基于磁谐振器加载的宽频带超材料吸波体的设计

基于加载集总元件的磁谐振器设计了一种宽频带、极化不敏感和宽入射角的超材料吸波体.该吸波体的结构单元由加载集总元件的磁谐振器、介质基板和金属背板组成.仿真得到的加载集总元件和不加载集总元件情况下一维阵列结构吸波体的吸收率表明,相对于不加载集总元件的情况,加载集总元件的一维阵列结构吸波体能够实现宽频带吸波.仿真得到的集总电阻和集总电容取不同值时一维阵列结构吸波体的吸收率表明,集总电阻和集总电容都存在一个最佳值,此时吸波体的吸收率最高、吸收带宽最宽.仿真得到的基板有耗和无耗情况下一维阵列结构吸波体的吸收率表明, 关键词： 磁谐振器 集总元件 宽频带 超材料吸波体     

宽带透射吸收极化无关超材料吸波体

提出了一种新的基于磁性吸波体材料的具有低频透射和高频宽带吸收特性的超材料吸波体.该超材料吸波体在1 GHz的透射系数为-0.5 dB,具有较好的低频透射特性,可以实现对低频信号的相互通信;在频率大于8.4 GHz的频段,吸收率均大于80%,基本覆盖整个X波段和Ku波段,实现高频宽带吸收.此外,由于该超材料吸波体的单元金属周期结构具有较好的四重旋转对称性,因而是极化无关的.该透射吸收超材料吸波体设计简单,实用性强,具有较强的潜在应用价值.     

基于电阻型频率选择表面的低频宽带超材料吸波体的设计

基于电阻型频率选择表面(Resistance Frequency Selective Surface, RFSS) 设计了一种低频宽带、 极化不敏感和宽入射角特性的超材料吸波体. 该吸波体的基本单元由开槽十字型平面超材料(Cave Cross Planar Metamaterial, CCPM)、 RFSS、 电介质基板和金属背板组成. 采用FDTD方法数值模拟得到的结果表明: 相比于单纯的CCPM吸波体、 RFSS吸波体, CCPM和RFSS复合结构吸波体低频吸收特性得到极大改善, 在整个1-5 GHz频率范围内, 吸收率大于80%, 吸收峰值达到98%以上. 数值模拟得到的不同极化角和不同入射角下的吸收率表明: 该复合结构吸波体具有极化不敏感和宽角度吸收特性.     

基于磁/电介质混合型基体的宽带超材料吸波体的设计与制备

本文设计了一种基于磁/电介质混合型基体的宽带超材料吸波体, 吸波体基本单元由电阻膜、磁/电介质混合型基体以及金属背板组成. 采用时域有限差分法对超材料吸波体吸波性能进行了仿真, 使用遗传算法优化了反射率小于-10 dB的带宽. 仿真结果表明, 当超材料吸波体厚度为2.5 mm时, 在7.8–18 GHz频率范围内的反射率小于-10 dB, 具有厚度薄、宽带、极化不敏感等优点. 通过等效电路模型对其工作机理进行了分析与讨论. 最后制备样品进行测试, 测试结果与仿真结果一致.     

基于超材料的偏振不敏感太赫兹宽带吸波体设计

本文设计了一种基于超材料的偏振不敏感太赫兹宽带吸波体.吸波体包含两层金属和一层中间介质,表面金属层每一个周期单元由五种尺寸接近的金属块按照相邻不同的规律排列成5×5的方形阵列.各种尺寸金属块分别产生单峰谐振吸收,五个谐振吸收峰相互靠近从而产生宽带吸收.通过研究吸波体表面电流和电场z分量分布情况可知,入射太赫兹能量的吸收主要是由y方向上电场引起的电偶极子振荡和z方向上磁场引起的磁极化产生,而且金属层的欧姆损耗起主要作用.仿真结果表明,吸波体吸收率在80%以上的带宽约为1.2 THz,最高吸收率可达98.7%,半峰全宽(FWHM)为1.6 THz,该宽带吸波体的厚度约为中心波长的二十分之一,对偏振方向不敏感,且能实现大角度吸收,在太赫兹频段的电磁隐身、测辐射热探测器以及宽带通信等领域有潜在的应用价值.     

基于电磁谐振分离的宽带低雷达截面超材料吸波体

基于超材料的电磁谐振特性, 设计、制作了一种极化无关的宽带低雷达散射截面 (radar cross section, RCS)超材料吸波体. 通过场分布和反演法分析了其吸波机理, 利用波导法和空间波法测试了其吸波率和RCS特性. 理论分析表明: 在平面波的作用下, 该吸波体对某一吸波频率在不同的位置分别提供电谐振和磁谐振, 对不同的吸波频率, 利用不同的介质层提供主要的能量损耗, 从而有效减弱了电磁耦合, 保证了宽频带的强吸收特性. 实验结果表明: 设计的三层结构吸波体吸波率达90%以上的带宽是单层结构的4.25倍, RCS减缩10 dB以上的带宽为5.1%, 其单元尺寸为0.17λ, 厚度仅为0.015λ. 该吸波体的低RCS特性还具有极化无关、宽入射角的特点, 且通过改变吸波体的夹层结构可以实现工作带宽的灵活调节. 关键词： 超材料吸波体 雷达散射截面 宽带 电磁谐振     

基于宽带吸波体的微带天线雷达散射截面缩减设计

利用加载集总电阻的方式设计出一种极化稳定且宽入射角的宽带超材料吸波体(wide-band metamaterial absorber, WBMA), 在平面波垂直入射时, 其吸波半波功率带宽达12.7 GHz, 吸波率大于90%的带宽达10.42 GHz, 峰值吸波率达99.9%. 将其与微带天线共基板共接地板的方式加载, 制备出WBMA微带天线, 实现了天线宽频域内雷达散射截面(radar cross section, RCS)大幅缩减. 仿真与实测结果表明: 将WBMA加载于微带天线后, 天线的前向增益提高了0.53 dB, 整体辐射特性基本保持不变; 在不同极化波下, 天线的工作频带带内和带外等宽频域(6.95-17.91 GHz)内的单站RCS缩减大于3 dB以上, 最大缩减值达21.2 dB; 在天线的中心频点8 GHz处± 48°的宽角域内, 双站RCS缩减效果明显, 很好地实现了天线的宽频域大角度的隐身设计.     

基于宽边耦合螺旋结构的低频小型化极化不敏感超材料吸波体

设计、仿真并实验验证了基于宽边耦合螺旋结构的低频小型化超材料吸波体. 实验测试结果表明, 该超材料吸波体在1.39 GHz吸收率达到最大为98%, 其单元尺寸和总厚度均为6.8 mm, 约为1/32工作波长, 实现小型化窄带吸波. 由于吸波体中螺旋结构是旋转对称排列的, 因而其对垂直入射电磁波的极化方向是不敏感的. 此外, 该超材料吸波体对斜入射横电和横磁极化电磁波在60°时, 仍具有强吸收. 关键词： 超材料 吸波体 小型化     

基于集总元件和负微分元件的有源可调谐超材料传输线

针对无源超材料高色散、高损耗和均匀性差的缺点,利用集总元件和负微分元件设计、加工了一种微波频段的有源可调谐超材料传输线,并对其进行了测试.实验获得了具有散射参数随外加偏置电压改变而变化的电控可调谐特性以及衰减常数为负值的有源超材料传输线.     

A wideband metamaterial absorber based on a magnetic resonator loaded with lumped resistors

<正>A wideband metamaterial absorber（MA） based on a magnetic resonator loaded with lumped resistors is presented. It is composed of a one-dimensional periodic array of double U-shaped structured magnetic resonators loaded with lumped resistors,a dielectric substrate,and a metal plate.We simulated,fabricated,measured,and analyzed the MA. The experimental results show that the reflectance(S₁₁) is below -10 dB at normal incidence in the frequency range of 7.7 GHz-18 GHz,and the peak value is about—20 dB.Simulated power loss density distributions indicate that wideband absorption of the MA is mainly attributable to the lumped resistors in the magnetic resonator.Further investigations indicate that the distance between two unit cells along the magnetic field direction significantly influences the performance of the MA.     

Broadband low-frequency acoustic absorber based on metaporous composite

Broadband absorption of low-frequency sound waves via a deep subwavelength structure is of great and ongoing interest in research and engineering. Here, we numerically and experimentally present a design of a broadband low-frequency absorber based on an acoustic metaporous composite (AMC). The AMC absorber is constructed by embedding a single metamaterial resonator into a porous layer. The finite element simulations show that a high absorption (absorptance A>0.8) can be achieved within a broad frequency range (from 290 Hz to 1074 Hz), while the thickness of AMC is 1/13 of the corresponding wavelength at 290 Hz. The broadband and high-efficiency performances of the absorber are attributed to the coupling between the two resonant absorptions and the trapped mode. The numerical simulations and experimental results are obtained to be in good agreement with each other. Moreover, the high broadband absorption can be maintained under random incident acoustic waves. The proposed absorber provides potential applications in low-frequency noise reduction especially when limited space is demanded.     

Tunable broadband metamaterial absorber consisting of ferrite slabs and a copper wire

A tunable broadband metamaterial absorber is demonstrated at microwave frequencies in this paper.The metamaterial absorber is composed of ferrite slabs with large resonance beamwidths and a copper wire.The theoretical analysis for the effective media parameters is presented to show the mechanism for achieving the perfect absorptivity characteristic.The numerical results of transmission,reflectance,and absorptivity indicate that the metamaterial absorber exhibits a near perfect impedance-match to free space and a high absorptivity of 98.2% for one layer and 99.97% for two layers at 9.9 GHz.The bandwidth with the absorptivity above 90% is about 2.3 GHz.Moreover,the absorption band can be shifted linearly in a wide frequency range by adjusting the magnetic bias.This metamaterial absorber opens a way to prepare perfectly matched layers for engineering applications.     

低雷达散射截面的超薄宽带完美吸波屏设计研究

提出了一种基于PMA单元结构的超薄宽带完美吸波屏设计方法. 该方法将多层拓展带宽的技术与单层多谐振方法有机结合, 实现带宽拓展的同时, 保持了完美吸波屏结构简单、无集总元件的特点, 易于实际加工和应用. 以双层三谐振超薄宽带完美吸波屏为例, 结合其等效电路, 理论上验证了所设计吸波屏的吸波机理, 同时验证了方法的有效性. 仿真分析该吸波屏具有低雷达散射截面、极化不敏感和宽入射角的特征. 仿真和实测结果表明: 该吸波屏在厚度为0.01 λ的条件下, 具有14.1%的半波功率带宽;-3 dBsm的雷达散射截面缩减带宽为18.9%, 在法线方向的最大缩减量为23 dBsm, 在法向±40°内具有较好的雷达散射截面减缩效果. 关键词： 完美吸波屏 宽带 雷达散射截面 等效电路     

Solar broadband metamaterial perfect absorber based on dielectric resonant structure of Ge cone array and InAs film

The broadband metamaterial perfect absorber has been extensively studied due to its excellent characteristics and promising application prospect. In this work a solar broadband metamaterial perfect absorber is proposed based on the structure of the germanium (Ge) cone array and the indium arsenide (InAs) dielectric film on the gold (Au) substrate. The results show that the absorption covers the whole ultraviolet-visible and near-infrared range. For the case of A > 99%, the absorption bandwidth reaches up to 1230 nm with a wavelength range varied from 200 nm to 1430 nm. The proposed absorber is able to absorb more than 98.7% of the solar energy in a solar spectrum from 200 nm to 3000 nm. The electromagnetic dipole resonance and the high-order modes of the Ge cone couple strongly to the incident optical field, which introduces a strong coupling with the solar radiation and produces an ultra-broadband absorption. The absorption spectrum can be feasibly manipulated via tuning the structural parameters, and the polarization insensitivity performance is particularly excellent. The proposed absorber can possess wide applications in active photoelectric effects, thermion modulators, and photoelectric detectors.