# Enhancement of Wireless Power Transfer Efficiency Using Higher Order Spherical Modes

• Kim, Yoon Goo (Department of Electrical Engineering and Computer Science, Seoul National University) ;
• Park, Jongmin (Department of Electrical Engineering and Computer Science, Seoul National University) ;
• Nam, Sangwook (Department of Electrical Engineering and Computer Science, Seoul National University)
• Accepted : 2013.02.21
• Published : 2013.03.31
• 72 8

#### Abstract

We derive the Z-parameters for the two coupled antennas used for wireless power transfer under the assumption that the antennas are canonical minimum scattering antennas. Using the Z-parameter and the maximum power transfer efficiency formula, we determine the maximum power transfer efficiency of wireless power transfer systems. The results showed that the maximum power transfer efficiency increases as the mode number or the radiation efficiency increases. To verify the theory, we fabricate and measure two different power transfer systems: one comprises two antennas generating $TM_{01}$ mode; the other comprises two antennas generating $TM_{02}$ mode. When the distance between the centers of the antennas was 30 cm, the maximum power transfer efficiency of the antennas generating the $TM_{02}$ mode increased by 62 % compared to that of the antennas generating the $TM_{01}$ mode.

#### Keywords

Canonical Minimum Scattering Antenna;Higher Order Mode;Spherical Mode;Wireless Power Transmission

#### Acknowledgement

Supported by : KCA (Korea Communications Agency)

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