Imaging algorithm for squint sliding spotlight SAR operating in medium-earth-orbit based on polynomial and azimuth resampling method

doi:10.7523/j.ucas.2024.009

Abstract

Abstract: The medium-earth-orbit synthetic aperture radar (MEO SAR) possesses the capability of low-revisit cycle, high spatial resolution, and wide coverage, which has promising applications in both military and civilian fields. The MEO SAR can improve azimuth resolution by operating in sliding spotlight mode, and can enhance system flexibility through squint imaging mode. However, the increase of orbit height invalidates the assumption of azimuth invariance and the squint mode causes spectrum distortion. In this paper, first, we derive the calculation process of imaging parameters based on the polynomial signal model. Then, by introducing a new model fitting method and a deramp function, we extend the azimuth time-domain resampling method from the stripmap mode to the sliding spotlight mode, correcting the azimuth space-variant characteristics. We further propose a processing flow by combing the two-step method and the non-linear range walk correction to solve the spectrum aliasing in the squint sliding spotlight mode. Finally, the proposed method is verified through simulation experiments.

Key words: spaceborne SAR, MEO, azimuth resampling, sliding spotlight mode, squint

CLC Number:

TN957.52

GUO Yiqiong, REN Mingshan, ZHANG Heng, YUE Haixia. Imaging algorithm for squint sliding spotlight SAR operating in medium-earth-orbit based on polynomial and azimuth resampling method[J]. Journal of University of Chinese Academy of Sciences, DOI: 10.7523/j.ucas.2024.009.

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