Full-wave analysis of circular waveguide horn antennas including the outer wall geometry with an hybrid MM/BCMM method

An efficient hybrid technique is developed for the rigorous analysis of circular waveguide horns including the arbitrarily shaped outer antenna geometry with symmetry of revolution. The mode matching method for stepped waveguide discontinuities is used to model the interior surfaces. The boundary contour mode matching (BCMM) method with spherical wave expansion is employed for the outer region. To show the usefulness of the method, the far field patterns of a conical horn example at 12.5 GHz are calculated and compared with measurements. Excellent agreement also for wide angles and in the back region of the horn is demonstrated.