Coaxial capacitor loop resonator for wireless power transfer systems

We present a novel resonator, based on a coaxial capacitor, suitable for resonant magnetic-coupled Wireless Power Transfer (WPT) applications. Its advantages are compactness, ease of manufacture and low cost. In our structure, the electric field is primarily confined inside the coaxial cable, while the magnetic field is generated by the currents flowing on the outside conductors. The paper describes the resonator structure and invetigates geometrical trade-offs on the quality factor Q. A few resonators with Q higher than 900, operating around 30 MHz, have been built, simulated and measured confirming the validity of the proposed approach.