New Faraday Rotation Estimators Based on Polarimetric Covariance Matrix

Spaceborne synthetic aperture radar (SAR) systems operating at lower frequencies, such as P-band, are significantly affected by Faraday rotation (FR). FR angle (FRA) estimation is affected by additive noise, system imbalance, and cross-talk. Two new FRA estimators are proposed from linearly polarized covariance matrix data. Assumptions of these estimators are looser than reciprocity of the true scattering matrix, which is assumed for all the pre-existing estimators. The new estimators are validated by ALOS PALSAR full-pol data processing. Simulation results show that one of the new methods is sensitive to system amplitude imbalance, but possesses particularly high robustness to system phase imbalance. Hence, the proposed estimators can be candidates for FRA estimation according to the type and magnitude of the errors.