近年來，由於通訊科技的快速發展，且介電共振器(DR)又具有可以有效降低微波電路尺寸的優點，使得介電陶瓷材料在微波元件（如：濾波器、震盪器及天線等）的小型化上佔有相當重要的地位。以介電陶瓷材料所製作之介電共振器應用在微波領域中，需具有高介電常數(εr)、高品質因素(Q×f)及接近於零的溫度飄移係數(τf)等特性。針對以上所述，在本論文中將區分為下列之三大部分來進行研究與探討：
一、 開發具有高介電常數、低損失及接近於零之溫度係數的微波陶瓷介電材料：
a. (Mg0.95Ni0.05)TiO3微波陶瓷材料之備製及其介電特性之研究。
b. 混合兩種不同之陶瓷材料，依照不同的比例來研究，嘗試發展出新的陶瓷系統得到接近於零的溫度飄移係數(τf)。
二、 二次相(Mg0.95M2+0.05)Ti2O5 (M2+=Co, Ni, Zn)微波陶瓷材料之備製及其介電特性之研究。
三、以前面所完成之介電陶瓷系統來作為元件的基板材料，來應用在微帶線之濾波器的設計上，希望藉由提升基板的介電常數及降低基板的介電損失，可以得到較小之濾波器尺寸及較好之濾波效果。

With recent progress in microwave communication systems, microwave dielectric ceramics have become increasingly important in the miniaturization of microwave devices such as filters, oscillators, and antennas. The advantage of using dielectric resonators is that they enable the size reduction of microwave components. Requirements for these dielectric ceramics are combined with a high dielectric constant (εr) for possible size miniaturization, a high quality factor (Q×f) for high frequency selectivity and low signal attenuation, and a near-zero temperature coefficient of resonant frequency (τf) for temperature stable circuits. This dissertation includes the study of low-loss microwave dielectric materials, how to combine two or more materials to achieve near-zero temperature coefficient of resonant frequency (τf), and their applications as planar filters at microwave frequencies.
1. Development of a novel microwave ceramic material which has a high dielectric constant, low loss, and a near-zero temperature coefficient:
a. With the partial replacement of Mg by Ni, (Mg0.95Ni0.05)TiO3 ceramics with an ilmenite-type structure were prepared and studied. The dielectric constant values (εr) saturated at 17-17.35. Q×f values of 94,000-188,000 GHz can be obtained with sintering at a temperature in the range of 1300-1350°C for 4 h. The temperature coefficient of resonant frequency (τf) was not sensitive to the sintering temperature. An εr value of 17.35, a Q×f value of 188,000 GHz, and a τf value of -47 ppm/°C were obtained for (Mg0.95Ni0.05)TiO3 ceramics sintered at 1350°C for 4 h.
b. To compensate the temperature coefficient (τf), SrTiO3, CaTiO3, Ca0.6La0.8/3TiO3, Ca0.61Nd0.26TiO3, and Ca0.8Sm0.4/3TiO3, were added to the (Mg0.95Ni0.05)TiO3 ceramic, respectively. The microstructures and the microwave dielectric properties of these ceramic systems were investigated. A Two-phase system was confirmed by XRD patterns.
2. Investigation of the dielectric properties of the second phase (Mg0.95M2+0.05)Ti2O5 (M2+=Co, Ni, Zn) ceramics at microwave frequencies:
In this section, the second phase of (Mg0.95M2+0.05)Ti2O5 (M2+ =Co, Ni, and Zn) in (Mg0.95M2+0.05)TiO3 (M2+ =Co, Ni, and Zn) ceramics were investigated. (Mg0.95M2+0.05)Ti2O5 solid solutions with an orthorhombic structure were detected throughout the entire experiment. The (Mg0.95M2+0.05)Ti2O5 ceramics had the following microwave dielectric properties: εr of 16~18.5, Q×f of 28,000~68,000 GHz, and τf of -38~-47 ppm/°C sintered at 1425-1450°C for 4 h.
3. Design and fabrication of planar filters:
A compact hairpin filter with a 0o feed structure was investigated in this section. Its size can be reduced by using a high permittivity ceramic substrate. The selectivity and stop-band rejection of the designed filters can be significantly improved by utilizing a skew-symmetric (zero degree) feed structure. The responses of the compact hairpin filters using Al2O3 (εr= 9.7, Q × f = 35,000 GHz) and 0.9(Mg0.95Co0.05)TiO3-0.1Ca0.61Nd0.26TiO3 ceramics with 0.25wt% V2O5 (εr = 21.7, Q × f = 58,000 GHz, τf =-10.0 ppm/°C) ceramic substrates were designed to have a center frequency of 2.0 GHz. The compact size, low-loss, sharp response and performance of the filter are presented in this study.

Abstract…Ⅰ
Contents……Ⅶ
Table Captions……………………………Ⅹ
Figure Captions…………………………………XII
Chapter 1 Introduction…………………………1
Chapter 2Theory and Measurements of Dielectric Resonator
2-1 Dielectric Theorem…………………………11
2-2 Measurements of Microwave Dielectric Properties....14
2-3 Applied to Medium for Transmission Lines…19
2-4 Basic Theories of Microwave Filters……20
Chapter 3 Microstructures and Microwave Dielectric Properties of (Mg0.95Ni0.05)TiO3 ceramics
3-1 The replacement of Mg2+ by Ni2+ in MgTiO3…28
3-1-1 Experimental Procedures………29
3-1-2 Characteristics Analysis and Measurement of Microwave Dielectric Properties…………30
3-1-3 Results and Discussions……………33
3-2 Compensation of the Temperature Coefficient in (Mg0.95Ni0.05)TiO3 Ceramics……………………37
3-2-1 Sample Preparation……………………37
3-2-2 Characteristic Analysis and Measurement of Microwave Dielectric Properties……………38
3-2-3 Results and Discussions……………………39
Chapter 4 Investigation of the Dielectric Properties of the Second Phase (Mg0.95M2+0.05)Ti2O5 (M2+=Co, Ni, Zn) Ceramics at Microwave Frequencies
4-1 Experimental Procedures………………………96
4-1-1 Sample Preparation………………………96
4-1-2 Characteristics Analysis and Measurement of Microwave
Dielectric Properties……………………97
4-2 Results and Discussion…………….98
Chapter 5 Cross-Coupled Hairpin Filter Design Using
High-Permittivity Substrates
5-1 Stepped Impedance Resonator (SIR)………113
5-1-1 Basic Structure of SIR…………113
5-1-2 Resonance Conditions and Resonator Electrical Length…...114
5-1-3 Analysis of Filters With Zero Feed Tapping Feed Lines…...115

5-2 Compact Size Filters………118
Chapter 6 Conclusions and Future Works
6-1 Conclusions………………………………………127
6-2 Future Works…………………131
References…………………………………134

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