GB2182240A - Portable support; radio antenna arrangement - Google Patents

Abstract

A portable support has four legs, (6, 8, 10 and 12), each in the form of upper and lower relatively slidable parts, each lower part terminating in a ground-engaging foot 6D, 8D, (10D,) 12D. The legs at their upper ends are pivotally connected to a base 14. The base 14 is rigidly secured relative to the legs by screwing down handwheels (18A,) 18B, (18C,) 18D which press respective pads (20a, 20B, 20C, 20D) into firm contact with the outer surfaces of the upper parts of the legs. A dish-shaped radio antenna 42, such as for satellite communication, is supported on an arm 40 from a column 24. The column is adjustable to swivel the antenna about a substantially vertical axis and the arm is pivotally mounted on the column 24 so as to move the dish about a substantially horizontal axis. The sub-reflector 50 for the antenna is completely enclosed within a cone-shaped support 48 made of GRP and with foam-filled reinforced ribs 54 and a GRP end plate 52. <IMAGE>

Description

SPECIFICATION Portable supports such as for radio antennas, and a radio antenna suitable for supporting by such a support The invention relates to portable supports. An embodiment of the invention to be described in more detail below isforsupportingaradio antenna. However, the portable supports of the invention are not restricted for use to supporting radio antennas.

The invention also relates to radio antennas which may, though not necessary are, supported by portable supports according to the invention.

According to the invention,there is provided a portable support, comprising a base having four adjustable-length legs pivotally depending therefrom and extending downwardly and outwardly into engagementwith the ground, and adjustable means, individually adjustable relative to each said leg in accordance with its angular position relative to the base, for rigidlysecuringthe base to the legs.

According to the invention,there its further provided a radio antenna arrangement comprising a dishshaped reflector supported within and at the closedoff large diameter end of a conically-shaped support made of radio-transparent glass reinforced plastics material.

A portable radio antenna assembly embodying the invention will now be described, byway of example only, with reference to the accompanying drawings in which Figure lisa perspective view of the support ofthe assembly; Figure2 is a side elevation ofthe assembly; and Figure3 is an enlarged view of part ofthe assembly.

The assembly to be described is intended for use in radio communications between the ground and a satellite. The assembly is designed to be portable, in disassembled form. When re-assembled, it is intended to be able to be set up on any convenient patch of ground and its antenna then directed at the satellite from which radio communication is to be received.

Therefore, the assembly has to be able to be set up so that the antenna can be given the desired orientation even when the assembly has to be placed on an uneven ground surface, and, furthermore,the assembly has to provide an extremely stable support forthe antenna once it has been set up; because of the distance involved to the satellite, even extremely minorchanges in antenna attitudewill disrupt radio communication.

As shown in Figure 1,the supportS ofthe assembly has four legs, 6,8,10 and 12. The legs are of generally square cross-section. Each leg has a lower part6A,8A, 10A, 12which is slidablewithin a respective upper part 68, 8B, lOB, 12B. The relative position of each lower part with respect to each upper part is thus easily adjustable, and when the desired relative position has been achieved,thetwo parts of each leg can be locked together by means of a respective friction clamp operated bya respective handle 6C, 8C, 100 and 12C (the latter not visible in Figure 1).Each lower leg part 6A, 8A, 10A, 12Aterminates in a respective foot 6D, 8D, 1 OD, 1 2D, the feet being in the form of respective circular discs which are pivoted to the distal ends of the lower leg parts by respective ball and socket joints.

The upper parts6B,8B,10B,12B are attached to a cruciform-shaped base 14. The base 14 has four wings 14A, 14B, 14C, 14D each of which is made up of a respective pair of side plates between which are spective one ofthe upper leg parts 6B,8B,10B,12B extends. A bolt 16 extends between the two side platesofthewing 14Aand passes through holes at the distal end (not visible) ofthe upper leg part 6B, thus pivotally supporting the leg 6 and attaching itto the base 14. The other legs 8,10 and 12 are pivotally supported to the otherth ree wings 14B, 14C and 14D ofthe base in exactly similarfashion.

The upper and outer edges of the pair of side plates forming the wing 14A are joined together by a bridg- ing piece 17Aand a bridging piece 17Dsimilarlyjoins the side plates of wing 14D; the bridging pieces four wings 14B and 14C are not visible in Figure 1. Each bridging piece supports a block having a screwthreaded bore in which is engaged a correspondinglythreaded bolt having at its upper end a knob 18A, 18B, 18C, 18D by means of which it may be screwed in and out of the respective block.At its lower end, each bolt is attached, by means of a ball and socket joint, to a pad 20A,20B,20C,20D (pads 20B and 20C not being visible), the pads thus being in alignmentwith and capable of being screwed down into contact with the outer faces of the respective upper parts 6B,8B,1 OB and 12B of the legs.

The antenna arrangement 22 is mounted on the base 14 by means of a column 24 (see Figure 2).Atits lower end, the column 24 is located in a mating part situated centrallyofthe base 14so asto befixed against rotation. The upper part ofthe column is rotatable relative to the lower part, after release of clamp 26 by means of a knob 28.

At its upper end, the column 24 supports an arm 40 carrying the main reflector 42 of the actual antenna.

The arm is attached to the upper end ofthe column 24 by a mechanism 44. The mechanism 44 is pivotally attached to column 24 and released and clamped via a knob 46. At the end of the arm 40 is mounted a hollow cone-shaped support 48 made of glassreinforced-plastics (GRP) material, more clearly shown in Figure 3. At its outer end, the sub-reflector dish 50 forthe antenna (shown dotted) is mounted and the open end ofthe support48 is closed offbya disc-shaped cover 52, such as also made ofGRP.

The support 48 is strengthened by means ofthree foam-filled GRP ribs 54 (only one shown, the others being arranged at 120 degree intervals around the outer surface ofthe cone).

Electrical connections are made to the antenna itself via the arm 40.

The coníplete assembly is set up by adjusting the effective lengths of each of the four legs 6,8,10, 12 by sliding the lower leg parts relative to the upper leg parts and then clamping them by means oftheclam- ping handles6C,8C,10C,12C.Thefeet6D,8D,10D, 1 2D adjust themselves so asto make firm contact with the ground. When the legs have been set up in this way, the knobs 18A, 18B, 18C and 18D are adju sted so as to bring the pads 20A, 20B, 20C, 20D into firm contact with the respective leg upper parts so as to secure the base 14 rigidly with respect to the legs.

The column 24 is thus rigidly supported in an approximately vertical attitude on the base 14. Thereafter, the knobs 28 and 46 areturned to release their respective clamps and the attitude of the antenna reflector42 is adjusted aboutthe horizontal and vertical axes by the means ofthe arm 40 accordingtothean- gular position ofthe satellite. The knobs 28 and 46 arethentightened to clamp the antenna.

As stated above, for effective operation it is es sentiai thatthe antenna, once adjusted, be supported art a constant attitude. Thewholestructuretherefore hasto be rigid. In particular,thestructure must be such that it remains firmly and constantly positioned on the ground. The antenna dish is of substantial size and the wind forces on the structure can therefore be quite considerable. It is found thatthe provision of four legs, in accordance with the invention, instead ofthe more usual three legs, provides considerably better support. Athree-legged support, although well able to accommodate different ground contours, provides a resistance to wind forces which varies according to the direction ofthe wind relative to the three legs.Such variation is much less pronounced with four legs. However, a problem with the use of four legs is that it is less easy to adjust them to suit variations in ground contour; not only must the lengths be adjusted but it is also necessary to provide adjustments to take account of the angle which each makes to the horizontal plane. This is achieved by arranging for the legs to be pivotally connected to the base 14 and by arranging forthe base 14to be firmly supported from the legs, afterthe legs have been set up, by means ofthe adjusting knobs 18A, 1 8B, 18C, 18D.

The assembly illustrated clearly has to be designed to copewith relatively rough handling and with frequent assembly and disassembly. It is particularly importantthatthe dish 42 and the sub-reflector 50 be held in the correct relationship with each other and that the sub-reflector be properly protected from damage. This is achieved by the GRP cone-shaped support48. It and the cover 52 enclose the subreflector 50 and rigidly support it in the correct position relative to the dish 42. At the sametime, however, the cone is effectively radio-transparent and sufficiently rigid yet light in weight.

Although the support (the part indicated generally at 5) has been described and illustrated as supporting a radio antenna, itwill be appreciated that it may instead be used for other purposes - wherever are latively rigid support is required for mounting on ground of variable contour.

Claims (18)

1. A portable support, comprising a base having fouradjustable-length legs pivotally depending therefrom and extending downwardly and outwardly into engagement with the ground, and adjustable means, individually adjustable relative to each said leg in accordance with its angular position relative to the base, for rigidly securing the base to the legs.

2. Asupportaccording to claim 1, in which each leg comprises two relatively slidable portions for adjusting its length, and means for releasably clamping the two portions of each leg together.

3. A support according to claim 1 or2, in which the distal end of each leg carries a respective groundengaging pad whose attitude relative to the distal end of the leg is adjustable.

4. A support according to any preceding claim, in which each adjusting means comprises means acting between the base and each leg and adjustable to prevent pivoting movement of that leg relative to the base in a direction tending to liftthe distal end ofthat leg from the ground.

5. A support according to claim 4, in which each adjusting means comprises screw-threaded means in screw-threaded engagement with the base so as to be capable of being screwed relative to the base into contact with an outer part of the respective leg at a point spaced down the leg from its point of pivotal attachmenttothe base.

6. Asupportaccording to any preceding claim, in which the base is of cruciform shape, comprising fourwings each of which has two side members spa- ced apart in the generally horizontal direction to provide a gap for receiving the upper end of a respective one of the legs, with the axis of pivoting of the leg passing between the two side members, and in which each screw-threaded means comprises are spective bolt screw-threadedly engaging a respective block between the respective pair of side members, the bolt having means at its upper end for rotat ingitanda leg-engaging pad at its lowerend.

7. Asupportaccording to any preceding claim, including mounting means for mounting a radio antenna arrangement on the base.

8. Asupportaccordingto claim 7, in whichthe mounting means comprises a column for mounting in a position upstanding from the base and in which the antenna comprises dish means supported from the column.

9. Asupportaccording to claim 8, in which the column is angularly movable about an up-standing axis so as to move the dish means correspondingly and in which the dish means is adjustable aboutan axis perpendicularto the upstanding axis.

10. Asupportaccordingto claim 8to 9, in which the dish means comprises a relatively large dish having its concave surface facing towards the convex surface of a coaxially positioned smaller dish.

11. Asupportaccording to claim 10, in which the smaller dish is enclosed within a support made of radio-transparent glass reinforced plastics material.

12. A support according to claim 11, in which the glass reinforced plastics material is cone-shaped with the said smaller dish mounted at its large diameter end.

13. A support according to claim 12, in which the cone-shaped glass-reinforced plastics material is strengthened by one or more foam4illed ribs.

14. A radio antenna arrangement comprising a dish-shaped reflector supported within and at the closed-offlargediameterend of a conically-shaped support made of radio4ransparent glass reinforced plastics material.

15. An antenna arrangement according to claim 15, in which the conically-shaped glass reinforced plastics material is strengthened by one or more foam-filled ribs running along its outside surface.

16. An antenna arrangementaccording to claim 14 or 15, in which the conically-shaped support supports the reflector cantilever4ashion with reference to a substantially larger antenna dish so that thesaid reflector acts as the sub-reflectorthereto.

17. A portable support, substantially as described with reference to the accompanying drawing.

18. A radio antenna arrangement, substantially as described with reference to the accompanying drawing.