Approximation of a nonuniform transmission line by a cascade of uniform lines

It is shown that an arbitrary nonuniform transmission line may be approximated by a cascade of commensurate uniform lines. In general, a small number of lines is sufficient to obtain a good approximation, and hence the method should prove useful, both in the analysis of arbitrarily tapered lines and in the study of their properties.     

Capacitance of nonuniform coaxial transmission lines

The physical realisation of a nonuniform transmission line. possessing some desirable characteristic impedance profile, is usually achieved using calculations which do not take into account the expanding or contracting nature of the line and the associated distortions of the electromagnetic fields. A method has been devised which gives an improved realisation of such lines in a coaxial configuration. Corrections for the conductor slopes and effective lengths are made and a design example is used to illustrate these effects.     

Analysis of transients in nonuniform and uniform multiconductortransmission lines

The author presents an effective method for computation of the transient response of multiple nonuniform transmission lines. This time-domain analysis technique can predict reflections and crosstalk. The proposed spectral technique is used to transform partial differential equations describing a system of transmission lines into a set of linear ordinary differential equations, which can be solved with one of the many well-developed integration techniques. Numerical experiments performed with the prototype program showed that the method can solve specific problems (lossless, uniform lines) just as fast as less general methods based on modal analysis exploiting the particular properties of lines     

Wide-band equal-ripple filters in nonuniform transmission lines

In this paper, a novel method to realize equal-ripple filters over microwave frequencies is presented. All networks are implemented by using cascade serial and shunt transmission-line sections having the same electrical length. The transfer functions of such networks are formulated in the Z domain. In particular, it can be shown that some shunt components are able to contribute zeros locating on the unit circle if the components are open circuited. Due to the feature of transfer-function zeros locating on the unit circle, we may use an optimization procedure to implement equal-ripple filters. Both low-pass and bandpass filters are realized in the form of microstrip lines and their frequency responses are measured to validate this novel method     

Synthesis of nonuniform transmission lines with terminaldiscontinuities

An integral equation was previously derived by the authors (ibid., vol.AP-34, p.546-53, Apr. 1986) for the inverse problem associated with finite-length nonuniform lines having known impedance discontinuities at the input and output. A procedure for determining the characteristic impedance profile of the line from the solution of the integral equation was also presented. Here, the numerical aspects of this inverse problem are treated. This equation is solved using general expansions of both the kernel and unknown functions, thereby reducing the integral equation to a system of linear algebraic equations. This makes possible a numerical implementation of the theory by which the impedance profile of a nonuniform line may be reconstructed from given spectral data. The realizability aspects of the problem are treated and several examples of computer-assisted profile inversion are presented     

Reconstruction of nonuniform transmission lines from time-domainreflectometry

A novel technique is developed to reconstruct the physical structures of a nonuniform transmission line from its time-domain or frequency-domain reflection (scattering) coefficient. This technique takes the past history of reflection processes of nonuniform line into considerations, and its accuracy exceeds that of a conventional time-domain reflectometry (TDR) technique. Experimental results are presented to illustrate the validity of this reconstruction technique     

不均匀多导体传输线的瞬态分析

针对越来越严重的信号畸变和线间耦合问题,应用时域有限差分法（Finite Difference Time Domain,FDTD）建立了不均匀多导体传输线的仿真模型,并通过MATLAB编程对不均匀多导体传输线两端的电压响应进行了仿真分析.在此基础上,理论说明了各端口瞬态响应的波形特点.结果表明了时域有限差分法用于分析多导体传输系统电磁兼容问题的正确性和有效性,为电磁干扰的预测提供了有价值的参考信息.     

Generalised theory of uniform transmission lines

The conventional circuit theory of uniform two-conductor transmission lines (TEM mode) assumes that at any cross-section the current in one conductor is equal and opposite to that in the other. This is not necessarily true, and even when it is true the resulting theory does not permit solution of some simple problems such as evaluation of the voltage difference between two points on the same conductor. The author presents a more general circuit theory which does permit solution of such problems and does not demand current balance. He shows that when there is current imbalance the expressions for voltage contain a term which depends linearly upon line length, as well as the familiar hyperbolic function terms     

The K-pulse and response waveforms for nonuniform transmission lines

Application of the K-pulse concept to a class of distributed-parameter systems which can be modeled by finite lengths of nonuniform transmission lies is demonstrated. The K-pulse of such a system is the excitation (input) waveform of finite duration which yields response waveforms of Finite duration at all points of the system. Numerical techniques using a finite element method are developed to derive accurate approximation of the K-pulse and response waveforms for uniform and nonuniform transmission lines. Comparison is made with exact results to illustrate the accuracy and utility of the method.     

Arbitrary pulse shape synthesis via nonuniform transmission lines

A discrete inverse scattering technique is used to define the impedance profile for a nonuniform transmission line which reflects an arbitrary waveform. Initially charged nonuniform lines, switched out into a general load, can also be synthesized by this method, and are discussed. The direct or layer peeling algorithm is applied to generate profiles which are subsequently analyzed using the one-dimensional finite difference method and fabricated in stripline. Excitation for the nonuniform line is done by using a charged line connected to a photoconductive Si switch triggered by a mode-locked YLF laser. Several lines were fabricated relevant to amplitude modulation of the master oscillator laser pulse for fusion experiments. Using the layer peeling method, a complex high-voltage pulse shape for use in laser fusion experiments is synthesized to an extraordinary degree of precision. It is possible to generate any arbitrary pulse shape by reflecting a step pulse off a synthesized nonuniform transmission line provided the power spectrum of the reflected pulse does not exceed that of the input pulse at any frequency     

Transient analysis of nonuniform, high-pass transmission lines

The transient behavior of nonuniform transmission lines is studied by investigating the step response of a cascaded multiple-section line. The first arriving wave and the transition ripple at the load end are examined in detail. It is found that the characteristic impedances necessary for obtaining the maximum first arriving wave are the same as those of the conventional multiple-section, quarter-wave transformer. The discrete characteristic impedances of the multiple-section line are then extended to a continuously varied impedance function of a tapered line. The high-pass characteristic of the tapered nonuniform line is verified with techniques in the frequency domain     

Electromagnetic coupling to transmission lines under complex illumination

Electromagnetic coupling to transmission lines under complex illumination is studied. The proposed method relies on the plane wave spectrum representation of the excitation fields and on the complex equivalent length formalism. Results concerning the mathematical expectation of the induced voltage and of the maximal available power at the transmission line terminations are derived.     

Theory of nonreciprocal and nonsymmetric uniform transmission lines

A nonreciprocal and nonsymmetric transmission line is one which has different line parameters for waves propagating in opposite directions. Such a concept emerges in problems of electromagnetic wave propagation in layered structures of biisotropic (nonreciprocal chiral) media. It is shown that the well-known transmission-line formulas can be generalized for the present transmission line     

Natural frequencies of piecewise uniform transmission lines

A transmission line composed of a number of cascaded uniform lines with different characteristic impedances and lengths is considered. Approximate expressions for the chain parameters and natural frequencies useful to a variational synthesis are given.     

端接非线性负载的非均匀传输线瞬态分析

在均匀多导体传输线的时域有限差分法(FDTD)基础上，对非均匀多导体传输线及端接非线性负载的情况进行了分析。结果表明：对于非均匀多导体传输线，采用FDTD法进行瞬态分析极为方便，并且可以处理端接非线性负载的情况；同时，还可获得线上各点的电压、电流波过程。通过实例验证了所提出的FDTD算法的有效性，可用于传输线波过程的研究。     

General principle of electrical equivalence for nonuniform transmission lines

The criterion of electrical equivalence for nonuniform transmission lines, introduced by Hellstrom, has recently been interpreted in a more general form. The letter presents the electrical-equivalence principle' in a simple manner. It is shown that any nonuniform RC (or LC) line may be made electrically equivalent to another RC (or LC) line, if the physical lengths of the two lines are properly chosen.     

Green's function matrices of arbitrarily terminated nonuniform transmission lines

It is shown that the Green's function matrix of an arbitrarily terminated nonuniform transmission line can be readily determined, provided an analytical form of its ABCD parameter matrix is known. The procedure is illustrated with reference to the exponential line.     

An accurate calculation of uniform microstrip transmission lines

An analytical program for calculating the field distribution about a microstrip transmission line bounded by a shielding wall is used to calculate the impedance, velocity, and attenuation parameters. The program input parameters are the dimensions of the strip and shielding wall and the relative dielectric constant of the substrate material. The field distribution about the strip is integrated to find the charge density on the strip and walls with and without the dielectric substrate. From these two calculations, the relative velocity and impedance can be calculated.     

Driving point function synthesis using uniform transmission lines

It is shown that the two classes of driving point functions realized by Wyadrum and by O'Shea, using uniform transmission lines, are identical and further that these driving point functions may always be cascade synthesized. An alternative set of necessary and sufficient conditions for this class of driving point functions is given.     

Lumped-parameter analogues of nonuniform RC distributed networks and lossless transmission lines

Analogues of nonuniform RC distributed networks and lossless transmission lines are deduced, and their chain parameters are expressed in terms of the solutions of the associated voltage and current difference equations. It is shown that in many instances the above equations can be solved exactly, and an example includes the exponential, trigonometric, hyperbolic and other structures.