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BELL SYSTEM TECHNICAL JOURNAL 



length section of line as a step-up or step-down transformer was 

 described. Hriefly the principle of operation is the fact that the 

 sending end impedance Zg and the receiving end impedance Zr are 

 related to the characteristic impedance Zo by the simple expression: 



Zj s^ r — ^0 • 



(8) 



Thus, by choosing the proper characteristic iinpedance any two real 

 impedances may be matched provided these do not dififer too greatly. 



IMPEDANCE TRANSFORMER 



Is I*- 



-<3 



zs 



zs-ol^ 



Zo 



Zo=ZsZr 





-Zr 



z.=z„l2. 



Fig. 13 — The principles underlying the use of one quarter wave-length bars as a 

 transformer are shown in the upper diagram. The lower illustration depicts a 

 commercial installation. 



Often the scheme is made workable by constricting the line spacing for 

 a one-quarter wave-length section. Where a large difference in trans- 

 former line and transmission line spacing is undesirable the transformer 

 line may comprise conductors of large diameter. A transformer set-up 

 of this type is shown in Fig. 13. 



There is another effective way for transforming line impedances by 



