| 摘要 |
PROBLEM TO BE SOLVED: To suppress the sneak path of a transmission frequency by inserting a filter circuit for turning the differential frequency of the transmission frequency and the reception frequency of the master unit of a selected channel to a resonance point and attenuating the differential frequency components. SOLUTION: In a radio telephony set provided with plural transmission/reception parts for performing transmission and reception with a slave unit in the master unit, the filter circuit for turning the differential frequency of the transmission frequency and the reception frequency of the master unit of the selected channel to the resonance point and attenuating the differential frequency components is inserted to an input terminal on the side of at least one transmission/reception part of the shared device of an antenna. That is, one ends of individual coils are connected to the respective input terminals in the direction of the two transmission/reception parts as the shared device of the antenna, a resistor and a capacitor are parallelly connected between the input terminals, the other ends of the individual coils are connected and turned to an output terminal in an antenna direction and the capacitor is inserted between the output terminal and ground. Further, aπtype or serial LC circuit is inserted as the filter circuit between the input terminal of the shared device and at least one transmission/reception part.
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