The Design And Simulation Of Microwave Coaxial Dielectric Filter

In recent years,along with the exploitation and application of the high frequency radio wave as well as the rapid development of the mobile communication, dielectric materials with a high relative dielectric constant εr, high Q values and with a low temperature coefficient of resonant frequency have been developed. Low insertion loss, lightweight, low-cost and high performance microwave dielectric filters are widely used in mobile communications and wireless local area network (LAN) systems. The overview of the microwave dielectric ceramic and microwave dielectric ceramic filter were introduced briefly in this paper, The design principle and the design method of the microwave dielectric ceramic filter were described. The structure of the filter was simulated by HFSS(High Frequency Structure Simulator) software and the relationship between structures such as coupling cavity diameter R and properties such as center frequency f0 were discussed in the paper. Based on the Maxwell's equation,the HFSS solves the electric field and magnetic field by using finite element method(FEM). It can shorten design cycle greatly. Through microwave network theory, we analyzed the coupling mechanism and set up the equivalent circuit model to look for theoretical foundation of the relationship between microwave filter structure parameters and its properties. The microwave dielectric ceramic filter was simulated with the HFSS, which has the performance of Center frequency=945 MHz,Insertion loss≤2.5 dB,Bandwidth≥30 MHz,Passband ripple≤0.8dB,Attenuation≥20dB(f0±40MHz). We made the sample of microwave filter by a series of complicate working procedure. Finally, the measured outcome of the filter was compared with the HFSS simulation and the result was analyzed.