Free-Space-Impedance-Matched Composite Dielectric Metamaterial With High Refractive Index

In this letter, we present an all-dieletric metamaterial (ADM) design to achieve both free-space impedance matching and high refractive index in the X-band. This design is formed by two different-size of dieletric resonator cubes, which are made of strontium titanate, SrTiO3, with high permittivity and low loss. The Mie theory is used as theoretical framework to design high permittivity and high permeability, simultaneously. By scaling the size and lattice constant of the individual units, the first magnetic resonance of one cube (generating high permeability) and the first electric resonance of the other cube (generating high permittivity) can be colocated in order to achieve the free-space impedance matching. The S-parameters and the constitutive parameters are used to demonstrate that the composite cube/cube design has a transmission window with a high refractive index. Experimental measurements are carried out to verify the design concept. All-dieletric metamaterial can be presented as an alternative way to achieve the reflection-less surface, referred to as a Huygens' surface, and create a high index of refraction at the same time.