An antenna duplexer (14) comprises a transmission (TX) filter (16) having an input and an output. The TX filter input is arranged to connect to a TX port of a mobile telecommunications handset and the TX filter output is arranged to connect to an antenna (12) for the mobile telecommunications handset. The duplexer further includes a Dual Mode Surface Acoustic Wave (SAW) type receiver (RX) filter (18) having an input and a balanced output. The RX filter input is arranged to connect to the antenna (12) and the RX filter output is arranged to connect directly to a balanced input RX port of the mobile telecommunications handset.