Abstract:
An antenna mount with low final lockdown pointing error characteristics especially suited for use with an antenna configuration having an offset center of gravity such as a reflector antenna. The antenna mount having a primary mount with a connecting surface for an azimuth plate; the azimuth plate coupled to the connecting surface by an az-pivot fastener; the azimuth plate pivotable about the az-pivot fastener with respect to the connecting surface; an az-lockdown fastener with an az-lockdown head coupled to the connecting surface; the az-lockdown fastener passing through the an az-lockdown slot of the azimuth plate; a retaining spacer of the az-lockdown fastener positioned in the az-lockdown slot between the connecting surface and an underside of the az-lockdown fastener head; the retaining spacer having a height greater than a thickness of the azimuth plate.

Description:
BACKGROUND 
       [0001]    For optimal performance, a directional antenna such as a reflector antenna must be closely aligned with a target signal source. Alignment of a reflector antenna is typically performed via an adjustable antenna mount that, with respect to a fixed mounting point, is adjustable in azimuth and elevation to orient the antenna towards the target signal source. 
         [0002]    Antenna mount coarse adjustment is often cost effectively incorporated into an antenna mount via a movable connection coupled to a fixed point, for example via one or more slot(s) and or a pivot point and a slot along which the pivot angle of the movable connection may be fixed by tightening one or more fasteners. Fine adjustments are difficult to make in these arrangements because the targeting resolution along the slot(s) is very low due to the free movement of the movable connection until the bolt(s) are tightened. Further, the weight of the antenna acts as a cantilever on the associated fasteners, distorting the selected alignment by biasing the fasteners towards an open rather than lock down fastener position. After the desired alignment has been achieved, for example by monitoring signal peaking, tightening these fasteners to the lock down position causes the alignment to shift back, causing a pointing error that cannot be readily compensated by the installer. Furthermore, when the fastener(s) are tightened, imperfect bearing and contact points between the adjusting surfaces can cause additional pointing error as the mechanism distorts. 
         [0003]    Where multiple feeds are applied to a single reflector to simultaneously receive closely spaced beams from different satellites, precision alignment is critical to achieve acceptable signal performance with respect to each of the satellites. High resolution adjustment capability may also be used for a single feed reflector and or terrestrial applications where precision alignment is desired. For example, the Ka Band has an especially strict alignment requirement 
         [0004]    The adjustable antenna mount must support the entire antenna mass and also withstand any expected environmental factors such as wind shear and or ice loading. However, adjustable antenna mounts that are both sufficiently strong and easily adjustable with precision significantly increase the overall cost of the resulting antenna. 
         [0005]    U.S. Pat. No. 7,046,210 “Precision Alignment Mount” by Brooker et al, issued May, 16, 2006, co-owned with the present invention by Andrew Corporation of Westchester, Ill., hereby incorporated by reference in the entirety, discloses an antenna mount with fine adjustment capabilities that applies bias springs and or belliview washers to minimize final tightening shift. However, these springs and or spring washers add complexity to the assembly operation, additional materials cost and over time the spring force of these elements may degrade, reducing their effect. 
         [0006]    The increasing competition for reflector antennas and associated mounting assemblies adapted for both industrial and high volume consumer applications such as data, VSAT, satellite tv and or internet communications has focused attention on cost reductions resulting from increased materials, manufacturing and service efficiencies. Further, reductions in required assembly operations and the total number of discrete parts are desired. 
         [0007]    Therefore, it is an object of the invention to provide an apparatus that overcomes deficiencies in the prior art. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the general and detailed descriptions of the invention appearing herein, serve to explain the principles of the invention. 
           [0009]      FIG. 1  is an exploded isometric view of an exemplary embodiment of the invention. 
           [0010]      FIG. 2  is an elevated isometric rear angle view of the  FIG. 1  antenna mount, assembled. 
           [0011]      FIG. 3  is a rear view of  FIG. 1 , assembled. 
           [0012]      FIG. 4  is a top view of  FIG. 1 , assembled. 
           [0013]      FIG. 5  is a top view of  FIG. 1 , assembled. 
           [0014]      FIG. 6  is a simplified exploded isometric view of portions of  FIG. 1 . 
           [0015]      FIG. 7  is a partially exploded front isometric view of the  FIG. 1  antenna mount, antenna mounting surface removed. 
           [0016]      FIG. 8  is a cross sectional close-up view of  FIG. 3 , along line B-B. 
           [0017]      FIG. 9  is a cross sectional close-up view of  FIG. 4 , along line L-L. 
           [0018]      FIG. 10  is a cross sectional close-up view of  FIG. 5 , along line I-I. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    An exemplary embodiment of a fine adjusting antenna mount with improved final azimuth and elevation final lockdown pointing error characteristics is shown for example in  FIGS. 1-10 . A primary mount  2  is adapted to secure the antenna mount upon a desired mounting point. In the present embodiment, the primary mount  2  is a pipe clamp adapted to mount upon the end of a cylindrical mounting pole or mast (not shown) via clamp fasteners  4  such as a coach bolt  6  and serrated nut  8 . Alternatively, the primary mount  2  may be any rigid connection to a desired mounting point. Coarse azimuth adjustment is effected by rotation of the primary mount  2  about the mounting point prior to final tightening of the, for example, clamp fasteners  4 . The top of the primary mount  2  is provided with connecting surfaces  10  for an azimuth plate  12 , here shown as a U-bracket with generally parallel azimuth angled ends  14 . The connecting surfaces  10  are demonstrated as generally normal to a longitudinal axis of the primary mount  2 . 
         [0020]    Fine azimuth adjustments are provided by a pivot action of the azimuth plate  12  with respect to the connecting surfaces  10  about an az-pivot fastener  16 , such as a short neck coach bolt that couples the azimuth plate  12  to a connecting surface  10 . Alternatively, the az-pivot fastener  16  may be a removable and or fastening force adjustable nut and bolt or a permanently connected fastener such as a rivet. A washer  18  ( FIG. 6 ) or the like may be applied between the connecting surface  10  and the azimuth plate  12  at the az-pivot fastener  16  to improve the motion of the pivot action. The pivot action about the az-pivot fastener  16  is regulated by at least one az-lockdown fastener  20  connected to the connecting surface  10  via an az-lockdown slot  22  formed with an arc radius generally about the az-pivot fastener  16 . The extents of the az-lockdown slot  22  define the range of available fine azimuth adjustment between the connecting surfaces  10  and the azimuth plate  12 . An az-retaining nut  24  couples the az-lockdown fastener  20  to the connecting surface  10 . The present embodiment is demonstrated with two az-lockdown fasteners  20  at two spaced apart connecting surfaces  10  and two corresponding az-lockdown slots  22  formed in the azimuth plate  12 . Depending upon the dimensions and or design loads of the desired antenna and mounting assembly, any number of az-lockdown fasteners  20  and corresponding az-lockdown slots  22  may be applied. One skilled in the art will recognize that an equivalent alternative structure is the location of the az-lockdown slots  22  in the az-lockdown fastener  20  connecting surfaces  10  of the primary mount, in addition to or rather than in the azimuth plate  12 . 
         [0021]    Fine azimuth adjustment of the antenna mount may be driven by rotation of an azimuth bolt  26 . For example, the azimuth bolt  26  may be rotatably retained at a fixed end  28  to the azimuth plate  12  via a pair of split inserts  32  keyed to and retained around a groove  34  of the azimuth bolt  26 , the split inserts  32  held within a plummer pin  36  fixed to the azimuth plate  12 . At a movable end  30  the azimuth bolt  26  threads into, for example, a threaded insert  38  seated in another plummer pin  36  formed in the head  40  of one of the az-lockdown fasteners  20 . Incremental rotation of the azimuth bolt  26 , rotatably fixed to the azimuth plate  12  and threadably connected to an az-lockdown fastener  20 , the az-lockdown fastener  20  coupled to a connecting surface  10 , operates to pivot the azimuth plate  12  about the az-pivot fastener  16  in fine increments proportional to the thread pitch of the azimuth bolt  26  threads. 
         [0022]    Operator feedback indicia related to the azimuth fine adjustment may also be incorporated in the antenna mount. An az-thimble  42  with graduated indicia  44  of, for example, 0-100 graduations may be added to the azimuth bolt  26  to enable repeated fine tuning of known increments less than a full rotation of the azimuth bolt  26  with respect to a stationary reference point. 
         [0023]    Elevation adjustment functionality may be added to the antenna mount via the addition of a generally U-shaped elevation bracket  46  with elevation angled ends  48  arranged to rotate around an elevation pivot formed by el-pivot fasteners  50  that couple the elevation angled end(s)  48  of the elevation bracket  46  to the azimuth angled ends  14  of the azimuth plate  12 . For ease of rotation and a reduced manufacturing precision requirement, elevation pivot washers  52  may be applied to the el-pivot fasteners  50 . 
         [0024]    A selected elevation angle of the elevation bracket  46  about the elevation pivot may be locked by el-lockdown fasteners  54  coupling the elevation bracket  46  to the azimuth angled ends  14  through corresponding arc slots  56  formed in the elevation angled ends  48  having a radius of curvature generally about the elevation pivot. 
         [0025]    The antenna may be directly coupled to the elevation bracket  46  via, for example, mounting tabs  58  ( FIG. 3 ) or to an antenna mounting surface  59  that then is coupled to the mounting tabs  58 . The antenna mounting surface  58  is useful where a further rotational tilt adjustment mechanism is desired between the antenna and the antenna mount. To reduce the number of discrete components, the antenna mounting surface  59  may be permanently coupled to the mounting tabs  58  and or elevation bracket  46  via rivets, spot welding or the like. 
         [0026]    The antenna (not shown) attachment typically results in a combined center of gravity that is located forward of the az-pivot fastener  16 . Therefore, a cantilever effect acting on a fulcrum at the az-pivot fastener  16  will urge a gap to open between the azimuth plate  12  and the primary mount  2  connecting surfaces  10  at the az-lockdown fasteners  20  when the az-lockdown fasteners  20  are loosened for azimuth adjustment, thus causing a lockdown shift when the az-lockdown fasteners  20  are finally locked down. To counteract pointing errors arising from the cantilever effect and lockdown shift, the present invention, as best shown in  FIGS. 3 ,  6  and  8 , applies a retaining spacer  60  inserted along the az-lockdown fasteners  20 , seated within the az-lockdown slots  22  between the az-lockdown fastener head  62  and the connecting surface  10 . The retaining spacers  60  each have a height selected to be slightly more than a thickness of the azimuth plate  12 . Thereby, when the az-retaining nuts  24  are tightened against the connecting surface  10 , the underside of the az-lockdown fastener heads  62  form a retaining surface spaced away from the connection plate  20  by the height of the retaining spacers  60 , retaining the azimuth plate  12  against the connecting surface  20 . Because the azimuth plate  12  is slightly thinner than the retaining spacer height  60 , the pivot action of the azimuth plate  12  about the az-pivot fastener  16  is still enabled and any gap between the azimuth plate  12  and the connecting surfaces  10  of the primary mount  2  due to the cantilever effect is maintained as a constant. 
         [0027]    Alternatively, the retaining spacer  60  may be formed integral with the az-lockdown fastener  20  as a shoulder of the desired height below the az-lockdown fastener head  62 . The shoulder having a diameter less than the diameter of the az-lockdown slot  22  but larger than the associated connecting surface  10  az-lockdown fastener  20  hole. 
         [0028]    To finally lock down the azimuth plate  12  with respect to the connecting surfaces  20 , an az-lockdown spacer  64  having at least one projection  66  that passes around the az-retaining nut  24  and through a corresponding projection hole  68  in the connecting surface  10  is retained at the bottom of the az-lockdown fasteners  20  by an az-lockdown nut  70 . Preferably, at least two projections  66  are applied, so that the az-lockdown spacer  64  seats evenly via the projections  66  against the azimuth plate  12 . Because the projections  66  pass through projection holes  68  of the connecting surfaces  10 , a compression force is not applied between the azimuth plate  12  and the connecting surfaces  10  as the az-lockdown nut  70  is tightened against the azimuth lockdown spacer  64 , driving the projections  66  to lock against the azimuth plate  12  to prevent further pivot of the azimuth plate  12  via the az-lockdown slots  22 . 
         [0029]    Similar to the azimuth fine adjustment, as best shown in  FIGS. 5 and 10 , fine elevation adjustment functionality may be added to an antenna mount according to the invention by the addition of an elevation bolt  72  coupled between the elevation bracket  46  and at least one of the el-lockdown fastener(s)  54 . As the elevation bracket  46  may be adapted to move though a wide angular range of movement, the threaded elevation bolt  72  connection to the elevation bracket  46  is provided with a corresponding angular movement capability. An aperture  74  in the elevation bracket  46  may be formed with rounded edge(s) adapted to seat and rotatably key an elevation pointer  76  rotatably coupled to the elevation bolt  72 . The elevation pointer  76  is retained in the aperture  74  against the elevation bracket  46 , for example, by an elevation bolt nut  78  fixed in place upon the elevation bolt  72  by crimping, thread adhesive or the like. An el-thimble  80  with graduated indicia  44  of, for example, 0-100 graduations may be added, keyed to the elevation bolt  72 , between the elevation pointer  76  and the head of the elevation bolt  72  to provide high resolution operator feedback on the threading progress of the elevation bolt  72  to pivot the elevation bracket  46  to a desired angle about the elevation pivot. Angular changes occurring at the el-lockdown fastener  54  that the elevation bolt  72  threads into, for example via another threaded insert  38  that fits into a plummer pin  36  of an el-lockdown fastener  54 , are compensated for by rotation of the threaded insert  38  within the plummer pin  36 . 
         [0030]    To minimize lockdown shift introduced with respect to the elevation adjustment, as best shown in  FIGS. 7 and 9 , the el-lockdown fastener  54  may be fitted with a washer  82  and an elevation spacer  84 . The washer  82  and elevation spacer  84  initially fill an oversized elevation fastener hole  86  of the azimuth angled end  14 . As tightening progresses, the elevation spacer  84 , deforms and expands to fully fill the elevation fastener hole  86  but retains enough thickness to prevent the underside of the el-lockdown fastener bolt head  88  from contacting the azimuth angled end  14 . The washer  82 , generally sized to fill the elevation fastener hole  86  operates to prevent the elevation spacer  84  from projecting into the arc slot  56  as it deforms and expands. Because the underside of the el-lockdown fastener bolt head  88  never contacts the azimuth angled end  14 , potential for deformation of the azimuth angled end  14  is reduced, minimizing the introduction of lockdown shift from final tightening of the el-lockdown fasteners  54 . Alternatively and or in combination, as best shown in  FIG. 10 , the el-lockdown fastener  54  may be supplied with an el-retaining nut  90 , pre-tightened to a point where elevation pivoting remains enabled but where minimal play remains, and an el-lockdown spacer  92  which fits around the el-retaining nut  90  to bear upon the elevation angled end, retained by an el-lockdown nut  94 . 
         [0031]    One skilled in the art will appreciate that the main components of the invention may be cost effectively fabricated by metal stamping. Alternatively, die casting and or injection molding may be applied. The specific exemplary embodiment of the invention described herein in detail is demonstrated with respect to a vertical pole mounting but may alternatively be readily adapted to a particular desired mounting surface and or mounting surface orientation. While the present invention has been demonstrated with mating u-brackets, equivalent elevation pivoting structures may be formed by mating angle or T-brackets having sufficient materials strength to withstand the expected weight and environmental stresses upon the antenna mount. 
         [0032]    The present invention provides an antenna mount with precision alignment capability having significantly reduced complexity and manufacturing precision requirements, resulting in a significant reduction in overall cost. Also, the time required for installation and configuration of a reflector antenna incorporating an antenna mount according to the invention is similarly reduced by high resolution of alignment adjustments enabled by the azimuth and or elevation bolts  26 ,  72 , aided by the graduated indicia of the az-thimble  42  and el-thimble  80 . 
         [0000]    
       
         
               
             
               
               
             
           
               
                   
               
               
                 Table of Parts 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 2 
                 primary mount 
               
               
                 4 
                 clamp fastener 
               
               
                 6 
                 coach bolt 
               
               
                 8 
                 serrated nut 
               
               
                 10 
                 connecting surface 
               
               
                 12 
                 azimuth plate 
               
               
                 14 
                 azimuth angled end 
               
               
                 16 
                 az-pivot fastener 
               
               
                 18 
                 washer 
               
               
                 20 
                 az-lockdown fastener 
               
               
                 22 
                 az-lockdown slot 
               
               
                 24 
                 az-retaining nut 
               
               
                 26 
                 azimuth bolt 
               
               
                 28 
                 fixed end 
               
               
                 30 
                 movable end 
               
               
                 32 
                 split insert 
               
               
                 34 
                 groove 
               
               
                 36 
                 plummer pin 
               
               
                 38 
                 threaded insert 
               
               
                 40 
                 head 
               
               
                 42 
                 az-thimble 
               
               
                 44 
                 graduated indicia 
               
               
                 46 
                 elevation bracket 
               
               
                 48 
                 elevation angled end 
               
               
                 50 
                 el-pivot fastener 
               
               
                 52 
                 elevation pivot washer 
               
               
                 54 
                 el-lockdown fastener 
               
               
                 56 
                 arc slot 
               
               
                 58 
                 mounting tab 
               
               
                 59 
                 antenna mounting surface 
               
               
                 60 
                 retaining spacer 
               
               
                 62 
                 az-lockdown fastener head 
               
               
                 64 
                 az-lockdown spacer 
               
               
                 66 
                 projection 
               
               
                 68 
                 projection hole 
               
               
                 70 
                 az-lockdown nut 
               
               
                 72 
                 elevation bolt 
               
               
                 74 
                 aperture 
               
               
                 76 
                 elevation pointer 
               
               
                 78 
                 elevation bolt nut 
               
               
                 80 
                 el-thimble 
               
               
                 82 
                 washer 
               
               
                 84 
                 elevation spacer 
               
               
                 86 
                 elevation fastener hole 
               
               
                 88 
                 el-lockdown fastener head 
               
               
                 90 
                 el-retaining nut 
               
               
                 92 
                 el-lockdown spacer 
               
               
                 94 
                 el-lockdown nut 
               
               
                   
               
             
          
         
       
     
         [0033]    Where in the foregoing description reference has been made to ratios, integers, components or modules having known equivalents then such equivalents are herein incorporated as if individually set forth. 
         [0034]    While the present invention has been illustrated by the description of the embodiments thereof, and while the embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, representative apparatus, methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departure from the spirit or scope of applicant&#39;s general inventive concept. Further, it is to be appreciated that improvements and/or modifications may be made thereto without departing from the scope or spirit of the present invention as defined by the following claims.