SHIELD-SUPPORTING FILLER FOR DATA COMMUNICATIONS CABLES WITH REDUCED CROSS-SECTIONAL DIAMETER

Abstract

Methods of design, manufacture and implementations of balanced twisted pair cables with a barrier tape or shield, with tuned attenuation, impedance, and coupling properties. A filler is included within the cable to separate the pairs and provide a support base for the shield, allowing for optimized ground plane uniformity and stability for tuned attenuation, impedance, and coupling properties. The filler orientation, shape, and size provides support for the shield such that a gap is provided between the shield and the twisted pairs with a given minimum size without increasing the maximum cable core size. The length of arms of the filler may be adjusted to fine-tune the size and shape of this gap and control air-dielectric volume and radial contact or spacing between any pair(s) and the shield, tuning electrical performance characteristics caused by non-linear effects of electromagnetic interactions at short ranges between the pairs, shield, filler, or other components.

Claims

1. A data cable for providing enhanced electrical performance in a reduced cross-sectional configuration comprising: a filler comprising a plurality of filler arms that are each configured to radiate from a central portion of the filler so as to define a plurality of channel portions; a first twisted insulated conductor pair disposed in a first channel portion of the plurality of channel portions; a second twisted insulated conductor pair disposed in a second channel portion of the plurality of channel portions; and a conductive barrier tape portion configured to surround at least a portion the filler, a portion of the first twisted insulated conductor pair, and a portion the second twisted insulated conductor pair; wherein a first arm portion of the plurality of arms is configured to extend along a first arm length portion greater than a first distance portion extending from the central portion of the filler to a line tangent to an outermost portion of the first twisted insulated conductor pair so as to define an enhanced cross-sectional configuration of the first channel; and wherein the enhanced cross-sectional configuration comprises: a first portion of an outer surface of a first insulator of the first twisted insulated conductor pair that is configured to contact the first arm portion; a second portion of the outer surface of the first insulator of the first twisted insulated conductor pair that is configured to contact a second arm portion of the plurality of arms; an outer surface of a second insulator of the first twisted insulated conductor pair that is configured to contact at least a portion of the conductive barrier tape; and an outer surface of a first insulator of the second twisted insulated conductor pair that is configured to contact at least one of the first arm portion or the second arm portion; and wherein the first arm length portion is greater than twice a conductor diameter portion of the first twisted pair of insulated conductors so as to form a reduced cross-sectional configuration.

2. The data cable of claim 1, wherein the first arm length portion is greater than twice a diameter of a conductor of the first twisted insulated conductor pair.

3. The data cable of claim 1, wherein the first arm length portion is greater than a longest dimension across the first twisted insulated conductor pair.

4. The data cable of claim 1, wherein the enhanced cross-sectional configuration is configured to increase an average power summed attenuation to near-end crosstalk ratio (PS-ACRN) electrical characteristic value of the data cable over a frequency range from 200 to 600 MHz by at least 3 decibels relative to an average PS-ACRN electrical characteristic value of a second data cable lacking a filler having at least one arm with an arm length portion greater than a first distance portion from a central portion of the filler of the second data cable to a line tangent to an outermost portion of a twisted insulated conductor pair of the second data cable over the frequency range.

5. The data cable of claim 1, wherein the first arm length portion is at least forty percent of a total radius of the data cable.

6. The data cable of claim 1, wherein the enhanced cross-sectional configuration is configured to reduce an attenuation response of the data cable over a frequency range from 300 to 600 MHz by at least 1 decibel relative to an attenuation response of a second data cable lacking a filler having at least one arm with an arm length portion greater than a first distance portion from a central portion of the filler of the second data cable to a line tangent to an outermost portion of a twisted insulated conductor pair of the second data cable over the frequency range.

7. The data cable of claim 1, wherein the enhanced cross-sectional configuration is configured to increase an average input impedance of the data cable over a frequency range from 50 to 150 MHz by at least 2 relative to an average input impedance of a second data cable lacking a filler having at least one arm with an arm length portion greater than a first distance portion from a central portion of the filler of the second data cable to a line tangent to an outermost portion of a twisted insulated conductor pair of the second data cable over the frequency range.

8. A data cable having a reduced filler channel configuration for providing enhanced electrical performance comprising: a twisted pair filler having a first filler arm portion of a first filler arm, a second filler arm portion of a second filler arm, and a central filler portion; wherein the first filler arm portion is configured to extend along a first filler arm length portion that is greater than a distance portion that extends from the central filler portion to a line that extends tangent to an outermost portion of a first twisted insulated conductor pair so as to form a cross-sectional filler configuration of the data cable as an enhanced cross-sectional filler channel configuration; wherein the enhanced cross-sectional filler channel configuration comprises: a first outer surface portion of a first insulator of the first twisted insulated conductor pair that is configured to contact the first filler arm portion; a second outer surface portion of the first insulator of the first twisted insulated conductor pair that is configured to contact the second filler arm portion that is different from the first filler arm portion; a third outer surface of a second insulator of the first twisted insulated conductor pair that is configured to contact at least a portion of a conductive barrier tape; a fourth outer surface of a first insulator of the second twisted insulated conductor pair that is configured to contact at least one of the first filler arm portion or the second filler arm portion; and wherein the first filler arm length portion is greater than twice a diameter portion of a conductor of the first twisted insulated conductor pair so as to form the enhanced cross-sectional filler channel configuration by reducing the cross-sectional filler channel configuration from a first cross-sectional filler channel configuration to a second cross-sectional filler channel configuration that is smaller than the first cross-sectional filler channel configuration.

9. The data cable of claim 8, wherein the first twisted insulated conductor pair comprises insulation having a dielectric constant of greater than or equal to 1 to and less than or equal to

3.

10. The data cable of claim 8, wherein the first filler arm portion and the second filler arm portion are configured to radiate from opposite sides of the central filler portion.

11. The data cable of claim 8, further comprising a shield around the enhanced cross-sectional filler channel configuration.

12. A data cable for providing an enhanced conductor pair separator channel configuration comprising: a conductor pair separator having a first separator arm portion, a second separator arm portion, and a central separator portion; wherein the first separator arm portion is configured to extend along a first separator arm length portion that is at least forty percent of a total radius of the data cable so as to form an enhanced cross-sectional separator channel configuration; wherein the enhanced cross-sectional separator channel configuration comprises: a first outer surface portion of a first insulator of a first twisted insulated conductor pair that is configured to face the first separator arm portion; a second outer surface portion of the first insulator of the first twisted insulated conductor pair that is configured to face the second separator arm portion that is different from the first separator arm portion; a third outer surface of a second insulator of the first twisted insulated conductor pair that is configured to face at least a portion of a conductive barrier tape; a fourth outer surface of a first insulator of a second twisted insulated conductor pair that is configured to face at least one of the first separator arm portion or the second separator arm portion; and wherein the first separator arm length portion is configured to be greater than twice a diameter portion of a conductor of the first twisted insulated conductor pair so as to form the enhanced cross-sectional separator channel configuration by reducing the cross-sectional separator channel configuration from a first cross-sectional separator channel configuration to a second cross-sectional separator channel configuration that is smaller than the first cross-sectional separator channel configuration.

13. The data cable of claim 12, wherein the conductor pair separator comprises a twisted conductor pair separator configured to separate the first twisted insulated conductor pair from the second twisted insulated conductor pair.

14. The data cable of claim 12, wherein the first outer surface portion of the first insulator of the first twisted insulated conductor pair is configured to contact the first separator arm portion.

15. The data cable of claim 12, wherein the second outer surface portion of the first insulator of the first twisted insulated conductor pair is configured to contact the second separator arm portion that is different from the first separator arm portion.

16. The data cable of claim 12, wherein the third outer surface of the second insulator of the first twisted insulated conductor pair that is configured to contact at least the portion of the conductive barrier tape.

17. The data cable of claim 12, wherein the fourth outer surface of the first insulator of the second twisted insulated conductor pair is configured to contact at least one of the first separator arm portion or the second separator arm portion.

18. A data cable for providing an enhanced separator channel configuration comprising: a conductor pair separator having a first separator arm portion of a first separator arm, a second separator arm portion of second separator arm, and a central separator portion; wherein the first separator arm portion is configured to extend along a first separator arm length portion that is greater than a central-to-outer-insulator pair distance portion that extends from the central separator portion to a line that extends tangent to an outer portion of a first twisted insulated conductor pair so as to form a separation channel configuration of the data cable as an enhanced cross-sectional separator channel configuration; and wherein the first separator arm length portion is configured to be greater than twice a diameter portion of a conductor of the first twisted insulated conductor pair so as to form the enhanced cross-sectional separator channel configuration by reducing the cross-sectional separator channel configuration from a first cross-sectional separator channel configuration to a second cross-sectional separator channel configuration that is smaller than the first cross-sectional separator channel configuration.

19. The data cable of claim 18, wherein the conductor pair separator comprises a twisted conductor pair separator.

20. The data cable of claim 18, wherein the enhanced cross-sectional separator channel configuration comprises: a first outer surface portion of a first insulator of the first twisted insulated conductor pair that is configured to face the first separator arm portion; and a second outer surface portion of the first insulator of the first twisted insulated conductor pair that is configured to face the second separator arm portion that is different from the first separator arm portion.

21. The data cable of claim 18, wherein a third outer surface of a second insulator of the first twisted insulated conductor pair is configured to face at least a portion of a conductive barrier tape.

22. The data cable of claim 18, wherein a fourth outer surface of a first insulator of the second twisted insulated conductor pair is configured to face at least one of the first separator arm portion or the second separator arm portion.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0019] FIG. 1A is a cross section of an embodiment of a balanced twisted pair cable incorporating a filler;

[0020] FIG. 1B is a top view of an embodiment of the cable of FIG. 1A with a longitudinally wrapped shield;

[0021] FIG. 1C is a top view of an embodiment of the cable of FIG. 1A with a helically wrapped shield;

[0022] FIG. 1D is a cross section of an embodiment of the cable of FIG. 1C with a collapsed helically wrapped shield;

[0023] FIG. 2A is a cross section of an embodiment of a balanced twisted pair cable incorporating a shield-supporting filler;

[0024] FIG. 2B is an enlarged portion of the embodiment of the balanced twisted pair cable incorporating a shield-supporting filler of FIG. 2A;

[0025] FIG. 2C is a cross section of an embodiment of the shield-supporting filler of FIG. 2A;

[0026] FIG. 2D is an enlarged portion of a cross section of another embodiment of the balanced twisted pair cable including a shield-supporting filler with reduced arm or fin length;

[0027] FIG. 2E is a cross section of another embodiment of a balanced twisted pair cable incorporating a shield-supporting filler with an omitted arm or fin;

[0028] FIGS. 2F-2L are cross-sections of embodiments of fillers;

[0029] FIGS. 3A-3C are graphs of attenuation response over frequency for different embodiments of balanced twisted pair cables;

[0030] FIG. 3D is a graph illustrating a portion of the graphs of FIGS. 3A-3C for a given frequency range;

[0031] FIGS. 3E-3N are tables of measured attenuation values for the different embodiments of balanced twisted pair cables of FIGS. 3A-3C;

[0032] FIG. 4A is a graph of input impedance over frequency for different embodiments of balanced twisted pair cables;

[0033] FIG. 4B is a graph illustrating a portion of the graph of FIG. 4A for a given frequency range;

[0034] FIGS. 4C-4L are tables of measured input impedance values for the different embodiments of balanced twisted pair cables of FIG. 4A;

[0035] FIG. 5A is a graph of power sum attenuation to crosstalk ratio near-end (PS ACRN) over frequency for different embodiments of balanced twisted pair cables;

[0036] FIG. 5B is a graph illustrating a portion of the graph of FIG. 5A for a given frequency range; and

[0037] FIGS. 5C-5L are tables of measured PS ACRN values for the different embodiments of balanced twisted pair cables of FIG. 5A.

[0038] In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements.

DETAILED DESCRIPTION

[0039] High-bandwidth Category 6A cables and other similar high-bandwidth data cables have strict specifications for maximum return loss and crosstalk, amongst other electrical performance parameters. Crosstalk is the result of electromagnetic interference (EMI) between adjacent pairs of conductors in a cable, whereby signal flow in a first twisted pair of conductors in a multi-pair cable generates an electromagnetic field that is received by a second twisted pair of conductors in the cable and converted back to an electrical signal. Similarly, alien crosstalk is electromagnetic interference between adjacent cables. In typical installations with a large number of cables following parallel paths from switches and routers through cable ladders and trays, many cables with discrete signals may be in close proximity and parallel for long distances, increasing alien crosstalk. Alien crosstalk is frequently measured via two methods: power sum alien near end crosstalk (PSANEXT) is a measurement of interference generated in a test cable by a number of surrounding interfering or disturbing cables, typically six, and is measured at the same end of the cable as the interfering transmitter; and power sum alien attenuation to crosstalk ratio, far-end (PSAACRF), which is a ratio of signal attenuation due to resistance and impedance of the conductor pairs, and interference from surrounding disturbing cables.

[0040] Return loss is a measurement of a difference between the power of a transmitted signal and the power of the signal reflections caused by variations in impedance of the conductor pairs as well as the characteristic impedance relative to the system impedance. Any random or periodic change in impedance in a conductor pair, caused by factors such as the cable manufacturing process, cable termination at the far end, damage due to tight bends during installation, tight plastic cable ties squeezing pairs of conductors together, or spots of moisture within or around the cable, will cause part of a transmitted signal to be reflected back to the source. The same is true for the overall offset of pair characteristic impedance relative to system impedance.

[0041] Failure to meet the return loss and crosstalk requirements means that the cable may not be usable for high data rate communications such as 1000BASE-T (Gigabit Ethernet), 10GBASE-T (10-Gigabit Ethernet), or other future emerging standards. Some attempts at addressing alien and internal crosstalk include internal plastic fillers, sometimes referred to as splines, separators, or crossweb fillers, that provide separation between adjacent pairs of conductors within the cable. However, fillers add significant expense to manufacturing, and increase the thickness and density of the cables.

[0042] Conductive shields, typically made of a discontinuous or continuous conductive layer of foil or other conductive material, and potentially including one or more non-conductive layers (e.g. substrates or barriers under and/or on top of the conductive layer) may be utilized, with or without a drain wire in various implementations, to provide an EMI barrier in an attempt to control alien crosstalk and ground current disruption, but add manufacturing complexity depending on implementation. However, shields may magnify the susceptibility of cross-talk, increase delay and delay skew, and significantly reduce the twist lay delta choices to achieve crosstalk levels. However, simply increasing the size of the cable in order to space out the shield from the conductors results in larger, heavier, and more expensive cables, as well as greater variability in performance due to shifting of conductors within the cable. Thus, there are competing interests in having cables as small as possible and having uniform shielding and electrical characteristics.

[0043] For example, and referring first to FIG. 1A, illustrated is a cross section of an embodiment of a balanced twisted pair cable 100. The cable includes a plurality of unshielded twisted pairs 102a-102d (referred to generally as pairs 102) of individual conductors 104 having insulation 106. Conductors 104 may be of any conductive material, such as copper or oxygen-free copper (i.e. having a level of oxygen of 0.001% or less) or any other suitable material, including Ohno Continuous Casting (OCC) copper or silver. Conductor insulation 106 may comprise any type or form of insulation, including fluorinated ethylene propylene (FEP) or polytetrafluoroethylene (PTFE) Teflon, high density polyethylene (HDPE), low density polyethylene (LDPE), polypropylene (PP), or any other type of suitable insulation. The insulation 106 around each conductor 104 may have a low dielectric constant (e.g. 1-3) relative to air, reducing capacitance between conductors. The insulation 106 may also have a high dielectric strength, such as 400-4000 V/mil, allowing thinner walls to reduce inductance by reducing the distance between the conductors 104 within each pair 102. In some embodiments, each pair 102 may have a different degree of twist or lay (i.e. the distance required for the two conductors to make one 360-degree revolution of a twist), reducing coupling between pairs. In other embodiments, two pairs may have a longer lay (such as two opposite pairs 102a, 102c), while two other pairs have a shorter lay (such as two opposite pairs 102b, 102d). Each pair 102 may be placed within a channel bordered or defined by two adjacent arms or fins of a filler 108, said channel sometimes referred to as a groove, void, region, or other similar identifier.

[0044] In some embodiments, cable 100 may include a filler 108, sometimes referred to as a spline, separator, or crossweb filler. Filler 108 may be of a non-conductive material such as flame retardant polyethylene (FRPE) or any other such low loss dielectric material, and may be solid or foamed in various implementations. In many implementations, filler 108 may have a plurality of arms, separators, or fins (generally referred to as arms, though other terms may be utilized) radiating from a central point as shown (e.g. four arms). In some implementations with four arms at right angles to each other, each pair of arms may define a channel or quadrant of the cable containing a corresponding twisted pair of conductors. Similarly, in other implementations with a greater or fewer number arms, regions between adjacent arms may be defined as quadrants, sectors, regions, channels, sub-space, or by similar terms.

[0045] In some embodiments, cable 100 may include a conductive barrier tape 110 surrounding filler 108 and pairs 102, which may serve as an EMI barrier to mitigate ground interference. The conductive barrier tape 110 may comprise a continuously conductive tape, a discontinuously conductive tape, a foil, a dielectric material, a combination of a foil and dielectric material, or any other such materials. For example, in some implementations, a conductive material, such as aluminum foil, may be located or contained between two layers of a dielectric material, such as polyester (PET). Intermediate adhesive layers may be included between the dielectric material and conductive material. In some embodiments, a conductive carbon nanotube layer may be used for improved electrical performance and flame resistance with reduced size. In some implementations, the conductive layer may be continuous along a longitudinal length of the cable. In some implementations, the conductive layer may be continuous across a lateral width of the barrier tape (e.g. orthogonal to the longitude of the cable). In some implementations, the conductive layer may be continuous in both a longitudinal and lateral direction. In some implementations, the conductive layer may extend to each lateral edge of the barrier tape. In other implementations, the conductive layer may extend to one lateral edge of the barrier tape; in some such implementations, a top and bottom dielectric layer surrounding the conductive layer may be continuous and wrap around or fold over the conductive layer at the other lateral edge. This may reduce manufacturing complexity in some implementations. In some implementations, edges of the tape may include folds back over themselves. In one embodiment, the tape has three layers in a dielectric/conductive/dielectric configuration, such as polyester (PET)/Aluminum foil/polyester (PET). In some embodiments, the tape may not include a drain wire and may be left unterminated or not grounded during installation.

[0046] In some embodiments, the cable 100 may include a jacket 112 surrounding the barrier tape 110, filler 108, and/or pairs 102. Jacket 112 may comprise any type and form of jacketing material, such as polyvinyl chloride (PVC), fluorinated ethylene propylene (FEP) or polytetrafluoroethylene (PTFE) Teflon, high density polyethylene (HDPE), low density polyethylene (LDPE), or any other type of jacket material. In some embodiments, jacket 112 may be designed to produce a plenum-or riser-rated cable.

[0047] Although shown for simplicity in FIG. 1A as a continuous ring, barrier tape 110 may comprise a flat tape material applied around filler 108 and pairs 102, and may have an overlapping portion. For example, FIG. 1B is a top view of an embodiment of the cable 100 of FIG. 1A (as a top view, only conductor pairs 102a and 102b are visible; conductor pairs 102c and 102d hidden from view beneath the conductor pairs 102a and 102b and filler 108). As shown, the cable 100 includes a longitudinally wrapped shield 110 surrounding the conductor pairs 102 and filler 108 (a jacket 112 is not illustrated for clarity, and may also be optional in some implementations). Longitudinally wrapped shields as shown are sometimes referred to as cigarette wraps or by similar terms and are wrapped around the filler and conductor pairs during manufacturing, with a seam in the shield 110 running longitudinally along the length of the cable (as shown, the seam may overlap an inner portion of the shield in many implementations).

[0048] Longitudinally wrapped shields are simple for manufacturing, but may not provide the best performance for avoidance of crosstalk and return loss. For example, external and internal signals may couple to the edge or seam of the shield and travel along the length of the cable. Gaps in the overlapping portions of the shield may also allow small wavelength signals to pass through the shield, reducing its ability to block EMI. Additionally, longitudinally wrapped shields may not be wrapped very tightly, resulting in an air space between the shield and conductor pairs 102. This may allow the conductor pairs 102 to move relative to each other (although constrained by the filler in two directions, for a cross-shaped filler).

[0049] For example, returning briefly to FIG. 1A, in many implementations of cables incorporating fillers 108, the lateral dimensions (height and width) of the filler 108 may be smaller than the diameter of the cable, theoretically resulting in gaps 114 between the filler 108 and barrier tape 110 as shown and creation of an air space 120 (although, in practice and in many implementations, as discussed below, the barrier tape 110 and/or jacket 112 are collapsed down onto the conductor pairs). For example, the cable has a minimum diameter determined by a line through a pair of a conductors (e.g. 102a), the center of the filler 108, and a second pair of conductors (e.g. 102d). As the conductors and filler are substantially solid and not compressible, when the pairs are oriented such that the conductors are on a diameter of the cable as shown, the cable cannot compress further in this direction. The filler is typically smaller than this diameter for cost savings, as the filler may be a substantial part of the cost of manufacturing of the cable, and it adequately serves to separate the conductor pairs. For example, high flame-rating materials for fillers are highly expensive, so it is typically desirable to reduce the size of the filler as much as possible. However, due to the gaps 114 and resulting air space 120 between the barrier tape 110, the conductor pairs may be able to move relative to each other in a direction away from the filler. For example, in the illustrated example of FIG. 1A, conductor pair 102c has space to move to the left, farther from conductor pair 102d. This may result in variability in crosstalk between conductor pairs at certain positions along the cable, resulting in impaired performance.

[0050] As shown, the theoretical air space 120, sometimes referred to as a gap region, air-dielectric region, sub-space within the cable, or by other similar terms, is due to both the small dimensions of the filler and the surrounding barrier tape 110, along with the maintained position of the barrier tape (and jacket). Because the filler 108 has arms that do not extend past a line 116 (shown as dotted lines) tangent to the outermost surfaces of adjacent conductor pairs (e.g. pairs 102a and 102c, or 102c and 102d), a substantial air space 120 with varying volume (particularly longitudinally along the cable as the twisted pairs of conductors are in different orientations) is present between the conductor pairs and the barrier tape 110. If the barrier tape is relatively loose due to the manner in which it is wrapped around the conductors and filler during manufacture, which may apply particularly in some implementations of longitudinally wrapped tapes, or if the barrier tape is fixed to a surrounding stiff jacket, the tape is not pressed down tightly to the conductor pairs 102, potentially allowing this uncontrolled air space 120 to form.

[0051] However, as discussed above, in many implementations, the barrier tape may be pulled tight during manufacture or pressed down onto the conductor pairs. FIG. 1C is a top view of an embodiment of the cable 100 of FIG. 1A with a helically wrapped shield 110 (as a top view, only conductor pairs 102a and 102b are visible; conductor pairs 102c and 102d are hidden from view beneath the conductor pairs 102a and 102b and filler 108). As shown, the cable 100 includes a helically wrapped shield 110, sometimes referred to as a spiral-wrapped shield or barrier tape, surrounding the conductor pairs 102 and filler 108 (a jacket 112 is not illustrated for clarity, and may also be optional in some implementations). In many implementations, substantial tension may be applied to the helically wrapped shield 110 during manufacture, allowing the shield to be pressed or squeezed tightly to the conductor pairs. This reduces or eliminates the air space surrounding the conductor pairs, and also locks down or prevents the conductor pairs from moving relative to each other, reducing crosstalk.

[0052] However with either a helically wrapped tape under tension or a longitudinally wrapped tape compressed down against the conductors, squeezing the shield tightly to the conductor pairs affects the cross-sectional geometry of the cable. FIG. 1D is a cross section of an embodiment of the cable 100 of FIG. 1C with a collapsed helically wrapped shield 110, and lacking an implementation of the shield-supporting filler discussed herein. As shown, while the air gaps 114 are substantially reduced (and almost eliminated on one side), the cable is no longer round. Worse, as each conductor pair twists along the longitudinal length of the cable, the cross-sectional geometry of the cable (and accordingly, the distance of the shield 110 from each conductor) will vary. This lack of uniformity may impair alien crosstalk performance, and result in non-optimized ground plane uniformity and lack of stability for impedance/RL performance. Further, heavier insulation may be required to counteract the effects of increased attenuation and lowered impedance.

[0053] Accordingly, in implementations of cables lacking embodiments of the shield-supporting fillers discussed herein, reduction in the sizing of a filler may result in non-uniform cable cross-sections and impaired electrical performance,

[0054] These and other problems may be solved by a cable utilizing a well-tuned shield or barrier-tape supporting filler. FIG. 2A is a cross section of an embodiment of a balanced twisted pair cable 200 incorporating a shield-supporting filler 202a. As shown, the dimensions of the filler 202a are substantially larger than the implementations of FIGS. 1A-1D, such that terminal portions of each arm of the filler 202a contact the surrounding shield 110 at contact points 204a-204d. The shield 110 may be applied helically during manufacture with significant tension, reducing air gaps around the conductor pairs and preventing the conductor pairs from moving relative to each other. In many implementations, as shown, the cable and/or shield 110 may not be perfectly circular, as the tension applied to the shield may cause it to be pulled in closer where room is available due to the orientation of a conductor pair (e.g. as shown, the radius of the cable between contact points 204c and 204d is slightly smaller than between other adjacent pairs of contact points). While pulling the barrier tape or shield tight against the conductor pairs prevents the conductors from moving relative to each other, decreasing performance variability, the proximity of the shield to the conductors may degrade the electrical characteristics of the cable, and particularly attenuation, impedance, and near end crosstalk (NEXT). However, these characteristics and variability may be optimized by adjusting the length of fins of the filler to support or lift the shield or barrier tape away from the conductors. As shown in the accompanying graphs and tables of FIGS. 3A-5L, there is an unexpected but substantial electrical performance improvement when the filler fin length is optimized, while not increasing the cable core diameter.

[0055] FIG. 2B is an enlargement of the left side of the embodiment of the cable illustrated in FIG. 2A. In the example illustrated, the arms of the filler 202a have a length approximately equal to the inner radius of the shield 110 or equal to the maximum radius of the cable through a conductor pair, such that the cable is substantially circular. However, other lengths are possible and may be utilized to optimize various characteristics of the cable. For example, the arm length may be shortened to a length that is at least as long as the distance from the center of the filler to the tangent line 116 that is tangential to the outer portions of the conductor pairs (e.g. tangent to a surface of the conductors having the greatest displacement in the direction of the arm, such as the leftmost edges of the left upper and left lower conductor pairs for the left arm, topmost edges of the top left and top right conductor pairs for the top arm, etc.). Reducing the length of the arm to a length smaller than shown but at least as long as this tangent line will reduce the air space 120, but will still ensure a larger air space and more uniform cable than reducing the arm length to a length smaller than the tangent line, as shown in FIG. 1D. As discussed above, having an arm length within this range from the tangent line to the maximum width of a conductor pair results in a cable that is as small as possible without reducing the conductor diameter or width of other components, while retaining substantial uniformity of the cross section of the cable at any point along its longitudinal length.

[0056] Using a non-diameter increasing shield-supporting filler provides an additional benefit, in that the spacing of the shield relative to the conductor pairs may be controlled to a greater degree relative to cables utilizing smaller fillers. This allows for more latitude in other characteristics of the cable, such as lay length of conductor pairs. Specifically, in many implementations, by tuning the air space volume and shield radial proximity, and controlling separation of the shield from conductor pairs, longer lay lengths (or looser twists) may be used for many twisted conductor pairs, reducing insulation thickness, and cable size while still accomplishing the particular electrical requirements for the cable standard.

[0057] FIG. 2C is a cross section of an embodiment of the shield-supporting filler 202a of FIG. 2A. As shown, filler 202a may have a cross-shaped cross section with a plurality of arms 208 radiating from a central point 206 and having a terminal portion 210 having end surfaces 204a-204d. The length of each arm 208 may be longer than twice the diameter of an insulated conductor, or longer than the longest dimension across a twisted pair of conductors, such that each arm extends beyond the pairs and contacts the shield at an end surface 204. In some implementations, each arm may be approximately 40% of the total radius of the cable or greater. For example, in some implementations, each arm may have a length approximately equal to the cable diameter minus the total thickness of any jacket and shield, minus the width of the central portion 206 of the filler.

[0058] FIG. 2D is an enlarged portion of a cross section of another embodiment of the balanced twisted pair cable including a shield-supporting filler with reduced arm or fin length. In the example implementation shown, the left-pointing filler arm 202a is reduced to an intermediate length, greater than a length corresponding to tangent line 116, but less than the length of arm 202a shown in FIG. 2B, such that the shield and jacket can be drawn tighter or collapsed to a smaller diameter than the full diameter 203 (shown in dashed line). In the example implementation of FIG. 2D, upwards and downwards pointing arms of the filler are the same length as shown in the implementation of FIG. 2B for comparison purposes. In many instances, these arms would be similarly shortened.

[0059] Although shown with four arms in a cross-shape, other geometries may be used for the filler to reduce cost while still supporting the shield at a plurality of contact points 204. For example, FIG. 2E is a cross section of another embodiment of a balanced twisted pair cable 200 incorporating a shield-supporting filler 202b with three arms in a T-shape. The filler 202b supports the shield 110 at three contact points 204a-204c rather than four as in FIG. 2A. While the cross section of the cable is less cylindrical than that of FIG. 2A (compare to the circular profile 201 shown in dotted line), being compressed at the top, the performance of the cable may still be sufficient, and may result in a reduced size cable. The cable is also lighter due to the reduced material of the filler. Furthermore, while the conductor pairs at the top of the conductor may be pressed closer together during manufacture due to the tension on the shield, the non-separated pairs may be selected to reduce NEXT effects. For example, this may be done by selecting the pair having the longest lay length (e.g. lay #1) and the pair having the shortest lay length (e.g. lay #4) or second-shortest lay length (e.g. lay #3), or the pair having the shortest lay length (e.g. lay #4) and the pair having the second longest-lay length (e.g. lay #2), to be adjacent and not separated by a filler arm. Different pairs may be selected, with a requirement in many implementations that any adjacent pairs not separated by a filler arm do not have the most similar lay lengths (e.g. not lay lengths #1 and #2; #2 and #3; or #3 and #4, but any other combination). Although specific lengths are not mentioned above, in many implementations, simply organizing the pairs such that similar lengths are not adjacent may help achieve this benefit. In some implementations, adjacent pairs may be selected based on other relationships between the lay lengths (e.g. not integer multiples of a common wave length, etc.).

[0060] Similarly, FIG. 2F is a cross section of another embodiment of a shield-supporting filler 202c having two arms 208 in a line, with two contact points 204a-204b. The conductor pairs on each side of the filler 202c may be selected as above to reduce crosstalk effects (e.g.

[0061] a longest lay length pair and second shortest lay length pair on one side of the filler, and a second longest lay length pair and shortest lay length pair on the other side of the filler). While the cable may be somewhat flatter or oval shaped as a result of tension on the shield during helical wrapping, this may be sufficient for many uses, while attaining substantially reduced effective diameter and weight of the cable.

[0062] Each terminal portion 210 of each arm 208 may be blunt, as shown in the implementations of FIGS. 2A-2F, or may have other shapes. For example, FIG. 2G illustrates a cross section of an implementation of a shield-supporting filler 202d with T-shaped terminal portions 210, resulting in wider contact portions 204a-204b. FIG. 2H similarly illustrates a cross-section of an implementation of a T-shaped shield-supporting filler 202e with three arms, each terminating in a T-shaped terminal portion 210. FIG. 2I illustrates a cross-section of an implementation of a T-shaped shield supporting filler 202f with three arms, each terminating in a trapezoidal or anvil-shaped terminal portion 210.

[0063] Furthermore, each arm does not need to be identical in profile. For example, FIG. 2J illustrates a cross-section of an implementation of a T-shaped shield supporting filler 202g with three arms, in which two arms terminate in L-shaped terminal portions 210, with a third arm terminating in a T-shaped portion 210. Similarly, FIG. 2K illustrates a cross-section of an implementation of a T-shaped shield supporting filler 202h with three arms, with two arms terminating in T-shaped portions 210 and one arm terminating in an anvil shaped portion 210. Terminal portions may thus be anvil-shaped, rounded, T-shaped, L-shaped, blunt, or otherwise shaped. Although shown symmetric, in some embodiments, the terminal portions may have asymmetric profiles. Similarly, although shown flat, in some embodiments, end surfaces of the terminal portions may be curved to match an inner surface of the shield. For example, FIG. 2L illustrates a cross-section of an implementation of a filler having rounded or curved end surfaces of terminal portions 210, 210 , and 210 to provide more continuous contact with an inner surface of a shield.

[0064] Furthermore, the arms may be of different lengths in some implementations, as shown above in the embodiment of FIG. 2D. For example, as shown in FIG. 2K, the bottom arm 208 is shorter than side arms 208. Each arm may still contact and support a tightly wrapped shield, as discussed above. While this may result in a less cylindrical cable, the performance of the cable may be sufficient, and the cable may further have reduced weight and cost relative to a cable with identical arms.

[0065] FIGS. 3A-3C are graphs of attenuation response over frequency for different embodiments of balanced twisted pair cables (specific measured values at each frequency for the different embodiments are listed in the tables of FIGS. 3E-3N). Specifically, FIG. 3A illustrates attenuation over frequency for an embodiment of a balanced twisted pair cable in which a foil shield is not supported by a filler, but instead is wrapped directly over the twisted pairs of conductors with no or minimal intervening air space (e.g. as shown in the example embodiment of FIG. 1D), referred to as foil-over-pairs or FOP. The attenuation response is shown relative to a standard attenuation limit (Limit, shown in dotted line) in dB at each frequency in MHz, defined as:

[00001]$-\left(\left(1.82*\sqrt{\mathrm{frequency}}\right)+\left(0.0091*\mathrm{frequency}\right)+\frac{0.25}{\mathrm{frequency}}\right).$

In other implementations, other standard limits or comparisons may be utilized.

[0066] Similarly, FIG. 3B illustrates attenuation over frequency for an embodiment of a balanced twisted pair cable in which a foil shield or barrier is partially lifted by arms or fins of a filler or separator to an intermediate point, above a tangent line between adjacent conductor pairs, but not to a full diameter of the cable (e.g. as shown in the embodiments of FIG. 2D or 2E), referred to as supported. The standard attenuation limit is shown for comparison purposes. As shown, the supported cable has less attenuation than the FOP cable, particularly at higher frequencies.

[0067] FIG. 3C is a graph illustrating attenuation over frequency for an embodiment of a balanced twisted pair cable in which a foil shield or barrier is over-extended to more easily meet the electrical performance requirements of a specification for the cable, though having a large effective diameter. In such an embodiment, the foil shield or barrier may be in contact with each arm or fin of the filler or separator at a full diameter of the cable (e.g. as shown in the embodiment of FIG. 2A), referred to as over-extended. The standard attenuation limit is shown for comparison purposes. As shown, the over-extended cable has even less attenuation than the FOP or supported cables, particularly at higher frequencies. However, the over-extended cable also has a cross-sectional diameter larger than the FOP or supported cable implementations, and requires more filler material.

[0068] To further highlight the attenuation distinctions between the embodiments, FIG. 3D is a graph illustrating a portion of the graphs of FIGS. 3A-3C within the range of 300 to 600 MHz, with the FOP cable measurements shown as a line with X's; the supported cable measurements shown as a line with triangles; and the over-extended cable measurements shown as a line with squares; and the attenuation limit shown in dotted line. As shown, the supported cable provides an intermediate compromise in attenuation between the FOP cable and the over-extended cable.

[0069] FIG. 4A is a graph of input impedance over frequency for the FOP, supported, and over-extended embodiments of balanced twisted pair cables as discussed above (specific measured values at each frequency for the different embodiments are listed in the tables of FIGS. 4C-4L). While highly variable, on average, the input impedance was measured as slightly lower for FOP embodiments and slightly higher for over-extended embodiments, with supported embodiments being an intermediate compromise. This is particularly evident in the graph of FIG. 4B, which illustrates a 100 MHz band from 50 MHz to 150 MHz of the graph of FIG. 4A, along with linear trendlines (in solid line for FOP, dotted line for supported, and dashed line for over-extended embodiments). As shown, the supported embodiment has less reduction of input impedance than the FOP embodiment, while still reducing cable diameter and material cost.

[0070] FIG. 5A is a graph of power sum attenuation to crosstalk ratio near-end (PS ACRN) over frequency for different embodiments of balanced twisted pair cables (specific measured values at each frequency for the different embodiments are listed in the tables of FIG. 5C-5L). PS ACRN (sometimes written as PS ACR-N) describes the ratio between signal strength reduced by attenuation at the receiver end of a link, sometimes referred to as insertion loss, and near-end crosstalk, which is at its strongest at this point. The larger this ratio is, the higher quality the link is and the more data that can be reliably transmitted via the cable. Various standards including the Cat 6A Ethernet standard (TIA/EIA-568.2-D, incorporated by reference herein) have PS ACRN requirements for cables. As shown, the ratio is lower (smaller-dB values) for FOP embodiments and higher for supported and over-extended embodiments). To clarify this distinction, FIG. 5B is a graph illustrating a portion of the graph of FIG. 5A for the range from 200-600 MHZ, along with linear trendlines (in solid line for FOP, dotted line for supported, and dashed line for over-extended embodiments). The performance for supported embodiments is very similar to over-extended embodiments, while utilizing less filler material, reducing manufacturing cost, weight, and cable diameter.

[0071] Accordingly, the present disclosure addresses problems of cable to cable or alien crosstalk and signal Return Loss by allowing for tightly wrapped shields or barrier tapes without significantly collapsing the cross-sectional geometry of the cable and maintaining a substantially cylindrical profile. Although discussed primarily in in terms of Cat 6A balanced twisted pair cable, shield-supporting fillers may be used with other types of cable including any unshielded twisted pair, shielded twisted pair, or any other such types of cable incorporating any type of dielectric, semi-conductive, or conductive tape. Similarly, although primarily discussed with helically wound shields, in some implementations, cables may be constructed with longitudinal shields, either solely or bound using binders. Shields may include drain wires, either internal or external to the shield in various implementations. In some implementations, shields and/or jackets of any configuration (e.g. helical or longitudinal) may be applied tightly to lock conductors in place against a filler.

[0072] The above description in conjunction with the above-reference drawings sets forth a variety of embodiments for exemplary purposes, which are in no way intended to limit the scope of the described methods or systems. Those having skill in the relevant art can modify the described methods and systems in various ways without departing from the broadest scope of the described methods and systems. Thus, the scope of the methods and systems described herein should not be limited by any of the exemplary embodiments and should be defined in accordance with the accompanying claims and their equivalents.