Anisotropic impedance surfaces activated by incident waveform
Anisotropic impedance surfaces activated by incident waveform
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DOI：
10.1515/nanoph-2021-0659
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发表时间：
2022-02
期刊：
影响因子：
7.5
通讯作者：
Haruki Homma;M. R. Akram;A. Fathnan;Jiyeon Lee;C. Christopoulos;H. Wakatsuchi
中科院分区：
文献类型：
--
作者：
Haruki Homma;M. R. Akram;A. Fathnan;Jiyeon Lee;C. Christopoulos;H. Wakatsuchi
各向异性阻抗表面已被用于控制表面波的传播，这使得包括射频（RF）和光学器件、传感、电磁兼容性、无线电力传输和通信在内的各个领域的应用受益。然而，一旦这些表面被制造出来，它们的响应是固定的。虽然可调谐阻抗表面已经通过利用功率相关的非线性元件引入，但这种调谐机制通常仅限于特定应用。在这里，我们提出了一种额外的机制，通过嵌入可通过入射波形类型控制的瞬态电路来实现可调谐的各向异性阻抗表面。通过在电路的开路和短路状态之间切换，可以在两个正交的方向上分别控制单元阻抗，从而从各向同性阻抗面转变为各向异性阻抗面。仿真结果表明，在3ghz频率下，短脉冲在x和y方向上都有很强的传播。但是，当波形变为连续波时，x方向的透光率降至26%，但y方向的透光率仍达到77%。因此，即使在相同的功率水平和相同的频率下，所提出的超表面也能够根据入射波形将表面波引导到特定的方向。我们的研究为表面波控制在从无线通信到传感和隐形设备等应用中的应用开辟了新的途径。
Abstract Anisotropic impedance surfaces have been used to control surface wave propagation, which has benefited applications across a variety of fields including radio-frequency (RF) and optical devices, sensing, electromagnetic compatibility, wireless power transfer, and communications. However, the responses of these surfaces are fixed once they are fabricated. Although tunable impedance surfaces have been introduced by utilizing power-dependent nonlinear components, such a tuning mechanism is generally limited to specific applications. Here we propose an additional mechanism to achieve tunable anisotropic impedance surfaces by embedding transient circuits that are controllable via the type of incident waveform. By switching between the open and short states of the circuits, it is possible to separately control the unit-cell impedances in two orthogonal directions, thereby changing from an isotropic impedance surface to an anisotropic impedance surface. Our simulation results show that a short pulse strongly propagates for both x and y directions at 3 GHz. However, when the waveform changes to a continuous wave, the transmittance for x direction is reduced to 26%, although still the transmittance for y direction achieves 77%. Therefore, the proposed metasurfaces are capable of guiding a surface wave in a specific direction based on the incident waveform even with the same power level and at the same frequency. Our study paves new avenues regarding the use of surface wave control in applications ranging from wireless communications to sensing and cloaking devices.