An adapter (10) comprises a single adapter output (45) connectable to at least one antenna line device (100a-c), at least two base station inputs (30a-c), the at least two base station inputs (30a-c) being individually connectable to a base station (110a-c) or a primary control device (460c) and at least one microcontroller (40a-c), the microcontroller (40a-c) being connected between one of the base station inputs (30a-c) and the single adapter output (45). An antenna system (5) comprising such an adapter (10) and a plurality of antenna line devices (100a-c) connected to the single adapter output (45) of the adapter is also disclosed. A method for operating the radio antenna (10) having a plurality of antenna line devices (100a-c) from at least two base stations (110a-c) is disclosed.