Portable Reflective-Mode Phase-Variation Microwave Sensor Based on a Rat-Race Coupler Pair and Gain/Phase Detector for Dielectric Characterization
Vélez Rasero, Paris (Universitat Autònoma de Barcelona. Departament d'Enginyeria Electrònica)
Paredes, Ferran (Universitat Autònoma de Barcelona. Departament d'Enginyeria Electrònica)
Casacuberta Orta, Pau (Universitat Autònoma de Barcelona. Departament d'Enginyeria Electrònica)
Elgeziry, Mahmoud (Università di Pisa. Dipartimento di Ingegneria dell'Informazione)
Su, Lijuan (Universitat Autònoma de Barcelona. Departament d'Enginyeria Electrònica)
Muñoz Enano, Jonathan (Universitat Autònoma de Barcelona. Departament d'Enginyeria Electrònica)
Costa, Filippo (Università di Pisa. Dipartimento di Ingegneria dell'Informazione)
Genovesi, Simone (Università di Pisa. Dipartimento di Ingegneria dell'Informazione)
Martín, Ferran (Universitat Autònoma de Barcelona. Departament d'Enginyeria Electrònica)

Date:	2023
Abstract:	This article presents a low-cost and portable phase-variation planar microwave sensor operating in reflective mode, where the output variable, the phase of the reflection coefficient of the one-port sensing element, is retrieved by means of a distributed circuit based on a pair of rat-race hybrid couplers and the associated electronics. This includes a microcontroller, a voltage controlled oscillator (VCO), a digital-to-analog converter (DAC), and an RF/microwave gain/phase detector. By this means, vector network analyzers (VNAs), i. e. , high-cost instruments typically used for obtaining the reflection coefficient in one-port structures or circulators (microwave components able to separate the injected signal from the reflected signal in any one-port network) are avoided. Indeed, the presented architecture (including the microwave rat-race hybrid configuration and the associated electronics) can be adapted to other one-port reflective-mode phase-variation microwave sensors. A prototype example, where the sensing element is a one-port step-impedance open-ended transmission line, is reported. The device provides the phase of the reflection coefficient of the sensing element as a function of the dielectric constant of the material under test (MUT) with a maximum sensitivity of −65. 7° and a relative error of less than 8% in all the measurements.
Grants:	Agencia Estatal de Investigación PID2019-103904RB-I00 Agencia Estatal de Investigación PDC2021-121085-I00 Agència de Gestió d'Ajuts Universitaris i de Recerca 2017/SGR-1159 Agencia Estatal de Investigación FPU20/05700 Agencia Estatal de Investigación IJC2019-040786-I
Note:	Altres ajuts: Institució Catalana de Recerca i Estudis Avançats
Rights:	Tots els drets reservats.
Language:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Subject:	Hybrid coupler ; Microstrip technology ; Microwave sensor ; Permittivity sensor ; Phase detector ; Phase-variation sensor ; Reflective-mode sensor
Published in:	IEEE sensors journal, Vol. 23, Issue 6 (March 2023) , p. 5745-5756, ISSN 1530-437X

DOI: 10.1109/JSEN.2023.3240771

Available from: 2025-03-31 Postprint

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