Antenna for near field communication, accessory and electronic device including the same

1. An electronic device comprising:

a near field communication (NFC) antenna comprising a first coil, a second coil, and a third coil that are separated from each other; and

a mobile device comprising the first coil,

wherein the second coil and the third coil are arranged on an outside of the mobile device, and the second coil and the third coil are included in an accessory that is removably attachable to the mobile device,

wherein the mobile device comprises an NFC transceiver configured to transmit and receive NFC signals via the first coil, the second coil, and the third coil under control of the mobile device,

wherein when the accessory is attached to the mobile device, a distance between the first coil and the second coil is from approximately 0 mm to approximately 10 mm, and inductive coupling is generated between the first coil and the second coil, and

wherein the second coil and the third coil are overlapped with each other in an area of the accessory, at least one of the second coil and the third coil is arranged in a plurality of layers through a via, and insulating materials are arranged among the plurality of layers.

2. The electronic device of claim 1 , wherein each of the first coil and the second coil has a rectangular spiral form or a helical form.

3. The electronic device of claim 1 , wherein the mobile device further comprises:

an application processor configured to provide a program for exchanging data with an external device, a card program, or a card reader program, and

wherein the NFC transceiver is configured to transmit and receive the NFC signals under control of the application processor.

4. The electronic device of claim 3 , further comprising a matching circuit connected between the NFC transceiver and the first coil of the antenna, the matching circuit comprising an electromagnetic compatibility (EMC) filter comprising inductor elements and capacitor elements,

wherein the capacitor elements are configured to match an impedance between the NFC transceiver and the antenna.

5. The electronic device of claim 1 , wherein the mobile device further comprises:

a hall sensor integrated circuit configured to sense whether the accessory is attached to the mobile device.

6. The electronic device of claim 1 , wherein each of the first coil, the second coil, and the third coil has a rectangular spiral form or a helical form.

7. The electronic device of claim 1 , wherein when the accessory is attached to the mobile device, inductive coupling is generated between the first coil, the second coil, and the third coil.

8. The electronic device of claim 1 , wherein the accessory comprises at least one of the a cover, a sticker, an antiskid pad, a film, an auxiliary battery, and a smart grip.

9. The electronic device of claim 1 , wherein the accessory has a space to accommodate the mobile device therein, and the second coil is provided in an interior of the accessory.

10. The electronic device of claim 1 , wherein the NFC antenna further comprises a fourth coil which is included in the accessory and is separated from the first coil, the second coil, and the third coil.

11. The electronic device of claim 10 , wherein the accessory is a flip cover of the mobile device,

wherein the second coil and the third coil are arranged on a front surface of the flip cover, and

wherein the fourth coil is arranged on a rear surface of the flip cover.

12. The electronic device of claim 10 , wherein the accessory is a flip cover of the mobile device,

wherein the second coil is arranged on a front surface of the flip cover, and

wherein the third coil and the fourth coil are arranged on a rear surface of the flip cover.

13. A near field communication (NFC) antenna comprising:

a first coil that is arranged in a mobile device; and

a second coil and a third coil that are separated from the first coil and are arranged on an outside of the mobile device,

wherein the second coil is included in an accessory that is removably attachable to the mobile device,

wherein the mobile device comprises an NFC transceiver configured to transmit and receive NFC signals via the first coil, the second coil, and the third coil under control of the mobile device,

wherein when the accessory is attached to the mobile device, a distance between the first coil and the second coil is from approximately 0 mm to approximately 10 mm, and inductive coupling is generated between the first coil and the second coil, and

wherein the second coil and the third coil are overlapped with each other in an area of the accessory, at least one of the second coil and the third coil is arranged in a plurality of layers through a via, and insulating materials are arranged among the plurality of layers.

14. The NFC antenna of claim 13 , wherein each of the first coil and the second coil has a rectangular spiral form or a helical form.