传输线参数提取和瞬态响应分析

利用传输线的基本原理推导出半无限长传输线的瞬态响应,总结出传输线在高频下的基本特性,接着对双线传输线这一特定情况提取传输线的分布参数,然后应用提取结果进行传输线Hspice仿真,进而得出传输线的时域特性。     

基于广义传输线方程的平行双导线电磁耦合分析

近地传输线系统的电磁耦合特性分析一直是通信电力系统电磁兼容分析中比较重要的一部分内容。主要对 双线传输线系统进行BLT 建模分析,在此模型中分析高度、半径参数对传输线上电流的影响,并且分析了传输线系 统在不同入射情况下的电流结果。计算结果物理意义明确,可供EMC 设计时参考。     

基于FDTD的不等长有损耗传输线的瞬态分析

本文在考虑传输线损耗的情况下,对时域有限差分(FDTD)法应用于不等长有损耗传输线的情况进行了研究。首先,在考虑传输线损耗的情况下给出了传输线上各点电压和电流的迭代计算公式;其次,利用该公式对不等长有损耗传输线模型进行数值计算和理论分析;最后,通过仿真实验,其结果表明了所提计算方法是正确和有效的。该方法对不等长有损耗传输线的研究提供了理论计算参考。     

求解传输线方程定解的一般边界条件

求解传输线上电压/电流分布是分析其工作状态的基础,“微波技术与天线”教材给出了三种边界条件（源端条件、终端条件、电源和阻抗条件）来求解传输线方程通解中的待定系数,从而确定传输线上电压/电流分布。给出传输线方程定解的一般边界条件,即假定已知传输线上任意某点的电压/电流,则可以确定传输线上的电压/电流分布,并将教材中的三种边界条件归纳为一般边界条件的特例。     

多导体传输线的邻近效应和分布参数研究

随着多导体传输线内各导体之间间距的减小, 导体之间的近邻效应对传输线的分布参数和传输特性的影响越来越大.为此, 我们针对三种典型的传输线结构, 分别建立了基于矢势有限元方法分析的多导体传输线的模型, 并分析了近邻效应对磁通密度和分布电感的影响.利用提出的方法计算了同轴传输线的单位长度分布电感, 并将它与采用解析方法得到的结果进行比较来证明该方法的正确性.计算双线传输线在不同间距时的单位长度电感, 与理论分析得到的结果相比较验证了导线间距越小, 近邻效应对单位长度电感的影响越大.最后, 计算考虑了近邻效应的耦合微带线的电感矩阵, 并将它与其他不考虑近邻效应的方法得到的结果相比较, 说明近邻效应对传输线电感矩阵的影响.     

不等长非均匀有损耗传输线FDTD瞬态分析

以分析等长均匀无损耗多导体传输线的时域有限差分(FDTD)法为基础,在考虑传输线损耗的情况下,对不等长非均匀多导体传输线进行分析。首先,在考虑传输线损耗的情况下给出传输线上各点电压和电流的迭代计算公式;其次,利用该公式对不等长非均匀有损耗传输线模型进行数值计算和理论分析;最后,通过仿真实验,其结果表明所提计算方法是正确和有效的。该方法对不等长非均匀有损耗传输线的研究提供理论计算参考。     

基于FFT的传输线串扰时域响应分析与实验研究

基于传输线分布参数结点导纳方程和快速傅立叶反变换方法,仿真分析了传输线串扰电压响应及传输线参数和端接阻抗对串扰电压峰值的影响.发现在不考虑传输线终端负载电阻的电感影响时,仿真结果中振荡不明显,在考虑电感时仿真结果振荡较明显.基于实验室研究设备,对共地平行传输线间的串扰电压和电流进行了实验研究,并将部分实验结果与理论仿真结果进行了比较.结果显示:在考虑传输线终端负载电感时的仿真波形与幅度和测量结果的波形与幅度基本一致,仿真的脉冲宽度要大于测量脉冲宽度,仿真结果峰值略大于测量峰值.     

动车组内电磁场对线缆耦合及抑制措施分析

分析动车组在运行的时候产生的空间电磁干扰源,采用Agrawal传输线理论对场线耦合进行分析计算;分析干扰源参数变化对传输线终端负载电流的影响;通过计算数据分析线缆的抗干扰措施,为车辆布线电磁兼容性设计提供参考。     

传输线参数测试方法研究

传统的传输线参数测试方法是终端开路、短路测试。对于高压输电线路,终端直接短路时,短路电流较大,对电力设备有损害。本文提出了在线路正常运行时利用全球定位系统（GPS）提供的时间为基准,对传输线两端的电压、电流进行同步采样和测量。根据牛顿—拉夫逊法对传输线方程进行迭代计算可以得到传输线参数。通过Matlab仿真计算验证了该方法是有效的。     

传输线端接复杂电路的电磁耦合时域分析方法

该文基于时域有限差分(FDTD)方法和传输线方程,结合Ngspice软件,提出一种高效的时域混合算法,能够快速模拟空间电磁场作用传输线端接复杂电路的电磁耦合问题。该算法的优势在于实现了空间电磁场辐射与端接复杂电路瞬态响应的协同计算,且避免了对传输线和复杂电路结构的直接建模。首先,将复杂电路通过传输线的特性阻抗进行等效,采用FDTD方法结合传输线方程,求解得到特性阻抗上的入射电流响应。然后,在每个时间步上,将该电流引入复杂电路作为激励源,联合电路模型建立网表文件。最后,使用Ngspice软件读取网表文件,并仿真得到电路各元件上的瞬态响应。通过相应计算实例的数值模拟,与电磁场仿真软件CST的计算结果以及耗用内存和时间进行对比,验证了算法的正确性和高效性。     

Characteristics of Bifilar Helix Circuit

The characteristics of two kinds of bifilar helix circuit are discussed in this paper. One is alike wound bifilar helix and another is contrawound bifilar helix. Alike wound bifilar helix is often used in O-type backward wave tube (BWO). Owing to wider operating bandwidth, higher interaction impedance and large dimensions, the contrawound helix is suitable for broadband millimeter wave traveling wave tube (MMW TWT).     

Implementation of first-order and second-order microwave differentiators

Simple and accurate formulations are employed to represent discrete-time infinite impulse response processes of both first- and second-order differentiators in the Z-domain. These formulations, in conjunction with the representations of transmission-line elements in the Z-domain, lead to transmission-line configurations that are eligible for wide-band microwave differentiators. Both the first- and second-order differentiators in microstrip circuits are implemented to verify this method. The experimental results are in good agreement with simulation values.     

A Frequency Transformation for Commensurate Transmission-Line Networks

The frequency transformation W=1/S, where S= tanh(/spl gamma/L), is investigated for commensurate transmission-line networks consisting of stubs, resistors, ideal transformers, and unit elements. This transformation takes transmission-line transformers into transmission-line lowpass filters and vice versa, Iowpass (or bandstop) filters into highpass (or band-pass) filters and vice versa, and elliptic-function bandstop filters into elliptic-function bandpass filters and vice versa. The practicality of the transformation lies in the fact that element values of the transformed network are easily related to the corresponding element values of the original network. The transformation is useful because it provides an alternative viewpoint for synthesis, and because it reduces the number of tables of designs needed for various filter types. Several examples of designs using the transformation are given. One design is an unusual narrowband 3-dB directional coupler.     

双线背射螺旋作馈源的新式背射天线

本文提出一种用双线背射螺旋作馈源的新式背射天线。这种天线具有结构简单，馈电方便，增益较高，易于产生圆极化波等优点。     

Gain-Bandwidth Limitations and Synthesis of Single-Stub Bandpass Transmission-Line Structures

Gain-bandwidth limitations and synthesis of a class of bandpass transmission-line structures with a single shunted stub and n cascaded commensurate lines are presented in this paper. With a shunt shorted stub as the reactive constraint, the optimum gain bandwidth is derived for an ideal bandpass gain characteristic. Explicit gain-bandwidth and synthesis results have been obtained for the class of single-stub cascaded line structures with one and two cascaded lines for both maximally flat and Chebyshev characteristics. For the general case of n cascaded lines approximate gain-bandwidth limitations have also been derived. The explicit results including gain-bandwidth limitations and element values can be used for the design of this class of bandpass transmission-line networks for broad-band matching of the reactive constraint as well as impedance transformation.     

On the Attenuation of Monofilar and Bifilar Modes in Mine Tunnels (Short Papers)

The modal equations for both the monofilar and bifilar modes of a two open wire transmission line located in a waveguide model of a rectangular mine tunnel are derived by extending an earlier general analysis. Attenuation curves of both modes in the frequency range 200 kHz-200 MHz are presented for two distinct configurations of the transmission line that may be used in practice. It is demonstrated that the proximity of the Iossy tunnel wall tends to increase greatly the attenuation rate for the monofilar modes but has relatively little effect on the bifilar modes.     

Time-constant control of microwave integrators using transmission lines

A model describing the time constant of a transmission-line integrator is presented. By representing the formulations of integrators in the discrete-time (or Z) domain, we implement the integrators with equal-length transmission lines. Three integrators with different time constants and frequency bands are built and tested. The experimental results are in good agreement with theoretical values.     

隧道中低频导行电磁波的传播特性

在低频段上，导行电磁波的衰减率很小，随频率的升高而缓慢增加，不论单线波模还是双线波模其近壁效应都很小。用数值分析方法术解了单线波模方程和双线波模方程，得出的主要结论为它们的衰减率与隧道壁电导率和隧道半径有撤弱依赖关系。理论分析含单导体的任意横截面隧道可知低频段上导行电磁波的衰减率与隧道横截面积大小有微弱依赖关系，而与横截面形状无关。     

Short-Step-Stub Chebyshev Transformers Impedance

A transfer function for short-step impedance transforming filters consisting of short cascaded TEM transmission-line sections and at least one commensurate length open-circuit stub is described. Element values are given for a particular family of octave-bandwidth short-step transformers that are much more compact than existing short-step transformers.     

A high quality factor and low power loss micromachined RF bifilar transformer for UWB RFIC applications

In this letter, the authors demonstrate that high quality factor and low power loss transformers can be obtained by using the CMOS process-compatible backside inductively coupled plasma (ICP) deep-trench technology to selectively remove the silicon underneath the transformers. A 62.4% (from 8.99 to 14.6) and a 205.8% (from 8.6 to 26.3) increase in the Q-factor, a 10.3% (from 0.697 to 0.769) and a 30.2% (from 0.652 to 0.849) increase in the maximum available power gain (G/sub Amax/), and a 0.43- (from 1.57 to 1.14 dB) and a 1.15-dB (from 1.86 to 0.71 dB) reduction in the minimum noise figure (NF/sub min/) were achieved at 5.2 and 10 GHz, respectively, for a bifilar transformer with overall dimension of 240/spl times/240 /spl mu/m/sup 2/ after the backside ICP etching. The values of G/sub Amax/ of 0.769 and 0.849 are both state-of-the-art results among all reported on-chip bifilar transformers. These results indicate that the backside ICP deep-trench technology is very promising for high-performance radio frequency integrated circuit applications.