共查询到20条相似文献,搜索用时 93 毫秒
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提出了一种基于平板波导的新型异向谐振结构——交叉椅型谐振结构,通过理论分析和数值计算,说明和验证了单个交叉椅型谐振结构加载的平板波导具有双通带特性和异向特性;设计了一种由多个交叉椅型谐振结构周期加载的异向平板波导结构,并通过仿真实验验证了其负折射特性。交叉椅型谐振结构的全金属半封闭式结构和其特殊的电磁谐振方式,使得此类2维异向平板波导与传统的由金属开口谐振环与金属线正交阵列而成的2维异向介质相比,具有双通带、无介质损耗、功率容量大等特异性质;单个交叉椅型谐振结构加载的平板波导作为一种新型的滤波器结构,具有良好的双通带特性,尺寸较小。 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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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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提出了一种新型二维左手材料结构单元,该结构由介质板及其两侧放置的两个反向对称的Z形金属条组成.在电磁波垂直于介质板和平行于介质板入射两种情况下,这种结构单元于X波段均表现出左手通带特性.通过模拟仿真,提取等效电磁参数,建立等效磁谐振电路模型,分析验证了该结构的左手特性.并将双Z形结构与相似的工字形结构相比较,发现在电磁波垂直入射时两种结构均出现相似的左手通带,而在电磁波平行入射时,只有双Z形结构实现了双负特性.结果表明这种双Z形左手单元结构具有更优越的电磁波入射适应特性,即实现了双入射型左手结构单元.
关键词:
双Z形结构
二维
左手材料
双入射 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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We present the design of a multiband left-handed three-dimensional (3D) metamaterial based on improved fishnet structure at terahertz frequencies. The design realizes a three-dimensional material by mechanical stacking of multiple layers. The electromagnetic properties of the metamaterial have been investigated by numerical simulation. The results show that simultaneously negative values of permittivity, permeability and refractive index are found around the frequencies of 0.73, 0.85 and 1.12 THz for the electromagnetic wave normal incidence. The proposed metamaterial with independent polarization and compact effect offers a way to develop THz 3D materials and devices suitable for multifrequencies. 相似文献
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The isotropic-like fishnet metamaterial with an array of cross-shaped holes penetrating through the multiple layers has been numerically studied in the terahertz regime. Its left-handed properties are described by the retrieved effect media parameters and validated by the simulation of a wedge-shaped model. The influences of the various geometrical parameters on the electromagnetic response and the left-handed performance are investigated. This isotropic-like fishnet metamaterial has the advantage of lower losses and higher transmission and holds potential for further applications at higher frequencies. 相似文献
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We design and analyze a novel multiband left-handed metamaterial based on a fishnet-like structure at terahertz (THz) frequencies.The metamaterial exhibits simultaneous negative refractions around the frequencies of 0.48,1.05,and 1.19 THz for the electromagnetic (EM) wave normal incidence,and around the frequencies of 0.20,0.79,and 1.13 THz for parallel incidence.The simulated results verify the left-handed properties.A particularly important observation is the capability of the proposed metamaterial with a single geometrical structure to display multifrequency operations in a unit cell.The compact metamaterial is a major step toward the miniaturization of THz materials and devices suitable for multifrequencies. 相似文献
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Jian-Wen Dong 《Physics letters. A》2008,372(24):4532-4535
Multiple omnidirectional resonances are found in a sandwich structure consisting of a left-handed metamaterial cavity and two single-negative-permittivity reflection walls. These resonances appear because the phase shift of left-handed metamaterial can cancel the reflection phase shift of single-negative-permittivity metamaterials at every incidence angle. By using such particular structure, a kind of structure possessing multiple omnidirectional resonances in both polarizations has been designed. In addition, issues associated with energy loss are discussed. 相似文献
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A dual-band and polarization-independent fishnet metamaterial for the sub-THz frequency range is proposed and investigated. Dual-band modes have two resonances in which the first one is fixed as a left-handed mode and the second one can be arranged as a left-handed or single-negative mode. We select the character of second resonance by the choice of substrate properties. The metamaterial features of the structure are analyzed using the scattering data and confirmed by applying Kramers-Kronig relations. The characteristic features are also verified by the current distribution at the inner metallic surfaces of the structure. The influence of substrate modifications is studied and the effect of this change on resonances is discussed. The design of a dual-band and polarization-independent sub-THz metamaterial presented here can serve as a model and guide to realize tunable fishnet metamaterials for other frequency regimes. 相似文献
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Christian Imhof Remigius Zengerle 《Applied Physics A: Materials Science & Processing》2009,94(1):45-49
We report on microwave experiments with a metamaterial composed of pairs of metallic crosses. The transmission properties
of the structure show a left-handed transmission band at frequencies around 10.2 GHz. The validity of the negative effective
index of refraction is verified by a Snell’s law refraction experiment performed on a wedge-shaped sample of the metamaterial.
A second measurement of a similar wedge made from blank FR4 boards is done for reference. The results of the measurements
show positive refraction over the whole measured frequency band for the FR4 wedge as well as the refraction of the incident
radiation to negative angles within the designated left-handed frequency band for the metamaterial sample. 相似文献
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《Photonics and Nanostructures》2009,7(4):206-211
We investigated the effects of dielectric-spacer thickness on the left-handed behavior of a symmetric fishnet-like metamaterial working at microwave frequency. The left-handed behavior was demonstrated and characterized by the standard retrieval procedure. The thickness of spacer was varied in order to examine the electromagnetic response of the fishnet structure. It was found that the changed thickness can cause different pictures of the left-handed behavior based on the electric-magnetic correlation. 相似文献