Optimum frequency of high Q-factor resonator for magnetic resonance coupling

In this paper, an efficient wireless power transmission (WPT) method using high Q-factor mu-zero resonators (MZRs) is investigated. Since one-cell of a MZR consists of series inductance and capacitance, it can be analyzed by using a series RLC circuit. To design an efficient WPT system, the maximum Q-factor and the optimum resonance frequency are analytically calculated by adjusting the size of a MZR. It is always observed that one seventh of the total power loss is radiative loss at the optimum resonance frequency. The theoretical and measured results prove that the Q-factor and WPT efficiency are also maximized when the radiation efficiency of the resonator is one-seventh.