Based Communication System Of The Spiral Filter

The filters are very important components in modern microwave communication systems. The performance of the filters impact the capability of the whole microwave communication systems. As the information techniques developing rapidly, the microwave communication frequency resource are becoming more and more precious and crowded. It has made a more rigorous technical requirement in the microwave filters design. The key technical requirement is developing the filters with small size, high selectivity, low loss and low cost in a short period of time, which promotes the deeper research in microwave filters.Neither LC filters, waveguide filters nor coaxial filters are suitable for the frequency range from 100MHz to 1500MHz, but using helical filters are able to avoid the weakness of the structures above. This paper designed a helical filter, and summarized a new method of calculating the couple coefficient, analyzed the couple coefficient between helical resonators in different topologic configuration, and improved the matrix coefficient of the filters by plugging cross-coupling.Nowadays, the accuracy and efficiency of the electromagnetic analysis software are improved quickly as the fast development of the computer technology and the microwave CAD. It improves that the method of using electromagnetic simulation soft to design helical filters is feasible, and the method can also reduce researching time and cost.The main content of this paper includes: summarized the principle of helical filters design, founded the equivalent circuit of helical resonators and calculated the couple coefficient, analyzed the rule of couple coefficient between different position of helix in resonators, and designed a helical filter and realized it; investigated the power capacity in cavity filter and figuring out the power capacity in the helical filter designed.