Apparatus for adjusting the coupling reactances between twisted pairs for achieving a desired level of crosstalk

• US 6,410,845 B2
• Filed: 02/07/2001
• Issued: 06/25/2002
• Est. Priority Date: 09/29/1998
• Status: Expired due to Term

• Current Assignee: Nordx/CDT Inc. (Belden Inc.)
• Original Assignee: Nordx/CDT Inc. (Belden Inc.)
• Inventors: Reede, Ivan
• Primary Examiner(s): Reichard, Dean A.
• Assistant Examiner(s): Mayo, III, William H.
• Application Number:
  US09/778,574
• Publication Number:
  US 20010008189A1
• Time in Patent Office: 503 Days
• Field of Search: 174/110.R, 174/113.R, 174/117.F, 174/117.FF, 174/36, 174/74.R, 174/84.R, 174/27
• US Class Current: 174/27
• CPC Class Codes: H01R 13/6461 Means for preventing cross-talk
• CPC Class Codes: H01R 13/6463 using twisted pairs of wires
• CPC Class Codes: H01R 13/6474 by variation of conductive properties, e.g. by dimension variations
• CPC Class Codes: H01R 13/6599 Dielectric material made conductive, e.g. plastic material coated with metal

Abstract

A method and apparatus for adjusting the coupling reactances between twisted pairs contained within a data communications cable is disclosed. An isolation element is used to isolate one or more twisted pairs of wires from the other twisted pairs of wires contained within the data communications cable. The isolation element may be constructed of dielectric, conductive, or ferromagnetic materials or a combination thereof. It may also include various shapes, patterns, and/or windows for creating a specified level of crosstalk among the twisted pairs contained within the cable.

Claims

1. A terminated cable assembly having a desired level of crosstalk comprising:

a cable having a plurality of twisted pairs, the twisted pairs each having two insulated conductors, the cable having an exit region where the twisted pairs exit the cable;

a de-twisted region transversely adjacent to the exit region wherein the twisted pairs transition into an untwisted configuration and are arranged to mate with connecting hardware; and

an isolation element located in the de-twisted region of the cable, the isolation element controlling coupling between adjacent pairs;

wherein the isolation element includes a plurality of channels that are open along a longitudinal length of the isolation element, the plurality of twisted pairs being disposed in the open channels.

2. The terminated cable assembly as in claim 1, wherein the isolation element controls a phase of the coupling between adjacent pairs.

3. The terminated cable assembly as shown in claim 1, wherein the isolation element controls a magnitude of the coupling between adjacent pairs.

4. The terminated cable assembly as in claim 1, wherein the isolation element is conductive.

5. The terminated cable assembly as in claim 4, wherein the conductive isolation element is metallic foil.

6. The terminated cable assembly as in claim 1, wherein the isolation element selectively adjusts coupling reactances between the plurality of twisted pairs to adjust the desired level of crosstalk to a desired value.

7. The terminated cable assembly as in claim 1, wherein the isolation element selectively adjusts coupling reactances to adjust a magnitude of crosstalk to a desired value.

8. The terminated cable assembly as in claim 1, wherein the isolation element selectively adjusts coupling reactances to adjust a phase of crosstalk to a desired value.

9. The terminated cable assembly as in claim 1, wherein the isolation element is dielectric material having a dielectric constant and also having an electrical thickness.

10. The terminated cable assembly as in claim 9, wherein the isolation element has a length, and the dielectric constant varies over the length for varying the electrical thickness of the isolation element over the length.

11. The terminated cable assembly as in claim 1, wherein the isolation element forms a strip having free ends, the isolation element having a thickness for separating the two insulated conductors of one of the plurality of twisted pairs from the two insulated conductors of another of the plurality of twisted pairs.

12. The terminated cable assembly as in claim 1, wherein the isolation element includes a length and a thickness and the thickness varies over the length of the isolation element for selectively adjusting coupling reactances to achieve the desired level of crosstalk.

13. The terminated cable assembly as in claim 1, wherein the isolation element includes a length and a thickness wherein the thickness varies over the length of the isolation element for selectively adjusting coupling reactances between the plurality of twisted pairs to adjust a magnitude of crosstalk to a predetermined value.

14. The terminated cable assembly as in claim 1, wherein the isolation element includes a length and a thickness wherein the thickness varies over the length of the isolation element for selectively adjusting coupling reactances between the plurality of twisted pairs to adjust a phase of crosstalk to a predetermined value.

15. The terminated cable assembly as in claim 1, wherein the isolation element is a ferromagnetic material.

16. The terminated cable assembly as in claim 1, wherein the isolation element is composed of at least two from a list of a conductive material, a dielectric material, and a ferromagnetic material.

17. The terminated cable assembly as in claim 1, wherein the isolation element has features which create compensating reactances between the plurality of twisted pairs.

18. The terminated cable assembly as in claim 17, wherein the features include regions of reduced thickness.

19. The terminated cable assembly as in claim 17, wherein the features include conductors.

20. The terminated cable assembly as in claim 17, wherein the features include ferromagnetic materials.

21. The terminated cable assembly as in claim 17, wherein the features include dielectric materials.

22. The terminated cable assembly as in claim 21, wherein the features include regions having dissimilar dielectric constants.

23. A terminated cable assembly having a desired level of crosstalk relative to a conventional cable, comprising:

a cable having a plurality of twisted pairs, the twisted pairs each having two insulated conductors;

the cable further having a de-twisted region wherein the twisted pairs transition into an untwisted configuration and are arranged to mate with connecting hardware; and

a means for isolating the two insulated conductors of one of the plurality of the twisted pairs from the two insulated conductors of another of the plurality of twisted pairs, wherein the means for isolating also adjusts coupling reactances between the insulated conductors within the de-twisted region of the cable and includes a plurality of channels that are open along a longitudinal length of the isolation element, the insulated conductors being disposed within the channels;

whereby the desired level of crosstalk between the twisted pairs is achieved.

24. A terminated cable assembly having a desired level of crosstalk relative to a conventional cable, comprising:

a cable having a plurality of twisted pairs, the twisted pairs each having two insulated conductors;

the cable further having a de-twisted region where the twisted pairs transition into an untwisted configuration and are arranged to mate with connecting hardware;

means for creating a larger center-to-center distance between the two insulated conductors of one of the plurality of twisted pairs and the two insulated conductors of another of the plurality of twisted pairs than a thickness of insulation of each insulated conductor provides within the de-twisted region of the cable;

whereby electromagnetic coupling is adjusted between individual insulated conductors and the desired level of crosstalk is achieved; and

wherein the means for creating a larger center-to-center distance includes a plurality of channels that are open along a longitudinal length of the isolation element, the insulated conductors being disposed within the channels.

25. The terminated cable assembly as in claim 24, wherein the means for creating a larger center-to-center distance includes means for creating a larger electrical length separating the two insulated conductors of one of the plurality of twisted pairs from the two insulated conductors of another of the plurality of twisted pairs than the thickness of insulation of each insulated conductor provides.

26. The terminated cable assembly as in claim 25, wherein the means for creating a larger electrical length is an isolation element having a length and a thickness wherein the thickness varies over the length.

27. The terminated cable assembly as in claim 25, wherein the isolation element has a length and a dielectric constant, and wherein the dielectric constant varies over the length.

28. A cable assembly having a repeatable level of crosstalk terminated with mating hardware, the cable assembly comprising:

a cable containing a plurality of twisted pairs of conductors;

the cable having an exit region wherein the plurality of twisted pairs exit from the cable;

an isolation element having top and bottom surfaces, an end region distal to the exit region of the cable, and constructed and arranged to physically separate and at least partially electrically isolate the twisted pairs from one another;

a second region adjacent to the end region of the isolation element, wherein each twisted pair is detwisted and oriented to electrically mate with the mating hardware; and

wherein the isolation element comprises a plurality of main channels on the top surface of the isolation element and at least one main channel on the bottom surface of the isolation element, wherein each of the plurality of twisted pairs is disposed within a single main channel, and the main channels are open along a longitudinal length of the isolation element.

29. The cable assembly as in claim 28, wherein each of the plurality of main channels on the top surface and each of the at least one main channel on the bottom surface of the isolation element has two sub-channels.

30. The cable assembly as in claim 29, wherein each of the sub-channels within a main channel has a ridge vertically extending between the sub-channels forming the two sub-channels into a W shape;

wherein each of the two sub-channels contains a single conductor of the twisted pair disposed within the main channel.

31. The cable assembly as in claim 28, the isolation element further comprising a laminated structure.

32. The cable assembly as in claim 31, wherein the laminated structure of the isolation element includes at least first, second, and third layers, wherein said first layer is a conductor and is disposed between said second and third layers, and the second and third layers are dielectric materials.

33. The cable assembly as in claim 32, wherein the first layer is composed of stainless steel.

34. The cable assembly as in claim 32, wherein the second and third layers are composed of MYLAR®

tape.

35. The cable assembly as in claim 32, wherein the first layer is at virtual ground with respect to the plurality of twisted pairs.

36. The cable assembly as in claim 28, wherein the isolation element controls a phase of coupling between adjacent pairs.

37. The cable assembly as in claim 28, wherein the isolation element controls a magnitude of coupling between adjacent pairs.

38. The cable assembly as in claim 28, wherein the isolation element selectively adjusts coupling reactances to adjust the level of crosstalk to a desired value.

39. The cable assembly as in claim 28, wherein the isolation element selectively adjusts coupling reactances to adjust a magnitude of crosstalk to a desired value.

40. The cable assembly as in claim 28, wherein the isolation element selectively adjusts coupling reactances to adjust a phase of crosstalk to a desired value.

41. The cable assembly as in claim 28, wherein the isolation element includes a length and a thickness and the thickness varies over the length of the isolation element for selectively adjusting coupling reactances to achieve a desired level of crosstalk.

42. The cable assembly as in claim 28, wherein the isolation element includes a length and a thickness wherein the thickness varies over the length of the isolation element for selectively adjusting coupling reactances to adjust a magnitude of crosstalk to a predetermined value.

43. The cable assembly as in claim 28, wherein the isolation element includes a length and a thickness wherein the thickness varies over the length of the isolation element for selectively adjusting coupling reactances to adjust a phase of crosstalk to a predetermined value.

44. The cable assembly as in claim 28, wherein the isolation element has features which create compensating reactances between the plurality of twisted pairs.

45. A terminated cable assembly comprising:

a cable including a plurality of twisted pairs of insulated conductors, the cable having a detwisted region where the insulated conductors transition into an untwisted configuration;

an isolation element having a plurality of channels that are open along a longitudinal length of the isolation element, the isolation element at least partially located in the detwisted region of the cable;

wherein the twisted pairs of insulated conductors are disposed within the channels of the isolation element.

46. The terminated cable assembly as in claim 45, wherein a single twisted pair of insulated conductors is disposed within each channel.

47. The terminated cable assembly as in claim 46, wherein a first channel of the plurality of channels includes two sub-channels, and each of the two sub-channels contains a single insulated conductor of the twisted pair of insulated conductors disposed within the first channel.

48. The terminated cable assembly as in claim 45, wherein each of the plurality of channels includes a vertical ridge disposed within the channel that divides the channel into two sub-channels, thereby causing the channel to have a W shape.

49. The terminated cable assembly as in claim 48, each of the two sub-channels contains a single insulated conductor of the twisted pair of insulated conductors disposed within the channel.