| Summary: | 碩士 === 龍華科技大學 === 電機工程系碩士班 === 100 === In this study, improvement of microwave dielectric properties of La(Mg0.5Sn0.5)O3 were investigated. La(Mg0.5Sn0.5)O3 ceramics were synthesized and some of the La3+ ions were substituted by Yb3+, Sm3+, Bi3+, and B2+ ions to improve their Q f. Since La0.97Sm0.03(Mg0.5Sn0.5)O3 ceramics had a relatively high temperature coefficient of resonant frequency, an investigation involved tailoring the temperature coefficient of resonant frequency of La0.97Sm0.03(Mg0.5Sn0.5)O3 ceramics by combining Ca0.8Sm0.4/3TiO3. B2O3 was added to reduce the sintering temperature of 0.45La0.97Sm0.03(Mg0.5Sn0.5)O3-0.55Ca0.8Sm0.4/3TiO3 ceramics. The 2 wt.% B2O3-doped 0.45La0.97Sm0.03(Mg0.5Sn0.5)O3-0.55Ca0.8Sm0.4/3TiO3 ceramic sintered at 1450 OC for 4 h had a dielectric constant of 35.5, a Q f of 5,500 GHz, and a temperature coefficient of resonant frequency of -1.2 ppm/℃. The La2Sn2O7 ceramic sintered at 1580 OC for 34 h had a dielectric constant of 14.4, a Q f of 40,500 GHz, and a temperature coefficient of resonant frequency of -54 ppm/℃.
In the design of CPW Fed chip antenna. Use La0.97Sm0.03(Mg0.5Sn0.5)O3 ceramic substrate to achieve miniature CPW feed chip antenna. Bandwidth of 35.16 %( 2.21 GHz ~3.11 GHz ). The radiation patterns are near omni-directional in the x-z plane. The radiation patterns are near dipole in the y-z plane. In x-z plane, has a maximum gain of 0.66 dBi, in y-z plane, has a maximum gain of 3.38 dBi.
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