618 



BELL SYSTEM TECHNICAL JOURNAL 



In the foregoing, the behavior of an active four-pole has been described 

 either in terms of four-pole parameters or in terms of elements of an equiva- 

 lent circuit. The particular four-pole parameters, which are of customary- 

 use in communication engineering, are the so-called image parameters, but 

 they have usually been used only in connection with passive four-poles. 

 They may, however, also be used in the more general vacuum tube four-pole 

 now under discussion, but whether their employment would be of practical 



Table VI 



Four-Pole Parameters for Grounded Plate Triode in the Range of 

 Moderately Low Frequencies 



4 



1 (coCi)2 



5 



Ctf+ G 



^2 = - 





+ io3 





1 +- 



1 (a)Ci)2 

 5 



Cif 



I •[-!(■ n^')j'^-K-i-:') 



Pn 



1 + 



1 + 



14- 



+ ^-G 



\ 3xi / fi\ 3«;i/ 



1 + 



1 X2 



— F 

 HXi 



m\ 3xi /_ 



1 + 



/3i2 -{■ /Sai = 



^0 



1 + 



(-!?') 



X2 



11 



i—di 

 30 



11m 



1 + 





'5"^* 



value is a matter which engineering experience will decide. In any case 

 their use would be limited to vacuum tubes in which appreciable interaction 

 between input and output terminals is present. From a practical standpoint 

 this means that their usefulness would be mainly found in connection with 

 triodes. 



Triode Networks at Moderately Low Frequencies 



The networks discussed in the preceding section were of general validity 

 in respect to both operating conditions and frequency and it was mentioned 



