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Open AccessArticle

Free-Space Materials Characterization by Reflection and Transmission Measurements using Frequency-by-Frequency and Multi-Frequency Algorithms

1
Department of Electrical Engineering, Federal University of Minas Gerais, Belo Horizonte 31270-901, Brazil
2
Pitágoras Faculty, Belo Horizonte 31210-800, Brazil
3
Department of Engineering, University of Campania “Luigi Vanvitelli”, 81031 Aversa, Italy
*
Author to whom correspondence should be addressed.
Electronics 2018, 7(10), 260; https://doi.org/10.3390/electronics7100260
Received: 12 September 2018 / Revised: 10 October 2018 / Accepted: 12 October 2018 / Published: 18 October 2018
(This article belongs to the Special Issue Microwave Imaging and Its Application)
The knowledge of the electromagnetic constitutive properties of materials is crucial in many applications. Free-space methods are widely used for this purpose, despite their inherent practical difficulties. This paper describes an affordable free-space experimental setup for the characterization of flat samples in 1–6 GHz in a non-anechoic environment. The extracted properties are obtained from the calibrated Scattering Parameters, using a frequency-by-frequency solution or a multi-frequency reconstruction. For the first, we describe how the Time-Domain Gating can be implemented and used for filtering the signals. For the latter, a weighting factor is introduced to balance the reflection and transmission data, allowing one to have a more favorable configuration. The different role of transmission and reflection measurements on the achievable results is analyzed with regard to experimental uncertainties and different noise scenarios. Results from the two strategies are analyzed and compared. Good agreement between simulation, measurement and literature is obtained. According to the reported results for dielectric materials, there is no need of filtering the data by a Time-Domain Gating in case of the multi-frequency approach. Experimental results for Polymethylmethacrylate (PMMA) and Polytetrafluorethylene (PTFE) samples validate both the setup and the processing. View Full-Text
Keywords: conductivity; extraction algorithms; free-space calibration; free-space method; scattering parameters; time-domain gating; material characterization; non-destructive testing; permeability; permittivity conductivity; extraction algorithms; free-space calibration; free-space method; scattering parameters; time-domain gating; material characterization; non-destructive testing; permeability; permittivity
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MDPI and ACS Style

Gonçalves, F.J.F.; Pinto, A.G.M.; Mesquita, R.C.; Silva, E.J.; Brancaccio, A. Free-Space Materials Characterization by Reflection and Transmission Measurements using Frequency-by-Frequency and Multi-Frequency Algorithms. Electronics 2018, 7, 260. https://doi.org/10.3390/electronics7100260

AMA Style

Gonçalves FJF, Pinto AGM, Mesquita RC, Silva EJ, Brancaccio A. Free-Space Materials Characterization by Reflection and Transmission Measurements using Frequency-by-Frequency and Multi-Frequency Algorithms. Electronics. 2018; 7(10):260. https://doi.org/10.3390/electronics7100260

Chicago/Turabian Style

Gonçalves, Fábio J.F.; Pinto, Alfred G.M.; Mesquita, Renato C.; Silva, Elson J.; Brancaccio, Adriana. 2018. "Free-Space Materials Characterization by Reflection and Transmission Measurements using Frequency-by-Frequency and Multi-Frequency Algorithms" Electronics 7, no. 10: 260. https://doi.org/10.3390/electronics7100260

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