Phase calibration of multibaseline SAR data based on a minimum entropy criterion

Prior to any processing of multibaseline (MB) synthetic aperture radar (SAR) data stacks, a MB phase calibration is necessary to compensate for phase contributions due to platform motions and/or atmospheric propagation delays. Classical calibration methods rely on the detection of point-like scatterers. However, especially in natural scenarios, their final calibration performance could be impaired by the nature of the scattering and by the typical low number of baselines. In this paper, we propose a calibration method based on the minimization of the entropy of the vertical profile of the backscattered power. This allows to potentially exploit the MB SAR signal independently of the nature of the scattering. The proposed method has been tested by processing simulated and real airborne datasets of a forest stand.