All-dielectric ultra broadband MIMO Luneburg lens with sub-diffraction resolution

Abstract A 3D-printed ultra-broadband planar Luneburg lens composed of periodic gradient structures is proposed in this paper. Compared to the previous studies, the proposed lens has a pretty large operating frequency range, spanning from 5 to 22 GHz. The measured results of the near-field and far-field illustrate the feasibility and validity of this lens antenna. High efficiency achromatic sub-diffraction focusing with a full-width at half-maximum of 0.3 λ and a highly directive far-field radiation pattern with side lobes below −10 dB are achieved. Triple input and triple output function is also realized experimentally.