基于无线能量传输的近场聚焦超表面设计

      Near-field focusing metasurface design based on wireless energy transmission

      • 摘要: 针对传统的相位梯度近场聚焦超表面阵列单元相位值计算量大和相位分布复杂的问题,提出了一种改进的无线能量传输的近场聚焦超表面。该超表面采用十字和开口环结构的优化四层级联结构混合型周期单元,通过改变末端带有寄生枝节的外开口环张角角度实现360°线性相移。采用7个简化的单元对相位值进行全覆盖,设计加工了共包含13×13个周期单元、有效面积为117 mm×117 mm的近场聚焦超表面。实测结果表明,在13.72%的相对带宽内实现了最大聚焦效率62.91%和透射效率94.1%,在工作频率14 GHz实现了61.4 mm的焦深,实测结果与仿真结果具有较好的一致性。所设计的超表面展现出了对xy极化电磁波360°的相位控制,实现了平均−0.52 dB的透射损耗。该超表面具有设计简单、高透射效率和高聚焦效率的特点,为近场聚焦超表面的简化设计提供了解决思路。

         

        Abstract: This article proposes an improved near-field focused metasurface for wireless energy transmission, which solves the problems of large phase value calculation and complex phase distribution in traditional phase gradient near-field focused metasurface array units. The metasurface adopts a hybrid periodic element with a cross and open ring structure, and achieves a 360° linear phase shift by changing the angle of the outer open ring with parasitic branches at the end. A near-field focusing metasurface with 13×13 periodic elements and an effective area of 117 mm ×117 mm is designed and processed by fully covering the phase values using seven simplified elements. The measured results show that the maximum focusing efficiency of 62.91% and transmission efficiency of 94.1% are achieved within a relative bandwidth of 13.72%, and a focal depth of 61.4 mm is achieved at a working frequency of 14 GHz. The measured results are in good agreement with the simulation results. The designed metasurface exhibits 360° phase control of x and y polarized electromagnetic waves, achieving an average transmission loss of −0.52 dB. This metasurface has the characteristics of simple design, high transmission efficiency, and high focusing efficiency, providing a solution for the simplified design of near-field focusing metasurface.

         

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