数値電磁界解析を用いた磁界方式人体通信の信号伝送特性と生体安全性評価

抄録

This study evaluated the signal transmission characteristics, the electromagnetic field distributions in and around the human body, and the biosafety criteria of magnetically coupled intra-body communication through computer simulation. The analyzed magnetic couplings were a normal inductive coupling (non-resonant coupling) and two types of resonant couplings. The target evaluation regions were the forearm and upper body, and we analyzed up to an inter-coil distance of 100 cm, which is considered to be the assumed human body communication range. The results of the frequency characteristics of the signal path loss, which were the same as before, revealed that the amount of signal loss for the inductive coupling was minimized between 2 and 3 MHz at each coil distance; one of the resonant couplings could improve the signal path loss by approximately 20 dB at a resonant frequency of 2 MHz. Furthermore, when the signal voltage was 1 V, the electric field strength in the body was smaller than the general environmental limit value by more than two orders of magnitude. The local specific absorption rate was smaller by approximately four orders of magnitude; thus, it was concluded that the magnetic field method is very safe for the living body.