The invention relates to a circuit arrangement comprising an antenna port (2), a transmission port (1), and a reception port (3), each of which is connected to one respective 90 DEG hybrid (6, 7, 8) that splits an input signal into two output signals that are in quadrature. The circuit arrangement further comprises two duplexers (4, 5) which are connected in such a way that the two output signals emitted by the 90 DEG hybrid that is connected to the transmission port (1) constructively interfere on the antenna port (2), while spurious signals caused by the two output signals destructively interfere on the reception port (3).