基于小型化结构的各向同性负磁导率材料与左手材料

提出了一种双面环各向同性结构单元模型, 理论与实验研究了其微波电磁谐振行为. 结果表明: 在电磁波平行入射和垂直入射条件下, 该结构可在同一频段实现磁谐振, 且在谐振频段磁导率为负; 当电磁波以不同角度斜入射时, 其产生负磁导率频段也保持不变, 即该结构的电磁特性不依赖于入射角度, 双面环结构具有各向同性的特点. 将双面环结构与金属线结构组合, 该组合结构具有负折射率. 另外,双面环结构还具有小型化的优点, 在不增加结构单元几何尺寸的情况下, 通过在结构单元中引入金属化过孔的方法, 增加结构单元的电长度, 可使谐振频率大幅度地向低频方向移动, 使其在低频工作时 仍保持小型化的优点. 在双面环结构中引入金属化过孔技术可使谐振单元的几何尺寸减小50%, 在微波器件、滤波器、天线等领域有广阔的应用前景.

Isotropic negative permeability metamaterials and left-handed metamaterials based on miniature structure

We propose an isotropic structure based on double split-ring resonator. We investigate experimentally and numerically the electromagnetic resonant properties of the proposed structure. The result shows that when the electromagnetic wave transmits in the directions parallel and perpendicular to the plane of the split ring resonator, respectively, the resonant bands having the negative permeability both arise at the same frequencies. However, when the electromagnetic wave transmits with oblique angle, the resonant characteristic is still unchanged. That is to say, resonant characteristic of the proposed structure is independent of incidence angle. This result indicates that the proposed structure is an isotropic medium. Combining the proposed double split-ring resonator structure with the wires, the left-handed metamaterial with negative refractive index can be obtained. In addition, the proposed structure has the merit of the miniaturization due to adding the metallic via-hole, which can increase the electric length of the structure. As a result, the resonant frequency of the structure shifts toward lower frequency greatly without increasing the dimension of the structure, and then the structure is still compact in the low frequency case. The introduction of the metallic via-hole can reduce the dimension of the structure by 50%. Therefore, the proposed structure will be a good candidate in the microwave applications such as antennas, filter, among others.