Statistical properties of the phase difference between two orthogonally polarized SAR signals

The theoretical behavior of two linearly polarized (VV and HH polarization states) radar backscattered fields is examined from a statistical point of view. The coherency between two polarized signals is studied in terms of the statistical behavior of the phase difference between two signals. The probability density function (PDF) corresponding to the phase difference between two signals is derived and studied in terms of the degree of polarization and the variance of each polarized signal. The phase difference PDF is then considered with respect to the polarimetric synthetic aperture radar (SAR) data collected over rugged terrain and the ocean. It is found that the phase coherency between two copolarized channels (VV and HH polarizations) strongly depends upon the degree of terrain roughness structure