A 3D-Printed Spherical Dual-Circular Polarized Luneburg Lens Antenna for Ku-Band

Abstract

In this paper, we propose a novel three-dimensional-printed Luneburg lens for converting linear polarization to dual-circular polarization and successfully apply it in a multibeam antenna. The discrete unit cell, used as the gradient-index material to approximate the required refractive index in the Luneburg lens, has its effective refractive index calculated by effective medium theory. To achieve the polarization conversion, the symmetry of the unit cell is disrupted. A 100 mm diameter lens is designed to operate at 12.6-17.1 GHz, fed by a low-profile dual-polarized magneto-electric dipole antenna. By analyzing the size and isolation of the antenna, a multibeam lens antenna with five feeds was designed, which features a compact antenna layout and low coupling between them. The multibeam Luneburg lens antenna enables beam scanning of ±60° in the horizontal plane. Measurement results show an overlapped bandwidth of 30% with reflection coefficients below -10 dB and axial ratios under 3 dB. At the center frequency of 15 GHz, the gain reaches 21 dBi, approximately 14 dB higher than the magneto-electric dipole antenna without the lens.

Keywords

• Dual-circular polarization antenna
• Luneburg lens
• multibeam antenna
• polarization conversion
• three-dimensional-printed antenna