| Summary: | 博士 === 國立成功大學 === 電機工程學系碩博士班 === 91 === Microwave dielectric resonators which are fabricated by high dielectric constant, low dielectric loss and good temperature stability of microwave dielectric materials are suitably applied in microwave filters, oscillators, antennas and microwave integral circuits (MICs). With the recent progress of microwave communication devices, miniaturization of microwave components for volume efficiency is a major research requirement. For the miniaturized multilayer ceramic filters, reduce the sintering temperature has become the important tendency to researched dielectric materials. In addition, the integration of dielectric materials are also become main studied for implement microwave devices. As mentioned above, the main research of this dissertation is divided three parts which preparation of low sintering temperature microwave dielectric resonators, fabrication of dielectric thin films and their applications on microwave planar filters.
1.Preparation for microwave dielectric resonator with high quality factor (Q×f), excellent temperature stability and high dielectric constant:
[ a ] Zirconium tin titanium oxide was investigated as a potentially useful dielectric material owing to its excellent dielectric properties. Properties improvement and reduce the sintering temperature of Zr0.8Sn0.2TiO4 dielectric materials have been achieved by amount various additions. The experimental results showed that small amount of additions attribute to sintering and grain growth.
[ b ] For producing miniaturized devices, multilayer structures with low sintering temperatures are needed to co-fire with low melting point electrodes. Using low melting dopants are generally the most effective and least expensive technique to reduce the sintering temperature. Since CuO and Fe2O3 are the popular sintering fluxes, these were chosen as a sintering aid to lower the firing temperature of the MgNb2O6 ceramics in this experiment. The microwave dielectric properties and the microstructures of CuO-doped and Fe2O3-doped MgNb2O6 ceramics were also investigated.
2.Fabrication of Dielectric Thin Films:
Due to thin-film technology has become a major requirement for integration since integrated circuits have been applied in today’s microwave communication system and dynamic random access memories. In this part, the electrical and physical properties of ZnO-doped (Zr0.8Sn0.2)TiO4 thin films were fabricated by rf magnetron sputtering have been researched. A ZST target was prepared and used for deposition. ZST thin films were deposited at different processing parameters. The dependence of the physical and electrical characteristics on rf power, substrate temperature and Ar/O2 ratios were also investigated.
3.Design and Fabrication of Microwave Filters:
Microwave planar filters are widely used in the communication circuits. In this part, analysis, design and fabrication of microwave hairpin planar filter were studied. The results of the first part are applied to constructed hairpin band-pass filter. The band-pass filter were constructed by using λ/2 microstrip resonators. Both mixed-coupling and cross-coupling structures were designed as the coupling instruments in the transformation electromagnetic energy. In addition, the coupled lines at the ends of a miniaturized hairpin resonator are used as a capacitor for the purpose of reducing its size. The compact hairpin filters are also implemented and characteristics compared with normal hairpin filters were also investigated in different substrate materials.
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