Modeling Accuracy and Features of Body-Area Networks with Out-of-Body Antennas at 402 MHz

Voltage and power transfer functions for the path loss of a 402 MHz body-area network are reviewed. The corresponding expressions are valid in both the near- and far-fields of a transmitting antenna. It was shown that basic FDTD simulations for a homogeneous human-body model, implemented in MATLAB^®, agreed quite well with the advanced FEM solver for an inhomogeneous accurate human-body model. Both methods modeled a voltage transfer function (path loss) for out-of-body dipole antennas at 402 MHz at different antenna locations, as close to the body as 15 mm. The reason for the good agreement was that the propagation path was mostly determined by a diffraction of the electromagnetic signal around the body, and not by propagation through the (inhomogeneous) body. Such an observation made it possible to use various homogeneous body meshes in order to study the effect of different body types and positions for out-of-body antennas. A method of creating such meshes using a three-dimensional body scanner is described. For a number of different white-male body meshes, the magnitudes of the received voltages matched exceptionally well when the antenna positions were measured from the top of the head.