550 BELL SYSTEM TECHNICAL JOURNAL 



where 



p' = y/ih-yY+x^ 



= distance of point in dielectric /row axis of wire. 

 p" = V{h-\-yy+x^ 



= distance of point in dielectric /row image of wire. 



e = sin-icVp") 



Q; = 47rXco. 



These values of r and 6 are, of course, to be employed in calculating 

 J = P-\-iQ from the formulas and curves of the preceding section. 

 As a special case the electric intensity at the surface of the earth is 



p" = VW+x"" 

 r = p"y/a 

 Q = sm-'{x/p") 



2. Self Impedance of Ground Return Circuit. (See equations (25) . 



(27), (30) ). 



Z = Zo+4co/ 

 Z'' = self impedance with perfectly conducting ground. 

 r^2h\/a 



e = o. 



3, Mutual Impedance of Ground Return Circuits. (See equations (26), 



(28), (31) ). 



Zi2 = Z52+4w/ 



Zi2 = mutual impedance with perfectly conducting ground. 



r = V^V{hi-\-h2Y-\-x^=p" Va 

 e = sin-i (.Vp")- 



The axial electric intensity Ez in the ground (v<0) is given by equation 

 (1), and the subsequent analysis, whence 



