一种基于有源频率选择表面的可调吸波体特性分析

Performance analysis of a tunable absorber based on active frequency selective surface

[目的]周期结构吸波体可有效吸收入射电磁波并降低目标反射特征。提出一种基于有源频率选择表面(AFSS)的微波吸收体,通过加载PIN二极管,实现对吸波体频带范围的动态调控。[方法]首先,利用电磁仿真软件CST研究吸波体结构的可调控特性,探究PIN二极管等效电阻随偏置电流变化时吸波体反射率改变的情况;然后,采用多反射干涉理论分析多层结构中电磁波传播反射的特性,确定理想吸波情况下不同路径电磁波的幅度和相位条件;最后,加工实物样件在微波暗室进行测试和验证。[结果]结果表明,加载PIN二极管后,吸波体反射率随之改变,且在2.5~9.1 GHz频带范围灵活可调。[结论]研究成果在武器装备电磁隐身设计方面具有一定应用价值。

[Objectives]A periodic absorber can absorb incident electromagnetic waves and effectively reduce the reflectivity of a target.To this end,a novel microwave absorber based on an active frequency selective surface(AFSS)is proposed in this paper.The absorption frequency bandwidth can be dynamically adjusted by adding one PIN diode to the unit cell.[Methods]First,the tunable reflection performance of the proposed absorber is studied by means of a full-wave electromagnetic simulator CST in order to investigate the reflectivity of the absorber diode as the equivalent resistance of the PIN diode changes with different forward current.The propagation and reflection properties of electromagnetic waves in a multi-layer structure is then analyzed using multi-reflection interference theory so as to quantitatively illustrate the magnitude and phase condition with regard to the near unity absorption.Finally,an experiment is conducted on a fabricated absorber to verify its effectiveness in an anechoic chamber.[Results]The results indicate that the reflectivity of the absorber can be effectively controlled within the range of 2.5-9.1 GHz after adding the PIN diode.[Conclusions]The results of this paper have the potential to be applied in the electromagnetic stealth technology of weapons and equipment.