A mobile terminal (1), comprising a casing (2), which accommodates radio electronic circuits (REC) and a screening device (SD) for the radio electronic circuits, comprises an antenna system comprising an end-fed antenna (EA), having an extended shape, presenting a first end and a second end and being connected to the radio electronic circuits (REC). A counterpoise element (5) is located near the first end of the end-fed antenna (EA), the end-fed antenna being adapted to be fed against the counterpoise element (5) by the radio electronic circuits (REC). A tuning network (TN) is located near the second end of the end-fed antenna (EA). The tuning network (TN) is adapted to adjust the electrical length of the antenna so as to assume a value corresponding to a multiple of a half wave-length of the frequencies used.