大气折射会对无线电波造成射线弯曲和时延色散。对工作在微波频段的LEO-SAR而言,弯曲效应会导致雷达图像在距离上的偏移,而色散效应导致的二次相位误差会对接收信号造成脉冲展宽,使雷达图像分辨率降低,产生畸变。通过对这两种传播效应进行建模分析,选择电离层、对流层环境折射效应均较强的三亚地区进行折射指数剖面建模,仿真计算了该大气环境下,不同频段和轨道高度上LEO-SAR目标成像的距离向漂移和分辨率的变化,分析了大气折射引起的射线弯曲和时延色散特性对LEO-SAR成像质量的影响,为不同类型的LEO-SAR提供准确合理的折射误差修正补偿。

Atmospheric refraction can cause radio wave curved and time delay dispersion. For LEO-SAR worked at microwave frequencies, bend ray may lead to range shift of radar image, and dispersion may bring on secondary phase error which result in the extended pulse of received signals, and the range resolution of radar image may be reduced. These two propagation effects are modeled and analysed, and the refractive index profile in Sanya where have strong ionosphere and troposphere atmospheric refractive effect is chosen to evaluate the range shift and resolution of imaging with different frequencies and orbit height of LEO-SAR system, and the ray bend and time delay dispersion characteristics caused by atmospheric refraction is analysed, which can provide precise refractive errors correction for LEO-SAR imaging.

TN957.52

国家自然科学基金资助项目(41305024)