Highly selective left-handed transmission line loaded with split ring resonators and wires

The frequency selectivity of coplanar transmission lines loaded with split ring resonators and shunt strips was dramatically improved owing to a blueshift of the electrical plasma frequency by oversizing the strip width. Beyond a higher rejection level, which was expected as a consequence of the deepening of the forbidden gap between the left- and right-handed dispersion branches, a huge enhancement in the loaded $Q$ quality factors, while maintaining low insertion losses were also pointed out. This $Q$ factor improvement was a consequence of a decrease in the coupling between the resonators and the transmission line.