Rotation-independent helical antenna

• US 7,286,099 B1
• Filed: 09/02/2005
• Issued: 10/23/2007
• Est. Priority Date: 09/02/2005
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Lier, Erik, Lindinger, Bernard F., Smolenski, Leon R.
• Primary Examiner(s): LE, HOANGANH T
• Application Number:
  US11/217,439
• Time in Patent Office: 781 Days
• Field of Search: 343/895, 343/715, 343/900
• US Class Current: 343/895
• CPC Class Codes: H01Q 1/362 for broadside radiating helical antennas
• CPC Class Codes: H01Q 11/08 Helical antennas
• CPC Class Codes: H01Q 11/083 Tapered helical aerials, e.g. conical spiral aerials

Abstract

A helical antenna having a central axis defined between a base end and a distal end comprises a helical conductor wound about the central axis and having a feed line disposed at the base end and along the central axis, and may also include an elongated dielectric core about which the electrical conductor is wound.

Claims

1. A helical antenna having a central axis defined between a base end and a distal end, the helical antenna comprising:

A. an elongated dielectric core formed about the central axis between the base end and the distal end; and

B. a helical coil coaxial with and wound about the core, the helical coil comprising;

1) a feed line formed at the base end and along the central axis;

2) an axially tapered end formed at the distal end, the tapered end decreasing in radius along the central axis and in the direction of the distal end; and

3) a midsection disposed between the feed line and tapered end, the midsection having a taper angle smaller than a taper angle of the tapered end relative to the central axis and in the direction of the distal end.

2. The helical antenna of claim 1 wherein the feed line is configured to couple to a transmission path comprising at least one of a coaxial cable, waveguide, strip line, or micro-strip line.

3. The helical antenna of claim 1 wherein the tapered end is formed of up to two turns of the helical coil.

4. The helical antenna of claim 1 wherein the tapered end is configured to achieve an axial ratio of about 1 dB or less.

5. The helical antenna of claim 1 wherein the core is a cruciform.

6. A method of making a helical antenna comprising the steps of:

A. winding an elongated electrical conductor about a central axis, the electrical conductor having a base end and a distal end, including;

1) forming an axially tapered end by tapering the conductor in decreasing radius along the central axis and in the direction of the distal end;

2) forming a feed line at the base end along the central axis; and

3) forming a midsection disposed between the feed line and the tapered end, the midsection having a taper angle smaller than a taper angle of the tapered end relative to the central axis and in the direction of the distal end.

7. The method of claim 6 wherein step A includes the step of winding the conductor around an elongated dielectric core formed about the central axis.

8. The method of claim 6 wherein the core is a cruciform.

9. The method of claim 6 wherein step A. 1) includes the step of forming the tapered end with up to two turns of the conductor.

10. The method of claim 6 wherein step A. 1) includes the step of forming the tapered to achieve an axial ration of about 1 dB or less.

11. The method of claim 6 wherein step A. 2) includes the step of forming the feed line to couple to a transmission path comprising at least one of a coaxial cable, waveguide, strip line, or micro-strip line.

12. A method of adjusting a phase of a helical antenna, the helical antenna comprising an elongated helical coil having a central axis disposed between a base end and a distal end and a feed line disposed at the base end, the method comprising the steps of:

A. rotatably mounting the base end of the helical antenna to a substrate such that the helical antenna is substantially oriented for at least one of radiation or reception in the direction of the central axis;

B. disposing the feed line along the central axis and providing a transmission path comprising a coupling junction disposed at the central axis;

C. coupling the feed line to the coupling junction; and

D. rotating the helical antenna about the central axis until a desired phase is achieved, without decoupling the feed line from the coupling junction.

13. The method of claim 12, wherein the transmission path comprises at least one of a coaxial cable, waveguide, strip line, or micro-strip line.

14. The method of claim 12 wherein helical antenna includes an axially tapered end formed at the distal end and decreasing in radius along the central axis and in the direction of the distal end.

15. A helical antenna having a central axis defined between a base end and a distal end, the helical antenna comprising:

A. a helical coil coaxial with and wound about the central axis, the helical coil comprising;

1) a feed line formed at the base end and along the central axis;

2) an axially tapered end formed at the distal end, the tapered end decreasing in radius along the central axis and in the direction of the distal end; and

3) a midsection disposed between the feed line and tapered end, the midsection having a taper angle smaller than a taper angle of the tapered end relative to the central axis and in the direction of the distal end.

16. The helical antenna of claim 15 wherein the feed line is configured to couple to a transmission path comprising at least one of a coaxial cable, waveguide, strip line, or micro-strip line.

17. The helical antenna of claim 15 wherein the tapered end is formed of up to two turns of the helical coil.

18. The helical antenna of claim 15 wherein the tapered end is configured to achieve an axial ratio of about 1 dB or less.