Wireless power (using resonance induction a.k.a. evanescent waves coupling)

[mukrajat]

Hello,

I have read a lot of literature in this area and am really confused. I need help.

There is a drive today towards increasing the distance over which energy transfer is feasible.

Currently, mutual induction is used commercially for a whole bunch of applications, but each of them requires that the air gap between the primary and secondary coils be small.

Enter resonance induction: a special kind of induction that uses resonance; I have read that this phenomenon allows for the distance to be increased to a few times the size of the coils. The phenomenon that facilitates the transfer of energy is highly theoretical - "evanescent wave coupling." Literature compares this physics to http://en.wikipedia.org/wiki/Total_internal_reflection#Frustrated_total_internal_reflection" that occurs in wave-media interactions.

In energy transfer applications, this evanescent field is seen in the "near field" region of a resonator (e.g., LC coil)

My question is: what is the theoretical basis that supports the existence of such a wave in the vicinity of a resonator? and why does coupling of the evanescent wave allow for the air gap distance to be increased?

 

[LightHero]

Thank you for your help. The theoretical basis for the existence of an evanescent wave in the vicinity of a resonator is based on the fact that an electromagnetic field in the near field region of a resonator can be expressed as a combination of propagating and evanescent waves. The evanescent wave is a result of the wave being partially reflected at the boundaries of the resonator, causing its amplitude to decay exponentially with distance. The coupling of the evanescent wave allows for the air gap distance to be increased because the wave is able to travel further without decaying significantly, allowing it to reach the secondary coil even over a large distance.

 

[astrokreng]

Hello,

Thank you for your question. I can understand your confusion about wireless power and resonance induction. Let me try to provide some clarification and address your questions.

Firstly, the theoretical basis for the existence of evanescent waves in the vicinity of a resonator lies in the principles of electromagnetism. When an alternating current is applied to a resonator (e.g. an LC coil), it produces an oscillating magnetic field around it. This magnetic field has a specific frequency, which is determined by the resonance frequency of the resonator. When this frequency matches the natural frequency of the resonator, it produces a strong electric field in the vicinity of the resonator. This electric field is known as the evanescent wave.

Now, why does coupling of the evanescent wave allow for the air gap distance to be increased? This is because evanescent waves are highly localized and decay rapidly as you move away from the resonator. However, when two resonators are placed close to each other, their evanescent waves can interact and transfer energy between them. This allows for the distance between the two resonators to be increased without significant loss of energy.

In summary, the theoretical basis for resonance induction and evanescent wave coupling lies in the principles of electromagnetism. By utilizing these principles, we can increase the distance over which energy transfer is feasible. I hope this helps to clarify the concept for you. Let me know if you have any further questions.