Wireless power transmission

A method of manufacturing a power transmitting unit, comprising:

• forming a transmit coil configured to generate a magnetic field to wirelessly power a device within an active wireless charging area;
• conductively coupling a power source to transmit an alternating electrical current to an input terminal of the transmit coil;
• conductively coupling a plurality of reactive elements placed in series with the transmit coil, wherein the plurality of reactive elements attach to the transmit coil at least a quarter of a turn from the input terminal;
• and
• conductively coupling a controller to the transmit coil to modify a reactance value of the reactive elements to adjust a current distribution of the transmit coil in response to detecting a characteristic of a power receiving unit or a change in the transmit coil of the power transmitting unit.

A wireless charger, comprising:

• a transmit coil configured to generate a magnetic field to wirelessly power a device within an active wireless charging area;
• a power source to transmit an alternating electrical current to an input terminal of the transmit coil;
• a plurality of reactive elements placed in series with the transmit coil, wherein the plurality of reactive elements attach to the transmit coil at least a quarter of a turn from the input terminal;
• and
• a controller to modify a reactance value of the plurality of reactive elements to adjust a current distribution of the transmit coil in response to detecting a characteristic of a power receiving unit with a metal backing, the characteristic comprising a size of the power receiving unit, or a coupling distance between the power transmitting unit and the power receiving unit.