Evaluation of ground loop through the floor in human body communication

Abstract

Ground loop through the floor is often modeled in the transmission model of Human Body Communication (HBC). This paper reports evaluation of ground loop through the floor in HBC between two subjects shaking their hands, and HBC between a subject and a stationary receiver on the floor. Subjects wore a transmitter or a receiver on the wrist. Received signal strength was measured on carpet-covered aluminum die cast floor, concrete floor, and wooden floor. The signal varied largely depending on the choice of the hand to shake hands or to touch the stationary receiver, i.e. using the hand with or without the device on the wrist. On the other hand, the signal level varied very little among floor constructions. These results indicate that most of the signal of HBC in the present case is transmitted through the capacitive coupling between the two human bodies or between the human body and the device touched by the user, and contribution of ground loop through the floor is small.