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.     

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。     

Equivalent Circuits of Binomial Form Nonuniform Coupled Transmission Lines

Equivalent circuits of nonuniform coupled transmission lines whose self and mutual characteristic admittance distributions obey binomial form are presented. Telegrapher's equations of these nonuniform coupled transmission lines can he solved exactly rising Bessel functions of fractional order. By decomposing the chain matrix, it is shown that equivalent circuits of these nonuniform conpled transmission lines consist of cascade connections of lumped reactance elements, uncoupled uniform transmission lines and ideal transformers.     

Time-Domain Analysis of a Lossy Nonuniform Transmission Line

An analytical solution of the coupled Telegrapher's equations for the voltage and current on a homogeneous lossy transmission line is presented. The resulting expression is obtained in the form of an exact time-domain propagator operating on the line voltage and current. It is shown that an application of Simpson's rule yields a simple accurate numerical representation of the propagator that can be used to analyze both homogeneous and inhomogeneous transmission lines. Numerical dispersion in lossy media is examined proving that this method has no numerical dispersion.      

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。     

Parallel Coupled Bandstop Filter Using Double Negative Coupled Transmission Line

In this letter, a novel parallel coupled bandstop filter (BSF) using a double negative (DNG) coupled transmission line is presented. Between microstrip as a double positive (DPS) transmission line and mushroom structure as a DNG transmission line, strong coupling broadly arises in the cross range of dispersion curves of isolated microstrip and mushroom structure because of a complex propagation constant in the cross range. Strong coupling inhibits wave propagation, so that this kind of structure can be utilized as a BSF. This BSF utilizes coupled transmission line instead of coupled resonator, resulting in broad bandwidth (>30%), sharp-rejection, and high rejection level. The strong coupling between the DPS and DNG transmission line makes it possible to shorten the coupling length, resulting in compact size     

电磁场数值模拟TLM算法及其应用

传输线矩阵（TLM）算法是基于Huygens的波传播模型，与计算机结合起来后，成为一种强有力的三维时域电磁场数值仿真算法，在1971年TLM被首次提出以后，便得到不断的改进，从二维到三维，从扩展型结点到凝缩型结点，从时域TLM到频域TLM，而其应用也从最初的处理电磁场问题发展到对微波电路的模拟，高速IC的设计，以及处理光学，机械学，热学和声学问题，本文详细介绍了二维、三维空间的TLM算法，扩展型结点和几种改进的对称凝缩结点，阐述了TLM在各领域的应用，最后还简单介绍了我们完成的工作。     

Impedance Transformation and Matching for Lumped Complex Load with Nonuniform Transmission Line

New nonuniform transmission-linematching networks for a class of lumped complex loads are presented. A parabolic (or reciprocal parabolic) tapered transmission line, whose exact equivalent circuit is represented by a mixed lumped and distributed circuit, can transform the lumped series RC (or parallel RL) loads into different lumped impedances which are more convenient than the original load impedances for ordinary matching network design. Simple design procedures are described and useful design charts are given. Also, numerical examples are shown including experimental verification.     

Coupled Strip Transmission Line with Three Center Conductors

An exact analysis is made for the shielded coupled strip transmission line with three center conductors. By means of the immittance matrices presented, the electrical behavior of the coupled strip transmission line of this type may be completely described. Design formulas which enable one to evaluate the cross-section dimensions from the desired values of characteristic immittances are derived for the two kinds of the line configurations. Equivalent circuits of the two-port networks for various port conditions are also presented. In addition, an application is discussed involving the asymmetrical coupled strip transmission line with two center conductors. The appendix gives the derivation of the design formulas by means of conformal mapping techniques.     

传输线在宽带匹配中的应用

提出了一种宽带匹配网络设计的新思路。文中以任意输入阻抗的匹配为分析模型,详细分析了传输线在宽带匹配中的各种应用,并从宏观角度定性分析了传输线在阻抗匹配中的应用原理。在此基础上分析设计了一副工作在30～88 MHz频段、电压驻波比小于3．0的实用单极子天线,其实测结果良好地满足了要求。     

Miniature Strip Transmission Line for Microwave Applications

The construction of a strip line whose physical size is kept as small as possible consistent with reasonable electrical performance is presented. This line is fabricated by relatively simple techniques and can be shaped to fit line components into relatively confined spaces. The line has good power handling capacity and moderately low attenuation. Various components have been developed in this line including a broadband 3/8" coaxial line to strip line adapter, a broadband matched load, attenuators, and high and low pass filters.     

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.     

Left-Handed Transmission Line Based on Resonant-Slot Coupled Cavity Chain

In this letter, a novel realization of left-handed transmission line is presented; the proposed structure is based on identical symmetrical resonant-slot coupled cavity chain. The dispersion characteristic of the resonant-slot coupled cavity chain is analyzed by means of field theory and finite element method (FEM) eigenmode simulation, and a left-handed passband is proved to exist. A backward wave behavior is demonstrated unambiguously from FEM driven modal simulation. The phase front is observed to be in the opposite direction with respect to the energy one for a finite nine-unit cell prototype     

输电线路覆冰特征及其防治对策

输电线路覆冰是一种严重的自然灾害,可引发输电线路导线舞动、绝缘子闪络等事故,严重危害电力系统的安全运行。文中总结分析了输电线路覆冰的种类、性质及其影响因素,详细说明了由覆冰引起的绝缘子闪络和线路舞动的定义及防治方法,列举了现有的线路覆冰防治对策,为研究覆冰对输电线路的危害作了较全面的分析,有利于设计抵御冰灾的输电线路,提高了输电线路抵御自然灾害的能力。     

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。     

SDH广电传输网及其应用

SDH全称为同步数字传输体制(协议),这种传输体制规范了数字信号的帧结构、复用方式、传输速率等级、接口码型等特性。它与光纤技术或微波技术结合起来形成的同步数字传输网融复接、线路传输及交换功能于一体,有完善的网络管理功能,能有效     

耦合传输线信道传输矩阵建模及串扰抵消效果分析

针对高速互连系统中传输线上的串扰问题,基于电磁耦合理论,研究了耦合传输线信道传输矩阵的性质,建立了以下两种情况的耦合传输线信道传输矩阵模型及其矩阵分解形式,分别是：（1）考虑受扰线两边各一条相邻微带线对受扰线的串扰;（2）考虑受扰线两边各两条相邻微带线对受扰线的串扰.给出了上述两种情况下基于耦合传输线信道传输矩阵分解形式的串扰抵消方案,并利用仿真工具ADS对其进行了验证.结果表明：信号抖动和失真大幅下降,串扰抵消效果良好,并且第二种情况下的串扰抵消效果优于第一种情况.该结果说明了在基于耦合传输线信道传输矩阵进行串扰抵消时,考虑两边各两条相邻微带线的串扰效果较好,对保持高速信号完整性具有一定的实际应用价值.     

Tapped-Line Coupled Transmission Lines with Applications to Interdigital and Combline Filters

Exact, general, open-wire-line equivalent circuits for tapped-line combline and interdigital arrays are derived using a combination of graph transformations and induction. A significant feature of the equivalent circuits is that they do not require commensurate length sections. The equivalent circuit for tapped-line interdigital arrays is utilzed to develop design equations for tapped-line interdigital filters.