Dual-directional near field communication tag antenna with effective magnetic field isolation from wireless power transfer system

Wireless power transfer (WPT) system has been developed to achieve higher charging power and convenient charging experience to users. In some mobile electronic devices with WPT system near-field communication (NFC) system can also be utilized. However, during the wireless charging, large voltage is induced in the NFC tag due to the magnetic fields from the wireless charging system. Consequently, the NFC tag must be isolated from the WPT system for simultaneous operation. In this paper, the NFC tag with dual-directional pattern antenna is presented for efficient isolation of the WPT system. The transmission coefficient between the proposed NFC tag and the NFC antenna is reduced by 3 dB at 13.56 MHz, while insertion loss between the tag and WPT coil is reduced by 18 dB at 110 kHz. Even with 10 mm misalignment between the proposed NFC tag and the WPT coils, 10 dB reduction of insertion loss can be achieved at 110 kHz.