Transmission line models for negative refractive index media and associated implementations without excess resonators

TLDR

Three‑dimensional composite periodic media of split‑ring resonators and thin wires have been shown to exhibit a negative refractive index near the SRR resonance. This letter proposes transmission‑line models to study and interpret electromagnetic propagation in such negative‑index materials. The models represent the media as periodically loaded transmission‑line networks with series capacitors and shunt inductors. Using these models, the authors demonstrate that a negative‑index medium can be synthesized without excess resonators, achieving wideband, planar, frequency‑scalable, compact, and easily implementable RF/microwave circuit performance with tailorable properties across a broad frequency range.

Abstract

Recently, three-dimensional composite periodic media comprising split-ring resonators (SRR) and thin wires have been shown to exhibit a negative refractive index in the frequency range around the SRR resonance. In this letter, we propose transmission line models for studying and interpreting the electromagnetic propagation behavior of such materials. Based on these equivalent transmission line models, we show that by periodically loading a network of transmission lines with series capacitors and shunt inductors, a negative refractive index medium can be synthesized without excess resonators, thus leading to wideband behavior. These proposed media have tailorable properties over a broad frequency range. Moreover, they are completely planar, frequency scalable, more compact, and easier to implement for RF/microwave circuit applications than their SRR/wire counterparts.