https://orcid.org/0000-0002-9936-1994
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Abstract
A planar sensor designed using the fourth Hilbert fractal curve iteration for solid material characterization at multiple frequencies is reported in this paper. The fractal curve is self-similar with space-filling properties. The Hilbert fractal geometry is used to form a compact resonator, with a multiband frequency response where miniaturization is achieved since a large transmission line length is effectively confined in a limited area. The sensor provides five resonances in the frequency range from 0 to 5 GHz. The resonant frequencies are 0.56, 1.68, 2.72, 3.69 and 4.72 GHz, all used to measure the real permittivity of known samples with a sensitivity of 7, 20, 27, 43 and 50 MHz/permittivity, respectively. The sensor is used to measure dielectric samples with 20 × 20 mm2 areas with several thicknesses. Simulations and measurements demonstrate that the Hilbert fractal geometry can be used to design a multiband planar sensor for solid dielectric material characterization.
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Notes on contributors
C. P. do N. Silva
C. P. do N. Silva recently conclude her Ph.D. in electrical engineering at Federal University of Pernambuco (UFPE). In the Ph.D., she studied the design, manufacture and tests of active and passive microwave circuits for frequency identification and sensors devices. Obtained the Master’s Degree and her B.Sc. Degree in Electrical/Electronic Engineering at same institution. The Master’s Degree was with emphasis on development of passive microwave devices. During her undergraduate studies, she joined the Microwave Laboratory of UFPE, since then, she has been participated in research projects and contributed to national and international publications in this laboratory. Hers interests include active and passive microwave devices, filters, couplers, antennas and sensors.
J. A. I. Araujo
J. A. I. Araujo received his B.Sc. in Electrical Engineering from Federal University of Piauí, Brazil in 2017, and M.Sc. in Electrical Engineering from Federal University of Pernambuco, Brazil in 2019. He is currently a Ph.D. student with the Federal University of Pernambuco, Recife, Brazil. His research activities focus on electromagnetic waveguides, antennas and resonators, microwave sensors and FSS.
M. S. Coutinho
M. S. Coutinho received the B.S. degree in Telecommunication Engineering from the Centro Universitário Maurício de Nassau, Recife, Brazil, in 2014. In this year, he started to work as a RF and cellular engineer. Since 2015, he has been working toward the M.S. degree from the Universidade Federal de Pernambuco. He received the M.S. degree in Electrical Engineering in 2017. The subject of the dissertation was focused on microstrip sensor for materials characterization. He is currently pursuing his Ph.D. in electrical engineering, at the same university. His present research interests include fault detection in metal structures through microwave devices and the design and fabrication of coplanar structures in microwave and RF frequencies, like antennas, filters, sensors, fractal structures and couplers.
M. R. T. de Oliveira
M. R. T. de Oliveira completed her B.Sc. Degree in Electronic Engineering at the Federal University of Pernambuco (UFPE) in 2013. She also completed her D.Sc. and Master’s Degree with emphasis on Photonics, in the design and manufacture of Frequency Selective Surface, at the same institution in 2016 and 2018 respectively. Form 2010 to 2012, she joined the Microwave Laboratory of UFPE to participate in a program of scientific initiantion. She is professor at the Instituto Federal de Pernambuco, Campus Garanhuns.
I. Llamas-Garro
Dr I. Llamas-Garro is an expert in the field of device engineering and implementation from design to fabrication and testing, applied to wireless communications and sensors, including RF and microwave circuits, reconfigurable designs using microelectromechanical systems and semiconductor diode-based components. Micromachined devices, 3D printing of microwave passive components, inkjet printing of planar circuits and sensors, and micro/nano fabricated optical sensors for the detection of hazardous liquids and gases. Ignacio Llamas-Garro obtained his Ph.D. from the University of Birmingham, United Kingdom in 2003, and has been with the CTTC since 2010.
M. T. de Melo
Prof. M. T. de Melo, has completed undergraduate degree in Physics from the Federal University of Pernambuco-UFPE, Brazil, in 1983. Continuing his studies at the same University he received the M.Sc. degree also in Physics in 1992, where his dissertation focused on Microwave Absorption on Superconducting Samples. In 1997, he received the Ph.D. in Electrical Engineering from Birmingham University, England, where his thesis focused on High Temperature Superconducting Devices. In 1999, he joined the Department of Electronic and Systems, UFPE. During 2012–2013 he also had the position of Visiting Professor at Imperial College London, Electrical and Electronic Engineer Dep. He is now Visiting Professor at CTTC (Centre Tecnólogic de Telecomunicacions de Catalunya)-Barcelona-Spain. He became full Professor of the UFPE in 2019. He was able to contribute to attracting more than 9 million dollars in research and development projects, involving government funding agencies and also (mainly) national and international companies. He has 180 published works, among Journal papers, Conference papers, books, book chapters and patents. He was the General Chair of the 2015 SBMO/IEEE MTT-S International Microwave and Optoelectronic Conference. He is IEEE senior member since 2020 and IEEE MTT-S Chapter Chair - Bahia Section. He will be Co-Chair of 2023 SBMO/IEEE MTT-S International Microwave and Optoelectronic Conference which will take place in Barcelona (already approved by SBMO). His present research interests include the design and fabrication of coplanar structures in microwave frequencies, like resonator, power divider, filter, delay line, instantaneous frequency 80 measurement systems, microsatellites, neural network, measurement of dielectric properties of novel materials for microwave applications, frequency selective surface, micromachined technique and also terahertz device applications.