In this paper, the radiation characteristics of an open circular waveguide asymmetrically covered by a layered dielectric hemi-spherical radome are analyzed. On the waveguide opening, the dominant TE11 wave of the circular waveguide is assumed. The technique of dyadic Green's function is applied to obtain the radiated electromagnetic fields due the circular aperture. Huygens' equivalence principle and the image theory are utilized to simplify the problem. The translational addition theorems of spherical vector wave functions are also employed to make the mathematical representation of the radiated fields compact. Both the exact formulation in the near (radiating-field) zone and the approximate expressions in the far (Fraunhofer) zone of the radiated fields are obtained. Numerical computations are implemented to show the effects of the off-centered source feed asymmetrically covered by the hemi-spherical dielectric radome.
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