494 



THE BELL SYSTEM TECHNICAL JOURNAL, JULY 1951 



constant over a low range of frequencies and then rises at a rate propor- 

 tional to the square root of the frequency. The laminated Une has a higher 

 initial attenuation, but remains constant to higher frequencies. At high 

 enough frequencies the attenuation of the laminated Hne rises at a rate di- 

 rectly proportional to frequency for a while, and then eventually approaches 

 the attenuation of the unlaminated line. 



The frequency at which the attenuation of the laminated Une begins to 

 increase is greater than the corresponding frequency for the conventional 

 line by a factor 



^(0© 



SOLID CENTER 

 CONDUCTOR 



^=f 



77-fytZo 



n 



9*- 

 o< 



cr 



QL 



1 



1 

 (TD 



LAMINATED CENTER 

 CONDUCTOR 





V3 



7T/Uo(rD^ 77-//o^WD FREQUENCY 77//o^W2 



Fig. 2 — Comparison of conventional and laminated transmission lines. 

 This is accomplished with an increase in initial attenuation by a factor 



which we will see later will be about 3/2 in a typical case. We might make 

 a corresponding increase in the flat range of the conventional line by de- 

 creasing <7 to a new value ai. In that case the attenuation would be increased 

 by a factor 



^(i)Q 



which may be very large since ( ^ ) ( ^ ) is just the number of laminations 

 of conductor or dielectric used on the center conductor. 



