Intel 1000BASE-T User Manual

1000BASE-T/100BASE-TX/10BASE-T Physical Layer Compliance Tests Manual
Intel Confidential 121
Reducing Measurement Error by Avoiding Cable Bending
Figure F-1. Equation for Twin-Lead (Twisted-Pair) Cable
Figure F-2. Equation for Co-axial Cable
Using the Twin-Lead equation for the CAT 5 cable shown in Figure F-1, we can calculate the effect
of compressing the cable (during sharp bends) or separating the wires (straightening after a sharp
bend).
By compressing the dielectric between the two wires by 0.002 inches, the cable impedance was
decreased to 95.3 ohms at the point of compression. This is similar to the impedance produced by
the knot.
By separating the wires in the pair by 0.003 inches, the cable impedance increased to 111.9 ohms at
the point of separation. This is similar to the impedance produced when a kinked cable is
straightened— the wires can “birdcage” or separate.
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Intel 1000BASE-T Specifications

General

Brand	Intel
Model	1000BASE-T
Category	Adapter
Language	English