Navegando por Assunto "Geometric theory of diffraction"

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A Radio propagation model for mixed paths in Amazon environments for the UHF band
(Universidade Federal do Pará, 2019-01-22) ERAS, Leslye Estefania Castro; CAVALCANTE, Gervásio Protásio dos Santos; http://lattes.cnpq.br/2265948982068382
The present work proposes a radio propagation model for the Amazon region called Mixed Path. The techniques used for Mixed Path model are Geometrical Optics (GO) and the Uniform Theory of Diffraction (UTD). Only ten rays are considered the main contributors to calculate the total electric field. Increasing the number of rays does not improve the accuracy of Mixed Path model since the scenario is for receivers located in long distances. Then slope diffraction or multiple reflections means a low electric field that does not contribute significantly to the total electric field. The parameters of Mixed Path model such as electrical constants, antennas height, buildings height among others, are analyzed in order to know the influence of them in the received electric field. Measured data in the central frequency of 521 MHz of a Digital Television station in the city of Belem of Pará are used to validate Mixed Path model. This city is located in the Amazon region of Brazil and presents mixed routes formed by city, river, and forest. Because digital television has a wide coverage and reception flexibility, Mixed Path was designed for receivers at the user’s level for the service of Mobile Digital Television (M-DTV) and for fixed receivers on the rooftops of homes for Home digital television (H-DTV). Finally, the proposed model and other models in the literature are compared with the data measured for M-DTV, being Mixed Path the model with the lowest RMS error with a value of 3.15 dB for a receiver over the river behind the city and behind the forest.