多层介质多导体传输线的小波矩量法分析

全电荷格林函数法是解决分层介质的多导体传榆线的参数提取的一个通用有效的方法，但是用矩量法处理时需将导体表面和介质分界面一起剖分，系数矩阵的阶数较大，计算效率降低。详细分析了多层介质多导体传榆线，并在矩量法处理时引入小波变换，使原稠密系数矩阵变换为稀疏矩阵。从而提高了求解速度。     

基于超平面法矢量的欠定盲混合矩阵估计

源信号稀疏性差时,基于源信号稀疏特性的欠定盲混合矩阵估计算法,通常先聚类求得混合矢量张成的超平面,然后估计混合矩阵。但此方法涉及运算量较大的超平面聚类,算法效率低。针对这一缺陷,提出了一种新的混合矩阵估计算法。先由所提出的基于梯度法的法矢量更新方法求得超平面法矢量的估计,然后求出混合矩阵。该方法不需要进行超平面聚类,大大降低了运算量,提高了混合矩阵估计效率。仿真结果证明了该方法的正确性和有效性。     

离散小波变换加速导体目标散射计算的分析

如今矩量法被广泛地应用于解决电磁场问题中,但是应用矩量法所得到的矩阵是稠密阵,如果直接求解无疑耗费大量的时间,若能将矩阵稀疏化,那么求解起来就会省时得多.针对这个问题,本文将给出离散小波变换方法稀疏化矩量矩阵,并以Daubechies三阶尺度函数为例,阐述小波的一些基本性质以及滤波系数的构造,论述小波变换原理和详细推导了变换矩阵的构造.并给出一个全新的算例--二维导电平面上的平行双槽线上的散射问题.     

小波变换在电磁场数值计算中的应用

本文从算子展开的角度将小波矩量法应用于解电场积分方程，分析了其系统矩阵的精确度、稀疏性及条件数等，并在以上几个方面同一般的分域基矩量法进行了比较。指出小波矩量法形成的系数矩阵是一个稀疏矩阵，但是它的条件数高。我们分析了系数矩阵的稀疏原理，并解释了矩阵性态不好的原因，给出了改善矩阵性态的方法。最后以一个无限长的薄导体片在ＴＭ平面波入射下的感应电流为计算对象，验证了我们的结论。     

小波矩量法分析环形微带缝隙天线*

将矩量法和小波变换理论结合起来,应用于求解电磁场积分方程,分析计算了环形微带缝隙天线磁流分布、驻波、阻抗特性和辐射方向图,通过用小波基代替一般的分域基矩量法中的权函数和基函数,使矩量法中与算子相对应的阻抗矩阵变成为大量元素为零的稀疏矩阵,减小了数值方法对存储量的要求,在达到允许精度的前提下,使计算量显著降低。文中给出计算实例,验证该方法,计算结果与用一般矩量法计算结果和实际测试结果相比,吻合较好。     

预处理结合AWE技术求解导体目标RCS

采用渐近波形估计技术(AWE)和预处理技术求解导体目标的宽带雷达散射截面(RCS)。应用矩量法求解导体目标的电场积分方程,通过构造预条件算子,使由矩量法得到的阻抗矩阵稀疏化,从而计算导体表面电流时变得简便,再结合渐近波形估计(AWE)技术计算导体目标的宽带雷达散射截面(RCS)。实例结果表明,该方法在计算电大导体目标时具有较高的计算效率和很好的精度。     

多层自适应交叉近似加速的旋转对称体矩量法

为了更有效地分析旋转对称电大物体的电磁散射问题,提出了一种针对旋转对称矩量法的多层自适应交叉近似加速方法,并分别应用于基于三角形基函数和3阶Hermite基函数的旋转对称矩量法.使用所提方法加速混合场积分方程下旋转对称体矩量法的单模式与多模式阻抗矩阵的构建过程时,计算得到的远场雷达散射截面积与传统旋转对称矩量法的结果吻合良好,且计算效率明显提高.     

线天线的小波矩阵变换法求解

本文研究天线的小波矩阵变换法求解。首先采用三角插值基函数和线天线的一种精确计算模型,利用矩量法得到矩阵方程,然后通过Daubechies离散小波变换进行快速求解。计算结果表明,该方法能够使阻抗矩阵稀疏化,从而提高了求解速度。     

高阶矢量有限元方法中的稀疏矩阵技术

系统研究了高阶矢量有限元方法中的稀疏矩阵存储、重排序和快速求解技术。针对有限元(FEM)矩阵稀疏的特点,验证了高阶矢量有限元矩阵具有随机稀疏结构的特点,并采用合适的变带宽存储技术实现了FEM矩阵的高效稀疏存储。针对有限元矩阵非零元素分布不规则的缺点,采用RCM技术对矩阵元素进行重排序,从而压缩了矩阵带宽。研究了基于稀疏矩阵技术的(直接法、迭代法)快速求解和预处理技术。数值结果验证了稀疏技术极好的计算性能。     

基于小波矩量法的平面螺旋电感的电磁辐射研究

 平面电感实现了电感器件的小型化和片式化.当工作频率达到射频或微波段时,应考虑平面电感线圈的辐射和散射对其周围电路的影响.本文采用小波矩量法研究了PCB(printed circuit board)平面螺旋电感的电磁辐射特性.采用区间小波作为矩量法中的基函数和检验函数,计算了电感中的电流分布,给出了辐射方向图.与传统矩量法相比,小波矩量法可以使系数矩阵稀疏化,从而节省了计算机资源和计算时间.     

三维寄生电容边界元计算的半解析积分方法

在VLSI三维多介质互连寄生电容的边界元法计算中,利用互连结构特点,本文提出一种半解析积分方法,它应用原函数方法将二维面积分转化为一维线积分,再用一维高斯积分求出积分值.与二维高斯积分相比,速度更快、精度更高,并改善了解的精度.     

电大导体目标电磁散射特性的投影迭代法分析

将投影迭代法应用于分析任意二维和三维电大导体目标的电磁散射特性。该方法首先剖分传统矩量法得到的矩阵方程,然后通过投影迭代逐步修正未知电流值,进而计算目标的雷达散射截面。数值计算表明：该方法与传统矩量法计算结果相吻合,计算量大大降低。     

An analytical solution to the microstrip line problem

An analytical method for determining the line capacitance of a microstrip line is presented. The solution is exact, but it is expressed by means of the solution of an infinite system of linear equations whose coefficients are the result of certain numerical quadratures. The analysis is carried out for the case of two dielectric substrates. Changes to include additional stratified layers are readily available using the transfer matrix method described by P.M. van Berg et al. (1985). Comparison of the results obtained using the proposed formula with those obtained using exact formulas (available in particular cases) shows that, in cases of practical interest, it is sufficient to consider only the first two equations in the above-mentioned infinite set of linear equations     

Analysis and design of class E amplifier with shunt capacitance composed of nonlinear and linear capacitances

The Class E amplifier requires exact shunt capacitance to achieve optimum operation. Most Class E amplifiers are usually constructed by adding an external capacitor to the output capacitance of the power transistor in order to obtain the total required shunt capacitance. The output capacitance of the power transistor is nonlinear and the external capacitance is linear. Therefore, neither design equations for linear shunt capacitance nor the design equations for nonlinear shunt capacitance can be used in most designs, especially when the two are comparable. This paper presents an analysis and a design procedure for the Class E amplifier with a shunt capacitance composed of both a transistor nonlinear output capacitance and a linear external capacitance for the duty cycle D=0.5. Because the design equations do not have analytical forms, this paper provides a table and figures, which show results of numerical analysis. The Class E amplifier can be designed using these table and figures. A design example is given to illustrate the design procedure. Simulation results of the example circuit with PSpice and experimental results are presented to verify the theoretical results.     

On the two-dimensional capacitance calculation of multiconductor multilayered interconnects

In this paper a method for analysis and modelling of transmission interconnect lines on multilayered dielectric media is presented. The analysis is based on semianalytical layered Green’s function and the electromagnetic concept of free charge density. It allows us to obtain integral equations between electric scalar potential and charge density distributions. These equations are solved by the Galerkin procedure of the Method of Moments. After this, the capacitance matrix of multiconductor interconnect lines in the presence of planar dielectric interfaces is calculated. When there exists no infinite ground plane, we enforce the constraint that the sum of all free charges is zero. The feasibility of the method has been shown by simulations of several transmission-line problems. The results have been compared with reported data obtained by free-space Green’s function method, conformai mapping formulas, generalized method of lines and inverted capacitance coefficient matrix technique. The proposed approach is not inferior to other procedures in terms of generality and memory requirements. At the same time, a reduction of the central processing unit (cpu) time is achieved because the integral equations are solved numerically only on the surface of conductor lines.     

Analytically determined quasi-static parameters of shielded or openmulticonductor microstrip lines

An exact analytical expression for the capacitance matrix of a shielded or open multiconductor microstrip structure is derived by solving the system's dual integral equations by constructing a Volterra boundary-value problem (BVP). The solution is expressed in terms of infinite matrices with very good convergence properties. This new approach uses a series of Bessel functions rather than trigonometric series to approximate the solution which results in an efficient algorithm. Simplified formulas are given for the even and odd capacitance of symmetric coupled microstrip lines and compared to the results given by the finite analytical solution available in this particular case. Numerical examples demonstrate that the method yields accurate results and is computationally effective for structures having a large number of conductors     

On a class of predefined wavelet packet bases for efficientrepresentation of electromagnetic integral equations

A general wavelet packet tree is proposed to design predefined wavelet packet (PWP) bases for the efficient representation of electrodynamic integral equations. The wavelet packet decomposition tree is constructed by zooming in along the spectral oscillatory frequency of the free-space Green's function. Numerical results show that for typical two dimensional (2-D) scatterers the number of above-threshold elements in the PWP-based moment matrix is on the order of O(N^1.3) and tends to grow at a rate of O(N·log N) for large-scale problems. Therefore, the complexity of solving the moment equations can be reduced accordingly. Furthermore, it is shown that the elements of the moment matrix based on the PWP bases can be computed directly at approximately the same complexity as the fast wavelet transform approach. Consequently, with on-the-fly thresholding of the matrix elements, the O(N²) memory bottleneck in the formation of the PWP-based moment matrix can be circumvented     

A capacitance model for GaAs MESFETs

A capacitance model for a GaAs MESFET suitable for implementation in the circuit analysis program SPICE is presented. The model consists of nonlinear capacitances that are a function of two voltages. Such a model gives rise to ordinary nonlinear capacitances and transcapacitances. The placement of these elements in the Y matrix is shown. The empirical equations for the gate charge of a GaAs MESFET given provide an accurate SPICE model for the gate charge and capacitances of a MESFET. A comparison of measured capacitance values with the modeled values gives close enough agreement for circuit simulation purposes     

多层递推小波算法及其在计算电磁学中的应用

本文给出了一种快速的多层递推小波算法,它能有效地求解由小波展开而获得的稀疏矩阵方程,这种算法利用小波展开的阻抗矩阵的多分辨率表示,将原来的稀疏矩阵方程转化为多个小型矩阵方程进行求解,从而节省求解方程的时间.在本文中,我们以求解二维散射问题为例,将这种算法用于计算电磁学中,数值结果表明该算法比通常的小波算法更快速有效.     

基于分段预留法的互连线二维电容提取技术

随着制造工艺的不断演进、电路规模的不断增大,集成电路逐渐进入后摩尔时代。如何准确快速地进行寄生电容参数提取,对于保证设计质量、减少成本和缩短设计周期变得越来越重要。文章提出了一种基于分段预留法的二维电容提取技术,该技术基于改进的有限差分法,采用非均匀网格划分和求解不对称系数矩阵方程,模拟互连结构横截面,可以高效计算出主导体的单位长度总电容以及主导体和相邻导体之间的单位长度耦和电容。为了验证提出方法的准确性和有效性,进行了一系列验证实验。实验结果表明,提出的互连线二维电容提取技术在寄生电容计算精度上平均提高了140倍,运行时间平均缩了10%。