 Users may download and print one copy of any publication from the public portal for the purpose of private study or research.  You may not further distribute the material or use it for any profit-making activity or commercial gain  You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.

A highly sophisticated ray-based propagation model is used to find the optimal on-body radiation pattern for an earto-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.

Two different formulations of the antenna far-field used to evaluate the on-body path gain at 2.45 GHz through a raybased ear-to-ear propagation model are compared. The free-space far-field formulation does not take field coupling to the human body in the on-body far-field into account, whereas the on-body formulation does. The simulations are compared with a reference full-wave simulation. It is expected that the on-body formulation should improve the accuracy of the propagation model since it takes the field-to-body coupling into account in the on-body farfield. It is found that the results of the comparative study are aligned with expectations. The path gain that results from the use of the on-body far-field formulation is closer to the reference path gain in the band of interest, i.e., around 2.45 GHz.