Two dimensional diffraction of an antenna pattern by a local half plane

Abstract

Beam blockage by local obstacles is frequently unavoidable in urban antenna sites. To efficiently minimize its effect analysis of the scattering problem is desirable. If the antenna pattern is omnidirectional and large in wavelengths a uniform geometrical theory of diffraction solution can be obtained which can be supplemented by slope diffraction for antennas of low directivity. For a directive antenna beam slope diffraction is usually inadequate but the omnidirectional source solution can be converted to a beam source solution by the complex source point method. Antenna patterns consisting of more than a single beam require a less simple approach. It has already been shown that antenna patterns with sidelobes can be synthesized from arrays of Gaussian beams (Einziger et al., 1986) and this representation applies to both near and far radiation patterns of the apertures. Here such arrays of complex sources of appropriate amplitude and phase are used to calculate the scattering patterns of a local obstacle such as a half plane. For each source in the array the exact solution for the far field, a line source in the presence of a half plane is used so the total scattered field, which is the superposition of these elementary scattering solutions, is as accurate as the representation of the true antenna pattern by the synthesized pattern.