Omega-Type Balanced Composite Negative Refractive Index Materials

We report on the theoretical and experimental analysis of Omega-type metamaterials operating in X and Ku-bands. The prototypes are fabricated on the basis of metal waveguide technologies (hollow and TEM parallel plate) loaded with printed boards of interconnected Omega-shaped motifs. This interconnection of particles in the transverse direction leads to a broad left-handed band. Moreover, it is shown that such structures can be designed for a continuous negative-zero-positive index dispersion. This balanced composite behavior, so far known for periodically loaded transmission lines is verified experimentally with left- and right-handed dispersion branches extending from 8 to 12 and 12 to 16 GHz respectively. This zero-gap capability is explained on the basis of effective parameters retrieval.