IOE OpenIR  > 光电技术研究所博硕士论文
基于亚波长结构的电磁低散射调控技术研究
张昌磊
Subtype博士
2019-05
Degree Grantor中国科学院大学
Place of Conferral中国科学院光电技术研究所
Degree Name工学博士
Keyword低散射,亚波长结构,电磁吸收材料,双频,兼容低散射,动态
Abstract

隐身技术的核心是实现目标电磁特征的低散射设计,也可以称为目标低可探测技术。而电磁吸收材料作为电磁低散射调控技术的重要研究方向一直以来都是研究人员关注的热点。随着探测手段的多样化以及复合探测技术的快速发展,探测系统的目标识别和跟踪能力得到很大的提升。传统的电磁吸收材料难以满足电磁低散射调控技术的发展需求。亚波长结构的出现,为这一问题的解决提供了新的研究方向。亚波长结构材料由特定排布的阵列结构组成,是一种具有奇异电磁特性的人工结构材料。亚波长结构材料的一个核心因素是其阵列结构的周期远小于波长,在波矢匹配的条件下,材料中产生的高阶衍射级次会被束缚在结构内部而无法向自由空间传播。利用这一特性,通过巧妙设计可以增强损耗介质对电磁波的吸收效果,为电磁吸收材料的研究注入了新的设计理念,也带来了新的设计思路。

本文主要围绕亚波长结构电磁低散射调控技术展开研究,设计出四类电磁低散射材料,分别是基于亚波长结构的双频红外电磁吸收材料;微波红外兼容的电磁低散射透明材料;基于二氧化钒材料的双向及宽带动态可调电磁吸收材料;基于有源亚波长结构的多功能动态低散射材料。相关研究有望在针对复合探测的低散射领域发挥作用,推动电磁低散射调控技术的发展。论文的具体研究内容包括以下几点:

第一,提出了一种双频宽角电磁吸收材料的设计方法。该研究基于亥姆霍兹谐振以及局域表面等离子谐振在1.064 μm10.6 μm处实现了双频近完美吸收,吸收率达到99.7%以上,且该双频吸波材料的频带比高达10。通过全波电磁仿真,验证了该电磁吸收材料的宽角吸收和极化不敏感特性,同时通过电场电流分布,理论分析了电磁能量的耗散原理,进一步解释了双频电磁吸收材料的物理机制。

第二,提出了一种透明柔性的微波红外兼容电磁吸收材料的设计方法。根据基尔霍夫理论分析设计出了红外反射雷达透波的电容型频率选择表面,结合亚波长结构宽带电磁吸收理论实现了多波段复合的电磁吸收材料。计算结果和实验验证均表明,该亚波长结构材料在7.7-18 GHz内具有大于90%的高吸收率,即使在40度的斜入射下也能保持较强的吸收。另外,将该材料覆盖在金属柱上可以实现7.5-18 GHz范围内宽带雷达散射截面(Radar Cross Section, RCS)缩减性能。并且,该结构在大气窗口中具有0.23的低发射以实现红外目标低可探测性能。最后,由于透明材料氧化铟锡(Indium Tin OxideITO)膜和聚氯乙烯(Polyvinyl ChloridePVC)的使用,该材料保持了约30%的透光率。

第三,提出了一种基于VO2相变特性的新型电阻可调层。该电阻可调层通过电热效应能够实现等效电阻从18 Ω/sq300 Ω/sq的动态调控,基于这一特性构造出了双向动态电磁吸收材料和非平面宽带宽角动态电磁吸收材料。其中双向动态电磁吸收材料可在两个方向上实现吸收率从18%98%的大幅度动态调制;而非平面动态电磁吸收材料则能在曲面上实现从1.08 THz2.5 THz的宽带电磁吸收,且吸收幅度可动态控制。上述两种动态电磁吸收材料都具有较好的角度适应性。

第四,提出了基于亚波长结构的多功能电磁调控器件的设计方法,实现了RCS缩减调控、波束扫描、极化转化等电磁功能的动态重构。该材料的亚波长单元结构中同时集成了PINPositive-intrinsic-negative)二极管和变容二极管,通过改变偏置电压可产生180°位相差实现RCS缩减,进一步调制180°位相差的产生频段,可动态控制RCS的缩减频段;同时利用上述两种二极管的组合调控还产生了覆盖360°的连续反射位相差,实现了宽角波束扫描效果;此外进一步改变二极管的偏置电压配置,使材料在两个正交极化上产生90°-90°相位差,则实现了线极化和不同旋向圆极化状态的动态切换。上述三种电磁功能仅通过调控单层有源亚波长结构材料就能实现。

Other Abstract

Stealth technology is used to make military target undectable thourgh the low-scattering design, which can be also called as low observable technology. As a significant research direction in the stealth field, electromagnetic absorber is one of the most effective methods to achieve stealth by converting the incident wave into Ohmic loss. However, with the rapid development of composite detection technology, the target recognition and tracking capabilities of the detection system have been greatly improved, so that traditional electromagnetic absorbers cannot meet the continuous improvement of the stealth demand. The emergence of subwavelength structure provides a new route to solve this problem. Sub-wavelength structured materials consisted of array structures are artificial materials with special electromagnetic properties. Under the condition of wave vector matching, the high-order diffraction waves generated in the material can be trapped inside the structure and cannot propagate to free space. Thus, perfect absorption could be generated by the lossy medium through electric or(and) magnetic resonances, bringing in a novel way to design high-performance low scattering materials.

In this paper, we focused on the manipulation technology of electromagnetic low scattering materials. Four kinds of electromagnetic stealth materials have been designed as follows: Dual-band infrared electromagnetic absorber based on sub-wavelength structure; transparent and flexible microwave-infrared bi-stealth material; Bidirectional and broadband dynamically tunable electromagnetic absorber based on vanadium dioxide material; A multifunctional dynamic low scattering material based on an active sub-wavelength structure. The above methods can be developed for potential applications in the stealth field and promote the development of stealth technology. The main research contents of this paper include the following four points:

Firstly, a design method of a dual-band wide-angle infrared electromagnetic absorber is proposed. Dual-band near perfect absorptions at 1.064 μm and 10.6 μm based on Helmholtz resonance and localized surface plasmon resonance are achieved, and the absorptivity is over 99.7%. The wide-angle absorption and polarization insensitivity of the electromagnetic absorber have been also verified by full-wave electromagnetic simulation. Through the electric field and current distributions, the dissipative mechanism of electromagnetic energy is theoretically analyzed, and the physical mechanism of the dual-frequency electromagnetic absorber is further explained.

Secondly, a flexible and transparent microwave-infrared bi-stealth structure is proposed to avoid composite detection in microwave and infrared band. By combining the intrinsic material properties with proper design, the proposed flexible metamaterial can simultaneously achieve high absorption in microwave band, low emission in infrared band, as well as optical transparency. As a proof of concept, the measured results demonstrate that our structure exhibits wide-angle (40°), broadband (7.7-18 GHz) and high-efficiency (>90%) absorption. Besides, by further using our structure to cover a metallic column, a 10 dB radar cross section (RCS) reduction in 7.5-18 GHz is achieved. The thermal emissivity of our structure is about 0.23 in the infrared atmosphere window, which is closed to that of metal. Furthermore, the elaborately designed metamaterial keeps optical transparency and flexibility due to the use of indium tin oxide (ITO) films and polyvinyl chloride (PVC) substrates.

Thirdly, a novel electrically-controlled resistive layer (ECRL) based on VO2 phase transition characteristics is proposed. The effective resistance of ECRL is numerically verified to be tuned from 18 ohm/sq. to 300 ohm/sq by the electrothermal effect. Based on this characteristic, a bidirectional dynamic electromagnetic absorber and a non-planar wide band dynamic electromagnetic absorber are constructed. The bidirectional dynamic electromagnetic absorber can realize large-scale dynamic modulation of absorptivity from 18% to 98% in two directions, while the non-planar dynamic electromagnetic absorber can realize broadband electromagnetic absorption from 1.08 THz to 2.5 THz, and its absorption amplitude can be dynamically controlled. Both dynamic electromagnetic absorbers described above have good angular adaptability in the case of normal incidence.

Fourthly, the design method of multi-functional electromagnetic device based on sub-wavelength structure is proposed, which realizes the dynamic reconfigurable feature of electromagnetic functions such as RCS reduction control, beam scanning and polarization conversion. A PIN diode and a varactor diode are integrated in the unit cell of the sub-wavelength structure. By changing the bias voltage, 180° phase difference can be generated to achieve RCS reduction. Besides, the 180° phase difference generation band can be further modulated to dynamically control the reduced frequency band of RCS. At the same time, a continuous reflection phase difference covering 360° can be realized by controlling the above two diodes, which achieves wide-angle beam scanning effect. By further changing the bias voltage configuration of the diodes, the material can produce 0°, 90° and -90° phase differences on two orthogonal polarizations, enabling dynamic switching of linear polarization and different rotational circular polarization states. The above three electromagnetic functions can be realized only by regulating a single-layer active sub-wavelength structural material.

MOST Discipline Catalogue工学
Language中文
Document Type学位论文
Identifierhttp://ir.ioe.ac.cn/handle/181551/9087
Collection光电技术研究所博硕士论文
Recommended Citation
GB/T 7714
张昌磊. 基于亚波长结构的电磁低散射调控技术研究[D]. 中国科学院光电技术研究所. 中国科学院大学,2019.
Files in This Item:
File Name/Size DocType Version Access License
基于亚波长结构的电磁低散射调控技术研究.(5513KB)学位论文 开放获取CC BY-NC-SAApplication Full Text
Related Services
Recommend this item
Bookmark
Usage statistics
Export to Endnote
Google Scholar
Similar articles in Google Scholar
[张昌磊]'s Articles
Baidu academic
Similar articles in Baidu academic
[张昌磊]'s Articles
Bing Scholar
Similar articles in Bing Scholar
[张昌磊]'s Articles
Terms of Use
No data!
Social Bookmark/Share
All comments (0)
No comment.
 

Items in the repository are protected by copyright, with all rights reserved, unless otherwise indicated.