Exploration of edge modes formed in periodic hexagonal metasurfaces with glide symmetry

We study the edge modes supported by a bilayer metasurface formed by two arrays of circular metallic patches with a finite width. The circular patches are arranged in an identical hexagonal array in each layer. It was found that depending on the way the second layer is placed with respect to the first one, there exists an edge mode at frequencies that lie inside the stopband of the structure.