This book discusses and analyse the use of P band SAR observations with emphasis on the Faraday rotation of the plane of radio wave traveling in the ionosphere. Forest biomass and other earth parameters can be retrieved using SAR data. Faraday rotation effects must be calibrated towards the generalization of biomass retrieval for varied forest and environmental conditions. To this aim, we developed experimental and theoretical approaches allowing the understanding of the system models and simulation that allows the study of Faraday rotation angle. The FR angle, channel imbalance and crosstalk are successively derived by using the measured scattering matrices from the active and passive calibrators. The formula derivation procedure and data processing scheme are presented. The computer simulations and numerical studies in terms of the typical FR angle and system error values are presented to illustrate and compare the performance of the calibration approaches.