Youth and College Years

 Armstrong was born in New York City on 18 December 1890 to John Armstrong, an employee and later vice president of Oxford University Press, and Emily Smith Armstrong, a public school teacher. At the age of nine, Armstrong developed a severe case of Saint Vitus' Dance, a disorder causing involuntary contortions and contractions of muscles, especially in the face and neck, probably caused by rheumatic fever. Because of their concern over their son's illness, in 1900 the Armstrongs moved, 15 miles up the Hudson River to the relative serenity of Yonkers.

     When Armstrong was 13, his father gave him a book entitled The Boys Book of Inventions: Stories of the Wonders of Modern Science. The next year Armstrong read Stories of Inventors: The Adventures of Inventors and Engineers, True Incidents and Personal Experiences. From that time on, Arm­ strong knew that he would be an inventor. He was particularly interested in reading about Guglielmo Marconi and his invention of the wireless telegraph. By the time he entered high school in 1905, Armstrong's inventive energies focused on wireless, and, with the help and encouragement of his family, he set up his first "laboratory" in his upstairs bedroom, from which he sent and received wireless messages with his friends. By the time he graduated from high school in 1909, Armstrong had built wireless receivers so sophisticated that he regularly received signals from as far north as Newfoundland and as far south as Key West.

     Armstrong entered Columbia University in September 1909, commuting from his home in Yonkers on his high school graduation present, a red Indian motorcycle. The next year he gained admittance to the University's School of Mines, Engineering, and Chemistry, where he concentrated his studies in the electricity department. Though many of Armstrong's professors disliked him because of his willingness to question and even contradict their teachings, Armstrong found a mentor and proponent in Columbia's leading researcher in the electrical engineering department, Michael Pupin.

     Because he commuted to Columbia from his home in Yonkers, Armstrong was able to continue his wireless experiments in his bedroom laboratory. In 1910, dissatisfied with his indoor antenna, Armstrong built a 125-foot tower behind his house, to which he attached his antenna wire at the top. Armstrong built the tower himself, hoisting himself skyward on a bosun's chair. This early experience demonstrated another of Armstrong's passions: the love of heights.

     During his junior year at Columbia, Armstrong set out to understand the workings of the Audion tube, invented six years earlier by pioneer wireless inventor Lee de Forest. De Forest had taken the two-element "valve" (tube) of Ambrose Fleming and added another element, which he called a "grid." The grid allowed de Forest to regulate the flow of electrons through the tube and amplify them, thus providing a superior detection device for wireless signals. But de Forest never understood how or why his Audion worked. After much experimentation, Armstrong came to understand how the Audion worked and resolved to improve it by making it not only detect electromagnetic waves but amplify them as well. To do this, Armstrong fed the current back through the grid many thousands of times per second, thus amplifying it over and over again. He achieved success on 22 September 1912, noting "great amplification obtained at once." Using his new invention, Armstrong could receive signals from Ireland and Hawaii with remarkable clarity. The "feedback" or "regenerative" circuit, as it came to be known, revolutionized radio reception. Further tests of the regenerative circuit led Armstrong to discover that it could also be used to transmit continuous waves much more efficiently and powerfully than the large and expensive mechanical generators then in use. By early 1913, using modified circuitry, Armstrong successfully demonstrated the transmitting capabilities of his new invention.

     Armstrong graduated from the engineering program at Columbia University in June 1913. Later that year he filed two patent applications, one in October for his wireless receiving system and one in December for his transmission circuit. At about the same time, Armstrong demonstrated his regenerative circuit to the then chief inspector of the American Marconi Wireless Company, David Sarnoff. The two quickly became close friends.

Patent Battles and World War I

     Lee de Forest, believing that Armstrong had gained prominence by using his discovery, fought back by filing a patent in 1915 for an oscillating Audion, which he claimed to have discovered in 1912-a year before Armstrong filed his patents. In doing so, de Forest asserted that he was the inventor of the circuit that made the Audion work as both a receiver and a transmitter. This led to a series of patent infringement suits between the two inventors that lasted almost 20 years.

     The looming patent battles between Armstrong and deForest were delayed by the entry of the United States into World War I. During the war, the U.S. government suspended all patent cases and pooled the wireless patents in order to develop better technology for the war effort. The Navy Department controlled wireless and its development throughout the war. Armstrong joined the U.S. Army Signal Corps with the rank of captain; he was stationed in France, assigned to the division of research and inspection. Armstrong upgraded the wireless capabilities of the Expeditionary Forces on the ground and then developed a communication system for the Army Air Corps.

     While Armstrong was in France, he developed his second major invention-the superheterodyne. Allied forces suspected that the Germans were using very high-frequency bands to transmit messages, anywhere from 500,000 to 3 million cycles per second. Although receivers could be built to detect such high frequencies, tuning them proved to be extremely difficult. Armstrong developed a circuit that would combine the higher frequency with lower frequencies and then amplify them so they could be heard. This new circuit permitted the precise tuning of very high frequencies. Armstrong filed a patent for his new invention in France in 1918 and in the United States in 1919 when he returned from the war. For his efforts during the war he was promoted to major. While in Paris, Armstrong learned that the Institute of Radio Engineers had awarded him the first medal of honor it ever presented.

     Armstrong initially won his patent battles with de Forest and began to profit handsomely from the sale of his patents to Westinghouse and to the newly formed Radio Corporation of America (RCA). Sarnoff, then general manager and vice president of RCA, negotiated directly with Armstrong for rights to his next invention, the super-regeneration circuit. Following their agreement, which included cash and RCA stock, Armstrong became RCA's largest private shareholder. Armstrong's financial prosperity seemed secure. It was during this time that Armstrong met Marion Macinnis, Sarnoff's secretary, and began wooing her by doing tricks atop RCA's 115-foot towers in downtown New York and giving her rides in his new Hispano-Suiza automobile. They married on 1 December 1923. Armstrong's wedding gift to Marion was the first portable superheterodyne radio.

     Although Armstrong had won his patent case against de Forest in 1923, the decision was never finalized because Armstrong, considering de Forest an unethical thief, refused to sign off on the judgment, which waived de Forest's court costs because he was nearly bankrupt. Nor would Armstrong agree to license his patents to de Forest. With nothing to lose, de Forest initiated another suit in federal court, this time challenging adverse decisions from the U.S. Patent Office. In 1924 the court overruled the Patent Office decisions, ignored the prior court cases, and awarded the rights to the regenerative circuit to de Forest, based on an arcane reading of the original patent applications. Armstrong lost again at the U.S. Court of Appeals and then appealed the decision to the U.S. Supreme Court. In 1928, 15 years after Armstrong filed his patent for the regenerative circuit, the Court ruled decisively in de For­est's favor. The Court did not reach the merits of the claims but made the judgment based on a technical reading of the patent applications.

     Most of the community of radio engineers correctly believed that Armstrong had been wronged. Armstrong took up yet another patent suit against the owners of de Forest's regenerative circuit patent, now RCA. Armstrong lost at the trial level but won at the Court of Appeals. RCA, wanting to protect its ability to earn royalties on the patents, took the case to the Supreme Court. In 1934 the Court ruled again in favor of de Forest's claims. This time, however, the case was decided on the merits, with the Court finding that de Forest was the true inventor of the regenerative circuit. But the decision, written by Justice Cardozo, revealed serious errors in the Court's understanding of the inventions. Again the engineering community reacted with disapproval. Later that year Armstrong attended the annual meeting of the Institute of Radio Engineers, intending to return the medal of honor it had awarded him in 1918. The president of the Institute would not accept Armstrong's offer, and the assembled engineers, knowing who really invented the regenerative circuit, stood and applauded when Armstrong took the stage.

Invention of Frequency Modulation

     The amplitude modulation signals used by radio stations in the 1920s shared many drawbacks; among the most serious was that they were subject to significant levels of interference. This interference led to much crackling and hissing at the radio receiver. Armstrong had studied this problem on and off since 1914, but he did not pursue it seriously until 1923. One way of eliminating static that had been discussed by some radio engineers involved a different form of modulation in which the frequency of the carrier wave was modulated instead of the amplitude. However, mathematicians considering this issue stated categorically that frequency modulation could not solve the problem. Armstrong disagreed. For the next ten years, when not distracted with patent lawsuits, Armstrong worked toward eliminating static through the use of FM.

     Conventional wisdom dictated that radio should be sent via as narrow a bandwidth as possible. Widening the bandwidth, it was thought, would simply subject the signal to more interference. After several years of failure in trying to reduce interference through a narrow-band FM system, Armstrong changed course and began experimenting with wide-band FM transmission in 1931. After redesigning his transmitter and receiver to utilize wide-band (200 kHz) FM, Armstrong found success. In the process of designing his new system, Armstrong filed five new patents from 1930 to 1933, all of which were granted in 1933.

     In December 1933 he invited Sarnoff and several RCAengineers to his laboratory, where he displayed his new invention. Skeptical of the results, Sarnoff offered RCA transmitting space atop the Empire State Building for a field test. Armstrong conducted the first test on 9 June 1934. A receiver was placed in a house 70 miles from the transmitter. When Armstrong transmitted a signal via AM, there was significant static. When Armstrong switched over to his FM system, the static disappeared. In fact, the receiver picked up low notes from an organ that the AM signal, with its narrow band­ width, could not even carry. In addition to high-fidelity sound, later tests with Armstrong's FM system proved the possibility of sending more than one signal simultaneously-a process known as multiplexing.

     According to Sarnoff, Armstrong's invention was not an improvement, but a revolution-one that Sarnoff could not support given RCA's existing investment in AM radio and the NBC network, as well as Sarnoff's decision to spend heavily to develop television. By July 1935 Sarnoff asked Armstrong to remove his equipment so RCA could further test its television system. Sarnoff's lack of support for FM, plus RCA's recent patent suit against Armstrong, created a strain on their friendship.

     Without the backing of Sarnoff and RCA, Armstrong decided to pursue the development of FM on his own using his patent-generated fortune. After securing an experimental license from the Federal Communications Commission (FCC), Armstrong constructed an FM station in Alpine, New Jersey (across the Hudson from New York City), and began testing W2XMN in 1938. By 1940 several experimental FM stations, including several built by the Yankee Network in New England, all using Armstrong's technology, were in operation. At this time, Armstrong displayed the network potential of FM by relaying FM programs from station to station over the air, over the length of the East Coast, with virtually no signal deterioration. By the end of 1940, the FCC had received over 500 applications for FM licenses and had decided that the audio portion of television signals should be transmitted by FM. Commercial FM broadcasting was authorized to begin 1 January 1941.

World War II and More Patent Battles

     With the growing popularity of FM, Armstrong struck patent­ licensing deals with all of the major radio manufacturers except RCA. According to the terms of these agreements, the manufacturers agreed to pay Armstrong 2 percent of all their earnings from the sale of FM receivers and related equipment. When RCA finally realized the importance of FM, it offered Armstrong $1 million for a non-exclusionary license to use the FM technology. Armstrong refused, insisting that RCA pay the same royalty as the other manufacturers. This decision by Armstrong led to fierce patent battles as well as the loss of his friendship with Sarnoff and, over the next dozen years, his fortune, his wife, and his life.

     Once again, however, a war delayed the pending patent suits. When the United States entered World War II, Armstrong declined to accept royalty payments on the sale of radio equipment to the military, believing he should not profit from the war effort. He worked with military personnel to perfect FM equipment for their wireless communications links and then began working on long-range radar systems, which he continued to develop after the war.

     In 1944-45, the FCC undertook a number of investigations of spectrum allocation and use, drawing on wartime research. In a hugely controversial decision, the commission decided in early 1945 to shift the FM service higher in the VHF band, to 88-108 MHz. In so doing, it made more than 50 FM radio station transmitters and half a million FM receivers obsolete after a three-year transition period. Pressured by other major broadcasters who wanted to ensure AM radio's dominance, notably William Paley at Columbia Broadcasting System (CBS), the FCC also limited the power at which FM stations could operate. Although Armstrong contested them, these actions by the FCC severely limited (and nearly terminated) FM radio broadcasting for more than a decade while the industry turned to developing television and expanding AM.

     Meanwhile, unwilling to pay Armstrong the royalties he sought, RCA began developing FM circuits of its own, which its engineers claimed did not use Armstrong's inventions. By using these circuits, RCA would not have to pay Armstrong any royalties on the sale of television sets, which used FM for the audio portion of the signal. RCA convinced other set manufacturers to do the same. In July 1948 Armstrong filed suit against RCA, alleging infringement on his five basic FM patients. RCA's trial strategy was to delay the proceedings as long as possible, to a date after the expiration of Armstrong's parents. RCA's attorneys also realized that, without any royalty revenues, Armstrong would soon be broke and unable to continue prosecuting the case. The strategy worked. By 1952 Armstrong had run out of money and had to rely on credit to pay his lawyers.

     In August 1953 Armstrong proposed to settle the suit against RCA, seeking $3.4 million over a ten-year period. In December RCA responded by agreeing to pay $200,000 initially, with an "option" to pay more the next year. The option meant that Armstrong was guaranteed nothing but the initial $200,000, and Armstrong rejected the offer.

     The years of litigation had taken their toll. His one-time friend David Sarnoff was now his bitter enemy. His fortune was depleted. In a fit of rage in November 1953, he took his anger out on Marion, his wife of 30 years, and she fled their apartment. On the evening of 31 January 1954, Armstrong wrote a note to Marion apologizing for his actions. He then stepped outside the window of his 13th-story apartment and fell to his death.

     Marion Armstrong continued the patent battles. RCA settled its case for just over $1 million in 1955. Through settlements and court decisions-the last of which came in 1967- the other equipment manufacturers began paying damages. In the end, all of Armstrong's FM patent claims were upheld.