A frequency autonomous retrodirective array transponder

Retrodirective arrays are able to radiate a signal in response to a signal transmitted by an interrogator back toward the transmitter position with no a priori knowledge of the arrival direction. We present a novel architecture that enables the retrodirective array to respond to an interrogator at the same transmitted frequency with no previous knowledge of the transmission frequency. The frequency agile prototype array shows excellent retrodirectivity at various frequencies.