非均匀介质结构中线天线辐射问题的有限元-边界积分方法

采用有限元边界积分方法,通过把所求解区域分成内外两部分,内场用有限元计算,外场用边界积分计算,分析了线天线辐射问题.边界积分采用伽略金方法处理,并用变换解决了积分方程的奇异性问题,最后给出了仿真结果.     

基于边界元法的微结构光波导模场分布研究

本文基于加权余量法,阐述了利用边界元法求解矢量亥姆霍兹方程的数学基础-亥姆霍兹方程的边界积分方程;并推导了数值求解该边界积分方程的方法;利用推导结果,编写计算机程序分析了圆光波导的模式场分布情况。实验结果表明,该方法可以在较低方程组阶数,较少输入数据量的前提下准确地分析微结构光波导内模式场的分布情况。     

电磁场边界元法分析中的域积分和奇异积分问题及一种改进边界元法

在电磁场边界元法中，域积分和奇异积分的计算是经常遇到的困难之一。本文概述几种把域积分化为边界积分及计算奇异积分的有效方法，并介绍用齐次方程的基本解系作权函数的一种改进型边界元法。改进边界元法消除了传统边界元法中的固有奇异性，计算精度和效率都较高，是更为有效的一种方法。     

基于奇异值分解的方法求解目标内谐振时的散射截面

表面积分方程已被广泛地用来分析电磁散射问题,但在离散的内谐振频率点上,用矩量法求解积分方程将得到错误的结果.本文基于电场积分方程,应用奇异值分解找出谐振模电流,并采用正交化方法将其舍去,从而得到非谐振模电流的分布.文中计算了一无限长理想导体圆柱内谐振时的散射截面,所得结果与解析解一致,并对一无限长理想导体三角柱的前向散射截面进行了计算,结果表明本文方法是有效和准确的.     

高速电路电源/地层间阻抗参数计算与分析

为了快速准确地计算高速电路地层与电源层之间的阻抗参数,基于边界积分方程提出了有效的计算方法.该方法充分利用了实际电源层/地层的结构特征,将三维电磁场问题转化为二维问题,减少了计算时间.由于在计算中不需要考虑整个 电源层/地层结构的格林函数,故该方法可以用于任意边界形状的电路板.基于提出的积分方程法,分析了介质相对电介质...     

高速大规模电路系统互连线电阻矩阵的边界积分算法

本文用边界积分法计算高速大规模电路系统互连线的电阻矩阵，文中进行了边界积分方程的推导及将其转换为矩阵方程后计算电阻矩阵的方法，最后以实例说明其计算结果及适用范围。     

本征权边界积分法解任意截面波导传输问题

本文选取本征函数作为权函数,由格林第二恒等式建立边界积分方程,并采用边界基形式得到线性齐次方程组。这种方法不仅降低了系数矩阵的维数,而且使其各项仍保持为简单一项,减少了计算量.本文提供了几种常见金属波导的例子,计算结果既收敛快、又足够准确。     

二维扩散方程边界元解法中的四重奇异积分计算

对二维热传导方程的Dirichlet初边值问题,采用带时间变量的基本解,利用基于单层位势的间接边界积分方程及其等价的Galerkin变分形式求解,该方法涉及到与时空相关的四重奇异积分的计算.在采用常单元离散的情况下,推导了具体实施数值计算所需的积分公式,完成了数值实验,验证了该方法的有效性和可行性.     

电磁场与微波技术

(〕月4,024 94050850电磁场边界元法分析中的域积分和奇异积分问题及一种改进边界元法/马西奎(西安交通大学)11光纤与电缆及其应用技术一1 994,(2)一1一7 概述了几种把域积分化为边界积分及计算奇异积分的有效方法,并介绍用齐次方程的基本解系作权函数的一种改进型边界法。改进边界元法消除了传统边界元法中的固有奇异性,计算精度和效率都较高,是更为有效的一种方法.表1参5(北)数.表1参8(北)044 94050851最小二乘边界配点法在电磁场边值问题数值分析中的应用/马西奎(西安交通大学)lj微波学报一1994,(2)一17~22 进行了最小二乘边界配点法在电…     

任意截面金属波导截止波数的边界元解法

本文从实对称核积分方程出发,给出了用边界元法求任意截面均匀填充金属波导截止波数的一般方法。采用实对称核积分方程而不用常用的复型核,可使数值计算大大简化,但要引入赝解。本文给出赝解的两种判别法,并且容易除去。最后对几种常见的金成波导作了数值计算,表明这种方法是有效的。     

New boundary integral equations for CAD of waveguide circuits:guided-mode extracted integral equations

Novel boundary integral equations which are applicable to the analysis of many kinds of waveguide circuits are presented. The new integral equations can treat the waveguide discontinuity problems like the scattering by the isolated finite-sized metallic objects or cavity problems and do not use normal-mode expansion techniques. They are suitable for the basic theory of CAD software for various waveguide circuits. The two-port and H-plane waveguide discontinuity problems which satisfy the single-mode and two-mode conditions are treated. The case of waveguide corner bend is considered as an example. Numerical examples are shown in order to confirm the validity of the new integral equations     

Integral equation method in problems of electromagnetic-wave reflection from inhomogeneous interfaces between media

Problems on reflection of a plane electromagnetic wave from various irregular interfaces between media are studied by the integral equation method in the cases of two- and three-dimensional incident electromagnetic field. The reflecting surfaces are meant as periodic transparent interfaces between two media and plane boundaries with locally inhomogeneous and transparent sections. The boundary value problems for the system of Maxwell’s equations in an infinite domain with an irregular boundary are reduced to Fredholm or singular integral equations, depending on the problem considered. Numerical algorithms for solving such integral equations are developed. Results of calculation of currents induced on inhomogeneities and characteristics of the electric field in the far zone are presented.Problems on reflection of a plane electromagnetic wave from various irregular interfaces between media are studied by the integral equation method in the cases of two- and three-dimensional incident electromagnetic field. The reflecting surfaces are meant as periodic transparent interfaces between two media and plane boundaries with locally inhomogeneous and transparent sections. The boundary value problems for the system of Maxwell’s equations in an infinite domain with an irregular boundary are reduced to Fredholm or singular integral equations, depending on the problem considered. Numerical algorithms for solving such integral equations are developed. Results of calculation of currents induced on inhomogeneities and characteristics of the electric field in the far zone are presented.     

Radiation properties of an arbitrarily flanged parallel-plate waveguide

The radiation properties of an arbitrarily flanged parallel-plate waveguide are investigated by means of the boundary integral equations that are called guided-mode extracted integral equations. The boundary integral equations derived in this paper can be solved by the conventional boundary-element method. Numerical results are presented for a number of cases of flanged parallel-plate waveguide. Reflection coefficient, reflected and radiated powers as well as radiation patterns are numerically calculated for the incidence of transverse electric guided-mode wave.     

The Maxwell's equations in the sense of distributions

It is well known that there is no direct one-to-one correspondence between the electromagnetic theory based on the physical laws and that based on the Maxwell's differential equations. For example, in order to derive the boundary conditions from the Maxwell's differential equations, one assumes that some integral identities derived from them are valid even when the field components (or material parameters) are discontinuous. This assumption violates, in a sense, the completeness of the theory of electromagnetism based on the Maxwell's differential equations. We will prove that if one postulates that the Maxwell's equations are valid in the sense of distributions, then this incompleteness will be removed and the boundary conditions will appear implicitly in the basic differential equations.     

The spreading resistance of an inhomogeneous slab with a disc electrode as a mixed boundary value problem

This paper presents a treatment of the mixed boundary value problem that arises in determining the spreading resistance of an inhomogeneous slab backed by a perfectly conducting substrate. It is shown that the inhomogeneity enters into the problem through the weight function of a pair of dual integral equations, and that this function is the same as the integration factor that occurs in previous approximate solutions based on assumed source current distributions. Except for the difference in the weight function, the dual integral equations are similar to those for the homogeneous slab. Calculations are performed for structures with exponential resistivity profiles, and the results used to determine the accuracy of three approximate methods currently available for spreading resistance calculations on semiconductor device structures.     

SOLUTION OF ARBITRARY CROSS-SECTION WAVEGUIDE USING METHOD OF EIGEN WEIGHTED BOUNDARY INTEGRAL EQUATION

Based on the second kind of Green's identity,a boundary integral equation forarbitrary cross-section waveguide is transformed to a system of linear homogeneous algebraicequations by means of expansion of boundary bases and by using the eigenfunctions of a fictitiousregular boundary as weighting functions,which corresponds to less algebraic equations than BEMand simpler coefficients than the modified BEM.The numerical results for some typical metallicwaveguides are given by using the method of eigen-weighted boundary integral equation,and theyare accurate enough with fast convergence.     

Effect of dead space on gain and noise in Si and GaAs avalanchephotodiodes

The effect of dead space on the mean gain, the excess noise factor, and the avalanche breakdown voltage for Si and GaAs avalanche photodiodes (APDs) with nonuniform carrier ionization coefficients are examined. The dead space, which is a function of the electric field and position within the multiplication region of the APD, is the minimum distance that a newly generated carrier must travel in order to acquire sufficient energy to become capable of causing impact ionization. Recurrence relations in the form of coupled linear integral equations are derived to characterize the underlying avalanche multiplication process. Numerical solutions to the integral equations are obtained and the mean gain and the excess noise factor are computed     

Extended boundary condition integral equations for perfectly conducting and dielectric bodies: Formulation and uniqueness

The equivalence theorem is used to derive novel generalized boundary condition (GBC) integral equations for the tangential components of the electric and magnetic fields on the interfaces of a finite number of dielectric or conducting scatterers. Closed surface, plane, and line extended boundary conditions (EBC) equivalent to the GBC are introduced. The GBC integral equations can now be replaced by any of these EBC integral equations whose solutions are unique and easy to obtain numerically using the moment method. A perfectly conducting sphere and a dielectric sphere in the electrostatic field of two equal and opposite point charges are presented as simple examples of the general procedure.     

Equivalent network representation of boundary conditions involving generalized trial quantities

Virtual adjustable sources are introduced in equivalent network representation of boundary conditions. For this purpose, integral equations are to be solved simple application of analog Kirchoff’s and Ohm’s laws. These adjustable sources represent generalized trial quantities. In order to illustrate this proposed approach, equivalent network representation of lossy planar transmission lines with arbitrary metallization thickness is presented.     

Higher order impedance boundary conditions applied to scattering bycoated bodies of revolution

In this paper higher order impedance boundary conditions will be employed in the solution of scattering by coated conducting bodies of revolution. The higher order impedance solution reduces the total number of unknowns relative to the exact solution, and produces a system matrix which is less dense than that of the exact solution. The construction of the solution involves two distinct steps. In the first step the body of revolution is replaced by an equivalent set of electric and magnetic currents on its exterior surface which generate the true fields outside the body. An integral equation relating these currents through the free space Green's function is derived. Step two employs the higher order impedance boundary condition to relate the electric and magnetic currents on the surface of the body. This replaces the rigorous solution of the interior problem. The higher order impedance boundary conditions are derived by obtaining an exact impedance boundary condition in the spectral domain for the coated ground plane, approximating the impedances as ratios of polynomials in the transform variables, and employing the Fourier transform. The resulting spatial domain differential equations are solved in conjunction with the integral equation using the method of moments. Several examples of bistatic and monostatic radar cross section for coated bodies of revolution are used to illustrate the accuracy of the higher order impedance boundary condition solution relative to the standard impedance boundary condition solution and the exact solution. The effects of coating thickness, loss, and curvature on the accuracy of the solution are discussed