Substrate-Integrated Waveguide Microwave Sensor for Water-in-Diesel Fuel Applications
A water-in-diesel microwave sensor based on a substrate integrated waveguide (SIW) microwave applicator is designed and characterized in this study. The interaction between the microwave electromagnetic field and the diesel fuel contaminated with small concentrations of water is obtained via suitabl...
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| Main Authors: | , , , , , , , |
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| Format: | article |
| Language: | EN |
| Published: |
MDPI AG
2021
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| Subjects: | |
| Online Access: | https://doaj.org/article/bf8f2dd3b4cd4769974c6ae3ed797a9a |
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| Summary: | A water-in-diesel microwave sensor based on a substrate integrated waveguide (SIW) microwave applicator is designed and characterized in this study. The interaction between the microwave electromagnetic field and the diesel fuel contaminated with small concentrations of water is obtained via suitable radiating slots placed on the top of an SIW waveguiding structure. The SIW applicator working frequency is chosen by observing the behavior of the complex dielectric permittivity of the fuel–water blend based on a preliminary wide band investigation. The performances of the SIW microwave sensor are evaluated in terms of scattering parameter modulus <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mrow><mo>|</mo><mrow><msub><mi>S</mi><mrow><mn>21</mn></mrow></msub></mrow><mo>|</mo></mrow></mrow></semantics></math></inline-formula> as a function of the water concentration in ppm. The best sensitivity <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mfrac><mrow><mi mathvariant="sans-serif">Δ</mi><mrow><mo>|</mo><mrow><msub><mi>S</mi><mrow><mn>21</mn></mrow></msub></mrow><mo>|</mo></mrow></mrow><mrow><mi mathvariant="sans-serif">Δ</mi><mi>ρ</mi></mrow></mfrac><mo>=</mo><mn>1.42</mn><mo> </mo><mi>mdB</mi><mo>/</mo><mi>ppm</mi></mrow></semantics></math></inline-formula> is obtained at a frequency of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>f</mi><mo>=</mo><mn>9.76</mn><mo> </mo><mi>GHz</mi></mrow></semantics></math></inline-formula>, with a coefficient of determination <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msup><mi>R</mi><mn>2</mn></msup><mo>=</mo><mn>0.94</mn></mrow></semantics></math></inline-formula>. The sensor is low-cost, low profile and ensures a good sensitivity for constant and real-time monitoring. |
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