Radio

The transmission of sound signals through space by means of radio-frequency electromagnetic waves. In 1888 the German physicist Heinrich Hertz produced and detected radio waves, developing the equations made by James Clerk Maxwell. Guglielmo Marconi constructed a device to translate radio waves into electrical signals, and in 1901 transmitted signals across the Atlantic Ocean. Prior to World War 1, radio messages were sent between land stations and ships, and between land and aircraft. In 1918, a radiotelegraph message was transmitted from Wales to Australia. Radio broadcasting became routinely available during the 1920s, when such institutions as the BBC (1922) came into being. .