Abstract:
An adjustable satellite antenna holder has a first base member, a first coarsely adjustable support member pivotable about a first axis with respect to the first base member and a first finely adjustable support member pivotable about an axis parallel to said first axis with respect to the first coarsely adjustable support member.

Description:
FIELD OF THE INVENTION 
   The invention relates to a satellite antenna holder. 
   BACKGROUND OF THE INVENTION 
   Satellite antennas, in particular parabolic antennas popularly referred to as “satellite dishes” have come into widespread use with the advent of satellite-based television. Such satellite dishes are known to require careful alignment in order to achieve a good reception performance. In order to allow for elevation and azimuth alignment of such antennas, in particular of antennas for private household use, simple antenna holders have been designed in which e.g. a ball-and-socket joint ensured to degrees of rotational freedom. In an unlocked state of this joint, the dish was pivoted freehandedly until an appropriate alignment was found, and then the joint was locked in order to fix the dish in this alignment. 
   Forthcoming applications such as interactive television, high speed internet access by satellite etc. will require small and economic satellite antenna designs which enable a user not only to receive a downlink signal from the satellite, but also to transmit data in the uplink direction, towards the satellite. 
   For uplink transmission, the alignment of the satellite antenna with respect to the satellite is much more critical than for downlink. This is because the receiving characteristic of the satellite dish on earth, being very narrow and aimed at the satellite, receives very little noise besides the signal from the satellite, whereas a satellite antenna that must be able to receive uplink signals from numerous satellite dishes at various places on earth is exposed to a much higher level of noise. Therefore, it is expected that for bi-directional applications, earthborn satellite antennas will have to be aligned with an accuracy of approximately 0.1 degrees. This is a level of precision which is not reliably achieved with the conventional satellite dish holders described above. 
   SUMMARY OF THE INVENTION 
   It is therefore desirable to design a simple and economical satellite holder that can be aligned quickly and with a high degree of precision. 
   The invention proposes an adjustable satellite antenna holder comprising a first base member, a first coarsely adjustable support member pivotable about a first axis with respect to the first base member and a first finely adjustable support member pivotable about an axis parallel to said first axis with respect to the first coarsely adjustable support member. 
   When the first base member of the antenna holder is mounted on an appropriate substructure and the satellite antenna is mounted to its first finely adjustable support member, a quick and rough adjustment can simply be done by turning the first coarsely adjustable support member until a downlink signal from a desired satellite is received, and then using the finely adjustable support member for a fine alignment. Whereas the coarsely adjustable support member may simply be a joint rotated by hand, as in the prior art, the finely adjustable support member will preferably comprise an adjusting actuator by which small rotations in the range of 0.1 to 1 degree can be reliably and reproducibly driven. 
   For adjustment in elevation and azimuth directions, a two-stage construction may be used in which the first base member and support members are for adjustment of one rotational degree of freedom, and a second stage comprising a second base member, a second coarsely adjustable support member and a second finely adjustable support member is provided for the second rotational degree of freedom. Here, the first base member is rigidly coupled to the second finely adjustable support member; in particular, they may be formed by a unitary element. 
   The second support member need not be integrated into a single device together with the other members; it may e.g. be a pole or another type of appropriate substructure to which the satellite antenna holder is mounted, a coarse adjustment between the pole and the second coarsely adjustable support member being done at mounting time. 
   The adjusting actuator should preferably be designed so as to lock the support members coupled by it relative to each other when it is not driven. Such an actuator may simply comprise a screw and a nut that can be rotated with respect to each other, a pneumatic or hydraulic piston, a motorized translation stage, etc. 
   According to a first group of preferred embodiments of the invention, the actuator comprises a screw mounted to one of said support members and a nut rotatably mounted to the other support member and engaging the screw. In a first embodiment of this group, the screw is rigidly held at said one support member and the nut is coupled to a cross-bar that engages said other support member and is gradually displaceable therein with respect to the pivoting axis. Alternatively, the screw may be gradually displaceably engaged with said one support member, and the other support member to which the nut is rotatably mounted comprises guiding means for guiding the screw in its longitudinal direction. 
   According to a second preferred embodiment, the actuator is also formed of a screw, and this screw has a circumferential profile, preferably a circumferential groove near the head of the screw, which is rotatably engaged with one of said support members, the threaded portion of the screw engaging a threaded bore of said other support member. The portion of said one support member engaging the groove preferably has a circular cross section, so that it can freely tilt within the groove when the support members are pivoted with respect to each other. 
   Additionally, the screw should be equipped with a locking nut for locking the screw once a properly aligned position has been found. 
   According to another embodiment, the actuator comprises two screws mounted in threaded bores of one of said support member in such a way that the tips of these screws face each other, and a trunnion of said other support member extending between the tips. When the tips of the two screws are far apart from each other, the two support members may be freely rotated with respect to each other by hand, until the trunnion hits one of the two tips. A fine adjustment can be carried out by reducing the space between the tips to a minimum and rotating both screws and synchronism, so that one tip pushes the trunnion while simultaneously, the other tips recedes. This type of actuator is particularly suitable for azimuth adjustment. 
   In order to readily achieve the desired accuracy of adjustment, one should preferably choose the pitch of the screw(s) such that one turn of the screw(s) corresponds to a rotation of the finely adjustable support member of less than 0.5°. In order to make the adjustment procedure not more tedious than necessary, the rotation of the finely adjustable support member per turn of the screw should be at least 0.1°. 
   There should preferably be means for fixing the base and support members with respect to each other after adjustment. In particular, if there are two degrees of rotational freedom to be adjusted, it is important to fix one before adjusting the other. Of course, when fixing the base and support members to each other, care must be taken not to induce a movement that would destroy the adjustment. For this purpose, a very advantageous locking means is an eccentric mounted on a shaft defining the axis of rotation, the eccentric being pivotable between a locking position in which it urges said members into a frictional engagement and an unlocking position in which said frictional engagement is released. Since the eccentric is mounted close to the axis of rotation, any torque it might exercise when locking is very small. In particular, if the eccentric comes into contact with one of said members of both sides of the shaft, frictional forces exercised on these two sides tend to compensate each other. 
   As an additional locking means, a base member may be provided with a circular slot centred around its axis of rotation, and the coarsely adjustable support member that is pivotable around this axis of rotation has a threaded portion extending through the slot which may be fixed to the slot using a nut. This type of fixing means is particularly appropriate for fixing when a coarse adjustment for one degree of freedom has been carried out and before the fine adjustment is begun. A slight pivoting movement of the coarsely adjustable support member which may be caused by fixing the screws may afterwards be compensated during fine adjustment. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further objects, features and advantages of the invention will become apparent from the subsequent description of preferred embodiments given with respect to the appended drawings. 
       FIG. 1  is a perspective view of a satellite antenna holder according to a first embodiment of the invention having azimuth and elevation adjusting mechanisms; 
       FIG. 2  shows part of the same holder under a different angle and especially the fine elevation adjusting mechanism; 
       FIG. 3  shows a cross section of the azimuth fine adjusting mechanism of the holder of  FIG. 1 ; 
       FIG. 4  shows a first modified embodiment of the elevation adjusting mechanism; 
       FIG. 5  shows a second modified embodiment of the elevation adjusting mechanism; 
       FIG. 6  shows a first modified embodiment of the azimuth adjusting mechanism; 
       FIG. 7  shows a second modified embodiment of the azimuth adjusting mechanism; and 
       FIG. 8  shows locking means for the azimuth adjusting mechanism. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   The holder shown in  FIG. 1  comprises a first finely adjustable support member  1  which is approximately in the shape of the letter L. It has an approximately vertical branch  10  and an approximately horizontal branch  11 . A slot  12  extends through all of branch  10  and most of branch  11 . A cylindrical rod  13  extends through a bore which is formed at the angle between branches  10 ,  11  of first finely adjustable support member  1  and is held in a first base member  3 . 
   A first roughly adjustable support member  2  is also rotatably mounted to the rod  13 . The roughly adjustable support member  2  is formed of a rod  20  of rectangular cross section bearing two crossbars  21  and  22 . As is best seen in  FIG. 2 , the crossbar  21  has two upturned end portions  23  in which holes are formed through which the cylindrical rod  13  rotatably extends. 
   It should be noted that in  FIG. 2  only a left hand portion of the first finely adjustable support member  1  is shown, the portion to the right of slot  12  is not represented in order to allow a view of adjusting means  26  to  29  that will be explained in detail below. 
   The other crossbar  22  has threaded end portions  24  that extend through slots  30  formed in vertical side wings  31  of first base member  3  and may be fixed to the base member  3  in a given position by means of nuts  25 . The slots  30  are in the shape of circle sectors that extend concentrically around the cylindrical rod  13 . 
   A threaded bolt  26  extends perpendicularly from the surface of the rod  20  into the slot  12  of branch  11 . It extends through a bore (not shown) of rod  20  and is fixed to the rod  20  by means of locking nuts at the upper and lower sides of rod  20 , only the upper one of which is shown in the FIG. The threaded bolt  26  bears a knurled nut  27  held in a cage  28 . The cage  28  has openings through which the nut  27  can be rotated by a user&#39;s fingers, whereby the cage  28  is displaced up and down along the threaded bolt  26 . The cage  28  has two laterally extending arms  29  that engage slits  14  symmetrically formed in the left-hand and right-hand portions of branch  11  of first finely adjustable support member  1 . 
   The members  1 ,  2 ,  3  form an elevation adjusting mechanism of the antenna holder. Adjustment is carried out by first roughly setting the orientation of roughly adjustable support member  2  with respect to base member  3 . This can be done by tilting member  2  by hand until a weak satellite signal is received by an antenna mounted on branch  10 , or by setting the angle between base member  3  and roughly adjustable support member  2  to a predefined value, for example by inserting a template between the rod  20  and a base plate  32  of support member  3 , adapting the angle between the two to the template and fixing the roughly adjustable support member  2  using the nuts  25 . 
   A fine adjustment is then carried out by setting the position of finely adjustable support member  1  with respect to roughly adjustable support member  2  by rotating the nut  27  until optimal receiving conditions are achieved. The pitch of threaded bolt  26  is set such that the bolt  26  is self-locking, i.e. that pressure exercised on the support members will not cause the bolt  26  to rotate. Specifically, the pitch should be such that one turn of the nut  27  corresponds to a rotation of the finely adjustable support member  1  of approximately 0.1° to 0.5° if a beam opening angle of 0.1° is assumed for the satellite at which the antenna is directed. 
   The base plate  32  forms a second finely adjustable support member for an azimuth adjusting mechanism. This mechanism further comprises a pole  5  forming a second base member and a pole adaptor  4  forming a second roughly adjustable support member. The pole  5  is cylindrical in cross section, and the pole adaptor  4  has a mounting socket which is not shown in detail in  FIG. 1 , in which an end portion of the pole  5  may be inserted and fixed by pressing the pole  5  in an arbitrary azimuth orientation. 
   The base member  3  is rotatable with respect to the pole adaptor  4  around a bolt  40 . This bolt  40  extends through two plate members  41 ,  42  of pole adaptor  4  and, between these two, through a bar  33  which is part of base member  3 . At one end of the bolt  40 , there is a nut  43  in contact with the lower one  41  of the two plate members, at the other there is an eccentric lever  44 . In the position shown in  FIG. 1 , the lever  44  is in a downturned, locked position in which it holds the plate members  41 , 42  pressed against the bar  33 , so that no azimuth rotation of the base member  3  with respect to the pole adaptor  4  is possible. In an unlocked, upturned position of lever  44 , the plate members  41 ,  42  and the bar  33  come apart and can be rotated. Since this locking mechanism is located at the axis of azimuth rotation of the antenna holder, any force exercised on the locking lever  44  cannot generate a torque in the azimuth direction. Moreover, since the bar  33  is sandwiched between the plate members  41 , 42 , the base member can not be rotated by frictional forces that may occur when the lever  44  is rotated between its locked and unlocked positions. In this way, when an adjustment of the azimuth orientation of the antenna has been carried out, it will not be destroyed by locking the lever  44 . 
   A mechanism for finely adjusting the azimuth orientation of the antenna is concealed inside the holder. In  FIG. 1 , only part of a threaded bolt  45  for driving this adjusting mechanism can be seen. The mechanism as such will therefore be described referring to FIG.  3 . This FIG. is a partial horizontal section through the holder of  FIG. 1  at the level of bar  33 . This bar  33  has a projection  34  extending backwards into the holder. At an end portion of the projection  34 , a slightly elongated hole  35  is formed. The end portion extends into a box  46  rigidly coupled to the end of threaded bolt  45 . A pin  47  firmly held in walls of the box  46  extends through the hole  35 . The threaded bolt  45  extends though an opening in a side wall  36  of base member  3 . A compression spring  415  extending around threaded bolt  45  urges the box  46  away from the side wall  36 , so that a nut  48  held by the threaded bolt  45  is always firmly pressed against the outside of wall  36 . By turning the nut  48 , the bar  33  may be turned in either direction around the axis defined by bolt  40 , whereby a fine adjustment of the azimuth angle of the antenna is achieved. 
   Once a satisfying adjustment of the azimuth angle has been found, it may be fixed using a locking nut  49 . 
   Here, again, the pitch of bolt  45  is chosen such that one turn of nut  48  amounts to a rotation of between 0.1° and 0.5°. The total adjusting range of the azimuth fine adjusting mechanism may amount to approximately 2°. 
   Some modified embodiments of elevation and azimuth adjusting mechanisms for antenna holders according to the present invention will be discussed referring to the remaining FIGS. Unless otherwise stated, any elevation adjusting mechanism can be combined with any azimuth adjusting mechanism and vice versa. Elements of these embodiments that correspond to elements already described above have the same reference numerals and are not described in detail again. 
     FIG. 4  is a detail of a modified elevation adjusting mechanism. The first roughly adjustable support member  2  is identical with that of  FIG. 1  except for the way in which the threaded bolt  26  is mounted to the rod  20 . Just as in the case of  FIG. 1 , the bolt extends through a bore of rod  20 , which, this time, is shown in the FIG. and has the reference numeral  219 . Here, the rod  20  has two claws  211  by which an adjusting nut  212  is held at the upper side of rod  20  at the end of bore  219 . The adjusting nut  212  has a knurled wide diameter portion  213  that extends beyond the sides of rod  20  and can easily be held and rotated by the fingers of a user. By rotating the adjusting nut  212 , the threaded bolt  26  is displaced axially. 
   At the upper end of threaded bolt  26 , a fork  214  is formed having two fingers that extend along the lateral flanks of branch  11  and bear a bolt  215  which extends through a short slit  14  formed in branch  11 . 
   At a lower end of threaded bolt  26 , a locking nut  217  is shown. When the elevation of the antenna has been adjusted by turning adjusting nut  212 , it can be fixed by turning the locking nut  217  so that the rod  20  is squeezed between the two nuts  212 ,  217 . In order to prevent a rotation of adjusting nut  212  while doing so, the adjusting nut has a hexagonal portion  218  that may be held by a wrench. 
   In this embodiment, the slot  12  of  FIG. 1  is not required. 
   In the embodiments of FIG.  1  and  FIG. 4 , there is a slit  14  formed in branch  11  of first finely adjustable support member  1 . This slit  14  is required because, in case of  FIG. 1 , the cage  28  and in case of  FIG. 4 , the threaded bolt  26  itself is only linearly displaceable, and the radius where the arms  29  or bolt  215  engage the branch  11  may vary according to the angular orientation of the first finely adjustable support member  1 . This slit  14  might be replaced by a circular hole exactly fitting the arms  29  or the bolt  215 , respectively if the threaded bolt  26  were pivotably mounted at the rod  20 . 
   Another modified embodiment where no such slit or elongated hole is necessary is shown in FIG.  5 . In this embodiment the rod  20  has a threaded bore in which the threaded bolt  26  is engaged and can be adjusted by turning around its axis. A locking nut  217  engaging threaded bolt  26  is provided at one side of rod  20 , in this case at the upper side. The threaded bolt  26  has a cylindrical head portion  220  the top of which is shaped for engagement with a screwdriver. A cylindrical rod  15  held by branch  11  engages a circumferential groove  221  of this head portion. In the embodiment shown, the branch  11  has a slot  12  as shown in  FIG. 1 , and the rod  15  extends across this slot  12 . The depth of the groove  221  is set such that while threaded bolt  26  engages the bore of rod  20 , the rod  15  will never come out of the groove  221 . Elevation fine tuning is done by firstly turning threaded bolt  26  using a screwdriver until a satisfying elevation value is found, and then fixing the threaded bolt  26  using the locking nut  217 . 
   Alternatively, there might be no thread for engagement with threaded bolt  26  in the bore of adjustable member  2 . In that case the threaded bolt  26  might be held using two locking nuts  212 ,  217 , just as shown in FIG.  4 . 
     FIG. 6  is a horizontal cross section taken along the same plane as in  FIG. 3 , illustrating a first modified embodiment of the azimuth adjusting mechanism. In this embodiment, there are threaded bores formed in opposing side walls  36  of base member  3 . Two threaded bolts  45  extend through these bores. The bolts  45  have plate-shaped inward end portions facing each other. The projection  34  has a circular end portion  37  which is located in a space between the inward ends of the two bolts  45 . The outward end of each bolt is provided with a hexagonal socket head for receiving an Allen wrench or with an equivalent structure for engaging with another type of screwdriver. 
   In the configuration shown in  FIG. 6 , there is a clearance between the circular end portion  37  and the plate-shaped end portion of one of the threaded bolts  45 . In this configuration, the base member  3  is freely rotatable with respect to the pole adaptor  4  by an angle defined by said clearance. Accordingly, this embodiment allows for a first coarse azimuth adjustment when mounting the adaptor  4  on the pole  5 , and a second coarse adjustment by rotating the base member  3  over the angle defined by said clearance. 
   For a fine adjustment, the clearance is set to zero. Then the azimuth position of the antenna is adjusted by rotating both threaded bolts  45  to the same extent and in the same direction. When the correct azimuth position has been found, the mechanism is locked by rotating the bolts  45  in opposite directions, so that the circular end portion  37  is squeezed between then. Additionally, locking nuts  49  may be placed at the outward ends of the two bolts  45 . 
   In the embodiment of  FIG. 7 , the two threaded bolts  45  are replaced by a single cylindrical shaft  410  extending through both bores in the opposing side walls  36 . Only one of these bores must have a thread that engages threaded first narrow portion  410  of shaft  411 . A second narrow portion  412  of shaft  410  may be with or without thread. In a thick portion  413  of shaft  410  between the two narrow portions  411 ,  412 , a circumferential groove  414  is formed. The width of this groove  414  is selected such that it will receive the circular end portion  37  of projection  34  without a clearance in the axial direction of the shaft  410 . 
   This embodiment may be regarded as a variation of that of  FIG. 6 , in which the two threaded bolts  45  are combined into a single shaft, so that for carrying out the fine adjustment, it is no longer necessary to move the two bolts  45  separately. 
   For locking the elevation adjustment of the antenna holder, an elevation position locking mechanism may be provided which is similar to the azimuth locking mechanism described above referring to FIG.  1 . This elevation position locking mechanism is illustrated in FIG.  8 . It comprises a locking nut  16  mounted at one end of rod  13  and an eccentric lever  17  similar to lever  44  of  FIG. 1 , which is mounted at the other end of rod  13  and is rotatable around an axis which is perpendicular to that of the rod  13 . The rod  13  extends through vertical wings  38  of base member, through the upturned end portions  23  of crossbar  21  of the first roughly adjustable support member  2  and through the region joining branches  10 ,  11  of the first finely adjustable support member  1 . 
   In the position shown in  FIG. 8 , the eccentric lever  17  and the locking nut  16  presses from outside against the vertical wings  38  and urges these into contact with the end portions  23 . The end portions  23 , in turn, are pressed against the first finely adjustable support member  1 . In this way, all three elements  1 ,  2 ,  3  of the holder are in frictional engagement and cannot turn with respect to one another. When the lever  17  is raised, the vertical wings  38  and end portions  23  relax and come apart from each other, so that they can turn around rod  13  again. 
   Since the lever  17  and the blocking nut  16  only come into direct contact with the base member  3 , the support members  1 ,  2  are not subject to any torque when the lever  17  is closed, so that an elevation adjustment carried out with the lever  17  open will not be accidentally destroyed when the lever  17  is closed. Accordingly, the holder can be easily and straightforwardly adjusted to a particular satellite by e.g. first performing a coarse adjustment of elevation and azimuth angles, so that a signal from the satellite is clearly detectable. Second, a fine adjustment of the azimuth angle is carried out, the azimuth adjustment mechanism is locked using lever  44 , the elevation angle is finely adjusted, and finally the elevation adjusting mechanism is locked using lever  17 .