Maximal Operation Band of Binary Metasurfaces with Controllable Anomalous Reflection

The maximal achievable bandwidth of a reconfigurable intelligent surface implemented as a binary metasurface is considered and analytically deduced taking into account the restrictions imposed by the non-ideal angular stability of practical metasurfaces. This bandwidth is proportional to the effective inductance of the metasurface, and its maximum demands the low-index substrate of sufficient thickness.