吸波材料与FSS复合的隐身技术研究进展

吸波材料通过把电磁波转化为其它形式的能量来降低目标的雷达散射截面,从而实现目标隐身的目的.频率选择表面(FSS)是一种具有二维周期性结构的滤波结构,主要在滤波器上使用.在总结了吸波材料作用原理和FSS结构分析方法的基础上,介绍了FSS结构和吸波材料复合构成的隐身技术的研究进展.     

利用容性频率选择表面改善单层雷达吸波材料吸波性能

本文分析了等效电路法对含容性频率选择表面(capacitive FSS)单层吸波材料(RAM)反射率计算的不足,并用有限元法对此结构吸波材料吸波性能进行了计算。结果表明:当FSS位于较靠近金属背衬位置时,反射率曲线出现双峰,带宽增加;当其位于吸波材料表面时可以明显改善吸波材料低频性能。通过实验验证,计算与实验结果较吻合,两者均证明容性FSS能有效改善单层雷达吸波材料的吸波性能,具有较好的应用前景。     

干涉型多层吸波材料研究

综合介绍了干涉型多层吸波材料的吸波原理及其国内外研究现状，并分别研究了干涉型多层吸波材料三种基本类型：一般干涉型吸波材料、Jauman吸收体和频率选择表面（FSS）吸收体的一般结构、应用以及分析与方法，得出FSS吸收体较之其他类型具有更优的吸收性能和更高的实用价值，最后指出了干涉型吸波材料发展的新方向是有源FSS吸收体。     

嵌入分形频率选择表面的低频超薄吸波层的设计

研究了频率选择表面对超薄多层微波吸波体在低频(L和S频段)吸波性能的影响. 分别采用硫化工艺和激光刻蚀方法制备出传统的微波吸收材料(MAM)--橡胶板和FSS层, 然后利用它们合成多层微波吸波体(MMA)样品, 在NRL弓形法测试系统中测量该样品的反射率. 发现随着FSS层在传统吸波材料层中的引入, 确实可以增强整个多层吸波体在低频段的吸波性能. 实验结果显示, 当两个FSS层在多层吸波体中适当排列时, 可以在1 GHz得到一个–3.49 dB的反射率峰值, 最大反射峰值可达–9.35 dB, 这时的样品厚度是1.8 mm. 本研究为吸波材料的吸波性能向低频段的拓展提供了一种有效的方法.     

含容性频率选择表面铁氧体吸波材料的实验研究

通过热压成型工艺制备了含容性FSS结构的铁氧体复合吸波材料,按GJB2038-94标准,利用Agilent公司的矢量网络分析仪PNA8363B采用弓形测量法在8～18GHz频率范围对复合材料的反射率进行测试.研究结果表明,FSS的缝隙宽度、缝隙间距、FSS结构的方块电阻以及FSS结构的放置位置对复合材料的吸波性能都有很大影响.这些参数都存在一个最佳值,在其他条件不变的情况下,缝隙宽度为5mm,缝隙间距为7.2mm,FSS方块电阻为60Ω/□时,复合材料的吸波性能最好.FSS在复合材料中间层相比在面层和反射层,复合材料具有较好的吸波性能.通过设计FSS结构的频率特性可以达到改善材料吸波性能的目的,为高性能吸渡材料的设计提供一条可行的途径.     

雷达吸波材料的研究进展

根据电磁波在介质中的传播理论,详细地介绍了雷达吸波材料的吸波原理;综述了各种雷达吸波材料的特点、性能、应用现状以及发展趋势;列举了几种新型雷达吸波材料的吸波原理、吸波性能与应用现状;展望了雷达隐身材料的发展趋势。     

新型轻质雷达吸波材料的应用研究及进展

综述了目前国内外轻质雷达吸波材料的研究动态,详细介绍了具有发展前景的空心微珠吸波材料、碳纳米管吸波材料、导电高聚物吸波材料、纳米吸波材料和智能隐身材料等新型轻质雷达吸波材料的隐身机理及最新研究状况,并对雷达隐身材料应用技术的未来做了展望.     

雷达波隐身技术及雷达吸波材料研究进展

随着雷达技术的迅猛发展,雷达吸波材料(Radar absorbing materials,RAM)在军事装备隐身防御系统中的作用日趋重要。叙述了雷达波隐身技术的工作原理、吸波材料的损耗机制,综述了BaTiO3、铁氧体、铁(镍)氮化物、陶瓷材料、碳纳米管等雷达波吸收剂的研究现状及应用,最后展望了雷达吸波材料的发展趋势和研究发展的重点。     

雷达隐身技术的研究现状及其展望

叙述了雷达隐身技术的工作原理、类型及研究现状,综述了雷达吸波涂层中使用的吸收剂、胶粘剂和助剂,并介绍了以聚氨酯为胶粘剂的涂层基体,对聚氨酯复合材料进行了展望.回顾了雷达吸波材料的研究和发展,介绍了雷达吸波材料若干新的发现、性能及应用,同时展望了雷达吸波材料的发展趋势和研究发展的重点.     

吸波材料的研究进展

阐述了雷达吸波材料在隐身技术中的重要作用及其吸波原理,综述了石墨吸波材料、铁氧体吸波材料、陶瓷吸波材料、导电高聚物、视黄基席夫碱材料等的特点及研究现状,并提出雷达吸波材料未来的研究方向为不同类型吸波材料的复合。     

EM characteristics of the RAS composed of E-glass/epoxy composite and single dipole FSS element

From the methods to reduce radar cross section (RCS) such as shaping of the target, radar absorbing material (RAM), and radar absorbing structure (RAS), the RAS composed of frequency selective surface (FSS) screens and low-loss composite materials is used widely because the FSS screen transmits or reflects electromagnetic (EM) waves selectively and the composite material withstands external loads. In this study, the RAS composed of the E-glass/epoxy composite and single dipole FSS element was fabricated by printed circuit board (PCB) manufacturing process, and their EM transmission characteristics, such as a resonant frequency, a minimum transmission loss, and a transmission bandwidth, were measured in the X-band frequency range by the free space method with respect to the size of dipole element and its periodicity of array.     

Novel optimization method of single square FSS impinged and cascaded radar absorbing composites

It is well known that radar absorbing potentiality of existing magneto-dielectric composites can be significantly enhanced by the application of frequency selective surface (FSS) and cascaded electromagnetic (EM) structures. But the optimization of such complex EM structures and validation of the adopted optimization strategy is still a very challenging task for the researchers. Therefore, in this study, an effective effort has been made for the optimization and the corresponding validation for Single Square FSS (SS-FSS) impinged and cascaded radar wave absorbers using advanced computational EM software’s like FEldberechnung fur Korper mit beliebiger Oberflache – a German acronym (FEKO) and high frequency structure simulator (HFSS). In addition, a critical analysis of dielectric constant (ε′) has been carried out to select the best combination of composites for the development of efficient radar wave absorbers. A comparison between optimized and simulated results have been carried out to examine the effect of advanced EM approaches over reflection loss (RL) characteristics of composite radar absorbing materials (CRAMs). A rapid change in radar absorption properties of composites has been observed after the application of SSFSS and cascading. A SS-FSS impinged composite has been found to provide a wide absorption bandwidth of 3.6 GHz at X-band. A cascaded absorber having layer thickness 1.8 mm provides a peak RL of ?42.6 dB at 10.6 GHz with an absorption bandwidth of 2.5 GHz. The strong agreement between mathematical model, HFSS and FEKO results clearly reflects the efficiency of adopted approach for distinct practical EM applications.     

十字型电阻贴片频率选择表面吸收体吸波性能研究

本工作用有限元法对十字型电阻贴片频率选择表面(FSS)吸收体的吸波性能进行了研究,结果表明:改变十字型电阻贴片FSS的周期排列方式、周期尺寸、FSS单元的尺寸、FSS的方阻、介质层厚度均可对其吸收峰的位置、峰值以及带宽进行调节,并且调节范围较大,计算结果与实验结果基本吻合.研究表明这种结构具有传统Salisbury吸收体所不具有的优势.     

钩针工艺之于活性碳纤维/环氧树脂电路屏吸波复合材料的设计

通过钩针工艺将活性碳纤维(ACF)和玻璃纤维(GF)混编,提高了频率选择性表面(FSS)的可设计性和复杂性,制备了ACF钩针结构单元电路屏碳纤维/环氧树脂(ACF/EP)复合材料。研究了不同编织结构和ACF质量分数对复合材料吸波性能的影响。结果表明:ACF质量分数为100%的4针枣形FSS的ACF/EP复合材料和质量分数为50%的16针枣形FSS复合材料的最大反射损耗(RL)可以达到-50dB以上,有效吸收带宽(RL-10dB)达10GHz以上。复杂的钩针设计使ACF/EP复合材料的多孔结构增多,有效吸收带宽变宽,4针枣形结构具有较多不规整孔径使吸波效果显著。适量的ACF质量分数结合编织结构有利于获得理想的CF/EP吸波复合材料。     

Broad bandwidth of thin composite radar absorbing structures embedded with frequency selective surfaces

The three-layer ultrathin radar absorbing structure (RAS) involving a frequency selective surface (FSS) exhibiting excellent broad bandwidth properties is designed and fabricated. The EW and flaky carbonyl iron powders were used to produce two kinds of silicone rubber matrix magnetic composites for the top and the bottom layer, respectively. The electromagnetic parameters of the composites were measured in the frequency range of 2–18 GHz. The middle layer is an FSS in the form of double-square loops with four micro-split gaps in the middle of the outer loop. The results show that the proposed RAS can provide a 10 dB absorbing bandwidth of 13.2 GHz from 4.8 to 18 GHz (1.7 mm thickness) and a 10 dB absorbing bandwidth of 14.1 GHz from 3.9 to 18 GHz, covering C-band, X-band and Ku-band (2.0 mm thickness). A good match between simulation and measurement results demonstrates the validity of our design.     

宽频段雷达表面波衰减特征规律研究

目标物体上表面波的衰减吸收对目标的隐身起到很大的作用.研究了雷达吸波涂层对宽频段雷达表面波衰减吸收的规律以及频率选择表面与吸波涂层相结合的复合吸波涂层对宽频段表面波衰减吸收的规律.实验结果表明,低厚度的雷达吸波涂层就可以实现高频表面波的强衰减吸收,而频率选择表面与低厚度雷达吸波涂层相结合的复合涂层与雷达吸波涂层共同交替使用可以实现宽频段表面波的强衰减吸收,有望实现目标物体在宽频段范围内的高性能均衡雷达隐身.     

Metamaterial Inspired Radar Absorbers: Emergence,Trends and Challenges

The advances in metamaterial science and technology have raised the expectations of camouflage or stealth researchers to one order higher in terms of absorption characteristics. As metamaterial inspired radar absorbing structures are proving themselves as a good candidate with near unity absorption, feasibility towards hardware realization is necessary. Hence an extensive literature survey of metamaterial inspired radar absorbing structure has been carried out and reported in this paper along with the challenges and material issues. The various types of metamaterial structures that can be used as absorber have been provided along with simulation figures. To make the review more useful, graphene and carbon nanotube (CNT) based radar absorbing structures are also included along with their simulation and fabrication techniques.