Rules of thumb for predicting path loss in body coupled communication channels

Abstract

In Body-Coupled Communication, a signal propagates as an Electric Field around the human body. It can be generated and picked-up by a capacitive transducer near the skin. This paper proposes approximate expressions for the path loss in such channels and compares these with more accurate calculations of an equivalent circuit. In particular, the authentication use case is addressed of a transmit tag in the immediate vicinity of the body, e.g. in a wallet, and a reader tag at some distance from the human, e.g. near a hand reaching out.