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James Clerk Maxwell showed in theoretical and mathematical form in 1864 that electromagnetic waves could propagate through free space.
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In 1888 Heinrich Rudolf Hertz was able to conclusively prove transmitted airborne electromagnetic waves in an experiment confirming Maxwell's theory of electromagnetism.
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Over several years starting in 1894 the Italian inventor Guglielmo Marconi built the first complete, commercially successful wireless telegraphy system based on airborne Hertzian waves (radio transmission).
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In 1900, Brazilian priest Roberto Landell de Moura transmitted the human voice wirelessly for a distance of approximately a half mile.
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In June 1912 Marconi opened the world's first purpose-built radio factory at New Street Works in Chelmsford, England.
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The first radio news program was broadcast August 31, 1920 by station 8MK in Detroit, Michigan, which survives today as all-news format station WWJ under ownership of the CBS network. The first college radio station began broadcasting on October 14, 1920 from Union College, Schenectady, New York under the personal call letters of Wendell King, an African-American student at the school.
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In the early 1930s, single sideband and frequency modulation were invented by amateur radio operators. By the end of the decade, they were established commercial modes.
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In 1947 AT&T commercialized the Mobile Telephone Service. From its start in St. Louis in 1946, AT&T then introduced Mobile Telephone Service to one hundred towns and highway corridors by 1948.
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In 1955, the newly formed Sony company introduced its first transistorized radio.[47] It was small enough to fit in a vest pocket, powered by a small battery. It was durable, because it had no vacuum tubes to burn out. Over the next 20 years, transistors replaced tubes almost completely except for high-power transmitters.
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By 1963, color television was being broadcast commercially (though not all broadcasts or programs were in color), and the first (radio) communication satellite, Telstar, was launched. In the late 1960s, the U.S. long-distance telephone network began to convert to a digital network, employing digital radios for many of its links.
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The Advanced Mobile Phone System analog mobile cell phone system, developed by Bell Labs, was introduced in the Americas in 1978, gave much more capacity.
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Soon, the U.S. Navy experimented with satellite navigation, culminating in the launch of the Global Positioning System (GPS) constellation in 1987.
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Internet radio was pioneered by Carl Malamud. In 1993, Malamud launched "Internet Talk Radio" which was the "first computer-radio talk show, each week interviewing a computer expert.".
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In 2003, revenue from online streaming music radio was US$49 million. By 2006, that figure rose to US$500 million.[3] A February 21, 2007 "survey of 3,000 Americans released by consultancy Bridge Ratings & Research" found that "[a]s much as 19% of U.S. consumers 12 and older listen to Web-based radio stations." In other words, there were "some 57 million weekly listeners of Internet radio programs.
