3-D Printed Cylindrical Luneburg Lens for Dual Polarization

In this letter, a 2-D Luneburg lens sandwiched by two parallel metallic plates is proposed. To support both the vertical and the horizontal polarizations, parallel plate waveguide (PPW) theory is applied to analyze the proposed lens. The results shown that the height of the lens and the consistence of the gains for each polarization has a tradeoff relation. The optimized height of the lens is approximate one operating wavelength. To verify our idea, a cylindrical Luneburg lens is fabricated using 3-D printing technique with a radius of 4.65λ
₀
. Using effective medium theory, the relative permittivity in each region of the lens can be obtained by adjusting the air-to-space ratio of the meta-atoms in that region. A dual-polarized patch antenna working around 15 GHz is used to feed the lens. The measured results agree well with the simulated ones, which prove that the gains of the two polarizations can be designed as equality by setting a suitable height of the lens. The measured gain is 15.1 dBi for vertical polarization and 14.7 dBi for horizontal polarization at 15 GHz. The lens-antenna system launches beams which points at -60°, -20°, 20°, 60° in the measurement for verification. The proposed Luneburg lens is suitable for base station which has the requirement of dual-polarized multibeam antennas.