| 摘要 |
PROBLEM TO BE SOLVED: To provide a first stage coupling method by which the variable range of the coupling quantity of the electromagnetic coupling of a filter device is wide, adjustment is easy and a manufacturing cost can be reduced. SOLUTION: A U-shaped or J-shaped coupled antenna 13 is used for a first stage resonant pole 15 of the filter device 10 composed of a semi-coaxial resonator 14 to electromagnetically couple an input high frequency signal. An input terminal 11 is connected to one end part of a straight section of the coupled antenna 13, and the other straight section is parallelly provided adjacently to the resonant pole 15. An adjustment screw 17 for adjusting coupling quantity is screwed from the above into a section in the vicinity of a U-shaped straight section of an end part side connected to the input terminal. The coupled antenna 13 can be formed of a conductor pattern on a printed circuit board. The coupling quantity is adjusted by the insertion quantity of the adjustment screw.
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