Electromagnetic field analysis of human body communication between wearable and stationary devices including the earth ground

In this study, we investigated the electric field distribution and transmission characteristics between a stationary device and an arm-mounted wearable human body communication device including earth ground. The results showed that when the stationary device signal electrode is excited, the electric field distribution around the legs and torso becomes weak when there is an earth ground as compared to when there is no earth ground, regardless of the size of the earth ground (finite, infinite). In addition, it was found that when there is an earth ground, the transmission characteristics between the stationary device and the arm-mounted wearable human body communication device are better by approximately 6 dB than when there is no earth ground, regardless of the size of the earth ground (finite, infinite). These are thought to be because a change occurs in the electric current path flowing through the body owing to the presence of the earth ground. The above proves that when examining communications between a stationary device and a human body wearing a human body communication device, the study should consider earth ground.