SPLIT APERTURE ARRAY FOR INCREASED SHORT RANGE TARGET COVERAGE

• US 20080291087A1
• Filed: 05/23/2008
• Published: 11/27/2008
• Est. Priority Date: 06/09/2006
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Tietjen, Byron W., Nickels, Matthew T., Delfanian, Neemah, Shanmuganandham, Krishnan J.
• Granted Patent: US 7,737,879 B2
• Time in Patent Office: Days
• US Class Current: 342/372
• 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;

means responsive to a first control signal 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 independently steerable array apertures;

means to apply an amplitude taper across each of the 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 for 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 1, wherein the amplitude taper comprises one or more sets of Taylor weights.

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

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

7. 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.

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 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.

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 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.

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 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.

12. 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.

13. 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.

14. 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.

15. 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.

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 m×

n elements, said system comprising;

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

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;

a first amplitude taper applied across said first sub-arrays and a second amplitude taper applied across said second sub-arrays each of the tapers applied to reduce one or more peak sidelobe levels;

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

18. 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-array, 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, and 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-array to reduce a first peak sidelobe level;

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;

receiving beamformed data from each of said first and second sub-apertures corresponding to said narrowband interrogating beam, and combining said beamformed data to provide target information indicative of the full common array aperture; and

applying an amplitude taper across said the full common array aperture to reduce a third peak sidelobe level.