Biography of Edwin Howard Armstrong, Inventor of FM Radio

Edwin Howard Armstrong

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Edwin Howard Armstrong (December 18, 1890–February 1, 1954) was an American inventor and one of the great engineers of the 20th century. He is best known for developing the technology for FM (frequency modulation) radio. Armstrong won numerous patents for his inventions and was inducted into the National Inventors Hall of Fame in 1980.

Fast Facts: Edwin Howard Armstrong

  • Known For: Armstrong was an accomplished inventor who developed the technology for FM radio.
  • Born: December 18, 1890 in New York, New York
  • Parents: John and Emily Armstrong
  • Died: February 1, 1954 in New York, New York
  • Education: Columbia University
  • Awards and Honors: National Inventors Hall of Fame, Institute of Radio Engineers Medal of Honor, French Legion of Honor, Franklin Medal
  • Spouse: Marion MacInnis (m. 1922-1954)

Early Life

Armstrong was born in New York City on December 18, 1890, the son of John and Emily Armstrong. His father was an employee of Oxford University Press, while his mother was deeply involved in the Presbyterian Church. When he was still very young Armstrong became afflicted with St. Vitus' Dance—a muscular disorder—which forced him to be home-schooled for two years.


Armstrong was only 11 years old when Guglielmo Marconi made the first trans-Atlantic radio transmission. Enthralled, the young Armstrong began studying radio and building homemade wireless equipment, including a 125-foot antenna in his parents' backyard. His interest in science and technology took Armstrong to Columbia University, where he studied at the school's Hartley Laboratories and made a strong impression on several of his professors. He finished college in 1913 with a degree in electrical engineering.

Regenerative Circuit

The same year he graduated, Armstrong invented the regenerative or feedback circuit. Regeneration amplification worked by feeding a received radio signal through a radio tube 20,000 times per second, increasing the power of the received radio signal and allowing radio broadcasts to have a greater range. In 1914, Armstrong was awarded a patent for this invention. His success, however, was short-lived; the following year another inventor, Lee de Forest, filed several applications for competing patents. De Forest believed that he had developed the regenerative circuit first, as did several other inventors who became involved in the legal dispute that lasted many years. Although an initial case was resolved in Armstrong's favor, a later decision ruled that De Forest was the true inventor of the regenerative circuit. This was Armstrong's first experience with the legal system that would later cause him so much turmoil.

FM Radio

Armstrong is most commonly known for inventing frequency modulation, or FM radio, in 1933. FM improved the audio signal of radio by controlling the static caused by electrical equipment and the earth's atmosphere. Prior to this, amplitude modulation (AM) radio had been extremely susceptible to such interference, which was what prompted Armstrong to investigate the problem in the first place. He conducted his experiments in the basement of Columbia University's Philosophy Hall. In 1933, Armstrong received U.S. patent 1,342,885 for a "Method of Receiving High-Frequency Oscillations Radio" for his FM technology.

Again, Armstrong was not the only one experimenting with such technology. Scientists at the Radio Corporation of America (RCA) were also testing frequency modulation techniques to improve radio transmissions. In 1934, Armstrong presented his latest finding to a group of RCA officials; he later demonstrated the power of the technology using an antenna at the top of the Empire State Building. RCA, however, decided not to invest in the technology and instead focused on television broadcasting.

Armstrong had not lost faith in his discovery, though. He continued to refine and promote FM radio technology, first by partnering with smaller companies such as General Electric and then by presenting the technology to the Federal Communications Commission (FCC). Unlike the RCA officials, those at the FCC presentation were impressed by Armstrong's demonstration; when he played them a jazz recording over FM radio, they were struck by the clarity of the sound.

Improvements to FM technology over the 1930s made it more and more competitive with existing technologies. In 1940, the FCC decided to create a commercial FM service, which launched the following year with 40 channels. However, the outbreak of World War II limited the resources that could be put toward new radio infrastructure. Conflicts with RCA—which was still using AM transmissions—also prevented FM radio from taking off. It was not until after the war that the technology began to win popular support.

In 1940, RCA, seeing that it was losing the technological race, tried to license Armstrong's patents, but he refused the offer. The company then developed its own FM system. Armstrong accused RCA of patent infringement and began litigation against the company, hoping to win damages for lost royalties.


Armstrong's inventions made him a rich man, and he held 42 patents in his lifetime. However, he also found himself embroiled in protracted legal disputes with RCA, which viewed FM radio as a threat to its AM radio business. Much of Armstrong's time, as a consequence of the litigation, was devoted to legal matters rather than work on new inventions. Struggling with personal and financial problems, Armstrong committed suicide in 1954 by jumping to his death from his New York City apartment. He was buried in Merrimac, Massachusetts.


In addition to frequency modulation, Armstrong is also known for developing a number of other key innovations. Every radio or television set today makes use of one or more of his inventions. Armstrong even invented the superheterodyne tuner that allowed radios to tune into different radio stations. During the 1960s, NASA used FM transmissions to communicate with its astronauts while they were in space. Today, FM technology is still used throughout the world for most forms of audio broadcasting.


  • Sterling, Christopher H., and Michael C. Keith. "Sounds of Change: a History of FM Broadcasting in America." University of North Carolina Press, 2008.
  • Richter, William A. "Radio: a Complete Guide to the Industry." Lang, 2006.