Dielectric Properties Characterization of Material Under Test using Microstrip Ring Resonator

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The Resonator is one of the techniques widely used to determine the dielectric properties of a material. It is due to the accuracy of the resonator technique as compared to the other methods such as open wave guide sensor, transmission method, and coaxial probe. The accuracy plays an important role in any measurement devices as this is one of the features to show that the device is competent enough to perform a specific task. So, as to cope with accuracy issues, two microstrip ring resonators were designed and prototyped to detect the dielectric properties of Material Under Test (MUT) in this study. Both utilize Rogers Duroid 4003C as the substrate for the dielectric sensor and is meant to resonate at 4 and 5 GHz in which the substrate possesses 3.38 dielectric properties and 0.0027 loss tangent. Several features in designing the resonator such as the coupling gap, d, and radius of the ring, R were taken into consideration. Those parameters were verified and validated through software simulation and measurement using Vector Network Analyzer (VNA) to achieve the expected sensor prototype to operate in the real environment. The measurement was made to test two known dielectric properties of MUT to demonstrate the sensitivity of the sensors. The outcome from the measurement was evaluated in terms of S-21 parameter. The dielectric measurement leads to a change in frequency response against different MUT. The measurement was extended to study the performance of the resonator through the R and d of the resonator in which these parametric studies were made by varying the R and d of the resonator with the presence and the absence of MUT. The outcomes from the measurement suggest the best R and d for the resonator in terms of dielectric permittivity.