A Novel Metamaterial-Based Planar Integrated Luneburg Lens Antenna With Wide Bandwidth and High Gain

Bo Hu,Yang Cai,Tao Wu,Wei Zhang,Bao-Ling Zhang

doi:10.1109/access.2019.2960634

Abstract

A novel metamaterial-based and broadband planar integrated Luneburg lens antenna is designed, fabricated, and measured. A substrate integrated waveguide (SIW) horn antenna is applied as the source to illuminate the operation of the Luneburg lens. In particular, air-via metamaterial structures are loaded in front of the SIW horn aperture to realize broadband performance. Meanwhile, the feeding structure by the SIW horn antenna and the Luneburg lens are integrated through this air-via metamaterial transition. Accordingly, the air-via unit cells are designed and arranged in an array with an equivalent gradient refractive index through diameters to achieve good wave focusing effects. Besides, a good agreement is observed between simulations and experiments. The measured results indicate that a wide bandwidth from 16 to 28 GHz is realized with the return loss below -10 dB. Moreover, high end-fire gains varying from 12.5 to 17 dBi are obtained in the band of 18-27 GHz.

Highlights

Luneburg lens has the ability to transform a spherical wave on the edge of the lens into a plane wave on the opposite side
Every point on the surface of an ideal Luneburg lens is the focal point of a plane wave incident from the opposite side
Luneburg lens is popular for the wide-angle radiation scanning application because of its wide bandwidth, high gain and the property of forming multiple-beams

Summary

INTRODUCTION

Luneburg lens has the ability to transform a spherical wave on the edge of the lens into a plane wave on the opposite side. Every point on the surface of an ideal Luneburg lens is the focal point of a plane wave incident from the opposite side This provides a Luneburg lens antenna with high gain and radial symmetry. Core-shell units consisting of air and a certain dielectric were previously adopted to provide a gradually varying refractive index. This method suffers from complex design and processing. The planar Luneburg lenses have been designed and fabricated to provide broadband and high-gain function by different metamaterial units [4]–[6]. B. Hu et al.: Novel Metamaterial-Based Planar Integrated Luneburg Lens Antenna With Wide Bandwidth and High Gain

FEEDING STRUCTURE DESIGN

EXPERIMENTAL RESULTS

CONCLUSION