Multi-band design of matched wireless power transfer links

In magnetic resonant wireless power transfer the free-space part of the link can be represented as coupled inductances. By adding appropriate series capacitances (so as to obtain resonance) only an immittance inverter is left. When the value of the immittance inverter is selected equal to the load impedance, no further elements are necessary to accomplish matching. In addition, by considering lossy coupled inductances, it is possible to accurately define the reference impedances which realize the maximum efficiency for the wireless link. By using this principle for different frequencies we can realize a network capable of achieving maximum efficiency for different values of coupling at different frequencies. Numerical and experimental verification of the proposed approach are also presented.