Human Body Communication Based on Magnetic Coupling

This paper presents a method of human body communication that employs magnetic coupling. Since a human body acts as one component of a loop for creating the magnetic coupling, strong coupling occurs only when a person closes the loop. Thus, a person's natural bodily movement forms a communication channel. Here, the validation of the mechanism of channel formation and the robustness against surrounding environment were presented. First, the validity of the circuit model was demonstrated through measurement of the transfer function of the channel (channel loss) at frequencies up to 20 MHz. Second, the validity of the mechanism of channel formation was demonstrated. Comparing to opening the loop, closing was found to increase the transfer function by more than 30 dB at frequencies below 10 MHz. This strong channel formation verifies its mechanism. Finally, to investigate the influence of a nearby metal object on the transfer function, a metal object was placed on or near the experimental setup; but no significant degradation of the transfer function was observed. This demonstrates robustness against surrounding environment. These results suggest the possibility of communication by magnetic coupling with a human body as part of the communication channel.