| 摘要 |
PROBLEM TO BE SOLVED: To provide a band-pass filter which has a plurality of resonators and also functions as a directional coupler. SOLUTION: The band-pass filter 10 has an input terminal 1, an output terminal 2, a monitor terminal 3, and an isolated terminal 4. Further, the band-pass filter 10 has a band-pass filter unit which is provided between the input terminal 1 and output terminal 2 because of circuit constitution to function as a band-pass filter. The band-pass filter unit includes resonators 11, 12, and 13. The band-pass filter 10 has a line 15 for detection which is coupled on an electromagnetical field basis to the band-pass filter unit to function as a sub-line of the directional coupler by connecting the monitor terminal 3 and isolated terminal 4 to each other. Furthermore, the band-pass filter 10 has a multilayer substrate and the resonators 11, 12, and 13 are constituted by conductor layers in the multilayer substrate. COPYRIGHT: (C)2009,JPO&INPIT
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