Phase Statistics for Strong Scatterers in SAR Interferograms

In synthetic aperture radar interferometry, past studies of interferometric phase statistics are mainly based on the assumption that the interferogram cell size is much larger than the wavelength of the incident radiation and the scene is a homogeneously distributed scatterer. However, strong scatterers are often present in the scene, and in this work, the interferometric phase statistics are studied for this case for single-look interferograms. Its closed-form probability density function is first derived by approximating the complex interferogram signals to two correlated Gaussian random variables with nonzero-mean values. The closed-form mean value and variance are then derived with the assumption that the intensity of the strong scatterer is much larger than that of its background. It is shown that the phase statistics of strong scatterers are related not only to the correlation but also to the intensity of the dominant point and the phase difference variation between the dominant point and the remaining points.