Banca de DEFESA: GABRIEL AMARAL SOUTO

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : GABRIEL AMARAL SOUTO
DATE: 18/07/2025
TIME: 09:00
LOCAL: Remoto
TITLE:

Analysis and Design of Communication Devices for High Frequency Applications

KEY WORDS:

Graphene Cardioid Antenna; QCL; DMSO; Graphene Pptical Sensor; Rib Waveguide; Surface Plasmons.

PAGES: 70
BIG AREA: Engenharias
AREA: Engenharia Elétrica
SUBÁREA: Telecomunicações
SPECIALTY: Teoria Eletromagnetica, Microondas, Propagação de Ondas, Antenas
SUMMARY:

The constant evolution of information technology demands increasingly innovative, fast and reliable solutions for data transfer. In this scenario, the use of higher frequency bands allows applications that support higher transmission rates and speeds. In this context, graphene emerges as a promising alternative to noble metals in high-frequency applications, presenting advantages such as lower losses, malleability, water resistance and adaptability, especially in the gigahertz to terahertz bands. This study presents an analysis of two high-performance graphene-based devices intended for applications in quantum cascade lasers (QCL) in the Terahertz band: a microstrip antenna with cardioid geometry for Terahertz transmission, built with graphene multilayers, and a Rib-type waveguide used as a high-sensitivity plasmonic biosensor. The dynamic conductivity of graphene was obtained by the Kubo formalism and, subsequently, modeled with the Drude-like approximation to define the final parameters. The antenna was designed with a cardioid-shaped radiating element on a silica substrate, using the Full Wavelength Method (FWM) for initial dimensioning, followed by the application of the Finite Element Method (FEM) for parametric analysis of the substrate height. For the plasmonic sensor, a waveguide with a tantalum pentoxide (Ta₂O₅) substrate was developed, with a niobium pentoxide (Nb₂O₅) ridge, on which a multilayer graphene sheet was deposited. This structure was designed to analyze variations in dimethyl sulfoxide (DMSO) concentration from 50% to 100%, in 10% increments. The localized surface plasmon resonance (LSPR) effect occurs at the interface between graphene and the analyte and is induced by the oscillations of free electrons in the graphene coupled to the electromagnetic fields. For detection of DMSO concentrations, the structure was tuned to operate at a wavelength of 0.6329 µm.

COMMITTEE MEMBERS:
Presidente - 1422265 - JOSE PATROCINIO DA SILVA
Interno - 2524053 - ANTONIO LUIZ PEREIRA DE SIQUEIRA CAMPOS
Interno - 349732 - LAERCIO MARTINS DE MENDONCA
Externo à Instituição - IDALMIR DE SOUZA QUEIROZ JÚNIOR - UFERSA
Externa à Instituição - SAMANTA MESQUITA DE HOLANDA - UFERSA