Faraday rotation angle estimation from polarimetric covariance matrix

Spaceborne Polarimetric SAR data operated at lower frequencies (L, P band) are subjected to Faraday rotation (FR) effects. FR estimators based on polarimetric SAR data are studied. Accuracy and stableness of the FR estimators are analysed theoretically under effects of additive noise. The results show that FRA estimated by Freeman´s second estimator tends to be biased from the true FRA. Performances of the estimators are related to combined components of the true PCM. FR estimator performs more stable when amplitude of PCM components related to the estimator is higher. The estimators and theory analysis are validated by FR estimation from PALSAR polarimetric data.