llVPER-FRliQUENCY WAVE GUIDES 



289 



unlike the nia^inetic field in a coaxial conductor such as shown in 

 Fig. 2. The F.i wave consists of electric and magnetic lines very simi- 

 lar in form to those associated with two parallel electric conductors 

 surrounded by a metallic shield. The similarity between the fields for 

 the two dielectric waves and the corresponding two arrangements 

 for ordinary transmission is made more obvious by a comparison of 

 Fig. 1 with Fig. 2. For the most part this similarity ends at this 

 point, however, as their corresponding properties follow quite differ- 

 ent laws. 



(a) coaxial conductor 



LINES OF ELECTRIC FORCE 



(b) shielded PAIR 



LINES OF MAGNETIC FORCE 



Fig. 2 — Approximate configuration of lines of electric and magnetic force in a 

 coaxial conductor and also in a shielded pair of conductors. Note similarity to £o 

 and El waves of Fig. 1. 



The configurations of the two magnetic waves are somewhat similar 

 to the electric waves provided we assume the electric and magnetic 

 components to be interchanged. Nature has thus far failed to provide 

 us with materials that possess exclusively magnetic conductivity in 

 the sense that copper possesses electrical conductivity so there are no 

 counterparts of Fig. 2 applicable to magnetic weaves. 



The general shape of the lines of electric force for all of these types 

 of waves have been calculated. These fields have also been verified 

 experimentally by means of a small probe consisting of a crystal 

 detector with short pick-up wires connected to a sensitive meter. 

 This probe was carried over the cross-section of the guide always 



