NORMAL MODE BENDS FOR CIRCULAR ELECTRIC WAVES 1305 



If {ulf is equal to 3(C/5), 



a^ al4 _ / al^Y ^ 4B^ i - 2u 



du^ dp \dudl) ~ l^u (l-uy 



and 



dA 2B 1 - 2u 



Bu- 



lu (1 -uY 



Hence, if w < | or, because of (31) and (34) r < 1, a minimum of A{u, 

 I) is located at 



008 



01 



O 



_J 



- 0.06 



0.04 



0.02 



0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 30 

 COAT THICKNESS IN PER CENT OF THE GUIDE RADIUS 



Fig. 4 — 90° normal mode bend of |-inch I.D. copper pipe with a dielectric coat 

 of e' = 2.5, e" = 2.5 X 10~^ Optimum design for 5.4-mm wavelength. 



