Practical Considerations for Resonant Near Field Wireless Power Transfer over Common Ground

Wireless power transfer (WPT) schemes need to be both efficient and practical. When the receiver is hovering close to the charging region the alignment requirements for high efficiency should not be so stringent that a practical system cannot be built. Experimental results for the basic scheme show that when two identical helical antennas are placed on opposite sides of a ground plane strong coupling is possible in the near field when the axes of the antennas are aligned. Starting with these experimental findings this paper explores, through simulation and analysis, a range of important variations of the basic scheme that allow efficient and practical power transfer.