| 摘要 |
This invention is a filter circuit provided in a radio communication module. First to third conductor patterns ( 8 to 10 ) having a length shorter than lambda/4 of a passing wavelength lambda and electromagnetically coupled with each other are formed as distributed line patterns parallel to each other in a dielectric board ( 2 ), and a first capacitor ( 16 ) and a second capacitor ( 17 ) add parallel capacitance to the first conductor pattern ( 8 ) and the second conductor pattern ( 9 ) having their distal ends short-circuited. The third conductor pattern ( 10 ) has its both end opened. As the first conductor pattern ( 8 ) and the second conductor pattern ( 9 ) carry out inductive operation and the third conductor pattern ( 10 ) is capacitive-coupled with these conductor patterns, resonance is made in a band lower than a frequency band prescribed by the length of the lines.
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