A flexible ultra-broadband multi-layered absorber working at 2 GHz-40 GHz printed by resistive ink

A flexible extra broadband metamaterial absorber(MMA)stacked with five layers working at 2 GHz–40 GHz is investigated.Each layer is composed of polyvinyl chloride(PVC),polyimide(PI),and a frequency selective surface(FSS),which is printed on PI using conductive ink.To investigate this absorber,both one-dimensional analogous circuit analysis and three-dimensional full-wave simulation based on a physical model are provided.Various crucial electromagnetic properties,such as absorption,effective impedance,complex permittivity and permeability,electric current distribution and magnetic field distribution at resonant peak points,are studied in detail.Analysis shows that the working frequency of this absorber covers entire S,C,X,Ku,K and Ka bands with a minimum thickness of 0.098λ_(max)(λ_(max) is the maximum wavelength in the absorption band),and the fractional bandwidth(FBW)reaches 181.1%.Moreover,the reflection coefficient is less than-10 dB at 1.998 GHz–40.056 GHz at normal incidence,and the absorptivity of the plane wave is greater than 80%when the incident angle is smaller than 50°.Furthermore,the proposed absorber is experimentally validated,and the experimental results show good agreement with the simulation results,which demonstrates the potential applicability of this absorber at 2 GHz–40 GHz.

Broadband and conformal metamaterial absorber

In this study, a new broadband and conformal metamaterial absorber using two flexible substrates was proposed. Simulation results showed that the proposed absorber exhibited an absorption band from 6.08 to 13.04 GHz and a high absorption of 90%, because it was planar. The absorber was broadband as its relative absorption bandwidth was 72.8%. Moreover, the proposed absorber was insensitive to the polarization of the TE and TM waves. The absorber was ultra-thin; its total thickness was only 0.072 at the lowest operating frequency. Furthermore, different regions of absorption can be adjusted by lumping and loading two resistors onto the polyimide film, respectively. Moreover, compared with the conventional microwave absorber, the absorption bandwidth of the proposed absorber can be broadened and enhanced when it was bent and conformed to the surface of objects. Experimental and simulation results were in agreement. The proposed absorber is a promising absorbing element in scientific and technical applications because of its broad- band absorption, polarization insensitivity, and flexible substrates.

宽带柔性透明超材料吸波体设计

基于阻抗匹配原理提出一种具有宽带微波吸收、高灵活性和高透光性的超薄反射型超材料吸波体,该吸波体由硬度小且高度光学透明的导电膜和介质基板构成,可实现柔性和高透光性。电磁仿真结果表明:在8.22~22.76 GHz的频率范围内,吸波体的吸收率大于90%,吸收总带宽为14.54 GHz,相对吸收带宽达93.9%。由于谐振层图案的中心对称特点,吸波体表现出对电磁波极化不敏感的特性。此外,对于入射角小于60°的电磁波,它仍然表现出良好的吸收性能。该研究结果表明所提出的超材料吸波体在医疗设备、航空航天以及雷达隐身方面具有巨大的应用潜力。

可共形透明宽带超材料吸波体设计与分析

为解决传统吸波体吸收带宽窄和不可弯曲共形等问题,设计了一款柔性宽带超材料吸波体。该超材料由氧化铟锡(Indium tin oxide,ITO)电阻膜和聚对苯二甲酸乙二醇酯(Polyethylene Terephthalate,PET)组成,周期单元为ITO-PET-ITO三明治结构,通过表面电流和等效电路模型分析了结构单元的吸波机理。仿真结果表明,电磁波正入射时超材料在10~21.7 GHz频率范围内吸收率均高于90%,厚度仅为0.066λ_(0)(λ_(0)为最低截止频率对应的波长),结构单元的对称设计使其具有极化不敏感和较好的角度稳定性。将所提出的超材料进行实物加工和测量,实测结果与仿真结果基本吻合。该超材料具有柔性、透明、宽带、极化不敏感等特点,在电磁隐身和雷达吸波等领域具有潜在的应用价值。

基于电阻膜结构的宽带柔性透明超材料吸波器

研制了一种基于电阻型表面电材料氧化铟锡(ITO)的柔性透明电磁超材料吸波器,中间介质层选用聚对苯二甲酸乙二醇酯(PET)和聚甲基丙烯酸甲酯(PMMA)组合而成,谐振结构和底层反射板由ITO构成。设计的超材料吸波器的吸波率峰值可达0.999,吸波率约为0.9时的频段能够完全覆盖Ku到U波段,相对带宽为136%。同时超材料吸波器会表现出极化不敏感性以及宽角度入射的吸收特性。结合软件仿真与实验结果,利用电场分布图、谐振层结构特性和叠加结构吸收特性对吸收机理进行了分析,表明电阻膜的稳定阻抗实现了电磁波能量的强欧姆损耗,其中上、下层电阻膜结构分别作用在高频段和低频段,二者相互叠加实现了高效的宽频吸收性能。该吸波器在高温环境透明射频器件领域和常规电磁防护方面有潜在应用价值。