Here, the goal is to reduce the operational frequency of power transfer. One solution to reduce the resonant frequency
of object is to add a large external capacitor (“large external capacitor” means that its value exceeds the coil’s self capacitance). Such systems have been discussed in Ref.[3] and Ref.[7]. In figure 12, a capacitive-loaded helical coil is presented. In order to calculate the quality factor of such a coil the inductance, self capacitance, and resistance must be evaluated.