A monopulse radar comprising a pilot signal generator (20) for injecting phase and amplitude-defined pilot signals into the separate receiving channels (6-12, 3, 16-19) to obtain correction signals through the variation in the mutual phase and amplitude relationship between the separate receiving channels for correcting angle error signals derived from target return signals. The pilot signal generator (20) and the transmitter (1) are tunable and a control circuit is incorporated for adapting the pilot signal generator (20) relative to the frequency of the target return signals.