| 摘要 |
PURPOSE:To decrease number of components and to attain miniaturization by having only to switch a power supply so as to switch transmission and reception and also use components for transmission/reception in common. CONSTITUTION:In throwing a switch 7 to the position T, the position T, the transmission state is obtained. A voltage is applied to a base of a transistor (TR) 13 for an output buffer amplifier and an oscillating circuit 12 and a battery voltage is applied to a collector of the TR13 via a filter 8. Then an output oscillated and amplified appears the collector of the TR13 and a high frequency signal is transmitted from an antenna 1. Moreover, a diode 11 is interrupted completely and it is possible to disconnect an antenna 1 from a reception circuit 5. In throwing the switch 7 to the R position, the reception state is obtained. A voltage is applied to the reception circuit in this case and the power supply of the transmission circuit is disconnected. Then the diode 11 is conducted and the antenna 1 is connected to the reception circuit 5 via the filter 8. Furthermore, the power supply of the transmission circuit 4 is interrupted, and the TR13 is cut off and reaches the high impedance state, which does not give any effect onto the reception circuit. |
