Patent Publication Number: US-6985057-B2

Title: Quick turn-lock waveguide transition assembly

Description:
BACKGROUND OF INVENTION 
     1. Field of the Invention 
     This invention relates to the precision and variable angle attachment between two waveguide components, for example the transition between a feed waveguide or transmitter output and a dual reflector antenna feed assembly. More particularly, the invention relates to a cost effective feed transition assembly with quick tool-less initial mounting and widely variable connection angle alignment features. 
     2. Description of Related Art 
     Microwave antennas commonly have a feed assembly linked to a transmitter or receiver by a waveguide. To minimize signal degradation, the waveguide components are precision formed to create closely aligned and gap free interconnections. An aperture in the waveguide signal path may be aligned to select between vertical and horizontal polarization by alternating the aperture orientation by 90 degrees. In addition to primary orientation for a desired polarization, a fine tuning ability is desirable to enable optimizing the selected polarization. 
     Prior dual reflector microwave antennas have used an aperture slip ring with a plurality of bolt holes, each bolt hole in the form of an arc shaped slot to permit fine adjustment of the selected aperture angle. This configuration has three main disadvantages. First, at least one of the plurality of bolts required to attach the aperture need to be inserted and threaded before the aperture becomes self-supporting. Seemingly simple mechanical operations of this type are made much more difficult when they must be performed in exposed locations such as high atop a radio tower. Second, the assembly is relatively expensive to manufacture, because the plurality of arc shaped bolt slots require complex machining capabilities. Also, the overall number of required separate components is significant, increasing a drop hazard during installation and maintenance. Third, to maintain the strength of the component, the arc shaped bolt holes have a minimal angular adjustment range. To change the angle 90 degrees from vertical to horizontal polarization, or vice versa, the entire assembly must be removed, rotated and again supported while the initial bolt(s) are re-inserted and tightened. 
     Alternatively, a slip ring separate from the aperture has been used, adding additional costs and introducing additional potential failure points to the overall system while maintaining the drawbacks described hereinabove. 
     Competition within the communications component and or systems industry has focused attention on structural integrity, materials and manufacturing operations costs. Also, ease of installation and service is a growing component and or system selection consideration. 
     Therefore, it is an object of the invention to provide an apparatus that overcomes deficiencies in the prior art. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with a general description of the invention given above, and the detailed description of the embodiments given below, serve to explain the principles of the invention. 
         FIG. 1  is an exploded isometric angled top side view of a first embodiment of the invention. 
         FIG. 2  is an isometric angled top side view of  FIG. 1 , with the transition assembly seated against the feed assembly spigot. 
         FIG. 3  is an isometric angled top side view of  FIG. 1 , with the transition assembly seated against the feed assembly spigot and rotated to align the transition assembly with a first polarization groove. 
         FIG. 4  is an isometric angled top side view of  FIG. 1 , with the transition assembly seated against the feed assembly spigot and rotated to align the transition assembly with a second polarization groove. 
         FIG. 5  is a cross sectional schematic side view of the first embodiment of the invention, applied to an antenna base casting with a self supported feed assembly hub. 
     
    
    
     DETAILED DESCRIPTION 
     A first embodiment of the invention is described with reference to  FIGS. 1–5 . A transition assembly  1  with a waveguide  2  there through is adapted to mate with the feed point, also known as the spigot  3 , of an antenna feed assembly  5 . The transition assembly  1  is retained against the spigot  3  at a spigot end  4  by a pair of clamping screw(s)  7  that engage a clamping groove  9  formed in an outer surface  10  of the transition assembly  1 . Cutout(s)  11  formed in the outer surface  10  of the transition assembly  1  extending from the spigot end  4  of the assembly to the clamping groove  9  allow the clamping screw(s)  7  to reach the clamping groove  9  without interference from the transition assembly  1  during an initial seating of the transition assembly  1  against the spigot  3 . Then, rotation of the transition assembly  1  engages an outer edge of each clamping screw head  13  into the clamping groove  9 , retaining the transition assembly  1  against the spigot  3 . 
     An aperture  15  may be formed in the transition assembly  1  to configure the polarization of the antenna feed assembly  5 . Alignment indicia  17 , for example grooves, formed on both the transition assembly  1  and a mating surface of the, for example, antenna base  19  corresponding to a desired angular orientation of the transition assembly  1  with respect to the base  19  provide a quick reference for aligning the aperture  15  via rotation of the transition assembly  1 . The aperture  15  may be machined directly into the transition assembly  1  or configured as a separate component which inserts into and is retained by the transition assembly  1 , allowing the user to select from a range of different apertures  15 , depending upon the specific application at hand. 
     The clamping screw(s)  7  may be provided with a guide surface  21  formed in an area of the base  19  surrounding a portion of each clamping screw head  13 . The guide surface(s)  21  are adapted to a level from the base  19  which corresponds to the clamping groove  9  whereby when the top of each of the clamping screw(s)  7  is flush with the top of the respective guide surface(s)  21  the clamping screw(s)  7  are aligned to engage the clamping groove  9  upon initial seating of the transition assembly  1  onto the spigot  3 . To ensure that the clamping screw(s)  7  securely retain the transition assembly  1  over time, an anti-vibration coating  25  may be added to the clamping screw  7  threads and or contact surfaces of the clamping screw head(s)  13 . Alternatively and or additionally, the anti-vibration coating  25  may be added to the clamping groove  9 . 
     Sealing groove(s)  27  may be added to the spigot  3  and or transition assembly  1  to provide a seat for O-rings  29  or other gaskets used to seal the interconnection between the transition assembly  1  and the spigot  3  and or the transition assembly  1  and further waveguide components or a transmitter/receiver (not shown) connected to the transition assembly  1  via, for example, screws mating with screw holes  31 . 
     In use, the clamping screw(s)  7  are screwed into the base  23  to a level where the clamping screw head(s)  13  are flush with the guide surface(s)  21 . The transition assembly  1  cutout(s)  11  are aligned with the clamping screw(s)  7  and the transition assembly  1  seated onto the spigot  3 . The transition assembly  1  may then be rotated to engage the clamping screw head(s)  13  into the clamping groove  9 . The transition assembly  1  is rotated until the alignment indicia  17  of a desired polarization are aligned. Precision adjustment of the polarization alignment may then be made with the initial alignment as the starting point. When aligned as desired, the clamping screw(s)  7  are tightened to secure the transition assembly  1  to the spigot  3 . 
     When a change of polarization, for example from vertical to horizontal is desired, only the clamping screw(s)  7  need be partially loosened and the transition assembly  1  rotated and aligned as desired proximate the opposite alignment indicia  17 . The waveguide and or other components attached to the transition assembly  1  need not be removed, because unless the transition assembly is fully rotated to an alignment where the cutout(s)  11  are aligned with the clamping screw(s)  7 , the transition assembly  1  is retained upon the spigot  3  by the clamping screw head(s)  13  engagement with the clamping groove  9 . 
     If automated polarization control and or fine tuning is desired, the transition assembly  1  may be configured to be rotatable by having the clamping screws tightened to secure the clamp screw heads in the clamp groove but not to prevent rotation of the transition assembly  1  which may then be rotatably driven by a drive (not shown) anchored, for example by a boss  33  formed in the base  19 . 
     Alternatively, rather than using the clamping screw head(s)  13 , the clamping screw(s)  7  may use tabs, washers, keyed retaining rings or the like as means for engaging the clamping groove  9 . 
     One skilled in the art will appreciate that the present invention may be cost effectively fabricated without requiring advanced machining operations. Manufacturing and installation efficiencies are also increased when one appreciates that minimizing the number of necessary interconnecting screws and or bolts reduces the total number of components. 
     The present invention brings to the art a cost efficient quick turn-lock transition assembly  1  that may be aligned for either vertical or horizontal polarization without removing it from, for example, the feed assembly  5  of an antenna. Further, the present invention provides heretofore unavailable ease of installation and or service characteristics, including the ability to align the transition assembly  1  for either vertical or horizontal polarization without removing it from, for example, the feed assembly  5  of an antenna. 
     
       
         
           
               
             
               
                   
               
               
                 Table of Parts 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                 1 
                 transition assembly 
               
               
                 2 
                 waveguide 
               
               
                 3 
                 spigot 
               
               
                 4 
                 spigot end 
               
               
                 5 
                 antenna feed assembly 
               
               
                 7 
                 clamping screw 
               
               
                 9 
                 clamping groove 
               
               
                 10 
                 outer surface 
               
               
                 11 
                 cutout 
               
               
                 13 
                 clamping screw head 
               
               
                 15 
                 aperture 
               
               
                 17 
                 alignment indicia 
               
               
                 19 
                 base 
               
               
                 21 
                 guide surface 
               
               
                 25 
                 anti-vibration coating 
               
               
                 27 
                 sealing groove 
               
               
                 29 
                 o-ring 
               
               
                 31 
                 screw hole 
               
               
                 33 
                 boss 
               
               
                   
               
            
           
         
       
     
     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.