共查询到20条相似文献,搜索用时 15 毫秒
1.
A theoretical investigation has been carried out for electromagnetic waves scattering from a perfect electromagnetic conductor (PEMC) sphere which is placed in chiral media. The formulation of the problem is realized by expanding the incident as well as the scattered electromagnetic fields in terms of left circularly polarized (LCP) and right circularly polarized (RCP) waves. By applying the boundary conditions at the chiral-PEMC interface, eight simultaneous equations are generated, which yield the scattering coefficients associated with the Left and Right electromagnetic waves. The relative contribution of Co-polarized and Cross-polarized components of fields to the calculations of scattering cross-section is presented. The effect of admittance parameter and the effect of chirality parameter in cases of lossless, lossy permittivity and lossy permeability on Co and Cross components of scattering cross sections are observed. The results are also compared with available published literatures which are in good agreement. 相似文献
2.
《Waves in Random and Complex Media》2013,23(4):708-719
Theoretical analysis of electromagnetic wave propagation in a perfect electromagnetic conductor (PEMC) parallel-plate waveguide filled with a chiroplasma material is presented in this article. The derived formulations are general and can analyze perfect electric, perfect magnetic, or PEMC waveguides filled with any general isotropic/anisotropic material including plasma and metamaterials. The characteristic equation for the modes in this waveguide is obtained, and the behavior of the dispersion curves and the energy flux are examined and evaluated numerically. The results demonstrate that the chirality parameter, the plasma frequency, and the cyclotron frequency influence the behavior of the energy flux transported in the guide, in magnitude and orientation. The bifurcated mode cutoff frequencies are sensitive to the variations in the filling material parameters and likewise effected by the variations in the PEMC walls admittance parameter. 相似文献
3.
Shakeel Ahmed 《Optics Communications》2008,281(17):4211-4218
Electromagnetic scattering of an incident plane wave from a rectangular strip and strip grating, are presented semi-analytically. The strip and strip grating are simulated by joining parallel perfect electromagnetic conductor (PEMC) circular cylinders and are illuminated by a TMz incident plane wave. The PEMC medium does not allow electromagnetic energy to enter. An interface of this medium serves as an ideal boundary to the electromagnetic field. The solution is based on the application of the boundary conditions on the surface of each cylinder in terms of its local coordinate system. The technique is used to predict the scattered field pattern of PEMC strip and PEMC strip grating. 相似文献
4.
The two dimensional analytical formulation of scattering of electromagnetic wave from a perfect electromagnetic conductor (PEMC) cylinder placed in un-magnetized isotropic plasma medium is presented. The extended classical scattering theory is used. The incident wave is taken as linearly polarized wave. The analytical theory is formulated for parallel polarization (TM) and also for perpendicular polarization (TE). The numerical computation results show that backscattering and forward scattering are sensitive to electron density and effective collision frequency of plasma medium. We placed different types of cylinders (PEC, PMC and PEMC) in un-magnetized plasma medium and concluded that stealth capability of plasma increases with the placement of PEMC cylinder in plasma medium. 相似文献
5.
In this paper, the electromagnetic radiation of a line source scattered by an infinite perfect electromagnetic conductor (PEMC) coated with anisotropic media is analytically analyzed. A line source is placed inside the anisotropic media. To validate the presented formulas, the radiation patterns for isotropic cases are compared to the published literature and good agreement is found between them. Also, the directivity of the electromagnetic radiation pattern is improved using the anisotropic coating. Furthermore, when the line source is placed on the surface of PEMC core and the relative tensors of anisotropic shell are appropriately chosen, the co- and cross-polarization components of the fields form the same radiation patterns. 相似文献
6.
《Waves in Random and Complex Media》2013,23(4):706-721
ABSTRACTIn this study, we analyzed the influence of isotropic plasma on far field scattering radiation of perfect electromagnetic conductor (PEMC) cylinder in the presence of directive electromagnetic radiation excited from an electric line source. Two cases regarding electric line source have been considered to gain more graphical variation corresponding to plasma parameters. In the first case, electric line source is placed outside the coating layer while in second case electric line source placed inside the coating. It has been demonstrated that the far field scattering patterns of PEMC, PEC, and PMC are strongly dependent on plasma parameters; however, their importance to control scattering pattern slightly changed/reversed corresponding to electric line source placement (inside the coating and outside the coating). 相似文献
7.
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
8.
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
9.
给出了不同坐标系中介质参数张量的变换,得到了磁化冷等离子体球电场的表达式,得出了任意各向异性目标散射场的表达式,研究了磁化冷等离子体球的微分散射截面、散射截面等的函数关系,仿真结果与有关文献一致,表明了本算法的有效性,从而为各向异性目标识别等提供理论支持。 相似文献
10.
给出了不同坐标系中介质参数张量的变换,得到了磁化冷等离子体球电场的表达式,得出了任意各向异性目标散射场的表达式,研究了磁化冷等离子体球的微分散射截面、散射截面等的函数关系,仿真结果与有关文献一致,表明了本算法的有效性,从而为各向异性目标识别等提供理论支持。 相似文献
11.
Shakeel Ahmed 《Optics Communications》2008,281(23):5664-5670
Electromagnetic scattering of an incident uniform plane wave from a perfect electromagnetic conductor (PEMC) circular cylinder, coated with a metamaterial is investigated theoretically. In the analysis the coating layer may be double-positive (DPS), double-negative (DNG), epsilon-negative (ENG) or mu-negative (MNG). It is assumed that both PEMC cylinder and the coating layer are infinite along the cylinder axis. Both parallel and perpendicular polarization cases are considered for the analysis. Comparison between the monostatic and bistatic echo widths, of a PEMC cylinder coated with metamaterial and coated with ordinary dielectric material (DPS), is presented. The numerical results are compared with the published literature, and comparison is found to be in good agreement. 相似文献
12.
《Waves in Random and Complex Media》2013,23(3):336-348
Abstract Using dielectric permittivity tensor of the magnetized prolate plasma, the scattering of long wavelength electromagnetic waves from the mentioned object is studied. The resonance frequency and differential scattering cross section for the backward scattered waves are presented. Consistency between the resonance frequency in this configuration and results obtained for spherical plasma are investigated. Finally, the effective factors on obtained results such as incident wave polarization, the frequency of the incident wave, the plasma frequency and the cyclotron frequency are analyzed. 相似文献
13.
Christodoulos Athanasiadis 《Reports on Mathematical Physics》2004,53(3):339-350
A time-harmonic plane dyadic electromagnetic field is scattered by a chiral body in a chiral environment. The body is either a perfect conductor or a dielectric. The incident field is a linear combination of left-circularly polarized and right-circularly polarized dyadic electromagnetic fields, each of which has a different wave number. We prove reciprocity and scattering theorems in dyadic form, which incorporate as special cases the corresponding known theorems for vector electromagnetic waves. Specializing to the same direction of incidence and observation in the general scattering theorems we obtain forward scattering theorems. 相似文献
14.
The characteristic of electromagnetic scattering by plasma cylinder is researched in this paper. Scattered fields of the parallel-polarized wave and vertical-polarized wave by plasma cylinder are calculated and analyzed. The calculated results show that the higher the electron density, is the greater the scattering intensity in the outside of the cylinder and the higher the plasma frequency of collision, is the smaller the scattering intensity in the outside of the column. In addition, the electromagnetic wave polarization and frequency of the incident wave also have a significant impact on the scattering intensity of electromagnetic waves, the vertically polarized wave is more likely to be scattered, and the lower frequency of the incident wave is also easier to scattering. These have certain reference value for designing and studying of the plasma antenna. 相似文献
15.
Based on the scales transformation of electromagnetic theory,the analytical expressions of electric fields inside and outside a magnetised cold plasma sphere are presented by reforming the spherical electromagnetic parameter.The obtained results are in good agreement with that in the literature.The angle between the direction of inside field and that of outside field is derived.In S wave band,calculations for the effects induced by parameters of the inner field are established.Simulations show that the angle between incident field and the outside magnetic field influences the inner field remarkably.The inner field will increase as the electron density increases.The inner field varies with frequency nonlinearly.There is an angle between the inner field and the incident field,it changes nonlinearly with the frequency. 相似文献
16.
《Waves in Random and Complex Media》2013,23(3):370-382
The distribution of the electric potential inside and outside a cold plasma column with elliptical cross-section when electromagnetic waves scatter from it are obtained. It is assumed that the wavelength of incident wave is much greater than the dimensions of the cross section of the plasma column. The electrical potential inside and outside a magnetized elliptical plasma column for an anisotropic scattering process are obtained. The graphs of the ratio of the electric field inside the plasma and the incident electric field versus the incident angle, the geometrical dimension of the elliptical plasma column and cyclotron frequency are presented separately. Finally, scattering of the same waves from an elliptical cylindrical inhomogeneous isotropic cold plasma is also investigated. 相似文献
17.
Yiping Han Yang Zhang Huayong Zhang Guoxia Han 《Journal of Quantitative Spectroscopy & Radiative Transfer》2009,110(14-16):1375-1381
The expansions of the incident arbitrary beam shape in spherical, spheroidal and cylindrical coordinates in the general case of oblique illumination are presented. The scattered electromagnetic fields of typical particles of arbitrary orientation illuminated with a beam shape are provided. The numerical results of the normalized scattering cross section are evaluated. 相似文献
18.
Jingjing Chen Feinan Chen Yanru Chen Yu Xin Yongqing Wang Qi Zhao Muchun Zhou 《Optics Communications》2012,285(19):3955-3960
The coherence properties of the scattered field generated by linearly polarized and uniformly unpolarized electromagnetic plane waves incident on anisotropic quasi-homogeneous media are studied. The analytical expressions for the spectral density and the spectral degree of coherence of the three dimensional scattered field are derived. The results of the numerical simulations indicate that not only the properties of the anisotropic media have a great effect on the coherence properties of the scattered field, but also the polarization of the incident wave. And most important, the effect of the polarization of the incident wave on the coherence properties of the scattered field nearly concerns the properties of the anisotropic media. There are also close and interesting relations between the coherence properties of the scattered field that generated by the anisotropic media and by the corresponding isotropic media. 相似文献
19.
Xiaoping Zhu Tongqing Liao Huayong Zhang Rongqing Hui 《Journal of Quantitative Spectroscopy & Radiative Transfer》2012,113(15):1946-1950
Based on the generalized Lorenz–Mie theory that provides the general framework, an analytic solution to Gaussian beam scattering by a chiral sphere is constructed, by expanding the incident Gaussian beam, scattered fields and internal fields in terms of spherical vector wave functions. The unknown expansion coefficients are determined by a system of equations derived from the boundary conditions. For a localized beam model, numerical results of the normalized differential scattering cross section are presented. 相似文献