Does anyone know if the external antenna mounted at the top of the rear window is exclusively for the mobile phone? I have a 740 with TV, Navigator and GSM 900 MHz phone (live in Sweden). The external antenna window is rather big and seems complicated with a coil and wire wound around it. If it is only for a mobile phone I would like to replace it with a smaller one, but I am afraid this might also affect TV and GPS reception. I suppose the radio antenna is integrated in the rear window.