FERRITES IN MICROWAVE APPLIC \TI()\. 



1353 



in obtaining a ferrite which gives the maximum rotation per unit loss, 

 and at the same time we are interested in obtaining such fundamental 

 information as the mechanisms of loss, the effect of composition, and the 

 relationship between the various physical properties of the ferrite crystals 

 and their microwave behavior. As a corollary interest we wish to relate 

 the microwave behavior of ferrites to their low frequency performance. 

 For convenience most of the microwave measurements have been made 

 in the 9,000 mc X-Band region, but 4,000, 24,000 and 48,000 mr. meas- 

 urements have been carried out by others in Bell Laboratories and some 

 of their findings will be reported here for comparison with those obtained 

 at X-Band. 



In the most common procedure the Faraday Rotation and attenuation 

 of a Hnearly polarized wave and the ellipticity of the resultant wave are 

 measured as a function of the intensity of the applied longitudinal 

 magnetic field. The experimental equipment used in these measurements 

 is shown in Fig. 10(a). A variety of sample shapes ranging from cylinders 

 completely filling the waveguide to very small cylindei-s suspended along 

 the axis have been measured. From these data the absorption of the 

 positive circular component may be obtained if one assumes that the 

 attenuation of the negative component remains constant as predicted in 

 the plane wave theory. This is not always the case, however, due to the 

 mode configurations sometimes present, and for this reason an alternate 



rectangular to 

 ^'"round transformers "^x 



ASSEMBLY ROTATES 



10 DB PAD QUARTER 



WAVE PLATE 



Fig. 10 — Block diagrams of the two most commonly used measuring set-ups. 



