Antenna design for unified far-field communication and near-field recharging

The same antennas exploiting their far-field behavior for communication purposes, can be suitably configured for realizing wireless power transfer via their near-field properties. In this paper we theoretically and numerically study the behavior of a pair of closely coupled transmitting and receiving antennas, originally designed for far-field communication. They realize a two-port reactive network to be arranged in a resonant link configuration for wireless power transfer. By appropriately selecting matching network and load values it is possible to obtain the coexistence of these two antenna operation modes. A proof of concept is discussed in this paper by designing a printed dipole antenna, combined with its matching networks, to operate at 13.56 MHz in the near-field and at 868 MHz in the far-field.