基于超材料的超宽带吸波研究

发布时间：2018-07-05 12:04

本文选题：电磁超材料 + 超宽带吸波　；参考：《西南大学》2017年硕士论文

【摘要】：电磁超材料是一种人工复合结构,由于其反常的电磁特性受到了国内外学者的广泛关注。基于超材料的吸波与传统的吸波材料相比具有质量轻、厚度薄、吸收率高等优点,被广泛应用于隐身技术、无损探测、太赫兹成像、天线等领域。本论文以拓宽吸波带宽为目标,主要开展了如下工作:(1)在微波段,通过在一个周期内放置四个不同尺寸的金字塔形单元,提出了梯度分布的金字塔形吸波结构。研究结果表明,对于9层结构(总厚度为4.122 mm),在8~14 GHz吸收率达到90%以上;对于13层结构(总厚度为4.134 mm),在7~21.5GHz吸收率达到90%以上。该结构对TE和TM极化都有效,且在较大的入射角度范围内吸收率都保持了高吸收率。进一步分析发现,尺寸较大的谐振单元的高阶模对宽频吸收有很大的贡献,与以往只考虑基模的吸波机理有所不同。(2)在红外波段,通过把四个不同尺寸的五边形谐振单元嵌入到一个周期内,提出了新型的超宽带吸波结构。单层结构在7.8~12.1μm对TE和TM极化吸收率均达到90%以上;双层结构在5.17~13.73μm对TE和TM极化吸收率均达到90%以上。通过研究金属层的电流和磁场分布,发现在谐振频点处电谐振和磁谐振同时存在,并且谐振波长跟表层金属的尺寸成正比关系。微波段的吸波在雷达隐身方面有重要的应用,而红外波段的吸波在辐射冷却方面有重要的应用。因此,本文工作在这两方面都有重要的实用价值。
[Abstract]:Electromagnetic supermaterial is a kind of artificial composite structure. Compared with traditional absorbing materials, the microwave absorbing materials based on metamaterials have the advantages of light weight, thin thickness and high absorptivity. They are widely used in stealth technology, nondestructive detection, terahertz imaging, antenna and other fields. The main work of this thesis is as follows: (1) in the microwave section, four pyramidal units with different sizes are placed in a period, and the gradient distribution pyramid absorbing structure is proposed. The results show that for 9 layers (the total thickness is 4.122 mm), the absorptivity is more than 90% at 814 GHz), for 13 layers (the total thickness is 4.134 mm), the absorptivity is more than 90% at 721.5 GHz). The structure is effective for both te and TM polarization, and the absorptivity remains high in the range of larger incidence angle. Further analysis shows that the higher-order modes of the larger resonant elements have a great contribution to the broadband absorption, which is different from the previous absorption mechanism which only considers the fundamental modes. (2) in the infrared band, A novel ultra-wideband (UWB) absorbing structure is proposed by embedding four pentagonal resonant elements of different sizes into one period. The polarization absorptivity of te and TM in monolayer structure is above 90% for te and TM, and that for double layer structure is above 90% for te and TM at 5.170.73 渭 m. By studying the distribution of current and magnetic field in the metal layer, it is found that both the electric resonance and the magnetic resonance exist at the resonance frequency point, and the resonant wavelength is proportional to the size of the surface metal. Microwave absorption plays an important role in radar stealth, while infrared wave absorption has important applications in radiation cooling. Therefore, the work of this paper has important practical value in these two aspects.
【学位授予单位】：西南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB34

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