| 摘要 |
PROBLEM TO BE SOLVED: To cope with two communication systems with adjacent frequencies with a simple circuit configuration and to miniaturize a device by forming the prescribed circuit configuration, through the use of a strip line having a prescribed line length. SOLUTION: The line length of a strip line SL is set as one-fourth of the wavelength of the frequencies of a transmission signal and a second reception signal, and an impedance is set as infinity for the line length of the strip line SL. When a control signal is supplied to a control terminal CONT1, the transmission signal from a transmission terminal TX is set to infinity in impedance by the strip line SL and it does not flow in a reception terminal RX1, does not flow in the reception terminal RX2 by a diode D2 and is supplied to an antenna terminal TX. The diodes D1-D3 are turned off in a reception state, unless the signal is transmitted to the control terminal CONT1, a reception signal does not flow in the antenna terminal TX, the strip line SL is operated as a transmission line, and the reception signal is led to the reception terminal RX1.
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