A method of controlling a tuneable filter (13a) of an antenna network (13) for use in a base station (1). The proposed method comprises: inputting an output of the antenna network (13) to a pre-distortion feedback path (5), inputting an output of the pre-distortion feedback path (5) and part of an original baseband signal to be transmitted by the base station (1) to a tuneable filter optimization algorithm (20a), controlling the tuneable filter (13a) in accordance with an output (CS) of said tuneable filter optimization algorithm (20a).