US3865971A

US3865971A - Submarine coaxial cables

Info

Publication number: US3865971A
Application number: US386284A
Authority: US
Inventors: Denroku Kumagai; Gen Marubayashi; Kishio Arita; Shugo Kubo; Goro Yamauchi; Toshio Takahashi; Toshihiko Sato
Original assignee: Nippon Telegraph and Telephone Corp
Current assignee: Nippon Telegraph and Telephone Corp
Priority date: 1972-08-08
Filing date: 1973-08-07
Publication date: 1975-02-11
Anticipated expiration: 1992-02-11
Also published as: DE2340173A1; FR2195828B1; DE2340173B2; GB1448736A; FR2195828A1

Abstract

There is provided a submarine coaxial cable in which both of the inner and outer conductors or at least the inner conductor, is made of a conductive material having a lower temperaturecoefficient of resistivity than that of annealed pure copper. The change of attenuation with respect to the temperature of the submarine coaxial cable may be considerably decreased.

Description

United States Patent [191 Kumagai et a1.

[ SUBMARINE COAXIAL CABLES [75] Inventors: Denroku Kumagai, Tokyo; Gen

Marubayashi, Mito; Kishio Arita, Mito; Shugo Kubo, Mito; Goro Yamauchi, Mito; 'Toshio Takahashi, Mito; Toshihiko Sato, Tokyo, all of Japan {73] Assignee: Nippon Telegraph and Telephone Public Corporation, Tokyo, Japan 22 Filed: Aug. 7, 1973 21 Appl. No; 386,284

[30] Foreign Application Priority Data v Aug. 8, 1972 Japan 47-79241 Sept. 1, 1972 Japan.... 47-87624 Sept. 1, 1972 Japan.... 47-87625 Sept. 1, 1972 Japan.... 47-87626 Sept. 1, 1972 Japan 47-87627 [52] US. Cl. 174/102 R, 174/107, 174/126 R, 174/128 [451 Feb. 11,1975

51 int. Cl. 1101b 7/18 [58] Field of Search 174/102 R, 102 A, 107, 174/126 R, 126 CP, 128; 333/96, 81 A, 97 S; 178/45 [56] References Cited UNITED STATES PATENTS 2,337,556 12/1943 Hosking: 174/102 A 2,831,921 4/1958 Morgan 333/96 X 2,924,795 2/1960 Black et al 333/96 2,929,034 3/1960 Doherty 333/96 X 3,569,610 3/1971 Garner et a1. 174/102 R Primary Examiner-Arthur T. Grimley [57] ABSTRACT There is provided a submarine coaxial cablein which both of the inner and outer conductors or at least the inner conductor, is made of a conductive material having a lower temperature-coefficient of resistivity than that of annealed pure copper. The change of attenuation with respect to the temperature of the submarine coaxial cable may be considerably decreased.

12 Claims, 9 Drawing Figures ATENIEmIBnim-s v 3.865 971 SHEET 10F 8 INSULATOR FIG 2 ATTENUYATION (db e 5 lb 5b lo'o FREQUENCY(MH2) THE GRAPH ILLUSTRATING THE RELATION BETWEEN THE FREQUENCY AND THE AT' TENUATION OF THE SUBMARINE CABLE.

Z /XTENTEU FEB] 1 IQYS sum 2 or s FIG. 3

A: MATTHIESSEN'S RULE b-f CONDUCTIVE MATERIALS OF THE INVENTION O Y O 4 L/ll TEMPERATURE-COEFFICIENT OF RESISTIVITY (I/C) THE GRAPH ILLUSTRATING THE RELATION BETWEEN MATHIESSEN'S'RULE AND THE ELECTRICAL PROPER- TIES OF THE CONDUCTIVE MATERISLS PATENTEDFEBHIQTS 3865,97].

SHEET 3 OF 8 FIG. 4

o PURE COPPER b 3 0.2% THERMISTOR CU ELECTRICAL RESIST-IVITY LSl-Cm) I I I I -20 0 20 4b 60 so TEMPERATURE(C) THE GRAPH ILLUSTRATING THE CHANGE OF RESISTIVITY WITH TEMPERATURE OF THE CONDUCTIVE MATERIAL (0.2% THERMISTOR-Cu) I T'fCENTEU T551 71975 SHEET u 0F 8 FIG. 5

O: PURE COPPER b 0.2% FERRlTE-CU EOEO 22. .l

TEMPERATURE (c) THE GRAPH ILLUSTRATING THE CHANG WITH TEMPERATURE OF THE CON (0.2% FERRlTE-CU) E OF RESISTIVITY DUCTIVE MATERIAL PMMEU E 1865971 SHEET 5 OF 8 'g. O1 PURE COPPER b 0.2% MgO -Cu 3 I *1 2 2.0- U) 6 i I5- E |.0- l-v 0 LL! l LLl l l l 1 -26 0. 2b 40 6O 8O TEMPERATURE (c THE GRAPH ILLUSTRATING THE CHANGE OF RESISTIVITY WITH TEMPERATURE OF THE CONDUCTIVE MATERIAL 0.2% MgO-Cu) I WEE TEflFEBH-IBYS SHEET 6 OF 8 FIG. 7

0 RuRE COPPER b 0.5% TiC-Cu EQ QE E ERE 3258 5 TEMPERATURE (C) THE GRAPH ILLUSTRATING THE CHANGE OF RESISTIVITY WITH TEMPERATURE OF THE CONDUCTIVE MATER IAL (0.5 TiC-Cu) mam FEB] 1 I975 sum 70F a FIG. 8

ELECTRICAL RESISTIVITY m-cm) I I I l -2o 0 2fo -40 6O 8O TEMPERATURE(C) THE GRAPH ILLUSTRATING THE CHANGE OF RESISTIVITY P/Vlglj INEMPERATURE OF THE CONDUCTIVE MATERIAL I. o i-Cu -CU) P/IIEIITEU FEBI I I975 sum 8 OF 8 FIG. 9

- FREQUENCY (MHZ m m O O O O X THE GRAPH ILLUSTRATING THE RELATION BETWEEN THE FREQUENCY ANDTHEATTENUATION OF THE CABLE IN ACCORDANCE WITH THE INVENTION BACKGROUND OF THE INVENTION The present invention relates to a submarinecoaxial cable in which an inner conductor or both inner and outer conductors are made of a conductive material having a low temperature-coefficient of resistivity.

Shallow sea cable transmission systems have been recently watched with much interest because the cable laying speed is faster, the cable manufacturing cost is less expensive and the operation is more reliable than land cable system. However the problem is that the repeaters are more expensive than those used in the land cable system. Especially when the transmission band is higher than 10 MHz, the repeaters must be inserted every 10 odd kilometers, so that the cost of the repeaters becomes the major cost of the shallow-sea cable system. Therefore, the problem is the research and development of repeaters which are inexpensive to manufacture yet reliable in operation. However, at the continental shelf up to 200 meters in depth, the temperature of sea water changes from one place to another and according to the season. The conductors of the-communication cables are generally made of pure copper whose temperature coefficient of electrical resistivity (dp/dT) is for'very high-and is example, 6.77 X luQ-cm/"C at 30C so that the rate of change of electrical resistivity p with temperature is very high. Therefore, the change of attenuation with temperature must be taken into consideration in a shallow sea cable system. That is, the change of=attenuation with temperature must be equalized by some means and some margin oferror must be takeninto consideration in the design of the repeaters in order to prevent an overload and the noise decay. As a result, the cost of repeaters is increased.

In order to overcome this problem, there has been proposed and used a method for inserting an automatic gain control (AGC) circuit into a repeater for a submarine coaxial cable system. In a typical automatic gain control circuit, the temperature of the sea water is detected by a direct-heating type thermistor so that the response of an equalizing circuit may be controlled in response to the change in resistance of the thermistor. This method has an advantage in that the circuit is simple in construction, but also has a disadvantage in that the response error is very high. In order to reduce the residual error there has been proposed a method for utilizing an automatic gain control circuit with a pilot control; but the system is complicated and the repeaters become expensive to manufacture and are unreliable in operation.

In view of the above, one of the objects of the present invention is to provide a submarine coaxial cable whose change of attenuation with temperature is extremely small.

Another object of the present invention is to provide a submarine coaxial cable which itself functions as a circuit equivalent to an automatic gain control circuit so that the submarine coaxial cable may become inexpensive to manufacture but is highly reliable in operation. I

Another object of the present invention is to provide a submarine coaxial cable using conductors made of a novel dispersion-type conductive material with a low temperature-coefficient of resistivity so that the temperature coefficient of loss of inner dielectrics may be compensated, with theresulting considerable reduction in the changeof attenuation with temperature of the submarine cable.

The present invention willbecome more apparent BRIEF DESCRIPTION OF THE- DRAWING FIG. 1 is a cross sectional view of a typical submarine coaxial cable;

FIG. 2 is a graph illustratingthe relation betweenthe frequency and the attenuationof a submarine cable, the graph being used for an explanationlof the underlying principle of the present invention;v

FIG. 3' is a graphused'for the explanation of the'relation between M'atthiessens rule and. the electrical properties of the conductive materialsin accordance with the present invention;

FIGS. 4-8 are graphs illustrating the changes of resistivity with temperature of the conductive materials prepared in accordance with the present invention in comparison with that of pure copper (curvea);

FIG. 9 is a graph illustrating the changes of attenuation with temperature of the cables in accordance with the present invention using the conductors made of a conductive material consisting of 0.15% Al O Cu prepared in accordance with the present invention in comparison with those of the conventional cables using the conductors made of copper wires; and

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1 a submarine coaxial cable is gen erally composed of a steel strand. 1 covered with a first copper tape 2 which serves as an inner-conductor, a second copper tape 4 which is coaxially spaced apart from the first copper tape 2 andserves as an outer conan fiu v pJdn/rn z/ 1)] N /m 3 a8 K VEIftanS Nep/m 4 d d outer diameters of inner conductor and insulation in meters,

p p resistivities in ohm-meter of inner and outer conductors,

e, relative dielectric constant of insulator 3 filled into the space between the inner and outer conductors,

tan8 dielectric power factor of the insulator 3,

f= frequency in Hz,

K, coefficient equals 5.27 X 10 and K coefficient equals 1.05 X 10 When the temperature of the coaxial cable changes from TC to (T AT)C, the above parameters change as follows: 7

d, z constant 1 v 5 tanfi (T+ AT) tan6(T) {l K 'AT} Since the linear thermal expansion coefficent of the Next, the underlying principle of the present invention will be described with reference to FIG. 2. The curve d indicates the change in attenuation when a conductive material with a low temperature coefficient inner conductor is negligibly small, d is constant as 5 is used so that the change in attenuation due to change shown in Eq. 5, and temperature coefficients K K e in resistivity is decreased from the curve a tothe curve and K 5 are negative whereas K p l and K p 2 are posa. It can be seen that this method is very effective to itive. decrease the overall change in attenuation of the cable.

Due to the temperature variations of these parame- In the instant embodiment, the temperature coeffiters, there are attenuation changes with temperature as l0 cients of the conductors were reduced by about pcrshown in Table 1. cent with the result of the reduction in change in atten- Table l alternation frequency variation characterattenuation symin response to istics of in Nep or dB causes bol temperature rise attenuation in proporchange of tion to 1/2K p ,a AT resistivity f of inner conductor increase a change of do. f" VzK p 2(MAT resistivity of outer conductor change of do. f /2K 5 (a,,+a,,)AT dielectric constant decrease b change of do. f K,,{a, +(a, +a,,/ln(d /d,)} diameter of outer conductor change of do. f'-" AK g a 6 AT dielectric constant decrease c change of do. f""' K 5 a 5 AT tanS The terms in proportion to f are introduced beuation to about one third. FIG. 2 shows that when the cause the frequency characteristic of dielectric power temperature coefficient of the conductors are defactor of the insulator, which is generally polyethylene, 40 creased from the curve a to the curve a the change in is in proportion to P at a low frequency less than 500 attenuation is considerably reduced as shown by the MHz. Changes in diameter of the outer conductor are arrow d to d. Ordinarily the change in resistivity of the caused by the volume expansion of the insulator. conductor with temperature, which is the main cause When the conductors are made of annealed pure of the change in attenuation, is compensated to some copper and the insulators are made of polyethylene, the extent by the change with temperature of the insulator, temperature coefficients are as follows: so that the change in attenuation with temperature may K p K p 2 3.9 X l0"/C be considerably reduced when the temperature coeffi- K e 4.9 X l0"'/C cient of resistivity of the conductor is slightly reduced. K,, 2.9 X lO"/C The curve d in FIG. 2 indicates the case where both K 5 -5.7 X lO' /C the inner and outer conductors 2 and 4 of the coaxial The relation of the above variation factors with the cable shown in FIG. 1 were made of a material with a overall variation is shown in FIG. 2 when the outer conlow temperature coefficient of resistivity. However, in ductor is 25.4 mm in inner diameter and the inner conpractice, the change in attenuation with temperature ductor is 8.38 mm in diameter. The frequency change may be satisfactorily reduced only by making the inner per 1C of the submarine coaxial cable of I kilometer conductor 2 of a material with a low temperature coefis shown, and a, b and c in FIG. 2 show the parameters ficient of resistivity. Shown in Table 1. Next, the conductive materials for the inner and The change of attenuation is given by a (b c) outer conductors of the coaxial cable of the present ina. It is seen that the change in attenuation is suddenly vention will be described. In FIG. 3 the curve A indidecreased at a high frequency mainly because of the cates the Matthiessens rule. It is seen that the product effect of tan 8 (the curve d), but is considerably high of the resistivity (p) of a conductor (including copper at a low frequency because of the lesser effect of tan8. alloy) and the temperature coefficient l/p)'(dp/d!)] In view of the above, the primary object of the presis a constant so that the resistivity is increased as the ent invention is to considerably decrease the change in temperature coefficient of resistivity is decreased. attenuation with temperature of a submarine coaxial Therefore, in the conventional coaxial cables using the cable by using a conductive material with a low temperature coefficient of electrical resistivity.

inner and outer conductors made of copper alloys, it is difficult to reduce the temperature coefficient of resistivity without increasing the attenuation even when a conductive material with a low temperature coefficient of resistivity is used. However, in case of the conductive materials in which a small percentage of one of the metal oxides, ferrite, finely divided thermistor, carbides, or finely divided nickel-copper alloy powder is dispersed into copper, Matthiessens rule is not valid so that the temperature coefficient of resistivity may be reduced by about 30 percent without increasing resistivity. In FIG. 3, a white dot a indicates the measured value of a standard annealed copper wire; a white triangle b, a copper wire into which is dispersed 0.2 percent of thermistor fine powder; c, a copper wire into which is dispersed 0.2 percent of MgO; d, a copper wire into which is dispersed 0.15 percent of A1 e, a copper wire into which is dispersed 0.5 percent of finely divided TiC', and f, a copper wire into which is dispersed 1.0 percent of nickel-copper alloy powder. Electrical properties of these conductive materials are shown in In addition to the above conductive materials, there maybe used ferrite such as MnCoFe O BaFe O NiZnFe O NiCuFe O Li ,-,Fe O and the like; thermistor powder consisting of, as a major component, oxides of transition metal elements, that is the oxides of Mn, Ni, Co and Cu, and, as a minor component, the oxides of Mo, Fe, Cr, and V; oxides such asMgO, A1 0 Mn O CrO V0 V 0 ThO and the like; and carbides such as Mo C, SiC, TaC, WC, Fe C and the like. In general, 0.01 5.00 percent by weight of these compounds are added to copper to obtain a desired temperature coefficient of resistivity. In addition to the above compounds, 0.01 5.00 percent by weight of, Ni-Cu alloy may be added to copper. However, when the weight ofa compound to be added is less than 0.01 percent, a desired low temperature coefficient is not obtained, and when the weight is in excess of 5.0 percent, a conductive material becomes too brittle to be drawn or rolled even though a satisfactory low temperature coefficient of resistivity is obtained. Next, some examples of the present invention will be described.

EXAMPLE 1 40 percent by weight of Mn0 35 percent by weight of C00, 20 percent by weight of NiO and 4 percent by weight of CuO 50 grams of pure copper powder of about 100 microns in particle size and 50 grams of thermistor fine powder about 40 microns in particle size were uniformly mixed in ethyl alcohol, and thereafter eter. The wire was annealed for about 1 hour at 600C in vacuum, and then cooled in the furnace. The content of thermistor powder in the wire was 0.2 percent. The thermistor oxide was uniformly dispersed in copper matrix. The resistivity was measured by an automatic electrical resistance measuring equipment at l X 10' torr at a speed of 0.625C/minute.

EXAMPLE 2 FIG. 5 shows the change of resistivity with temperature (curve b) of a copper wire having 0.2 percent of ferrite dispersed therein in comparison with that of a pure copper wire. 99.8 grams of pure copper powder 10 microns in particle size and 0.2 grams of MnCoFe- 0 500A in particle size' was uniformly mixed in ethyl alcohol, and thereafter the alcohol was evaporated at 50C. The mixture was pressed by a rubber press machine under a hydrostatic pressure of 3,000 kg/cm and then sintered in vacuum for 2 hours at 950C. The pressed material was forged at 850C and drawn into a wire 0.7 mm in diameter. The wire was annealed for about 1 hour at 600C in vacuum and then cooled in the furnace. Ferrite was uniformly dispersed in copper matrix which was confirmed by an image analyzer in a quantitative metallurgical system.

Co-precipitation of MnCoFe O was effected by reaction in aqueous solution and then synthesized by hydrothermal synthesis. The particle size'of MnCOF 0 was confirmed by an electron microscope. in like manner, other ferrites such as BaFe O NiZnFe O,, NiCuFe O and Li Fe O were used, and the electrical properties of copper wires thus provided are shown in Table 3.

Table 3 FIG. 6 shows the change of resistivity with temperature (curve b ofa copper wire containing 0.2 percent of MgO in comparison with the curve a of a pure copper wire.

50 grams of pure copper powder about microns in particle size and 50 grams of MgO about 10 microns in particle size were mixed methyl alcohol, and then the alcohol was evaporated at 50C. The mixture was pressed into a cylinder by a mechanical press under a pressure of 1,000 kglcm The mold was sintered for about 1 hour at 800C to provide a Cu-MgO mother al- 10y. 1.6 grams of the mother alloy was added to 200 grams of molten copper at 1,250C and mixed for I about hours before it was cast in a mold. The yield of MgO in the mother alloy was about 50 percent, and the copper alloy contained 0.2 percent of MgO. The ingot was forged at 850C, drawn into a wire 0.7 mm in diameter, annealed in vacuum at 600C for about 1 hour and then cooled in the furnace. The added MgO was uniformly dispersed in a copper matrix, and the change of resistivity with temperature was measured by an automatic electrical resistance measuring equipment at 1 X 10 torr and at a speed of 0.625C/minute.

In like manner, 99.5 grams of pure copper powder 10 microns in particle size and 0.5 grams of Th0; powder 0.7 microns in particle size were uniformly mixed in ethyl alcohol, and thereafter the alcohol was evaporated at 50C. The mixture was pressed by use ofa rubber press machine under a pressure of 3,000 kg/cm 50 grams of pure copper powder 100 microns inparticle size and 50 grams of TiC'4O microns in particle size were uniformly mixed in ethyl alcohol and thereafter the alcohol was evaporated at 50C. The mixture was pressed into a cylinder by a mechanical press under a pressure of 1,000 kg/cm and the cylinder was sintered for one hour at 800C to prepare a Cu-TiC mother alloy. 2.0 grams of the mother alloy was charged into 98 grams of molten copper at about 1,250C and mixed for 10 minutes before it'was cast into a metal mould. The yield of TiC in the mother alloy was about 50 percent, and the ingot contained 0.5 percent of TiC. The ingot was forged at 850 C, drawn into a wire of 0.7 mm in diameter, annealed for about 1 hour at 600C in vacuum, and then cooled in the furnace. The-change of resistivity-with temperature was 7 measured by an automatic electrical resistivity measuring equipment at 1 X 10 torr and at a speed of 0.625C/minute.

Table 5 shows the electrical properties of copper wires containing carbide powder.

Table 5 uQ-cm/C pure 7 copper pure copper 1.79 3.78 6.77 100 0.5% TiC-Cu 1.792 2.86 5.13 75.8

1.5% TiC-Cu 1.870 3.02 5.65 83.5

0.3% WC-Cu 1.904 2.93 5.58 82.4

firmed by an image analyzer in a quantitative metall'ur- EXAMPLE 5 gical system that ThO was uniformly dispersed in copper matrix.

ln like manner the copper wires containing other oxides such as MnO CrO' V0 and V 0 were prepared, and the electrical properties of the copper wires of Example 3 were shown in Table 4.

FIG. 7 shows the change of resistivity with temperature (curve b) of a copper wire having-0.5 percent of TiC dispersed therein in comparison with-that ofa pure copper wire (curve a).

FIG. 8 shows the change of resistivity with temperature (curve b) of a copper wire containing 1' percent of (50% Ni-Cu).alloy in comparison .with that of a pure copper (curve a). t

. 198 grams of pure copper powder about microns in particle size and. 2.0 grams of 50% Ni-Cu) alloy about 40 microns in particle size were uniformly mixed in ethyl alcohol. (50% Ni-Cu) alloy was prepared by an atomization method. A ball mill was used for mixing. The ingredients were therefore 99% Cu and 1 percent (50% Ni-Cu).

The mixture wasdried at 50C to completely remove the alcohol and was pressed into acylinder about 200 mm in length and about 10 mm in diameter by arubber press machine under the pressure of 2,000 kg/cm The cylinder was sintered in vacuum for 30 .minutes at 700C, and thereafter drawn by a swaging machine into a wire about 4 mm in diameter. The wire was annealed at 600C for a few times in order to prevent the hardening in a continuous drawing step by which the wire was finally drawn to a wire 0.7 mm indiameter. The wire was annealed for one hour at 600C. The added NiCu was uniformly dispersed in Cu matrix.

The electrical properties were measured in vacuum- (1 X 10" torr.) and at a speed of 0.625C/minute by an automatic electrical resistivity measuring equipment, and shown in Table 6.

Table ,6 Continued P/ )3u ratio resistivity :30 to dp/dT (uQcm) (Xl0/C) l0 of pure #Q'cm/C) copper(%) 0.57: (Ni-Cu) -Cu L87 3.06 5.72 84.5 1.0% (Ni-Cu) -Cu L98 2.82 5.58 82.4

Remarks: (Ni Cu) is 50% Ni-Cu alloy.

EXAMPLE 6 The inner and outer conductors of the coaxial cable were made of copper having 0.15 percent of'Al O dispersed therein, and the insulator was polyethylene with a low density for submarine cables. FIG. 9 shows the changes of attenuation with temperature of 1 kilometer submarine cables of the type described and 1 inch, 1.5 inch and 2 inch in diameter (curves a, b and c, respectively) in comparison with those (curves a,b, and c) of the conventional submarine, cables of 1 inch, 1.5 inch and 2 inch in diameter and using the ordinary soft copper wires. It is seen that the change of attenuation of the submarine coaxial cable of the present invention is reduced to about Vs as compared with the conventional submarine cables. I

What is claimed is:

1. A submarine coaxial cable characterized by comprising I a. an inner conductor,-

b. an outer conductor disposed coaxially of said inner conductor and in spaced apart relation therewith to surround the same,

c. an insulating material filling the space between said inner and outer conductors, and

d. said inner conductor being made of a dispersion type conductive material having a temperature coefficient of resistivity lower than that of pure copper and consisting of copper and 0.01-5.00 percent by weight of finely divided powder dispersed in said copper, said finely divided powder being from the group consisting of metal oxides, ferrite, thermistor, carbides, and nickel-copper alloy powder.

2. A submarine coaxial cable as defined in claim 1 wherein said dispersion-type conductive material consists of copper having 0.01 5.00 percent by weight of finely divided ferrite powder dispersed therein, said ferrite powder being'selected from the group consisting of MnC0Fe O BaFe O NiZnFe O NiCuFe O and ms as m 3. A submarine coaxial cable as defined in claim 1 wherein said dispersion-type conductive material consists of pure copper having dispersed therein 0.01-5.00 percent by weight of finely divided thermistor powder, said thermistor powder consisting of, as a major component, oxides of transient elements selected from the group consisting of oxides of Mn, Ni, Co and Cu and, as a minor component, oxides selected from the group consisting of Mo, Fe, Zr, Cr and V. v

4. A submarine coaxialcable as defined in claim 1 wherein said dispersion-type conductive material consists of pure copper having dispersed 0.01 5.00 percent by weight of at least one compound selected from the oxide group consisting of MgO, MnO CrO V 0 and A1203.

5. A submarine coaxial cable as defined in claim 1 wherein said dispersion-type conductive material consists of pure copper having dispersed therein 0.01 5.00 percent by weight of at least one compound selected from the carbide group consisting of TiC, MoC, SiC, TaC, WC and Fe C.

6. A submarine coaxial cable as defined in claim 1 wherein said dispersion-type conductive material consists of pure copper having dispersed therein 0.01 5.00 percent by weight of 30 percent NiCu alloy (by weight percent).

7. A submarine coaxial cable characterized by comprising a. an inner conductor b. an outer conductor disposed coaxially of said inner conductor and in spaced apart relation therewith to surround the same,

c. an insulating material filling the space between said inner and'oute r conductors, and

(1. said inner and outer conductors being made of a dispersion type conductive material having a temperature coefficient of resistivity lower than th at of pure copper and consisting of copperand 0.01 5.00 percent by weight of a finely divided powder dispersed in said copper, said finely divided powder being from the group consisting of metal oxides, ferrite, thermistor, carbides, and nickel-copper alloy powder. 7

8. A submarine coaxial cable as defined in claim 7, wherein said dispersion-type conductive material consists of copper having 0.01-5.00 percent by weight of finely divided ferrite powder disposed therein, said fer rite powder being selected from the group consisting of MnCoFe O BaFe O NiZnFe O,, NiCuFe- O and 0.5 2.5 4'

9. A submarine coaxial cable as defined in claim 7 wherein said dispersion-type conductive material consists of pure copper having dispersed therein 0.01-5.00

percent by weight of finely divided thermistor powder,

said thermistor powder consisting of, as a-majorcomponent, oxides of transient elements selected from the group consisting of oxides of Mn, Ni, Co and Cu, and, as a minor component, oxides selected from the group consisting of Mo, Fe, Zr, Cr and V.

10. A submarine coaxial cable as defined in claim 7 wherein said dispersion-type conductive material consists of pure copper having dispersed 0.01-5.00 percent by weight of at least one compound selected from the oxide group consisting of MgO, MnO CrO V 0 and A1 0 11. A submarine coaxial cable as defined in claim 7 wherein said dispersion-type conductive material consists of pure copper having dispersed therein 0.01-5.00 percent by weight of at least one compound selected from the carbide group consisting of TiC, MoC. SiC. TaC, WC and Fe C.

12. A submarine coaxial cable as defined in claim 7 wherein said dispersion-type conductive material consists of pure copper having dispersed therein 0.01-5.00 percent by weight of 30 70 percent NiCu alloy (by weight percent).

Claims

1. A SUBMARINE COAXIAL CABLE CHARACTERIZED BY COMPRISING A. AN INNER CONDUCTOR, B. AN OUTER CONDUCTOR DISPOSED COAXIALLY OF SAID INNER CONDUCTOR AND IN SPACED APART RELATION THEREWITH TO SURROUND THE SAME, C. AN INSULATING MATERIAL FILLING THE SPACE BETWEEN SAID INNER AND OUTER CONDUCTOR, AND D. SAID INNER CONDUCTOR BEING MADE OF A DISPERSION TYPE CONDUCTIVE MATERIAL HAVING A TEMPERATURE COEFFICIENT OF RESISTIVITY LOWER THAN THAT OF PURE COPPER AND CONSISTING OF COPPER AND 0.01-5.00 PERCENT BY WEIGHT OF FINELY DIVIDED POWDER DISPERSED IN SAID COPPER, SAID FINELY DIVIDED POWDER BEING FROM THE GROUP CONSISTING OF MATERIAL OXIDES, FERRITE, THERMISTOR, CARBIDES, AND NICKEL-COPPER ALLOY POWDER.

2. A submarine coaxial cable as defined in claim 1 wherein said dispersion-type conductive material consists of copper having 0.01 - 5.00 percent by weight of finely divided ferrite powder dispersed therein, said ferrite powder being selected from the group consisting of MnCoFe2O4, BaFe12O19, NiZnFe2O4, NiCuFe2O4 and Li0.5Fe2.5O4.

3. A submarine coaxial cable as defined in claim 1 wherein said dispersion-type conductive material consists of pure copper having dispersed therein 0.01-5.00 percent by weight of finely divided thermistor powder, said thermistor powder consisting of, as a major component, oxides of transient elements selected from the group consisting of oxides of Mn, Ni, Co and Cu and, as a minor component, oxides selected from the group consisting of Mo, Fe, Zr, Cr and V.

4. A submarine coaxial cable as defined in claim 1 wherein said dispersion-type conductive material consists of pure copper having dispersed 0.01 - 5.00 percent by weight of at least one compound selected from the oxide group consisting of MgO, MnO2, CrO2, V2O3 and Al2O3.

5. A submarine coaxial cable as defined in claim 1 wherein said dispersion-type conductive material consists of pure copper having dispersed therein 0.01 - 5.00 percent by weight of at least one compound selected from the carbide group consisting of TiC, MoC, SiC, TaC, WC and Fe3C.

6. A submarine coaxial cable as defined in claim 1 wherein said dispersion-type conductive material consists of pure copper having dispersed therein 0.01 - 5.00 percent by weight of 30 - 70 percent Ni-Cu alloy (by weight percent).

7. A submarine coaxial cable characterized by comprising a. an inner conductor b. an outer conductor disposed coaxially of said inner conductor and in spaced apart relation therewith to surround the same, c. an insulating material filling the space between said inner and outer conductors, and d. said inner and outer conductors being made of a dispersion type conductive material having a temperature coefficient of resistivity lower than that of pure copper and consisting of copper and 0.01 - 5.00 percent by weight of a finely divided powder disperSed in said copper, said finely divided powder being from the group consisting of metal oxides, ferrite, thermistor, carbides, and nickel-copper alloy powder.

8. A submarine coaxial cable as defined in claim 7, wherein said dispersion-type conductive material consists of copper having 0.01-5.00 percent by weight of finely divided ferrite powder disposed therein, said ferrite powder being selected from the group consisting of MnCoFe2O4, BaFe12O19, NiZnFe2O4, NiCuFe2O4 and Li0.5Fe2.5O4.

9. A submarine coaxial cable as defined in claim 7 wherein said dispersion-type conductive material consists of pure copper having dispersed therein 0.01-5.00 percent by weight of finely divided thermistor powder, said thermistor powder consisting of, as a major component, oxides of transient elements selected from the group consisting of oxides of Mn, Ni, Co and Cu, and, as a minor component, oxides selected from the group consisting of Mo, Fe, Zr, Cr and V.

10. A submarine coaxial cable as defined in claim 7 wherein said dispersion-type conductive material consists of pure copper having dispersed 0.01-5.00 percent by weight of at least one compound selected from the oxide group consisting of MgO, MnO2, CrO2, V2O3 and Al2O3.

11. A submarine coaxial cable as defined in claim 7 wherein said dispersion-type conductive material consists of pure copper having dispersed therein 0.01-5.00 percent by weight of at least one compound selected from the carbide group consisting of TiC, MoC, SiC, TaC, WC and Fe3C.

12. A submarine coaxial cable as defined in claim 7 wherein said dispersion-type conductive material consists of pure copper having dispersed therein 0.01-5.00 percent by weight of 30 - 70 percent Ni-Cu alloy (by weight percent).