共查询到20条相似文献,搜索用时 78 毫秒
1.
采用移位算子方法把时域有限差分法推广应用于二维磁各向异性色散介质—磁化铁氧体中.证明了电磁波横向入射二维轴向磁化铁氧体目标情形下,电磁波可按目标的轴向分解为横电波(TE波)和横磁波(TM波),且TE波的散射特性与铁氧体介质无关,而TM波的散射特性与介质电磁参量密切相关,同时对其物理原因进行了分析.通过采用移位算子方法处理磁化铁氧体频域本构关系,得到该情形下目标电磁散射的移位算子时域有限差的迭代计算公式,同时解决了电磁波在各向异性和频率色散介质中传播的问题.计算了轴向磁化铁氧体涂敷VonKarman型导体柱的TM波双站雷达散射截面,分析了铁氧体参量对目标双站雷达散射截面的影响.结果表明:恰当地选择铁氧体参量能有效地减少目标的雷达散射截面,本文时谐因子取exp〔jωt〕. 相似文献
2.
V. Kalesinskas A. Konstantinov V. Shugurov 《International Journal of Infrared and Millimeter Waves》1997,18(6):1269-1279
The paper is devoted to the problem of scattering of plane electromagnetic wave by transversely magnetized ferrite cylinder.
Exact analytical expressions for all partial cylindrical modes are obtained by solving Maxwell’s equations for transversely
magnetized ferrite medium in cylindrical coordinate system. They are represented as the power series expansion and then are
used to formulate and to solve the boundary problem. Numerical calculations of scattering patterns are also presented. Particular
attention is paid to the possibility to control the scattering pattern by the external magnetic field. 相似文献
3.
Absorbers and reflectors of electromagnetic waves have many applications, and so the interactions between electromagnetic waves and low-temperature plasma, particularly numerical analysis of reflection, absorption, and transmission of electromagnetic waves in unmagnetized, magnetized, nonuniform, and uniform plasma, have been a topic of intensive research. For instance, Laroussi numerically evaluated the interactions between electromagnetic waves and a uniform magnetized plasma cylinder, and Helaly and Yeh studied the scattering from nonuniform magnetized plasma cylinders. 相似文献
4.
The total amplitude reflection coefficient of EM wave in a nonuniform plasma slab coated on perfect conductor plane is newly derived by using the scattering matrix method (SMM), and the attenuation is calculated. Three types of plasma electron density profile, that is the hyperbolic, sinusoidal, and linear profiles, are used. The external magnetic field and plasma parameters such as the maximum electron density and collision frequencies are discussed to calculate the attenuation of EM wave. The calculation results show that the plasma electron density profile and maximum electron density exert a large effect to the attenuation of EM wave and the attenuation under the uniform external magnetic field is taken place by the electron cyclotron resonance absorption, the up hybrid resonance absorption and geometric resonances absorption. 相似文献
5.
N. Iqbal 《Waves in Random and Complex Media》2018,28(4):589-600
Scattering of electromagnetic waves from a perfectly electrical conducting (PEC) cylinder of circular cross-section, coated with uniaxial non-magnetic chiral anisotropic medium, was discussed. A conducting sheath helix structure with adjustable pitch angle exists over the outer surface of coated cylinder, which is interfaced with the free-space. Under the uniform parallel polarized plane wave with fixed oblique incidence angle, the echo widths were determined emphasizing the other relevant scattering-related parameters (e.g. scattering/extinction efficiency etc.), taking into account different pitch angle values (of the sheath helix) and the kinds of coating mediums. The results revealed that the coating of negative uniaxial chiral medium causes enhancement in scattering efficiency (of the scatterer). Also, the scattering efficiency was found to be the same as the extinction efficiency, thereby yielding vanishing absorption of the medium. The obtained results were also compared with the situation of vanishing chirality of coating medium over the PEC cylinder; the echo width and scattering efficiency both decrease in this case. 相似文献
6.
Tang D.L. Sun A.P. Qiu X.M. Chu P.K. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》2003,31(3):405-410
The absorption, reflection, and transmission of electromagnetic waves by a nonuniform plasma slab immersed in an ambient uniform magnetic field of various strengths are studied in this paper. The effects of the plasma parameters and magnetic field strength on the absorbed, reflected, and transmitted power are discussed. The magnetized nonuniform plasma slab is modeled by a series of magnetized uniform plasma subslabs. The calculation results show that the effects of the magnetic field strength and density gradient on the absorbed power, as well as the frequency band of resonant absorption, are significant. A complete analysis utilizing the scattering matrix method is also used to compare the above calculation results which neglect multiple reflections between subslab interfaces. Broadband absorption of electromagnetic waves can be achieved by changing the magnetic field strength and plasma density. More than 90% of the electromagnetic wave power can be absorbed in a magnetized nonuniform plasma slab with width of 12 cm and the absorption bandwidth can range from 1 to 20 GHz with different plasma parameters and external magnetic field strengths. 相似文献
7.
V. Kalesinskas V. Shugurov 《International Journal of Infrared and Millimeter Waves》1995,16(11):2035-2044
The paper presents a rigorous solution of the diffraction problem by a finite set of magnetized ferrite cylinders. The main purpose of the research is to determine the steerability of scattering diagram of diffraction by several longitudinally magnetized ferrite cylinders. A plane wave scattering as well as main mode scattering by cylinders in the open end of rectangular waveguide are considered and numerical investigations are presented. 相似文献
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W. B. Dou Edward K. N. Yung 《International Journal of Infrared and Millimeter Waves》2000,21(6):1001-1017
The scattering field of a ferrite post and a cylindrical ferrite post containing conducting post illuminated by a plane wave is analyzed. The special interest is the scattering property of the ferrite posts, which is resonating at certain modes such as TM11 mode. We hope to know the speciality it shows and find its applications. It is found that the scattering field pattern of a resonating ferrite post is similar to the rotation of the scattering field pattern of a dielectric cylindrical post, which has the same dimension as ferrite. The scattering properties of the ferrite may give us some inspirations to explore its applications in microwave components. This property is utilized to explain the mechanism of the operation of the circulators. It also may be used in microstrip patch antenna, coupler and filter to control their properties. Other applications may be possible too. Some calculation results are presented. 相似文献
10.
Makoto Ohki Haruo Sakurai Jun Horikoshi Syogo Kozaki 《International Journal of Infrared and Millimeter Waves》1996,17(5):871-886
Exact solution of the electromagnetic wave scattering by N dielectric cylinders is presented by using matrix formulation. To check this present method, two comparisons between exact solutions for a single circular conducting and dielectric cylinder and this model composed of N=25 circular cylinders are made. Numerical results of conducting and dielectric square cylinder has been also checked with well-known result (B.E.M). The scattering patterns and the near field distributions in space are presented for the concave, convex and dielectric circular cylinder with conducting reflector. 相似文献
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12.
将移位算子(shift operator,SO)-时域有限差分(fintie difference time domain,FDTD)方法推广到外磁场沿任意方向时磁化铁氧体的情形.从磁化铁氧体的相对磁导系数张量和各向异性情形下Maxwell旋度方程出发,推导出外磁场沿任意方向情形下磁化铁氧体电磁散射的SO-FDTD迭代公式.应用该方法计算了磁化铁氧体层、磁化铁氧体球及含磁化铁氧体涂层的Von Karman形雷达罩电磁散射,数值计算结果表明了该算法的正确有效性.
关键词:
磁化铁氧体
FDTD
移位算子法 相似文献
13.
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
14.
Juozas Bucinskas Liudmila Nickelson Romanas Martavicius 《Applied Physics A: Materials Science & Processing》2014,115(2):467-473
We present here for the first time the rigorous solution of the boundary diffraction problem of microwave scattering by a multilayered 2D cylinder. The cylinder layers may be made of isotropic, uniaxial anisotropic, electrically and (or) magnetically gyrotropic materials. The number and thickness of the layers may have arbitrary values in our solution. We calculated scattering diagrams (a radial component of real part of the Poynting vector) inside and outside of cylinder using the solution. Here we present scattering diagrams from a three-layered cylinder made of SiC and metamaterial or saturate magnetized ferrite. Diagrams were computed for wave incidence angles θ=π/2,π/3,π/6 inside of metamaterial/ferrite layer at a distance of 1 mm and outside of cylinder at a distance of 2.5 mm from the cylinder axis. 相似文献
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W. B. Dou T. Shen Z. L. Sun 《International Journal of Infrared and Millimeter Waves》1994,15(7):1247-1253
The scattering of a Gaussian beam by a ferrite cylinder is analyzed using two methods. The spatial pictures in the amplitude of the total Gaussian beam near the cylinder resulting from the two methods are both clarified and compared. The scattering by a ferrite cylinder coating a dielectric sleeve is also presented. 相似文献
18.
Muhammad Arshad Fiaz Muhammad Aqueel Ashraf Azhar Abbas Rizvi 《Waves in Random and Complex Media》2018,28(1):60-75
Scattering from a perfect electric conducting cylinder with random radius buried below a half space dielectric homogenous interface is studied. The cylindrical wave scattered by cylinder is expanded in terms of plane wave spectrum. Small perturbation method is used to study the interaction of each plane wave with the interface. The zeroth order term yields solution for a flat interface, whereas scattering from a rough surface is given by first-order term. Results are obtained for both TM and TE polarizations. Analytical expressions of the average scattered field are obtained and verified using numerical evaluation. Different scattering scenarios are simulated by varying the distribution of the radius. It is observed that average scattering cross section of an ensemble with normal/uniform distribution is almost equal to that of a cylinder with mean radius. 相似文献
19.
Makoto Ohki Haruo Sakurai Jun Horikoshi Syogo Kozaki 《International Journal of Infrared and Millimeter Waves》1996,17(10):1707-1718
Rigorous expression of the electromagnetic beam wave scattering by N circular cylindrical models is described. To check this method, comparison between exact solution and this model composed of N=24 circular cylinders is presented for a single circular conducting cylinder. Numerical results of conducting square cylinder has been also checked with well-known result (B.E.M). 相似文献