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THE BELL SYSTEM TECHNICAL JOURNAL, JULY 1956 



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Hi 



Fig. 2 — Permeability versus magnetic field. 



Clearly, in employing a ferrite medium, we intend to use the basic dif- 

 ference between the scalar permeabilities ix^ and /i_ . To this end we may 

 exploit the fact that the magnetic field configuration at any given point 

 in a rectangular waveguide is, in general, elliptically polarized. Travel- 

 ing loops of magnetic intensity appear in Fig. 3 for the fundamental 

 (TEio) mode. At point P an observer sees a counterclockwise elliptically 

 polarized magnetic intensity if the wave is traveling in the (+y) direc- 

 tion.* The propagating wave may be decomposed into two oppositely 

 rotating circularly polarized waves of different amplitudes: 



+ O 



For propagation in the ( — y) direction the rj polarization is reversed: 



+ O 



Let us now consider the actual experimental configuration shown in 

 Fig. 4 (the partial height geometry was chosen on an experimental basis, 

 in that it gave VSWR considerably less than that for a full height ferrite 

 slab). The precession of the spin magnetic moments is counterclockwise 



* It is evident that a point converse to P exists symmetrically to the right of 

 center. This is utilized in a double slab isolator which has been investigated by fi 

 S. Weisbaum and H. Boyet, I.R.E., 44, p. 554, April, 1956. ' 



