ELECTRIC CURRENTS OF HIGH FREQUENCY, AND TO
APPARATUS THEREFOR.
I, HENRY HARRIS LAKE, of the Firm of Haseltine, Lake & Co.,
Patent Agents, 45 Southampton Buildings, in the County of
Middlesex, do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:
This invention, subject of the present application, is embodied
in certain improvements in methods of and apparatus for producing,
regulating and utilizing electric currents of high frequency heretofore
invented by Nikola Tesla, and described in British Letters Patent
No. 8576, dated May 19, 1891. The method and apparatus referred
to in said patent were devised for the purpose of converting, supplying
Appendix 189
and utilizing electrical energy in a form suited for the production of
certain novel electrical phenomena which require currents of high
potential and a higher frequency than can readily or even possibly be
developed by generators of the ordinary types or by such mechanical
appliances as were theretofore known. The invention referred to was
based upon the principle of charging a condenser or a circuit
possessing capacity and discharging the same, generally through the
primary of a transformer, the secondary of which constituted the
source of working current, and under such conditions as to yield a
vibratory or rapidly intermittent discharge current.
The present invention, while aiming to simplify and render more
efficient the apparatus heretofore used, lias for its object, primarily,
to provide a means for converting such currents as are generally and
most readily obtainable from the mains of ordinary systems of
municipal distribution, into currents of the special character referred
to, and to regulate or control, and utilize such currents in a simple,
economical arid efficient manner. The improvements are illustrated
herein in forms of apparatus adapted for use with existing circuits or
systems, and which while constructed and operating on the same
general principles are modified only as rnay be required by a direct
or an alternating source of supply. ......
When the potential of the source of current periodically rises and
falls, whether with reversals or riot is immaterial, it is essential to
economical operation that the intervals of interruption of the
charging circuit should bear a definite time relation to the period of
the current, in order that the effective potential of the impulses
charging the condenser may be as high as possible. In case,
therefore, an alternating or equivalent electromotive force he employed
as the source of supply, a circuit controller is used which will
interrupt the charging circuit at instants predetermined with
reference to the variations of potential therein.
A convenient, and probably the most practicable means for
accomplishing this is a synchronous motor connected with the source
of supply and operating a circuit controller which first interrupts the
charging current at or about the instant of highest intensity of each
wave and then permits the condenser to discharge the energy stored
in it, through its appropriate circuit. Such apparatus, which may
be regarded as typical of the means for accomplishing this purpose,
it illustrated in Fi#s. 4, 5 and 6.
In Fig. 4, A 11 A 11 are the conductors taken from the mains of
any alternating current generator A, and for raising the potential of
uch current a transformer is employed represented by the primary B
and secondary B 1 .
The circuit of the secondary includes the energizing coils of a
synchronous motor G, and a circuit controller C fixed to the shaft of
the motor;
An insulating arm O, stationary with respect to the motor shaft
and adjustable with reference to the poles of the fixed magnets, carries
two brushes F F 1 which bear upon the periphery of the disk C.
140 Radio: Beam and Broadcast
With the parts thus arranged, the secondary circuit is completed
through the coils of the motor whenever the two brushes rest upon
the uninsulated segments of the disk, and interrupted through the
motor at other times.
Such a motor, if properly constructed, in well understood ways,
maintains very exact synchronism with the alternations of the source,
and the arm O may, therefore, be adjusted to interrupt the current at
any determined point of its waves. By the proper relations of
insulated and conducting segments, and the motor poles, the current
may be interrupted twice in each complete wave at or about the points
of highest intensity.
In order that the energy stored in the motor circuit may be
utilized at each break to charge the condenser II, the terminals of the
latter are connected to the two brushes F F 1 or to points of the circuit
adjacent thereto, so that when the circuit through the motor is
interrupted the terminals of the motor circuit will be connected with
the condenser. The discharge of the condenser takes place through
the primary K, the circuit of which is completed simultaneously with
the motor circuit and interrupted while the motor circuit is broken
and the condenser being charged. The secondary impulses of high
potential and great frequency are available for the operation of
vacuum tubes P, single terminal lamps R, and other novel and useful
purposes.
It is obvious that the supply current need not be alternating,
provided it be converted or transformed into an alternating current,
before reaching the controller. .......
In some cases the energy delivered by the system may be readily
and economically regulated. It is well known that every electric
circuit, provided its ohmic resistance does not exceed certain definite
limits, has a period of vibration of its own analogous to the period of
vibration of a weighted spring. In order to alternately charge a
given circuit of this character by periodic impulses impressed upon
it and to discharge it most effectively, the fretjjjenqy of the impressed
impulses should bear a definite relation to the frequency of vibration
possessed by the circuit itself. Moreover, for like reasons, the period
of vibration of the discharge circuit should bear a similar relation to
the impressed impulses or the period of the charging circuit. When
the conditions are such that the general law of harmonic vibrations is
followed, the circuits are said to be in resonance or in electro-magnetic
synchronism, and this condition of the system is found to be highly
advantageous.
In carrying out the invention, therefore, the electrical constants
should be so adjusted that in normal operation the condition of
resonance is approximately attained. To accomplish this, the number
of impulses of current directed into the charging circuit per unit
time is made equal to the period of the charging circuit itself, or,
generally, to a harmonic thereof, and the same relations are main-
tained between the charging and discharge circuit. Any departure
from this condition will result in a decreased output, and this fact is
Fig. IX.
142 Radio: Beam and Broadcast
taken advantage of in regulating such output by varying the
frequencies of the impulses or vibrations in the several circuits.
Inasmuch as the period of any given circuit depends upon the
relations of its resistance, self-induction and capacity, a variation of
any one or more of these may result in a variation of its period. . . .
In order to secure the greatest efficiency in a system of this kind,
it is essential, as before stated, that the circuits, which mainly as a
matter of convenience are designated as the charging and the
discharge circuits, should be approximately in resonance or electro-
magnetic synchronism. Moreover, in order to obtain the greatest
output from a given apparatus of this kind it is desirable to maintain
as high a frequency as possible. .......
The circuit controller or the device which ensures the proper
charging and discharging of the condenser may be of any construction
that will perform the functions required of it. In illustration of the
principle of construction and mode of operation, reference has been
made only to forms of mechanism that make and break metallic
contacts, but there need he no actual metallic contact, if provision be
made for the passage of a spark between separated conductors. Such
a device is illustrated in Figs. 11 to 15.
A designates, in Fig. 11, a generator having a commutator a 1
and brushes a 11 bearing thereon, and also collecting rings b 11 ,
6 11 , from which an alternating current is taken by brushes b l in tho
well-understood manner
Having now particularly described and ascertained the nature of
the said invention and in what manner the same is to be performed,
as communicated to me by my foreign correspondent, I declare that
what I claim is:
1. The apparatus herein described for converting electric
currents of the kind generally obtainable from municipal systems of
electric distribution, into currents of hi/arh frequency, comprising in
combination a circuit of high self-induction, a circuit controller
adapted to make and break such circuit, a condenser into which the
said circuit discharges when interrupted, and a transformer through
the primary of which the condenser discharges, as set forth.
6. The method herein described of converting alternating
currents of relatively low frequency into currents of high frequency,
which consists in charging a condenser by such currents of low
frequency during determinate intervals of each wave of said current;
and discharging the condenser through a circuit of such character as
to produce therein a rapid succession of impulses, as set forth.
14. The combination with a source of alternating current, of a
condenser adapted to be charged thereby, a circuit into which the
condenser discharges in a series of rapid impulses, arid a circuit
controller for effecting the charging and discharge of said condenser
composed of conductors movable into and out of proximity with each
other in synchronism with the alterations of the source, as set forth.
16. A circuit controller for systems of the kind described,
comprising in combination a pair of angularly adjustable terminals
Appendix 148
and two or more rotating conductors mounted to pass in proximity to
the said terminals, as set forth.
16. A circular controller for systems of the kind described,
comprising in combination two sets of conductors, one capable of
rotation and the other of angular adjustment whereby they may be
brought into and out of proximity to each other at determinate points
and one or both being subdivided so as to present a group of
conducting points, as set forth.
Dated this 22nd day of September, 1896.
HASELTINE, LAKE & CO.,
Agents for the Applicant,
45 Southampton Buildings, London, W.C.
UNITED STATES PATENT OFFICE
THOMAvS A. EDISON, OF MENLO PARK, NEW JERSEY
ELECTRICAL INDICATOR
SPECIFICATION FORMING PART OF LETTERS PATENT NO. 307,031, DATED
OCTOBER 21, 1884 (ABRIDGED)
Application filed November 15, 1883. (A ; o model.)
To all whom it may concern:
Be it known that I, THOMAS A. EDISON, of Menlo Park, in the
county of Middlesex and State of New Jersey, have invented a new
and useful Improvement in Electrical Indicators (Case No. 603), of
which the following is a specification.
The object of my invention is to produce an efficient apparatus
for indicating variations of electro-motive force in an electric circuit,
preferably for use in connection with systems of electrical distribution
to show the changes in pressure in the various parts of the district.
The apparatus is also capable of use in automatically regulating the
electro-motive force to correspond with such variations. I have
discovered that if a conducting substance is interposed anywhere in
the vacuous space within the globe of an incandescent electric lamp,
and said conducting substance is connected outside of the lamp with
one terminal, preferably the positive one, of the incandescent
conductor, a portion of the current will, when the lamp is in
operation, pass through the shunt-circuit thus formed, which shunt
includes a portion of the vacuous space within the lamp. This
current I have found to be proportional to the degree of incandescence
of the conductor or candle-power of the lamp.
My invention consists in the utilization of this discovery for
indicating or regulating variations in electro-motive force, or for
affecting electrical apparatus in any desired manner.
144 Radio: Beam and Broadcast
The wire 5 leads to the binding-post c, while a wire 6,
connected with the positive wire 3 of the lamp, leads to the binding-
post c 1 . 1
What I claim is
4. The combination, with an incandescent electric lamp, of a
circuit having one terminal in the vacuous space within the globe of
said lamp, and the other in connection without the lamp with the
positive side of the lamp-circuit, substantially as set forth.
This specification signed and witnessed this 2nd day of
November, 1883.
THOS. A. EDISON.
Witnesses :
H. W. SEELY,
EDWARD H. PYATT.
EXTRACT FROM SPECIFICATION OF BR. PAT. NO. 24,850,
A.D. 1901
Date of Application, November 16, 1904
Complete Specification Left, August 15, 1905
Accepted, September 21, 1905
COMPLETE SPECIFICATION
IMPROVEMENTS IN INSTRUMENTS FOR DETECTING AND MEASURING
ALTERNATING ELECTRIC CURRENTS
I, JOHN AMBROSE FLEMINGS, of University College, Gower Street,
in the County of London, Doctor of Science, do hereby declare the
nature of this invention and in what manner the same is to be
performed, to be particularly described and ascertained in and By the
following statement:
This invention relates to certain new and useful devices for
converting alternating electric currents and especially high frequency
alternating electric currents or electric oscillations into continuous
electric currents for the purpose of making them detectable by, and
measurable with, ordinary direct current instruments such as a
" mirror galvanometer " of the usual type or any ordinary direct
current ammeter.
Such instruments as the latter are not affected by alternating
electric currents either of high or low frequency which can only be
measured and detected by instruments called alternating current
instruments of special design. It is, however, of great practical
importance to be able to detect feeble electric oscillations, such as are
employed in Hertzian wave telegraphy by an ordinary movable coil
or movable needle mirror galvanometer. This can be done if the
alternating current can be " rectified," that is either suppressing all
the constituent electric currents in one direction and preserving th$
1 Drawings on following page.
c 9 ? 9 V
Fig. X. Edison's U.S. Patent 307,031 (p. 143)
146
Radio: Beam and Broadcast
7A
others, or else by changing the direction of one of the sets of currents
which compose the alternating current so that the whole movement
of electricity is in one direction. Many means have been devised
and are in use for rectifying low frequency alternating currents, such
as are used in electric lighting. There are well-known forms of
mechanical rectifier, also there is a well-known form of electro-
chemical rectifier depending on the fact that when a plate of carbon
and aluminium is placed in any electrolyte which yields oxygen on
electrolysis, an electric current
can only pass through this cell
in one direction if below a certain
voltage.
Both these forms of rectifier
are, however, inapplicable for
high frequency currents. I have
found that the aluminium-carbon
cell will not act with high
frequency currents.
I have discovered that if two
conductors are enclosed in a
vessel in which a good vacuum
is made, one being heated to
a high temperature, the space
between the hot and cold con-
doctors possesses a unilateral
electric conductivity, and negative
electricity can pass from the hot
conductor to the cold conductor
but not in the reverse direction.
... As a very high vacuum
should be obtained in the bulb
a and as a considerable quantity
of air is occluded in the con-
ductors these should be heated
when the bulb is being exhausted.
. . . Although Fig. 1 shows the
application of the instrument to
wireless telegraphy it will be
understood that the aerial wire n
may be replaced by any circuit in which there is an alternating
electromotive force, whether of low frequency or of high frequency.
. . . The galvanometer I may be replaced by any other instrument
for detecting the oscillations or by a relay for actuating a detecting
or recording instrument.
In those cases in which a larger alternating current has to be
dealt with, the hot conductor may be a rod of soft graphitic carbon
held in suitable supports.
I find it possible by means of the device described above to
rectify an alternating current without the use of any auxiliary
Appendix 147
continuous heating current. Thus, if I pass through the carbon
filament an alternating current to bring it to bright incandescence, I
find if I connect either terminal of the filament by a circuit outside
the bulb with the terminal of the embracing cylinder or other cold
conductor, then in this circuit a continuous current flows. Hence,
the device may be used for rectifying either high frequency or low
frequency alternating currents of electrical oscillations, provided these
are of sufficient strength to render a carbon filament brilliantly
incandescent.
Having now particularly described and ascertained the nature of
my said invention and in what manner the same is to be performed,
I declare that what I claim is:
1. A vacuous vessel having in it two conductors adjacent to but
not touching each other, one of them being heated, these conductors
being connected by a circuit outside the vessel, such circuit being
exposed to some influence tending to produce an alternating current
in it and which contains a galvanometer or other instrument for
detecting a continuous current substantially as described.
2. In instruments such as are covered by Claim 1, heating the
conductor by means of a continuous electric current passed through
it substantially as described.
3. The application of the instruments covered by Claims 1 and 2
to wireless telegraphy substantially as described.
4. Duplicating the instruments covered by Claims 1, 2 and 3, by
connecting the two coils of a differential galvanometer respectively
to the heated conductor in one vessel and the unheated conductor in
the other, the connection between the two coils being connected to
the other pair of conductors substantially as described.
6. Instruments for converting alternating electric currents into
unilateral currents substantially as described.
Dated this 1st day of August, 1905.'
J. A. FLEMING.
AUTHOR'S NOTE. This specification was amended by disclaimer
in 1918 when the patent expired, and an application was unsuccessfully
made for its extension.
148 Radio: Beam and Broadcast
UNITED STATES PATENT OFFICE
LEE DE FOREST, OF NEW YORK, N.Y.
DEVICE FOR AMPLIFYING FEEBLE ELECTRICAL CURRENTS
SPECIFICATION OF LETTERS PATENT NO. 841,387.
PATENTED JANUARY 15, 1907 (ABRIDGED)
Application filed October 25, 1906. Serial No. 340,467
To all whom it may concern:
Be it known that I, LKE DE FOREST, a citizen of the United States,
and a resident of New York, in the county of New York and State of
New York, have invented a new and useful Improvement in Devices
for Amplifying Feeble Electrical Currents, of which the following is
a specification.
My invention relates to devices for amplifying feehle electrical
currents such, for example, as telephone-currents; and its object is
to produce an amplifying device of greater efficiency and simplicity
than those heretofore employed.
My invention will be described with reference to the drawings
accompanying and forming a part of this specification, and in
which
Figs. 1, 2, 4 and 5 represent conventionally or diagrammatically
various arrangements of apparatus and circuits whereby my invention
may be carried into effect.
In the figures, A represents an evacuated vessel inclosing a
sensitive conducting gaseous medium maintained in a condition of
molecular activity.
R is a signal-indicating device.
B B 1 are batteries or other sources of electrical energy.
D E D 1 are electrodes sealed within the receptacle A.
In Fig. 2 the current to be amplified may be impressed upon the
medium intervening between the electrodes D and E, and thereby
alter, by electrostatic attraction, the separation between the electrodes.
In this case D 1 may be a strip of platinum-foil, and the slightest
approach thereof toward the filament will act to slightly cool the
gaseous medium, arid thereby alter the current in the local circuit, or,
if D 1 is rigid, the increase in electrostatic attraction between D 1 and
E will cause E to recede from D, and thereby alter the current in the
local circuit. ...........
In Fig. 4 the currents to be amplified may be impressed upbn the
gaseous medium intervening between D 1 and E by means of the
transformer M l . A condenser C may be included in series with the
secondary of said transformer and the electrodes D 1 E. In this case
there may or may not be a variation between the separation of the
flectrodes, and the currents to be amplified may vary the motions qf
Appendix
149
the ions around the filament, thereby controlling to a greater degree
the flux between said filament and the electrode D. .
It will be obvious that the amplifying device, which constitutes
the subject-matter of the present invention, is not limited in its use
to any particular kind of electrical circuit or apparatus, but that it is
capable of general application wherever an amplifying device is
required. By way of example of its application to a wire telegraph
Fig. XII.
or cable system I have shown the line F in Fig. 1 as including a
telegraph transmitting-key T 1 and source of vibratory current G. In
Fig. 2 I have shown the line F as constituting the local circuit of a
wireless-telegraph receiving system including the battery B 11 and
oscillation-detector T 11 , the latter being connected in series with an
antenna V and the earth E 1 . In Fig. 4 I have shown the line F as
constituting a telephone-circuit including the microphone-transmitter
T 111 and battery B 111 . In all instances it will be understood by thos
150
Radio: Beam and Broadcast
skilled in the art and without going into further detail that the signal-
indicating device R, which is included in the local receiving-circuit,
may be any device suitable for the purpose of reproducing the signal
initiated in the line F.
I do not limit myself to any of the specific embodiments of my
invention herein described, inasmuch as many modifications will
\
//
u?
9'
~ r WVW*
i
FIG. i
Fig. XI la.
readily occur to those skilled in the art without departing from the
principle of my invention.
I claim
4. In a device for amplifying electrical currents, an evacuated
vessel, three electrodes sealed within said vessel, means for heating
one of said electrodes, a local receiving-circuit including two of said
electrodes, and means for passing the current to be amplified between
one of the electrodes which ie included in the receiving-circuit and
the third electrode.
Appendix 151
5. In a device for amplifying electrical currents, an evacuated
vessel inclosing a gaseous medium, means other than the received
energy for maintaining said gaseous medium in a condition of
molecular activity, means for impressing the currents to be amplified
upon said gaseous medium, and a local receiving-circuit having its
electrodes sealed within said vessel.
6. In a device for amplifying electrical currents, an evacuated
vessel, a heated electrode and two non-heated electrodes sealed within
said vessel, the non-heated electrodes being unequally spaced with
respect to said heated electrode, a local receiving-circuit including
said heated electrode and that one of the non-heated electrodes which
has the greater separation from the heated electrode, and means for
passing the current to be amplified between the heated electrode and
the other non-heated electrode.
In testimony whereof I have hereunto subscribed my name this
17th day of October, 1906.
LEE DE FOREST.
Witnesses :
RALPH POLK BUELL,
SIDNEY WILLIAMS.
UNITED STATES PATENT OFFICE
LEE DE FOREST, OF NEW YORK, N.Y., ASSIGNOR, BY MESNE
ASSIGNMENTS, TO DE FOREST RADIO TELEPHONE
CO., A CORPORATION OF NEW YORK
SPACE TELEGRAPHY
SPECIFICATION OF LETTERS PATENT NO. 879,532.
PATENTED FEBRUARY 18, 1908 (ABRIDGED)
Application filed January 29, 1907. Serial No. 354,662
To all whom it may concern:
Be it known that I, LEE DE FOREST, a citizen of the United
States, and a resident of New York, in the county of New York and
State of New York, have invented a new and useful Improvement in
Space Telegraphy, of which the following is a specification.
My invention relates to wireless telegraph receivers or oscillation
detectors of a type heretofore described in my prior Letters Patent
Nos. 824,637, June 26, 1906 and 836,070, November 13, 1906.
The objects of my invention are to increase the sensitiveness
of oscillation detectors comprising in their construction a gaseous
medium by means of the structural features and circuit arrangements
which are hereinafter more fully described.
My invention will be described with reference to the drawing*
152 Radio: Beam and Broadcast
which accompany and form a part of the present specification,
although it is to be understood that many modifications may , be made
in the apparatus and systems herein described without departing from
the principles of my invention.
In the drawings, Fig. 1 represents in diagram a wireless telegraph
receiving system comprising an oscillation detector constructed and
connected in accordance with the present invention and Fig. 2
represents a space telegraph receiving system having a modified form
of oscillation detector connected therein in a manner which constitutes
one of the subjects matter of said invention. .....
D represents an evacuated vessel, preferably of glass, having
sealed therein thrc* conducting members, F., a and 6, in Fig. 1 and F,
o 1 and b in Fig. 2. The conducting member or electrode F is shown
as consisting of a filament, preferably of metal, which is connected in
series with the battery A or other source of electrical current of
sufficient strength to heat said filament, preferably to incandescence.
The conducting member 6, which may be a plate of platinum, has
one end brought out to the terminal 3. Interposed between the
members F and b is a grid-shaped member a, which may be formed
of platinum wire, and which has one end brought out to the
terminal 1. The local receiving circuit, which includes the battery B,
or other suitable source of electromotive force, and the signal
indicating device T, which may be a telephone receiver, has its
terminals connected to the plate b and filament F at the points 3 and
4 respectively. The means for conveying the oscillations to be
detected to the oscillation -detector, are the conductors which connect
the filament F and grid a to the tuned receiving circuit and, as
shown, said conductors pass from -the terminals 2 and 1 to the
armatures of the condenser G.
I have determined experimentally that the presence of the
conducting member a, which as before stated may be grid-shaped,
increases the sensitiveness of the oscillation detector and, inasmuch as
the explanation of this phenomenon is exceedingly complex and at
best would be merely tentative, I do not deem it necessary herein to
enter into a detailed statement of what I believe to be the probable
explanation. ...........
By reference to Fi#. 1, it will be seen that a similar closed
circuit exists between said battery, and the electrode b and conducting
member a. In order to close each of said circuits to the passage of
direct current from the aforesaid battery there- through, or to prevent
the development of a difference of potential between the members
a and 6, or between a 1 and b, or to prevent the members a or a 1
from receiving an electrical charge from said battery, I insert the
condenser C 1 in said otherwise mechanically closed circuit and find
that the presence of said condenser produces a great increase in the
sensitiveness of the oscillation detector as determined by the very
marked increase in the sound produced in the telephone T when
said condenser is present over the sounds produced therein under the
game conditions when said condenser is not employed.
I
ir
/
H|l|lH +
"->- -/ *
-lilf
ij'
Fig. Xlll.
154 Radio: Beam and Broadcast
It will be understood that the circuit arrangements herein
described with reference to the particular forms of audion herein
disclosed may with advantage also be employed with various other
types of audion.
I claim:
1. An oscillation detector comprising an evacuated vessel, an
electrode inclosed therein, means for heating said electrode, a second
electrode inclosed within said vessel, a local circuit having its
terminals electrically connected to said electrodesi, a conducting
member inclosed within said vessel and located between said electrodes,
and means for conveying the oscillations to be detected to the first
mentioned electrode and said conducting member.
2. An oscillation detector comprising an evacuated vessel, two
electrodes inclosed within said vessel, means for heating one of said
electrodes, and a conducting member inclosed within said vessel and
interposed between said electrodes.
3. An oscillation detector comprising an evacuated vessel, two
electrodes inclosed within said vessel, means for heating one of said
electrodes, and a grid-shaped member of conducting material inclosed
within said vessel and interposed between said electrodes.
4. An oscillation detector comprising an evacuated vessel, a
filament sealed therein, a source of electrical energy connected in
series with said filament, an electrode sealed in said vessel, a local
circuit having its terminals connected to said filament and electrode,
respectively, said local circuit including a source of electromotive force
and a signal-indicating device, a grid of conducting material sealed
in said vessel and interposed between said filament and electrode, and
means for conveying the oscillations to be detected to said filament
and grid.
5. An oscillation detector comprising an evacuated vessel, an
electrode inclosed therein, means for heating said electrode, a second
electrode inclosed within said vessel, a local circuit having its
terminals connected to said electrodes, a conducting member inclosed
within said vessel and located between said electrodes, a closed circuit
for conveying the oscillations to be detected to said first-mentioned
electrode and conducting member, and a condenser in said closed
circuit. ......
In testimony whereof, I have hereunto subscribed my name this
21st day of December, 1906.
LEE DE FOREST.
Witnesses :
THOMAS I. GALLAGHER,
HANS W. GOETZE.
AUTHOR'S NOTE. This patent expires on February 18th, 1925.
Appendix 155
EXTRACTS FROM THE SPECIFICATION OF BR. PAT. NO. 8821,
A.D. 1913
Date of Application, April 15, 1913
Accepted, October 2, 1913
COMPLETE SPECIFICATION
A RECEIVING ARRANGEMENT FOR USE IN WIRELESS TELEGRAPHY
AND TELEPHONY
(Communicated by GESELLSCHAFT FUR DRAHTLOSE TELEGRAPHIB
M.B.H., of 9 Tempelhofer Ufer, Berlin, in the Empire of
Germany, Manufacturers.) 1
Receiving arrangements for use in wireless telegraphy are known
in which vacuum tubes with a glowing cathode and one or more cold
anodes are employed for detecting electrical oscillations. However,
these known devices have hitherto only utilized the unidirectional
conductivity of the gas ionized by the hot electrode in order to
transform the electrical oscillations into direct current or into
pulsating current of unchanging sign, thus making them suitable
for indication by means of a telephone or a direct current instrument.
The object of the present invention is a device for receiving
electrical oscillations, for use in wireless telegraphy and telephony,
in which the valve action of vacuum tubes is not employed for the
detection of the electrical oscillations, but in which vacuum tubes
having glowing cathodes serve the purpose of strengthening the
electrical oscillations without thereby giving rise to a change in their
wave form owing to the valve action. The detection of the electrical
oscillations is accordingly not affected by the vacuum tubes themselves
as in known devices, but other or separate detectors are employed for
this purpose, e.g., thermo-cells or electrolytic rectifiers.
In the arrangements hitherto known the telephone or a sensitive
direct current instrument has been inserted in the circuit containing
the source of direct current i. It is obvious that in such an arrange-
ment the relay action of the tube is practically non-existent because
it is well known that electrical oscillations of high frequency cannot
directly influence such instruments. For this reason, hitherto, it has
been only the comparatively small unidirectional conductivity of
such gaseous conducting paths that came into consideration for
detecting the oscillations. According to the present invention the
relay action of vacuum tubes is utilized and another detector is
employed to rectify the oscillations. In the form of the arrangement
shown in* Fig. 1 this is effected by transferring the strengthened
current oscillations, by means of the transformer fc, to a special
receiving circuit, where they are rectified by the detector I so that
1 Thig in Bchloemilch and Von Brouk'a invention.
156 Radio: Beam and Broadcast
they act on the telephone m. In this \vay the detector gives regular
unidirectional current impulses of low frequency, for example, in
the case of transmitting regular impulses as in sending devices in
wireless telegraphy in which the wave trains are produced at
acoustic frequencies, or the detector gives irregular unidirectional
current pulsations, also of low frequency, in the case of transmitting
speech in telephony.
The impulses or currents of low frequency given by the rectifier
can now be further strengthened by similar gaseous conducting paths
before they are led to the telephone or other indicating instrument.
For this method of operation an especially simple arrangement is
obtained, which is very effective in its working, by employing one
and the same gaseous path both for strengthening the high frequency
oscillations and also for strengthening the low frequency currents.
Fig. 2 shows an example of an arrangement for strengthening by
a plurality of gaseous path. Here again a is the vacuum tube with
the oxide cathode c, the anode d and the auxiliary anode e. The
oscillations excited in the coil g by way of the aerial conductor / are
led to the auxiliary anode e and cathode c in the same manner as in
Fig. 1. The strengthened high frequency oscillations then pass into
the circuit containing the source of direct current i through the
cathode c and anode d, and are transferred therefrom by the aid of
the transformer k to the detector circuit containing the detector I.
In this case it is convenient to provide an intermediate circuit n
tuned to the oscillations. The low frequency impulses or currents
furnished by the detector I are now led through a transformer o to a
second tube a 1 having a cathode c 1 , anode d 1 and auxiliary anode e 1 .
They are again strengthened by this tube and the strengthened
currents of low frequency are finally led from the circuit containing
the source of direct current i 1 through a further transformer p to the
telephone m or other indicating instrument. Obviously further
strengthening can be effected by other vacuum tubes.
A double strengthening by means of one and the same tube is
obtained in a very simple way by the arrangement shown in Fig. 3.
. . . Having now particularly described and ascertained the nature of
the said invention and in what manner the same is to be performed,
as communicated to me by my foreign correspondents, I declare that
what I claim is:
1. A receiving arrangement for use in wireless telegraphy and
telephony, having a gaseous path permanently ionized by a heated
cathode influenced by the electrical oscillations, in which the
oscillations, strengthened in known manner by an auxiliary current,
are by a rectifier made capable of being received by an indicating
device.
2. A receiving arrangement as in Claim 1, in which the pulsating
currents of comparatively low frequency are again strengthened by
similar gaseous paths working with heated cathodes, before said low
frequency currents are led to the indicating instrument.
3. A receiving arrangement as in Claim 1, in which the
158 Radio: Beam and Broadcast
strengthening of the currents of low frequency furnished by the
rectifier is effected by the same gaseous path which strengthens the
high frequency currents.
4. An .arrangement as in Claim 3, in which the low frequency
currents from the detector circuit are led through a transformer to
the gaseous path, and the secondary coil of this transformer is
inserted in the circuit leading the high frequency currents to the
gaseous path, the said currents being led to the indicating instrument
after strengthening through a second transformer, the primary coil
of which is inserted in the circuit connecting the gaseous path and
the detector, a condenser being inserted in parallel with the coils of
each transformer, said condenser being of low impedance for the
high frequency currents.
Dated this 14th day of April, 1913.
W. P. THOMPSON & CO.,
Agents for the Applicant.
COMPLETE SPECIFICATION SLIGHTLY ABRIDGED OF BR.
PAT. NO. 13,636, A.D. 1913
Date of Application, June 12, 1913
Complete Specification Lc//, January 12, 1914
Accepted, June 11, 1914
COMPLETE SPECIFICATION
IMPROVEMENTS IN RECEIVERS FOR USE IN WIRKLESS TELEGRAPHY
AND TELEPHONY
We, MARCONI'S WIRELESS TELEGRAPH COMPANY, LIMITED, and
CHARLES SAMUEL FRANKLIN, Electrical Engineers, both of Marconi
House, Strand, London, W.C., do hereby declare the nature of this
invention and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following
statement:
It has been shown that an exhausted tube which contains a
heated cathode consisting of a strip of metal covered with an oxide
and two anodes, one of which is in the form of a plate with holes
and which screens the cathode from the other anode, can be used in
a wireless receiver for magnifying both the received oscillations and
the telephone currents.
According to this invention when such a tube is used for
magnifying the received oscillations we make the circuit, in which
the magnified oscillations occur, react on the circuit, in which the
oscillations to be magnified occur, by coupling these circuits, either
tfoetrostatically or electromagnetically, to a certain degree,
Appendix
159
If the coupling be too strong, the tube will be unstable and will
itself tend to produce oscillations, but there is a certain critical
strength of coupling below which the tube is unable to maintain
oscillations. At a coupling a little below this critical strength the
tube and circuits are stable but act while receiving oscillations as
though the resistance in the circuits was very small.
The result is that the damping of the receiving system can be
reduced to any required degree and the tuning of the system is made
very sharp.
The accompanying diagram shows a scheme of connections to
obtain this result, v is an exhausted tube containing a cathode fc,
Fig. XV.
which is preferably a metal strip covered with an oxide, and is heated
by a battery 6 through a resistance r. ......
The anode a 1 is connected to a circuit containing inductances n
and o and a condenser / which are adjustable and the other side of
the condenser is connected through a battery s, the E.M.F. of which
may be about 200 volts, to the cathode ft. Across the condenser /
is connected a rectifier q, potentiometer p 1 , and a telephone or
detector t for detecting the oscillations in the circuit no/.
Magnified oscillations occur in the circuit no/ and when there
is no coupling between m and n, and all the circuits are tuned, the
valve produces in this circuit oscillations which are similar in
frequency and damping to the oscillations in the circuit I m c, but of
much greater intensity.
160 Radio: Beam and Broadcast
By coupling the circuits together by means of the coils m and n
the magnified oscillations in circuit no f may be made to sustain the
oscillations in the circuit m I c and the system then produces
continuous oscillation; if however the coupling is adjusted so that
the system just refuses to oscillate it will be found that the system
acts like a circuit of very low resistance and shows very sharp tuning.
The above circuits are arranged for high frequency oscillations
but obviously a similar circuit may be arranged for tuning to the
spark frequency of a wireless telegraph transmitter or to the note
obtained in a wireless telegraph receiver when using the interference
method of receiving continuous oscillations or generally for any case
in which sharp tuning is required.
By adjusting the couplings the system can be made to act as a
circuit having any desired decrement down to practically zero.
Having now particularly described and ascertained the nature of
our said invention and in what manner the same is to be performed,
we declare that what we claim is:
1. A receiving system for electrical oscillations which contains
a valve for magnifying the oscillations and which is so arranged that
the circuit in which are set up the magnified oscillation reacts on the
circuit in which occur the oscillations to be magnified substantially
as described.
2. A receiving system for electrical oscillations substantially as
described with reference to the drawing.
Dated this llth day of January, 1914.
CARPMAEL & CO.,
Agents for Applicants,
24 Southampton Buildings, London, W.C.
UNITED STATES PATENT OFFICE
EDWIN H. ARMSTRONG, OF YONKERS, NEW YORK
WIRELESS RECEIVING SYSTEM
SPECIFICATION OF LETTERS PATENT NO. 1,113,149.
PATENTED OCTOBER 6, 1914 (ABRIDGED)
Application filed October 29, 1913. Serial No. 797,947
To all whom it may concern:
Be it known that I, EDWIN H. ARMSTRONG, a citizen of the
United States, residing at 1032 Warburton Avenue, Yonkers, county
of Westchester, State of New York, have invented certain new and
useful Improvements in Wireless Receiving Systems; and I do hereby
declare the following to be a full, clear, and exact description of ths
ijr. XVI.
162 Radio: Beam and Broadcast
invention, such as will enable others skilled in the art to which it
appertains to make and use the same.
The present invention relates to improvements in the arrangement
and connections of electrical apparatus at the receiving station of a
wireless system, and particularly a system of this kind in which a
so-called " audion " is used as the Hertzian wave detector; the object
being to amplify the effect of the received waves upon the current in
the telephone or other receiving circuit, to increase the loudness and
definition of the sounds in the telephone or other receiver, whereby
more reliable communication may be established, or a greater distance
of transmission becomes possible. To this end I have modified and
improved upon the arrangement of the receiving circuits in a manner
which will appear fully from the following description taken in
connection with the accompanying drawings. As a preliminary, it is
to be noted that my improved arrangement corresponds with the
ordinary arrangement of circuits in connection with an audion
detector to the extent that it comprises two interlinked circuits; a
tuned receiving circuit in which the audion grid is included, and
which will be hereinafter referred to as the " tuned grid circuit," and
a circuit including a battery or other source of direct current and the
" wing " of the audion, and which will be hereinafter referred to as
the " wing circuit." As is usual, the two circuits are interlinked by
connecting the hot filament of the audion to the point of junction of
the tuned grid circuit and the wing circuit. I depart, however, from
the customary arrangement of these circuits in a manner which may,
for convenience of description, be classified by analysis under three
heads; firstly, the provision of means, or the arrangement of the
apparatus, to impart resonance to the wing circuit so that it is capable
of sustaining oscillations corresponding to the oscillations in the
tuned grid circuit; secondly, the provision of means supplementing
the electrostatic coupling of the audion to facilitate the transfer of
energy from the wing circuit to the grid circuit, thereby reinforcing
the high frequency oscillations in the grid circuit, and thirdly, the
introduction into the wing circuit of an inductance through which
the direct current of the wing circuit flows, and which is so related
to the grid circuit that the maintaining electromotive-force across the
terminals of the inductance due to reduction of the direct current, is
effective in the tuned grid circuit to increase the grid charge and
consequently to further reduce the current in the wing circuit and in
the telephones. By a further extension of this idea, the effect of the
maintaining electromotive-force upon the grid current may be
augmented by the use of a transformer in a manner which will be
understood from the following description.
Fig. 1 illustrates the arrangement and connection of apparatus
with which I have thus far obtained the best results and which
embodies in combination the several features of improvement which
I have invented or discovered. Fig. 2 represents a like arrangement
with the exception that there is no transformer for augmenting the
effect of the maintaining electromotive-force, and several condensers,
Fig. XVIa
164 Radio: Beam and Broadcast
which may advantageously be employed but which are not essential,
are eliminated. Fig. 3 illustrates an arrangement in which the
advantages of my invention are only partially present, the inductance
which produces the maintaining electromotive-force effective on the
(uned grid circuit being eliminated. Fig. 4 illustrates an arrangement
in which inductance, in this case the inductance of the telephones, is
employed for producing the maintaining electromotive-force effective
on the tuned grid circuit, but the wing circuit is not resonant.
Fig. 5 illustrates an arrangement in which an inductance replaces the
telephones in that portion of the connections which is common to the
two circuits, and the telephones are put in the wing circuit, and
Fig. 6 illustrates an arrangement in which a double winding
transformer is used, the primary being located in the wing circuit.
... I find that with such an arrangement of apparatus, and by
properly adjusting the reactances, signals which arc scarcely audible
with the ordinary audion connection can be amplified to a point
where they are too strong for, and " paralyse " the most stable
audions that I have been able to obtain. .....
It will be observed, that this capacity of the telephone cords in
Figs. 2 and 4, and likewise the capacity C 5 in Fig. 5 and the
distributed capacity of the transformers in Figs. 1 and 6, is in each
case common to the grid circuit and the wing circuit and constitutes
an electrostatic coupling facilitating the transfer of energy from the
wing circuit to the grid circuit and increasing the effect upon the
grid of high frequency pulsations in the wing circuit. This effect
occurs whether the wing circuit is tuned or not, but obviously the
transfer of energy is increased by tuning the two circuits alike. I
have discovered, however, that the beneficial effect may be still further
increased by the interposition of a transformer in such a way as to
increase the effect of the maintaining electromotive-force due to the
reduction of current through the telephone receivers, and such a
transformer is shown at T in Fig. 1. ... It will be understood from
what has been said that the ratio of transformation of the
transformer should be adjusted to get the maximum signals without
causing the audion to generate oscillations. .....
From what has been said, it will be understood that the
inductance of the telephones may be utilized as the generator of
the maintaining electromotive-force by inserting the telephones in the
connections common to the two circuits, as shown in Figs. 1, 2 and 4;
but a like result will be obtained by locating the telephones in the
wing circuit as indicated in Fig. 5, and placing a suitable inductance
as L 2 in that portion of the connections which is common to the two
circuits. ............
The way to tune this set is to cut out L 1 , set C 1 at "00005
microfarads, and then adjust P, S, L and C as in the ordinary audion
set until signals are strongest. The inductance L 1 is then gradually
cut in and the strength of the signals will increase many times until
a point is reached where the signals lose distinctness and there is a
loud hiss in the telephones. This indicates that the audion is
Fig. XVU.
166 Radio: Beam and Broadcast
generating high frequency oscillations in the grid and wing circuits,
and the inductance L 1 should be set at a point just below that at which
this occurs. If there is no hiss as L 1 is increased, and the signals
pass through a maximum of strength and begin to fall off, then L 1
should be set at the point of maximum strength of signals and G 1
should be increased to a point just below that at which the hiss
appears. Under these circumstances, the increase of C 1 will be
accompanied by an increase of the strength of the signals, the
maximum strength being obtained in each case just below that point
at which the audion begins to act as a generator of high frequency
oscillations.
I find that the capacity required to by-pass the oscillations about
the inductance which is common to the two circuits, and about the
transformer, if the transformer is used, is relatively small; and when
the telephone receivers are used as the inductance at this point, the
capacity of the telephone cords is sufficient. .....
Having thus described my invention, what I claim is:
1. An audion wireless receiving system having a resonant wing
circuit interlinked with a resonant grid circuit upon which the
received oscillations are impressed, the resonant grid circuit having
a capacity so related to the grid as to receive and retain the charge
which accumulates thereon.
16. An audion wireless receiving system having a resonant wing
circuit interlinked with a resonant grid circuit upon which the
received oscillations are impressed, and means supplementing the
coupling of the audion to facilitate transfer of energy from the wing
circuit to the grid circuit, whereby the effect upon the grid of high
frequency pulsations in the wing circuit is increased.
17. An audion wireless receiving system having a wing circuit
interlinked with a resonant grid circuit upon which received
oscillations are impressed and an electrostatic coupling between the
circuits supplementing the coupling of the audion to facilitate
transfer of energy from the wing circuit to the grid circuit, whereby
the effect upon the grid of high frequency pulsations in the wing
circuit is increased. ..........
In testimony whereof I affix my signature, in presence of two
witnesses.
EDWIN H. ARMSTRONG.
Witnesses :
WILLIAM H. DAVIS,
JOHN C. PENNIE.
AUTHOR'S NOTE. The status of this patent must be considered
in the light of the judgment quoted on page 46.
Appendix 16T
EXTRACTS FROM THE COMPLETE SPECIFICATION OF
BR. PAT. NO. 28,413. A.D. 1913
Date of Application, December 9, 1913
Complete Specification Left, July 8, 1914
Accepted, December 9, 1914
COMPLETE SPECIFICATION
IMPROVEMENTS in RECEIVERS FOR USB in WIRBLBSS TBLBGRAPHY
We, MARCONI'S WIRELESS TELEGRAPH COMPART, LIMITED', and
HENRY JOSEPH ROUND, both of Marconi House, Strand, London, W.C.,
Electrical Engineers, do hereby declare the nature of this invention
and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:
This invention relates to improvements in receivers for wireless
telegraphy in which a vacuum tube of the type having a hot filament,
a grid and a third electrode is employed.
According to this invention we connect across the hot filament
and the third electrode, and in addition to the ordinary telephone and
battery, an oscillation circuit which is tuned to a frequency slightly
different from that of the received oscillations. By suitably adjusting
the circuits, signals produced by continuous waves can be heard in
the telephones. If the capacity between the grid and the third
electrode is insufficient, a small condenser may be connected across
the grid and the third electrode, or the oscillation circuit may be
made to interact with the aerial or with an intermediate oscillation
circuit by so arranging the circuits that there is mutual inductance
between them. ...........
Our invention is illustrated in the accompanying drawing. 1
Having now particularly described and ascertained the nature of
our said invention and in what manner the same is to be performed,
we declare that what we claim is:
1. In a receiver for continuous waves having a vacuum tube
containing a hot filament, a grid and a third electrode, an oscillation
circuit tuned to a frequency slightly different from that of the received
waves and connected across the filament and the third electrode
substantially as described.
2. A receiver as claimed in Claim 1 in which the oscillation
circuit is caused to interact with the aerial or with an intermediate
circuit substantially as described.
3. A vacuum tube containing a hot filament, a grid formed as a
closed cylinder completely surrounding the filament and a third
electrode, in the form of a cylinder surrounding- the grid substantially
as described.
1 P. 100.
168 Radio: Beam and Broadcast
4. Wireless telegraph receivers substantially as described with
reference to the drawing.
Dated the 8th day of July, 19H.
CARPMAELS & CO.,
Agents for Applicants.
EXTRACTS FROM THE AMENDED SPECIFICATION OF
BR. PAT. NO. 252. A.D. 19U
Date of Application, January 5, 1914
Accepted, August 19, 1915
COMPLETE SPECIFICATION (AMENDED)
IMPROVEMENTS IN AND RELATING TO RELAY ARRANGEMENTS FOR
ALTERNATING CURRENTS
We, GRAF GEORG VON ARCO and DR. ALEXANDER MEISSNER, both
of Tempelhofer Ufer 9, Berlin, in the Empire of Germany, Engineers,
do hereby declare the nature of this invention and in what manner
the same is to be performed, to be particularly described and
ascertained in and by the following statement:
The present invention relates to a new arrangement of electrical
relays in which the means exerting the relay action essentially consist
of an ionized gas. A specially suitable form of this relay consists of
a glass vessel wholly or partially evacuated or filled with gas or
vapour at a low pressure, which vessel contains a heated oxide cathode
and one or more anodes. The cathode rays streaming from the
oxide cathode effect an ionization of the gas so that a permanent
current path is made from the anode to the cathode. The currents
to be strengthened may be led to the heated cathode and an auxiliary
anode. The strengthened currents are then developed in the current
circuit, being led through the cathode and main anode, by which
means the increased energy of this current is obtained from the source
of current furnishing permanent current. In another form which
resembles the known Braun's cathode ray tube, the oscillations to be
strengthened are led to two special electrodes between which are
passed streams of ions from anode to cathode.
Since the active element of this relay has no mass, in contra-
distinction to mechanically operating relays, these relays are especially
well suited for such alternating currents in which the current
variations take place very rapidly and for such purposes in which an
exact repetition of all changes is desired, for example, for strengthen-
ing microphone currents and especially for the strengthening and
generation of the rapid oscillations in wireless telegraphy and
telephony.
The present invention relates to the arrangement of the current
M
/:
"
fiuf.Z.
ftyd.
Fig. XVII. Round's &r. Pat. 28,413/13 (see p. 167.)
170 Radio: Beam and Broadcast
circuit operating with the relay. This arrangement essentially
consists in that the circuit, which is connected to the secondary path
of the relay, i.e., to which the strengthened relay current is led, is
again connected with the circuit carrying the original current and
connected with the primary path of the relay, so that the energy
furnished by the relay again passes into the relay with unchanged
frequency.
By this return coupling a considerable improvement of the relay
action is attained, i.e., a strengthening of weak currents which
surpasses that attainable in known arrangements. At the same time
the return passage of the energy in this arrangement renders possible
a mode of action of this relay which is quite novel. Thus if a relay
so arranged is connected with an electric system capable of oscillation,
it is then possible to maintain a permanent condition of oscillation in
the system. More particularly for wireless telegraphy and telephony
this is of very great importance since by this means it is possible for
the first time to generate undamped oscillations possessing an
absolutely constant amplitude.
The new arrangement further renders possible the formation of
specially active receiving arrangements by allowing the relays so
arranged to co-operate with a receiving arrangement in a common
detector or indicator circuit. If the oscillations generated by the relay
are given, in a manner known per se, a frequency somewhat diverging
from the oscillations received, then by means of an ordinary receiving
apparatus it is possible to receive undamped oscillations in the form
of completely pure tones, produced by interference of the two
oscillations. By the strengthening which is thus possible oscillations
can be received of such small intensity as can no longer be rendered
perceptible by other means; in this way it is possible to magnify the
range of wireless stations
Fig. 6 represents a simple exciting arrangement.
The generation of oscillations also takes place when using an
alternating current of low period, and since the tubes as mentioned
above possess a valve action this generation always takes place in the
half period in which there is a positive potential at the anode 3. In
this way trains of oscillations are obtained which are separated by
pauses of the length of a half period of the alternating current supply.
In order to be able to generate uninterrupted oscillations with an
alternating current supply, it is preferable to employ two relays
connected in parallel in such manner that during one half period the
alternating current supplied operates one relay while during the other
half period the reverse is the case
The energy which can be generated by this generator can attain
fairly considerable values so that it is possible indeed to employ this
generator for transmitting purposes in wireless telegraphy. This
excitation arrangement is particularly suitable however for receiving
very weak currents when producing sounds in that the oscillations
received are caused to interfere with the oscillations generated in the
above manner at the receiving station
Fig.6
Fig. XVIII.
172 Radio: Beam and Broadcast
It in this interference arrangement the relay acting as generator
is supplied with alternating current in the manner described, it is
convenient in order to obtain a pure sound to choose the frequency of
this alternating current supply comparatively low so that within one
alternation a number of beats takes place.
The strengthening action of the arrangement makes it possible
to detect easily even very weak signals from very distant sending
stations which signals are otherwise scarcely perceptible, but even
in those cases in which the incoming signals are in themselves
sufficiently strong for detection, this arrangement makes it possible
to secure other advantages which consist in a very thorough selection
from atmospheric and other disturbances. .....
Experiments with this receiving arrangement have shown that
it is possible to produce easily audible sounds by the interference
arrangement when two oscillations are made not approximately equal,
but considerably different from one another. This is the case
when the oscillations generated at the receiving place are given a
frequency which is either near to an over-tone or an under-tone
of the oscillations received which therefore differs therefrom by an
approximate multiple. This procedure is of special advantage in the
case of receiving damped oscillations generated by sparks.
The interference arrangement above described can also be
employed several times in series in such manner that the interfer-
ence oscillation first generated co-acts with a second oscillation
generator which generates a current of diverging frequency again
causing interference. In this way it is possible with certainty to
remove all disturbances caused by atmospheric discharges or other
causes. ............
Having now particularly described and ascertained the nature of
our said invention and in what manner the same is to be performed,
we declare that we do not claim the inventions claimed in Specifications
Nos. 13,636 and 28,413 of 1913 and No. 24,231 of 1914, but what we
claim is:
1. A relay arrangement for alternating currents particularly
suitable for wireless telegraphy and telephony having an electric
relay operating by means of an ionized gas path in which the current
strengthened by the relay is led with unchanged frequency directly
or indirectly to the primary circuit of the relay again, so that the
whole of this current or a part thereof repeatedly passes through the
relay and is thus further strengthened.
2. An arrangement as in Claim 1 in which the primary current
to be strengthened is directly or indirectly led both to the relay and
also to the detector circuit or the indicating instrument.
3. An arrangement as in Claims 1 or 2 in which the indicating
instrument or the detector circuit is directly coupled with the antenna
or the telephone line.
4. An arrangement as in any of the preceding claims in which
the indicating instrument (telephone) is directly connected (for
example by means of a transformer) with the circuit coupled back to
Appendix
178
the primary circuit of the relay and receiving the strengthened relay
current.
5. An arrangement as in Claim 4 in which a regulable alternating
current resistance (condenser or choking coil) is connected in parallel
Fig. 10
13-
Fzg. &
*~S 2 f
f**-
-\\yvwwwv
XVIIIa.
or in series with the telephone transformer, for regulating the
reception of energy by the indicating instrument.
6. An arrangement as in Claim 1 in which a closed adjustable
oscillation circuit is connected with the primary current circuit or
the secondary current circuit of the relay.
174 Radio: Beam and Broadcast
7. An arrangement as in Claim 6 in which the closed oscillation
circuit is connected both with the side of the relay taking weak
current (primary) and that giving strengthened current (secondary),
so that the initial oscillations excited in the oscillation circuit are
strengthened by the relay and will be maintained.
8. An arrangement in which a high tension alternating current
is employed to supply the oscillation generator as in Claim 7.
9. An arrangement as in Claim 8 in which two relays are
connected in parallel with the source of alternating current in such a
manner that the anode of one and the cathode of the other are always
at the same pole of the source of alternating current so that both
relays alternately operate corresponding to the half periods of the
alternating current, thus making the generation of oscillations
continuous.
10. An arrangement as in Claims 7, 8 or 9 in which the return
coupling of the oscillation circuit with the relay is effected through
two special auxiliary electrodes placed opposite to one another in the
relay, between which electrodes passes the stream of ions flowing from
the cathode to the anode.
11. A relay adapted for use in an arrangement as claimed in
Claim 10 having two auxiliary electrodes of comb, spiral or the like
shape arranged inter-engaging, for the purpose of strongly affecting
the stream of ions.
12. In an arrangement as claimed in Claims 7 to 11, a relay
having the cathode material of tungsten, tantalum, osmium or
carbon without a coating of oxide so that it is possible to obtain a
higher load and a greater utilization of the energy of the relay in
generating oscillations.
13. An arrangement as claimed in any of the preceding claims
for receiving electric oscillations in which the relay connected by
return coupling with a closed oscillation circuit, and thus operating
as an oscillation generator, and a receiving antenna, act in common
on a receiving apparatus comprising a detector and indicating
instrument, and in which the frequency of the oscillations generated
due to this relay is made approximately equal to the frequency of the
oscillations received, in order to strengthen the oscillations received
by interference and to make them perceptible as pure and readily
audible sounds.
14. An arrangement as in Claim 13 in which when the
relay is supplied by alternating currents, the frequency of the
alternating current supply is made low in comparison to the number
of oscillations of the beats desired, to obtain pure sounds.
15. An arrangement as in Claim 13 in which the coupling
between the antenna and the receiving system is made as loose as
possible in order to diminish the action of atmospheric disturbances
on the receiving apparatus.
16. An arrangement as in Claim 13 in which the frequency of
the oscillations generated by the relay is variably regulated to an
approximate multiple of the frequency 'of the oscillations received.
Appendix 175
17. An arrangement as in Claim 13 in which several relays acting
as oscillation-generators each connected with a detector circuit, are
employed in series for causing interference action and in which the
indicator (telephone) is first connected with the last relay arrangement
in order to render the receiving perceptible.
18. An arrangement as in Claim 1 in which the relay is
connected with two closed oscillation circuits tuned to different
frequencies.
19. An arrangement as in Claim 1 for receiving electric
oscillations in which a relay connected with a closed oscillation circuit
by return coupling and acting as a generator of oscillations is coupled
with a second closed oscillation circuit, tuned to an audible frequency,
and with the antenna, in such a manner that the interference
produced by infringement of waves, between the oscillation of the first
circuit and the oscillation of the antenna, influences the second
oscillation circuit so that the signals are perceptible by changes of
intensity or sound of the permanent sound produced.
20. An arrangement as in Claim 19 in which an acoustic or
electric resonator co-acts with the indicator in such a manner that
essentially only the sound of the signal is perceptible in the indicator.
21. A relay arrangement for alternating currents substantially
as described and illustrated with reference to the accompanying
drawings Figs. 1 to 8 and Figs. 11 and 12.
Dated this 3rd day of January, 1914.
W. P. THOMPSON & CO.
UNITED STATES PATENT OFFICE
ELIHU THOMSON, OF SWAMPSCOTT, MASSACHUSETTS,
ASvSIGNOR TO THE THOMSON - HOUSTON ELECTRIC
COMPANY, OF CONNECTICUT
METHOD OF, AND MEANS FOR PRODUCING ALTERNATING CURRENTS
SPECIFICATION FORMING PART OF LETTERS PATENT NO. 500,630,
DATED JULY 4, 1893 (ABRIDGED)
Application filed July 18, 1892. Serial No. 440,698. (No model)
To all whom it may concern:
Be it known that I, ELIHU THOMSON, a citizen of the United
States, residing at Swampsrott, in the county of Essex and State of
Massachusetts, have invented a certain new and useful Improvement
in Methods of and Means for Producing Alternating Electric Currents*
of which the following is a specification.
The present invention relates to methods of and apparatus for
176
Radio: Beam and Broadcast
obtaining alternating currents from a continuous current source or
from a source in which the currents are intermittent or from a source
in which the potential is sustained during a period more or less great.
My invention is applicable particularly to obtaining currents of
and effects of high frequency alternations from continuous current
lines or sources. The frequencies obtained can be adjusted or varied.
Thus from a five hundred volt supply circuit I may obtain alternating
current effects the frequency being, say, ten thousand, twenty thousand,
thirty thousand, fifty thousand per second, or more. I may also obtain
inductively from the alternating currents of a desired frequency, other
7t//
Fig. XIX.
alternating currents (by transformers or condensers in the ordinary
way), and may employ such currents for any such purposes for
which alternating impulses are applicable.
In Fig. 1 is a diagram showing the features of my invention.
Fig. 2 is another diagram showing some additional features.
What I claim as new, and desire to secure by Letters Patent, is
7. The method of obtaining high frequency currents from
continuous currents, consisting in establishing a circuit in which
rapid current changes cannot easily take place, and rupturing said
circuit at suitable terminals bridged by a condenser, with inductive
devices or self-induction coils of wire in said bridge, the capacity
Appendix 177
self-induction in such bridging path together with the spark gap
or rupture distance being adjusted or adjustable, substantially as
set forth.
8. The method of obtaining high frequency currents from
continuous currents, consisting in establishing a circuit in which
rapid current changes cannot easily take place, and rupturing said
circuit by a magnetic field at suitable terminals bridged by a
condenser, with inductive devices in said bridge, substantially
as described.
9. The method of obtaining from continuous currents or currents
tending, through self-induction or otherwise, to remain unchanged,
or to resist sudden change of value, high frequency alternating
currents of desired periodicity consisting in bridging by determinate
capacity of condenser and a determinate self-induction coil or circuit,
a spark gap in said continuous current circuit, said spark gap being
adjusted and arranged so as to respond to the desired frequency,
substantially as set forth. ........
In witness whereof I have hereunto set my hand this 13th day of
July, 1892.
ELIHU THOMSON.
Witnesses :
JOHN W. GIBBONEY,
ALEC F. MACDONALD.
EXTRACT FROM COMPLETE SPECIFICATION OF BR.
PAT. NO. 21,629, A.D. 1900
Date of Application, November 29, 1900
Complete Specification Left, August 29, 1901
Accepted, November 23, 1901
COMPLETE SPECIFICATION
IMPROVEMENTS IN AND CONNECTED WITH MEANS FOR THE CONVERSION
OF ELECTRICAL ENERGY, DERIVED FROM A SOURCE OF DIRECT
CURRENT, INTO VARYING OR ALTERNATING CURRENTS
I, WILLIAM Du Bois DUDDELL, of 47 Hans Place, London, S.W.,
Electrical Engineer, do hereby declare the nature of this invention
and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement:
This invention relates to the conversion of electrical energy
derived from a source of direct current, into varying or alternating
currents of sympathetic or controllable periodicity, and has for its
object the provision of a method and means, by which such conversion
may be effected without the employment of moving contacts; the
M
178 Radio: Beam and Broadcast
resulting current being so sympathetic as to its variations or
alternations that it may be utilized to reinforce an existing varying or
alternating current, or the periodicity of its alternations may be
determined by utilizing known means having self-induction and
capacity; and this invention has for its further object the adaptation
of such a converted sympathetic current to purposes of practicable
utility, such as the reinforcement of the energy of an already existing
varying current, as a telephone current, so as to increase the loudness
of speech, or the distance to which speech can be transmitted; and the
reinforcement of telegraph currents; and for the production of
alternating currents; and for the indication of frequency or its
variations under certain conditions hereinafter to be defined; and
for like purposes. ..........
I can use as my converting device, the electric arc between solid
carbon or other electrodes; and other gaseous conductors, such as
vacuum tubes, exhausted to a suitable pressure, and containing
suitable gases or vapours; or metallic oxides or salts, or the mixtures
of any of these such as a filament of the Nernst lamp; or any other
conductors belonging to the class of electrolytic conductors, which
fulfil the above defined necessary condition.
I have found that when such a converting device is made to form
part of a circuit connected to the source of direct current energy, I
can obtain in a shunt circuit between the terminals of such converting
device a current which is sympathetic, as to its variations or
alternations, to any existing varying or alternating currents flowing
in the circuit, which it will therefore reinforce.
Or, I can obtain in the shunt circuit an alternating current of
any required frequency, which frequency is determined by the self-
induction, capacity, and resistance of that shunt circuit as hereinafter
more fully defined.
I find that under suitable conditions part, or the whole of the
circuit containing the source of direct current energy can be used in
forming the above-mentioned shunt circuit to the converting device,
so that the reinforcing of the energy of an already existing varying or
alternating current, or the production of alternating current may take
place in the circuit containing the source of direct current energy
with or without the use of the whole or part of the above-mentioned
shunt circuit. ...........
In order to increase the energy of an already existing varying or
alternating current, the converting device should be made to form
part of the circuit in which the existing current is flowing.
I find it an advantage, in some cases, to prevent direct current
energy from flowing round the shunt circuit, and for this purpose I
may employ a condenser, and also to prevent the varying or
alternating currents from flowing round the circuit containing the
source of direct current energy, and for this purpose I use a highly-
inductive resistance. ..........
Such a method and device will produce alternating currents or
of high frequency and constant amplitude, which e*a be
Appendix 179
used with advantage, in wireless telegraphy especially where it is
required to tune the transmitter and receiver to syntony, as compared
with present methods in which a series of groups of oscillations are
used, the oscillations in each of the said groups, rapidly decreasing
in amplitude. ...........
When using as a converting device a conductor, such as the
electric arc, which emits sound waves when the current through it
varies, I find the pitch of the sounds emitted is determined by the
frequency of the variations of the current flowing through it, and
will thus give an audible indication of such frequency or change of
frequency, which may be applied to practical purposes. A series of
musical notes may be artificially produced in such case, by a control
of the frequency of the varying current, which may be done by
varying as by means of a keyboard the capacity or self-induction or
both of the shunt circuit which I use in carrying out my invention.
Having now particularly described and ascertained the nature of
my said invention and in what manner the same is to be performed,
I declare that what I claim is:
1. A method and means for the conversion of electrical energy
obtained from a source of direct current into the energy of varying
or alternating currents which are sympathetic, or of controllable
frequency, consisting of utilizing a specific conductor connected to a
source of direct current in such a way that the said specific conductor
shall form part of the circuit in which the varying or alternating
current energy is required, the aforesaid specific conductor being of
such a character that the ratio of the change in the current passing
through the said conductor to the corresponding change in the
potential difference between the terminals of the said conductor is a
negative quantity, substantially as hereinbefore described.
5. In a method for the conversion of electrical energy derived
from a source of direct current into the energy of varying or
alternating currents, in which the electric arc is used as the specific
conductor or converting device, controlling the frequency of the
varying or alternating current, as by means of a keyboard, for the
production of a series of musical notes, substantially as described.
Dated this 29th day of August, 1901.
FELL & JAMES,
1 Queen Victoria Street, London, E.G.,
Agents for the Applicant.
180 Radio: Beam and Broadcast
EXTRACTS FROM THE AMENDED SPECIFICATION OP
BR. PAT. NO. 15,599, A.D. 1903
(Amended in accordance with the decision of the Comptroller-General,
dated the llth day of June, 1917)
Date of Application, July 14, 1903
Complete Specification Left, April 13, 1904
Accepted, July 14, 1904
COMPLETE SPECIFICATION (AMENDED)
IMPROVEMENTS RELATING TO THE PRODUCTION OF ALTERNATING
ELECTRIC CURRENTS
I, VALDEMAR POULSEN, of 22 St. Blichcrsvej, in the City of
Copenhagen and Kingdom of Denmark, Civil Engineer, do hereby
declare the nature of this invention and in what manner the same is
to be performed, to be particularly described and ascertained in and
by the following statement:
As demonstrated by Duddell (British Patent No. 21,629, 1900), it
is possible by suitable employment of self-induction, capacity, and
an electric conductor of such a character, that the ratio of the
change in the current passing through the said conductor to the
corresponding change in the potential difference between the terminals
of the said conductor, is a negative quantity, that is to say: the
potential decreases, when the current increases, to produce an
alternating current from a continuous current. In this way, only a
proportionately low efficiency has hitherto been reached.
The present invention aims at increasing this efficiency by placing
the conductor in question in the form of an electric arc in an
atmosphere consisting of hydrogen or hydrogen compounds producing
in a similar way alternating currents of greater useful effect, and, if
desired, of a much higher frequency (200,000 1,000,000 or more),
the conductor being at the same time arranged in a magnetic
field, by which the effect is still more essentially increased.
On Fig. 1, a and b indicate the feed conducting wire for a
continuous current, d a self-induction coil, e an electric arc, formed
between two carbons, I the self-induction of the circuit of the
alternating current and fc a condenser. The number of alternations
of the circuit of the alternating current is then found to b
approximately
10 s 1
1L_ L__ per second
2*- VLK
where L is henry and K microfarad. On account of the self-
induction coil d, alternating currents are prevented from streaming 1
F.I. F.2.
* 6 a I) a
-.<?
J
I
F.4.
F.5.
E8.
Si
^
/k
I
VWA '
Fig. XX.
182 Radio: Beam and Broadcast
out in the feed conduction wires. As stated, the alternating currents,
produced in this way, are rather limited, both as regards intensity
and number of vibrations. However, by introducing the electric arc
into an atmosphere of hydrogen or some other hydrogen compound,
the efficiency, intensity and frequency can be increased considerably.
A simple method of carrying out the invention (the magnetic
field mechanism not being shown) is shown in Fig. 2 the electrio
arc e being surrounded by an atmosphere / containing hydrogen.
This can most simply be executed by arranging the electric arc and
the neighbouring parts of the electrodes in a flame of illuminating
gas near the opening for letting out the gas.
Fig. 3 shows the same device, but with two self-induction coils
Jj and 1 2 placed one on each side of the electric arc in the alternating
circuit.
The device shown in Fig. 4 has two self-induction coils d t and d a
which prevent the alternating current from streaming out upon the
conductors of the continuous current and are inserted one on each id
of the electric arc.
When the intensity of the current exceeds a certain limit, tht
alternating currents will cease.
Fig. 6 shows a device, by which it is possible to transfer a
considerable quantity of energy with same number of vibrations in the
system of alternating currents, by means of a plurality of electric arcs
placed in parallel. The letters a b d, and d a refer to like parts as in
Fig. 4
The substantial self-induction of the alternating system is here
placed in I and the substantial resistance in the electric arcs e l a
and ij.
The capacity of each of the condensers fcj fe a and k 3 is greater than
the capacity of the condenser h and the capacities are mutually
adjusted in such a manner, that the electric arcs e t e 2 and e^ are
approximately or completely syntonized.
As will be seen, the condensers fej fe 2 and fe, keep the electrodes m l
m a and m a thus separated from each other that continuous current
cannot pass from one electrode to the other. As the electrodes
n r n a and n% have all the same potential, they may be replaced by a
ingle electrode. ..........
In this and similar ways as many electric arcs as desired may be
joined in parallel and a syntonic addition of the alternating currents,
produced by the electric arcs, can be obtained. Of course the
alternating currents, produced by the electric arcs arranged in
parallel can have different frequencies and the interference effect
resulting therefrom, can be employed. .....
If, as shown in Fig. 8, the self-induction I forms the primary
coil of a transformer, oil-insulated, an alternating current of higher
or lower potential can be induced in the secondary coil of same.
The secondary conductor o combined with the devices known in the
art of wireless signalling, can be used for wireless telegraphy, and
UUphony, and on account of the continuance of tht waves produced,
I
I
I
x x
y
t
XX.
184 Radio: Beam and Broadcast
being of determined length, the system is fit for syntonized telephony
and telegraphy. ...........
Wireless signalling and all the other phenomena mentioned can
be carried out even without a real transformer, when sufficient
difference of potential between the coatings of the condenser k is
produced. ...........
It is not necessary, that the feed-conductors a and b should
conduct continuous current; an alternating current can also in the
manner above described be transformed into an alternating current
of some other frequency. ........
An essentially more useful effect is obtained by placing the arc in
a magnetic field, the lines of force of which are perpendicular to
the conductor, or have some other suitable position. The magnet
can either be a permanent or an electro-magnet, and this latter
can be energized from the same source of electricity as the electric
arc.
It is specially suitable to produce the electric field by means of
an electro-magnet (with or without iron-core), which is placed in
series with the electric arc. The inductive resistances d x and d 2 can
then form the coils of the electro-magnet. In some special cases the
self-induction I, L and L may also serve for producing the magnetic
field
As illustrated in Fig. 12 the magnetic field is produced by means
of a pair of electro-magnets t; v the coils of which are traversed by
the current which feeds the arc.
Fig. 13 shows a device only differing from the device shown in
Fig. 12 in that only part of the feeding current is led through the
magnet coils, the remainder of the current passing through a
resistance, the amount of which can be varied by turning the switch
arm y. The intensity of the electro-magnetic field can thereby be
regulated as desired.
Fig. 14 shows a diagram in which the coils of the magnets v v
are placed as self-induction coils in the feed-conductors of the electric
arc, and act in the same manner as the self-induction coil d in the
other diagrams described.
The manner in which the electric arc is placed in a hydrogenic
atmosphere can be greatly varied. In addition to the gas-flame
previously mentioned, alcohol vapour, ether vapour or the like can
be used, which vapours probably by the influence of the electric arc,
will be dissociated into hydrogen and carbon. The electric arc can
also be placed in a reservoir, containing hydrogen or a gaseous
hydrogen-compound. . . . The pressure in the reservoir may be
higher or lower than the pressure of the atmosphere.
Fig. 16 shows an electrode, which can be cooled off by leading
a jet of water in through the tube 7 and out through the tube 6 or
vice versa.
The employment of such a cooled-off copper electrode as anode
and a carbon rod as cathode is very appropriate.
An inconvenient deposit of carbon may take place by tht
Appendix 185
employment of carburetted hydrogen as media, or when carbon is
employed as material for the electrodes; or Ihe electrodes may be
worn out in an irregular manner. Therefore it would be preferable
to make the electrodes mutually adjustable, so that the pole-area is
continually changed. .........
The invention as herein described may obviously be modified and
the parts arranged in various forms to suit special requirements
without departing from the spirit of the invention.
Having now particularly described and ascertained the nature of
my said invention and in what manner the same is to be performed,
I declare that what I claim is:
1. Method for producing alternating currents with a high
frequency by means of an electric conductor in the form of an
electric arc the quality of which is that the ratio between an alteration
in the current passing through the conductor in question and the
corresponding alteration in the potential difference between the
terminals of the conductor is a negative quantity, connected with a
source of electricity in such a manner, that the conductor in question
forms a part of the circuit in which the varying or alternating
currents are produced, characterized by the conductor being arranged
in an atmosphere of hydrogen or hydrogen-compound, and in a
magnetic field.
2. A modification of the method mentioned in Claim 1
characterized by the hydrogen containing atmosphere surrounding
the conductor being submitted to a pressure higher than one
atmosphere.
3. A modification of the method mentioned in Claim 1
characterized by the hydrogen containing atmosphere surrounding
the conductor being submitted to a pressure lower than one
atmosphere.
4. A modification of the method mentioned in Claim 1
characterized by the electrodes being cooled off in a suitable manner.
5. A modification of the method mentioned in Claim 1
characterized by a plurality of conductors, e 1 c 2 <? 3 arranged in
parallel with associated condensers /c x fc 2 fe a in series with the
self-induction I of the alternating circuit (Figs. 5 and 6).
6. A modification of the method mentioned in Claim 5
characterized by the electric arcs arranged in parallel having a
common electrode.
7. A modification of the method mentioned in Claim 1
characterized by a plurality of conductors being arranged in series.
8. A modification of the method mentioned in Claims 1-7
characterized by the alternating currents being conducted to a branch
conductor of the condenser k.
9. A modification of the method mentioned in Claim 1
characterized by the produced alternating currents of a high
frequency, being employed in connection with apparatuses for wireless
telegraphy and telephony and other wireless transmission of energy.
10. A modification of the method mentioned in Claims 1-7
186 Radio: Beam and Broadcast
characterized by the alternating currents being used for producing
cathode-rays, Rontgen-rays, and the like.
11. A modification of the method mentioned in Claims 1-10
characterized by either one or more electrodes being arranged to
rotate.
12. A modification of the methods mentioned in Claims 1-11
characterized by the magnetic field being produced by an electro-
magnet, the coil of which is traversed by the current, which feeds
the conductor.
13. A modification of the methods mentioned in Claims 1-11,
characterized by the coils of the electro-magnets being used as
elf -induction coils in the feed conductors for the electric arc.
Dated this 13th day of April, 1904.
HASELTINE, LAKE & CO.,
7 & 8 Southampton Buildings, London, W.C.,
Agents for the Applicant.
BIBL1OGKAFHY
1. A History of Wireless Telegraphy, 1838-1899. By J. J. Fahie.
Wm. Blackwood and Sons, London.
2. Wireless Telegraphy. By A. Frederick Collins. McGraw
Publishing Co., New York, 1905.
3. An Elementary Manual of Radio-telegraphy and Radio- telephony.
By J. A. Fleming, Longmans, Green and Co., London, 1916.
4. Forty Years of Electrical Progress. " The Electrician " Publish-
ing Co., London, 1916.
5. A Handbook of Wireless Telegraphy. By James Erskine-Murray.
Crosby Lockwood and Son, London, 1914.
6. Text Book of Wireless Telegraphy. By Rupert Stanley.
Longmans, Green and Co., 1918.
7. Journal, Institution of Electrical Engineers. London, March, 1920
7o. Journal, Institution of Electrical Engineers. London, Dec. 1921.
76. Journal, Institution of Electrical Engineers. London, May, 1922.
7c. Journal, Institution of Electrical Engineers. London, Aug. 1922.
Id. Journal, Institution of Electrical Engineers. London, June, 1921.
8. Proc., Institute of Radio Engineers, New York. (Specific
references given in text.)
9. The Illustrated Official Journal (Patents); May llth, 1921.
Supplement.
10. Journal, Royal Society of Arts. London, December 9th, 1921.
10a. Journal, Royal Society of Arts. London, June 9th, 1922.
10b. Journal, Royal Society of Arts. London, December 16th, 1921.
lOc. Journal, Royal Society of Arts. London, July llth, 1924.
lOd. Journal, Royal Society of Arts. London, July 25th, 1924.
11. The Year-Book of Wireless Telegraphy. The Wireless Press,
Ltd., London, 1915.
lib. The Year-Book of Wireless Telegraphy. The Wireless Press,
Ltd., London, 1919.
lie. The Year-Book of Wireless Telegraphy. The Wireless Press,
Ltd., London, 1921.
12. Wireless Telegraphy. By Dr. J. Zenneck. Translated from
German by A. E. Seelig. McGraw-Hill Book Co., New York.
13. Dictionary of Applied Physics. R. Glazebrook. Macmillan, London.
14. London Daily Telegraph. December 4th, 1923.
15. The Thermionic Valve. J. A. Fleming. Wireless Press, London.
16. Report from the Select Committee on Radio- telegraphic
Convention. Wyman and Sons, Ltd., London, 1907.
17. " fei&tt," August 6th, 1920, Vol. LU, p. 19*.
187
188 Radio: Beam and Broadcast
18. The Poulsen Arc Generator. By C. F. Elwell. Ernest Benn,
Ltd., London, 1923.
19. U.S. Federal Trade Commission's Report on the Radio Industry,
December 1st, 1923. Published at 40 cents by Government
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Postmaster-General, with regard to the Establishment of a
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25. Report of the Imperial Wireless Telegraphy Committee
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INDEX
ACOUSTIC tuning, 63
Adams, Prof. W. Grylls, 18
Aerial, 19
, aperiodic direction-finding, 60
, counterpoise or earth screen, 36,
43
, directional, 29, 34
, multiply-tuned, 35
Aid-to-navigation, 71, 72, 73
Aircraft, identification of, 72
, direction-finding gear for, 60
Air-jet relay, 64, 65
Aleicanderson, E. F. W., 35, 58
, beam radio, 93, 95
, multiply-tuned aerial, 35
Allen, H. W., circular to Marconi
shareholders, 76
Alternator, radio-frequency, 56
American Marconi Co., 38, 39, 97
Amplification, radio-frequency, 45, 60,
155 et seq.
Amplifier, triode, 37, 38, 45, 60, 148
, invention of, 37, 148
, Lichen's, 45
, Schloeinilch's, 60, 155
Antipodean -stations, 67, 68
Aperiodic direction-finding aerial, 60
Arc, Duddell's, 30, 177
, Elwell's work on, 75
, Federal Company's work, 75
, Poulsen's, 31, 32, 180
, Rome station, 75
stations of the world, 77
, Thomson's, 23, 175
Arco, Graf Georg von, 87, 168
Armstrong, E. II., 46, 48, 49, 55, 61, 83,
85, 86, 160 et scq.
Arnold, H. de F., 58, 81, 82
Artom, A., 42
Atlantic, ether congestion in N., 63
Atmospherics, 61
Audio-frequency electro-static field, 69
Audio-frequency tuning, 63
Auclion, 40, 50, 51, 52, 53, 83
Australian Inventions Encouragement
Board, 98
Autodyne or Self-heterodyne, 83, 84,
167, 170, 172
BALANCING-OUT DUPLKX, 45
Balloon aerial, Edison's, 19, 21
, Marconi's, 26, 122, 123
" B " battery, 37, 41, 44
Beam, 64, 68
as aid-to-navigation, 64. 73
, Crookes* forecast, 22, 94
, definition of, 94
method, advantages of, 88, 91
, patents relating thereto, 95, 102
et aeq.
, story of, 88
Beat reception, 33
Beat, supersonic, 61
Bellini-Tosi, 42, 58
Bibliography, 187
Bichel, C. E., 95
189
Bjerknes, 27
Blochmann, G. F. B., 95
Bolitho, J. B., 65
Borkum Riff Light Vessel, 71
Branly, Prof. E., 20, 125, 130
Braun, F., 25
, beam radio, 95, 102
, coupled circuits, 29, 132
, heart-shaped polar diagram, 38
British Broadcasting Co., 81
British Post Office Telegraphs, 98
Brown, S. G., 29, 95
Broadcasting, 67, 78
, apparatus for reception, 79
, inauguration of, 98
, opportunities of, 70-78
, U.S. patents relating to trans-
mission, 81
, wave-lengths, 68
CAMPBELL, G. A., 58
Campbell-Swinton, A. A., 96
Canada, origin of broadcasting, 98
Canadian Marconi Co., 89
" Canaries," 83
Carrier- wave methods, 57
, suppression of, 58
Carson, J. R., 58
Cassel, E. F., 72
Carbon filament, 41, 147, 174
Carborundum, 17, 36
Cathode, oxide-coated, 32, 156, 158
et scq., 168
" C " battery or grid bias, 45, 60
nhisholm, C.' L., 43
Cinema, 78
Claims (U.S.) on triode as generator,
47
Coherer, 20, 24, 125, 130
Collins, A. F., 187
rolpitts, E. H., 82
Compass, wireless, 42
Cooper, W. R., on invention of
triode, 39
CountPT poise, 36, 43
Coupled-circuits in receiver, 29
in transmitter, 29
Craufurd, Q. C. A., 73
Crookes, Sir Wrn., on beam radio, 22
, on work of Hughes, 18, 22
Crystal detectors, 36, 37, 42, 79
DK FOREST, LEE, passim
De Forest's amplifier, 37, 38, 148
" B " battery, 37
detector (triode), 38 ct 9eq. 9 151
metal filament, 44
oscillation generator, 45 ct icq.
Detector, carborundum, 17
crystal, 36, 37, 42, 79
diode, 19, 32, 33, 37, 43
electrolytic, 36, 42
silicon, 36
triode, 38, 39
Dictaphone recorder, invention of, 43,
44
Diode, Edison's, 19, 143
190
Radio: Beam and Broadcast
Diode, Fleming's, 32, 33, 43, 144
r, Wehnelf s, 32
Directional aerial, Brown's, 29
, Marconi's, 34, 35, 36
Direction-finder, Bellini-Tosi's, 42, 58,
60
, Kolster's, 60
, Robinon', 60
Direction-finding, 59
, aperiodic aerial, 60
, sense effect, 42
Discharger, synchronous, 25
, quenched gap, 36
Distance finding, 71, 72
Distress call, 70
receiver, 70, 71
Dolbear, Prof. A. E., 19
Doughty-Wylie, L. O. f 73
Duddell, W. du B., 30, 31, 177, 180
Dunmore, F. W., 94, 189
Dunwoody, H. H. G., 17, 36
EARTH screen, 36, 43
Earthed antenna, 21, 24
Eccles, W. H., on freaks, 61, 62
, on Lodge's work, 28
Eckersley, T. L., on " directional "
aerial, 34
Eddington, Prof,, on existence of
ether, 67
Edison, T. A., 19, 21, 143
Electrolytic detector, 36, 42, 155
Elster and Geitcl, 33
Elwell, C. F., 75
, on " The Poulsen Arc Genera-
tor," 188
Engel, F. H., 94, 189
" Equivalents " of patents in other
countries, 9
Espenschied, Lloyd, 58
Esperanto, 70
Ether, discussion on, 66, 67
FADING, 61, 66, 67
Fahie, J. J., 187
Farrington, 82
Federal Telegraph Company of San
Francisco, 75
Feed-back circuit, 46, 48, 50, 52, 85
Fessenden, R. A., 31, 96
, dictaphone reception, 43, 44
\ heterodyne, 33, 34, 56, 85
, signalling by wave change, 31, 32
, signalling by note change, 44
, voice modulation, 31
Filament, carbon, 41, 147, 174
f coated, 32, 158 et *eq.
, metal, 37, 44
, osmium. 174
, platinum, 44
, tantalum, 44, 174
, tungsten, 43, 174
Fleming, Prof. J. A., 17, 19, 41
- t book on thermionic valve, 188
, invention of diode, 32, 33, 43, 44
, an the etEev, 66
Fleming, Prof. J. A., on the directional
aerial of Marconi, 34, 35
, on Lodge's syntonic system, 27,
28
, on the Poulsen arc, 77
, on developments of diode, 40,
Fog, navigation in, 73
Foresio, B. G., 57, 95
Four-circuit or four-sevens patent of
Marconi, 30, 134
Franklin, C. S., beam and short-wave
experiments and patents, 89, 91, 93,
95, 110, 112-5
, on short-wave jamming, 72
, regenerative receiver, 45, 84, 86,
158 et seq.
Freaks, 61, 62, 67
GEITEL, ELSTER and, 33
Generator, arc, 9, 23, 31, 32, 75 et *tq .,
175 et seq.
, alternator, 56
, triode, 56, 164, 170
Gibraltar, report of beam test with, 90
Goldschmidt Alternator, acquisition
of, by Marconi Co., 76
Grid, introduction of, 37 et teq. 9 152
bias, 45, 60
condenser, 41, 152, 154
leak, 41, 60
Grove, W., 18
Guided-wave methods, 56, 57, 64
Guided-waves, Elihu Thomson oa,
66 fn.
HALE and LYLE, audio-frequency
electro-static field, 69
Hall Relay, 64, 65
Hanson, E. C., 73
Hartley, R. V. L., 58, 61, 90
Hazeltine, Prof. L. A., 61
Hibberd, A. S., inventor of Hummer,
86
Heaviside Layer, 66
Heinicke and Jasper, 73, 95
Heising, R. A., 82
Henrv, Prof. Joseph, 18
Hertz, R. A., 20, 56, 89, 104, 112, 125, 126
Heterodyne, 33, 34, 56, 83, 84, 85, 172
Hettinger, J., conducting beam, 84
Hovland, A. N., 73, 95
Howe, Prof. G. W. 0., on invention
of triode, 40
, on Marconi directional aerial,
35, 36
, on Lodge's nyntonie system, 96
Hughes, Prof. D. E., 18, 86
Hummer telephone, 86
Hutin, M., 57
Huygens, Christian, 17, 18
ILO, 70
Imperial Wireless Chain. 34
Inductive systems, Craufurd, 75
, Dolbear, 19
, Doughty- WylU, 71
Index
191
Inductive systems, Edison, 19
, Hanson, 73
, Preece, 96
, resuscitation of, 73
Interference method of reception, 33,
56
JAMMING (interference), 72
Jasper, M., 95
KELVIN Lecture, Elihu Thomson's
1924, 66
Kelway, C. F., 71
Kinraide, T. B., quenched gap, 36 fn.
Kite aerials, Dolbear's, 19
, Marconi's, 26, 122, 123
Kolster, F. A., 60
LADD, H. W., beam radio, 73, 95
41 L " inverted aerial, 19, 21, 34, 35
Langmuir, I., 46, 48, 60
Larsen, Prof., hummer, 86
Leblanc, Maurice, wired-wireless, 57
Levy, L., 61
Lieben, R. von, 45
Lightship, Borkum Riff, 71 fn.
, E. Goodwin, 96
" Line time," economizing, 44, 63
Lingua franca, need of a, 70
Lodge, Sir O., 20, 24, 39
, American patents, 97
, first coupled receiver, 28, 29,
130, 131
, loud speaker, 28, 29
, removal of spark gap from aerial
circuit, 28, 128
, syntonic system, 26, 27, 28, 124
, use of coherer without tapper,
20, 130
Logwood, C. V., 50, 82
Loud-speaker, 28, 29, 69
Lowenstein, F., 60, 82
Lyle and Hale, audio-frequency
electro-static field, 69
MAGNETIC Detector, Rutherford's, 24
, Marconi's, 31, 42
Magnetic variation, 42
Marconi Co., 19, 76, 88, 97
Marconi, Senator Guglielmo, passim,
76 77, 88, 89, 97
beam radio, 88 et seq. t 109, 118,
120
directional aerial, 34, 35, 36
Duplex, 45
magnetic detector, 31
use of short-waves. 72, 88 *t mq.
Marconi Year Book, 40, 84
Maskelyne, J. N., early triangular
aerial, 43
Mathes, R. C., 60
Maxwell, James Clerk, 18, 20
Meissner, A., 45, 46, 48, 61, 84, 87, 168
Miller, De forest v., 54
Mirage, radio equivalent, 62
Modulation, 31, 61
Monopoly, effect of, 06
Morecroft, Prof. J. H., en Arm-
strong's invention, 83
, on De Forest's invention, 40, 41
Moulton, Lord, 28
Muirhead, Alexander, 43
Munroe and Munroe, 89
Murray, Erskine, 57, 188
NAVIGATION, aids-to-, 72, 73
Neutrodyne method of reception, 61
Newspapers, effect of broadcasting
on, 80
Nichols, Dr. H. W., 58
Nobel Prize Winners
Branly, E., 22
Braun, F., 29
Marconi, G., 29, 76
Wien, Max, 38
OBERBECK, 27
Osmium filament, 174
Oxide-coated filament, 32, 156, 158 *
seq., 168
PARABOLIC reflectors, 88, 92, 93, 94.
102 et seq., 105 et seq., 109 st scq., 110
et stq., 116, 118 et seq.
Patents relating to
air-jet relay, 64
aperiodic direction- finding aerial, 80
arc, 30, 35, 75, 77, 175-86
audio-frequency electro-static field,
69
" B " battery, 32, 41
beam radio, 73, 95, 102-23
broadcast transmitters, U.S., 81, 88
carrier-wave suppression, 58
" C " battery, 45, 60
dictaphone recording, 43
diode, 19, 32, 143-7
direction-finding, 42, 60
distance-finding, 72, 73
earth-screen, 36, 43
grid bias, 45, 60
grid leak, 41 X 60
minded-wave systems, 57
heterodyne, 33, 61, 83, 84
inductive systems, 73
Lodge's American invention!, 97
navigation in fog, 72, 73
11 Neutrodyne, 1 ' 61
quenched gap, 36
radio-frequency amplification, 45,
60, 155
reflex circuit, 60, 155
regeneration, 45 et seq. 9 83, 84, 86,
160, 167, 168
synchronous discharger, 25
triode, 37, 38
triode radio-frequency generator, 45
et seq., 87
wave- filters, 58
Patent office practice, 8
Patent specifications, permission to
reproduce, 9, 101
, how to procure and price, 101
Ptrptfeual motion, patent* oa, 8
192
Radio: veam ana &roaacasi
Pickard, O. W., 56
Platinum filament. 44
Poldhu, 76, 93
Popoff, A. E., 24, 132
Poulsen, V. (Arc), 31, 32, 75, 76, 77, 180
Preece, Sir William, at Hughes's
demonstration. 18
, on Marconi Company, 97
, wireless system, 96
Punch cartoon, 4
Pupin, Prof. M. I., 39, 57
QUENCHED gap, 36
RADIO Corporation of America, form-
ation of, 97
, sale of triodes in 1923, 41
Radio-frequency amplification, 45, 60
Radiography (X-Ray), 25, 74
Reactive or regenerative circuit, 45-
55, 83, 84, 85
Reflectors. See Parabolic Reflectors
Reflex circuit, 60, 155 ct seq.
Regeneration, 83
, super, 84-5
Re-issue, term of, 26 fn.
Reisz, E., 45
Relay, proportional, 45
, air-jet, 64, 65
Rice, C. W., 61
Righi, Senator A., works and death
of, 62
, use of short waves, 89
Roberts- Austin, Sir W., at Hughes'
demonstration, 18
Robinson, J., air-craft direction-find*
ing, 60
Rome Station, 75
Rb'ntgen, 25
Round, H. J., autodvne, 84, 167, 169
, direction -finding work, 42, 58
Ruhmkorff Coil, 18, 19, 20, 25
Rutherford, Sir E., 24, 96
SAWYER, F. L., 72
Schieasler, J., 72
Schloemilch, W., 60, 155
Screen, Earth-, 36, 43
Secrecy, 88, 91, 92
Sense quality in direction-finding, 42
Shaughnessy, E. H., on multiply-
tuned aerial, 35
Ship radiotelejrraph. 70
Short wave potentialities, 72, 83 ft seq.
Short waves, 72, 73
Side-band suppression, 58
Siemens and Company, 61
Silicon detector, 36
Spark, quenched, 36
Spark transmitters on shipboard,
passing of, 70
Spider-web coil, 7
Squier, Gen. G. 0., 56, 57
Stanley, R., 187
Stchensnovitch, A., 72
Stokes, Sir Geo., 18
Stone, J. S., 43, 53, 57, 58, 96
.Strauss, S., 45
Super-heterodyne circuit, 61, 172
Super-regenerative circuit, 84
Supersonic frequency, 61
Swift, Dean, paraphrased, 64
Swinton, A. A. Campbell, 96
Synchronous discharger, 25, 138 et tcq.
Syntonic System, Lodge's, 26 et *e0.,
124
, Marconi's, 30, 134
TAPPER, Lodge's, 125-6
, Marconi's, 118
, Popoff's, 24
, shown by < Lodge to be non-
essential, 126
Tantalum filament, 44, 174
Tesla, N., generation of high-fre-
quency currents^23, 138 et seq.
, synchronous aischarger, 25, 138
et seq.
Thomson, Prof. Elihu, 39
, arc, 23, 175
, on theory of transmission, 66
Threlfall, Prof. R., on beam radio, 23
Tone transmission, 63
Tosi, Alessandro, 42
Triode amplifier, 37, 38
(Audion), invention of, 50
detector, 38, 39
generator of radio- frequency
oscillations, 45 et seq., 86, 87
Trowbridge, Augustus, tribute to
Righi, 62
Tungsten filament, 43, 174
Turner, L. B., 85
UNDULATORY theory of light, 17
United States Court of Appeal, Judg-
ment in, re Do Forest's Triode
Generator, 45-5
United Wireless Telegraph Company,
19, 97
VALVE. 8?e Diode
Van Etten, 49, 50, 51, 52
Van Orsdel, Judge, 46, 55
Volapuk, 70
Von Arco. 61, 87
Von Bronk, 60
Von Lieben, R., 32, 45, 60
Vortex ethereal rings, 74
WKHNELT, DR. A., 32
Wien, Max, 36
Williams, R. L., 79
Winds in ether, 66
White, 58
Wired -wireless, 57
Wright, G. M., 60
Wylic, L. O. Doughty-, 73
Xs. See Atmospherics
ZBNNECK, DR. J., 43, 187
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