Radiation from a wide-angle conical horn with a homogeneous dielectric sphere in front of its aperture

The effects of placing a homogeneous dielectric sphere in front of the aperture of a wide-angle conical horn are studied both theoretically and experimentally. The theoretical formulation of the ratiation characteristics of the device is made on the basis of scattering of electromagnetic waves by a dielectric sphere. The calculations based on this formulation show overall agreement with the experimental radiation pattern and directivity measurements. It is concluded that the dielectric sphere mounted conical horns will have directiveities in excess of that obtained with a conventional conical horn of the same dimensions, and also that the device can be used as a variable beam feed for parabolidal reflectors.