12 



THE BELL SYSTEM TECHNICAL JOURNAL, JANUARY 1952 



It is almost impossible to get a feeling for what these equations mean 

 with respect to a wave travelling through the medium, especially since 

 ju and K are given by equations which are almost as difficult to per- 

 ceive. An appreciation of these equations can be obtained however, by 

 reference to Fig. 4 which gives qualitatively the behavior predicted by 

 these expressions. Essentially, a and (3 are functions of two variables. 

 These are co, the frequency of the wave, and Ha , the applied magnetic 

 field. In Fig, 4, the index of refraction and attenuation of the positive 

 circularly polarized component are given relative to these values for 



X > 



111 (T 



Q< 



z a. 

 - H 

 •a m 



APPLIED MAGNETIC FIELD (ARBITRARY UNITS) 



Fig. 4 — Index of refraction and absorption of a positive circularly polarized 

 wave relative to the same quantities for a negative circularly polarized wave 

 being propagated through a magnetized medium. 



the negative component. Hence, both the index of refraction and 

 attenuation of the negative component are represented by the abscissa 

 of the graph. In Fig. 4 these quantities are plotted as a function of the 

 apphed magnetic field for a wave of a fixed frequency. Many of the 

 properties of the medium are clearly displayed in this graph. In partic- 

 ular, as the field necessary for ferromagnetic resonance is approached, 

 the attenuation of the positive component becomes larger and larger. 

 Eventually this component will be substantially completely absorbed 

 and only the negative circularly polarized component will be propagated. 

 Hence it should be possible to establish a circularly polarized wave in a 

 waveguide simply by passing the dominant mode through a ferromag- 

 netic material which is subjected to a longitudinal magnetic field of the • 

 proper amplitude. However, there will be an absorption of one-half 

 of the power being propagated. If Fig. 4 had been plotted as a function 



