TE11-mode excitation of a circular aperture antenna covered by a layered dielectric hemi-spherical radome

Abstract

This paper presents a full-wave analysis of the antenna radiation due to an aperture in a ground plane generating a circular waveguide TE11 wave, which is covered by a dielectric hemi-spherical radome of multi-layered geometry. Huygen's equivalence principle and the image theory are utilized to simplify the problem. The dyadic Green's function technique is applied to analyze the electromagnetic fields due to the circular aperture antenna with TE11 field distribution. Following the conventional procedure, the magnetic dyadic Green's functions for radially three-layered and four-layered geometry are formulated to account for the full-wave contribution due to such an equivalent magnetic surface current. The coefficients of these dyadics are derived by duality substitution and reduction from the authors' earlier published work. The Fraunhofer electric fields are obtained using the far-zone approximation. In order to show the applicability of the analysis in this work and demonstrate the effects of the dielectric radome on the radiation patterns, computations of the power patterns, beamwidths, and total transmission losses are made and the results obtained here are compared with the existing results in the literature.