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Boxed Ring Resonator for Liquid Dielectric Constant Measurement

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The present study describes a compact and low-cost microstrip based resonant sensor that is specially developed for measurements of dielectric constant for liquid and paste at a frequency of 2.45GHz. The sensor utilizes shielded, boxed microstrip annular ring resonator structure, enabling a simple method to place a sample of liquid to be measured. The Transmission Line Model (TLM) of the multilayer system is successfully developed. The inverse algorithm is used to calculate real (ε’) and imaginary parts (ε”) of the permittivity for the liquid sample with the inputs of the changes in the resonant frequency (fr) and the quality factor (Q). Experimental data is testified against the related theory and compared with the results obtained by other researchers. CST MWS simulation software is used for the optimization of the boxed annular ring and concentric ring resonator structure. The comparison is done for the annular ring and concentric ring resonator boxed structure. Annular ring resonator structure has better accuracy than concentric ring resonator structure. This measurement system indicates high potential towards the development of a portable technique for quality analysis of liquids.
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Microstrip Ring Resonator; Transmission Line Model; Permittivity Measurement; Quality Factor

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