US 3530477 A
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Description (OCR text may contain errors)
Sept. 22, 1970 R. JARRETT ET AL 3,530,477
SCANNING ANTENNA HAVING DRIVE MOTORS FIXED WITH RESPECT TO THE ANTENNA Filed March 25, 1968 '6 Sheets-Sheet 1 W gm fiddam v a ATTORNEYS.
Sfipf. 22, 1970 JARRETT ET AL 3 530,477
1 SCANNING AN NA ING DRIVE MOTORS FIXED WITH R ECT THE AN TENNA Filed March 25, 1968 3 Sheets-Sheet 2 ATTORNEYS Sept. 22, 1970 R. JARRETT ET AL SCANNING ANTENNA HAVING DRIVE MOTORS FIXED Filed March 25, 1968 WITH RESPECT TO THE ANTENNA Fla}. J
3 Sheets-Sheet 3 United States Patent 3,530,477 SCANNING ANTENNA HAVING DRIVE MOTORS FIXED WITH RESPECT TO THE ANTENNA Richard Jarrett, Leigh-on-Sea, and Eric Davenport Gilbert, Chelmsford, England, assignors to The Marconi Company Limited, London, England, a British compan Filed Mar. 25, 1968, Ser. No. 715,607 Claims priority, application Great Britain, Mar. 28, 1967, 14,053/ 67 Int. Cl. H01q 3/00 US. Cl. 343--765 4 Claims ABSTRACT OF THE DISCLOSURE This invention relates to aerial drive mechanisms and particularly to such mechanisms for driving what are herein termed nodding scanning aerials, i.e. aerials which are required to move both in elevation andazimuth.
The invention is illustrated in and explained with reference to the accompanying drawings in which FIG. 1 is an exploded diagrammatic view of a known nodding scanning aerial arrangement, FIG. 2 is a diagrammatic view of one embodiment of the present invention, and FIG. 3 shows, to an enlarged scale, part of FIG. 2. Like references denote like parts in all figures.
Referring to FIG. 1, 1 is an aerial which is mounted on trunnions 2 which are pivoted in a support member 4, the pivotal axis being horizontal and indicated by the chain line 3. Movement about this axis 3 is, of course, movement in elevation. Movement in azimuth is obtained by movement about the axis indicated by the chain line 6, such movement being obtained by driving the support member 4 by a shaft 5 which engages in a hole 8 in the support member 4. The axis 6 is, of course, the axis of the shaft 5 which is driven by a motor (not shown) installed in a fixed tower 7. The movement of the aerial 1 about the elevation axis 3 is provided by a jack arrangement consisting of a screw 9 connected by a trunnion at one end 10 to the aerial 1, and a nut member 11 which is on the screw 9 and is rotatable through suitable reduction gear 12 by an elevation motor 13. As will be apparent when the nut member is rotated by the motor the screw 9 is moved endwise and the aerial is moved in elevation.
This known arrangement has the disadvantage that because the mechanism driven by the motor 13 and the motor itself are mounted on the moving support member 4, the total inertia associated with this member is increased due to the extra weight of the motor and the mechanism. This is very undesirable. There is also the defect that fairly long flexible leads must be used to supply electrical power to the motor 13. In addition lubrication and maintenance are made somewhat more ice difiicult by reason of the fact that the motor and mechanism are on a moving member.
The present invention seeks to avoid the above disadvantages.
According to this invention, in a nodding scanning aerial arragement of the kind in which an aerial is carried by a member which is pivoted about one axis to a second member, said second member being in turn pivoted about a second axis perpendicular to the fixed member movement of said aerial about said one axis is obtained by a push-pull drive member actuated by a motor driven shaft which, with its driving motor, is mounted on the fixed member and has its axis coincident with said second axis.
Preferably the push-pull drive member is a screw shaft which is entered into a captive nut carried by and pivotally connected to the aerial, said screw shaft being rotated by said motor driven shaft through an epicyclic bevel drive comprising a bevel gear which is on the motor driven shaft and which drives through a ring gear having its axis at right angles to the motor shaft axis, a second bevel gear which is on the screw shaft, said screw shaft being journalled in a member pivoted about the axis of the ring gear.
Referring to FIGS. 2 and 3, the azimuthal drive for the aerial is as in FIG. 1 but the elevation drive is different. A captive nut member 11 is in effect pivotally connected to the aerial 1 by means of a clamping ring member having radial ends 14 between which the nut 11 is pivoted as shown. Into the nut member 11 is entered a screwed shaft 9 which is driven by the motor 13 by a drive mechanism best shown in FIG. 3. This drive mechanism, and the motor 13, are both mounted on the fixed tower 7.
Referring particularly to FIG. 3 the shaft 15 which is journalled in a support bracket -19 fixed to the tower 7 rotated by the motor 13 (not shown in FIG. 3 but see FIG. 2). The axis of the shaft 5 is coincident with the azimuth axis 6 which intersects the elevation axis 3 perpendicularly. On the end of shaft 15 is a bevel pinion wheel 16 meshing with a ring bevel gear 17 the axis of which is at right angles to and passes through the axis 6. The shaft of the ring gear 17 is journalled in the ends of a fork or U member 20 in the cross piece of which is journalled the screwed shaft 9. The member 20 can thus pivot about the axis of the ring gear 17. The screwed shaft 9 is rotated by a second bevel pinion 18 also meshing with the ring gear 17 as shown.
1. An improved scanning aerial arrangement of the kind in which an aerial is carried by a member which is pivoted about one axis to a second member, said second member is in turn pivoted about a second axis to a fixed member, said second axis being perpendicular to said one axis, means are provided for moving said aerial about said one axis, and means are provided for moving said aerial about said second axis; the improvement comprising means for mounting a driving motor on said fixed member; a motor driven shaft driven by said driving motor, said driven shaft having its axis coaxial with said second axis; and a push-pull drive member coupled to said driven shaft and said aerial for moving said aerial about said one axis.
2. An arrangement as claimed in claim 1 wherein the push-pull drive member is a screw shaft which is entered into a captive nut carried by and pivotally connected to the aerial, said screw shaft being rotated by said motor driven shaft through an epicyclic bevel drive comprising a bevel gear which is on the motor driven shaft and which drives through a ring gear having its axis at right angles to the motor shaft axis, a second bevel gear which is on the screw shaft, said screw shaft being journalled in a member pivoted about the axis of the ring gear.
3. An arrangement as claimed in claim 1, wherein the means for moving the aerial about said second axis is mounted on said fixed member.
4. An arrangement as claimed in claim 1 wherein said push-pull dri-ve member is coupled to said drive shaft via gearing means mounted on said fixed member.
4 References Cited FOREIGN PATENTS 8/ 1963 Great Britain.
ELI LIEBERMAN, Primary Examiner US. Cl. X.R.