AN EXPERIMENTAL DUAL POLARIZATION ANTENNA FEED 



399 



the 11-kmc band; thereby low transfer loss is obtained in the 6-kmc band 

 and a high transfer loss in the 11-kmc band. Measurements have shown 

 that when the cut-off frequencies of higher modes occur in the band of 

 interest an uncontrolled increase of coupling may result. Special precau- 

 tions are recjuired in selecting the round guide size to avoid this condi- 

 tion. The design process is shown in Appendix I. Figs. 6 and 7 show the 

 transfer and insertion losses in the G-kmc; band. 



16 



UJ 



m 

 o 



UJ 



o 



14 



- 12 



tn 

 O 



z 

 o 



I- 

 cr 



UJ 



If) 



z 



10 



5.6 



5.8 



6.0 



6.8 



Fig. 7 



6.2 6.4 6.6 



FREQUENCY IN KILOMEGACYLES 



- Insertion loss of 6-kmc coupler. 



7.0 



7.2 



SLOT SI ZE= 0.740" X 0.0786" 



SPACING= 0.780" 



POST DIA = 0.300" 



GUIDE SIZE= 1.724" X 0.872" 



COUPLING ARRAY CONSISTS 

 OF 38 FULL SIZE SLOTS 8. 

 6 REDUCED SIZE SLOTS 



Fig. 8 — 4-kmc coupler sketch. 



