An effective low-grazing reflection coefficient for modeling groundwave propagation over randomly rough terrain

In this study, in order to arrive at an analytical representation for the effects of terrain roughness on the near-ground channel, new closed-form expressions for the effective reflection coefficient are presented. The basis of the derivation is founded on the perturbation approach applied to a volumetric integral equation as introduced by Sarabandi and Chiu for remote sensing applications involving the modeling of the general scattering coefficients of rough surfaces with inhomogeneous dielectric profiles. Here, expressions for the coherent effective reflection coefficient are derived for the 2D problem; the accuracy of these expressions for excitation sources of vertical and horizontal polarizations is validated by comparing the simulation results to those obtained from the numerical solver outlined by Liao and Sarabandi (2008).