On-Body Antenna Parameters

Within the scope of on-body communications, an approach is presented which is capable to describe the radiated on-body field of arbitrarily shaped antenna structures. The method is based on a segmentation of the excited current distribution on the antenna body by a finite number of small electric dipoles. To consider the presence of the human body, which affects the underlying radiation mechanism significantly, the model is implemented by the use of the Norton surface wave theory. Based thereon, a method is presented to model the on-body far field of an antenna by two equivalent electric dipoles: 1) a TM and 2) a TE source. Based on this assumption, the directivity and the effective antenna area are defined for on-body propagation scenarios. The radiation characteristic of body worn antennas is discussed in terms of their radiation characteristic using the example of tilted half-wave dipoles and a planar inverted-F antenna. The last part of the study discusses a pathloss model which is calculated from the underlying antenna parameters. Numerical full-wave simulations, based on the FDTD method, and measurements in an anechoic chamber, verify the results.