电离层不规则体对P波段星载SAR成像的影响

Effects of ionospheric irregularities on spaceborne P band SAR imaging

电离层不规则体导致星载合成孔径雷达(SAR)信号产生幅度及相位闪烁,严重影响低波段星载SAR的图像分辨性能。推导了具有普遍性的幂律谱对应的双频双点互相关函数。基于此研究了电离层对星载P波段SAR分辨性能的影响及其规律。研究表明,电离层不规则体导致星载P波段SAR两维分辨率恶化,图像峰值增益损失严重。电离层不规则体强度,谱指数,外尺度等参数的增大都会导致星载SAR图像分辨率及峰值增益进一步下降。基于相位屏技术的数值仿真结果验证了本文研究。

Spacebome SAR imaging at lower frequencies such as P/UHF/VHF band is severely affected by ionospheric irregularities induced signal scintillation. Mutual coherence function of signals penetrating through the ionosphere was deduced. Electron density in the ionosphere was modeled by Rinog power density function. Patterns were studied that how spaeebome P band SAR image performances varies with parameters of ionospheric irregularities. The study shows that irregularities in ionospheric will defocus the image, causing considerable gain loss of the imaging. Increases in irregularity strength parameter CkL, outer scale Lo, and index of the power density function will further degrade the image. The study is validated by numerical simulation based on phase screen technique.