Reconfigurable intelligent surfaces (RISs) are gaining huge momentum in the field of wireless communications due to the paradigm shift that they bring. Indeed, they allow making any environment electromagnetically smart and dynamically reconfigurable for more efficient and greener wireless communications. As physicists, we proposed to use electronically tunable metasurfaces to shape the electromagnetic waves carrying our wireless communications in reflection almost ten years ago, inspired by some works that we and colleagues did in the field of wave control in complex media. In this article, we review the seminal works that led us to propose this concept, starting from the original one that is time reversal. Then, we propose a physicist’s point of view of RISs using a comparison with phase conjugation. Finally, we highlight what we think are their limitations, relying on both our knowledge of wave control and our study of them over a decade.

中文翻译：

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复杂媒体中无线通信的波前整形：从时间反转到可重新配置的智能表面


由于可重构智能表面（RIS）带来的范式转变，它们在无线通信领域获得了巨大的发展势头。事实上，它们可以使任何环境变得电磁智能并可动态重新配置，以实现更高效、更环保的无线通信。作为物理学家，受到我们和同事在复杂介质波控制领域所做的一些工作的启发，我们在大约十年前提出使用电子可调超表面来塑造反射中携带无线通信的电磁波。在本文中，我们回顾了导致我们提出这一概念的开创性工作，从最初的时间逆转开始。然后，我们通过与相位共轭的比较提出了物理学家对 RIS 的观点。最后，我们根据我们对波浪控制的知识和十多年来对它们的研究，强调了我们认为它们的局限性。