| 摘要 |
PURPOSE:To control easily the signal pass characteristics by connecting a variable capacitor to a place near a connecting part between coupling elements of a band-pass filter BPF. CONSTITUTION:A BPF is formed in a cavity space 4 between an input terminal 1 and an output terminal 5 with an inductor 12, a capacitor 13, coupling elements 14 and 15, etc. Then a variable capacitor 16 is connected between an earth conductor 9 and an intermediate partition 3 of a cavity 1. In case the signal band pass characteristics are controlled after the parts are repaired or replaced, a measuring device is connected to an output terminal 7 to change the capacity of the capacitor 16 and to set it at a revolving position where the best characteristics are obtained. Thus it is possible to control quickly the signal pass characteristics.
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