OPEN-WIRE TELEPHONE LINES 



755 



If the two wires forming one of the sides of the phantom circuit are 

 designated 1 and 2, and the wires forming the other side are designated 

 3 and 4, the inductance of the phantom circuit is 



L = 0.32187 r 1.1513 log^o ^^f^;fl^^* + ^5 

 L LfnL>zia 



X 10~^ henrys per loop mile (13) 



where Diz, D23, etc. represent the spacing between the wires 1 and 3, 2 

 and 3, etc., and where d, ix, and 8 have the same significance as in Equa- 

 tion (3). 



The capacitance of a phantom circuit in space is 



C = 



0.07766 X 10-6 



log: 



10 



4DjsDuD23Du 



farads per loop mile. 



(14) 



20 30 



FREQUENCY— MLOCYCLES 



40 



50 



Fig. 18 — ^Attenuation of phantom open-wire circuits. 



