Reflective-Mode Phase-Variation Permittivity Sensor Based on a Step-Impedance Microstrip Line Terminated With a Slot Resonator for Solid and Liquid Characterization
Muñoz Enano, Jonathan (Universitat Autònoma de Barcelona. Departament d'Enginyeria Electrònica)
Vélez Rasero, Paris (Universitat Autònoma de Barcelona. Departament d'Enginyeria Electrònica)
Casacuberta Orta, Pau (Universitat Autònoma de Barcelona. Departament d'Enginyeria Electrònica)
Su, Lijuan (Universitat Autònoma de Barcelona. Departament d'Enginyeria Electrònica)
Martín, Ferran (Martín Antolín) (Universitat Autònoma de Barcelona. Departament d'Enginyeria Electrònica)

Data:	2023
Resum:	This article proposes a highly sensitive single-frequency microwave sensor for dielectric characterization of solids and liquids. The sensor is a reflective-mode one-port device consisting of a step-impedance microstrip line terminated with a slot resonator (the sensing element) transversely etched on the ground plane. The working principle of the sensor is the variation experienced by the phase of the reflection coefficient at the operating frequency as a consequence of changes in the dielectric properties (dielectric constant) of the material under test (MUT), either a solid or a liquid, which should be in contact with the slot resonator. A relevant advantage of the reported sensor is the fact that the MUT is located in the back substrate side of the microstrip structure. Therefore, any potential interaction between the MUT, including the mechanic holder used for liquid sensing, and the microstrip line, is prevented. A detailed sensitivity analysis that considers the effects of losses is carried out. It is concluded that, depending on the losses of the MUT, there are two different sensor operation regimes (the low-loss and the high-loss regimes), with unequal behavior, but both are useful to sensitively detect changes in the dielectric properties of the MUT. The maximum sensitivity in the prototype device devoted to the measurement of the dielectric constant in low-loss solid samples is 255. 5 ∘. In the liquid sensor, equipped with a 3-D-printed holder, and focused in this article on the detection of small volume fractions of isopropanol in deionized (DI) water, the maximum sensitivity is 64. 96 ∘ /%.
Ajuts:	Agencia Estatal de Investigación PID2019-103904RB-I00 Agencia Estatal de Investigación PID2022-139181OB-I00 Agencia Estatal de Investigación PDC2021-121085-I00 Agència de Gestió d'Ajuts Universitaris i de Recerca 2021/SGR-00192 Agencia Estatal de Investigación FPU20/05700 Agencia Estatal de Investigación IJC2019-040786-I
Nota:	Altres ajuts: ICREA Academia
Drets:	Tots els drets reservats.
Llengua:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Matèria:	Liquid sensor ; Microstrip ; Microwave sensor ; Phase-variation sensor ; Slot resonator ; Step-impedance transmission line
Publicat a:	IEEE transactions on microwave theory and techniques, (October 2023) , ISSN 0018-9480

DOI: 10.1109/TMTT.2023.3315832

Disponible a partir de: 2024-10-31 Postprint

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