An Azimuth Ambiguity Suppression Method without Resolution Degradation

Azimuth ambiguity is caused by the combination of antenna sidelobe and finite azimuth sampling, which seriously influences the synthetic aperture radar (SAR) image quality and application. Current suppression methods have been designed at the cost of resolution loss mostly. Therefore, an ambiguity suppression method without resolution degradation is proposed, and the core is employing ambiguity refocusing and threshold segmentation. Firstly, an accurate analytical model of azimuth ambiguity is established to provide theoretical basis for ambiguity refocusing. Secondly, by taking advantage of the entropy difference before and after refocusing, ambiguity area detection is accomplished. Finally, the ambiguity energy in obtained detection area is eliminated by threshold segmentation and amplitude suppression. The presented approach is verified by both simulation results and Chinese LJ2-01 satellite.