Numerical Assessment of Specific Absorption Rate in the Human Body Caused by NFC Devices

The Near field communication technology (NFC) is applied for transferring data over short distances by maintaining an inductive coupling of the transmitter and the receiver at 13.56 MHz. The relatively high magnetic field strength in the immediate surrounding of NFC devices give rise to the question about the local personal exposure of the user holding such a device in the hand or close to the body. In the present paper personal exposure in terms of the maximum 10g-averaged specific absorption rate (SAR) while using NFC was estimated for different scenarios using MRI-based anatomically correct body models. The simulations were performed with the method of Finite Differences in Time Domain (FDTD). The numerical models of the considered NFC devices were validated by SAR measurements using a simplified homogeneous body phantom and acceptable agreement between measurements and simulations was achieved. Several exposure scenarios with a cell phone comprising NFC functionality and a stationary NFC reader were investigated considering two different body models (male 34 years, male 14 years). The results showed maximum 10g-averaged SAR-values more than two orders of magnitude below the basic restriction recommended by the International Commission for Non Ionizing Radiation Protection (ICNIRP). The absolute maximum value of the maximum 10g-averaged SAR found in the considered scenarios was 11.18 mW/kg. Therefore, it can be concluded that personal exposure due to NFC devices typically cause SAR levels far below the basic restrictions of safety guidelines.