The research on wireless power transmission using microwaves in recent years has been advanced greatly. In this paper, focusing on the high efficiency of the rectifier circuit including the nonlinear element diode in the rectenna circuit, an optimized antenna and rectifier will be designed and reported. Combining optimized antenna and rectifier, a 2.45 GHz rectenna is prototyped and implemented to the UAV. An experiment which is carried out in the METLAB anechoic chamber demonstrates the four motors of the UAV are successfully rotated with 20W transmitter far from 4 meters from the UAV.