A deramping based omega-k algorithm for wide scene spotlight SAR

Spotlight SAR accumulates large Doppler bandwidth to improve azimuth resolution. On condition of certain pulse reputation frequency (PRF), Doppler bandwidth accumulates at the cost of imaging scene. This is a classic tradeoff between azimuth resolution and scene size in spotlight mode. A novel algorithm is proposed here to break the restriction. Firstly, a deramping based method is presented through bulk data processing to finish azimuth Fourier transform under low PRF. Omega-k algorithm is then applied to focus the full image. This algorithm is free of classic restriction and requires PRF only larger than the instantaneous bandwidth. Its bulk data processing is efficiency with no sub-aperture or interpolation. In this case, this algorithm is qualified to wide scene spotlight SAR imaging. The effectiveness of this algorithm is demonstrated by point target simulation.