Improved motion compensation approach for squint airborne SAR

Airborne synthetic aperture radar (SAR) raw data are affected by motion errors due to atmospheric turbulence and aircraft properties, and this makes motion compensation (MOCO) an essential step. In order to decrease the influence of variable motion information, a kind of MOCO approach called azimuth-subaperture processing is widely used, which causes the azimuth-signal aliasing in squint SAR mode. Usually, this aliasing can be ignored, since its effect on final results is not worth mentioning. However, when the squint angle grows, it becomes serious and drops the quality of final images severely. To address this problem, an improved MOCO approach is proposed in this paper. Its main idea is to calculate the extended number of subapertures and eliminate the azimuth aliasing by extending the subaperture length. After theoretic analyses, simulations and experimental results are provided to demonstrate our proposed approach.