Navegando por Assunto "Return loss"

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Acesso aberto (Open Access)
Projeto de um monopolo Hi para aplicações no sistema brasileiro de TV digital
(Universidade Federal do Pará, 2013-01-04) ALCÂNTARA NETO, Miércio Cardoso de; BARROS, Fabrício José Brito; http://lattes.cnpq.br/9758585938727609; CAVALCANTE, Gervásio Protásio dos Santos; http://lattes.cnpq.br/2265948982068382
This research deals with the design and analysis of a planar monopole antenna with modified geometry aiming its use for signal reception of digital TV in Brazil working in the of 470 MHz to 806 MHz. Track this contained in the spectrum of UHF-Ultra High Frequency (300 MHz to 3 GHz). To develop this work was taken as reference the antenna called "The Hi Monopole". What originally was presented to operate in UWB (Ultra Wide Band) at 3.1 to 10.6 GHz. For the development of the proposed work, different techniques of adjustment of the antenna can be used for broadband operation, such as: changes in the structure of antenna, resistive loading, switching, using of parasitic elements and matching structures. The design of broadband antennas can be made from three different approaches: time domain, frequency domain and expansion for singularities method. The frequency domain method was employed in this work to the antenna design proposed, some of the techniques mentioned above were analyzed aiming to increase bandwidth, and made a prototype of the antenna to validate the concepts employed. The antenna was designed for the range of 470 MHz to 890 MHz. the prototype built for this same range presented good results, which validates the technique employed. Positive and negative aspects of use of this technique are discussed throughout the work. The commercial computer program CST® MICROWAVE STUDIO, based on the Finite Integration Technique (FIT) was used for simulations in frequency domain.
Acesso aberto (Open Access)
Projeto e construção de um monopolo para aplicações de banda ultralarga (UWB) com elementos fractais
(Universidade Federal do Pará, 2015-05-08) SANTOS, Nelson Mateus Ferreira; CAVALCANTE, Gervásio Protásio dos Santos; http://lattes.cnpq.br/2265948982068382
This work describes the design and analysis of antenna monopole printed type. The initial geometry in the printed monopole antenna is of a regular hexagon, with 9 mm segments in length. The initial proposal is an antenna to serve the UWB range (3.1 to 10.6 GHz). To achieve a bandwidth satisfying the proposed problem, fractal curves (Peano curve and the Koch curve) were implemented in the geometry composition of the monopole and the ground plane, respectively, the introduction of these curves generate additional resonances, optimizing bandwidth and serving the specifications of UWB systems. To perform the analyzes, CST Microwave Studio ® software was used, which is based on finite integration method in the time domain, having the computing environment to simulate the antenna properties and the electromagnetic behavior of the same as the results of these simulations, a new frequency range going from 2.74 to 11.5 GHz is presented, satisfying the range of UWB systems. As a last stage, a prototype was made and the measurements with the proper equipment to compare the measured results with the simulated were realized, covering a frequency range from 3.2 to 13.5 GHz, where the range of results shows concordance with the simulated, validating the model.