WAVKC.UIDK AS A fOMMUXICATK )\ Mi;i)irM 



1251 



circular olectrie wave family have wall ciirrcnts in the loiigitiidiiuil (iirco- 

 tion and oxperienec con-sidcrahly increased loss in the spaced-rinii slruc- 

 t are compared to a solid-walled wavi'ji;uide. A. (".. i'ox lirst ohserxcd lliat 

 the spaced rinp; structure could \)o used to transmit circular electric 

 waves around bends, and since that time additional work has been car- 

 ried out by A. P. King and M. Aronoff . The observed loss for the spaced- 

 rins structure under ])ro])er conditions was observed to be about ()() per 

 cent more than the theoretical loss for an ideal copper tube, whereas the 

 observed loss for the unused modes of propagation was on the order of 

 1,000 to 5,000 times the circular electric wave value. 



The spaced-ring structure therefore has the electrical properties we 

 seek. The higher-order circular waves exist with losses comparable to 

 their values in a solid copper pipe, but fortunately the magnitudes of 

 conversion between the waves of the circular-electric family have been 

 found to be small. The spaced-ring structure does present some difficult 

 problems with regard to fabrication. 



An analogous structure composed of a continuous helical conductor 

 supported within a lossy housing has electrical properties which approxi- 

 mate tho.se of the spaced-ring .structure, and the helix should be con- 

 siderably easier to manufacture in long lengths. The helix might be 

 expected to support a wave-type approximating the circular electric 

 wave both from the standpoint of field distribution and loss when one 

 observes that a helix of very small pitch presents almost circumferential 

 conductivity as required by the circular-electric wave, and the very small 

 longitudinal component necessary due to the finite wire size tends toward 

 zero as the helix pitch tends toward zero. James A. Young of these 

 laboratories has constructed helices in the 2 db/mile waveguide size (4.73" 

 diameter at 9,000 mc) and found a heat-loss coefficient on the order of 

 1.75 times the theoretical value for ideal copper pipe. These large ex- 



B-B A-A 



Fig. 26 ■ — Spaced-ring circuhir electric wtivoguide. 



