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本研究基于电磁谐振理论和镜像对称原理,提出了一种结构简单的新型左手材料,该结构仅在介质板单面印制。通过理论分析、HFSS仿真软件、NRW(Nicolson-Ross-Weir)等效电磁参数提取以及FOM(figure of merit)系数计算验证了该结构的左手特性。结果表明:该结构在12.65~23.32GHz频率范围内具有等效介电常数和等效磁导率同时为负的特性,其左手频带的绝对带宽达到10.67GHz,相对带宽达到59.33%,最大单元损耗仅为0.29dB,远远优于传统的左手材料。 相似文献
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本文设计了一种可开关的双频段左手材料,该结构在聚酰亚胺介质基板上面放置了两组对称的开口环结构,背面放置3条相同的金属铜线.通过在谐振环的开口间隙处加载RF MEMS开关来控制磁响应从而实现可开关的双频响应.运用高频电磁仿真软件HFSS对不同开关状态下该结构的电磁特性进行仿真研究,结果表明:当开关处于不同状态时,该结构可分别实现低频、高频和双频可开关的负折射率和左手特性.该研究结果对拓展左手材料在不同频段的应用具有潜在的应用价值. 相似文献
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针对目前由金属开口谐振环与金属杆构成的左手材料结构存在构造比较复杂、工艺实现较难的缺点,设计实现了一种基于金属条的改进结构-"王"字型结构。通过理论分析和电磁仿真软件Ansoft HFSS 10模拟仿真,利用散射参量法提取参数结果表明该结构可以在X波段实现介电常数和磁导率同时为负。讨论研究了该左手结构的金属条宽度、中间缺口宽度、中间条宽度三个结构尺寸参数变化对谐振频率和透射峰幅值的影响,结果表明三个参数的变化都会对二者产生影响,其中金属条宽度改变对透射峰值影响幅度相对较大,缺口宽度改变对谐振频率影响幅度相对较大。 相似文献
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近年来,电磁干扰及电磁兼容问题日益加剧,严重危害军民领域仪器、仪表等电子设备的安全运行,亟待开发出新型高性能电磁屏蔽材料。石墨烯是一种新型的二维碳纳米结构材料,具有优异的物理与化学性能,为柔性、轻薄、服役性能好的电磁屏蔽材料设计提供了新的解决方案。从电磁屏蔽的基本原理出发,介绍了电磁波屏蔽和损耗的机理及能量转化方式。进一步对石墨烯电磁屏蔽材料进行了系统地分类与归纳,综述了近年来石墨烯电磁屏蔽材料的屏蔽效能和研究进展,对石墨烯电磁屏蔽材料面临的挑战和发展前景进行了展望。 相似文献
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MXene是一类具有二维层状结构的过渡金属族碳化物或氮化物,由于具有独特的层状结构、优异的导电性、可调节的活性表面和优异的机械强度,其在二维材料中备受瞩目,并在各领域中都具有很大的应用潜力,特别是用于微波吸收(MA)和电磁干扰(EMI)屏蔽.本文从MXene材料的典型结构、性能和主要的合成策略出发,综述和分析了近年来关于MXene材料在电磁屏蔽和吸波领域的研究现状,剖析了其在应用过程中面临的主要问题和进一步发展的瓶颈,最后对MXene材料的发展前景进行了展望. 相似文献
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Samir Salem Al-Bawri Mohammad Tariqul Islam Kabir Hossain Thennarasan Sabapathy Muzammil Jusoh 《计算机、材料和连续体(英文)》2022,71(1):611-628
This paper presents a textile-based C-shaped split-ring resonators (SRR) metamaterial (MTM) unit cells with an electrical tunability function. The proposed MTM was composed of two symmetrical C-shaped SRR combined with a central diagonal metal bar, whereas the RF varactor diode is placed on the backside of the splitted ground plane. Stopband behavior of single and array MTM unit cells were analyzed while the achieved negative index physical characteristics were widely studies. Though four different MTM arrays (i.e., 1 × 1, 1 × 2, 2 × 1, and 2 × 2) were analyzed in simulation, a 2 × 2-unit cell array was chosen to fabricate, and it was further undergone experimental validation. This proposed tunable MTM exhibits double negative (DNG)/left-handed properties with an average bandwidth of more than 2.8 GHz. Furthermore, attainable negative permittivity and negative permeability are within 2.66 to 9.59 GHz and within 2.77 to 15 GHz, respectively, at the frequency of interest (between 1 and 15 GHz). Moreover, the proposed tunable MTM also showed tunable transmission coefficient characteristics. The proposed electrically tunable textile MTM might function in a dynamic mode, making it suitable for a variety of microwave-wearable applications. A satisfactory agreement between simulations and experiments were achieved, demonstrating that the proposed MTM can operate over a wide bandwidth. 相似文献
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Oxley C.H. Williams J. Hopper R. Flora H. Eibeck D. Alabaster C. 《Science, Measurement & Technology, IET》2007,1(3):166-169
There is increasing interest in conducting fabrics and their uses at radio frequencies and microwave frequencies. The reflection and transmission measurements of bobbinet and knitted materials from around 8 GHz into the milli-metric frequency range 110 GHz, where the material geometry is comparable to the wavelength of the wave are considered. Bobbinet materials were found to behave like lossy dielectrics and may be useful in the construction of thin lightweight screening and absorption planes. While the knitted materials, with very small mesh geometry, gave a reflection coefficient which was comparable to a metal foil 相似文献
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《IEEE transactions on instrumentation and measurement》1967,16(3):206-211
The bolometer unit widely used for measuring microwave and millimeter wave power becomes more difficult to construct and obtain good performance, as the wavelength gets shorter. To overcome these difficulties, a new unit has been developed which has a very simple structure by virtue of a new matching procedure. The bolometer element is made of a thin metal film evaporated on a thin mica substrate, and its mount consists only of a short circuit and a flange. Experimental units have been designed at 35 GHz and 10 GHz, and these have demonstrated excellent characteristics, such as high efficiency, low VSWR, wide bandwidth, high power handing capacity, etc. The thermistor units applying the same matching theory are also investigated at 35 GHz and 50 GHz. 相似文献
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A grounded coplanar waveguide technique for microwave measurement of complex permittivity and permeability 总被引:2,自引:0,他引:2
Jiqing Hu Sligar A. Chih-Hung Chang Shih-Lien Lu Settaluri R.K. 《IEEE transactions on magnetics》2006,42(7):1929-1931
We present a method for extracting the complex permittivity and permeability of dielectric/magnetic thin films in a grounded coplanar waveguide configuration. The technique is applicable for extraction of these material parameters for lossy and lossless materials over a broad frequency range with high accuracy. For validation, we extracted complex permittivity and permeability, using the scattering parameters obtained from the full-wave electromagnetic simulation for two test cases over a frequency range of 5 to 15 GHz. Accuracy for both dielectric as well as magnetic materials is within 2% error. 相似文献
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AbstractVanadium dioxide is an intensively studied material that undergoes a temperature-induced metal–insulator phase transition accompanied by a large change in electrical resistivity. Electrical switches based on this material show promising properties in terms of speed and broadband operation. The exploration of the failure behavior and reliability of such devices is very important in view of their integration in practical electronic circuits. We performed systematic lifetime investigations of two-terminal switches based on the electrical activation of the metal–insulator transition in VO2 thin films. The devices were integrated in coplanar microwave waveguides (CPWs) in series configuration. We detected the evolution of a 10 GHz microwave signal transmitted through the CPW, modulated by the activation of the VO2 switches in both voltage- and current-controlled modes. We demonstrated enhanced lifetime operation of current-controlled VO2-based switching (more than 260 million cycles without failure) compared with the voltage-activated mode (breakdown at around 16 million activation cycles). The evolution of the electrical self-oscillations of a VO2-based switch induced in the current-operated mode is a subtle indicator of the material properties modification and can be used to monitor its behavior under various external stresses in sensor applications. 相似文献
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Jinggui Zhang 《Journal of Modern Optics》2017,64(17):1717-1724
In this paper, we first derive a modified two-dimensional non-linear Schrödinger equation including high-order diffraction (HOD) suitable for the propagation of optical beam near the low-diffraction regime in Kerr non-linear media with spatial dispersion. Then, we apply our derived physical model to a designed two-dimensional configuration filled with alternate layers of a left-handed material (LHM) and a right-handed media by employing the mean-field theory. It is found that the periodic structure including LHM may experience diminished, cancelled, and even reversed diffraction behaviours through engineering the relative thickness between both media. In particular, the variational method analytically predicts that close to the zero-diffraction regime, such periodic structure can support stable diffraction-management solitons whose beamwidth and peak amplitude evolve periodically with the help of HOD effect. Numerical simulation based on the split-step Fourier method confirms the analytical results. 相似文献
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AbstractFilter characteristics of a planar Mach–Zehnder interferometer (MZI) structure composed of periodically thin corrugated metal films were studied here. From theoretical simulation, spoof surface plasmon polaritons can propagate along the periodically thin corrugated metal films in microwave frequency, which can be excited by a coplanar waveguide. When the two arms of the MZI have the same length with the angle between them being 60°, the MZI structure has a very wide bandwidth with 8.6 GHz. By changing the length of one of the interference arms, a novel low-pass filter based on the planar MZI structure with two notched frequencies was proposed. The proposed planar structure can find potential applications in developing surface wave devices in integrated microwave circuits and systems. 相似文献
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Microwave absorbing materials play a major role in electromagnetic interference and compatibility measurements in anechoic
chambers. Nanocrystalline calcium titanate (CT) was synthesized by hydrothermal method and further composites of CT/epoxy
resin were fabricated as thin solid slabs of four different weight ratios. The composite material was analyzed by X-ray diffraction
(XRD) and transmission electron microscopy (TEM), which reveals that CT was observed to be in the monoclinic phase with an
average crystallite size of 24 nm. The reflectivity measurement of the composite materials was carried out by the transmission/reflection
method using a vector network analyzer R&S: ZVA40, in the X- and Ku-bands. The effective permittivity and permeability of
the samples was also computed with the help of measured transmission and reflection coefficients. The results show that CT
with equal weight of epoxy resin provides −30 dB at 8.5 GHz in the X-band and −19.5 dB at 18.0 GHz in the Ku-band. Reflectivity
was found to be better than −10 dB for 2.2 GHz and 1.9 GHz for X-band and Ku-band, respectively and encourages use of it as
potential microwave absorber material. 相似文献
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The thermal metastability of iron nitride was exploited to fabricate thin-film microstructures applicable to left-handed metamaterials. A granular thin film containing dispersed iron particles was prepared by post-annealing an rf-sputter-deposited Fe0.5Al0.5N thin film with a wurtzite-type structure in a nitrogen atmosphere at 450 °C. The obtained samples showed magnetic resonance in the microwave region. Laser direct writing was also applied in a nitrogen atmosphere to an rf-sputter-deposited Fe0.7Al0.3N thin film. 200 μm-wide, 300 Ω cm iron metal lines were drawn in a host nitride film of approximately 2 kΩ cm. Combining and optimizing the above negative permeability and permittivity values should provide left-handed materials with a negative refractive index. 相似文献