Transmission model of Human Body Communication incorporating size and distance between the two electrodes of a transmitter

In Human Body Communication (HBC), electrodes are equivalent to antennas in other wireless communication. Transmission from a transmitter worn on the wrist to an off-body receiver touched by the subject's finger at frequency of 10 MHz was investigated. The received signal voltage was measured for transmission electrodes of several different dimensions and electrode distances. The results were compared with a transmission model where the transmitter electrodes were modeled as electric dipole. The received signal voltage was proportional to the transmitter electrode distance indicating that electric dipole model was applicable. Capacitive reactance between the transmitter electrodes was evaluated by assuming that the received signal was proportional to the charge accumulated at the electrode. The estimated equivalent capacitance was proportional to the area of the electrode with power of 0.4. These results provide relationship between the transmitter electrode impedance, transmitter electrode configuration, and received signal strength.