A METHOD OF IMPEDANCE CORRECTION 



825 



o 



N 



0.9 



1.0 



1.2 1.3 1.4 1,5 1.6 1.7 



FREQUENCY IN ARBITRARY UNITS 



1.8 



1.9 



2.0 



2.1 



Fig. 14 — Susceptance correction of a set of parallel x-terminated band-pass filters. 



I — Uncorrected susceptance. 



II — Susceptance after the addition of a simple auxiliary network. 

 Ill — Susceptance after the addition of a more elaborate auxiliary network. 



Reverse Method of Designing Terminating Sections 



Hitherto we have assumed that the load impedance of the terminat- 

 ing network was the filter image impedance, and our procedure has 

 consisted essentially in determining an adjustment of the network 

 parameters which would make its input impedance a constant pure 

 resistance. As we have already seen, however, it is equally legitimate 

 to assume that the network is terminated in the line resistance, and 

 determine parameter values which will produce a match between its 

 impedance and that of the filter. This assumption leads to the circuit 

 arrangement shown in Fig. 15. 



Upon examining what happens to the general expression for the 

 resistance of the network when the load impedance reduces to the 



