784 



BELL SYSTEM TECLINICAL JOURNAL 



typical image impedance ^ characteristic of the next more compHcated 

 structure (Fig. \2-B) is shown on Fig. 13. The vertical scale of this 

 figure has been made considerably larger than that of Fig. 4 in order 



N 



UJ 



I.UA 



1.03 



.02 



1. 01 



O 1-00 



z 

 < 



I- 



g 0.99 



Q 



Z 



o 



U 0.98 



0.97 



0.96 



0.95 



0.04 



0.03 



0.02 



0.01 



-0.01 



N 



X 



UJ 



O 



z 

 < 



1- 



Q. 

 LU 



u 



-0.02 ^ 



-0.03 



-0.04 



-0.05 



0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 



X 



Fig. 13 — Typical image impedance characteristic of a 2-branch termination 



(Fig. 12-5). 

 I — Real component. 

 II, III and IV — Various possible imaginary components. 



24 



UJZ 

 OUJ 



ou 



o^ 

 uz 



Ul ~ 



_l 

 u. 



a. 



16 



10 



12 



14 



16 18 20 22 24 26 



FREQUENCY IN KILOCYCLES PER SECOND 



28 



30 



32 



Fig. 14 — Schematic and reflection coefficient of a low-pass filter with 2-branch 



terminations. 



^ The fact that the so-called "image impedances" of Figs. 12 and 16 contain 

 slight imaginary components, in defiance of the fact that the image impedance of a 

 reactive network is never a complex quantity, is traceable to the method used in 

 analyzing the structures, which will be more fully understood from the discussion 

 in the accompanying paper. The curves actually represent the impedance of the 

 section when they are terminated in the filter image impedance. The reason for 

 showing several curves for the imaginary component will be brought out later. 



