Investigation of dual-band coil module for near-field wireless power transfer systems

This work presents a dual-band coil module for near-field resonant wireless power transfer (WPT). It provides additional channel either for more power transfer or higher data transmission. We use only one single-turn coil which can avoid interference among coils occuring in a multi-coil WPT system, and adopt a simple LC branch circuit into the single-turn coil to obtain dual-band operation. In contrast to a single-band WPT, it can transmit more amount of power than maximum permissible exposure (MPE) to a receiver within the human electromagnetic exposure constraint. Measurement results show a good performance that reaches 103% MPE power at a coil separation distance inside 20 cm (1.87 loop radii) and 40% MPE power at a coil separation distance of 100 cm (10 loop radii).