The present invention relates to an antenna system (1), a method and an apparatus (20) for directing a received signal (RX), along selected signal path/paths (12, 13, 14, 15), such that the operation of any of the radio base stations (40, 50) in the antenna system (1) depends on the selected signal path/paths (12, 13, 14, 15). The antenna system (1) is comprised of a filter combiner (10) connected to radio base stations (40, 50) that are of different radio access networks. The apparatus (20) of the antenna system further comprises a duplex filter (21), coupled to the filter combiner (10), and adapted to receive/transmit signals of different access networks. The duplex filter (21) further comprises a transmitter filter (21a) and two receiver filters (21b, 21c). The receiver filters (21b and 21c) are further connected to a switch (22), said switch (22) is adapted to direct the received signal along one or several selected signal paths (12, 13, 14, 15) such that the operation of any of the radio base stations (40, 50) is dependent on which signal path/paths that is/are selected.