A novel single wideband retroreflector is disclosed that eliminates the need for a local oscillator and a local transmitter. The wideband retroreflector of the present invention comprises an antenna, a circulator, and a mixer. An externally produced continuous wave radio wave transmission within the microwave-millimeter wave frequency band is modulated with a wideband signal with a minimum operating instantaneous bandwidth of 5 KHz-500 MHz and retransmitted as a modulated waveform by the antenna.