Accurate radiation characteristics of horn antennas-a moment method model

Presents an accurate model to predict the performance of rectangular horns. The authors first characterize the aperture of the horn in terms of its generalized reflection matrix. The generalized reflection matrix is formulated using the principle of equivalence and the spectral Galerkin method. The reflection matrix so obtained includes the effects of several incident modes on the aperture surface, the energy stored in the vicinity of the aperture surface, and the induced current on the finite flange. The reflection matrix is then combined with the generalized scattering matrix of the horn to yield the input return loss of the horn and the aperture fields (both electric and magnetic) in terms of the incident field at the input section. The generalized scattering matrix can be obtained using a mode matching formulation or using the multimode moment method formulation (Bhattacharyya 1994). The aperture electric and magnetic fields and the induced current on the flange determines the radiation pattern of the horn. It is found that the present model can predict the input return loss, co-pol and cross-pol patterns of a horn very accurately. The authors present some representative results to validate the formulation.