MEASUREMEXT OF DIELECTRIC AHD MAGNETIC PROPERTIES 



429 



magnetic susceptibility Xm is known to have tensor properties. Assum- 

 ing that the static magnetic field Hr is in the ^-direction we have 



Xm — 



(1) 



If we restrict ourselves to sinusoidal time variation of the RF fields we 

 may describe electric and magnetic losses in the ferrite bj' regarding 

 Xe , Xm , and K as complex quantities: 



Xe Xe 



Xm ^^ X" 



JXe 

 ■ jXr. 



^ = k' - Jk" 



Thus, it is seen that the RF properties of a ferrite medium regardless of 

 geometry are completely described by six "intrinsic" parameters, 

 Xe', Xe" , Xm , Xm" , K , SLiid k" . The diclectric constant e and permeability 

 TT of the material are obtained from 



£ = Xe + 1 



"m = x^ + 1 



where 1 is the unit matriix. 



It is the objective of the measurement to obtain each of the above 

 parameters as a function of one or more variables of interest such as 

 frerjuency, saturation magnetization, static magnetic field, temperature, 

 applied power and others. Aleasurements may be made on single ferrite 

 crystals — ■ mostly for research purposes — or on polycrystalline ma- 

 terial for many purposes in connection with the development of ferrite 

 materials and devices. These measurements are generally compared to 

 the behavior of Xm and k as predicted by Polder's equations. One ob- 

 tains from the equation of motion of magnetization^ 



Xm = M — 1 = 





CO' 



(0 





\y\M. 



ym,^ - 0,2 



Using Suhl and Walker's notation this may be WTitten as 



_ po- 



Xm ~ft "7 



(T^ — I 



V 





- 1 



