A wireless communication system comprising a smartphone comprising antenna system, and an add-on device that is configured to be attached to the smartphone, wherein, the add-on device comprises, a wireless communication module configured to transmit and receive RF communication signals, and an antenna coupling system that couples between the wireless communication module and the smartphone's antenna system in order to at least transmit or receive the RF communication signals by the smartphone's antenna system, the antenna coupling system couples the RF communication signals by at least one of or the combination of (a) conduction with the enclosure of the smartphone, and (b) induction between the add-on device and the smartphone.