448 THE BELL SYSTEM TECHNICAL JOURNAL, MARCH 1957 



we have a relationship between the change in (l/Q) and the loss terms 

 Xm" and k" 



A(l/Q)± = ^ ^ (xJ'i^i ± k"R2) (A151 



Clearly, (A 15) holds only if the initial Q of the empty cavity is very 

 high and the change in Q is quite small. 



The electric susceptibility of the ferrite disc can be obtained in a 

 similar way, provided we place the disc at the cavity center where the 

 electric field has a maximum. Then, the additional electric energy 

 stored in the disc is found to be 



We'-' = 0.2387 ^ Moxe p B'ahR^ (A16) 



It should be noted that there is an important difference between loca- 

 tion of a thin disc at the endwalls and at the center of a C3'lindrical 

 cavity. Whereas the electric field at the endwall may be neglected en- 

 tirely, the magnetic field at the cavity center has a component parallel 

 to the cavity axis. The effect of this component bn the stored energ}' in 

 the disc may be minimized by magnetizing the disc beyond saturation in 

 the ^-direction. 



With the assumption that the effects of the magnetic RF field may be 

 neglected we obtain relationships for the electric susceptibility and 

 electric loss factor: 



2(AC./C0o) - jMl/Q) = iXe' - jXe") ~{ /?! (Al7) 



Since Xe is a scalar quantity there is no splitting of the cavity resonance^ 



j 



ACKNOWLEDGMENT 



We would like to thank L. G. ^"an Uitert who supplied the ferrite ma- 

 terials, Barbara De Hoff who did all of the numerical computation and 

 Edward Kankowski who made most of the measurements shown herein. 



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