Power Efficiency and Antenna Array Dimension of Middle Range Wireless Power Transmission

Abstract

Recently, long and middle range WPT (wireless power transmission) is very hot issue, which uses RF (radio frequency) beamforming technology. To efficiently provide the power at distance, large dimension of array system is basically required in to the far end power receiver. In this paper, we design an antenna and phase conjugate circuit for Retrodirective Array Antenna (RDA) - based Wireless Power Transfer (WPT) system. In this paper, we design a patch array antenna by applying Electromagnetic Band Gap (EBG) structure and compare the structure and performance without EBG. In this paper, a phase conjugate circuit is designed based on a heterodyne structure. Simulations show that beam directivity is improved by 0.2dBi, 0.45dBi and 0.3dBi at 0, 120 and 180 degree. Simulation results show that the phase conjugation is well performed. So, we can find that the proposed system can be useful for the long and middle range WPT system. Also, we have studied and discussed the system power efficiency for wireless power transmission and antenna array dimension. As a design example, we have introduced the primary design of 5% power efficiency for wireless power transmission at the distance of 4 m. when the center frequency is 2.45GHz. The antenna dimension and the size will be determined by the service style and space consideration and specific application area and so on.