Antenna array with robust failed-element processor

• US 8,049,661 B1
• Filed: 11/15/2007
• Issued: 11/01/2011
• Est. Priority Date: 11/15/2007
• Status: Expired due to Fees

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Loberger, David G.
• Primary Examiner(s): SOTOMAYOR, JOHN B
• Application Number:
  US11/940,571
• Time in Patent Office: 1,447 Days
• Field of Search: 342/173, 342/174, 342/81, 342/82, 342/157, 342/158, 342/159, 342/162
• US Class Current: 342/173
• CPC Class Codes: G01S 2013/0254 Active array antenna
• CPC Class Codes: H01Q 3/267 Phased-array testing or checking devices

Abstract

An array antenna has elements spaced less than one-half wavelength in order to produce a spatial pattern which has both visible and invisible regions. The elements in their nominal state are weighted so as to define particular sidelobe levels. In the presence of failed elements which might otherwise degrade the sidelobe levels, the element weighting function is compensated so as to preserve the sidelobe levels within the visible region of the antenna pattern by placing most or all of the degradation of the sidelobe levels into the invisible region of the antenna pattern.

Claims

1. A method for generating a beam from an antenna, said method comprising the steps of:

providing an array antenna including antenna transducing elements spaced at less than one-half wavelength, whereby the element-to-element phase shift defines visible and invisible regions for the antenna beam spatial pattern;

applying uncompensated weights to signals of said antenna transducing elements of said array antenna when no antenna elements have failed, so as to provide a specified sidelobe level distribution;

identifying at least one failed antenna transducing element of said antenna transducing elements;

in the presence of said at least one failed antenna transducing elements, which degrade the sidelobe levels, applying compensated weights to said signals of said antenna transducing elements of said array antenna so as to place a principal portion of the degradation of said side lobe levels into said invisible region, whereby the side lobe levels within said visible region are maintained at said specified sidelobe level.

2. A method according to claim 1, wherein said step of applying compensated weights to said signals of said antenna transducing elements of said array antenna so as to place the principal, portion of the degradation of said sidelobe levels into said invisible region comprises the step of applying compensated weights to said signals of said antenna transducing elements of said array antenna so as to place the principal portion of the degradation of said sidelobe levels into a first portion of said invisible region remote from said visible region.

3. A method according to claim 2, wherein said first portion of said invisible region is spaced apart from said visible region by a second portion of said invisible region having a selected range of phase shifts, the method further comprising the step of:

adjusting an element-to-element phase shift so as to scan said antenna beam and to move at least a part of said second portion of said invisible region into said visible region.

4. A method according to claim 1 wherein said step of applying compensated weights comprises the steps of:

generating a mathematical matrix in which each column of the mathematical matrix corresponds to an antenna transducing element;

selecting columns of said mathematical matrix which correspond to failed antenna transducing elements in order to form selected column vectors;

orthogonalizing said selected column vectors in order to remove overlapping components to thereby generate orthogonalized vectors;

selecting weight values of said uncompensated weights which correspond to the failed antenna transducing elements of the antenna in order to form corresponding weight values;

processing said corresponding weight values analogously to the orthogonalization processing of the selected column vectors in order to generate processed corresponding weight values;

normalizing said processed corresponding weight values to thereby generate normalized corresponding weight values;

calculating mathematical inner products of said orthogonalized vectors and the vectors which comprise the columns of said mathematical matrix in order to generate new vectors;

multiplying each of said new vectors by said normalized corresponding weight value in order to generate scaled new vectors; and

subtracting each said scaled new vector from said uncompensated weights in order to calculate the compensated weights.

5. A method according to claim 4, wherein said step of generating a mathematical matrix in which each column of the mathematical matrix corresponds to an antenna transducing element comprises the steps of:

generating column vectors which span angular region(s) of an antenna pattern which correspond to said invisible region(s) or to specified regions(s) of the antenna pattern in order to form generated column vectors; and

concatenating said generated column vectors so that each generated column vector constitutes a column of a matrix in order to form a mathematical G matrix, said G matrix including N columns, where the number of columns N is the same as the total number of antenna transducing elements, said G matrix also including M rows where the number of rows M corresponds to a number of vectors which are chosen to span the angular region(s) of the antenna pattern which correspond to said invisible regions(s) or to specified region(s) of the antenna pattern.

6. A method according to claim 5 for generating column vectors, wherein the generation of said column vectors comprising the steps of:

using the uncompensated weights; and

,

using phase values which span an angular region or regions of the antenna spatial pattern which is or are supplementary to the angular region or regions; and

,

where the phase values which span the supplementary angular region or regions are spaced no farther apart than 2nlN radians.

7. A method for receiving signals or transmitting signals with an antenna which can be compensated for performance degradations which are due to failed antenna transducing elements, said method comprising the steps of:

receiving signals from, or transmitting signals into, free space using an antenna comprising an array of antenna transducing elements;

applying uncompensated weights to signals of said antenna transducing elements in order to control sidelobe levels of the antenna in the absence of antenna transducing element failures;

identifying at least one failed antenna transducing element;

for degradations of sidelobe levels attributable to said at least one failed antenna transducing elements;

applying compensated weights to signals of said antenna transducing elements in order to adjust and compensate for said at least one failed antenna transducing elements; and

combining or adding signals for receiving signals from free space, or splitting or separating signals for transmitting signals into free space.

8. A method according to claim 7 whereby said step of using an antenna comprising an array of antenna elements includes the step of using a linear array of antenna elements;

and

said step of applying compensated weights for said at least one failed antenna transducing elements is applied to said linear array of antenna elements.

9. A method according to claim 7 whereby compensation for said at least one failed antenna transducing elements is applied to each dimension of multi-dimensional array antennas.

10. A method according to claim 7 wherein said step of calculating compensated weights uses information of which antenna transducing elements have failed along with the uncompensated weights and a mathematical matrix which has elements which are specified by a set of angle values which span supplement(s) of specified angular region(s) of antenna pattern.

11. A method according to claim 10 wherein said step of calculating compensated weights includes the steps of:

generating column vectors which correspond to the antenna transducing elements in order to form generated column vectors; and

concatenating said generated column vectors in order to form a mathematical matrix in which each column of the mathematical matrix corresponds to a generated column vector;

selecting columns of said mathematical matrix which correspond to the at least one failed antenna transducing elements in order to form selected column vectors;

orthogonalizing said selected column vectors in order to remove overlapping components to thereby generate orthogonalized vectors;

selecting weight values of the uncompensated weights which correspond to the at least one failed antenna transducing elements in order to form corresponding weight values;

processing said corresponding weight values analogously to the orthogonization processing of the selected column vectors in order to form processed corresponding weight values;

normalizing said processed corresponding weight values in order to form normalized corresponding weight values;

calculating mathematical inner products of said orthogonalized vectors and the vectors which comprise the columns of the mathematical matrix in order to form new vectors;

multiplying each said new vector by said normalized corresponding weight value in order to generate scaled new vectors; and

,

subtracting each said scaled new vector from the uncompensated weights in order to calculate the compensated weights.

12. A method according to claim 7 wherein for an antenna which has element spacings which are less than one-half of the wavelengths of operational radio frequencies of the antenna, said step of calculating compensated weights uses information of which elements have failed along with the uncompensated weights and a mathematical matrix which has elements which are specified by a set of phase values which span a phase region or regions which is or are supplementary to a region of phase values which steer the antenna beam over an entire visible angular region of the antenna.

13. A method according to claim 12 wherein said step of calculating compensated weights includes the steps of:

generating column vectors which correspond to the antenna transducing elements in order to form generated column vectors; and

,

concatenating said generated column vectors in order to form a mathematical matrix in which each column of the mathematical matrix corresponds to a generated column vector;

selecting columns of said mathematical matrix which correspond to the at least one failed transducing elements of the antenna in order to form selected column vectors;

orthogonalizing said selected column vectors in order to remove overlapping components to thereby generate orthogonalized vectors;

selecting weight values of the uncompensated weights which correspond to the at least one failed transducing element in order to form corresponding weight values;

processing said corresponding weight values analogously to the orthogonalization processing of the selected column vectors to thereby generate processed corresponding weight values;

normalizing said processed corresponding weight values in order to generate normalized corresponding weight values;

calculating mathematical inner products of said orthogonalized vectors and the vectors which comprise the columns of the matrix in order to generate new vectors;

multiplying each said new vector by said normalized corresponding weight value in order to generate scaled new vectors; and

,

subtracting each said sealed new vector from the uncompensated weights in order to calculate the compensated weights.

14. A method for generating a beam from an antenna, said method comprising the steps of:

providing an array antenna including antenna transducing elements, the array antenna defining an antenna spatial pattern with visible and invisible regions;

applying uncompensated weights to signals of said antenna transducing elements of said array antenna to provide a sidelobe level distribution;

identifying any failed elements of said antenna transducing elements;

applying compensated weights to signals of said antenna transducing elements of said array antenna wherein one or more of said antenna transducing elements are identified as failed elements, so as to place at least a portion of any degraded sidelobe levels into said invisible region.

15. A system for receiving signals or transmitting signals with an antenna which can be compensated for performance degradations which are due to failed antenna transducing elements, said system comprising:

a processor executing instructions for performing the steps of;

receiving signals from, or transmitting signals into, free space using an antenna comprising an array of antenna transducing elements;

applying uncompensated weights to signals of said antenna transducing elements in order to control sidelobe levels of the antenna in the absence of antenna transducing element failures;

identifying at least one failed antenna transducing element;

for degradations of sidelobe levels attributable to said at least one failed antenna transducing element;

applying compensated weights to signals of said antenna transducing elements in order to adjust and compensate for said at least one failed antenna transducing element; and

combining or adding signals for receiving signals from free space, or splitting or separating signals for transmitting signals into free space.

16. A system according to claim 15 whereby said step of using an antenna comprising an array of antenna elements includes the step of using a linear array of antenna elements;

and

said step of applying compensated weights for said at least one failed antenna transducing element is applied to said linear array of antenna elements.

17. A system according to claim 15 whereby compensation for said at least one failed antenna transducing element is applied to each dimension of multi-dimensional array antennas.

18. A system according to claim 15 wherein said step of calculating compensated weights uses information of which antenna transducing elements have failed along with the uncompensated weights and a mathematical matrix which has elements which are specified by a set of angle values which span supplement(s) of specified angular region(s) of antenna pattern.

19. A system according to claim 18 wherein said step of calculating compensated weights includes the steps of:

generating column vectors which correspond to the antenna transducing elements in order to form generated column vectors; and

concatenating said generated column vectors in order to form a mathematical matrix in which each column of the mathematical matrix corresponds to a generated column vector;

selecting columns of said mathematical matrix which correspond to the at least one failed antenna transducing element in order to form selected column vectors;

orthogonalizing said selected column vectors in order to remove overlapping components to thereby generate orthogonalized vectors;

selecting weight values of the uncompensated weights which correspond to the at least one failed antenna transducing element in order to form corresponding weight values;

processing said corresponding weight values analogously to the orthogonization processing of the selected column vectors in order to form processed corresponding weight values;

normalizing said processed corresponding weight values in order to form normalized corresponding weight values;

calculating mathematical inner products of said orthogonalized vectors and the vectors which comprise the columns of the mathematical matrix in order to form new vectors;

multiplying each said new vector by said normalized corresponding weight value in order to generate scaled new vectors; and

,

subtracting each said scaled new vector from the uncompensated weights in order to calculate the compensated weights.

20. A system according to claim 15 wherein for an antenna which has element spacings which are less than one-half of the wavelengths of operational radio frequencies of the antenna, said step of calculating compensated weights uses information of which elements have failed along with the uncompensated weights and a mathematical matrix which has elements which are specified by a set of phase values which span a phase region or regions which is or are supplementary to a region of phase values which steer the antenna beam over an entire visible angular region of the antenna.