Faraday Rotation Estimation from Unfocussed Raw Data: Analysis Using Alos Palsar Data

We propose to estimate Faraday rotation (FR) from SAR unfocussed raw data rather than focussed Single Look Complex (SLC) data. The main issue of the previous approaches presented in literature is the inherent averaging of the FR angle with the focussing process. This averaging might lead to wrong estimation of FR especially in the case of rapid spatial variation of Total Electron Content (TEC) in the ionosphere. The presence of nonlinear operations in the SAR processor is a second issue that might affect the FR estimation from SLC data. We show the comparison between the two approaches using ALOS-PALSAR data and the ESA PALSAR verification processor.