FERRITES IN MICROWAVE APPLICATIONS 



1335 



Equations giving ^ and k in terms of the applied magnetic field and 

 the fundamental atomic constants are given by Hogan.^ These equations 

 show that both ^ and k have a resonance at a value of effective internal 

 field given by yH = 27r/. If H is in ampere turns per meter and /in mega- 

 cycles the gyromagnetic ratio is 7/27r = 3.51 X 10~l 



A plane wave travelling in the z direction in an infinite medium de- 

 scribed by equations (1) can be resolved into two counter-rotating cir- 

 cularly polarized plane waves having propagation constants as follows: 



r+ = icoV/xoeo VeC/x - k) r_ = jojv^o Ve{n + k) (4) 



where the subscripts zb refer to positive and negative circularly polarized 

 waves.* The terms inside parentheses are effective scalar permeabilities 

 completely describing the medium for a circularly polarized wave. Cal- 

 culated values of these effective permeabilities are plotted as functions 

 of applied field in Fig. 1 for a ferrite operating at three frequencies. 



-2.0 



:i -1.0 



100 

 50 

 

 -50 



1000 2000 3000 4000 5000 6000 7000 8000 9000 lO.OOO 



EFFECTIVE MAGNETIC FIELD IN OERSTEDS 



Fig. 1 — Calculated effective permeabilities for positive and negative circularly 

 polarized plane waves computed for three different wave frequencies. 



2 C. L. Hogan, Revs. Mod. Phys., 26, Jan., 1953. 



* A positive circularly polarized wave is one which rotates in the direction of 

 the positive current producing the dc magnetic field. 



