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" Numerical analysis of a conical type coaxial open-ended probe for dielectric measurement "
Homa Arab Salmanabadi
Akyel, Cevdet; Conan, Jean
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Latin Dissertation
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| Language of Document
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English
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| Record Number
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804235
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| Doc. No
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TL49057
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| Call number
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1845327564; 10296159
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| Main Entry
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Islam, Mohammed Shahidul
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| Title & Author
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Numerical analysis of a conical type coaxial open-ended probe for dielectric measurement\ Homa Arab SalmanabadiAkyel, Cevdet; Conan, Jean
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| College
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Ecole Polytechnique, Montreal (Canada)
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| Date
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2014
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| Degree
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M.Sc.A.
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2014
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| Page No
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90
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| Note
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Place of publication: United States, Ann Arbor; ISBN=978-1-369-39367-5
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| Abstract
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The main objective of this research is to find an accurate model for computing the di- electric constant and the loss factor of a homogeneous dielectric material from a measured reflection coefficient by using conical-type coaxial probe in radio and microwave frequencies. This sort of probe can be easily inserted into a wide range of biological tissue types and semi-rigid materials like rubber, some plastics, and organic materials (e.g., dairy, butter, etc.) for measuring moisture content. This feature is very important in biological and industrial applications. The measuring principle is based on detecting capacitance change with respect to the dielectric mass movement in the fringe electrical field. The electrical input admittance as well as the reflection coefficient are found from the finite-element analysis. In contrast to many other modelling techniques used for coaxial probe which are approximate and hence limited, the finite-element model is more accurate and is applicable to complicated geometries. To demonstrate the accuracy of the numerical model, a parallel experimental study was carried out in the laboratory in the same geometric dimensions. The numerical and experimental results are compared and showed an excellent agreement, demonstrating that finite-element modelling is a good approach for optimized conical coaxial probe design. A three-dimensional finite-element formulation is employed in the dielectric material region and a small neighbouring region of the probe structure on which it is mounted. The reflection coefficient factor, electromagnetic field at the probe aperture and permittivity of different materials were analyzed in the frequency range of 300 MHz to 3 GHz. Moreover, a comparative study of three conical open-ended coaxial probe models (capacitive model, antenna model, improved virtual line model) which relate the reflection coefficient to the complex permittivity of the Material Under Test (MUT) is presented. In addition, the effects of the cone angle and shape of the coaxial cable ( at-conical-elliptical) are studied and evaluated in detail in this research. It is shown that for designing an efficient and operational dielectric measurement probe, an accurate and computationally efficient method with rigorous validation and reduced computational burden is required.
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| Subject
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Electrical engineering
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| Descriptor
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Applied sciences
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| Added Entry
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Akyel, Cevdet; Conan, Jean
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Ecole Polytechnique, Montreal (Canada)
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