Determination of the Impedance Parameters of Antennas and the Maximum Power Transfer Efficiency of Wireless Power Transfer

In this paper, we derive formulas that calculate the impedance parameters (Z-parameters) of multiple antennas near objects to analyze wireless power transfer. Furthermore, we propose a method to calculate the impedance parameters of antennas, the maximum power transfer efficiency, and the optimum load impedance of a wireless power transfer system using equivalent current that generate the same electromagnetic field as that generated by an antenna in transmitting mode.