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BELL SYSTEM TECHNICAL JOURNAL 



The characteristic impedances, K 2 i(m) and Kx 2 (m), follow from 

 the substitution of (19) and (21) in (1), and are given by the relations 



R 



K 21 (m) 



K l2 {m) 

 R 



1 + i* 



1 + 



(1-ra 2 ) Zik 



(22) 



4 z 2 k 



Fig. 5 shows graphically how this impedance ratio, neglecting dis- 



1.5 

 1.4 

 1.3 

 1.2 

 1.1 

 1.0 

 .9 



-1.0 -.9 



.7 



-.3 -.2 



Fig. 5 — M-Type Characteristic Impedances in Transmitting Band 



sipation, depends upon m in any transmitting band. For the limiting 



respectively. 



K K 



values m = 1 and m = it corresponds to —^ and 



For the intermediate value m = .6 it, and hence K 2x {m) and Ki 2 (m), 

 is approximately constant over the greater part of the transmitting 

 band thereby approaching the ideal sought. A wave-filter network 

 having these latter terminations could then be connected between 



