Measurement system, measurement method and new use of antenna

• US 8,525,647 B2
• Filed: 06/30/2006
• Issued: 09/03/2013
• Est. Priority Date: 07/04/2005
• Status: Expired due to Fees

• Current Assignee: Valtion Teknillinen Tutkimuskeskus
• Original Assignee: Valtion Teknillinen Tutkimiskeskus
• Inventors: Varpula, Timo, Nummila, Kaj, Jaakkola, Kaarle, Lajunen, Pentti
• Primary Examiner(s): Lim, Steven
• Assistant Examiner(s): BURGDORF, STEPHEN R
• Application Number:
  US11/988,235
• Publication Number:
  US 20090160612A1
• Time in Patent Office: 2,622 Days
• Field of Search: 340/10.1, 340/10.2, 340/572.7, 340/928, 340/941, 343/700.MS, 343/810, 343/824, 343/702, 343/846, 343/847, 343/772, 343/825, 343/826
• US Class Current: 340/10.2
• CPC Class Codes: G07C 1/24 Race time-recorders
• CPC Class Codes: H01Q 1/2216 used in interrogator/reader equipment
• CPC Class Codes: H01Q 13/206 Microstrip transmission line antennas
• CPC Class Codes: H01Q 21/12 Parallel arrangements of substantially straight elongated conductive units travelling-wave antennas comprising transmission line loaded with transverse elements H01Q11/02; Yagi antennas H01Q19/30

Abstract

The invention relates to a measuring system for detecting radio-frequency tags, a measuring method, and a new use for a leaky waveguide. The measuring system comprises a reading device and an antenna, which is connected to reading device for connecting to the tags. According to the invention, the antenna is a microstrip-type leaky waveguide having a length which is several times the operating wavelength of the tags. The invention permits reliable and precise RFID detection, for example, for a results service for sports events.

Claims

1. A measuring system for detecting radio-frequency tags operating at a predefined wavelength, the system comprising a reading device and an antenna, which is connected to the reading device for connecting to one or more radio-frequency identifier (RFID) tags moving in a direction towards said antenna,

wherein the antenna has a microstrip configuration and a length which is equal to or longer than a multiple of said predefined wavelength of the one or more RFID tags in order to form a leaky waveguide and an elongated detection zone,

said leaky waveguide having the microstrip configuration acting as both a transmission and a reception antenna and being connected to the reading device in order to produce a radio-frequency excitation signal and in order to receive from said one or more RFID tags crossing said elongated detection zone, a return signal powered by the radio-frequency excitation signal, and

wherein the antenna comprises:

a long conductor configured like a wire,

an elongated ground plane in the vicinity of the long conductor and essentially parallel to the long conductor in order to form said elongated detection zone, and

wherein the long conductor is connected at one end to the elongated ground plane.

2. The measuring system according to claim 1, wherein the long conductor comes closer to the elongated ground plane in a tapered manner at least in the vicinity of said one end.

3. The measuring system according to claim 1, wherein the antenna is equipped with a signalling point located essentially at one end of the long conductor, in order to feed radio-frequency energy to the antenna and to lead radio-frequency energy from the antenna.

4. The measuring system according to claim 1, wherein the long conductor is attached at least locally to insulating material, which locks the long conductor'"'"'s position relative to the elongated ground plane.

5. The measuring system according to claim 1, wherein the antenna is arranged as a module, which comprises a common conductive elongated ground plane, at least one long conductor configured like a wire and located mainly at a distance from the elongated ground plane, and an insulating-material layer, which separates the elongated ground plane and the long conductors from each other.

6. The measuring system according to claim 1, wherein the antenna is arranged to form a module, which is adapted to be rolled up in the longitudinal direction of the antenna.

7. The measuring system according to claim 1, wherein the length of the antenna is at least 3 times said predefined wavelength.

8. The measuring system according to claim 7, wherein the length of the antenna is 6-60 times said predefined wavelength.

9. The measuring system according to claim 7, wherein the length of the antenna is 8-30 times said predefined wavelength.

10. The measuring system according to claim 1, wherein a first dimension of the elongated detection zone produced by the antenna is at least 8-times compared to a second direction at right angles, said dimensions being located in the normal plane of the main radiation direction of the antenna.

11. The measuring system according to claim 10, wherein the first dimension of the detection zone produced by the antenna is at least 20-times compared to the second direction at right angles, said dimensions being located in the normal plane of the main radiation direction of the antenna.

12. The measuring system according to claim 1, which comprises several reading devices and antennae, which are correspondingly connected to each other in the said manner, a central computer, and systems for transferring data from the reading devices to the central computer for storage.

13. The measuring system according to claim 1, which comprises in addition results-service software.

14. The measuring system according to claim 1, wherein the antenna is connected to the reading device in order to produce the radio-frequency excitation signal, and in order to receive from the radio-frequency tag the return signal caused by the excitation signal.

15. A measuring system for detecting radio-frequency tags operating at a predefined wavelength, the system comprising a reading device and an antenna, which is connected to the reading device for connecting to one or more radio-frequency identifier (RFID) tags moving in a direction towards said antenna,

wherein the antenna has a microstrip configuration and a length which is equal to or longer than a multiple of said predefined wavelength of the one or more RFID tags in order to form a leaky waveguide and an elongated detection zone,

said leaky waveguide having the microstrip configuration acting as both a transmission and a reception antenna and being connected to the reading device in order to produce a radio-frequency excitation signal and in order to receive from said one or more RFID tags crossing said elongated detection zone, a return signal powered by the radio-frequency excitation signal,

wherein the leaky waveguide comprises at least two one-way long conductors configured like wires in the vicinity of an elongated ground plane, and essentially parallel to the elongated ground plane, in order to form said elongated detection zone,

wherein the at least two one way conductors are electrically connected to the elongated ground plane at one end, and

wherein said leaky waveguide further comprises a signalling point, the signalling point located at a point which permits a quarter-wave phase difference in the at least two one way conductors.

16. The measuring system according to claim 15, wherein the long conductor is attached at least locally to insulating material, which locks the long conductor'"'"'s position relative to the elongated ground plane.

17. The measuring system according to claim 15, wherein the antenna is arranged as a module, which comprises a common conductive elongated ground plane, at least one long conductor configured like a wire and located mainly at a distance from the elongated ground plane, and an insulating-material layer, which separates the elongated ground plane and the long conductors from each other.

18. The measuring system according to claim 15, wherein the antenna is arranged to form a module, which is adapted to be rolled up in the longitudinal direction of the antenna.

19. The measuring system according to claim 15, wherein the length of the antenna is at least 3 times said predefined wavelength.

20. The measuring system according to claim 19, wherein the length of the antenna is 6-60 times said predefined wavelength.

21. The measuring system according to claim 19, wherein the wherein the length of the antenna is 8-30 times said predefined wavelength.

22. The measuring system according to claim 15, wherein a first dimension of the elongated detection zone produced by the antenna is at least 8-times compared to a second direction at right angles, said dimensions being located in the normal plane of the main radiation direction of the antenna.

23. The measuring system according to claim 22, wherein the first dimension of the detection zone produced by the antenna is at least 20-times compared to the second direction at right angles, said dimensions being located in the normal plane of the main radiation direction of the antenna.

24. The measuring system according to claim 15, which comprises several reading devices and antennae, which are correspondingly connected to each other in the said manner, a central computer, and systems for transferring data from the reading devices to the central computer for storage.

25. The measuring system according to claim 15, which comprises in addition results-service software.

26. The measuring system according to claim 15, wherein the antenna is connected to the reading device in order to produce the radio-frequency excitation signal, and in order to receive from the radio-frequency tag the return signal caused by the excitation signal.

27. A method for detecting a radio-frequency (RFID) tag operating at a predefined wavelength, comprising:

radiating power from an antenna in an elongated detection zone sufficient to exceed a threshold value of at least one RFID tag crossing said elongated detection zone, thereby producing a radio-frequency excitation signal, and

receiving a return signal powered by the radio-frequency excitation signal from said at least one RFID tag,

wherein said at least one radio-frequency identifier (RFID) tag is moving in a direction towards the antenna connected to a reading device,

wherein the antenna has a microstrip configuration and has a length which is equal to or longer than a multiple of said predefined wavelength of the at least one RFID tag, forming a leaky waveguide and said elongated detection zone,

wherein the antenna comprises;

a long conductor configured like a wire,

an elongated ground plane in the vicinity of the long conductor and essentially parallel to the long conductor in order to form said elongated detection zone, and

wherein the long conductor is connected at one end to the elongated ground plane.

28. The method according to claim 27, wherein the antenna has a length of at least 3 times said predefined wavelength.

29. The method according to claim 28, wherein the antenna has a length of 6-60 times said predefined wavelength.

30. The method according to claim 28, wherein the antenna has a length of 8-30 times said predefined wavelength.

31. The method according to claim 27, wherein the antenna is arranged as a module, which comprises a common conductive elongated ground plane, at least one long conductor configured like a wire and located mainly at a distance from the elongated ground plane, and an insulating-material layer, which separates the elongated ground plane and the long conductors from each other.

32. The method according to claim 27, being used for monitoring performance of a sportsperson in a results-service system based on radio-frequency tags.

33. The method according to claim 27 being used for warehouse-management.

34. The method according to claim 27 being used for traffic-control.

35. A method for detecting a radio-frequency tag operating at a predefined wavelength, comprising,

radiating power from an antenna with an elongated detection zone sufficient to exceed a threshold value of at least one RFID tag crossing said elongated detection zone, thereby producing a radio-frequency excitation signal, and

receiving a return signal powered by the radio-frequency excitation signal from said at least one RFID tag,

wherein said at least one radio-frequency identifier (RFID) tag is moving in a direction towards the antenna,

wherein the antenna is connected to a reading device,

wherein the antenna has a microstrip configuration and has a length which is equal to or longer than a multiple of said predefined wavelength of the at least one RFID tag, forming a leaky waveguide and said elongated detection zone,

wherein the leaky waveguide comprises at least two long one-way conductors configured like wires in the vicinity of an elongated ground plane, and essentially parallel to the elongated ground plane, in order to form said elongated detection zone,

wherein the at least two one way conductors are electrically connected to the elongated ground plane at one end, and

wherein said leaky waveguide further comprises a signalling point, the signalling point located at a point which permits a quarter-wave phase difference in the at least two one way conductors.

36. The method according to claim 35, wherein the antenna has a length of at least 3 times said predefined wavelength.

37. The method according to claim 36, wherein the antenna has a length of 6-60 times said predefined wavelength.

38. The method according to claim 36, wherein the antenna has a length of 8-30 times said predefined wavelength.

39. The method according to claim 35, wherein the antenna is arranged as a module, which comprises a common conductive elongated ground plane, at least one long conductor configured like a wire and located mainly at a distance from the elongated ground plane, and an insulating-material layer, which separates the elongated ground plane and the long conductors from each other.

40. The method according to claim 35, being used for monitoring performance of a sportsperson in a results-service system based on radio-frequency tags.

41. The method according to claim 35, being used for warehouse-management.

42. The method according to claim 35, being used for traffic-control.