ih:Ki:G{i..iRmis i.\ loaded rr.i.r.riioxr. circl-its ?« 



lurvo shwts v;ivi' llu- iiUMMiivd \,iliRs of rrtiirn loss fmiinl in tlic 

 groups of liaiiils lisUtl in the i-xplanatory notes on the drawings. 



In general, it will Ik- observed that there is a fair agreement between 

 the theoretical curves and the measured rcliirn losses especialK- at 

 1000 and 21HH) cycles. 



Hue to the limited range of the measuring apparatus, readings of 

 return losses greater than 40.7 TU were not made except in the ca^e 

 of the Ligonier to Pittsburgh phantoms shown on Figs. 12, 13 and 14, 

 when a special arrangement was available to extend the range to 

 47.3 TU. For this reason points representing observed return losses 

 above these limits are not available which causes the observed values 

 for .")00 cycles in Figs. 9 and 12 to appear somewhat low at first sight. 



Where the highest point in a given set of data represents many 

 circuits as in the cases represented by the small triangles and circles 

 in Fig. 9 this point probably gives closely the return loss corresponding 

 to the percentage of circuits it indicates but the points for higher 

 return losses are not available. When the highest point represents 

 only one or two circuits as in the case represented by the square in 

 Fig. 9, it is likely that the actual return loss is higher than the point 

 inilicates. 



It should also be noted that above 40 TU the actual inipetlaiice 

 of the line and its characteristic impedance differ by less than 2 per 

 cent, so that very small departures of the network from the true 

 characteristic impedance of the line would tend to make the observed 

 return loss low. 



Conclusion 



It is believed that the procedure described in this paper offers a 

 reliable method for determining the probability of attaining a particu- 

 lar \'aluc of return loss at any assigned frequency when a circuit is 

 built with definite limitations on inductance and capacity deviations 

 so that the representative deviations are known. 



