Space diversity for robust wireless power transmission in multipath environments

Interest in wireless power transmission (WPT) systems has increased remarkably in recent years thanks to their unlimited applications in wireless sensor networks, energy harvesting systems, RFIDs and so on. The key element on the receiving side of a WPT system is the rectenna (rectifier + antenna) which receives electromagnetic power and converts it into electric power. This paper investigates space diversity technique for a WPT system operating in multipath environments. First, a reference rectenna operating at 2.45 GHz is presented. Then, the measurement setup is described with the sleeve dipole transmitting antenna, the movable rectenna receiving system and the configuration of the environment. The results demonstrate that by using two rectennas separated by an optimized distance based on space diversity technique, the phenomenon of deep fading in real environment is considerably mitigated and the DC output signal is rather stable over the position range of the receiver.