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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

[en] THEORETICAL INVESTIGATION ON THE LONG DISTANCE PROPAGATION BY TROPOSPHERIC DUCTS / [pt] INVESTIGAÇÃO TEÓRICA SOBRE A PROPAGAÇÃO À LONGAS DISTÂNCIAS POR DUTOS TROPOSFÉRICOS

JORGE KOURY BECHARA 30 September 2009 (has links)
[pt] Este trabalho trata do problema da propagação à longa distância por dutos troposféricos, sendo usado um modelo bi-linear para caracterizar a variação do índice de refração com a altura. Apesar da complexidade matemática, os resultados teóricos são de grande utilidade para uma análise qualitativa deste mecanismo de propagação. Entretanto, sob o ponto de vista quantitativo, tanto pela idealização da formulação teórica, como pela dificuldade de calcular numericamente as expressões resultantes, o mesmo não acontece. Assim, é imprescindível que se disponha de dados experimentais para complementar as informações que podem ser obtidas através do modelo matemático. / [en] This work considers the propagation problem in long distances by tropospheric ducts. A bi-linear model is used in order to characterize the refraction index variation as a function of height. Inspite of the mathematical sophistication, the theoretical results are vey useful in perfoming a qualitative analysis concerning this propagation scheme. On the other hand, by a quantitative viewpoint, the same is not true; and this is due to the idealization of theorectical formulation, as well as the dificulty of numerical implementation of resultant expressions. In this way, it is definitely necessary to have access to expressions. In this way, it is definitely necessary to have access to experimental data to complement the information supplied by the mathematical model.

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