Coaxial cables having improved smoke performance

• US 20060175074A1
• Filed: 02/04/2005
• Published: 08/10/2006
• Est. Priority Date: 02/04/2005
• Status: Active Grant

• Current Assignee: CommScope Inc. (CommScope Holding Company, Inc.)
• Original Assignee: CommScope Inc. (CommScope Holding Company, Inc.)
• Inventors: Huffman, Jason
• Granted Patent: US 7,157,645 B2
• Time in Patent Office: Days
• US Class Current: 174/102.R
• CPC Class Codes: H01B 11/1826 Co-axial cables with at least one longitudinal lapped tape-conductor

Abstract

A coaxial cable includes an elongate inner conductor. A dielectric layer surrounds the inner conductor. A first outer conductor surrounds the dielectric layer and has perforations defined therein. A second outer conductor surrounds the first outer conductor. A polymeric jacket surrounds the second outer conductor. The cable is adapted such that, when the dielectric layer is melted, at least a portion thereof and/or smoke therefrom can flow through the perforations in the first outer conductor. According to some embodiments, the second outer conductor defines a plurality of voids therein and, when the dielectric layer is melted, at least a portion thereof and/or smoke therefrom can flow through the perforations in the first outer conductor and into the voids. According to some embodiments, the second outer conductor is braided.

Claims

1. A coaxial cable comprising:

a) an elongate inner conductor;

b) a dielectric layer surrounding the inner conductor;

c) a first outer conductor surrounding the dielectric layer and having perforations defined therein;

d) a second outer conductor surrounding the first outer conductor; and

e) a polymeric jacket surrounding the second outer conductor;

f) wherein the cable is adapted such that, when the dielectric layer is melted, at least a portion thereof and/or smoke therefrom can flow through the perforations in the first outer conductor.

2. The coaxial cable of claim 1 wherein the second outer conductor defines a plurality of voids and, when the dielectric layer is melted, at least a portion thereof and/or smoke therefrom can flow through the perforations in the first outer conductor and into the voids.

3. The coaxial cable of claim 2 wherein the second outer conductor is braided.

4. The coaxial cable of claim 2 wherein the second outer conductor covers between about 50 and 98% of the first outer conductor.

5. The coaxial cable of claim 1 wherein the cable is adapted to pass NFPA 262 (2002).

6. The coaxial cable of claim 5 wherein the cable is adapted such that the shielding effectiveness of the cable, as measured in accordance with EN 50289-1-6:

2002, is not degraded by more than about 7 dB as compared to the same cable not having the perforations.

7. The coaxial cable of claim 5 wherein the jacket is formed of polyvinyl chloride (PVC).

8. The coaxial cable of claim 5 wherein the cable is adapted for use as a plenum cable.

9. The coaxial cable of claim 1 wherein the collective area of the perforations is no more than 2% of the total area of the first outer conductor.

10. The coaxial cable of claim 1 wherein the perforations in the first outer conductor are distributed along the first outer conductor at a rate in the range of from about one perforation per 0.25 inch length of the cable to about one perforation per 3 inches length of the cable.

11. The coaxial cable of claim 1 wherein the perforations in the first outer conductor each have an area of between about 0.001 and 0.020 in².

12. The coaxial cable of claim 1 wherein the perforations in the first outer conductor have a nominal separation distance of between about 0.75 and 1.25 inches.

13. The coaxial cable of claim 1 wherein the perforations in the first outer conductor are generally circular holes.

14. The coaxial cable of claim 1 wherein the perforations in the first outer conductor are slits.

15. The coaxial cable of claim 1 wherein the inner conductor is formed of a material selected from the group consisting of solid copper, copper clad aluminum (CCA), silver coated copper, and copper clad steel (CCS).

16. The coaxial cable of claim 1 wherein the dielectric layer is formed of a foamed polymeric material.

17. The coaxial cable of claim 16 wherein the dielectric layer is formed of foamed fluorinated ethylene propylene (FEP).

18. The coaxial cable of claim 1 wherein the first outer conductor has a thickness of between about 0.001 and 0.005 mil.

19. The coaxial cable of claim 1 wherein the first outer conductor is a metallic tape.

20. The coaxial cable of claim 19 wherein the first outer conductor includes a metallic layer laminated to a polymer layer.

21. The coaxial cable of claim 1 wherein the second outer conductor is formed of a material selected from the group consisting of tinned copper, bare copper, and aluminum.

22. The coaxial cable of claim 1 wherein the jacket is formed of a material selected from the group consisting of polyvinyl chloride (PVC), a fluoropolymer, and co-polymers and blends thereof.

23. The coaxial cable of claim 1 further including a third outer conductor surrounding the second outer conductor and surrounded by the jacket.

24. The coaxial cable of claim 23 wherein the third outer conductor is a metallic tape.

25. The coaxial cable of claim 24 further including a fourth outer conductor surrounding the third outer conductor and surrounded by the jacket.

26. The coaxial cable of claim 25 wherein the fourth outer conductor is braided.

27. A coaxial cable comprising:

a) an elongate inner conductor;

b) a dielectric layer surrounding the inner conductor;

c) an outer conductor surrounding the dielectric layer and having perforations defined therein;

d) a polymeric jacket surrounding the outer conductor;

e) wherein the perforations in the outer conductor each have an area of between about 0.001 and 0.020 in²; and

f) wherein the cable is adapted such that, when the dielectric layer is melted, at least a portion thereof and/or smoke therefrom can flow through the perforations in the outer conductor.

29. The coaxial cable of claim 27 further including a second outer conductor surrounding the first outer conductor, wherein the second outer conductor defines a plurality of voids and, when the dielectric layer is melted, at least a portion thereof and/or smoke therefrom can flow through the perforations in the first outer conductor and into the voids.

30. The coaxial cable of claim 29 wherein the second outer conductor is braided.

28. A coaxial cable comprising:

a) an elongate inner conductor;

b) a dielectric layer surrounding the inner conductor;

c) an outer conductor surrounding the dielectric layer and having perforations defined therein;

d) a polymeric jacket surrounding the outer conductor;

e) wherein the cable is adapted to pass NFPA 262 (2002);

f) wherein the cable is adapted such that the shielding effectiveness of the cable, as measured in accordance with EN 50289-1-6;

2002, is not degraded by more than about 7 dB as compared to the same cable not having the perforations; and

g) wherein the cable is adapted such that, when the dielectric layer is melted, at least a portion thereof and/or smoke therefrom can flow through the perforations in the outer conductor.

31. The coaxial cable of claim 28 further including a second outer conductor surrounding the first outer conductor, wherein the second outer conductor defines a plurality of voids and, when the dielectric layer is melted, at least a portion thereof and/or smoke therefrom can flow through the perforations in the first outer conductor and into the voids.

32. The coaxial cable of claim 31 wherein the second outer conductor is braided.