Scattering of a Gaussian beam by a dielectric rectangular cylinder

For purpose of finding the dielectric constant, a new expression of the beam scattering is obtained by using the boundary element method (BEM) with extended boundary conditions. Comparison between with and without the resonant condition was made for the total scattered power. To find the accuracy, convergence property of the total scattered power versus divided number has been examined. To check the boundary conditions at the corner of the scatter, the electric field difference between inner and outer side has also been calculated and confirmed. The total electric field distributions in space are illustrated for the plane and beam wave. Microwave experiments was also performed     

Scattering by a nihility cylinder

The total scattering and the extinction efficiencies of a nihility cylinder of infinite length and circular cross-section are identical and independent of the polarization state of a normally incident plane wave.     

厄米-高斯波束对各向异性圆柱的散射特性研究

为了研究厄米-高斯波束在各向异性媒质中的散射特性，采用了将各向异性圆柱的散射场和内部场用圆柱矢量波函数展开，应用电磁场边界条件和投影法，提出了一种分析单轴各向异性圆柱对厄米-高斯波束散射特性研究的精确半解析方法; 获得了厄米-高斯波束通过单轴各向异性圆柱的内场以及近场的归一化强度分布图; 对两种不同的厄米高斯波束入射情形做出了分析和对比。结果表明，两种波束在通过圆柱后都有入射波和反射波叠加而成的驻波现象，而TEM₁₀(x′)模式厄米-高斯波束入射后近场强度增强，且有明显的折射现象。该研究结果对厄米-高斯波束的应用具有一定的参考价值。     

Scattering by an inhomogeneous dielectric/ferrite cylinder ofarbitrary cross-section shape-oblique incidence case

A moment method (MM) solution is developed for the fields scattered by an inhomogeneous dielectric/ferrite cylinder of arbitrary cross-section. The incident field is assumed to be a plane wave of arbitrary polarization with oblique incidence with respect to the axis of the cylinder. The total electric and magnetic fields are the unknown quantities in two coupled equations from which a system of linear equations is obtained. Once the total electric and magnetic fields within the cylinder are computed, the scattered fields at any other point in space can be calculated. It is noted that for the case of oblique incidence, the scattered field has TE_z and TM_z polarized fields regardless of the polarization of the incident field. The echo widths of cylinders and shells of circular, semicircular, and rectangular cross section are calculated for TE_z and TM_z polarized incident fields. It is shown that the results obtained for dielectric/ferrite cylinders and shells of circular cross section with the solutions developed here agree very well with the corresponding exact eigenfunction solutions     

Scattering by a multilayer chiral cylinder

An efficient recursive eigenfunction solution for the problem of scattering by a multilayer chiral circular cylinder, with or without a surface impedance center cylinder, is presented. For an M layer cylinder, the solution requires the multiplication of M4×4 matrices, versus the solution of a 4M×4M matrix equation in a standard approach. The problem of a transverse electric (TE) incident plane wave differs from that of a transverse magnetic (TM) wave only by a plus/minus sign at one step in the solution. The addition of the surface impedance center cylinder requires only one additional matrix multiplication. Numerical results, including echo width and internal fields, are presented for several sample cylinders     

Scattering of a Gaussian laser beam by a large perfectly conducting cylinder: physical optics and exact solutions

Two particularly accurate solutions representing the scatter of a Gaussian laser beam from a perfectly conducting cylinder, one a physical optics solution using a series Green's function and the other an exact solution, are developed. A comparison of their resulting numerical data follows in order to validate the two solutions. The practicality of these solutions is then demonstrated by using the exact solution to plot the power distribution of the scattered beam on a sensor, and to confirm that the strategic placement of a cylinder in the path of a laser beam enables amplification of the laser beam deflection angle.     

Scattering by thin wire loaded with a ferrite ring

A coupled integral equation formulation and a method of moments (MoM) solution are presented for the problem of scattering by a thin conducting wire of circular cross section with ferrite loading. It is proved that ferrite loading can be used to reduce the radar cross section of long thin objects at their resonant frequency     

Scattering by cavity-backed antennas on a circular cylinder

Conformal arrays are popular antennas for aircraft, spacecraft, and land vehicle platforms due to their inherent low weight, drag, and observables. However, to date there has been a dearth of rigorous analytical or numerical solutions to aid the designer. In fact, it has been common practice to use limited measurements and planar approximations in designing such nonplanar antennas. We extend the finite element-boundary integral method to scattering by cavity-backed structures in an infinite, metallic cylinder. In particular, we discuss the formulation specifics, such as weight functions, dyadic Green's function, implementation details, and particular difficulties inherent to cylindrical structures. Special care is taken to ensure that the resulting computer program has low memory demand and minimal computational requirements. Scattering results are presented and validated as much as possible     

Scattering by a lossy dielectric cylinder in a rectangularwaveguide

Electromagnetic fields in a rectangular waveguide containing a lossy dielectric cylinder are investigated by means of the orthogonal expansion method. The calculated results are provided by measurement. Resonance effects become visible through the frequency responses of the scattering parameters and understandable by patterns due to magnetic fields and Poynting vectors. The lowest resonance is nonsymmetric and can be used to realize tunable bandstop filters with a relative 3-dB bandwidth of about 0.04 and an attenuation of more than 40 dB     

Scattering by a chiral cylinder of arbitrary cross section

An integral equation and method-of-moments (MM) solution to the problem of scattering by an inhomogeneous chiral cylinder of arbitrary cross section is presented. The volume equivalence theorem for chiral media is developed and used to formulate a set of coupled integral equations for the electric and magnetic volume polarization currents representing the chiral cylinder. These coupled integral equations are solved using a standard pulse basis and point-matching MM solution. Numerical results, including echo width and internal fields, are presented for the scattering by chiral slabs and circular cylinders. These results are compared to exact solutions when available     

Scattering of electromagnetic plane waves by a circular cylinder

Numerical investigation of scattering electromagnetic plane waves by a circular conducting cylinder is considered. The results presented are 1) validity of asymptotic far-field expressions when it is applied to calculate near-field around the cylinder and 2) equicontours of amplitude and phase of total field around the cylinder.     

Scattering by a slightly rough cylinder and a cylinder with an impedance boundary condition

The two-dimensional problems of an E-polarized wave incident on a slightly rough perfectly conducting cylinder and also a cylinder with an impedance boundary condition are considered. Numerical results for a. rectangular cylinder are presented to illustrate the similarities between thesis two cases.     

Scattering by a rotating circular cylinder with finite conductivity

The effect of motion on the signal scattered by a rotating circular cylinder with finite conductivity is investigated. The problem is solved by means of the "instantaneous rest-frame" hypothesis. The analysis shows that a surface current must be taken into account to calculate the jump in the tangential magnetic field at the cylindrical surface. This holds even in the case of finite conductivity. For a perfectly conducting cylinder, the influence of the motion on the fields is negligible. This is shown by considering the limit of high but finitesigma.     

高斯光束在照相机中的传输

本文对高斯光束在照相机中的成象特性，进行了详细的分析。结果表明，高斯光束的成象位置与均匀球面光波的成象位置之间，存在着明显的差剐。     

Scattering of a beam wave by a spherical object

The theoretical analysis of the scattering of a beam wave by a small spherical object, which exists at the neighborhood of the beam waist on the propagation axis, is treated. In this analysis, the property of a spherical object is generalized so as to have anr-dependent dielectric constant. Through numerical calculations for the case of the conducting sphere, the difference between the scattering of a beam wave and that of a plane wave are discussed.     

Scattering by a dielectric cylinder of arbitrary cross section shape

The theory and equations are developed for the scattering pattern of a dielectric cylinder of arbitrary cross section shape. The harmonic incident wave is assumed to have its electric vector parallel with the axis of the cylinder, and the field intensities are assumed to be independent of distance along the axis. Solutions are readily obtained for inhomogeneous cylinders when the permittivity is independent of distance along the cylinder axis. Although other investigators have approximated the field within the dielectric body by the incident field, we treat the total field as an unknown function which is determined by solving a system of linear equations. In the case of the dielectric cylindrical shell of circular cross section, this technique yields results which agree accurately with the exact classical solution. Scattering patterns are also presented in graphical form for a dielectric shell of semicircular cross section, a thin homogeneous plane dielectric sheet of finite width, and an inhomogeneous plane sheet. The effects of surface-wave excitation and mutual interaction among the various portions of the dielectric shell are included automatically in this solutiom     

单轴双各向异性媒质柱体的电磁散射

采用广义多极子技术（Ｇｅｎｅｒａｌｉｚｅｄ Ｍｕｌｔｉｐｏｌｅ Ｔｅｃｈｎｉｑｕｅ,ＧＭＴ）分析了单轴双各向异性媒质任意截面柱体的电磁散射,计算结果与解析解和矩量法（Ｍｅｔｈｏｄ ｏｆ Ｍｏｍｅｎｔｓ,ＭｏＭ）所得结果一致,讨论了该方法在电磁散射应用中的优缺点。     

Scattering of a plane wave by a circular cylinder with uniformlyincreasing radius

The interest in the problems of diffraction by moving objects has become obvious due to the applications of nonstationary models for the simulation of different processes. Among them are radar control for the industry ejections or military explosions in the atmosphere and scattering by moving fronts of ionization, or by mobile artificial space objects. The detailed analysis of such processes implies the choice of an adequate model that on the one hand can be effectively investigated but on the other hand ensures a reliable approximation for the complex nonstationary processes. From this point of view, the set of canonical problems that can be solved accurately has great practical significance. We study the diffraction of an electromagnetic plane wave by a circular cylinder with a uniformly increasing radius. The formulation and analysis include propagating singularities as well as the continuous component of the solution. An accurate result is developed by means of separation of variables. Some numerical examples are discussed     

Scattering of long waves by a cylinder with an inhomogeneous sheath

This note deals with a perfectly conducting infinitely long circular cylinder coated with a radially stratified sheath. Scattering of normally incident plane electromagnetic waves is considered at low frequencies, and a resonance condition is derived.