State Key Laboratory of Millimeter Waves, Southeast University, Nanjing, 210096, China.
Synergetic Innovation Center of Wireless Communication Technology, Southeast University, Nanjing, 210096, China.
Nat Commun. 2018 Oct 18;9(1):4334. doi: 10.1038/s41467-018-06802-0.
The recently proposed digital coding metasurfaces make it possible to control electromagnetic (EM) waves in real time, and allow the implementation of many different functionalities in a programmable way. However, current configurations are only space-encoded, and do not exploit the temporal dimension. Here, we propose a general theory of space-time modulated digital coding metasurfaces to obtain simultaneous manipulations of EM waves in both space and frequency domains, i.e., to control the propagation direction and harmonic power distribution simultaneously. As proof-of-principle application examples, we consider harmonic beam steering, beam shaping, and scattering-signature control. For validation, we realize a prototype controlled by a field-programmable gate array, which implements the harmonic beam steering via an optimized space-time coding sequence. Numerical and experimental results, in good agreement, demonstrate good performance of the proposed approach, with potential applications to diverse fields such as wireless communications, cognitive radars, adaptive beamforming, holographic imaging.
最近提出的数字编码超表面使得实时控制电磁波（EM）成为可能，并允许以可编程的方式实现许多不同的功能。然而，当前的配置仅进行空间编码，并未利用时间维度。在这里，我们提出了一种时空调制数字编码超表面的通用理论，以在空间和频率域同时对电磁波进行操控，即同时控制传播方向和谐波功率分布。作为原理验证的应用示例，我们考虑了谐波波束转向、波束成形和散射特征控制。为了验证，我们实现了一个由现场可编程门阵列控制的原型，该原型通过优化的时空编码序列实现了谐波波束转向。数值和实验结果吻合较好，证明了该方法的良好性能，有望应用于无线通信、认知雷达、自适应波束形成、全息成像等多个领域。
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