| Summary: | 碩士 === 國立成功大學 === 電機工程學系碩博士班 === 92 === The microwave properties of La(Mg1/2Ti1/2)O3 dielectric ceramic materials are discussed in this paper. By adding different sintering aids B2O3、ZnO and CuO
respectively, we study the existence effects of liquid phase for the microwave properties of La(Mg1/2Ti1/2)O3. The experiment results show that La(Mg1/2Ti1/2)O3 with 1wt% B2O3 addition can efficiently reduce sintering temperature from 1650 oC to 1425 oC, and we obtain that the dielectric properties are εr~27.9，Q×f~63000(9GHz) and τf~-40(ppm/oC). Concerning about the negative value of τf , we choose adding the CaTiO3(+712(ppm/oC)) to adjust the value approaching to zero. At 1400 oC, 0.5La(Mg1/2Ti1/2)O3-0.5 CaTiO3＋1wt% B2O3 appears the best property: εr~44, Q×f~29000(7GHz) andτf~-8(ppm/oC) . Hence, the microwave properties of La(Mg1/2Ti1/2)O3 dielectric ceramic materials is improved.
In addition, we design and fabricate a third order compact elliptic function low-pass filters using microstrip stepped-impedance hairpin resonators with 2GHz 3dB cutoff frequency on FR4、Al2O3、La(Mg1/2Ti1/2)O3 substrate.
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