190 



BELL SYSTEM TECHNICAL JOURNAL 



1.0 5 



1.00 



0.95 



0.90 



0.85 



0.80 



0.75 



0.70 



0.65 

 T3 



^, 0.60 



^ 0.55 



0.50 



5 0.45 



O 



f 0.40 



0.35 



0.30 



0.25 



0.20 



0.15 



0.10 



0.05 







-0.05 

 -0.10 



3 4 5 10 20 30 50 100 200 300 



FREQUENCY IN KILOCYCLES PER SECOND 



500 1000 



Fig. 5 — Mutual inductance between pairs of parallel wires in terms of value for Ma 



at one kilocycle. 



of the curves of Ma and Mb in Figs. 3 and 4 with the curves of Fig. 6 

 illustrates the relative importance of the proximity effect on magnetic 

 crosstalk in cable pairs and in open-wire pairs. In cable pairs the 

 wires are close together as in Figs. 3 and 4, while in open wire the sepa- 

 ration is much greater than that shown in Fig. 6. 



The effect of wire gauge on the variation of Ma and Mb is shown in 

 Figs. 7, 8, 9- A and 9-B. Two gauges of wire (No. 10 and No. 18 

 A.W.G.) were used with centers located at the corners of a 0.14-inch 

 square. The mutual impedance between the vertically adjacent pairs 

 was measured. The corresponding values of Ma and Mb are shown in 



