Efficiency investigations for wireless resonant energy links realized with resonant inductive coils

Electromagnetic wireless resonant energy links (WRELs) can be realized by using resonant coils coupled via their magnetic fields. By means of a simple equivalent network we investigate the efficiency of WRELs. It is demonstrated that, in order to improve the efficiency, a matching network at the input and output section should be used. In our arrangement the matching network is made by placing the input coupling at a certain position along the helix of the coil, thus realizing an impedance inverter.