| 摘要 |
PURPOSE:To eliminate the deterioration in the band charcteristics, due to the resonance frequency of the unnecessary mode closed to that of the basic mode, by arranging a fixed fottom surface of cavity section of a cylindrical cavity resonator in a plane different from that including that of the other resonator. CONSTITUTION:This filter is a four-stage band-pass filter where the position of a fixed bottom of a resonator is changed in response to the coupling of each respnator, and since a resonator 1' of the 1st stage and a resonator 4' of the 4th stage, and a resonator of the 2nd stage and a resonator 3' of the 3rd stage are coupled in the same way, fixed bottom surfaces 1'a and 4'a, and 2'a and 3'a are on the same plane. The distribution of the electric field strength is different at each mode generally and a different coupling is obtained with the different mode even if the position of coupling hole is the same. The resonator fixed bottom is changed for each stage by taking the reduction in the resonance frequency due to coupling at each resonator into consideration, the position of the coupling hole center is arranged to 1/4-1/2 of the cavity height from the fixed bottom surface, and the relative position between both the bottom surfaces of the coupling hole is changed, allowing to improve the deterioration in the band characteristics. |
