On the Orientation of Split-Ring Resonators in Metamaterial Media

Split-ring resonators (SRR) are used both in microstrip and waveguide metamaterial structures to obtain negative values of permeability, whereas complementary split- ring resonators (CSRR) result in negative permittivity when placed below the microstrip. While the orientation of SRR positioned next to the microstrip transmission line significantly influences its performances, it is generally accepted that such dependence does not exist in the case of CSRR-loaded microstrip or SRR-loaded waveguide. In this paper, we show that SRR and CSRR can not be arbitrarily orientated, neither in microstrip nor in waveguide structures. The influence of the orientation is especially visible in the case of multiple CSRR geometries. To validate simulation results, microstrip lines loaded with multiple CSRRs were designed, fabricated and measured.