Current sheet array antenna

1. An antenna element, comprising:

a substrate;

a first dipole arm disposed on a first surface of the substrate;

a second dipole arm disposed on the first surface of the substrate;

a first capacitive structure, wherein the first capacitive structure includes:

a first capacitive element that extends from a branch portion of the first dipole arm towards a second surface of the substrate; and

a second capacitive element that extends from a branch portion of the second dipole arm towards the second surface of the substrate,

wherein the branch portion of the first dipole arm from which the first capacitive element extends is adjacent the branch portion of the second dipole arm from which the second capacitive element extends, and

wherein the first surface of the substrate is opposite the second surface of the substrate.

2. The antenna element of claim 1 , wherein the capacitive elements are parallel to one another.

3. The antenna element of claim 1 , wherein the capacitive elements are perpendicular to the first surface of the substrate.

4. The antenna element of claim 1 , wherein the capacitive elements include a plurality of plated vias.

5. The antenna element of claim 1 , wherein the capacitive elements include contiguous conductive walls.

6. The antenna element of claim 1 , wherein the first and second surfaces of the substrate are parallel to one another.

7. The antenna element of claim 1 , further comprising:

a ground plane, wherein the ground plane is disposed on the second surface of the substrate.

8. The antenna element of claim 1 , further comprising:

a dielectric material in a volume between the first and second capacitive elements.

9. The antenna element of claim 1 , further comprising:

a gas in a volume between the first and second capacitive elements.

10. The antenna element of claim 1 , further comprising:

a third dipole arm;

a fourth dipole arm;

a second capacitive structure;

a third capacitive structure; and

a fourth capacitive structure.

11. The antenna element of claim 10 ,

wherein the first capacitive element of the first capacitive structure extends from a second branch portion of the first dipole arm,

wherein the second capacitive element of the first capacitive structure extends from a first branch portion of the second dipole arm,

wherein the second capacitive structure includes:

a first capacitive element that extends from a second branch portion of the second dipole arm towards the second surface of the substrate; and

a second capacitive element that extends from a first branch portion of the third dipole arm,

wherein the third capacitive structure includes:

a first capacitive element that extends from a second branch portion of the third dipole arm towards the second surface of the substrate; and

a second capacitive element that extends from a first branch portion of the fourth dipole arm, and

wherein the fourth capacitive structure includes:

a first capacitive element that extends from a second branch portion of the fourth dipole arm towards the second surface of the substrate; and

a second capacitive element that extends from a first branch portion of the first dipole arm.

12. The antenna element of claim 11 , wherein viewed along a line perpendicular to the first surface of the substrate:

the capacitive elements of the first and third capacitive structures are parallel to a first line,

the capacitive elements of the second and fourth capacitive structures are parallel to a second line, and

the first line is perpendicular to the second line.

13. The antenna element of claim 12 , wherein each of the dipole arms includes a trunk portion, and wherein the branch portions of each of the dipole arms intersect one another at one end of the trunk portion.

14. An array antenna, comprising:

a substrate, wherein the substrate includes a first side and a second side opposite the first side;

a plurality of antenna elements, wherein each of the antenna elements includes:

first, second, third, and fourth dipole arms disposed on the first side of the substrate, wherein each of the dipole arms includes first and second branch portions; and

a plurality of capacitive elements, wherein at least one of the capacitive elements extends from each branch portion of each of the dipole arms in a direction towards the second side of the substrate.

15. The array antenna of claim 14 , further comprising:

a ground plane disposed on the second side of the substrate, wherein the capacitive elements are spaced apart from the ground plane.

16. The array antenna of claim 15 , wherein each branch portion in any one of the antenna elements is adjacent another branch portion in the same antenna element.

17. The array antenna of claim 16 , further comprising:

a plurality of trunk portions, wherein each dipole arm includes one trunk portion that is electrically connected to the branch portions of the respective dipole arm.

18. The array antenna of claim 17 , further comprising:

a feed network, wherein the trunk portion of each dipole arm connects the respective dipole arm to the feed network.

19. The array antenna of claim 14 , wherein the plurality of antenna elements are disposed in a planar array.

20. A method of forming an antenna element, comprising:

patterning a conductive layer on a first side of a substrate, wherein a plurality of dipole arms are formed;

providing a ground plane on a second side of the substrate;

forming voids that extend from the first side of the substrate and towards the second side of the substrate, wherein each void is adjacent a portion of a dipole arm included in the plurality of dipole arms; and

placing a conductive material in the voids, wherein the conductive material in each of the voids is in electrical contact with a corresponding portion of the dipole arms, and wherein the conductive material in each of the voids is not in electrical contact with the ground plane.