The recent introduction of the smart radio environments (SREs) paradigm, facilitated by reconfigurable intelligent surfaces (RISs) and large surface antennas, has highlighted the need for physically consistent models and design tools in communication systems that integrate information theory (IT) and electromagnetic (EM) theory. In this paper, we present a comprehensive framework for characterizing and designing programmable EM environments, based on rigorous EM arguments and represented through a linear graph employing matrix operators. The framework enables the determination of the EM transfer function of the system and the channel matrix used in IT, along with their relationship as functions of the programmable parameters. Considering that the mapping of EM quantities into IT signals occurs through the presence of ports in antenna structures, using the framework, we analyze the constraints imposed by the ports in terms of potential degrees-of-freedom (DoF) and establish the fundamental limits on the DoF of large surface antennas. To demonstrate the utility and validity of the framework, we provide examples specifically related to the characterization and optimization of RISs.

中文翻译：

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可重构电磁环境：通用框架


最近引入的智能无线电环境 (SRE) 范式在可重构智能表面 (RIS) 和大表面天线的推动下，凸显了在集成信息论 (IT) 和电磁学 (IT) 的通信系统中对物理一致的模型和设计工具的需求。 EM）理论。在本文中，我们提出了一个用于表征和设计可编程 EM 环境的综合框架，该框架基于严格的 EM 参数，并通过使用矩阵运算符的线性图表示。该框架能够确定系统的 EM 传递函数和 IT 中使用的通道矩阵，以及它们作为可编程参数函数的关系。考虑到电磁量到 IT 信号的映射是通过天线结构中端口的存在而发生的，使用该框架，我们分析了端口在潜在自由度 (DoF) 方面施加的约束，并建立了基本限制大表面天线的自由度。为了证明该框架的实用性和有效性，我们提供了与 RIS 的表征和优化特别相关的示例。