Constant Resistance with Applications to Filter Groups

NE of the m o s t useful principles available to the n e t w o r k design engineer is t h a t of c o n s t a n t resistance networks. T h e use of these networks is widespread in the telephone system for purposes of loss e q u a l i z a t i o n a n d d i s t o r t i o n c o r r e c t i o n , w h e r e t h e y h a v e t h e a d v a n t a g e of providing a m e a n s for altering the transmission properties Z, ·WW z2 R Z| LATTICE SHUNT SERIES Fig. 1--The three fundamental forms of constant resistance networks. of a circuit w i t h o u t affecting its impedance.1 T h e three usual types o f c o n s t a n t r e s i s t a n c e n e t w o r k s a r e s h o w n i n F i g . 1 , w h e r e , i n all c a s e s , Z i Z 2 = R 2 , a r e l a t i o n s h i p w h i c h is a l w a y s p o s s i b l e to fulfill if 1 " Distortion Correction in Electrical Circuits with Constant Resistance Recurrent Networks," Otto J. Zobel, Bell Sys. Tech. Jour., July 1928.