1384 THE BELL SYSTEM TECHNICAL JOURNAL, NOVEMBER 1956 | 



This final approximation leads to the simple equations (7a) and (7b) of 

 Section III, namely: 



TMnm modes 



a + iA/3 



a(l - vY'''[l + tanV] 

 TE„;„ modes 



. . . ^ ^ (^ + iy) v'V [tan yp - n{l - vf^/yvf 



" ^ ^^ a(l - v'^yi'' {f- - ^2) [1 + tanV] 



where 



i 



