Near-field electromagnetic induction (NFEMI) antenna

1. A near-field electromagnetic induction (NFEMI) antenna, comprising:

an electric antenna including a first electrically conductive planar surface;

a magnetic antenna including a first coil coupled to a second coil;

a first feeding connection coupled to one end of the first coil;

a second feeding connection coupled to another end of the first coil and one end of the second coil;

wherein another end of the second coil is connected to the electrically conductive surface; and

a magnetic permeable material coupled to one side of the magnetic antenna and configured to be placed between the magnetic antenna and a set of electric components;

wherein the first coil is a planar spiral coil; and

wherein the first coil is configured to function as a second electrically conductive surface in the electric antenna by physically facing the first electrically conductive planar surface.

2. The antenna of claim 1 :

wherein the magnetic permeable material is configured to shield the set of electronic components from a magnetic field generated by the coils.

3. The antenna of claim 1 :

wherein the magnetic permeable material is at least one of: a planar sheet, a ferrite shield, a ferrite sheet or a coating comprising ferrite particles in suspension.

4. The antenna of claim 1 :

wherein the magnetic permeable material is configured to spatially amplify magnetic flux generated by the coils toward a direction opposite from the set of electronic components.

5. The antenna of claim 1 :

wherein a position of the first electrically conductive surface is at least one of: between the set of electronic components and the magnetic permeable material or between the magnetic permeable material and the coils.

6. The antenna of claim 1 :

wherein the magnetic permeable material includes an adhesive on one side for adhering to the coils.

7. The antenna of claim 1 :

wherein the first electrically conductive surface and the coils are in a stacked configuration, wherein the first electrically conductive surface defines a first end of the stack and the coils define a second end of the stack.

8. The antenna of claim 7 :

wherein a position of the magnetic permeable material is at least one of: between the coils and the first electrically conductive surface; or at either end of the stack.

9. The antenna of claim 7 :

further comprising a substrate configured to physically separate the coils from the electrically conductive surface in the stack.

10. The antenna of claim 9 :

wherein the substrate is at least one of: a dielectric material, a ferrite material, air, plastic or a polymer.

11. The antenna of claim 1 :

wherein the first electrically conductive surface includes an open end.

12. The antenna of claim 1 :

wherein the first electrically conductive surface is a plate.

13. The antenna of claim 1 :

wherein the first electrically conductive planar surface and the planar spiral coil have substantially matching shapes.

14. The antenna of claim 1 :

wherein the antenna is positioned on a backside of a mobile device or a wearable device.

15. A wearable device, comprising:

an electric antenna including a first electrically conductive planar surface;

a magnetic antenna including a first coil coupled to a second coil;

a first feeding connection coupled to one end of the first coil;

a second feeding connection coupled to another end of the first coil and one end of the second coil;

wherein another end of the second coil is connected to the electrically conductive surface; and

a magnetic permeable material coupled to one side of the magnetic antenna and configured to be placed between the magnetic antenna and a set of electric components;

wherein the electric and magnetic antennas form a near-field electromagnetic induction (NFEMI) antenna;

wherein the first coil is a planar spiral coil; and

wherein the first coil is configured to function as a second electrically conductive surface in the electric antenna by physically facing the first electrically conductive planar surface.

16. The device of claim 15 :

wherein the antenna is embedded in at least one of: a smart watch; a smartwatch housing, a wireless mobile device, an earbud, a hearing aid, a headphone, an activity tracker, or a heart rate monitor.

17. The device of claim 15 :

wherein the antenna is embedded in a transceiver configured to communicate using near-field electromagnetic induction with another wearable device.

18. The device of claim 15 :

wherein the antenna is configured to communicate signals using both magnetic and electric near-field induction.