基于反射型超表面的超宽带涡旋波生成

由于轨道角动量的模态正交性,涡旋波的应用已成为提升信道容量的关键。然而,现有的涡旋波产生装置存在带宽窄、效率低、结构复杂等缺点,不利于无线通信系统信号的高效传输。文章利用 Pancharatnam-Berry相位原理,提出了 1种用于产生涡旋波的反射型超表面,能覆盖 8.6~19.3 GHz(相对带宽 76.7%)的频率范围,且在整个工作频带内入射平面波转换为反射涡旋波的效率达 80%以上。为验证所提超表面结构的性能,模拟了由不同旋转角的单元结构组成的超表面反射阵列,在右旋圆极化波的激励下,产生了期望模式数 l= 2的轨道角动量涡旋波,其数值模拟结果与理论相符。提出的超表面具有工作频带宽、模式纯度较高、低剖面、易于制作等优点,为超宽带涡旋波的产生提供了新的参考。

Generation of Ultra-Wideband Vortex Waves Based on Reflective Metasurface

Because of the orthogonality of the orbital angular momentum, the application of vortex waves has become the key to improve the channel capacity. However, the existing vortex generation device has the disadvantages of narrow band width, low efficiency and complex structure, which is not conducive to the efficient transmission of wireless commu-nication system signals. Based on the Pancharatnam-Berry phase principle, a reflective metasurface for generating vortex waves is proposed, which can cover the frequency range of 8.6~19.3 GHz (relative bandwidth 76.7%), and the conversion efficiency of incident plane waves into reflected vortex waves in the entire operating band is more than 80%. In order to verify the performance of the proposed metasurface structure, a metasurface reflector array composed of elements with different rotation angles is simulated. The orbital angular momentum vortex waves with the desired mode number l= 2 are generated under the excitation of right-circularly polarized waves. The numerical simulation results are in agreement with the theory. The metasurface proposed has the advantages of wide working frequency band, high mode purity, low profile and easy fabrication, which provides a new reference for the generation of ultra-wideband vortex waves.