US3383692A - Main dish with adjustable subreflector - Google Patents

Description

May 14, 1968 J. LAIBSON ETAL 3,383,692

MAIN DISH WITH ADJUSTABLE SUBREFLECTOR Filed Jan. 7, 1965 4 Sheets-Sheet 1 I N VE NTO Jzzzx 445.5%;

May 14, 1968 J, LA|B$oN ET AL 3,383,692

MAIN DISH WITH ADJUSTABLE SUBREFLECTOR Filed Jan. 7, 1965 4 Sheets-Sheet 2 May 14, 1968 J. LAIBSON E L MAIN DISH WITH ADJUSTABLE SUBREFLECTOR 4 Sheets-Sheet 3 Filed Jan. 7, 1965 0 Jazzy Pl /$50? 20552744 MV/l Zd May 14, 1968 J, LAIBSON ET MAIN DISH WITH ADJUSTABLE SUBREFLECTOR 4 Sheets-Sheet 4 Filed Jan. 7, 1965 5 My WWW M mg m 2 WMM, 7 if W7 W ay V United States Patent 3,383,692 MAIN DISH WITH ADJUSTABLE SUBREFLECTOR Jerry Laibson, San Diego, and Robert M. Munro, El

Cajon, Calif., assignors to Whittaker Corporation,

Los Angeles, Calif., a corporation of California Filed Jan. 7, 1965, Ser. No. 424,102 10 Claims. (Cl. 343-781) ABSTRACT OF THE DISCLOSURE A large parabolic antenna comprising a series of individual reflecting panels having each of such panels adjustably secured to flanges of a central hub member and flanges of a series of radially extending support members secured to the hub member. Such individual panel adjustment is effected using threaded studs each having a portion thereof embedded in the panel. A small subreflector is mounted on the large parabolic antenna such that it may be independently adj'usta'bly moved along any one of three mutually perpendicular axes without changing the adjustment along the other two of such axes.

The present invention relates to antenna constructions.

Briefly, the antenna construction described herein involves generally a main reflector and a subrefle-ctor constructed and assembled in a novel manner to achieve advantages, some of which are enumerated as follows:

(1) A resulting construction in which rigid manufacturing and alignment tolerances can be satisfied.

(2) A resulting construction wherein a high strength to weight ratio exists.

(3) A resulting structure wherein a shallow backup structure permits a close-in assembly to the pedestal with a resulting low mass moment of inertia.

(4) -A resulting construction wherein the interaction of panel and casting design maintains high natural frequencies in all modes of vibration.

5 A resulting structure wherein the maximum stress levels under survival conditions are considerably below any fatigue requirements and which thus result in a high reliability confidence factor.

(6) A construction which may be easily assembled, disassembled and transported with no damage or accuracy degradation to the structure.

(7) A resulting construct-ion wherein individual panels of the main reflector may be easily and accurately aligned.

(8) A resulting construction wherein the subreflector may be easily adjusted in three dimensions with respect to the main reflector.

It is therefore a general object of the present invention to provide an improved antenna construction having one or more of the above enumerated features and advantages.

A specific object of the present invention is to provide an improved antenna construction in which the subreflector and support system consist of cast elements which are integrated with a quadripod tube structure which is rigidly connected to radial trusses, with the rigidity of the cast components and tubular structure assuring realignment capabilities.

Another specific object of the present invention is to provide an antenna construction of this character in which the subreflector may be readily adjusted along the Z axis, the X axis or the Y axis.

Another specific object of the present invention is to provide novel means whereby a subreflector may be mounted on the main antenna dish supporting structure.

3,383,692 Patented May 14, 1968 Another specific object of the present invention is to provide an improved supporting structure for the main antenna dish.

Another specific object of the present invention is to provide an improved arrangement whereby individual panels of the main dish may be accurately aligned on their supporting structure.

The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. This invention itself, both as to its organiza-tion and manner of operation, together with further objects and advantages thereof, may be best understood by reference to the following description taken in connection with the accompanying drawings, in which:

FIG. 1 is a view taken as indicated by the arrowed line 1- 1 in FIG. 9.

FIG. 2 is a view taken in the direction indicated by the arrowed line 2-'2 in FIG. 1, with the subreflector shown in full lines and also in dotted lines, the dotted lines indicating two different adjusted positions of the subreflector.

FIG. 3 is a view of the subreflector taken as indicated ;by the arrowed line 3- 3 in FIG. 4.

FIG. 4 is a view taken as indicated by the arrowed line 4-4 in FIG. 1.

FIG. 5 illustrates connections between panels on the main reflector and is a view taken substantially as indicated by the arrowed lines 5 5 in FIG. 9, with a portion of the panels broken away to illustrate the backing structure.

FIG. 6 is a view taken as indicated by the arrowed line 6-6 in FIG. 5.

FIG. 7 is a view taken as indicated by the arrowed line 7- 7 in FIG. 5.

FIG. 8 illustrates a portion of the panel construction which is illustrated also in FIG. 7.

FIG. 9 is a view of the main and subreflector assembly, with a portion of the main reflector being illustrated in section.

FIG. 10 is a view of a portion of the main reflector taken as indicated by the arrowed line 10''10 in FIG. 9.

FIG. 11 illustrates details of one of four fastening structures for the subreflector and is a view taken as indicated by the arrowed line '111 1 in FIG. 10.

FIG. 12 is a view taken as indicated by the arrowed line -12-- 12 in FIG. 4-.

FIG. 13 is a perspective view of two of the adjustment elements shown in FIG. 12.

FIG. 14 is a view like FIG. 12 and serves to illustrate by dotted lines a different adjusted position of the subreflecto-r.

FIG. 15 is a sectional view taken as indicated by the arrowed lines 151-5 in FIG. 14.

FIG. 16 shows a modified structure.

The antenna described includes, as seen in FIG. 9, a main reflector '10 which may be parabolic in shape and a subrefiector 12 which may be hyperbolic in shape when used in a Cassegrain arrangement.

The main reflector 10, as illustrated, is in general defined by twelve sections of honeycomb constructed panels 14, each of which is in the form of a curved sector, as shown in FIGS. 9 and 10, and each of such panels 14 is provided with a suitable conventional reflecting surface element 16 in the form of a reflecting coating.

The panels 14 are individually mounted on a supporting structure 18, FIGS. 9 and 10, as now described in relation to FIGS. 5-11.

The panel supporting structure 18 includes, as seen in FIGS. 9 and 10, a centrally disposed generally annular member 20 in the nature of a torus member which may be a casting formed to define radially extending rib portions A, radially extending flange portions 20B and twelve circumferentially extending and joined flanged portions 200 to which are bolted or otherwise secured twelve radially extending support members 24, each of which may also be a casting formed to define a radially extending rib portion 24A and a pair of radially extending flange portions 24B and also an inner flanged portion 24C, such flanged portion 24C being illustrated as being secured to the flanged portion 20C by bolts 25 (FIG. 9). This central support member 20, as illustrated, is formed with an inner annular ring portion 20D to which the inner ends of rib members 20A and flange members 203 are joined. This ring portion 20D thus defines an annular opening 26 through which a part of the antenna feed system (not shown) may extend when desired.

It is noted that only four of these radial support members 24 are provided at their outer ends with a support structure 24E, FIGS. 9, 10, 11, for a corresponding one of four equally spaced subreflector support arms 28 for supporting the subreflector 12, as described in more detail hereinafter.

Each of the individual panels 14 (twelve in number) are adjustably and releasably secured to the support structure 18 and more specifically to the flange portions 20B and 24B of the support elements 20 and 24, respectively, with slight clearance between adjacent edges of adjacent panels, such slight clearance being provided to allow for expansion and contraction of the panels and being illustrated in exaggerated scale at 30 (FIG. 10).

For such panel fastening purposes, the individual panels are constructed as illustrated in FIGS. 7 and 8, each with a series of internally and externally threaded metal inserts 34 which are secured in the corresponding panel 14 by a suitable cement such as, for example, a thermosetting cement 36, with the externally threaded portion 34A of the insert 34 extending outwardly of the panel and with the insert 34 being knurled at 348 (FIG. 7) to improve the bond between it and the cement 36.

In assembling a panel to its supporting structure, the threaded stud portion 34A initially has a nut 41) (FIG. 7) threaded thereon, the threaded apertured portion 34C of insert 34 is aligned with a corresponding apertured portion in the corresponding flange 24B, and when so aligned, a bolt 42 with a lock washer 44 thereon is threaded into the threaded insert portion 340, and the bolt 42 is then tightened to cause clamping of the flange 24B between the washer 44 and nut 40. In such assembly, it is, of course, necessary that the reflector side of the panels be accurately positioned and aligned, and this usually requires individual adjustment of individual panels, and such adjustment is accomplished by positioning of the individual panels inwardly or outwardly with respect to the supporting structure, such adjustment being accomplished by releasing the bolt 42, i.e., releasing the clamp, turning the nut inwardly or outwardly, as desired, and retightening the bolt 42 to thereby adjust the spacing between the end of the panel insert 34 and the corresponding portion of flange 24B. It will be seen that the nut 40 serves essentially as an adjustable shim between the flange 24B and insert 34, with the effective shim thickness being adjustable to zero thickness, if desired.

The individual panels are secured and adjusted in like manner on the flanges 20B of the inner structural support 20 using like bolts designated by the same reference numeral 42.

As indicated previously, the subreflector 12 is supported on four equally spaced arms 28. One end of each of such arms 28 is secured to the support structure 18 and more specifically the ends of four support members 24 in the manner now described in relation to FIGS. 9-11, with such arms 28 extending through a corresponding panel apertured portion 14A.

Each of the arms or spars 28 is of tubular stock and, as seen in FIG. 11, one end thereof has secured thereto a flange member 46 having a cylindrical portion fitted in the tubular spar member 28 after which the members 46 and 28 are welded together at weld 50; and bolts 52 serve to releasably secure the flange member 46 to a plate portion 24G integrally formed with a corresponding one of four radial support members 24. This plate portion 24G forms the bottom wall of a cylindrical opening through which access is had to one end of the bolts 52.

The other end of each of the arms or spars 28 is releasably secured in like manner to the subreflector assembly, 'as now described in relation to FIGS. 1-4, and particularly FIG. 4, wherein a like flange member is fitted within the tubular spar member 28 and welded thereto at weld 64. In this case, the flange member 60 is secured by bolts 66 to a corresponding fiat plate like portion 68F of a generally annular and tapered support member 68 which may be a casting formed with the eight outer sloping walls 68F so that the same appears octagonal in cross-section, as illustrated in FIG. 1, and with eight rib portions 68A extending radially inwardly from the junction of the adjacent walls 68F to a central hub portion 68B which is also integrally formed with a recessed annular wall portion 68C that likewise joins the hub portion 68B with the inner edge portions of the eight outer wall portions 68F. The wall portion 68C is recessed to provide an inner annular recessed portion 68H.

Mounted on the wall portion 68C is an annular generally ring-shaped guide member 72 having an outer flanged portion 72A and an integrally formed inner radially extending flange portion 72B, the members 72 and 68 being releasably secured together by four bolts 76 extending through the flange portion 723 (FIG. 12) and cooperating to provide a guide structure for an adjustably positioned subreflector support 80 (FIG. 13).

The support 80 has a central internally threaded sleeve portion 30A integrally formed with a disc portion 80B which is undercut to provide four circumferential flat portions 800 for engagement with the face of a rectangular bar 82A connected, as shown in FIG. 15, to one end of 'a corresponding adjustment screw 82, each of such four screws 82 being threaded in apertured portions in the flange 72A and being undercut, as shown in FIG. 15, to mount a retaining ring 82C which frictionally cooperates with an annular grooved portion 82D in block 82A to allow turning of the screw 82 in block 82A and yet cause the block 82A to move rectilinearly upon turning of screw 82.

It will be seen that the support 80 may be adjusted, as illustrated in FIG. 14, by turning the screws out and in to what is termed as X and Y adjustments having reference to the X-X and Y-Y axes. Thus, in FIG. 14, the vertically aligned screws 82 are adjusted for up and down adjustment, i.e. Y adjustment, and likewise, the horizontally aligned screws are adjusted for right and left adjustment, i.e. X adjustment of the subreflector support 80; and during such adjustment, the support 80 is guided in its movement by the spaced parallel wall 68C and flange 72B.

The subreflector 12 is formed with a hub portion 12A and rib portions 12B (FIG. 3) extending radially outwardly therefrom, and secured to the hub portion 12A by pins is an externally threaded sleeve 92 which is threaded in the sleeve portion 80A of support 80. This threaded interconnection provides for a so-c'alled Z axis adjustment (which is perpendicular to the previously mentioned X and Y adjustments) in that the reflector 12 may be adjustably positioned further from or closer to the main reflector 10 (FIGS. 4 and 9), and once so adjusted, the adjustment may be secured by the two nuts 96 and 98 threaded on the sleeve 92.

It will thus be seen that the antenna construction as illustrated involves twelve radial castings 24, a center cast hub 20 and twelve honeycomb panels 14, with the radial ribs or castings being structurally integrated by their connections to the strong center hub 20 and the reflector panels '14. The ribs 2 4 are aluminum castings which serve as trusses in transferring the various loads to a transition or pedestal structure, with the individual ribs 24 being joined through the hub ring formed with intercostal plate or flange portions 200, such flange portions 20C providing high torsional rigidity during handling and operation and contributing also towards equalizing deformations. This construction is particularly useful where the outside diameter of the main dish or reflector is, for example, in the range of 12 to 18 feet. In such case, the panels 14 may be 2 /2 inches thick, with a reflecting aluminum sheet material thereon of, for example, a thickness of .020 inch.

FIG. 16 shows a different and preferred form of the adjustment elements one of which is also shown in FIG. 15. The block 182A in FIG. 16 corresponding to block 82A in FIG. 15 is formed with an undercut portion 182G and one end of the threaded element 182 (corresponding to 82 in FIG. 15) extends loosely through the block 182A into the undercut portion 182G and is retained thereon by a snap rin g 1 82C, the snap ring 182C being within an annular groove formed on the element 182.

While the particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from this invention in its broader aspects and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

We claim:

1. In an antenna construction of the character described, a central hub member, said hub member having a series of circumferentially extending and joined flange sections; a series of radially extending support members each having a flanged portion on its inner end secured to a corresponding flange section of said hub member, each of said radially extending support members having a pair of radially extending flange portion-s; a series of panel members secured to said radially extending flange portions and to said hub member, said hub member having an inner ring portion, said ring portion being joined to said flan-ge sections by a series of radially extending rib members, said hub member having a series of radially extending flange portions to which said panel members are secured, each of said panel members including an insert member which has an internally threaded portion 'and an externally threaded portion with said externally threaded portion extending outwardly beyond the confines of the panel member, a nut member threaded on said externally threaded portion, a bolt extending through said radially extending flange portion and threaded in said internally threaded portion.

2. In an antenna construction of the character described, a central hub member, said hub member having a series of circumferentially extending and joined flange sections; a series of radially extending support members each having a flanged portion on its inner end secured to a corresponding flange section of said hub member, each of said radially extending support members having a pair of radially extending flange portions; a series of panel members secured to said radially extending flange portions and to said hub member, said hub member having an inner ring portion, said ring portion being joined to said flange sections by a series of radially extending rib members, said hub member having a series of radially extending flange portions to which said panel members are secured, said radially extending support members each having a flange portion near its outer end; a subreflector mounting structure; said mounting structure including a plurality of tubular support members; a flanged plug member fitted into and secured within a corresponding one of said tubular support members; said flanged plug memher being secured to a corresponding one of said outer ganged portions of said radially extending support mem- 3. A construction as set forth in claim 2, in which said subreflector mounting structure includes a hub element having a plurality of flat plate sections defining the circumference of said hub member; a flanged plug member extending in and secured within a corresponding one of said tubular support members; the last mentioned plug members each being secured to a corresponding one of said plate sections.

4. A construction as set forth in claim 3, including a subreflector having a threaded hub portion, a threaded support member on which said hub portion of said subreflector is threaded to adjustably support said subreflector on said support member along the axis of said hub portion; said support member having a flanged portion which extends radially with respect to said axis; means slidably mounting the last mentioned flange portion on said subreflector supporting structure; and means for adjustably positioning the last mentioned flange portion on said mounting structure.

5. In an antenna construction of the character described, a subreflector having a threaded hub portion; a support member on which said hub portion is threaded; said support member having a flanged portion which extends radially with respect to the axis of Said hub portion; said flanged portion having a plurality of flat portions on its periphery, a support structure, means slidably mounting said flange portion on said support structure; said means including adjustable elements on said support structure and engaging said flat portions to position said flange portion on said support structure.

6. In an antenna construction of the character described, a panel support member, a panel, an insert secured within said panel and having an internally threaded portion and an externally threaded portion, a nut member threaded on said externally threaded portion and engaging said support member, a bolt extending through said support member and threaded in said internally threaded portion.

7. In an antenna construction of the character described, a subreflector support member in the form of a flanged hub having a flanged peripheral portion defined by a series of plate sections; a main reflector support structure; the last mentioned support structure including radially extending support members each having an outer flat end portion which extends generally parallel with the plane of a corresponding one of said plate sections; and spar elements each having a flat portion at each end thereof connected respectively to and between said flat endportion and said corresponding one of said one plate section.

8. A construction as set forth in claim 7, in which said subreflector support member has a flat face; a subreflector, a subreflector support element on which said subreflector is threaded for movement along an axis which is coaxial with said flanged hub and also perpendicular to said flat face; means slidably mounting said support element on said flat face; and means for adjusting the position of said support element on said flat face.

9. A construction as set forth in claim 7, in which each of said spar members is tubular with a flanged plug extended in and secured to opposite ends thereof with one of said flanged plugs being secured to one of said plate sections and with the other of said flanged plugs being secured to said flat end portion.

10. In an antenna construction of the character described, a subreflector; a subreflector support member on which said subreflector is threaded for movement along one axis; said support member having a flange portion which extends perpendicular to said axis; a subreflector support structure having a flat face; means on said support structure and slidably mounting said flange portion on said face; screw-threaded elements threaded on said means and extending perpendicular to said axis and en- References Cited UNITED STATES PATENTS Burrell 343-781 Feldman 343-761 Blanchard 343-839 X Palmer 343-915 X Holland et a1 343-912 Ashton 343-912 Alsber-g 343-779 Thomas 343-912 White 343-915 ELI LIEBERMAN, Primary Examiner.

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