896 THE BELL SYSTEM TECHNICAL JOURNAL, JULY 1956 



where AtMs is the saturation magnetization in gauss and y is the mag- 

 netomechanical ratio. The Polder tensor evidently remains unchanged 

 if Ms and H are both scaled directly with frequency. 



Since the field distributions are assumed unchanged relative to the 

 scale shift, normal and tangential E and H field components continue 

 to satisfy the appropriate boundary equalities at interfaces. Then, in- 

 voking the uniqueness theorem, the guide characteristics are only as 

 presumed and the model has been properly scaled as a function of fre- 

 quency. 



The scaling equations are: 



(V-3) 



where d is any linear dimension. 



CONCLUSION 



An isolator with low forward loss and high reverse loss can be con- 

 structed by a proper choice of parameters. Once a suitable design has 

 been reached the scaling technique can be used to reach a suitable design 

 for other frequencies. 



As yet, a theoretical analysis of this problem has been carried out only 

 for a full height ferrite. 



ACKNOWLEDGMENT 



We would like to thank F. J. Sansalone for his assistance in developing 

 the field displacement isolator. We would also like to thank Miss M. J. 

 Brannen for her competent handling of the numerical computations. 



APPENDIX 



It is desirable to establish an isolator figure of merit. A simple quan- 

 tity characterizing the isolator action is the normalized rate of power 



