Electromagnetic Aspects of Wave Propagation over Terrain

Based on Green's theorem and the Huygens's principle, this chapter first introduces the Fresnel zone presentation that will be used for the description of terrain and other obstruction effects, such as reflection and diffraction on radio channels. It presents the main formulas for path loss prediction for a free‐space communication link. Next, the chapter describes the reflection phenomena due to a flat terrain. It then deals with the electromagnetic (EM) aspects of radiowave propagation above a rough terrain. Here, the three methods of mathematical derivation of the field strength are presented to obtain the effects of radiowave scattering from ground surfaces with various roughness (large, median, and small) with respect to the wavelength. The chapter considers the effect of the ground curvature by using Fock's theory of diffraction. FInally, it describes diffraction phenomena caused by a single obstruction placed at the flat ground surface.