MUTUAL IMPEDANCE OF GROUNDED WIRES 



167 



quantities for X2/X1 = 10. When the depth b approaches the Hmits 

 zero and infinity, the ground condition approaches the hmits of 

 homogeneous ground of conductivities X2 and Xi, respectively. By 

 reference to Figs. 2 and 4 it will be seen that there is a wide range in 

 which the curves for other values of the depth are parallel to these 



0.0018 

 0.0016 

 0.0014 , 



UJ 



_l 

 O 



0.0012 o 



ct 



UJ 



0.0010 °- 



LiJ 



0.0008 2 



(T 



0.0006 ^ 



I 

 0.0004 O 



Fig. 2 — Imaginary component of mutual impedance gradient 

 for conditions of Fig. 1. 



limiting curves so that for a given frequency a properly chosen homo- 

 geneous ground conductivity leads to equivalent results. The equiva- 

 lent conductivity varies with the frequency, increasing or decreasing 

 with increasing frequency according as Xi is greater or less than X2; 

 this variation of apparent homogeneous conductivity with frequency 

 has been frequently observed in results obtained from mutual im- 



