448 



BELL SYSTEM TECHNICAL JOURNAL 



each at mid-series and mid-shunt. The first two sections are dis- 

 symmetrical as regards the two pairs of terminals. The two mid-series 

 sections are symmetrical and identical except for the structure of their 

 shunt branches, which, however, are equivalent impedances. Simi- 



Full-Serles 

 2, 



Ladder 



Mid-Series 



O oAfs^ o • o-^^^-o O 



FullShunt 



MidShunt 



2, 



-o-VWV*- 



•U/') 



XA/A/o 



\2Z, 



Lo/Uice 



Bridged-T 



zZoj 



0-4-o>VW*-«>- 





zZoj 



'■•Zr 



Types of general recurrent network sections. 



larly, the symmetrical mid-shunt pair have different series branches of 

 equivalent impedance. It may be of interest to point out that if each 

 of these sections is closed by a resistance, R, to form a two-terminal 

 network, then three pairs of these networks are seen directly from 

 series and parallel rules to be inverse networks; namely. 



7„, 7b; 7c, 7/; and 7^, 7, 



