Spiral resonator-slot antenna

• US 20030222825A1
• Filed: 06/03/2003
• Published: 12/04/2003
• Est. Priority Date: 06/03/2002
• Status: Active Grant

• Current Assignee: Johns Hopkins University
• Original Assignee: Johns Hopkins University
• Inventors: Soranno, Robert T., Sparks, Kenneth D.
• Granted Patent: US 6,897,822 B2
• Time in Patent Office: Days
• US Class Current: 343/767
• CPC Class Codes: H01Q 13/10 Resonant slot antennas
• CPC Class Codes: H01Q 13/12 Longitudinally slotted cylinder antennas; Equivalent structures
• CPC Class Codes: H01Q 13/16 Folded slot antennas

Abstract

A resonator-slot antenna is configured to have a spiral of a conducive sheet material having at least one turn and extending along an axis with an elongated antenna slot helically wound around the axis in at least one full twist.

Claims

1. A resonator-slot antenna comprising a spiral of a conductive sheet material having at least one turn and extending along an axis with an elongated antenna slot helically wound around the axis in at least one full twist

2. The resonator-slot antenna of claim 1, wherein at least one full twist is at least of about 360°

.

3. The resonator-slot antenna of claim 1, wherein the conductive sheet material is selected from the group consisting of foil, copper mesh, gold, silver, monel, aluminum and mixtures thereof.

4. The resonator-slot antenna of claim 1, wherein the conductive sheet material has initially a polygonal shape defined between two spaced-apart axial edges juxtaposed with one another to define a helical seam of a body of the resonator-slot antenna formed after the sheet material has been rolled and twisted.

5. The resonator-slot antenna of claim 4, further comprising a sliver of a dielectric material coupled to either of the axial edges and configured to be substantially smaller than the conductive sheet material to be sandwiched by the conductive sheet material along the seam of the body.

6. The resonator-slot antenna of claim 5, wherein the sliver of the dielectric material has a portion overhanging one of the axial edges, so that when the body is formed, the axial edges overlap opposite faces of the sliver of dielectric material and coupled thereto.

7. The resonator slot antenna of claim 5, wherein the body is hollow or provided with a low dielectric core comprising a buoyant material and the dielectric material of the sliver having a dielectric constant of about 10 and being moisture immune.

8. The resonator slot antenna of claim 5, wherein the buoyant material is selected from the group consisting of fiberglass, polyvinyl chloride, polyurethane and a combination thereof.

9. The resonator-slot antenna of claim 5, further comprising a coaxial feeder having one of opposite ends thereof for coupling to a signal source/receiver, the opposite end of the coaxial feeder being coupled to the sheet of conductive material at a tuned point and extending along about 20% of a total length of the sliver.

10. The resonator-slot antenna of claim 9, wherein the tuned point includes a hole in the sheet of conductive material traversed by the opposite end of the coaxial feeder from an interior of the body out or from outside into the interior.

11. The resonator-slot antenna of claim 9, wherein the sheet of conducting material constitutes a ground plane of the resonator-slot antenna and configured to provide the resonator-slot antenna with a self-supporting structure.

12. The resonator-slot antenna of claim 11, further comprising a shell provided with a cylindrical body having an inner surface, which is radially juxtaposed with the body of the resonator-slot antenna and made from moisture immune material.

13. A resonator-slot antenna-assembly for towing by a submarine or a surface vessel, comprising:

an annular body made from conducive material and having two edges spaced laterally from a longitudinal axis of the annular body in opposite directions;

a sliver of dielectric material sandwiched between the two edges to form an axial antenna slot helically wound around the annular body in at least one full twist of about 360°

to form a resonator-slot antenna; and

a floating shell housing the resonator-slot antenna and being displaceably fixed therewith, wherein the resonator-slot antenna is immune to a roll of the resonator-slot antenna in sea water.

14. The resonator-slot antenna assembly of claim 13, wherein the sliver has a portion projecting laterally beyond one of the edges.

15. The resonator-slot antenna of claim 14, further comprising a coaxial feeder having one of opposite ends thereof coupled to the sheet material at a tuned point, the resonator-slot antenna being configured to have an outer diameter, a length and thickness of the sliver, a location of the tuned point and a number of revolutions of the sliver a function of desired frequency.

16. The resonator-slot antenna assembly of claim 15, wherein the outer diameter resonator-slot antenna is dictated by operating frequency and dielectric sliver material, the tuned point being located at a distance from a leading end of the sliver corresponding to about 20% of the length of the sliver.

17. A method for fabricating a resonator-slot antenna comprising the steps of:

providing a longitudinal sliver of dielectric material;

fusing the longitudinal sliver to one of opposite surfaces of a sheet of conductive material covering the sliver;

forming an annular body by rolling and twisting the sheet of conductive material to form a helical longitudinal slot of the resonator-slot antenna defined by the longitudinal sliver sandwiched between juxtaposed portions of the sheet; and

coupling the sliver to the other surface of the sheet of conductive material.

18. The method of claim 17, wherein the annular body is twisted to form at least one about 360°

helical twist of the sliver of dielectric material.

19. The method of claim 17, wherein the coupling of the sheet of conductive material to the sliver includes:

(a) selectively soldering one of opposite surfaces of the sheet along a respective longitudinal edge thereof to one face of the sliver, thereby forming a first plurality of spaced apart soldered regions, each pair of which defines a respective space;

(b) cooling the soldered sliver and the sheet; and

(c) soldering the spaces between the initially soldered regions; and

(d) soldering the opposite surface of the sheet to a face of the sliver opposite to the one face by repeating steps (a) through (c) upon rolling another longitudinal edge of the sheet to form the annular body with a continuous helical slot defined by the sliver and equal to about 360 degrees.

20. The method of claim 19, further comprising attaching a coaxial feeder to the annular body at a tuned point located between leading and trailing ends of the annular body.

21. The method of claim 20, wherein the tuned point is spaced from the leading end of the annular body by a distance equal to about 20% of an entire length of the sliver.