Low-Profile Dual-Polarized Luneburg Lens Based on TE/TM Surface Wave Modes

Abstract

This letter presents a novel dual-polarized two-dimensional (2-D) Luneburg lens operated at millimeter-wave band with a low-profile and planar structure. Based on a dual-mode unit cell that supports TE/TM surface wave modes with orthogonal polarizations, the proposed 2-D Luneburg lens with gradient refractive index distribution compresses the beamwidth in one dimension and achieves fan-shaped beams for both of the two polarization modes. To verify the proposed Luneburg lens, a prototype is fabricated using the printed circuit broad process with low cost, weight, and profile. The measured peak gain of H- and V-pol mode is 17.0 dBi and 17.2 dBi, respectively. Because the surface wave modes are applied to both polarizations of the proposed Luneburg lens, the electromagnetic waves transform from the lens to the air smoothly, without the need for additional radiation structures, which reduces the profile further and increases the antenna aperture.