Using the nfc field from a phone to power card to phone bluetooth communications

A contactless card communication method, the method comprising:

• providing a contactless card comprising a processor, a communication interface, and a power harvesting unit;
• harvesting, by the power harvesting unit, power from a near field communication (NFC) field generated by a secondary device;
• limiting, by the processor, an amount of power supplied to the communication interface in order to limit a range of a signal generated by the communication interface to a pre-determined range;
• detecting, by the contactless card, an NFC field generated by the secondary device,
• wherein the secondary device comprises a radio antenna and a NFC field generator, and
• wherein the secondary device is in communication with a server;
• harvesting power, by the contactless card, from the NFC field generated by the secondary device;
• and
• establishing two-way communication between the contactless card and the secondary device.

A contactless card comprising:

• a processor;
• a communication circuit;
• and
• a power harvesting unit configured to harvest power from a radio signal,
• wherein the processor is configured to limit an amount of power supplied to the communication circuit in order to limit a range of a signal generated by the communication circuit to a pre-determined range.