Efficient wireless energy transfer
Daniela Vera Maria Manuela Gomez Laura Perez 10B
In the early days of electro-‐ magnetism before the electrical wire grid was released, a lot of interest and effort from engineering was shown towards the development of energy transportation through long distances without any medium carrier. despite all the efforts there were no successful results since their last option was of no use for the expected energy transfer, this option was the omni-‐ dirctional antenna which works very well for information transfer but not for energy, because a huge amount of energy is wasted into free space, but it was then discovered that using lasers or highly directional antennas are efficiently used for energy transfer, even for long distances, although requires an uninterruptable line of sight in a complicated tracking system, making it a not so efficient option.
Nowadays we face a different challenge that even though we have wireless energy we still have schemes that relay on non-‐ radioative mode, but they are restricted to very close range or very low power energy transfers. In result of the investigations the proposed methods for efficient wireless non-‐ radioative mid-‐ range energy transfer is based on resonant coupling, mining that two same frequency resonant objects tend to couple while interacting with other off resonant environmental objects, as well as resonant evanescent coupling, where the coupling mechanism is made through the overlap of the non-‐ radioative near fields of the two objects. This performs at mid-‐ range distances but it has not been proved that it transfer for a few times larger than the largest dimension of both objects involved.
Range and rate of coupling the scheme proposed includes the first subjects of examination, without considering the drainage from the system for use into work. An important framework for modeling this resonant energy exchange is the coupled mode theory( CMT). Strong
coupling rate is required over distances larger that the characteristics sizes of the objects. Since the extend of the near field into the air surrounding afinite sized resonant object is set by the wave length leading to significantly longer evanescent field tails. This has not being thoroughly studied since one prefers short tails to minimize interfering that are accompanies wave high radiation. The proposed scheme is very general and any type of resonant structure can satisfy the requirements and be used. As examples we choose to work with two electromagnetic resonant systems:
• Dielectric disks
• Capacitively loaded conducting wire loops