End loaded helix antenna

• US 5,329,287 A
• Filed: 06/04/1992
• Issued: 07/12/1994
• Est. Priority Date: 02/24/1992
• Status: Expired due to Term

• Current Assignee: EMS Technologies Canada Ltd. (Honeywell International Inc.)
• Original Assignee: EMS Technologies Canada Ltd. (Honeywell International Inc.)
• Inventors: Strickland, Peter C.
• Primary Examiner(s): Wimer, Michael C.
• Application Number:
  US07/893,525
• Time in Patent Office: 768 Days
• Field of Search: 343/895, 343/752, 343/749, 343/899
• US Class Current: 343/752
• CPC Class Codes: H01Q 11/08 Helical antennas

Abstract

A device is provided for use in a helical antenna having an antenna element wound about the periphery of a dielectric support post, the post being in the form of a tube or cylinder. The device has an electrically conductive member electrically connected to one end of said antenna element. The conductive member is of any appropriate shape or configuration and is operable to increase the loading on the antenna whereby standing waves on the antenna element are reduced and a more uniform electrical current is produced along the antenna element.

Claims

1. In a helical antenna of the type having a ground plane;

a hollow dielectric support tube with an end fixed to said ground plane and a free end, said support tube extending normal to said ground plane; and

an antenna element with a feed end, a number of windings about the periphery of said support tube, and a free end arranged at said free end of said support tube, said antenna being for operation in the axial mode, the improvement comprising;

an electrically conductive member for placement over said free end of said support tube, said member being electrically connected to said free end of said antenna element; and

said conductive member being a concavely shaped disc, with a central portion of said disc projecting into said dielectric support tube.

2. In a helical antenna of the type having a ground plane;

a hollow dielectric support tube with an end fixed to said ground plane and a free end, said support tube extending normal to said ground plane; and

an antenna element with a feed end, a number of windings about the periphery of said support tube, and a free end arranged at said free end of said support tube, said antenna being for operation in the axial mode, the improvement comprising;

an electrically conductive member for placement over said free end of said support tube, said member being electrically connected to said free end of said antenna element; and

said conductive member being cone shaped with the apex of said cone projecting away from said ground plane.

3. In a helical antenna of the type having a ground plane;

a hollow dielectric support tube with an end fixed to said ground plane and a free end, said support tube extending normal to said ground plane; and

an antenna element with a feed end, a number of windings about the periphery of said support tube, and a free end arranged at said free end of said support tube, said antenna being for operation in the axial mode, the improvement comprising;

an electrically conductive member for placement over said free end of said support tube, said member being electrically connected to said free end of said antenna element; and

including a conductive post electrically connected to said ground plane and extending substantially normal to said ground plane and within said hollow dielectric support tube, a free end of said conductive post being spaced from said conductive member.

4. A device as defined in claim 3, including a lumped reactive element electrically connected between said conductive member and said free end of said conductive post.

5. In a helical antenna of the type having a ground plane;

a hollow dielectric support tube with an end fixed to said ground plane and a free end, said support tube extending normal to said ground plane; and

an antenna element with a feed end, a number of windings about the periphery of said support tube, and a free end arranged at said free end of said support tube, said antenna being for operation in the axial mode, the improvement comprising;

an electrically conductive member for placement over said free end of said support tube, said member being electrically connected to said free end of said antenna element for increasing the loading on the antenna so that in use a current flows between said free end of the antenna element and said ground plane due to the capacitive coupling between said conductive member and said ground plane;

said conductive member being a concavely shaped disc, with a central portion of said disc projecting into said dielectric support tube.

6. In a helical antenna of the type having a ground plane;

a hollow dielectric support tube with an end fixed to said ground plane and a free end, said support tube extending normal to said ground plane; and

an antenna element with a feed end, a number of windings about the periphery of said support tube, and a free end arranged at said free end of said support tube, said antenna for operation in the axial mode, the improvement comprising;

an electrically conductive member for placement over said free end of said support tube, said member being electrically connected to said free end of said antenna element for increasing the loading on the antenna so that in use a current flow is produced between said free end of the antenna element and said ground plane due to the capacitive coupling between said conductive member and said ground plane;

said conductive member being cone shaped with the apex of said cone projecting away from said ground plane.

7. In a helical antenna of the type having a ground plane;

a hollow dielectric support tube with an end fixed to said ground plane and a free end, said support tube being perpendicular on said ground plane; and

an antenna element with a feed end, a number of windings about the periphery of said support tube, and a free end arranged at said free end of said support tube, said antenna for operation in the axial mode, the improvement comprising;

an electrically conductive member for placement over said free end of said support tube, said member being electrically connected to said free end of said antenna element for increasing the loading on the antenna so that in use a current flow is produced between said free end of the antenna element and said ground plane due to the capacitive coupling between said conductive member and said ground plane; and

including a conductive post electrically connected to said ground plane and extending substantially normal to said ground plane and within said hollow dielectric support tube, a free end of said conductive post being spaced from said conductive member.

8. A device as defined in claim 7, including a lumped reactive element electrically connected between said conductive member and said free end of said conductive post.

9. In a helical antenna having an antenna element wound about the periphery of a hollow dielectric support tube extending from a ground plane in a direction generally normal to the ground plane, the improvement comprising:

an electrically conductive circular disc member electrically connected to one end of said antenna element, said one end of said antenna element being an end opposite a feed point end of said antenna element;

a conductive post electrically connected to said ground plane and extending substantially normal to said ground plane and within said hollow dielectric support tube, a free end of said conductive post being spaced from said conductive member;

said disc member being for increasing the loading on the antenna so that in use a current flows through the antenna element due to the capacitive coupling between said disc member and said ground plane, thereby reducing standing waves on said antenna element.

10. In a helical antenna of the type having a ground plane;

a hollow dielectric support tube with an end fixed to said ground plane and a free end, said support tube extending normal to said ground plane; and

an antenna element wound about the periphery of said support tube, said antenna being for operation in the axial mode, the improvement comprising;

an electrically conductive member for placement over said free end of said support tube, said member being electrically connected to one end of said antenna element, said one end of said antenna element being remote from a feed point of said antenna element; and

said conductive member being a concavely shaped disc, with a central portion of said disc projecting into said dielectric support tube.

11. In a helical antenna of the type having a ground plane;

a hollow dielectric support tube with an end fixed to said ground plane and a free end, said support tube extending normal to said ground plane; and

an antenna element wound about the periphery of said support tube, said antenna being for operation in the axial mode, the improvement comprising;

an electrically conductive member for placement over said free end of said support tube, said member being electrically connected to one end of said antenna element, said one end of said antenna element being remote from a feed point of said antenna element; and

said conductive member being cone shaped with the apex of said cone projecting away from said ground plane.

12. In a helical antenna of the type having a ground plane;

a hollow dielectric support tube with an end fixed to said ground plane and a free end, said support tube extending normal to said ground plane; and

an antenna element wound about the periphery of said support tube, said antenna being for operation in the axial mode, the improvement comprising;

an electrically conductive member for placement over said free end of said support tube, said member being electrically connected to one end of said antenna element, said one end of said antenna element being remote from a feed point of said antenna element; and

including a conductive post electrically connected to said ground plane and extending substantially normal to said ground plane and within said hollow dielectric support tube, a free end of said conductive post being electrically isolated from said conductive member.