1200 THE BELL SYSTEM TECHNICAL JOURNAL, SEPTEMBER 1956 



Fig. 1 — ■ Fastening the I'adial sectors to the hub. 



folding was required. Figs. 1 to 5 illustrate the paraboloid construction 

 and support. The weight of the antenna is carried on a vertical column 

 which is mounted on bearings to permit movement in azimuth. The 

 column is held upright by a tripod structure. The central hub of the 

 paraboloid is fastened to a steel girder which extends to the rear along 

 the paraboloid axis and is pinned to a yoke carried by the vertical col- 

 umn, thus permitting movement in elevation. The antenna is scanned 

 by two motors mounted on an A-frame and connected to the end of the 

 axial girder by crank mechanisms. The total scanning range of the an- 

 tenna is about 3° in both azimuth and elevation. 



The antenna is designed for use at frequencies of 460 mc and 4,000 

 mc. The tolerance on the parabolic reflecting surface is set by the higher 

 frequency and thus must be ±t6 i^^ch to meet the usual ±X/i6 criteria. 

 The focal length is 25 feet, so that the total angle intercepted by the 

 paraboloid as seen from the focal point is 124°. Design of a feed horn for 



