Effect of Faraday rotation on polarimetric SAR

The effect of ionospheric Faraday rotation on polarimetric synthetic aperture radar (SAR) imagery is evaluated theoretically. Faraday rotation is readily included in the polarimetric SAR system equation describing the received signal if the rotation angle is assumed constant over the synthetic aperture length. Deviations from a constant rotation angle over this length impact the validity of the derived system equation, but an explicit evaluation shows such effects to be negligible for most expected ionospheric conditions. The modified system equation provides a basis for calibration techniques that can be used to either remove or measure Faraday rotation effects in SAR imagery.