| 摘要 |
The invention relates to a bandpass filter comprised of coaxial resonators. On the side of a resonator chain (200) which makes the filter there is provided an additional equalizing resonator (EQ1) which is coupled to a resonator (R3) in the chain. The resonance frequency of the equalizing resonator and the coupling with the rest of the filter are arranged so that attenuation increases at a point corresponding to an original attenuation minimum. Thereby it follows that attenuation variation in the whole pass band decreases. Response equalization can be further enhanced by providing a second equalizer (EQ2) affecting a band beside the first one. Using the structure according to the invention, a decrease of a certain magnitude in the pass band attenuation variation of a bandpass filter can be achieved with a smaller increase in the number of resonators than in known structures. Moreover, the production costs caused by the additional structure are relatively small. <IMAGE> |
