An attenuator (French attenuer — to soften, to weaken) is a device for smoothly, stepwise, or fixedly reducing the intensity of electrical or electromagnetic oscillations.
An attenuator is an electronic device that reduces the amplitude or power of a signal without significantly distorting its waveform. In functional terms, an attenuator is the opposite of an amplifier, although these devices operate on different principles. While an amplifier increases signal strength, an attenuator provides signal attenuation.
Attenuators are generally passive devices made from networks of simple voltage dividers. Switching between different resistances forms adjustable step-type and continuously variable attenuators using potentiometers. For high frequencies, carefully tuned resistive circuits are employed to minimize the standing wave ratio (SWR).
Attenuators are used when a strong signal needs to be reduced to an acceptable level, for example, to avoid overloading a radio receiver's input with an excessively powerful signal. A useful side effect is that placing an attenuator between the line and the load can improve the traveling wave ratio and the standing wave ratio in the feed line when the load is poorly matched to the line.
When an attenuator is a separate device, it must be placed between the signal source and the load, interrupting the signal path. Additionally, its impedance (characteristic wave impedance) must match both the source and load impedance, thereby ensuring circuit matching.
Related articles: Semiconductors, Diode - definition, Potentiometer - definition, Transistor - definition, Comparator - definition
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