Characterization of infinite- and finite-extent coplanar waveguide metamaterials with varied left- and right-handed passbands

Coplanar waveguide (CPW) metamaterials with varied left- (LH) and right-handed (RH) passbands are thoroughly studied in terms of per-unit-length transmission parameters and magnitude/phase of transmission coefficient, respectively. The two metamaterials are constructed by simultaneously loading the lumped or distributed CPW series-capacitive and shunt-inductive elements in periodic intervals. Effective characteristic impedance and propagation constant of these infinite-extent metamaterials are first extracted to give a physical insight into the guided-wave propagation characteristics in the LH/RH passbands. It is further exhibited that the stopband between the LH and RH passbands can be wholly eliminated in the distributed CPW case. The two finite-extent CPW metamaterials with 5042 feed lines are then modeled via simple cascaded transmission line theorem. Predicted magnitude and phase of transmission coefficient are confirmed by experiment, showing the distinctive backward- and forward-wave performances in the LH and RH passbands, respectively.