Amplitude distribution of composite terrain radar clutter and the K-distribution

A novel class of probability distributions resulting from a compound Poisson process is found to correlate well with amplitude distributions of radar clutter returns spatially sampled from composite terrain. This class of distributions, derived from assumptions of random scattering phase and Poisson spatial distribution of elementary scattering sources, is specified by several physical and statistical parameters in its complete generality. These parameters are: (1) the number of scatterer types; (2) the average radar scattering cross section and the cross-sectional distribution of each different scatterer type; (3) the occurrence probability or the average scatterer size and spatial density; (4) the radar resolution area; and (5) the average background radiation as well as the radar internal noise power. Excellent fits of the theoretical clutter distributions to the measurement data are obtained by assuming a Rayleigh amplitude distribution for the elementary scatterer return for high grazing angle cases and a more general K-distribution for low grazing angle cases.