Polarimetric Calibration of RISAT-1 Compact-Pol Data

Abstract

India's radar imaging satellite RISAT-1 was the first spaceborne SAR platform operated in the compact polarimetric (CP) mode, which posed several advantages compared to the commonly used quad-pol system architecture in terms of design complexity and data quality. But, to make use of the advantages offered by the compact polarimetry mode, the acquired datasets should be free from the system induced polarimetric distortions, which include the channel imbalances, phase bias, and crosstalk between the channels. In addition to these system induced errors, the ionosphere also induces polarimetric distortion to the datasets in terms of Faraday rotation. For accurate ground target characterization using the CP datasets, the polarimetric distortions should be estimated and minimized. This article focuses on the CP calibration of the RISAT-1 dataset using trihedral and dihedral corner reflectors deployed at the study area. The Cloude CP decomposition technique is used to assess the ground target characterization quality of the dataset before and after polarimetric calibration.