A study on the receiving signal level in relation with the location of electrodes for wearable devices using human body as a transmission channel

Studies of wearable computers have attracted public attention in these days And one of the area of interest is the communication system adopted in those wearable computers. As an example, wear-able devices which use the human body as a transmission channel, have been developed. This communication system uses near field region of the electromagnetic wave generated by the device which is eventually coupled to human body by electrodes. Hence, the structure of electrodes is one of the key issues for the transmission using human body. However, little is known about the transmission mechanism of such devices in the physical layer. In this paper, we propose calculation models of the transmitter and the receiver attached to the arm using the FDTD method. From this model, we estimated the difference in the received signal level due to the electrode structures of the transmitter and the receiver under various conditions. Moreover, in order to verify the validity of these calculation models, we compared the calculated received signal levels to the measured ones by using the biological tissue-equivalent phantom with die transmitter and the receiver. The result shows a good agreement of the calculated and measured received signal levels. In addition, it is found that the GND electrode of the transmitter strengthens the generated electric field around the ann. However, the existence of a GND electrode for the receiver reduces the received signal level.