GB1213266A - Improved az/ef turret type antenna - Google Patents

Abstract

1,213,266. Aerials. ROHR. CORP. 5 May, 1969, No. 22905/69. Heading H4A. An elevation over azimuth aerial structure comprises a pedestal 12, Figs. 1, 2, upon which a turret 11 is supported by roller means 13. A shaft 51 projects upwardly from the pedestal to the turret on an axis of azimuthal rotation of the latter. A reflector 10 is pivotally mounted on the turret, on an axis of elevational rotation. As described, the reflector 10 comprises a reflector surface 16 of aluminium panels mounted on a steel back-up structure 17, and it is associated with a sub-reflector 10 and a feed cone 8 in a Cassegrain type aerial system. A pair of elevation wheels 21, 22 are secured to, and are spaced apart on the back-up structure 17 and are also secured to respective tubular elevation shafts 23, 24 directly and by means of sets of spoke members 25, 27. A length of triple stranded roller chain 115 is secured on the outside of the wheel 21 and is engaged by the two sets of triple drive sockets of elevation drive means comprising a pair of motors and reducers mounted on an elevation platform 201 (Figs. 20, 21, not shown). Buffers and stops are also provided, which limit the movement to about 94 degrees. Teeth are provided on the outside of the wheel 22 which may be locked by complementary teeth on a hand-operated fixture mounted on the platform 201, so securing the reflector against rotation about the elevation axis, when required (Fig. 22, not shown). Bearing structures 26, 28 for the shafts 23, 24 are supported by respective systems of three beams 29, 30, 31 and 33, 34, 35 to base frame 50 of the turret 11. Said frame is of generally triangular configuration and supports at its centre the shaft 51, Fig. 4, which is hollow and in which runs an elevator 55, driven by a motor 122, with cable drum 123 and cables 124, 124A, for providing access in and between the pedestal 12 and the turret 11. The three ends of the frame 50 are provided with tapered rollers which run on a central flat portion of a circular track 39, which also has inner and outer rims, and which is mounted on top of the pedestal 12. The two front ends 56, 57 of the frame 50 support azimuth drive means 14, 15 comprising motors, gearing and triple drive sockets (Figs. 27, 28, not shown). Said sockets engage an endless triple stranded roller chain 112 which is secured on the outside of the outer rim of the track 39. The frame 50 also carries buffers 100, 102 (Figs. 7, 8, not shown) which co-operate respectively with stops 103, 101 mounted on the pedestal 12 to limit the azimuthal movemant to about 270 degrees. The rear end 58 of the frame 50 is provided at each side with a yoke carrying rollers which run under the rims of the track 39, and are maintained in contact therewith by hydraulic means (Fig. 26; not shown). Each end of the frame 50 is also provided with a pivoted yoke carrying a pair of rollers which bear radially against the inside of the inner rim of the track 39 with a pressure which may be preset by means of a lockable adjusting screw (Fig. 25, not shown). An electronics room 145 is provided on the turret 11 between the elevation wheels 21, 22 and a hoist 155 on a boom 156 allows for handling equipment. A bellows 180 connects the turret 11 to a centre hub room (9), Fig. 10 (not shown), and in order to provide for access a folding or jalousy type ladder (197) in the room (9) is hinged at one end to the top of a fixed ladder (194) in the room (145) and has a roller (198) at its other end which moves in a channel (199) fixed in the room (9). In an alternative arrangement, additional area for equipment is provided in the turret (Figs. 16 to 19, not shown). The pedestal (12), Fig. 3 (not shown), is a massive concrete structure which is octagonal in cross-section and which has several storeys. Bearings are provided at the various floor levels for the shaft (51) and the track (39) is supported on a ridge (38) formed on the roof.