Complementary metamaterial elements provide an effective permittivity and/or permeability for surface structures and/or waveguide structures. The complementary metamaterial resonant elements may include Babinet complements of "split ring resonator" (SRR) and "electric LC" (ELC) metamaterial elements. In some approaches, the complementary metamaterial elements are embedded in the bounding surfaces of planar waveguides, e.g. to implement waveguide based gradient index lenses for beam steering/focusing devices, antenna array feed structures, etc..

Metamaterials for surfaces and waveguides

Utilizing non-resonant metamaterial elements, we demonstrate that complex gradient index optics can be constructed exhibiting low material losses and large frequency bandwidth. Although the range of structures is limited to those having only electric response, with an electric permittivity always equal to or greater than unity, there are still numerous metamaterial design possibilities enabled by leveraging the non-resonant elements. For example, a gradient, impedance matching layer can be added that drastically reduces the return loss of the optical elements due to reflection. In microwave experiments, we demonstrate the broadband design concepts with a gradient index lens and a beam-steering element, both of which are confirmed to operate over the entire X-band (roughly 8-12 GHz) frequency spectrum.

Broadband gradient index microwave quasi-optical elements based on non-resonant metamaterials

A multiple beam reflector antenna includes at least one reflector, a plurality of feed horns for feeding the at least one reflector, and a metamaterial lens interposed between the plurality of feed horns and the at least one reflector. The metamaterial lens may provide an overlapping element distribution from at least two feed horns of the plurality of feed horns. In one embodiment, the metamaterial lens has an index of refraction between about zero and about one.

Metamaterial lens feed for multiple beam antennas

Arbitrarily high permittivity realized in artificial dielectrics makes it possible to fabricate a very thin lens antenna for the microwave and m/m wave frequency bands. Photolithography technology adopted to make artificial dielectrics help control the permittivity place to place on the lens surface, resulting in a flat antenna different from the conventional convex or concave counterpart.

Very Thin and Flat Lens Antenna Made of Artificial Dielectrics

Loss and bandwidth have been major problems that limit the potential applications on metamaterials for a long time. To bring the ultimate opportunity to metamaterials, we analyze and discuss, in this chapter, another type of metamaterials that perform at low loss and broad bandwidth. Although the range of structures is limited to those having only electric response, with an electric permittivity always equal to or greater than unity, there are still numerous metamaterial design possibilities enabled by leveraging the non-resonant elements. For example, a gradient, impedance matching layer can be added that drastically reduces the return loss of the optical elements, making them essentially reflectionless and lossless. In microwave experiments, we demonstrate the broadband design concepts with a gradient-index lens and a beam-steering element, both of which are confirmed to operate over the entire X-band (roughly 8–12 GHz) frequency spectrum.

Tomoyuki Nojima

Papers

A reflector lens antenna consisting of an artificial dielectric

A Reflector Lens Antenna Consisting of an Artificial Dielectric