AN EXPERIMENTAL DUAL POLARIZATION ANTENNA FEED 403 



28 



26 



^ 24 



_i 



UJ 



UJ ^'^ 

 Q 



Z 



20 

 (/) J. ' 



q 30 



28 



26 

 10.6 



3.8 



3.9 4.0 



4.1 



4.2 



36 



34 



32 



30 



28 

 4.3 5.9 



6.0 



6.1 



6.2 6.3 6.4 6.5 



10.7 



10.8 



10.9 11.0 11.1 11.2 11.3 11.4 11.5 



FREQUENCY IN KiLOMEGACYCLES PER SECOND 



11.6 



11.7 



11.8 



Fig. 13 — Transfer losses in the array for non-coupling polarization. 



soldered to the round guide. The coupling slots were then cut through 

 the common wall. An electroforming technique was used to fabricate 

 the 6- and 11-kmc couplers. A rectangular guide with precut coupling 

 holes was clamped to a round mandrel and the entire structure was 

 electroformed. The mandrel was later removed by dissolving it in a hot 

 concentrated solution of sodium hydroxide. A typical mandrel and 

 rectangular guide is shown in Fig. 14. An illustration of the entire 

 ensemble appears as Fig. 15. 



DESIGN REFINEMENTS 



Return loss at the round Port P might be improved in a revised 

 design by broad-banding the TEio°-TE]i° transfer loss, with an asso- 

 ciated increase in the TEii° insertion loss. This might be done without 

 introducing mode troubles, by using ridged wa\eguide. In Fig. 12 the 

 abrupt peak of transfer loss for coupling polarization waves in the 11 



Fig. 14 — Mandrel and rectangular guide. 



