Ear-to-Ear Propagation Model—Antenna Radiation Pattern Optimization

A highly sophisticated ray-based propagation model is used to find the optimal on-body radiation pattern for an ear-to-ear link. The propagation model allows for a rapid evaluation of the path gain given the antenna radiation patterns. The radiation patterns are represented by the spherical wave expansion (SWE) since they are easy to handle in the computer and in addition the expansion coefficients separate one antenna from another. Furthermore, the SWE produces physically realizable radiation patterns. The procedure to obtain the optimal radiation patterns is formulated as evolution-based optimization. It is found that the optimal gain pattern directs the power in the directions of the geodesic paths traced by the model that lead from one ear to the other. This is in accordance with expectations. The optimized path gain is -35.0 dB, which is obtained with lossless antennas with a minimum sphere of 0.2 free-space wavelengths.