基于精细积分法的耦合传输线瞬态分析

在耦合传输线的瞬态分析中提出了一种基于精细积分法的龙格-库塔迭代法。这是一种时域内的数值解法，该方法在对电报方程进行空间离散而获得对时间的一阶微分方程之后，没有采用精细计算法，而是采用了龙格-库塔迭代法。避免了大量的矩阵运算，提高了传输线瞬态响应分析的效率。     

Asymmetric Coupled Transmission Lines in an Inhomogeneous Medium

Terminal characteristic parameters for a uniform coupled-line four-port for the general case of an asymmetric, inhomogeneous system are derived in this paper. The parameters (impedance, admittance, etc.) are derived in terms of two independent modes that propagate in two uniformly coupled propagating systems. The four-port parameters derived are of the same form as those obtained for the symmetric case resulting in similar port equivalent circuits for various circuit configurations considered by Zysman and Johnson. The results obtained should be quite useful in designing asymmetric coupled-line circuits in an inhomogeneous medium for various known applications.     

Coupled Transmission Line Networks in an Inhomogeneous Dielectric Medium

In this paper, two-port networks composed of two identical, coupled transmission lines embedded in an inhomogeneous dielectric (e.g., suspended substrate, microstrip) are investigated. The ABCD parameters of circuit configurations, considered by Jones and Bolljahn, are obtained for the case of inhomogeneous dielectilc. Equivalent circuits of these networks are also given. It is shown that the characteristics of such circuits differ markedly from those embedded in a homogeneous medium. In addition, experimental results are presented for three types of circuits which have been constructed and tested. There is excellent agreement between the experimental results and those predicted theoretically on the basis of the equivalent circuits.     

Coupled Transmission Lines

An analysis of coupling between a stripline and a rectangular waveguide is presented. Coupling is through small apertures in the form of a circular hole or a narrow rectangular slot. A closed form expression for the normalized field distribution in the stripline, required for the purpose of analysis, is also derived. The theoretical results show good agreement with the experimental results.     

Coupled-Mode Analysis of Nonuniform Coupled Transmission Lines

The transmission-line equations describing propagation along coupled transmission lines are cast in coupled-mode form so that the roles of the different coupling coefficients and the impedance variation are more directly observable. Restrictions on the various parameters for obtaining directional coupling with nonuniform lines are then discussed and exact solutions for the coupling response of two nonuniform coupled lines with particular variations of the coupling coefficients are presented. The results obtained from the exact closed-form solutions should aid in the design of tapered couplers.     

Time-Domain Perturbational Analysis of Nonuniformly Coupled Transmission Lines

A method of analyzing the time-domain behavior of a pair of nonuniformly coupled, dispersionless transmission lines is presented. The coupling coefficient of the system is assumed to be slowly varying with position. The set of coupled equations is transformed into a form for which the method of characteristics applies. Instead of numerically integrating the coupled equations, we decouple the equations by writing the solution in the form of a perturbational series. The resulting zeroth-order term corresponds to the inverse transform of the WKB approximation in the frequency domain, which contains only the wavefront and amplitude information. The higher order terms can be directly interpreted as reflections along the lines. Causality is satisfied to all orders. This method has the advantage of easier implementation, and is more versatile than frequency-domain methods as well as the brute-force numerical integration of the coupled partial differential equations.     

无损均匀传输线的PSpice仿真分析

在正弦稳态情况下,无损均匀传输线终端开路、短路或接纯电抗时,传输线上会出现驻波.无损线的特性阻抗是纯电阻,所以负载匹配时沿线任一点的电压和电流同相位.PSpice中的无损线模型与有损线模型有很大区别,无损线的长度用归一化长度表示.应用PSpice可以对无损线进行时域仿真和频域仿真,时域仿真可以获得线上任一点的电压、电流、瞬时功率随时间变化的曲线,频域仿真可以获得线上任一点的频率特性.     

Transient Analysis of Systems with Exponential Transmission Lines

Two computer solutions are given for pulse propagation along exponentially tapered transmission lines with arbitrary nonlinear sending and receiving networks. The solutions allow series and shunt loss terms per unit of length of the line. The method of characteristics is shown to be computationally superior to the cubic spline method in terms of accuracy and efficiency.     

Transient Analysis of Single and Coupled Lines with Capacitively-Loaded Junctions

Transient processes are studied for a single line or a pair of coupled lines consisting of line sections with different characteristic admittances and with capacitances loaded at the junctions of line sections. Equations for the Laplace transform of the reflection and transmission coefficients of single and coupled lines are derived for the general case. When the capacitances are loaded at regular intervals, the corresponding expressions of the transient response waveforms at different terminal ports of these lines for both a step and a ramp input are developed. Based on the theoretical analysis, we illustrate the transient responses to ramp signals on some simplified computer signal lines, such as parallel-plate lines with transverse ridges, and parallel striplines with perpendicular crossing strips sandwiched between common upper and lower ground planes. The numerical results suggest that signals with a rise time of t/sub r/<50 ps will cause too much distortion, and should not be used when the length of the line is longer than 2 cm.     

Transient Analysis of Partially Coupled Lines (Short Paper)

We propose a time-domain analysis method for partially coupled Iines by dividing them into "tubes." A tube of order N is a set of N coupled lines of equal lengths for which transient analysis based on modal decomposition is well known. An interface problem occurs at the junction of tubes of different orders. Such a case is analyzed by introducing two operators, called dilatation and shrinkage.     

非零初始状态传输线瞬态分析

本文结合付里叶变换和拉氏变换技术，得出了具有任意非零初始电压、电流分布的多导体传输线的等效时域线性网络模型，传输线可以为有耗丰均匀性，该模型可与常用电路分析软件接口，因而可处理非线性终端负载，给出了一个应用本文模型进行瞬态分析的例子。     

无损线终端接任意负载暂态响应分析

本文基于均匀线方程,利用拉普拉斯变换,研究了阶跃激励在终端和起端都不匹配的无损均匀线上多次反射传输情形,借助负载中储能元件响应产生过程的"附加电源",推导出终端为任意负载时求解暂态响应的一般方法,最后通过RC电路和RLC电路分析及仿真实验加以验证了该求解方法的正确性.     

Artificial Dielectric Shields forIntegrated Transmission Lines

We present a novel shielding method for on-chip transmission lines built on conductive silicon substrates. The shield consists of an artificial dielectric with a very high in-plane dielectric constant, built from two patterned metal layers isolated by a very thin dielectric film. Inserted below an integrated coplanar transmission line, the artificial dielectric layer blocks the electric field of the line from entering the silicon substrate. Shielded coplanar waveguides fabricated on a conventional silicon wafer show a two- to three-fold loss reduction compared to unshielded lines at frequencies below 30 GHz.     

Comments on "Asymmetric Coupled Transmission Lines in an Inhomogeneous Medium" (Letters)

In the above paper, the terminal characteristic parameters for a uniform coupled-line four-port for the general case of an asymmetric, inhomogeneous system are derived, and some of the equivalent circuits are presented.     

用基于Chebyshev展开的NILT进行传输线的瞬态分析

本文提出了用基于Ｃｈｅｂｙｓｈｅｖ多项式展开的ＮＩＬＴ（数值拉普拉斯反变换）进行传输线瞬诚分析 方法。文中介绍了方法的基本原理,分析了实际应用中误差产生的原因,并给出相应的措施：通过引入Ｌａｎｃｚｏｓ因子对通近结果的平滑,与ＮＩＬＴ的重新启动,最后用实例说明了方法的应用。结果表明这种方法较目前传输线分析中通用的ＮＩＬＴ方法及卷积法都有更快的速度。     

传输线瞬态响应的一种时域分析方法

提出一种传输线瞬态响应的时域分析方法。该方法对电报方程在时域内差分离散,在建立对空间的一阶微分方程组后,采用精细积分法,可获得传输线瞬态响应。这是一种时域内的半解析数值计算方法,具有方法简单、计算精度高等优点,能够有效地分析具有非线性负载的有损耦合传输线瞬态响应问题,也可以用于输电线路的瞬态分析及故障测距。     

Time-Domain Simulation of n Coupled Transmission Lines

In this paper, a general SPICE model for n coupled transmission lines is presented. The model consists of two identical transformation networks and n single-transmission-line models. The transformation networks are realized with linear time-invariant voltage-controlled voltage sources (VCVS's) and current-controlled current sources (CCCS's) only. A simplified model designed to simulate connections on multilayer printed circuit boards is also presented. In this case, the coupling model is adequately described by a capacitance matrix C and an inductance matrix L that are Toeplitz, symmetric, and tridiagonal. The particular structure of C and L makes the computation of the parameters of the transformation network extremely easy and efficient because only simple function evaluations (cosines) are required. Furthermore, the transformation network depends only on the number of coupled lines and not on the parameters of those lines. Therefore, a library of such models needs to be determined only once, and only the characteristic impedances and time delays for the single lines have to be recomputed. The simulation results have been compared against expermental results, and the difference between the two is less than 1 percent.     

Radiation from Bends in Dielectric Rod Transmission Lines

The radiation from the fundamental mode propagating around curved dielectric rod transmission lines is investigated experimentally with microwave frequencies. Three methods are used to determine the attenuation by radiation: measuring the insertion loss of bends, measuring the Q-factor of ring resonators, and measuring the Q-factor of sections of curved dielectric rod transmission lines terminated by large reflecting plates. The attenuation is found to depend mainly on the combination R lambda/sub 0//sup 2/ / r/sub 0//sup 3/ where R is the radius of curvature, lambda/sub 0/ the free space wavelength and r/sub 0/ a measure of the transverse field extent of the HE/sub 11/ mode. The experimental results are compared with theoretical predictions of other authors. The measured values of the attenuation constant are found to be smaller than the theoretical values. The distribution of the electromagnetic field near bends is recorded using a semiautomatic field plotter. From the field pictures, it can be concluded that the curved dielectric waveguide radiates tangentially from the outer side. The results presented will also be useful for understanding the mechanism of radiation from bent optical waveguides.     

Nonreciprocity in Dielectric Loaded TEM Mode Transmission Lines

An analysis is presented of partially dielectric loaded strip transmission line from the point of view of ferrite applications. It is shown that the microwave magnetic field is elliptically polarized both at the dielectric surface and within the dielectric. The degree of elliptical polarization is expressed analytically as a function of the dielectric constant, the degree of dielectric loading, and the frequency. For specific values of dielectric constant and loading, a high degree of circularity may be made to exist at the dielectric surface over extremely broad frequency bands. Experimental data are presented which are in accord with the theoretical predictions.