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.
