Moment method formulation for the radiation patterns of horn antennas

First, the equivalence principle is applied on the radiating aperture, which yields an equivalent magnetic surface current backed by a perfect electric conductor. The electric conductor together with the flange of the horn acts as a scatterer. The radiation problem is then modified as a scattering problem with magnetic surface current as the primary source of radiation. The unknown induced current on the scatterer is solved using the Galerkin method. A set of entire domain basis functions is used to approximate the current distribution. The radiation patterns which result from both electric and magnetic surface currents are then determined. The entire formulation is computer coded to analyze circular horns. The theoretical results agree favorably with measured data.<>