| Summary: | 碩士 === 國立雲林科技大學 === 電機工程系 === 104 === Since microwave dielectric materials may have a great effect on the characteristics of high-frequency circuit components, how to accurately grasp their electromagnetic parameters has become very important in high-frequency circuit design. In this study, microstrip resonant methods, including the straight-ribbon resonator method and T-resonator method, were employed to measure the dielectric constants of dielectric materials. Because some undesired unknowns are present in the theoretical formulas of microstrip resonant methods, it is difficult to determine the dielectric constant if only one resonant structure is considered. In order to overcome this problem, we considered two resonators with different lengths, and measured the transmission coefficients of the structures. From the transmission-coefficient curves, we can determine the resonant frequencies, from which the permittivity of the microwave material under study can then be calculated using available theoretical formulas. Finally, results obtained using microstrip resonant methods were compared with those extracted using the open-ended coaxial probe method. For validation, sampled materials with known dielectric constants, such as FR4, bakelite, and glass, were adopted in the measurement.
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