Analysis of the Human Body as an Antenna for Wireless Implant Communication

Currently, the radio-frequency (RF) implant wireless communication is enabled by utilizing small antennas that radiate radio waves inside the human body. As an alternative technique for implant wireless communication, we propose to use the human body itself as an antenna by feeding an RF current into the tissues. In particular, this paper studies the scenario when the RF current is fed by a tiny toriodal inductor that is implanted and clamped around the tissues in the ankle. The frequency range of 170 MHz is considered, which includes the resonance frequency of the human body. Theoretical results, from applying small toroidal inductors, show that the system exhibits broadband characteristics with a maximum gain of -25 dB between 20 and 40 MHz, assuming an isotropic radiation from human body. However, for the case of the small toroidal inductors considered, the radiation resistance of the system is very small, which increases the power consumption. It is known that the radiation resistance can be further improved by choosing a magnetic core with high permeability and low loss, as well as, by optimizing the number of turns to reduce the parasitic capacitance and obtain a usable magnetizing inductance.