The upcoming high-speed wireless communication systems will be hosted by millimeter- and sub-millimeter-wave frequency bands. At these frequencies, electromagnetic waves suffer from severe propagation losses and non-line-of-sight scenarios. A new wireless communication paradigm has arrived to resolve this situation through the use of reconfigurable intelligent surfaces (RISs). These metadevices are designed to reconfigure the wireless environment in a smart way. Traditional RIS designs based on the implementation of 2D configurations have been considered up to now. However, 3D structures enable an extra degree of freedom in the design that can be taken as an advantage for the development of improved RIS structures with advanced functionalities. This article proposes the implementation of a novel electronically reconfigurable RIS based on the use of 3D graphene meta-atoms. The reconfigurability lies in the graphene conductivity, easily tunable with a biasing voltage. Different conductivity values vary the meta-atom electromagnetic response, modifying the RIS functionality. A multi-objective optimization framework determines the optimal phase state of each meta-atom to accomplish the desired RIS performance. The operation of the RIS as an efficient beam steerer/ splitter, absorber, and polarization selector is validated with full-wave results.

中文翻译：

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基于超材料的可重构智能表面：石墨烯结构控制的 3D 超原子

即将推出的高速无线通信系统将由毫米波和亚毫米波频段托管。在这些频率下，电磁波会遭受严重的传播损失和非视距场景。通过使用可重构智能表面 (RIS)，一种新的无线通信范式已经出现来解决这种情况。这些元设备旨在以智能方式重新配置无线环境。迄今为止，已经考虑了基于 2D 配置实现的传统 RIS 设计。然而，3D 结构在设计中提供了额外的自由度，可以作为开发具有高级功能的改进 RIS 结构的优势。本文提出了一种基于 3D 石墨烯元原子的新型电子可重构 RIS 的实现。可重构性在于石墨烯的导电性，可通过偏置电压轻松调节。不同的电导率值会改变元原子电磁响应，从而修改 RIS 功能。多目标优化框架确定每个元原子的最佳相状态，以实现所需的 RIS 性能。RIS 作为高效光束转向器/分离器、吸收器和偏振选择器的操作已通过全波结果进行验证。多目标优化框架确定每个元原子的最佳相状态，以实现所需的 RIS 性能。RIS 作为高效光束转向器/分离器、吸收器和偏振选择器的操作已通过全波结果进行验证。多目标优化框架确定每个元原子的最佳相状态，以实现所需的 RIS 性能。RIS 作为高效光束转向器/分离器、吸收器和偏振选择器的操作已通过全波结果进行验证。