Image formation from squinted sliding spotlight synthetic aperture radar (SAR) is limited by azimuth spectral folding and severe two dimension coupling. This paper presents an Extended Wavenumber Domain Algorithm (WDA) for highly squinted sliding spotlight SAR data processing. This algorithm adopts azimuth deramping approach to overcome the azimuth spectral folding phenomenon. The chirp rate for azimuth deramping and the principle of choosing pulse repetition frequency (PRF) is presented to accommodate the characteristic of Doppler history. Subsequently, the full focusing is implemented by WDA. Instead of the conventional Stolt mapping in WDA, a modified Stolt mapping is introduced in order to enlarge the range extension of focused image and enable to update the Doppler parameters along range. To confirm the correctness of the implementation of modified Stolt mapping and the azimuth position of target in focused image, related compensation terms are developed. Point target simulation results are presented to validate the effectiveness of extended WDA to process highly squinted sliding spotlight SAR data.
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