Different types of radio waves travel around the world in different ways, according to their frequency. Short waves can travel...Read More >>Different types of radio waves travel around the world in different ways, according to their frequency. Short waves can travel great distances by bouncing off a layer of the atmosphere called the ionosphere. Microwaves can only move in straight lines and travel from one radio mast to the next, or via satellites. Medium and long waves can travel for several hundred kilometres. The word “radio” means communicating with radio waves, which move through the air at the speed of light. These are part of the electromagnetic spectrum. Radio has a huge range of applications. It is used in the telephone network for mobile phones and links in the network, including Wi-Fi and Bluetooth, for TV and radio broadcasting, for two-way radio communications as used by the emergency services, and for remote control of machines. “Radio” also means the media of radio, in which music and speech from radio stations are transmitted by radio waves (analogue or digital), cable or internet, and are picked up by radio or digital receivers.
First radio signal
The existence of radio waves was confirmed in 1888 by the German physicist Heinrich Hertz (1857–1894), but it was the Italian Guglielmo Marconi (1874–1937) who, in 1896, was the first to make long-distance radio transmissions. In 1901, the first transatlantic radio signal, the three dots of S in Morse code, from the Poldhu Wireless Station, Cornwall, England, was received extremely faintly at Signal Hill, Newfoundland in Canada, 3520 kilometres (2200 miles) away.
Using an antenna carried by a kite, the signal was received by Marconi himself, but his claims were not verified. Marconi carried out further tests over the next two years to prove his success.
Italian radio pioneer Guglielmo Marconi with his radio equipment
By 1903, Marconi's radio signals were sufficiently developed for the US President Theodore Roosevelt to send a message of greetings to King Edward VII of the UK. Two-way radio communications using Morse code began in the early 20th century, and radio broadcasting began in the 1920s.
The first use of the word "radio" was made by US inventor Lee De Forest in 1907, who preferred it to "wireless". De Forest conducted the first public radio broadcast in 1910, when part of a performance of Puccini's opera Tosca in New York City was broadcast experimentally.
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