A method and an antenna arrangement are disclosed for reducing the antenna radar cross section for an externally illuminating radar source. A radar pulse is transmitted with the antenna arrangement fully matched to achieve lowest possible power loss of the pulse. At all other times the antenna will be poorly matched and thereby acting as a low radar cross section. The reduced radar cross section leads to an antenna gain reduction, which most often Can be accepted since competing noise is reduced as much as the useful signal. It is further suggested that the range gate of the receiver and the transmitter pulse control the antenna. Thus the antenna is 'fully opened' during the transmitting pulse and may be partly or 'trade-off' matched during range gate reception. In the interval of not transmitting or receiving the antenna will present a low radar cross section.