Planar Active Rectrodirective Array With Subharmonic Phase Conjugation Mixers

A planar active retrodirective four-element array with subharmonic phase conjugation mixers based on anti-parallel diode pairs (APDPs) is proposed. As compared to previous phase conjugation mixers using twice RF frequency for LO frequency, the proposed conjugation mixers need only half RF frequency so that it can be easily applied for millimeter-wave applications. Receive, transmitting, local oscillator, and intermediate frequencies (fR, fT, fLO, and fIF,) are 5.79, 5.81, 2.9 GHz, and 10 MHz. Monostatic RCS and Bistatic RCS measurements at source locations of 0°, -20°, and 28° show good agreement with the calculated data.