Characterisation of narrowband communication channels on the human body at 2.45 GHz

A number of propagation measurements of belt-to-head and belt-to-wrist channels have been performed with inverted F-antennas, planar inverted F-antennas (PIFAs), monopole, loop and dipole antennas, and propagation models were derived. It is found that the channel can be separated into short-term and long-term fading components. The short-term fading can generally be modelled with a Rician distribution, whereas in many cases, long-term fading is lognormal, the best distribution is dependent on the channel, antenna type and orientation. Variation of channel parameters with time is studied and an alternative approach to modelling long-term fading deterministically is suggested. Power spectral densities, autocorrelation functions, fade probabilities, level crossing rates and average fade durations are also investigated.