ELECTRIC WAVE-FILTERS 



321 



and its terminating resistance R will produce only a small effect upon 

 the impedances at the other terminals. As a result the latter imped- 

 ances will be approximately equal to W^k and W-k in the attenuating 

 bands also. Higher order transducers might also be used.''' 



Ajuhjuch /lijirmlated^ W,h, 



1, 



.36/5 Z,^ 



— o-VW-° — 



1646 Z,h 1-^79 Z^j, 



.Z355z,f,l .maz.H, 



n 



Mlob-hhu/nb ifmp^edojrhce /miAjjovh 



.5110 Z;/, 



z. 



\z.766z2fi, 



a.Z8z ZzH, 



7Z50Z,j, 



6.076Z2h 



6.69JZ^^ 



R 



Fig. IS — Impedance networks which simulate the image impedances, W\k and Wik, 

 of "constant yfe" and related wave-filters of any class. 



With this explanation of their origin the general impedance 



networks of Fig. 15 have been assembled. One of impedance Zi 



simulates the image impedance \\\k\ the other of impedance Z2, the 



image impedance W^k. The degree of simulation attained can be 



seen from the characteristics of Fig. 16, wherein the effect of small 



dissipation is included by assuming Vk = -\- -OlC/fc in a negative 



branch and Vk = - .01 1/^ in a positive branch, as before. Over most 



of a transmitting band the agreement is within a few per cent; outside 



it is still quite satisfactory. Near the critical frequencies, where 



" Still other forms of networks have been considered by R. Feldtkeller in a paper 

 "Uber einige Endnetzwerke von Kettenleitern," Eleklrische Nachnchlen-Techmk, 

 Band 4, Heft 6, p. 253, 1927. 



