基于等效传输线理论的高效超宽带吸波体

Efficient Ultra-broadband Wave Absorber Based on Equivalent Transmission Line Theory

设计了一种基于氧化铟锡(ITO)薄膜的宽带吸波体,该吸波体在1.92~13.15 GHz之间实现90%以上吸波,绝对带宽达到11.12 GHz,相对带宽达到149.04%,完全覆盖了S、C、X波段,部分覆盖了L波段和Ku波段,峰值吸收率达到了99%以上。文中采用BP神经网络快速精确计算出方环与方贴片所构成的表面结构的等效阻抗;仿真对比了不同层数的影响并通过遗传算法对单元结构参数进行优化;基于等效传输线理论,解析表达优化后单元的反射率并与实际仿真结果进行了对比。仿真与测试结果显示不同极化和不同斜入射角情况下,单元的吸收率曲线变化较小,说明该结构具有极化不敏感和大入射角特性。提出的方法解决了传统经验公式对结构参数普适性不足的问题,由于使用ITO作为表面结构,其阻抗实部可调范围广,在理论上无需扫参,可以快速精确地设计任意波段吸波的吸波体。

In this paper,a broadband absorber based on indium tin oxide(ITO)thin film is designed,which can achieves more than 90%absorption between 1.92 GHz to 13.15 GHz.Absolute bandwidth is 11.12 GHz,and relative bandwidth reaches 149.04%,completely covering the S,C,X band,partly covering L band and Ku band,and achieve a peak absorption rate of over 99%.Firstly,BP neural network is used to calculate the equivalent impedance of the surface structure composed of square ring and square patch.Secondly,the effects of different layers are simulated and optimized by genetic algorithm.Finally,based on the equivalent transmission line theory,the reflectivity of the optimized unit is expressed analytically and compared with the simulation results.The simulation and test results show that the absorption curve of the element changes little under different polarization and different oblique incidence angles,indicating that the structure has the characteristics of polarization insensitivity and large incidence Angle.The method proposed in this paper solves the problem that the traditional empirical formula is not universal to the structural parameters.Since ITO is used as the surface structure,the real part of its impedance can be adjusted in a wide range.The absorbing body of any wave band can be designed quickly and accurately without sweeping parameters in theory.