Wireless Electricity or Witricity


The technology used for wireless power transmission is known as witricity. Wireless power transmission is not a new idea, Nikola Tesla proposed theories of wireless power transmission in the late 1800s and early 1900s. Tesla's work was impressive, but it did not immediately lead to wide spread practical methods for wireless power transmission. Since then many researchers have developed several techniques for moving electricity over long distances without wires. Some exist only as theories or prototypes, but others are already in use. In 2006 researchers at Massachusetts Institute of Technology led by Marine Soijacic discovered an efficient way to transfer power between coils separated by a few meters. They have dubbed this technology as witricity. Witricity is based upon coupled resonant objects.

Radio And Microwave

If resonance is incorporated or not, induction generally sends wireless power over relatively short distance. For very long distance power transmission radio and microwaves are used. Japanese researcher YAGI developed a directional array antenna known as YAGI antenna for wireless energy transmission. It is widely used for broadcasting and wireless telecommunications industries. While it did not prove to be particularly useful for power transmission. Power transmission via radio waves can be made more directional, allowing longer distance power beaming, with shorter wavelengths of electromagnetic radiation, typically in the microwave range. A rectenna is a rectifying antenna, an antenna used to convert microwaves into DC power. Being that an antenna refers to any type of device that converts electromagnetic waves into electricity or vice versa. A rectenna is simply a microwave antenna.

Wireless Electricity ppt

Micro Wave Power Transmission Has Some Drawbacks

» The solar power stations on the moon would require supervision and maintenance. In other words, the project would require sustainable, manned moon bases.

» Only part of the earth has a direct line of sight to the moon at any given time.

Witricity In History

Wireless power transmission is not a new idea. Nickola Tesla demonstrated transmission of electrical energy without wires in early 19th century. Tesla used electromagnetic induction systems. William C Brown demonstrated a micro wave powered model helicopter in 1964. This receives all the power needed for flight from a micro wave beam. In 1975 Bill Brown transmitted 30kW power over a distance of 1 mile at 84% efficiency without using cables. Researchers developed several technique for moving electricity over long distance without wires.

Witricity At Present

In 2006 MIT researchers discovered a new method to provide electricity to remote objects without wires. Wiricity is based on coupled resonant objects. In 2007 researchers implemented a prototype using self resonant coils. In this first experiment they demonstrated efficient non-radiative power transfer over distance up to eight times the radius of the coils. This experiment was done using two copper coils. Each coil act as self resonant system. One of the coils is attached to the electricity source. Instead of irradiating the environment with electromagnetic waves, it fills the space with a non-radiative magnetic field oscillating at MHz frequencies. The non-radiative field mediates the power exchange with the other coil, which is specially designed to resonate with the field.


Witricity is in development stage, lots of work is to be done to use it for wireless power applications. Currently the project is looking for power transmission in the range of 100w. Before the establishment of this technology the detailed study must be done to check whether it cause any harm on any living beings.