DISTORTION CORRECTION 497 



different proportions make up the network. It consists of a com- 

 posite lattice network of two sections having four real, positive 

 parameters, Wi, m2, m/, and m2 , two in each section. 

 In the first section put for the series impedance 



2u = — ^- r~ • (78) 



— 1 — 



IntiZa 2zblin2 



To satisfy the condition for the desired iterative impedance at all 

 frequencies, 



K = -V211S21 = k = V^, (79) 



it follows that the lattice impedance must be 



m2Za I Zb ,_„. 



That is, 2ii and 221 are also inverse networks of impedance product k". 

 The propagation constant, by generalized (13) (that is, R replaced 



by K), is 



^ _ 1 + ntiy + mim^y'^ . 



1 — niiy + niiniiy^ ^ ' 



where for convenience y = -yjzjzb = yl = propagation length. 

 In the second section, similarly, 



1 



2ii = 



' + ' 



2miZa 2zb/m2 



../=^- + :^. (82) 



and 



p, _ 1 + mxy + mi'm^y'^ 

 1 — mi'y + mimi'y^ 



For the composite structure made up of these two sections in 

 tandem, the iterative impedance condition is already fulfilled inde- 

 pendently of the values of the coefficients, since (79) holds for each 

 section. Its propagation constant is given from (81) and (82) by 



pVc — oT+T' 



1 -f {nil + mi)y -f (miW2 + mim/ -f mim2)y'^ 



+ {mim^mi + mimim2)y^ + m^m2niim2y' ^ 



1 — (mi + mi')y + (wim2 + mim/ + mi'm2)y'^ 



— (miW2mi' + mim/m2')/ + mim2mi'm2y^ 



(83) 



