共查询到20条相似文献,搜索用时 31 毫秒
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提出一种单元电尺寸小、工作频带宽、损耗小、结构简单的异向介质设计方案,在1.7—2.7 GHz上所设计的异向介质结构单元电尺寸小于0.035,相对带宽达到45.5%,在整个工作频带上单个结构单元传输损耗小于0.75 dB.对由上述异向介质单元构成的半无限大异向介质平板的电磁波反射、透射特性进行了数值仿真分析,并提取出了电磁波在该异向介质平板中传播时的波数、相速、折射率以及该异向介质平板的有效介电常数和有效磁导率等一系列电磁特性参数,仿真与计算结果表明复波数的实部、相速以及折射率的实部在1.7—2.7 GHz的范围上为负值,并且在相同频带上,有效介电常数和有效磁导率的实部同时为负值,从而有效地验证了“后向行波效应”、“负折射效应”、“双负效应”等异向介质特有的电磁特性,对上述异向介质的存在性给予有力证明.
关键词:
异向介质
宽频带
小单元
介质参数 相似文献
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A planar left-handed metamaterial(LHM) composed of electric resonator pairs is presented in this paper.Theoretical analysis,an equivalent circuit model and simulated results of a wedge sample show that this material exhibits a negative refraction pass-band around 9.6GHz under normal-incidence and is insensitive to a change in incidence angle.Furthermore,as the angle between the arm of the electric resonators and the strip connecting the arms increases,the frequency range of the pass-band shifts downwards.Consequently,this LHM guarantees a relatively stable torlerence of errors when it is practically fabricated.Moreover,it is a candidate for designing multi-band LHM through combining the resonator pairs with different angles. 相似文献
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The design of the metamaterial that can exhibit negative refraction at two frequency bands is presented. The components of this metamaterial are cut wire pairs and continuous wires. The cut wire pairs structure in our sample can achieve the magnetic resonance at two frequency bands by appropriately designing the cut wire dimension. Through numerical simulation, the transmission property of the proposed dual band negative index metamaterial is investigated and its result shows that with the introduction of continuous wires, the stop bands for cut wire pairs (permeability μ<0) and the frequency band for continuous wires (permittivity ε<0) components would overlap and lead to the appearance of pass bands near the two magnetic resonance frequency bands. Its electromagnetic properties are then retrieved to demonstrate that the dual band left-hand behavior can be obtained in our sample structure. It is believed that our approach will be effective to make this kind of dual band negative refractive metamaterial based on the multiple magnetic resonances work at optical frequency. 相似文献
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提出了一种基于平行金属条和细金属线的双梯形二维超材料结构单元.该结构由介质板以及其两侧放置的一对反向对称梯形金属条组成.与传统二维超材料相比,该结构在电磁波平行入射时具有双左手频带特性,在电磁波双向入射情况下具有良好的左手频带拓展性,且结构易于制备.利用电磁仿真软件分别模拟电磁波垂直入射和平行入射条件下该结构的电磁性能.结果表明:该结构在两种入射情况下均能实现双负特性;梯形上底每增大0.5mm,双入射情况下结构的双负特性分别向高频移动0.2GHz和0.4GHz.该研究对基于平行金属条的左手材料的研究以及二维左手材料的发展具有参考价值. 相似文献
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基于裂缝谐振环结构的降频技术,首先设计了一种电尺寸较小的左手介质微带线单元,并根据电磁波在微带线上的传输和反射数据,分别计算了左手介质的有效介电常数和有效磁导率.之后针对左手介质八元阵列进行三维电磁仿真实验,结果表明该八元阵列在左手介质频段上具有独特的后向波效应,从而证实了该左手介质频段的存在.与传统的左手介质微带单元相比,阐述的左手介质单元的电尺寸减小了60%,而且结构简单,便于加工,适用于平面电路器件的小型化等应用研究工作.
关键词:
左手介质
小型化
双负特性
后向波特性 相似文献
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Yong Zhi Cheng He Lin Yang Yan Nie Rong Zhou Gong Zheng Ze Cheng 《Applied Physics A: Materials Science & Processing》2011,103(4):989-994
A low losses broadband planar negative refractive index metamaterial based on split-ring resonator (SRR) pairs is proposed
and investigated experimentally and numerically at microwave frequency range. The transmission spectra of the single-layer
SRR pairs were measured, and exhibited left-handed (LH) transmission passband clearly. The metal-dielectric-metal structure
exhibits strong magnetic and electric responses simultaneously, and leads to negative permeability and negative permittivity.
To further verify the LH properties of planer structure metamaterials, effect media parameters were retrieved, a refraction
phenomenon based on a wedge-shaped model and negative phase advance between consecutive numbers of layers were also demonstrated. 相似文献
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通过设计一定的单元结构, 可以实现超宽带人工电磁材料. 基于蘑菇型金属结构, 提出了一种同时具有左右手通带无缝结合的超宽带双入射型复合媒质材料结构单元. 该结构由嵌入到介质板的两个反向对称的蘑菇型金属结构组成, 能够同时引发电谐振和磁谐振而得到左手通带. 通过利用CST软件仿真、等效电磁参数提取、折射率计算以及建立等效磁谐振电路模型等方法, 分析验证了该结构的双入射特性和左手特性. 仿真结果表明, 在电磁波垂直于介质板和平行于介质板入射两种情况下, 在X波段均表现出左手通带特性, 并具有1 GHz以上的左手带宽. 当电磁波垂直于介质板入射时, 在7.2 GHz-9.3 GHz频段为右手通带, 在9.3 GHz-11 GHz频段为左手通带; 当电磁波平行于介质板入射时, 在7.0 GHz-9.0 GHz频段为右手通带, 在9.0 GHz-10 GHz频段为左手通带. 在两种情况下分别于9.3 GHz与9.0 GHz处得到了零折射率, 从而构造了一种正-零-负复合媒质材料, 实现了具有3 GHz带宽的双入射超宽带平衡结构. 相似文献
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提出了一种工作在C波段的新型平面结构异向介质,它除了带宽宽和损耗小外,还具有体积小、结构简单的优点,而且能够实现工作频段的平移,频率平移范围为4—20 GHz.基于电磁波由自由空间入射半无限大异向介质平板的传输和反射数据,计算出了电波在其中传播时的相速随频率的变化曲线,结果表明所讨论的异向介质确实在预想的频段上表现出后向波特性;同时利用相位观察法进一步验证了上述的后向波特性,从而肯定了异向介质的存在.
关键词:
异向介质
宽频带
小单元
后向波特性 相似文献
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I. Ili?P.P. Beli?ev V. Milanovi?J. Radovanovi? Lj. Had?ievski 《Physics letters. A》2011,375(10):1357-1361
We present an analysis of the influence of the Goos-Hänchen effect on tunneling times, group delay and dwell time, of electromagnetic waves propagating through an obstacle made of left-handed metamaterial embedded in a dielectric which exhibits saturable type of nonlinearity. The derived equations show that only the group delay, is affected by the Goos-Hänchen shift without any impact on the dwell time. Besides the reduction of the group delay, the most remarkable result is the possibility for total reduction of the Goos-Hänchen shift for finite incident angles. These phenomena are observable in the frequency region for which metamaterial exhibits negative index of refraction. 相似文献
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We propose a type of elastic metamaterial comprising fluid-solid composite inclusions which can possess a negative shear modulus and negative mass density over a large frequency region. Such a material has the unique property that only transverse waves can propagate with a negative dispersion while longitudinal waves are forbidden. This leads to many interesting phenomena such as negative refraction, which is demonstrated by using a wedge sample and a significant amount of mode conversion from transverse waves to longitudinal waves that cannot occur on the interface of two natural solids. 相似文献
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We report on three types of tunable dual-band metamaterial with dual negative refraction in this paper. The three types of
metamaterial are composed of ferrite slabs and three different metallic resonators, including split-ring resonators (SRR),
Ω-like resonators, and short wire pairs. The ferrite slabs under an applied magnetic bias provide one magnetic resonance frequency
band and the three metallic resonators provide another magnetic resonance frequency band, respectively. The continuous wires
within the metamaterials provide the negative permittivity in a wide frequency band covering the two magnetic resonance bands.
We give the design, analysis and numerical demonstrations of three such types of metamaterial in detail. The effective electromagnetic
parameters obtained from the simulated S-parameters indicate that the three types of metamaterial indeed exhibit two negative
refraction passbands and the two passbands can also be shifted by changing the magnetic bias. Our results open the way to
fabricate tunable dual-band metamaterial cloaks, absorbers, and antennas. 相似文献
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通过实验及仿真研究了基于C环的新型八边形开口谐振环金属线复合周期结构左手材料.以金属铜八边形谐振环(SRRs)为基本单元的周期结构负磁导率材料,与闭口环(CSRRs)结果对比发现八边形谐振环能产生很好的谐振效果即能产生负磁导率;复合结构仿真结果显示,八边形谐振环金属线复合结构实现负折射具有可行性.设计、制作并实验和仿真研究了两种尺寸的八边形谐振环金属线复合周期结构左手材料,实验结果显示,分别在9.8—15GHz和9.5—15GHz出现良好负折射效应,表明小尺寸材料负折射频段较宽但整体能量透过率较小.通过与尺寸相近的传统C环样品实验对比发现八边形样品损耗较大,但其负折射区域能量分布比例较大,具有一定的优越性.该研究对新型周期结构左手材料的研究、设计和研制具有重要的科学意义,在国防、通信等领域也具有广阔的应用前景. 相似文献
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N. T. Tung J. W. Park V. T. T. Thuy P. Lievens Y. P. Lee V. D. Lam 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,81(3):263-268
In this paper we experimentally and numerically study the left-handed behavior in a biplanar metamaterial operating at microwave
frequency. The metamaterial consists of ϕ-shaped metallic patterns on both sides of a dielectric spacer. The origin of negative refractive index is elucidated by performing
the effective medium analysis. Additionally, the dependence of the left-handed transmission on geometric parameters, such
as the periodicities, the shapes of metallic slabs and continuous wires, and the impact of spacer separation, is examined. 相似文献
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We report the true left-handed transmission of a composite metamaterial (CMM) consisting of periodically stacked split-ring resonator (SRR) and wire elements. The negative permeability (μ < 0) gap is demonstrated explicitly by comparing SRR and closed-ring resonator structures. We confirm experimentally that the plasma cut-off frequency of the CMM is determined by the combined dielectric response of SRR and wire elements, and it is much lower than that of the wire-only medium. This is crucial to identify the left-handed transmission bands of the CMM. We further investigate the effect of intralayer and interlayer disorder on the transmission spectrum of CMM arising from misaligned fabrication and stacking of the SRR layers. We found that the intralayer disorder affects the μ < 0 gap of SRRs and the left-handed transmission band of CMM significantly, whereas the SRR transmission is rather immune to interlayer disorder. 相似文献
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We address the problem of positive phase-shifting, negative refraction and focusing via a flat lens on the basis of the metamaterial technologies. With this aim, three examples are considered which differ by the technology employed and the operating frequency. The first one concerns negative-zero-positive refraction by using a prism-shaped electromagnetic metamaterial which consists of omega-type inclusion arrays operating at microwaves. The experimental verification was done in this case by angle-resolved transmission measurements. Second, we report on the phase-shift properties of a negative index transmission line which operates at Terahertz frequencies. In order to experimentally demonstrate the left-handed character of the propagation along the line, resulting in a phase advance, we used time domain experiments. At last, focusing by double refraction in a flat negative index lens was demonstrated by the theoretical and experimental mapping of the intensity of the electric field. Such a mapping of the E-field was carried out at near infrared (1.5 μm) by analysis in the time domain and scanning by near field optical microscopy. To cite this article: D. Lippens, C. R. Physique 10 (2009). 相似文献