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A Modified Beckmann-Kirchhoff Scattering Model for Slightly Rough Surfaces at Terahertz Frequencies

The diffuse reflection of electromagnetic waves is merely dependent on the surface roughness, incident angles, complex refractive index of materials and wavelength at hand. At terahertz frequencies, diffuse reflection tends to be particularly strong due to the increased surface roughness and this causes an additional attenuation even in the specular direction of reflection. In this paper, we examine the terahertz (THz) channel from 300 GHz (0.3 THz) to 310 GHz (0.31 THz) in the presence of slightly rough surfaces (0 < g ≪ 1) by using the approximate solutions from Rayleigh-Rice (R-R) and Beckmann-Kirchhoff (B-K) scattering theories. However, the classical Beckmann-Kirchhoff theory contains a small-angle limitation (i.e., it fails at large angles of incidence and wide scattering angles). Thus, we also endeavor to demonstrate the modified Beckmann-Kirchhoff scattering theory, an approach by Verold and Harvey, using multipath channel transfer function (CTF) dynamics for line-of-sight (LoS) and non-line-of-sight (NLoS) conditions in a simple office environment.