The concept of wireless power transmission has expanded in many directions, including high-intensity microwave beams, lasers and magnetic induction. More and more companies develop contactless powering products, using distinctive technologies.
- Magnetic induction like in the Duracell power-mats. Or in a variant, like WiTricity uses to transmit power, over distances ranging from centimeters to a meter. The company plans to use this technology to charge Intel-chip powered laptops in the near future.
- Radio waves (electromagnetic waves), like the company Energous does. They make devices which create a 30-foot envelope of wire-free charging space.
- Transmitting power through sound waves, pioneered by uBeam. With this technology they are able to send 25 watts over ten feet.
Above technologies don’t explain Wi-Tap’s replication experiments of Tesla’s Wireless Energy Transmission (WET). Also Wi-tap hasn’t a satisfying explanation at this moment.
The scientific community and other experimenters proposed various explanations for the energy transfer in the WET system. One of the most favoured theories is that an ‘electrical power conducting path’, also called ‘transmission-line wave’ or ‘surface wave’ is created between the TC’s. Energy transmission takes place because of this surface wave, is behaving like a “single-wire” transmission line (see Kenneth and James Corum). But how exactly the conducting path is created is not very clear.
Another idea, called ‘Capacitive Coupling ‘ states that the transfer of energy between the respective TC’s is a result of ‘displacement current’, exactly like the transfer of electrical energy between two closely-spaced plates of a conventional capacitor in a typical AC circuit.
An overview of many of the circulating theories you can find here, but, there’s no agreement.
Tesla speaks about “Electrostatic Induction”, meaning the two distant terminals are electrically coupled together.
Some other thoughts in the post Exploring the Wireless Energy Transfer concept / 2