REGULAR COMBINATION OF ACOUSTIC ELEMENTS 

 r = Xi, we find 

 ^ -P 



275 



= - Wp. 



oTP 



(32) 



If we substitute this value of Zs in equation (21), we can readily 

 determine the value of F and Zq. Fig. 7 shows a plot of ^ and B for 

 this case assuming (x2 — Xi) = L. 



1.0 2 5 



VALUE OF ^ 



35 



Fig. 7 — Propagation constant of a low pass type of filter. 



IV. Tapered Filter Structures and Horns 



In addition to recurrent filters, other types of filters exist. If, for 

 example, we connect sections with the same propagation constants and 



