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2-D Frequency Autofocus for Squint Spotlight SAR Imaging With Extended Omega-K

2021; Institute of Electrical and Electronics Engineers; Volume: 60; Linguagem: Inglês

10.1109/tgrs.2021.3092060

1558-0644

Hao Lin, Jianlai Chen, Mengdao Xing, Xiaoxiang Chen, Dong You, Guang‐Cai Sun,

Microwave Imaging and Scattering Analysis

In the existing time-domain autofocus algorithms, the azimuth deramping operation will change the azimuth-independent phase into the azimuth-dependent phase, which may greatly reduce the accuracy of autofocus processing in squint spotlight synthetic aperture radar (SAR). In contrast, the frequency-domain autofocus algorithms can avoid this problem because it does not involve the azimuth deramping operation. However, the existing frequency-domain autofocus algorithms are proposed based on the assumption of broadside mode, which cannot be directly applied to the squint mode. Therefore, this article extends the existing frequency-domain autofocus algorithm to the squint mode combined with the extended Omega-K (EOK) algorithm. Furthermore, a space division (SD) algorithm is embedded into the proposed algorithm as preprocessing, which can effectively compensate for the azimuth-dependent motion error. The simulation and real data are processed to verify the effectiveness of the algorithm.