Split aperture array for increased short range target coverage

• US 7,737,879 B2
• Filed: 05/23/2008
• Issued: 06/15/2010
• Est. Priority Date: 06/09/2006
• Status: Expired due to Fees

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Nickels, Matthew T., Delfanian, Neemah, Shanmuganandham, Krishnan J., Tietjen, Byron W.
• Primary Examiner(s): Tarcza; Thomas H
• Assistant Examiner(s): Brainard; Timothy A
• Application Number:
  US12/126,400
• Publication Number:
  US 20080291087A1
• Time in Patent Office: 753 Days
• Field of Search: 342/59
• US Class Current: 342/59
• CPC Class Codes: G01S 13/426 Scanning radar, e.g. 3D radar G01S13/66 takes precedence
• CPC Class Codes: G01S 2013/0254 Active array antenna
• CPC Class Codes: G01S 2013/0272 Multifunction radar
• CPC Class Codes: G01S 7/03 Details of HF subsystems specially adapted therefor, e.g. common to transmitter and receiver
• CPC Class Codes: H01Q 21/065 Patch antenna array

Abstract

A phased array radar system comprising a plurality of radiating elements configured in a common array aperture for detecting and tracking targets; and a transmit and receive arrangement responsive to a first control signal for configuring the plurality of radiating elements to define a plurality of sub-apertures from the common array aperture for detecting and tracking short range targets, wherein the plurality of sub-apertures are independently steerable array apertures and include an amplitude taper applied across each of the plurality of sub-apertures to reduce a peak sidelobe level.

Claims

1. A phased array radar system comprising:

a plurality of radiating elements configured in a common array aperture for detecting and tracking targets in a long range mode or a short range mode of operation;

a control processor operatively coupled to a pair of exciter and receiver arrangements coupled in parallel to said array, said control processor adapted for configuring said plurality of radiating elements to define a plurality of sub-apertures from said common array aperture for detecting and tracking short range targets, wherein said plurality of sub-apertures are each independently steerable array apertures, each sub-aperture communicating with a respective one of said pair of exciter and receiver arrangements;

wherein in said short range mode, each of said exciter pairs is responsive to a corresponding pulse waveform to form separate beams from said sub-apertures differing in at least one of frequency, phase, and beam pointing direction;

wherein in said long range mode, each of said exciter pairs is responsive to a corresponding pulse waveform of the same frequency, phase, and beam pointing direction to coherently combine signal data to form a single narrowband beam from said sub-apertures;

wherein in said short range mode, said control processor is adapted to apply a first amplitude taper across each of the plurality of sub-apertures to reduce at least one peak sidelobe level; and

wherein in said long range mode, said control processor is adapted to apply a second amplitude taper across each of said plurality of sub-apertures to reduce at least one peak sidelobe level.

2. The system of claim 1, wherein said plurality of sub-apertures comprises a first aperture for providing a beam at a first frequency, and a second aperture fin providing a beam at a second frequency.

3. The system of claim 2, wherein said first aperture and second aperture are combined to form a full aperture.

4. The system of claim 3, wherein a set of Taylor weights is applied to the full aperture.

5. The system of claim 3, wherein a full aperture operation produces a substantially ninety percent probability of detection at a target range of substantially 500 meters for incoming projectiles having a muzzle velocities between substantially 200 and 800 meters per second and having corresponding incoming angle less than 200 mils.

6. The system of claim 3, wherein a full aperture operation produces a substantially ninety percent probability of detection at a target range of substantially 900 meters for incoming projectiles having a muzzle velocities between substantially 200 and 800 meters per second and having corresponding incoming angle less than 600 mils.

7. The system of claim 3, wherein a full aperture operation produces a substantially ninety percent probability of detection at a target range of substantially 1300 meters for incoming projectiles having a muzzle velocities between substantially 200 and 800 meters per second and having corresponding incoming angle less than 900 mils.

8. The system of claim 3, wherein a full aperture operation produces a substantially ninety percent probability of detection at a target range of substantially 2100 meters for incoming projectiles having a muzzle velocities between substantially 200 and 800 meters per second and having corresponding incoming angle less than 1400 mils.

9. The system of claim 2, wherein a split aperture operation produces a substantially ninety percent probability of detection at a target range of substantially 500 meters for incoming projectiles having a muzzle velocities between substantially 200 and 800 meters per second and having corresponding incoming angle less than 700 mils.

10. The system of claim 2, wherein a split aperture operation produces a substantially ninety percent probability of detection at a target range of substantially 900 meters for incoming projectiles having a muzzle velocities between substantially 200 and 800 meters per second and having corresponding incoming angle less than 1200 mils.

11. The system of claim 2, wherein a split aperture operation produces a substantially ninety percent probability of detection at a target range of substantially 1300 meters for incoming projectiles having a muzzle velocities between substantially 200 and 800 meters per second and having corresponding incoming angle less than 1400 mils.

12. The system of claim 2, wherein a split aperture operation produces a substantially ninety percent probability of detection at a target range of substantially 2100 meters for incoming projectiles having a muzzle velocities between substantially 200 and 800 meters per second and having corresponding incoming angle less than 1400 mils.

13. The system of claim 1, wherein the first and second amplitude tapers comprise one or more sets of Taylor weights.

14. The system of claim 1, wherein the Taylor weights are applied to the array antenna aperture to produce a sum beam.

15. The system of claim 1, wherein a set of Taylor weights is applied to the first aperture and a set of Taylor weights is applied to the second aperture.

16. The system of claim 1 further comprising a fire control system to detect a moving target, lock onto the target and direct armament to destroy the target.

17. A phased array radar system having a plurality of radiating elements configured in a common array aperture of inn elements, said system comprising:

a controller for configuring a first subset of said elements of said common array aperture into a first sub-array for providing a first interrogating beam; and

a second subset of said elements of said common array aperture distinct from said first subset, into a second sub-ray for providing a second interrogating beam;

a pair of transmitters, each one coupled to a corresponding one of said first and second sub-arrays and responsive to said controller for simultaneously generating said first and second interrogating beams, said beams being independently steerable;

wherein said pair of transmitters are adapted to switchably apply a first amplitude taper across said first sub-array and a second amplitude taper across said second sub-array in a split aperture mode and are adapted to switchably apply a third amplitude taper coherently across said first sub-array and said second sub-array in a full aperture mode;

a pair of receiver beamformers, each one coupled to a corresponding one of said first and second sub-arrays for providing beamformed output data indicative of target reflections from each of said first and second interrogating beams and

a signal processor arrangement responsive to said beamformed output data for determining target detection and tracking according to each said sub-array.

18. The system of claim 17, wherein said pair of transmitters are adapted to independently apply said first amplitude taper to said first sub-array and said second amplitude taper to said second sub-array.

19. The system of claim 18, wherein said first amplitude taper, said second amplitude taper, and said third amplitude taper each comprise one or more sets of Taylor weights.

20. In a phased array radar system having a plurality of radiating elements configured in a common array aperture of m×

n elements, a method for detecting and tracking targets comprising;

electronically separating said common array aperture of m×

n elements into a first sub-aperture comprising a first subset of said m×

n elements defining a first sub-array, and a second sub-aperture comprising a second subset of said m×

n elements distinct from said first subset defining a second sub-array;

in a first mode, generating a first interrogating beam of a first frequency from said first sub-array, and a second interrogating beam of a second frequency from said second sub-away, said first and second interrogating beams differing in at least one of frequency, phase, and beam pointing direction;

independently steering said first and second interrogating beams;

receiving beamformed data from each of said first and second sub-apertures corresponding to said interrogating beams, independently processing said beamformed data to provide target information for each of said first and second sub-apertures, applying an amplitude taper across said first sub-away to reduce a first peak sidelobe level, and applying an amplitude taper across said second sub-array to reduce a second peak sidelobe level;

in a second mode, coherently operating said first and second sub-arrays to generate a narrowband interrogating beam of a given frequency corresponding to the full common array aperture, receiving beamformed data from each of said first and second sub-apertures corresponding to said narrowband interrogating beam, combining said beamformed data to provide target information indicative of the full common away aperture, and applying an amplitude taper across said full common array aperture to reduce a third peak sidelobe level.