No one person in the colorful history of radio can be credited with inventing radio. Almost all radio “inventors” improved on someone else’s idea. Wireless communication became a theoretical hypothesis in 1864, when the Scottish mathematician and physicist James Clerk Maxwell predicted the existence of invisible electromagnetic waves. More than twenty years later, German physicist Heinrich Hertz conducted experiments in 1887 to prove Maxwell’s theories correct. The fundamental unit of frequency of electromagnetic waves, Hertz (Hz), is named after him, although Hertz never promoted wireless communication.
In the 1890s, four inventors were working simultaneously on wireless transmission and detection. French physicist Edouard Branly invented a signal detector called the “cohereur,” which consisted of a glass tube filled with metal filings that responded to signal detection. The English physicist Oliver Lodge worked on the principle of resonance tuning, which allowed the transmitter and receiver to operate on the same frequency. Alexander Popov of Russia developed the best coherency and vertical receiving antenna.
The fourth and most famous pioneering inventor was the twenty-year-old Italian Guglielmo Marconi, who began experimenting with wireless communication in 1894. Within two years Marconi had created a wireless system capable of sending and detecting a signal. When the Italian government showed no interest in wireless, Marconi’s family connections allowed him to meet investors in England. He founded British Marconi in 1897 and began selling radio as a telegraph that did not require wires to send dots and dashes of Morse code . British Marconi and a subsidiary of American Marconi in the United States dominated wireless communications for ship-to-shore and transatlantic communications until after World War I .
Canadian Reginald Fessenden created a wireless system that would transmit speech. On Christmas Eve 1906, Fessenden broadcast programs from a studio in Brant Rock, Massachusetts. An audience of frightened radio operators on ships at sea, newspaper reporters who had been alerted to his publicity broadcast, and a small number of home experimenters heard Fessenden speak and play the fiddle.
After several failures and allegations that he was a fraud, American Lee De Forest’s radio company aired publicity-inducing broadcasts, including one from the Eiffel Tower in Paris. In 1906, De Forest also took credit for creating one of the most important wireless components, the Audion, a triode electronic tube that amplified signals and improved reception. Previously, receivers had struggled to detect weak radio signals. Although De Forest owned the patent for Audion, historians say he did not fully understand what he had invented or how it worked.
Beginning in 1912, Edwin Armstrong studied Audion and discovered the principle of regeneration. Regeneration improved signal amplification and produced the oscillating signal or carrier wave that has become the fundamental principle of modern radio transmitters.
Greed, the pursuit of fame, or maybe just the association of many individuals pursuing the same subject at the same time, led to a succession of patent lawsuits. The U.S. government stopped these disputes after the United States entered World War I in 1917. During the war, as a security measure, the U.S. Navy took over all radio stations, even those owned by American Marconi, and shut down most amateur and experimental stations. After the war, American Marconi tried to return to regular business, but opposed a foreign company with a monopoly on wireless communications in the United States .Eventually leading to General Electric (GE) buying a controlling interest in American Marconi in 1919. Along with co-owners Westinghouse and American Telephone & Telegraph (AT&T), GE transferred American Marconi’s assets to Radio Corporation of America (RCA), which made radio receivers. Probably the biggest breakthrough in receiver design came from Armstrong, who developed a tuner with better amplification and sound quality. The superheterodyne receiver was licensed by RCA in 1920 and was soon put into production.