Abstract:

Because of the long synthetic aperture time for the spaceborne synthetic aperture radar (SAR) in the case of high resolution, the effects of acceleration are considerable, and the traditional algorithms would be failed. Based on the acceleration model, the spacevariant of spaceborne SAR in curved flight path is analyzed, and an azimuth frequency domain nonlinear chirp scaling method is proposed to process the case of large scene and high resolution. Firstly, an azimuth polynomial phase filter is constructed to make the coefficients of the perturbation function has sufficient flexibility to eliminate the spatialvariant couple terms between range and azimuth. Then, the traditional twostep method is modified, which is more applicable to the curved flight path. Finally, the gradient operation is used to expand the spacevariant coefficients of azimuth modulation term, and the perturbation function is applied to eliminate the spacevariant in azimuth direction. The simulation results verify the effectiveness of the proposed imaging approach.