REDUCED SIZE CAVITY FILTERS FOR PICO BASE STATIONS

摘要

An improved microwave cavity filter used in cellular communication systems such as base stations is disclosed. The cavity filter has a conductive housing forming a cavity therein and a hollow conductive resonator configured in the cavity with a folded hat shaped upper portion. A tuning screw extends from the top cover of the housing into the top folded hat portion of the hollow resonator to fine tune the resonator. The resonator also may preferably include two different diameter sections providing a first high impedance section with smaller diameter and a second lower impedance section with a larger diameter configured at an upper end of the resonator. This configuration provides a significantly smaller cavity height for a given power handling capability. The resonator is preferably of constant thickness allowing low cost stamping or other forming techniques to be used in forming the resonator.