Recent Advances in Metamaterial Transmission Lines Based on Split Rings

This paper is focused on metamaterial transmission lines based on split rings. Specifically, the considered lines are those based on the hybrid approach, where complementary split ring resonators (CSRRs) are combined with series gaps and shunt inductive stubs, and those implemented by loading a host line with open split ring resonators (OSRRs) and open complementary split ring resonators (OCSRRs). The dispersion characteristics and the characteristic impedance of such lines, essential for design purposes, are analyzed to the light of the lumped element equivalent circuit models of the lines. Finally, it is shown that hybrid lines are useful for the design of power splitters with filtering capability, and OSRR/OCSRR-loaded lines are of interest for the design of wideband bandpass filters. The achieved performances are satisfactory and device dimensions small.