Investigation of RF Based Wireless Energy Transmission for Micro-Scale Electronics Devices

Abstract

Wireless energy transmitting is an interesting research topic with design challenges due to low power density in the scale of nano/micro-watt range. In the day to day life, primary and secondary batteries are used in low power devices like sensors. When the batteries are used, they should be replaced or recharged time to time. Therefore wireless energy transmission is a good solution to overcome this difficulty. In addition to that this is a good technology for supplying power to low power devices which are deployed in unreachable places. Radio frequency was selected to transmit power for micro scale power consumption electronics devices. There is an immense amount of un-utilized radio frequency (RF) energy around us all the time. Mobile-phone base stations, radio and television stations, satellites orbiting earth and even the cellular phones are continuously transmitting RF waves throughout the day which lead to scattered RF energy everywhere. The power that is required to power up a modern small circuit is mostly within pW or mW. The pW or mW level of power can be generated using energy harvesters that can generate electricity using RF energy waves. As the demand increases for remote and disposable sensors, there is an increasing interest in battery-less systems that use energy harvesters. The main challenge in this field is to reduce the size of the harvester and to use passive and low power components. The research work was focused to implement a practical solution to the above discussed issues by wireless energy transmission and harvesting enough RF energy to power low power consumption devices. The overall objective was to develop a fully functional micro-scale RF energy transmission and harvesting unit that would be able to power devices which can operate within the pW or mW range. Energy transmission and harvester design, implementation and test results are given in detail. Dipole, isotropic and spiral antennas are used to scavenge the power and comparison of harvested power is displayed under different scenario.