The American electrical engineer and radio inventor Edwin Howard Armstrong (1890-1954) was one of a small group who made fundamental contributions to the development of radio.

Edwin Armstrong was born in New York City, where his father was the American representative of the Oxford University Press. Armstrong rode his motorcycle to classes at Columbia University, and he took a degree in electrical engineering in 1913. He remained at Columbia for the rest of his life, serving as research assistant to Michael Pupin and, on the latter's death in 1934, as professor of electrical engineering.

Armstrong had one of those turbulent careers typical of so many inventors, especially those working in new and rapidly developing industries. Driven by a thirst for historical vindication and a love of legal combat, perhaps more than by the desire for money, inventors have plagued each other's lives to a remarkable degree. Armstrong took out his first patent before he finished college in 1913, and patents and disputes over them always seem to have occupied an inordinate amount of his time and effort.

His early and long association with Prof. Pupin gave Armstrong direct access to one of the best and most fertile minds in the electrical field. Armstrong's academic base also kept him free of connection with any of the many companies then vying for dominance in the radio field; he was one of the few men to successfully maintain such independence.

The radio was not one invention but a combination of inventions, many of them of disputed origin. Armstrong's first important contribution was his realization of the value of Lee De Forest's audion vacuum tube as a means of amplifying current. To Armstrong this realization appeared to rank alongside the invention of the audion itself. Armstrong's second contribution was the feedback circuit, another means of amplifying current, which he (and others independently) worked out in 1912. The following year he discovered that the audion could be used to generate high-frequency oscillations; again, there were several contemporary claims to this discovery.

While serving as a signal officer in World War I, Armstrong developed in 1918 the superheterodyne circuit, in which incoming high-frequency signals were beaten against low-frequency signals from a local oscillator so that they could be detected. After the war he sold his feedback and superheterodyne patents to the Westinghouse Company for $350,000 and received even more from the Radio Corporation of America (RCA) for a superregenerative invention. His last great contribution was frequency modulation (FM), a method of overcoming static in broadcasting, on which he worked from 1924 to 1933 in the face of indifference and even hostility from large manufacturers and broadcasters.

During his last years perhaps 90 percent of Armstrong's time was taken up by court battles with the National Broadcasting Company, and others; this poisoned his life. He died, an apparent suicide, in 1954.

Further Reading

• There is no biography of Armstrong. A brief discussion of his work is in John Jewkes, David Sawers, and Richard Stillerman, The Sources of Invention (1958). The standard history of the radio is William R. Maclaurin, Invention and Innovation in the Radio Industry (1949). Two other useful books are Donald M. McNicol, Radio's Conquest of Space (1946), and Carl F.J. Overhage, ed., The Age of Electronics (1962).
• Lewis, Thomas S. W., The Legacies of Edwin Howard Armstrong: the regenerative circuit, the superheterodyne circuit, the superregenerative circuit, frequency modulatio, Radio Club of America, 1990.