Fig. 4From: An improved three-coil wireless power link to increase spacing distance and power for magnetic resonant coupling systemNormalized active power PL as a function of k12 and Q L . LEGEND: The abscissa axis is the coupling coefficient k12 and the load quality factor Q L . They are two important parameters affecting the power. The normalized active power PL is displayed on the ordinate axis. It is a unimodal function of the coupling coefficient and the quality factor. Only when both of them get the appropriate value, can the power reach the maximumBack to article page