Polygonal cylinder array antenna

• US 7,522,095 B1
• Filed: 05/31/2006
• Issued: 04/21/2009
• Est. Priority Date: 07/15/2005
• Status: Expired due to Fees

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Wasiewicz, Richard, Stockmann, Peter H.
• Primary Examiner(s): Tarcza; Thomas H
• Assistant Examiner(s): Bythrow; Peter M
• Application Number:
  US11/443,815
• Time in Patent Office: 1,056 Days
• Field of Search: 343/700.MS, 343/705, 343/706, 343/708, 343/893, 342/368, 342/371, 342/160, 342/422, 342/423, 342/428
• US Class Current: 342/160
• CPC Class Codes: G01S 13/424 Stacked beam radar
• CPC Class Codes: G01S 2013/0254 Active array antenna
• CPC Class Codes: G01S 2013/0272 Multifunction radar
• CPC Class Codes: H01Q 1/28 Adaptation for use in or on aircraft, missiles, satellites, or balloons
• CPC Class Codes: H01Q 21/20 the units being spaced along or adjacent to a curvilinear path slotted waveguide arrays H01Q21/005; circularly or helically slotted waveguides H01Q21/0062

Abstract

A polygonal cylindrically shaped phased array antenna forming a radar has an active aperture that focuses in any of one or more angular azimuth directions without inertia. It further includes adjacent multiple similar polygonal staves joined along their vertical edges to form a right regular polygonal cylinder. Each stave is further decomposed into flat panels, wherein each panel has a plurality of antenna elements positioned in a regular rectangular or triangular lattice. Each panel contains a beam forming network that electronically forms and steers an electromagnetic beam for purposes of transmission and subsequent reception. The panels optionally may operate as autonomous radars which when coherently combined form multiple larger antenna apertures, each capable of operating autonomously. A switching network allows transmit power and all requisite radar and control signals to be sent to and received from a selected set of panels anywhere on the polygonal cylinder.

Claims

1. A radar antenna array comprising:

a cylinder having thereon a plurality of rows of panels, wherein each panel is an electronically scanned antenna array that independently forms, steers, transmits and receives electromagnetic beams, and wherein each of the plurality of rows of panels comprises inactive panels and at least one set of selected active panels configured to be staggered relative to a selected set of active panels in an adjacent row.

2. The radar antenna array of claim 1, wherein the cylinder is a right circular cylinder.

3. The radar antenna array of claim 1, wherein the panels are rectangular.

4. The radar antenna array of claim 1, wherein the panels are flat and joined along vertical edges.

5. The radar antenna array of claim 2, wherein the panels are tangent to the right circular cylinder, such that the panels form a right polygonal cylinder having M panels along the circumference of the cylinder and N horizontal panels along the axis of the cylinder.

6. The radar antenna array of claim 1, further including a signal switching distribution network that allows transmit power and control signals to be sent to selected subsets of the panels.

7. The radar antenna array of claim 1, further including a signal switching distribution network that allows the incoming radar signal returns to be received as outputs from selected subsets of the panels.

8. The radar antenna array of claim 7, wherein a processor combines the outputs of the selected subsets of the panels to provide an output signal indicative of the radar coverage area.

9. The radar antenna array of claim 1, wherein the panels form an active aperture that focuses in one or more angular azimuth directions without inertia.

10. The radar antenna array of claim 5, wherein each of the panels is further decomposed into flat rectangular panels joined along the horizontal edges wherein each panel includes a plurality of antenna elements positioned in one of rectangular, triangular or hexagonal tessellation of the plane.

11. The radar antenna array of claim 1, wherein each panel contains a beamforming network that electronically forms and steers the electromagnetic beam for purposes of transmission and reception.

12. The radar antenna array of claim 1, wherein the panels operate as autonomous radars, which when electronically combined form multiple antenna apertures, each capable of operating autonomously.

13. A radar antenna array comprising:

a plurality of antenna elements affixed in adjacent parallel rows to a cylindrical surface to emit and receive electromagnetic signals in forming multiple electromagnetic beams, each of said plurality of antenna elements being adapted to operate as a corresponding autonomous electronically scanned radar, wherein each radar element is capable of independently forming, steering, and shaping transmit and receive beams, and wherein each of the plurality of rows of said antenna elements comprises inactive panels and at least one set of selected active antenna elements configured to be staggered relative to a selected set of active antenna elements in an adjacent row.

14. The radar antenna array of claim 13, wherein said antenna array has an electromagnetic radiation field of view relative to a longitudinal axis.

15. The radar antenna array of claim 13, wherein said antenna array has an electromagnetic radiation field of view of plus or minus 60 degrees relative to a longitudinal axis.

16. The radar antenna array of claim 13, wherein said array is affixed to a non-planar mounting structure providing instantaneous scan capability over a full 360°

azimuth without at least one of inertia and scan loss.

17. The radar antenna array of claim 13, wherein the array is mounted to an airship.

18. The radar antenna array of claim 17, wherein the array is independent of the surface of the airship to which it is mounted.

19. A radar antenna comprising:

a polygonal cylindrically shaped active aperture that focuses in one or more angular azimuthal directions and includes a beamformer and a plurality of transmit-receive panels wherein each panel has a corresponding set of transmit-receive modules having phase shifters with amplitude control to generate multiple independent and simultaneous beams distributed to one or more associated transmit-receive panels of the set of panels, wherein the panels having corresponding sets of transmit-receive modules having phase shifters with amplitude control are electronically combined in subsets to form multiple radars, and wherein the multiple radars have multiple staggered rows, which serve as multiple independent radars.

20. The antenna array of claim 19, wherein the radar antenna is operative in a receive mode, and wherein the transmit-receive modules are synchronized to previous transmissions.

21. The antenna array of claim 19, wherein the radar antenna is operative in a transmit mode, and wherein multiple simultaneous transmissions emanate from separate panels on the cylinder.

22. The antenna array of claim 19, wherein an amplitude taper across the elements of each panel are variably controlled.

23. The antenna array of claim 19, wherein the element amplitude control maintains low sidelobes on transmit and receive.

24. The antenna array of claim 19, wherein the beamformer includes phase spoiling to broaden the radar transmit beams in azimuth.

25. The antenna array of claim 19, wherein each transmit beam includes multiple simultaneous and narrow receive beams to provide increased target dwell time.

26. The antenna array of claim 19, wherein each panel is operative as an independent sub-radar.

27. The antenna array of claim 19, wherein each individual panel transmit-receive module has a corresponding transmit-receive element.

28. The antenna array of claim 19, wherein the multiple radars are coherently combined to form one or more single pencil-beam radars.

29. The antenna array of claim 19, wherein the array includes a non-linear phase progression across selected panels on transmit and complex amplitude and phase weighting across selected panels on receive to shape the two-way beam gain in elevation.

30. The antenna array of claim 19, wherein the beamformer produces a constant signal-to-noise ratio against a reference surface target at a fixed azimuth for a target range from the horizon into a pre-determined minimum range.

31. The antenna array of claim 19, wherein multiple simultaneous receive beams, each with identical elevation shape and each steered to a different azimuth fill the transmit beam.

32. The antenna array of claim 19, wherein each simultaneous beam has a substantially equivalent and constant signal-to-noise ratio.

33. The antenna array of claim 19, wherein the panel electromagnetic near-field radiation pattern of the antenna is a projection of the panel shape in a direction perpendicular to the plane of the panel.

34. The antenna array of claim 19, wherein the panel electromagnetic far-field radiation phase front is substantially planar and subtends an angle with respect to the antenna array face as a function of the beam steering direction.

35. The antenna array of claim 19, wherein the panels are arranged as adjacent staves in a square matrix around the circumference of the cylinder.

36. The antenna array of claim 19, wherein an electronic system adjusts the amplitude and phase of each panel element independently.

37. The antenna array of claim 19, further comprising including an analog system, a plurality of panel manifolds that feed and receive signals of the transmit-receive module, a plurality of wave form generators, a plurality of up conversion processors that feed the panel manifolds, and a plurality of receiver and digital demodulators that receive signals from the panel manifolds.

38. The antenna array of claim 37, wherein the panel manifolds receive amplified element signals and feed the signals to the plurality of receiver and digital demodulators.

39. The antenna array of claim 37, wherein the panel manifolds distribute element signals on transmit and coherently combine element signals on receive.

40. The antenna array of claim 37, further including a digital system comprising a digital fiber link that feeds the plurality of wave form generators and an up converter that receives the plurality of receiver and digital demodulators return signals.

41. The antenna array of claim 40, wherein the demodulators within the receiver and digital demodulators receive radar return signals and produce a demodulated radar signal.

42. The antenna array of claim 40, wherein the receivers, demodulators and associated beamforming networks combine the panel elements to amplify the beamformer output and associated downconverters into digitized in-phase and quadrature-phase signals for signal processing.

43. The antenna array of claim 40, wherein a panel selector and distributor each feeds and receives transmission signals from the fiber link.

44. The antenna array of claim 43, wherein the fiber link receives analog signals and converts the analog signal to digital signals so as the panel selector and distributor receives radar return signals from the fiber link for signal processing.

45. The antenna array of claim 43, wherein the panel selector and distributor each receive input data from a radar controller to select certain of the panels for operation as a group.

46. A radar antenna array comprising:

a right regular polygonal cylinder having multiple generally flat rectangular columnar stave panels and row panels, each capable of operating as an autonomous electronically scanned radar, and each capable of independently forming, steering, and shaping transmit and receive beams, having selective sets of active staves whereby signals and power are sent to various subsets of staves to form one or more active radar and wherein each of the plurality of rows of panels comprises inactive panels and at least one set of selected active panels configured to be staggered relative to a selected set of active panels in an adjacent row.

47. The antenna array of claim 46, wherein a subset of staves whose average normal is closest in azimuth to the desired beam azimuth are electronically identified.

48. The antenna array of claim 46, wherein the staves whose individual statistical normals deviate from the desired azimuth direction by more than a pre-selected threshold angle are electronically excluded from processing.

49. The antenna array of claim 46, further comprising a panel selector in combination with a panel-level multi-radar to configure the selected staves as a radar having outputs that are coherently combined.

50. The antenna array of claim 46, wherein phase progressions are applied to the stave and row panels to electronically steer the net beam to the desired angle.

51. The antenna array of claim 46, wherein electronic steering is less than 180/M degrees, where M is the number of staves.

52. The antenna array of claim 46, wherein the antenna is mounted in an airship, such that as the airship rotates, the selected set of staves moves about the polygonal cylinder to maintain its near-normal orientation with respect to the desired beam direction.

53. The antenna array of claim 52, wherein the radar beam probes a given earth-fixed azimuth independent of the airship orientation.

54. The antenna array of claim 46, wherein selected panel sets of staggered active panels and inactive panels has M staves and N panels per stave.

55. The antenna array of claim 46, wherein the selected sets of panel transmit aperture are uniformly weighted in amplitude and the receive aperture of weights are applied to each stave.

56. A process comprising:

forming a plurality of electromagnetic beams for transmission from a subset of a plurality of antenna elements affixed in parallel rows to a cylindrical surface wherein the subset of antenna elements are selected in such a way that each of the plurality of rows of antenna elements comprises inactive panels and at least one set of selected active panels configured to be staggered relative to a selected set of active panels in an adjacent row;

receiving electromagnetic energy associated with the plurality of beams at a plurality of antenna elements affixed in parallel rows to a cylindrical surface;

setting one or more phase and gain control devices associated with each antenna element;

combining multiple signals received from the antenna elements; and

generating control signals to drive the phase and gain control devices to create the beams.

57. The process of claim 56, wherein, the step of combining multiple signals comprises the steps of:

computing an in-phase component for the control signal for each antenna element comprising a sum of in-phase beam components for the corresponding antenna element;

computing a quadrature component for the control signal for each antenna element comprising a sum of quadrature beam components for the corresponding antenna element; and

computing a total gain and a total phase shift for each antenna element from the corresponding in-phase and quadrature components.

58. The process of claim 56, wherein the in-phase beam components for each antenna element include an in-phase component corresponding to each beam;

and the quadrature beam components for each antenna element include a quadrature component corresponding to each beam.

59. The process of claim 56, wherein forming beams further comprises steering, and shaping transmit and receive beams.