A high-performance line source feed for the AIO spherical reflector

An aberration-correcting line source feed has been designed, modeled, constructed, and tested in the Arecibo reflector. The feed is a linearly polarized flat wavegnide 40-foot-long array illuminating 700 feet of the 1000-foot-diameter spherical reflector at 318 MHz. The antenna, illuminated by the new feed, yields an aperture efficiency of 70 percent with a peak gain near 56 dB, half-power beamwidth of 16.2 minutes of arc, and sidelobe levels below 4 percent of the on-axis gain. Vignetting losses are approximately 30 percent at the highest zenith angle.