Transmitter and receiver structures for near-field wireless power charging

1. A transmitter structure for delivering wireless power, comprising:

a housing;

a metallic core disposed in an opening defined by the housing; and

one or more magnets, integrated with a surface of the housing, configured to magnetically attract one or more other magnets integrated with a receiver structure in order to bring and maintain the transmitter structure and the receiver structure within a threshold distance from each other,

wherein:

the transmitter structure is configured to carry one or more radio frequency (RF) signals to the metallic core when the receiver structure is within the threshold distance from the transmitter structure, and

the receiver structure is configured to receive and convert the one or more RF signals into usable energy to power an electronic device coupled to the receiver structure.

2. The transmitter structure of claim 1 , wherein the housing is configured to keep desired currents inside the transmitter structure and undesired currents outside of the transmitter structure.

3. The transmitter structure of claim 1 , wherein the surface of the housing includes one or more non-skid regions to resist motion of the receiver structure when the receiver structure is within the threshold distance from the transmitter structure.

4. The transmitter structure of claim 1 , wherein the transmitter structure operates as an open circuit when the receiver structure is not within the threshold distance from the transmitter structure, such that wireless power does not leak from the transmitter structure.

5. The transmitter structure of claim 1 , wherein the surface of the housing is a planar surface configured to be positioned adjacent to a planar surface of the receiver structure when the receiver structure is within the threshold distance from the transmitter structure.

6. The transmitter structure of claim 1 , wherein the housing comprises at least one metamaterial.

7. The transmitter structure of claim 1 , wherein the metallic core is at a center location of the housing.

8. The transmitter structure of claim 1 , wherein:

the transmitter structure is part of a charging device; and

the housing is also part of the charging device.

9. The transmitter structure of claim 1 , further comprising a transmission line that feeds the one or more RF signals.

10. A wearable electronic device for receiving wireless power, comprising:

a receiver structure, including:

a housing;

a metallic core disposed in an opening defined by the housing; and

one or more magnets, integrated with a surface of the housing, configured to magnetically attract one or more other magnets integrated with a transmitter structure in order to bring and maintain the transmitter structure and the receiver structure within a threshold distance from each other,

wherein:

the transmitter structure is configured to transfer one or more radio frequency (RF) signals to the metallic core when the receiver structure is within the threshold distance from the transmitter structure, and

the receiver structure is configured to convert the one or more RF signals into usable energy to power the wearable electronic device.

11. The wearable electronic device of claim 10 , wherein the wearable electronic device is a wearable watch.

12. The wearable electronic device of claim 10 , further comprising a battery, wherein receiver structure is further configured to convert the one or more RF signals into usable energy to charge the battery.

13. The wearable electronic device of claim 10 , further comprising one or more switch elements configured to (i) detect the one or more RF signals transferred by the transmitter structure, and (ii) direct the one or more RF signals to conversion circuitry when a power level of the one or more RF signals exceeds a threshold.

14. The wearable electronic device of claim 13 , wherein the one or more switch elements minimize power surges in the wearable electronic device, thereby protecting components of the wearable electronic device from power-surge related damage.

15. The wearable electronic device of claim 10 , wherein the housing is configured to keep desired currents inside the receiver structure and undesired currents outside of the receiver structure.

16. The wearable electronic device of claim 10 , wherein the threshold distance is less than 10 mm.

17. The wearable electronic device of claim 10 , wherein the receiver structure is further configured to be excited by the one or more RF signals transferred from the transmitter structure when the receiver structure is within the threshold distance from the transmitter structure.

18. The wearable electronic device of claim 10 , wherein the receiver structure further comprises circuitry to convert the one or more RF signals into usable energy to power the wearable electronic device.

19. The wearable electronic device of claim 18 , wherein the circuitry includes a rectifier and a power converter.

20. A wireless charging system comprising:

a transmitter structure comprising:

a first metallic core disposed in an opening of the transmitter structure; and

one or more first magnets; and

a receiver structure comprising:

a second metallic core disposed in an opening of the receiver structure; and

one or more second magnets,

wherein:

the one or more first magnets are configured to magnetically attract the one or more second magnets in order to bring and maintain the transmitter structure and the receiver structure within a threshold distance from each other,

the transmitter structure is configured to transfer one or more radio frequency (RF) signals from the first metallic core to the second metallic core when the receiver structure is within the threshold distance from the transmitter structure, and

the receiver structure is configured to convert the one or more RF signals into usable energy to power an electronic device coupled to the receiver structure.