ELECTRIC WAVE-FILTERS 



305 



or may not be in the range from Uk = to — 1 one maximum for 

 W],k{m) and one minimum for W^him). The image impedances at the 

 other mid-points are independent of m and are identical with those of 

 the "constant ^" wave-filter already shown in Fig. 3. 



Af^m 



-1 



Ifr) 



-I 

 (frJ 



u,. 



Fig. 7 — Characteristics of M-type wave-filters; 



m = .6. 



{Wxk and Wik are illustrated in Fig. 3. Broken lines indicate the effects of dissi- 

 pation.) 



1.8 MM'-Type Wave-Filters 



As wave-filters of the second order in each sequence they have two 

 parameters, m and m' . Their series and shunt impedances are derived 

 by means of the single operations with parameter m' performed in the 

 regular manner upon the iU-type structures as prototypes which have 

 the formulas (13) and (14). 



