Terahertz Wave Scattering by Rough Surfaces including Higher Moments: Ray-Tracing Developments

The most common analytical model used in raytracing to estimate the scattered field by a random rough surface is the Kirchhoff approximation, where a normal distribution of the surface heights is assumed. When approximating the non-Gaussian surface roughness with a Gaussian distribution, the high peaks and valleys cause an overestimation of the heights’ standard deviation and yields to inaccurate valuation of the coherent component of specular reflection. In this work, for an accurate scattering modeling of a non-line-of-sight (NLOS) propagation scenario, a curve fitting method is applied to calculate the effective roughness from non-Gaussian surfaces and then implemented in a self-programmed three-dimensional ray-tracer. When considering the third moments of the heights distribution, a deviation of (0 – 3.5) dB is observed in the scattering power depending on the material roughness.