A Dual Resonance Near Field Communication Coil for EMF Reduction in Near Field Communication and Wireless Power Transfer Dual Coil System

Current wireless power transfer (WPT) technology is widely used for various applications because of convenience and safety. One of the typical application of the WPT system is the near-field communication (NFC) system utilized mobile WPT system. However, WPT systems have problems with electromagnetic field (EMF) leakage which can cause electromagnetic interference (EMI) issues on the nearby electrical devices. In this paper, we propose the dual resonance NFC coil for EMF reduction. Proposed dual resonance coil generates resonance not only at the NFC operating frequency of 13.56 MHz but also at the wireless charging frequency 130 kHz. When comparing the proposed NFC coil with a typical NFC antenna, the total EMF level of the WPT system is reduced by 3.96 dB at 130 kHz without any effect at the NFC operating frequency of 13.56 MHz.