Wearable near-field communication antennas with magnetic composite films

The flexible near-field communication (NFC) antennas integrated with Fe3O4/ethylene-vinyl acetate copolymer (EVA) magnetic films were presented, and the influence of the magnetic composite films on the performance and miniaturization capability of the NFC antennas was investigated. Theoretical analysis and experimental results show that the integration of the magnetic composite films is conducive to the miniaturization of the NFC antennas. However, the pattern design of the integrated magnetic film is very important to improve the communication performance of NFC antenna. When magnetic film covers whole antenna, the inductance (L) and quality factor (Q) of the NFC antenna at 13MHz are increased by 60% and 5% respectively, but the communication distance of NFC system is decreased by 70%. When the magnetic film is located at the center of the antenna, the L value, Q value and communication distance of the NFC antenna are increased by 16.5%, 15.5% and 20% respectively. It can be seen that the application of the integrated magnetic film with optimized pattern to the NFC antenna can not only reduce the size of the antenna, but also improve the overall performance of the antenna.