CA1225459A - Satellite dish - Google Patents
Satellite dishInfo
- Publication number
- CA1225459A CA1225459A CA000462791A CA462791A CA1225459A CA 1225459 A CA1225459 A CA 1225459A CA 000462791 A CA000462791 A CA 000462791A CA 462791 A CA462791 A CA 462791A CA 1225459 A CA1225459 A CA 1225459A
- Authority
- CA
- Canada
- Prior art keywords
- axis
- dish
- reflector
- movable
- cradle member
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
- H01Q15/14—Reflecting surfaces; Equivalent structures
- H01Q15/16—Reflecting surfaces; Equivalent structures curved in two dimensions, e.g. paraboloidal
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q1/00—Details of, or arrangements associated with, antennas
- H01Q1/12—Supports; Mounting means
- H01Q1/125—Means for positioning
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Variable-Direction Aerials And Aerial Arrays (AREA)
- Aerials With Secondary Devices (AREA)
Abstract
Abstract:
A satellite dish is required to be pivotally mounted so that it can be trained to receive from different synchronous satellites along the Clarke Belt. The dish is rendered better balanced by arranging for its pivotal axis to pass through its centre of gravity. This axis is slightly inclined to the plane of the rim of the reflector, which plane determines the direction in which the dish is looking. The arrangement enhances the stability of the dish and enables a lighter and less expensive motor drive to be used.
A satellite dish is required to be pivotally mounted so that it can be trained to receive from different synchronous satellites along the Clarke Belt. The dish is rendered better balanced by arranging for its pivotal axis to pass through its centre of gravity. This axis is slightly inclined to the plane of the rim of the reflector, which plane determines the direction in which the dish is looking. The arrangement enhances the stability of the dish and enables a lighter and less expensive motor drive to be used.
Description
r Satellite dish Background to the Invention The invention relates to a so-called satellite dish, that is to say a dish type antenna that can be used for receiving signals from synchronous satellites.
While receiving from a selected satellite the dish will remain in a fixed orien~ation. However J when it is desired to receive signals from one of the other numerous satellites in place in synchronous orbit along the Clarke lQ Belt, it is necessary to rotate the dish to direct it in a different direction. The axis of this rotation will be pointed at the North Pole Star, i.e. will be parallel with the earth's axis. However, the plane of the rim of the dish, which determines the direction in which the dish is "looking" will not be parallel to this axis of rotation.
For proper réception from satellites locat~d along the Clark Belt, the top of the rim of the dish needs to be off-set forwards a few degrees with respect to the axis of dish rotation.
Summary of the Invention The object of the present invention is to provide an improved manner of mounting the dish that will facilitate the Çoregoing geometry, while at the same time minimising the torque requirements for rotating the dish and maximis-~5 ing the stability of the dish while in a given orientation.
~-s~
To this end, the invention consists of a fixed support structure and a movable signal-detecting structure supported on the fixed structure to pivot about an axis that extends substantially through the centre of gravity S of the movable structure.
In a preferred form, the invention consists of a satellite dish comprising (a) an elongate cradle member, (b) means for mounting the cradle member in a ~ixed location at an inclination intermediate a horizontal and a vertical orientation, (c) a movable signal-detecting structure including a paraboloidal reflector, and (d) means at respective ends of the cradle member for pivotally supporting the movable structure about an axis parallel with the earth's axis, (e) said means being connected to the reflector at locations such that the rim of the reflector defines a plane inclined to the horizontal at a greater angle than said pivotal axis, (f) the centre of gravity of the movable structure being located substantially on said pivotal axis.
2Q The dish may include driving means mounted on the cradle member drivingly engaging the movable structure.
In addition, the dish may also be such that the fixed structure can be mounted on a support located substantially ~ertically beneath the centre of gravity of the fixed and movable structures combined.
Brief ~escription of the Drawin~s In the drawings:
Figure 1 is a perspective front view of an embodiment of the invention;
Figure 2 is a side view of Figure l;
Figure 3 is a rear view taken on the line 3-3 in Figure 2 with the pedestal omitted; and Figure 4 is a view on 4-4 in Figure 3.
~;~2Sg~5~3 Detail ~ Embodiment The dish shown in Figure 1 consists o~ a paraboloidal reflector 10 and a horn 11 mounted by means of an arm 12 at the focus of the reflector in the usual way. Since the horn 11 and arm 12 are convent~ional, no further description of them will be given and they have been largely omitted from Figures 2-4.
The reflector 10 is formed from a series of curved spokes 13 radiating from a central connecting member 14 and supporting a wire mesh 15. This mesh 15 is conventional and has been omitted for clarity from Figures 2-4. The free ends o~ the spokes are interconnected by a peripheral -rim 16.
This signal-detecting structure is supported by a fixed structure consisting primarily of a curved, elongate cradle member 17, one end 1~ of which carries an arm 19, the end of which is pivotally connected by a pin 20 to a bracket 20a secured to the lower edge of the rim 16. At its upper end 21 the cradle member 17 carries an arm 22 on 2Q the free end of which there is a pin 23 that pivotally supports a bracket 24 secured to the reflector by means of a bar 25 extending across and connected to three of the spokes 13. The pins 20, 23 are in line with each other and define an axis A (Figure 2) about which the reflector 10 can be rotated relative to the cradle member 17. In normal operation and subject to any adjustment needed from time to time, this cradle member 17 is fixed at 26, for example to a vertical pedestal 27 or other convenient structure (not shown), e.g. the side of a tower.
A circular member 30, centred on the axis A, extends between brackets 31 securing its two ends to a pair of the spokes 13. This bar 30 is engaged by a roller 32 drivable by a motor drive 33 secured to the cradle member 17 by a bracket 34. Rotation of the roller 32 will thus cause the dish to pivot about the axis A. Alternatively, the dish can be rotated manually.
~lZ~S4S~
-- 4 ~
The line B shown in Figure 2 lies in the plane of the rim 16 and in the same vertical plane as the axis A. The plane defined by the rim 16 determines ~he direction in which the dish is looking. The centre of gravity of the 5 movable signal-detecting structure, i.e. the reflector 10, horn 11, arm 12 and bar 30, is at a point Gl that lies o~
or very close to, the axis A. This feature balances the dish and enables a lighter and less expensive motor drive to be used than hitherto. It also avoids any tendency for lQ the reflector to be rotated unintentionally.
The centre of gravity G2 of the entire assembly, i.e.
both the moving and the fixed parts, can conveniently be arranged to be approximately directly above the mounting location 26, although ~his orientation is less important than the orientation of the point Gl and may vary with the manner of mounting the assembly and with the attitude of the assembly. This attitude will depend on the latitude at which the dish is used.
The slight asymmetry observable in Figure 3 whereby the cradle member 17 passes to one side of the centre of the central member 14 of the reflector is provided to balance the weight of the feed horn and its arm.
~2;~S4~9 SUPPLEMENTP~RY DISCLOSURE
.
In the drawings:
Figure 5 is a fragmentary view of a modification; and Figure 6 is a fragmentary view of another modificationO
Figure 5 shows a modification wherein the upper end 21 of the cradle member 17 is telescopic, consisting of an outer part 21a and an inner part 21b carrying the arm 22, the far end of which is connected, as before, to the bar 25 through the pin 23 and the bracket 24. The pin has nuts 23a to anchor it longitudinally in the bracket 24.
The purpose of ~his arrangement is to enable the inner cradle part 21b to be pulled outwardly to tress the dish and ensure it maintains its proper shape. The part 21b can then be fixed in place by a bolt 21d engaging a nut 21c welded to the outer cradle part 21a and passing through such part to engage a roughened surface of the inner part 21b. A lock nut 21e completes the assembly.
Figure 6 shows a modification to the other end of the cradle member 17, i.e. the end 18 which carries the arm 19. The pin 20 is shown connected to the arm 19 at 20e and pivotally supports a sleeve 20d projecting from a plate 20b. The plate 20b has slots 20c engaged by bolts 16b projecting from a bar 16a secured to the rim 16 of the dish. Nuts 16c secure the bolts in the desired location in the slots 20c. Spacers 16d surround the bolts 16b behind the plate 20b.
By moving the bolts to new positions in the slots, it becomes possible to change the angle between the axis A
(defined by the pins 20 and 23) and the plane B of the rim 16. At the equator, for example, this angle should ideally be 5 degrees, while at the North Pole it should be 7.5 degrees, with intermediate values at locations inbetween.
While receiving from a selected satellite the dish will remain in a fixed orien~ation. However J when it is desired to receive signals from one of the other numerous satellites in place in synchronous orbit along the Clarke lQ Belt, it is necessary to rotate the dish to direct it in a different direction. The axis of this rotation will be pointed at the North Pole Star, i.e. will be parallel with the earth's axis. However, the plane of the rim of the dish, which determines the direction in which the dish is "looking" will not be parallel to this axis of rotation.
For proper réception from satellites locat~d along the Clark Belt, the top of the rim of the dish needs to be off-set forwards a few degrees with respect to the axis of dish rotation.
Summary of the Invention The object of the present invention is to provide an improved manner of mounting the dish that will facilitate the Çoregoing geometry, while at the same time minimising the torque requirements for rotating the dish and maximis-~5 ing the stability of the dish while in a given orientation.
~-s~
To this end, the invention consists of a fixed support structure and a movable signal-detecting structure supported on the fixed structure to pivot about an axis that extends substantially through the centre of gravity S of the movable structure.
In a preferred form, the invention consists of a satellite dish comprising (a) an elongate cradle member, (b) means for mounting the cradle member in a ~ixed location at an inclination intermediate a horizontal and a vertical orientation, (c) a movable signal-detecting structure including a paraboloidal reflector, and (d) means at respective ends of the cradle member for pivotally supporting the movable structure about an axis parallel with the earth's axis, (e) said means being connected to the reflector at locations such that the rim of the reflector defines a plane inclined to the horizontal at a greater angle than said pivotal axis, (f) the centre of gravity of the movable structure being located substantially on said pivotal axis.
2Q The dish may include driving means mounted on the cradle member drivingly engaging the movable structure.
In addition, the dish may also be such that the fixed structure can be mounted on a support located substantially ~ertically beneath the centre of gravity of the fixed and movable structures combined.
Brief ~escription of the Drawin~s In the drawings:
Figure 1 is a perspective front view of an embodiment of the invention;
Figure 2 is a side view of Figure l;
Figure 3 is a rear view taken on the line 3-3 in Figure 2 with the pedestal omitted; and Figure 4 is a view on 4-4 in Figure 3.
~;~2Sg~5~3 Detail ~ Embodiment The dish shown in Figure 1 consists o~ a paraboloidal reflector 10 and a horn 11 mounted by means of an arm 12 at the focus of the reflector in the usual way. Since the horn 11 and arm 12 are convent~ional, no further description of them will be given and they have been largely omitted from Figures 2-4.
The reflector 10 is formed from a series of curved spokes 13 radiating from a central connecting member 14 and supporting a wire mesh 15. This mesh 15 is conventional and has been omitted for clarity from Figures 2-4. The free ends o~ the spokes are interconnected by a peripheral -rim 16.
This signal-detecting structure is supported by a fixed structure consisting primarily of a curved, elongate cradle member 17, one end 1~ of which carries an arm 19, the end of which is pivotally connected by a pin 20 to a bracket 20a secured to the lower edge of the rim 16. At its upper end 21 the cradle member 17 carries an arm 22 on 2Q the free end of which there is a pin 23 that pivotally supports a bracket 24 secured to the reflector by means of a bar 25 extending across and connected to three of the spokes 13. The pins 20, 23 are in line with each other and define an axis A (Figure 2) about which the reflector 10 can be rotated relative to the cradle member 17. In normal operation and subject to any adjustment needed from time to time, this cradle member 17 is fixed at 26, for example to a vertical pedestal 27 or other convenient structure (not shown), e.g. the side of a tower.
A circular member 30, centred on the axis A, extends between brackets 31 securing its two ends to a pair of the spokes 13. This bar 30 is engaged by a roller 32 drivable by a motor drive 33 secured to the cradle member 17 by a bracket 34. Rotation of the roller 32 will thus cause the dish to pivot about the axis A. Alternatively, the dish can be rotated manually.
~lZ~S4S~
-- 4 ~
The line B shown in Figure 2 lies in the plane of the rim 16 and in the same vertical plane as the axis A. The plane defined by the rim 16 determines ~he direction in which the dish is looking. The centre of gravity of the 5 movable signal-detecting structure, i.e. the reflector 10, horn 11, arm 12 and bar 30, is at a point Gl that lies o~
or very close to, the axis A. This feature balances the dish and enables a lighter and less expensive motor drive to be used than hitherto. It also avoids any tendency for lQ the reflector to be rotated unintentionally.
The centre of gravity G2 of the entire assembly, i.e.
both the moving and the fixed parts, can conveniently be arranged to be approximately directly above the mounting location 26, although ~his orientation is less important than the orientation of the point Gl and may vary with the manner of mounting the assembly and with the attitude of the assembly. This attitude will depend on the latitude at which the dish is used.
The slight asymmetry observable in Figure 3 whereby the cradle member 17 passes to one side of the centre of the central member 14 of the reflector is provided to balance the weight of the feed horn and its arm.
~2;~S4~9 SUPPLEMENTP~RY DISCLOSURE
.
In the drawings:
Figure 5 is a fragmentary view of a modification; and Figure 6 is a fragmentary view of another modificationO
Figure 5 shows a modification wherein the upper end 21 of the cradle member 17 is telescopic, consisting of an outer part 21a and an inner part 21b carrying the arm 22, the far end of which is connected, as before, to the bar 25 through the pin 23 and the bracket 24. The pin has nuts 23a to anchor it longitudinally in the bracket 24.
The purpose of ~his arrangement is to enable the inner cradle part 21b to be pulled outwardly to tress the dish and ensure it maintains its proper shape. The part 21b can then be fixed in place by a bolt 21d engaging a nut 21c welded to the outer cradle part 21a and passing through such part to engage a roughened surface of the inner part 21b. A lock nut 21e completes the assembly.
Figure 6 shows a modification to the other end of the cradle member 17, i.e. the end 18 which carries the arm 19. The pin 20 is shown connected to the arm 19 at 20e and pivotally supports a sleeve 20d projecting from a plate 20b. The plate 20b has slots 20c engaged by bolts 16b projecting from a bar 16a secured to the rim 16 of the dish. Nuts 16c secure the bolts in the desired location in the slots 20c. Spacers 16d surround the bolts 16b behind the plate 20b.
By moving the bolts to new positions in the slots, it becomes possible to change the angle between the axis A
(defined by the pins 20 and 23) and the plane B of the rim 16. At the equator, for example, this angle should ideally be 5 degrees, while at the North Pole it should be 7.5 degrees, with intermediate values at locations inbetween.
Claims (11)
1. A satellite dish comprising a fixed support structure and a movable signal-detecting structure supported on said fixed structure to pivot about an axis extending substantially through the centre of gravity of the movable structure.
2. A dish according to claim 1, wherein the movable structure includes a paraboloidal reflector having a rim defining a plane, said axis being inclined to said plane.
3. A dish according to claim 2, wherein the fixed structure includes an elongate cradle member located at the rear of said reflector and having means at its respective ends for pivotally supporting the reflector and hence defining said axis.
4. A dish according to claim 3, including driving means mounted on said cradle member and drivingly engaging the movable structure.
5. A dish according to claim 3, including means for mounting the fixed structure on a support located substantially vertically beneath the centre of gravity of the fixed and movable structures combined.
6. A satellite dish comprising (a) an elongate cradle member, (b) means for mounting the cradle member in a fixed location at an inclination intermediate a horizontal and a vertical orientation, (c) a movable signal-detecting structure including a paraboloidal reflector, and (d) means at respective ends of the cradle member for pivotally supporting the movable structure about an axis parallel with the earth's axis, (e) said means being connected to the reflector at locations such that the rim of the reflector defines a plane inclined to the horizontal at a greater angle than said pivotal axis, (f) the centre of gravity of the movable structure being located substantially on said pivotal axis.
7. A dish according to claim 6, including driving means mounted on said cradle member drivingly engaging a circular member on the movable structure described about said axis.
8. A dish according to claim 6, including means for mounting the fixed structure on a support located substantially vertically beneath the centre of gravity of the fixed and movable structures combined.
CLAIMS SUPPORTED BY SUPPLEMENTARY DISCLOSURE
CLAIMS SUPPORTED BY SUPPLEMENTARY DISCLOSURE
9. A dish according to claim 2, including means for varying the inclination of said axis to said plane.
10. A dish according to claim 6, wherein said means for pivotally supporting the movable structure on the cradle member includes means for varying the inclination of said pivotal axis to said rim plane.
11. A dish according to claim 6, wherein said cradle member is expansible for applying a tensioning force to the reflector to enable correction of its shape.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000462791A CA1225459A (en) | 1984-09-10 | 1984-09-10 | Satellite dish |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000462791A CA1225459A (en) | 1984-09-10 | 1984-09-10 | Satellite dish |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1225459A true CA1225459A (en) | 1987-08-11 |
Family
ID=4128679
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000462791A Expired CA1225459A (en) | 1984-09-10 | 1984-09-10 | Satellite dish |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1225459A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0371213A1 (en) * | 1988-09-08 | 1990-06-06 | SELENIA SPAZIO S.p.A. | Linear actuator for antenna pointing, particulary suitable for space applications |
-
1984
- 1984-09-10 CA CA000462791A patent/CA1225459A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0371213A1 (en) * | 1988-09-08 | 1990-06-06 | SELENIA SPAZIO S.p.A. | Linear actuator for antenna pointing, particulary suitable for space applications |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |