An adaptive multi-functional array for wireless sensor systems

Smart antenna and retrodirective array technologies are combined to establish a reconfigurable phased array communication system. The array serves as a retrodirective transponder with a LO frequency at 11.6 GHz. By changing the LO frequency to 2.9 GHz, the array can be reconfigured to a smart antenna enabling multi-user communications. The retrodirective transponder provides 20 dB circuit gain and 20 dB RF-IF Isolation exhibiting excellent retrodirectivity. When operating as a smart antenna, the receiver array successfully demodulates a QPSK modulated signal with circuit gain of 7 dB and E/sub b//N/sub 0/ for BER=10/sup -4/ is approximately 12 dB without any error correction. In the retrodirective array mode, the system provides 20 dB.