Developments in the Utilization of Radiofrequency Radiation (RF)
The radio is generally perceived by the public in the context of radio broadcasts, and is less well-known from the broader aspect of radiofrequency (RF or radio waves). In general, the term radio embraces the means and technologies for transmitting and receiving information (e.g. sound and image) by means of radiofrequency radiation. The transmission of images is generally perceived as 'television broadcasts', although it too is achieved through radiofrequency radiation.
Used mainly in telecommunication, radiofrequency radiation is a part of the electromagnetic spectrum. The theoretical background for the existence of radiofrequency radiation was established by James Clark Maxwell, and was first made public as early as 1861. In 1873, Maxwell was the first to provide mathematical proof that electromagnetic waves could spread out (propagate) through space, even before their existence had been proven experimentally. It was only in 1880 that David Hughes first succeeded in transmitting sound through electromagnetic waves. However, the first to validate Maxwell's equations experimentally, during the years 1886-1888, was Heinrich Rudolf Hertz, after whom the unit of frequency of electromagnetic waves was named 'Hertz'.
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The first widespread use of RF radiation took off with the invention of the radio by Guglielmo Marconi, who successfully transmitted Morse code wirelessly across the Atlantic ocean, thus verifying Hertz's theory of the propagation of electromagnetic waves. During the first years of the 20th century, the radio became an accepted mode of transmission of news, information and music to the general public. |
Morse code transmission using telegraph |
The sources of RF radiation are both natural and artificial. Lightning and astronomical bodies, for example, are natural sources of RF radiation. Artificial sources of RF radiation have numerous uses, including TV and radio broadcasting stations, wireless transmitters and receivers, radar, navigation systems, communication satellites, communication networks, wireless internet, etc.
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Satellite dish receiving data signals for communication |
Military Radar Station |
The vast diversity of radiofrequency radiation sources necessitates regulation of the allocation of frequencies at the international, national and individual levels, in order to avoid problems of reciprocal interference between different sources of transmission. To this end, the International Telecommunications Union (ITU) was founded, and it is responsible for the organization and allocation of radiofrequencies.
References
- William BC. The history of power transmission by radio waves, microwave theory and techniques, IEEE Transactions 1984; 32:1230-1242
- Poole I. Basic radio: principles and technology. 1998; Newnes
- Barclay LW. Propagation of radio waves, 2nd Edition IET Electromagnetic Waves Series 502. 2003.
