A radio coverage extender is provided for extending the radio range of a wireless network node embedded in a user terminal, for example a ZigBee node integrated on the SIM card of a mobile phone. The radio coverage extender may include: a radio signal repeater operable to receive radio signals from the wireless network node and to retransmit the received signals externally to the user terminal, and a power supply module operable to scavenge electrical energy from electromagnetic fields in which it happens to be immersed and to store the scavenged electrical energy for supplying the stored power to the radio signal repeater. The radio coverage extender is adapted to be included in a user terminal, for example it can be a flexible, pliable film attachable to a user terminal battery.