The Design of a Dual-Band 4-Port Magnetic Resonant Wireless Power Transfer Coupler: Theoretical Analysis of Losses and Interference for Biomedical Wearable Applications

This study analyzes cross-band interference and losses in a compact dual-frequency 4-port inductive coupler operating at 6.78 MHz and 13.56 MHz for Magnetic Resonant Wireless Power Transfer (MR-WPT) using an equivalent circuit model fitted to 3D full wave analysis and empirical measurements. The model is first matched to idealized 3D model results to establish baseline parameters and then theoretically analyzed in relation to measured S-parameters to reflect empirical losses. This approach achieves accurate theoretical interpretation, with errors remaining below 5%. The results show consistent transmission coefficients, with the model most closely matching the measurements. Power loss and efficiency comparisons indicate that the model accurately captures deviations, with its performance positioned between the 3D full wave analysis and measured results. Cross-band interference remains below −20 dB, and the maximum measured efficiency reaches 71.18%.