Novel broadband conventional- and dual-composite right/left-handed (C/D-CRLH) metamaterials: properties, implementation and double-band coupler application

Broadband conventional- and dual-composite right/left-handed (C/D-CRLH) transmission line metamaterials are presented. The extended transmission line theory for these structures is developed and the fundamental C-CRLH and D-CRLH properties are described comparatively in terms of dispersion/attenuation diagrams and Bloch/characteristic impedances with subsequent transmission characteristics. A D-CRLHstructure, implemented in microstrip technology, is demonstrated experimentally for the first time and shown to have potential for unique applications. As an illustration of such applications, a novel double-band coupled-line coupler constituted of one C-CRLH and one D-CRLH transmission line is demonstrated and explained by generalized coupled-mode theory.