宽阻带二阶带通频率选择表面研究

Study on wide stopband second-order bandpass frequency selective surface

为了得到宽阻带二阶带通频率选择表面,采用三层金属层结构和两层相等的介质构成频率选择表面的微结构,阐述了宽阻带二阶带通频率选择表面的结构.采用理论计算和HFSS仿真软件进行了仿真设计,窄带理论计算结果和仿真结果一致性较好,均具有二阶带通的频率特性,仿真设计结果具有宽阻带特性,该二阶带通频率微结构单元的容差性和频率稳定性较好.设计了单元尺寸为0.017λ×0.017λ,厚度为λ/59的频率选择表面,其中λ为自由空间的波长.制作实物并测试了频率特性,实测和仿真结果一致性较好,中心频率为0.74 GHz,阻带为0.9~14.9GHz,整个阻带内的抑制度大于15 dB,相对带宽为5%,带内插损小于0.4 dB.

In order to obtain a wide stopband second-order frequency selective surface(FSS),the microstructure of FSS with three metal layers and two equal dielectric layers was adopted. The structure of a wide stopband second-order bandpass frequency selective surface was described. The results of the equivalent circuit theoretical calculation are in good agreement with the simulation design result of HFSS software, and both have the frequency characteristics of second-order bandpass. The simulation results of the HFSS software have the characteristics of wide stopband. The second-order bandpass frequency selective surface micro-structural element has good tolerance and frequency stability.A frequency selective surface(FSS) with a cell size of 0.017λ×0.017λ and a thickness of λ/59 was designed. λ is the wavelength of free space. The prototype was made and the frequency characteristics were tested.The results of measurement and simulation are in good agreement,the central frequency is 0.74 GHz,and the stopband is from 0.9 GHz to 14.9 GHz. The rejection in the stopband is more than 15 dB, the relative bandwidth is 5%,and the insertion loss is less than 0.4 dB.