1150 THE BELL SYSTEM TECHNICAL JOURNAL, SEPTEMBER 1954 



1.2 



0.8 



0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 



Fig. 1 — Propagation constant of a circular guide containing an unmagnetized 

 coaxial, dielectric rod (e/eo = 10). ri is the radius of the rod and ro the radius of 

 the guide, ro = 0.4Xo , where Xo is the free space wavelength. 



The computed values of Q and P — Q are shown in Fig. 3 as a function 

 of relative rod radius. P — Q is plotted since P and Q are very nearly 

 equal.* 



1.3 Perturbations Non-Uniform in z 



So far we have been concerned only with structures indefinitely ex- 

 tended in the direction of wave propagation. In practice the non-recipro- 

 cal element is, of course, finite, but end effects can frequently be ne- 

 glected, since the element is matched at its ends (by tapering of the finite 



* H. Seidcl and Miss M. J. Brannon, at the suggestion of M. T. Weiss, have i-e- 

 cently calculated the dielectric loss for the guides containing a dielectric rod de- 

 scribed above. By combining such information with that obtained here it is possi- 

 ble to discuss figures of merit (degrees of rotation loss in dli) for various pencil 

 radii. Such an analysis is being made by M. T. Weiss and will appear in an ar- 

 ticle, by S. E. Miller, A. G. Fox and M. T. Weiss, in a forthcoming issue of the 

 Journal. 



