Abstract: A radar system with an array antenna includes various signal paths, including beamformers, extending between an exciter, a receiver, and the array antenna. The signal paths are calibrated by a method that includes frequency modulation of the exciter signals that reach the “antenna” and additional amplitude modulation of signals just as they enter the receiver. Leakage paths directly from the exciter to the receiver are unmodulated, those extending from the exciter through the beamformer are amplitude modulated, and only those reaching the “antenna” and returning to the receiver are both amplitude and frequency modulated. The receiver is tuned to receive only the “doubly-modulated” signals, which tends to reject leakage signals.