Radiative Wireless Power Transfer System using Circularly Polarised Transmitter-Receiver Antenna Module to Improve Power-Transfer-Efficiency

In this paper, a circular polarization based wireless power transfer system is proposed for implantable medical devices (IMDs). Initially, a sequentially rotated left-handed circular polarization (LHCP) array operating at 2:4 GHz is designed for transmitter. Similarly, for receiver a miniaturised LHCP implantable antenna is designed inside a skin box to develop the WPT link. To improve the power transfer efficiency (PTE) of the WPT link a parasitic patch is placed near the receiver antenna. Parasitic patch improves the transmission coefficient by 8 dB for separation distance of 100 mm between transmitter and receiver. It is also verified that the proposed WPT system is insensitive to the angular rotation and lateral shift of the transmitter while keeping the receiver stationary. Finally, the specific absorption rate (SAR) of the implanted device is evaluated to ensure the safety limits of the proposed system.