2D phase-conjugated retrodirective array with information carrying capability

A new two-dimensional (2D) phase-conjugated retrodirective array with star-shaped antenna elements is proposed. The phase conjugators provide high isolation of -48 dB between RF and IF ports when RF/IF signals share the same ports in a balanced hybrid. By on-off keying modulation of the local oscillator (LO), the new 2D phase-conjugated retrodirective array can reflect the signal back to the interrogator with the modulation signal carried on it for information exchange. Experimental results show that this array can achieve 2D retrodirectivity within 120deg angle of wide scan range at arbitrary signal polarisation and injection direction