摘要 |
Systems and methods for low loss wireless power transmission are described herein. In one aspect, a transmission coil for transmitting wireless power comprises a first and second spiral coil. Each spiral coil comprises a plurality of turns. A center of the first spiral coil to an outermost turn of the first spiral coil defines a first cross section, and a center of the second spiral coil to an outermost turn of the second spiral coil defines a second cross section. Portions of the first spiral coil along the first cross section and the second spiral coil along the second cross section have a mutual inductance with respect to a receive coil greater than 65% of a maximum mutual inductance along the first and second cross sections. The second spiral coil is counter-wound relative to the first spiral coil. |