Desenvolvimento de material ferrimagnético do tipo NiFe2O4 para aplicação em sistemas de comunicação de micro-ondas
Due the need to develop new wireless technologies, the researches involving communication devices has become intense, mainly in characteristics like device miniaturization and reconfigurability. With this objective, this work presents a proposal for the development of ferrimagnetic compounds aimi...
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| Formato: | doctoralThesis |
| Idioma: | pt_BR |
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Brasil
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| Endereço do item: | https://repositorio.ufrn.br/jspui/handle/123456789/28471 |
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| Resumo: | Due the need to develop new wireless technologies, the researches involving
communication devices has become intense, mainly in characteristics like device
miniaturization and reconfigurability. With this objective, this work presents a proposal for the
development of ferrimagnetic compounds aiming their application in wireless communication
devices. The project was performed starting at the nickel ferrite (NiFe2O4) through Sol-Gel
modified by ICR technique. A calcination process was applied to eliminate organic compounds
from Sol-Gel, as the large particle size production, over 300 nm. The calcination was performed
at 1100 °C, for ten hours, with 10 °C/min step. The obtained particles were characterized by
SEM, XRD and EDS. Magnetic behavior (hysteresis loop) was also obtained, as complex
electric permittivity parameter. All performed morphological characterization were applied in
a study of Sol-Gel process efficiency, according to nitrate concentration on chitosan matrix.
The nitrate concentration was modified to verify which concentration promote better process
efficiency, so that 120 g/L concentration could be verified as the more suitable for a high-quality
product. Posteriorly, one of the proposed devices was manufactured: ferrite powder
encapsulated with low permittivity wood material, aiming FRA application. Electric
characterization was performed in all four types of applied woods. Reflection coefficient was
determined and discussed. Then, ferrite bulk materials were manufactured using a 15-ton
uniaxial press with propanone binding agent, followed by heating process before sintering. This
process was performed with same temperature parameters of the powder production, aiming to
not change microscopical characteristics. Electric characterization of ferrite bulk was
performed and its application as microstrip patch antenna substrate and FRA was verified.
Magnetic permeability was estimated based on previous papers characterization of NiFe2O4
powder. With electric characterization, simulations of FRA, with three different types of
excitation, and proposed antennas was performed by HFSS software, using FEM method and
the reflection coefficient was experimentally determined to validate the simulations. The
experimental results presented good agreement with all performed process of production and
characterization, reaching a 0.82% error in resonance frequency based on simulated results. The
nickel ferrite potential as FRA and microstrip patch antenna is evidenced along the results
discussion, being possible to expand the applications possibilities in other electrical engineering
fields. |
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