Abstract:
A receptacle with an adjusting slot is adapted to receive a mounting lip of the feed assembly. A means for positioning which may include a threaded shaft threaded into a first side of the receptacle that projects into a first side of the mounting lip, is operative to move the mounting lip within the adjusting slot. A bias spring may be positioned between the mounting lip and a second side of the mounting lip, the bias spring biasing the mounting lip against the threaded shaft. Alternatively, the threaded shaft may extend threaded through the mounting lip, longitudinally retained with respect to the receptacle operative to move the mounting lip along the adjusting slot as the threaded shaft is rotated.

Description:
BACKGROUND 
     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. 
     Because the entire antenna assembly is adjusted, the adjustable antenna mount must be designed to support the entire antenna mass and also withstand any expected environmental factors such as wind shear and or ice loading. Adjustable antenna mounts that are both strong and easily adjustable with precision significantly increase the cost of the resulting antenna. 
     High resolution azimuth adjustment capability is increasingly important for multiple feed reflector antennas used with satellites positioned in equatorial orbit. Where multiple feeds are applied to a single reflector to simultaneously receive closely spaced beams from different satellites, alignment is critical to achieve acceptable signal performance with respect to each of the satellites. Although equatorial orbits are generally constant by definition, in reality there is a certain range of azimuth “wobble” to an equatorial orbit that determines the precise position of the satellite at any given instant. When multiple satellites are targeted using multiple feeds of a common reflector the “wobble” position of each satellite may at one extreme or the other unacceptably degrade performance of the other signals as they move through their own ranges of positional “wobble”. High resolution adjustment capability may also be used for a single feed reflector and or terrestrial applications where precision accuracy is required. 
     To avoid configuring a reflector antenna for a primary satellite alignment other than the middle of a known wobble range an installation technician first aligns the antenna for maximum signal strength with respect to the primary satellite. Then, by contacting a satellite ground control resource the installation technician can obtain a desired azimuth offset representing the present distance of the primary satellite from the center of its wobble range. These adjustments are extremely small, creating a need for azimuth adjustments that are easy to perform, accurately controlled, easily measurable and reliably repeatable for a given input. 
     The increasing competition for reflector antennas adapted for high volume consumer applications such as 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. 
     Therefore, it is an object of the invention to provide an apparatus that overcomes deficiencies in the prior art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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. 
         FIG. 1  is a schematic front view of a first exemplary embodiment of the invention, shown applied to a feed assembly. 
         FIG. 2  is a schematic isometric close-up view of  FIG. 1 , with the receptacle and a portion of the feed assembly cover omitted for clarity. 
         FIG. 3  is a schematic close-up view of  FIG. 1 , normal to a cross section of the receptacle, demonstrating a left range of adjustment. 
         FIG. 4  is a schematic close-up view of  FIG. 1 , normal to a cross section of the receptacle, demonstrating a right range of adjustment. 
         FIG. 5  is a schematic isometric close-up view of a second exemplary embodiment of the invention, with the receptacle and a portion of the feed assembly cover omitted for clarity. 
         FIG. 6  is a schematic close-up view of the alternative embodiment, normal to a cross section of the receptacle, demonstrating a left range of adjustment. 
         FIG. 7  is a schematic close-up view of the alternative embodiment, normal to a cross section of the receptacle, demonstrating a right range of adjustment. 
         FIG. 8  is a schematic isometric view of a first adjustment scale embodiment, fine adjusting hardware omitted for clarity. 
         FIG. 9  is a schematic isometric view of a second adjustment scale embodiment fine adjusting hardware omitted for clarity. 
         FIG. 10  is a schematic isometric view of a third adjustment scale embodiment fine adjusting hardware omitted for clarity. 
     
    
    
     DETAILED DESCRIPTION 
     Applicant has recognized that rather than adjusting the entire antenna structure, accurate azimuth fine tuning functionality may be cost effectively implemented by adjusting the feed assembly with respect to the feed assembly connection with the boom arm and or the reflector of the antenna. A small adjustment to the orientation of the feed assembly with respect to the reflector adjusts the, for example, azimuth beam alignment but does not significantly affect alignment of the feed assembly with a focal area of the reflector. 
     A first exemplary embodiment of the invention is shown in  FIGS. 1–4 . A feed assembly  2  is coupled to a receptacle  4  such as an adjusting collar  6  that is in turn mounted to a boom arm of the reflector antenna (not shown). Existing feed assembly  2  configurations may have a mounting lip  8  adapted to fit into the open end of a hollow boom arm. These configurations may be readily adapted according to the invention with a minimum of additional adaptations. The mounting lip  8  is inserted into an adjusting slot  10  of the receptacle  4 , here demonstrated as an adjusting collar  6 . Alternatively, the receptacle  4  function may be incorporated into an end of the boom arm and or directly to the main reflector. 
     The adjusting slot  10  is dimensioned with respect to the mounting lip  8  for a close vertical fit and free horizontal movement over a desired range as demonstrated by  FIGS. 2 and 3 . If output(s)  12  of the feed assembly  2  are being routed through a hollow boom arm, the adjusting slot  10  may be formed passing end to end through the receptacle  4 , providing an internal cable path. 
     An adjusting knob  14  with a threaded shaft  16  threads into a corresponding threaded hole  18  formed in a first side  20  of the receptacle  4 . The threaded shaft  16  extends into the adjusting slot  10  into contact with a first side  20  of the mounting lip  8 , setting the horizontal position of the mounting lip  8  and thereby the feed assembly  2  within the adjusting slot  10 . To minimize the opportunity for the threaded shaft  16  to skew as it rotates against the mounting lip  8 , a seating hole  22  may be formed in the mounting lip  8  to receive the distal end of the threaded shaft  16 . A guide pin  24  positioned in a second side  26  of the adjusting slot  10  also fits into a corresponding seating hole  28  on the second side  26  of the mounting lip. A bias spring  30  on the guide pin  24  is compressed between the receptacle  4  and the mounting lip  8 , biasing the receptacle  4  against the threaded shaft  16 . 
     As the adjusting knob  14  is turned to thread the threaded shaft  16  into the threaded hole  18  of the receptacle  4 , the mounting lip  8  is moved against the bias spring  30 . Conversely, as the adjusting knob  14  is turned to thread the threaded shaft  16  out of the receptacle  4 , the bias spring  30  holds the mounting lip  8  against the retracting distal end of the threaded shaft  16 . Thereby, the mounting lip  8  may be positioned horizontally within the receptacle  4  according to the position of the threaded shaft  16 . A further benefit of the bias spring  30  is that the constant bias against the threaded shaft  16  reduces the potential for any threading slop or backlash that may be present between the threading of the threaded shaft  16  and the threaded hole  18 . 
     Angular resolution of azimuth corrections introduced by horizontal feed assembly  2  movements resulting from rotation of the adjusting knob  14  is a function of the selected thread pitch applied to the threaded shaft  16  and corresponding threaded hole  18 . For example, in a typical consumer digital satellite TV reflector antenna embodiment, a thread pitch resulting in a threaded shaft  16  displacement of 2.5 mm every 4 turns equates to an angular resolution of approximately 0.025 degrees for every quarter turn of the adjusting knob  14 . 
     In alternative embodiments the means for positioning the mounting lip within the adjusting slot may be adapted according to a range of different threaded shaft configurations, as shown for example by  FIGS. 5–7  the length of the threaded shaft  16  may be extended to pass across the receptacle  4 , through the mounting lip  8 . The receptacle  4  then acts as a carrier for the threaded shaft  16  now threaded through the mounting lip  8  of the feed assembly  2 . With either end of the threaded shaft  16  passing through unthreaded hole(s) at both sides of the receptacle  4  and held longitudinally captive between the adjusting knob  14  and a stop  33  such as a retaining clip or the like on the distal end of the threaded shaft  16 , respectively, rotation of the threaded shaft  16  via the adjusting knob  14  operates to thread the mounting lip  8  and thereby the feed assembly  2  left or right within the adjusting slot  10 , as shown in  FIGS. 6 and 7 . If desired, a bias spring  30  for example in the form of a coil spring as shown in  FIGS. 2 and 3  or a spring washer, not shown, may be added at either inside or outside end of the receptacle  4  or adjusting slot  10  to reduce the potential for any threading slop or backlash that may be present between the threaded shaft  16  and the threads within the mounting lip  8 . 
     As shown in  FIGS. 8–10 , vernier scale(s)  34  of various types may be applied to the receptacle  4  to provide a ready visual reference of azimuth adjustment progress as the adjustment knob  14  is turned. At least one aperture in the form of a slot  36  or series of scale hole(s)  38  in the receptacle  4  may be used to view scale marking(s)  40  printed upon, etched or cast into the mounting lip  8 . Alternatively, the vernier scale(s)  34  may be applied along a top edge of the receptacle  4 , proximate corresponding scale marking(s)  40  on the feed assembly  2  above the mounting lip  8 , reducing the number of required receptacle  4  machining steps. 
     Although the adjusting knob  14  precisely positions the feed assembly  2  within the receptacle  4 , further fastening may be applied to securely hold the feed assembly  2  in the final adjustment position. In the present embodiment(s), retaining fasteners (not shown) may be applied passing through horizontally elongated fastener slot(s)  42  formed in the top of the receptacle  4  either bolting across or threading into the mounting lip  8  of the feed assembly  2 . When a final adjustment of the feed assembly  2  with respect to the receptacle  4  has been completed, the feed assembly  2  may be securely fixed in place by tightening the retaining fastener(s). 
     One skilled in the art will appreciate that the precision orientation adjustments enabled by the present invention significantly reduces the complexity and precision adjustability requirements of the general antenna mount required for a reflector antenna incorporating the invention, resulting in a significant reduction in overall cost. Also, the time required for installation and configuration of the reflector antenna is similarly reduced. 
     It should further be appreciated that, while the embodiments described herein demonstrate a feed assembly arrangement oriented to provide for feed assembly fine azimuth adjustment, the invention may also be applied within the scope of the attached claims with respect to elevation adjustment or a combination thereof via an adaptation of the adjusting slot orientation. 
     
       
         
               
             
               
               
             
           
               
                   
               
               
                 Table of Parts 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 2 
                 feed assembly 
               
               
                 4 
                 receptacle 
               
               
                 6 
                 adjusting collar 
               
               
                 8 
                 mounting lip 
               
               
                 10 
                 adjusting slot 
               
               
                 12 
                 output 
               
               
                 14 
                 adjusting knob 
               
               
                 16 
                 threaded shaft 
               
               
                 18 
                 threaded hole 
               
               
                 20 
                 first side 
               
               
                 22 
                 seating hole 
               
               
                 24 
                 guide pin 
               
               
                 26 
                 second side 
               
               
                 28 
                 seating hole 
               
               
                 30 
                 bias spring 
               
               
                 32 
                 threaded rod 
               
               
                 33 
                 stop 
               
               
                 34 
                 vernier scale 
               
               
                 36 
                 slot 
               
               
                 38 
                 scale hole 
               
               
                 40 
                 scale marking 
               
               
                 42 
                 fastener slot 
               
               
                   
               
             
          
         
       
     
     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. 
     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.