Thesis (M.S.)--University of Wisconsin--Madison, 1969. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1966. / Vita. Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis--Columbia University. / Vita. Includes bibliographical references.

Thesis (Ph.D.)--University of Delaware, 2008. / Principal faculty advisor: John Q. Xiao, Dept. of Physics and Astronomy. Includes bibliographical references.

Thesis (MScEng)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: Equal division microwave power dividers are investigated in this study. A wideband Wilkinson power divider and a wideband directional coupler with a centre frequency of 10 GHz were built. The design of the directional coupler is scaled, such that it can be used between 18 and 40 GHz. The details of the electromagnetic analyses of these structures are discussed and physical implementation issues are investigated. In a complementary study to the design of planar microwave dividers, the FDTD computational method was implemented and used to analyse the Wilkinson divider and the 18 to 40 GHz directional coupler. Results are compared to those obtained from commercial numerical method packages and in the case of the Wilkinson divider, to measured results. Suggestions are made for improvements in the implementation of the directional coupler and methods for a more efficient FDTD implementation are discussed. / AFRIKAANSE OPSOMMING: Mikrogolf drywings verdelers wat gelyk verdeel, word in hierdie studie ondersoek. ’n Wyeband Wilkinson verdeler en wyeband gerigte koppelaar met ’n senter frekwensie van 10 GHz is gebou. Die onwerp van die gerigte koppelaar is ook geskaleer sodat die ontwerp gebruik kan word tussen 18 en 40 GHz. Die details van die elektromagnetiese analise van hierdie strukture word bespreek en kwessies rondom die implementering van die strukture word ondersoek. In ’n komplementere studie, is die Eindige Verskil Tyd Gebied numeriese metode (Engels: FDTD) geimplimenteer en gebruik om die Wilkinson en die 18 tot 40 GHz gerigte koppelaar te analiseer. Resultate word vergelyk met resultate verkry met numeriesie metodes geimplimenteer in kommersiele pakkette, en in die geval van die Wilkinson verdeler, ook met gemete resultate. Aanbevelings word verder gemaak vir verbeterings in die implementering van die gerigte koppelaar asook metodes om ’n meer effektiewe FDTD kode te implementeer.

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An analysis of a class of corrugated structures is given for the purpose of determining the extent to which slot evanescent modes affect the shape of the dispersion curve. The analysis also permits a critical examination of a previous prediction of conditional confluence in this structure. An existing analysis of the cylindrical slot-coupled cavity chain is presented and then extended to include the effect of higher normal modes. The accuracy of this extension is examined experimentally. A discussion of zero-mode conditional confluence based upon this theory is presented. Experimental confirmation of zero-mode confluence is made. The possibility of achieving conditional confluence in the centipede structure and the reversed-loop-coupled cavity chain is discussed. The discussion is based upon an analysis by Bevensee. Two confluence tests are presented to complement the existing one. Finally, a discussion on the usefulness of auto-confluent structures for accelerator applications is presented. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

The microwave absorption spectra of ortho pairs in low ortho concentration samples of solid hydrogen is studied theoretically and experimentally. A theory is developed for several line broadening mechanisms and a comparison made with experiment. Phonon induced lifetime effects are calculated to be less than 2 MHz in the temperature range T=1.2-4.2 K but have not yet been observed experimentally. Inhomogeneous broadening due to isolated ortho molecules and to isotopic mass defect impurities is observed and found to be consistent with theory. Several new lines in the out-of-plane pair configuration are reported which confirm the assignments made previously, whereas two new lines in the next nearest neighbor configuration support a reassignment of these transitions. Also, three excited state transitions which fix the position of the 10 P level are reported and compared with the theoretical predictions of Harris et al. (1977) and Luryi and Van Kranendonk (1979). / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Given the proper conditions, antennas applied in medicine can offer improved quality of life to patients. However the human body proves hostile to typical, analytical antenna design techniques as it is composed entirely of frequency- and temperature-dependent lossy media. By combining optimization techniques with numerical methods, many of these challenges may be overcome. Particle swarm optimization (PSO) models the solution process after the natural movement of groups such as swarms of bees as they search for food sources. This meta-heuristic procedure has proven adept at overcoming many challenging problems in the electromagnetics literature. Therefore, this dissertation explores PSO and some of its variants in the solution of two biomedical antenna problems. Recent advances in biosensor technology have led to miniaturized devices that are suitable for in vivo operation. While these sensors hold great promise for medical treatment, they demand a wireless installation for maximum patient benefit, which in turn demands quite specific antenna requirements. The antennas must be composed of biocompatible materials, and must be very small (no more than a few square centimeters) to minimize invasiveness. Here PSO is applied to design a 22.5 mm × 22.5 mm × 2.5 mm implantable serpentine planar inverted-F antenna for dual-band MedRadio and ISM operation. Measurements reveal the accuracy of the models. Hyperthermia is the process of elevating a patient’s temperature for therapeutic gain. Since the ancient Egyptians, physicians have employed hyperthermia in the destruction of cancerous tumors. Modern implementations typically apply electromagnetic radiation at radio and microwave frequencies to induce local or regional heating. In this dissertation PSO is used to evaluate candidate antennas for inclusion in an array of antennas with the aim of local adjuvant hyperthermia for breast cancer treatment. The nearield of the array is then optimized to induce a uniform specific absorption rate throughout the breast.