The polarimetric distortion in the PolSAR datasets causes the polarimetric decomposition and classification techniques to produce wrong outputs, which result in misinterpreting the scattering phenomenon and the ground targets. The most important polarimetric distortions in airborne PolSAR datasets are the channel imbalance and crosstalk. The minimization of these polarimetric distortions using polarimetric calibration techniques is very important to carry out the quantitative analysis using PolSAR data and time-series analysis and to compare the results between different sensors. The objective of this study was to implement the external polarimetric calibration of the L-band UAVSAR system using trihedral corner reflectors. The polarimetric distortion matrix (PDM) was formulated after considering the crosstalk and channel imbalance polarimetric distortions to derive the scattering matrix free from all kinds of polarimetric distortions from the observed scattering matrix. The channel imbalance between different polarization channels was estimated with the help of trihedral corner reflectors and homogeneously distributed targets. The crosstalk parameters were estimated by assuming the scattering reciprocity constraint, which is valid in the case of monostatic radars. The scattering matrix free from polarimetric distortions was derived from the PDM after estimating the polarimetric distortions. The polarimetric signatures and the coherency matrix behaviour of the trihedral corner reflectors were used to analyse the ground target characterization improvement after polarimetric calibration.

中文翻译：

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L波段UAVSAR数据的极化校准

PolSAR 数据集中的极化失真导致极化分解和分类技术产生错误的输出，从而导致对散射现象和地面目标的误解。机载 PolSAR 数据集中最重要的极化失真是信道不平衡和串扰。使用极化校准技术最小化这些极化失真对于使用 PolSAR 数据和时间序列分析进行定量分析以及比较不同传感器之间的结果非常重要。本研究的目的是使用三面角反射器对 L 波段 UAVSAR 系统进行外部极化校准。偏振失真矩阵 (PDM) 是在考虑串扰和信道不平衡偏振失真后制定的，以从观察到的散射矩阵中导出没有各种偏振失真的散射矩阵。借助三面角反射器和均匀分布的目标，估计不同偏振通道之间的通道不平衡。串扰参数是通过假设散射互易约束来估计的，这在单基地雷达的情况下是有效的。没有偏振失真的散射矩阵是在估计偏振失真后从 PDM 导出的。