Edwin Howard Armstrong
Edwin Howard Armstrong (December 18, 1890 – January 31, 1954) was an
American electrical engineer and inventor, best known for developing
FM (frequency modulation) radio and the superheterodyne receiver
system. He held 42 patents and received numerous awards, including the
first Medal of Honor awarded by the
Institute of Radio Engineers (now
IEEE), the French Legion of Honor, the 1941
Franklin Medal and the
1942 Edison Medal. He was inducted into the National Inventors Hall of
Fame and included in the International Telecommunication Union's
roster of great inventors.
1 Early life
2 Early work
2.1 Regenerative circuit
2.3 Super-regeneration circuit
3 Wide-band FM radio
6 Personal life
9 See also
12 Further reading
13 External links
Armstrong's boyhood home, 1032 Warburton Avenue, overlooking the
Hudson River in Yonkers, New York, c. 1975. It was demolished in
November 1982 due to fire damage.
Armstrong was born in the Chelsea district of New York City, the
oldest of John and Emily (Smith) Armstrong's three children. His
father began working at a young age at the American branch of the
Oxford University Press, which published bibles and standard classical
works, eventually advancing to the position of vice president. His
parents first met at the North Presbyterian Church, located at 31st
Street and Ninth Avenue. His mother's family had strong ties to
Chelsea, and an active role in church functions. When the church
moved north, the Smiths and Armstrongs followed, and in 1895 the
Armstrong family moved from their brownstone row house at 347 West
29th Street to a similar house at 26 West 97th Street in the Upper
West Side. The family was comfortably middle class.
At the age of eight, Armstrong contracted
Sydenham's chorea (then
known as St. Vitus' Dance), an infrequent but serious neurological
disorder precipitated by rheumatic fever. For the rest of his life,
Armstrong was afflicted with a physical tic exacerbated by excitement
or stress. Due to this illness, he withdrew from public school and was
home-tutored for two years. To improve his health, the Armstrong
family moved to a house overlooking the Hudson River, at 1032
Warburton Avenue in Yonkers. The Smith family subsequently moved next
door. Armstrong's tic and the time missed from school led him to
become socially withdrawn.
From an early age, Armstrong showed an interest in electrical and
mechanical devices, particularly trains. He loved heights and
constructed a makeshift backyard antenna tower that included a bosun's
chair for hoisting himself up and down its length, to the concern of
neighbors. Much of his early research was conducted in the attic of
his parent's house.
In 1909, Armstrong enrolled at
Columbia University in New York City,
where he became a member of the Epsilon Chapter of the Theta Xi
engineering fraternity, and studied under Professor Michael Pupin at
the Hartley Laboratories, a separate research unit at Columbia.
Another of his instructors, Professor John H. Morecroft, later
remembered Armstrong as being intensely focused on the topics that
interested him, but somewhat indifferent to the rest of his
studies. He was known for challenging conventional wisdom and being
quick to question the opinions of both professors and peers. In one
case, he recounted how he tricked an instructor he disliked into
receiving a severe electrical shock. He also stressed the
practical over the theoretical, stating that progress was more likely
the product of experimentation and work based on physical reasoning
than on mathematical calculation and formulae (known as part of
Armstrong graduated from Columbia in 1913, earning an electrical
During World War I, Armstrong served in the Signal Corps as a captain
and later a major.
In 1934, he filled the vacancy left by John H. Morecroft's death,
receiving an appointment as a Professor of Electrical Engineering at
Columbia, a position he held the remainder of his life.
Following college graduation, he received a $600 one-year appointment
as a laboratory assistant at Columbia, after which he nominally worked
as a research assistant, for a salary of $1 a year, under Professor
Pupin. Unlike most engineers, Armstrong never became a corporate
employee. He set up a self-financed independent research and
development laboratory at Columbia, and owned his patents outright.
Armstrong's "feed back" circuit drawing, from Radio Broadcast vol. 1
no. 1 1922.
Armstrong began working on his first major invention while still an
undergraduate at Columbia. In late 1906,
Lee de Forest
Lee de Forest had invented
the three-element (triode) "grid Audion" vacuum-tube. How vacuum tubes
worked was not understood at the time. De Forest's initial Audions did
not have a high vacuum and developed a blue glow at modest plate
voltages; De Forest improved the vacuum for Federal Telegraph. By
1912, how vacuum tubes worked was understood, and the advantages of
high vacuum tubes were appreciated.
While growing up Armstrong had experimented with the early,
temperamental, "gassy" Audions. Spurred by the later discoveries, he
developed a keen interest in gaining a detailed scientific
understanding of how vacuum-tubes worked. In conjunction with
Professor Morecroft he used an oscillograph to conduct comprehensive
studies. His breakthrough discovery was determining that employing
positive feedback (also known as "regeneration") produced
amplification hundreds of times greater than previously attained, with
the amplified signals now strong enough so that receivers could use
loudspeakers instead of headphones. Further investigation revealed
that when the feedback was increased beyond a certain level a
vacuum-tube would go into oscillation, thus could also be used as a
continuous-wave radio transmitter.
Beginning in 1913 Armstrong prepared a series of comprehensive
demonstrations and papers that carefully documented his research,
and in late 1913 applied for patent protection covering the
regenerative circuit. On October 6, 1914, U.S. patent 1,113,149 was
issued for his discovery. Although
Lee de Forest
Lee de Forest initially
discounted Armstrong's findings, beginning in 1915 de Forest filed a
series of competing patent applications that largely copied
Armstrong's claims, now stating that he had discovered regeneration
first, based on August 6, 1912 notebook entry, while working for the
Federal Telegraph company, prior to the January 31, 1913 date
recognized for Armstrong. The result was an interference hearing at
the patent office to determine priority. De Forest was not the only
other inventor involved — the four competing claimants included
Armstrong, de Forest, General Electric's Langmuir, and Alexander
Meissner, who was a German national, which led to his application
being seized by the
Office of Alien Property Custodian
Office of Alien Property Custodian during World
Following the end of
World War I
World War I Armstrong enlisted representation by
the law firm of Pennie, Davis, Martin and Edmonds. In order to finance
his legal expenses he began issuing non-transferable licenses for use
of the regenerative patents to a select group of small radio equipment
firms, and by November 1920 seventeen companies had been licensed.
These licensees paid 5% royalties on their sales which were restricted
to only "amateurs and experimenters". Meanwhile, Armstrong reviewed
his options for selling the commercial rights to his work. Although
the obvious candidate was the
Radio Corporation of America
Radio Corporation of America (RCA), on
October 5, 1920 the Westinghouse Electric & Manufacturing Company
took out an option for $335,000 for the commercial rights for both the
regenerative and superheterodyne patents, with an additional $200,000
to be paid if Armstrong prevailed in the regenerative patent dispute.
Westinghouse exercised this option on November 4, 1920.
Legal proceedings related to the regeneration patent became separated
into two groups of court cases. An initial court action was triggered
in 1919 when Armstrong sued de Forest's company in district court,
alleging infringement of patent 1,113,149. This court ruled in
Armstrong's favor on May 17, 1921. But a second line of court cases,
the result of the patent office interference hearing, would have a
different outcome. The interference board had also sided with
Armstrong, but he was unwilling to settle with de Forest for less than
what he considered full compensation. Thus pressured, de Forest
decided to continue his legal defense, and appealed the interference
board decision to the District of Columbia district court. On May 8,
1924, that court ruled that it was de Forest who should be considered
regeneration's inventor. Armstrong (along with much of the engineering
community) was shocked by this course of events, and his side appealed
this unexpected decision. But although the legal proceeding twice went
before the U.S. Supreme Court, in 1928 and 1934, he was unsuccessful
in overturning the decision.
In response to the second Supreme Court decision upholding de Forest
as the inventor of regeneration, Armstrong attempted to return his
1917 IRE Medal of Honor, which had been awarded "in recognition of his
work and publications dealing with the action of the oscillating and
non-oscillating audion". However, the organization's board refused to
let him, and issued a statement that it "strongly affirms the original
Armstrong in his Signal Corps uniform during World War I
The United States entered into
World War I
World War I in April 1917, and later
that year Armstrong was commissioned as a Captain in the U.S. Army
Signal Corps, and assigned to a laboratory in Paris, France to help
develop radio communication for the Allied war effort. He returned to
the United States in the fall of 1919, after being promoted to the
rank of Major. (During both world wars, Armstrong gave the U.S.
military free use of his patents.)
During this period Armstrong's most significant accomplishment was the
development of a "supersonic heterodyne" — soon shortened to
"superheterodyne" — radio receiver circuit. This circuit made
radio receivers more sensitive and selective and is still extensively
used today. The key feature of the superheterodyne approach is the
mixing of the incoming radio signal with a locally generated,
different frequency signal within a radio set. This circuit is
typically referred to as the mixer. The end result is a fixed,
unchanging intermediate frequency, or I.F. signal which is more easily
amplified and detected by subsequent circuit stages that follow the
mixer. In 1919, Armstrong filed an application for a U.S. patent of
the superheterodyne circuit which was issued the next year. This
patent was subsequently sold to Westinghouse. The patent would be
challenged, however, triggering yet another patent office interference
hearing. Armstrong ultimately lost this patent battle; although
the outcome was less controversial than that involving the
The challenger was
Lucien Lévy of France who had also worked
developing Allied radio communication during World War I. He had been
awarded French patents in 1917 and 1918 that covered some of the same
basic ideas used in Armstrong's superheterodyne receiver. AT&T,
which was interested in radio development at this time, primarily for
point-to-point extensions of its wired telephone exchanges, purchased
the U.S. rights to Lévy's patent and contested Armstrong's grant. The
subsequent court reviews continued until 1928, when the District of
Columbia Court of Appeals disallowed all nine claims of Armstrong's
patent, assigning priority for seven of the claims to Lévy, and one
Ernst Alexanderson of
General Electric and Burton W. Kendall
of Bell Laboratories.
Although most early radio receivers used regeneration Armstrong
approached RCA's David Sarnoff, whom he had known since giving a
demonstration of his regeneration receiver in 1913, about the
corporation offering superheterodynes as a superior offering to the
general public. (The ongoing patent dispute was not a hindrance,
because extensive cross-licensing agreements signed in 1920 and 1921
between RCA, Westinghouse and AT&T meant that Armstrong could
freely use the Lévy patent.)
Superheterodyne sets were initially
thought to be prohibitively complicated and expensive as the initial
designs required multiple tuning knobs and used nine vacuum-tubes.
However, in conjunction with RCA engineers, Armstrong developed a
simpler, less costly design. RCA introduced its superheterodyne
Radiola sets in the U.S. market in early 1924, and they were an
immediate success, dramatically increasing the corporation's profits.
These sets were considered so valuable that RCA would not license the
superheterodyne to other U.S. manufacturing companies until 1930.
Armstrong explaining the superregenerative circuit, New York, 1922
The regeneration legal battle had one serendipitous outcome for
Armstrong. While he was preparing apparatus to counteract a claim made
by a patent attorney, he "accidentally ran into the phenomenon of
super-regeneration", where, by rapidly "quenching" the vacuum-tube
oscillations, he was able to achieve even greater levels of
amplification. A year later, in 1922, Armstrong sold his
super-regeneration patent to RCA for $200,000 plus 60,000 shares of
corporation stock, which was later increased to 80,000 shares in
payment for consulting services. This made Armstrong RCA's largest
shareholder, and he noted that "The sale of that invention was to net
me more than the sale of the regenerative circuit and the
superheterodyne combined". RCA envisioned selling a line of
super-regenerative receivers until superheterodyne sets could be
perfected for general sales, but it turned out the circuit was not
selective enough to make it practical for broadcast receivers.
Wide-band FM radio
"Static" interference — extraneous noises caused by sources such as
thunderstorms and electrical equipment — bedeviled early radio
communication using amplitude modulation (AM) and perplexed numerous
inventors attempting to eliminate it. Many ideas for static
elimination were investigated, with little success. In the mid-1920s,
Armstrong began researching whether he could come up with a solution.
He initially, and unsuccessfully, attempted to resolve the problem by
modifying the characteristics of existing AM transmissions.
One approach considered as a potential solution had been the use of
frequency modulation (FM) transmissions, where, in order to encode
audio, instead of varying (technically known as "modulating") the
amplitude (strength) of a radio signal, as was done for AM
transmissions, the frequency was varied. However, in 1922 John Renshaw
Carson of AT&T, inventor of
Single-sideband modulation (SSB), had
Proceedings of the IRE paper which included a detailed
mathematical analysis which showed that FM transmissions did not
provide any improvement over AM. Although the Carson bandwidth
rule for FM is still important today, this review turned out to be
incomplete, because it analyzed only what is now known as
In early 1928 Armstrong began researching the capabilities of
frequency modulation. Although there were few others involved in FM
research at this time, he did have knowledge of a project being
conducted by RCA engineers, who were investigating whether FM
shortwave transmissions were less susceptible to fading than AM. In
1931 these engineers constructed a successful FM shortwave link
transmitting the Schmeling-Stribling fight broadcast from California
to Hawaii, and noted at the time that the signals seemed to be less
affected by static, but the project made little further progress.
Working in secret in the basement laboratory of Columbia's Philosophy
Hall, Armstrong slowly developed what eventually resulted in wide-band
FM, in the process discovering significant advantages over the earlier
"narrow-band" FM transmissions. He was granted five U.S. patents
covering the basic features of new system on December 26, 1933.
Initially, the primary claim was that his FM system was effective at
filtering out the noise produced in receivers by vacuum tubes.
Armstrong had a standing agreement to give RCA the right of first
refusal to his patents. In 1934 he made a presentation of his new
system to RCA president Sarnoff. Sarnoff was somewhat taken aback by
its complexity, as he had hoped it would be possible to eliminate
static merely by adding a simple device to existing receivers. From
May 1934 until October 1935 Armstrong conducted field tests of his FM
technology from an RCA laboratory located on the 85th floor of the
Empire State Building
Empire State Building in New York City. An antenna attached to the
building's spire transmitted signals for distances up to 80 miles
(130 km). These tests helped demonstrate FM's
static-reduction and high-fidelity capabilities. However RCA, which
was heavily invested in perfecting television broadcasting, chose not
to invest in FM, and instructed Armstrong to remove his equipment.
Denied the marketing and financial clout that RCA would have brought,
Armstrong decided to finance his own development and form ties with
smaller members of the radio industry, including Zenith and General
Electric, to promote his invention. Armstrong thought that FM had the
potential to replace AM stations within 5 years, which he promoted as
a boost for the radio manufacturing industry, then suffering from the
effects of the Great Depression, since making existing AM radio
transmitters and receivers obsolete would necessitate that stations
buy replacement transmitters and listeners purchase FM-capable
receivers. In 1936 he published a landmark paper in the Proceedings of
the IRE that documented the superior capabilities of using wide-band
FM. (This paper would be reprinted in the August 1984 issue of
Proceedings of the IEEE.) A year later, a paper by Murray G.
Crosby (inventor of
Crosby system for FM Stereo) in the same
journal provided further analysis of the wide-band FM
characteristics, and introduced the concept of "threshold",
demonstrating that there is a superior signal to noise ratio when the
signal is stronger than a certain level.
In June 1936, Armstrong gave a formal presentation of his new system
at the U.S.
Federal Communications Commission
Federal Communications Commission (FCC) headquarters in
Washington, D.C. For comparison, he played a jazz record using a
conventional AM radio, then switched to an FM transmission. A United
Press correspondent was present, and recounted in a wire service
report that: "if the audience of 500 engineers had shut their eyes
they would have believed the jazz band was in the same room. There
were no extraneous sounds." Moreover, "Several engineers said after
the demonstration that they consider Dr. Armstrong's invention one of
the most important radio developments since the first earphone crystal
sets were introduced." Armstrong was quoted as saying he could
"visualize a time not far distant when the use of ultra-high frequency
wave bands will play the leading role in all broadcasting", although
the article noted that "A switchover to the ultra-high frequency
system would mean the junking of present broadcasting equipment and
present receivers in homes, eventually causing the expenditure of
billions of dollars."
In the late 1930s, as technical advances made it possible to transmit
on higher frequencies, the FCC investigated options for increasing the
number of broadcasting stations, in addition to ideas for better audio
quality, known as "high-fidelity". In 1937 it introduced what became
known as the Apex band, consisting of 75 broadcasting frequencies from
41.02 to 43.98 MHz. As on the standard broadcast band these were
AM stations, but with higher quality audio — in one example, a
frequency response from 20 Hz to 17,000 Hz
+/- 1 dB — because station separations were 40 kHz
instead of the 10 kHz spacings used on the original AM band.
Armstrong worked to convince the FCC that a band of FM broadcasting
stations would be a superior approach. That year he financed the
construction of the first
FM radio station, W2XMN (later KE2XCC) at
Alpine, New Jersey. FCC engineers had believed that transmissions
using high frequencies would travel little farther than line-of-sight
distances, limited by the horizon. However, when operating with 40
kilowatts on 42.8 MHz, the station could be clearly heard 100
miles (160 km) away, matching the daytime coverage of a full
power 50-kilowatt AM station.
FCC studies comparing the Apex station transmissions with Armstrong's
FM system concluded that his approach was superior. In early 1940, the
FCC held hearings on whether to establish a commercial FM service.
Following this review, the FCC announced the establishment of an FM
band effective January 1, 1941, consisting of forty 200 kHz-wide
channels on a band from 42-50 MHz, with the first five channels
reserved for educational stations. Existing Apex stations were
notified that they would not be allowed to operate after January 1,
1941 unless they converted to FM.
Although there was interest in the new FM band by station owners,
construction restrictions that went into place during World War II
limited the growth of the new service. Following the end of World War
II, the FCC moved to standardize its frequency allocations. One area
of concern was the effects of tropospheric and Sporadic E propagation,
which at times reflected station signals over great distances, causing
mutual interference. A particularly controversial proposal,
spearheaded by RCA, was that the FM band needed to be shifted to
higher frequencies in order to avoid this potential problem. This
reassignment was fiercely opposed as unneeded by Armstrong, but in the
end he lost. The FCC made its decision final on June 27, 1945.  It
allocated one hundred FM channels from 88–108 MHz, and assigned
the former FM band to 'non government fixed and mobile' (42–44 MHz),
and television channel 1 (44–50 MHz), curiously now sidestepping the
interference concerns. A period of allowing existing FM stations
to broadcast on both low and high bands ended at midnight on January
8, 1949, at which time any low band transmitters had to be shut down,
officially making obsolete 395,000 receivers that had already been
purchased by the public for the original band. Although converters
allowing low band FM sets to receive high band were manufactured, they
ultimately proved to be complicated to install, and often as (or more)
expensive than buying a new high band set outright.
Armstrong felt the FM band reassignment had been inspired primarily by
a desire to cause a disruption that would limit FM's ability to
challenge the existing radio industry, including RCA's AM radio
properties that included the NBC radio network, plus the other major
networks including CBS, ABC and Mutual. The change was also thought to
have been favored by AT&T, as the elimination of FM relaying
stations would require radio stations to lease wired links from that
company. Particularly galling was the fact that the FCC then assigned
TV channel 1 to the 44-50 MHz segment of the old FM band, despite
the fact that in 1941 the FCC had adopted FM sound as part of the NTSC
television standard, moreover, the video portions of the standard were
even more susceptible to interference than the audio. Channel 1
eventually had to be deleted as well, with all TV broadcasts licensed
at frequencies 54 MHz or higher, and in the United States these
frequencies are no longer widely used for emergency first responders,
those services having moved mostly to UHF.
Although the FM band shift was an economic setback, there was still
reason for optimism, and a book published in 1946 by Charles A.
Siepmann heralded FM stations as "Radio's Second Chance". In late
1945, Armstrong contracted with John Orr Young, founding member of the
public relations firm Young & Rubicam, to conduct a national
campaign promoting FM broadcasting, especially by educational
institutions. Article placements promoting both Armstrong personally
and FM were made with general circulation publications including The
Nation, Fortune, the New York Times, Atlantic Monthly, and The
Saturday Evening Post.
In 1940, RCA offered Armstrong $1,000,000 for a non-exclusive,
royalty-free license to use his FM patents. But he refused this offer,
primarily because he felt this would be unfair to the other licensed
companies, which had to pay 2% royalties on their sales. Over time
this impasse with RCA would come to dominate Armstrong's life. RCA
countered by conducting its own FM research, eventually developing
what it claimed was a non-infringing FM system. The corporation also
encouraged other companies to stop paying royalties to Armstrong.
Outraged by this turn of events, in 1948 Armstrong filed suit against
RCA and the National Broadcasting Company, accusing them of patent
infringement and that they had "deliberately set out to oppose and
impair the value" of his invention, for which he requested treble
damages. Although he was confident that this suit would be successful
and result in a major monetary award, the protracted legal maneuvering
that followed eventually began to impair his finances, especially
after his primary patents expired in late 1950.
Bitter and overtaxed by years of litigation and mounting financial
problems, Armstrong lashed out at his wife one day with a fireplace
poker, striking her on the arm. She left their apartment to stay
with her sister, Marjorie Tuttle, in Granby, Connecticut.
Sometime during the night of January 31–February 1, 1954, with his
wife in Connecticut and three servants having left for the day,
Armstrong removed the air conditioner from a window in his twelve-room
apartment on the thirteenth-floor of River House in Manhattan, New
York City, and jumped to his death. His body—fully clothed, with
a hat, overcoat and gloves—was found in the morning on a third-floor
balcony by a River House employee. The
New York Times
New York Times described the
contents of his two-page suicide note to his wife: "he was heartbroken
at being unable to see her once again, and expressing deep regret at
having hurt her, the dearest thing in his life." The note concluded,
"God keep you and Lord have mercy on my Soul." David Sarnoff
disclaimed any responsibility, telling
Carl Dreher directly that "I
did not kill Armstrong." After his death, a friend of Armstrong
estimated that 90 percent of his time was spent on litigation against
RCA. U.S. Senator
Joseph McCarthy (R-Wisconsin) reported that
Armstrong had recently met with one of his investigators, and had been
"mortally afraid" that secret radar discoveries by him and other
scientists "were being fed to the Communists as fast as they could be
developed". Armstrong was buried in Locust Grove Cemetery,
Following her husband's death, Marion Armstrong took charge of
pursuing his estate's legal cases. In late December 1954, it was
announced that through arbitration an out-of-court settlement of
"approximately $1,000,000" had been made with RCA. Dana Raymond of
Cravath, Swaine & Moore in New York served as counsel in that
litigation. Marion Armstrong was able to formally establish Armstrong
as the inventor of FM following protracted court proceedings over five
of his basic FM patents, with a series of successful suits, which
lasted until 1967, against other companies that were found guilty of
It wasn't until the 1960s that FM stations in the United States
started to challenge the popularity of the AM band, helped by the
development of FM stereo by General Electric. Armstrong's FM system
was also used for communications between
NASA and the Apollo program
astronauts. (He is of no known relation to Apollo astronaut Neil
Armstrong has been called "the most prolific and influential inventor
in radio history". The superheterodyne process is still
extensively used by radio equipment. Eighty years after its invention,
FM technology has started to be supplemented, and in some cases
replaced, by more efficient digital technologies. The introduction of
digital television eliminated the FM audio channel that had been used
by analog television,
HD Radio has added digital sub-channels to FM
band stations, and, in Europe and Pacific Asia, Digital Audio
Broadcasting bands have been created that will, in some cases,
eliminate existing FM stations altogether. However, FM
broadcasting is still used internationally, and remains the dominant
system employed for audio broadcasting services.
Armstrong and his new wife
Esther Marion MacInnis
Esther Marion MacInnis in Palm Beach in
1923. The radio is a portable superheterodyne that Armstrong built as
a present for her.
In 1923, combining his love for high places with courtship rituals,
Armstrong climbed the WJZ (now WABC) antenna located atop a
twenty-story building in New York City, where he reportedly did a
handstand, and when a witness asked him what motivated him to "do
these damnfool things", Armstrong replied "I do it because the spirit
moves me." Armstrong had arranged to have photographs taken, which
he had delivered to David Sarnoff's secretary, Marion MacInnis.
Armstrong and MacInnis married later that year. Armstrong bought a
Hispano-Suiza motor car before the wedding, which he kept until his
death, and which he drove to Palm Beach, Florida for their honeymoon.
A publicity photograph was made of him presenting Marion with the
world's first portable superheterodyne radio as a wedding gift.
He was an avid tennis player until an injury in 1940, and drank an Old
Fashioned with dinner. Politically, he was described by one of his
associates as "a revolutionist only in technology — in politics he
was one of the most conservative of men."
In 1955, Marion Armstrong founded the Armstrong Memorial Research
Foundation, and participated in its work until her death in 1979 at
the age of 81. She was survived by two nephews and a niece.
Philosophy Hall at Columbia University, which housed the basement
laboratory where Armstrong developed FM radio.
In 1917, Armstrong was the first recipient of the IRE's (now IEEE)
Medal of Honor.
For his wartime work on radio, the French government gave him the
Legion of Honor
Legion of Honor in 1919. He was awarded the 1941 Franklin Medal,
and in 1942 received the AIEEs
Edison Medal "for distinguished
contributions to the art of electric communication, notably the
regenerative circuit, the superheterodyne, and frequency
ITU added him to its roster of great inventors of
electricity in 1955.
He later received two honorary doctorates, from Columbia in 1929, and
Muhlenberg College in 1941.
In 1980, he was inducted into the National Inventors Hall of Fame, and
appeared on a U.S. postage stamp in 1983. The Consumer Electronics
Hall of Fame inducted him in 2000, "in recognition of his
contributions and pioneering spirit that have laid the foundation for
Columbia University established the Edwin
Professorship in the School of Engineering and
Applied Science in his memory.
Philosophy Hall, the Columbia building where Armstrong developed FM,
was declared a National Historic Landmark. Armstrong's boyhood home in
Yonkers, New York
Yonkers, New York was recognized by the National Historic Landmark
program and the National Register of Historic Places, although this
was withdrawn when the house was demolished.
Armstrong Hall at Columbia was named in his honor. The hall, located
at the northeast corner of Broadway and 112th Street, was originally
an apartment house but was converted to research space after being
purchased by the university. It is currently home to the Goddard
Institute for Space Studies, a research institute dedicated to
atmospheric and climate science that is jointly operated by Columbia
and the National Aeronautics and Space Administration. A storefront in
a corner of the building houses Tom's Restaurant, a longtime
neighborhood fixture that inspired Susanne Vega's song "Tom's Diner"
and was used for establishing shots for the fictional "Monk's diner"
in the "Seinfeld" television series.
A second Armstrong Hall, also named for the inventor, is located at
the United States Army Communications and Electronics Life Cycle
Management Command (CECOM-LCMC) Headquarters at Aberdeen Proving
E. H. Armstrong patents:
U.S. Patent 2,630,497 : "Frequency Modulation Multiplex System"
U.S. Patent 2,602,885 : "Radio Signaling"
U.S. Patent 2,540,643 : "Frequency-Modulated Carrier Signal
U.S. Patent 2,323,698 : "Frequency Modulation Signaling System"
U.S. Patent 2,318,137 : "Means for Receiving Radio Signals"
U.S. Patent 2,315,308 : "Method and Means for Transmitting
Frequency Modulated Signals"
U.S. Patent 2,295,323 : "Current Limiting Device"
U.S. Patent 2,290,159 : "Frequency Modulation System"
U.S. Patent 2,276,008 : "Radio Rebroadcasting System"
U.S. Patent 2,275,486 : "Means and Method for Relaying Frequency
U.S. Patent 2,264,608 : "Means and Method for Relaying Frequency
U.S. Patent 2,215,284 : "Frequency Modulation Signaling System"
U.S. Patent 2,203,712 : "Radio Transmitting System"
U.S. Patent 2,169,212 : "Radio Transmitting System"
U.S. Patent 2,130,172 : "Radio Transmitting System"
U.S. Patent 2,122,401 : "Frequency Changing System"
U.S. Patent 2,116,502 : "Radio Receiving System"
U.S. Patent 2,116,501 : "Radio Receiving System"
U.S. Patent 2,104,012 : "Multplex Radio Signaling System"
U.S. Patent 2,104,011 : "Radio Signaling System"
U.S. Patent 2,098,698 : "Radio Transmitting System"
U.S. Patent 2,085,940 : "Phase Control System"
U.S. Patent 2,082,935 : "Radio Signaling System"
U.S. Patent 2,063,074 : "Radio Transmitting System"
U.S. Patent 2,024,138 : "Radio Signaling System"
U.S. Patent 1,941,447 : "Radio Telephone Signaling"
U.S. Patent 1,941,069 : "Radiosignaling"
U.S. Patent 1,941,068 : "Radiosignaling"
U.S. Patent 1,941,067 : "Radio Broadcasting and Receiving System"
U.S. Patent 1,941,066 : "Radio Signaling System"
U.S. Patent 1,716,573 : "Wave Signaling System"
U.S. Patent 1,675,323 : "Wave Signaling System"
U.S. Patent 1,611,848 : "Wireless Receiving System for Continuous
U.S. Patent 1,545,724 : "Wave Signaling System"
U.S. Patent 1,541,780 : "Wave Signaling System"
U.S. Patent 1,539,822 : "Wave Signaling System"
U.S. Patent 1,539,821 : "Wave Signaling System"
U.S. Patent 1,539,820 : "Wave Signaling System"
U.S. Patent 1,424,065 : "Signaling System"
U.S. Patent 1,416,061 : "Radioreceiving System Having High
U.S. Patent 1,415,845 : "Selectively Opposing Impedance to
Received Electrical Oscillations"
U.S. Patent 1,388,441 : "Multiple Antenna for Electrical Wave
U.S. Patent 1,342,885 : "Method of Receiving High Frequency
U.S. Patent 1,336,378 : "Antenna with Distributed Positive
U.S. Patent 1,334,165 : "Electric Wave Transmission" (Note:
Co-patentee with Mihajlo Pupin)
U.S. Patent 1,113,149 : "Wireless Receiving System"
U.S. Patent and Tradmark Office Database Search
Armstrong oscillator – basic circuit for reception of AM radio
Armstrong Tower – tall lattice tower built and used by Edwin
Armstrong in 1938
Armstrong Phase Modulator
Awards named after E. H. Armstrong
^ a b c Tsividis, Yannis (Spring 2002). "Edwin Armstrong: Pioneer of
the Airwaves". Columbia Magazine. Living Legacies: Great Moments and
Leading Figures in the History of Columbia University. New York:
Columbia University. Retrieved September 18, 2017.
^ a b c d e "Armstrong, FM Inventor, Dies In Leap From East Side
Suite". The New York Times. February 2, 1954. p. 1.
ISSN 0362-4331. Maj. Edwin H. Armstrong, whose inventions
provided much of the basis for modern broadcasting, was found dead
yesterday morning on a third-floor balcony of River House, 435 East
Fifty-second Street. The 63-year-old electrical engineer had plunged
from a window of his luxurious thirteenth-floor apartment, apparently
late Sunday evening or during the night.
^ Lessing 1956, p. 22
^ Lessing 1956, p. 23
^ Lessing 1956, p. 26
^ Lessing 1956, p. 24
^ a b c d Lessing 1956, p. 27
^ a b Wu 2010, p. 126
^ "What Everyone Should Know About Radio History: Part II" by Prof. J.
H. Morecroft, Radio Broadcast, August, 1922, pages 294-302.
^ Empire of the Air by Tom Lewis, 1991, pages 60-61.
^ a b c d Who Was Who in American History - the Military. Chicago:
Marquis Who's Who. 1975. p. 15. ISBN 0837932017.
^ "Major Armstrong Goes to Columbia". The New York Times. August 7,
1934. p. 20. ISSN 0362-4331. The appointment of Major Edwin
Howard Armstrong as Professor of Electrical Engineering at Columbia
University yesterday by Dr. Nicholas Murray Butler, president of the
^ The Legacies of Edwin Howard Armstrong, "E. H. Armstrong" by Thomas
Sykes, 1990, page 22.
^ DeForest Radio Co. v.
General Electric Co., 283 U.S. 664 (May 25,
1931). Fleming and Lilenfeld had advocated high vacuum. "Of critical
importance in the present controversy is the effect of the presence of
gas within the tube." "In consequence, the low vacuum tube is more
sensitive both as a detector and as an amplifier than a tube of high
vacuum." "August 20, 1912, the earliest date claimed for Langmuir, was
rejected rightly, we think, by the District Court, which held that
Langmuir was anticipated by Arnold in November, 1912. But before the
earlier date, De Forest sought and obtained a high vacuum in the
audions used as amplifiers, and observed that when the vacuum was too
low the blue glow effect occurred at from 15 to 20 volts. In order to
secure higher voltages from the audions used as amplifiers and to
procure the requisite high vacuum, he had some of the bulbs
re-exhausted while superheated. By August 1912, the Telegraph Company
used De Forest amplifying audions at 54 volts, and by November, they
were used by another at 67 1/2 volts. This was possible only because
the tubes had thus been exhausted of gas, which would otherwise have
ionized with blue glow at from 20 to 30 volts."
^ "Operating Features of the Audion" by E. H. Armstrong, Electrical
World, December 12, 1914, pages 1149-1152.
^ Armstrong, E. H. (August 2, 1917). "Operating Features of the
Audion". Annals of the New York Academy of Sciences. 27 (1):
^ Lewis (1991), pages 77, 87.
^ Ibid., page 192.
^ Invention and Innovation in the Radio Industry by W. Rupert
Maclaurin, 1949, page 122.
^ Radio Manufacturers of the 1920's: Volume 3 by Alan Douglas, 1991,
page 3. Organized broadcasting barely existed when the initial
"amateur and experimental" licenses where granted. By 1922 a
"broadcast boom" in the U.S. saw a tremendous growth in the sale of
radio receivers to the general public. Westinghouse tried to claim
that these sales infringed on its rights, as they should be considered
"commercial", but the courts did not agree. Thus, the companies that
held these "amateur and experimental" license rights found they now
had a very valuable asset.
^ Douglas (1991), pages 193-198, 203.
^ MacLaurin (1949), page 106. "Westinghouse then made an even more
important move by purchasing [on May 22, 1920] for $335,000 the
Armstrong patents on the regenerative and superheterodyne circuits."
^ a b "Who Invented the Superheterodyne?" by Alan Douglas, originally
published in The Legacies of
Edwin Howard Armstrong
Edwin Howard Armstrong from the
"Proceedings of the Radio Club of America", Nov. 1990, Vol.64 no.3,
pages 123-142. Page 139: "Lévy broadened his claims to purposely
create an interference, by copying Armstrong's claims exactly. The
Patent Office would then have to choose between the two inventors."
^ Lewis (1991), page 205. "...the case did not seem to affect
Armstrong emotionally in the same way the regeneration suit did...
Possibly he recognized the Frenchman did have some legitimate claim to
the invention... Armstrong respected Levy in a way that he could not
respect de Forest..."
^ The Continuous Wave: Technology and American Radio, 1900-1932 by
Hugh G. J. Aitken, 1985, page 467.
^ History of Radio to 1926 by Gleason L. Archer, 1938, page 297: "It
appears that Armstrong first exhibited the device to the astute
General Manager of RCA, David Sarnoff. Mr. Sarnoff had just concluded
arrangements that involved ordering several millions' dollars worth of
an improved type of radio... He was so impressed by the Armstrong
invention that he at once halted these negotiations..."
^ Maclaurin (1949). October 12, 1947 letter from Armstrong to the
author, page 122.
^ Carson, J. R. (February 1922), "Notes on the theory of modulation",
Proceedings of the Institute of Radio Engineers, 10 (1): 57–64,
^ Early FM Radio by Gary L. Frost, 2010, pages 72-73.
^ Raymond, Dana M. "Air War: Legal Battles Over FM Radio". Fathom.
Columbia University. Archived from the original on May 15, 2008.
^ Frost (2010), page 95.
^ Wu 2010, p. 125
^ Katzdorn, Mike. "Beginning of Armstrong's FM station W2XMN at
Alpine, NJ (1937)". Retrieved December 19, 2011.
^ Armstrong, E. H. (May 1936), "A method of reducing disturbances in
radio signaling by a system of frequency modulation", Proc. IRE, 24
(5): 689–740, doi:10.1109/jrproc.1936.227383, archived from the
original on January 2, 2008
^ Armstrong, E. H. (August 1984), "A method of reducing disturbances
in radio signaling by a system of frequency modulation", Proc. IEEE,
72 (8): 1042–1062, doi:10.1109/proc.1984.12971, archived from the
original on January 2, 2008
^ Crosby, M. G. (April 1937), "
Frequency modulation noise
characteristics", Proc. IRE, 25 (4): 472–514,
^ "New Radio Shown" (UP), Bellingham (Washington) Herald, June 17,
1936, page 2.
^ America's Apex Broadcasting Stations of the 1930's by John
^ "Armstrong, Edwin Howard". Current Biography. The H. W. Wilson
Company: 23–26. 1940.
^ a b AP (June 27, 1945). "Device to make FM Radios Work Under FCC
Ruling". The Miami News. 6-A. Retrieved 2017-08-14 – via
^ INS (June 27, 1945). "395,000 FM Radio Sets Must Be Replaced".
Journal Gazette. p. 6. Retrieved 2017-08-14 – via
^ "Pre-War FM Radio Sets to Become Obsolete Saturday". The Times.
January 6, 1949. p. 1. Retrieved 2017-08-14 – via
^ Radio's Second Chance by Charles A. Siepmann, 1946, pages 239-253.
^ "A Case study of Edwin Howard Armstrong's public relations campaign
for FM" (thesis) by Jessica Francis, December 14, 2012, pages 16, 19.
^ Lewis (1991), pages 247-278, 300-328.
^ Stashower, Daniel (2002), The Boy Genius and the Mogul: the untold
story of television, New York: Broadway Books, ISBN 0767907590,
His health began to suffer and his behavior grew erratic. On one
occasion he came to believe that someone had poisoned his food and
insisted on having his stomach pumped. On another, his wife fled the
house as Armstrong lashed out with a fireplace poker.
^ "Maj. Edwin Armstrong, Father of FM, Other Radio Inventions, Dead at
63", Broadcasting-Telecasting, February 8, 1954, pages 67-68.
^ Kaempffert, Waldemar (December 9, 1956). "Stubborn genus". The New
York Times. p. 297. Retrieved February 4, 2012. After he penned
the last sentence, "God keep you and the Lord have mercy on my soul,"
he put on his overcoat, hat and gloves and stepped out of a window
thirteen stories above the ground.
^ Dreher (1976), page 207.
^ "Major Armstrong Felt Reds Stole His Ideas—McCarthy",
Broadcasting-Telecasting, February 8, 1954, page 68.
^ Griffith, John (January 1, 2001). "Edwin Howard Armstrong". Find A
Grave. Retrieved December 20, 2011.
^ "Fm Suit Settlement Ends Six-Year Fight". Broadcasting-Telecasting.
January 10, 1955. p. 84. the fm patent suit brought against
RCA-NBC some years ago by the late Maj. Edwin H. Armstrong has been
settled for approximately $1 million.
^ Lewis (1991), page 358.
^ Campbell, Richard; Christopher R. Martin; Bettina Fabos (2011).
Media and Culture: An Introduction to Mass Communication, 8th Ed.
MacMillan. p. 124. ISBN 0312644655.
^ "Norway to Become First Country to Switch Off FM Radio in 2017" by
Scott Roxborough, Hollywood Reporter, April 20, 2015.
^ Dreher (1976), page 46.
^ Lewis (1991), page 160. Three of the photographs are included in the
pictorial section between pages 118-119.
^ Dreher (1976), page 208.
^ "Esther Armstrong, 81, the Wife Of
Inventor of FM Radio System". The
New York Times. August 10, 1979. p. A13. ISSN 0362-4331.
Esther Marion Armstrong, the wife of the late Maj. Edwin Howard
Armstrong, a leading American inventor, died Wednesday at the Exeter
(N.H.) Hospital, after a brief illness. She was 81 years old and lived
in Rye Beach, N.H.
^ "IEEE Medal of Honor". IEEE Global History Network. IEEE. June 27,
2011. Retrieved July 7, 2011.
^ "Edwin Howard Armstrong", Radio's 100 Men of Science by Orrin E.
Dunlap, 1944, page 250.
^ Sheire, James (July 1975). "National Register of Historic Places
Inventory/Nomination: Edwin H. Armstrong House". Archived from the
original on July 24, 2011. Retrieved January 25, 2008. (includes
^ "Withdrawn Designations:
Edwin H. Armstrong House
Edwin H. Armstrong House Designation".
National Historic Landmark
National Historic Landmark summary listing. National Park Service.
Retrieved September 18, 2017.
^ "U.S. Patent and Trademark Office Database Search: Edwin H.
Erickson, Don V. (1973), Armstrong's fight for FM broadcasting: one
man vs big business and bureaucracy, University of Alabama Press,
Frost, Gary L. (2010), Early FM Radio: Incremental Technology in
Twentieth-Century America. Baltimore: Johns Hopkins University Press,
2010. ISBN 0-8018-9440-9, ISBN 978-0-8018-9440-4.
Lessing, Lawrence (1956), Man of High Fidelity: Edwin Howard
Armstrong, a biography, Philadelphia: Lippincott
Lewis, Tom (1991), Empire of the air: the men who made radio, New
York: Edward Burlingame Books, ISBN 0-06-098119-9
Who Was Who in American History - the Military. Chicago: Marquis Who's
Who. 1975. ISBN 0837932017.
Wu, Tim (2010), The Master Switch, New York: Alfred A. Knopf,
Ira Brodsky. The History of Wireless: How Creative Minds Produced
Technology for the Masses. St. Louis: Telescope Books, 2008.
Ken Burns. Empire of the Air. Documentary that first aired on PBS in
Süsskind, Charles (1970). "Armstrong, Edwin Howard". Dictionary of
Scientific Biography. New York. pp. 287–288 Charles Scribner's
Sons. ISBN 0-684-10114-9.
Wikimedia Commons has media related to Edwin Howard Armstrong.
Wikiquote has quotations related to: Edwin Howard Armstrong
Works by or about
Edwin Howard Armstrong
Edwin Howard Armstrong at Internet Archive
Armstrong Memorial Research Foundation - The Armstrong Foundation
disseminates knowledge of Armstrong's research and achievements
Houck Collection - A collection of images and documents that belonged
to Armstrong's assistant, Harry W. Houck, which have been annotated by
Rare Book & Manuscript Library Collections - A collection of
images and documents at Columbia University
The Broadcast Archive - A brief biography by Donna Halper
Ammon, Richard T., "The Rolls Royce Of Reception : Super
Heterodynes - 1918 to 1930".
IEEE History Center's Edwin H. Armstrong : Excerpt from "The
Legacy of Edwin Howard Armstrong," by J. E. Brittain Proceedings of
the IEEE, vol. 79, no. 2, February 1991
Hong, Sungook, "A History of the Regeneration Circuit: From Invention
to Patent Litigation" University, Seoul, Korea (PDF)
Who Invented the Superhetrodyne? The history of the invention of the
superhetrodyne receiver and related patent disputes
Yannis Tsividis, "Edwin Armstrong: Pioneer of the Airwaves", 2002. A
profile on the web site of Columbia University, Armstrong's alma mater
IEEE Edison Medal
William D. Coolidge
William D. Coolidge (1927)
Frank B. Jewett
Frank B. Jewett (1928)
Charles F. Scott (1929)
Frank Conrad (1930)
Edwin W. Rice (1931)
Bancroft Gherardi (1932)
Arthur Edwin Kennelly (1933)
Willis R. Whitney (1934)
Lewis B. Stillwell (1935)
Alex Dow (1936)
Gano Dunn (1937)
Dugald C. Jackson (1938)
Philip Torchio (1939)
George Ashley Campbell (1940)
John B. Whitehead (1941)
Edwin H. Armstrong (1942)
Vannevar Bush (1943)
Ernst Alexanderson (1944)
Philip Sporn (1945)
Lee De Forest
Lee De Forest (1946)
Joseph Slepian (1947)
Morris E. Leeds
Morris E. Leeds (1948)
Karl B. McEachron (1949)
Otto B. Blackwell (1950)
IEEE Medal of Honor
Edwin H. Armstrong (1917)
Ernst Alexanderson (1919)
Guglielmo Marconi (1920)
Reginald Fessenden (1921)
Lee de Forest
Lee de Forest (1922)
John Stone Stone
John Stone Stone (1923)
Mihajlo Pupin (1924)
ISNI: 0000 0001 1438 9385