Realizing an ultra-wideband backward-wave metamaterial waveguide

Abstract

Electroinductive waves have emerged as an attractive solution for designing metamaterials that support backward propagating waves. Stacked metasurfaces etched with complementary split-ring resonators (CSRRs) have also been shown to exhibit a broadband negative dispersion. We demonstrate, through experiment and numerical modeling, that the operational bandwidth of a CSRR metamaterial waveguide can be improved by restricting cross-polarization effects in the constituent meta-atoms. We report a fractional bandwidth of $>56%$, which, to the best of our knowledge, is broader than any previously reported value for an electroinductive metamaterial. We present a traditional coupled-dipole toy model as a tool to understand the field interactions in CSRR-based metamaterials, and to explain the origin of their negative dispersion response.