Open-ended circular waveguide with an infinite conducting flange covered by a dielectric hemi-spherical radome shell: full-wave analysis and Green dyadics

Abstract

This paper investigated the radiation of a dipole antenna inside a conducting waveguide with an infinite conducting flange. The opening of such a waveguide is further covered by a hemi-spherical dielectric radome shell. To completely solve the problem, not only the electromagnetic fields radiated by the antenna located inside the waveguide but also the dyadic Green's functions in such a structure are formulated using the mode-matching technique. The scattering coefficients of the dyadic Green's functions, coupled in matrix form, are derived by matching the boundary conditions on circular waveguide conducting walls and all the dielectric interfaces. To show how the derived theoretical formulas are implemented numerically, the radiation patterns of the open aperture excited by a dipole antenna inside the circular waveguide are obtained for various dimensions of the radiating system. Comparison between numerically exact results in the presence of radome in this paper and those approximate results in the presence of radome or those exact results in the absence of radome, demonstrating accuracy and applicability.