斜入射下电离层闪烁对GEO SAR成像影响分析

Analysis of Ionospheric Scintillation Impacts on GEO SAR Focusing

本文基于多相位屏理论,研究了电离层闪烁对GEO SAR成像的影响。首先针对电离层各向异性的特点,修正了各向异性电子密度起伏的功率谱,并重新推导了斜入射条件下随机介质中的电磁波传播方程,改进了传统的基于垂直入射和各向同性电离层条件下的多相屏仿真方法,然后结合典型GEO SAR参数,分析了电离层闪烁对GEO SAR成像的影响。最后,通过Monte Carlo仿真,给出了不同电离层电子密度起伏条件下GEO SAR进行合成孔径处理的最优积累时间。分析结果表明,相同GEO SAR系统配置下,电离层闪烁的起伏越大,合成时间越长,GEO SAR成像质量越差,甚至会出现无法聚焦的情况。

The paper studies ionospheric scintillation impacts on GEO SAR focusing based on multiple phase screen （MPS）simulations.The power spectrum of electron irregularities is modified according to the anisotropic ionosphere.In the case of the oblique incidence,the electromagnetic wave equations in random medium are derived,and then the MPS simulations are realized.After the simulation of GEO SAR imaging,the effects of the random fluctuations are analyzed.Fi-nally,the optimized integration time under different scintillation conditions are proposed through Monte Carlo simulations. The paper concludes that the greater ionospheric fluctuations and longer integration time will lead to more serious deteriora-tion in the same GEO SAR configuration;and even not focus at all for the worst case.