Design of multibeam scanning antennas with high gains and low sidelobes using gradient-index metamaterials

Metamaterials, composed of artificial structures with subwavelength unit cells, can be fabricated to achieve gradually refractive indices. By designing the refractive indices properly, a gradient-index planar slab will transform spherical waves to plane waves. Using such a property, we propose a beam-scanning antenna with high gain and low sidelobes based on the gradient-index planar lens and a horn antenna, where the beam direction is controlled by the refractive-index distribution. When such four lenses are fixed together, we can get a four-beam scanning antenna with high gain and low sidelobes, in which each beam can be controlled independently. The gradient-index planar lenses can be realized using metamaterial structures.