为实现在中、远红外两个大气窗口的低透过率, 设计了一种基于六边形环状结构的双屏红外频率选择表面(FSS), 利用CST电磁软件进行仿真分析, 发现该FSS在3~5 μm和8~14 μm两个波段内的平均透过率低于2.5%, 实现了红外波段的双阻带; 采用表面电流模式分析法和有效介质理论分析了该FSS的滤波机理, 发现不同谐振点处由于屏间耦合或屏内单元间的耦合在谐振单元表面感应出对称分布的电流从而使散射总场增强, 形成增强型反射, 即比较理想的红外光阻带; 最后研究了电磁波的极化方式、入射角度、介质属性以及结构参数对FSS传输特性的影响。结果表明该FSS具有良好的偏振稳定性和角度稳定性, 介质属性和结构参数对其传输特性有较大影响。

In order to get the low transmission rate in both mid and far infrared atmospheric windows, an infrared frequency selective surface(FSS) composed of two layers based on hexagonal ring structure was designed. Simulation analysis using CST electromagnetic software shows that the frequency selective surface has two stopbands in both 3-5 μm and 8-14 μm, of which the average transmission is lower than 2.5%. Therefore, this frequency selective surface realizes two stopbands in infrared wavelengths; the filtering mechanism of the frequency selective surface was analyzed based on the method of surface current model analysis and the effective medium theory. And it was found that the inducted current on the surface of units was symmetrical in different resonance points, which enhanced the total scattering-field and led to the enhanced reflection. That was the ideal infrared stopband. The inducted current was produced by the coupling between screen and the coupling between unit in a screen; In the end, the effect of electromagnetic wave polarization mode, incident angle, dielectric layer properties and structural parameters on the transmission properties of the frequency selective surface was researched. The results reveal that the transmission of FSS is insensitive to polarization mode and incident angle, while the dielectric layer properties and structural parameters are important factors to the transmission.