Analysis of bandwidth and loss in negative-refractive-index transmission-line (NRI-TL) media using coupled resonators

The bandwidth and loss characteristics of negative-refractive-index transmission-line (NRI-TL) metamaterials are examined in the limit of the model of coupled C-L resonators. It is analytically shown that the tighter the coupling between resonators, the wider the size of the backward passband and the smaller the propagation losses. This establishes that the wider bandwidths and smaller losses that characterize NRI-TL media are due to the tight coupling (i.e., electrical connection) between their constituent C-L loop resonators, rather than the absence of resonators.