This series is divided into the following five types of correspondence: general,
catalogued, early, laboratory and carbon correspondence. The catalogued
correspondence is alphabetical by correspondent. The remainder of the series is
chronological with the general containing schematic drawings, notes and
photographs. Diagrams and notes on the regenerative circuit and superheterodyne
can be found along with correspondence with Armstrong's sisters, Ethel and Edith,
as well as his mother, Emily, and Charles Underhill, H.J. Round, C.V. Logwood and
Irving Langmuir. The first box within this series contains the contents of a
binder entitled "Instructions for Filing." These materials appear to indicate the
manner in which Armstrong originally titled and filed various materials within his
office and laboratory.
These records are organized chronologically. Many are standard publications
written by E.H. Armstrong, some are annotated. There are drafts with annotations
which are typically addresses or speeches. Also included are newspaper articles,
statements and testimony.
Armstrong maintained clipping files on a variety of topics directly relating to
his work. These materials appear to be organized as Armstrong left them. With the
exception of the first box, the series is organized chronologically.
This series is comprised of a large set of files which appears to have been
Armstrong's filing system, which was expanded upon at a later date to include
litigation, the Armstrong Memorial Research Foundation Files, and others. This
series is organized alphabetically by both name and subject.
Throughout the series there are folders which are filed by individual name. The
majority are engineering publications, filed by author. Others contain legal
statements, testimony, correspondence and memoranda.
There are also large sets of litigation files, which contain material relating to
specific cases, generally filed by defendant. These files contain testimony,
transcripts, abstracts, notes, disclosures, technical reports and papers, license
agreements, articles, press releases, correspondence, legal memoranda, instruction
manuals, exhibits and patent file wrappers. Large amounts of Armstrong's and
relevant others original work including correspondence, diagrams, notes, testing
data, photographs, notebooks, logbooks, and patent disclosures used in exhibits
can be found under litigation files as well. The following organizations can be
found amongst litigation; Admiral Corp., American Telephone & Telegraph,
Co., Arvin Industries, Avco Corp., Bendix Radio and Aviation Corp,. De Forest
Radio and Telegraph Co., DuMont Laboratories, Emerson Radio, FADA Radio and
Electric Co., Gilfillan Bros., Hoffman Radio Corp., Fred M. Link, Motorola, Inc.,
Packard-Bell Co., Philco Corp., Radio and Television, Inc., Radio Corp. of America
and the National Broadcasting Corp., the Radio Craftsman, Inc., Sentinel Radio,
Sylvania Electric Products, Inc. and Wells-Gardner and Co. The litigation files
found within this series should be researched in conjunction with series five as
the two overlap.
This series encompasses materials given to Columbia University by a variety of
legal firms who had represented Armstrong and his wife, Marion, in litigation or
estate matters. The bulk of the records came from Cravath, Swaine and Moore, Darby
and Darby, Brumbaugh, Graves, Donohue and Raymond, and Pennie and Edmunds. These
materials relate directly to the administration of the Edwin H. Armstrong estate,
but many of Armstrong's original writings, disclosures, schematic drawings and
notes can be found within this series, most prominently within the litigation
files. Financial records for Armstrong's laboratories at Columbia University and
at Alpine, New Jersey are included here as well.
This series contains photographic media, arranged alphabetically. They are
separated into two different types of materials; photographs with the negatives,
followed by lantern slides. The series spans the course of Armstrong's life
including childhood, military service in WWI, and his work in the Marcellus
Hartley Laboratory at Columbia University. Images of the apparatus used in the
development of regenerative circuit, the superheterodyne circuit and FM radio are
also included. The FM-radio materials include the first tests of FM at the Empire
State Building, Westhampton Beach, New York and Haddonfield, New Jersey,
construction and operation of the first FM tower at Alpine, NJ, and the Yankee
Network. Lantern slides that are duplicated in the photographs or negative are
marked as "duplicate."
Edwin Howard Armstrong was born on December 18, 1890, in the
Chelsea District of Manhattan. He was the first child of John and Emily (Smith)
Armstrong. John worked as Vice President of the American branch of Oxford Press, while
Emily, a graduate of Hunter College, taught in the New York City public schools. Prior
to moving out of Manhattan, Edwin gained two younger sisters, Ethel and Edith. In 1902,
the Armstrong family moved north, to 1032 Warburton Avenue, in Yonkers, New York.
In 1905, Armstrong entered high school. He already sought to emulate Marconi, the
Italian inventor responsible for a system of wireless telegraphy. He began to tinker
with the telegraph with companions in his neighborhood who were also taken with the
invention. Many of these childhood companions would become lasting friends for the
balance of Howard’s life. Thomas Styles lived down the block in Yonkers; Randy Runyon
was located about a mile away, and William Russell was in the adjacent town of
Hastings-on-Hudson. Howard’s uncle, Frank Smith, introduced him to Charles R. Underhill,
an engineer and inventor for the American Telegraph Company. He furnished Armstrong with
experimental apparatus, and more importantly, a constant mentor. Howard would join
Underhill frequently after school for years, where they would discuss wireless
On June 24, 1909, Armstrong graduated from high school. The following September, he
entered Columbia University’s Department of Electrical Engineering. Armstrong was
constantly in the laboratory, conducting endless experiments. Some professors thought
the young student needed discipline, he did not follow maintain records of his
experiments. But several instructors defended Armstrong, fostering his need for freedom
to investigate. Howard distrusted mathematics as the essential proof of phenomena of the
physical world and refused to accept the findings of experts. He continued his
experiments both at the Columbia lab and in his attic at home. He was determined to find
a method that would strengthen the wireless signal.
While in his junior year, Armstrong came under the influence of Professor Michael I.
Pupin. Pupin was one of the founders of the Columbia University Department of Electrical
Engineering, and head of the Marcellus Hartley Research Laboratory. Pupin believed in
rigorous scientific experiments, understanding that theory cannot replace results. A
successful inventor himself, he soon took notice of Armstrong.
In 1912, Armstrong joined the Radio Club of America, which his close friends from
Yonkers had all joined. The Club, originally called the Junior Wireless Club Ltd., had
been organized in 1909, with Reginald A. Fessenden as the advisor. Fessenden had
invented and patented the heterodyne principle in 1902. It was an amateur club that
would eventually have a large impact on the development of radio and more specifically,
The Regenerative Circuit
In 1906, Lee de Forest created the “audion”, an early vacuum tube, by adding a wire grid
to the Edison-Fleming diode. Subsequently, in 1912, he accidentally connected the output
circuit of one audion to its own input circuit and obtained a loud howling sound, which
he later identified as regeneration. Instead of attempting to understand the hissing or
howling sound, he tried to abolish it.
When Armstrong began experimenting with the audion, he took numerous measurements in
order to ascertain how this tube functioned, eventually devising a circuit that would
operate as a powerful amplifier of incoming radio waves. By the winter of 1912, he had
discovered that if part of the plates output circuit was fed back to the grid in a
controlled manner, the incoming signals were remarkably strengthened. In addition, he
discovered that when feedback was increased sufficiently the circuit could be used as a
transmitter by generating high frequency oscillations, a required element for radio
communications. He mentioned his idea to instructors at Columbia University, who advised
him to contact William Davis, a patent attorney who had secured patents for many of
them. Lacking the necessary funds to file, his uncle advised him to prepare a sketch and
have it notarized. He did just that, providing him with a record date of January 31,
Armstrong’s regenerative circuit led to a nearly twenty year legal battle over patent
rights. While the controversy is best known to have been between Armstrong and de
Forest, there were actually two other individuals who claimed rights to this invention--
Irving Langmuir and Alexander Meissner.
In October 1913, Armstrong, along with another inventor, Irving Langmuir of General
Electric, filed patent applications disclosing the principle of radio-frequency
regeneration and claimed the arrangement of tuned radio frequency circuits, which is
characteristic of the invention. Armstrong’s patent was issued on October 6, 1914. This
patent disclosed the circuit arrangement in its non-oscillating stage, that of an
improved receiver of wireless signals. By now his patent attorney, William Davis,
recommended he incorporate the transmitting ability into the same patent. Armstrong
refused and the regenerative circuits oscillating capacity was disclosed in a separate
patent application, filed December 18, 1913.
A German inventor, Alexander Meissner, filed a United States Patent application on the
regenerative circuit on March 16, 1914. Four days later, Lee de Forest filed an
application for his “ultra-audion”. In De Forest’s original claims, he considered his
device a detector, not an amplifier (transmitter).
In November 1913, de Forest delivered a paper to the Institute of Radio Engineers (IRE)
on the subject of “The audion, detector and amplifier”. He gave an explanation of the
action of the audion with regard to circuit change. He made no mention of feedback and
this presentation served to reinforce the fact that he did not understand the audion
qualities or how it functioned. It was not until after Armstrong’s paper “Some Recent
Developments in the audion Receiver”, was delivered to the IRE in New York on March 3,
1915, and published in September, that de Forest changed his patent disclosure. De
Forest filed for patent with oscillating features in September 1915 and was later issued
a second patent, claiming a date of invention prior to March 1913, disclosing specifics
This was the patent that the United States Supreme Court would, on May 21, 1934, decide
to sustain in favor of de Forest. The decision of the Supreme Court was the thirteenth
pronouncement by a judicial or administrative tribunal with regard to the question of
priority between Armstrong and de Forest. These two men fought each other in the courts
both as individuals and through the corporations (Westinghouse Electric and American
Telephone and Telegraph, respectively) that had purchased rights to their patents. Prior
to the Supreme Court decision, six of the tribunals decided in favor of Armstrong and
six had decided in de Forest’s favor. The scientific community, especially the
engineering community, believed that in favoring de Forest's claim the Court had made a
large mistake, one based on the justices' lack of technical training and understanding.
In 1934, the IRE held a convention in Philadelphia. Armstrong indicated that he would
like to return the Medal of Honor he had received in 1917 for his discovery of
regeneration. He believed that since the United States Supreme Court had decided against
him, it was his duty to return what may have been awarded to him in error. The IRE
President, along with the Board of Directors unanimously agreed that Armstrong should be
reaffirmed as the recipient of the 1917 Medal of Honor, so instead of allowing Armstrong
to return his Medal, they restated the award.
When the United States entered World War I, Armstrong enlisted in the Signal Corps. In
1917 he was posted in France and placed in charge of the Radio Group of the Research
Section of the Division of Research and Inspection. This Division had been created in
order to examine any existing equipment manufactured by the Europeans for the American
Expeditionary Forces. The Major set off to France but en route he was delayed in England
due to heavy fog. While there, he ventured to London, stopping by the Marconi offices
where he met Henry J. Round.
Round was an engineer with Marconi who, at the time, was in charge of the Admiralty’s
wireless direction-finding stations. It was here that Armstrong was introduced to
Round’s short-wave equipment. Round had created these amplifiers by designing his own
vacuum tube (V24). These tubes were not of military use to the French or the Americans,
but they captured Armstrong’s attention and he concluded that this was a problem that
required further research.
Armstrong had studied heterodyne circuitry for quite a while and understood it well.
This meeting with Round pushed him further and he continued to examine the problem of
receiving weak high frequency signals. In 1918, Harry W. Houck, a sergeant in the United
States Army, was sent to Paris to assist Armstrong with his work. They worked together
to solve the problem of detecting high frequency waves and converting them to a lower
frequency range audible to the human ear. After observing a bombing raid in Paris,
Armstrong was inspired to improve the methods of locating aircraft. He used the
heterodyne principle to bring short-wave frequencies down to the range of his long-wave
amplifier. He worked out the necessary experiments needed to prove his forthcoming
invention, writing down the proposed method in June 1918 with Major Buckley signing off
Following his proposed methodology to Major Buckley, Armstrong needed assistance to
stage these experiments and create the necessary apparatus. With war work taking
precedence and his fellow officers tied up in other pressing projects, his work was
delayed. The first model was not ready until November. Armstrong first applied for
patent in France in December 1918 and for United States patent in February 1919.
In early 1919, Armstrong was raised to permanent rank of Major. He also received the
Chevalier de la Legion d'honneur from General Ferrie, Head of the French Military
Communications Division. When Armstrong returned from the war he presented his paper, "A
New System of Short Wave Amplification," to the Institute of Radio Engineers in December
of 1919, delineating his new receiver.
In 1920, Westinghouse purchased Armstrong’s regeneration and superheterodyne patents.
Also, around this time, American Telephone and Telegraph (AT & T) purchased
Lucien Levy’s patent for essentially the same invention. Levy’s patent referred to a
different use of the technology than did Armstrong’s, resulting in the United States
Patent Office not catching the conflict. Someone eventually noticed this apparent
conflict and priority needed to be resolved.
The Court of Appeals in the District of Columbia ruled in Levy’s favor and his patent
was issued on November 5, 1929, with a priority date of August 4, 1917 (he had filed 6
months prior to Armstrong). While Levy, by law, is considered the inventor of the
superheterodyne method, Armstrong is recognized as bringing about its commercialization
through the single tuning knob superheterodyne receiver.
The Super-regenerative Circuit
In 1922, Armstrong devised the super-regenerative circuit, a detector with much higher
sensitivity. In June, RCA and Armstrong made a deal; Armstrong received two hundred
thousand dollars in cash and sixty thousand shares of stock for his super-regeneration
invention. It was around this time that he met Marion MacInnis who worked as David
Sarnoff's secretary at RCA. In December of 1923, they married at her parents' home in
Merrimac. Radio broadcasting was now becoming very popular, what had begun as one
station in 1920 had grown to over 500 stations.
Wide-band Frequency Modulation System
For many years Armstrong and Pupin had been investigating how to eliminate the problem
of natural and man-made noise that plagued AM radio, with no success. At the time, the
method accepted of reducing noise was in narrowing the band of frequencies used to
transmit radio waves. The conventional theories taught that a narrower band of
frequencies utilized for broadcasting would allow less noise into the signal. In 1931,
Armstrong took the opposite approach and pursued wideband frequency modulation as a
remedy for noise.
On December 26, 1933 about 18 months after he began experimenting with wide-band FM,
Armstrong had secured patent number 1,914,069, titled Radio Signaling. In addition, he
secured three other patents; patent number 1,941,068 titled Radio Signaling, patent
number 1,941,066 titled Radio Signaling System, and the last issued in 1933, patent
number 1,941,067 titled Radio Broadcasting and Receiving.
Armstrong first approached RCA, offering them first option on his new invention. In the
spring of 1934 he set up his system in the Empire State building and for the next few
years RCA engineers, alongside Armstrong, tested FM. During the summer of 1934, tests
were conducted between the Empire State building and Westhampton Beach, Long Island. The
results were excellent, but proof was needed from a site located at a further distance.
The receiver was moved to the Haddonfield, New Jersey home of Harry Sadenwater, an
engineer at RCA. This experiment established that even with longer range, the signals
could be heard loud and clear.
Alpine, New Jersey
Still, RCA would not buy Armstrong’s frequency modulation system. So he attempted to
obtain permission from the Federal Communications Commission to build a high powered FM
station in 1935. First, the FCC denied his request, but he was finally able to secure an
experimental license after he hired an attorney to help him. Armstrong began
constructing his station in Alpine, New Jersey. In 1936, he poured a large sum of money
into it, selling some of his RCA stock to do so. There were no FM broadcast stations in
existence (with the exception of W2AG, his longtime childhood friend Randy Runyon’s
station, operating out of Yonkers, New York), hence all the apparatus would have to be
built from scratch. Armstrong oversaw the project from top to bottom.
Station W2XMN went on the air with a regular operating schedule in July 1939.
Immediately following, various other FM stations went on the air, all under experimental
licenses. These stations now wanted to go commercial and thus were applying to the FCC
to do so. Finally, at the end of 1939, the FCC began to study the commercial
possibilities of FM broadcast.
The Federal Communications Commission
In January 1941, the FCC authorized the commercial development of FM. When the United
States entered World War II, there were under one hundred commercial FM stations
authorized, but applications were rolling in. The FCC froze the civilian electronics
industry; only FM stations already broadcasting could continue. It became clear to the
FCC that they would need to establish standards for the post-war electronics industry. A
new allocation scheme for the use of frequencies above 30 MHz would become
In November 1942, at a joint meeting of the IRE and the electrical engineering
department of the Radio Manufacturers Association (RMA), FCC Commissioner James L. Fly
encouraged the industry to establish an organization that could provide the FCC with
engineering advice for the development of frequency allocation and system standards.
Fly's proposal resulted in the establishment of the Radio Technical Planning Board
(RTPB), set up in September 1943.
The RTPB was divided into 13 panels, each responsible for recommendations pertaining to
various electronic industry standards. FM broadcasting, including frequency allocations
and standards was the responsibility of Panel 5.
Various hearings were held where a multitude of experts in the field testified.
Generally accepted was that the majority of experts, both on the applicable panel, or
consulted, agreed that the FM frequency allocations should remain where they were in the
40-50 MHz vicinity. A few experts felt that there was evidence of atmospheric
disturbances that could cause interference in the frequency band that was currently
being used. The FCC then began to investigate a possible move for FM frequency
allocation, to the 100 MHz vicinity.
In June 1945, after multiple hearings and evidence from an engineer employed by the FCC,
Kenneth Norton, the FCC ordered FM stations to broadcast in the 88-106 MHz band. This
decision rendered the old FM system, in use since January 1941, obsolete. Engineers,
manufacturers and broadcasters had to begin again from scratch.
A few years prior to the FCC decision to shift frequency allocations, RCA had begun work
on FM. Negotiations between Armstrong and RCA for use of his FM System patents had never
come to fruition. An engineer employed with RCA, Stuart Seeley, had invented the
"radio-detector" for RCA, who claimed that Armstrong's patents were not used. In fact,
the Seeley invention did appropriate two of Armstrong's inventions, the limiter and
detector. RCA was licensing the rights to what it claimed was its FM invention, to other
manufacturers, some of which were Emerson, Motorola and Philco. With the shift in
frequency band, RCA was back on a level playing field.
Radar and FM Multiplexing
Armstrong set out to prove the FCC wrong so he leased a cottage on Westhampton Beach,
Long Island and sent John Bose to reside there. Signals were sent from Alpine and the
documentation of FM propagation was extensive. He produced incontrovertible evidence
that FM could work well in a lower frequency band. At the same time, he also conducted
experiments to prove that FM transmission was not limited to short distances. He
transmitted from Alpine, high powered FM signals that bounced off the ionosphere and was
received by a mobile receiver in Alabama. The pentagon and Bell Labs recognized the
importance of this discovery and continued development with Massachusetts Institute of
Technology (MIT), REL and Bell Labs. The result was early warning radar.
At the start of the war, Armstrong offered the United States government use of his FM
patents royalty free. Unfortunately, his bills for the Columbia Lab and Alpine station
were building so his attorney, Al McCormack, encouraged Armstrong to accept government
contract work. At the time, Armstrong was investigating long-range radar. As a result of
incoming work, Armstrong hired another assistant, Robert Hull, a recent graduate of
Columbia University, to join his investigations of continuous wave radar.
He had adapted frequency modulation to radar to extend the range of detection far beyond
conventional methods. His research provided the basis for long-range radar in use today.
Armstrong had still been working on radar and in January 1946, his radar system was
tested at the US Army Signal Corps lab in Fort Evans, located in Belmar, New Jersey.
Army engineers bounced the first radio signal off the moon and back to earth. His radar
system proved that FM waves could penetrate the ionosphere.
In March 1953, a new invention is announced, FM multiplexing. Armstrong had developed
the invention with John Bose, which facilitates a single FM station to transmit
simultaneously, two or three different signals over the same FM wave. This invention
made stereo broadcasting possible.
Wide-band Frequency Modulation System--Patent Infringement
On July 22, 1948, Armstrong's attorney, McCormack, filed suit against RCA and NBC in
Wilmington, Delaware. The main charge being infringement of his five basic FM patents.
In addition, the suit also charged that RCA deliberately set out to retard the
production of FM. McCormack was assisted by Dana Raymond (who had worked at Cravath,
Swaine & Moore), and the attorney who had filed all of Armstrong's patents since
super-regeneration, Albert Nolte, assisted as well.
In March 1953, a new invention was announced, FM multiplexing. Armstrong had developed
the invention jointly with John Bose, which facilitates a single FM station to transmit
simultaneously, two or three different signals over the same FM wave. This invention
made stereo broadcast possible.
The litigation continued and Armstrong began to become not only financially drained, but
physically drained as well. At the end of the fifth year of litigation, 1954, Armstrong
took his own life.
His widow Marion would continue the battle against RCA and twenty other companies who
had infringed Armstrong's FM patents. It would not be until 1968, when the final pending
suit and ruling was made in Armstrong's favor. All twenty-one companies had either
settled or were ruled infringers by the courts.
Honors and Awards:
Degree of Doctor of Science Columbia University, 1929
L'Universite Laval, 1948
Medal of Honor, Institute of Radio Engineers, 1917
Chevalier de la Legion d'Honneur, 1919
Armstrong Medal, established by The Radio Club of America, 1935
Egleston Medal, Columbia University, 1939
Holley Medal, American Society of Mechanical Engineers, 1940
National Modern Pioneer Award, National Association of Manufacturers, on the 150th
Anniversary of the American Patent System, 1940
Medal of Class on 1989--School of Mines, Columbia University, 1941
Franklin Medal, the Franklin Institute, 1941
John Scott Medal, Awarded by the Board of Directors of City Trusts, City of
Edison Medal, American Institute of Electrical Engineers, 1942
Medal for Merit (United States) with Presidential Citation, 1947
Radio Club Armstrong Medal along with Ernest V. Amy, George E. Burghard, Milton
Cronkhite, Paul F. Godley, John F. Grinan, and Walter P. Inman, for the first shortwave
transoceanic signals (1BCG), 1950
Washington Award, Western Society of Engineers, 1951
Lion Award, Columbia University Alumni Club of New Jersey, 1953
Honorary Membership, Institute of Radio Engineers, Australia
Honorary Membership, Franklin Institute
Honorary Membership, American Institute of Electrical Engineers