Metaprism Design for Wireless Communications: Angle-Frequency Analysis, Physical Realizability Constraints, and Performance Optimization

Recent advancements in smart radio environment technologies aim to enhance wireless network performance through low-cost electromagnetic (EM) devices. Among these, metaprisms (MTPs)—a class of static, frequency-selective metasurfaces—stand out for their ability to create multiple beams at different frequencies without requiring channel state information (CSI) or active reconfiguration. Unlike reconfigurable intelligent surfaces (RIS), which rely on programmable elements and periodic tuning, MTPs operate passively, significantly reducing system complexity and overhead. The working principle of MTPs is specifically tailored for scenarios in which a large number of devices must be served simultaneously, each requiring low data rate and low latency, as envisioned by, e.g., Industrial Internet-of-Things (IoT). In this paper, we address the design of an ideal MTP by considering frequency-dependent reflection coefficients, and by identifying the general properties that are necessary to achieve the desired beam steering function in the angle-frequency domain. We also discuss the limitations of previous studies that employed oversimplified models, which may compromise performance. Key contributions include a detailed exploration of the equivalence of the MTP to an ideal S-parameter multiport (MP) model and an analysis of its implementation using Foster’s circuits. Additionally, we introduce a realistic MP network model that incorporates aspects overlooked by ideal scattering models, along with an ad-hoc optimization strategy for the obtained model. The performance of the proposed optimization approach and circuits implementation are validated through simulations using a commercial full-wave EM simulator, showcasing the effectiveness of the proposed method.