Linear array dual polarization for roll compensation

• US 5,255,004 A
• Filed: 09/09/1991
• Issued: 10/19/1993
• Est. Priority Date: 09/09/1991
• Status: Expired due to Fees

• Current Assignee: Cubic Defense Systems, Inc. (Cubic Corporation)
• Original Assignee: Cubic Defense Systems, Inc. (Cubic Corporation)
• Inventors: Miller, David J., Eberhardt, Paul R., Berkowitz, Bernard
• Primary Examiner(s): Hille, Rolf
• Assistant Examiner(s): BROWN, PETER T
• Application Number:
  US07/756,454
• Time in Patent Office: 771 Days
• Field of Search: 343/770, 343/771, 343/776, 343/797, 343/799, 343/810, 343/812-814, 343/853, 342/149, 342/153, 342/154, 342/361, 342/362
• US Class Current: 343/853
• CPC Class Codes: H01Q 25/02 providing sum and difference patterns H01Q25/04 takes precedence

Abstract

A planar array of linearly polarized antenna elements, each element tilted so that its polarization orientation is disposed at an angle with respect to the array vertical axis so that array polarization loss is minimized as a function of roll about an array normal. Half of the elements are tilted uniformly at a positive angle with respect to the array vertical axis and the remaining elements are tilted at a negative angle with respect to the array vertical axis. The invention substantially reduces the unwanted variation in received RF energy magnitude as a function of array roll angle caused by polarization loss, for both vertical and horizontal components. The vertically polarized signal component magnitude remains nearly constant with respect to array roll angle values of 50°-60° and more. If the element tilt angle magnitude is between 0°-45°, the vertically polarized components from the two element groups are additive whereas the horizontally polarized components from the two groups are subtractive. Monopulse sum and difference outputs isolate the vertical and horizontal energy components. Broadside beam scanning without losing this roll compensation is possible if the two element groups are segregated into horizontal rows spanning the planar array.

Claims

1. A planar array having a vertical center line in the array plane, said array comprising:

at least one row of linearly polarized antenna elements disposed in said array plane with an equal number of said elements disposed on first and second sides of said center line, each said element on said first side corresponding to one said element on said second side;

each said element disposed such that its polarization orientation is tilted at an angle with respect to said vertical center line, said tilt angles of said corresponding elements having opposite signs and magnitudes greater than 0° and

less than 90°

;

first summing means for adding the output signals from all said elements on a first said side to form a first sum signal;

second summing means for adding the output signals from all said elements on the second said side to form a second sum signal; and

third summing means for combining said first and second sum signals to form a monopulse sum signal and a monopulse difference signal.

2. The planar array described in claim 1 wherein:

said tilt angles are identical for all said elements on a single said side.

3. The planar array described in claim 2 wherein:

each said element tilt angle is disposed inwardly toward said center line.

4. The planar array described in claim 3 wherein:

each said row is disposed orthogonally to said center line.

5. The planar array described in claim 4 further comprising:

phase delay means for steering the primary array pattern lobe at an angle with respect to an array normal.

6. The planar array described in claim 1 wherein:

each said antenna element comprises a center-fed unipolar exponential slot radiator.

7. The planar array described in claim 3 wherein:

said inward element tilt angle is inwardly disposed by an identical amount on each said side.

8. The planar array described in claim 2 wherein:

each said element tilt angle is disposed outwardly away from said center line.

9. The planar array described in claim 8 wherein:

said outward tilt angle is outwardly disposed by an identical amount on each said side.

10. The planar array described in claim 2 wherein:

the magnitude of each said element tilt angle is equal to 45°

.

11. The planar array described in claim 1 wherein:

each said element tilt angle is disposed inwardly toward said center line.

12. The planar array described in claim 1 wherein:

each said element tilt angle is disposed outwardly away from said center line.

13. The planar array described in claim 1 wherein:

each said element row is disposed orthogonally to said center line.

14. The planar array described in claim 1 further comprising:

phase delay means for steering the primary array pattern lobe at an angle with respect to an array normal.

15. A planar array having a vertical axis and a horizontal axis, said array comprising:

a plurality of linearly polarized antenna elements disposed in said array plane such that the polarization orientation of each said element is titled at an angle with respect to said vertical array axis, said angle having a magnitude equal to 45°

;

wherein half of said elements are disposed on each side of said vertical array axis, said vertical array axis not intersecting any of said antenna elements;

wherein half of said elements are tilted in a first horizontal direction and all remaining said elements are tilted in the second horizontal direction;

first summing means for adding the output signals from all said elements having a tilt angle in said first horizontal direction to form a first sum signal;

second summing means for adding the output signals from all said elements having a tilt angle in said second horizontal direction to form a second sum signal; and

third summing means for combining said first and second sum signals to form a monopulse sum signal and a monopulse difference signal.

16. The planar array described in claim 15 further comprising:

phase delay means for steering the primary array pattern lobe at an angle with respect to an array normal.

17. The planar array described in claim 16 wherein:

each said antenna element comprises a center-fed unipolar exponential slot radiator.