Validation of a Low-Cost Open-Ended Coaxial Probe Setup for Broadband Permittivity Measurements up to 6 GHz

This work presents the validation of a low-cost measurement system based on an open-ended coaxial SMA (SubMiniature version A) probe for the characterization of complex permittivity in the microwave frequency range. The system combines a custom-fabricated probe, a vector network analyzer, and a dedi...

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Main Authors: Julia Arias-Rodríguez, Raúl Moreno-Merín, Andrea Martínez-Lozano, Germán Torregrosa-Penalva, Ernesto Ávila-Navarro
Format: Article
Language:English
Published: MDPI AG 2025-06-01
Series:Sensors
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Online Access:https://www.mdpi.com/1424-8220/25/13/3935
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author Julia Arias-Rodríguez
Raúl Moreno-Merín
Andrea Martínez-Lozano
Germán Torregrosa-Penalva
Ernesto Ávila-Navarro
author_facet Julia Arias-Rodríguez
Raúl Moreno-Merín
Andrea Martínez-Lozano
Germán Torregrosa-Penalva
Ernesto Ávila-Navarro
author_sort Julia Arias-Rodríguez
collection DOAJ
description This work presents the validation of a low-cost measurement system based on an open-ended coaxial SMA (SubMiniature version A) probe for the characterization of complex permittivity in the microwave frequency range. The system combines a custom-fabricated probe, a vector network analyzer, and a dedicated software application that implements three analytical models: capacitive, radiation, and virtual transmission line models. A comprehensive experimental campaign was carried out involving pure polar liquids, saline solutions, and biological tissues, with the measurements compared against those obtained using a high-precision commercial probe. The results confirm that the proposed system is capable of delivering accurate and reproducible permittivity values up to at least 6 GHz. Among the implemented models, the radiation model demonstrated the best overall performance, particularly in biological samples. Additionally, reproducibility tests with three independently assembled SMA probes showed normalized deviations below 3%, confirming the robustness of the design. These results demonstrate that the proposed system constitutes a viable alternative for cost-sensitive applications requiring portable or scalable microwave dielectric characterization.
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institution Kabale University
issn 1424-8220
language English
publishDate 2025-06-01
publisher MDPI AG
record_format Article
series Sensors
spelling doaj-art-ea35446a47bc4a0bb301682bcfa757e62025-08-20T03:29:02ZengMDPI AGSensors1424-82202025-06-012513393510.3390/s25133935Validation of a Low-Cost Open-Ended Coaxial Probe Setup for Broadband Permittivity Measurements up to 6 GHzJulia Arias-Rodríguez0Raúl Moreno-Merín1Andrea Martínez-Lozano2Germán Torregrosa-Penalva3Ernesto Ávila-Navarro4Elche Microwave Laboratory (EMwLab), Engineering Research Institute of Elche (I3E), Miguel Hernández University of Elche, 03202 Elche, SpainElche Microwave Laboratory (EMwLab), Engineering Research Institute of Elche (I3E), Miguel Hernández University of Elche, 03202 Elche, SpainElche Microwave Laboratory (EMwLab), Engineering Research Institute of Elche (I3E), Miguel Hernández University of Elche, 03202 Elche, SpainElche Microwave Laboratory (EMwLab), Engineering Research Institute of Elche (I3E), Miguel Hernández University of Elche, 03202 Elche, SpainElche Microwave Laboratory (EMwLab), Engineering Research Institute of Elche (I3E), Miguel Hernández University of Elche, 03202 Elche, SpainThis work presents the validation of a low-cost measurement system based on an open-ended coaxial SMA (SubMiniature version A) probe for the characterization of complex permittivity in the microwave frequency range. The system combines a custom-fabricated probe, a vector network analyzer, and a dedicated software application that implements three analytical models: capacitive, radiation, and virtual transmission line models. A comprehensive experimental campaign was carried out involving pure polar liquids, saline solutions, and biological tissues, with the measurements compared against those obtained using a high-precision commercial probe. The results confirm that the proposed system is capable of delivering accurate and reproducible permittivity values up to at least 6 GHz. Among the implemented models, the radiation model demonstrated the best overall performance, particularly in biological samples. Additionally, reproducibility tests with three independently assembled SMA probes showed normalized deviations below 3%, confirming the robustness of the design. These results demonstrate that the proposed system constitutes a viable alternative for cost-sensitive applications requiring portable or scalable microwave dielectric characterization.https://www.mdpi.com/1424-8220/25/13/3935complex permittivityopen-ended coaxial probelow-cost systemSMA-based dielectric sensormicrowave measurementdielectric spectroscopy
spellingShingle Julia Arias-Rodríguez
Raúl Moreno-Merín
Andrea Martínez-Lozano
Germán Torregrosa-Penalva
Ernesto Ávila-Navarro
Validation of a Low-Cost Open-Ended Coaxial Probe Setup for Broadband Permittivity Measurements up to 6 GHz
Sensors
complex permittivity
open-ended coaxial probe
low-cost system
SMA-based dielectric sensor
microwave measurement
dielectric spectroscopy
title Validation of a Low-Cost Open-Ended Coaxial Probe Setup for Broadband Permittivity Measurements up to 6 GHz
title_full Validation of a Low-Cost Open-Ended Coaxial Probe Setup for Broadband Permittivity Measurements up to 6 GHz
title_fullStr Validation of a Low-Cost Open-Ended Coaxial Probe Setup for Broadband Permittivity Measurements up to 6 GHz
title_full_unstemmed Validation of a Low-Cost Open-Ended Coaxial Probe Setup for Broadband Permittivity Measurements up to 6 GHz
title_short Validation of a Low-Cost Open-Ended Coaxial Probe Setup for Broadband Permittivity Measurements up to 6 GHz
title_sort validation of a low cost open ended coaxial probe setup for broadband permittivity measurements up to 6 ghz
topic complex permittivity
open-ended coaxial probe
low-cost system
SMA-based dielectric sensor
microwave measurement
dielectric spectroscopy
url https://www.mdpi.com/1424-8220/25/13/3935
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