Patent ID: 7349674

Claim:
An apparatus for separating transmit and receive signals in a radio system for transmitting and receiving a signal by using a single frequency and an antenna, comprising: a power amplifier for amplifying a transmit signal and outputting the signal; a transmitter circulator for passing the amplified transmit signal through a transmission path with a lessened signal loss, and respectively outputting a transmit leakage signal to first, second, and third leakage paths for reducing the transmit leakage signal; an antenna circulator for passing the transmit signal through the transmission path and radiating the signal through an antenna, and outputting the leaked transmit leakage signal to the first leakage path to be reduced; and a receiver circulator for inverting the transmit leakage signals received through the first and third leakage paths with respect to each other and canceling out the signals, and reducing the transmit leakage signal received through the second leakage path and outputting the signal.