US3622683A

US3622683A - Telephone cable with improved crosstalk properties

Info

Publication number: US3622683A
Application number: US778073A
Authority: US
Inventors: Walter L Roberts; Frederic N Wilkenloh
Original assignee: Superior Continental Corp
Current assignee: SUPERIOR TELETEC TRANSMISSION PRODUSTS Inc A Corp OF; Superior Essex Inc; Superior Continental Corp
Priority date: 1968-11-22
Filing date: 1968-11-22
Publication date: 1971-11-23
Anticipated expiration: 1988-11-23
Also published as: DE6945245U; DE1958603A1; GB1289554A; IL32985A0; GB1289553A; BR6912448D0; IL32985A; FR2023912A1

Abstract

Disclosed herein is an economical telephone cable structure and method of making same, such cable structure possessing improved crosstalk properties. A plurality of insulated electrical conductors (pairs), of an otherwise conventional telephone cable design are divided into at least two portions by plastic-coated metal foil strip or tape. Measurements between pairs, divided by this plastic-coated metal foil, of unwanted energy transferred from one conductor to another by means of mutual inductive, capacity, or conductive coupling (crosstalk), shows greatly improved properties over undivided cable pairs or divided cable pairs of prior art. By dividing electrical conductor telephone pairs within a telephone cable structure with plastic-coated metal foil, the crosstalk properties are so vastly improved that a greater spacing between repeaters can be designed into a telephone cable system, as compared to a cable system employing prior art divided or undivided cable pairs.

Description

United States Patent [72] Inventors Walter L. Roberts Hickory; Frederic N. Wllkenloh, Conover. both of N.C. [21] Appl. No. 778.073 [221 Filed Nov. 22. 1968 I45] Patented Nov. 23, 1971 [73] Assignee Superior Contlnentel Corporation Hickory, N.C.

(54] TELEPHONE CABLE WITH IMPROVED CROSSTALK PROPERTIES 37 Claims, 24 Drawing Figs.

[52] U.S. Cl. 174/36, 174/25. 174/27. 174/103. 174/105. 174/107. 174/113. 174/115 [51] lnt.Cl. HOIblI/Oti [50] Field 01 Search 174/102-109. 113.115, 116, 1l9,36,27.25.26

[56] References Cited UNITED STATES PATENTS 311.174 1/1885 Clark 174/105 3,233,036 2/1966 .lachimowicz.... 174/107 3,306,971 2/1967 Olson et a1 174/119 FOREIGN PATENTS 105,876 1 H1937 Australia 174/36 1,120,216 7/1956 France 174/113 775.84! l/1935 France 174/36 657.411 3/1938 Germany 174/36 314.564 7/1929 Great Britain 174/36 434.855 9/1935 Great Britain 174/36 449.582 6/ l 936 Great Britain l74/l03 995,582 6/1965 Great Britain 174/23 367,814 2/1932 Great Britain 174/36 OTHER REFERENCES Communications News. Apr.. 1969 M. C. Biskeborn & D. P. Dobbin, Jelly Blend Waterproofs Cable. Bell Laboratories Record. March 1969, p. 71, 72. 73. 74. 75. Copy in 174- 23 Primary Examiner-Lewis H. Myers Assistant Examiner-A. T. Grimley Almrney- Roy B. Mol'fitt ABSTRACT: Disclosed herein is an economical telephone cable structure and method of making same. such cable structure possessing improved crosstalk properties. A plurality of insulated electrical conductors (pairs). of an otherwise conventional telephone cable design are divided into at least two portions by plastic-coated metal foil strip or tape. Measurements between pairs, divided by this plastic-coated metal foil. of unwanted energy transferred from one conductor to another by means of mutual inductive. capacity, or conductive coupling (crosstalk). shows greatly improved properties over undivided cable pairs or divided cable pairs of prior art. By dividing electrical conductor telephone pairs within a telephone cable structure with plastic-coated metal foil, the crosstalk properties are so vastly improved that a greater spacing between repeaters can be designed into a telephone cable system, as compared to a cable system employing prior art divided or undivided cable pairs.

PATENTEDuuv 23 um 3,622,683

sum 01 0F 15 FIG. 2

INVENTORS WALTER L ROBERTS FREDERIC N. WILKENLOH ATTORNEY PAIENTEnwuv 23 Ian NNNNNNN RS WILKENLOH PATENTEBunv 2a l97| sum 03 u IIIIIIIIIIIII NG m\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ so IIIIIIIIIIIII NG EEEEEEEEEEEEEEEEE OH IIIIIIIIIIIII NG PATENTEUNnv 23 Ian SHEET 05 0F 15 INVENTORS WALTER L. ROBERTS FREDERIC N. WlLKENLOH ATTORNEY PATENTEDNUV 23 I91: 7 3,622,683

SHEET 08 0F 15 PLASTIC COVERIN POLYETHYLENE GREASE INVENTORS WALTER L. ROBERTS FREDERIC WlLKENLQH ATTORNEY PATENTEDNHV 2 I9?! 3. 622,683

sum 07 or 15 PLASTIC COVERING POLYETHYLENE GREASE INVENTORS WALTER L. ROBERTS FREDERIC N. WILKENLOH ATTORNEY A $1 35 PLASTIC JACKET PLASTIC TAPE PLASTIC COVERING METAL FOIL POLYETHYLENE GREASE L FIG. l2

INVENTORS WALTER L.ROBERTS FREDERIC N. WILKENLOH ATTORNEY PATENTEUNUV 23 I97! 8,622,683

PLASTIC COVERING POLYETHYLENE GREASE FIG. l3

COVERING POLYETHYLENE GREASE INVENTORS WALTER L. ROBERTS Fl G. 14 FREDERIC N WILKENLOH ATTORNEY PATENTEDNUV 2 l8?! 3.622.683

SHEET

10 or 15 POLYETHYLENE GREASE INVENTORS WALTER L. ROBERTS FREOERIC N. WlLKENLO-l ATTORNEY PATENTEUNUV 23 Ian SMET 11 [1F 15 PLASTIC JACKET PLASTIC COVERING POLYETHYLENE GREASE INVENTORS WALTER LROBERTS FREDERIC N. WILKENLOH ATTORNEY PATENTEU 23 3, 622,683

SHEET 12 [1F 1 5 METAL SHIELD PLASTIC l 1 K 3 q Chi FIG. [7

POLYETHYLENE GREASE PLASTIC COVERING FIG. l9

METAL FOIL e METAL LASTIC COVERING INVENTORS WALTER L. ROBERTS FREDERl/w WILKENLOH "7 0 m ATTORNEY PATENTEuuuv 23 l97l SHEET FIG. 22

INVENTORS WALTER L. ROBERTS FREDERIC N. WILKENLOH FIG. 23

INVENTORS WALTER L. ROBERTS FREDERIC N. WILKENLOH AT TORNE Y PAIENTEDunv 23 Ian sum 15 OF 15 \PRIOR ART CABLE 600 800 I000 I200 I400 FREQUENCY (KHz) O O O p (D ID INVENTORS WALTER L. ROBERTS FREDERIC N. WILKENLOH TELEPHONE CABLE WITH IMPROVED CROSSTALK PROPERTIES DETAILED DISCLOSURE This invention relates to multiconductor cables and has particular reference to arrangements for shielding certain of the conductors of such a cable from other conductors of the cable. In order to transmit currents of the same frequency in both directions within the same cable, more particularly when the currents to be transmitted are of carrier frequencies, it is desirable that the conductors used for transmitting in one direction be shielded (electrically) from those transmitting in the opposite direction. Accordingly, it is the purpose of this disclosure, to show how to arrange the conductors of a cable into two concentric groups, with a shield between the two groups of conductors. In such an arrangement of a cable, those conductors on one side of the shield may all be used for transmitting carrier frequencies in one direction, while the returned channels for transmission in the opposite direction will be applied to the conductors on the other side of the shield. The shield has the efiect of reducing so called near end" crosstalk since the weak attenuated currents coming in at a repeater point are in a compartment of the cable electri cally shielded from a large amplified current entering the conductors in the other compartment of the cable. The instant invention also envisions and incorporates the concept of two distinct bundles of conductors inside a cable structure, one such bundle being electrically shielded from the other bundles and neither one of the aforesaid bundles necessarily being concentric around the other.

In one embodiment, a cable with a shield is formed by arranging a group of conductors into a cylindrical bundle, spirally wrapping or twisting tapes of aluminum foil, either per se or coated with a plastic such as polyethylene terapthalate (Mylar), upon the cylindrical bundle of insulated wires, and then mounting another group of insulated wires, preferably equal in number, outside of the shielding tape in the form of a concentric cylindrical bundle, upon which another sheath of plastic, or other material, is applied in the usual manner.

The prior art has recognized the same problem to which the instant invention only crosstalk and it is interesting to note that Nyquist, US. Pat. No. 1,979,402, (179/78), teaches that the shielding material should be thin tape of soft iron, alternating with layers of copper. Nyquist goes on to teach that while various materials may be used, iron (in particular soft iron) is preferred for one group of the alternating layers. This, according to Nyquist, is so because the product of the permeability by the conductivity of the iron is large, thereby making its attenuating effect large. Furthermore, Nyquist teaches that the ratio of permeability of the iron to its conductivity is quite different from that of the copper or other conductive material, which may be used for the other alternating layers. Such a combination, according to Nyquist, causes electromagnetic wave reflection losses brought about by interfering waves penetrating through the shield. For a sake of completeness and reference, the entire specification of the aforementioned United States patent of Nyquist is incorporated specifically herein by reference.

In passing, it might be well to note that the prior art teaching, concerned with the transmission of carrier energy along telecommunication cable, addresses its shield design solution to the use of alternating layers of different metals, e.g., copper and soft iron. At least one of these two metals is magnetic (soft iron). In contradistinction, the instant invention addressed its solution to the same problem by using alternating layers of a metal and a nonmetal, neither one of which is magnetic. As stated above, the instant invention uses as its shield, an aluminum foil either per se or coated with a plastic, such as polyethylene terapthalate. Furthermore, the prior art teaches that the materials to be used must have electromagnetic properties such that the product of permeability and conductivity should be as large as possible and that the ratio of permeability to conductivity should be as much different as possible from one material to the other. This is not the case in the instant invention where there is used as a shield. an aluminum foil either per se or coated with a plastic.

For the purposes of this disclosure, a foil is defined the same as found on page 18 of the METALS HANDBOOK, Eighth Edition, published by the American Society for Metals, to wit: A foil is a' metal in sheet form possessing a thickness of less than 0.006'inches.

The invention will now be more fully understood from the following descriptions, when read in connection with the accompanying drawing,

FIG. I of which is a cutaway pictorial view of one embodiment of the instant invention, showing two groups of conductors separated by a longitudinally disposed circumscribing foil shield;

FIG. 2 is a pictorial cutaway view of another embodiment of the instant invention, similar to that shown in FIG. 1, wherein the shield between the two groups of electrical conductors is not longitudinally but helically disposed;

FIG. 3 is an additional pictorial cutaway view of one of the embodiments of the instant invention, showing two groups of electrical conductors separated by a shield made from a plurality of tapes helically disposed, the lateral edges of which overlap adjacently lying tapes;

FIG. 4 is a portion of that cable shown in FIG. 2 in a cutaway view, emphasizing the helical seam formed by the overlapping terminal edges of a helically wound tape shield;

FIG. 5 is a cross-sectional view of a metal foil coated on both sides with a plastic, used to shield one group of electrical conductors from another;

FIG. 6 is a cross-sectional view of an uncoated metal foil shield;

FIG. 7 is a cross-sectional view of an embodiment of a foil tape shield showing a metal foil coated only on one side by a plastic;

FIG. 8 is a cross-sectional view of a piece of metal foil shield having a plastic coating that completely surrounds said foil;

FIG. 9 is a cross-sectional view of that cable structure as shown in FIG. I, employing as a shield a metal foil coated on both sides with a plastic;

FIG. 10 is a cross-sectional view of that cable structure as shown in FIG. 3, employing a shield composed of a plurality of tapes made from a metal foil coated on both sides with a plastic, the lateral edges of which overlap adjacently disposed tapes;

FIG. 11 is a cross-sectional view of the cable structure as shown in FIG. I wherein the metal foil shield is completely surrounded by a plastic coating;

FIG. 12, is a cross-sectional view of that cable structure as shown in FIG. 3, wherein a shield composite is shown, made up of a plurality of metal foil tapes each of which is completely surrounded on both sides by a plastic;

FIG. 13 is a cross-sectional view of a cable structure showing four groups of insulated conductors, only two of which are longitudinally circumscribed by a shield made of metal foil coated on both sides with a plastic and the remaining groups being longitudinally circumscribed by a plastic tape;

FIG. 14 is a cross-sectional view of a cable structure the same as that shown in FIG. 13 except that the plastic coating on the metal foil shield or screen completely surrounds the foil screen;

FIG. 15 is-a cross-sectional view of a cable structure the same as that shown in FIG. 14 except that the shield is composed of a plurality of foil tapes, coated on both sides by a plastic, the lateral edges of which overlap adjacently disposed tapes;

FIG. 16 is a cross-sectional view of a cable structure the same as that shown in FIG. 15 except that the plastic coating of the metal foil completely surrounds the foil;

FIG. 17 is a cross-sectional view of a cable structure showing a screen or shield dividing groups of insulated electrical conductors that does not longitudinally circumscribe any group of conductors;

FIG. 18 through 21 inclusive are cross-sectional views of various metal shields used in that cable structure of FIG. 17; FIG. 18 being a metal foil coated on both major surfaces with a plastic; FIG. 19 being a metal foil coated only on one side with a plastic; FIG. 20 being an uncoated metal foil; and FIG. 21 being a metal foil completely surrounded by a plastic coating;

FIG. 22 shows in schematic form, a wire twisting apparatus used to apply the plastic-coated metal foil shield in between first and second groups of electrical conductors;

FIG. 23 is an enlarged diagrammatic view of a rotating die member used to apply the plastic-coated metal foil shield between first and second groups of electrical conductors; and,

FIG. 24 is an exemplary plot of crosstalk values derived from the improved cable structure of the instant invention.

One embodiment of the cable to be considered herein is made up of the usual cylindrical plastic or lead sheath with the conductors arranged in the usual fashion, except that they are separated into two equal or substantially equal but separate concentric groups by means of an essentially cylindrical concentric shield. When a signal is transmitted over any circuit in this cable, it is permissable to consider an electromagnetic field as spreading out from this circuit in the form of a wave motion. This wave reaches other conductors and may induce currents and electromotive forces in other circuits unless they are perfectly balanced. The first of these circuits may be called the disturbing and the other the disturbed circuit. If the disturbing and disturbed circuits are on opposite sides of a shield, it is obvious that the disturbance is reduced due to the attenuation the wave energy undergoes when passing through a shield and such reflections as may occur. This object is achieved in the instant invention by using a piece of metal (copper, aluminum, silver, steel, and etc.) foil, either per se, coated on both sides, coated only on one side, or completely surrounded by a plastic such as polyethylene, polypropylene, or polyethylene terapthalate (Mylar). It is, however, one of the many preferred embodiments of the instant invention to use aluminum foil coated on both sides with a plastic. The reason for this preference is that the instant invention uses the plastic coating of the metal (aluminum) foil as a dielectric to keep unwanted currents [emitting from pinholes in the insulation of individual electrical conductors], from reaching the metallic shield (aluminum foil). It is quite obvious that when a metal foil, coated only on one side, is employed, that the bundle of electrical conductors in nearest proximity therewith is not protected by a dielectric from the electrical conductors, other than that dielectric used as the insulation on the electrical conductors themselves. Thus, there is in this instance a preference for the aluminum foil shield, coated on both sides with the polyethylene terapthalate (Mylar) dielectric.

It is also an embodiment of the instant invention to employ as a shield, a metal foil which is completely surrounded on all sides by a plastic coating, e.g., an aluminum foil, completely surrounded by polyethylene terapthalate (Mylar), polyethylene, polypropolyene, polystyrene or PVC. An aluminum foil, which is coated only on its two major surfaces with a plastic, still has exposed naked aluminum surfaces at the edges thereof. When considering a cable of many miles in length, this amount of exposed conductive metal becomes significant. Therefore, the instant invention takes this into account in one of two ways: the first way is to employ a metal foil which is completely surrounded by plastic. As an example, such a foil would be envisioned as being aluminum with the plastic covering being polyethylene terapthalate (Mylar). Another way to mitigate undesirable electrical properties created by having an exposed surface (edge) of metal to the electrical conductors is to fill that portion of the space created by the plastic-coated metal foil shield not otherwise occupied by the electrical conductors therein with a polyethylene greaselike material. This greaselike material acts as both a dielectric protection, as well as an inhibitor of any subsequent incoming moisture. This particular feature will be more fully discussed later.

Turning now to FIG. 1, the overall general configuration of the cable structure is exhibited by element (1). Shown at (14) is a first group of insulated conductors, the outer peripheral surface thereof being longitudinally circumscribed by a plastic-coated foil shield shown at (15), this foil shield being either uncoated, coated on one or both of its major surfaces as well as completely surrounded by a plastic. Indicated by element (16), is a second group of insulated electrical conductors disposed in an annular fashion on the outermost surface of the plastic-coated metal foil shield l5). Disposed in a longitudinally and circumscribed fashion around the composite formed by the first and second group of insulated electrical conductors (I4) and (16) and the interposed metal foil shield (15) is a polyethylene terapthalate (Mylar) tape shown at (17). Longitudinally circumscribing the tape (17) is a corrugated metal armor tape shown at (18). This metal armor, having a thickness greater than a foil, (18), is a tapelike strip that has been longitudinally folded or wrapped around the plastic tape (17). This particular piece of armor is in a sense an electrical, as well as a mechanical, shield and it can have a plastic, such as polyethylene, firmly adhered to either one or more surfaces thereof. Disposed on the outer most surface of metal shield (18) is a molded plastic sheath (19). This outer most plastic sheath is the customary extruded polyethylene that can be and usually is filled with carbon black.

Shown in FIG. 2 is essentially the same cable structure as that set forth in FIG. I. The overall structure (2) differs from that cable structure (1) only in the respect that the plasticcoated metal foil shield (15) has lateral edges that overlap in a helically rather than a longitudinal fashion. The metal shield (15) of FIG. 1, is longitudinally disposed, the lateral edges of the shield overlapping one another. See 1511]) A further cable structure is shown at (3) in FIG. 3, wherein the difference between structure (3) and (2) being that the shield of element (2) is formed from a plurality of tapes 15b), (15c), and (15d) I rather than a single tape. The lateral edges of the helically disposed tapes overlap adjacently lying tapes. A representative cross-sectional view of this particular cable structure is shown in FIG. 9.

Element (4) of FIG. 4, is a portion of the helically wound tape, as shown in FIG. 2. Here in this drawing, the low number of turns or helical dispositions per linear length is emphasized. As will be remembered, the tape (15) of FIG. 2 was a single tape, and it was helically disposed around the first group of insulated electrical conductors (14). The lateral edges of this tape (15) overlap, forming the seam (14s).

Elements (5), (6), (7), and (8) of FIGS. 5, 6, 7, and 8, respectively, show a cross-sectional view of the particular metal foil tapes, both plastic coated and otherwise, used by the instant invention. Element (5) shows a metal foil (6), coated on both sides with a plastic, whereas element (6) shows an uncoated metal foil shield. Element (7), of FIG. 7, shows a metal foil (6), coated only on one side, with a plastic coating [5 (a) 1. Either one of the embodiments (5), (6), (7), and (8), shown in respective figures, are viable as a shield from both a structural and electrical standpoint. Foil (6) has a thickness between 1 and 5 mils and is generally twice the thickness of plastic coating [5 (a)]. All of elements (5), (6), (7), and (8) of FIGS. 5, 6, 7, 8, as well as 18, 19,20 and 21, can be corrugated to increase its mechanical strength. For the purposes of this disclosure, when reference is made to a shield, other than element (18), an electrical shield is meant. Even though the word shield" has an accepted double meaning, i.e. electrical as well as mechanical (armor) protection, the metal foil shield of the instant invention connote primarily an electrical shield.

Element (9) of FIG. 9, shows a cross-sectional view of that cable structure as depicted in FIG. I. Like numbers of FIG. I also represent like elements in FIG. 9. Here it will be noted that the plastic-coated metal foil shield (15) is coated on its two major surfaces with a plastic; however, it can be seen by element (20), that thin strips of uninsulated metal are exposed to the first and second group of electrical conductors (l4) and (16) respectively. It is quite obvious that pinholes in the electrical insulation of the insulated electrical conductors (14) or ticular plastic-coated metal foil shield is used to separate a (16), or the shield (15),.would allow unwanted electrical first group of insulated electrical conductors (14) from a energy to reach exposed portions (edges) ofthe aluminum foil second group of insulated electrical conductors (16). The shield, through the edges (20) or pinholes in its plastic coatbalance of the cable structure is essentially the same as that ing. From an electrical standpoint, it is desirable to avoid this. 5 shown ,by element (9) of FIG. 9. Here again, that innermost It is also electrically desirable to keep moisture away from the cavity defined by the overlapping plurality of plastic-coated electrical conductors. Thus, the instant invention envisions an metal foil shields (15), (15), and (15"), not otherwise occuembodiment in which a polyethylene greaselike material pied by insulated electrical conductors(14), can be essentially flooding compo n is i p s in th ca ity Created r filled with the same polyethylene grease described in associadefine y h f il hi l n h r i pi y n tion with the description of element (9) of FIG. 9. Also that lated electrical conductors (14). Furthermore, it is also envicavity d fi d between ourer I i tape (17 d h I I sioned that the same polyethylene greaselike material can be ated met l foil hield (15), (15'), and (15"), not otherwise disposed in that cavity created by the plastic-coated metal fOil occupied by insulated electrical conductors (16), can be also shield and Plastic p not Otherwise Occupied y I filled with the polyethylene greaselike material described the insulated electrical conductors 16). Such a polyethylene b I l m nt of FIG, 10, a wa the a e with ele greaselike material is described as an amorphous t (9) f FIG, 9, the e ed metal edge (20) present a polyethylene, having n r g m le gh below problem. Electrical energy escaping through pinholes in the about 10,000 and a ensi y of b l w about 1. namely insulation of the electrical conductors into that uninsulated [0.85] grams per milliliter at C.]. This grease is marketed 20 portion of shield (14) and (16) where there is exposed metal by Dow Chemical Company Of Mi l n Mi h g n, under the foil is electrically undesirable. As was the case with element e ign of Q l n has been tested y the Same (9) of FIG. 9, the polyethylene greaselike material can be used i ment used to test well-known polyethylenes as define here to serve two functions: the first to provide a dielectric inby ASTM Dl238.65T. Essentially the same method as em- [erposed between the exposed metal edge and the insu- Ployed by this ASTM designation was Used to test this 25 lated electrical conductors (16) or (14); and the second to inpolyethylene grea elik materia x ep for slight modificasure the exclusion of water, either in the liquid or vapor state, tions. One such modification was that the extrusion barrel was f h ni f th bI t t e whe th ele tri al heated to 100 C., instead of 125 C., as called for in the aforeonductor are disposed,

mentioned ASTM Specification. This temperature modifica- Element (11) of FIG, 11, how a cro ectional view of 3 tion was necessary because of the viscosity of the polyethylene further embodiment of the instant invention. The cross-secgrease material, i.e., it is chara eri i f hi gr to tional structure of element (11) is essentially the same as elebecome highly fluid when exposed to any high degree of heatment 9) of FIG. 9, except for one specific deviation. It will be Th m l in x (fl r m r ing hi mo ifie noted that in element (9) of H6. 9, there were exposed metal ASTM m h was 10 t0 A 2,160 g 108d (P and foil edges (20). Shield (15) of FIG. 11, does not have any Weight) was used in this modified A TM test. as w ll as n rimetal edges exposed. It will be noted that in FIG. 11, a plasticfice of 0.020 inches. Other data supplied by t e DOW Chemicoated metal foil shield (15), having a cross-sectional similar cal Company on other properties of the polyethylene grease to that as shown by shield (8) of FIG. 8, is employed. Thus, by are as follows: using this particular embodiment, no metal of the plastic foil TABLE L-PROPERTIES OF POLYETHYLENE GREASE GREASE Property Condition Value Power factor 1 to 100 kc Less than 5 10' Pour point Approximately l0 0.

Coefficient of volumetric expansion 25 C 7.3 10- Density 25 0.581 gram per milliliter.

Water absorption (percent) 24 hours at 00% RH 0.01

Mean specific heat to 100 C Less than .53 cal./ C./gm.

By placing the above described polyethylene greaselike shield is exposed at any time to any electrical conductor. This material in the two areas indicated, two functions are served. is not to say, however, that the polyethylene grease used in the The first function is that of interposing a dielectric between structure ofcable (9) or (10) can not also be used here. Either the electrical conductors and the exposed metal edge portion that innermost cavity, not otherwise occupied by insulating (20); the second function is to exclude water, in any form, i.e., conductors (l4), defined by plastic-coated metal foil shield vapor or liquid, from ingressing into that area where the elec- (15), or that cavity defined between the plastic-coated metal trical conductors are situated. In essence, the polyethylene foil shield (15) and plastic tape (17), not otherwise occupied greaselike material is a hydrophobic material, as shown by its by electrical conductor (16), or both, can be essentially filled extraordinary low (less than 0.01 percent) water absorption at with polyethylene greaselike material as previously discussed. 24 hours at I00 percent relative humidity. Thus, by using the Thus it can be seen that in the case of a cable structure like polyethylene grease as discussed, water tight cable can be prothat of element (11), of FIG. 11, the polyethylene greaselike vided. That is to say, the cable using the polyethylene grease material serves basically as a water-repellant substance. How as disclosed, can be directly buried in the ground without the ever, in the case where there are pinholes in both the insulabenefit of pressurization, and remain in service for an intion of the electrical conductors (I4) and (16) as well as the definite length of time without the ingressing of water into the plastic-coated metal foil shield (15), the polyethylene area where the el ctric l con u ors re i a greaselike material serves as a dielectric and keeps unwanted Element 0f 10 Shows h Overall Cross-Sectional 5 electrical energy from being transferred into the shield (15). view of a further embodiment of the instant invention. The Element (12) of FIG. 12 shows a cross-sectional view of a basic difference between the cable (10) of FIG. 10 and cable cable structure essentially the same as element (10) of FIG. (9) of FIG. 9, is that the plastic-coated foil shield (15) is not a 10. The only difierence between element (12) and that of elesingle unitary tape as shown in element (9) of FIG. 9. In this ment (10) of FIG. 10 is that in element (12) a plurality of particular embodiment, the shield (15) is made up ofa pluraliplastic-coated metal foil shields is used, the plastic-coating of ty of tapes, the lateral edges of which overlap adjacently which completely surrounds the metal foil. Generally speakdisposed like tapes. Elements (I5), (15 and (15") show this ing, a plastic foil completely surrounded by an integral coating particular feature with the individual plastic-coated metal foil of plastic material would be available to a manufacturer in esshields having lateral edges in an overlapping relationship with sentially a limited number of tape widths. Therefore, with only each other. As was the case in element (9) of FIG. 9, this para single width availability, such as shown in element (12), a

cable structure configuration can be designed for any size cable core circumference using just one given width of shield tape. Thus, notwithstanding the fact that a plastic-coated metal foil tape comes in only one width and that width is less than the outer peripheral dimension ofa core made up of insulated electrical conductors (14), a plurality of tapes can be used to circumscribe the core, the lateral edges of the individual tapes overlapping adjacently disposed tapes. As was the case with similar cable structures shown in FIGS. 9, l and 11, a polyethylene greaselike material can be disposed in the innermost cavity created by overlapping plastic-coated metal foil shield (15), (15), (15"), not otherwise occupied by electrical conductors (14). Also, in combination with this filled core concept, polyethylene grease can be disposed in that space created by the plastic-coated metal foil shields (I),

(15' (15" and plastic tape (17), not otherwise occupied by electrical conductors (16). Here again, as was the case in element of FIG. 10, the polyethylene greaselike material has the primary function to exclude water from that space where the electrical conductors are disposed. However, it has a secondary function to provide a dielectric between the source of electrical energy, i.e., the electrical conductors (l4) and (I6), and any pinholes or other electrical access to the metal foil ofthe shields (15), and (15").

Shown in FIG. 13, by element (22) is a further embodiment of the instant invention which shows the insulated electrical conductors divided into quad configuration. It is to be understood that like numbers represent like cable components as was shown in previously discussed figures. This exemplary quad is made up of four groups of insulated electrical conductors (I4) and (16). The two groups of insulated conductors shown at (14) are longitudinally circumscribed by shield or screen (15), which in this particular embodiment is made up of a single tape, the lateral edges of which overlap one another. These particular tapes not only have a width that is equal to or greater than the outer peripheral dimension of the cores made up by the insulated electrical conductors (14), but also are made up of a metal foil coated on both sides with a plastic, such as that shown in element (5) of FIG. 5. Making up the balance of the quad configuration are two additional groups of insulated electrical conductors (16). These particular insulated electrical conductors are longitudinally circumscribed by a plastic tape (17a) which in this particular embodiment can be made up of the conventional polyethylene terapthalate (Mylar). Transmission of an electrical signal in a given direction is carried on the insulated conductors (14). Conversely, transmission of electrical signals in opposite or returning direction, is carried over insulated electrical conductors I6).

Polyethylene greaselike material, the same as previously discussed, can be used in this particular embodiment. Here, one has many options as to what particular cavity or combination of cavities that can be filled with the polyethylene grease. Any one or any combination of all of the following cavities can be filled with the polyethylene greaselike material: that cavity defined by the plastic-coated metal foil shield (15), not otherwise occupied by insulated electrical conductors (I4); that cavity defined by plastic tape (17a), not otherwise occupied by insulated electrical conductors (I6); or that cavity defined by plastic tape (I7), not otherwise occupied by insulated electrical conductors (16), plastic tape (17a), insulated electrical conductors (I4), and plastic-coated metal foil shield (15).

Shown in FIG. 14, by element (23) is another embodiment of the instant invention, which shows insulated electrical conductors divided into a quad configuration. Here again, like numbers represent like cable components as was shown in previously discussed figures. This exemplary quad is made up of four groups of insulated electrical conductors (14) and (16), The two groups ofinsulated electrical conductors shown at (I4) are longitudinally circumscribed by a shield or screen (15), which in this particular embodiment is made up ofa single tape as was the case in FIG. I3. This tape has a width that is at least equal to but preferably greater than the outer peripheral dimension of the cores made up by the insulated electrical conductors (I4), and are made up of a metal foil completely coated on all sides with a plastic, such as that shown by element (8) of FIG. 8. Making up the balance of the quad configuration are two additional groups of insulated electrical conductors (16). These particular insulated elcctri cal conductors are longitudinally circumscribed by a plastic tape (17a), which in this particular embodiment can be made up of the conventional polyethylene terapthalate (Mylar). Transmission of an electrical signal in a given direction is carried on the insulated electrical conductors (14). Conversely, transmission of electrical signals in an opposite or returning direction, is carried over insulated electrical conductors I6 Polyethylene greaselike material, the same as previously discussed, can be used in this particular embodiment. Here one has many options as to what particular cavity or combination of cavities that can be filled with the polyethylene grease, Any one or any combination of all the following cavities can be filled with the polyethylene greaselike material: that cavity defined by the plastic-coated metal foil shield (15), not otherwise occupied by insulated electrical conductors (I4); that cavity defined by plastic tape (17a), not otherwise occupied by insulated electrical conductors (16); or that cavity defined by a plastic tape (17), not otherwise occupied by insulated electrical conductors (16), plastic tape (17a), insulated elec trical conductors (l4), and plastic-coated metal foil shield (15).

Shown in FIG. 15, by element (20) is another embodiment of the instant invention, which shows insulated electrical eonductors divided into a quad configuration. Like numbers represent like cable components as was shown in previously discussed figures. This exemplary quad is made up of four groups of insulated electrical conductors (l4) and (16). The two groups of insulated electrical conductors shown at (14) are longitudinally circumscribed by a shield or screen (I5), which in this particular embodiment is made up of a plurality of tapes. These particular tapes have a width that is less than the outer peripheral dimension of the cores made up by the insulated electrical conductors (l4), and are a metal foil and coated on both sides with a plastic, such as that shown in element (5), FIG. 5. Making up the balance of the quad configuration, are two additional groups of insulated electrical conductors (I6). These particular insulated electrical conductors are longitudinally circumscribed by a plastic tape 1711), which in this particular embodiment can be made up of the conventional polyethylene terapthalate (Mylar). Transmission of an electrical signal in a given direction is carried on the insulated electrical conductors (14). Conversely, transmission of electrical signals in an opposite or returning direction, is carried over insulated electrical conductors (16).

Polyethylene greaselike material, the same as previously discussed, can be used in this particular embodiment. Here, one has many options as to what particular cavity or combination of cavities that can be filled with the polyethylene grease, any one or any combination of all of the following cavities can be filled with the polyethylene greaselike material: that cavity defined by the plastic-coated metal foil shield (I5), not otherwise occupied by insulated electrical conductors (14); that cavity defined by plastic tape not otherwise occupied by insulated electrical conductors (16); or that cavity defined by plastic tape (17), not otherwise occupied by insulated electrical conductors (16), plastic tape (17a), insulated electrical conductors (I4), and plastic-coated metal foil shield (15).

Shown in FIG. 16, by element (21) is another embodiment of the instant invention, which shows insulated electrical conductors divided into a quad configuration. Like numbers represent like cable components as was shown in previously discussed figures. This exemplary quad is made up of four groups of insulated electrical conductors (l4) and (16). The two groups of insulated electrical conductors shown at (I4) are longitudinally circumscribed by a shield or screen (15), which in this particular embodiment is made up of a plurality of tapes. These particular tapes have a width that is less than

Claims

1. A cable comprising: a. a cable core having first and second groups of insulated electrical conductors; b. a metal foil shield covered on both surfaces with a plastic, said metal foil shield peripherally surrounding said first group of electrical conductors but not said second group of electrical conductors; c. a plastic tape peripherally surrounding said second group of electrical conductors, but not said first group of electrical conductors, and d. a plastic sheath circumferentially surrounding said first and second groups of electrical conductors.

2. The cable defined in claim 1, wherein the plastic covering both surfaces of said metal foil shield also covers the longitudinally extending edges of said metal foil shield.

3. A cable as defined in claim 1, wherein a further shield is made of metal and circumferentially surrounds said metal foil shield and said plastic tape.

4. A cable as defined in claim 1, wherein that space not otherwise occupied by insulated electrical conductors inside of said metal foil shield is filled essentially with polyethylene grease-like material, having an average molecular weight below about 10,000 and a density at 25* C. of about 0.85 grams per milliliter.

5. A cable as defined in claim 1, wherein that space circumferentially surrounded by said plastic tape and not otherwise occupied by said second group of insulated electrical conductors is essentially filled by a polyethylene grease-like material, having a molecular weight below about 10,000 and a density of 25* C. of about 0.85 grams per milliliter.

6. A cable as defined in claim 1, wherein an additional plastic tape circumferentially surrounds both said first and second groups of insulated electrical conductors.

7. A cable as defined in claim 6 wherein a further grease-like is made of metal and circumferentially surrounds said additional plastic tape. grease-like

8. A cable as defined in claim 6, wherein a polyethylene greaselike material essentially fills that space circumferentially surrounded by said additional plastic tape and not otherwise occupied and circumferentially surrounded by said metal foil shield and the first mentioned one of said plastic tapes, said polyethylene greaselike material having a molecular weight bElow about 10,000 and a density at 25* C. of about 0.85 grams per milliliter.

9. A cable as defined in claim 6, wherein that space circumferentially surrounded by said additional plastic tape and not otherwise occupied by said first shield, the first-mentioned one of said plastic tapes, and said first and second groups of electrical conductors is essentially filled by a polyethylene grease-like material, having a molecular weight below about 10, 000 and a density at 25* C. of about 0.85 grams per milliliter.

10. A cable comprising: a. a core made up of a plurality of insulated electrical conductors; b. a shield circumscribing said core, said shield being made of a metal foil that is coated on both sides by plastic; c. a second plurality of insulated electrical conductors defining an annular core distributed around the outermost surface of said shield; d. an integral plastic tube peripherally surrounding the composite of said first and second plurality of electrical conductors and said shield, and e. a plastic tape circumferentially surrounding said second plurality of electrical conductors.

11. A cable comprising a tubular covering being formed with an inner peripheral surface that delimits a core-receiving cavity, a tubular metallic shield forming a part of said covering, a core made up of a plurality of electrically insulated conductors received in said core-receiving cavity and nested within said tubular metallic shield, and integral metallic crosstalk shield disposed within said core-receiving cavity and extending longitudinally in said core, said crosstalk shield extending between circumferentially spaced-apart regions located on said inner peripheral surface of said tubular covering to separate said conductors into a plurality of longitudinally extending groups, each group being delimited by said crosstalk shield and a portion of said inner peripheral surface, the transverse cross section of said crosstalk shield having first and second terminal portions and an intermediate portion extending between and integrally joined to said terminal portions, said first and second terminal portions circumferentially extending around portions of the outer periphery of said core and having respective spaced-apart free ends that lie on opposite sides of that plane in which said intermediate portion lies, and said terminal portions being in close proximity with said inner peripheral surface and said metallic tubular shield.

12. The cable defined in claim 11 wherein said terminal portions seat against said inner peripheral surfaces.

13. The cable defined in claim 11 wherein said crosstalk shield has a serpentine-shaped configuration in transverse cross section.

14. The cable defined in claim 11 wherein said crosstalk shield has an S-shaped configuration in transverse cross section.

15. The cable defined in claim 11 wherein said crosstalk shield is made of metal foil.

16. The cable defined in claim 11 wherein said crosstalk shield is a metal foil coated only on one side with a plastic.

17. The cable defined in claim 11 wherein said crosstalk shield is made of metal foil, and wherein both sides and the longitudinal edges of said crosstalk shield are completely covered with a plastic.

18. The cable defined in claim 11 wherein said crosstalk shield is the only crosstalk barrier between said groups, and wherein crosstalk shield is formed in transverse cross section only with said first and second terminal portions and said intermediate portion.

19. The cable defined in claim 11 wherein said crosstalk shield is made of non-magnetic electrically conductive material.

20. The cable defined in claim 19 wherein said crosstalk shield is made of metal foil.

21. The cable defined in claim 19 wherein said metal foil is coated on at least one side with plastic.

22. The cable defined in claim 19 wherein said metal foil is coated on both sides with a plastic.

23. The cable defiNed in claim 11 wherein the space in said cavity, not otherwise occupied by said conductors and said crosstalk shield, is essentially filled with a greaselike material.

24. The cable defined in claim 23 wherein said crosstalk shield is made of metal foil.

25. The cable defined in claim 11 wherein the space in said cavity, not otherwise occupied by said conductors and said crosstalk shield, is essentially filled with a polyethylene greaselike material having an average molecular weight below about 10,000 and a density at 25* C. of about 0.8 grams per milliliter.

26. The cable defined in claim 11 wherein the width of said crosstalk shield is less than the outer peripheral circumference of said core.

27. The cable defined in claim 26 wherein the space in said cavity, not otherwise occupied by said conductors and said crosstalk shield, is filled with a greaselike material.

28. The cable defined in claim 26 wherein said crosstalk shield has an S-shaped configuration in transverse cross section.

29. The cable defined in claim 26 wherein said tubular covering further includes a plastic tape nested inside of said tubular shield and defining said inner peripheral surface.

30. The cable defined in claim 29 wherein said terminal portions are spaced from said tubular shield only by said plastic tape.

31. The cable defined in claim 30 wherein said terminal portions seat against said inner peripheral surface.

32. The cable defined in claim 29 wherein said crosstalk shield is made of metal foil.

33. The cable defined in claim 32 wherein said foil is non-magnetic.

34. The cable defined in claim 33 wherein said foil is covered on at least one side with a plastic.

35. The cable defined in claim 33 wherein said foil is covered on both sides with a plastic.

36. The cable defined in claim 29 wherein said tubular covering further includes a tubular plastic sheath, said tubular shield being nested within said tubular plastic sheath.

37. A cable comprising: a. a cable core having first and second groups of insulated electrical conductors; b. a metal foil shield peripherally surrounding said first group of electrical conductors but not said second group of electrical conductors; c. a plastic tape peripherally surrounding said second group of electrical conductors, but not said first group of electrical conductors, and d. a plastic sheath circumferentially surrounding said first and second groups of electrical conductors.