ELECTRIC 1 1 VI T 'E-FIL TERS 



291 



A mid-series section is that part between the mid-point of one series 

 impedance Zi and the mid-point of the next series impedance. It has 

 the three impedance branches hzi, Zo, and i-i and has the structure of a 

 T-network. Its image impedance at each end is the mid-series image 

 impedance Wi. 



A mid-shunt section is that part between the mid-point of one shunt 

 admittance I/S2 and the mid-point of the next shunt admittance. It 



-o-/\AAr-o- 



Midy-Ahw)iL xjCeniiKLtwrYv 





Fig. 1 — -Fundamental derivations. 

 < 5< 1. 



has the three impedance branches 2^2, Si. and Izi and has the structure 

 of a TT-network. Its image impedance at each end is the mid-shunt 

 image impedance W^. Both of the above symmetrical sections have 

 the same transfer constants, 7", as we should expect since both sections 

 represent one full interval of the ladder type structure. 



