  This paper presents the ultra-wideband (UWB) on-body radio channel modelling
using a sub-band Finite-Difference Time-Domain (FDTD) method and a model
combining the uniform geometrical theory of diffraction (UTD) and ray tracing
(RT). In the sub-band FDTD model, the frequency band (3 - 9 GHz) is uniformly
divided into 12 sub-bands in order to take into account the material frequency
dispersion. Each sub-band is simulated separately and then a combination
technique is used to recover all simulations at the receiver. In the UTD/RT
model, the RT technique is used to find the surface diffracted ray path while
the UTD is applied for calculating the received signal. Respective modelling
results from two-dimensional (2-D) and three-dimensional (3-D) sub-band FDTD
and UTD/RT models indicate that antenna patterns have significant impacts on
the on-body radio channel. The effect of different antenna types on on-body
radio channels is also investigated through the UTD/RT approach.
