An Experimental Dual Polarization 



Antenna Feed for Three Radio 



Relay Bands 



By R. W. DAWSON 



(Manuscript received April 26, 1956) 



The fundamental problems associated with coupled-wave transducers 

 which operate over a 3-to-l frequency hand have been explored and usable 

 solutions found. The experimental models described are directed toward the 

 broad objectives of feeding the horn-rcficctor antenna with two polarizations 

 of waves in the 4-, 6- and 11-kmc radio relay bands. 



INTRODUCTION 



There are at least two communications problems which require fre- 

 quency selective filters that operate in waveguides over an approxi- 

 mately 3-to-l frequency interval: (1) channel-separation filters for a 

 circular-electric waveguide system in which it is desirable to use the 

 medium from perhaps 35 to 75 kmc,^ and (2) band-separation networks 

 needed for the horn reflector antenna that permits simultaneous trans- 

 mission or reception in the 4, 6 and 11 kmc bands with both polariza- 

 tions.-- ^ The research reported in this paper was directed at deter- 

 mining the capabilities of coupled-wave transducers for solving such 

 problems. Experimental work was directed toward the second problem 

 (above) because it is more immediate. 



Fig. 1 , which is a schematic representation of the feed array, comprised 

 of three sets of directional couplers, shows that the -l-kmc bands are 



mB 



j:^ 



^ 1 - I M I i i _ I IE 



n — n H I _ .n — n N o 



D E J 



TT 



h 



K 



Fig. 1 — -Schematic of dual-polurizatioii feed for three microwave bands. 



391 



