Microwave amplitude limiter is a assembly used mainly for power regulation by which the signal will go through without attenuation at low power and will attenuate greatly when power goes up to a fixed level that is called as threshold level and the output power would keep stable even though the input power may continually increase beyond the threshold level.

Usually amplitude limiter can be used to protect power-sensitive parts from burnt by strong signal and also can be applied in microwave swept signal generator or phase detector to keep the output signal stable.