Research And Design Of A Coaxial Cavity Bandpass Filter

As an important microwave component, coaxial cavity band-pass filter has recently been vigorously developed and it has a big power capacity, low insertion loss, parasitic pass faraway and so on. And now it has been widely used in wireless communications fields. Therefore, studies of microwave filters have attracted the device engineer deeply at home and abroad. A coaxial cavity band-pass filter has been studied in this paper. We use new cross coupling structure on the edge to achieve the design of high isolation. With Using HFSS and Microwave Office software to co-simulate, we make the overall simulation and optimization, based on the entire design of the coaxial cavity band-pass filter.The application of co-simulation methods have great improved the design efficiency and reduced the production cycle cost, especially for those complex filters. In the communication frequency ranges, the design model has these features:small dimension, wide pass band, high-band rejection, low insertion loss, which make it important in the field of wireless communications development. In this research process, which mainly include the following aspects:1. From the basic concept of the filter, we learn and study the feature, specifications classification, and process from low-pass filter prototype to band-pass filter design.2. On the basis of cavity coupling theory, we have studied some kinds of coupling structure and simulation of coupling coefficient, analyzed the cross-coupling phase model, so as to draw filter design ideas from the actual design of the coupling structure with desired transmission zeros.3. Passive inter-modulation has always been difficult for the passive components. And this paper includes a systematic analysis of passive inter-modulation for the band-pass filter. This process will be a certain guiding role in the future manufacturing. 4. According to the design specifications, the design process includes band-pass filter topology, coupling coefficient and resonator frequency which has been easily gained by computer-aided software (couple-filter). In the help of Microwave Office and HFSS, this filter model has been simulated and optimized. This designed filter of geometric size and specification meets the requirements well. The results proved the feasibility of this approach and practicality.