EP0912982A1

EP0912982A1 - Electrical signal transmission lines made by a laminations process

Info

Publication number: EP0912982A1
Application number: EP98910715A
Authority: EP
Inventors: David Watson; Herbert GRÜNSTEUDL
Original assignee: WL Gore and Associates GmbH
Current assignee: WL Gore and Associates GmbH
Priority date: 1997-02-27
Filing date: 1998-02-20
Publication date: 1999-05-06
Also published as: JP2000509897A; AU6499498A; WO1998038651A1

Abstract

Process for the simultaneous manufacture of a multiplicity of individual electrical insulated wires with, in each case, an individual electrical conductor (11), which is provided with a dielectric sheath, with use being made of a strip type of dielectric material in which at least two strips (13, 15), which comprise a dielectric material with the individual conductors (11) lined up side by side between them and at a distance from one another, are initially compressed together by means of two pressure rollers (17, 19), which are arranged parallel to one another and whereby each has a number of peripheral grooves (23), to give a strip cable type of integrated system (21) and, in order to isolate the individual insulated wires in the longitudinal direction of the conductor, the dielectric material is subsequently separated at locations which are situated between the individual insulated wires (11) of the integrated system (21).

Description

Electrical Signal transmission lines made by a laminations process.

Background of the Invention

The invention pertains to electrical signal transmission cables simultaneously manufactured as a multiplicity of individual insulated electrical wires.

Microporous ePTFE (expanded polytetrafluoroethylene) is especially suitable as the strip type dielectric material for such individual insulated wires whereby, because of its microporosity, the expanded polytetrafluoroethylene has a dielectric constant which is especially suitable for high frequency cables in particular. However, other materials can also be used as the strip type dielectric material, e.g. PE (polyethylene), PFA (perfluoroalkoxy) or FEP (fluoroethylenepropylene).

Multiconductor flat cables made from ePTFE are known from FR-A-2 036 798 (Fileca) and WO-A- 92/04719 (Gore).

Individual insulated wires of the designated type are conventionally manufactured by helically winding such a dielectric material onto individual electrical conductors, such as known from US-A-5 554 236 (Singles et. al), or by applying the dielectric material by means of an extrusion process. The former of two methods is relatively expensive and are not suitable for the manufacture of very large lengths of cable per unit time. In the case of the method which involves winding a band type material, especially in the case of mechanically unstable materials, e.g. ePTFE or porous PE onto the individual conductors, one encounters the additional problem that very narrow strips have to be wound onto the individual conductors, whilst the strips have to be cut from significantly wider tapes. During cutting, both the tape and the narrower strips, which are to be cut from it, have to be held securely. The back tension, which arise in this way, lead to stretching the tapes, which are relatively unstable from a mechanical standpoint. After this, the cut tapes are wound onto spools from which they are unwound again for the process of winding onto the individual conductors. As a result, differing forces of extension and compression are exerted on the narrow and relatively soft tapes during these processes of cutting, winding up and unwinding again and this can lead to a varying degree of thickness of the material at different positions on the wire and this can lead to corresponding electrical tolerances in a cable which is assembled using such individual insulated wires. The results are different impedance tolerances and propagation time tolerances along the cable and between parallel cables, e.g. in a bus system. The same process variations can also be observed in the case of extruded, foamed thermoplastics. Should parallel or twisted pairs of cables be required , two or more adjoining conductors can be slit out together. This reduces the effect of variations in twist legth on the electrical length of each member of the group.

Using the present invention, one significantly increases the length of cable, which is capable of being manufactured in a period of time, together with a simultaneous reduction in the tolerance variations in signal propagation time, in impedance and in capacitance along the cable and between parallel cables or between the individual components of a multicore cable.

For this purpose, the invention makes use of a process for manufacturing multi-conductor wiring strips as taught by US-A-3 082 292 (Gore). The multi-conductor are then slit out into individual insulated wires or groups of wires.

The invention comprises the feature that individual insulated wires for electrical cables are no longer manufactured individually as known in the art but, rather, a multiplicity of insulated wires are manufactured communally in a strip cable type of integrated system and this integrated system is then cut into individual insulated wires.

For this purpose, and in accordance with the invention, a multiplicity of individual conductors together with at least two strips of dielectric material, between which the individual conductors are located, are passed through two pressure rollers which are provided with peripheral grooves at the positions of the individual conductors. In this connection, the peripheral grooves and the separation of the two pressure rollers are designed to have dimensions such that the strips of dielectric material are pressed together at positions which are located between the individual conductors. Depending on the dielectric material which is being used, compressive adhesion-type joining takes place in this way between the two dielectric strips. In the case where adequate adhesion-type joining does not take place, the strip cable type of integrated system is sintered after this compression joining process; as a result of this, the two dielectric strips undergo weld-type joining with one another. Insulated individual conductors are provided after subsequent longitudinal cutting of the integrated system at positions between the individual conductors.

The individual conductors are then used for the manufacture of cables, e.g. in the form of coaxial cables. For the manufacture of coaxial cables, an electrical shield, in the form of an external conductor, is applied to an individual insulated wire that has been prepared in accordance with the invention. An external jacket, e.g. comprising poly(vinyl chloride) (PVC), polyurethane (PU), polyethylene (PE), perfluoroalkoxy (PFA) or fluoroethylenepropylene (FEP), is applied to the shield of the coaxial cable.

As far as the shield is concerned, use can be made of a conventional shield, e.g. in the form of a braided or wound shield. In an especially preferred form of embodiment of the invention a band of insulating material is used as the shield. In particular plastic material can be used which has been made suitable as a material for electrical cable shields by incorporating therein electrically conducting particles. Use can again be made of the inventive method for applying such cable shields, namely by guiding the individual insulated wires of a multiplicity of coaxial cables, which are positioned between two strips of shield material, through pressure rollers, as a result of which a strip cable type of integrated cable system is formed which, after sintering if required, can again be subdivided into individual cables by means of longitudinal cutting.

The band cable type of integrated system is preferably sintered continuously. The sintering temperature depends on the strip material that is being used. In the case of the preferred use of ePTFE for such a strip material, a sintering temperature in the range from approximately 340°C to 430°C is recommended.

Expanded microporous PTFE (polytetrafluoroethylene), PE (polyethylene), PFA (perfluoroalkoxy) and FEP (fluoroethylenepropylene) are especially suitable as dielectric materials for the individual insulated wires. Use can also be made of dielectric materials in which air-filled micro-spheres, especially those consisting of glass, are deposited. Use can be made of the same dielectric materials for the shield material as for the dielectric sheath on the individual insulated wires if electrically conducting particles are deposited in these materials.

As a result of the feature that one leads either dielectric strips of different thicknesses or a differing number of layers of such dielectric strips through different axial regions of the pressure rollers, one can manufacture a strip cable type of integrated system in one single manufacturing process, whereby the individual insulated wires have different diameters after separating the integrated system into parts in order to produce a cable with different electrical properties.

Using the method in accordance with the invention, one can manufacture, per unit, time very long lengths of individual insulated wires or very long lengths of cable. Whereas, in the case of conventional manufacturing processes in which a strip type of dielectric material is wound helically onto the individual conductors, one achieves manufacturing lengths of 60 m/min, one can achieve 60 km/h or more with the method in accordance with the invention. This is because, on the one hand, up to 60 or even more individual conductors can be manufactured in the strip cable type of integrated system and because, on the other hand, leading the individual conductors and dielectric strips through the pressure rollers can be carried out at much higher throughput speeds than is achievable in the case of the helical winding of dielectric strips.

The method in accordance with the invention leads not only to an enormous increase in manufacturing length per unit time but it also permits much tighter manufacturing tolerances in the area of signal propagation time, impedance and capacities than are achievable in the case of the conventional method of winding a strip type of dielectric material. This is because significantly wider dielectric strips can now be processed, which are much less sensitive to retention forces, and because the manufacturing machines, which are usable for this purpose, permit significantly lower thickness tolerances than are capable of being achieved with machines for the helical winding of thin dielectric strips.

The reduction in manufacturing tolerances is manifested in a corresponding reduction in differences in the propagation time between parallel cables. One can achieve a reduction in such differences in propagation time by a factor of approximately 10. Whereas one cannot currently achive a propagation time difference of less than about 60 to 70 ns/m at the same time as a propagation velocity of 75% of light or better, cables with a propagation time difference in the range from approximately 2 to 16 ns/m can be achieved with the manufacturing method in accordance with the invention.

The same problems of wide tolerances in regard to differences in propagation time, impedance variations and capacity variations also occur, in accordance with experience, with conductors that have been extruded with foamed thermoplastics. Whilst it is possible to select cables with similar delay times and bundle these together to achive minimum differences in propagation velocity and impedance along the cables, this is a time and cost consuming process.

In regard to the manufacture, in accordance with the invention, of individual insulated wires in a band cable type of integrated system, use can be made of machines by means of which conventional band cables are produced. The process in accordance with the invention therefore has the advantage that one can make use of conventional manufacturing machines and one needs merely to add a cutting device in order to isolate the individual insulated wires from the strip cable type of integrated system. A cable manufacturer, who is already producing band cables, can therefore install the process in accordance with the invention without any larger investment.

Accordingly, the advantages, which accompany the process in accordance with the invention for the manufacture of individual insulated wires, manifest themselves when one applies strip type shield conductors using the process in accordance with the invention.

The invention will now be described in more detail on the basis of various forms of embodiments.

The following aspects are shown in the appended drawings:

Figure 1 shows a device for the manufacture of a strip cable type of integrated system;

Figure 2 shows a sintering device and a cutting device for the manufacture of individual insulated wires; Figure 3 shows an example of an individual insulated wire that has been manufactured in accordance with the invention;

Figure 4 shows a device for applying a shield to an individual insulated wire;

Figure 5 shows an example of a coaxial cable that has been manufactured with an individual insulated wire in accordance with Figure 3;

Figure 6 shows a device for manufacturing a strip cable type of integrated system and for applying a shield;

Figure 7 shows an example of a coaxial cable that has been manufactured in accordance with Figure 6;

Figure 8 shows a device for the manufacture of a strip cable type of integrated system with different dielectric strips;

Figure 9 shows the results of propagation time measurements using cables that have been manufactured in accordance with the invention;

Figures 10 shows the cable impedance along a conventionally manufactured cable; and

Figures 1 1 shows the cable impedance along a cable that has been manufactured in accordance with the invention.

In the case of the form of embodiment that is illustrated in Figure 1, a number of individual conductors 11, an upper dielectric strip 13, which is located above it, and a dielectric strip 15, that is located below it, are communally passed between two contra-rotating pressure rollers 17 and 19 and are thereby pressed together to give a band cable 21. For this purpose, each of the two pressure rollers 17, 19 is provided with a plurality of peripheral grooves 23 which are spaced at a distance from one another along the axes of the pressure rollers. In this way, each peripheral groove 23 of the upper pressure roller 17 together with one of the peripheral ribs 23 of the lower pressure roller 19 forms a passageway channel for one of the individual conductors 11. The distance between the two pressure rollers 17, 19 and the peripheral grooves 23 are designed in terms of their dimensions in such a way that a single conductor 1 1 and the two dielectric strips 13, 15 pass continuously between a pair of peripheral grooves, that are associated with one another, whereas the peripheral grooves 25, which are formed between adjacent peripheral grooves 23, have such a small separation from another that the two dielectric strips 13, 15 are firmly pressed together there.

The individual conductor 11 used were silver-plated copper conductors of AWG 30. However other conductors 11, for example made of silver or alloys, may be used. Furthermore the conductors may be coated with thermoplastic adhesives such as FEP in order to aid adhesion of the conductorr 1 1 to the dielectric strips 13,15.

In the case of the preferred form of embodiment, use is made of dielectric strips 13, 15 of microporous ePTFE. In order to improve the adhesion to the individual conductors 11 and within the band cable 21, the band cable 21 is led through a sintering device in which the band cable 21 is heated such that one achieves intimate joining in the intermediate zones of the dielectric strips 13, 15, which are pressed onto one another, between the individual conductors 11. On using dielectric strips comprising PTFE, use is made of a sintering temperature in the range from 360° to 410°C.

The microporous PTFE especially suitable for used as dielectric strips 13, 15 is that which has been produced by the process described in US-A-3 953 566 with properties described in US-A-4 187 390.

An example of an embodiment of a sintering device in the form of a sintering oven 27 is illustrated in a schematic and simplified form in Figure 2 together with a cutting device 31. The band cable 21 is also illustrated in a simplified form in this figure. In the case of this example of an embodiment, the strip cable type of integrated system 21, which was manufactured in accordance with Figure 1, is sintered continuously and led through the cutting device 31. Alternatively a salt bath as known from WO-A- 92/04719 (Gore) can be used. After the sintering process, the band cable 21 is led through the cutting device 31 by means of which the band cable 21 is separated between the individual conductors 11 in order to divide it into the individual insulated wires 43. The cutting device 31 comprises a supporting device 37 for the integrated system 21. Its upper side is provided with a recess 39 from which separating knives 41 stand up vertically in a number which corresponds to the number of individual conductors and past which the integrated system 21 is led for the cutting operation in order to provide separation into the individual insulated wires.

After this, a plurality of individual insulated wires 43, which correspond to the plurality of individual conductors 1 1 that were used, are available for further processing, e.g. to give coaxial cables.

In a schematic manner, Figure 3 shows an individual insulated wire 43, that was manufactured in accordance with the invention, with a single conductor 1 1 and two dielectric sheath components 45 and 47 which were produced during the manufacturing process of Figure 1 and in accordance with the process for providing separation from the dielectric strips 13 and 15 in accordance with Figure 2.

One can proceed in a similar manner in regard to the application of electric shields to the individual insulated wires which have previously been insulated. This process is illustrated in Figure 4. Instead of the individual conductors 11, individual insulated wires 43 in accordance with Figure 1 together with a strip 50 of shield material, which is located above it, and a strip 55 of shield material, which is located below it, are led through two pressure rollers 60, 65 which have each been provided with peripheral grooves 70 which correspond to the dimensions of the individual insulated wires 43. As a result of this, a band type coaxial cable 75 is produced which, optionally after a sintering process, is separated into individual cables by longitudinal cutting. For this purpose, one can again make use of the devices in accordance with Figure 2.

In a schematic manner, Figure 5 shows a coaxial cable 80, that was prepared in accordance with this, with an individual insulated wire 43 in accordance with Figure 3 that is surrounded by an electrical shield 85 in the form of an external conductor which, for its part, is sheathed by an external jacket 90. The coaxial cable 80 can be prepared by passing a defined number of individual insulated wires 43 and two strips, which comprise the shield material 50, 55, through pressure rollers 60, 65 and then passing the coaxial integrated system 75, which is obtained, through a sintering oven 27 and a cutting device 31 and extruding external jackets 90 onto the shielded individual insulated wires that are then present.

The external jacket 90 may be constructed of polyvinylchloride (PVC), PVC compounds, FEP, or similar polymers. These materials are preferred because of their environmental and electrical properties. These materials are inherently flame retardant and do not contribute to flame propagation. Moreover, they have high dielectric strength and insulation resistance, and operate in the temperature range from - 55°C. to +105°C. for PVC and 200°C. for FEP. Additionally, these materials have relatively high tensile strengths, good abrasion resistances, and can withstand exposure to the environment and corrosive chemicals. Moreover, they are relatively inexpensive and easy to process. Preferably, jacket 24 is between about 0.010 an 0.015 inches thick.. The jacket 24 may be extruded over or otherwise positioned around the shield 22.

The shield 85 can also be applied to the individual insulated wire 43 by a further prior process art. For example, it can be applied by braiding metal wires onto the individual insulated wires 43. Suitable braids are made from silver, tin or nickel-plated copper wire or silver wire. The braids are helically wrapped. Alternatively the shield may be made from copper or silver foil.

The application of coaxial cable shielding, whereby the coaxial cable shielding comprises a filled material, can also be carried out in a lamination step. This process is illustrated in Figure 6. According to this, four strips 11, 13, 95, 100, for example, are led through the pressure rollers 17, 19, whereby the strips 13, 15, which lie adjacent to the conductor 11, comprise the dielectric material, e.g. ePTFE, and the two external strips 95, 100 comprise electrically conducting strips.

In a schematic manner, Figure 7 shows a coaxial cable 102, that has been manufactured according to this with an individual insulated wire 43 in accordance with Figure 3 which is surrounded by two electric semi-shields 105, 110 in the form of an external conductor which, for its part, is insulated by an external jacket 90. The coaxial cable 102 is prepared by way using the lamination equipment of Figures 2 and 6 and passing a plurality of individual conductors 11 with four strips, whereby two are a dielectric strip 13 and two are an electrically conducting strip 90, 95, through pressure rollers 17, 19. The coaxial band cable 21 that is obtained is passed through a sintering oven 27 and a cutting device 31 and external jackets 90 are extruded onto the shielded individual insulated wires that are then present. The two semi-shields 105 and 110 do not need to be in electrical contact with one another.

In a further form of embodiment, which is illustrated in Figure 8, four dielectric strips 13, 13a, 15 and 15a are passed through the pressure rollers 17, 19. The dielectric strips 13a and 15a can have a different dielectric constant and can also be narrower than the dielectric strips 13 and 15.

After sintering and isolating by means of the cutting device of Figure 2, individual insulated wires 43 of different sizes and different impedances can be manufactured in a single manufacturing process. An external conductor in the form of a shield can be applied to the individual insulated wires 43, that have been prepared in this way, via the process in accordance with Figure 4 or Figure 6.

Figure 9 shows the result of propagation time measurements in ns/m using cables that have been manufactured in accordance with the invention. The upper line of measured values shows five measured values which were taken using five different cables manufactured at different times. The lower line of measured values shows ten measured values that were taken at the same measurement location on ten cables that were simultaneously manufactured side by side in the same lamination process. The very low differences in propagation time along the cable or between the individual cables are noteworthy in these measured results. The different propagation times in the upper and lower lines are a result of the different dielectric constants of the ePTFE material that was used in the manufacture of the cables.

Figures lOa-d and 1 la-d show the cable impedance along a cable trajectory for a conventionally manufactured cable and respectively, for a cable that has been manufactured in accordance with the invention. A comparison of these two measured impedance lines shows that the impedance profile of the conventionally manufactured cable (Figures 1 Oa-d) has much more uniform electrical characteristics than the cable that was manufactured in accordance with the invention. (Figures 1 la-d). Both the cables of Figures lOa-d and Figures 1 la-d have an insulated wire 43 with a diameter of 0,5 mm surrounded by a dielectric sheat 45,47 having an external diameter of 1,2 +/- 0,05 mm and having an braid electrical shield 85 sheathed by an external jacket 90 of diameter 2,0 +/- 0,2 mm. Further experiments have shown that between two individual cables adjacently produced then the skew is approximately 5-6 ps/ft at a signal propagation velocity of 80 % of that of light. This compares to a conventional skew of 20 ps/foot from individual cables made using conventional tape wrapping techniques.

Although a few exemplary embodiments of the present invention have been described in detail above, those skilled in the art readily appreciate that many modifications are possible without materially departing from the novel teachings and advantages which are described herein. Accordingly, all such modifications are intended to be included within the scope of the present invention, as defined by the following claims.

Claims

1. Process for the simultaneous manufacture of a plurality of electrical insulated wires (43) with an individual electrical conductor (11) and a dielectric sheath disposed about the individual electrical conductor (11), the process comprising the following steps:

a first step of passing between a first roller (17) and a second roller (19) a first dielectric material strip (13) and a dielectric material second strip (15) with a plurality of said individual electrical conductors (11) being disposed between said first dielectric material strip (13) and said dielectric material second strip (15), whereby the axes of the first roller (17) and the second roller (19) are arranged parallel to each other and each roller (17, 19) having a plurality of ribs (25), and applying pressure to the first dielectric material strip (13) and the second dielectric material strip (15) at a plurality of first positions disposed longitudinally along the first dielectric material strip (13) and the second dielectric material strip (15) and corresponding to said plurality of ribs (25) so as to laminate the first dielectric material strip (13) to the second dielectric material strip (15) at said first positions and whereby said individual electrical conductors are positioned between said first positions;

a second step of slitting said first dielectric material strip (13) and said second dielectric material strip (15) longitudinally at said first positions so as to provide said plurality of said electrical insulated wires (43).

2. Process according to claim 1 whereby the first dielectric material strip (13) has a different thickness than the second dielectric material strip (15).

3. Process according to claim 1 whereby a third dielectric strip (13a, 15a) is additionally passed between the first roller (17) and the second roller (19) and is disposed adjacent to one of the first dielectric strip (13) or the second dielectric strip (15).

4. Process according to Claim 1 wherein the dielectric sheath is made from the group of dielectric materials selected from polyethylene, perfluoralkoxy, fluoroethylene-propylene, polypropylene, polymethylpentene, polytetrafluoroethylene or expanded polytetrafluorethylene.

5. Process according to Claim 1 wherein the dielectric sheath is made from expanded polytetrafluoroethylene.

6. Process in accordance with Claim 4 in which a dielectric material is used in which air-filled micro-spheres have been deposited.

7. Process in accordance with Claim 6 in which use is made of micro-spheres comprising glass.

8. Process in accordance with the Claim 1 further comprising a third step of sintering the dielectric sheath prior to slitting said first dielectric material strip (13) and said second dielectric material strip (15).

9. Process in accordance with Claim 1 further comprising a fourth step of applying a shield (85, 105, 110) to the surface of the dielectric sheath (45, 47).

10. Process in accordance with Claim 9 in which said fourth step is carried out by is applied by braiding metal wires onto the surface of the dielectric sheath (45, 47).

a first step of passing between the first roller (17) and the second roller (19) a first electrically conducting strip (90) and a second conducting strip (96), wherein the said plurality of said individual electrical conductors (11), said first dielectric material strip (13) and said second dielectric material strip (15) are disposed between the first electrically conducting strip (90) and said second conducting strip (95), and whereby the first roller (17) and the second roller (19) apply pressure to the first electrically conducting strip (90) and the second electrically conducting strip (95) at a plurality of first positions disposed longitudinally along the first electrically conducting strip (90) and the second electrically conducting strip (95) and corresponding to said plurality of ribs (25) so as to laminate the first dielectric material strip (13), the second dielectric material strip (15), the first electrically conducting strip (90) and the second electrically conducting strip (95) at said first positions, and whereby said individual electrical conductors

(11) are positioned between said first positions.

12. Process in accordance with Claim 11 further comprising a second step of slitting said first dielectric material strip (13), said second dielectric material strip (15), said first electrically conducting strip (90) and said second electrically conducting strip (95) longitudinally at said first positions so as to provide said plurality of said electrical insulated wires (102).

13. Process according to Claim 11 further comprising a third step of sintering said first dielectric material strip (13), said second dielectric material strip (15), said first electrically conducting strip (90) and said second electrically conducting strip (95) using a sintering oven (27).

14. Process in accordance with Claim 11 whereby said first electrically conducting strip (90) and/or said second electrically conducting strip (95) are made of the group of electrically conducting materials consisting of expanded polytetrafluoroethylene, polyethylene, perfluoroalkoxy or fluoroethylenepropylene, whereby said electrically conducting material have electrically conducting particles deposited therein.

15. Process in accordance with Claim 11 further comprising a fourth step in which an insulating outer jacket (61) is applied to the shield (59).

16. Process in accordance with Claim 15 in which the outer jacket (61) is made from insulating material selected from the group of insulating materials consisting of poly(vinyl chloride), polyethylene, polytetrafluoroethylene, perfluoroalkoxy or fluoroethylenepropylene.

17. Insulated wire (80, 102) comprising an individual electrical conductor (11) embedded between at least a first dielectric material strip (13) and a second dielectric material strip (15), each dielectric material strip (13, 15) having an inside surface and an outside surface and covering a portion of the periphery of the individual conductor (11).

18. Insulated wire (43) according to Claim 17 wherein the first dielectric material strip (13) and the second dielectric material strip (15) are joined together at join sites at approximately opposite peripheral locations on the individual insulated wires.

19. Insulated wire (43) in accordance with Claim 17 wherein said first dielectric material strip (13) and/or said second dielectric material strip (15) are made from dielectric materials selected from the group of dielectric materials comprising polyethylene, perfluoralkoxy, fluoroethylene-propylene, polypropylene, polymethylpentene, polytetrafluoroethylene or expanded polytetrafluorethylene.

20. Insulated wire (43) in accordance with Claim 17 with dielectric strips (13, 15) in which air-filled micro-spheres are deposited.

21. Insulated wire (43) in accordance with Claim 20 with micro-spheres comprising glass.

22. Insulated wire (43) in accordance with Claim 18 wherein the first dielectric material strip (13) and/or the second dielectric material strip (15) are sintered at least at said join sites.

23. Cable with at least one individual insulated wire (43) in accordance with one of the Claims 17 through 22.

24. Coaxial cable with an internal insulated wire (43) in accordance with one of the Claims 17 through 22 further comprising an electrical shield (85) disposed on the outside surface of the first dielectric material strip (13) and a second dielectric material strip (15).

25. Cable in accordance with Claim 24 wherein the electrical shield (85) is braided onto the outer surface of the first dielectric material strip (13) and a second dielectric material strip (15).

26. Cable in accordance with Claim 24 whereby the electrical shield (85) comprises an electrically conducting strip.

27. Cable in accordance with Claim 24 whereby the electrical shield (105, 110) comprises two electrically conducting strips of material, whereby a first one (105) of the two electrically conducting strips of material is disposed over a first part of the outer surface of the dielectric sheath (13) and a second one (110) of the two electrically conducting strip of material is disposed over a second part of the outer surface of the dielectric sheath (15) and whereby the first electrically conducting strip (105) and the second electrically conducting strip (110) are in electrical isolation from each other over at least a portion of the lenght of the cable.

28. Cable in accordance with Claim 26 wherein the electrically conducting strip of material is selected from the group of electrically conducting materials consisting of expanded polytetrafluoroethylene, polyethylene, perfluoroalkoxy or fluoroethylenepropylene, whereby said electrically conducting material have electrically conducting particles deposited therein.

29. Cable in accordance with Claim 25 which strips of shield material (50, 55) are sintered at least at the join sites.

30. Cable in accordance with Claim 24 that has an external jacket (90) comprising an insulating material that surrounds the electrical shield (85).

31. Cable in accordance with Claim 30 whose insulating material of the external jacket (90) is selected from the group of insulating materials comprising poly(vinyl chloride), polyethylene, polytetrafluoroethylene, perfluoroalkoxy or fluoroethylenepropylene.