Edwin Howard Armstrong was an American electrical engineer and inventor the regenerative circuit, the superheterodyne circuit and the complete Frequency Modulation( FM) system, all  of which are considered essential to modern radio, radar, and television.  Often noted as one of the radio's leading inventors, Armstrong invented the regenerative circuit (1912), which revolutionized wireless radio communication by amplifying weak radio signals without distortion far more effectively than other radio receivers of that time; the superheterodyne circuit (1918), which further improved the ability to receive radio signals; and the complete Frequency Modualtion (FM) system (1933) that would eventually displace Amplitude Modulation (AM) technology. In 1940, Armstrong was issued a permit to build the first FM station, which he erected at his own expense on the Hudson River Palisades at Alpine, NJ.

Source

• Cleveland, Cutler (Lead Author); Tom Lawrence (Topic Editor). 2008. "Armstrong, Edwin Howard." In: Encyclopedia of Earth. Eds. Cutler J. Cleveland (Washington, D.C.: Environmental Information Coalition, National Council for Science and the Environment). [First published in the Encyclopedia of Earth June 15, 2006; Last revised August 21, 2008; Retrieved July 6, 2009