A device for separating signal transmission and reception has first, second, and third device ports, a circulator including a first circulator port, a second circulator port and a third circulator port, a transmission filter coupled between the first circulator port and the first device port, and a reception filter coupled between the third circulator port and the third device port. The second circulator port is coupled to the second device port An input to the first port is output from the second port and an input to the second port is output from the third port. The circuit provides isolation between transmission and reception to improve communication efficiency and can reduce the size of a communication system.