The present invention relates to a source antenna for transmitting/receiving electromagnetic waves comprising means for transmitting electromagnetic waves with longitudinal radiation operating in a first frequency band and means for receiving electromagnetic waves, characterized in that the means for receiving electromagnetic waves consist of a first array of n radiating elements operating in a second frequency band and a second array of n′ radiating elements operating in a third frequency band, the first and second arrays and the longitudinal-radiation means having a substantially common phase centre and the radiating elements of the first and second arrays being arranged around the longitudinal-radiation means.