632 



BELL SYSTEM TECHNICAL JOURNAL 



O 



o 



u. 



a. 

 u 

 Q. 



in 



X 



o 



a 



< 



o 



3.0 



2.0 



1.0 



0.5 



0.3 

 0.2 



0.1 



0.05 



0.03 

 0.02 



0.01 



^ 0.005 



< 

 o 

 JJ 0.003 



2 



"" 0.002 



< 



D 



3 0.001 



5 



0.0005 



0.0003 

 0.0002 



0.0001 



0.00005 



0.00003 

 0.00002 



0.00001 



200 400 600 800 1000 1200 



DISTANCE FROM ELECTRODE IN FEET 



1400 



1600 1800 



Fig. 5 — Cross Keys tests — mutual impedance gradient in vicinity of grounding 



electrode. Experimental curves. 



