ANTENNA SLEW SYSTEM
United States Patent 3646564
An antenna azimuthal positioning mechanism formed from pairs of elongated antenna supporting struts pivotally mounted on a fixed support structure and extending both outwardly and in crossed relationship therefrom to pivotally connect with an antenna whereby the antenna pivots with respect to the supporting struts as the supporting struts carry the antenna past an end of the fixed support structure to give a partial view to the rear of the support structure and thereby provide an azimuth sector scan subtending an arc which is greater than the pivoting arc of any one of the supporting struts. The supporting struts can be disconnected from the antenna to facilitate transfer of the antenna to a telescoping stowage support for antenna stowage.
US Patent References:
Positioning device continuous in azimuth and elevation using multiple linear drives
Storm - November 1965 - 3215391
Scanning reflector on stabilized platform having a stowed position
Clemence et al. - November 1966 - 3286265
Torsionally decoupled antenna support
Lapp - January 1967 - 3296621
Scanning dish reflector having a stowed position
Bergling - November 1968 - 3412404
/2734710.html
Noble - February 1956 - 2734710
Positioning device continuous in azimuth and elevation using multiple linear drives
Storm - November 1965 - 3215391
Scanning reflector on stabilized platform having a stowed position
Clemence et al. - November 1966 - 3286265
Torsionally decoupled antenna support
Lapp - January 1967 - 3296621
Scanning dish reflector having a stowed position
Bergling - November 1968 - 3412404
/2734710.html
Noble - February 1956 - 2734710
Application Number:
04/803626
Publication Date:
02/29/1972
Filing Date:
03/03/1969
View Patent Images:
Export Citation:
Assignee:
Raytheon Company (Lexington, MA)
Primary Class:
Other Classes:
343/872, 74/96, 343/881, 74/89
International Classes:
H01Q1/12; H01Q3/06; H01Q3/02; H01Q3/00
Field of Search:
343/757,762,763,765,766,760,872,881 74/89,96
US Patent References:
| 3253473 | Mechanical linkage | May 1966 | Chisholm |
Primary Examiner:
Lieberman, Eli
Claims:
What is claimed is
1. An antenna positioning mechanism for carrying an antenna through a sector scan comprising:
2. The apparatus of claim 1 including stowage means, said stowage means having the form of an enclosed shelter means with an entrance adjacent to said antenna, said support struts having means for disconnection of said antenna from said struts, and means for guiding said antenna after said disconnection into said stowage means.
3. An antenna positioning mechanism for carrying an antenna through a sector scan comprising:
4. A positioning mechanism for scanning radiating means through a sector comprising:
5. An antenna positioning mechanism for carrying an antenna through a sector scan comprising:
6. An antenna positioning mechanism carrying an antenna through a sector scan comprising:
7. A positioning mechanism for sector scanning a radiating device comprising radiating means, a fixed support structure enclosing a stowage means contained therein, retractable guide arm means mounted to said stowage means and telescopically extending from within said enclosed stowage means to said radiating means, positioning means including at least one rigid member pivotally interconnecting said radiating means to said fixed support structure and adapted to carry said radiating means in a path of sector scan towards an extended position of said guide arm means, and means for disconnecting said radiating means from said positioning means to transfer said radiating means from said positioning means to said guide arm means for antenna stowage.
8. An antenna positioning mechanism comprising:
9. An antenna positioning mechanism for carrying an antenna through a sector scan comprising:
10. An antenna positioning mechanism for carrying an antenna through a sector scan comprising:
1. An antenna positioning mechanism for carrying an antenna through a sector scan comprising:
2. The apparatus of claim 1 including stowage means, said stowage means having the form of an enclosed shelter means with an entrance adjacent to said antenna, said support struts having means for disconnection of said antenna from said struts, and means for guiding said antenna after said disconnection into said stowage means.
3. An antenna positioning mechanism for carrying an antenna through a sector scan comprising:
4. A positioning mechanism for scanning radiating means through a sector comprising:
5. An antenna positioning mechanism for carrying an antenna through a sector scan comprising:
6. An antenna positioning mechanism carrying an antenna through a sector scan comprising:
7. A positioning mechanism for sector scanning a radiating device comprising radiating means, a fixed support structure enclosing a stowage means contained therein, retractable guide arm means mounted to said stowage means and telescopically extending from within said enclosed stowage means to said radiating means, positioning means including at least one rigid member pivotally interconnecting said radiating means to said fixed support structure and adapted to carry said radiating means in a path of sector scan towards an extended position of said guide arm means, and means for disconnecting said radiating means from said positioning means to transfer said radiating means from said positioning means to said guide arm means for antenna stowage.
8. An antenna positioning mechanism comprising:
9. An antenna positioning mechanism for carrying an antenna through a sector scan comprising:
10. An antenna positioning mechanism for carrying an antenna through a sector scan comprising:
Description:
BACKGROUND OF THE INVENTION
This invention relates to antenna positioning and support mechanisms and more particularly to an improved azimuthal positioning mechanism which is mounted on the side of a support structure or shelter and provides increased sector scan capability.
Conventional radar antennas are usually mounted either on top of a supporting structure such as a shelter for housing the electronics equipment or at some distance from the shelter in order to permit continuous azimuthal scanning through a 360° field of view which is unobstructed by the structure or shelter. In certain applications a continuous scanning of 360° in azimuth is not required, as in the surveillance of an airport runway, or may be impracticable to implement such as on a ship where the antenna may have to be mounted near a mast, or where space requirements preclude the mounting of the antenna on top of a structure. In each of these applications, it is frequently desirable to utilize a simpler form of antenna positioning mechanism which provides only a sector scan, and which can be mounted on the side of a structure such as the shelter. It is desirable to provide a side-mounted positioning mechanism that will provide a maximum sector scan angle in the range of 270° to 360° by swinging the antenna from one corner of the shelter to the other so that the antenna has at least a partial view towards the rear.
The side mounting of the antenna is advantageous for maintenance and checkout since the antenna is low enough to be within easy reach of service personnel. In the case of portable radar sets completely self-contained within a shelter, the side mounting of the antenna reduces the chance of a strong wind overturning the radar as might occur if a large antenna was mounted on top of the shelter, and also facilitates disconnection of the antenna for stowage.
It is therefore an object of the present invention to provide an azimuthal positioning mechanism side-mounted on a shelter for supporting and directing an antenna.
It is a further object of the invention to provide an improved side-mounted positioning mechanism for rigidly supporting an antenna and providing increased sector scan coverage.
It is also an object of the invention to provide a side-mounted antenna positioning mechanism having a compact form which facilitates stowage of the mechanism and the antenna.
SUMMARY OF THE INVENTION
An antenna positioning mechanism formed from at least one pair of elongated antenna supporting struts pivotally mounted at an end thereof to a fixed support structure and extending outwardly therefrom to pivotally connect with an antenna which pivots with respect to the supporting struts as the supporting struts carry the antenna around at least a portion of the fixed support structure, the supporting struts in said pair of supporting struts being crossed at an angle which varies with antenna position.
In a preferred embodiment the supporting struts are pivotally mounted to swing in horizontal planes so that the antenna scans an azimuthal sector subtending an arc which is larger than the pivoting arc of any of said supporting struts. The supporting struts can be disconnected from the antenna to facilitate transfer of the antenna to a telescoping stowage support for antenna stowage.
BRIEF DESCRIPTION OF THE DRAWINGS
The aforementioned objects and other features of the invention are explained in the following description taken in connection with the accompanying drawings wherein:
FIG. 1 is a pictorial view of a portable radar system employing the antenna positioning mechanism of the invention;
FIG. 2 is a plan view exposing the drive mechanism and waveguide assembly in the antenna positioning mechanism of the invention;
FIG. 3 is a diagrammatic plan view of the positioning mechanism showing three positions of the antenna, one central position and two extreme positions, and the corresponding geometric configurations of the supporting struts of the antenna positioning mechanism;
FIG. 4 is an isometric view, partially cut away, of a portion of a supporting strut of the antenna positioning mechanism exposing the waveguide and cabling connections;
FIG. 5 is an isometric view, partially cut away and exploded, of a hinge assembly and power train of one of the supporting struts of the antenna positioning mechanism;
FIG. 6 is a pictorial view of the portable radar system showing the antenna in a folded configuration, and a telescoping stowage support extending from the interior of a shelter to the antenna; and
FIG. 7 is a perspective view, partially cut away, of a portable radar system with the antenna tilted in a horizontal position preparatory to stowage within the shelter.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIGS. 1, 2, and 3, there is shown, respectively, a pictorial view, a plan view, and a diagrammatic plan view of a side-mounted antenna positioning mechanism in accordance with the invention utilized in conjunction with a portable electronically beam-steered radar for airport runway surveillance. The side-mounted antenna positioning mechanism is a four-arm mechanical linkage indicated generally by 20 for supporting radiating means such as a radar antenna 22 at an end of a portable shelter 24 which serves as a fixed support structure for the linkage 20. The linkage 20, composed of upper struts or arms 26 and 28, and lower struts or arms 30 and 32, each being of a common length, is connected to the antenna 22 at four points along its edge by hinges 34, 36, 38, and 40 to which the aforementioned struts are respectively pivotally connected to provide stability in the presence of strong wind forces. The hinges 34, 36, 38 and 40 are carried by the struts in arcuate paths and protrude outwardly from the back side of antenna 22 to provide clearance of antenna frame 42 for the struts 26, 28, 30 and 32. The other end of each of these struts is pivotally mounted to the shelter 24 respectively by means of hinges 44, 46, 48, and 50, so that, as shown in FIG. 3, these struts carry the antenna 22 through a curved path in the horizontal plane. The upper struts 26 and 28 are in crossed relation to each other, and similarly, the lower struts 30 and 32 are in crossed relation to each other to provide a pivoting of the antenna 22 through a larger angle than the pivot angle of any one of the aforementioned struts with the result that, as shown in FIG. 3, the antenna 22 has a partial view to the rear of shelter 24.
Referring specifically to FIG. 2, each of the struts has the form of a rigid beam having a hollow interior, one of which serves as a passage by which electrical conductors are brought out from the shelter to the antenna. Accordingly, one of the struts, namely strut 28 shown in phantom plan view in FIG. 2, serves as a passage for waveguide 52 and cabling 54. Electromagnetic energy and radar beam-steering signals are transferred from radar electronics equipment 56 having transmission, receiving, and beam-steering means, not shown, by means of waveguide 52 and cabling 54 respectively to antenna feed 58 and phased array subreflector 60 which are supported by boom 62. A rotary joint 64 is provided within hinge 46, as described in greater detail in FIG. 5, in order to connect waveguide 52 to a stationary waveguide 66 which, in turn, is connected to the transmission and receiving portion of electronics equipment 56. At the other end of strut 28, a second rotary joint 68, having the same form as rotary joint 64, is provided within hinge 36 to connect waveguide 52 with boom waveguide 70 so that electromagnetic energy can be transferred via these waveguides irrespective of the antenna azimuth position. Waveguide 52 is formed from two sections, a long rigid section 52A connected to a shorter flexible section 52B, which permits alignment at the flanges 72A and 72B for mating the two waveguide sections. Also, cabling 54 is formed from two sections, namely, a section 54A within strut 28 and a second section 54B in boom 62, which are joined by a connector 74 to permit disconnection and reconnection of section 54A from the antenna prior to stowage as will be described. Two electric drive motors 76 and 78 located near the upper corners of shelter 24 are mechanically connected respectively to struts 26 and 28 by means of gear trains 80 and 82, partially shown in FIG. 2, to impart pivotal motion about the hinges 44 and 46 to the struts 26 and 28 and thereby position the antenna 22 in azimuth.
Referring specifically to FIG. 3, the antenna 22 is shown in two positions of maximum azimuthal extension and a third position in which the antenna 22 is centered along the end of shelter 24. FIG. 3 shows three positions of the struts 26 and 28 corresponding to the aforementioned three antenna positions by means of solid and dashed lines, the solid lines being used to show the orientations of the struts 26 and 28 for the centered position of antenna 22. The struts 30 and 32, not shown, are positioned respectively beneath struts 26 and 28. The hinges 34, 36, 38 and 40 protrude outwardly from the back side of antenna 22 to accommodate the struts in a position of maximum azimuthal extension so that, for example, the strut 28 passes beneath hinge 34 in a maximum clockwise azimuthal extension, and the strut 26 passes above hinge 36 in a maximum counterclockwise azimuth extension. The angular velocity or rotation rate of upper strut 26 and lower strut 30 are always equal and, in general, different from the rotation rate of struts 28 and 32. It is readily apparent that a linear rotation rate of any strut is accompanied by a nonlinear rotation rate of the antenna 22, and that the average rotation rate of the antenna 22 from one maximum azimuthal extension to the other maximum azimuthal extension is approximately double the average rotation rate of any of the struts 26, 28, 30 and 32 since antenna 22 rotates in azimuth approximately 270° while each strut rotates approximately 135°, as seen in FIG. 3. The maximum sector scan of antenna 22 can be increased beyond 270° by a further extension of the hinges 34, 36, 38 and 40 outwardly from the back side of antenna 22.
Referring now to FIG. 4, there is shown a portion of upper strut 28, partially cut away to expose waveguide 52 and cabling 54 as seen in FIG. 2. The waveguide flanges 72A and 72B are held together by bolts 73. Cabling connector 74 has connecting sections 74A and 74B which are held together by screws such as screw 75 located behind access cover 84 which is hinged about hinge 85 in a sidewall of the strut 28. FIG. 4 also shows strut flanges 86A and 86B held together by bolts and nuts such as bolt 87A and nut 87B, by means of which strut 28 can be disassembled into two sections, as is done for antenna stowage to be described in connection with FIG. 6.
Referring now to FIG. 5, there is shown a detailed isometric view of hinge 46 attached to shelter 24 as seen in FIG. 2, partially cut away, and showing hinge bracket 88 which pivotally supports strut end fitting 90 by means of two pins 92A and 92B about which strut 28 pivots. The upper portion of fitting 90 is provided with gear segment 94 which is driven by pinion 96 mounted on vertical shift 102 supported by bracket 88. Pinion 96 is of smaller diameter than gear segment 94 to provide a torque multiplication for pivoting strut 28 about pins 92A and 92B. Pinion 96 is connected to drive gear 100 which extends through an aperture 98 in the vertical sidewall of bracket 88 into engagement with motor pinion 104 located within shelter 24. Drive gear 100 rotates with pinion 96 about shaft 102 and is in turn driven by motor pinion 104 directly connected by motor shaft 105 to electric motor 78 and to a brake 106 for restraining the antenna 22 against wind loading. Electric motor 78 rotates pinion 104 to impart torque to drive gear 100. The waveguides 52 and 66 are connected to a well-known rotary joint 64 respectively by means of pairs of mounting flanges 108 and 110, secured together by bolts 111. The axis of rotary joint 64 coincides with the axis of hinge 46, so that electromagnetic energy can be transferred to and from the antenna for all angles of pivot of strut 28.
An angle sensing device such as potentiometer 112 is mounted coaxially with the axis of hinge 46 by means of bracket 114 affixed to hinge bracket 88 by means of screws such as screw 89. Potentiometer shaft 115 is connected by means of a well-known antibacklash shaft coupling 116 to extension 117 of pin 92A which is connected rigidly to fitting 90 and rotates with strut 28 to provide a voltage signal in accordance with the angular disposition of strut 28 relative to stationary bracket 88. The voltage signal of potentiometer 112 is transmitted along electrical conductors 118 to electronics equipment 56 shown in FIG. 2 and provides an indication of antenna azimuth position based on the geometric relationship of the azimuth angle of antenna 22 of FIG. 3 to the angle of strut 28 relative to shelter 24.
Hinge 44, shown in FIG. 2, which is mechanically connected to its motor 76 through gear train 80, operates in an analogous manner to hinge 46.
In operation, therefore, the electric motors 76 and 78 are energized from a source of electric power, not shown, to impart rotation to the gears of gear trains 80 and 82, as seen in FIG. 2, the gear diameters being selected to provide a torque multiplication through the gear trains 80 and 82 whereby the motors 76 and 78 can impart sufficient torque to the upper struts 26 and 28 to redirect the antenna 22 even in the presence of opposition forces of wind blowing against the antenna 22. The brake 106 connected to motor 78 and a similar brake, not shown, connected to motor 76 retain the antenna 22 in a fixed position when motors 76 and 78 are deenergized. Rotary joints 64 and 68 located respectively within hinges 46 and 36 at the ends of strut 28 provide for the coupling of electromagnetic power from electronics equipment 56 to antenna 22 through waveguides 66, 52, and 70 independently of the various relative positions of antenna 22 and strut 28 to shelter 24.
In order to store antenna 22 within shelter 24, each strut or arm of linkage 20 is readily adapted to become disconnected from antenna 22. The stowage procedure, shown in FIGS. 6 and 7, begins with the removal of access panel 120, shown in FIG. 1 to provide an entrance into shelter 24 for the antenna. Panel 120 is preferably made from a lightweight material such as well-known aluminum-foam sandwich and is located between the upper and lower struts in the front end of shelter 24. The panel is removed with the aid of handgrips, not shown. Antenna 22 is then positioned along the centerline of shelter 24 as shown in FIG. 3 and FIG. 6. The bottom flap 122 of antenna 22 is folded up manually about hinges 124, shown in FIG. 1 and FIG. 6, to decrease the antenna length so that the antenna 22 can be fitted into the shelter 24.
Also the boom 62 is folded inwardly toward the face of the antenna about hinge 126 after unbolting hinge flanges 127 and waveguide flanges 71A, shown in FIG. 2, by means of an access panel, now shown. In like manner, microwave feed 58 containing waveguide 70, as shown in FIGS. 1 and 2, if folded inwardly along boom 62 toward subreflector 60 by a hinge and flange structure similar to that of hinge 126, although not shown, after unbolting waveguide flanges 71B located behind an access panel, not shown. The folding of boom 62 and feed 58 is done preparatory to antenna stowage so that when the antenna 22 is moved into the shelter 24 as shown in FIG. 7, the antenna clears the electronics equipment 56 in the shelter.
The antenna 22 is guided into the shelter 24 by guide arm means such as telescoping slides 128 which are attached to interior sidewalls of shelter 24. Slides 128 are extended out manually in a well-known manner from shelter 24 to be pivotally attached to the antenna 22 at slide brackets 130 and 132 secured to antenna 22, and located respectively beneath hinges 34 and 36. The pivotal attachment is effected by means of pins 134, one of which is passed through an aperture, not shown, in the end of each slide 128 and into a similar aperture in brackets 130 and 132. In order to compensate for sag in the struts 26, 28, 30 and 32 due to the weight of antenna 22 each slide 128 is pivotally mounted near the front end of shelter 24 by means of slide pivot 136 located on the interior wall of shelter 24, as shown in FIG. 7, so that the extended portion of each slide 128 carrying pin 134 can be raised or lowered to line up with brackets 130 and 132 on the antenna. This raising and lowering of the extended portion of a slide 128 is accomplished by means such as a rotatable bolt 138 threading vertically through a well-known threaded end fitting 139 on the back end of slide 128, as shown in the cutaway portion of FIG. 7, and journaled in a fixed bracket 140 which is attached, as by bolting, to the wall of shelter 24, thus permitting bolt 138 to rotate and move slide 128 relative to the fixed bracket 140. The rotatable bolt 138 terminates at its upper end in a hexagonal fitting 142 to mate with a wrench by which bolt 138 is manually rotated to urge the end of slide 128 vertically and thereby compensate for sag in the struts 26, 28, 30 and 32. This arrangement permits pins 134 to be inserted into brackets 130 and 132. The bolts 138 in each slide 128 are then further rotated to shift the antenna weight from the linkage 20 to the slides 128.
The waveguide 52 and cabling 54, shown in FIGS. 2 and 4, are then disconnected from the antenna as shown in FIG. 4, by opening the access cover 84 in strut 28 and then unbolting waveguide flanges 72A and 72B, and opening the cabling connector 74. The four struts 26, 28, 30, and 32 are then disassembled by unbolting the flanges adjacent to the antenna hinges in each strut, such as the pair of flanges 86A and 86B in strut 28 to free the antenna 22 from the struts.
The stowage procedure is completed by folding the four struts 26, 28, 30 and 32 inwardly towards the shelter 24 until they are aligned within the shelter as shown in FIG. 7. By tilting antenna 22 about the axis of the pins 134, it is brought into a horizontal position as shown in FIG. 7. The tilting operation can be accomplished manually since the slide brackets 130 and 132 are located approximately along an axis through the center of gravity of the antenna. The antenna 22 is then slid into the shelter 24 and the access panel 120 is replaced. To erect the antenna, the foregoing procedure is repeated in reverse order. In this manner, the entire radar system is rapidly converted into a form which is readily transportable to another site whereupon it can be manually set up for operation.
It is understood that the above-described embodiments of the invention are illustrative only and that modifications thereof will occur to those skilled in the art. Accordingly, it is desired that the invention is not to be limited to the embodiments disclosed herein but is to be limited only as defined by the appended claims.
This invention relates to antenna positioning and support mechanisms and more particularly to an improved azimuthal positioning mechanism which is mounted on the side of a support structure or shelter and provides increased sector scan capability.
Conventional radar antennas are usually mounted either on top of a supporting structure such as a shelter for housing the electronics equipment or at some distance from the shelter in order to permit continuous azimuthal scanning through a 360° field of view which is unobstructed by the structure or shelter. In certain applications a continuous scanning of 360° in azimuth is not required, as in the surveillance of an airport runway, or may be impracticable to implement such as on a ship where the antenna may have to be mounted near a mast, or where space requirements preclude the mounting of the antenna on top of a structure. In each of these applications, it is frequently desirable to utilize a simpler form of antenna positioning mechanism which provides only a sector scan, and which can be mounted on the side of a structure such as the shelter. It is desirable to provide a side-mounted positioning mechanism that will provide a maximum sector scan angle in the range of 270° to 360° by swinging the antenna from one corner of the shelter to the other so that the antenna has at least a partial view towards the rear.
The side mounting of the antenna is advantageous for maintenance and checkout since the antenna is low enough to be within easy reach of service personnel. In the case of portable radar sets completely self-contained within a shelter, the side mounting of the antenna reduces the chance of a strong wind overturning the radar as might occur if a large antenna was mounted on top of the shelter, and also facilitates disconnection of the antenna for stowage.
It is therefore an object of the present invention to provide an azimuthal positioning mechanism side-mounted on a shelter for supporting and directing an antenna.
It is a further object of the invention to provide an improved side-mounted positioning mechanism for rigidly supporting an antenna and providing increased sector scan coverage.
It is also an object of the invention to provide a side-mounted antenna positioning mechanism having a compact form which facilitates stowage of the mechanism and the antenna.
SUMMARY OF THE INVENTION
An antenna positioning mechanism formed from at least one pair of elongated antenna supporting struts pivotally mounted at an end thereof to a fixed support structure and extending outwardly therefrom to pivotally connect with an antenna which pivots with respect to the supporting struts as the supporting struts carry the antenna around at least a portion of the fixed support structure, the supporting struts in said pair of supporting struts being crossed at an angle which varies with antenna position.
In a preferred embodiment the supporting struts are pivotally mounted to swing in horizontal planes so that the antenna scans an azimuthal sector subtending an arc which is larger than the pivoting arc of any of said supporting struts. The supporting struts can be disconnected from the antenna to facilitate transfer of the antenna to a telescoping stowage support for antenna stowage.
BRIEF DESCRIPTION OF THE DRAWINGS
The aforementioned objects and other features of the invention are explained in the following description taken in connection with the accompanying drawings wherein:
FIG. 1 is a pictorial view of a portable radar system employing the antenna positioning mechanism of the invention;
FIG. 2 is a plan view exposing the drive mechanism and waveguide assembly in the antenna positioning mechanism of the invention;
FIG. 3 is a diagrammatic plan view of the positioning mechanism showing three positions of the antenna, one central position and two extreme positions, and the corresponding geometric configurations of the supporting struts of the antenna positioning mechanism;
FIG. 4 is an isometric view, partially cut away, of a portion of a supporting strut of the antenna positioning mechanism exposing the waveguide and cabling connections;
FIG. 5 is an isometric view, partially cut away and exploded, of a hinge assembly and power train of one of the supporting struts of the antenna positioning mechanism;
FIG. 6 is a pictorial view of the portable radar system showing the antenna in a folded configuration, and a telescoping stowage support extending from the interior of a shelter to the antenna; and
FIG. 7 is a perspective view, partially cut away, of a portable radar system with the antenna tilted in a horizontal position preparatory to stowage within the shelter.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIGS. 1, 2, and 3, there is shown, respectively, a pictorial view, a plan view, and a diagrammatic plan view of a side-mounted antenna positioning mechanism in accordance with the invention utilized in conjunction with a portable electronically beam-steered radar for airport runway surveillance. The side-mounted antenna positioning mechanism is a four-arm mechanical linkage indicated generally by 20 for supporting radiating means such as a radar antenna 22 at an end of a portable shelter 24 which serves as a fixed support structure for the linkage 20. The linkage 20, composed of upper struts or arms 26 and 28, and lower struts or arms 30 and 32, each being of a common length, is connected to the antenna 22 at four points along its edge by hinges 34, 36, 38, and 40 to which the aforementioned struts are respectively pivotally connected to provide stability in the presence of strong wind forces. The hinges 34, 36, 38 and 40 are carried by the struts in arcuate paths and protrude outwardly from the back side of antenna 22 to provide clearance of antenna frame 42 for the struts 26, 28, 30 and 32. The other end of each of these struts is pivotally mounted to the shelter 24 respectively by means of hinges 44, 46, 48, and 50, so that, as shown in FIG. 3, these struts carry the antenna 22 through a curved path in the horizontal plane. The upper struts 26 and 28 are in crossed relation to each other, and similarly, the lower struts 30 and 32 are in crossed relation to each other to provide a pivoting of the antenna 22 through a larger angle than the pivot angle of any one of the aforementioned struts with the result that, as shown in FIG. 3, the antenna 22 has a partial view to the rear of shelter 24.
Referring specifically to FIG. 2, each of the struts has the form of a rigid beam having a hollow interior, one of which serves as a passage by which electrical conductors are brought out from the shelter to the antenna. Accordingly, one of the struts, namely strut 28 shown in phantom plan view in FIG. 2, serves as a passage for waveguide 52 and cabling 54. Electromagnetic energy and radar beam-steering signals are transferred from radar electronics equipment 56 having transmission, receiving, and beam-steering means, not shown, by means of waveguide 52 and cabling 54 respectively to antenna feed 58 and phased array subreflector 60 which are supported by boom 62. A rotary joint 64 is provided within hinge 46, as described in greater detail in FIG. 5, in order to connect waveguide 52 to a stationary waveguide 66 which, in turn, is connected to the transmission and receiving portion of electronics equipment 56. At the other end of strut 28, a second rotary joint 68, having the same form as rotary joint 64, is provided within hinge 36 to connect waveguide 52 with boom waveguide 70 so that electromagnetic energy can be transferred via these waveguides irrespective of the antenna azimuth position. Waveguide 52 is formed from two sections, a long rigid section 52A connected to a shorter flexible section 52B, which permits alignment at the flanges 72A and 72B for mating the two waveguide sections. Also, cabling 54 is formed from two sections, namely, a section 54A within strut 28 and a second section 54B in boom 62, which are joined by a connector 74 to permit disconnection and reconnection of section 54A from the antenna prior to stowage as will be described. Two electric drive motors 76 and 78 located near the upper corners of shelter 24 are mechanically connected respectively to struts 26 and 28 by means of gear trains 80 and 82, partially shown in FIG. 2, to impart pivotal motion about the hinges 44 and 46 to the struts 26 and 28 and thereby position the antenna 22 in azimuth.
Referring specifically to FIG. 3, the antenna 22 is shown in two positions of maximum azimuthal extension and a third position in which the antenna 22 is centered along the end of shelter 24. FIG. 3 shows three positions of the struts 26 and 28 corresponding to the aforementioned three antenna positions by means of solid and dashed lines, the solid lines being used to show the orientations of the struts 26 and 28 for the centered position of antenna 22. The struts 30 and 32, not shown, are positioned respectively beneath struts 26 and 28. The hinges 34, 36, 38 and 40 protrude outwardly from the back side of antenna 22 to accommodate the struts in a position of maximum azimuthal extension so that, for example, the strut 28 passes beneath hinge 34 in a maximum clockwise azimuthal extension, and the strut 26 passes above hinge 36 in a maximum counterclockwise azimuth extension. The angular velocity or rotation rate of upper strut 26 and lower strut 30 are always equal and, in general, different from the rotation rate of struts 28 and 32. It is readily apparent that a linear rotation rate of any strut is accompanied by a nonlinear rotation rate of the antenna 22, and that the average rotation rate of the antenna 22 from one maximum azimuthal extension to the other maximum azimuthal extension is approximately double the average rotation rate of any of the struts 26, 28, 30 and 32 since antenna 22 rotates in azimuth approximately 270° while each strut rotates approximately 135°, as seen in FIG. 3. The maximum sector scan of antenna 22 can be increased beyond 270° by a further extension of the hinges 34, 36, 38 and 40 outwardly from the back side of antenna 22.
Referring now to FIG. 4, there is shown a portion of upper strut 28, partially cut away to expose waveguide 52 and cabling 54 as seen in FIG. 2. The waveguide flanges 72A and 72B are held together by bolts 73. Cabling connector 74 has connecting sections 74A and 74B which are held together by screws such as screw 75 located behind access cover 84 which is hinged about hinge 85 in a sidewall of the strut 28. FIG. 4 also shows strut flanges 86A and 86B held together by bolts and nuts such as bolt 87A and nut 87B, by means of which strut 28 can be disassembled into two sections, as is done for antenna stowage to be described in connection with FIG. 6.
Referring now to FIG. 5, there is shown a detailed isometric view of hinge 46 attached to shelter 24 as seen in FIG. 2, partially cut away, and showing hinge bracket 88 which pivotally supports strut end fitting 90 by means of two pins 92A and 92B about which strut 28 pivots. The upper portion of fitting 90 is provided with gear segment 94 which is driven by pinion 96 mounted on vertical shift 102 supported by bracket 88. Pinion 96 is of smaller diameter than gear segment 94 to provide a torque multiplication for pivoting strut 28 about pins 92A and 92B. Pinion 96 is connected to drive gear 100 which extends through an aperture 98 in the vertical sidewall of bracket 88 into engagement with motor pinion 104 located within shelter 24. Drive gear 100 rotates with pinion 96 about shaft 102 and is in turn driven by motor pinion 104 directly connected by motor shaft 105 to electric motor 78 and to a brake 106 for restraining the antenna 22 against wind loading. Electric motor 78 rotates pinion 104 to impart torque to drive gear 100. The waveguides 52 and 66 are connected to a well-known rotary joint 64 respectively by means of pairs of mounting flanges 108 and 110, secured together by bolts 111. The axis of rotary joint 64 coincides with the axis of hinge 46, so that electromagnetic energy can be transferred to and from the antenna for all angles of pivot of strut 28.
An angle sensing device such as potentiometer 112 is mounted coaxially with the axis of hinge 46 by means of bracket 114 affixed to hinge bracket 88 by means of screws such as screw 89. Potentiometer shaft 115 is connected by means of a well-known antibacklash shaft coupling 116 to extension 117 of pin 92A which is connected rigidly to fitting 90 and rotates with strut 28 to provide a voltage signal in accordance with the angular disposition of strut 28 relative to stationary bracket 88. The voltage signal of potentiometer 112 is transmitted along electrical conductors 118 to electronics equipment 56 shown in FIG. 2 and provides an indication of antenna azimuth position based on the geometric relationship of the azimuth angle of antenna 22 of FIG. 3 to the angle of strut 28 relative to shelter 24.
Hinge 44, shown in FIG. 2, which is mechanically connected to its motor 76 through gear train 80, operates in an analogous manner to hinge 46.
In operation, therefore, the electric motors 76 and 78 are energized from a source of electric power, not shown, to impart rotation to the gears of gear trains 80 and 82, as seen in FIG. 2, the gear diameters being selected to provide a torque multiplication through the gear trains 80 and 82 whereby the motors 76 and 78 can impart sufficient torque to the upper struts 26 and 28 to redirect the antenna 22 even in the presence of opposition forces of wind blowing against the antenna 22. The brake 106 connected to motor 78 and a similar brake, not shown, connected to motor 76 retain the antenna 22 in a fixed position when motors 76 and 78 are deenergized. Rotary joints 64 and 68 located respectively within hinges 46 and 36 at the ends of strut 28 provide for the coupling of electromagnetic power from electronics equipment 56 to antenna 22 through waveguides 66, 52, and 70 independently of the various relative positions of antenna 22 and strut 28 to shelter 24.
In order to store antenna 22 within shelter 24, each strut or arm of linkage 20 is readily adapted to become disconnected from antenna 22. The stowage procedure, shown in FIGS. 6 and 7, begins with the removal of access panel 120, shown in FIG. 1 to provide an entrance into shelter 24 for the antenna. Panel 120 is preferably made from a lightweight material such as well-known aluminum-foam sandwich and is located between the upper and lower struts in the front end of shelter 24. The panel is removed with the aid of handgrips, not shown. Antenna 22 is then positioned along the centerline of shelter 24 as shown in FIG. 3 and FIG. 6. The bottom flap 122 of antenna 22 is folded up manually about hinges 124, shown in FIG. 1 and FIG. 6, to decrease the antenna length so that the antenna 22 can be fitted into the shelter 24.
Also the boom 62 is folded inwardly toward the face of the antenna about hinge 126 after unbolting hinge flanges 127 and waveguide flanges 71A, shown in FIG. 2, by means of an access panel, now shown. In like manner, microwave feed 58 containing waveguide 70, as shown in FIGS. 1 and 2, if folded inwardly along boom 62 toward subreflector 60 by a hinge and flange structure similar to that of hinge 126, although not shown, after unbolting waveguide flanges 71B located behind an access panel, not shown. The folding of boom 62 and feed 58 is done preparatory to antenna stowage so that when the antenna 22 is moved into the shelter 24 as shown in FIG. 7, the antenna clears the electronics equipment 56 in the shelter.
The antenna 22 is guided into the shelter 24 by guide arm means such as telescoping slides 128 which are attached to interior sidewalls of shelter 24. Slides 128 are extended out manually in a well-known manner from shelter 24 to be pivotally attached to the antenna 22 at slide brackets 130 and 132 secured to antenna 22, and located respectively beneath hinges 34 and 36. The pivotal attachment is effected by means of pins 134, one of which is passed through an aperture, not shown, in the end of each slide 128 and into a similar aperture in brackets 130 and 132. In order to compensate for sag in the struts 26, 28, 30 and 32 due to the weight of antenna 22 each slide 128 is pivotally mounted near the front end of shelter 24 by means of slide pivot 136 located on the interior wall of shelter 24, as shown in FIG. 7, so that the extended portion of each slide 128 carrying pin 134 can be raised or lowered to line up with brackets 130 and 132 on the antenna. This raising and lowering of the extended portion of a slide 128 is accomplished by means such as a rotatable bolt 138 threading vertically through a well-known threaded end fitting 139 on the back end of slide 128, as shown in the cutaway portion of FIG. 7, and journaled in a fixed bracket 140 which is attached, as by bolting, to the wall of shelter 24, thus permitting bolt 138 to rotate and move slide 128 relative to the fixed bracket 140. The rotatable bolt 138 terminates at its upper end in a hexagonal fitting 142 to mate with a wrench by which bolt 138 is manually rotated to urge the end of slide 128 vertically and thereby compensate for sag in the struts 26, 28, 30 and 32. This arrangement permits pins 134 to be inserted into brackets 130 and 132. The bolts 138 in each slide 128 are then further rotated to shift the antenna weight from the linkage 20 to the slides 128.
The waveguide 52 and cabling 54, shown in FIGS. 2 and 4, are then disconnected from the antenna as shown in FIG. 4, by opening the access cover 84 in strut 28 and then unbolting waveguide flanges 72A and 72B, and opening the cabling connector 74. The four struts 26, 28, 30, and 32 are then disassembled by unbolting the flanges adjacent to the antenna hinges in each strut, such as the pair of flanges 86A and 86B in strut 28 to free the antenna 22 from the struts.
The stowage procedure is completed by folding the four struts 26, 28, 30 and 32 inwardly towards the shelter 24 until they are aligned within the shelter as shown in FIG. 7. By tilting antenna 22 about the axis of the pins 134, it is brought into a horizontal position as shown in FIG. 7. The tilting operation can be accomplished manually since the slide brackets 130 and 132 are located approximately along an axis through the center of gravity of the antenna. The antenna 22 is then slid into the shelter 24 and the access panel 120 is replaced. To erect the antenna, the foregoing procedure is repeated in reverse order. In this manner, the entire radar system is rapidly converted into a form which is readily transportable to another site whereupon it can be manually set up for operation.
It is understood that the above-described embodiments of the invention are illustrative only and that modifications thereof will occur to those skilled in the art. Accordingly, it is desired that the invention is not to be limited to the embodiments disclosed herein but is to be limited only as defined by the appended claims.