Mitigation of antenna displacement with array antenna for data transmission in wireless power transfer system

Magnetic resonance wireless power transfer is expected to be one of the prevalent schemes because of its high efficiency and long transmission range. However, in this scheme, there is a problem that the characteristics of a transmission channel changes in according with the distance between coil antennas. This paper investigates the performance of data transmission with an array antenna in a wireless power transfer system. In the assumed system, the same antennas for wireless power transfer are used for data transmission. The frequency response of the channel for data transmission changes in according with the distance between the antennas. The assumed system uses multiple transmit antennas and beamforming is realized with ideal phase shifts to transmit symbols in the transmitter. Numerical results obtained through computer simulation show that the proposed scheme can mitigate the dependency of the bit error rate (BER) to the distance between the antennas. It is within 1-3 dB at the BER of 10-5 with two transmit antennas. In addition, the system with two transmit antennas achieves 2 dB or more improvement in term of the BER than with a single antenna for specific antenna distances.