Radio frequency

Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around 20 kHz to around 300 GHz. This is roughly between the upper limit of audio frequencies and the lower limit of infrared frequencies; these are the frequencies at which energy from an oscillating current can radiate off a conductor into space as radio waves. Different sources specify different upper and lower bounds for the frequency range.

History

The discovery of radio waves can be attributed to James Clerk Maxwell, who in 1864 presented a theoretical framework for understanding electromagnetism. His mathematical theory, now called Maxwell's equations, predicted that a coupled electric and magnetic field could travel through space as an "electromagnetic wave". Maxwell proposed that light consisted of these waves, and so radio waves were first known as "Hertzian waves".

Applications

Radio frequency (RF) is used in various fields such as telecommunications, heating, and identification systems. RF is also used in medical treatments, for example, RF ablation is used in cardiology to remove problematic heart tissues.

Health effects

Exposure to RF fields above certain levels can result in harmful biological effects. The specific absorption rate (SAR) is a measure of the rate at which energy is absorbed by the human body when exposed to a radio frequency (RF) electromagnetic field.

See also

• Electromagnetic spectrum
• Electromagnetic radiation
• Radio wave
• Radio propagation
• Radio astronomy
• Radio frequency identification

Radio frequency

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  Spectrum
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  International Telecommunication Union ITU