Analysis and Correction of Antenna Pattern Effects in AMAO Spaceborne SAR Images

Azimuthal multi-angle observation (AMAO) is a novel spaceborne synthetic aperture radar (SAR) technique proposed recently, which significantly improves the acquisition performance of target information. It has highly flexible antenna beams with powerful beam-steering capability while affecting the consistency of radiometric measurements, especially in the high-squint case. This paper mainly focuses on the antenna pattern effect analysis and correction method of AMAO spaceborne SAR. The antenna pattern characteristics of the squint steering beam are first analyzed. On this basis, an analytical model is developed to quantify the antenna pattern effects in AMAO SAR images. Different from the conventional approach that corrects the elevation antenna pattern, an improved antenna pattern correction method, which accounts for the spatial variation in the two-dimensional antenna pattern, is then proposed for AMAO spaceborne SAR. Finally, experiments are conducted to verify the proposed correction method. The results show that the newly proposed method considering the spatial-variant antenna pattern has higher performance than the conventional approach using a reference elevation pattern.