Bai Xudong, Zhang Fuli, Sun Li, Cao Anjie, Zhang Jin, He Chong, Liu Longhai, Yao Jianquan, Zhu Weiren
School of Microelectronics, Northwestern Polytechnical University, Taicang, 215400 Suzhou, China.
School of Physical Science and Technology, Northwestern Polytechnical University, Xi'an 710072, China.
Research (Wash D C). 2022 Jul 9;2022:9825903. doi: 10.34133/2022/9825903. eCollection 2022.
Programmable metasurfaces have great potential for the implementation of low-complexity and low-cost phased arrays. Due to the difficulty of multiple-bit phase control, conventional programmable metasurfaces suffer a relatively high sidelobe level (SLL). In this manuscript, a time modulation strategy is introduced in the 1-bit transmissive programmable metasurface for reducing the SLLs of the generated patterns. After the periodic time modulation, harmonics are generated in each reconfigurable unit and the phase of the first-order harmonic can be dynamically controlled by applying different modulation sequences onto the corresponding unit. Through the high-speed modulation of the real-time periodic coding sequences on the metasurface by the programmable bias circuit, the equivalent phase shift accuracy to each metasurface unit can be improved to 6-bit and thus the SLLs of the metasurface could be reduced remarkably. The proposed time-modulated strategy is verified both numerically and experimentally with a transmissive programmable metasurface, which obtains an aperture efficiency over 34% and reduced SLLs of about -20 dB. The proposed design could offer a novel approach of a programmable metasurface framework for radar detection and secure communication applications.
可编程超表面在实现低复杂度和低成本相控阵方面具有巨大潜力。由于多位相位控制的困难，传统可编程超表面的旁瓣电平（SLL）相对较高。在本论文中，一种时间调制策略被引入到1位透射式可编程超表面中，以降低所产生方向图的SLL。经过周期性时间调制后，每个可重构单元中会产生谐波，并且通过在相应单元上应用不同的调制序列，可以动态控制一阶谐波的相位。通过可编程偏置电路对超表面上的实时周期编码序列进行高速调制，每个超表面单元的等效相移精度可提高到6位，从而显著降低超表面的SLL。所提出的时间调制策略通过一个透射式可编程超表面在数值和实验上都得到了验证，该超表面获得了超过34%的孔径效率和约-20 dB的降低后的SLL。所提出的设计可为雷达探测和安全通信应用的可编程超表面框架提供一种新颖的方法。
