High-Efficiency Multi-Beam GRIN Lens with 2-D Wide-Angle Coverages

Multi-beam gradient-index (GRIN) lenses are investigated to enable high aperture efficiencies and 2-D wide angular coverages. Metasurface composed of engineered elements with varied refractive indices is employed to implement the lens. Innovative methodologies are developed to calculate refractive-index distributions on the lens as well as the corresponding feed positions for multiple beams. A three-metal-layer element is developed to enable the variation of effective refractive index. Microstrip patch array antennas are designed as feed sources. Thirteen feed arrays are arranged on two focal arcs in xoz and yoz planes. A GRIN lens prototype is constructed, radiating multiple beams in a wide range of +/- 45 degrees in two orthogonal planes with low scanning losses. The peak realized gain is 21.8 dBi with an aperture efficiency of 62.8%. The operating bandwidth is 22.2% from 12 GHz to 15 GHz.