Antenna device and wireless device

• US 9,543,642 B2
• Filed: 11/21/2013
• Issued: 01/10/2017
• Est. Priority Date: 09/09/2011
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Kato, Noboru
• Primary Examiner(s): DUONG, DIEU HIEN
• Application Number:
  US14/085,830
• Publication Number:
  US 20140062827A1
• Time in Patent Office: 1,146 Days
• Field of Search: 343/856, 343/741, 343/866
• US Class Current: 1/1
• CPC Class Codes: G06K 19/07794 the record carrier comprising a booster or auxiliary antenna in addition to the antenna connected directly to the integrated circuit
• CPC Class Codes: H01Q 1/2225 used in active tags, i.e. provided with its own power source or in passive tags, i.e. deriving power from RF signal
• CPC Class Codes: H01Q 1/38 formed by a conductive layer on an insulating support patch antennas H01Q9/0407; microstrip dipole antennas H01Q9/065; microstrip slot antennas H01Q13/106; transmission line microstrip antennas H01Q13/206; manufacturing reflecting surfaces using insulating material for supporting the reflecting surface H01Q15/142
• CPC Class Codes: H01Q 1/50 Structural association of antennas with earthing switches, lead-in devices or lightning protectors
• CPC Class Codes: H01Q 7/00 Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop

Abstract

An RFID tag includes an antenna element and a feed device. The antenna element includes a base sheet and a coil conductor on the upper surface thereof. The feed device includes a feed element and an RFIC. The feed element includes a base sheet and a first coil conductor and a second coil conductor on the upper surface of the base sheet. The first coil conductor and the second coil conductor are arranged on the base sheet such that magnetic flux generated in the first coil conductor and the second coil conductor constitutes a closed magnetic circuit. The feed device is adhered to a coupling portion of the antenna element. As a result, the RFIC is strongly coupled to the antenna element.

Claims

1. An antenna device comprising:

an antenna element including a coupling portion; and

a feed element including a first coil conductor and a second coil conductor, the first coil conductor and the second coil conductor being arranged such that magnetic flux generated in the first coil conductor and the second coil conductor constitutes a closed magnetic circuit;

wherein

the feed element and the antenna element are arranged such that the closed magnetic circuit of the feed element extends around the coupling portion of the antenna element;

the antenna element includes a spiral or loop-shaped coil conductor;

the coupling portion is part of the spiral or loop-shaped coil conductor; and

the feed element is disposed across the coupling portion of the antenna element such that the first coil conductor and the second coil conductor are positioned on respective sides of the coupling portion.

2. The antenna device according to claim 1, wherein the first coil conductor and the second coil conductor respectively have different winding axes and are electrically connected in series to each other.

3. The antenna device according to claim 1, wherein the first coil conductor and the second coil conductor are disposed adjacent to each other on a same plane.

4. The antenna device according to claim 1, wherein the first coil conductor and the second coil conductor are asymmetric to each other.

5. The antenna device according to claim 1, wherein the first coil conductor and the second coil conductor are located on a same base sheet.

6. The antenna device according to claim 1, wherein the antenna element has a resonance frequency that corresponds to a carrier frequency of a communication signal.

7. The antenna device according to claim 1, wherein the antenna element includes a third coil conductor and a fourth coil conductor arranged in a rectangular or substantially rectangular spiral pattern and having winding directions opposite to each other.

8. The antenna device according to claim 7, wherein the third coil conductor and the fourth coil conductor define an LC circuit.

9. The antenna device according to claim 1, wherein the feed element includes a plurality of dielectric base sheets each including a coil conductor pattern located thereon, and via conductors defining inter-layer connections.

10. A wireless device comprising:

an antenna element including a coupling portion; and

a feed element including a first coil conductor and a second coil conductor, the first coil conductor and the second coil conductor being arranged such that magnetic flux generated in the first coil conductor and the second coil conductor constitutes a closed magnetic circuit;

wherein

the feed element and the antenna element are arranged such that the closed magnetic circuit of the feed element extends around the coupling portion of the antenna element;

the antenna element includes a spiral or loop-shaped coil conductor;

the coupling portion is part of the spiral or loop-shaped coil conductor; and

the feed element is disposed across the coupling portion of the antenna element such that the first coil conductor and the second coil conductor are positioned on respective sides of the coupling portion.

11. The wireless device according to claim 10, further comprising a radio frequency integrated circuit that is connected to the first coil conductor and the second coil conductor of the feed element.

12. The wireless device according to claim 11, wherein the radio frequency integrated circuit and the feed element constitute a resonant circuit that resonates at a frequency corresponding to a carrier frequency of a communication signal.

13. The wireless device according to claim 10, wherein the first coil conductor and the second coil conductor respectively have different winding axes and are electrically connected in series to each other.

14. The wireless device according to claim 10, wherein the first coil conductor and the second coil conductor are disposed adjacent to each other on a same plane.

15. The wireless device according to claim 10, wherein the first coil conductor and the second coil conductor are asymmetric to each other.

16. The wireless device according to claim 10, wherein the first coil conductor and the second coil conductor are located on a base sheet.

17. The wireless device according to claim 10, wherein the antenna element has a resonance frequency that corresponds to a carrier frequency of a communication signal.

18. The wireless device according to claim 10, wherein the wireless device is one of an RFID tag, a GPS receiving circuit, a wireless LAN, and a digital TV.