Ie transmission properties of stratified chiroferrite media with obliquely incident plane wave

A parameter study of electromagnetic wave propagating through the air-chiro ferrite inter face and through a chiro ferrite slab is presented, and such bianisotropic medium can be made from chiral and gyrotropic ferrite materials artifically. The partial differential equations of the fourth order defining the field components E_y and H_y in chiroferrite are derived. The influence of different constitutive parameters on the transmission coefficients and refraction angles of transmitted fields are demonstrated. The results show that chirality causes strong effect of energy conversion between mode 1 and 2.     

Reflection of a transient plane wave obliquely incident on compressible plasma half-space

The expression for the reflected transient pulses from the sharp surface of a compressible plasma half-space are obtained in a series form with the first perturbation order explicitely evaluated and valid for small to moderate compressibility (α = u/C0≤ 0.3, u is the electron acoustic velocity and C0is the velocity of light in free space). The reflected waveform are close to the waveform of cold plasma (α = 0) with noticeable change of amplitude and time delay of the first maxima.     

Closed-form expressions for uniform currents on a wedge illuminatedby TM plane wave

Closed-form expressions for nonuniform currents on a perfectly conducting, infinite wedge illuminated by a transverse magnetic plane wave are presented. The expressions are derived by requiring that they agree with the current predicted by the eigenfunction solution close to the edge and J.B. Keller's geometrical theory of diffraction (1962) far from the edge. The angle of incidence is arbitrary and the expressions remain uniformly valid even for glancing angles of incidence when the geometrical optics boundaries are in the vicinity of the wedge faces. The formulas presented are simple, involving Fresnel functions with complex arguments. These functions can be expressed in terms of complimentary error functions which may be computed using standard subroutine packages. Exact expressions for nonuniform currents are available for the two special cases of half-planes and infinite planes. Closed-form expressions for the axial electric field, and hence all the field components in the vicinity of the wedge axes, are also obtained. Currents computed using expressions obtained are compared with currents computed from the eigenfunction solution of the wedge, with good agreement throughout     

Transient plane wave coupling to bare and insulated cables buriedin a lossy half-space

The current induced on an infinite bare or insulated cable buried in a lossy earth medium due to a transient plane wave is presented. An exact solution is formulated in the frequency domain using a spatial transform under the thin-wire approximation. The widely used equivalent circuit transmission line model is derived from the exact solution. Results are presented for typical transmission structures under high frequency transient excitation and the exact solution is compared with the transmission line approximation. The transmission line approach provides good results for a wide range of cases. For accurate results in the high frequency situation it is necessary that the correct incident field expressions be used and that a complete representation of the earth's electrical properties (σ and ϵ) be retained     

单轴各向异性球对任意方向入射平面波的散射

基于球矢量波函数的正交完备性,给出了具有任意传播方向两种极化模式的平面波用球矢量波函数展开的形式,导出了其展开系数的具体表达式．研究了单轴各向异性介质球对任意方向入射平面波的散射,利用球矢量波函数及傅里叶变换方法得到了各向异性介质球的内场展开式,结合切向连续边界条件给出了散射系数．数值分析了介电常数张量元、有耗、无耗、尺寸参数、入射角和方位角等对单轴各向异性介质球的雷达散射截面的影响．     

Riemann-Green function solution of transient electromagnetic plane waves in lossy media

B. Riemann's (1953) solution of the Cauchy problem for the linear wave equation is used to find a closed-form solution for the problem of transient nonsinusoidal waves is lossy media. A method for finding the required Riemann-Green function is discussed. The evolution of a wavefront propagating in a semi-infinite lossy medium is studied, and a series solution for the corresponding electric field is obtained.<>     

The diffraction of an inhomogeneous plane wave by an impedancewedge in a lossy medium

The diffraction of an inhomogeneous plane wave by an impedance wedge embedded in a lossy medium is analyzed. The rigorous integral representation for the field is asymptotically evaluated in the context of the uniform geometrical theory of diffraction (UTD) so that the asymptotic expressions obtained can be employed in a ray analysis of the scattering from more complex edge geometries located in a dissipative medium. Surface wave excitations at the edge and their propagation along the wedge faces are discussed with particular emphasis on the effects of losses     

BOR-FDTD斜入射脉冲平面波一维时域算法

针对斜入射脉冲波不能直接引入BOR-FDTD计算的问题,根据柱坐标系统中入射波在对称轴方向只有时间延迟的特性,结合平面波的柱面波展开,提出了一种行之有效的计算BOR-FDTD中斜入射脉冲平面波的一维时域算法,从而避免了大量快速傅里叶变换运算,节省了计算时间.计算结果表明该算法运行速度比基于完全傅里叶变换的算法快50倍.就整个程序运行时间而言,一维时域算法可以节省约20%的计算时间.为了验证该算法的有效性,计算了高斯脉冲斜入射时有限长金属圆柱体的散射问题,提取出某一频率下圆柱体母线电流密度分布并与MoM计算结果比较,二者吻合较好.然后计算了金属球的单站RCS随频率的变化,所得结果与理论值一致性也很好.     

Diffraction of a normally incident plane wave at a wedge withidentical tensor impedance faces

Diffraction of a normally incident plane wave by a wedge with identical tensor impedance faces is studied and an exact solution is obtained by reducing the original problem to two decoupled and already solved ones. A uniform asymptotic solution then follows from the exact one and agrees excellently with numerical results due to the method of parabolic equation     

On the scattering of an obliquely incident plane wave by a biisotropic cylinder

Scattering of an obliquely incident electromagnetic plane wave by an infinitely long, homogeneous, biisotropic cylinder is addressed. The ambient host medium considered is isotropic, homogeneous and dielectric-magnetic. It is observed that the constitutive coupling of the electric and the magnetic fields in the biisotropic material causes the cross-polarization component of the scattered field not to vanish even for the normal incidence case.     

New results for the effective propagation constants of nonuniform plane waves at the planar interface of two lossy media

This paper presents a correction and a generalization of the solution presented previously (for original papers see R. D. Radcliff and C. A. Balams, "Modified propagation constants for nonuniform plane wave transmission through conducting media," IEEE Transactions in Geoscience Remote Sensing, vol. GE-20, no. 3, p. 408-411 (1982) and C. A. Balams, Advanced Engineering Electromagnetics, New York: Wiley (1989)) for the effective propagation constants of nonuniform plane waves at the planar interface of two isotropic homogeneous possibly lossy media of infinite transverse dimensions.     

Currents induced in a wire cross by a plane wave incident at an angle

The currents induced in a thin-wire cross with equal mutually perpendicular arms by an incident plane electromagnetic wave are determined when the normal to the wave front is perpendicular to the horizontal wire and is at an anglethetawith respect to the vertical wire; the direction of the electric vector in the wave front is arbitrary. The analysis is formulated in general terms but explicit formulas are obtained only for the zero-order currents which are generally adequate to determine the scattered field of very thin wires. The relatively simple formulas consist of even and odd parts for both the vertical and horizontal wires; they include components due to mutual coupling as well as those excited directly by the incident field.     

Diffraction by a half-plane with two face impedances uniform asymptotic expansion for plane wave and arbitrary line source incidence

A uniform asymptotic expansion (UAE) of Maliuzhinets' exact solution for incident plane wave diffraction by a half-plane with two face impedances has been obtained using Van der Waerden's method. This solution has been further extended to the case of arbitrary line source incidence using a heuristic approach.     

High-frequency surface currents induced on a perfectly conducting cylindrical sheet by an obliquely incident plane wave

Explicit expressions for the surface currents of different kinds induced on a perfectly conducting cylindrical sheet by an obliquely incident high-frequency plane wave are derived. The results are in such forms that they can both be used directly in numerical applications and permit us to understand the structure of the induced surface current. It is shown that the components due to the surface and edge diffractions propagate along certain geodesic lines on which the transfer coefficients as well as the attenuation constants are dependent only on the curvature radius.     

Diffraction of a normally incident plane wave by three parallel half-planes with different face impedances

The diffraction problem of plane waves by a set of three parallel half-planes one of which is placed in the opposite direction and having characterized with different surface impedances on upper and lower faces is solved by mode-matching method where available and Fourier transform technique elsewhere. The solution includes two independent Wiener-Hopf equations each involving infinite number of expansion coefficients which satisfy an infinite system of linear algebraic equations. After the determination of these coefficients numerically, some graphical results are presented showing the influence of the surface impedances and the distances between the half-planes on the diffracted and transmitted waves.     

Spectral FDTD: a novel technique for the analysis of oblique incident plane wave on periodic structures

This paper introduces a new technique which calculates the reflection coefficient for the plane wave incident on planar periodic structures. The method referred to as spectral finite-difference time-domain (SFDTD) replaces the conventional single-angle incident wave, with a constant transverse wavenumber (CTW) wave. Because the transverse wavenumbers are constant, the fields have no delay in the transverse plane (x-y plane), and PBC (periodic boundary condition) can be directly implemented in the time domain for both oblique and normal incident waves. The stability criterion for this new FDTD technique is angle-independent and therefore this method works well for incident angles close to grazing (/spl theta/=90/spl deg/) as well as normal incident (/spl theta/=0/spl deg/). This shows the efficiency of the method compared to other available FDTD techniques for the same purpose that force a more restricted stability criterion as angles turns to grazing. The validity of this method is verified by comparing the reflection coefficient calculated by this method with the analytical results of a grounded slab. The results of this technique are also compared with method of moments for a periodic array of metallic patches and a good agreement is observed. A periodic array of metallic patches above a PEC plate is analyzed and the reflection coefficient is calculated over a wide frequency band for angles varying from 0/spl deg/ to close to 90/spl deg/.     

Scattering of a plane wave by a cascade of two frequency-selective structures

Propagation of a plane electromagnetic wave through a multilayer frequency-selective dielectric structure with biperiodic metallization of two interfaces is considered. A method is proposed for calculation of the reflection and transmission coefficients of the structure. Computation results are presented for a structure with gratings consisting of metal rings. The effects of longitudinal and transverse shifts of gratings on the electrodynamic characteristics of the frequency-selective structure are studied. The computation results are compared to experimental data obtained in the microwave band.     

Diffraction of a plane wave by a sector with Dirichlet or Neumann boundary conditions

The problems of diffraction by a screen occupying an infinite sector with Dirichlet or Neumann boundary conditions are addressed by the random walk method. The solution is represented as a superposition of the wave field completely determined by an elementary ray analysis and of the field formed by the waves diffracted by the tip of the screen. The diffracted field is explicitly represented as a mathematical expectation of a specified functional on trajectories of a random motion whose behavior is determined by the configuration of the problem and by the boundary conditions. The numerical results confirm the efficiency of the random walk approach to the analysis of diffraction by wedge-shaped screens of different angles.     

入射平面波复射线展开精度的分析

从复射线展开表达式出发,通过参数变换,得到了入射平面波复射线展开拟合精度的单变量表达式,利用该式对展开面上及离开展开面后的拟表度进行了系统的讨论,建立了一种系统分析入射平面波复射线展开精度的方法。这一方法有助于建立通用的任意目标散射复射线分析软件。