Electronically agile multi-beam antenna

• US 6,771,218 B1
• Filed: 02/13/1995
• Issued: 08/03/2004
• Est. Priority Date: 09/11/1992
• Status: Active Grant

• Current Assignee: Ball Aerospace & Technologies Corporation (Ball Corporation)
• Original Assignee: Ball Aerospace & Technologies Corporation (Ball Corporation)
• Inventors: Lalezari, Farzin, Boone, Theresa Cronin
• Primary Examiner(s): Issing, Gregory C.
• Application Number:
  US08/392,312
• Time in Patent Office: 3,459 Days
• Field of Search: 342/368, 342/371, 342/372, 342/373, 342/374, 342/157-8, 343/705, 343/708, 343/777, 343/700.MS
• US Class Current: 342/373
• CPC Class Codes: G01S 13/48 using multiple beams at emission or reception
• CPC Class Codes: H01Q 1/28 Adaptation for use in or on aircraft, missiles, satellites, or balloons
• CPC Class Codes: H01Q 21/205 providing an omnidirectional coverage turnstile aerials H01Q21/26
• CPC Class Codes: H01Q 25/02 providing sum and difference patterns H01Q25/04 takes precedence
• CPC Class Codes: H01Q 3/24 varying the orientation by switching energy from one active radiating element to another, e.g. for beam switching

Abstract

The present invention provides an antenna system including a body for use in determining N unknown parameters values relating to an object located in the vicinity of the system. The system further includes an antenna array comprised of a plurality of elements that are spaced to reduce ambiguities in the subsequently determined N values. In one embodiment, several pair of elements are used. The spacing between the elements comprise the pairs and the spacing between pairs reduces ambiguities. The antenna system also includes a beamformer for producing a plurality of beams and a device for using the plurality of beams to determine N values associated with the object. The amplitude of the plurality of beams can be compared to obtain coarse data on the object. The phases of the plurality of spatially independent but overlapping beams are compared to realize an interferometer that can provide coarse resolution data and/or fine resolution data on the position and/or polarization of an object relative to the antenna system. The amplitudes of the beams can also be compared to obtain coarse data on the position and/or polarization of the object. The beamformer includes a switching network for selecting which elements of the antenna array form the subsets. This permits, for example, the position of the beams to be moved and the baseline of the beams to be varied.

Claims

1. An electronically agile antenna system comprising:

a body having an exterior surface, a longitudinal axis and a plane that is substantially perpendicular to said longitudinal axis;

an antenna array that is operatively connected to said body, has at least three elements that are each located in a first ring around a periphery of said body, and is capable of providing a plurality of signals that are representative of the environment about the antenna system, wherein each of said at least three elements is capable of providing one of said plurality of signals; and

a beamformer that includes means for selecting a first portion of said plurality of signals provided by a first subset of elements of said plurality of elements to form a first beam and a second portion of said plurality of signals provided by a second subset of elements of said plurality of elements to form a second beam, wherein selections of said first portion and said second portion vary depending on polarization and location parameters of an object in the vicinity of said body and\or desired accuracies, said beamformer further including means for processing said first portion of said plurality of signals to form said first beam and means for processing said second portion of said plurality of signals to form said second beam, wherein information is obtained using said first and second portions related to said polarization parameters of the object, with said information related to said polarization parameters of the object being used to determine position information related to the object located in the vicinity of said body.

2. An electronically agile antenna system, as claimed in claim 1, wherein:

said body is a missile.

3. An electronically agile antenna system, as claimed in claim 1, wherein:

said antenna array is substantially conformal to said exterior surface.

4. An electronically agile antenna system, as claimed in claim 1, wherein:

said antenna array forms a portion of said exterior surface.

5. An electronically agile antenna system, as claimed in claim 1, wherein:

said exterior surface includes a front surface and a side surface; and

substantially all said antenna array is located on said side surface.

6. An electronically agile antenna system, as claimed in claim 1, wherein:

said antenna array has a field of view of approximately ±

60°

relative to said longitudinal axis.

7. An electronically agile antenna system, as claimed in claim 1, wherein:

at least one of said at least three elements includes a surface wave mode element.

8. An electronically agile antenna system, as claimed in claim 1, wherein:

at least one of said at least three elements includes one of the following;

a wave guide feed and a printed circuit feed.

9. An electronically agile antenna system, as claimed in claim 1, wherein:

at least one of said at least three elements provides a broadband mode of operation.

10. An electronically agile antenna system, as claimed in claim 1, wherein:

at least one of said at least three elements has an endfire pattern.

11. An electronically agile antenna system, as claimed in claim 1, wherein:

said at least three elements includes one of the following;

at least three discrete elements, each with a feed and a lens, a single lens with at least three feeds, and a hybrid of at least one discrete element and a single lens with at least two feeds.

12. An electronically agile antenna system, as claimed in claim 1, wherein:

at least one of said at least three elements is one of the following;

a radially polarized element and a circumferentially polarized element.

13. An electronically agile antenna system, as claimed in claim 1, wherein:

at least two elements have different polarization responses.

14. An electronically agile antenna system, as claimed in claim 1, wherein:

said first ring has a substantially circular shape.

15. An electronically agile antenna system, as claimed in claim 1, wherein:

said at least three elements that are each located in said first ring include a discrete pair of elements, wherein a distance between the elements comprising said discrete pair of elements is predetermined to aid in resolving ambiguities in the determination of said position information.

16. An electronically agile antenna system, as claimed in claim 1, wherein:

said at least three elements that are each located in said first ring includes a first element, a second element that is located immediately adjacent to said first element, and a third element that is located immediately adjacent to said second element and separated from said first element by said second element, wherein a first distance between said first element and said second element is different than a second distance between said second element and said third element.

17. An electronically agile antenna system, as claimed in claim 16, wherein:

said first distance is predetermined to aid in resolving ambiguities in the determination of said position information.

18. An electronically agile antenna system, as claimed in claim 1, wherein:

said at least three elements that are each located in said first ring includes at least two discrete pair of elements, wherein the two elements comprising each of said at least two discrete pair of elements are separated by a first distance and each of said at least two discrete pair of elements is separated from an immediately adjacent discrete pair of elements by a second distance that is greater than said first distance.

19. An electronically agile antenna system, as claimed in claim 18, wherein:

a first of said at least two discrete pair of elements is separated from a second of said at least two discrete pair of elements by approximately 90°

as measured from said longitudinal axis.

20. An electronically agile antenna system, as claimed in claim 1, wherein:

said at least three elements are equally spaced from one another.

21. An electronically agile antenna system, as claimed in claim 1, wherein:

said at least three elements that are each located in said first ring include a plurality of pair of elements, wherein the two elements comprising each of said plurality of pair of elements are separated by a first distance and each of said plurality of pair of elements is separated from an immediately adjacent pair of elements by a second distance that is greater than said first distance and the distance between immediately adjacent pairs of elements is substantially equal.

22. An electronically agile antenna system, as claimed in claim 1 wherein:

said at least three elements that are each located in said first ring includes a plurality of pair of elements, wherein the two elements comprising each of said plurality of pair of elements are separated by a first distance and each of said plurality of pair of elements is separated from an immediately adjacent pair of elements by a second distance that is greater than said first distance and at least two immediately adjacent pair of elements have a different distance therebetween than between a different immediately adjacent pair of elements.

23. An electronically agile antenna system, as claimed in claim 1, wherein:

said at least three elements that are each located in said first ring include at least eight discrete pair of elements.

24. An electronically agile antenna system, as claimed in claim 22, wherein:

said at least eight discrete pair of elements are substantially equally spaced from one another.

25. An electronically agile antenna system, as claimed in claim 1, wherein:

said antenna array includes an element that is located in a second ring that is different from said first ring.

26. An electronically agile antenna system, as claimed in claim 1, wherein:

said first ring is located within said plane; and

said antenna array includes at least three radially polarized elements located in said first ring and at least three circumferentially polarized elements located in a second ring in said plane that is different from said first ring.

27. An electronically agile antenna system, as claimed in claim 1, wherein:

said first subset of elements is immediately adjacent to said second subset of elements.

28. An electronically agile antenna system, as claimed in claim 1, wherein:

said first subset of elements includes only one element;

said second subset of elements includes only one element; and

said first subset of elements is located immediately adjacent to said second subset of elements.

29. An electronically agile antenna system, as claimed in claim 1, wherein:

said beamformer includes means for forming said first beam at a first time and said second beam at a second time that is later than said first time.

30. An electronically agile antenna system, as claimed in claim 1, wherein:

said beamformer includes means for forming said first beam at substantially the same time as said second beam.

31. An electronically agile antenna system, as claimed in claim 1, wherein:

said first beam is spatially independent but overlapping with said second beam.

32. An electronically agile antenna system, as claimed in claim 1, wherein:

said means for processing includes means for performing an amplitude comparison of said first beam and said second beam.

33. An electronically agile antenna system, as claimed in claim 1, wherein:

said means for processing includes means for performing a phase comparison of said first beam and said second beam.

34. An electronically agile antenna system, as claimed in claim 1, wherein:

said means for processing includes means for performing an amplitude comparison and a phase comparison of said first beam and said second beam.

35. An electronically agile, mobile antenna system for use in determining at least one unknown parameter value associated with an object located in the vicinity of the system, comprising:

a body having an exterior surface, a longitudinal axis, and a plane that is substantially perpendicular to said longitudinal axis;

an antenna array that is operatively connected to said body, has a plurality of elements that are each located in a ring around the periphery of said body, and is capable of providing a plurality of signals that are each representative of the environment about the antenna system, wherein each of said plurality of elements is capable of providing one of said plurality of signals and said plurality of elements includes at least one radially oriented element;

a beamformer for processing portions of said plurality of signals provided by subsets of said plurality of elements to produce a plurality of beams; and

means for cooperatively using said plurality of beams to determine said at least one unknown parameter value associated with the object, said means for cooperatively using including means for evaluating an offset f(p) in at least one of phase and amplitude Δ

caused by said at least one radially oriented element whose phase and amplitude response depends on element orientation.

36. An electronically agile, mobile antenna system, as claimed in claim 35, wherein:

said offset f(p) in phase Δ

is a function of polarization parameters of the object.

37. An electronically agile, mobile antenna system, as claimed in claim 35, wherein:

said plurality of elements are located substantially conformal to said exterior surface and include a discrete pair of elements; and

said discrete pair of elements are located substantially in said plane and are one of the following;

in equal proximity to each other and in closer proximity to one another than to other of said plurality of elements.

38. An electronically agile, mobile antenna system as claimed in claim 35, wherein:

said beamformer, when at least two of said plurality of beams to be provided to said means for cooperatively using are substantially linearly polarized and a phase difference therebetween is described by;

39. An electronically agile, mobile antenna system as claimed in claim 35, wherein:

said beamformer, when at least two of said plurality of beams to be provided to said means for cooperatively using are substantially circularly polarized and a phase difference therebetween is described by;

40. An electronically agile, mobile antenna system as claimed in claim 35, wherein:

said beamformer, when at least two of said plurality of beams to be provided to said means for cooperatively using are one of linearly polarized and circularly polarized, and a phase difference therebetween is described by;

41. An electronically agile mobile antenna system as claimed in claim 35, wherein:

said beamformer includes a look up table for polarization parameters of said elements that is indexed based upon element location; and

said means for cooperatively using includes means for determining f(p), where f(p) relates to at least one of polarization parameters for the object and said body, using said polarization parameters of at least one of said body and the object and a measured phase difference between beams.

42. An electronically agile mobile antenna system as claimed in claim 35, wherein:

said means for cooperatively using, when at least two of said plurality of beams are of a known polarization and a location of an object is approximately known, includes means for calculating location parameters of the object with two phase difference measurements.

43. An electronically agile mobile antenna system as claimed in claim 35, wherein:

said beamformer includes means for selecting said plurality of beams such that said plurality of beams are derived from portions of said plurality of signals produced by a group of said plurality of elements that are located substantially adjacent to one another.

44. An electronically agile mobile antenna system as claimed in claim 35, wherein:

said beamformer includes means for selecting said plurality of beams such that said plurality of beams are derived from portions of said plurality of signals produced by elements located substantially on opposite sides of said ring to achieve substantially 180°

spatial separation for high resolution measurements in a reduced field of view.

45. An electronically agile, mobile antenna system, as claimed in claim 35, wherein:

each of said plurality of elements is a broadband launch element.

46. An electronically agile, mobile antenna system, as claimed in claim 35, wherein:

said plurality of elements includes a plurality of discrete pair of elements.

47. An electronically agile, mobile antenna system, as claimed in claim 35, wherein:

said plurality of elements includes at least two discrete pair of elements and no more than eight discrete pair of elements.

48. An electronically agile, mobile antenna system, as claimed in claim 35, wherein:

each of said subsets of said plurality of elements includes only one element.

49. An electronically agile, mobile antenna system, as claimed in claim 35, wherein:

said beamformer includes only one beamforming channel and means for sequentially using said only one beamformer channel to produce said plurality of beams.

50. An electronically agile, mobile antenna system, as claimed in claim 35, wherein:

said beamformer includes a plurality of beamforming channels and means for simultaneously using said plurality of beamforming channels to produce said plurality of beams.

51. An electronically agile, mobile antenna system, as claimed in claim 35, wherein:

at least two of said plurality of beams are spatially independent and overlapping.

52. An electronically agile, mobile antenna system, as claimed in claim 35, wherein:

all of said plurality beams are spatially independent and overlapping.

53. An electronically agile, mobile antenna system for determining at least one unknown parameter value associated with an object in the vicinity of the system, comprising:

a body having an exterior surface, a longitudinal axis, and a plane that is substantially perpendicular to said longitudinal axis;

an antenna array that is operatively connected to said body, has a plurality of discrete pair of broadband elements that are each located in a ring around a periphery of said body, and is capable of providing a plurality of signals that are each representative of the environment about the antenna system, wherein each element of said plurality of discrete pair of elements is capable of providing one of said plurality of signals;

a beamformer for processing a number of said plurality of signals provided by a number of elements of said plurality of discrete pair of broadband elements to produce a plurality of beams, wherein each element of said number of elements is separated from every other element of said number of elements by less than about 180°

relative to said longitudinal axis; and

means for cooperatively using said plurality of beams to determine said at least one unknown parameter value, said means for cooperatively using including means for determining f(p), where f(p) relates to polarization parameters of the object and polarization parameters of the body, by using said polarization parameters of said body and said polarization parameters of the object and a measured phase difference between said plurality of beams.

54. An electronically agile, mobile antenna system, as claimed in claim 53, wherein:

said beamformer includes means for forming a first beam from a first signal provided by a first broadband element of a discrete pair of broadband elements and a second beam from a second broadband element of the same said discrete pair of broadband elements.

55. An electronically agile, mobile antenna system, as claimed in claim 53, wherein:

said beamformer includes means for forming a first beam from a first signal provided by a first broadband element of a first discrete pair of broadband elements, a second beam from a second signal provided by a second broadband element of said first discrete pair of broadband elements, and a third beam from a third signal provided by a third element of a second discrete pair of broadband elements that is different than said first discrete pair of broadband elements.

56. An electronically agile, mobile antenna system, as claimed in claim 55, wherein:

said third element is separated from said first and second elements by less than 90°

relative to said longitudinal axis.

57. An electronically agile, mobile antenna system, as claimed in claim 55, wherein:

said third element is separated from said first and second elements by approximately 90°

relative to said longitudinal axis.

58. An electronically agile, mobile antenna system, as claimed in claim 53, wherein:

said beamformer includes means for forming first and second beams from first and second signals provided by a first discrete pair of broadband elements and means for forming third and fourth signals from a second discrete pair of broadband elements that is different than said first pair of discrete broadband elements.

59. An electronically agile, mobile antenna system, as claimed in claim 58, wherein:

said first pair of broadband elements is separated from said second pair of broadband elements by less than 90°

relative to said longitudinal axis.

60. An electronically agile, mobile antenna system, as claimed in claim 58, wherein:

said first pair of broadband elements is separated from said second pair of broadband elements by approximately 90°

relative to said longitudinal axis.

61. An electronically agile, mobile antenna system, as claimed in claim 58, wherein:

said beamformer includes means for selecting said beams such that said beams are derived from portions of said plurality of signals produced by elements located substantially on opposite sides of said ring to achieve substantially 180°

spatial separation for high resolution measurements in a reduced field of view.

62. A method for operating an electronically agile, mobile antenna system for determining location information associated with an object in the vicinity of said system, comprising:

providing a body having an exterior surface, a longitudinal axis, and a plane that is substantially perpendicular to said longitudinal axis;

providing an antenna array that is operatively connected to said body, has a plurality of elements that are each located in a ring around a periphery of said body, and is capable of providing a plurality of signals that are representative of the environment about the antenna system, wherein each of said elements is capable of providing one of said plurality of signals;

forming a first plurality of beams from said plurality of signals provided by said antenna array;

acquiring coarse information related to location of the object by comparing the amplitudes of said first plurality of beams to one another;

generating, after said step of acquiring is completed, a second plurality of beams, with said second plurality of beams being different from said first plurality of beams based on information from said first plurality of beams; and

tracking fine information related to location of said object by using at least one of phases and amplitudes of said second plurality of beams, while not using at least some of said first plurality of beams that are different from said second plurality of beams.

63. A method, as claimed in claim 62, wherein:

said step of forming a first plurality of beams includes forming at least one of said plurality of beams at a different time than another of said first plurality of beams.

64. A method, as claimed in claim 62, wherein:

said step of forming a first plurality of beams includes forming all of said first plurality of beams at substantially the same time.

65. A method, as claimed in claim 62, wherein:

said step of generating second plurality of beams includes generating at least one of second plurality of beams at a different time than another of said second plurality of beams.

66. A method, as claimed in claim 62, wherein:

said step of generating a second plurality of beams includes generating all of said second plurality of beams at substantially the same time.

67. A method, as claimed in claim 62, wherein:

said step of generating a second plurality of beams includes generating spatially independent and overlapping beams.

68. A method, as claimed in claim 62, wherein:

said step of tracking includes comparing a first phase of a first beam produced using a first subset of said plurality of elements to a second phase of a second beam produced from using a second subset of said plurality of elements, wherein said first subset of elements is separated from said second subset of elements by less than 90°

relative to said roll plane.

69. A method, as claimed in claim 62, wherein:

said step of tracking includes comparing a first phase of a first beam produced using a first subset of elements of said plurality of elements to a second phase of a second beam produced using a second subset of said plurality of elements, wherein said first subset of elements is separated from said second subset of elements by approximately 90°

.

70. A method, as claimed in claim 62, wherein:

said step of forming includes selecting said beams such that said beams are derived from portions of said plurality of signals produced by elements located substantially on opposite sides of said ring to achieve substantially 180°

spatial separation for high resolution measurements in a reduced field of view.

71. A method, as claimed in claim 62, wherein:

each of said at least three elements has a polarization vector that differs from a polarization vector of each of the other of said elements, with each of said polarization vectors of each of said elements depending upon location of said elements on said body.

72. A method, as claimed in claim 62, wherein:

said step of forming includes using a first baseline related to element spacing and said step of generating includes using a second baseline related to element spacing, with said second baseline being greater than said first baseline.

73. A method, as claimed in claim 62, wherein:

said step of tracking includes obtaining information related to polarization parameters of said object.

74. A method, as claimed in claim 62, wherein:

said second plurality of beams is chosen based upon at least one polarization parameter of said object.

75. A method for operating an electronically agile, mobile antenna system for determining location information associated with an object in the vicinity of said system, comprising:

providing a body having an exterior surface, a longitudinal axis, and a plane that is substantially perpendicular to said longitudinal axis;

providing an antenna array that is operatively connected to said body, has a plurality of elements that are each located in a ring around a periphery of said body, and is capable of providing a plurality of signals that are representative of the environment about the antenna system, wherein each of said elements is capable of providing one of said plurality of signals;

forming a first plurality of beams from said plurality of signals provided by said antenna array;

selecting a first two beams from said first plurality of beams, said first two beams having a first baseline, said first baseline depending upon a spacing between first and second elements that are used to form said first two beams;

generating a second plurality of beams from said plurality of elements of said antenna array;

choosing a second two beams from said second plurality of beams, said second two beams having a second baseline that is different from said first baseline, said second baseline depending upon a spacing between third and fourth elements that are used to form said second two beams; and

determining location information associated with said object using at least said first two beams and said second two beams.