Scavenging Residual Energy from Wi-Fi Sources Using a Rectenna Circuit

With the increasing popularity of wireless devices, the need to develop ways to charge, or to expand the battery life, also increases. This paper proposes a hybrid rectification circuit for collecting energy from nearby Wi-Fi networks. The circuit scavenges the energy emitted, but not used, by routers when they send information through the air, and stores the energy within a capacitor. The proposed architecture consists of two main building blocks: a bridgeless converter, and a diode bridge. The incident power on the antenna of the harvester is passed through the network of the LC lumped circuit, which helps in rectifying and boosting the voltage level. The second building block takes the output of the first block and further rectifies it, helping to further enhance voltage. The proposed system has been tested by using two distinct capacitive loads: 0.47 uF and 1000 uF. It was found that in the case of 1000 uF, the capacitor was able to charge 2.47 V within a span of 16.5 hours when kept directly next to the transmitting source antenna. In the case of 0.47 uF, it was able to charge within a span of 12 hours when kept 10 feet away from the transmitting source. The energy stored was used to light an LED, which was successful in the proximity circuit, albeit briefly.