In order to reduce the weight, cost and complexity of an active antenna array, designed for use with a plurality of different mobile telecommunications systems (multi-band system), the array comprises a plurality of antenna elements, which are divided into a plurality of antenna groups; a plurality of RF transceivers, which are divided into transceiver sets, wherein each transceiver of a set is arranged to operate on a different mobile telecommunications system, and including respective phase shifting and feeding networks coupled between each transceiver set and a respective antenna group, so that each transceiver of a set is coupled to each antenna element of the respective antenna group.