Dual mode switched beam antenna

• US 6,198,434 B1
• Filed: 12/17/1998
• Issued: 03/06/2001
• Est. Priority Date: 12/17/1998
• Status: Expired due to Term

• Current Assignee: Kathrein SE
• Original Assignee: Metawave Communications Corp.
• Inventors: Elson, J. Todd, Huang, Leibing, Martek, Gary A.
• Primary Examiner(s): Blum, Theodore M.
• Application Number:
  US09/213,640
• Time in Patent Office: 810 Days
• Field of Search: 342/373, 343/820, 343/813, 343/814, 343/816
• US Class Current: 342/373
• CPC Class Codes: H01Q 21/061 Two dimensional planar arrays
• CPC Class Codes: H01Q 21/22 Antenna units of the array energised non-uniformly in amplitude or phase, e.g. tapered array or binomial array
• 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 3/40 with phasing matrix

Abstract

Systems and methods for providing antenna beams having reduced grating and side lobes when steered off of the antenna broadside are disclosed. According to the present invention an arrangement of antenna elements suitable for use in generating antenna beams steered at greater angles off of the antenna broadside is utilized with a beam feed network consistent with the antenna beams being steered at the greater angles and reduced antenna element spacing to provide the reduced grating and side lobes. A preferred embodiment utilizes a 2_n+1 Butler matrix coupled to 2_n+1 antenna columns spaced according to the present invention to provide 2_n antenna beams.

Claims

1. A method of providing reduced grating lobe levels when at least a first antenna beam is steered off of an antenna broadside at a maximum desired first angle, said method comprising the steps of:

selecting desired operating attributes of said first antenna beam including selecting said first angle and a beam width of said first antenna beam;

identifying an antenna system design having a beam forming circuit and a number of antenna columns coupled thereto suitable for providing an antenna beam steered off of said antenna broadside at a second angle which is greater than said first angle; and

deploying said number of antenna columns with an inter-column spacing less than that of said antenna system design while maintaining said beam forming circuit substantially unchanged, wherein said inter-column spacing is selected at least in part to provide an antenna beam substantially meeting said operating attributes.

2. The method of claim 1, wherein said first antenna beam is associated with a first communication mode, and wherein said inter-column spacing is selected at least in part to provide a second antenna beam having desirable characteristics including a wider beam width than said first antenna beam, wherein said second antenna beam is associated with a second communication mode.

3. The method of claim 2, wherein said first communication mode is an analogue cellular format, and said second communication mode is a digital cellular format.

4. The method of claim 1, wherein said first angle is substantially 45°

and said beam width is substantially 30°

.

5. The method of claim 4, wherein said antenna system design is an eight column planar array having an eight by eight beam forming matrix coupled thereto for forming eight substantially non-overlapping antenna beams.

6. The method of claim 5, wherein said inter-column spacing is within the range of from approximately 0.25λ

to approximately 0.35λ

.

7. The method of claim 5, wherein said inter-column spacing is 0.27λ

.

8. The method of claim 1, wherein said beam forming circuit is an adaptive beam forming circuit providing adjustable steering of said first antenna beam between said first angle and an angle off of said antenna broadside less than said first angle.

9. The method of claim 1, further comprising the step of:

deploying antenna elements in ones of said columns to provide outer columns of said plurality of columns having a reduced length as compared to inner columns of said plurality of columns.

10. The method of claim 9, wherein said step of deploying antenna elements comprises the step of:

introducing a dielectric material into an air-line bus of said outer columns.

11. The method of claim 1, further comprising the step of:

deploying antenna elements in ones of said columns to provide polarization diversity as among said columns.

12. The method of claim 1, wherein said substantially unchanged beam forming circuit is a beam forming matrix having a plurality of antenna beam interfaces a first one of which is coupled to said first antenna beam and a second one of which is associated with said antenna beam steered off of said antenna broadside at said second angle, wherein said second interface is unused as deployed.

13. An antenna system adapted to provide reduced grating lobe levels when at least a first antenna beam is steered off of an antenna broadside at a maximum desired first angle, said system comprising:

beam forming circuitry having at least one A interface associated with said first antenna beam and a plurality of B interfaces having a plurality of phase progressions associated therewith, wherein a first phase progression of said plurality of phase progressions is associated with said first angle; and

a plurality of driven antenna elements each coupled to one of said B interfaces, wherein said plurality of phase progressions are consistent with forming antenna beams more narrow than said first antenna beam and at least one antenna beam steered off of the antenna broadside at a second angle which is greater than said first angle, and wherein each of the plurality of driven antenna elements which are coupled to different ones of said B interfaces are spaced a distance from a next adjacent one of the plurality of driven antenna elements which are coupled to different ones of said B interfaces determined to provide said first antenna beam with a desired beam width using said first phase progression.

14. The system of claim 13, wherein said beam forming circuitry comprises:

a beam forming matrix having a plurality of A interfaces of which said at least one A interface is one, wherein a number of said plurality of A interfaces and said plurality of B interfaces is the same.

15. The system of claim 14, wherein at least a second interface of said plurality of A interfaces is associated with a second antenna beam steered off of the antenna broadside at said second angle.

16. The system of claim 15, wherein said second interface is not utilized in forming antenna beams by said antenna system.

17. The system of claim 14, wherein said beam forming matrix is a Butler matrix.

18. The system of claim 15, wherein said number of A interfaces and said number of B interfaces is eight, and wherein four A interfaces are not utilized by an antenna beam of said antenna system.

19. The system of claim 13, wherein said beam forming circuitry comprises:

an adaptive beam forming circuit providing adjustable steering of said first antenna beam.

20. The system of claim 13, wherein said plurality of driven antenna elements comprise:

a plurality of columns of antenna elements each including a same number of individual antenna elements, each column of said plurality being coupled to a different one of said B interfaces, wherein columns disposed at an edge of said antenna system are compressed in size as compared to columns disposed more near the middle of said antenna system.

21. The system of claim 20, wherein said antenna columns are coupled to said B interfaces through a air-line bus, and wherein said columns disposed at said edge of said antenna system include a dielectric disposed in said air-line bus.

22. The system of claim 20, wherein said distance said next adjacent driven antenna elements are spaced is selected from the range of from approximately 0.25λ

to approximately 0.35λ

.

23. The system of claim 22, wherein said plurality of columns is eight columns and said first angle is approximately 45°

.

24. The system of claim 13, wherein said distance said next adjacent driven antenna elements are spaced is selected at least in part to allow said first antenna beam to be steered said first angle and to have a desired beam width.

25. The system of claim 24, wherein said distance said next adjacent driven antenna elements are spaced is also selected at least in part to allow an antenna beam to be formed having desired characteristics which provides a beam width greater than said first antenna beam.

26. The system of claim 25, wherein said antenna beam larger than said first antenna beam is a synthesized sector.

27. The system of claim 25, further comprising:

a first communication mode associated with said first antenna beam; and

a second communication mode associated with said antenna beam larger than said first antenna beam.

28. The system of claim 27, wherein said first communication mode is an analogue cellular telephone communication mode and said second communication mode is a digital cellular telephone communication mode.

29. The system of claim 13, wherein said A interface is a signal input into said beam forming circuitry and said plurality of B interfaces are signal outputs from said beam forming circuitry.

30. The system of claim 13, wherein said A interface is a signal output from said beam forming circuitry and said plurality of B interfaces are signal inputs to said beam forming circuitry.

31. A method of providing a multi-beam antenna having desired antenna beam characteristics, said method comprising the steps of:

selecting a number of antenna beams associated with said multi-beam antenna, wherein said number is 2ⁿ;

selecting desired operating attributes of said antenna beams including selecting a maximum desired scan angle and a beam width;

providing 2ⁿ⁺¹ antenna columns in a predetermined arrangement wherein each antenna column is spaced equidistant from any adjacent antenna columns; and

coupling a beam forming matrix having a first set of interfaces associated with antenna beam signals and a second set of interfaces associated with a phase progression of said antenna beam signals to said antenna columns, wherein second set of interfaces are each coupled to a different one of said antenna columns, wherein said column spacing is selected at least in part to provide said antenna beams with said selected operating attributes.

32. The method of claim 31, wherein said beam forming matrix is a 2ⁿ⁺¹ by 2ⁿ⁺¹ Butler matrix.

33. The method of claim 31, further comprising the step of:

compressing ones of said antenna columns longitudinally to be shorter than other ones of said antenna columns.

34. The method of claim 33, wherein each antenna column of said antenna columns includes a same number of antenna elements therein.

35. The method of claim 34, wherein said number of antenna elements is 4 .

36. The method of claim 33, wherein said compressing step comprises the step of:

disposing a dielectric material in the feed path of said compressed ones of said antenna columns.

37. The method of claim 31, wherein said number n is 2 .

38. The method of claim 37, wherein said column spacing is between 0.25λ

and 0.35λ

inclusive.

39. The method of claim 37, wherein said column spacing is selected at least in part to provide an antenna beam having desirable attributes when multiple ones of said first set of interfaces are provided a same antenna beam signal.

40. The method of claim 39, wherein said same antenna beam signal provided said multiple ones of said first set of interfaces are weighted differently at ones of said multiple ones of said first set of interfaces.

41. The method of claim 39, wherein a first mode of communication signal is provided individual ones of said first set of interfaces and a second mode of communication signal is provided said multiple ones of said first set of interfaces.

42. The method of claim 41, wherein said first mode is an AMPS type communication format and said second mode is a CDMA type communication format.

43. The method of claim 31, further comprising the step of terminating 2ⁿ⁺¹-2ⁿ interfaces of said first set of interfaces.

44. A multiple beam antenna system having reduced grating lobe levels associated with outer ones of said multiple beams, said system comprising:

2ⁿ antenna beams having desired operating attributes including a maximum desired scan angle and a substantially same desired beam width;

2ⁿ⁺¹ antenna columns disposed in a predetermined arrangement wherein each antenna column is spaced equidistant from any adjacent antenna columns at a spacing determined to provide said antenna beams with said operating attributes; and

a beam forming matrix having a first set of interfaces associated with antenna beam signals and a second set of interfaces associated with a phase progression of said antenna beam signals coupled to said antenna columns, wherein second set of interfaces are each coupled to a different one of said antenna columns.

45. The system of claim 44, wherein said beam forming matrix is a 2ⁿ⁺¹ by 2ⁿ⁺¹ Butler matrix.

46. The system of claim 44, wherein ones of said antenna columns are shorter than other ones of said antenna columns.

47. The system of claim 46, wherein each antenna column of said antenna columns includes a same number of antenna elements therein.

48. The system of claim 46, wherein said shorter antenna columns include a dielectric material disposed in the feed path of said compressed ones of said antenna columns.

49. The system of claim 44, wherein said number n is 2 .

50. The system of claim 49, wherein said column spacing is between 0.25λ

and 0.35λ

inclusive.

51. The system of claim 49, wherein said column spacing is 0.27λ

.

52. The system of claim 49, wherein said column spacing is also determined to provide an antenna beam having desirable attributes when multiple ones of said first set of interfaces are provided a same antenna beam signal.

53. The system of claim 52, wherein a first mode of communication signal is provided individual ones of said first set of interfaces and a second mode of communication signal is provided said multiple ones of said first set of interfaces.