IMPEDANCE CORRECTION OF WAVE FILTERS 



in 



pedance characteristics such as those shown in Fig. 4:-A or Fig. 4-5 face 

 the block type image impedances of the same figure. In the system of 

 Fig. 5, for example such junctions occur at B, C, D, E, and to some 



Fig. 4 — Image impedances of "constant-^" and "m-derived" low-pass and band-pass 



sections. 

 Figs. 4-A and 4-B — "constant-^" sections. 

 Figs. 4-C and 4-D — "m-derived" sections. 



extent at yl. It is evident, of course, that reflected waves will be 

 produced at these points, and since impedance differences occur at 

 several junctions a wide variety of multiple reflections may exist. 



UPPER 



BAND PASS 



FILTER 



LOWER 



BAND PASS 



FILTER 



TO VOICE FREQUENCY CIRCUITS 



MODULATOR 



DEMODULATOR 



Fig. 5 — Simplified circuit diagram of a typical carrier terminal. 



Upon reaching the line terminals, all of these reflections combine with 

 the wave originally propagated to determine the actual current enter- 

 ing the structure. The reflected waves are of course diminished in 



