29-11-2012, 05:59 PM
WIRELESS POWER TRANSMISSION
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INTRODUCTION-
Witricity, standing for wireless electricity, is a term coined by MIT researchers, to describe the ability to provide electricity to remote objects without wires. Using self-resonant coils in a strongly coupled regime, efficient non-radiative power transfer over distances of up to eight times the radius of the coils can be done.. Unlike the conduction-based systems, Witricity uses resonant magnetic fields to reduce wastage of power. Currently the project is looking for power transmissions in the range of 100 watts.
HOW IT WORKS-
Wireless light: Researchers used magnetic resonance coupling to power a 60-watt light bulb. Tuned to the same frequency, two 60-centimeter copper coils can transmit electricity over a distance of two meters, through the air and around an obstacle.
The researchers built two resonant copper coils and hung them from the ceiling, about two meters apart.
When they plugged one coil into the wall, alternating current flowed through it,
HOW WIRELESS POWER COULD WORK
1. Power from mains to antenna, which is made of copper
2. Antenna resonates at a frequency of 6.4MHz, emitting electromagnetic waves
3. Tails' of energy from antenna 'tunnel' up to 5m (16.4ft)
4. Electricity picked up by laptop's antenna, which must also be resonating at 6.4MHz.
Long-distance Wireless Power-
Some plans for wireless power involve moving electricity over a span of miles. A few proposals even involve sending power to the Earth from space. The Stationary High Altitude Relay Platform (SHARP) unmanned plane could run off power beamed from the Earth. The secret to the SHARP's long flight time was a large, ground-based microwave transmitter.