A retrodirective transponder with polarization duplexing for dedicated short-range communications

This paper presents a microwave active transponder using a two-port cross-s haped microstrip antenna, The linearly polarized held coming from an interr ogating signal is received by the first port, amplified and used as the loc king signal of a local oscillator. The output signal of this oscillator is radiated with an orthogonal polarization by the second port of the same ant enna. Two transponders are then connected in a Van Atta array arrangement t o provide a retrodirective function, This type of array can be built at low cost and find application in short-range communications for vehicular syst ems.