Fractal Base Antennas Effects on Wi-Fi Harvesting Technologies

Abstract

The world is moving towards wireless technologies. Wireless charging is common these days. However, the existing system requires contact between the charging point and the equipment to be charged. True wireless and contactless charging are still under research. In this paper, the aim is to devise a method of charging low powered devices using energy harvested from RF signals given by Wi-Fi routers. Specifically, to show how a fractal-based antenna performs compared to a regular 2.4 GHz Wi-Fi energy harvester. The method of harvesting used here involves a hybrid rectification circuit that boosts the output voltage. For the circuit design, the proposal comprises of a bridgeless converter and a diode bridge. The data is collected using the newly devised method of two fractal-based monopole antennas and two others with varied capacitance. The same test was repeated with another antenna as well as by putting the router at a distance from the antenna and observing the performance of the charging. The third test was performed by placing two routers together at different positions and orientations to check the results with two fractal antennae designs. The first capacitive load used was 4.7uF, which charged to 2.46V in 6 minutes with a 3D Fractal tree antenna. The second capacitor used had a capacitance of 1000uF, and this capacitor took approximately 37 hours to charge to 1.9V with the same antenna.