The invention comprises an antenna structure particularly suited for mobile stations. The antenna comprises a radiating element (100) which is of a conductor form. The antenna conductor comprises a basic conductor and as an extension to this a conductor (115, 116) which at least partly is located relatively close to the basic conductor. As the conductors are close to each other that causes an electromagnetic coupling, which again causes a second resonance frequency for the antenna. The bandwidth of the antenna can be widened when the second resonance frequency is arranged close to the first one. The antenna can be made as a two-band antenna when the second resonance frequency is arranged relatively far from the first one. The bands can be made relatively wide, so that the antenna operates satisfactorily in different positions and in the neighbourhood of objects. It can be fastened to the back wall of a mobile station, whereby the distance to the user's head is made as large as possible.