3D printed multibeam circularly polarized Luneburg lens antenna based on anisotropic metamaterials

This paper proposes a 3D-printed X-band circularly polarized (CP) Luneburg lens (LL) antenna based on anisotropic unit cells. To achieve independent control of the equivalent permittivity for waves of different polarization and enables a stable phase difference, an asymmetric cross-shaped anisotropic unit cell is proposed. Then the 3-D-printed LL, composed of nine radially stacked layers, is designed. The LL antenna exhibits a measured axial ratio bandwidth of 26.5%-30.7% and an aperture efficiency of 39.1%-71.1%. The antenna achieves ±60° beam coverage and a peak gain of 20.54 dBic, while maintaining reflection coefficients below -10 dB and isolation greater than 17 dB over the operation band. The proposed LL antenna would be a good candidate for X-band application.