Broadband Dispersionless Glide-Symmetric Parallel-Plate Waveguide with Small Corrugations

Glide-symmetric metasurfaces are a low-loss, con-formable and cheap solution for the design of wide-band microwave devices, notably lens antennas. However, existing models do not explain why glide symmetry decreases the dispersion over a large spectrum. Here, the dispersion equation of a glide-symmetric corrugated parallel-plate waveguide is linearized under certain geometrical restrictions, notably the size of the corrugations, proving that the effective refractive index of this structure is frequency-independent over the first Brillouin zone.