520 



BELL SYSTEM TECHNICAL JOURNAL 



of two dimensional wave propagation theory. The specific case of 

 four wires in a square array was selected as the basis of a comparison of 

 measured and theoretical values of mutual inductance. The configura- 

 tion with four equal wires is shown in cross section in Fig. 4 where 

 wires No. 1 and No. 4, centered at 0] and d and carrying currents 

 I\ and — /i, respectively, form the first pair or primary and wires No. 2 

 and No. 3 at Oi and O3 and carrying currents I^ and — h, respectively, 



0.7 

 0.6 

 0.5 

 0.4 



0.2 



0.1 







-0.1 



300 400 500 600 700 800 



FREQUENCY IN KILOCYCLES PER SECOND 



900 



1000 



3 4 5 10 20 30 40 50 100 200 300 



FREQUENCY IN KILOCYCLES PER SECOND 



1000 



Fig. 5 — Real and imaginary components, Ma and Mb, respectively, of the mutual 

 inductance between a pair of No. 10 A.W.G. wires and a pair of filaments. Length 

 of wires = 74 inches; mteraxial separation = 0.14 inch. 



i 



