Impact of Ocean Wave Motion on SAR Imaging with Different Integration Times

The currently widely accepted theory of moving ocean waves SAR imaging is only valid when the synthetic aperture radar (SAR) integration time is short relative to the ocean wave period. To get clearer physical insight into the ocean wave SAR imaging mechanism, the effect of moving ocean waves on SAR imaging with the different integration time is analyzed in this paper. A formula characterizing the degradation of azimuth resolution is provided for short integration times. Due to the challenges associated with obtaining a closed-form expression for azimuth resolution degradation in the long integration times, the numerical simulation of ocean wave SAR imaging is carried out. Azimuth spectral width, spectral peak density and spectral peak-to-average ratio (PAR) are used to evaluate the contrast of ocean SAR images at different integration times. The results show that the longer the integration time, the blurrier the wave SAR image is, and the azimuthal resolution is degraded. However, the degraded azimuthal resolution is much smaller than the theoretical degradation of azimuth resolution under the assumption of uniform velocity motion. Furthermore, the correctness of the theory and simulation analysis in this paper is verified by airborne experimental data.