基于极化定标的极化隔离度空变分析

Analysis of Polarization Isolation Spatial Variation Based on Polarimetric Calibration

极化定标是多极化合成孔径雷达(PolSAR)系统获取真实目标极化散射矩阵的必要步骤。文中针对极化定标过程中存在的极化隔离度距离向空变特性,采用基于无源角反射器的极化定标算法作为仿真工具,对PolSAR系统极化隔离度绝对值及其空变范围对图像中极化隔离度的影响规律进行了分析。分析结果表明:当用于极化修正的极化误差矩阵与PolSAR系统自身极化隔离度不匹配时,极化修正将会使得修正后的图像极化隔离度变差。因此,在进行极化定标时,应当尽可能在定标场沿距离向布设一定间距的多组定标器,从而获取PolSAR系统在整个距离向成像带宽内的极化隔离度拟合曲线,在进行极化修正时对图像中距离向不同的像素点采用曲线中对应位置的极化误差矩阵进行修正,进而得到尽可能接近目标真实极化散射矩阵的估计值。

Polarimetric calibration is a necessary step for obtaining real target polarimetric scattering matrix by polarimetric synthetic aperture radar(PolSAR) system. In this paper,the impact of polarization isolation and its spatial variation to PolSAR image has been developed and analyzed with polarimetric calibration using passive corner reflectors. The results show that the polarization isolation in PolSAR image could be worse under the not suitable polarimetric calibration parameters. Thus multi groups of corner reflectors should be layout along the range direction to get the fitting curve of polarization isolation of PolSAR system. Then,this fitting curve should be used for polarimetric calibration of different targets in PolSAR image,to obtain the estimated polarimetric scattering matrices of targets accuratly.