Antenna with curved dipole elements

• US 5,173,715 A
• Filed: 06/12/1991
• Issued: 12/22/1992
• Est. Priority Date: 12/04/1989
• Status: Expired due to Fees

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Janky, James M., Gildea, David R., Rodal, Eric B., Detro, Michael C.
• Primary Examiner(s): WIMER, MICHAEL C
• Application Number:
  US07/714,192
• Time in Patent Office: 559 Days
• Field of Search: 343/795, 343/797, 343/793, 343/802, 343/806, 343/808, 343/817, 343/818, 343/829, 343/833, 343/846, 343/830
• US Class Current: 343/795
• CPC Class Codes: H01Q 21/205 providing an omnidirectional coverage turnstile aerials H01Q21/26
• CPC Class Codes: H01Q 21/26 Turnstile or like antennas comprising arrangements of three or more elongated elements disposed radially and symmetrically in a horizontal plane about a common centre

Abstract

An antenna comprises a base plate forming a ground plane, a coaxial feed serving as a mast connected to the base plate and extending along an axis that is normal to the ground plane, and two orthogonal dipoles each formed of two elements. Each dipole element has a first end connected to and supported by the mast at a first location spaced apart from the ground plane by a predetermined distance and a second end closer to the ground plane and exhibits a curvature in a plane containing the mast.

Claims

1. An antenna comprising:

a base plate member defining a ground plane element;

mast means for conducting electrical feed current, said mast means being attached to the base plate member and extending along an axis that is normal to the ground plane element;

means for conducting electrical feed current to said mast means;

a first pair of antenna elements defining a dipole, each of said antenna elements being a single substantially flat conductive strip formed on one surface only of a first thin flexible portion of dielectric material thereby to define a conductive printed circuit on said one surface of said first portion of dielectric material and being conductively coupled to the mast means at a first end, each of said first ends and said first thin flexible portion of dielectric material being supported by the mast means at a first location space apart from the ground plane element by a predetermined distance, and each of said antenna elements having a second end substantially closer to the ground plane element than to said first end, no portion of said ground plane element being closer to said first location than said predetermined distance;

each of the printed circuit antenna elements together with said first thin flexible portion of dielectric material exhibiting a smooth and continuous first curvature throughout its length in a plane containing the mast means;

a first pair of conductive tabs each electrically connected to said ground plane element, one of said first pair of conductive tabs being connected to said first thin flexible portion of dielectric material in closely spaced-apart relation to said second end of one of said first pair of antenna elements and the other of said first pair of conductive tabs being connected to said first thin flexible portion of dielectric material in closely spaced apart relation to said second end of the other of said first pair of antenna elements;

a second pair of antenna elements defining a dipole, each of said second pair of antenna elements being a single substantially flat conductive strip formed on one surface only of a second thin flexible portion of dielectric material thereby to define a conductive printed circuit on said one surface of said second portion of dielectric material and being conductively coupled to the mast means at a first end, said first end of each of said second pair of antenna elements and said second thin flexible portion of dielectric material being supported by the mast means adjacent to the first location, each of said antenna elements of said second pair having a second end substantially closer to the ground plane element than to said first end;

each of the printed circuit antenna elements of the second pair together with said second thin flexible portion of dielectric material exhibiting a smooth and continuous second curvature in a plane that contains the mast means; and

a second pair of conductive tabs each electrically connected to said ground plane element, one of said second pair of conductive tabs being connected to said second thin flexible portion of dielectric material in closely spaced-apart relation to said second end of one of said second pair of antenna elements and the other of said second pair of conductive tabs being connected to said second thin flexible portion of dielectric material in closely spaced-apart relation to said second end of the other of said second pair of antenna elements.

2. The antenna according to claim 1, wherein said curvature of said first and second pairs of antenna elements is convex.

3. The antenna according to claim 1, wherein said curvature of said first and second pairs of antenna elements is concave.

4. The antenna according to claim 1, further comprising a pair of elongate parasitic antenna elements each of said parasitic antenna elements respectively cooperating with a corresponding one of said first pair of antenna elements and each exhibiting a curvature in a plane containing the mast means and said corresponding one of said first pair of antenna elements.

5. The antenna according to claim 4, wherein each of said parasitic antenna elements is respectively generally parallel to said corresponding one of said first pair of antenna elements.

6. The antenna according to claim 1, wherein each of said first pair of conductive tabs is formed with a first projection and said ground plane element is formed with a first projection and said ground plane element is formed with a first pair of holes respectively positioned to receive said first projections so that when said first projections are respectively inserted through said first pair of holes and said mast means is properly positioned, said first thin portion of dielectric material and therefore said first pair of antenna elements are automatically given said first curvature.

7. The antenna according to claim 1, wherein the curvature of said first pair of antenna elements is given by ##EQU4## wherein x is the distance from the origin along the X axis, z is distance from the origin along the Z axis, a and b are arbitrary constants, and n is a parameter such that

8. The antenna according to claim 7, wherein the curvature of said second pair of antenna elements is given by ##EQU5## wherein y is distance from the origin along the Y axis.

9. The antenna of claim 1, wherein each of said second pair of conductive tabs is formed with a second projection and said ground plane element is formed with a second pair of holes respectively positioned to receive said second projections so that, when said second projections are respectively inserted through said second pair of holes and said mast means is properly positioned, said second thin portion of dielectric material and therefore said second pair of antenna elements are automatically given said second curvature.

10. The antenna of claim 1, in which in a planar projection of said antenna elements each element of each pair of each such first and second pairs of printed circuit antenna elements is in substantially orthogonal relationship to an element of the other pair of antenna elements.

11. The antenna of claim 1, in which said mast means comprises a center conductor and one element of each pair of antenna elements is electrically connected to said center conductor.

12. The antenna of claim 1, in which said mast means comprises an outer conductor and one element of each pair of printed circuit antenna elements is electrically connected to said outer conductor.

13. The antenna of claim 12, in which one element of each pair of antenna elements is formed on said one surface of said first thin flexible portion of dielectric material and the other element of each pair of antenna elements is formed on a surface of said second thin flexible portion of dielectric material that is opposite said one surface.

14. The antenna of claim 13, in which the elements of each pair of said first and second pairs of antenna elements are out of electrical contact with each other.

15. The antenna of claim 1, in which said first and second thin flexible portions of dielectric material are formed as a single dielectric board in the shape of a cross.

16. The antenna of claim 1, in which said mast means comprises an inner conductor and one element of each pair of printed circuit antenna elements is electrically connected to said inner conductor.