Electric-Type Dyadic Green´s Functions for a Corrugated Rectangular Metaguide Based on Asymptotic Boundary Conditions

The Green´s functions for the mixed potential electric field integral equation are derived for a rectangular waveguide with dielectric-filled corrugations supporting left- as well as right-hand propagation. Under the asymptotic boundary conditions assumption, the expressions of the Green´s dyadic components can be decomposed into terms that represent conventional waveguide modes and others that represent hybrid metaguide modes. A simple approach is used to find the poles of the spectral domain expressions before obtaining the spatial domain expressions using the inverse Fourier transform. The dispersion diagram reflects very interesting characteristics for the structure and the deviation from the conventional case. The derived Green´s function is verified by considering the problem of a probe excitation and comparing the input impedance obtained using a moment method procedure based on the present theory and the finite-difference time-domain method