CROSSTALK BETWEEN COAXIAL CONDUCTORS 



379 



sible for the results described in the discussion of near-end crosstalk in 

 a five-mile length." 



The relative importance of various tertiary circuits in the production 

 of interaction crosstalk between two sections was studied for the case 

 of near-end near-end crosstalk between two 12,000-foot lengths. It 

 was found that the outer conductor-quads and outer conductor-sheath 

 circuits were about equally important and that crosstalk via the quad- 

 sheath tertiary circuit was from 20 to 30 db less. These results are 

 about as expected since the outer conductors are the source of the 



40 50 60 



80 100 150 200 300 400 500 600 



FREQUENCY IN KILOCYCLES PER SECOND 



Fig. 11 — Interaction crosstalk between two 12,000-foot lengths. 



tertiary emf and thus the tertiary circuits involving the outer con- 

 ductors should be the important ones. It is therefore permissible to 

 consider sheath and quads as a single unit as was done in Part I. 



Effectiveness of Transpositions on Far-End 

 Crosstalk Reduction 



In a long repeatered system the far-end crosstalk measured in suc- 

 cessive individual sections inherently tends to sum up directly since all 



" It should be noted that while Fig. 11 shows the measured values of the three 

 types of interaction crosstalk between two 12,000-foot sections, the relative impor- 

 tance of the various types acting between repeater sections, that is, around repeaters, 

 is not as shown there, since different correction factors have to be applied when 

 estimating the total crosstalk at system terminals. 



