Wireless power collection using radio frequency identification system

A wireless power collection (WPC) system is proposed to harvest excess electromagnetic energies in space that are reflected and not received by target antennas. The radio frequency identification (RFID) system was utilized to demonstrate WPC. The power was transmitted between the reader and tags, and the rectenna (rectified antenna) was used to collect energy in our WPC system. The rectenna includes ultra-high frequency RFID tags. When the distance between the rectenna and the reader was 10 cm, the maximum voltages of a single rectenna and four rectennas in series were measured to be nearly 1.5 and 5.7 V, respectively. This WPC system can be used to supply power to charge batteries or other electronic products. A WPC tree consisted of four sets of rectenna arrays provided a charging current of ∼0.203 mA to a set of four AAA NiMH batteries.