An isotropic three-dimensional negative-refractive-index transmission-line metamaterial

We propose an isotropic three-dimensional (3D) negative-refractive-index medium using transmission lines loaded with reactive elements. The medium is referred to as the 3D dual transmission line (TL). Analytical expressions are derived which provide insight into the backward-wave propagation supported by the proposed medium. The dispersion characteristics of a physically realizable 3D dual TL are computed using a full-wave eigenmode solution of Maxwell's equations based on the finite-element method. In addition, scattering parameters for a slab made of the 3D dual TL are presented. The described approach can be generalized for synthesizing a wide range of 3D metamaterials with tailored material parameters including both isotropic and anisotropic designs. (c) 2005 American Institute of Physics.