Improved analysis of antenna radiation from a circular aperture covered by a dielectric hemispherical radome shell

Abstract

A novel full-wave analysis of the antenna radiation due to an aperture flush-mounted on a ground plane and excited by a circular waveguide TE11 wave is presented. The aperture is further covered by a dielectric hemispherical radome. Huygens' equivalence principle and image theory are utilized to simplify the problem, and magnetic dyadic Green's functions are employed to formulate both the reactional magnetic current distribution around the aperture and the inner near-zone and outer far-zone electromagnetic fields. The idea of reactional iteration is implemented in this work, and, hence, the final equivalent source is obtained in quite a compact form. Comparison between the results obtained and those published elsewhere in the literature shows the additional contributions to the equivalent magnetic source distribution and the near- and far-zone field patterns from the feedback of the electromagnetic fields reflected from the dielectric radome. Although applied only for a simple-layer dielectric radome, the method itself is not restricted by the number of layers and can easily be extended to a multi-layered radome or dielectric inhomogeneous radome.