Assessment of Opening Hole Patterns on Copper Plate of Metal-Body Housing for Wireless Power Transfer of Mobile Devices

This paper aims to assess the opening hole patterns on copper plates used in the metal-body housing for wireless power transfer in mobile devices. By incorporating these patterns of drilled opening in the back cover housings made of magnesium and aluminum alloys, or copper plates, power transmission efficiency can be boosted. The study involves adding numerous isolated hole areas to the housing, where each small hole acts like an intermediate coil, providing additional space for electromagnetic waves to penetrate the metal-body housing, thereby effectively increasing the amount of transmitted power. To confirm the feasibility of this proposed method, the study also examines the dimensions of the transmitter and receiver coils under different scenarios. It is found that if the coil diameters are too close to the frame of the metal-body housing, more electromagnetic waves may be attracted to the housing, inducing power loss and resulting in lower power transmission efficiency. Therefore, the distance between each isolated metal area and the dimensions of the transmitter and receiver coils need to be carefully considered. Moreover, the study found that narrowing the distance between each isolated metal area benefits the efficiency of wireless power transfer. The test results from this study are useful for design alternatives and enhance the understanding of wireless power transfer in handheld electronic and mobile devices.