Transmission-Mode Phase-Variation Sensor Based on Weakly Coupled Distributed Resonators and Phase Detector for High-Sensitivity Applications
Canalias Ferreros, Xavier (Universitat Autònoma de Barcelona. Departament d'Enginyeria Electrònica)
Vélez, Paris (Universitat Autònoma de Barcelona. Departament d'Enginyeria Electrònica)
Casacuberta, Pau (Universitat Autònoma de Barcelona. Departament d'Enginyeria Electrònica)
Su, Lijuan (Universitat Autònoma de Barcelona. Departament d'Enginyeria Electrònica)
Kurniawati, Nazmia (Universitat Autònoma de Barcelona. Departament d'Enginyeria Electrònica)
Martín, Ferran (Universitat Autònoma de Barcelona. Departament d'Enginyeria Electrònica)

Date:	2025
Abstract:	This letter presents a highly sensitive single-frequency permittivity sensor based on a pair of weakly coupled quarter-wavelength resonators. The sensor is a two-port structure operating in transmission, with the pair of coupled resonators shunt connected to the host line, and the output variable is the phase of the transmission coefficient at the operating frequency, i. e. , the pole frequency. The maximum sensitivity of the reported prototype is Smax = -593. 5° per dielectric constant, and the figure of merit, or ratio between the maximum sensitivity and the area of the sensing region expressed in terms of the squared wavelength, is FoM = 25 917°/λ2, which is a very competitive value. By operating in transmission, the main advantage of the proposed sensor over reflective-mode phase-variation sensors based on coupled resonators is the separation of the input (feeding) signal and the output (transmitted) signal at different ports. This facilitates retrieving the phase information in a real scenario, i. e. , without the use of a vector network analyzer. Specifically, a phase detector for that purpose is considered in this letter. Sensor validation is carried out by detecting tiny defects (small holes) in samples and the presence of minuscule perturbations (small strips of polyethylene terephthalate) in the sensing region.
Grants:	Agencia Estatal de Investigación PID2022-139181OB-I00 Agencia Estatal de Investigación PREP2022-000364 Agencia Estatal de Investigación RYC2022-035819-I Ministerio de Ciencia, Innovación y Universidades FPU20/05700 Generalitat de Catalunya 2021/SGR-00192 Generalitat de Catalunya 2024/ICREA-00114
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Language:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Subject:	Coupled lines ; Microwave sensor ; Permittivity sensor ; Phase-variation sensor
Published in:	IEEE sensors letters, Vol. 9, Num. 10 (October 2025) , art. 3505604, ISSN 2475-1472

DOI: 10.1109/LSENS.2025.3609453

Available from: 2027-12-30 Postprint 4 p, 664.9 KB

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Research literature > UAB research groups literature > Research Centres and Groups (research output) > Engineering > CIMITEC-UAB
Articles > Research articles
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