📝 SummarXiv

Abstract

In recent decades Human Body Communication has emerged as a promising alternative to traditional radio wave communication, utilizing the body's conductive properties for low-power connectivity among wearables. This method harnesses the human body as an energy-efficient channel for data transmission within the electro-quasistatic frequency range, enabling advancements in human-machine interaction. While prior work has noted the role of parasitic return paths in such capacitively coupled systems, the influence of surrounding metallic objects on these paths, which are critical for EQS wireless signaling, has not been fully explored. This paper fills that gap with a structured study of how various conducting objects, from non-grounded (floating) metals and grounded metals to enclosed metallic environments such as elevators and cars, affect the body-communication channel. We present a theoretical framework supported by finite element method simulations and experiments with wearable devices. Results show that metallic objects within 20 cm of devices can reduce transmission loss by about 10 dB. When a device ground connects to a grounded metallic object, channel gain can increase by at least 20 dB. Contact area during touch-based interactions with grounded metals produces contact-impedance dependent high-pass channel characteristics. Proximity to metallic objects introduces variability within a critical distance, with grounded metals producing a larger overall effect than floating metals. These findings improve understanding of body-centric communication links and inform design for healthcare, consumer electronics, defense, and industrial applications.