EP0999557A1 - Pair or quad high frequency transmission cable - Google Patents

Abstract

The cable has two insulated conductors (11,12), of diameter d, separated by dielectric spacers (41,42). To reduce cross-coupling between the conductors, these spacers are contained in a notional axial cylinder having a diameter greater than 2d, holding the conductors so that there is an air gap between the conductor and the notional cylinder.

Description

The present invention relates to a cable transmission for high frequency signals, telephone and / or data processing and video (voice data, images). The cable includes at least one pair or quarter of electrical conductors individually isolated can be surrounded by a holding envelope.

In a high frequency transmission cable of this type, the insulated conductive wires forming a pair or a quarter star are arranged perfectly symmetrically about a longitudinal axis of cable. Any lack of symmetry in the pair or quarte leads to parasitic couplings and by therefore transmission errors which cannot be corrected only depending on the speed of computerization transmitted in the pair or the quarter.

The higher the data rate transmitted in the cable and the frequency band width are the harder it is to maintain good transmission quality in the cable. In particular, crosstalk phenomena between pairs or between quartes quickly become unacceptable.

When the envelope surrounding the pair or quarter is an individual shielding screen, this one helps avoid crosstalk between the pair or quarter and others. Furthermore, for protect transmission cables against electromagnetic disturbances or couplings (EMF), it is known to collectively coat a set of pairs or quads with a continuous metallic screen.

However, an individual or collective screen generates crosstalk phenomena by the third circuit thus created. Depending on the distance between screen and pair or quarter, the characteristics of each pair or fourth, such as characteristic impedance and linear loss, can be changed.

In order to increase the speed of propagation in a cable by reducing the linear capacity between two conductors in this cable, the distance between the two conductors and an insulating sheath is increased according to EP-A-0 485 920 thanks to two insulating rods nested which encloses the two conductors neighboring rectilinear, rotate in the same direction and have the same constant pitch, the rod enclosing a driver also pressing against the other driver. In addition, the two insulating rods enclosing the two conductors can rotate in opposite direction and having different steps no multiple of each other, so as never to overlap.

So each rod is wrapped around a respective driver independently of the other rod and the other driver, which implies a cable manufacturing in two phases: a first phase relating to each pair of rod and conductor to wrap the rod around the conductor, and a second phase for the reunion of the two couples in taking care to nest the rods or put the rods periodically in contact in the space between the two conductors. Two-phase manufacturing and the care to be taken in the second phase requires a specific production line for this cable, this which increases the cost of it.

The invention aims to remedy the disadvantages of the known two-conductor cable so to facilitate the manufacture of a cable at least two conductors and at least two rods insulators.

For this purpose, a high transmission cable frequency including a predetermined number of wires individually insulated electrical conductors having a predetermined diameter d and symmetrical with respect to to a longitudinal axis, and dielectric rods in number equal to insulated electrical conductors, and contained in a fictitious cylinder having a diameter greater than 2 d and centered on the longitudinal axis for keep the insulated electrical conductors inside the fictitious cylinder with a gap of air between each wire and the fictitious cylinder, is characterized in that each rod is tangent to two wires along two continuous tangent lines respective and to the fictitious cylinder along a line respective continuous tangency.

Each ring being in continuous contact with two conductor wires, rods and cable conductors of the invention are assembled in a single phase so that insulated electrical conductors and dielectric rods can be twisted together around the longitudinal axis of the cable so that naturally hold them together. The making of the cable according to the invention is thus substantially analogous to cables with twisted conductors known which reduces the cost of the cable.

Between neighboring pairs or quads is created in the cable of the invention an air gap having a sufficient width, preferably greater than d, which reduces coupling, in particular by get rid of crosstalk phenomena between pairs or quartes. Thanks to this air gap, the cable high frequency transmission according to the invention is a low loss cable. Indeed, the capacity line length of the cable being inversely proportional to the ratio of the diameter of the fictitious cylinder to the diameter d of insulated electrical conductors, the linear capacity decreases when the diameter of the fictitious cylinder merged with the interior surface a holding envelope such as a screen metallic increases, or when the permittivity (dielectric constant) of the medium surrounding the wires decreases. As the linear loss of the transmission is proportional to the square root of the linear capacity, the insertion losses of the cable decrease when cylinder diameter fictitious increases.

deux joncs sont accolés l'un à l'autre le long de l'axe longitudinal, et chaque fil conducteur électrique isolé est logé dans un sillon sensiblement en vé formé entre les deux joncs accolés, le diamètre des joncs étant supérieur à 1,5 d ;

ou les deux fils conducteurs électriques isolés sont accolés l'un à l'autre le long de l'axe longitudinal, et chacun des deux joncs est logé dans un sillon sensiblement en vé formé entre les deux fils conducteurs électriques isolés, le diamètre des joncs étant supérieur à 0,66 d ;

ou bien encore les deux fils conducteurs électriques isolés sont écartés symétriquement l'un de l'autre le long de l'axe longitudinal, et les deux joncs sont écartés symétriquement l'un de l'autre le long de l'axe longitudinal, le diamètre des joncs étant supérieur à d.

When the number of wires is two, that is to say when the cable comprises a pair,

two rods are joined to one another along the longitudinal axis, and each insulated electrical conductor wire is housed in a substantially V-shaped groove formed between the two joined rods, the diameter of the rods being greater than 1.5 d;

or the two insulated electrical conductor wires are joined to one another along the longitudinal axis, and each of the two rods is housed in a substantially V-shaped groove formed between the two insulated electrical conductor wires, the diameter of the rods being greater than 0.66 d;

or else the two insulated electrical conductor wires are symmetrically spaced from one another along the longitudinal axis, and the two rods are symmetrically spaced from each other along the longitudinal axis, the diameter of the rods being greater than d.

soit chacun des quatre joncs est accolé longitudinalement à deux autres joncs, et chaque fil conducteur électrique isolé est logé dans un sillon sensiblement en vé formé entre deux joncs accolés respectifs, le diamètre des joncs étant supérieur à 2,4 d ;

soit chaque fil conducteur électrique isolé est accolé longitudinalement à deux autres fils, et chacun des quatre joncs diélectriques est appliqué dans un sillon sensiblement en vé formé entre deux fils conducteurs électriques isolés accolés, le diamètre des joncs étant supérieur à 0,41 d.

When the number of wires is four, that is to say when the cable comprises a fourth,

either each of the four rods is joined longitudinally to two other rods, and each insulated electrical conductor wire is housed in a substantially V-shaped groove formed between two respective joined rods, the diameter of the rods being greater than 2.4 d;

either each insulated electrical conductor wire is joined longitudinally to two other wires, and each of the four dielectric rods is applied in a substantially V-shaped groove formed between two insulated electrical conductor wires joined together, the diameter of the rods being greater than 0.41 d.

In the first variants above for pair or quarter, distance from conductors metallic of the same pair (fourth) reduces the effect "proximity" which plays a harmful role on mitigation. The latter is thus still improved.

At least one of the dielectric rods can be tubular. The introduction of tubular rods in the cable increases the air volume between two or four insulated electrical conductors forming a pair or quarter in the cable and another pair or quarter neighbor, which decreases the permittivity of the cable and consequently the linear weakening of this one.

At least one of the dielectric rods can include at least one optical fiber.

The air gap between each wire and the fictitious cylinder can be at least higher substantially at d / 2.

Cable may include an enclosure cylindrical with the same inner surface with the fictitious cylinder. The envelope can be a shielding screen with at least one metal face, or well a dielectric holding sheath.

• la figure 1 est une section transversale d'un câble de transmission avec deux fils conducteurs électriques isolés écartés par deux joncs diélectriques pleins accolés selon une première réalisation de l'invention ;
• la figure 2 est analogue à la figure 1, mais avec deux joncs diélectriques creux ;
• la figure 3 est une section transversale d'un câble de transmission avec deux fils conducteurs électriques isolés accolés et deux joncs diélectriques pleins écartés selon une deuxième réalisation de l'invention ;
• la figure 4 est analogue à la figure 3, mais avec deux joncs diélectriques creux ;
• la figure 5 est une section transversale d'un câble comprenant quatre câbles élémentaires tels que celui montré à la figure 1 ;
• la figure 6 est une section transversale d'un câble de transmission avec deux fils conducteurs électriques isolés écartés par deux joncs diélectriques pleins écartés selon une variante des première et deuxième réalisations ;
• la figure 7 est une section transversale d'un câble de transmission avec quatre fils conducteurs électriques isolés écartés par quatre joncs diélectriques pleins selon une troisième réalisation de l'invention ;
• la figure 8 est analogue à la figure 7 mais avec quatre joncs diélectriques creux ;
• la figure 9 est une section transversale d'un câble de transmission avec quatre fils conducteurs électriques isolés accolés et quatre joncs diélectriques pleins selon une quatrième réalisation de l'invention ; et
• la figure 10 est analogue à la figure 9 mais avec des joncs diélectriques creux.

Other characteristics and advantages of the present invention will appear more clearly on reading the following description of several preferred embodiments of the invention with reference to the corresponding appended drawings in which:

• Figure 1 is a cross section of a transmission cable with two insulated electrical conductors spaced apart by two solid dielectric rods joined according to a first embodiment of the invention;
• Figure 2 is similar to Figure 1, but with two hollow dielectric rods;
• FIG. 3 is a cross section of a transmission cable with two insulated insulated electrical conductor wires and two solid dielectric rods spaced apart according to a second embodiment of the invention;
• Figure 4 is similar to Figure 3, but with two hollow dielectric rods;
• Figure 5 is a cross section of a cable comprising four elementary cables such as that shown in Figure 1;
• Figure 6 is a cross section of a transmission cable with two insulated electrical conductors spaced apart by two solid dielectric rods spaced apart according to a variant of the first and second embodiments;
• Figure 7 is a cross section of a transmission cable with four insulated electrical conductors spaced apart by four solid dielectric rods according to a third embodiment of the invention;
• Figure 8 is similar to Figure 7 but with four hollow dielectric rods;
• Figure 9 is a cross section of a transmission cable with four insulated electrical conductor wires joined and four solid dielectric rods according to a fourth embodiment of the invention; and
• Figure 10 is similar to Figure 9 but with hollow dielectric rods.

Referring to Figures 1 and 3, cables of high frequency transmission CA1 and CA2 according to first and second embodiments of the invention each include a pair of conductors electric insulated individually 11 and 12. Each insulated electrical conductor consists of a solid conductor or a strand of fine copper wire annealing 2 and an individual insulating sheath 3 surrounding the solid conductor 2. For example, the sheath 3 has an outside diameter d of the order of 0.5 to 1.6 mm and is made of polyethylene or polypropylene massive, or cellular, or cellular and massive. The cable CA1 is axially symmetrical, i.e. the insulated electrical conductors 1 and 2 are symmetrical about a longitudinal axis of XX symmetry and twisted around it.

Transmission cable CA1, CA2 includes also a dielectric means in the form of two cylindrical stuffing rods 41 and 42, 51 and 52. The rods are made of low-thermoplastic material permittivity (dielectric constant), for example in extruded thermoplastic polymer, such as polyethylene or polypropylene or fluoropolymer, massive or cellular. Rush 41 and 42, 51 and 52 are twisted helically together with the wires insulated conductors 11 and 12 around the axis longitudinal XX. As shown in Figures 1 and 3, the rods 41 and 42, 51 and 52 symmetrical with respect to the axis XX are tangent inside a cylinder fictitious C1, C2 of predetermined diameter D1, D2 along of two helical and parallel lines of tangency T1 and T2 diametrically opposite with respect to the axis longitudinal XX of the cable. In cross section of cable, the diameter passing through the axes of the rods is perpendicular to the diameter passing through the axes of insulated conductors 11 and 12.

According to the first embodiment shown in Figure 1, the rods 41 and 42 are tangent to each other along the longitudinal axis XX, while being twisted around this axis, and have a diameter DJ1 = D1 / 2. Insulated electrical conductors 11 and 12 are kept in helical "grooves" in vee, diametrically opposite, formed between the rods 41 and 42 thanks to twisting around at the same time rods and threads. Each insulated conductor 11, 12 is applied along two lines of respective helical tangency of rods 41 and 42.

So that the conductive wires thus applied are contained in the fictitious cylinder C1, it is necessary that the DJ1 diameter of the rods is greater than 1.5 d.

The DJ1 diameter of rods 41 and 42 is greater at approximately 2d so that an air gap I1, I2 enters each insulated conductor 11, 12 and the interior of the fictitious cylinder C1 has a radial width LI greater than approximately d / 2, i.e. greater than DJ1 / 4 = D1 / 8 approximately. This gap width is the distance between each insulated conductor wire 11, 12 and the inner surface of a holding envelope cylindrical 61 combined with the fictitious cylinder C1, as in the CAla cable shown in Figure 2 according to a variant of the first embodiment. In practice, when two elementary CAla cables are joined longitudinally, the minimum distance between a wire insulated conductor of a pair and a conductive wire isolated from the other pair is greater than 2LI and is sufficient for signals in one of the pairs do not disturb signals in the other pair.

For example, as shown in Figure 5, a cable includes four elementary cables CA1 according to the invention, i.e. four pairs of wires insulated conductors 11-12 twisted each with two dielectric rods 41 and 42. The four cables elementary are maintained and protected in a screen collective shielding 7, possibly surrounding a insulating holding tape. Screen 7 has at least one metallized face, or is completely metallic. A outer protective sheath 8 of insulating material such as PVC, or a halogen-free flame retardant material surrounds the screen 7. Tear wires, not represented, inside the screen and between the screen 7 and the sheath 8 as well as a continuity wire electric, not shown, between screen 7 and sheath 8 are provided. Alternatively, the metal screen 7 is replaced by a sheath made of material halogen-free flame retardant thermoplastic of thickness a few tenths of a millimeter, surrounded by a thin complex polyester aluminum screen of a few tens of micrometer.

If we take care to shift longitudinally the helix pitch of the twists formed by the four pairs 11-12 to further reduce coupling electromagnetic between pairs, as shown in Figure 5, the distance between two wires of two pairs different in the four-pair cable is fine greater than the preferred minimum distance 2LI = d.

Referring to Figure 3 showing the second realization, rods 51 and 52 in the CA2 cable do not are not tangent to each other, but the wires insulated conductors 51 and 52 are tangent to each other along the longitudinal cable axis XX. Against "furrows" in vee, diametrically opposite, formed between insulated conductors 11 and 12 are applied rods 51 and 52 respectively thanks to the twists around both the rods 51 and 52 and wires 11 and 12. Each rod 51, 52 is in mechanical contact along two lines of tangency respective helical with conductive wires isolated 11 and 12.

In this second embodiment, the gap I1, I2 between each insulated conductor wire 11, 12 and the interior of the fictitious cylinder C2 is created when the DJ2 diameter of rods 51 and 52 is greater than 0.66 d. Preferably, the width LI of the interstices Il and I2 is greater than approximately d / 2, which corresponds to a minimum gap width of D2 / 6 approximately. The diameter of rods 51 and 52 is preferably at less substantially equal to approximately d. The second CA2 cable production is thus less bulky that the first realization, with equal diameter d of wire insulated conductor.

By analogy with FIG. 2, a variant of CA2a cable of the second embodiment includes a cylindrical holding envelope 62 whose surface interior is confused with the fictitious cylinder C2, that is to say tangent with each of the rods 51 and 52 and separated by a distance LI from the conducting wires isolated 11 and 12.

The cylindrical holding envelope 61, 62 in Figure 2, 4 is a metal shielding screen in the form of a tube having at least one side metallic or is completely metallic. According to one another variant, the casing 61, 62 is a sheath of dielectric tubular support containing the pair 11-12.

According to other variants of the first and second achievement, the solid rods 41 and 42, 51 and 52 are replaced by stuffing tubes 41a and 42a, 51a and 52a in low-thermoplastic material permittivity, of the same outside diameter DJ1, DJ2, as shown in Figures 2 and 4. These variants help reduce the linear loss of the cable thanks to the additional air trapped in the stuffing tubes 41a and 42a, 51a and 52a.

In the multi-pair cable shown in the Figure 5, the elementary cables CA1 can be partially or totally by CA2 cables such as shown in Figure 3, and / or by cables CAla and / or CA2b shown in Figures 2 and 4.

According to a variant of the first and second achievements shown in Figure 6, a cable CA2b transmission has two conductors electrical insulated 11 and 12 which are separated symmetrically from the longitudinal axis of the cable, and two solid or hollow dielectric rods, 51b and 52b which are also symmetrically spaced from the axis longitudinal of the cable. In cross section, of a substantially analogous to a fourth of conductors, the centers of rods 51b and 52b of diameter dj are located at two opposite vertices of a side square dj, and the centers of the conductors 11 and 12 are located substantially in said square under the other two opposite vertices of the square. The diameter d of conductors 11 and 12 is less than the diameter of rush dj. Thin interstices of width LI are thus provided between the insulated conductors 11 and 12 and the internal periphery C2b of a holding envelope cylindrical 62b which is tangent only to the rods dielectrics 51b and 52b. The internal diameter of the envelope 62b is substantially equal to 2.41 dj.

To elementary to pair cable structures shown in Figures 1 to 4 correspond to analogous structures for star quads shown in Figures 7-10.

According to a third embodiment, in the cable CA3, CA3a shown in figure 7, 8, four rods of solid or tubular packing 43 to 46, 43a to 46a are twisted together with two pairs of wires insulated conductors 11-13 and 12-14 around the axis longitudinal cable XX. Each wire 11 to 14 has in cross section two tangent points with two respective adjacent rods 43-44, 531-54 to 46-43, 56-53 which have in common a line of tangency which, in cross section, is aligned radially with the cable axis XX and the wire axis 11 to 14. Viewed in cross section, the conductive wires 11 to 14 are centered on the vertices of a square whose main axes are confused with the diagonals of a smaller side square, at the tops of which are centered the rods 43 to 46, 43a to 46a. CA3 cable, CA3a includes a first pair of lead wires isolated 11-13 housed in two external "grooves" in vé diametrically opposed between two adjacent rods 43 and 44 and between the two other adjacent rods 45 and 46, and a second pair of insulated conductors 12-14 housed in two external "grooves" in vé diametrically opposed between two adjacent rods 44 and 45 and between the two other adjacent rods 46 and 43, respectively.

The diameter DJ3 of the rods 43 to 46, 43a to 46a is greater than 2.4 d so that the insulated conducting wires 11 to 14 in the cables CA3 and CA3a are contained in a fictitious cylinder C3 tangent to the four rods along four lines of tangency helical and parallel T3 to T6. The fictitious cylinder C3 has a diameter D3 = (1 + 2 ) DJ3 / 2. The air gap I1 to I4 between each insulated conductor wire 11 to 14 and the interior of the fictitious cylinder C3 has a radial width LI preferably greater than approximately d / 2, that is to say greater than 0, 2 DJ3 approximately. This radial width LI is the distance between each insulated conductor wire and the inner surface of a cylindrical envelope 63, of metallic, plastic-metallic or plastic material, which coincides with the fictitious cylinder C3 in the cable CA3a shown in FIG. 8 .

According to a fourth embodiment, the cables CA4 and CA4a shown in Figures 9 and 10 include also each four rods 53 to 56, 53a to 56a twisted with insulated conductors 11-13 and 12-14 of two pairs. Lead wires 11 to 14 are arranged in the center of the cable CA4, CA4a, of a analogous to rods 43 to 46, 43a to 46a in the cable CA3, CA3a. Seen in cross section, the wires conductors 11 to 14 are centered on the vertices of a square of side d whose major axes are combined with the diagonals of a larger side square, at the tops of which the rods 53 to 56, 53a to 56a are centered. Each thread 11 to 14 has two helical tangency lines around the axis longitudinal cable XX, with two adjacent rods respective 53-54 to 56-53. The conducting wires 11 and 13, 12 and 14 of a pair are still diametrically opposites.

Each rod 53 or 53a, 54 or 54a, 55 or 55a, 56 or 56a is applied along two lines of helical tangency in an external v-groove respective, formed between a respective thread 11 or 11a, 12 or 12a, 13 or 13a, 14 or 14a of one of the pairs and a respective lead 14 or 14a, 11 or 11a, 12 or 12a, 13 or 13a of the other pair, these two wires being adjacent by a line of tangency helical.

The diameter DJ4 of the four rods 53 to 56, 53a to 56a must be greater than 0.41 d, where d is the wire diameter 11 to 14, so that the wires conductors are not in mechanical contact with a fictitious cylinder C4 tangent to the four rods along four helical tangent lines and parallels T3 to T6 respectively. Interstices of air I1 to I4 between the fictitious cylinder C4 such that that of the inner surface of an envelope of holding 64 in the same material as the envelope 61, 62, 63 defined above, and the conducting wires insulated 11 to 14 preferably have a width LI greater than approximately d / 2, i.e. 0.6 DJ4 about.

In all the embodiments of the invention, a or several hollow or solid rods may contain one or more optical fibers. Optical fibers FO are embedded in the dielectric material of the rods solid, as illustrated in Figures 1, 6 and 9, or are embedded in a filling material and sealant, such as gel, contained in rods hollow as illustrated in Figures 4 and 8.

Claims (16)

High frequency transmission cable comprising a predetermined number of conducting wires individually insulated electrical (11, 12; 11 to 14) having a predetermined diameter d and symmetrical relative to a longitudinal axis (XX), and rods dielectric (41, 42; 51, 52; 43 to 46; 53 to 56) equal in number to the electrical conductors isolated (11, 12; 11 to 14), and contained in a fictitious cylinder (C1; C2; C3; C4) having a diameter greater than 2 d and centered on the longitudinal axis (XX) to hold the electrical conductors insulated (11-12; 11-14) inside the cylinder fictitious with an air gap (I1-I2; I1-I4; IH) between each wire and the fictitious cylinder, characterized in that each rod (41, 42; 51, 52; 43 to 46; 53 at 56) is tangent to two wires (11-12; 11-14) following two respective tangent lines and at fictitious cylinder along a line of tangency respective continuous (T1, T2; T3 to T6). Cable according to claim 1, in which the insulated electrical conductors (11, 12; 11 to 14) and the dielectric rods (41, 42; 51, 52; 43 to 46; 53 to 56) are twisted together around the longitudinal axis (XX). Cable according to claim 1 or 2, in which the number of wires is two, both rods (41, 42) are joined to one another along the longitudinal axis (XX), and each thread electric insulated (11, 12) is housed in a groove substantially v-shaped formed between the two rods joined. Cable according to claim 3, in which the diameter (DJ1) of the rods (41, 42) is greater than 1.5 d. Cable according to claim 1 or 2, in which the number of wires is two, the two wires insulated electrical conductors (11, 12) are joined to each other along the longitudinal axis (XX), and each of the two rods (51, 52) is housed in a substantially V-shaped groove formed between the two wires insulated electrical conductors. Cable according to claim 5, in which the diameter (DJ2) of the rods (51, 52) is greater than 0.66 d. Cable according to claim 1 or 2, in which the number of wires is two, the two wires insulated electrical conductors (11, 12) are separated symmetrically to each other along the axis longitudinal (XX), and the two rods (51b, 52b) are spread symmetrically from each other along the longitudinal axis. Cable according to claim 7, in which the diameter of the rods (51b, 52b) is greater to d. Cable according to claim 1 or 2, in which the number of wires is four, each of four rods (43 to 46) is joined longitudinally to two other rods, and each thread insulated electric (11 to 14) is housed in a groove substantially V-shaped formed between two adjoining rods respective. Cable according to claim 9, in which the diameter (DJ3) of the rods (43 to 46) is greater than 2.4 d. Cable according to claim 1 or 2, in which the number of wires is four, each wire insulated electrical conductor (11 to 14) is attached longitudinally to two other wires, and each of four dielectric rods (53 to 56) is applied in a substantially V-shaped groove formed between two insulated electrical conducting wires joined together. Cable according to claim 11, in which the diameter (DJ4) of the rods (53 to 56) is greater than 0.41 d. Cable conforms to any of claims 1 to 12, wherein at least one of dielectric rods (41a, 42a; 51a, 52a; 43a to 46a ; 53a to 56a) is tubular. Cable conforms to any of claims 1 to 13, wherein at least one of dielectric rods comprises at least one fiber optical (FO). Cable conforms to any of claims 1 to 14, wherein the air gap (I1-I2; I1-I4; IH) between each wire and the cylinder fictitious is at least substantially greater than d / 2. Cable conforms to any of Claims 1 to 15, comprising an envelope cylindrical (61; 62; 63; 64; 65; 66) whose interior surface (C1; C2; C3; C4; C5; C6) is substantially confused with the fictitious cylinder.

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