DUAL-BAND ANTENNA

• US 20080278391A1
• Filed: 05/07/2007
• Published: 11/13/2008
• Est. Priority Date: 05/07/2007
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Mayer, Lukas W.
• Granted Patent: US 8,174,454 B2
• Time in Patent Office: Days
• US Class Current: 343/725
• 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 21/28 Combinations of substantially independent non-interacting antenna units or systems multiple beam H01Q25/00
• 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
• CPC Class Codes: H01Q 9/27 Spiral antennas

Abstract

Dual-band antenna including a shorted loop slot antenna and a spiral antenna.

Claims

1. A dual-band antenna, comprising a shorted loop slot antenna, and a spiral antenna.

2. The dual-band antenna of claim 1, wherein the shorted loop slot antenna has a resonance frequency which is two orders of magnitude higher than a resonance frequency of the spiral antenna.

3. The dual-band antenna of claim 2, wherein the shorted loop slot antenna is an ultra-high-frequency (UHF) band antenna.

4. The dual-band antenna of claim 3, wherein the shorted loop slot antenna has a resonance frequency lying between 860 MHz and 960 MHz.

5. The dual-band antenna of claim 3, wherein the spiral antenna is a high-frequency (HF) band antenna.

6. The dual-band antenna of claim 5, wherein the spiral antenna has a resonance frequency of 13.56 MHz.

7. The dual-band antenna of claim 5, further comprising:

a non-conducting carrier with a top side and a bottom side;

metallizations on the top side of the carrier; and

metallizations on the bottom side of the carrier.

8. The dual-band antenna of claim 7, wherein the carrier has a thickness smaller than 100 μ

m.

9. The dual-band antenna of claim 8, wherein the carrier has dimensions smaller than 71 mm×

44 mm.

10. The dual-band antenna of claim 7, wherein the shorted loop slot antenna comprises an outer ring and a plate surrounded by the outer ring to form a loop slot in the metallizations on the top side of the carrier.

11. The dual-band antenna of claim 10, further comprising a short electrically connecting the outer ring to the plate.

12. The dual-band antenna of claim 10, wherein the plate and the outer ring are electrically connected.

13. The dual-band antenna of claim 12, wherein the plate comprises a cut-out to form an inner ring.

14. The dual-band antenna of claim 13, wherein a bypass strip couples a side of the inner ring to an opposite side of the inner ring.

15. The dual-band antenna of claim 14, wherein the bypass strip is coupled by capacitors which conduct at ultra-high-frequencies (UHF) and do not conduct at high-frequencies (HF), the capacitors comprising a first metallization on the bottom side of the carrier which extends at least over the metallization of one side of the inner ring to the metallization of the opposite side of the inner ring.

16. The dual-band antenna of claim 15, wherein the inner ring comprises a non-conducting gap cutting through the inner ring.

17. The dual-band antenna of claim 16, further comprising a second metallization on the bottom side of the carrier which extends at least across the non-conducting gap in the inner ring,

wherein the second metallization, the carrier and the metallization on each side of the non-conducting gap in the inner ring form two capacitors, each having a capacitance so that ultra-high-frequencies (UHF) are conducted and high-frequencies (HF) are not conducted across the gap in the inner ring.

18. The dual-band antenna of claim 17, wherein the outer ring comprises a non-conducting gap cutting through the outer ring.

19. The dual-band antenna of claim 18, further comprising a third metallization on the bottom side of the carrier which extends at least across the non-conducting gap in the outer ring,

wherein the third metallization, the carrier and the metallization on each side of the gap in the outer ring form two capacitors, each having a capacitance so that ultra-high-frequencies (UHF) are conducted and high-frequencies (HF) are not conducted across the gap in the outer ring.

20. The dual-band antenna of claim 19, wherein the resonance frequency of the shorted loop slot antenna is determined by a loop slot length.

21. The dual-band antenna of claim 19, wherein the input impedance of the shorted loop slot antenna is determined by a loop slot length.

22. The dual-band antenna of claim 19, wherein the input impedance of the shorted loop slot antenna is determined by a feed position along the loop slot.

23. The dual-band antenna of claim 22, wherein the input impedance of the shorted loop slot antenna is determined by a width of the loop slot.

24. The dual-band antenna of claim 19, wherein the spiral antenna is formed in the metallization on the top side of the carrier and

comprises turns of conductor arranged around the outer ring of the shorted loop slot antenna, or

comprises turns of conductor arranged inside the inner ring of the shorted loop slot antenna.

25. The dual-band antenna of claim 24, wherein additional turns of conductor for the spiral antenna comprise the outer ring and the inner ring of the shorted loop slot antenna.

26. The dual-band antenna of claim 24, wherein the resonance frequency of the spiral antenna is determined by the number of conductor turns of the spiral antenna.

27. The dual-band antenna of claim 26, further comprising fourth and fifth metallizations on the bottom side of the carrier for altering the capacitance of the spiral antenna to tune the center frequency of the spiral antenna.

28. The dual-band antenna of claim 24, wherein a quality factor of the spiral antenna is determined by the conductor width of its conductor turns.

29. The dual-band antenna of claim 1, wherein an electronic chip is coupled in parallel to the shorted loop slot antenna and spiral antenna.

30. The dual-band antenna of claim 29, wherein the electronic chip is coupled to the inner ring and the outer ring.

31. The dual-band antenna of claim 30, wherein the electronic chip is electrically connected to sixth and seventh metallizations on the bottom side of the carrier.

32. The dual-band antenna of claim 31, further comprising:

a non-conducting carrier with a top side and a bottom side,

wherein the shorted loop slot antenna comprises an outer ring and a plate surrounded by the outer ring, and the plate comprises a cut-out to form an inner ring;

a first metallization on the bottom side of the carrier which extends at least over metallization of one side of the inner ring to metallization of the opposite side of the inner ring;

a second metallization on the bottom side of the carrier which extends at least across a non-conducting gap in the inner ring; and

fourth and fifth metallizations on the bottom side of the carrier for altering the capacitance of the spiral antenna to tune the center frequency of the spiral antenna,

wherein the first metallization, the second metallization, the fourth metallization and the sixth metallization are electrically connected.

33. The dual-band antenna of claim 32, further comprising a third metallization on the bottom side of the carrier which extends at least across a nonconducting gap in the outer ring,

wherein the third metallization, the fifth metallization and the seventh metallization are electrically connected.

34. The dual-band antenna of claim 33, wherein the electronic chip is electrically connected to the inner ring by means of a first via.

35. The dual-band antenna of claim 34, wherein the electronic chip is electrically connected to an outermost turn of the spiral antenna by means of a second via.

36. The dual-band antenna of claim 24, wherein at least one of the inner ring, the outer ring and the turns of conductors have a rectangular, circular or elliptical shape.

37. A contactless data storage medium comprising the dual-band antenna of claim 1.

38. The contactless data storage medium of claim 37, wherein the contactless data storage medium is a radio frequency identification tag or a smart card.

39. A dual-band antenna, comprising:

a shorted loop slot antenna comprising an inner ring and an outer ring, each ring comprising a non-conducting gap;

a spiral antenna comprising a plurality of conductor turns arranged around the outer ring of the shorted loop slot antenna or comprising a plurality of conductor turns arranged inside the inner ring of the shorted loop slot antenna; and

a switch connected to the shorted loop slot antenna and the spiral antenna such that

at a UHF frequency the gaps of inner ring and the outer ring are electrically shorted, and

at a HF frequency the inner ring and the outer ring are connected in series to each other and in series to the plurality of conductor turns of the spiral antenna.

40. The antenna of claim 39, wherein the switch comprises capacitors conducting at the UHF frequency and non-conducting at the HF frequency.

41. A dual-band antenna, comprising:

a shorted loop slot antenna;

a spiral antenna; and

a switching means for permitting the dual-band antenna to operate in the UHF ultra-high-frequency band and the HF high-frequency band.