对流层对地球同步轨道SAR成像的影响研究

地球同步轨道SAR（GEO SAR）具有超长孔径时间和大覆盖范围的特性，使得传统低轨SAR成像中采用的对流层冻结模型假设失效。因此，需要考虑时变条件下的对流层效应对GEO SAR成像的影响。本文根据对流层中电磁波的传播规律，利用射线描迹法，分析了GEO SAR中相位误差的特点；并通过建立时变对流层影响下的GEO SAR回波信号模型，研究了对流层引起的GEO SAR图像偏移及图像散焦现象，并分析总结了相关影响的边界条件。最后，基于仿真数据，分析了对流层效应对GEOSAR成像的影响。 

Analysis of Troposphere Impacts on Geosynchronous SAR Imaging

Due to the ultra-long aperture time and large coverage characteristics of Geosynchronous Synthetic Aperture Radar (GEO SAR), the troposphere freezing model in the traditional Low Earth Orbit SAR (LEO SAR) imaging is assumed to fail in the GEO SAR, thus it should take the effects of the temporal variation troposphere on the GEO SAR imaging into account. In this paper, the phase error introduced by the troposphere was analyzed by using the ray tracing method. Concurrently, through the establishment of a GEO SAR signal model under the influence of temporal variation troposphere, it has probed into the GEO SAR two-dimensional image shift and image defocusing phenomena caused by the troposphere, as well as analyzed and summarized the boundary conditions of relevant effects. Finally, the imaging results of GEO SAR under the effect of troposphere were obtained based on simulation parameters.