Four wire dual mode spiral antenna

• US 4,498,084 A
• Filed: 12/30/1982
• Issued: 02/05/1985
• Est. Priority Date: 12/30/1982
• Status: Expired due to Term

• Current Assignee: CommScope Technologies AG (CommScope Holding Company, Inc.)
• Original Assignee: Granger Associates (Nokia Corporation)
• Inventors: Werner, William L., DuHamel, Raymond H.
• Primary Examiner(s): NOT, DEFINED
• Application Number:
  US06/454,693
• Time in Patent Office: 768 Days
• Field of Search: 343/792.5, 343/886, 343/890, 343/891, 343/895, 343/908
• US Class Current: 343/792.5
• CPC Class Codes: H01Q 1/14 for wire or other non-rigid radiating elements
• CPC Class Codes: H01Q 3/24 varying the orientation by switching energy from one active radiating element to another, e.g. for beam switching
• CPC Class Codes: H01Q 9/27 Spiral antennas

Abstract

A dual mode broadband antenna especially designed to provide an omni-directional low angle or high angle radiation pattern which is predominately horizontally polarized is disclosed herein. This antenna utilizes four wire radiators in the form of an inverted conical log-spiral supported in a vertically extending fashion a predetermined distance above the horizontal ground plane. In order to alternatively operate the antenna in its high and low angle modes, first and second oppositely phased AC currents are applied to the radiators in two different ways using a simple switching device rather than a more complicated network of four hybrid circuits.

Claims

1. An antenna, comprising:

first, second, third and fourth wire radiators;

means for supporting said radiators in electrically insulated relationship to one another above a horizontal ground plane and around the outer surface of an imaginary inverted cone having its apex located a fixed distance above said plane and its central axis extending vertically upward therefrom, said first, second, third and fourth radiators being supported so as to define successively interlaced first, second, third and fourth conical spiral windings, respectively, beginning at the lowermost ends of the radiators adjacent the apex of said cone, said lowermost ends being circumferentially spaced 90°

from each other about said central axis;

means for providing first and second alternating currents having the same amplitude and a given frequency but 180°

out of phase with one another; and

means for simultaneously electrically connecting said first current to the lowermost ends of said first and second radiators and said second current to the lowermost ends of said third and fourth radiators, whereby to cause said radiators to produce a high angle radiation pattern relative to said horizontal ground plane.

2. An antenna according to claim 1 wherein said connecting means includes switch means movable between a first operating mode for simultaneously connecting said first current to the lowermost ends of said first and second radiators and said second current to the lowermost ends of said third and fourth radiators to provide said high angle radiation pattern and a second operating mode for simultaneously connecting said first current to the lowermost ends of said first and third radiators and said second current to the lowermost ends of said second and fourth radiators whereby to cause said radiators to produce a low angle radiator pattern relative to said horizontal plane.

3. An antenna according to claim 2 wherein said apex of said imaginary cone defines a preselected cone angle with its central axis and wherein said spiral windings define a preselected pitch angle with said axis, said cone and pitch angles being selected such that said low angle radiation pattern is predominantly horizontally polarized.

4. An antenna according to claim 3 wherein said cone angle is approximately 45°

and wherein said pitch angle is approximately 80°

.

5. An antenna according to claim 2 wherein said means for supporting said radiators includes a horizontally extending circumferential rim forming the inverted base end of said cone, said rim being formed primarily from electrically conductive structural wires connected in end-to-end relationship to one another by electrical insulating means between adjacent ends of adjacent wires whereby to electrically insulate the wires from one another, said supporting means also including means for structurally connecting each of said radiators at its uppermost end to said rim and means for electrically connecting each of said radiators to a respective one of said wires such that each wire functions as a radiator extension of its radiator for reducing the low frequency cut-off of the antenna.

6. An antenna according to claim 5 wherein said four wires are of equal lengths and are connected together at adjacent ends by dielectric coupling members serving as said insulating means, wherein said means for structurally connecting each of said radiators to said rim including means connecting the uppermost end of each of said radiators to a respective one of said coupling members, and wherein said means for electrically connecting each of said radiators to a respective one of said wires includes an electrical jumper wire.

7. An antenna according to claim 2 wherein said radiators are able to provide said high angle radiation pattern within a bandwidth of 2 to 30 MHz and said low angle radiation pattern within a bandwidth of 4 to 30 MHz.

8. An antenna according to claim 2 wherein said spiral windings define conical logarithmic spirals.

9. An antenna according to claim 2 wherein said inverted cone has a cross-sectional configuration normal to its central axis in the shape of a hexagon.

10. An antenna according to claim 2 wherein said supporting means includes a single vertical tower coextensive with the central axis of said cone and serving as the primary structural support for said radiators.

11. A broadband antenna, comprising:

first, second, third and fourth wire radiators;

means for supporting said radiators in electrically insulated relationship to one another above a horizontal ground plane and around the surface of an imaginary inverted cone having its apex located a fixed distance above said plane and its central axis extending vertically upward therefrom, said first, second, third and fourth radiators being supported so as to define successively interlaced first, second, third and fourth spiral windings, respectively, beginning at the lowermost ends of the radiators adjacent the apex of said cone, said lowermost ends being circumferentially spaced 90°

from each other about said central axis;

means for providing first and second alternating currents having the same amplitude and a given frequency but 180°

out of phase with one another; and

means for simultaneously electrically connecting said first current to the lowermost ends of said first and third radiators and said second current to the lowermost ends of said second and fourth radiators whereby to cause said radiators to produce a low angle radiation pattern relative to said horizontal ground plane, said imaginary cone defining a preselected cone angle axis and the spiral windings defining a preselected pitch angle with said central axis such that said low angle radiation pattern is predominately horizontally polarized.

12. A broadband antenna, comprising first, second, third and fourth wire radiators, means for supporting said radiator in electrically insulated relationship to one another above a horizontal ground plane and around the surface of an imaginary inverted cone having its apex located a fixed distance above said plane and its central axis extending vertically upward therefrom, said first, second, third and fourth radiators being supported so as to define successively interlaced first, second, third, and fourth spiral windings, respectively, beginning at the lowermost ends of the radiators adjacent the apex of said cone and ending at the uppermost ends of the radiators adjacent the base of the cone, said lowermost ends being circumferentially spaced 90°

from each other about the central axis of the cone at its apex, and said uppermost ends also being circumferentially spaced 90°

from each other about the central axis of said cone about its base;

means for providing first and second alternating currents having the same amplitude and a given frequency but 180°

out of phase with one another; and

means for simultaneously electrically connecting said first and second currents to preselected ones of said radiators in order to cause the latter to produce a given radiation pattern relative to said horizontal ground plane at the frequency within a given bandwidth;

said means for supporting said radiators including a horizontally oriented circumferential rim at the base end of said cone for aiding in supporting said radiators, said rim including means for extending the radiating length of each of said radiators sufficient to reduce the low frequency cut-off of the antenna without increasing the maximum horizontal extent of said cone beyond said rim.

13. An antenna according to claim 12 wherein said rim consists essentially of four electrically conductive structural wires of equal length connected in end-to-end relationship to one another by dielectric coupling member, wherein the uppermost end of each of said radiators is positioned adjacent a corresponding one of said dielectric coupling members, wherein said means for supporting said radiators includes means for connecting the uppermost end of each radiator with its corresponding dielectric coupling member, and wherein said means for extending each radiator includes an electrical jumper cable connected between that radiator and a specific adjacent one of said wires.

14. A broadband antenna, comprising:

a first group of first, second, third and fourth wire radiators;

a second group of first, second, third and fourth wire radiators;

means for supporting the radiators in each of said groups in electrically insulated relationship to one another above a horizontal ground plane and around the surface of an imaginary inverted cone having its apex located a fixed distance above said plane and its central axis extending vertically upward therefrom, the cone including said first group of radiators and the cone including the second group of radiators being disposed in stacked relationship so as to define colinear central axes, the first, second, third and fourth radiators in each group being supported so as to define successively interlaced first, second, third and fourth spiral windings, respectively, beginning at the lowermost ends of its radiators adjacent the apex of its cone, said lowermost ends being circumferentially spaced 90°

from each other about the central axis of its cone;

means for providing first and second alternating currents having the same amplitude and a given frequency for 180°

out of phase with one another; and

means for simultaneously electrically connecting said first and second currents to the lowermost ends of the radiators in each of said groups in a predetermined way which causes the radiators to produce a given radiation pattern relative to said horizontal ground plane.

15. An antenna according to claim 14 wherein said means for supporting the radiators in each of said groups includes a common vertical support tower coextensive with the colinear axes of said cones.

16. A broadband, multi-range omni-directional antenna comprising:

first, second, third and fourth wire radiators;

means for supporting said radiators in electrically insulated relationship to one another above a horizontal ground plane and around the surface of an imaginary inverted cone having its apex located a fixed distance above said plane and its central axis extending vertically upward therefrom, said first second, third and fourth radiators being supported so as to define successively interlaced first, second, third and fourth logarithmic spiral windings, respectively, beginnning at the lowermost ends of the radiator adjacent the apex of said cone and ending at the uppermost ends of the radiators adjacent the base of said cone, said lowermost ends being circumferentially spaced 90°

from each other about said central axis at said apex and said uppermost ends being circumferentially spaced 90°

from each other about said central axis at said base, said supporting means including a horizontally oriented structural rim forming the base of said inverted cone and consisting essentially of four equal electrically conductive circumferential segments separated from one another by four dielectric coupling members and said supporting means also including a single central structural tower coextensive with the central axis of said cone and serving as the primary structural member for said radiators;

means for providing first and second alternating currents having the same amplitude and a given frequency within a bandwidth of about 2 MHz to about 30 MHz but 180°

out of phase with one another;

means including a switch movable between a first operating mode for simultaneously electrically connecting said first current to the lowermost ends of said first and second radiators and said second current to the lowermost ends of said third and fourth radiators, whereby to cause said radiators to produce a high angle radiation pattern relative to said horizontal ground plane and a second operating mode for simultaneously electrically connecting said first current to the lowermost ends of said first and third radiators and said second current to the lowermost ends of said second and fourth radiators whereby to cause said radiators to produce a low angle radiation pattern relative to said horizontal plane, the apex of said imaginary cone defining a preselected cone angle with its central axis and the spiral windings defining a preselected pitch angle with said axis such that said low angle radiation pattern is predominately horizontally polarized; and

means for electrically connecting said first, second, third and fourth radiators with said four electrically conductive wires, respectively, so as to extend the radiation capabilities of said radiators sufficient to reduce the low frequency cut-off of the antenna without increasing the size of said base.