共查询到20条相似文献,搜索用时 171 毫秒
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基于广义洛伦兹-米理论,研究两个聚焦的高斯光束沿着任意方向入射单轴各向异性涂层球的散射特性。基于球矢量波函数的正交特性,推导得到双高斯光束的球矢量波函数展开表达式。通过引入傅里叶变换,求解得到各向异性涂层区域内的电磁场展开式,将涂层球各区域的电磁场用球矢量波函数展开,再结合边界条件,得到沿任意方向传播的双高斯光束入射到涂层球的散射系数和雷达散射截面。数值模拟了雷达散射截面随散射角变化的分布,将单轴各向异性涂层球退化为单轴各向异性球时的散射结果与文献进行对比,结果十分吻合。分析双光束的入射角、粒子内半径、涂层厚度与内半径的比值、电和磁各向异性对散射强度及其散射角分布的影响。该理论和数值分析能够为激光对涂层颗粒的探测、散射以及光学操作提供有益帮助。 相似文献
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蜂窝夹芯结构作为天线罩最常用的透波材料, 其电各向异性特征对电磁传输性能具有不可忽略的影响. 本文基于各向异性蜂窝夹芯材料对电磁波水平极化和垂直极化分量的有效介电常数, 建立了多层蜂窝夹芯材料的等效传输线网络传输方程, 并给出了其传输系数的计算公式.该计算公式由于考虑了材料的三维各向异性特征, 不仅理论上可以计算多层各向异性介质板对任意方向入射电磁波的传输系数, 而且能够揭示出材料方向角对传输性能的影响规律.同时, 通过传输线网络等效, 其计算效率远高于有限元等方法.数值算例表明, 本方法能够有效地揭示蜂窝夹芯材料的各向异性对其传输性能的影响, 计算结果在入射角为0°–80° 时与有限元法符合很好.
关键词:
电磁传输性能
电各向异性介质
蜂窝夹芯材料 相似文献
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分析了电磁波以任意角度入射到有限磁场中的激光等离子体通道天线(LPCA)时的电磁散射特性。根据LPCA的工作原理建立了其电磁分析模型,推导出广义柱坐标系下各向异性磁化等离子体中纵向分量所满足的波动方程和纵向场与横向场的关系,得到LPCA和周围媒质中的电磁场,利用边界切向电磁场连续,得出了散射系数方程。通过计算实例,将结果与文献结果比较,吻合较好。该研究结果预期可应用于高功率微波武器系统的研究。 相似文献
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散射介质的传输矩阵系统描述了散射介质对输入与输出光场之间的变换关系,是研究与控制光在无序介质中传输特性的重要工具.本文使用数字微镜器件实现散射介质传输矩阵的自参考干涉测量,首先利用超像素法实现对入射光的复振幅调制获得同时包含参考光和信号光的复合场,进而基于四步相移法分别测量了散射介质在Hadamard基和轨道角动量(OAM)基下的传输矩阵.进一步,根据相位共轭原理实现了光透过散射介质后的单点聚焦、多点聚焦以及涡旋聚焦,验证了传输矩阵测量的准确性.该方法能够有效提高光场调制的自由度,实现散射介质传输矩阵的测量,对散射环境下的光学成像和光通信等具有潜在应用价值. 相似文献
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Xin Bao Wu 《International Journal of Infrared and Millimeter Waves》1994,15(10):1745-1754
A method based on the approximate wave functions for anisotropic media and the mode-matching approach is developed to solve the problem of the electromagnetic scattering from an anisotropic cylindrical dielectric shell. The cylindrical shell is assumed to be infinite in length, and it is illuminated by a plane wave or a cylindrical wave from a line source. The problem is two-dimensional and the solutions to both types of polarization (TE and TM) are presented. The validity of this solution is verified by comparing the numerical results with those in literatures and the previous calculations based on the exact wave functions for anisotropic media. Numerical results show the higher computational efficiency of the present method for bounded anisotropic media. 相似文献
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《Waves in Random and Complex Media》2013,23(3):323-333
The characteristics of guided modes in circular waveguides of a uniaxial anisotropic chiral core and a cladding filled with anisotropic plasma are presented. The cladding region is assumed to be infinitely extended with an external applied magnetic field oriented along the direction of propagation in the waveguide. The characteristics equation for the modes in this waveguide are obtained. The variations of the propagation properties with the plasma parameters, chiral parameters, and the cyclotron frequency of plasma have been investigated. Particularly, the effects of the chirality and the cyclotron frequency of plasma on the magnitude and orientation of the energy flux of the guided modes for three kinds of uniaxial anisotropic chiral media have been numerically investigated. Comparisons of the computed results of the presented formulations with published results for some special cases confirm the accuracy of the presented analyses. 相似文献
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Maksim Zalkovskij Radu Malureanu Christian Kremers Dmitry N. Chigrin Andey Novitsky Sergei Zhukovsky Peter T. Tang Peter U. Jepsen Andrei V. Lavrinenko 《Laser \u0026amp; Photonics Reviews》2013,7(5):810-817
A planar Babinet‐inverted dimer metamaterial possessing strong optical activity is proposed and characterized. An original fabrication method to produce large area (up to several cm2) freely suspended flexible metallic membranes is implemented to fabricate the metamaterial. Its optical properties are characterized by terahertz time‐domain spectroscopy, revealing anisotropic transmission with high optical activity. A simple coupled resonator model is applied to explain the principal optical features of the dimers, with predictive power of positions and number of resonances through a parametrical model. The model is validated for correct polarization‐dependent quantitative results on the optical activity in transmission spectra. The fabrication method presented in this work as well as the slit dimer design has great potential for exploitation in terahertz optics. 相似文献
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The transmission characteristics of a metallic film with
subwavelength periodic slits are investigated by using the
two-dimensional finite-difference time-domain method (2D-FDTD). Two
models are constructed to show the dependance of the transmission
spectrum on the slit structure. A sandwiched structure is used to
exhibit the contribution of the metallic wall inside slits to the
extraordinary high transmission. And a filled slit structure is
employed to reflect the relation between the average refractive
index inside the slits and the transmission spectrum of the
structure. The transmission characteristics of two structures can be
explained well with the waveguide resonance theory. 相似文献
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The numerical instability problem in the standard transfer matrix method has been resolved by introducing the layer stiffness matrix and using an efficient recursive algorithm to calculate the global stiffness matrix for an arbitrary anisotropic layered structure. For general anisotropy the computational algorithm is formulated in matrix form. In the plane of symmetry of an orthotropic layer the layer stiffness matrix is represented analytically. It is shown that the elements of the stiffness matrix are as simple as those of the transfer matrix and only six of them are independent. Reflection and transmission coefficients for layered media bounded by liquid or solid semi-spaces are formulated as functions of the total stiffness matrix elements. It has been demonstrated that this algorithm is unconditionally stable and more efficient than the standard transfer matrix method. The stiffness matrix formulation is convenient in satisfying boundary conditions for different layered media cases and in obtaining modal solutions. Based on this method characteristic equations for Lamb and surface waves in multilayered orthotropic media have been obtained. Due to the stability of the stiffness matrix method, the solutions of the characteristic equations are numerically stable and efficient. Numerical examples are given. 相似文献
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Ya.A. Ilyushin 《Journal of Quantitative Spectroscopy & Radiative Transfer》2012,113(5):348-354
The problem of coherent backscattering enhancement in media with highly anisotropic scattering is considered within the scalar wave theory. A stable computational algorithm, suitable for the media of finite thickness, is formulated. Numerical simulations are performed, and the results are presented and discussed. 相似文献
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Analysis of coaxial waveguide partially filled with chiral media 总被引:4,自引:0,他引:4
Xinzhang Wu Frédéric Mariotte 《International Journal of Infrared and Millimeter Waves》1997,18(12):2411-2435
In this paper, the canonical problem of coaxial waveguide partially filled with chiral media is analyzed by a new equivalent
transmission line network method. Both radial transmission lines in the cross section and multi-mode transmission lines in
the longitudinal direction are introduced. The symmetrical properties of the structure are also discussed. Therefore, this
method brings a clear physical picture into the wave propagation phenomena. Based on the analysis, the notable features and
the role of the chirality parameter of the medium on the reflected and transmitted guided waves are discussed. 相似文献
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J. W. Menezes L. F. Avila E. S. Braga L. Cescato 《Applied Physics A: Materials Science & Processing》2011,103(3):631-634
In this paper we compare the sensitivity of the Extraordinary Transmittance (ET) peak position with the surrounding media
for two types of metallic structures: arrays of holes and arrays of slits recorded in Au films. Both types of array were fabricated
using Interference Lithography (IL) with a period of 700 nm and an Au thickness of 150 nm. The transmission spectra measurements
were performed at normal incidence using a spectrophotometer. The results show that an array of slits presents a higher sensitivity
for the surrounding media than the array of holes. Theoretical TE and TM simulations of the transmission spectra for the slit
arrays agree very well with the experimental results, confirming the better sensitivity of the slit arrays. 相似文献