  With the advent of wearable technologies, Human Body Communication (HBC) has
emerged as a physically secure and power-efficient alternative to the otherwise
ubiquitous Wireless Body Area Network (WBAN). Whereas the most investigated
nodes of HBC have been Electric and Electro-quasistatic (EQS) Capacitive and
Galvanic, recently Magnetic HBC (M-HBC) has been proposed as a viable
alternative. Previous works have investigated M-HBC through an application
point of view, without developing a fundamental working principle for the same.
In this paper, for the first time, a ground up analysis has been performed to
study the possible effects and contributions of the human body channel in M-HBC
over a broad frequency range (1kHz to 10 GHz), by detailed electromagnetic
simulations and supporting experiments. The results show that while M-HBC can
be successfully operated as a body area network, the human body itself plays a
minimal or negligible role in it's functionality. For frequencies less than
about 30 MHz, in the domain of operation of Magneto-quasistatic (MQS) HBC, the
human body is transparent to the quasistatic magnetic field. Conversely for
higher frequencies, the conductive nature of human tissues end up attenuating
Magnetic HBC fields due to Eddy currents induced in body tissues, eliminating
the possibility of the body to support efficient waveguide modes. With this
better understanding at hand, different modes of operations of MQS HBC have
been outlined for both high impedance capacitive and 50 Ohm termination cases,
and their performances have been compared with EQS HBC for similar sized
devices, over varying distance between TX and RX. The resulting report presents
the first fundamental understanding towards M-HBC operation and its contrast
with EQS HBC, aiding HBC device designers to make educated design decisions,
depending on mode of applications.
