基于金属多环结构的多频段电磁超材料吸收器

设计了一种工作在微波频段的多频段超材料吸收器。该吸收器是典型的3层结构：顶层是由竖直站立的金属共面同心多环结构单元构成的二维周期 阵列，中间层是1层介质板，底层是1层连续金属板。利用电磁场数值模拟方法，模拟了顶层结构单元包含不同数目金属环时该超材料的吸收谱。结果表明，当顶层结构单元有n个环时，吸收谱上就会出现n个吸收峰。进一步的研究表明最高频率的吸收峰与顶层结构单元中多环结构整体具有的电偶极子模式的激发有关，而其他较低频率的吸收峰则与顶层结构 单元中相邻两环具有的捕获模式的激发有关。

Multiband Metamaterial Absorber Based on Metallic Multi-ring Structure

A multiband metamaterial absorber with typical sandwich structure in microwave region is proposed. The top layer is a square array with unit-cell of standing upright metallic concentric circular multi-ring structure, the middle layer is a dielectric slab, and the bottom layer is a continuous metallic slab. Using the fullwave simulation method, the absorption spectra of the metamaterial for different numbers of the rings in the unit-cell of the top layer are simulated. The results show that n absorption peaks appear when the unit-cell of the top layer owns n metallic rings. Detailed studies exhibit that the highest frequency absorption peak is related to the excitation of the electric dipole mode of the whole multi-ring unit-cell structure in the top layer, while other absorption peaks with lower frequencies are related to the excitation of the trapped-modes localized in the two corresponding neighbouring rings.