Twisted pair cable

Details Twisted pair cable Twisted pair cable

1998-03-27

2001-04-24

Kincaid, Kristine (Department: 2831)

Electricity: conductors and insulators

Conduits, cables or conductors

Insulated

C174S1100FC

Reexamination Certificate

active

06222129

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to twisted pair cables which can be used in high frequency applications and more particularly, the present invention relates to high frequency twisted pair cables having a pair of insulated conductors wherein each insulated conductor has at least a foam insulating layer surrounding the conductor.
BACKGROUND OF THE INVENTION
In the past, twisted pair cables were utilized in applications where data speeds reached an upper limit of about 20 kilobits per second. Recent advances in wire technology and hardware equipment have pushed the upper limit of twisted pair cable applications to about several hundred megabits per second.
Twisted pair technology advances have primarily focused on near end crosstalk. Both U.S. Pat. No. 3,102,160 and U.S. Pat. No. 4,873,393 teach the importance of utilizing pairs which are twisted with lengths of lay different from integral multiples of the lengths of lay of other paired conductors within the cable. This is done to minimize electrical coupling between paired conductors.
U.S. Pat. No. 5,015,800 focuses on another important issue of maintaining a controlled impedance throughout the transmission line. It teaches how impedance can be stabilized by the elimination of air gaps around a twisted pair embodiment through the use of a dual dielectric which has outer layers bonded after the insulated conductors are twisted.
When two or more pairs of different average impedance are connected together to form a transmission line (often referred to as a channel), part of the signal will be reflected at the point of attachment(s). Reflections due to impedance mismatch ultimately causes problems with signal loss and tracking errors (jitter).
Prior attempts to control conductor spacing has been entirely for the purposes of stabilizing capacitance within a cable. It is well known in the industry that utilizing a cable with uniform capacitance between its pairs has the advantage of reducing crosstalk. U.S. Pat. No. 3,102,160 explains how equal and uniform capacitance can be achieved along a transmission line by simultaneously extruding dielectric over two conductors.
However, U.S. Pat. No. 3,102,160 did not recognize problems encountered with impedance mismatch at high frequencies. The impedance of the cable was of little importance provided the capacitance of each pair within the cable was relatively uniform. The problem is in that different cables can have uniform capacitances between their respective pairs and yet possess different average impedances.
Another problem with the U.S. Pat. No. 3,102,160 is with regard to insulated conductor separation. In order for the pairs of the said cable to be used with current LAN systems and connecting hardware, the adjoined insulated conductors must have the ability to be separated from one another for at least 1 inch along the length of the pair. The prior art provides no means for the separation of the two adjoined insulated conductors.
SUMMARY OF THE INVENTION
Accordingly, with the first dielectric layer being a foamed dielectric, it is an object of this invention to provide a twisted pair cable having two conductors, at least two dielectric layers surrounding each conductor, the conductors and corresponding dielectric layers being twisted substantially along the length of the cable to provide the twisted pair cable having a center-to-center distance between the two twisted conductors varying over any 1000 ft length ±0.03 times an average center-to-center distance with the average center-to-center distance being the average of at least 20 distance measurements taken at least 20 feet apart from three randomly selected 1000 ft twisted cable of the same size taken from the same run or from three successive runs.
It is a further object of this invention to provide a twisted pair cable having two conductors, a dielectric layer surrounding each conductor, the conductors and corresponding dielectric layers being twisted substantially along the length of the cable to provide the twisted pair cable having over any 1000 ft., an impedance of about 90 to 110 ohms when measured at frequencies of about 10 MHz to about 200 MHz, the impedance being within an impedance tolerance of ±5% of an average impedance, the average impedance being:
a. an average of at least one impedance measurement on each of at least twenty 1,000 ft. twisted pair cables of the same size taken from the same run, or
b. an average of at least one impedance measurement from each of twenty randomly selected 1000 ft. twisted pair cables of the same size, taken from three separate successive runs with each run being at least 24 hours apart from each other, or
c. selecting one twisted pair cable from twenty consecutive 1000 ft. twisted pair cable and taking at least 200 impedance measurements on the one twisted pair cable with the at least 200 impedance measurements being at between 10 MHz and 200 MHz taken in less than 0.5 MHz increments.


REFERENCES:
patent: 3102160 (1963-08-01), Cook et al.
patent: 3219752 (1965-11-01), Harris
patent: 3361871 (1968-01-01), Brandt
patent: 3516859 (1970-06-01), Gerland et al.
patent: 3715458 (1973-02-01), Bayes et al.
patent: 3761842 (1973-09-01), Gandrud
patent: 3921381 (1975-11-01), Vogelsberg
patent: 4010231 (1977-03-01), Berglowe, Jr. et al.
patent: 4356345 (1982-10-01), Lee
patent: 4449012 (1984-05-01), Voser
patent: 4467138 (1984-08-01), Brorein
patent: 4486619 (1984-12-01), Trine et al.
patent: 4873393 (1989-10-01), Friesen et al.
patent: 4933513 (1990-06-01), Lee
patent: 5010210 (1991-04-01), Sidi et al.
patent: 5015800 (1991-05-01), Vaupotic et al.
patent: 5103067 (1992-04-01), Aldissi
patent: 5142100 (1992-08-01), Vaupotic
patent: 5162609 (1992-11-01), Adriaenssens et al.
patent: 5245134 (1993-09-01), Vana, Jr.
patent: 5270486 (1993-12-01), Chan et al.
patent: 5283390 (1994-02-01), Hubis et al.
patent: 5342991 (1994-08-01), Xu et al.
patent: 5448669 (1995-09-01), Dunn et al.
patent: 5606151 (1997-02-01), Siekierka et al.
patent: 5670748 (1997-09-01), Gingue et al.
patent: 5734126 (1998-03-01), Siekierka et al.
patent: 1265877 (1961-05-01), None
European Pat. Appln. 0302162A3; date Jan. 19, 1998.

Affiliated with

Also associated with

Rating

Twisted pair cable does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Twisted pair cable, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Twisted pair cable will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2494580