螺旋轨迹SAR极坐标格式算法研究

Polar Format Algorithm for Spiral Synthetic Aperture Radar

螺旋轨迹SAR作为更一般化的CSAR成像模式,减少了平台必须在同一高度平面的限制,提高了平台的机动能力,具有较高的研究价值。用于圆迹合成孔径雷达( Circular Synthetic Aperture Radar,CSAR )成像的极坐标格式算法( Polar Coordinate format Algorithm, PFA )通过两步相位补偿操作校正了波数二次相位误差,改善了平面波假设带来的成像场景大小限制。由于螺旋轨迹SAR其斜距一直在变化,其波数二次相位变得更加复杂并且难以补偿,本文算法首先对螺旋轨迹SAR回波数据进行距离向对齐,然后基于PFA算法中的两步补偿操作,建立了新的相位补偿函数以及补偿策略,精确补偿了螺旋轨迹几何成像中的波数二次相位误差,获得了较大的有效成像范围。最后,点目标仿真验证了算法的有效性。

As a more general CSAR imaging mode, spiral trajectory SAR reduces the limitation that the platform must be at the same height plane, improves the maneuverability of the platform, and has high research value. The Polar Coordinate Format Algorithm (PFA) for Circular Synthetic Aperture Radar (CSAR) imaging corrects the wavenumber quadratic phase error by a two-step phase compensation operation, which improves the imaging scene size limitation caused by the plane wave hypothesis. Since the slant range of the spiral trajectory SAR has been changing, the quadratic phase of the wave number becomes more complicated and difficult to compensate. The algorithm firstly aligns the spiral SAR echo data in a distance direction, and then based on the two-step compensation operation in the PFA algorithm. A new phase compensation function and compensation strategy are established, which accurately compensates the second-order phase error of the wave number in the geometric imaging of the spiral trajectory, and obtains a large effective imaging range. Finally, the point target simulation verifies the effectiveness of the algorithm.