Design of horn antennas by hybridizing mode matching with a spectral domain procedure

A hybrid MM/spectral domain based approach for the analysis of horn antennas has been presented. It has been show that the choice of TE and TM waveguide modal eigenvectors as basis functions, permits to resort to an efficient spectral domain procedure for the calculation of the admittance matrices. A numerical example involving an horn antenna with rectangular cross section has been presented. The proposed approach is well suited for solving problems involving analytically transformable modes; anyway if the analytical transforms of the modes are not available, a DFT procedure can be used. Thus, problems involving not-conventional shaped horn antennas can be addressed too. Moreover, the spectral domain procedure can be easily extended to the calculation of the mutual coupling when aperture array problems are encountered, even when dealing with not coplanar apertures.