A Brief History of Radio

Fessenden (1902); Majorana (1904); Fleming (1906); Pickard and Dunwoody (1906); De Forest (1907); Barthelemy (1910); Sarnoff (1916); Black (1930);  Blaupunkt (1932); Bardeen, Brattain and Schockley (1948) and Sony (1955).

It was in 1887 that the German Heinrich Hertz discovered the waves which were named after him at first and which are now called radio waves.

They are between 6 mm and 10 km in wavelength. They carried telegraph signals with ease because the power could be increased, there was no need for lines and their reception using a tuned aerial was easy. It was thought therefore that before the end of the 19th century it would be possible to use radio waves to carry electrical signals converted into sounds, such as the human voice, but the realization of the idea appeared impossible due to their very low frequency. The plan was not abandoned however.

Right at the beginning of the 20th century several technicians proposed to make use of waves of very high frequency and power but, with variable amplitude,  the sound signals would modify one of the parameters of the wave, either its frequency or its amplitude. This brilliant principle is the one which is now employed in amplitude modulation and frequency modulation: at the time it made reception rather difficult, for it required considerable power transmission, without which virtually nothing could be heard.

Due to the dispersion of radio waves, a 50 kilowatt transmitter could only produce a few microwatts at reception. Moreover, the modulation technique had not yet been established.

The first to have the idea of the modulation process was the Canadian-born Reginald Aubrey Fessenden. In 1902 he experimented with frequency modulation using an Anderson alternator winch transformed mechanical movement into electrical energy with the help of the vibrations of a microphone cooled by water.

Following this principle, Fessenden erected identical 420-foot high transmitter/receiver masts at Brant Rock, Massachusetts and at Machrihanish, near The Mull of Kintyre in Scotland, in 1905 and succeeded not only in sending continuous streams of Morse code signals between the two stations in early 1906 but too,  in November 1906,  also succeeded in repeatedly sending speech transmissions (later found to be travelling right round The World) between the two continents.

Fessenden made The World's first ever 'public broadcast' on Christmas Eve 1906. Three days before his now famous 'broadcast',  Fessenden had his operators notify all the ships of The U.S. Navy and of The United Fruit Co. that were equipped with the Fessenden apparatus that it was the intention of the Brant Rock Station to broadcast speech, music and singing on Christmas Eve.

Transmitting from Brant Rock in Massachusetts, on a frequency of 50 kHz [kilohertz] with a power of 1 kilowatt, he put two musical tunes, a poem and a talk on the air which were heard by radio operators several hundred kilometres away,  one ship off the equally now famous Guantanamo Bay in Cuba.

At the end of his Christmas Eve 'broadcast',  Fessenden scored another couple of 'world-firsts' by announcing that he would repeat everything he had done that night at the same time on New Year's Eve of 1906, thus the first ever 'radio advertisement' and the first ever 'repeat' programme,  albeit another live 'broadcast'.

Among other attempts at frequency modulation, that of the celebrated Italian physicist Enrico Majorana must be mentioned.

In 1904 he managed to obtain modulations from the displacement of air by the human voice. But the modulations were too weak and the reception much too faulty for the radio to provide an effective means of communication.

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