ANSYS, Inc.
Rough Surface Model for Shooting and Bouncing Rays

Abstract:

A method is disclosed for augmenting the SBR model used in EM field simulation by modeling the specular coherent and diffuse incoherent components of the field scattered by rough surfaces using statistical characteristics of surface roughness. For each projected ray-tube footprint, the magnitude of the coherent radiated field is attenuated with a scalar factor, while the incoherent radiated field is modulated by a random magnitude and phase. Both corrections are based on the statistical characteristics of surface roughness. Multiplying the incoherent field with a randomly generated phase renders it in a mathematically coherent form, which allows the method to generate a statistically viable instance of the total (i.e. coherent plus incoherent) field scattered by a rough surface. The results reproduce the field and power statistics (i.e. mean and variance) observed from direct SBR simulations using an ensemble of explicitly rendered rough surface geometry models, with a significant reduction in computation.