Line current reculaiion 



63J 



bridge arms are already loo large by approximately 14 olmis and 1170 

 ohms will be recjuired at points (2) to bring the line current down to 

 .070. The bridge arms will then be 1484 ohms greater than needed for 

 maximum received current. The question then arises as to why ar- 

 rangement (2) results in the subtsantial received current gains with lines 

 of low resistance, as shown by curves i\, i^ and i^, Fig. 2. This part of 

 the problem can best be solved by plotting equation (10). Fig. 3 shows 

 this equation plotted for a 1200 ohm line. It will be seen that, from the 



Fig. 3 



standpoint of received current strength, it is better to ha\e the bridge 

 arm too great than too small, as the received current rises rapidly to a 

 maximum and then descends slowly. On the other hand, if resistances 

 be added at points (1) or (3), the operating point on the received cur- 

 rent curve will in all cases be moved further away from the maximum, 

 and this movement away from the maximum will take place on the 

 side of the maximum which has the greatest effect in reducing the re- 

 ceived current, as will be shown. 



The resistance at points (1) or (3) moves the operating point on the 

 received current curve away from the maximum due to the fact that 

 the value of the bridge arm resistance corresponding to maximum 



