Radiation characteristics of a dielectric-loaded rectangular horn

It has been recognized [1] - [3] that the E-plane sidelobe level of a rectangular radiating aperture can be reduced by loading the aperture with a dielectric slab in the H-plane. Such loading is advantageous in certain applications - for example, in feed horns for parabolic reflectors wherein equality of radiation patterns in E and H planes coupled with low spillover radiation is desired. This paper reports some additional results regarding the radiation characteristics of a centrally-loaded rectangular horn. The geometry of the horn considered for the purpose of theoretical calculations and experimental study. The horn is assumed to be excited in the dominant LSM11mode. Omitting analytical details, several aspects of the radiation characteristics are presented in Figs.2 through 5. In the figure captions, h stands for the thickness of the dielectric slab and for its permittivity.