TECHNICAL ART The instant invention generally relates to methods of manufacturing a helical or contrawound helical antenna on a linear, toroidal, or generalized toroidal form, and more particularly a method of manufacturing a contrawound toroidal helical antenna.

BACKGROUND OF THE INVENTION U. S. Patent 5,734,353, the'353 Patent, incorporated herein by reference, teaches an electrically small contrawound toroidal helical antenna comprising a single conductor with two length portions overlapping in contrawound relationship to one another. Such an antenna can be difficult and time consuming to construct. The'353 Patent also teaches a generalized torus, a generalized helix, and a generalized contrawound toroidal helix.

The prior art teaches various methods of making a toroidal helical winding in the manufacture of toroidal inductors. U. S. Patents 4,379,527,4,872,618,5,274,907 and 5,331,729 teach methods of forming toroidal helical inductors from wire with various forms of toroidal core winding machines. U. S. Patent 3,740,837 teaches a method of forming a toroidal helical inductor by either cutting the helix out of a thin single layer conductive tube shaped as a helix, or by coating a torus of nonconductive material with a conductive material, such as by electro-deposition, and then cutting the thin conductive layer along a helical line, such as by etching.

The contrawound toroidal helical antennas utilize a relatively large helical pitch angle as compared with a toroidal helical inductor, and the separate contrawound length portions of the single conductive path preferably interleave one another, which complicates the manufacturing process.

SUMMARY OF THE INVENTION One method of constructing a contrawound toroidal helical antenna is to divide a single conductive element into two length portions, secure the mid point thereof at a point of reference on a generalized toroidal form, wrap the first length portion according to a first helical pitch sense around an over the surface of the generalized torus returning to the point of reference with the end point of the first length portion, then repeat the same procedure for the second length portion but in an opposite circumferential direction and with an opposite helical pitch sense, and finally join the ends of the first and second length portions to one another proximate the point of reference. The contrawound toroidal helical antenna may also be wound on a generalized toroidal form using two separate conductors which may be wound either simultaneously or separately.

Accordingly, one object of the instant invention is to provide a method of manufacturing a contrawound helical winding that can be automated.

A further object of the instant invention is to provide a method of manufacturing a contrawound toroidal helical antenna.

A yet further object of the instant invention is to provide an improved method of manufacturing a generalized helical winding.

A yet further object of the instant invention is to provide an improved method of manufacturing a generalized toroidal helical winding.

The instant invention also provides various methods for forming a contrawound toroidal helix without requiring an underlying solid form. In general, the windings are first formed in a plane, which is then deformed to created the generalized contrawound toroidal helix. While these techniques are described for producing a contrawound toroidal helix, one of ordinary skill in the art will recognize that the same techniques can be used to produce either monofilar, multifilar, or contrawound generalized helical windings along any shaped path including linear or circular (toroidal).

In one of these methods, a contrawound toroidal helical antenna is constructed by winding either a pair of conductors or the two length portions of a single conductor, over the periphery of a plurality of planar mandrels, and then bending the resulting planer

assembly in alternate angular directions at successive junctions between the planar mandrels.

In another of these methods, the planar mandrels are interconnected with hinges.

In yet another of these methods, the planer mandrels are coupled to a central mechanism which controls both the locations of the form centers and the relative angular deformations.

In yet another of these methods, wires simultaneously fed from two separate spools are wound over radial pins attached to a central hub which is rotated as the winding develops.

The points where the separate wires cross one another are then successively clasped radially inwards, and pushed radially outwards, so as to form a contrawound toroidal helix.

After cutting and terminating the wires, the resulting contrawound toroidal helix is released by retracting or extracting the radial pins, which operation may be performed after first encapsulating the winding to preserve dimensional stability.

In yet another of these methods, wires simultaneously drawn from two separate spools are grasped by a plurality of pairs of opposed hook elements, which are then retracted so as to displace the wire in a direction normal to the nominal direction of wire feed so as to form successive cells bounded by the two wires. The hook elements are then twisted and translated so as to form a generalized contrawound toroidal helix.

These and other objects, features, and advantages of the instant invention will be more fully understood after reading the following detailed description of the preferred embodiment with reference to the accompanying drawings and viewed in accordance with the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a method of winding a contrawound toroidal helical antenna using a single conductor divided into two length portions.

FIG. 2 illustrates a method of winding a contrawound toroidal helical antenna using two separate conductors.

FIG. 3 illustrates a method of winding a contrawound toroidal helical antenna using a plurality of planar mandrels.

FIG. 4 illustrates a method of winding a contrawound toroidal helical antenna using a plurality of planar mandrels which are hinged to one another.

FIG. 5 illustrates a method of winding a contrawound toroidal helical antenna using a plurality of planar mandrels which are connected to a central locating mechanism.

FIG. 6 illustrates a method of winding a contrawound toroidal helical antenna using pins to establish the contour of the winding.

FIG. 7 illustrates a method of winding a contrawound toroidal helical antenna using hooks to establish the contour of the winding.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT (S) Referring to FIG. 1, a conductor 5 is divided into first 11 and second 12 length portions by midpoint 10. The midpoint 10 is placed at a point of reference on the surface of over a generalized toroidal form 20, and the first length portion 11 is then wound in a first circumferential direction 13 as a generalized toroidal helix around and over a generalized toroidal form 20 with a first helical pitch sense. Then the second length portion 12 is wound in a second circumferential direction 14, opposite to the a first circumferential direction 13, as a generalized toroidal helix around and over a generalized toroidal form 20 with a second helical pitch sense opposite the first helical pitch sense, wherein the first and second length portions may be interleaved with one another. The ends of the first 11 and second 12 length portions are then secured to one another proximate the point of reference.

Referring to FIG. 2, first 30 and second 40 conductors are wound in contrawound helical relationship to one another around and over the surface of a generalized torus 20.

The first 30 and second 40 conductors may be wound either simultaneously or sequentially.

After winding, the ends are terminated as with the FIG. 1 embodiment.

Referring to FIG. 3, first 30 and second 40 conductors are wound over successively opposite peripheral sections of a plurality of planar mandrels 50, whereby on a given

planar mandrel 50, the peripheral sections thereof which contact the first 30 and second 40 conductors respectively are opposite one another. Fig. 3a illustrates the planar mandrels 50 prior to the formation of the winding. Fig 3b illustrates the initial stage of the winding process. Fig. 3c illustrates the process of tightening the winding around the planar mandrels 50, which draws the planar mandrels 50 together. Fig. 3d illustrates the process of bending the planar mandrels 50 relative to one another in successively opposite directions to form a contrawound helical winding.

In general, the contrawound helical winding is formed by forming first 30 and second 40 conductors in respective first and second cyclic patterns of opposite spatial phase relative to one another and which cross one another at a plurality of nodes 25. The nodes 25 are located along the axis of the contrawound helical winding and alternate nodes are displaced in alternate directions.

A contrawound toroidal helical antenna is formed from a contrawound helical winding by starting the contrawound helical winding at the first ends of the first 30 and second 40 conductors, ending the contrawound helical winding at the second ends of the first 30 and second 40 conductors, connecting the first end of the first conductor 30 to the second end of the second conductor 40, and connecting the first end of the second conductor 40 to the second end of the first conductor 30, so as to form an endless conductive path.

Referring to FIG. 4, planar mandrels 60 are hinged together with hinges 70 comprising hinge elements 71 and 72, and a hinge pin 73. The hinges are located on opposite faces of the planar mandrels 60 so that the planar mandrels 60 can freely hinge in alternating directions, whereby the hinges naturally act to retain the windings after the mandrels 60 are swung about the hinges relative to one another. The first 30 and second 40 conductors are wound around the planar hinge elements as for the FIGs. 3 and 4 embodiments, and the hinges 70 may alternatively be connected with their respective hinge pins 73 during or after the winding process.

Referring to FIGs. 5a and 5b, each of a plurality of planar mandrels 80 is interconnected to a respective spoke 100 with a respective hinge 90. The spokes are interconnected to a central pivot 120, whereat the spokes may be slotted to provide for radial travel. If slotted, control elements 130, which may cooperate with a cam or other

positioning mechanism, set the relative radial distances of the planar mandrels from the central pivot 120. Additional control linkage 140 is provided to rotate the planar mandrels to create a contrawound toroidal helix after forming the conductive winding around the planar mandrels 80. Fig. 5a illustrates the planar mandrels 80 positioned for receiving first and second conductors, whereas Fig. 5b illustrates the planar mandrels 80 positioned by the control linkage 140 so as to form a contrawound helical winding. In one embodiment, the resulting contrawound helical winding incorporates the planar mandrels 80, which are then detached from the winding mechansim. In another embodiment, the planar mandrels 80 are split into first 80.1 and second 80.2 portions, which when connected to one another locate the first and second conductors thereon, and which when separated from one another, enable the resulting contawound helical winding to be removed from the winding mechanism.

Referring to FIG. 6, a central hub 200 supports a plurality of first 210 and second 220 pins in pairs. First 30 and second 40 conductive wires from spools 281 and 282 respectively pass over control wheels 271 and 272 respectively. The ends of the first 30 and second 40 conductive wires initially and temporarily are secured to the end of push-rod 260. As spool 200 is rotated in direction 205, control wheel 271 is positioned to cause the first conductive wire 30 to alternately pass over the top of the first pin 210 and then the bottom of the second pin 220, whereas control wheel 272 is positioned to cause the second conductive wire 40 to alternately pass over the bottom of the second pin 220 and then the top of the first pin 210 for the same pair of pins. After the wires are directed around the first pair of pins, clasp 250 is deployed from hub 200 to grasp both first 30 and second 40 conductive wires at their cross over point and move that point radially inwards towards the center of hub 200. After the conductive wires are passed over the next pair of pins 210 and 220, the next push-rod 260 in sequence pushes the associated conductive wire cross-over point radially outwards. The above process repeats until the central hub 200 has rotated one full revolution, after which the first 30 and second 40 conductive wires are severed from their respective feeds and terminated so as to form a contrawound toroidal helical antenna. If the conductive wire is sufficiently stiff, the first 210 and second 220 pins, push-rods 260 and clasps 250 may be withdrawn leaving an air-core contrawound toroidal helical antenna. Alternatively, the antenna may be encapsulated withdrawing the first 210 and second 220 pins, push-rods 260 and clasps 250.

Referring to FIG. 7, first 30 and second 40 conductive wires are drawn in from spools 281 and 282 respectively. A plurality of first 300 and second 310 hook elements are placed along the path of the wires and generally travel with the wire, so that as additional wire is drawn from the spools, new pairs of hook elements are brought into engagement with the respective wires. The hook elements 300 and 310 are adapted for controlled movement in a direction normal to the general direction in which the wires are drawn. As initially positioned about the wires, the hook elements 300 and 310 overlap one another, but are then moved in opposite directions until separated by a distance which corresponds to the height of the associated underlying generalized toroidal form. The action of successive pairs of hooks creates successive cells bounded by the two conductive wires.

Hook elements 300 and 310 are then rotated about their respective axes in like--but alternating for adjacent cells-directions so as to form a contrawound helix. The hook elements 300 and 310 may be translated to follow the minor axis of a generalized torus so as to form a generalized contrawound toroidal helix.

While specific embodiments have been described in detail in the foregoing detailed description and illustrated in the accompanying drawings, those with ordinary skill in the art will appreciate that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention, which is to be given the full breadth of the appended claims and any and all equivalents thereof.