Wireless Power Transfer - help required

[Navaneeth1989]

I was going through some IEEE papers on wireless power transfer and found that most of them employ a 4 coil system. 2 of them are resonant coils which are typically multi-turn coils and there are 2 single turn coils in each transmitter and receiver. So essentially the transmitter has a single turn coil inductively coupled to the multi-turn coil and the receiver has the same configuration. The 2 multi-turn coils are resonant at a particular frequency. What is the purpose of the single turn coil? Does it provide impedance matching? If so, can someone explain how? The resonant coils are operated at 13.56 MHz

 

[sky_123]

By wireless power transfer, do you mean an RF loop antenna? What are the names of the IEEE papers?

 

[Navaneeth1989]

Analysis, Experimental Results, and Range Adaptation of Magnetically Coupled Resonators for Wireless Power Transfer, IEEE Industrial Electronics, 2011.
Wireless Power Transfer via Strongly Coupled Magnetic Resonances, Science, 2007 - This is the first paper on wireless power carried out in MIT.

 

[sky_123]

Well, the paper tells you that the loop and coil are behaving as a step-up transformer, and that the coil is storing energy like a tank circuit.
It's not something I'm particularly interested it so I don't have much knowledge about it, but the doc has an equivalent circuit.