Sidelobes and Ghost Targets Mitigation Technique for High-Resolution Forward-Looking MIMO-SAR

We propose and analyze an image reconstruction algorithm for high angular resolution with a forward-looking multiple-input multiple-output synthetic aperture radar (FL-MIMO-SAR). This algorithm achieves significant attenuation levels of the sidelobes (SL) and ghosts such as grating lobes (GL) and Doppler left-right ambiguity (DLRA). Aspects such as SAR image reconstruction, high SLs in SAR images, the formation of GLs, DLRA, and the overlapping between DLRA ghosts and nearby GLs are investigated. In addition, different imaging scenarios are simulated using a frequency-modulated continuous wave (FMCW) radar simulator and validated with real measurements using different time-division multiplexing MIMO FMCW radars. The simulation and experimental results show that the proposed algorithm manages to significantly enhance the SAR image by attenuating the SLs and canceling ghosts and ambiguities. Furthermore, the proposed algorithm results in true targets with narrower response patterns, which improves the detectability of targets in the SAR image.