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Invention of Radio

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Main article: Invention of radio

Source: wikipedia

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The idea of wireless communication predates the discovery of "radio" with experiments in "wireless telegraphy" via inductive and capacitive induction and transmission through the ground, water, and even train tracks from the 1830s on. James Clerk Maxwell showed in theoretical and mathematical form in 1864 that electromagnetic waves could propagate through free space.[1][2] It is likely that the first intentional transmission of a signal by means of electromagnetic waves was performed in an experiment by David Edward Hughes around 1880, although this was considered to be induction at the time. In 1888 Heinrich Rudolf Hertz was able to conclusively prove transmitted airborne electromagnetic waves in an experiment confirming Maxwell's theory of electromagnetism.

 

Electrical engineer/inventor Guglielmo Marconi with the spark-gap transmitter (right) and coherer receiver (left) he used in some of his first long distance radiotelegraphy transmissions during the 1890s.

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After the discovery of these "Hertzian waves" (it would take almost 20 years for the term "radio" to be universally adopted for this type of electromagnetic radiation)[3] many scientists and inventors experimented with transmitting and detecting Hertzian waves. Maxwell's theory showing that light and Hertzian electromagnetic waves were the same phenomenon at different wavelengths led "Maxwellian" scientists such as John Perry, Frederick Thomas Trouton and Alexander Trotter to assume they would be analogous to optical light.[4][5] The Serbian American engineer Nikola Tesla (who proposed a wireless power/communication earth conduction system similar to radio in 1893)[6][7][8] considered Hertzian waves relatively useless for his system since "light" could not transmit further than line of sight.[9] In 1892 the physicist William Crookes wrote on the possibilities of wireless telegraphy based on Hertzian waves.[10] Others, such as Sir Oliver Lodge, Jagadish Chandra Bose, and Alexander Popov were involved in the development of components and theory involved with the transmission and reception of airborne electromagnetic waves for their own theoretical work.

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Over several years starting in 1894 the Italian inventor Guglielmo Marconi built the first engineering complete, commercially successful wireless telegraphy system based on airborne Hertzian waves (radio transmission).[11] Marconi demonstrated the application of radio in military and marine communications and started a company for the development and propagation of radio communication services and equipment.

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In 1900, the invention of the radio was patented allowing news and music to be broadcast to many people simultaneously. It wasn’t long before inventors figured out how to broadcast pictures with the audio and soon the television was born. By 1955, television had made its way into the living rooms of half of the American population.