Finite conductivity uniform GTD versus knife edge diffraction in prediction of propagation path loss

摘要: Diffraction propagation over hills and ridges at VHF UHF is commonly estimated using Fresnel knife edge diffraction. This approach has the advantage of simplicity, for many geometries yields accurate results. However, since it neglects shape composition diffracting surface, can in some cases yield results which are serious disagreement with measurements. To remedy this, attempts have been made to approximate hill or ridge by other shapes, most notably cylinders. These approaches not widely adopted, due large part their greater numerical complexity. In this paper proposed apply wedge diffraction format geometrical theory (GTD), modified include finite conductivity local surface roughness effects. It shown that, grazing incidence and/or angles, significant improvement accuracy obtained. Further, GTD form used based on integral, so that only slightly more complex numerically than Finally, includes reflections from sides (wedge faces), be extended multiple three-dimensional terrain variations.