A system for generating a false target radar image for countering wideband synthetic aperture and inverse synthetic aperture imaging radar systems to prevent a selected target from being detected by such radar systems comprises a receiver system for producing a digital signal that represents an incident radar signal. A phase sampling circuit is connected to the receiver for sampling the digital signal and providing phase sample data. An image synthesizer circuit is connected to the phase sampling circuit and arranged to receive the phase sample data therefrom. The digital image synthesizer circuit is arranged to process the phase sample data to form a false target signal, which is input to a signal transmitter system arranged to transmit the synthesized false target signal so that it can be received by a radar system.