DIELECTRIC-COATED WAVEGUIDE 



1271 



-130 



-120 



-110 



-100 



-90 



LU 



?-80 



Z-70 



a. 



UJ 



p-60 



5-50 



_i 



-40 



-30 



-20 



-10 



0.1 0.15 0.2 0.3 0.4 0.5 0.6 0.8 1.0 1.5 2 3 4 



COAT THICKNESS IN PER CENT OF THE GUIDE RADIUS 



Fig. 8 — Higher circular electric waves at a transition from plain waveguide 

 to the dielectric-coated guide, e = 2.5; a/X = 4.70. 



Fig. 8 shows an evaluation of (34) for a/X = 4.70 and e' = 2.5 correspond- 

 ing to a 2-inch pipe with a polystyrene coat at X = 5.4 mm. 



VI. SUMM.\RY 



A theoretical analysis of wave propagation in the dielectric-coated 

 guide is presented to provide information necessarj'- for circular electric 

 wave transmission in this waveguide structure. The normal modes of a 

 waveguide with a thin dielectric coat are perturbed modes of the plain 

 waveguide. While the perturbation of the phase constant is only of third 

 order of the coat thickness for the circular electric waves, it is of first 



