(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2006/0169478 A1
`Clark
`(43) Pub. Date:
`Aug. 3, 2006
`
`US 20060169478A1
`
`(54) DATA CABLE FOR MECHANICALLY
`DYNAMIC ENVIRONMENTS
`
`(52) U.S. Cl. ........................................................ 174/113 C
`
`(75) Inventor: William T. Clark, Lancaster, MA (US)
`Correspondence Address:
`LOWRIE, LANDO & ANASTASI
`RVERFRONT OFFICE
`ONE MAIN STREET, ELEVENTH FLOOR
`CAMBRIDGE, MA 02142 (US)
`(73) Assignee: Cable Design Technologies, Inc., Leom-
`inster, MA
`s
`11/046,221
`
`(21) Appl. No.:
`
`(22) Filed:
`
`Jan. 28, 2005
`
`Publication Classification
`
`(51) Int. Cl.
`HOIB 700
`
`(2006.01)
`
`
`
`(57)
`
`ABSTRACT
`
`A multi-pair cable including a plurality of twisted pairs of
`insulated conductors, including first and second twisted
`pairs, each having a closing lay length (twist lay length
`measured after the twisted pairs are cabled together with a
`particular cable lay) of less than about 0.6 inches, the
`plurality of twisted pairs being twisted together with a cable
`lay of greater than about three inches to form the cable. In
`Some examples, the multi-pair cable may further comprise a
`separator disposed between the first and second twisted
`pairs. In another example, a ratio between a longest closing
`lay length and a shortest closing lay length in the cable is less
`than 1.65 inches. In another example, the cable further
`includes at least one additional twisted pair of conductors
`having a closing lay length that is greater than about 0.6
`inches, and the cable lay length is less than about four
`inches.
`
`

`

`Patent Application Publication Aug. 3, 2006 Sheet 1 of 4
`
`US 2006/0169478 A1
`
`
`
`F/G, 1A
`(Prior Art)
`
`Patent Application Publication
`
`Aug. 3, 2006
`
`Sheet 1 of 4
`
`US 2006/0169478 Al
`
`
`
`FIG.
`
`1A
`
`(Prior Art)
`
`

`

`
`
`FIG. 1B
`(Prior Art)
`
`Patent Application Publication
`
`Aug. 3, 2006
`
`Sheet 2 of 4
`
`US 2006/0169478 Al
`
`60a
`
`62a
`
`
`
`
`FIG.
`
`1B
`
`(Prior Art)
`
`™™
`
`60a
`
`62a
`
`60b
`
`62b
`
`d2
`
`
`
`
`
`
`FIG.
`
`1¢
`
`(Prior Art)
`
`

`

`Patent Application Publication Aug. 3, 2006 Sheet 3 of 4
`
`US 2006/0169478 A1
`
`
`
`Patent Application Publication
`
`Aug. 3, 2006
`
`Sheet 3 of 4
`
`US 2006/0169478 A1
`
`
`
`Page 4
`
`CommsScope Exhibit 1025
`
`FJO€WIYS 9007 ‘E “SNY UOHLVIQng UOHeoddy jUaeg
`
`TV 8L46910/9007 SO
`
`
`
`

`

`Patent Application Publication Aug. 3, 2006 Sheet 4 of 4
`
`US 2006/0169478 A1
`
`
`
`Patent Application Publication
`
`Aug. 3, 2006
`
`Sheet 4 of 4
`
`US 2006/0169478 Al
`
`
`
`

`

`US 2006/01 69478 A1
`
`Aug. 3, 2006
`
`DATA CABLE FOR MECHANCALLY DYNAMIC
`ENVIRONMENTS
`
`BACKGROUND
`
`0001)
`1. Field of the Invention
`0002 The present invention relates to high-speed data
`communications cables comprising at least two twisted pairs
`of insulated conductors. More particularly, the invention
`relates to high-speed data communications cables that may
`be exposed to force, stress, rough handing and/or other
`disturbances present in mechanically dynamic environ
`mentS.
`0003 2. Discussion of the Related Art
`0004 High-speed data communications cables often
`include pairs of insulated conductors twisted together gen
`erally in a double-helix pattern about a longitudinal axis.
`Such an arrangement of insulated conductors, referred to
`herein as “twisted pairs.” facilitates forming a balanced
`transmission line for data communications. One or more
`twisted pairs may subsequently be bundled and/or bound
`together to form a data communications cable.
`0005. A cable may undergo various mechanical stresses
`during handling and use. For example, cables may be
`exposed to rough handling during installation of a structured
`cabling architecture for a local area network (LAN), during
`cable pulling and tying, etc. In addition, cables may be
`employed in various industrial settings wherein the cable is
`likely to be subjected to often rigorous motion, various
`mechanical stresses such as bending and twisting, and/or
`general rough handling during ordinary use.
`0006. One example of relatively harsh treatment of cables
`occurs in automatic cable dispensing devices. In order to
`facilitate cable deployment and/or installation, a cable may
`be packaged and distributed in a container or housing having
`various mechanical features that automatically dispense
`cable during installation. Such housings are generally desir
`able with respect to simplifying and expediting cable
`deployment. However, the automatic features of such
`devices often apply forces and various mechanical stresses
`to the cable during operation. Such relatively harsh treat
`ment may alter the configuration and/or arrangement of the
`twisted pairs making up the cable.
`0007. The Telecommunications Industry Association and
`the Electronics Industry Association (TIA/EIA) have devel
`oped standards specifying a number of performance catego
`ries that establish requirements for various operating char
`acteristics of a cable. For example, a category 6 cable must
`meet requirements for cable impedance and return loss,
`signal attenuation and delay, crosstalk, etc. A category 6
`cable is generally considered a high performance cable and,
`as such, return loss and crosstalk requirements may be
`particularly stringent.
`0008. The term “return loss” refers to a measure of the
`relationship between the transmitted electrical energy and
`reflected electrical energy along a transmission line (e.g., a
`data communications cable). For example, return loss may
`be measured as the ratio of the signal power transmitted into
`a system (e.g., the power generated at the source end of a
`cable) to the signal power that is reflected. Return loss is
`often indicated in decibel (dB) units. Reflected electrical
`
`energy may have various adverse effects on data transmis
`Sion, including reduced output power, signal distortion and
`dispersion, signal loss (e.g., attenuation), etc. The severity of
`return loss effects may depend on frequency. For example,
`high frequency signals tend to be more sensitive to distortion
`effects associated with return loss. The return loss require
`ments for category 6 cables may therefore be rated in
`connection with transmission signal frequency. Accordingly,
`higher performance cables may be more vulnerable to return
`loss effects caused by rough handling of the cables.
`0009. A variety of factors may contribute to generating
`reflections that affect the return loss of a cable. For example,
`an impedance mismatch between a cable and a load that is
`coupled to the cable may cause reflections that adversely
`affect return loss. Other reflections may stem from unin
`tended variation in cable properties, non-uniformities and/or
`discontinuities along the length of a cable. Mechanical
`stresses on conventional cables in mechanically dynamic
`environments may result in variation in the intended lay
`configuration of the cable which may degrade the cable's
`return loss characteristics such that the cable no longer
`meets the performance requirements of its intended cat
`egory.
`0010 Referring to FIG. 1A, there is illustrated a per
`spective view of a twisted pair of insulated conductors 50.
`Twisted pair 50 may be one of a plurality of twisted pairs
`bundled together to form a data communications cable.
`Twisted pair 50 comprises a pair of conductors 60a and 60b,
`respectively insulated by insulators 62a and 62b. Ideally, the
`two insulated conductors making up twisted pair 50 should
`be in contact or maintain a uniform spacing or air gap along
`the entire twisted length of twisted pair 50. However,
`various factors, such as rough handling and/or a tendency of
`the insulated conductors to untwist may cause Some sepa
`ration between the two conductors at various points along
`the length of the twisted pair. For example, at a length L
`along a longitudinal axis 64 of the twisted pair 50, the
`twisted pair may be positioned as intended with the insula
`tors 62a and 62b in contact with one another. FIG. 1B is a
`cross-sectional diagram of the twisted pair 50 at length L.
`taken along line B-B. As illustrated in FIG. 1B, in such an
`arrangement, respective centers of conductors 60a and 60b
`are separated by a distanced, determined at least in part by
`the diameter of the conductors and the thickness of the
`insulators. This distance is referred to herein as the “center
`to-center distance.”
`0011. A characteristic impedance of twisted pair 50 may
`be related to several parameters including the diameter of
`the conductors 60a and 60b, the center-to-center distance,
`the dielectric constant of insulators 62a and 62b, etc. In
`order to impedance match a cable to a load (e.g., a network
`component), the cable may be rated with a particular char
`acteristic impedance. For example, many radio frequency
`(RF) components may have characteristic impedances of 50.
`75 or 100 Ohms. Therefore, many high frequency cables
`may similarly be rated with a characteristic impedance of 50.
`75 or 100 Ohms so as to facilitate connecting of different RF
`loads. Often, the characteristic impedance is determined
`from the average impedance of the cable based on the
`intended arrangement (i.e., arrangements wherein the insu
`lators are in contact or have a uniform, controlled air gap
`between them), as illustrated at length L in FIGS. 1A and
`1B. However, referring again to FIG. 1A, as discussed
`
`

`

`US 2006/01 69478 A1
`
`Aug. 3, 2006
`
`above, at a length L along the longitudinal axis 64, the
`center-to-center spacing between conductors of the pair may
`separate or compress to some extent such that the insulators
`62a, 62b no longer have the intended spacing due to, for
`example, bending, twisting and/or other rough handling of
`the cable. Accordingly, the center-to-center distance has
`increased to a distanced, as shown in FIG. 1C which is a
`cross-sectional diagram of the twisted pair taken along line
`C-C in FIG. 1A. At some arbitrary length L (see FIG. 1A),
`the twisted pair 50 may have yet another different center
`to-center distance between the two conductors. This varia
`tion in the center-to-center distance may cause the imped
`ance of the twisted pair to vary along the length of the
`twisted pair 50, resulting in undesirable signal reflections
`that affect return loss.
`0012. In addition, when the insulators of a twisted pair
`are not in contact, the dielectric between the two conductors
`includes an amount of air, the amount depending on the
`extent of the separation. As a result, the dielectric compo
`sition of the twisted pair may vary along the longitudinal
`length of the twisted pair, causing further variation charac
`teristic impedance of the twisted pair that may, in turn,
`produce unwanted signal reflections that degrade the return
`loss of the cable.
`
`SUMMARY OF INVENTION
`0013. According to various aspects and embodiments of
`the invention, there is provided a twisted pair cable that may
`be particularly suitable for use in mechanically dynamic
`environments. Such a cable may have one of various lay
`configurations that facilitate stability under force and
`stresses such as bending, cornering, rigorous movement,
`rough handling, etc., that may arise in industrial environ
`ments and/or during installations using various automatic
`cable dispensing devices, as discussed below.
`0014. According to one embodiment, a multi-pair cable
`may comprise a plurality of twisted pairs of insulated
`conductors each having a closing lay length (twist lay length
`measured after the plurality of twisted pairs are cabled
`together with the particular cable lay) that is less than about
`0.6 inches, the plurality of twisted pairs of insulated con
`ductors including a first twisted pair and a second twisted
`pair, and the plurality of twisted pairs may be twisted
`together with a cable lay to form the multi-pair cable, the
`cable lay being greater than about 3 inches. In some embodi
`ments, the multi-pair cable may further comprise a separator
`disposed between the first twisted pair and the second
`twisted pair.
`0015. In one example, a ratio between a longest closing
`lay length and a shortest closing lay length in the cable is less
`than 1.65 inches. In another example, the multi-pair cable
`further comprises at least one additional twisted pair of
`insulated conductors having a closing lay length that is
`greater than about 0.6 inches, and the cable lay length is less
`than about four inches.
`0016. According to another embodiment, a multi-pair
`cable comprises at least five twisted pairs of insulated
`conductors each having a closing lay length of less than
`about 0.6 inches, the plurality of twisted pairs of insulated
`conductors including a first twisted pair and a second twisted
`pair, wherein the plurality of twisted pairs are cabled
`together with a cable lay length to form the multi-pair cable,
`
`the cable lay length being greater than about seven inches.
`In one example, the multi-pair cable further comprises at
`least one additional twisted pair of insulated conductors
`having a closing lay length that is greater than about 0.6
`inches.
`0017 According to yet another embodiment, a multi-pair
`cable comprises a first twisted pair of insulated conductors
`having a first closing lay length, a second twisted pair of
`insulated conductors having a second closing lay length, a
`third twisted pair of insulated conductors having a third
`closing lay length, and a fourth twisted pair of insulated
`conductors having a fourth closing lay length. The multi-pair
`cable also comprises a tape separator disposed among the
`first, second, third and fourth twisted pairs So as to separate
`the first twisted pair from the third twisted pair and arranged
`So as to not separate the first twisted pair from the second
`twisted pair. Each of the first, second, third and fourth
`closing lay lengths are less than about 0.6 inches, and the
`first, second, third and fourth twisted pairs and the tape
`separator are cabled together to form the multi-pair cable
`with a cable lay length that is less than about five inches. In
`one example, a ratio between the first closing lay length and
`the second closing lay length is greater than about 1.4
`inches.
`
`BRIEF DESCRIPTION OF DRAWINGS
`0018 Various embodiments of the invention, and aspects
`thereof, will now be discussed in detail with reference to the
`accompanying figures. In the figures, in which like reference
`numerals indicate like elements,
`0.019
`FIG. 1A is a perspective view of a twisted pair of
`insulated conductors;
`0020 FIG. 1B is a cross-sectional diagram of the twisted
`pair of conductors of FIG. 1A, taken along line B-B in FIG.
`1A:
`FIG. 1C is a cross-sectional diagram of the twisted
`0021
`pair of conductors of FIG. 1A, taken along line C-C in FIG.
`1A and showing separation of the insulated conductors;
`0022 FIG. 2 is a diagram of one embodiment of a
`multi-pair cable employing a separator and having a stable
`lay configuration according to the present invention; and
`0023 FIG. 3 is a diagram of another embodiment of a
`multi-pair cable employing a separator and having a stable
`lay configuration according to the present invention, the
`separator selectively separating some twisted pairs in the
`cable.
`
`DETAILED DESCRIPTION
`0024. Various conventional high performance cables may
`not be usable in mechanically dynamic environments or
`industrial settings due to their Susceptibility to variation in
`the cable's configuration when introduced to various forces
`and mechanical stresses. Moreover, conventional cables
`may be vulnerable to performance degradation during instal
`lation, rough handling and/or other relatively harsh treat
`ment.
`0025. Accordingly, Applicant has recognized and appre
`ciated various lay configurations that facilitate stability
`under force and stresses such as bending, cornering, rigorous
`movement, rough handling, etc., that may arise in industrial
`
`

`

`US 2006/01 69478 A1
`
`Aug. 3, 2006
`
`environments and/or during installations using various auto
`matic cable dispensing devices, etc. The term “lay configu
`ration” as used herein refers to the arrangement of various
`components of a data communications cable. In particular,
`lay configuration refers to the various relationships within a
`cable. Such as the relationships between conductors in a
`twisted pair, between the plurality of twisted pairs in a
`multi-pair cable, and between the plurality of twisted pairs
`and any separators, shields or other materials that may be
`present in the cable. The lay configuration also refers to the
`twist lay, cable lay, closing lay, center-to-center distances
`and pair-to-pair distances of the cable and twisted pairs
`within the cable. The term “closing lay” refers to the twist
`lay length of a pair measured after the twisted pairs are
`cabled together with a particular cable lay, as discussed
`below in reference to equations (1) and (2). The term
`“stability” or “stable as used herein refers to a characteristic
`resistance to variation in an intended lay configuration. In
`particular, a stable lay configuration may be less Vulnerable
`to variation and/or alteration in the intended cable arrange
`ment when Subjected to the various stresses that may arise
`in mechanically dynamic environments.
`0026 Cable manufacturers often rely in part on charac
`teristics of a lay configuration to meet various performance
`requirements set forth in standards such as those developed
`by TIA/EIA. For example, in cables having a plurality of
`twisted pairs, the twist lay and twist direction of the twisted
`pairs may be varied with respect to one another in the cable.
`Varying the twist lays of the plurality of twisted pairs in a
`multi-pair cable may reduce the amount of signal induced by
`one twisted pair in adjacent and/or proximate twisted pairs
`in the cable. That is, varying the twist lay lengths may reduce
`crosstalk between twisted pairs. In addition, the direction of
`the twist may be alternated among the twisted pairs in a
`cable to further reduce the amount of crosstalk between the
`twisted pairs. The plurality of twisted pairs in a cable may
`be, in turn, twisted together about a longitudinal axis of the
`cable. This “cable lay” may help prevent variation in the
`twist lay, pair-to-pair distances, and other undesirable varia
`tion in the lay configuration of a cable that may result from
`bending, cornering, or otherwise mechanically disturbing
`the cable. For example, the twisted pairs of a multi-pair
`cable that are not twisted in a cable lay tend to separate when
`the cable is bent or cornered, which may cause variation in
`pair-to-pair relationships. As discussed in the foregoing, this
`variation may adversely affect the performance of a cable.
`0027. Another consideration of a lay configuration of a
`cable may be the relationship between each twist lay and the
`cable lay. When a cable lay is twisted in the same direction
`as a given pair twist lay (e.g., clockwise twist lay and
`clockwise cable lay), the cable lay tends to “tighten' the
`twisted pairs, that is, it shortens the twist lay length of a
`twisted pair. When a cable lay is twisted in the opposite
`direction of a given pair twist lay (e.g., a clockwise twist lay
`and a counter-clockwise cable lay), the cable tends to
`“loosen the twisted pair, that is, it lengthens twist lay length
`of the twisted pair. Therefore, the cable lay may effect the
`twist lay either by increasing or decreasing the twist lay
`lengths of each twisted pair in the cable. This final pair twist
`lay (after cabling) is referred to herein as the “closing lay.”
`The closing lay of a twisted pair may be determined from the
`reciprocal relationship between twist lay, cable lay and
`closing lay, as shown in equations 1 and 2 below. For a
`twisted pair wherein the cable lay is in the same direction as
`
`the twist lay of the twisted pair, the closing lay of the twisted
`pair is given by:
`
`- = - + -
`Lclosing
`LTP
`Lcable
`
`(1)
`
`where Less is the closing lay of the twisted pair, LTP is the
`lay length of the twisted pair prior to being cabled and L.
`is the cable lay length. Similarly, for a twisted pair wherein
`the cable lay is in the opposite direction as the twist lay of
`the twisted pair, the closing lay of the twisted pair is given
`by:
`
`1
`closing
`
`1
`LTP
`
`1
`cable
`
`(2)
`
`0028. Another consideration of the lay configuration of a
`cable is the relationship between the various pair lays in a
`cable. When adjacent twisted pairs have the same twist lay
`and/or twist direction, they tend to lie within a cable more
`closely spaced than when they have different twist lays
`and/or twist direction. Such close spacing increases the
`amount of undesirable crosstalk which occurs between the
`adjacent pairs. As discussed above, the twist lays of the
`twisted pairs in a multi-pair cable may be varied to prevent
`twisted pairs from aligning and contributing to crosstalk
`between the individual pairs. The extent of alignment that
`results in a multi-pair cable may depend on the range of twist
`lay lengths selected for a cable. In general, the Smaller the
`range, the smaller the difference or delta that can be achieved
`between individual twist lay lengths. The twist lay deltas
`may also affect the amount of crosstalk in a cable, for
`example, Smaller pair lay deltas tend to induce larger signals
`(i.e., increase crosstalk) in adjacent and/or proximate twisted
`pairs generally due to an increased alignment of the twisted
`pairs. One measurement indicative of the range of twist lays
`(and thus of twist lay deltas) is the ratio of the longest twist
`lay length to the shortest twist lay length.
`0029 Applicant has identified and appreciated that
`mechanical stresses on a cable may vary the lay configura
`tion of a cable to the extent that the cable no longer exhibits
`satisfactory operating characteristics for its intended perfor
`mance category, particularly with respect to high perfor
`mance cables. Tests conducted by Applicant indicate that
`conventional lay configurations adapted to provide high
`performance cables may be susceptible to undesirable varia
`tion when exposed to mechanically dynamic environments.
`For example, a cable manufactured to meet category 6
`requirements may no longer perform satisfactorily after
`various mechanical stresses that may occur during installa
`tion, rough handling, and/or use have been imposed on the
`cable.
`0030. In one embodiment, Applicant has recognized that
`twisted pairs having longer twist lay lengths may be more
`Vulnerable to bending, cornering and/or rough handling. In
`particular, in a high performance cable exposed to mechani
`cal stress, the twisted pairs having longer twist lay lengths,
`for example, in a range of about 0.744-0.850 inches (with a
`cable lay of about 5 inches), may fall short of requirements
`
`

`

`US 2006/01 69478 A1
`
`Aug. 3, 2006
`
`of an intended performance category while the twisted pairs
`with shorter twist lay lengths, for example, in a range of
`about 0.440-0.510 inches (with a 5 inch cable lay), may still
`perform satisfactorily. That is, the tighter twists are generally
`more resistant to movement and other mechanical distur
`bances.
`However, while the shorter twist lays may be
`0031
`desirable in resisting separation, the tighter twists may
`require longer manufacturing times and may tend to
`decrease production output. In addition, tighter twists may
`require thicker insulators around the conductors, further
`driving up production costs. Signal attenuation and delay
`may also be adversely affected by reducing the pair lay
`lengths of the twisted pairs in a multi-pair cable. Moreover,
`decreasing the range of pair lay lengths (e.g., by decreasing
`the pair lay lengths of the more vulnerable twisted pairs
`having longer pair lay lengths) may adversely affect twisted
`pair alignment and may increase undesirable crosstalk
`between twisted pairs.
`0032. As described above, a cable may be less vulnerable
`to separation and/or other unintended variation in configu
`ration when the plurality of twisted pairs are twisted together
`in a cable lay. In general, the shorter the cable lay length, the
`more resistant the cable is to separation, particularly with
`respect to pair-to-pair separation, and the less likely the
`cable is to deviate from its intended configuration. However,
`shorter cable lay lengths may increase production time and
`affect the manufacturing costs of producing cable. In addi
`tion, the cable lay effects the underlying pair lays in a cable
`by either increasing or decreasing the pair lay lengths of the
`twisted pairs. Accordingly, the tighter the cable lay, the more
`the individual pair lays will be affected. In addition, in a
`multi-pair cable, Some twisted pairs may have a clockwise
`twist while others may have a counter-clockwise twist. As a
`result, a cable lay may have the effect of tightening some of
`the twisted pairs while loosening others and may bring
`certain twisted pairs into closer alignment, thereby increas
`ing crosstalk. Accordingly, there may be various constraints
`on the cable lay so as to achieve a performance of the cable
`that meets requirements of the intended category.
`0033. In general, the lay configuration of a cable may
`contribute to its performance, stability, and production cost.
`However, the contributions may be often in competition and
`may conflict with one another. For example, tighter cable
`lays may tend to increase stability while increasing produc
`tion costs. Similarly, tighter twist lays may tend to be more
`resistant to dynamic environments but may be more expen
`sive and may adversely affect attenuation and transmission
`speeds. The tighter/shorter twist lays and cable lays tend to
`bunch the twisted pairs close together, resulting in a dense,
`relatively large mass being concentrated in the center of the
`cable which adds stability to the cable, making it less
`Susceptible to changes in the lay configuration that may
`result from rough handling.
`0034) Applicant has determined various lay configura
`tions for providing high performance cables that are gener
`ally resistant to mechanical stresses. In particular, Applicant
`has developed various lay configurations that may be used in
`any number of different cable arrangements to provide
`cables for mechanically dynamic environments (e.g., for
`automatic cable deployments, industrial settings, etc.) while
`maintaining the intended performance category of the cable.
`
`0035. According to one embodiment, a multi-pair cable is
`provided having a lay configuration that facilitates stability
`in mechanically dynamic environments. The lay configura
`tion includes a plurality of twisted pairs arranged Such that
`a cable lay length is greater than 3 inches, a ratio of the
`longest pair lay length of the twisted pairs in the cable to the
`shortest pair lay length of twisted pairs in the cable is less
`than 1.65, and each of the plurality of twisted pairs has a
`closing lay length less than 0.6 inches. Such a cable is
`capable of meeting category 6 performance requirements in
`Some mechanically dynamic environments. It is to be appre
`ciated that these numbers are provided as one specific
`example of a lay configuration that facilitates stability,
`however, the invention is not limited to the specific values
`given herein. Those of skill in the art may recognize that
`other configurations may be advantageous and will appre
`ciate possible modifications to the examples described
`herein.
`0036) One example of a lay configuration according to
`one embodiment of the present invention that meets the
`requirements of a generally stress resistant cable is presented
`for illustration. In this example, the cable comprises four
`twisted pairs that are cabled together with a cable lay of
`about 5 inches. The closing twist lay lengths for each of the
`four twisted pairs are shown in Table 1.
`
`TABLE 1.
`
`Twisted Pair
`
`Twist Lay Length
`(inches)
`
`1
`2
`3
`4
`
`O.365
`O.S4O
`O412
`0.587
`
`0037. In one embodiment, the above example may pro
`vide a stable lay configuration for a cable meeting the
`requirements set forth by performance category 6. Accord
`ingly, the above example and various other arrangements
`may be well suited for providing category 6 or above rated
`cables intended for use in industrial settings, deployed from
`any of various automatic dispensing devices, and/or for use
`in circumstances or environments wherein a high perfor
`mance cable is expected to undergo relatively harsh treat
`ment. However, the invention is not limited to cables pro
`vided for such uses.
`0038. Many high performance cables employ some form
`of separator between the individual twisted pairs in a cable
`for isolation to further reduce crosstalk. Examples of such
`separators include cross-web separators such that those
`described in U.S. Pat. No. 6,074,503. Separators may also be
`arranged Such that only certain pairs are separated from one
`another. U.S. Pat. No. 6,570,095 describes various config
`urable separators that facilitate relatively simple provision of
`any number of desirable arrangements of separators for
`separating twisted pairs in a multi-pair cable. The two
`above-identified patents are herein incorporated by refer
`ence in their entirety, and any configurations and arrange
`ments described therein can be used in cables having lay
`configurations described herein.
`0039 Separators may be manufactured from various ther
`moplastics such as polyolefin. In plenum rated cables (i.e.,
`
`

`

`US 2006/01 69478 A1
`
`Aug. 3, 2006
`
`cables that have satisfied various burn requirements such as
`those established by the Underwriters Laboratory (UL)),
`separators are often manufactured from fluoropolymer mate
`rial such as fluoro ethylene propylene (FEP) due to the
`generally desirable burn and Smoke characteristics of fluo
`ropolymers. Separators may be fabricated to either be con
`ductive or non-conductive. For example, a generally non
`conductive separator may be made conductive if desired by
`adding a conductive material Such as ferric powder or
`carbon black.
`0040 Separators are often provided in higher perfor
`mance cables, such as cables meeting requirements of per
`formance category 6 and above, to facilitate providing a
`cable that meets or exceeds the various operating require
`ments, such as crosstalk, of the intended performance cat
`egory. However, the various methods of providing separa
`tors tends to make a cable more Vulnerable to mechanical
`stresses, dynamic or pressure impinging environments, etc.
`This may be due, in part, to loss of pair-to-pair physical
`contact as well as loss of a Substantial ground plane in the
`cable core that is usually inherent in cable designs not using
`internal separators. The magnitude of any non-desirable
`effects may vary by the type of separator used and the degree
`to which some or all of the pars are separated. There is a
`need for a high speed cable that uses a separator (to meet, for
`example, crosstalk specifications) and that is resistant to
`non-desirable effects that may be caused by rough handling
`of the cable (such as cable pulling, installation, cable tying
`etc.).
`Referring to FIG. 2, there is illustrated a cross
`0041
`section of a cable 70 having a cross or “+” shaped separator
`72. Separator 72 forms spaces or channels 74a-74d for
`respective twisted pairs 50a-50d of the cable. While sepa
`rator 72 may reduce crosstalk between the twisted pairs,
`immediate contact between twisted pairs 50a-50d is effec
`tively eliminated. As discussed above, pair-to-pair contact
`may provide added stability and resistance to movement and
`variation within the cable. Accordingly, cables employing
`one more separators may be more Vulnerable to variation in
`lay configuration when exposed to mechanically dynamic
`environments.
`0042. In particular, separator 72 may not perfectly con
`form to the twisted pairs such that air gap may exist within
`each channel. These air gaps may allow the twisted pairs
`additional freedom of movement and may exacerbate twist
`separation and other variations in the lay configuration that
`may result when the cable is handled roughly or undergoes
`mechanical stresses. Furthermore, air gaps may affect the
`pair-to-pair relationship and may cause further undesirable
`variation in the lay configurations of the twisted pairs. In
`addition to the general loss of stability, separators may also
`disturb the ground plane provided by the individual conduc
`tors that is inherent in cable designs that do not include
`internal separators. These factors may generally contribute
`to cables being more sensitive to mechanical stre