High-Impedance Dipoles for Auto-Receiver Tracking Wireless Power Transfer Systems

This study presents a self-tuning multi-transmitter (multi-Tx) wireless power transfer (WPT) system designed for applications requiring freely positioned receivers (Rxs). The system leverages high-impedance dipole (HID) as Txs to dynamically activate the nearest Tx to a simple dipole antenna as the Rx while deactivating other Txs without additional control circuits. The Txs design incorporates a modified coaxial cable dipole antenna featuring symmetrical gaps over the shield and inductive tuning elements between the central wire and the shield to optimise the resonance frequency and ensure effective power transfer. The feeding point is connected to the central wire via a small cut in the shield. This autonomous behaviour simplifies system operation, enhances flexibility, and ensures acceptable efficient power transfer. Experimental evaluation demonstrates that the system achieves a power transfer efficiency of approximately 65% while maintaining consistent performance as the Rx rotates over two orthogonally located Txs. The dynamic self-tuning mechanism adapts to the position of the Rx, proving particularly advantageous on curved surfaces.