On the symmetry properties of coplanar waveguides loaded with symmetric resonators: Analysis and potential applications

This paper is focused on the analysis of coplanar waveguides (CPW) loaded with symmetric resonators (such as split ring resonators and stepped impedance resonators) whose symmetry plane behaves as an electric wall at the fundamental resonance frequency. If these resonators are symmetrically etched in the back substrate side of the CPW, the resonators are not excited, and signal propagation along the CPW is allowed. Conversely, if the symmetry is truncated, the magnetic wall of the CPW (fundamental mode) is not aligned with the electric wall of the resonator, and signal propagation is inhibited in the vicinity of the first resonance frequency. These structures can be of interest for the design of novel sensors or radiofrequency (RF) bar codes, based on the deviation from symmetry. The principle of operation of such structures is illustrated and experimentally validated by proof-of-concept devices.