Research On The Microwave Dielectric Properties Of Modified CaTiO₃-La(Ga_0.5Al_0.5)O₃ Ceramics And Their Antennas

With the rapid development of communication technology, communication equipment is required strictly, such as miniaturization, high performance. Therefore, In terms of the low loss, the miniaturization, and the good mechanical performance, the microwave dielectric materials applied to microwave devices had been widely used or have good prospects for development, such as waveguide, dielectric resonator antenna, coaxial dielectric filters, dielectric substrate of antenna. Based on the research object of CaTiO3-La(Ga0.5Al0.5)O3 ceramics, which possess the mediate electric constant and high quality factor, by using the traditional solid-reaction method, the microstructure and microwave dielectric properties of CaTiO3-La(Ga0.5Al0.5)O3 substituted A-site La by Nd3+ were discussed in detail. Since Nd3+(r = 1.27 ?, ? = 5.01 ?3) is similar to La3+(r = 1.31 ?, ? = 6.07 ?3) whether in the ionic radius or dielectric polarizablity, partial substitution of La3+ by Nd3+ in CaTiO3-La(Ga0.5Al0.5)O3 may obtain a series of excellent microwave dielectric materials with good microwave dielectric properties. Considering the business practical material(dielectric constant ?r ? 45, resonance temperature coefficient ?f ? ±10 ppm/oC), the range of 0.33 ? x ? 0.37, 0 ? ? ? 0.5 in(1-x)CaTiO3-x(La1-?Nd?)(Ga0.5Al0.5)O3 will be focused on, almost all samples presented good microwave dielectric properties: 33,448 GHz ? Q × f ? 49,466 GHz, 43 ? ?r ? 46.1,-0.7 ppm/°C? ?f ?-12 ppm/°C.In addition, based on the developed modified CaTiO3-LaGaO3 materials with high quality factor and mediate dielectric constant, by using the electro-magnetic simulation software HFSS and CST, it was designed two antenna respectively, two antenna respectively are circularly polarized microstrip patch antenna and dual frequency dielectric resonator antenna. First of all, the basic theory of antenna was introduced, including the electrical parameters of the antenna, the features of circular polarized antenna. Then, After introducing the basic theory of microstrip antenna, including the radiation mechanism, the analysis method, the feeding method of the microstrip patch antenna, the antenna, which was circularly polarized microstrip patch antenna, was applied to GPS(1.575 GHz), the circular polarization was realized by using the traditional single feed and corner cutting method, the simulation results showed that the antenna had a good matching impedance at 1.575 GHz, its impedance bandwidth was 15.9 MHz, its axis ratio was 0.64 dB, its axis ratio bandwidth 4 MHz, its max gain 0.046 dB. Finally, After introducing the dielectric resonator antenna's basic, including working principle, the frequency characteristics, feed and model of the cylindrical dielectric resonator antenna, the dual frequency dielectric resonator antenna was designed at PCS(1.9 GHz) and WLAN(2.45 GHz), which worked at 1.9 GHz and 2.45 GHz. The final simulated results showed that the antenna had good impedance matching, its impedance bandwidth is 62 and 38 MHz respectively, its max gain is 6.17 and 2.35 dB respectively.