640 BELL SYSTEM TECHNICAL JOURNAL 



3'22 = T2 ti^2 + jpi] 



oonio 

 In order to compute y-n , the following four-pole equations are used: 



h I I "2}'! 2 



y'n y'n 



,. -^1 I ^ 2J12 

 I 1 — — -r 



yn yn 



Fi 1 - >'iii?s 

 3^21 can be evaluated by making use of the relation 



n ^ 4 + ^' 



>'22 >'22 



Dividing (17) by V2 and rearranging terms 



}'22 



722 r r' -1 



where /2/F2 can be expressed as 



1 



1 



F2 66m2Zo 66w2 



(9) 



(10) 

 (11) 

 (12) 



(13) 

 (14) 



(15) 



(16) 



(17) 

 (18) 

 (19) 



where Zo = 1- 



F(/F2 can be expressed in terms of 721 , nii , and ;;/o by using the relations: 



1 1 _ . /66mi ^ 2 _ /66 



66m2 



(20) 



