Thesis--Ph. D., University of Hong Kong, 1979.

The studies of the designs on true-time-delay lines (TTDLs), n-bit digital phase shifters and wideband switched-line phase shifters using composite right/left-handed transmission-line (CRLH TL) unit cells are presented in this thesis. To simplify these designs, a symmetrical CRLH TL unit cell having equal input and output impedance is proposed. In the design of TDDLs, the symmetrical CRLH TL unit cell with higher time-delay efficiency helps achieve a size reduction of 67.9%, compared with the TTDL designed using right-handed transmission line (RH TL). The symmetrical CRLH TL unit cell is further modified to a compact CRLH TL unit cell to further reduce the size by 58%. For performances comparison, the TTDLs using the compact CRLH TL unit cells, symmetrical CRLH TL unit cells and RH TL are studied using computer simulation and measurement. Results show that the TTDLs using the compact CRLH TL unit cells can achieve much longer time delays. The TTDLs designed using CRLH TL unit cells have narrow bandwidths because CRLH TL unit cells have narrow bandwidths. In this thesis, a wideband unit cell obtained by rotating the CRLH TL unit cell by 900is proposed in the design of TTDLs. Simulation and measurement show that the TTDL using wideband unit cells can achieve a time delay about 3 times and 6 times longer than that of the periodic microstrip line (PML) and RH TL, respectively. A 2-bit, 3-bit and 6-bit phase shifters using symmetrical CRLH TL unit cells are designed using computer simulation. In these designs, positive-intrinsic-negative (PIN) diodes mounted on the fingers of the CRLH TL unit cells are used as switches to control the phase response at the output. Different phase shifts are achieved using different switching states determined by controlling bits. The phase shifters are fabricated and measured. Simulated and measured results agree very well. Power-handling capability is also analyzed using surface-current density on the CRLH TL unit cells. Results show that the phase shifters have much higher power-handling capabilities than that of the PIN diodes. A wideband 1800-switched-line phase shifter using symmetrical CRLH TL unit cell is proposed. The switched-line phase shifter employs a symmetrical CRLH TL unit cell as the reference arm and a RH TL as the delay arm to produce a constant phase shift across a wide frequency band. For comparison, a traditional 1800-switched-line phase shifter using RH TLs for both reference and delay arms is also designed. To reduce the size, the CRLH TL unit cell is realized using lump elements (LEs). Wideband 900-and 1800-switched-line phase shifters using LE-CRLH TL unit cells are studied and compared with the traditional 900-and 1800-switched-line phase shifters. Simulated and measured results show that the proposed designs using symmetrical CRLH TL unit cells and LE-CRLH TL unit cells have very constant phase shifts with smaller variations compared with the traditional designs. / published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

In this thesis, the problem of overvoltage calculation on multiconductor transmission lines due to nonuniform external electromagnetic field excitations, such as lightning, is investigated by introducing a field-voltage macromodel. The main purpose of this thesis is to find a fast and efficient algorithm to model the effect of the radiated electromagnetic fields on transmission lines. This is done by replacing distributed voltage and current sources along the transmission line which are as a result of external electromagnetic field radiation, by voltage and current sources at the terminals of the transmission line. For this purpose, the knowledge of electromagnetic field at every point on the transmission line is required. A transfer function based pole-residue tracing technique will be introduced in this thesis. By using the proposed algorithm, a closed form solution for the lumped sources at the terminals of transmission line in the frequency domain is obtainable. This approach will enable us to bridge the software working in frequency domain with those working in the time domain. The effect of different parameters on calculated overvoltage such as finite conductivity of the ground and lightning return stroke channel (RSC) specifications are studied. The theoretical background and extent of validity of the proposed algorithm are reviewed in this thesis.

In this thesis, the problem of overvoltage calculation on multiconductor transmission lines due to nonuniform external electromagnetic field excitations, such as lightning, is investigated by introducing a field-voltage macromodel. The main purpose of this thesis is to find a fast and efficient algorithm to model the effect of the radiated electromagnetic fields on transmission lines. This is done by replacing distributed voltage and current sources along the transmission line which are as a result of external electromagnetic field radiation, by voltage and current sources at the terminals of the transmission line. For this purpose, the knowledge of electromagnetic field at every point on the transmission line is required. A transfer function based pole-residue tracing technique will be introduced in this thesis. By using the proposed algorithm, a closed form solution for the lumped sources at the terminals of transmission line in the frequency domain is obtainable. This approach will enable us to bridge the software working in frequency domain with those working in the time domain. The effect of different parameters on calculated overvoltage such as finite conductivity of the ground and lightning return stroke channel (RSC) specifications are studied. The theoretical background and extent of validity of the proposed algorithm are reviewed in this thesis.

Accurate, efficient and general computational techniques are developed to evaluate the scattering parameters of passive microstrip components composed of discontinuities in microstrip transmission lines on general two layer substrates with single and two level metallization. An open domain model is used. The Electric Field Integral Equation is examined and the Green's function for single and double layer dielectric substrates on a infinite ground plane are reviewed while emphasizing the important computational details to the model, including singularity of the kernel, evaluation of the Sommerfeld Integrals, and interpolation of the Green's functions. In order to model accurately complex circuit geometries, two dimensional currents are used. Different basis functions for expansion and for testing are chosen in order to make the computation more efficient and allow for structures having general shape in the moment method formulation. A transmission line current source is used to model the parameters are flowing in and circuit evaluated out of structure. Structures excitation and the scattering by calculating the currents each of the N-ports of the such as microstrip bends, microstrip crossovers of arbitrary angle, and coupled microstrip discontinuities are analyzed. To validate the model, results of some elementary structures are compared with published results of other models. / Graduation date: 1992

Thesis, Ph.D., University of Hong Kong, 1979. / Also available in print.

Thesis (M.E.)--University of Canterbury, 2008. / Typescript (photocopy). "June 2008." Includes bibliographical references (p. [89]-92). Also available via the World Wide Web.

Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, March 1990. / Thesis Advisor(s): Atwater, H.A. Second Reader: Lee, H. M. "March 1990." Description based on signature page as viewed on August 26, 2009. DTIC Descriptor(s): Strip Transmission Lines, Computer Aided Design, Computerized Simulation, Parameters, Microwave Equipment, Radar, Full Wave Rectifiers, Transmittance, Resonant Frequency, Construction, Wave Propagation, Coefficients, Boundary Value Problems, Resonators, Circuits, Discontinuities, Ka Band, Models, Scattering, Equivalent Circuits, Frequency. Author(s) subject terms: Millimeter wave, suspended substrate, design model. Includes bibliographical references (p. 78-79). Also available online.

No description available.

Fault location for series compensated lines cannot be addressed sufficiently by conventional solutions developed for traditional uncompensated lines. Line-parameters vary with loading and weather conditions, and therefore settings used for fault location are often erroneous. Line-parameter free solutions for fault location are therefore more reliable and accurate than conventional solutions that require such settings. Hence, line-parameter free fault location algorithms for single-circuit and double-circuit series compensated transmission lines were developed during the research project. Single-circuit lines and double-circuit lines both present unique challenges for fault location. They also vary in the number of available measurements that can be used to arrive at a solution for distance to fault. A third algorithm is presented that allows the extension of existing short line algorithms to the case of long lines. This is done by providing a method for incorporating the line shunt admittance into these existing algorithms. The aforementioned three bodies of research work, form the focus of this thesis. The algorithms are derived using two-terminal synchronised current and voltage sampled measurements. Of these, the algorithms for series compensated lines are also derived for asynchronous measurements. Phasors are obtained by carrying out a Fast Fourier Transform, and then appropriate calculations are performed for distance to fault. The thesis covers the mathematical derivations of the algorithms, involving the algebraic reduction of non-linear equations in numerous variables into a single expression for distance to fault. The results for a variety of simulation tests are shown subsequently and discussed. Various fault resistances, fault types, degrees of series compensation, line lengths, fault levels are considered in the tests carried out. The algorithms are largely found to be highly accurate under these various conditions, and where the algorithms perform to a lesser degree of accuracy are highlighted and discussed. Lastly, a detailed chapter discussing future work is also included in the thesis.