Co-polarized Retrodirective Array with Active Enhancement

Four-arm spirals are proposed for use in an active Van Atta array configuration with co-polarized simultaneous transmit and receive in mind. Retrodirective behavior is observed out to 60° at the analysis frequency with active circuit gain possible up to a limit, related to the transmit-receive coupling. Additionally, retrodirection generally increases at a faster rate than specular reflection as circuit gain is increased.