The Design Of Coaxial Dielectric Filters And Fabrication With Roll Forming Technology

With the rapid development of wireless communication technology in the world today, the requirements for the performances of microwave filters are getting stricter and stricter. In addition, requirements for the size and quality of microwave devices have also been put forward because of the development of mobile portable terminal miniaturization. Above all, the dielectric filter with high Q value, low insertion loss, small size and high temperature stability is a meaningful research topic.At first, 3 order band-pass filter(center frequency f0=2618MHz, bandwidth BW3 dB =44.9MHz ? insertion loss IL<1dB) and 4 order band-pass filter(center frequency f0=2632MHz, bandwidth BW3 dB =69.9MHz?insertion loss IL<1.5dB) were designed through the simulation software by the network synthesis design method.In the following, the low-temperature sintering of(Mg0.95Ca0.05)0.9Zn0.1TiO3 ceramics was investigated. The(Mg0.95Ca0.05)0.9Zn0.1TiO3 ceramics doped with different amounts of ZnO-B2O3 glass were sintered at different temperature. The effects of ZnO-B2O3 glass addition and sintering temperature on microstructures and microwave dielectric properties were discussed. The ceramics sintered at low temperature was achieved and the optimal microwave dielectric properties(?r = 19.5, Q×f = 62,100 GHz at 6.8 GHz and ?f =-13 ppm/°C) were obtained for(Mg0.95Ca0.05)0.9Zn0.1TiO3 ceramics doped with 5 wt% ZnO-B2O3 glass sintered at 1075 °C.Finally, the paper presented the roll forming used in preparation of filters for the advantages and disadvantages of the traditional molding process for coaxial dielectric filter. In the experiments, the(Mg0.95Ca0.05)0.9Zn0.1TiO3 ceramics with excellent dielectric properties were chosen for the preparation of filter. The ceramic membranes were prepared by the roll forming process. Then ceramic membranes were laminated in orders to impacting into ceramic bodies by hot pressing. The ceramic bodies were processed by cutting and punching, sintering, silver plating and electrode making to make filter samples.