An analytical method to implement high-sensitivity transmission line differential sensors for dielectric constant measurements
Muñoz Enano, Jonathan (Universitat Autònoma de Barcelona. Departament d'Enginyeria Electrònica)
Vélez Rasero, Paris (Universitat Autònoma de Barcelona. Departament d'Enginyeria Electrònica)
Gil Barba, Marta (Universidad Politécnica de Madrid. Departamento de Ingeniería Audiovisual y Comunicaciones)
Martín, Ferran (Martín Antolín) (Universitat Autònoma de Barcelona. Departament d'Enginyeria Electrònica)

Date:	2020
Abstract:	A simple analytical method useful to optimize the sensitivity in differential sensors based on a pair of meandered microstrip lines is presented in this paper. Sensing is based on the phase difference of the transmission coefficients of both lines, when such lines are asymmetrically loaded. The analysis provides the combination of operating frequency and line length (the main design parameters) that are necessary to obtain the maximum possible differential phase (±180°) for a given level of the differential dielectric constant (input dynamic range). The proposed sensor is useful to detect tiny defects of a sample under test (SUT) as compared to a reference (REF) sample. It can also be applied to the measurement of the complex dielectric constant of the SUT, where the real part is inferred from the differential phase, whereas the imaginary part, or the loss tangent, is derived from the modulus of the transmission coefficient of the line loaded with the SUT. It is experimentally demonstrated that the proposed device is able to detect the presence of few and small (purposely generated) defects in a commercial microwave substrate, as well as subtle variations in their density, pointing out the high achieved sensor sensitivity. Sensor validation is also carried out by determining the dielectric constant and loss tangent of commercial microwave substrates.
Grants:	Ministerio de Ciencia e Innovación IJCI-2017-31339 Ministerio de Economía y Competitividad TEC2016-75650-R Agència de Gestió d'Ajuts Universitaris i de Recerca 2018/FI_B_00111 Agència de Gestió d'Ajuts Universitaris i de Recerca 2017/SGR-1159
Rights:	Tots els drets reservats.
Language:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Subject:	Dielectric characterization ; Differential sensors ; Microstrip ; Microwave sensors
Published in:	IEEE sensors journal, Vol. 20, issue 1 (Jan. 2020) , p. 178-184, ISSN 1558-1748

DOI: 10.1109/JSEN.2019.2941050

Postprint 8 p, 846.3 KB

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