WAVEGUIDE TRANSMISSION 



341 



guide could be devised where this type of attenuation alone exists, we 

 could then operate the guide at extremely high frequencies and thereby 

 obtain relatively low attenuations. This can, in effect, be done. It calls 

 for a guide of circular cross section and a special configuration, known as 





I I '>• . • 



iLi . 



o."!- 



_o ^ 



. !i ■ 



9 ^.*^f' I 



_o_o ^ _^ 9' 



I 



c-d d 



■LINES OF ELECTRIC FORCE 



K; -;>ir'-,^ vt^ 



.x\^\\^^^^^^^^^^^^^'^^ 



TE^ WAVE 

 01 



LINES OF MAGNETIC FORCE 



• TOWARD OBSERVER ©AWAY FROM OBSERVER 



Fig. 6.5-5. The circular electric or TEoi configuration in a circular waveguide. 



(d) (e) 



Fig. 6.5-6. Evolution of the circular-electric wave in a circular pipe from a dominant wave 



in a rectangular pipe. 



the ciradar-eleclric wave. In this conliguration, the resultant electric force 

 is everywhere parallel to the conducting boundary as shown in Fig. 6.5-5. 



That such a wave will lead to the interesting frequency characteristic 

 noted is made more plausible by referring to Fig. 6.5-6 and its associated 

 discussion. Figure 6.5-6(a) shows a conventional form of rectangular 

 guide in which plane waves are multiply reflected from the two short sides. 



