Rare Book & Manuscript Library

Edwin H. Armstrong papers, 1886-1982, bulk 1912-1954

Summary Information

At a Glance

Call No.: MS#0043
Bib ID 4078687 View CLIO record
Creator(s) Armstrong, Edwin H (Edwin Howard), 1890-1954
Title Edwin H. Armstrong papers, 1886-1982, bulk 1912-1954
Physical Description 295.7 linear feet (297 boxes, 2 flat folders, 30 phono discs, 10 tape reels)
Language(s) English .
Access You will need to make an appointment in advance to use this collection material in the Rare Book and Manuscript Library reading room. You can schedule an appointment once you've submitted your request through your Special Collections Research Account.

The following boxes are located off-site: 2-573. You will need to request this material from the Rare Book and Manuscript Library at least three business days in advance to use the collection in the Rare Book and Manuscript Library reading room.

This collection has no restrictions.



This collection is arranged in 6 series.



Professional and personal files including Armstrong's correspondence with professional associations, other engineers, and friends, his research notes, circuit diagrams, lectures, articles, legal papers, and other related materials. Of his many inventions and developments, the most important are: 1) the regenerative or feedback circuit, 1912, the first amplified radio reception, 2) the superheterodyne circuit, 1918, the basis of modern radio and radar, 3) superregeneration, 1922, a very simple, high-power receiver now used in emergency mobile service, and 4) frequency modulation - FM, 1933, static-free radio reception of high fidelity. More than half the files concern his many lawsuits, primarily with Radio Corporation of America, over infringement of the Armstrong patents. Litigation continued until 1967. Other files deal with his work in the Marcellus Hartley Research Laboratory at Columbia University, 1913-1935, and with the American Expeditionary Forces in France during World War I, his Air Force contracts for communications development, Army research during World War II, the Radio Club of America, the Institute of Radio Engineers, FM development at his radio station at Alpine, N.J., the use of FM in television, his involvement in Federal Communications Commission hearings and legislation, and his work with the Zenith Radio Corporation. Also, letters to H.J. Round

1990 ADDITION: Files from the firm of Cravath, Swaine& Moore. Files, dating from the late 1920s to the 1960s, pertaining to Professor Armstrong's litigation with Lee de Forest over the regeneration patents; his suit against RCA and other infringers of his FM patents; the original letters patent, among which are those for his FM system; and financial matters relating to the Armstrong laboratories, the FM station in Alpine, New Jersey, other real estate properties, and his estate

  • Series I: Correspondence, 1910-1975

    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.

  • Series II: Writings of EHA, 1913-1953

    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.

  • Series III: Clippings, 1912-1954

    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.

  • Series IV: Alphabetical Files, 1886-1980

    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.

  • Series V: Records of Cravath, Swaine and Moore and Other Legal Firms, 1901-1982

    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.

  • Series VI: Photographs, Negatives and Lantern Slides, 1886-1967

    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."

Using the Collection

Rare Book and Manuscript Library

Restrictions on Access

You will need to make an appointment in advance to use this collection material in the Rare Book and Manuscript Library reading room. You can schedule an appointment once you've submitted your request through your Special Collections Research Account.

The following boxes are located off-site: 2-573. You will need to request this material from the Rare Book and Manuscript Library at least three business days in advance to use the collection in the Rare Book and Manuscript Library reading room.

This collection has no restrictions.

Terms Governing Use and Reproduction

Single photocopies may be made for research purposes. Permission to publish material from the collection must be requested from the Curator of Manuscripts/University Archivist, Rare Book and Manuscript Library (RBML). The RBML approves permission to publish that which it physically owns; the responsibility to secure copyright permission rests with the patron.

Preferred Citation

Identification of specific item; Date (if known); Edwin H. Armstrong Papers; Box and Folder; Rare Book and Manuscript Library, Columbia University Library.

Selected Related Material-- at Columbia

James Laurence Fly Papers 1920-1977, Rare Book and Manuscript Library, Columbia University Libraries

Michael Idvorsky Pupin Papers 1800-1995, Rare Book and Manuscript Library, Columbia University Libraries

Archived Web Site of the Armstrong Memorial Research Foundation, 2013-present, Columbia University Libraries

George H. Clark Radioana Collection, c. 1880-1950, Archives Center, National Museum of American History, Smithsonian Institution, Washington, DC

Records of the Federal Communications Commission, National Archives, Washington, DC

Records of the National Institute of Standards and Technology, National Archives, Washington, DC

United States Army Communications Electronics Museum, Fort Monmouth, New Jersey

Armstrong Memorial Research Foundation Records. Columbia University Libraries.


No accruals are expected


The Armstrong Memorial Research Foundation,1977; Harold A. Wheeler, 1983; Pennie, Davis, Marvin & Edmonds, 1983; Keith E. Mullinger [Pennie, Davis, Marvin & Edmonds], 1984; Jerry Granat via the Armstrong Memorial Research Foundation, 1985; Cravath, Swaine and Moore, 1991; Columbia University Amateur Radio Club (W2AEE) via Henry Alvestad, 1992; Robin John Morecroft, 1995; Purchase, 1995; Dana Raymond [Brumbaugh, Graves, Donohoe & Raymond], 1997; Nancy Hull, 2007; Carlton Moseley, 2010; Steve McGrath, 2011.

Gift of the Armstrong Memorial Research Foundation, 1977.

Gift of Keith E. Mullinger, 1983.

Gift of Pennie & Edmonds, 1984.

Gift of Jerry Granat, via the Armstrong Memorial Research Foundation, 1985.

Gift of Cravath, Swaine& Moore, 1990.

Gift of the C.U. Amateur Radio Club (W2AEE) via Henry Alvestad, 1992.

About the Finding Aid / Processing Information

Columbia University Libraries, Rare Book and Manuscript Library

Sponsor Information

The processing of this collection was made possible through the generous support of the Armstrong Memorial Research Foundation, the IEEE Foundation, the IEEE Communications Society, the IEEE Circuits and Systems Society, the Alcatel-Lucent Foundation, Columbia University's Department of Electrical Engineering, and the Fu Foundation School of Engineering and Applied Science.

Processing Information

Processed by Henry Rowen 12/77; BRC 3/79; BRC 4/85; HR 3/86; AH 1991; HR 6/92

Cataloged Christina Hilton Fenn 03/24/1989.

Papers Processed AH 02/06/1991.

Laboratory notebook Processed HR 06/02/1992.

This collection was processed by Jennifer Comins; Carolyn Smith; Jennifer Howard, GS EE '11; Hilary Hanson, CC '11; Brian Mackus, GS '12; and Meredith Wisner, Pratt Institute, MLIS '11. Finding aid written by Jennifer Comins in October 2010.

Revision Description

2010-12-08 xml document instance created by Jennifer S. Comins

2019-05-20 EAD was imported spring 2019 as part of the ArchivesSpace Phase II migration.

Subject Headings

The subject headings listed below are found in this collection. Links below allow searches at Columbia University through the Archival Collections Portal and through CLIO, the catalog for Columbia University Libraries, as well as ArchiveGRID, a catalog that allows users to search the holdings of multiple research libraries and archives.

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Heading "CUL Archives:"
"CUL Collections:"
"Nat'l / Int'l Archives:"
Abstracts (summaries) Portal CLIO ArchiveGRID
Account books Portal CLIO ArchiveGRID
Agreements Portal CLIO ArchiveGRID
Annual reports Portal CLIO ArchiveGRID
Applications Portal CLIO ArchiveGRID
Articles Portal CLIO ArchiveGRID
Audiocassettes Portal CLIO ArchiveGRID
Audiotapes Portal CLIO ArchiveGRID
Bank statements Portal CLIO ArchiveGRID
Bibliographies Portal CLIO ArchiveGRID
Bills (financial) Portal CLIO ArchiveGRID
Biographies (literary works) Portal CLIO ArchiveGRID
Briefs Portal CLIO ArchiveGRID
Bylaws (administrative records) Portal CLIO ArchiveGRID
Charters Portal CLIO ArchiveGRID
Charts (graphic documents) Portal CLIO ArchiveGRID
Check stubs Portal CLIO ArchiveGRID
Checkbooks Portal CLIO ArchiveGRID
Clippings (Information Artifacts) Portal CLIO ArchiveGRID
Contracts Portal CLIO ArchiveGRID
Diagrams Portal CLIO ArchiveGRID
Dockets Portal CLIO ArchiveGRID
Financial records Portal CLIO ArchiveGRID
Glass plate negatives Portal CLIO ArchiveGRID
Graphs Portal CLIO ArchiveGRID
Insurance policies Portal CLIO ArchiveGRID
Inventories Portal CLIO ArchiveGRID
Lantern slides Portal CLIO ArchiveGRID
Lectures Portal CLIO ArchiveGRID
Letters patent Portal CLIO ArchiveGRID
Manuals (instructional materials) Portal CLIO ArchiveGRID
Maps (documents) Portal CLIO ArchiveGRID
Memorandums Portal CLIO ArchiveGRID
Notebooks Portal CLIO ArchiveGRID
Notes (documents) Portal CLIO ArchiveGRID
Patents Portal CLIO ArchiveGRID
Petitions Portal CLIO ArchiveGRID
Photographic prints Portal CLIO ArchiveGRID
Photographs Portal CLIO ArchiveGRID
Proceedings (reports) Portal CLIO ArchiveGRID
Regulations (executive records) Portal CLIO ArchiveGRID
Releases Portal CLIO ArchiveGRID
Reports Portal CLIO ArchiveGRID
Slides (photographs) Portal CLIO ArchiveGRID
Sound recordings Portal CLIO ArchiveGRID
Statistics Portal CLIO ArchiveGRID
Subpoenas Portal CLIO ArchiveGRID
Surveys (documents) Portal CLIO ArchiveGRID
Tax returns Portal CLIO ArchiveGRID
Technical drawings Portal CLIO ArchiveGRID
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Wills Portal CLIO ArchiveGRID
blueprints (reprographic copies) Portal CLIO ArchiveGRID
indexes (reference sources) Portal CLIO ArchiveGRID
logs (records) Portal CLIO ArchiveGRID
negatives (photographs) Portal CLIO ArchiveGRID


Heading "CUL Archives:"
"CUL Collections:"
"Nat'l / Int'l Archives:"
Alpine (N.J.) Portal CLIO ArchiveGRID
Armstrong, Edwin H (Edwin Howard), 1890-1954 Portal CLIO ArchiveGRID
Burger, Warren E., 1907-1995 Portal CLIO ArchiveGRID
Bush, Vannevar, 1890-1974 Portal CLIO ArchiveGRID
Butler, Nicholas Murray, 1862-1947 Portal CLIO ArchiveGRID
College teachers Portal CLIO ArchiveGRID
Columbia University. Marcellus Hartley Research Laboratory Portal CLIO ArchiveGRID
Coudert, Frederic R (Frederic René), 1871-1955 Portal CLIO ArchiveGRID
Cravath, Swaine & Moore Portal CLIO ArchiveGRID
De Forest, Lee, 1873-1961 Portal CLIO ArchiveGRID
De Voto, Bernard, 1897-1955 Portal CLIO ArchiveGRID
Dewey, Thomas E (Thomas Edmund), 1902-1971 Portal CLIO ArchiveGRID
Donovan, William J (William Joseph), 1883-1959 Portal CLIO ArchiveGRID
Eisenhower, Dwight D (Dwight David), 1890-1969 Portal CLIO ArchiveGRID
Electrical engineers Portal CLIO ArchiveGRID
Farley, James A. (James Aloysius), 1888-1976 Portal CLIO ArchiveGRID
Fermi, Enrico, 1901-1954 Portal CLIO ArchiveGRID
Hoover, Herbert, 1874-1964 Portal CLIO ArchiveGRID
Institute of Radio Engineers Portal CLIO ArchiveGRID
Inventors Portal CLIO ArchiveGRID
Kaempffert, Waldemar, 1877-1956 Portal CLIO ArchiveGRID
La Guardia, Fiorello H (Fiorello Henry), 1882-1947 Portal CLIO ArchiveGRID
Lodge, Henry Cabot, Jr., 1902-1985 Portal CLIO ArchiveGRID
Marconi, Guglielmo, 1874-1937 Portal CLIO ArchiveGRID
McCormick, Robert R. (Robert Rutherford), 1880-1955 Portal CLIO ArchiveGRID
Murray, Thomas E (Thomas Edward), 1860-1929 Portal CLIO ArchiveGRID
Paley, William S (William Samuel), 1901-1990 Portal CLIO ArchiveGRID
Patent lawyers Portal CLIO ArchiveGRID
Patent suits Portal CLIO ArchiveGRID
Powers of attorney Portal CLIO ArchiveGRID
Pupin, Michael, 1858-1935 Portal CLIO ArchiveGRID
Radar Portal CLIO ArchiveGRID
Radio -- Law and legislation Portal CLIO ArchiveGRID
Radio -- Patents Portal CLIO ArchiveGRID
Radio -- Receivers and reception -- Research Portal CLIO ArchiveGRID
Radio -- Transmitters and transmission -- Research Portal CLIO ArchiveGRID
Radio Club of America Portal CLIO ArchiveGRID
Radio Corporation of America Portal CLIO ArchiveGRID
Radio frequency modulation -- Research Portal CLIO ArchiveGRID
Radio stations -- New Jersey -- Alpine Portal CLIO ArchiveGRID
Round, Henry J Portal CLIO ArchiveGRID
Sarnoff, David, 1891-1971 Portal CLIO ArchiveGRID
Scrapbooks Portal CLIO ArchiveGRID
Stimson, Henry L (Henry Lewis), 1867-1950 Portal CLIO ArchiveGRID
Stokowski, Leopold, 1882-1977 Portal CLIO ArchiveGRID
Sulzberger, Arthur Hays, 1891-1968 Portal CLIO ArchiveGRID
Superheterodyne receivers -- Research Portal CLIO ArchiveGRID
United States. Air Force Portal CLIO ArchiveGRID
United States. Army. American Expeditionary Forces Portal CLIO ArchiveGRID
United States. Federal Communications Commission Portal CLIO ArchiveGRID
Woodbridge, Frederick James Eugene, 1867-1940 Portal CLIO ArchiveGRID
World War, 1914-1918 -- France Portal CLIO ArchiveGRID
World War, 1939-1945 Portal CLIO ArchiveGRID
Young, Owen D., 1874-1962 Portal CLIO ArchiveGRID
Zenith Radio Corporation Portal CLIO ArchiveGRID

History / Biographical Note

Biographical Note

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 phenomena.

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, Armstrong's career.

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, 1913.

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 of regeneration.

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.

The Super-heterodyne

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 as witness.

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 necessary.

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

Muhlenberg, 1941

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 Philadelphia, 1942

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