| 摘要 |
PURPOSE:To attain ease of insertion of a reception filter as required only by switchig an antenna in common use for transmission/reception to the reception and detecting and amplifying a transmission signal produced from the own device at transmission to drive a relay thereby switching the antenna for the transmission use. CONSTITUTION:When a transmitter 1 is brought into the operating state, a part of a transmission output is detected (6) from a terminal through a connecting section 8, a DC voltage is amplified (7) to drive relays 4, 5. Contacts 4-1, 5-1 of the relays 4, 5 are thrown to the position conversely from that shown in the figure, the terminal of the transmitter 1 and a terminal 21 are connected by a line 23 and the transmission output is irradiated externally from the antenna (not shown). The reception power on a contact S-2 and a line 4-1 at reception is very little in comparison with the transmission power and the relays 4, 5 are not activated. The crosstalk is eliminated by applying external connection to a reception filter 3 only when a frequency close to the reception wave exists, the decrease of the reception electric field is prevented normally to improve the reception efficiently. |
