Closed-form Analysis of Lossy Cosine-Squared Tapered Nonuniform Transmission Lines

The rigorous analytical solutions and the ABCD matrix of the lossy Cosine-Squared tapered nonuniform transmission lines (CSTNTL) are presented in this paper. According to different boundary conditions, the unique solution is obtained mathematically. Through the numerical calculations based on analytical solutions, the distributed voltages and currents in different terminated cases are shown to explain the transmission characteristics of CSTNTL. Especially in the lossy case the distributed power values are simulated to show the attenuation phenomenon.     

Equivalent Representations of Lossy Nonuniform Transmission Lines

Equivalent transformations, which were recently derived for mixed lumped and distributed circuits, may be extended to circuits consisting of lumped reactance, resistors, and Iossy transmission lines. It is shown that circuits consisting of a cascade connection of lumped element sections and Iossy uniform transmission lines are equivalent to circuits consisting of a cascade connection of lossy nonuniform transmission lines, lumped elements, and ideal transformers. Furthermore, by considering the limiting case of these transformations, equivalent transformations for circuits consisting of a cascade connection of lumped reactance, resistors, and nonuniform transmission lines are obtained. Exact equivalent circuits of Iossy even-order binomial form transmission lines are derived from these equivalent transformations.     

非均匀传输线间的串扰研究

应用时域有限差分法对非均匀传输线间的串扰耦合进行分析。基于细线散射的时域有限差分法分析非均匀结构时,采用阶梯式均匀传输线模型,对非均匀传输线进行分段逼近。针对不等长、线径变化、非平行线和交叉线4种情况分析其参数变化对串扰的影响。研究表明：不等长电缆超出部分长度对串扰耦合幅度影响较小,对谐振频率影响较大;电缆线径的变化对其串扰耦合影响较小;非平行线和交叉线的角度对电缆间串扰的影响较大。     

Lossy Transmission Line Filters

Reactive bandpass and low-pass filters often exhibit spurious responses in the frequency region above the design passband. The spurious responses limit the effectiveness of the filter in preventing interference by out-of-band signals. A simple and inexpensive technique for reducing or eliminating these passbands is to add short sections of an appropriate lossy transmission line in series with the conventional filter. A significant size reduction of conventional transmission line reactive filters can also be realized along with the reduction or elimination of spurious passbands by combining a lossy dielectric with the conventional reactive elements. This paper discusses the application of lossy line filters in cascade with and integrated into conventional reactive filters. The design of lossy transmission line sections and wide-band impedance matching techniques are described.     

非均匀有耗传输线ABCD参量的求解

传输线理论是射频与微波电路的重要基础理论,而其中ABCD参量特别适用于分析级联网络的传输性能.本文针对非均匀有耗传输线的ABCD参量求解问题,建立传输线的数学模型,给出了三种解法,即级联法、微分方程法和积分方程法,并对三种方法的准确性和效率进行了讨论.     

A Precise Time-Step Integration Method for Transient Analysis of Lossy Nonuniform Transmission Lines

This paper presents a novel time-domain integration method for transient analysis of nonuniform multiconductor transmission lines (MTLs). It can solve the time response of various kinds of transmission lines with arbitrary coupling status. The spatial discretization in this method is the same as the finite-difference time-domain (FDTD) algorithm. However, in order to eliminate the Courant-Friedrich-Levy condition constraint, a precise time-step integration method is utilized in time-domain calculation. It gives an analytical solution in the time domain for the spatial discretized Telegrapher's equations with linear boundary conditions. Large time steps can be adopted in the integration process to achieve accurate results efficiently. In the analysis of transmission lines with frequency-dependent parameters, a passive equivalent model is introduced, which leads to the similar semidiscrete model as that for the frequency-independent case. In addition, a rigorous proof of the passivity of the model is provided. Numerical examples are presented to demonstrate the accuracy and stability of the proposed method.     

有耗传输线的阻抗圆图

本文针对有耗传输线的特点，，分析了有耗传输线的阻抗圆图，并讨论了利用该圆图计算有耗线阻抗的方法。     

Analysis of Time Response of Lossy Multiconductor Transmission Line Networks

Systems are considered consisting of an arbitrary number of multiconductor transmission lines joined and terminated by arbitrary linear networks. The fines are assumed to be Iossy, with frequency-dependent parameters. The system is analyzed in the frequency domain, and the inverse Fourier transform is used to obtain the time-domain response.     

用波形迭代法分析非均匀多导体传输线的时域响应

本文从频域电报方程出发推出了一个描述传输线ABCD矩阵的微分方程,将传输线时域响应分析从微分方程的边值问题转化为数学上更易求解的初值问题。然后利用波形迭代法数值求解非均匀传输线的ABCD矩阵,证明了一个关于迭代收敛性的定理,并据此采取了旨在加快收敛速度的将传输线分割成许多相互级联的子网络的步骤。传输线的ABCD矩阵求得后,便可借用付里叶变换和卷积技术对具有线性、非线性负载的传输线时域响应进行分析。给出的应用实例表明,诙分析方法是有效而可靠的。     

有耗传输线的TLM模型法

本文从传输线理论出发,介绍了一种解决传输线问题的新方法－－TLM法。     

Analysis of Hermite Lossy Nonuniform Transmission Lines Based on Hermite Function and Confluent Hypergeometric Function

The rigorous analytical solutions of the lossy Hermite nonuniform transmission lines (HNTL) are presented in this paper. These solutions are based on two special functions, namely, Hermite function and confluent hypergeometric function. The ABCD matrix of HNTL is given to obtain the corresponding frequency characteristic of the HNTL transformer. Through numerical simulations in different terminated cases, it is found that the lossless HNTL can be matched by resistance loads. This conclusion is different from the lossless one presented by D.torrungrueng. etc. In addition, the distributed power values of HNTL in the lossy case are calculated to show the attenuation character.     

Coupled Nonuniform Transmission Line and Its Applications

Theory and applications of coupled nonuniform transmission lines are described. Matrix representations of a general coupled nonuniform transmission line are presented, by means of which the behavior of any coupled nonuniform transmission line maybe completely described. Among a wide variety of applications of coupled nonuniform transmission lines, two typical networks, one the coupled nonuniform transmission-line folded all-pass network and the other the coupled nonuniform transmission-line directional coupler, are treated in detail. Equivalent circuit representatious of these two networks are presented, which enable the designer to synthesize them in a greatly simplified manner by making use of the theories now available for more conventional single nonuniform transmission lines. In addition, the properties of these two networks using coupled exponential line are investigated. Design procedure is also given for asymmetrical coupled exponential-line directional couplers having excellent characteristics.     

Linear Analysis of Traveling Wave Tubes with Nonuniform Lossy Interaction Structures

A linear theory model is developed to analyze traveling wave tubes (TWT) employing distributed wall loss. The loss can be a function of position. The electronic and circuit equation are derived, taking into account the spatial variation of the circuit loss. This model can be used to provide a first-cut design of the TWT.     

非均匀传输线的仿真模型建立方法研究

利用分段线性和等效电路模型,结合Hspice电路仿真软件,提出了一种建立非均匀传输线仿真模型的方法,给出了非均匀传输线的Hspice等效电路模型。通过一个有代表性的算例,利用文中提出的仿真模型建立方法,得出了时域范围内的Hspice仿真结果。最后通过与已有的方法结果比较表明：该方法有较高的计算精度,且计算速度快,占用计算机资源少。     

二维有耗介质体电磁反演的时域玻恩迭代方法

本文利用时域非线性优化方法求解二维有耗介质的体的逆散射问题获得了很好的结果。并对正散射的求解精度做了改进。     

基于非均匀传输微带线设计Wilkinson功分器

在微带线基本理论的基础上,采用非均匀传输微带线研究设计了新型Wilkinson功分器有。运用阻抗匹配、奇偶模分析的方法,对基于非均匀传输微带线的Wilkinson功分器进行理论分析,并通过ADS2008(Advanced Design System 2008)软件的设计、仿真和优化得到了相关数据参数,设计制作了一款3.1~10.6 GHz范围内的非均匀传输微带线Wilkinson功分器,从而成功地实现了小型化、低功耗Wilkinson功分器。     

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 Simulation of Power Combining in a Chain of THz Gunn Diodes in a Transmission Line

Solid-state THz devices usually suffer from low power output. This, however, can be overcome by efficient power combining. In this paper, the power combining of a chain of active devices (longitudinal array of N Gunn diodes) in a semi-infinite transmission line has been simulated. Superlinear growth of power P is found in a line with inductive-capacitive elements: P is quadratic in N when P is small and becomes linear when P is large. Intricate auto-modulation due to coupling between the devices is shown to accompany power combining.