2x2 Tile Usable for Reconfigurable Intelligent Surfaces Operating at 28 GHz

Reconfigurable intelligent surfaces (RIS) have emerged as a promising technology to realize a smart wireless environment in millimeter wave (mmWave) communication systems. The implementation of RIS is considered to be used for 5G/6G technology operating in the mmWave range. However, manufacturing each unit cell of RIS in mmWave bands can be challenging due to the limited space for implementing RIS components with currently available technology. In addition, implementing a RIS as a dense plane on building facades for reallife applications can be unrealistic, and controlling the RIS can be challenging due to the potentially extreme number of unit cells. In this study, a novel 2x2 tile considered for sparse array RIS and operating at 28 GHz is designed and manufactured. Numerical simulations and experimental measurements are performed and the results are compared. Not only is a good agreement between the experimental and the numerical results presented but also a practical tile design for mmWave RIS implementations is proposed.