Network representation of resonators for wireless power transfer

We introduce a planar substrate-based resonator suitable for magnetic resonant wireless power transfer (WPT) applications. Its advantages are: flatness, limited space occupation, ease of manufacture, low cost and a relatively high Q. Resonators for WPT should operate by using magnetic field coupling and by avoiding external electric fields. In the proposed structure, the electric field is primarily confined inside the substrate, which acts as a capacitor; in this way we avoid unwanted radiation effects and electric field coupling with nearby dielectrics. The paper describes the resonator structure, the field and current distribution, suitable equivalent network modeling, and the mechanism for the resonator feeding. A few resonators, with Q of the order of 250-300, have been built, simulated, and measured confirming the validity of the proposed approach. The resonator structure is easily scalable at different frequencies.