A Method of Residual Spatially Variant Phase Error in Compensation for Airborne Curved Trajectory SAR Based on RAA

QIU Feng; SHEN Ruina; DU Wangwang; TANG Shiyang

doi:10.3969/j.issn.2097-1915.2026.01.008

Abstract：The highly-squinted airborne synthetic aperture radar(SAR)with curved trajectory has signifi-cant potential in applications characterized by disaster monitoring and resource exploration due to its flexi-ble flight and wide-area coverage.However,the significant spatially variant phase errors are introduced by large squint angle,leading to severe defocusing or even imaging failure at the scene edges when the tradi-tional imaging algorithms are employed.For this reason,a method of residual spatially variant phase error in compensation for airborne curved trajectory SAR based on the radius/angle algorithm(RAA)is pro-posed.First,an accurate model of residual spatially variant phase error is established,and its spatial distri-bution characteristics are deeply analyzed,and then,the analytical expression of the residual phase error in the spatial frequency domain is derived,and a simple and efficient spatially variant phase error compensa-tion filter is designed by establishing a mapping relationship between the slow-time domain and the spatial frequency domain.The filter operates in the spatial frequency domain by using a block-wise processing strategy,effectively eliminating the spatially variant phase errors caused by the curved trajectory and large squint angle.Compared with the traditional algorithms,this proposed method significantly improves ima-ging quality at the scene edges while maintaining low computational complexity.The simulation and exper-imental results show that the phenomenon of azimuth defocusing at edge point targets is significantly sup-pressed,and the image resolution,the peak sidelobe ratio,and the integrated sidelobe ratio are still more close to the theoretical values,enabling the wide-swath imaging under large squint conditions.