Radio technology is based on the principle of converting sound waves into electrical oscillations which are broadcast from a transmitting antenna in the form of electromagnetic waves. At the receiving antenna, the radio, they are converted back into audible signals.

On 13th December 1888, the German physicist Heinrich Hertz proved the existence of electromagnetic waves, which spread through the air unseen and at great speed – a discovery without which radio would have been unthinkable.

In 1890, the Frenchman Edouard Branly built a glass tube filled with metal filings. This device, known as a ‘coherer,’ made it possible to receive individual signals – an important step towards wireless telegraphy which was taken further by the American-based Serb Nikola Tesla in 1893 with his own experiments. However, his completed system was destroyed by fire.

On 12th March 1896, the Russian Alexander Stepanovitch Popov finally succeeded in transmitting the words “Heinrich Hertz” in Morse code to a receiving station 250 metres away. Just a few months later, Guglielmo Marconi succeeded in broadcasting over a distance of some three kilometres with his equipment. The Italian had combined Hertz’s dipole, Popov’s antenna and Branly’s coherer receiver in an operational telegraph system, for which he obtained a patent in June 1896.

In 1897, following significant improvements to the sparking devices, the German scientist Adolf Slaby managed to establish a wireless link over a distance of 21 kilometres.

On 12th December 1901, Marconi telegraphed the letter ‘S’ in wireless form from Poldhu in England to St. John’s in Newfoundland, Canada. The signal was received over a distance of 3,400 kilometres, and Marconi was relieved to discover that electromagnetic waves do not disappear into space, but follow the curve of the earth’s surface.

In 1906, the Canadian engineer Reginald Aubrey Fessenden successfully generated a continuous carrier wave whose oscillations were variable, thus opening the way for wireless voice transmission. The actual moment of radio’s birth is considered to be Christmas 1906 when Fessenden’s transmitter in the US state of Massachusetts broadcast a quarter-hour of singing by his wife, a violin solo and quotations from the Bible.

The first commercial radio station began regular operation in 1920 in Pittsburgh, USA.