Navegando por Assunto "Antena"

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Acesso aberto (Open Access)
Estruturas photonic band gap em antena de microfita com aplicações em microondas e terahertz
(Universidade Federal do Pará, 2019-08-16) OLIVEIRA, Jorge Everaldo de; COSTA, Marcos Benedito Caldas; http://lattes.cnpq.br/7636226766852440
In this work we are analyzing the simulations of two microstrip antennas. The first is an antenna using the ceramic material Bismuth Niobate (BiNbO4) doped with Vanadium Pentoxide (V2O5) on the substrate. The antenna patch was designed with indented power line to facilitate matching of impedances and the substrate with air holes was placed just below the patch to further decrease the losses. The second is a nano-antenne with Graphene Patch in the Terahertz range and PBG (Photonic Band Gap) substrate with triangular mesh, and holes in the following height configurations h1, h2 and h3. At time h1 the substrate is fully drilled, while at heights h2 the holes will be made top to bottom of the substrate and the height h3 is the antenna with substrate drilled from the bottom up to the middle of the substrate. Therefore three antennas are created in these geometries using a triangular hole network. The arrangement of the holes in the dielectric substrate constitute the PBG structure, to increase the performance and efficiency of these antennas, extinguishing surface waves in the substrate of microstrip antennas. The adopted geometry also improves antenna parameters such as efficiency and bandwidth. The commercial software HFSS and CST were used for the simulations of the antennas. After the numerical simulation steps the results of the parameters of these devices were obtained. The first antenna (periodic lattice with ceramic substrate) obtained a return loss of -36.21 dB, at a resonance frequency of 10,26 GHz, with a bandwidth of 2.18 GHz. In the simulations of the antennas of microstrip with Patch of graphene the antenna h3 obtained double transmission band with chemical potential of graphene of 0,3 eV.
Acesso aberto (Open Access)
Propriedades elétricas de nanoantena de grafeno
(Universidade Federal do Pará, 2015-02-24) TAVARES, Simone Cristina da Costa; DEL NERO, Jordan; http://lattes.cnpq.br/5168545718455899
The incessant rush for discovering new materials and the search for new solutions to the tech-nological problems and equipment that have devices with better performance than the currently available, operating at ever smaller scales led us to study antennas that allow to occupy an increasingly small space. This permitted us to show the study of the electronic carbon nanotube structure and the electrical properties of graphenenano-antenna as its precursors. The develop-ment of antennas made of carbon nanotube and graphene is, in the moment, a technological possibility opened to state of art. In this paper we investigate the electronic transport for gra-phene organic material using it as a nano-antenna where we present simulations of quantum calculations derived from Hartree-Fock theory and semi-empirical method, which is given by the electron charge distribution along the structure. The structural parameters of the optimized structure have been fully calculated, including external electric field across the matrix layer of closed Roothaan-Hall model. Featuring a characteristic related to the electrical response which results a transistor device field effect, with capacitance and operating frequency in 90 THz un-der an operating voltage around the 0,82 V rectification and we show, also, the Fowler-Nord-heim model and Millikan -Lauritsen for graphene structure.