A PHEMT-Based Phase Conjugator for Full-Duplex Retrodirective Arrays

In this letter, a phase conjugator for full-duplex retrodirective arrays is presented. Properly controlling a PHEMT nonlinear behavior, the modulation of the phase conjugated retransmitted signal is assured without distorting the information contained in the amplified version of the received signal. By means of a balanced architecture, the interrogating and response components are obtained through two mutually isolated output ports, respectively connected to the demodulation unit and the orthogonal feed of the employed aperture coupled patch. Measured results demonstrate the phase conjugator performance in two operating modes: retransmission of a BPSK signal after reception of an amplitude modulated interrogation, or ASK response when the incoming excitation is angularly modulated.