GB2227610A

GB2227610A - Dish aerial system

Info

Publication number: GB2227610A
Application number: GB8915247A
Authority: GB
Inventors: Gonzales Jose Francisco Outes
Original assignee: Televes SA
Current assignee: Televes SA
Priority date: 1989-01-31
Filing date: 1989-07-03
Publication date: 1990-08-01
Also published as: FR2642569A1; PT8050U; FR2642569B1; GB8915247D0; ES1008936Y; PT8050Y; ES1008936U

Abstract

A feeder support for a receiving dish aerial system has attachment means (7) for attaching the support to a receiving aerial dish and mounting means (2-4) for mounting at least two feeders thereon so that at least one feeder is spaced from the focal point of the dish to receive radio frequency signals from at least one direction different from that in which the dish is directed. <IMAGE>

Description

FEEDER SUPPORT FOR A RECEIVING DISH AERIAL SYSTEM This ir.venton relates to a feeder suDoort for a receiving dish aerial system. e.g. of the tvpe intended to receive radiofrequency signals emitted via satellite.

A conventional dish system for detecting radiofrecuen cv signals originating from a satellite comprises a Darabolic dish and, coincident with the focal point of the dish a feeoder mounted on a supDort. The feeder support is conveniently mounted on the parabolic dish by means of fastening rods. Thus in each known Parabolic dish aerial.

there is a single feeder disposed coincident with the focal point of the parabolic dish for the detection of signals emanating from a satellite.

There are currently two types of receiving dish aerial systerr. namely a fixed-position aerial and a movable- position or oriertable aerial.

h fixed-position aerial is orierted to a specific satellite, the eish remaining in a fixed position directes at all times in tne sane direction fcr detecting signals from tne same satellite.

A movable-position or orientable aerial has an orient station mechanism so that. cnce the aerial has Dee mounted.

the on may te eriented according to the wisnes ci ne user so as tc be cirected towaros one cf two cr mre selected satell:tes.

Typically tixed-position aerials or antennae are used in communrity installations where it is necessary to have avallable as mary antennae as satellites it is desired to receive signals from. On the other nand movable-position or orientable aeriale or antennae are typically used 11 in@@vidual installatione where the user may select the orientation of the dish towards a desired sateil'te.

Due to the increase in direct-transmission television satellites which is coming about and which will come about even more in the next few years. it is becoming necessarv in communitv installations employing fixed-position aerials to have numerous available aerials - i.e. as many aerials as satellites which it may be desired to receive. In addition to a considerable increase in the cost of the installation, this gives rise to problems of space and load which sometimes make complete and adequate mounting impos- sible. Even in locations where these problems mast be solved. the foreseeable increase in satellites. already a reality today, would transform housetops and terrace roofs of apartment blocks into veritable nests of aerials or antennae. with all the concomitant problems of safet.

visibility, etc..

The aim of the present invention i3 the development cf a dish aerial system comprising a single dish which is capable of detecting the signals originating from two or more satellites. In particular. the aim is tc crosuce a feeder support for an aerial system which permits the mounting OT two or more feeders on one and the same aerial dish. sc- that the feeders which occupy positions which are not coin@dent with the focal point of the antenna produce a deflection of the beam which makes it possible to detect the signals originating from the corresponding satellites within the recurred duality limits without there being appreciable ceteriorations in the quality of image ano souna.

According to the present invention there is pro'.'ided a feeder support for a receiving dish aerial system the support having attachment means for attaching the support to a receiving aeria cish and mountina means for mountino at least two feeders thereon so that at least one feeler S spaced from the focal point of the dish wren the suppart is attached to the dish and is able to receive radiofrequency signals directed from at least one direction different from that in which the dish is directed..

The development of an aerial incorporating a feeder support according to the invention is based on the study of the lateral displacement of the feeder conventionallv located at the focal point of the aerial dish. The displacement produces a deflection of the beam of the aerial which is proportional to the displacement of the feeder.

The proportionality factor depends on parameters such as the f/d (focal length/diameter) of the reflector, the level of illumination, etc.. By suitably quantifying the displacement of the feeder, deflected beams are achieved without appreciable reduction in the gain of the antenna in the direction of deflection.

Conveniently the feeder support comprises a ring intended to be mounted on the dish of the aerial or antenna in a position which is coaxial with the latter and an orientable arm which is mounted diametrically on the ring and which is provided with the mounting means. Carrier cases for the feeders are suitably mounted on the arm.

Typically the ring which forms part of the support is equipped with peripheral anchoring elements enabling roots to join the support to the dish of the aerial. These anchoring elements preferably comprise three annularly spaced apart eauidlstant flanges joined to the ring. The ring may also carr) a fixed diametrically disposeo plate on which the arm is turnably adrustable. To enable this adiustment arcuate grooves are formed in the arm andcr plate coaxial with the ring and screw-threadec members passing through the arcuate grooves connect together the arm and the plate.

The orientable arm is suitably of a U-shared Profile.

The feeder carrier cases are conveniently acijiustably mounted between the spaced apart side walls of the rm.

Each feeder-carrier case suitably comprises a right prismatic piece with a sauare base and with a side which is slightly smaller than the distance between the side walls of the U-shaped arm.

An embodiment of the invention will now be described.

by way of example only, with reference to the accompanying drawings, in which Figure 1 is a plan of a feeder support according to the invention, Figure 2 is a plan of a ring of the support shown in Figure 1 without an orientable arm mounted thereon, Figure 3 is a section along the section line III-III of Figure 2, Figure 4 is a plan of the orientable arm of the support shown in Figure 1, Figure 5 is a side elevation of the arm shown in Figure 4 Figure 6 is a profile view of the arm shown in Figure 4.

Figures 7 and R are, respectively, a plan and a side elevation of a feeder-carrier case.

Figure 1 shows a feeder support according to tne invention for a dish aerial system. The feeder support comprises a ring 1 an orientable arm 2 carried on the rin: 1 and a series of feeder-carrier cases 3 mounted on the arm 2.

The ring 1 carries a somali plate 4 which is diametri- cally fixed and which, as can be seen better in Figures 2 and 3 , has a circular central opening 5 and two arcuate grooves 6 located one on opposite sides of the opening 5, the grooves 6 and opening 5 being concentric with each other and with the ring 1. In order to fasten the ring 1 to rods (not shown) used as elements for mounting the feeder support on the aerial dish, e.g. of parabolic form.

the ring 1 has three angularly and equidistantly spaced apart radial flanges 7, one of which may be formed by an extension of the fixed plate 4.

As shown in Figures 4 to 6, the orientable arm 2 has a U-shaped or channel profile with its central web 8 having a circular opening 9 with a diameter which is apFroximatel,v equal to the opening 5 in the small plate 4. On either side of this opening 9 are fixed, at diametrically opposed positions, two nuts 10 which are coincident witri orifices made on the central web 8. In addition, two rectangular openings 11 are provided in the central weU 6. which openings run between the side wall 12 of the arm and which occupy symmetrical positions with respect to the transverse central plane.

On each of the side walls 12. groups of orifices are formed, those on one side wall being opposite those on the other side wall. the orifices in each group being aligned with each other. In the example shown in the drawings. as can be seen better in Figure 5, three grouts CT orifices are provided in each of the side walls 12. each group of orifices being formed of three orifices. The central orifice 13 of each group 7s similar in the three groups.

The lateral orifices 14 of the central group are identica to each other. In the two end groups or orifices il.e.

disposed on opposite sides of the central group the innermost orifice 1= of each group is similar to the orifices 14 of the central group whilst the outermost crifice 16 of each end group is defined b an arcuate groove centred on the orifice 15.

The three orifices 13 and 14 .of the central group 5 are aligned in the longitudinal direction of the arm. The orifices 13 of the three groups are also aligned longitudinally with each other. The orifices 13, 15 and 16 of the end groups are also aligned with each other but form a certain angle with the longitudinal axis of the side walls 12.

Each feeder-carrier case 3 is formed, as can be seen in Figures 7 and 8, by a right prismatic piece with a sauare or rectangular base whose side is of a size which is slightly less than the distance between the side walls 12 of the orientable arm and also less than the length of the rectangular openings 11 in the arm. Each of these pieces has a coaxial circular cylindrical passage 17. In each of its lateral faces, the pieces forming the cases have a central drilled and threaded hole 16 which opens into the cylindrical passage 17. In addition, on two of the opposing faces, the piece has two drilled and threaded blind holes 19 on each face located in an opposing position and coincident with the end orifices 14 and 15-16 of the groups of orifices in the orientable arm 2.

'with the abovementioned arrangement, the feedercarrier cases shown in Figures 7 and 6 are mounted on the orientable arm 2 by means of screws which are introduced through the orifices 14 and 15-16 of the groups cf orifices in the arm and which are threaded into the drilled threaded blind holes 19 of the cases. The grooved and arcuate hole 5 of the end groups of holes in the orientable arm 5, as well as the opening 11 of the central web 6, enable the axis of the passage 17 of the feeder-carrier cases mounted in the end groups of orifices to form a certain angle with the axis of the case mounted in the central group of orifices which will be coincident with the axis of the (parabolic) dish.

The orientable arm 2 with the feeder-carrier case is mounted on the small plate 4 by means of screws which pass through the grooves 6 and are threaded in the nuts 10. The arcuate form of the grooves 6 permits the partial rotation of the orientable arm 2, the assembly being mounted as represented in Figure 1. A feeder, which will be fastened by means of pressure screws located in the drilled-through and threaded holes 18 of the feeder-carrier cases, may be mounted in each of the cases 3, the orifice 13 of each group of orifices in the orientable arm being used for the introduction and pressure of the corresponding pressure screw.

In the event that the feeder support is designed to mount a central feeder and one or more off-centre feeders, the central feeder will be arranged such that it is coincident with the focal point of the (parabolic) disc, the offcentre feeders being located on an axis which is perpendicular to the focal axis of the dish. Thi's is the case of the support shown in the drawings. In the event that there is no central feeder, the displaced feeders will be arranged in a similar manner to the above case and. in addition, the central opening 9 of the orientable arm may be reduced to an orifice for the passage of a central rotation screw. the central group of orifices 1-14 of the side walls 12 also. in this case. being disnensec with.

Claims

1. A feeder support for a receiving dish aerial system, the support having attachment means for attaching the support to a receiving aerial dish and mounting means for mounting at least two feeders thereon so that at least one feeder is spaced from the focal point of the dish when the support is attached to the dish and is able to receive radiofrequency signals directed from at least one direction different from that in which the dish is directed.

2. A feeder support according to claim 1, in which said mounting means include at least two carrier cases each for carrying a different feeder.

3. A feeder support according to claim 2, in which said mounting means includes connection means for detachably connecting said carrier cases to said support.

4. A feeder support according to any one of the preceding claims, comprising a ring arranged to be coaxial with the aerial dish when the support is attached by said attachment means to the dish and an arm diametrically arranged relative to said ring and provided with the caid mounting means.

5. A feeder support according to claim 4. in which said arm is adustably turnably positionable relative to the said ring.

6. A feeder support according to claim 5, comprising a fixed plate carried by said ring and supporting means adjustable supporting the arm on the plate for turning movement about the axis of said ring.

7. A feeder support according to claim 5. in which said supporting means comprise at least two arcuate slots coaxial with the axis of said ring and formed in the plate and/or the arm and screw-threaded connection means passing through said arcuate slots and connecting the plate and arm together.

8. A feeder support according to any one of claims 4 to 7, each when dependent on claim 2 or 3, in which said arm is of channel section having a base and spaced apart sides and in which said carrier cases are mounted between said spaced apart sides.

9. A feeder support according to any one of claims 4 to 8, in which said attachment means comprise anchoring members angularly spaced around, and fixed elative to.

said ring.

10. A feeder support according to any one of claims 4 to 9, each when dependent on claim 3, in which the connection means includes adjusting means for enabling adjustment of the mounting position of each carrier case on the said arm.

11. A feeder support for a receiving dish aerial system constructed and arranged substantially as herein described with reference to, and as illustratea in. Figures 1 to 8 of the accompanying drawings.

12. A receiving dish aerial system comprising a receiving dish and, attached thereto, a feeder support as claimed in any one of the preceding claims.

13. A receiving dish aerial system according to claim 2, in which the receiving dish is of parabolic form.