Exact Solution of a PTD-Symmetric Bifilar-Line Waveguide Formed by Parallel-Plate Impedance Junctions

This work aims at investigating a parity time-reversal duality (PTD) symmetric bifilar-line waveguide structure constituted by a pair of two parallel-plate waveguides with complementary surface impedances on their boundary walls. Under certain conditions for the dimension of the waveguide, this structure supports electromagnetic edge-line modes protected against backscattering. The Wiener-Hopf method is carried out to derive an analytical exact solution for the dominant mode field along with its propagation constants. Numerical calculations are performed to validate the solution.