Interaxial spacing and dielectric constant of pairs in multipaired cables

A major handicap in the evaluation of different designs and manufacturing processes, in respect to efficiency of space utilization inside the sheath of multi-pair telephone cable, has been the lack of a simple and accurate method of measuring the dielectric constant of such cable pairs. This paper describes a simple non-destructive method of determining both the interaxial spacing between conductors of a cable pair and the dielectric constant. An important by-product of the work is the demonstration of the fact that ε = L × C is not a valid means of determining the dielectric constant of cable pairs.