Characterization of 3D-stacked nodes for Body Area Networks at 2.45 GHz

This paper presents the characterization of two 3D-stacked BAN nodes, both in free-space and on-body operation. Input impedance measurements have shown that the groundplanes below the antenna act as a shielding layer, preventing antenna detuning when placed on the human body. Radiation pattern measurements have indicated that the back radiation of the antenna is absorbed by the human body, while the off-body broadside radiation is preserved. On the other hand, measured efficiency values have been lower than the ones expected according to the electromagnetic simulations. It has been demonstrated through measurements that this is due to the presence of metal parts near the antenna (traces, vias, etc). These elements also have an impact on the input impedance of the antenna. Therefore, simplified simulation models are suitable for obtaining fast results, but they do not provide accurate results for antennas on Printed Circuit Boards (PCBs) with metallic elements around them.