| 摘要 |
PROBLEM TO BE SOLVED: To solve a problem that a filter circuit characteristics as can not be obtained as designed because of unwanted electric field or magnetic field coupling between respective resonators of the filter circuit. SOLUTION: A first dielectric layer 1, with which a first resonator 6 and a first ground conductor 8 are attached and formed on an upper surface and a lower surface, and a second dielectric layer 2, with which a second ground conductor 9 and a second resonator 7 are attached and formed on the upper surface and the lower surface, are confronted through a third dielectric layer 3 with the first and second ground conductors 8 and 9 in between so as to mutually confront the first and second resonators 6 and 7, and an opening 16 is provided for electromagnetic field coupling of the first and second resonators 6 and 7 to one of the first and second ground conductors 8 and 9 located between the first and second resonators 6 and 7 in a subordinate TEM mode. The filter circuit of characteristics as designed can be exactly designed/produced without the unwanted electric field or magnetic field coupling between two filter circuit boards.
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