Summary
International Symposium on Antennas and Propagation
2012
Session Number:POS1
Session:
Number:POS1-46
Equivalent Circuit of Intra-body Communication Channels Based on a Lossy Conductor Model
Nozomi Haga, Koichi Ito,
pp.-
Publication Date:2012/10/29
Online ISSN:2188-5079
Summary:
The physical channels establishing intra-body communications were first treated as capacitive circuits by Zimmerman. However, the conventional circuit model is of assuming capacitances only between particular conductors, and is not based on quantitative analyses; therefore, its validity had been unclear for a long time. For this reason, we have derived an improved circuit model by solving a boundary value problem of electric potentials of conductors. However, the applicable scope of the improved model is still limited for two reasons. One is that the wavelength should be sufficiently longer than the human body. The other is that the conduction currents inside the human body should be sufficiently little because the human body is approximated as a perfect electric conductor (PEC) in both the conventional and improved models. In contrast, the transmitter investigated by Fujii was designed so as to induce conduction currents inside the human body; therefore, the PEC model is no longer applicable even if the frequency is sufficiently low. Regarding the former problem, some researchers extended Zimmerman's circuit model to simulate the frequency dependence of the communication channels. However, the circuit parameters in their models were just assumed or determined so that the received voltage calculated by the circuit model fits with the measured or simulated results. In a strict sense, it is difficult to represent the channel characteristics by a circuit model at such a high frequency. On the other hand, the latter problem can be properly handled if the frequency is sufficiently low. In the present paper, the equivalent circuit for lossy conductors is derived and the physical mechanism of the communication channels inducing conduction currents inside the human body is addressed.