Efforts of transferring power wirel

Efforts of transferring power wirelessly can be dated back to the early 1900s (long before wired electric power grids) when Nikola Tesla experimented with large-scale wireless power distribution[28]. Due to its large electric fields, which is undesirable for efficient power transfer, Tesla’s invention was never put into practical use.Since then, there was hardly any progress in wireless energy transfer for many decades. In the early 1990s, the need of wireless power transfer reemerged when portable electronic devices became widely spread