为实现中、远红外大气窗口的双波段低红外透过率, 设计了由 2层不同尺寸圆环单元构成的双屏红外频率选择表面(FSS), 仿真结果表明该 FSS在 3～5 μm和 8～12 μm波段形成两个平均透过率低于 5%的阻带。对 FSS表面电流分析的结果说明, 谐振单元表面感应出的对称分布电流使散射总场增强, 形成增强型反射, 而不同尺寸的谐振单元具有不同的谐振波长, 两层谐振单元共同作用形成了两个阻带。研究了入射角以及介质层属性(厚度、介电常数和损耗角正切)对 FSS传输特性的影响, 结果表明 FSS在两个大气窗口内具有良好的角度稳定性, 介质层介电常数对 FSS的传输特性有较大影响。

In order to get the low transmission rate in both far infrared atmospheric window and mid infrared atmospheric window, an infrared frequency selective surface (FSS) composed of two layers of ring units with different sizes is designed. Simulation results show that the FSS has two stopbands in both 3μm-5μm and 8μm-12μm, of which the average transmission is lower than 5%. According to the analytical results for the surface current of FSS, inducted current on the surface of units is symmetrical, which enhance the total scattering-field and lead to the enhanced reflex. While resonant units with different size have different resonant wavelength, two layers of units cooperatively form two stopbands. The paper analyzes the effect of the incident angle and dielectric layer properties (thickness, dielectric constant and loss tangent) on the transmission properties of FSS. The results revealed that the transmission of FSS is insensitive to the incident angle, while the dielectric constant is an important factor to the transmission.