Electrical and Computer Engineering ETDs

Publication Date

12-12-1979

Abstract

The time-domain transmission-line equations for uniform multiconductor transmission lines in a conductive, homogeneous medium excited by a transient, nonuniform electromagnetic field, are derived from Maxwell's equations. Depending on how the line voltage is defined, two formulations are possible. One of these formulations is considerably more con­venient to apply than the other. The assumptions made in the derivation of the transmission-line equations and the boundary conditions at the terminations are discussed. For numerical calculations, the transmission­line equations are represented by finite-difference techniques, and numerical examples are included.

An effective method for computing the time-domain response of loss­less multiconductor transmission lines with branches in a cross-sectionally inhomogeneous dielectric medium is presented. Lines of this type are characterized by multiple propagation modes having different velocities. The theory of wave propagation on lossless multiconductor transmission lines with inhomogeneous dielectrics is used to obtain the modal amplitudes on the uniform section of the line. The scattering matrix for the junction is used to compute the transmitted and reflected waves in the different branches at the junction. Each mode arriving at the junction excites multiple modes in all branches. This method identifies all propagation modes in all branches of the line and leads to the direct physical interpretation of the results. The method is general and can be applied to either partially or completely nondegenerate cases. Experimental results for a six-conductor transmission line with a single branch are found to be in good agreement with the results computed using the described method.

The experimental technique for the measurement of multiconductor line parameters is presented and the appropriate multiconductor-line equations are solved to obtain these parameters. The experimental method is simple and involves only the short- and open-circuit impedance measurements for different configurations. The experimental results for a four-conductor line are found to be in good agreement with computed results and a low-frequency lumped model.

An effective method for the time-domain characterization of loss­less multiconductor transmission lines with cross-sectionally inhomoge­neous dielectrics is presented. Lines of this type are characterized by multiple propagation modes having different velocities. Time-domain reflectometry is used to obtain the characteristic impedance and the modal velocities of the line. A pulse or step-function response of the line is used to obtain the modal amplitudes which, in turn, deter­mines the velocity matrix. The appropriate multiconductor transmission­line equations are solved to obtain the per-unit-length inductance and capacitance matrices in terms of the measured characteristic-impedance and velocity matrices. The method is concise and complete and identi­fies the propagation modes in a way that permits direct physical inter­pretation of the results. The time-domain experimental results for a four-conductor transmission line are presented and are found to be in good agreement with independent frequency-domain measurements.

Document Type

Dissertation

Language

English

Degree Name

Electrical Engineering

Level of Degree

Doctoral

Department Name

Electrical and Computer Engineering

First Committee Member (Chair)

Shyam H. Gurbaxani

Second Committee Member

Martin D. Bradshaw

Third Committee Member

William Jackson Byatt

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