Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Wanting leaves 220-226 Conclusions and recommendations. Typescript. Vita. Includes bibliographical references (leaves [339]-342). Also available on the Internet.

Thesis (M. Eng.)--Carleton University, 2001. / Includes bibliographical references (p. 189-193). Also available in electronic format on the Internet.

The objective of this research is to compare radio channel impulse response measurements with site-specific radio wave propagation prediction techniques. A wide band spread spectrum measurement system was developed, and desirable measurement locations were selected on the Virginia Tech campus. These measurements are designed togo beyond statistical characterizations of the channel and will aid in determining how the propagation environment is influencing the multi path propagation. The objective is to not only measure the delays and relative powers of multi path components, but to carefully document their angles of arrival and resolve the overall paths that these multipaths had to take to reach the receiver. This information will be used to compare with propagation prediction simulations using the modeled environment, and therefore, provide new insight into the nature of reflection and scattering of radio propagation in typical microcellular environments. As a first step in this endeavor, building surface characterizations are made in order to determine empirical reflection coefficients of common building materials. Propagation experiments have been designed to determine applicability of Fresnel reflection formulas to non-ideal conditions, such as waves that are not perfect plane waves, rough surfaces, etc. This information allows propagation prediction techniques to further quantify the site-specific mobile radio environment and yield more accurate propagation estimates. For this endeavor, Whittemore Hall and Squires Student Center were Chosen to provide reflection measurements from rough stone, glass, and brick surfaces. Detailed descriptions of measurement techniques, analysis and results are included. / Master of Science

In this thesis a numerical technique is developed determining the propagation constant in waveguides and transmission lines. The technique accounts for both dielectric and conductor losses in a guide having an arbitrary cross section and uses a full-wave solution process. A set of coupled, vector integral equations which characterize the system are derived. The equations enforce the necessary boundary conditions on the tangential electric and magnetic fields at the boundaries separating the conductors and dielectrics. The method of moments (MOM) technique is used to cast the equations into a numerically solvable form. Computed results for various waveguide structures are compared to known or perturbed results for three well-known structures. However, the program is more general and may be applied to other cross-sections. Finally, possible future extensions of the work is presented. / Master of Science

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 138-145). Also available via the Internet.

Orientador: Luiz Carlos Pereira da Silva / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-24T07:39:20Z (GMT). No. of bitstreams: 1 Gomes_LeandroCostaFerreira_M.pdf: 6148500 bytes, checksum: bf5007e253bf40d848b0494ce01ead56 (MD5) Previous issue date: 2014 / Resumo: O presente trabalho está inserido num contexto de busca de novas fontes de energia elétrica e de aproveitamento de grandes potenciais energéticos localizados distantes dos principais centros de carga. Para estes, alternativas não convencionais de transmissão também são exigidas, nas quais se insere a transmissão em linhas de pouco mais de meio comprimento de onda, distância de pouco mais de 2500km no sistema brasileiro à 60Hz. Como este tipo de transmissão nunca foi implementado, trata-se de uma proposta inovadora, pouco explorada e que exige ensaios elementares para testar-se a viabilidade, vantagens e desvantagens frente a outras alternativas de transmissão de energia elétrica. Esta dissertação visa investigar alguns aspectos referentes à tal método de transmissão de grandes montantes de potência em distintos cenários de interligação entre as regiões Norte e Sudeste do Brasil do SIN (sistema interligado nacional). Três distintos corredores compostos por linhas de pouco mais de meio comprimento de onda foram ensaiados. Inseridos conectando a usina de Belo Monte no Pará a Assis-SP na rede de 500kV, percorrendo 2664 km. Cada um dos corredores é composto por: três linhas de 800 kV e 4846 MW de potência característica (SIL); um segundo com duas das mesmas linhas de 800kV e um terceiro com duas linhas de 1000 kV e 8100 MW de potência característica. Cada aspecto é ensaiado em seis diferentes situações de carregamento do SIN e de fluxo de potência pelo corredor, abrangendo cenários de alto, médio e baixo carregamento das linhas assim como mudanças no sentido do fluxo entre Norte e Sudeste. Dentre os aspectos abordados estão: a avaliação e redução das perdas manipulando a potência característica operacional das linhas; o controle do carregamento do corredor através do uso de transformadores defasadores não convencionais; a inserção de cargas e geração em pontos intermediários deste e o controle do fluxo de potência reativa. Por fim, o estudo não aborda aspectos transitórios e é realizado com o auxílio do ANAREDE, software elaborado pelo CEPEL / Abstract: This work is placed in a search for new sources of power and exploitation of large energy potential located far from major load centers. For the second scenarios, alternate non-conventional transmission are also required, in which half wavelength transmission lines are inserted, resulting in a distance of just over 2500km for the 60Hz brazilian electrical system. Since this type of transmission has never been implemented, it is an innovative solution and few explored, requiring elementary studies to test the feasibility, advantages and disadvantages compared to other alternatives for bulk electric power transmission. This thesis aims to investigate some aspects related to such transmission method for large amounts of power into distinct scenarios of interconnection between the North and Southeast of Brazil's SIN (Brazilian National grid). Corridors consisting of three distinct lines of just over half wavelength were tested. Inserted connecting Belo Monte hydro power plant in Para to Assis in São Paulo through the 500kV network, covering 2664 km, each corridor is composed: by three lines of 800 kV and 4846 MW of Surge Load Impedance (SIL), the second one by two of the same 800kV lines and a third by two lines of 1000 kV and 8100 MW SIL. Each aspect is tested in six different SIN load situations and power flowing through the corridor, covering scenarios of high, medium and low lines loading as well as changes in flow direction between North and Southeast. Among the issues tackled are: evaluation and reduction of losses by manipulating operating lines SIL; line load controlling using non-conventional phase shift transformers; inserting loads and generation at intermediate points of the lines and control of reactive power flow. Finally, the study does not handle with transient aspects and is accomplished with the aid of ANAREDE, software developed by CEPEL / Mestrado / Energia Eletrica / Mestre em Engenharia Elétrica

The increasing demand for greater capacity of mobile communications has led to the petition of more radio spectrum at 1900 MHz for the new personal communication service (PCS) systems. The PCS spectrum is proposed to coexist with current fixed microwave spectrum. This presents cochannel interference control problems which can be avoided with extensive propagation studies in both measurements and predictions. Currently, there is no readily available tool to predict propagation channels for the small coverage area that PCS operates at 1900 MHz. This thesis presents new methods for propagation prediction without relying on measurements but rather local environment geometries and their electrical properties. The propagation prediction tool developed is based on the principle of geometrical optics and Fresnel-Kirchoff diffraction. Geometrical optics enables computer software to automatically trace the propagation of radio wave energy from the transmitter to the receiver. The ray tracing techniques presented are optimized for speed with a little trade-off in accuracy. Also, efficient techniques were developed to find true diffracting building edges in dense urban environments. The propagation prediction software also rely on other commercial software packages such as AutoCAD and GRASS to maintain and manipulate the environmental database as well as displaying prediction results. The software yielded reasonable accuracy when compared against VT campus propagation measurements at 900 MHz and 1900 MHz. / Master of Science