Study of a Toroidal Lens

Abstract

This letter presents a study of a toroidal-shaped lens following a Luneburg-like distribution of refractive index intended to multibeam radio frequency front ends. Due to its toroidal shape, this is a new model of lens that does not present any blind spot, as an opposite to any other kind of either spherical or cylindrical lens when adding both antennas and associated electronics. A sidelobe level reduction is proposed based on interface intrinsic impedance matching with magnetic–dielectric composite materials. It also proposed a set of numerical approximations of the main electromagnetic parameters, such as the half-power beamwidth in both the E- and H-planes, and the sidelobe level, and the directivity, in order to provide some basic guidelines for such a lens project. Given the new shape, the impacts of the curvature of the torus on the radiation pattern are also carried out. In order to prototype a toroidal lens with 3-D printing technology, a material has been fully characterized electromagnetically considering infill ratio variations in some effective dielectric constant models for multimaterial mixtures. The resulting toroidal lens has been characterized in far field, demonstrating a good agreement with the model and confirming its great potential for multibeam applications.