Edwin Armstrong was one of the most prolific inventors of the radio era, with a vision that was ahead of his time.
Armstrong was the inventor of FM radio. He also invented the Regenerative circuit (invented while he was a junior in college, and patented 1914), the Super-regenerative circuit (patented 1922), and the Super Heterodyne receiver (patented 1918). Many of Armstrong's inventions were ultimately claimed by others in patent lawsuits. Armstrong's life is both a story about the great inventions he brought about, and the tragedy wherein those inventions' rights were claimed by others.
In particular, the regenerative circuit, which Armstrong patented in 1914, was subsequently patented by Lee DeForest in 1916; deForest then sold the rights to his patent to AT&T. Between 1922 and 1934, Armstrong found himself embroiled in a patent war, between himself, RCA, and Westinghouse on one side, and deForest and AT&T on the other. This patent lawsuit was the longest ever litigated to its date, at 12 years. Armstrong won the first round of the lawsuit, lost the second, and stalemated in a third. Before the United States Supreme Court, deForest was granted the regeneration patent in what is today widely believed to be a misunderstanding of the technical facts by the Supreme Court.
Even as the regeneration circuit lawsuit continued, Armstrong created another significant invention: frequency modulation. Rather than varying the amplitude of a radio wave to create sound, Armstrong's method used varying the frequency of the wave instead. Significantly, FM radio receivers proved to generate a much clearer sound, free of static, than the AM radio dominant at the time.
In proving the utility of FM technology, Armstrong successfully lobbied the FCC to create an FM radio band, between 42 and 49 MHz.
In the early 1940s, shortly before and during World War II, Armstong then helped to market a small number of high powered FM radio stations in the New England states, known as the Yankee Network. Armstrong had begun on a journey to convince America that FM radio was superior to AM, and, he hoped, to collect patent royalties on every radio sold with FM technology.
By June of 1945, the Radio Corporation of America, RCA had pushed the FCC hard on the allocation of electromagnetic frequencies for the fledgling television industry. Although they denied wrongdoing, David Sarnoff and RCA managed to get the FCC to move the FM radio spectrum from (42 to 49 MHz), to (88 to 108 MHz), while getting new television channels allocated in the 40-Megahertz range.
Coincidentally or otherwise, this rendered all Armstrong-era FM sets useless overnight, while helping protect RCA's strong AM radio stronghold. Armstrong's radio network did not survive the frequency shift up into the high frequencies; some experts believe that FM technology was set back decades by the FCC's decision.
Furthermore, RCA ultimately claimed and won its own patent on FM technology, and won the ensuing patent fight between themselves and Edwin Armstrong, leaving Armstrong without the ability to claim royalties on FM radios sold in the United States. The undermining of the Yankee Network and patent court fight left Armstrong virtually penniless and emotionally destroyed.
In this state, Armstrong committed suicide in 1954 by jumping out of his apartment window, depressed by what he saw as the failure of his invention of FM radio. It took decades after Armstrong's death for FM radio to meet and surpass the saturation of AM, and longer still for FM radio to become profitable for its broadcasters. Ultimately, however, the genius of FM technology was proven by its wide adoption today.