COUPLED HELICES 



171 



written 



Ro — 



(i8o a cot \J/iY cot ^2 „ 

 (yaY cot 4/1 



[ 



= P02 - 



(jSo a cot \p2) D 



? Vi -^ 12 



Poi - 



(/3oa cot ^0" 

 (yay 



_ (29) 



11 



The solutions of this equation are plotted in Fig. 4.1. 



There it is seen that there are two values of 7, one, yt , denoting the 

 slow mode with transverse fields between helices and the other, yt , 

 denoting the fast mode with longitudinal fields midway between the two 

 helices. 



5.0 



4.S 



4.0 



3.5 



3.0 



ra 



2.6 



2.0 



1.5 



1.0 



0.5 



0.5 1.0 1.6 



2.0 2.5 3.0 



/3o a COT yj 



3.5 4.0 4.5 5.0 



Fig. 4.1.1 —-The radial propagation constants associated with the transverse 

 and longitudinal modes on coupled coaxial sheath helices given as a function of 

 |3oa cot ^i-i for several values of hja = 1.25. 



