Sidelobe reduction with array fed spherical lenses

Abstract

The material contained in this paper is intended to help determine the feasibility of using a spherical lens as a low sidelobe multiple beam antenna. It includes what are deemed the most relevant points of a more thorough investigation. We consider the constant-k lens and the Luneberg lens. The constant-k lens, as the name implies, is a homogeneous dielectric sphere. R.K. Luneberg proposed the Luneberg lens in 1944. Morgan (1960) derived a general class of Luneberg lenses that focus from one arbitrary point source to another. In the 50s and 60s antenna designers applied Luneberg lenses to a wide variety of antenna and scattering applications. The array feed used to illuminate the lens has its surface on a sphere with a radius equal to, or larger than, the outer radius of the lens. Each element of the array forms an independent beam. These beams are combined to form a new beam with lower sidelobes.