an active cancellation unit is disclosed for improving the noise cancellation between a transmitter and a receiver which are connected to an antenna using a duplexer , the unit comprising a coupler sampling a signal to transmit provided by the transmitter , a cancellation duplexer having characteristics similar to the duplexer and receiving the sampled signal to provide a simulated signal and an active component receiving the simulated signal and providing an amplified signal having a phase 180 degree shifted with respect to the simulated signal ; and a coupler for injecting the simulated signal at the receiver .