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In telecommunications, field strength meter is a measuring device which measures the signal strength caused by a transmitter. ==The relation between the electric field and the transmitted power== In ideal free space, the electric field strength produced by a transmitter with isotropic radiator is readily calculated.〔 ''Reference Data for Radio Engineers'', Howard W.Sams Co.Inc.,ISBN 0-672-21218-8, p 27-7〕 : where :E is the electric field strength in volts per meter :P is the transmitter power output in watts :d is the distance from the radiator in meters It is clear that electric field strength is inversely proportional to the distance between the transmitter and the receiver. However, this relation is impractical for calculating the field strength produced by terrestrial transmitters, where reflections and attenuation caused by objects around the transmitter or receiver may affect the electrical field strength considerably. ==Field strength meter== Field strength meter is actually a simple receiver. After a tuner circuit, the signal is detected and fed to a microammeter, which is scaled in dBų. The frequency range of the tuner is usually within the terrestrial broadcasting bands. Some FS meters can also receive satellite (TVRO and RRO) frequencies. Most modern FS meters have AF and VF circuits and can be used as standard receivers. Some FS meters are also equipped with printers to record received field strength. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Field strength meter」の詳細全文を読む スポンサード リンク
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