具有双负折射率通带的双结构单元渔网电磁超介质的数值模拟研究

摘要

基于传统的"金属-电介质-金属"渔网状电磁超介质,平行和交叉排列具有不同介电常数介质板的两种单元,利用数值方法研究了两种排列方式下渔网电磁超介质的左手行为.与采用单一介质板相比,使用两种电介质板形成的双结构单元渔网结构能够使不同的单元在不同频率下谐振,表现出双负折射率通带.利用楔形结构和后向波模拟验证了两种排列方式下双结构单元渔网结构的负折射特性.利用双结构单元渔网结构,可以通过调节介质板的介电常数,同时在一个或多个频率带实现负折射,这为制作性能更为优良的多频带滤波器和变频通信微波器件等提供了一种可行方法.%Based on the traditional "metal-dielectric-metal" fishnet metamaterial, two new metamaterials were designed, each comprising four parallel or alternately arranged structural units of different permittivity of dielectric spacers as the unit cell. The left-handed properties for both fishnet structues were numerically investigated. The fishnet structure with two kinds of structural unit enabled different units to be excited at their corresponding frequencies compared with that of using single dielectric spacer, consequently resulting in dual left-handed bands. The behaviors of negative refractive index in both fishnet metamaterials were further validated by simulations of a wedge-shaped model and the backward wave propagation. One or more negative refraction bands in the fishnet metamaterials with two kinds of structural unit can be obtained by adjusting the permittivity of the spacer, which provided a feasible method for fabricating multi-band filters and variable-frequency microwave devices with better performances.