Multiple-mode resonance bands in periodically nonuniform conductor-backed coplanar waveguides

The full-wave spectral-domain technique is developed to investigate the characteristics of periodically nonuniform MIC transmission lines. The Floquet´s theorem is employed to express all the field quantities in terms of the spatial harmonics, so that the boundary-value problem of a periodically nonuniform transmission line can be treated similarly to that of the uniform one. The Galerkin´s method in the Fourier-spectral domain with a set of appropriate basis functions is used to obtain the numerical results for the characteristics of the sinusoidal-shaped coplanar waveguides with/without backside ground. The multiple resonance bands produced by the dominant mode as well as the higher-order modes in these periodic structures are exploited theoretically and experimentally