A Dirichlet to Neumann Map Based Hybridization of a Mode Matching and Offset Moment Method for Horn Antennas Analysis

A hybrid technique for the analysis of pyramidal and conical horn antennas is presented based on an exact vector Dirichlet to Neumann (DtN) mapping mathematical formalism. The transition from the feeding waveguide to the radiating aperture is analyzed by using the mode matching technique (MMT) employing a stepped-waveguide approach. Love's field equivalence principle is employed for the de nition of equivalent electric and magnetic current densities at the horn aperture. Explicitly, these currents are located at a plane parallel to the aperture but slightly shifted inwards in order to implement an offset Moment Method for their discretization, which is free of integral singularities. The unbounded area field generated by these sources is enforced to be continuous with the internal mode matching field by strictly following DtN principles. Besides that, this procedure mimics a By-moment approach ensuring the decoupling of the required number of modes from that of the sources discretization degrees of freedom. Finally, the implemented hybrid method is validated against published experimental and numerical results for a number of pyramidal and conical horn antennas including various corrugated geometries.