Edwin Howard Armstrong
American inventor of FM radio and the superheterodyne receiver.
Edwin Howard Armstrong was an American engineer and inventor best known for creating FM radio and the superheterodyne receiver. Born on December 18, 1890, in Chelsea, New York City, he was the oldest of three children. His father worked his way up to vice president at the American branch of Oxford University Press, and the family was comfortably middle class. When Armstrong was eight, he contracted Sydenham's chorea from rheumatic fever, a neurological disorder that left him with a lifelong physical tic that worsened under stress. The illness forced him out of public school and into home tutoring for two years, and the family moved to Yonkers for his health. He became socially withdrawn but showed an early passion for electrical and mechanical devices, building a backyard antenna tower with a bosun's chair that alarmed neighbors. Much of his early research took place in his parents' attic.
In 1909, Armstrong entered Columbia University, where he joined the Theta Xi engineering fraternity and studied under Professor Michael Pupin at Hartley Laboratories. He was intensely focused on subjects that interested him but indifferent to others, often challenging professors and peers. He once tricked a visiting Cornell professor he disliked into receiving a severe electric shock. He valued experimentation over mathematical theory. After earning his electrical engineering degree in 1913, he worked as a laboratory assistant at Columbia for a year on a $600 stipend, then as a research assistant for $1 a year under Pupin. Unlike most engineers, he never worked for a corporation; he set up his own independent lab at Columbia and owned all his patents. During World War I, he served in the U.S. Army Signal Corps, rising to the rank of major—a title that stuck with him throughout his career. In 1934, he became a professor of electrical engineering at Columbia, a position he held for life.
Armstrong’s first major invention came while he was still an undergraduate. He studied vacuum tubes in depth with Professor John Morecroft, using an oscillograph to understand how they worked. His breakthrough was discovering that positive feedback—called regeneration—could dramatically amplify signals. This led to the regenerative circuit, one of his 42 patents. He also developed the superheterodyne receiver and, later, FM radio.
Quick Facts
- Birth Date
- 1890-12-18
- Birth Place
- New York City, US
- Death Date
- 1954-02-01
- Education
- Columbia University
- Known For
- Armstrong oscillator / Armstrong phase modulator / Superheterodyne receiver / Regenerative circuit / FM radio
- Spouse
- Esther Marion McInnis · 1922
- Awards
- IRE Medal of Honor (1917) / Holley Medal (1940) / Franklin Medal (1941) / AIEE Edison Medal (1942) / Washington Award (1951)
- Fields
- Radio-frequency engineering
- Academic Advisors
- Michael Pupin
Facts from the source article.
Lore & Background
Armstrong was born on December 18, 1890, in Chelsea, New York City, the eldest of three children of John Armstrong and Emily Smith. At age eight he contracted Sydenham's chorea, a neurological disorder that left him with a physical tic exacerbated by excitement or stress, leading to home tutoring and social withdrawal. He showed an early interest in electrical and mechanical devices, constructing a makeshift backyard antenna tower. He enrolled at Columbia University in 1909, studied under Professor Michael Pupin, and graduated in 1913 with an electrical engineering degree. During World War I he served in the Signal Corps as a captain and later a major. He later became a professor of Electrical Engineering at Columbia, a position he held for the remainder of his life.
Armstrong began working on his first major invention, the regenerative circuit, while still an undergraduate. His breakthrough was determining that positive feedback produced amplification hundreds of times greater than previously attained, allowing receivers to use loudspeakers instead of headphones. He also discovered that when feedback was increased beyond a certain level, a vacuum tube would oscillate and could be used as a continuous-wave radio transmitter. He applied for patent protection in late 1913, and U.S. patent 1,113,149 was issued on October 6, 1914. Lee de Forest later filed competing patent applications claiming he had discovered regeneration first, leading to an interference hearing. The interference board sided with Armstrong, but de Forest appealed. Armstrong also licensed his regenerative patents to small radio equipment firms, and Westinghouse took an option for commercial rights to both the regenerative and superheterodyne patents.
Armstrong is also noted for his legal battles with Lee de Forest and David Sarnoff. The prolonged litigation took a toll on his health and finances, leading to a breakdown in his marriage, followed by his suicide in 1954. Thereafter, his estate's legal cases were pursued by his widow, Marion, who won several successful suits and settlements.
Reader's Guide
Armstrong's development of FM (frequency modulation) radio and the superheterodyne receiver system fundamentally shaped modern radio electronics. The superheterodyne receiver became the standard design for radio receivers, offering superior selectivity and sensitivity. FM radio provided a method of transmission that was less susceptible to static and interference than AM, revolutionizing broadcast quality. His regenerative circuit, which used positive feedback to achieve high amplification, was a key early advance in vacuum-tube technology. Despite these contributions, Armstrong's later years were consumed by protracted legal disputes over patent priority, particularly with Lee de Forest and David Sarnoff. These battles drained his finances and health, culminating in his suicide in 1954. After his death, his widow Marion pursued the estate's legal cases and won several successful suits and settlements. Armstrong's legacy is recognized through his induction into the National Inventors Hall of Fame, inclusion in the International Telecommunication Union's roster of great inventors, and posthumous induction into the Wireless Hall of Fame in 2001. His work remains foundational to radio and wireless communications.
Did You Know?
- Armstrong held 42 patents and received the first Medal of Honor awarded by the Institute of Radio Engineers (now IEEE).
- He achieved the rank of major in the U.S. Army Signal Corps during World War I and was often called 'Major Armstrong'.
- At age eight he contracted Sydenham's chorea, which left him with a lifelong physical tic exacerbated by stress.
- His widow Marion pursued his estate's legal cases after his suicide and won several successful suits and settlements.
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