Planar reflector antenna design based on gradient-index metamaterials

It is well known that a gradient-index planar slab can be designed to transform spherical waves to plane waves. Several high-directivity lens antennas with low sidelobe have been reported by using the gradient-index lens and a horn antenna. Here, we report a planar reflector antenna with high-directivity, in which the beam direction is controlled by the refractive-index distribution. The gradient-index planar lenses, covering on the metallic sheet, can be realized using metamaterial structures.