加速后向投影圆迹 SAR 成像方法

摘要

凭借多视角观测和高分辨成像的能力，圆迹合成孔径雷达（CSAR）受到了越来越多的关注。然而，特殊的运动轨迹和强烈的二维耦合给成像算法提出了挑战。以兼顾图像质量和运算效率为目标，本文提出了一种适用于 CSAR 成像的加速后向投影（EBP）算法。EBP 算法将整个合成孔径划分为若干子孔径，使用全局极坐标系重建每幅子图像。根据角域波数域和方位时域的对应关系，EBP 算法通过波数谱搬移实现波数谱融合，再经由二维逆傅里叶变换实现图像聚焦。EBP 算法继承了后向投影（BP）算法的精确性和运动补偿优势，避免了插值操作引起的图像质量损失。最后，通过仿真实验验证该方法的有效性。%Circular synthetic aperture radar (CSAR)wins fame for its ability of multi-aspect observation and high-resolu-tion imaging.However,special flight track and severe coupling challenge most imaging methods.To balance image quality and computational efficiency,we propose an expediting back-projection (EBP)for CSAR imaging.EBP works by dividing the full synthetic aperture into subapertures.Each subimage is formed onto the unified polar grid.Based on the relationship between azimuth time and angular wavenumber,EBP fuses subaperture spectrum together and obtains the reconstructed im-age followed by two-dimensional Fourier transform.Without interpolation-based fusion,EBP can decrease the loss of spec-trum.Moreover,EBP retains the advantages of back-projection (BP)algorithm,such as high percision and pefect motion compensation.Experiment based on simulated CSAR data validates the effectiveness of this proposed method.