Abstract: A microwave equalizer is used in aerospace applications to correct the gain/frequency response of a microwave system, in particular in a given range of temperatures. To obtain a variation opposite to that of the microwave system by introducing absorption at the operating frequency, it comprises at least one microwave coupler one branch of which has an active device fitted at each of its two ends so that variation in the device parameters enables displacement of the absorption frequency and optionally power. The coupler(s) are coupled to a transmission line of the system and a control circuit.