Metantennas: Flat Luneburg Lens Antennas Using Transformation Optics Method (TOM)

Luneburg lens has long been developed since first being proposed in 1944. The Luneburg lens is a spherical lens generally having a gradient of decreasing refractive index radially out from its center. The focusing properties of the Luneburg lens can be achieved through an infinite number of refractive-index solutions. With the spherically symmetrical structure and gradient radial refractive index change, the Luneburg lens is an excellent candidate for all-directional beamscanning antennas. This paper presents two types of flat Luneburg lens antenna based on printed circuit board technique for beamscanning applications. The transformation optics is used to flatten the design of conventional spherical Luneburg lenses and the technology based on metamaterials is proposed to implement the gradient index lens structure.