Correlation Effect Between Transmitter and Receiver Azimuthal Directions on the Illumination Function from a Random Rough

The resolution of some problems of electromagnetic scattering from random rough surfaces implies the derivation of the illumination function, especially when the geometrical optics approximation is valid. In current models, the shadowing effects occurring for both the trans-mitter and the receiver are assumed to be independent of their azimuthal directions. This assumption makes it possible to compute separately the shadowing probabilities in each di-rection. However, if the transmitter and receiver azimuthal directions are close, these proba-bilities become strongly correlated. In such a configuration, the uncorrelation approximation induces an overestimation of the average illumination function up to 10 % as well as a dis-continuity. In this paper, assuming surfaces of isotropic Gaussian statistics with independent heights and slopes, this correlation is taken into account. Comparisons of our model with Monte Carlo simulations are made and show a very good agreement, which validates our approach. 1