Brief history of radio
1873 The British physicist James Clerk-Maxwell announces the theory of electro-magnetic waves.

Morse Samuel Morse. (1791 - 1872)

Morse was born in Charlestown, Massachusetts (now part of Boston), on April 27, 1791, and educated at Yale College (now Yale University). He studied painting in London and became a successful portrait painter and sculptor. In 1825 he helped found the National Academy of Design in New York City, and the following year he became the first president of the institution. He continued his painting and became a professor of painting and sculpture at New York University in 1832. About that time he became interested in chemical and electrical experiments and developed apparatus for an electromagnetic telegraph that he completed in 1836. The following year he filed a caveat, or legal notice, at the patent office in Washington, D.C., and tried without success to obtain European patents for his apparatus. He also invented a code, now known as the Morse code, for use with his telegraph instrument.

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1888 Heinrich Hertz produces the first electro-magnetic waves by supplying an electric charge to a capacitor and then short-ciruiting it. The energy from the resulting spark is radiated in the form of electromagnetic waves and Hetz is able to measure the wavelength and velocity of these so-called Hertzian waves.

1894 British physicist Sir Oliver Lodge uses a device called the coherer to detect the presence of radio waves and demonstrates that these waves could be used for signalling.

1895 Marconi finally devises a practical apparatus for the purpose, comprising an aerial, a condenser and a connection to earth.

1896 Marconi demonstrates his apparatus to the British authorities by transmitting signals for more than 1 mile and he applies for his first British patent.

1898 Wireless telegraphy is used for the first time in naval manoeuvres - a range of 60 miles.

1899 Communication between England and France.

1901 Communication across the Atlantic.

1906 American inventor de Forest adds a third electrode to the diode and produces a sensitive receiver and amplifier.

Guglielmo Marconi (1874 - 1937)

Italian electrical engineer, He was born in Bologna and educated at the University of Bologna. As early as 1890 he became interested in wireless telegraphy, and by 1895 he had developed apparatus with which he succeeded in sending signals to a point a few kilometers away by means of a directional antenna. After patenting his system in Great Britain, he formed (1897) Marconi's Wireless Telegraph Company, Ltd., in London. In 1899 he established communication across the English Channel between England and France, and in 1901 he communicated signals across the Atlantic Ocean between Poldhu, in Cornwall, England, and Saint John's, in Newfoundland, Canada. His system was soon adopted by the British and Italian navies, and by 1907 had been so much improved that transatlantic wireless telegraph service was established for public use. Marconi was awarded honors by many countries and received, jointly with the German physicist Karl Ferdinand Braun, the 1909 Nobel Prize in physics for his work in wireless telegraphy.

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1914 The thermionic valve is used as a radio generator which produces a carrier wave capable of being modulated by speech. Marconi transmits speech over 50 miles.

1915 A radio station in Arlington, USA, communicates with both Paris and Honolulu.

1920 The rectifying properties of crystals, which means they could be used as radio detectors, gives rise to the popularity of the crystal-set.

Today! Immense developments in radio communication technology after World War II helped make possible space exploration, most dramatically in the Apollo moon-landing missions (1969-72) and communications satellites.

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