一种基于有源定标器的电离层对星载SAR定标影响校正方法

An Approach for Ionospheric Effects Correction on Spaceborne SAR Calibration Based on Active Radar Calibrator

针对电离层对低频星载合成孔径雷达(Synthetic Aperture Radar,SAR)定标的影响,该文提出一种基于有源定标器的电离层对星载SAR定标影响校正方法,主要针对由电离层群延时导致的距离向位置偏移和由电离层色散效应引起的脉冲展宽所导致的分辨率下降进行了分析,利用SAR内外定标相结合的方法,精确测量出电离层引起的脉冲时间宽度变化量,利用测量结果对电离层的影响进行校正。给出校正前后以及无电离层影响的有源定标器距离向成像仿真结果,结果表明通过校正可以很大程度上改善有源定标器距离向点目标图像质量,提高了定标测量精度,验证了校正方法的正确性。

For low frequency spaceborne Synthetic Aperture Radar（SAR） systems,the ionosphere will have a significant effect on SAR calibration.In this paper,an approach for ionospheric effects correction on spaceborne SAR calibration based on Active Radar Calibrator（ARC） is proposed.The range-displacement induced by ionosphere group delay and the degradation of the range resolution resulted from ionosphere dispersion effect are analyzed,and the effects are corrected by using the width change of the transmitted pulse measured by internal calibration and ARC.The imaging results of ARC before and after correction from simulation are presented.The results show that image quality in range is improved greatly after correction and the approach is proved to be valid.