An antenna system with a sharp difference in directional pattern is intended for receiving GNSS signals. The PCD is normally in radio communication with the first network, and is coupled to the first network by way of the second network when the PCD is out of radio communication with the first network. A sensing device 48 is arranged at an input region of the receiving zone for sensing at least one characteristic of the bill A controller 52 is in communication with the sensing device 48 for receiving an output signal from the sensing device 48.