Evanescent rectangular waveguide with corrugated walls: a composite right/left-handed metaguide

A negative-refractive-index guided-wave structure is realized using a rectangular waveguide with corrugated broad wall and operating in the evanescent region. In the equivalent transmission line model, the shunt inductance is inherent from the evanescence condition, where the waveguide equivalent circuit is an L-L circuit. The series capacitive impedance provided by the slots that constitute the corrugated wall dominates over the waveguide series inductance in a certain frequency range, resulting in the equivalent C-L transmission line circuit. Analysis of the structure using the equivalent transmission line model is presented showing the dispersion and scattering characteristics of the structure. Comparison between the equivalent circuit model and the full-wave finite-difference time-domain solution exhibits very good agreement.