WO1992007394A1

WO1992007394A1 - Satellite antenna

Info

Publication number: WO1992007394A1
Application number: PCT/GB1991/001813
Authority: WO
Inventors: David Macgregor
Original assignee: D-Mac International Limited
Priority date: 1990-10-18
Filing date: 1991-10-17
Publication date: 1992-04-30
Also published as: GB9022688D0

Abstract

A satellite antenna capable of receiving signals from one or more, preferably at least two, satellites comprising a concave dish (2) and one or more receiver units (9, 10). Each receiver unit (9, 10) is positioned to the front and to one side of the dish (2), such that in use the dish (2) is fixed at an angle of elevation and azimuth between those of the one or more satellites and signals incoming from the one or more satellites are reflected by the dish (2) to the appropriate receiver unit (9, 10).

Description

Satellite antenna

This invention relates to satellite antennae, and in particular to a satellite antenna capable of receiving signals from more than one satellite.

There has been a recent upsurge in the availability of domestic satellite television channels. This is due to the launching of a number of DBS (Direct Broadcast Satellites) . These are a new breed of high-powered satellites which are specifically designed to beam television signals direct to customers equipped with relatively small satellite antennae - otherwise known as satellite dishes. These DBS are positioned within the Clar.:e belt in a geostationary orbit, i.e. they are approximately positioned 36000kn above th-a equator and travel in the same direction as the earth's rotation. The result of this is that the satellite effectively remains above the same point on the earth's surface.

A number of types of satellite antenna presently exist, e.g. the prime focus type, the offset type and the flat plate type. Such antennae are fixed dishes capable of receiving incoming signals from only one satellite at any one time.

In order to receive signals from more than one satellite users must erect a separate antenna for each satellite of interest. However, due to the implementation of recent planning regulations in the UK, householders can erect only one antenna without permission. For a second antenna they must apply to the local authority for planning permission. Accordingly satellite antennae which are capable of receiving signals from more than one satellite have been proposed. However, these tend to be expensive, operationally unreliable and/or larger than conventional antennae.

It is therefore an object of the present invention to obviate or mitigate the aforementioned disadvantages in the prior art. It is a further object of the present invention to provide a fixed dish capable of receiving incoming signals from one or more satellites.

Accordingly one aspect of the present invention provides, a satellite antenna comprising a concave dish, at least two receiver units and support means arranged such that each receiver unit is movably locatable relative to the concave surface of the dish.

According to a second aspect of the present invention there is provided, a method of receiving signals from at least two satellites which comprises locating a separate receiver unit for each satellite signal relative to a concave receiving dish having its concave surface directed between the location of such satellites.

According to a third aspect of the present invention there is provided a satellite antenna capable of receiving signals from one or more satellites comprising a concave dish and one or more receiver units, wherein each receiver unit is positioned to the front and to one side of the dish, such that in use the dish is fixed at an angle of elevation and azimuth between those of the one or more satellites and signals incoming from the one or more satellites are reflected by the dish to the appropriate receiver unit. Each receiver unit may be positioned by means of a plurality of rods, a first end of each rod being attached to the dish at a suitable location thereon, a second end of each rod being attached to the receiver unit, the pitch and/or length of each rod being variable in order that the receiver unit can be moved to an optimum position to receive an incoming signal.

Alternatively, the receiver units may be supported on a polar bar, (i.e. a bar the curvature of which is such that a receiver unit supported at a point on the bar will receive, via the dish, signals incoming from a satellite located at a corresponding position along the polar arc of the earth) the polar bar being oriented substantially horizontally and being supported at or near the mid-point thereof by a support bar, the first end of the support bar being attached to the dish" at or near the lower edge thereof, the second end of the support bar being attached to the polar bar, the position of each receiver being variable along the polar bar and the pitch and/or length of the support bar being variable in order that each receiver can be moved to an optimum position to receive an incoming signal.

Preferably, there are only two satellites from which transmission signals are desired to be received and there are therefore provided only two receiver units. For example, one may be suitable for receiving BSB transmission signals and the other Sky transmission signals.

Preferably also, in use the dish is oriented so as to point in a direction substantially between the angles of aziπuth and elevation of the satellites of interest, the- receiver units being positioned so as to receive the optimum signal reflected from the dish transmitted by the respective satellites.

Preferably also, the dish is appropriately shaped so as to reflect the optimum signal to a receiver from a corresponding satellite.

According to another aspect of the present invention there is provided a polar bar, as hereinbefore defined, suitable for retaining one or more receiver units, the bar further being capable of being attached to a second end of a support bar, the first end of the support bar being attached to a concave dish at or near the lower edge thereof.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:-

Fig. 1 - is a perspective view from the front and to one side of a prime focus autenna according to the prior art;

Fig. 2 - is a perspective view from the front and to one side of an offset autenna according to the prior art;

Fig. 3 - is a perspective view from the front and to one side of a flat plate autenna according to the prior art; k-

Fig. -4 - is a perspective view from the front and to one side of a first embodiment of a satellite antenna according to the present invention;

Fig. 5 - is a view from the front of the satellite antenna of Fig. 4;

Fig. 6 - is a view from the top of the satellite antenna of Fig. 4;

Fig. 7 - is a cross-sectional view from the side of the satellite antenna of Fig. 4;

Fig. 8 - is a view from the front of a second embodiment of a satellite antenna according to the present invention; and

Fig. 9 - is a view from the front of a third embodiment of a satellite antenna (not to scale) according to the present invention.

Referring to Figs. 4 to 7, there is provided a first embodiment of a satellite antenna, generally designated 1, according to the present invention.

This embodiment is suitable for receiving signals from the satellites Marcopolo 1 and Astra 1A which trans ite signals for BSB and Sky Television respectively.

The antenna 1 comprises a concave dish 2 and a polar bar 3, the polar bar 3 being supported at the front of the dish 2 by means of a support bar 4.

A first end of the support bar 4 is attached to support means 13 (Fig. 7) at the rear of the dish 2. A u-bend 14 in the support bar 4 allows the bar 4 to bend round a bottom edge 6 of the dish 2 at or near the centre of the bottom edge 6.

A second end 7 of the support bar 4 is attached to the polar bar 3 by means of a first fastener 8 at or near the centre of the polar bar 3.

Two receiver units 9 and 10 are supported on the polar bar 3, one receiver unit 9 being suitable for receiving signals from BSB television, the second receiver unit 10 being suitable for receiving signals from Sky Television. Each unit 9, 10 is supported on the polar bar 3 by means of a jubilee clip (registered trade mark) 11, 12 or the like. This allows the receivers 9, 10 to be adjustably moved to any desired location along the polar bar 3. Each receiver unit 9, 10 comprises a feedhorn 15 connected to a low noise block converter (LNB) 16 by means of a waveguide 17.

The support means 13 comprise a planar member 18 having an arcuate slot 19, the arcuate slot 19 being capable of receiving a bolt on an antenna support (not shown) . This allows the antenna 1 to be suitably located while further allowing the angle of elevation of the dish 2 to be varied.

In use, the reguired angle of elevation and azimuth of the dish 2 is dependant upon both the location on the earth at which the antenna 1 is located, and also the satellites of interest. For example, Glasgow is 4.25° West, Marcopolo 1 is 31.00° West and Astra 1A is 19.21° East. Accordingly, as would be obvious to any skilled person, the required angles of elevation and azimuth for Marcopolo l from Glasgow are 22.01° and 205.67° respectively. Further, the required angles of elevation and azimuth for Astra 1A from Glasgow are 23.03° and 157.28°.

In order to set up the antenna 1, the dish 2 would therefore be set between these angles of elevation and azimuth, the exact position being dependent upon which incoming signal is the stronger.

The receiver units 9, 10 will then be moved to separate points on the polar bar 3 where they receive the respective incoming signals from the two satellites, and the position of the dish and receivers fine-tuned until the optimum signals are received.

The signals so received may then be fed to separate receiver units or to separate decoders and thence to a receiver unit. Alternatively, it may be envisaged that a single receiver unit may be provided for both signals.

Referring to Fig. 8, there is provided a second embodiment of a satellite antenna, generally designated 1', according to the present invention. In the same way as the first embodiment, this embodiment is suitable for receiving signals from the satellites Marcopolo 1 and Astra 1A, transmitting signals for BSB and Sky television respectively.

The antenna 1' comprises a concave dish 2' and two sets of three support rods 20', 21', 22', each set of rods being capable of supporting a receiver unit 9' , 10' .

The first ends of the support rods 20' are hingably connected to the dish 2' at a point on the dish 2' at or near an upper edge thereof. The second ends of the support rods 20* are suitably attached to the respective receiver unit 9' or 10* . Likewise the first end of each support rod 21' is hingably connected to the dish 2' at a point on the dish 2" at or near a lower edge thereof, the second end of each support rod 21' being suitably attached to the respective receiver unit 9' or 10' .

The first ends of support rods 22' are threadably connected to holes on the dish 22 ' at or near respective side edges thereof. The second ends of support rods 22' are suitably attached to the respective receiver unit 9* or 10' .

In this way, two receiver units 9' and 10' can be supported in front and to respective sides of the dish 2' .

In operation, the dish 2* is positioned and set-up in a similar way as the first embodiment. In the second embodiment, however, the position of the receiver units 9', 10' with respect to the dish 2' may be varied by varying the length of the support rod 22' between the receiver unit and the dish 2 ' and also by varying the angle of pitch of the support rods 20', 21*.

Referring to Fig. 9, there is provided a third embodiment of a satellite antenna, generally designated 1", according to the present invention. In the same way as the other embodiments, this embodiment is suitable for receiving signals from two satellites simultaneously.

The antenna 1" comprises a concave dish 2" and a polar bar 3", the polar bar 3" being supported to the front of the dish 2" by means of a support bar 4".

A first end 5" of the support bar 4" is suitably attached to the dish 2" at or near a lower edge thereof. A T second enc^" 7" of the support bar 4" is attached to the polar bar 3" at cr near the centre of the polar bar 3".

A plurality of vertical spaced holes 23" are provided on the horizontal axis and to one side of the dish 2" near the edge thereof. A corresponding plurality of vertically spaced holes 24" are provided on the horizontal axis and to the other side of the dish 2" near the edge thereof.

The plurality of holes 23" are equally spaced from one another, and may, for example, be spaced from one another by 1° with respect to the focal point of the dish. The plurality of holes 24" are spaced likewise.

A first end of the polar bar 3" is attachable to any one c the plurality of holes 23", and a second end of the polar bar 3" is attachable to any one cf the plurality cf r.oie≤ 24".

In this way the angle of the polar bar 3" from the horizontal may be varied. This may be particularly important if the angles of elevation of the satellites of interest are not close together, as would be apparent to any skilled person.

The embodiments of the invention described hereinbefore provide fixed satellite antennae capable of receiving signals from two satellites simultaneously. This capability is particularly useful for multi-user locations, such as blocks of flats, where different users desire to view different channels.

It should, however, be appreciated that these embodiments are given by way of example only and are not meant to limit the scope of the invention in any way. Particularly is should be appreciated that if more than two receiver units are provided then incoming signals from more than two satellites can be received.

Claims

sClaims

1. A satellite antenna comprising a concave dish, at least two receiver units and support means arranged such that each receiver unit is movably locatable relative to the concave surface of the dish.

2. A satellite antenna capable of receiving signals from one or more satellites comprising a concave dish and one or more receiver units, wherein each receiver unit is positioned to the front and to one side of the dish, such that in use the dish is fixed at an angle of elevation and azimuth between those of the one or more satellites and signals incoming from the one or more satellites are reflected by the dish to the appropriate receiver unit.

3. A satellite antenna as claimed in claim 1 or 2 wherein the or each receiver unit is positioned by means of a plurality of rods, a first end of each rod being attached to the dish at a suitable location thereon, a second end of each rod being attached to the receiver unit, the pitch and/or length of each rod being variable in order that the receiver unit can be moved to an optimum position to receive an incoming signal.

4. A satellite antenna as claimed in claim 1 or 2 wherein the or each receiver unit is supported on a polar bar, (i.e. a bar the curvature of which is such that a receiver unit supported at a point on the bar will receive, via the dish, signals incoming from a satellite located at a corresponding position along the polar arc of • the earth) the polar bar being oriented substantially horizontally and being supported at or near the mid-point thereof by a support bar, the first end of the support bar being attached to the dish at or near the lower edge thereof, the second end of the support bar being attached to the polar bar, the position of each receiver being variable along the polar bar and the pitch and/or length of the support bar being variable in order that.each receiver can be moved to an optimum position to receive an incoming signal.

5. A satellite antenna as claimed in any preceding claim wherein two receivers are provided.

6. A satellite antenna as claimed in any preceding claim wherein the dish is appropriately shaped so as to reflect the optimum signal to a receiver from a corresponding satellite.

7. A polar bar, as hereinbefore defined, suitable for retaining one or more receiver units, the bar further being capable of being attached to a second end of a support bar, the first end of the support bar being attached to a concave dish at or near the lower edge thereof.

8. A method of receiving signals from at least two satellites which comprises locating a separate receiver unit for each satellite signal relative to a concave receiving dish having its concave surface directed between the location of such satellites.

9. A method of receiving signals from at least two satellites as claimed in claim 8 wherein the dish is oriented so as to point in a direction substantially between the angles of azimuth and elevation of the satellites of interest, the receiver units being positioned so as to receive the optimum signals reflected from the dish transmitted by the respective satellites.