Banca de DEFESA: ELIEL POGGI DOS SANTOS

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : ELIEL POGGI DOS SANTOS
DATA : 18/07/2019
HORA: 09:00
LOCAL: Sala de reuniões do PPgEEC
TÍTULO:

Development of a numerical technique for the analysis of frequency selective surfaces of the type absorb-transmitt.

PALAVRAS-CHAVES:

Microwave absorbers; Frequency selective surfaces; Numerical technique; Equivalent circuit method; Scattering matrix.

PÁGINAS: 80
GRANDE ÁREA: Engenharias
ÁREA: Engenharia Elétrica
SUBÁREA: Telecomunicações
ESPECIALIDADE: Teoria Eletromagnetica, Microondas, Propagação de Ondas, Antenas
RESUMO:

Modern wireless communication systems use various types of devices such as antennas, modulators, filters, detectors, absorbers and many other types for the most diverse applications emerging in the field of telecommunications. In particular, electromagnetic wave absorbers have become critical components in security, detection and imaging systems. The fundamentals of the absorbers are based on configurations that allow the control of the absorption of electromagnetic waves and that by increasing the performance requirements of microwave absorption, good performance in civil applications and the emergence of new types of materials absorbers of microwaves, attracted considerable attention from the researchers resulting in considerable progress.

In this sense, the full-wave methods and numerical methods are usually used for the analysis of several parameters in the telecommunications structures. They are used in many cases in the core of commercial software as well as in hybrid methods. The use of simpler numerical techniques allows an analysis of reflection and transmission behavior in a suitable way with good approximation mainly in cascade structures.

In this work the absorber structure is composed of a conductive frequency selective surface (FSS) and a resistive FSS in which there is a d spacing between the FSS. The conductive FSS is formed by a FR4 dielectric with an electric permittivity of 4.4 and the geometries formed by conductive copper strips. Resistive FSS have an FR4 dielectric with an electrical permittivity of 4.4 and the geometries are formed by OhmegaPly 1A50PT (35 micron - 50 ohms / sq) resistive materials.

The thesis proposal is to develop a numerical technique for the analysis of integrated microwave absorbers to selective surfaces in frequency. A model was used for conductive FSS and one for resistive FSS both using the equivalent circuit technique based on the Marcuvitz equations and for analysis of the set or cascade of the structures, the scattering matrix technique was used. Attempts have been made to use other techniques, however, this combination has resulted in better results. Internal parameters of the method such as coefficients, resistance, inductive and capacitive reactances of the geometries were analyzed in order to allow a better approximation with respect to the simulations and measurements.

The designed absorbers used cross-dipole geometry and square loop both designed and measured in the laboratory. The numerical analysis technique showed good agreement with the measured and simulated results of the author's own structures as well as with other measured and simulated absorbers presented in the literature. Improvements and modifications can be tuned for other applications, integrate with optimization techniques, hybrid algorithms and other projects of periodic structures.

MEMBROS DA BANCA:
Presidente - 2524053 - ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
Interno - 1412682 - VICENTE ANGELO DE SOUSA JUNIOR
Externo à Instituição - ALFREDO GOMES NETO - IFPB
Externo à Instituição - ERICO CADINELI BRAZ - IFRN
Externo à Instituição - MAURICIO WEBER BENJÓ DA SILVA - UFF