Multiband, single feed antenna

• US 6,337,667 B1
• Filed: 11/09/2000
• Issued: 01/08/2002
• Est. Priority Date: 11/09/2000
• Status: Expired due to Term

• Current Assignee: RangeStar Wireless Inc.
• Original Assignee: RangeStar Wireless Inc.
• Inventors: Hill, Rob, Zavala, Juan, Ayala, Enrique
• Primary Examiner(s): LE, HOANGANH T
• Application Number:
  US09/711,263
• Time in Patent Office: 425 Days
• Field of Search: H01/Q.124, H01/Q.916, 343/795, 343/793, 343/700.MS, 343/702, 343/895, 343/803, 343/801, 343/806, 343/818
• US Class Current: 343/795
• CPC Class Codes: H01Q 1/243 with built-in antennas
• 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 5/357 using a single feed point
• CPC Class Codes: H01Q 5/378 Combination of fed elements with parasitic elements
• CPC Class Codes: H01Q 9/28 Conical, cylindrical, cage, strip, gauze, or like elements having an extended radiating surface; Elements comprising two conical surfaces having collinear axes and adjacent apices and fed by two-conductor transmission lines waveguide horns or mouths H01Q13/00; slot antennas H01Q13/00

Abstract

A multiband antenna operates in at least a first frequency band and a second frequency band, a higher frequency band. A dipole has a first conductive leg and a second conductive leg and may be directly fed between the first and second legs. At least a portion of the first leg of the dipole has a meander configuration. The first leg has an electrical length of about one-quarter wavelength, or an odd multiple thereof, in the first frequency band and the second leg has an electrical length of about one-quarter wavelength, or an odd multiple thereof, or more in the first frequency band. A non-driven parasitically-excited conductive element is closely spaced to the first dipole leg and is electrically connected to the second dipole leg. The parasitic element has an electrical length of about one-quarter wavelength, or an odd multiple thereof, in the second frequency band.

Claims

1. A multiband antenna operable in at least a first frequency band and a second frequency band higher in frequency than said first frequency band, comprising

a dipole having a first conductive leg and a second conductive leg, adapted to be directly fed between the first and second legs, at least a portion of the first leg of said dipole having a meander configuration, said first leg having an electrical length of about one-quarter wavelength, or an odd multiple thereof, in said first frequency band and said second leg having an electrical length of about one-quarter wavelength, or an odd multiple thereof, or more in said first frequency band, and

a non-driven parasitically-excited conductive element closely spaced to said first dipole leg and electrically connected to said second dipole leg, said parasitic element having an electrical length of about one-quarter wavelength, or an odd multiple thereof, in said second frequency band.

2. The antenna of claim 1 wherein said dipole legs and said element are conductive traces on a thin dielectric.

3. The antenna of claim 2 wherein said traces are on the same side of said dielectric.

4. The antenna of claim 2 wherein the physical width of said second leg is large with respect to its length in order to widen the antenna bandwidth in the first and second bands.

5. The antenna of claim 2 wherein said conductive traces and thin dielectric are conductive traces on a printed circuit board.

6. The antenna of claim 5 wherein said printed circuit board is rigid.

7. The antenna of claim 5 wherein said printed circuit board is flexible.

8. The antenna of claim 5 wherein said traces are on the same side of said printed circuit board, said antenna further comprising a further conductive trace on the other side of the printed circuit board, said further conductive trace electrically connected to the second leg of said dipole and extending under at least a portion of said second leg and under a portion of said parasitically-excited element.

9. The antenna of claim 5 wherein said traces are on the same side of said printed circuit board, said antenna further comprising a further conductive trace on the other side of the printed circuit board, said further conductive trace having no electrical connection to any other traces on said printed circuit board and extending under a portion of said parasitic element and under at least a portion of the space between the first leg and said parasitically-excited element.

10. The antenna of claim 5 wherein said traces are on the same side of a printed circuit board, said antenna further comprising two further conductive traces on the other side of the printed circuit board, one of said further conductive traces electrically connected to the second leg of said dipole and extending under at least a portion of said second leg and under a portion of said parasitically-excited element, the other of said further conductive traces having no electrical connection to any other traces on said printed circuit board and extending under a portion of said parasitic element and under at least a portion of the space between the first leg and said parasitically-excited element.

11. The antenna of claim 1 wherein the closest portions of the parasitically-excited element and the first dipole leg are spaced about 0.01 to 0.05 wavelength in the second frequency band.

12. The antenna of claim 1 wherein said dipole is an asymmetric dipole in which the electrical length of the second leg is greater than the electrical length of the first leg in said first frequency band.

13. The antenna of claim 12 wherein the configurations of the first and second legs are different from each other.

14. The antenna of claim 13 wherein the configuration of the second leg is substantially linear.

15. The antenna of claim 14 wherein the physical width of said second leg is large with respect to its length in order to widen the antenna bandwidth in the first frequency band.

16. The antenna of claim 1 wherein said second leg has an electrical length greater than the electrical length of said non-driven parasitically-excited element in said second frequency band.

17. The antenna of claim 16 wherein the configurations of the second leg and the non-driven parasitically-excited element are substantially similar.

18. The antenna of claim 17 wherein the configuration of the second leg and the non-driven parasitically-excited element are both substantially linear.

19. The antenna of claim 18 wherein the physical width of said second leg is large with respect to its length in order to widen the antenna bandwidth in the second frequency band.

20. The antenna of claim 1 wherein the first and second legs of the dipole are split and an unbalanced feed is applied to said dipole such that the first leg is fed by the hot side of the feed and the second leg is fed by the ground side of the feed.

21. The antenna of claim 20 wherein the split feed point of the dipole presents substantially the same feed point ohm impedance in said first and second frequency bands.

22. The antenna of claim 21 wherein said feed point impedance is nominally 50 ohms.

23. The antenna of claim 1 wherein the physical width of said parasitically-excited element is large with respect to its length in order to widen its bandwidth.

24. The antenna of claim 23 wherein the average length to width ratio of the parasitically-excited element is in the range of 3 to 10.

25. The antenna of claim 1 wherein said antenna is elongated, having a width substantially narrower than its length.

26. The antenna of claim 1 wherein said first frequency band is the 880-960 MHz band and the second frequency band is the 1850-1990 MHz band.

27. The antenna of claim 1 wherein said first frequency band is the 1850-1990 MHz band and the second frequency band is the 2.4-2.5 GHz band.

28. The antenna of any one of claims 1 and 20-24 wherein said first frequency band is the 880-960 MHz band and the second frequency band is the band of frequencies between 1850 MHz and 2.5 GHz band that includes the 1850-1990 MHz band and the 2.4-2.5 GHz band.

29. The antenna of claim 1 wherein said first frequency band is the 880-960 Mhz band and the second frequency band is the 5.15-5.25 GHz band.

30. A multiband antenna operable in at least a first frequency band and a second frequency band higher in frequency than said first frequency band, comprising

a dipole having a first leg and a second leg, adapted to be directly fed between the first and second legs, at least a portion of the first leg of said dipole having a meander configuration, said first leg having an electrical length of about one-quarter wavelength, or an odd multiple thereof, in said first frequency band and said second leg having an electrical length of about one-quarter wavelength, or an odd multiple thereof, or more in said first frequency band, wherein the legs of said dipole are conductive traces on the first side of a thin dielectric, and

a further conductive trace on the second side of the thin dielectric located underneath a portion of the meander configuration, the further conductive trace having no connection to any other trace, said further conductive trace shaped, sized and positioned under said meander portion so as to create an LC trap that electrically decouples a portion of the first leg when the antenna operates in said second frequency band such that the remaining portion of the first leg has an effective electrical length of about one-quarter wavelength, or an odd multiple thereof, in said second frequency band.

31. The antenna of claim 30 wherein at least a portion of the meander configuration folds back on itself at least twice and wherein said further conductive trace is located underneath a portion of the meander portion of the first leg that folds back upon itself at least twice.

32. An antenna according to claim 31 wherein said meander portion that folds back on itself at least twice has three segments generally parallel to each other in which at least two of the segments are substantially linear.

33. The antenna of claim 30 wherein the physical width of said second leg is large with respect to its length in order to widen the antenna bandwidth in the first and second bands.

34. The antenna of claim 30 wherein said dipole is an asymmetric dipole in which the electrical length of the second leg is greater than the electrical length of the first leg in said first frequency band.

35. The antenna of claim 34 wherein the configurations of the first and second legs are different from each other.

36. The antenna of claim 35 wherein the configuration of the second leg is substantially linear.

37. The antenna of claim 36 wherein the physical width of said second leg is large with respect to its length in order to widen the antenna bandwidth in the first frequency band.

38. The antenna of claim 30 wherein the first and second legs of the dipole are split and an unbalanced feed is applied to said dipole such that the first leg is fed by the hot side of the feed and the second leg is fed by the ground side of the feed.

39. The antenna of claim 38 wherein the split feed point of the dipole presents substantially the same feed point ohm impedance in said first and second frequency bands.

40. The antenna of claim 39 wherein said feed point impedance is nominally 50 ohms.

41. The antenna of claim 30 wherein said first frequency band is the 880-960 MHz band and the second frequency band is the 1850-1990 MHz band.

42. The antenna of claim 30 wherein said first frequency band is the 1850-1990 MHz band and the second frequency band is the 2.4-2.5 GHz band.

43. A multiband antenna operable in at least a first frequency band, a second frequency band higher in frequency than said first frequency band, and a third frequency band higher in frequency than the first and second frequency bands, comprising

a dipole having a first leg and a second leg, adapted to be directly fed between the first and second legs, at least a portion of the first leg of said dipole having a meander configuration, said first leg having an electrical length of about one-quarter wavelength, or an odd multiple thereof, in said first frequency band and said second leg having an electrical length of about one-quarter wavelength, or an odd multiple thereof, or more in said first frequency band,

a non-driven parasitically-excited element closely spaced to said first dipole leg and electrically connected to said second dipole leg, said parasitic element having an electrical length of about one-quarter wavelength, or an odd multiple thereof, in said second frequency band,

wherein said dipole and said parasitically-excited element are conductive traces on the same side of a thin dielectric, and

a further conductive trace on the second side of the thin dielectric located underneath a portion of the meander configuration, the further conductive trace having no connection to any other, said further conductive trace shaped, sized and positioned under said meander portion so as to create an LC trap that electrically decouples a portion of the first leg when the antenna operates in said third frequency band such that the remaining portion of the first leg has an effective electrical length of about one-quarter wavelength, or an odd multiple thereof, in said third frequency band.

44. The antenna of claim 43 wherein the physical width of said second legs is large with respect to its length in order to widen the antenna bandwidth in the first and second bands.

45. The antenna of claim 43 wherein said conductive traces and thin dielectric are conductive traces on a printed circuit board.

46. The antenna of claim 45 wherein said printed circuit board is rigid.

47. The antenna of claim 45 wherein said printed circuit board is flexible.

48. The antenna of claim 43 wherein the closest portions of the parasitically-excited element and the first dipole leg are spaced about 0.01 to 0.05 wavelength in the second frequency band.

49. The antenna of claim 43 wherein said dipole is an asymmetric dipole in which the electrical length of the second leg is greater than the electrical length of the first leg in said first frequency band.

50. The antenna of claim 43 wherein the first and second legs of the dipole are split and an unbalanced feed is applied to said dipole such that the first leg is fed by the hot side of the feed and the second leg is fed by the ground side of the feed.

51. The antenna of claim 50 wherein the split feed point of the dipole presents substantially the same feed point ohm impedance in said first and second frequency bands.

52. The antenna of claim 51 wherein said feed point impedance is nominally 50 ohms.

53. The antenna of claim 43 wherein the average length to width ratio of the parasitically-excited element is in the range of 3 to 10.

54. The antenna of claim 43 wherein said antenna further comprising a further conductive trace on the second side of the thin dielectric, said further conductive trace electrically connected to the second leg of said dipole and extending under at least a portion of said second leg and under a portion of said parasitically-excited element.

55. The antenna of claim 43 wherein said antenna further comprising a further conductive trace on the second side of the printed circuit board, said further conductive trace having no electrical connection to any other traces on said printed circuit board and extending under a portion of said parasitic element and under at least a portion of the space between the first leg and said parasitically-excited element.

56. The antenna of claim 43 wherein said antenna is elongated, having a width substantially narrower than its length.

57. The antenna of claim 43 wherein said first frequency band is the 880-960 MHz band, the second frequency band is the band of frequencies between 1850 MHz and 2.5 GHz band that includes the 1850-1990 MHz band and the 2.4-2.5 GHz band, and the third frequency band is the 5.15-5.25 GHz band.