Maritime circular SAR processing issues: Antenna pattern verification, sea-clutter analysis & ship image autofocus

Abstract:
During two SAR acquisition campaigns in 2015 and 2017, several circular SAR acquisitions have been performed on sea surface and ships. The 2015 set is full polarimetric acquisition at both X & L band (8 channels with 300 & 150 MHz bandwidth each). The 2017 set is vertical polarisation at X band (two channels with 2 GHz bandwidth each). Several processing issues had to be addressed with these experiments: - Simultaneous antenna pattern & sea clutter backscatter table evaluation was required because of antenna pattern compensation abnomalies at X band. - The autofocus used above ground was useless on the moving sea surface, hence the ships images required autofocus with tiepoints on the ship itself to compensate her own motion. During the 2017 campaign, low resolution images were synthesised on board to assess correct target acquisition during flight.