| 摘要 |
PROBLEM TO BE SOLVED: To provide a dual mode band-pass filter which has a high degree of freedom of design and is capable of easily obtaining a required bandwidth. SOLUTION: A dual mode band-pass filter 1 has such a structure where a metal film 3 is partially provided on the one surface of a dielectric board 2 or inside the dielectric board 2 at a certain height, and a first and a second input/output coupling circuit, 5 and 6, are connected to the metal film 3. When input signals are applied through one of the coupling circuits 5 and 6, two resonant modes are produced at the metal film 3, and at least a capacitor is added to the metal film 3 so as to couple the two resonant modes together, where the capacitor is composed of the opposed viahole electrodes 7 and 8 provided to the metal film 3.
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