| 摘要 |
PROBLEM TO BE SOLVED: To improve the reception sensitivity and also decrease the number of coaxial cables. SOLUTION: In the antenna switching circuit 2, an internal antenna 6 is connected to the input terminal 38 of a receiving circuit 14 through only a 2nd switch 30, so the reception sensitivity is higher than when the antenna is connected through two switches like before. A 4th switch 34 is arranged nearby 1st and 2nd external connection terminals 10 and 12 and a coaxial cable 40 is used only by the connection between the common terminal 26 of the 4th switch 34 and the 2nd terminal 24 of a 3rd switch 32, so the number of coaxial cables 40 can be made one less than usual. Consequently, the cost is reduced and the laying space for the coaxial cables is decreased to make the device small-sized.
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