Antennas and propagation for on-body communication systems

On-body communication channels are of increasing interest for a number of applications, such as medical-sensor networks, emergency-service workers, and personal communications. This paper describes investigations into channel characterization and antenna performance at 2.45 GHz. It is shown that significant channel fading occurs during normal activity, due primarily to the dynamic nature of the human body, but also due to multipath around the body and from scattering by the environment. This fading can be mitigated by the use of antenna diversity, and gains of up to 10 dB are obtained. Separation of the antenna´s performance from the channel characteristics is difficult, but results show that for many channels, an antenna polarized normal to the body´s surface gives the best path gain. Simulation and modeling present many challenges, particularly in terms of the problem´s scale, and the need for accurate modeling of the body and its movement.