Surface-wave luneberg lens antennas

It is demonstrated that a surface-wave structure having isotropy in the plane of the structure can be operated as a lens. The index of refraction is given for a dielectric slab on a ground plane, a bed of metal posts on a ground plane and a parallel-plate structure with one plate filled with holes. The necessary radial variations in index for several Luneberg-type lenses are given. These include the conventional Luneberg lens, Gutman´s modification, the rim-fed Luneberg adapted to a spherical surface and a modification adapted to a spherical surface and collimation of the rays at an arbitrary angle with respect to the plane on which the lens is mounted. An approximate analysis of surface-wave lenses based on optics is described.