Radiated electric field strengths on the ground for various body-worn antenna positions

Abstract

The knowledge of radiated fields from a body-worn RF antenna system receiver at the ground surface is important for applications such as unattended ground sensors, biomedical sensors, or peer-to-peer communications. The impact of operating frequencies, various on-body antenna positions, and various ground types are modelled in this study. Simulations are performed from VHF to SHF-bands in the near-field for a large number of scenarios using an accurate human body model. Far-field approximations are used to obtain the electric field strength just above the ground while taking into account scattering from the surface. It is found that the body affects the antenna radiation pattern differently at different frequencies, and has a significant shadowing effect above 1 GHz, with the strongest field occurring in direct line of sight. The ground moisture has a major impact on the transversal electric field and causes a much smaller attenuation of the normal field components. The methodology can be easily adapted to estimate the field strength on the ceiling or at wall locations in a room.