时变大气层效应对地球同步轨道SAR成像影响的分析与补偿

大气层效应会导致穿过其中的星载SAR信号产生相位误差，并进而可能造成星载SAR成像结果出现散焦现象。大气层效应包括背景电离层效应、电离层多重散射效应以及对流层效应，由于GEO SAR合成孔径时间可达几百秒量级，因此在其成像积累时间内大气层效应会随时间变化，因此必须考虑时变大气层效应对GEO SAR成像的影响，同时亟需研究时变大气层效应对GEO SAR成像影响的补偿方法。本文详细分析了时变大气层效应对SAR信号的影响机理，建立了时变大气层效应影响下的高精度GEO SAR回波信号模型，分析了时变大气层效应对GEO SAR成像的影响，并基于方位向子孔径划分，通过提取时变大气层相位误差，对大气层效应造成的GEO SAR图像散焦现象进行了补偿。 

Atmosphere Effects on Geosynchronous SAR: Theoretical Analysis and Compensation Method

Atmosphere would bring phase error to the SAR signal traversed therein, and further lead to defocusing phenomenon in the SAR imaging results. The effects of atmosphere include background ionosphere, multiple scattering in turbulent ionosphere and troposphere. Due to Geosynchronous SAR (GEO SAR) has an integration time up to the order of a few hundred seconds, thus the atmosphere within the integration time will varies with the integration time, and it should take the effects of the temporal-variation atmosphere on GEO SAR imaging into consideration. Meanwhile, it needs urgently to research the compensation method of the effects of the temporal-variation atmosphere on GEO SAR imaging. In this paper, it has analyzed the impact mechanism of temporal-variation atmosphere on GEO SAR signal, and established the GEO SAR accurate signal model under the influence of the temporal-variation atmosphere. Then, based on this model, it has analyzed the effects of atmosphere on the GEO SAR range and azimuth imaging. Finally, based on the subaperture partition in azimuth and phase error extracting, it has compensated the GEO SAR imaging defocusing phenomenon caused by atmosphere.