| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a compact filter having narrow-band filter characteristics by using interdigitally coupled resonators. Ž<P>SOLUTION: The filter includes a first resonator 1 and a second resonator 2 of an interdigitally coupled type. Electric-field coupling electrodes 11A, 12A are provided at open ends of a pair of quarter-wavelength resonators 11, 12 constituting the first resonator 1. Electric-field coupling electrodes 21A, 22A are also provided at open ends of the other pair of quarter-wavelength resonators 21, 22 constituting the second resonator 2. The electric-field coupling electrodes 11A, 12A and the electric-field coupling electrodes 21A, 22A are arranged oppositely to each other so as to mutually overlap between the first resonator 1 and the second resonator 2. An element that makes magnetic-field coupling and electric-field coupling cancel each other is added between the first resonator 1 and the second resonator 2. Accordingly, coupling between the first/second resonators is weakened compared with a structure of a prior art in which interdigital resonators are simply arranged in parallel, thereby achieving a narrow-band filter. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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