The invention relates to the field of radar for the detection and location of targets. All radar devices require a source of radio frequency energy to provide illumination of targets and a sensor of radio frequency energy to detect echo signals scattered by the targets. In prior devices, called active radar systems, the source of RF energy for target illumination; i.e., the transmitter, is closely associated with and constitutes an integral part of the overall radar system. One of the major problems with active systems is that, by transmitting, they reveal their own location.