Banca de QUALIFICAÇÃO: FELIPE ROCHA OLIVEIRA

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : FELIPE ROCHA OLIVEIRA
DATE: 19/02/2026
TIME: 15:30
LOCAL: Auditórion do CTEC da UFRN
TITLE:

Functional Reconfiguration of Planar Microwave Circuits for Sensing Applications

KEY WORDS:

Microwave sensors; Fractal antennas; Parallel-coupled line filters; Dielectric characterization; CSRR; Functional reconfiguration

PAGES: 106
BIG AREA: Engenharias
AREA: Engenharia Elétrica
SUBÁREA: Telecomunicações
SPECIALTY: Teoria Eletromagnetica, Microondas, Propagação de Ondas, Antenas
SUMMARY:

This work presents the development and characterization of two planar microwave circuits —a parallel-coupled line bandpass filter and a Koch fractal antenna with a complementary split-ring resonator (CSRR) notch — with the aim of demonstrating their functional reconfiguration as dielectric sensors. Initially, both devices were designed and evaluated in terms of their electromagnetic performance in their primary functions: the filter was synthesized to operate in the Bluetooth band (2.39–2.49 GHz), while the fifth iteration Koch fractal antenna was designed to exhibit multiple narrowband resonances. Subsequently, the structures were investigated as planar sensors by exploiting the resonant frequency shift induced by dielectric materials placed in regions of high surface current density. The adopted methodology involved full-wave electromagnetic simulations using HFSS, followed by prototyping and experimental measurements with a vector network analyzer. The sensing performance was assessed through key metrics such as frequency shift, sensitivity, percentage variation of the resonant frequency, and relative error, considering relative permittivities ranging from 1 to 20. In addition, the dielectric characterization of solid materials (FR4, ABS, and dry sand) was performed, and the estimated permittivity values were compared with reference data from the literature. The results show that the parallel-coupled line filter exhibits good sensitivity when compared with literature references, with percentage errors below 5% for the tested materials. For the fractal antenna, the insertion of the CSRR enabled selective control of the resonant bands, making its operation as a sensor feasible, with one resonance presenting performance comparable to that reported in the literature. Overall, this work demonstrates that structures originally conceived for wireless communication applications can be effectively exploited as microwave sensors without any geometric modification, representing an efficient and versatile approach for the development of multifunctional devices.

COMMITTEE MEMBERS:
Presidente - 6345784 - ADAILDO GOMES D ASSUNCAO
Interno - 349732 - LAERCIO MARTINS DE MENDONCA
Externo à Instituição - ADAILDO GOMES D ASSUNCAO JUNIOR - IFPB