The invention relates to an antenna system for a mobile terminal (1), comprising a casing (2), which accommodates radio electronic circuits (REC) and a screening device (SD) for the radio electronic circuits. The casing (2) comprises an end-fed antenna (4), connected to the radio electronic circuits (REC). The end-fed antenna (4) is located within and extends through a major part of the casing (2). The antenna system comprises a counterpoise element (5), located near one end of the end-fed antenna (4), and the end-fed antenna is adapted to be fed, during transmission, against the counterpoise element (5) by the radio electronic circuits (REC).