SHIELDED CABLE

• US 3,639,674 A
• Filed: 06/25/1970
• Issued: 02/01/1972
• Est. Priority Date: 06/25/1970
• Status: Expired due to Term

• Current Assignee: Cooper Industries, Inc. (Eaton Corporation PLC.)
• Original Assignee: Ronald L. Stier
• Inventors: Stier, Ronald L.
• Primary Examiner(s): Kozma, Thomas J.
• Assistant Examiner(s): Grimley, A. T.
• Application Number:
  US05/049,823
• Time in Patent Office: 586 Days
• Field of Search: 174/36,102,103,105,107,106,113,115,110
• US Class Current: 174/36
• CPC Class Codes: H01B 11/18 Coaxial cables; Analogous cables having more than one inner conductor within a common outer conductor
• CPC Class Codes: H01B 9/02 with screens or conductive layers, e.g. for avoiding large potential gradients
• CPC Class Codes: H01B 9/028 with screen grounding means, e.g. drain wires

Abstract

A low-noise coaxial cable is formed with an elongated inner electrical conductor about which is an elongated, dielectric insulating layer of polymeric material which may be either a solid or foamed polymeric material. A thin electroless deposited shield of metal is intimately bonded to the outer peripheral surface of the insulating layer even if the same has surface irregularities therein. The insulating layer may be made with a constant uniform cross-sectional thickness, usually being annular in cross section, and bent and flexed without experiencing discontinuities in the shield which would destroy its effectiveness. The cable may be produced with ordinary commercially feasible techniques to obtain consistently good lownoise characteristics which are maintained even with substantial use and flexing over prolonged periods of time.

Claims

1. A low noise coaxial cable comprising a central, elongated, flexible conductor, a dielectric insulating layer formed of a foamed polymer having an inner surface surrounding said conductor and having an outer peripheral surface, said insulating layer having a substantially uniform cross-sectional denconvoluted thickness throughout substantially its entire length, said outer peripheral surface having surface irregularities therein as a result of its being foamed, a shield formed of an electroless deposit of conductive metal intimately bonded to and extending into and along said surface irregularities of said peripheral surface of said dielectric insulating layer, and shield being thin in cross-sectional thickness compared to the cross-sectional thickness of said dielectric and flexing therewith and maintaining its electrical continuity during bending and a flexible protective sheath surrounding said shield, said insulating layer and said central flexible conductor.

2. A coaxial in accordance with claim 1 in which said shield is substantially cylindrical in shape, is formed with copper, and has a wall thickness in the range of about 0.0005 to 0.0015 inch.

3. A coaxial cable in accordance with claim 1 in which said shield is substantially cylindrical in shape, is formed with nickel, and has a wall thickness in the range of about 0.0005 to 0.002 inch.

4. A coaxial cable in accordance with claim 1 in which the the noise level of said cable is not greater than about 0.25 millivolts.

5. A coaxial cable in accordance with claim 4 in which at least one drain conductor is disposed between said sheath and said shield and extends longitudinally along and in contact with said shield.

6. A low noise coaxial cable comprising a central, elongated, flexible conductor, a dielectric layer surrounding said conductor and having a substantially uniform cross-sectional thickness throughout substantially its entire length, and a thin electroless deposition of metal of substantially uniform cross-sectional dimensions intimately bonded to the outer surface of said dielectric layer foR bending therewith and for maintaining its electrical continuity with flexing of the cable.

7. A coaxial cable in accordance with claim 6 in which said dielectric layer is formed of a foamed polymeric material.

8. A coaxial cable in accordance with claim 7 in which the noise level of said cable is not greater than 0.25 millivolts.

9. A coaxial cable in accordance with claim 7 in which said electroless deposition of metal is substantially cylindrical in shape, formed of copper and has a wall thickness of about 0.0005 to 0.0015 inch.

10. A coaxial cable in accordance with claim 7 in which said electroless deposition of metal is substantially cylindrical in shape, is formed of nickel, and has a wall thickness of about 0.0005 to 0.002 inch.

11. A coaxial cable in accordance with claim 6 in which a conductive shield is disposed about and on said electroless deposition of metal to aid the latter in shielding the inner conductor.

12. A coaxial cable in accordance with claim 11 in which at least one drain conductor is provided in electrical contact with said conductive shield and said electroless deposition of metal.

13. A coaxial cable in accordance with claim 12 in which said drain wire is sandwiched between and in direct contact with said conductive shield and said electroless deposition of metal.