Effect of a Protective Coating on the Characteristics of a Reconfigurable Intelligent Surface

Abstract—Reconfigurable intelligent surfaces (RISs) are promising devices capable of increasing the information capacity and coverage of new and available wireless networks. By now, most of these devices have been presented in the form of prototypes that have no environmental protection and are not adapted for use in real communication systems. Meanwhile, a protective coating can significantly affect the characteristics of a RIS and reduce its efficiency. This study considers the effect of thickness, permittivity, and dissipation factor of the most common protective coating materials on the frequency and phase responses of a RIS unit cell (UC). Recommendations on choosing a material and its thickness and on correcting UC sizes at constant parameters of a protective coating are provided.