Multifunction Radio Frequency Photonic Array With Beam-Space Down-Converting Receiver

A multifunction photonic beam-space array processor is shown to generate the beam space of an X-band array. Subsequent down-conversion of desired beams is performed via introduction of an optical local oscillator and high-speed photodetectors at the processor output. A separate optical path is used to “image” the full field of view of the input array for real-time angle-of-arrival estimation. Finally, experimental results showing simultaneous processing of output beams for a radar waveform and an in-band communications signal are presented. The recovery of a 10-MHz bandwidth, quaternary phase-shift keying communications signal with a nominal error vector magnitude of 15.5% is performed via a vector signal analyzer, whereas a custom digital beam-space beam-forming processor is shown to process the same beam data to recover a 100-MHz chirp radar waveform while simultaneously canceling the in-band communications signal by approximately 20 dB via an adaptive spatial null.