Linearly polarized active artificial magnetic conductor

• US 10,193,233 B1
• Filed: 09/16/2015
• Issued: 01/29/2019
• Est. Priority Date: 09/17/2014
• Status: Active Grant

• Current Assignee: HRL Laboratories LLC (The Boeing Co.)
• Original Assignee: HRL Laboratories LLC (The Boeing Co.)
• Inventors: Gregoire, Daniel, White, Carson, Colburn, Joseph
• Primary Examiner(s): Han, Jessica
• Assistant Examiner(s): Patel, Amal
• Application Number:
  US14/856,541
• Time in Patent Office: 1,231 Days
• CPC Class Codes: H01Q 15/008 said selective devices having Sievenpipers' mushroom elements
• CPC Class Codes: H01Q 15/14 Reflecting surfaces; Equivalent structures electromagnetic shields H01Q1/526

Abstract

An active artificial magnetic conductor comprising an array of unit cells, each unit cell comprising an electrically conductive patch that is connected with an electrically conductive patch of neighboring unit cell in a column of unit cells using a non-Foster negative inductor and having RF isolating plates or walls between rows of unit cells. These isolating plates or walls eliminate undesirable cross coupling between the non-Foster negative inductors. The electrically conductive patches may be formed by metallic patches preferably arranged in the 2D array of such patches. Each patch preferably has a rectilinear shape.

Claims

1. An active artificial magnetic conductor comprising:

an array of unit cells arranged in a plurality of rows and columns, each unit cell comprising an electrically conductive patch spaced from a ground plane, the electrically conductive patches of the unit cells arranged in each column of unit cells being coupled via a Non-Foster Circuit (NFC) impedance element to an electrically conductive patch of a neighboring unit cell in each column of unit cells and the electrically conductive patches of the unit cells arranged in each row of unit cells being connected via an electrically conductive isolating wall to said ground plane at a mid point of each electrically conductive patch in the row of unit cells, the electrically conductive isolating walls of the rows of unit cells comprising electrically conductive material which occupies a majority of space between opposing edges of electrically conductive patches in each row of unit cells.

2. The active artificial magnetic conductor of claim 1 wherein each electrically conductive patch is a metallic patch of a predetermined geometric shape.

3. The active artificial magnetic conductor of claim 2 wherein each electrically conductive patch is a square metallic patch.

4. The active artificial magnetic conductor of claim 1 wherein each electrically conductive isolating wall is formed of an integral piece of metal extending across each unit cell.

5. The active artificial magnetic conductor of claim 1 wherein the electrically conductive isolating walls are each formed by linear arrays closely spaced metallic posts.

6. A method of electrically stabilizing an active artificial magnetic conductor, the active artificial magnetic conductor comprising an array of unit cells, each unit cell comprising an electrically conductive patch that is (i) spaced from a ground plane of the active artificial magnetic conductor and (ii) connected to a neighboring electrically conductive patch with a non-Foster negative inductor in a direction parallel to an E-plane, the method comprising reducing E-plane coupling between the non-Foster negative inductors of the active artificial magnetic conductor by disposing, forming or inserting isolating walls in a direction parallel to an H-plane between the non-Foster negative inductors, the isolating walls further extending in a direction perpendicular to said E-plane between neighboring electrically conductive patches and occupying a majority of a space between opposing edges of the neighboring electrically conductive patches in the direction perpendicular to said E-plane, the isolating walls being coupled to said ground plane.

7. The method of claim 6 wherein the array of unit cells comprises a two dimensional array of unit cells arranged in columns and rows, the isolating walls are disposed between pairs electrically conductive patches at a mid point of each of said pairs of electrically conductive patches in adjacent rows of electrically conductive patches while the non-Foster negative inductors are disposed at a mid point of each electrically conductive patch in adjacent columns of electrically conductive patches.

8. The method of claim 6 wherein the isolating walls are formed of a solid plate of metallic material.

9. The method of claim 6 wherein each unit cell has dielectric material disposed between the electrically conductive patch and the ground plane of the active artificial magnetic conductor, the isolating walls being formed by forming a plurality of vias in said dielectric substrate and filling said vias with a metallic material.

10. The method of claim 6 wherein each electrically conductive patch has a rectilinear shape.

11. The method of claim 6 wherein each electrically conductive patch has a square shape.

12. The method of claim 11 where the active artificial magnetic conductor is responsive to incident RF waves and wherein said E-plane and said H-plane correspond, respectively, to an E-plane and said H-plane of said incident RF waves.

13. An active artificial magnetic conductor responsive to incident RF waves, the active artificial magnetic conductor comprising an array of unit cells, each unit cell comprising an electrically conductive patch that is (i) spaced from a ground plane of the active artificial magnetic conductor and (ii) connected to neighboring electrically conductive patches with non-Foster negative inductors in a direction parallel to an E-plane of the incident RF waves, the active artificial magnetic conductor including means for reducing the E-plane coupling between the non-Foster negative inductors of the active artificial magnetic conductor comprising isolating walls disposed, formed or inserted in a direction perpendicular to the E-plane between the non-Foster negative inductors, the isolating walls being disposed in a common linear direction between neighboring electrically conductive patches parallel to the H-plane of the incident RF waves, each isolating wall extending between the ground plane of the active artificial magnetic conductor and the electrically conductive patch of each unit cell, each isolating wall occupying a majority of a space between opposing edges of the electrically conductive patches in the direction perpendicular to the E-plane.

14. The active artificial magnetic conductor of claim 13 wherein the array of unit cells comprises a two dimensional array of unit cells arranged in columns and rows, the isolating walls being disposed at a mid point of each electrically conductive patch in a row of electrically conductive patches while the non-Foster negative inductors are disposed at a mid point of each electrically conductive patch in a column of electrically conductive patches.

15. The active artificial magnetic conductor of claim 13 wherein the isolating walls comprise a solid plate of metallic material extending between opposing edges of the electrically conductive patch of each unit cell.

16. The active artificial magnetic conductor of claim 13 wherein each unit cell has a dielectric material disposed between the electrically conductive patches and the ground plane of the active artificial magnetic conductor, the isolating walls being defined by a plurality of metallic posts in said dielectric substrate.

17. The active artificial magnetic conductor of claim 16 wherein said metallic posts associated with each unit cell are arranged in a rectilinear array of posts.

18. The active artificial magnetic conductor of claim 13 wherein each electrically conductive patch has a rectilinear shape.

19. The active artificial magnetic conductor of claim 18 wherein each electrically conductive patch has a square shape.

20. A magnetic conductor comprising:

an array of unit cells arranged in a plurality of rows and columns, each unit cell comprising an electrically conductive patch spaced from a ground plane, the electrically conductive patches of the unit cells arranged in each column of unit cells being coupled via a Non-Foster Circuit (NFC) impedance element to an electrically conductive patch of a neighboring unit cell in each column of unit cells, the electrically conductive patches of the unit cells arranged in each row of unit cells having an electrically conductive isolating wall connected to said ground plane and connected at a mid point of each electrically conductive patch in the row of unit cells and the electrically conductive isolating walls of the rows of unit cells extending along a majority of the distance between opposing edges of electrically conductive patches in each row of unit cells.

21. The magnetic conductor of claim 20 wherein each electrically conductive patch is a metallic patch of a predetermined geometric shape.

22. The magnetic conductor of claim 21 wherein each electrically conductive patch has a square metallic patch.