Focusing Spotlight-Mode Bistatic GEO SAR With a Stationary Receiver Using Time-Doppler Resampling

Bistatic geosynchronous synthetic aperture radar (GEO SAR) system, with a geosynchronous illuminator and a stationary ground receiver, provides capability and flexibility of continuous observation and frequent revisit over certain area, which is of great significance for applications such as disaster monitoring. The Doppler frequency modulation (FM) rate in this configuration, however, varies along the azimuth direction, which increases difficulty in imaging. To equalize the Doppler FM rate, a new imaging method is proposed in this paper. By conducting time-Doppler resampling, the proposed method can remove the quadratic variance of Doppler FM rate at orbital positions where the Doppler FM rate is around zero. Validation results show that the proposed algorithm provides a better focusing quality compared with existing methods.

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