Compact Multibeam Fully Metallic Geodesic Luneburg Lens Antenna Based on Non-Euclidean Transformation Optics

TLDR

Non‑Euclidean transformations link 3‑D homogeneous surfaces to 2‑D dielectric lenses, allowing propagation on a geometrical surface to emulate an equivalent refractive‑index distribution. The authors propose a fully metallic Luneburg lens that confines propagation to air. The lens consists of two curved metallic plates that mimic the designed curvature, is height‑reduced by mirroring the surface twice across two z‑constant planes, and is fed by 11 waveguide ports spaced 12.5° to enable 1‑D beam scanning over ±62.5°. A prototype was fabricated and measured, showing good agreement with simulations between 25 and 36 GHz, thereby validating the concept.

Abstract

Non-Euclidean transformations have been recently proposed to produce a link between 3-D homogeneous surfaces and 2-D dielectric lenses. Therefore, the propagation in a geometrical surface has the same response of an equivalent refractive index distribution. By using this concept, we propose here a fully metallic Luneburg lens where the propagation is only in the air. Two metallic plates, following a curved shape, are employed to support the propagation mimicking the designed curvature. To reduce the height of the required curvature, the surface has been mirrored twice with respect to two z constant planes. The lens is fed by 11 waveguide ports spaced with an angle of 12.5° providing 1-D beam scanning over an angular range of ±62.5°. A prototype is manufactured and measured with a good agreement with the simulated results between 25 and 36 GHz to demonstrate the concept.