电离层时空变化对中高轨SAR成像质量的影响分析

摘要

The Medium-Earth-Orbit SAR (MEOSAR) is one of the potential next-generation spaceborne SARs. Ionospheric effects analysis is one of the critical techniques for the development of MEOSAR. An analysis model for background ionospheric effect on MEOSAR is established based on the system characteristics of MEOSAR and the spatio-temporal variability of ionosphere. The degradation of image quality, including resolution and displacement distortion, induced by background ionosphere and its spatio-temporal variability is analyzed. The analysis result shows that ionosphere and its time-space variability affect critically the quality of obtained images. In condition of the same ionosphere, the degradation of resolution in both azimuth and range, the distortion on range image and the displacements in azimuth image are all more serious with the increasing of SAR orbit height when the resolution is same.%中高轨道合成孔径雷达(SAR)是下一代星载SAR重要的发展方向之一，电离层影响分析是推动中高轨道SAR系统发展的关键技术。该文针对中高轨道SAR的系统特点，结合电离层时空变化特征，建立了背景电离层对中高轨道 SAR 系统的影响分析模型，重点分析了背景电离层及其时空变化对中高轨 SAR 系统图像质量的影响，主要包括距离向和方位向图像分辨率的下降以及图像位移。分析结果表明，电离层及其时空变化对中高轨SAR图像质量产生较为严重的影响，相同电离层条件下，对于分辨率相同的SAR系统，随着轨道高度的增加，电离层引入的误差对距离向分辨率和图像畸变以及方位向分辨率和图像位移产生的影响程度将增大。