| 摘要 |
PROBLEM TO BE SOLVED: To simplify a high-frequency tuning circuit equipped with a circuit that suppresses an image frequency; to provide a composite coil which is made a adjustment-free set, reduced in size, and made to decrease in price; and to provide a method of manufacturing the same. SOLUTION: The composite coil forms a high-frequency tuning circuit having an integral configuration composed of a metal case, a screw core, a bobbin which is equipped with the implanted external connection terminals and winding grooves, and a circuit board where a circuit unit is formed. In the composite coil, the winding wires of an input coil, a tuning coil, and an output coil are wound in the prescribed grooves of the bobbin; the terminals of the windings are connected to the prescribed connection terminals; a circuit board mounted with electronic parts constituting the high-frequency tuning circuit is fixed to the external connection terminals of the bobbin; and the input coil, the output coil, and the tuning coil are magnetically coupled so as to satisfy a following formula, K1×K2/K3<1. K1 is a coupling coefficient of the tuning coil and the input coil, K2 is a coupling coefficient of the tuning coil and the output coil, and K3 is a coupling coefficient of the input coil and the output coil. COPYRIGHT: (C)2006,JPO&NCIPI
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