Design Of 1800MHz Microwave Ceramic Dielectric Filter

With the development of the communication technology recent years, the requires of the weight and length of the communication system equipment becomes more important , especially ,to the mobile communication system , the requirement of the filter and duplexer becomes more important. Not only the reliability and less insert loss, but also small volume and high selectivity. Below 1000 MHz , wavelength relatively long. Filter and duplexer use micro-stripe and metal resonator are very difficult to reduce size. SAW filter can reduce the circuit size ,but for the affection of the high power capability and insert loss , application field is restricted. This paper introduce an design method of dielectric filter. This paper briefly introduce the microwave dielectric ceramic materials and the microwave dielectric ceramic device situation. Focus on the information of microwave ceramic dielectric filter. Argue the design principle and method of microwave ceramic dielectric filter , simulate microwave filter using high frequency structure simulate soft to simulate the microwave dielectric filter , design the filter of center frequency is 1800MHz , bandwidth is 45MHz , insert loss less than 2.5dB, ripple in band less the 1.5dB, and restrain at 100MHz at the range 25dB to 45dB. The molding technics of the device was one of the most important step of manufacturing device, especially with the miniaturization and the complication of the device,. the traditional pressing forming cost high and rigorous manufacture was difficult to achieve, then a different kind of technics must be seeked and applied. In this paper, the microwave ceramic (Ba_6-3x(Sm_1-yNd_y)_8+2xTi₁8O₅4)was pitched to the preparation of the device. The Gelcasting technics which applied to the PTC moulding technics was applied to the microwave dielectric ceramic. Moulding the microwave device and compared the technics with the traditional pressing forming, the Gelcasting technics can be used to mould the microwave device. Last using the Gelcasting technics to produce the designed filter, and plating silver to the device sample from out-surface to in-surface according to the design request .