System and method for per beam elevation scanning

• US 6,188,373 B1
• Filed: 03/04/1998
• Issued: 02/13/2001
• Est. Priority Date: 07/16/1996
• Status: Expired due to Term

• Current Assignee: Kathrein-Werke KG. (Kathrein SE)
• Original Assignee: Metawave Communications Corp.
• Inventors: Martek, Gary Allen
• Primary Examiner(s): Ho, Tan
• Application Number:
  US09/034,471
• Time in Patent Office: 1,077 Days
• Field of Search: 343/853, 343/893, 343/846, 343/848, 343/890, 343/891, 342/371, 342/372, 342/373, 342/374, 342/375
• US Class Current: 343/893
• CPC Class Codes: H01Q 1/246 specially adapted for base stations
• CPC Class Codes: H01Q 1/362 for broadside radiating helical antennas
• CPC Class Codes: H01Q 11/08 Helical antennas
• CPC Class Codes: H01Q 19/10 using reflecting surfaces
• CPC Class Codes: H01Q 19/108 Combination of a dipole with a plane reflecting surface H01Q19/106 takes precedence; strip line H01Q9/065
• 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
• CPC Class Codes: H01Q 21/205 providing an omnidirectional coverage turnstile aerials H01Q21/26
• CPC Class Codes: H01Q 25/00 Antennas or antenna systems providing at least two radiating patterns arrangements for changing or varying the orientation or the shape of the directional pattern H01Q3/00
• CPC Class Codes: H01Q 3/242 Circumferential scanning
• CPC Class Codes: H01Q 3/26 varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture H01Q3/12, H01Q3/22, H01Q3/24 take precedence
• CPC Class Codes: H01Q 9/18 Vertical disposition of the antenna
• CPC Class Codes: H01Q 9/32 Vertical arrangement of element H01Q9/40 takes precedence

Abstract

Systems and methods are disclosed for providing elevation scanning for a multiple beam antenna system on a per antenna beam basis. In a preferred embodiment columns of antenna elements are divided into sub-groups each having a beam forming matrix associated therewith. Phase differentials are introduced into the antenna beam signals of each sub-group of antenna elements in order to provide a phase progression which steers the antenna beam a predetermined angle from the broadside. The phase differentials are independently provided for each antenna beam signal to thereby allow independent steering of each antenna beam. Additionally, dielectric material placed in the signal feed path may be utilized to alter radiation characteristics of certain antenna elements of the antenna system. Placing the dielectric material with outer elements of an array may be used for aperture tapering and side lobe control. Additionally, wind loading, due to the antenna system is reduced by using a gridded ground plane system.

Claims

1. A system for providing adjustable elevation scanning per antenna beam of a multibeam phased array, wherein said phased array includes a plurality of antenna elements divisible as an upper sub-group and a lower sub-group, said system comprising:

first means for coupling a first signal path to said upper sub-group of antenna elements and to said lower sub-group of antenna elements, wherein said first coupling means provides a first phase differential between signals associated with said upper and lower sub-groups of antenna elements, and wherein said first signal path is associated with a first antenna beam of said multibeam phased array; and

second means for coupling a second signal path to said upper sub-group of antenna elements and to said lower sub-group of antenna elements, wherein said second coupling means provides a second phase differential between signals associated with said upper and lower sub-groups of antenna elements, and wherein said second signal path is associated with a second antenna beam of said multibeam phased array.

2. The system of claim 1, wherein said first coupling means comprises:

a first beam forming signal feed matrix associated with said upper sub-group of antenna elements; and

a second beam forming signal feed matrix associated with said lower sub-group of antenna elements.

3. The system of claim 2, wherein at least one of said first and second beam forming signal feed matrixes is removed from the locality of said multibeam phased array.

4. The system of claim 2, wherein said multibeam phased array includes a plurality of interlocking antenna columns each including an upper portion and a lower portion associated with said upper sub-group and said lower sub-group respectively, wherein said interlocking of said antenna columns is at least in part defined by coupling of ones of said antenna columns to said first signal path by said first and second beam forming signal feed matrixes.

5. The system of claim 2, wherein said first coupling means further comprises:

a splitter/combiner coupling said first signal path to said first and second beam forming signal feed matrixes.

6. The system of claim 2, wherein said first phase differential is provided by a means for introducing a delay in a signal path associated with said second beam forming signal feed matrix coupled to said first signal path.

7. The system of claim 6, wherein said delay means comprises a removable predetermined length of transmission cable adapted to provide a predetermined angle of elevation scanning.

8. The system of claim 7, wherein said predetermined length of transmission cable is selected from a plurality of predetermined lengths of transmission cable each of which are adapted to provide a different predetermined angle of elevation scanning.

9. The system of claim 6, wherein said delay means comprises an in-phase and quadrature signal combiner adapted to provide a predetermined angle of elevation scanning.

10. The system of claim 6 wherein said delay means comprises an adjustable delay device providing a plurality of selectable angles of elevation scanning.

11. The system of claim 10, wherein said adjustable delay device includes a plurality of switchably selectable lengths of transmission cable.

12. The system of claim 10, wherein said adjustable delay device includes a continuously adjustable length signal path.

13. The system of claim 10, further comprising:

means for automatically adjusting said adjustable delay device.

14. The system of claim 1, wherein said plurality of antenna elements of said phased array is also divisible as an intermediate sub-group of antenna elements, and wherein said first coupling means also couples said first signal path to said intermediate sub-group of antenna elements, said first coupling means providing a third phase differential between signals associated with said upper and intermediate sub-groups of antenna elements.

15. The system of claim 14, wherein said first phase differential has a predetermined proportional relationship to said third phase differential.

16. The system of claim 1, wherein said upper sub-group of antenna elements includes at least two rows of antenna elements at least one of which is disposed vertically higher than another row.

17. The system of claim 16, wherein said lower sub-group of antenna elements includes at least two rows of antenna elements at least one of which is disposed vertically higher than another row.

18. The system of claim 16, wherein a phase differential is provided between elements of said at least two rows of antenna elements.

19. The system of claim 1, further comprising:

means for retarding the propagation velocity of electromagnetic energy distributed by said first coupling means to ones of said upper sub-group and lower sub-group of antenna elements.

20. The system of claim 19, wherein the antenna elements of the sub-groups of antenna elements coupled to the retarding means are more closely spaced to a next adjacent antenna element than are the antenna elements of the remaining sub-groups of antenna elements.

21. The system of claim 19, wherein said retarding means comprises:

means for attenuating the amplitude of radiated energy associated with the sub-groups of antenna elements coupled to the retarding means with respect to the amplitude of radiated energy associated with the remaining sub-groups of antenna elements.

22. The system of claim 19, wherein said retarding means comprises:

means for attenuating the amplitude of radiated energy associated with ones of the antenna elements of the sub-groups of antenna elements coupled to the retarding means with respect to the amplitude of radiated energy associated with other ones of the antenna elements of the sub-groups of antenna elements coupled to said retarding means.

23. The system of claim 19, wherein said retarding means comprises:

a plurality of antenna column feed buses ones of which are coupled to antenna elements of said upper sub-group of antenna elements and other ones of which are coupled to antenna elements of said lower sub-group of antenna elements, wherein ones of said feed buses have a dielectric material disposed between the feed bus and said coupled one of said sub-group of antenna elements and other ones of said feed buses have an air space disposed between the feed bus and said coupled one of said sub-group of antenna elements.

24. The system of claim 23, wherein at least one of said dielectric buses includes a dielectric material having a dielectric constant greater than that of another of said dielectric buses.

25. The system of claim 23, wherein at least one of the dielectric buses is adapted to provide amplitude attenuation.

26. The system of claim 25, wherein said at least one dielectric bus includes a lossy composite in a portion of said dielectric material.

27. The system of claim 26, wherein said lossy composite is distributed in different densities in said portion of said dielectric material.

28. A method for providing independent adjustable elevation scanning for antenna beams of a multibeam array, wherein said array includes a plurality of antenna elements divisible as a first sub-group and a second sub-group, said method comprising the steps of:

coupling a first signal path to said first and second sub-groups of antenna elements, wherein said first signal path is associated with a first antenna beam of said array;

introducing a first phase differential between signals associated with said first and second sub-groups of antenna elements;

coupling a second signal path to said first and second sub-groups of antenna elements, wherein said second signal path is associated with a second antenna beam of said array; and

introducing a second phase differential between signals associated with said first and second sub-groups of antenna elements.

29. The method of claim 28, wherein said first phase differential is introduced only with respect to a signal associated with said first signal path.

30. The method of claim 28, wherein said step of introducing a first phase differential includes the step of:

selecting a predetermined delay in a signal path associated with said second sub-group of antenna elements.

31. The method of claim 28, wherein said step of coupling a first signal path comprises the steps of:

coupling a first beam forming signal feed network between said first signal path and said first sub-group of antenna elements; and

coupling a second beam forming signal feed network between said first signal path and said second sub-group of antenna elements.

32. The method of claim 31, wherein said step of coupling a first signal path further comprises the step of:

coupling a signal splitter/combiner to said first signal path and each of said first and second beam forming signal feed networks.

33. The method of claim 31, wherein said first phase differential is introduced by a delay in a signal path associated with said second beam forming signal feed network.

34. The method of claim 32, wherein said delay comprises a removable predetermined length of transmission cable.

35. The method of claim 33, wherein said delay comprises an adjustable delay device.

36. The method of claim 35, further comprising the step of:

automatically adjusting said adjustable delay device.

37. The method of claim 28, further comprising the step of:

retarding the propagation velocity of electromagnetic energy distributed by said first signal path to ones of said first and second sub-groups of antenna elements.

38. The method of claim 37 further comprising the step of:

spacing the antenna elements of the sub-groups of antenna elements to which the propagation velocity of electromagnetic energy is retarded more closely to a next adjacent antenna element than the antenna elements of the remaining sub-groups of antenna elements.

39. The method of claim 37 wherein said retarding step comprises:

attenuating the amplitude of radiated energy associated with the sub-groups of antenna elements to which the propagation velocity of electromagnetic energy is retarded.

40. The method of claim 37, wherein said retarding step comprises:

attenuating the amplitude of radiated energy associated with ones of the antenna elements of the sub-groups of antenna elements to which the propagation velocity of electromagnetic energy is retarded with respect to the amplitude of radiated energy associated with other ones of the antenna elements of the sub-groups of antenna elements to which the propagation velocity of electromagnetic energy is retarded.

41. A system for providing adjustable elevation scanning in a multibeam antenna system having a plurality of radiating structures, wherein at least two of said radiating structures are displaced vertically with respect to each other, said system comprising:

means for forming a first antenna beam of said multibeam antenna system by associating an input signal with a preselected group of said radiating structures, said group of radiating structures selected such that excitation by said input signal combines to form a predetermined azimuthal beam width thereby defining said first antenna beam; and

means for electrically tilting said first antenna beam by associating a phase differential with a first sub-group of said preselected group of radiating structures relative to a second sub-group of said preselected group of radiating structures, wherein said first sub-group of radiating structures includes a first one of said at least two vertically displaced radiating structures and said second sub-group of said radiating structures includes a second one of said at least two vertically displaced radiating structures, and wherein said relative phase differential provided by said providing means is associated only with said first antenna beam thereby independently adjusting said first antenna beam with respect to other antenna beams of said antenna system.

42. The system of claim 41, wherein said tilting means comprises:

means for retarding a phase of said input signal as associated with said first sub-group of radiating structures, wherein said phase differential includes said retarded phase of said retarding means.

43. The system of claim 42, wherein said retarding means comprises:

a removable jumper disposed in a signal path associated with said first sub-group of radiating structures.

44. The system of claim 42, wherein said retarding means comprises:

an adjustable delay device disposed in a signal path associated with said first sub-group of radiating structures.

45. The system of claim 44 further comprising:

means for controlling said adjustable delay device.

46. The system of claim 41, wherein said forming means comprises:

a plurality of beam forming networks, a first beam forming network of said plurality being associated with said first sub-group of radiating structures and a second beam forming network of said plurality being associated with said second sub-group of radiating structures.

47. The system of claim 41, further comprising:

means for reflecting energy radiated from said plurality of radiating structures in a selected direction.

48. The system of claim 47, wherein said reflecting means comprises:

means for providing air permeability.

49. The system of claim 48, wherein said permeability means includes passages having a largest dimension of approximately {fraction (1/10)} λ

of the highest operating wavelength of said system.

50. An antenna system providing a plurality of antenna beams adapted to provide independently selectable down-tilt for ones of said plurality of antenna beams, said system comprising:

an array of antenna elements, wherein said array includes a plurality of antenna element columns, ones of said columns including a plurality of antenna elements;

a first beam forming matrix coupled to antenna elements of said array;

a second beam forming matrix coupled to antenna elements of said array, wherein said first and second beam forming matrixes are each coupled to different antenna elements of said columns including a plurality of antenna elements; and

a first phase adjusting circuit coupled to said second beam forming matrix, wherein said phase adjusting circuit alters a phase of a first signal associated with said second beam forming matrix a predetermined amount with respect to a first signal associated with said first beam forming matrix thereby providing elevation scanning of a first antenna beam of said plurality of antenna beams.

51. The system of claim 50, further comprising:

a second phase adjusting circuit coupled to said second beam forming matrix, wherein said first phase adjusting circuit and said second phase adjusting circuit both alter a phase of said first signal.

52. The system of claim 50, wherein said first phase adjusting circuit comprises:

a removable predetermined length of cable disposed in a signal path of said second beam forming matrix.

53. The system of claim 50, wherein said first phase adjusting circuit comprises:

an adjustable delay disposed in a signal path of said second beam forming matrix.

54. The system of claim 50, further comprising:

a second phase adjusting circuit coupled to said second beam forming matrix, wherein said phase adjusting circuit alters a phase of a second signal associated with said second beam forming matrix a predetermined amount with respect to a second signal associated with said first beam forming matrix thereby providing elevation scanning of a second antenna beam of said plurality of antenna beams.

55. The system of claim 50, wherein said antenna system is a planar array.

56. The system of claim 50, wherein said antenna system is a conical array.

57. The system of claim 50, wherein said antenna system is adapted to provide mechanical down-tilt to which said independently selectable down-tilt is added.

58. An antenna array providing aperture tapering for side lobe level control, said antenna comprising:

a plurality of antenna element columns each of which includes a same number of antenna elements; and

a plurality of antenna column feed buses each associated with an antenna element column of said plurality, wherein said feed buses are disposed substantially parallel to and proximal to said associated one of said antenna element columns, wherein ones of said feed buses have a dielectric material disposed between the feed bus and said associated one of said antenna element columns thereby defining dielectric line buses and other ones of said feed buses have an air space disposed between the feed bus and said associated one of said antenna element columns thereby defining air line buses, and wherein the antenna elements of the antenna element columns associated with said dielectric line buses have an inter column element spacing less than that of the antenna elements of the antenna element columns associated with said air line buses.

59. The antenna of claim 58, wherein said plurality of antenna element columns are disposed in a planar array of parallel antenna element columns, and wherein said antenna element columns associated with said dielectric line buses are disposed at the outer edges of said planar array.

60. The antenna of claim 59, wherein ones of said dielectric line buses include different densities of dielectric material, and wherein antenna element columns associated with dielectric line buses having a more dense dielectric material are disposed at the distal ends of said planar array and antenna element columns associate with dielectric line buses having a less dense dielectric material are disposed adjacent to said distal ends.

61. The antenna of claim 58, wherein at least a portion of said dielectric material is adapted to provide amplitude tapering.

62. The antenna of claim 61, wherein said portion of dielectric material includes a lossy material.

63. The antenna of claim 62, wherein said lossy material is carbon.

64. The antenna of claim 62, wherein said lossy material is distributed throughout said portion of dielectric material in zones of differing densities.

65. An antenna array providing aperture tapering for side lobe level control, said antenna comprising:

a ground plane;

a plurality of antenna element columns each of which includes a same number of antenna elements, wherein said plurality of antenna columns are disposed substantially parallel to and in close proximity to said ground plane;

a plurality of antenna column feed buses each associated with an antenna element column of said plurality, wherein said ground plane is disposed between said plurality of feed buses and an associated one of said antenna element columns, and wherein ones of said feed buses have a dielectric material disposed between the feed bus and the ground plane thereby defining dielectric line buses and other ones of said feed buses have an air space disposed between the feed bus and the ground plane thereby defining air line buses, and wherein the antenna elements of the antenna element columns associated with said dielectric line buses have an inter column element spacing less than that of the antenna elements of the antenna element columns associated with said air line buses; and

a beam forming matrix coupled to said plurality of feed buses, wherein substantially a same power level signal is applied by said beam forming matrix to each of said plurality of antenna element columns when energized.

66. The array of claim 65, wherein said dielectric line buses are associated with outer antenna element columns of said plurality of antenna columns.

67. The array of claim 65, wherein at least one said dielectric line bus includes a lossy material.

68. The antenna array of claim 67, wherein said lossy material is distributed in zones of differing densities in said dielectric material.

69. The antenna array of claim 68, wherein said zones of differing densities of lossy material are selected to provide tapering of a composite signal radiated from an antenna element column associated with said at east one dielectric line bus.

70. The antenna array of claim 65, wherein said ground plane includes a plurality of passages disposed therein, wherein said passages define a gridded surface of said ground plane.

71. The antenna array of claim 70, wherein the largest dimension of said passages is selected to be approximately {fraction (1/10)} λ

of the highest operating wavelength of said array.

72. A phased antenna array providing a plurality of antenna beams adapted to provide independently selectable down-tilt for ones of said plurality of antenna beams, said array comprising:

a ground plane having a plurality of passages disposed therein, wherein said passages define a gridded surface of said ground plane;

an array of antenna elements, wherein said array includes a plurality of antenna element columns, ones of said columns including a plurality of said antenna elements, and wherein said plurality of antenna columns are disposed substantially parallel to and in close proximity to said ground plane;

a plurality of antenna column feed buses each associated with an antenna element column of said plurality, wherein said ground plane is disposed between said plurality of feed buses and an associated one of said antenna element columns, and wherein ones of said feed buses have a dielectric material disposed between the feed bus and the ground plane;

a first beam forming matrix coupled to ones of the plurality of feed buses;

a second beam forming matrix coupled to other ones of the plurality of feed buses, wherein said first and second beam forming matrixes are each coupled to different antenna elements of said columns including a plurality of antenna elements; and

a first phase adjusting circuit coupled to said second beam forming matrix, wherein said phase adjusting circuit alters a phase of a first signal associated with said second beam forming matrix a predetermined amount with respect to a first signal associated with said first beam forming matrix thereby providing elevation scanning of a first antenna beam of said plurality of antenna beams.

73. The antenna array of claim 72, wherein said ones of said feed buses having a dielectric material disposed between the feed bus and the ground plane are associated with outer antenna columns of said plurality of antenna columns of said array.

74. The antenna array of claim 72, wherein said dielectric material associated with at least one antenna column of said plurality of antenna columns includes a lossy material.

75. The antenna array of claim 74, wherein said at least one antenna column associated with said dielectric material including lossy material is selected to provide amplitude tapering.

76. The antenna array of claim 74, wherein said lossy material is distributed in zones of differing densities in said dielectric material.

77. The antenna array of claim 76, wherein said zones of differing densities of lossy material are selected to provide tapering of a composite signal radiated from said at least one antenna element column.

78. The antenna array of claim 72, wherein a largest dimension of said passages is selected to be approximately {fraction (1/10)} λ

of the highest operating wavelength of said array.