574 BEI.L SVSTF.M TECIISICAI. JOURNAL 



RkTLKN I.OSSl.S ()!■ SllOKT l.iNi;s 



When a line is short and reijularly terminated the returned current 

 will be somewhat less than if it extends to infinity with irregularities 

 and consequently the return loss will be higher. I'rom equations (29) 



and (80), the returned current is lowered in the ratio , = s/X—A*" 

 by limiting the line to n sections; consequently 



Sn = 5+ {S„ - 5) = .S+ 10 \ogyoY-A^" ^'*'^^ 



in which 



5„-5= 10 login, \.„ (48) 



is the increase in return loss. 



Since the transmission loss in n sections of the line is 



y=20 1og,„J„ (49) 



it is easily seen th.it the increase of return loss can be expressed as a 

 function nf this loss, 'transposing (49) and substituting in (48) 



.S-„-.S=10 1og,„^^|_ ^^ _j,. ^^^^ 



|_log ,02,J 



("lI.\KTS 



The process of computing return losses can be greatly shortened 

 Ijy using the graphs of equations (43), (44), (45), (46), and (50) to 

 obtain the values of the various functions. The accompanying 

 I-igs. '.i to 8, inclusive, have been prepared to illustrate these graphs 

 and for use in rough calculations. 



Sii may be obtained from any (able or ch.ut giving the relation 

 between TU and current ratio by using // like a current ratio. Fig. 3 

 is a chart drawn es[iecialK' for this jjurpose. For values of // lying 

 between 0.1 and (1.(11 look up a point on the curve corresponding to 

 10// and add 20 11 in ihc corresponding value of Su, for values of 

 // lying between 0.01 and 0.001 look up a point corresponding to 

 100// and add 40 TT to the value of 5//, and so forth. 



Figs. 4, 5, G, and 7 are curves giving the relations between the 

 functions Sv, Sp and Sa, respectively, and the quantities upon which 



