Macromodeling of Reconfigurable Intelligent Surface Based on Microwave Network Theory

• Published in: IEEE transactions on antennas and propagation 2022-10, Vol.70 (10), p.8707-8717
• Main Authors: Zhang, Zhen, Zhang, Jun Wei, Wu, Jun Wei, Liang, Jing Cheng, Wang, Zheng Xing, Cheng, Qiang, Cheng, Qingsha S., Cui, Tie Jun, Yang, Han Qing, Liu, Guo Biao, Wang, Si Ran
• Format: Article
• Language: English
• Subjects: Beam steering; Circuit design; Encoding; Equivalent circuits; Far fields; Impedance; Incident waves; Integrated circuit modeling; Metasurfaces; Microwave network theory; Microwave theory and techniques; physical modeling; reconfigurable intelligent surface (RIS); Reconfigurable intelligent surfaces; Reflectance; Reflection; Surface impedance; Surface waves; Wireless communication systems
• ISSN: 0018-926X; 1558-2221
• DOI: 10.1109/TAP.2022.3187645

Reconfigurable intelligent surfaces (RISs) are of potential use in wireless communication systems due to their ability to perform beam steering, harmonic wave manipulation, and polarization conversion. However, the main challenge in designing RISs is to obtain their electromagnetic (EM) responses, which is time-consuming and computationally prohibitive. In this work, an efficient modeling method is proposed for fast evaluation of the reflection coefficient and far-field patterns of RISs. The proposed method utilizes the microwave network theory to compute the accurate reflection coefficient of RISs elements under the illumination of incident waves from arbitrary directions. Compared to the classical equivalent circuit model, it enables the separate design of meta-atoms and tunable devices at the network level. The proposed method is verified by the full-wave simulation results of two RIS elements and experimental results of a 3-bit RIS. This work forms a fast and feasible route to obtain the responses of RISs, which allows the RISs to find extensive applications in many scenarios.