Extension of WPT Distance for Folded Dipole Rectenna by Using Parasitic Elements as Directors

This paper proposes a novel method for extending the wireless power transmission distance for the dielectric embedded folded dipole antenna used as received rectenna. Proposed technique adopts parasitic elements to extend transmission distance. The parasitic elements are installed between the power transmission element and the power reception element. The parasitic element is working like directors of Yagi-Uda antenna. When the Yagi-Uda antenna’s principle is applied to the extension of the power transmission distance, problems yield that the element spacing and the shape are restricted. To address the issues, the folded dipole antenna embedded in a dielectric material is adopted for power receiving rectenna to study the wireless power transmission efficiency. It was calculated using electromagnetic field analysis and kQ product when parasitic elements were installed between power transmission and reception antennas. The results exhibited that the wireless power transmission efficiency could be increased by 20% compared to the case where the parasitic elements were not installed. Furthermore, we conducted an LED lighting experiment using a microwave oven as a wave source, and revealed that the distance of wireless power transmission could be extended by 50 mm.