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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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The first intentional transmission of a signal by means of electromagnetic waves was performed in an experiment by David Edward Hughes around 1880.
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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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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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The invention of amplitude-modulated (AM) radio, so that more than one station can send signals (as opposed to spark-gap radio, where one transmitter covers the entire bandwidth of the spectrum). This invention was made by Reginald Fessenden.
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Inventor Edwin Howard Armstrong is credited with developing many of the features of radio as it is known today. Armstrong patented three important inventions that made today's radio possible. Regeneration, the superheterodyne circuit and wide-band frequency modulation or FM.
