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中国物理学会期刊

可重构超构表面实现L波段波束动态调控及信息调制

CSTR: 32037.14.aps.74.20241668

Reconfigurable metasurface achieved dynamic beam control and information modulation of L-band beams

CSTR: 32037.14.aps.74.20241668
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  • 本文提出一种工作在L波段的宽带可重构转极化超构表面设计方法, 并实现了二进制幅移键控(binary amplitude shift keying, BASK)和二进制相移键控(binary phase shift keying, BPSK)两种调制方式的超构表面信息直接调制. 通过控制超构表面单元结构上的开关二极管通断状态, 可在1.17—1.66 GHz频段改变单元的转极化反射幅值和相位, 并通过对其幅相分布特性的实时编码实现波束调控与信息调制. 在此基础上, 构建了基于BASK和BPSK两种调制方式的超构表面新型无线通信系统, 实现了对数字信息的实时调制与传输. 本文提出的超构表面及其设计方法有望在信息传输、卫星通信等应用中发挥作用.

     

    In this paper, a method of designing broadband reconfigurable polarization-converting metasurface operating in L-band is proposed. This method can also be used to directly modulate the information by using two modulation modes: binary amplitude shift keying (BASK) and binary phase shift keying (BPSK). Switching the ON/OFF state of PIN diode can be used to modify the amplitude and phase responses of the cross-polarized reflection of the element in a frequency band of 1.17–1.66 GHz, thereby creating a 1-bit digital coding meta-atom. By changing the real-time coding patterns of amplitude and phase, the reconfigurable metasurface can control beams and information modulation. Simulation results show that by changing the coding patterns of the metasurface, twin-beams and four-beams with different reflection angles can be obtained which fully validates the control ability of dynamic far-field beam. As an experimental verification, a reconfigurable metasurface consisting of 10×10 meta-atoms is fabricated, and its beam control and information modulation functions are tested. The far-field patterns of the metasurface with different coding phase distributions are measured. Furthermore, modulation signals of varying high/low voltage levels and rates are loaded onto the metasurface, in order to control its modulation mode and rate. The modulated signals reflected from metasurface are captured by a high-speed radio-frequency (RF) oscilloscope at varying rates and reflection angles, and then demodulated so as to recover the original information. On this basis, a metasurface wireless communication system based on BASK and BPSK is constructed to transmit digital image information in a real-world environment. In the experiment, the image is first represented by a sequence of 0 bit and 1 bit, corresponding to the operational state sequence of the metasurface used for transmitting information. The field programmable gate array (FPGA) is then used to generate signals with high and low voltage levels in real time according to the sequence of working states of the metasurface, and to modulate the carrier signal irradiated onto the metasurface. Therefore, the signal is converted into a modulated signal and received by the antenna. Finally, the signal is demodulated by the universal software radio peripheral (USRP) and transmitted to the terminal equipment, yielding the constellation diagrams and enabling the recovering of the images. The image information recovered under both modulation schemes verifies that the system can achieve real-time modulation and transmission of digital information. The proposed metasurface and the design method may be used in many fields, such as satellite communications and digital broadcasting.

     

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