Measurement & Simulation of Differential Skew in Twisted Pair Cables


AUTHORS: J. Poltz, J. Beckett and M. Josefsson

VENUE: Presented at the 55th IWCS/Focus Conference, November 13-16, 2006, Providence, RI, USA

ABSTRACT - The impact of manufacturing tolerances on unbalances in various individually screened twisted pair cables is discussed in this paper. Unbalances were grouped under categories which originate from geometrical, conductance or dielectric asymmetry of the pair. The concept of quasi-common and quasi-differential modes of propagation and modal dispersion in an unbalanced pair is discussed. It is demonstrated that the geometrical asymmetry is the least harmful for the quality of propagation on an unbalanced pair. Three different samples of cables each with low- and high-skew pairs were selected for laboratory tests. The differential skew (intra pair skew) were measured directly with a Network Analyzer and a power splitter. Measurements were also performed on the conductor-screen loop to find out the difference in primary unit parameters (inductance, resistance, capacitance) within each screened pair. Simulation and measurement results lead to similar conclusions regarding the correlation between unit parameter unbalance and intra pair skew.

Cable with eccentric wire 2 photograph and model

To obtain a copy of this paper please make a note of the reference number and fill out ourrequest form.

Back to alltechnical papers.

Back to topBack to Top