Field-trial Demonstration of a Broadband Microwave Photonic TDM-MIMO Radar

A microwave photonic time division multiplexing (TDM) multiple-input-multiple-output (MIMO) radar is demonstrated in which photonic frequency quadrupling is applied to generate broadband radar signals and photonic frequency mixing is applied to implement de-chirp processing of the radar echoes. To enable TDM transmission, a radio frequency switch is used to control the signal in different channels. In the receiver, an effective transceiver connection architecture based on multi-channel optical reference signals is adopted to realize the aliasing-free processing of all the radar echoes. Thanks to the wide radar bandwidth and large virtual aperture size, this microwave photonic TDM-MIMO radar is capable to realize high-resolution target imaging with deep suppression of grating lobes. Performance of the proposed microwave photonic TDM-MIMO radar is investigated through field-trial experiments, in which the established radar has a 6×8 linear antenna array and a bandwidth of 8 GHz (10-18 GHz) in each channel. Using broadband digital beamforming with scanning time delay compensation, high-resolution imaging of a reflector mounted on an unmanned aerial vehicle (UAV) is achieved. In the obtained image, the range resolution and angular resolution of the radar are estimated to be 1.95 cm and 0.2°, respectively, and the grating lobes are well suppressed because of the broadband angular dispersion effect.