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BELL SYSTEM TECHNICAL JOURNAL 



of the short, small aperture horn used in feeding the dish antenna. The 

 antenna displayed an effective area which was 66% of its actual area which 

 is only 0.9 db below the theoretical, maximum. 



PARABOLOIDAL 

 SURFACE 



AXIS OF REVOLUTION 

 OF PARABOLOID 



j^^-~._ FOCAL POINT 

 OF PARABOLA 



Fig. III-2. — Schematic of horn-reflector antenna. 



Fig. III-3. — Experimental model of horn reflector antenna. 



The expected gain and directional characteristics of an antenna can be 

 realized only if the emerging wave fronts are truly plane. Since deviations 

 greater than d: ^ wavelength can materially impair the antenna perform- 



