Polarisation-diversity phase-encoded patch-antenna transponder

Application of phase encoding to a received RF signal, and retransmission of the signal phase encoded at the same frequency using polarisation diversity, is used to design a simple two-port microstrip patch antenna which will permit single-frequency polarisation-diversity operation. The antenna is characterised in terms of its far-field radiation pattern and its two-port parameters. An injection-locked is coupled to an adapted passive quasicirculator to perform the phase-encoding function. Here control of the direct tuning voltage to the injection-locked oscillator effects the degree of phase change obtained. The operation of this circuit is discussed and its inclusion with the dual-port patch antenna to form a phase-encoding transponder is described.