Channel Modeling and Characterization of EQS Capacitive Coupling Human Body Communication

Human body communication (HBC) has emerged as a key alternative to radio frequency (RF) communication, with path loss (PL) evaluation being crucial for HBC system development. Despite the existence of various PL measuring techniques in the quasi-static electric (EQS) band, the obtained results exhibit significant variance that tends to make overly optimistic PL estimates for HBCs. Additionally, these methods have displayed inconsistencies in comparison to simulation results, primarily because of the lack of an accurate simulation model, which fails to provide a complete characterization of capacitive coupling HBC (CC-HBC) operation. To address these issues, this study proposes a simple, battery-powered transceiver to accurately measure PL. Furthermore, a comprehensive lumped circuit model is introduced to verify measurements and support the characterization and development of CC-HBC systems. The study also investigates the effects of load impedance, intercoupling capacitance, and leakage impedance on overall PL through ADS simulation. Lastly, a PL model is developed that considers crucial parameters, including distance, frequency, ground plane size, receiver capacitance, and resistance, providing valuable design guidance for efficient EQS-HBC systems.