| 摘要 |
PURPOSE:To block the transmission of an unnecessary wave according to the discrimination of the unnecessary wave at the out-band by reflecting a signal from a transmitter at a reflection BPF, branching the result at a circulator and detecting it to compare a detected output with a prescribed value. CONSTITUTION:A signal of IF band from modulators 10, 18 of the radio transmitter is converted into a microwave signal different from that of other transmitters 19, 11 by the transmitters 11, 19 and fed to the 1st circulators 12, 20. A transmission signal from the circulators 12, 20 is fed to the reflection BPF13, 21 and also the reflected wave from the BPF13, 21 is fed to detectors 16, 24. An output of the detectors 16, 24 is fed to controllers 17, 25 and when its detected output is smaller than a prescribed value, switches 14, 22 are turned on and when larger, the switches 14, 22 are turned off. When the switches are turned on, a transmission signal is fed to an antenna 26 via the 2nd circulators 15, 23 and when they are turned off, a signal from the BPF13, 21 is subject to resistive termination to block the unnecessary wave from the circulators 15, 23 from being transmitted. |
