GB2231484A

GB2231484A - Bracket assembly for a dish antenna

Info

Publication number: GB2231484A
Application number: GB8905905A
Authority: GB
Inventors: Clive Marles Sinclair; James St Valentine Westwood
Original assignee: Cambridge Computer Ltd
Current assignee: Cambridge Computer Ltd
Priority date: 1989-03-15
Filing date: 1989-03-15
Publication date: 1990-11-21
Also published as: GB8905905D0

Abstract

A dish antenna bracket is formed from a dish bracket (10) for fixing to the dish antenna. This is pivotally coupled to an intermediate bracket (16), about a first axis, which is in turn pivotally coupled to a wall bracket (23), about a second axis. Each pivotal connection includes a pair of flanges (22, 26) and each flange of this pair has a circle of holes (28) concentric with respective axis. The holes (28) in each flange are equispaced but the holes in a first flange of the pair have a different spacing to the holes in the second flange of the pair. Thus there are a large number of closely spaced positions in which a hole in one flange lines up with a hole in the other flange for insertion of a positioning screw. <IMAGE>

Description

BRACKET ASSEMBLY FOR A DISH ANTENNA The need for inexpensive dish antennae to receive satellite television is now well established. Many such antennae will be mounted on walls and there is a need for an adjustable bracket assembly for this purpose which is inexpensive, umbstructive, minimises the standoff distance of the dish fran the wall and allows precise adjustment in azimuth and elevation to an accuracy of about 10, with moreover reliable retention of the adjustment.

To meet these objectives the bracket assembly according to the invention comprises a dish bracket pivotally connected to an intermediate bracket about a first axis and a wall bracket pivotally connected to the intermediate bracket about a second axis orthogonal to the first axis. The axes both lie in a plane perpendicular to the dish axis. The first and second axes may be horizontal and vertical respectively when the dish is mounted on a wall.

The e pivotal connections may be made with pairs of flanges with at least one pair of flanges pertaining to each axis having circles or arc of positioning holes concentric with the axis. The e holes in each flange are eguispaced but with a different angular spacing such as to provide, by the vernier principle, a large number of closely spaced positions in which a hole in one flange lines up with a hole in another flange for insertion of a positioning screw. For example, if there are 18 holes at 200 intervals in one circle and 17 holes at intervals of about 21.20 in the other circle, the 1.120 difference provides lining up positions at intervals of 0.56 which gives sufficient accuracy.

An embodiment of the invention is shown in plan view in the sole figure of the accompanying drawing, by way of example.

The bracket assembly shown comprises a dish bracket 10 having a cranked back plate 11 and out-turned flanges 12 and 13 at the radially inner and outer ends of the bracket respectively. The cranked back plate 11 has a radially inner portion 14 for fixing to the back of the antenna dish centrally of the dish and an inset radially outer portion 15 for fixing to a radially outer portion of the dish. The flanges 12 and 13 lie in spaced vertical planes parallel to the dish axis A.

An intermediate bracket 16 is pivotally connected to the dish bracket 10 by a pivot rod 17 passing through the dish bracket flanges 12, 13 and corresponding flanges 18, 19 at the ends of a central bar 20 (stiffened by a swage 21) of the intermediate bracket 16. The e radially outer flange 19 of the intermediate bracket has two horizontal flanges 22 extending radially outwards fran its top and bottom edges. A wall bracket 23 comprises a back plate 24 which is, in use, screwed to a wall (as symbolised at 25) and two horizontal flanges 26 extending forwardly fran the top and bottom edges of the back plate 24 and lying flat against the two flanges 22 respectively of the intermediate bracket 16.The horizontal flanges 22 and 26 are connected together by a vertical pivot pin 27.

As can be seen the top flange 26 has a circle of holes 28 concentric with the pivot axis 27, namely 17 equally spaced d holes 28. The bottam flange 26 also has such a circle of holes. The two horizontal flanges 22 of the intermediate bracket 16 have circles of holes (not shown) on the same pitch circle but spaced fractionally closer together, there being eighteen holes in the circle, instead of seventeen.

After the bracket assembly has been fixed to a wall the antenna dish is adjusted in azimuth and elevation. The azimuthal position is fixed by inserting a fixing pin or screw through whichever pair of holes line up in the top pair of flanges 22, 26 and similarly through the lined up holes in the bottan pair of flanges 22, 26.

For this purpose use may be made of nuts and bolts, self-tapping screws, rivets etc.

So far as the elevation is concerned, the radially outer vertical flanges 13 and 19 of the dish bracket 10 and the intermediate bracket 16 respectively are similarly provided with circles of holes. Although these cannot be seen in the drawing they are concentric with the horizontal pivot axis 17 and again one circle contains eighteen holes while the other oontains seventeen.

A fixing pin or screw is inserted through the holes which register in the set elevation position. Because of the cranking of the back plate 11 to match the contour of the antenna dish, the radially inner flanges 12 and 18 are too small to have circles of holes. If it is considered insecure to rely upon a single fixing pin or screw to hold the elevation setting the flanges 13 and 19 may be provided with slotted holes to accept clamping nuts and bolts. The elevation will be fixed by the pin or screw inserted through the registering holes but the pin or screw will be relieved of some of the shear forces by the nuts and bolts which clamps the two flanges 13 and 19 together.

The brackets lOt 16 and 23 may be made fram galvanized steel plate. The whole assembly lies behind the dish and the stand off distance, namely the spacing between the back plate 24 of the wall bracket 23 and the portion 14 of the dish bracket 10, is small.

Instead of the pivot pins 17 and 27 four sets of nuts and bolts, with washers, may be used to oonnect the four pairs of adjacent flanges.

Claims

1. A dish antenna bracket comprising a dish bracket member pivotally connected to an intermediate bracket member about a first axis and a wall bracket member pivotally connected to the intermediate bracket member about a second axis, each pivotal connection being made with a pair of flanges with at least one pair of flanges pertaining to an axis having circles or arcs of positioning holes concentric holes with the axis, the holes in each flange of the pair being eguispaced but each flange of the pair having different spacings such as to provide a large number of closely spaced positions in which a hole in one flange lines up with a hole in another flange for insertion of a positioning screw.

2. A dish antenna bracket according to claim 1 in which the first and second axes lie in a plane substantially perpendicular to the dish axis.

3. A dish antenna bracket according to claim 1 or 2 in which the first and second axes are horizontal and vertical respectively when the bracket is mounted on a wall.

4. A dish antenna bracket according to claim 1, 2, or 3 in which the dish bracket member includes a cranked back plate for fixing to the back of an antenna dish.

5. A dish antenna bracket substantially as herein described with reference to the acoompanying drawings.