| 摘要 |
PROBLEM TO BE SOLVED: To provide a compact and inexpensive dielectric filter which can attenuate the higher harmonics with a small number of parts by incorporating a correction resonator into the filter as a means which improves its higher harmonic characteristic. SOLUTION: The conductor films 4 are formed on the entire outer surface of a dielectric block 1, plural resonator through-holes 3, input/output terminal holes 2 and inner surface of through-holes 8 formed on the end faces of holes 2 respectively. Then the films 4 are scraped off by a tapered reamer, etc., at the peripheral parts of through-holes 3 and 8 and the peripheral parts of holes 2, so that the conductor film eliminated areas 5, 6 and 9 are formed. Thenλ/4 resonator consisting of a 3-stage structure of a resonator 3 is unified with a resonator 8 of a 1-stage structure which is capacitance coupled to the resonator 3, and the areas 5 of through-holes 3 are alternately arrayed on both upper and lower surfaces. In such a constitution, an inter-digital dielectric filter is obtained. If larger attenuation is required, two resonators 8 which improve the higher harmonics are symmetrically provided at both sides of the filter.
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