No description available.

Thesis (M.Sc.)--University of Adelaide, 1946. / C.S.I.R. Typewritten copy. Includes bibliographical references.

Thesis (M.S.)--Ohio University, November, 1982. / Title from PDF t.p.

Thesis (Ph. D.)--University of Hong Kong, 1999. / Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Madison, 1964. / eContent provider-neutral record in process. Description based on print version record. Bibliography: l. 62-63.

This work consists of two parts. The first part is a comprehensive study of surface-wave propagation along dielectric tube waveguides. It includes the derivation of the characteristic equations and expressions for group velocity and attenuation coefficient, the latter by a perturbation method. Mode designations are justified and the physical distinction between the HE₁₁ and EH₁₁ modes is further illustrated by showing three-dimensional plots of the field configurations. Computed characteristics are given for a wide range of parameters, and are compared with those of standard rectangular waveguides. Finally, a method of shielding the tube from weather conditions is proposed and the resulting changes in characteristics are noted. The second part of this work is essentially a unified analysis of all slow-wave modes in eight cylindrical waveguides. Characteristic equations are derived and expressions are obtained for the group velocity and the attenuation coefficients by a perturbation method. Accurate propagation characteristics for the dominant TM₀₁ mode are computed for four waveguides with no restrictions on their radial dimensions. These guides are the Goubau line and a coaxial cable with dielectric linings on the inner, outer, or both conductors. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

This thesis is mainly concerned with the effects of periodic loading of nonreciprocal waveguides by regular placement of discontinuitie and with the associated problem of the evaluation of a transverse discontinuity in a nonreciprocal ferrite loaded waveguide. The mode-matching technique is used to analyse a transverse discontinuity in a nonreciprocal waveguide. The difficult orthogonality relations are circumvented using a Galerkin approach. The elements of an exact three-element equivalent circuit for an infinitely thin metallic diaphragm are evaluated. Each element has two values, one for each direction of propagation. The numerical results show the same trends as those obtained experimentally in a similar configuration. The properties of a nonreciprocal, ferrite loaded, rectangular waveguide, which is periodically loaded by thin metallic "inductive" diaphragms, are investigated experimentally. The propagation constants of the structures are measured and are compared with predictions based on measured values of the scattering parameters of a single diaphragm in the nonreciprocal waveguide. The agreement between theory and experiment is generally good except for the smaller spacings between the diaphragms. This discrepancy is attributed to the effects of higher mode interaction. An investigation was also made of a magnetized ferrite loaded ridged waveguide. A theoretical and experimental investigation was first made of the preliminary problem of a reciprocal, inhomogeneous ridged waveguide and guided by these results an approximate, theoretical technique was formulated to analyse the nonreciprocal ferrite loaded ridged waveguide problem. It was found that introduction of the ridge had detrimental effects on the differential phase shift characteristics except for a few special cases. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Unknown

Ray-optical methods are used to calculate the coupling between open-ended parallel-plate waveguides, as well as the radiation patterns of finite arrays of coupled parallel-plate waveguides with only the central guide driven. These methods require extensive ray tracing, particularly for the larger arrays, to take into account the many possible ray paths. The coupling coefficients between both two and three guides in isolation agreed remarkably well with those previously derived in the presence of other guides, groundplanes etc., indicating a general lack of sensitivity of the coupling coefficients to the details of the surrounding structure. The calculated patterns were compared with experimental patterns using an H-plane sectoral horn to simulate the parallel-plate waveguide array. Radiation patterns of both three and five element arrays with all waveguide edges in the aperture plane, as well as that of a three element staggered array with the outer edges not in the aperture plane agreed well with the experimental patterns. A wide variety of patterns could be obtained by varying the width, depth, and number of the outer guides in the array. Ray-optical methods may thus be useful in the development of waveguide antennas for a variety of applications. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

No description available.

In this thesis, passive and active 3-branch Ti:LiNbO$ sb3$ waveguide devices were investigated. A multimode field-matching technique was employed to predict the power division in a passive 3-branch waveguide power divider. The limitation and range of validity of this method were pointed out. An alternative method was also employed to predict the power division when coupling between two neighbouring branches is not negligible, as is the case when the branching angle becomes small. The multimode field-matching method was also employed to predict the power division in an active 3-branch waveguide switch, where switching is achieved through the electrooptic effect of LiNbO$ sb3$. The edge effect of the electrodes on the beam steering was also considered. A linear mode-confinement modulator was then proposed and investigated as a derivative of the 3-branch waveguide switch. / Fabrication and experimental characterization of the three devices were also carried out. Key functional parameters were measured and compared with theoretical predictions. In general experimental results have borne out theoretical prediction. / Some calibration of the fabrication techniques employed, were also performed. An outline of the various experimental techniques used is also given. / Finally, some possible improvements are suggested for further work.