Homogenization and Dispersion Properties of Glide-Symmetric Corrugated Metasurfaces

In this paper we propose closed-form formulas for the effective refractive index of a wave propagating along two parallel corrugated surfaces arranged in a glide-symmetric configuration, having a small groove compared to the period. This kind of structure has proved to suppress the frequency dispersion typical of periodic material when the gap between the surfaces is small. The closed-form expressions show analytically this property and prove it for the first time, by means of the lack of a frequency dependence.