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A new form of the quasioptical equation is proposed to describe the propagation of an electromagnetic wave beam in a stationary smoothly inhomogeneous medium with spatial dispersion and dissipation. The proposed approach guarantees the positive definiteness of the absorbed power in the locally dissipative medium, which is a nontrivial property for inhomogeneous media with spatial dispersion. An efficient numerical scheme is constructed to solve the derived quasioptical equation. 相似文献
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基于位函数的引入与介质参量无关,将各向异性目标内外的电场展为级数形式,得到了任意各向异性目标n阶散射场、目标内场的递推表达式,给出了介电常量张量的变换关系,在平面波任意入射的条件下,并给出了传播单位矢量与极化单位矢量的一般关系.以磁化冷等离子体为例,给出了一阶散射场的具体表达式,并对二阶散射场引起的误差进行了评估.在THz波段和光波段,对所得结果进行了部分仿真.结果表明:微分散射对电波频率和极化状态等因素的影响较为敏感,介电常量张量的非对角元素对散射的影响不大,当波长与目标尺寸一定时,仿真结果不仅适用于THz波段,对其它波段也成立. 相似文献
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基于位函数的引入与介质参量无关,将各向异性目标内外的电场展为级数形式,得到了任意各向异性目标n阶散射场、目标内场的递推表达式,给出了介电常量张量的变换关系,在平面波任意入射的条件下,并给出了传播单位矢量与极化单位矢量的一般关系.以磁化冷等离子体为例,给出了一阶散射场的具体表达式,并对二阶散射场引起的误差进行了评估.在THz波段和光波段,对所得结果进行了部分仿真.结果表明:微分散射对电波频率和极化状态等因素的影响较为敏感,介电常量张量的非对角元素对散射的影响不大,当波长与目标尺寸一定时,仿真结果不仅适用于THz波段,对其它波段也成立. 相似文献
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Conditions for the appearance of modulation instability of an optical wave packet formed by one or two unidirectional strongly interacting waves are studied taking into account the influence of the temporal dispersion of a nonlinear response of the medium on this process. The regions of values of the frequency, input radiation intensity, and dispersion parameters in which the wave perturbations are increased are found. It is shown that the initial conditions for excitation of optical fibers of this type significantly affect the dynamics of the modulation instability. 相似文献
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Reflection of thermoelastic wave on the interface of isotropic half-space and tetragonal syngony anisotropic medium of classes 4,4/m with thermomechanical effect
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Nurlybek A Ispulov Abdul Qadir M A Shah Ainur K Seythanova Tanat G Kissikov Erkin Arinov 《中国物理 B》2016,25(3):38102-038102
The thermoelastic wave propagation in a tetragonal syngony anisotropic medium of classes 4, 4/m having heterogeneity along z axis has been investigated by employing matrizant method. This medium has an axis of second-order symmetry parallel to z axis. In the case of the fourth-order matrix coefficients, the problems of wave refraction and reflection on the interface of homogeneous anisotropic thermoelastic mediums are solved analytically. 相似文献
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We theoretically analyze waves propagating between an isotropic medium and an anisotropic medium. Closely examining the boundary condition reveals that the phenomenon of nonsymmetrical reflection occurs when the wave propagates from an anisotropic to an isotropic medium. Calculating the reflection of thin films requires correcting the phase change in each reflected trip in the Airy formula. Analytical results of measurement of the elliptical surface of a wave-vector distribution in an anisotropic medium indicate that reflection and transmission still occur when the reflected and the refracted angles are larger than 90 degrees . 相似文献
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W. B. Dou G. Zeng Z. L. Sun 《International Journal of Infrared and Millimeter Waves》1996,17(7):1193-1198
A quasioptical ferrite switch is proposed as an essential building block in millimeter wave systems. In this communication the configuration of the quasioptical ferrite switch is described. The performance of the switch is calculated, and its application in radiometric system is pointed out. The isolation of such device is greater than 30 dB and insertion loss less than 1.0dB over whole W band. 相似文献
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The effect of finite ion Larmor radius corrections on the propagation of small perturbations through self gravitating, anisotropic system with generalized polytrope law is investigated. The polytrope laws are considered for the pressure components in parallel and perpendicular directions to the magnetic field. The polytrope model proposed by Abraham-Shranuer can be reduced to CGL equations with double adiabatic equations of state and MHD set of equations with isothermal equation of state. The effects of FLR and polytrope indices are discussed on the gravitational, firehose and mirror instability. The critical Jeans wave numbers are found to depend on polytropic indices and derived for CGL and MHD cases. The FLR corrections are found effective in shorter wave length region and produce stabilizing influence. The condition of mirror instability is uninfluenced by FLR but dependent on polytropic indices. 相似文献
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V. I. Belousov G. G. Denisov N. Yu. Peskov 《International Journal of Infrared and Millimeter Waves》1991,12(9):1035-1043
The article presents results of theoretical and experimental investigation of quasioptical multiplexer based on reflecting diffraction grating. Diffraction losses caused by reflection into mirror harmonic, and by angle divergence of wave beams are calculated. In an experimental multiplexer, wave beams with the frequencies 70 GHz and 79 GHz were mixed with power losses less than 1%. 相似文献
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研究了弹性波在非均匀裂纹孔隙介质中的传播特性,建立了各向异性喷射流模型.当弹性波通过裂纹孔隙介质时,由于波的扰动及裂纹和孔隙几何结构的不一致,导致在裂纹内部及裂纹与周边孔隙之间同时存在着流体压力梯度.此时的弹性波波动响应中包含着裂纹内连通性特征和背景孔隙渗透率信息.流体的动态流动过程使得介质的等效弹性参数为复数(非完全弹性),并且具有频率依赖性.当弹性波为低频和高频极限时,介质为完全弹性;当处于中间频段时,波有衰减和频率依赖.裂纹孔隙介质的各向异性连通性(渗透率)对应着各向异性特征频率(当渗流长度等于非均匀尺度时的弹性波频率),波的传播受到裂纹内连通性的影响.在一定频段内,随着裂纹厚度的增加,将出现第二峰值,峰值大小同时受到裂纹厚度和半径的影响. 相似文献
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V. V. Glamazdin M. P. Natarov V. N. Skresanov A. I. Shubniy 《Radiophysics and Quantum Electronics》2009,52(3):210-226
We study theoretically and experimentally the efficiency of excitation of an open resonator by a waveguide. A two-dimensional
model of a quasioptical two-mirror open resonator, which is excited through a coupling element in the form of an open end
of a plane-parallel waveguide, is proposed. The field of the open resonator is represented as the superposition of Gaussian
wave beams and its scattering on the coupling element is described by solving the problem of diffraction of waveguide waves
and Gaussian wave beams on an open end of a flanged waveguide. Properties of the mirrors and the resonator loss are specified
from physical considerations. The calculation results are compared with the experimental data, and a physical interpretation
of the obtained results is offered. The factors which influence the efficiency of excitation of an open resonator are identified.
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 52, No. 3, pp. 231–249, March 2009. 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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Fabric dependence of quasi-waves in anisotropic porous media 总被引:1,自引:0,他引:1
Assessment of bone loss and osteoporosis by ultrasound systems is based on the speed of sound and broadband ultrasound attenuation of a single wave. However, the existence of a second wave in cancellous bone has been reported and its existence is an unequivocal signature of poroelastic media. To account for the fact that ultrasound is sensitive to microarchitecture as well as bone mineral density (BMD), a fabric-dependent anisotropic poroelastic wave propagation theory was recently developed for pure wave modes propagating along a plane of symmetry in an anisotropic medium. Key to this development was the inclusion of the fabric tensor--a quantitative stereological measure of the degree of structural anisotropy of bone--into the linear poroelasticity theory. In the present study, this framework is extended to the propagation of mixed wave modes along an arbitrary direction in anisotropic porous media called quasi-waves. It was found that differences between phase and group velocities are due to the anisotropy of the bone microarchitecture, and that the experimental wave velocities are more accurately predicted by the poroelastic model when the fabric tensor variable is taken into account. This poroelastic wave propagation theory represents an alternative for bone quality assessment beyond BMD. 相似文献
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A. S. Ashour 《ARI - An International Journal for Physical and Engineering Sciences》1999,51(4):254-257
The wave motion in a fluid-filled fracture embedded in an anisotropic medium is investigated using the technique of partial waves. A model is derived to calculate the complex dispersion relation of the Stoneley-wave mode in a fluid layer between two infinite transversely isotropic half-spaces. The effect of the anisotropic parameters on the Stoneley-wave in the fracture is investigated. The numerical results indicate that the velocity of the Stoneley-wave mode has significant dependence on the transversely isotropic constants. For a weakly anisotropic medium, the Stoneley-wave dispersion is almost the same as in an isotropic medium. 相似文献