| 摘要 |
A tower-top low noise amplifier of a time division duplexing communication system operates the system stably in case of the transmission of a high power transmission signal by using three-terminal circulator in transmission and reception terminals and separating the transmission signal and the reception signal by using a switch of the reception terminal. A first circulator(301) separates a reception signal received from an antenna transmitted to a receiver and a transmission signal from the base station to the antenna. A switch(302) is equipped in the receiver and performs the switching in order to determine the transmission timing according to a control signal. The receiver prevents the distortion of the signal received from the first circulator. An isolator(307) transmits the received signal from the receiver to the second circulator and protects the receiver from the transmission signal. A second circulator separates the reception signal received from the isolator to the base station and the transmission signal transmitted from the base station to the antenna. A disconnecting switch(310) is arranged in the transmission unit between the first and second circulators and maintains the isolation between the transmission signal and the reception signal. |
