Patent Publication Number: US-11387540-B2

Title: Antenna steering and locking apparatus

Description:
PRIORITY 
     The present application is related to, and claims the priority benefit of, and is a 35 U.S.C. 371 national stage application of, International Patent Application Serial No. PCT/EP2018/083707, filed Dec. 5, 2018, which is related to, and claims the priority benefit of Great Britain Patent Application Serial No. 1720251.6, filed Dec. 5, 2017. The contents of each of the aforementioned applications are hereby incorporated by reference in their entireties into this disclosure. 
     TECHNICAL FIELD 
     The present invention is concerned with an antenna steering and locking apparatus. More specifically, the present invention is concerned with an antenna steering and locking apparatus for a cellular antenna which facilitates manual and automatic azimuth adjustment. 
     BACKGROUND 
     It is well known to mount cellular antennas in the art. The applicant&#39;s previous application published as WO 2013/171291 describe several configurations of antenna mount. Such antenna mounts preferably have the ability to steer the antenna about a vertical axis—i.e. to adjust the azimuth of the antenna. 
     The present application is particularly concerned with antennas for use with cellular communication. Such antennas are typically directional, and usually elongate in form, mounted vertically. The antennas are also heavy-weighing several tens of kilograms. The ability to steer the antenna and thereby adjust its azimuth is very important to provide optimal network coverage to the users. Further, it is important that azimuth steering is carried out accurately and that the antenna remains in the desired position when set. 
     Although many antennas are manually adjusted by technicians, remote-controlled, automated cellular antennas are becoming more common, and the present invention is relevant to both types as will be described below. 
     Weight and wind load are widely acknowledged factors to consider when designing and operating a cellular communications antenna. Weight is a constant and predictable load on an antenna mast, but wind loading is dynamic and often unpredictable. All weight and wind loads need to be reacted by the structure supporting the antenna-specifically a mast or tower. 
     Excessive weight and wind load can cause performance problems, specifically when antennas move under their own weight or the force of the wind. There is also a safety concern—overloaded or high wind-resistant configurations may present a danger to service personnel, as such configurations may move without warning. 
     Problems with weight and wind loading become more serious when more antennas are fitted to existing installations. Due to the demand on cellular networks, this is becoming increasingly common. As capacity needs to be increased, and new technologies evolve, the tendency is for more antennas to be installed on a single mast. 
     Current installation techniques exacerbate the weight and wind loading problems. 
     It is an aim of the present invention to provide an improved antenna steering and locking apparatus. 
     BRIEF SUMMARY 
     According to a first aspect of the invention there is provided a cellular antenna steering and locking apparatus comprising:
         a first bracket for attachment to a fixed structure;   a second bracket for attachment to a cellular antenna;   a joint arrangement between the first and second brackets to facilitate rotation therebetween about a pivot axis; and,   a locking mechanism having a first condition in which rotation between the first and second brackets is prohibited, and a second condition in which rotation between the first and second brackets is permitted, the locking mechanism having a toothed ratchet and a ratchet-engaging member, the ratchet-engaging member being selectively engageable with the teeth of the ratchet to lock the joint arrangement against rotation in at least one rotational direction.       

     Advantageously, the use of a toothed ratchet provides a high degree of adjustability and precision. Preferably the ratchet has at least 20 teeth. The ratchet and ratchet-engaging member have a plurality of positions in which they are engaged together. Preferably those positions are N in number where 360/N=A where A is an integer angle between positions. For example, if the ratchet has N=20 positions, it will have 20 teeth each A=18 degrees apart. In another embodiment, the apparatus may have N=72 positions which are A=5 degrees apart. In another embodiment the apparatus may have N=180 positions which are A=2 degrees apart. The values of N or A can be chosen to suit the degree of accuracy required, although as mentioned it is preferred that N and A are integer values. 
     Preferably:
         the first ratchet-engaging member is configured to lock the joint arrangement at a first set of predetermined angular positions of the joint arrangement; and,   the locking mechanism comprises a second ratchet-engaging member, in which the second ratchet-engaging member has a locked condition in which it is engaged with the teeth of the first ratchet to lock the joint arrangement against rotation in at least the first rotational direction, and in which the second ratchet-engaging member is configured to lock the joint arrangement at a second set of predetermined angular positions interleaving the first set of predetermined angular positions.       

     This allows the system to have a finer resolution than would otherwise be permitted by the number of teeth on the ratchet. For example with teeth 10 degrees apart, a 5 degree offset (or “phase offset”) of the second ratchet-engaging member compared to the first would allow a 5 degree resolution. 
     This may be facilitated by having the second ratchet-engaging member offset relative to the first. Specifically, the second ratchet-engaging member can be positioned at a rotational position of A1/2 degrees about the pivot axis compared to the first ratchet-engaging member, where A1 is the angular tooth spacing of the ratchet. 
     Alternatively, the second ratchet-engaging member can be shaped differently to the first so as to provide locking at the second set of predetermined angular positions. This allows the first and second ratchet-engaging members to be pivotable about a common axis, offset from the pivot axis. 
     Preferably the locking mechanism comprises a first opposed ratchet-engaging member, the first opposed ratchet-engaging member having a locked condition in which it is engaged with either the teeth of the first ratchet or teeth of a second ratchet to lock the joint arrangement against rotation in at least a second rotational direction, opposite to the first rotational direction. 
     Preferably the first ratchet-engaging member and the first ratchet are configured to permit rotational movement in the second direction in the locked condition. 
     Preferably the first opposed ratchet-engaging member and the first or second ratchet are configured to permit rotational movement in the locked direction. 
     This allows e.g. the first ratchet-engaging member to be rotated in the first direction, keeping the opposed ratchet-engaging member engaged. This is advantageous as it limits e.g. back-driving by gusts of wind, which may damage the antenna or the actuation mechanism and/or motor which drives the antenna. 
     The first ratchet may comprise a first set of teeth for engagement with the first ratchet-engaging member, and a second set of teeth for engagement with the first opposed ratchet-engaging member. The first and second sets of teeth may span a portion of the circumference of the ratchet, and may be symmetrical. 
     The first and second sets of teeth may be raked in opposite rotational directions. 
     Preferably the ratchet engaging member is manually moveable between the first and second conditions. 
     Preferably the ratchet engaging member is moveable between the first and second conditions by an actuator. 
     Preferably the ratchet engaging member is configured to engage a plurality of the teeth of the ratchet in the first condition. 
     Preferably the ratchet engaging member is resiliently biased into the first condition. 
     Preferably the ratchet engaging member is a pawl, the pawl being pivotable between the first and second conditions. 
     Preferably the pawl is biased into the first condition by a spring. 
     Preferably there is provided a further pawl being pivotable between the first and second conditions. 
     Preferably the pawl and the further pawl move towards each other when moving from the second to the first condition. 
     Preferably an actuation member is positioned between the pawls and configured to selectively urge the pawls apart to move from the first to the second condition. 
     Preferably the actuation member comprises a cam. 
     Preferably the ratchet engaging member is linearly moveable between the first and second conditions. 
     Preferably the ratchet engaging member is moveable in a radial direction relative to the ratchet. 
     Preferably the ratchet engaging member comprises at least one elastically deformable member being elastically deformable between the first and second condition. 
     Preferably the ratchet engaging member comprises a plurality of elastically deformable members 
     Preferably the deformable members surround the ratchet. 
     Preferably there is a collar surrounding the deformable members, in which axial movement of the collar deforms the members into the first condition. 
     Preferably at least one of the deformable members and the collar comprises a tapered surface to effect the deformation. 
     Preferably there is an elongate central mounting structure having a main axis being vertical in use, and a first pair of cellular antenna steering and locking apparatuses according to any preceding claim being spaced along the axis and located so as to receive a first antenna thereon. 
     Preferably there is at least one further pair of cellular antenna steering and locking apparatuses according to the first aspect, being spaced along the axis and located so as to receive a second antenna thereon. 
     The invention also provides a method of steering and locking a cellular antenna comprising the steps of:
         providing a steering and locking apparatus according to any preceding claim;   providing an antenna attached to the steering and locking apparatus;   moving the steering and locking apparatus to the second condition;   rotating the antenna; and,   moving the steering and locking apparatus into the first condition to thereby lock the position of the antenna.       

     The invention also provides a cellular antenna locking mechanism having a first toothed ratchet and a first ratchet-engaging member, the first ratchet-engaging member having a locked condition in which it is engaged with the teeth of the first ratchet to lock a rotational joint arrangement against rotation in at least a first rotational direction. The locking mechanism may have any of the aforementioned features or combinations of features described herein. 
     According to a further aspect of the invention, there is provided a cellular antenna mounting system comprising:
         a mast comprising a load-bearing mast member, the load bearing mast member forming an integral part of the mast;   a clamp comprising a first clamp member and a second clamp member;   a steering unit comprising a rotational joint; and,   a cellular antenna;   wherein:   the load-bearing mast member is clamped between the first clamp member and the second clamp member to hold the clamp in position relative to the mast;   the steering unit is mounted to the first clamp member; and,   the antenna is attached to the steering unit such that the antenna is moveable about the rotational joint relative to the mast.       

     Preferably the system is used with a steering and locking unit according to the first aspect. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       An example antenna mounting, steering and locking apparatus will now be described with reference to the accompanying drawings in which: 
         FIG. 1  is a perspective view of an antenna mounted to a pole using two first antenna steering and locking apparatuses according to the present invention; 
         FIG. 2  is a first perspective view of an antenna steering and locking apparatus of  FIG. 1 ; 
         FIG. 3  is a second perspective view of the antenna steering and locking apparatus of  FIG. 2 ; 
         FIG. 4  is a section view of the antenna steering and locking apparatus of  FIG. 2 ; 
         FIG. 5  is an exploded view of the antenna steering and locking apparatus of  FIG. 2 ; 
         FIG. 6  is a section view of the antenna steering and locking apparatus of  FIG. 2 , along line A-A in  FIG. 4 , in a first mode of operation; 
         FIG. 7  is a section view of the antenna steering and locking apparatus of  FIG. 2 , along line A-A in  FIG. 4 , in a second mode of operation; 
         FIG. 8  is a perspective view of an antenna mounted to a pole using two second antenna steering and locking apparatuses according to the present invention; 
         FIG. 9  is a plan view of the antenna of  FIG. 8 ; 
         FIG. 10  is a first perspective view of an antenna steering and locking apparatus of  FIG. 8 ; 
         FIG. 11  is a second perspective view of the antenna steering and locking apparatus of  FIG. 10 ; 
         FIG. 12  is a section view of the antenna steering and locking apparatus of  FIG. 10 ; 
         FIG. 13  is an exploded view of the antenna steering and locking apparatus of  FIG. 10 ; 
         FIG. 14  is a section view of the antenna steering and locking apparatus of  FIG. 10 , along line A-A in  FIG. 12 , in a first mode of operation; 
         FIG. 15  is a section view of the antenna steering and locking apparatus of  FIG. 10 , along line A-A in  FIG. 12 , in a second mode of operation; 
         FIG. 16  is a perspective view of a subassembly of a third antenna steering and locking apparatus according to the invention; 
         FIG. 17  is a plan view of the subassembly of  FIG. 16  in a first mode of operation; 
         FIG. 18  is a plan view of the subassembly of  FIG. 16  in a second mode of operation; 
         FIG. 19  is a section view of a subassembly of a fourth antenna steering and locking apparatus according to the invention; 
         FIG. 20  is an exploded view of the subassembly of  FIG. 19 ; 
         FIG. 21  is a perspective view of a fifth antenna steering and locking apparatus according to the invention; 
         FIGS. 22 and 23  are views of the antenna steering and locking apparatus of  FIG. 21  with various components removed; 
         FIG. 24  is a detail view of a part of the antenna steering and locking apparatus of  FIG. 21 ; 
         FIG. 25  is an end view of a part of the antenna steering and locking apparatus of  FIG. 21 ; 
         FIG. 26  is a perspective view of a sixth antenna steering and locking apparatus according to the invention; 
         FIGS. 27 and 28  are views of the antenna steering and locking apparatus of  FIG. 26  with various components removed; 
         FIG. 29  is an end view of a part of the antenna steering and locking apparatus of  FIG. 26 ; 
         FIG. 30  is a detailed view of a portion of  FIG. 29 ; 
         FIG. 31  is a view of a subset of component of the steering and locking apparatus of  FIG. 26 ; 
         FIG. 32  is a perspective view of a cellular antenna attached to a mast using two of a first mounting assembly according to the present invention; 
         FIG. 33  is an exploded perspective view of a first mounting clamp of the first mounting assembly of  FIG. 32 ; 
         FIG. 34  is a plan view of the mounting clamp of  FIG. 33 ; 
         FIG. 35  is a perspective view of the mounting clamp of  FIG. 33  in an installed condition; 
         FIG. 36  is a perspective view of two cellular antennas to a mast using the mounting clamp of  FIG. 32  and a steering unit; 
         FIG. 37  is a plan view of an alternative configuration of the two cellular antennas of  FIG. 36 ; 
         FIG. 38  is a perspective view of a cellular antenna attached to a mast using two of a second mounting assembly according to the present invention; 
         FIG. 39  is a detail, exploded view of a part of  FIG. 38 ; 
         FIG. 40  is a detail, exploded view of a part of a mounting assembly of  FIG. 38 ; 
         FIG. 41  is a detail view of a part of the mast and mounting assembly of  FIG. 38 ; 
         FIG. 42  is a perspective view of a cellular antenna attached to a mast using two of a third mounting assembly according to the present invention; 
         FIG. 43  is a detail view of a part of the mast and mounting assembly of  FIG. 42 ; 
         FIG. 44  is a perspective view of a cellular antenna attached to a mast using two of a fourth mounting assembly according to the present invention; and, 
         FIG. 45  is a detail view of a part of the mast and mounting assembly of  FIG. 44 . 
     
    
    
     DETAILED DESCRIPTION 
     The First Embodiment 
     Structure 
     In the following description, words such as “vertical” and “horizontal” are used to refer to the subject feature in-use. “Longitudinal” generally refers to a direction parallel to the long axis of an elongate object, and “transverse” to directions normal to the longitudinal direction. 
     Referring to  FIG. 1 , there is provided a cellular antenna  10  being elongate in form having a first end  12 , a second end  14 , a flat back face  16  and a curved front face  18 . Constructional details of the antenna  10  will not be discussed further here, suffice to say that the antenna is a direction antenna configured to send and receive signals as part of a mobile phone network. 
       FIG. 1  also shows a vertical pole  20 , which is statically mounted to e.g. a building. The pole  20  is merely an example, and may be any other appropriate structure for mounting an antenna to (e.g. a mast). The exact position of the pole  20  is known by the operator. 
     A first pole clamp  22  and a second pole clamp  24  are also provided, being spaced apart in the longitudinal direction of the pole  20 . Each pole clap  22 ,  24  is immovably (but adjustably and removably) attached to the pole  20 . Each clamp presents a respective mounting face  26 ,  28  which is generally vertical and extending in a transverse direction relative to the pole  20 . 
     A first antenna steering and locking apparatus  100 , and a second antenna steering and locking apparatus  102  are provided between the respective clamps  22 ,  24  and the antenna  10 . The steering and locking apparatuses  100 ,  102  are identical to each other, and as such only the apparatus  100  will be described in detail here. 
     Referring to  FIGS. 2 to 7 , the apparatus  100  is shown in detail. Referring specifically to  FIG. 5 , the apparatus  100  comprises:
         A locking mechanism subassembly  104 ;   A first mounting subassembly  106 ;   A bearing subassembly  108 ; and,   A second mounting subassembly  110 .
 
Locking Mechanism Subassembly  104 
       

     The locking mechanism subassembly  104  comprises a locking mechanism housing  112 , a control  114 , two pawls  116   a, b , two pawl springs  118   a, b , a ratchet  120 , a shaft bolt  122 , a shaft nut  124 , a locking mechanism housing cover  126 , two locking mechanism housing screws  128   a, b  and two locking mechanism attachment screws  129   a, b.    
     The locking mechanism housing  112  comprises a generally planar portion  130  ( FIG. 4 ) defining a locking mechanism recess  132  on one face thereof. The locking mechanism recess  132  has a first portion  132   a  and a second portion  132   b , each of which are circular, forming a “figure of eight” shape in plan ( FIG. 6 ). A housing attachment leg  134  projects normal to the planar portion. As shown in  FIG. 4 , the locking mechanism housing  112  is generally “L” shaped in section. 
     The control  114  is generally cylindrical having an arm  136  projecting therefrom at a first end, and a cam in the shape of a prismatic, polygonal section  138  at a second end. The polygonal section  138  is in the shape of a regular octagon in section ( FIG. 6 ). 
     The pawls  116   a, b  are generally crescent-shaped in section ( FIGS. 6 and 7 ). The pawls  116   a, b  are identical (although mirror-images of each other). As such only the pawl  116   a  will be described with reference to  FIG. 7 . The pawl  116   a  comprises a first end  140  which is has a rounded, smooth surface and a second end  142  defining a ratchet-engaging formation  144  in the form of two teeth defining a groove therebetween. 
     The pawl springs  118   a ,  118   b  are simple compression springs. 
     The ratchet  120  has a cylindrical portion  146  defining a set of ratchet teeth  148  on a radially outwardly facing surface thereof ( FIG. 7 ). A first locking mechanism shaft  150  projects from a first side of the cylindrical portion  146 . The first locking mechanism shaft  150  is hollow, having an open end and defining a radial bore  152  through the walls thereof ( FIG. 4 ). A second locking mechanism shaft  154  extends opposite the first locking mechanism shaft  150 . 
     The locking mechanism housing cover  126  is shaped to fit into, and seal, the locking mechanism recess  132  as shown in  FIG. 4 . It defines a shaft opening  156  therethrough. 
     First Mounting Subassembly  106   
     The first mounting subassembly  106  comprises a bracket  158 , a bearing cover plate  160 , four bearing cover plate screws  162   a, b, c, d  and two first mounting subassembly attachment bolts  164   a, b.    
     The bracket  158  is a generally prismatic block of material having a bearing housing portion  166  and an attachment flange  168 . The bearing housing portion  166  defines an internal cylindrical bearing cavity  170  ( FIG. 4 ) having a first opening  172  in a first side of the housing portion  166  and a second opening  174  in a second side of the housing portion  166 . The second opening  174  is stepped defining a shoulder  176 . 
     The bearing cover plate  160  is flat, planar and circular defining a central shaft aperture  178 . 
     Bearing Subassembly  108   
     The bearing subassembly  108  comprises a first roller bearing  180 , a second roller bearing  182 , a circlip  184 , a pivot pin  186  and a seal  188 . 
     The first and second roller bearings  180 ,  182  are off-the-shelf components and as known in the art comprise an inner race, an outer race and a plurality of rolling elements disposed in an annular arrangement therebetween to facilitate relative rotational movement of the races. As such, the bearings  180 ,  182  require no further description. 
     The pivot pin  186  comprises a shaft  190  having a radial bore  192  at a first end, and a cylindrical flange  194  at a second end. A threaded bore  196  is defined at the flange end ( FIG. 4 ). 
     Second Mounting Subassembly  110   
     The second mounting subassembly  110  comprises a bracket  198 , two bracket mounting bolts  200   a, b , four bracket attachment bolts  202   a, b, c, d  and a pivot bolt  204 . 
     The bracket  198  is constructed from plate metal, and is L-shaped when viewed from the side. The bracket  198  comprises a mounting flange  206  and an attachment flange  208  which are normal to each other. 
     Assembly 
     The first antenna steering and locking apparatus  100  is assembled as follows, with reference to  FIGS. 4 and 5 . 
     The locking mechanism ratchet  120  is mounted for rotation within the locking mechanism housing  112 . The second locking mechanism shaft  154  engages a corresponding bore through the locking mechanism housing to form a plain bearing about a pivot axis X. The cylindrical portion  146  of the ratchet sits within the first portion  132   a  of the locking mechanism recess  132  ( FIG. 6 ). 
     The control  114  is also mounted for rotation about a control axis Y within the locking mechanism housing  112 , and projects from an exterior side of the housing (where the arm  136  is located) into the second portion  132   b  of the locking mechanism recess  132  (where the polygonal section  138  is located). The pawls  116   a, b  are located on either side of the control  114  within the second portion  132   b  of the locking mechanism recess  132 . The concave sides of the pawls  116   a, b  abut the exterior surface of the polygonal section  138  of the control  114 . The first ends  140  of the pawls rest against the interior surface of the second portion  132   b  of the recess  132 , and the second ends  142  face the exterior surface of the ratchet  120 . The pawl springs  118   a ,  118   b  are positioned between the convex sides of the pawls and the inside of the second portion  132   b  of the locking mechanism recess  132  such that the pawl springs  118   a ,  118   b  urge the pawls  116   a ,  116   b  towards the control  114 , and more importantly into engagement with the ratchet  120  as will be discussed below. 
     The locking mechanism housing cover  126  seals the locking mechanism recess  132  with the first locking mechanism shaft  150  projecting therethrough ( FIG. 4 ). 
     The bearings  180 ,  182  are press-fitted into the bearing cavity  170  of the bracket  158  and secured with the circlip  184  which engages an internal groove in the bracket  158 . The pivot pin  186  is passed through the bracket  158  and bearings  180 ,  182  such that it forms a press-fit with the inner races of the bearings  180 ,  182 . In this way, the pivot pin  186  is configured to rotate relative to the bracket  158  about the pivot axis X. The seal  188  sits between the exterior surface of the flange  194  of the pivot pin  186  and the interior surface of the shoulder  176  ( FIG. 4 ). The first end of the shaft  190  of the pivot pin  186  with the radial bore  192  projects from the bracket  158 . 
     The locking mechanism subassembly  104  is mounted to the first mounting subassembly  106  and bearing subassembly  108  by engaging the shaft  190  of the pivot pin  186  into the opening in the first locking mechanism shaft  150 . The shaft bolt  122  and corresponding nut  124  are used to secure the shaft  190  of the pivot pin  186  and the first locking mechanism shaft  150  together. 
     The locking mechanism housing  112  is attached to the bracket  158  by securing the housing attachment leg  134  to the bracket  158  with the locking mechanism attachment screws  129   a ,  129   b . It is noted that the attachment point is distal to the pivot axis X, as the attachment will need to react the rotational forces about that axis. 
     The bracket  198  of the second mounting subassembly  110  is attached to the pivot pin  186  using the four bracket attachment bolts  202   a, b, c, d  and the pivot bolt  204 . 
     When assembled, the apparatus  100  can be mounted to an antenna and pole as shown in  FIG. 1 . The bracket  158  of the first mounting subassembly  106  is mounted to the pole clamp  26  using the two first mounting subassembly attachment bolts  164   a, b . The bracket  198  of the second mounting subassembly  110  is mounted to the flat face  16  of the antenna  10  using the two bracket mounting bolts  200   a, b.    
     In use, the pivot axis X is typically aligned with the vertical axis (i.e. azimuth axis). In some installations, it may be tilted, but is generally within 30 degrees of vertical. 
     Function 
     The apparatus  10  has two primary modes of operation—fixed and rotatable. 
     In the fixed mode, the control  114  is rotated into a first position such that the polygonal section  138  allows the pawls  116   a ,  116   b  to move towards it under the force of the pawl springs  118   a, b . This is shown in  FIG. 6 . This rotation means that the ratchet-engaging formations  144  of the teeth engage the ratchet teeth  148  of the ratchet  120  preventing any rotation about the axis X relative to the locking mechanism housing  112 . Because the locking mechanism housing  112  is attached to the bracket  158 , and the ratchet  120  is secured to the pivot pin which in turn is attached to the bracket  198 , rotation of the antenna about the pivot axis X is prohibited. 
     To rotate the antenna  10 , the control  114  is rotated through 45 degrees such that the pawls  116   a ,  116   b  are pushed outwardly against the bias of the springs  118   a ,  118   b  ( FIG. 7 ). This disengages the ratchet-engaging formations  144  of the teeth from the ratchet teeth  148  of the ratchet  120  and allows rotation of the ratchet  120 . This, in turn, permits azimuth rotation of the antenna about the pivot axis X. 
     The Second Embodiment 
     Referring to  FIGS. 8 to 15 , the second embodiment of the invention is similar to the first, and common reference numerals will be used to denote similar features. Only the differences between the embodiments will be described here. 
     Structure 
     Referring to  FIGS. 8 and 9 , there is provided a cellular antenna  10  being elongate in form having a first end  12 , a second end  14 , a flat back face  16  and a curved front face  18 . Constructional details of the antenna  10  will not be discussed further here, suffice to say that the antenna is a direction antenna configured to send and receive signals as part of a mobile phone network. 
       FIGS. 8 and 9  also show a vertical pole  20 , which is statically mounted to e.g. a building. The pole  20  is merely an example, and may be any other appropriate structure for mounting an antenna to (e.g. a mast). The exact position of the pole  20  is known by the operator. 
     A first pole clamp  22  and a second pole clamp  24  are also provided, being spaced apart in the longitudinal direction of the pole  20 . Each pole clap  22 ,  24  is immovably (but adjustably and removably) attached to the pole  20 . Each clamp presents a respective mounting face  26 ,  28  which is generally vertical and extending in a transverse direction relative to the pole  20 . 
     A first antenna steering and locking apparatus  100 , and a second antenna steering and locking apparatus  102  are provided between the respective clamps  22 ,  24  and the antenna  10 . The mounting apparatuses  100 ,  102  are identical to each other, and as such only the apparatus  100  will be described in detail here. 
     Referring to  FIGS. 2 to 7 , the apparatus  100  is shown in detail. Referring specifically to  FIG. 13 , the apparatus  100  comprises:
         A locking mechanism subassembly  104 ;   A first mounting subassembly  106 ;   A bearing subassembly  108 ;   A second mounting subassembly  110 ; and,   A controller  222 .
 
Locking Mechanism Subassembly  104 
       

     Unlike the locking mechanism subassembly of the first embodiment, the locking mechanism subassembly of the second embodiment comprises a actuator in the form of an electric motor  216 . The motor  216  has a housing  218  and an output shaft  220 . Note that in  FIG. 12 , the motor is shown schematically (and in reality would have several internal parts). 
     The housing  212  is attached to the locking mechanism housing  112  (not described in detail, but within the ability of the skilled man to envisage). The shaft  220  is engaged with control  114 . As such, activation of the motor will rotate the control  114  to engage and disengage the locking mechanism as described above with reference to the first embodiment. 
     Second Mounting Subassembly  110   
     Unlike the second mounting subassembly of the first embodiment, the second mounting subassembly of the second embodiment comprises a actuator in the form of an electric motor  210 . The motor  210  has a housing  212  and an output shaft  214 . Note that in  FIG. 12 , the motor is shown schematically (and in reality would have several internal parts). 
     The housing  212  is attached to the housing  158  (not described in detail, but within the ability of the skilled man to envisage). The shaft  214  is engaged with the pivot pin  186 . As such, activation of the motor will rotate the pivot pin  186  (and therefore the bracket  198  and antenna  10 ) relative to the housing  158 , and pole  20 . 
     Controller  222   
     The controller  222  is connected to each motor  210 ,  216  via data connections  224 ,  226  respectively ( FIG. 10 ). It will be noted that the controller  222  is connected in the same way to the motors of the second apparatus  102 , and can control both sets of motors simultaneously. 
     Function 
     The controller  222  is configured to carry out the following sequence of operation:
         Receive a command comprising azimuth adjustment data (for example, angle);   Engage the locking mechanism motor  216  to move the locking mechanism to the rotatable condition;   Engage the drive motor  210  to adjust the azimuth of the antenna to the desired position;   Engage the locking mechanism motor  216  to move the locking mechanism back to the fixed condition.       

     The Third Embodiment 
     Structure 
     Referring to  FIGS. 16 to 18 , instead of using the two pawls  116   a, b , and a ratchet  120  as shown in the first embodiment, a single ratchet-engaging member  316  and a ratchet  320  are provided as part of a locking mechanism subassembly  304 . 
     The ratchet-engaging member  316  is a body defining a ratchet-engaging formation  344  at a first end thereof. The ratchet-engaging formation  344  is concave with the same radius of curvature as the ratchet  320  (discussed below) and defines a plurality of teeth  345 . The ratchet-engaging member  316  is mounted for sliding movement within a housing of the locking mechanism subassembly  304  (not shown) in a direction D towards and away from the ratchet  320 . 
     The ratchet  320  has a cylindrical portion  346  defining a set of ratchet teeth  348  on a radially outwardly facing surface thereof. A first locking mechanism shaft  350  projects from a first side of the cylindrical portion  346 . 
     Function 
     Instead of using springs to pivot pawls into engagement with a ratchet, the ratchet-engaging member  316  can be moved between a first condition per  FIG. 17  and a second condition per  FIG. 18 . In the first condition, the teeth  345  of the ratchet-engaging member  316  engage the teeth  348  of the ratchet  320  and thereby rotationally fix the ratchet  320 . Per the ratchet  120 , the ratchet  320  is rotationally fixed to the antenna mount, and as such the first condition is the fixed condition. In the second condition, the ratchet-engaging member  316  is moved in direction D away from the ratchet  320  such that the ratchet  320  and associated antenna can rotate. This is the rotatable condition. 
     In a further embodiment, the ratchet-engaging member  316  is biased to the first (fixed) condition by e.g. a spring or other resilient mechanism and can be either manually (per the first embodiment) or automatically (per the second embodiment) moved to the second (rotatable) condition. 
     The Fourth Embodiment 
     Structure 
     Referring to  FIGS. 19 and 20  there is provided a ratchet  420  and a ratchet-engaging mechanism  416  as part of a locking mechanism subassembly  404 . 
     The ratchet  420  has a cylindrical portion  446  defining a set of ratchet teeth  448  on a radially outwardly facing surface thereof. A first locking mechanism shaft  450  projects from a first side of the cylindrical portion  446 . 
     The ratchet-engaging mechanism  416  comprises a ratchet-engaging member  418  and a collar  421 . 
     The ratchet-engaging member  418  comprises a hollow, cylindrical shaft  422  having a ratchet-engaging formation  424  defined at a first end. The ratchet-engaging formation  424  comprises a plurality of axially extending flexible tooth members  426 . The tooth members  426  have tapered radially outwardly facing edges  430 . The radially outwardly facing edges  430  of the tooth members  426  taper radially inwardly away from the shaft  422 . A shoulder  428  is defined on the outer surface of the shaft  422  facing the tooth members  426 . 
     The collar  421  comprises a hollow, cylindrical shaft  432  and a curved, frustroconical tapered region  434  extending therefrom. The curved, frustroconical tapered region  434  tapers radially inwardly away from the shaft  432 . 
     The ratchet-engaging member  418  and a collar  421  are rotationally fixed but linearly moveable relative to each other via e.g. a spline  436  (visible only in  FIG. 19 ). 
     Assembly 
     The ratchet  420  is generally rotationally fixed to one of the antenna bracket and pole mount (as discussed above). The ratchet-engaging mechanism  416  is attached to the other. The ratchet  420  is inserted into the ratchet-engaging member  418  such that the teeth of the former  448  face the tooth members  426  of the outer (although they are not engaged—see  FIG. 19 ). The collar  421  is assembled to the ratchet-engaging member  418  via the spline  436 . 
     The ratchet  420  can rotate freely relative to the ratchet-engaging mechanism  416  in this mode (i.e. the rotatable condition). 
     When it is desired to lock the antenna, the collar  421  is moved axially in direction D such that the tapered region  434  radially inwardly deforms the flexible tooth members  426 . This forces them into engagement with the ratchet teeth  448  to fix the ratchet  420  relative to the ratchet-engaging mechanism  416 . This is the locked condition. 
     The Fifth Embodiment 
     Structure 
     Referring to  FIG. 21  certain sub-assemblies of a fifth steering and locking apparatus  500  are shown, specifically:
         A locking mechanism subassembly  504 ;   A first mounting subassembly  506 ; and,   A bearing subassembly  508 .       

     The first mounting subassembly  506  and bearing subassembly  508  are similar to those of the first and second embodiments and will not be described in detail. It should also be noted that a second mounting subassembly, being pivotable about the first mounting subassembly  506  via the bearing subassembly  508  but is not shown. 
     Locking Mechanism Subassembly  504   
     The locking mechanism subassembly  504  comprises a housing  512  having a first end plate  514  and a second end plate  516 . 
     Referring to  FIGS. 22 and 23 , encapsulated within the housing  512  there is provided a central shaft  518  rotatable on an azimuth steering axis X. This shaft is, in use, coupled to the pivot shaft of the second mounting subassembly, and rotates therewith relative to the first mounting subassembly  506  as with the first and second embodiments. 
     Two ratchets  520 ,  522  are mounted on the shaft. The ratchets  520 ,  522  are mounted adjacent one another along the shaft  518 . The ratchet  520  has a cylindrical portion  524  defining a set of ratchet teeth  526  on a radially outwardly facing surface thereof. The ratchet  522  has a cylindrical portion  528  defining a set of ratchet teeth  530  on a radially outwardly facing surface thereof. 
     Referring to  FIG. 24 , the teeth  526 ,  530  of the ratchets  520 ,  522  are shown in detail, viewed in direction XXIV in  FIG. 23 . The ratchet  522  (and hence teeth  530 ) are in the foreground. Each tooth  530  is angle A1 apart, meaning there are 
             N   =       3   ⁢   6   ⁢   0       A   ⁢   1             
teeth. In this embodiment A1=10 degrees, meaning there are N=36 teeth. Each tooth  530  has a raked face  532 , a radial face  534  and a flat, generally circumferential end face  535 . The internal angle A2 between the raked face and radial face is 52.72 degrees in this embodiment. Each tooth has a length Lt of 3.05 mm. The ratchets  520 ,  522  have a radius of 23.85 mm in this embodiment.
 
     It will be noted that (referring to  FIGS. 22 and 23 ) the teeth  526  of the ratchet  520  face in a first rotational direction RD 1 , whereas the teeth  530  of the ratchet  522  face in the opposite rotational direction RD 2 . The rotational direction is the direction in which the radial faces  534  face. 
     Four pawls  536 ,  538 ,  540 ,  542  are provided within the housing  512 . Two pawls  536 ,  538  are associated with the first ratchet  520 , and two pawls  540 ,  542  are associated with the second ratchet  522 . 
     Referring to  FIG. 25 , the second ratchet  522  is shown with the pawls  540 ,  542 . The pawls  540 ,  542  are identical, and as such only the pawl  540  will be described in detail. The pawl  540  comprises a generally prismatic body  544  tapering inwardly from a mounted end  546  to a free end  548 . The pawl defines a convex sidewall  550  and a concave sidewall  552 . The concave sidewall  552  defines a plurality of (in this case five) teeth  554 . Each tooth  554  has a is angle A1 apart. Each tooth  554  has a raked face  556 , a radial face  558  and a flat, generally circumferential end face  560 . The internal angle A2 between the raked face and radial face is 52.72 degrees in this embodiment. Each tooth has a length Lt of 3.05 mm. The concave face  552  of the pawl  540  has a radius of 23.85 mm in this embodiment. As a result, the teeth are complementary and engageable with the teeth  530  of the ratchet  522 . Referring to the pawl  542 , it is shown engaged with the ratchet  522 . 
     The pawls  540 ,  542  are mounted on respective pawl axes O and P for rotation thereabout. Axes  0  and P are parallel to the steering axis X, and both disposed at a common pawl radius PR from the axis X. Each pawl  540 ,  542  is biased into engagement with the ratchet  522 . 
     The pawls  540 ,  542  are, as discussed above, circumferentially spaced about the axis X. The pawl positions are selected such that, given N teeth of angle A1 apart, the pawl  540  fully engages at every A1 degrees (i.e. in this embodiment, every 10 degrees). The pawl  544  is positioned apart from the pawl  540  by angle 
               P   ⁢   S   ⁢   A     =       (       M   ·   A     ⁢           ⁢   1     )     +       A   ⁢   1     2             
degrees, where M is an integer. In other words, the pawl  542  is positioned at a phase offset of
 
               A   ⁢   1     2         
degrees. In this embodiment, PSA=85 degrees, and
 
                 A   ⁢   1     2     =     5   .           
This means that the ratchet  522  is fully engaged (and prevented from being backdriven) every 5 degrees. In other words, the ratchet “resolution” is 5 degrees, even though the teeth are 10 degrees apart.
 
     The pawls  536 ,  538  are identical to the pawls  540 ,  542 , although facing in the opposite circumferential direction about the first ratchet  520 . Each of the first pair of pawls  536 ,  538  is positioned to be “in phase” (i.e. simultaneously fully engaged with its respective ratchet at a given rotational position of the shaft  518 ) with a respective one of the second pair of pawls  540 ,  542 . 
     Each of the pawls can be retracted from engagement with the respective ratchets. Although not shown in detail, it will be understood that means are provided for rotating each pawl about its pawl axis to move the teeth out of engagement with the ratchet teeth, thus permitting rotational movement of the ratchet in the otherwise locked rotational direction. 
     Assembly 
     The ratchets  520 ,  522  and pawls  536 ,  538 ,  540 ,  542  are mounted and encapsulated and sealed within the housing  512 . 
     Function 
     The locking mechanism subassembly  504  has a fully locked condition in which all four pawls are released under bias to contact the respective ratchet ( FIGS. 22-25 ). In this embodiment, the pawls  538  and  542  are fully engaged with the ratchets  520 ,  522  respectively. The engagement of the pawl  538  with the ratchet  520  inhibits rotation in the direction RD 1 . The engagement of the pawl  542  with the ratchet  522  inhibits rotation in the direction RD 1 . The shaft  518  is therefore unable to rotate. 
     In order to steer the cellular antenna, in a first method, all four pawls are moved to the released position (i.e. out of contact with the respective ratchets). The shaft  518  can then be rotated to the desired position and the pawls released to lock the shaft  518 . 
     In a second, alternative method, only the pawls  536 ,  538  may be released, allowing the shaft  518  to be steered in direction RD 1 . The resiliently biased pawls  540 ,  542  “ride over” the teeth of the ratchet at the shaft  518  is rotated, but also inhibit reserve rotation in direction RD 2 . Similarly, only the pawls  540 ,  542  may be released for rotation in direction RD 2 . 
     It will be noted that in this embodiment, the shaft can be rotated by 360 degrees and locked in 5 degree increments. In practice, cellular antennas are only rotated by ±60 degrees at most. 
     In a modification to the above embodiment, the pawls  536 ,  538 ,  540 ,  542  may be electrically moved by e.g. an electromechanical actuator or solenoid. A controller may be provided to undergo the operational steps discussed above, including a step of rotating the antenna with an electric motor. 
     In a further modification, a third pawl may be provided with each ratchet. The third pawl may have a phase offset of 
               A   ⁢   1     4         
degrees, providing (in this embodiment) 2.5 degrees of resolution.
 
     The Sixth Embodiment 
     Structure 
     Referring to  FIG. 26 , a locking mechanism subassembly  604  of a sixth steering and locking apparatus  600  is shown. 
     The locking mechanism subassembly  604  is for use with a first mounting subassembly and bearing subassembly similar to those of the first and second embodiments (which will not be described in detail). 
     Locking Mechanism Subassembly  604   
     The locking mechanism subassembly  604  comprises a housing  612  having an end plate  614 . A central shaft  618  is provided for attachment to a mounting subassembly of an antenna steering apparatus. 
     Referring to  FIGS. 27 and 28 , encapsulated within the housing  612  the central shaft  618  is mounted on a first bearing  615  and a second bearing  616 , so as to be rotatable on an azimuth steering axis X. 
     A ratchet  620  is mounted on the shaft  618 . The ratchet  620  has a cylindrical portion  624  defining a first set of ratchet teeth  626  and a second set of ratchet teeth  628  on a radially outwardly facing surface thereof. Each set of teeth extend along the axial width of the ratchet  620  by the same distance, but cover only half of the perimeter each. In other words, each set of ratchet teeth  626 ,  628  cover 180 degrees (or a respective semi-cylindrical surface) of the ratchet  620 . 
     Referring to  FIG. 30 , the teeth  626 ,  628  of the ratchet  620  are shown in detail. 
     The teeth  626  are an angle A1 apart. In this embodiment A1=10 degrees, and there are 17 teeth  626 . Each tooth  626  has a raked face  632 , a radial face  634  and a flat, generally circumferential end face  635 . The internal angle A2 between the raked face and radial face is 52.72 degrees in this embodiment. Each tooth has a length Lt of 3.05 mm. The ratchet  620  has a radius Rr of 23.85 mm in this embodiment. 
     The teeth  628  are identical to the teeth  626  except for the fact that the face in the opposite direction—i.e. referring to  FIG. 30 , the teeth  626  face in direction RD 1 , and the teeth  628  in direction RD 2 . 
     Four pawls  636 ,  638 ,  640 ,  642  are provided within the housing  512 . Two pawls  636 ,  638  are associated with the first set of teeth  626 , and two pawls  640 ,  642  are associated with the second set of teeth  628 . The pawls  636 ,  638  are mounted on a first common pawl shaft  639  for rotation relative to each other about a first pawl axis Q, and the pawls  640 ,  642  are mounted on a second common pawl shaft  643  for rotation about a second pawl axis R. Both axes Q, R are parallel to the steering axis X, and both disposed at a common pawl radius PR from the axis X. Each pawl is biased into engagement with the ratchet  620 . 
     The pawls  636 ,  638 ,  640 ,  642  are similar to each other. The pawls  636 ,  640  are identical, and the pawls  640 ,  642  are identical. 
     The pawl  636  comprises a generally prismatic body  644  tapering inwardly from a mounted end  646  to a free end  648 . The pawl defines a convex sidewall  650  and a concave sidewall  652 . The concave sidewall  652  defines a plurality of (in this case five) teeth  654 . Each tooth  654  has a is angle A1 apart. Each tooth  654  has a raked face  656 , a radial face  658 . The internal angle A2 between the raked face and radial face is 52.72 degrees in this embodiment. Each tooth has a length Lt of 3.05 mm. The concave face  652  of the pawl  640  has a radius of 23.85 mm in this embodiment. As a result, the teeth are complementary and engageable with the teeth  626  of the ratchet  620 . Referring to the pawl  636 , it is shown engaged with the ratchet  620 . 
     Referring to  FIG. 31 , the pawls  640 ,  642  are shown at the same angular position. As can be seen, the teeth  654  of the pawl  640  are phase offset compared to the teeth  654 ′ of the pawl  642 . As discussed, each tooth  654  on the pawl  640  are A1 degrees apart (i.e. about the geometric centre of the concave face/steering axis X). It will be noted that the teeth  654 ′ of the pawl  642  are also A1 degrees apart, but offset by 
               A   ⁢   1     2         
degrees. This provides the same effect as the phase offset pawls of the fifth embodiment—i.e. to provide a higher resolution.
 
     The pawls are therefore configured such that, given ratchet teeth of angle A1 apart, one of the pawls fully engages at every 
               A   ⁢   1     2         
degrees (i.e. in this embodiment, every 5 degrees.
 
     The pawls  636 ,  638  are identical to the pawls  640 ,  642 , although facing in the opposite circumferential direction about the ratchet  620 , and engaging respective sets of teeth. 
     Each of the pawls  636 ,  638 ,  640 ,  642  is resiliently biased into engagement with the ratchet by e.g. a spring or other similar mechanism. 
     Each of the pawls can be retracted from engagement with the respective ratchets. Although not shown in detail, it will be understood that means are provided for rotating each pawl about its pawl axis to move the teeth out of engagement with the ratchet teeth, thus permitting rotational movement of the ratchet in the otherwise locked rotational direction. As shown in  FIG. 31  in particular, an abutment  662  extends to an opposite side of the pawl axis R, and a force PF on the pawl is applied to rotate it against the bias out of engagement with the ratchet. The force PF may be applied via manual means (e.g. a button) or by an electromechanical actuator or solenoid. 
     Function 
     The locking mechanism subassembly  604  has a fully locked condition in which all four pawls are released under bias to contact the respective ratchet ( FIG. 29 ). In this embodiment, the pawls  636  and  640  are fully engaged with the ratchet  620 . The engagement of the pawl  636  with the ratchet  620  inhibits rotation in the direction RD 1 . The engagement of the pawl  640  with the ratchet  620  inhibits rotation in the direction RD 2 . The shaft  618  is therefore unable to rotate. 
     In order to steer the cellular antenna, in a first method, all four pawls are moved to the released position (i.e. out of contact with the respective ratchets) by applying forces PF. The shaft  618  can then be rotated to the desired position and the pawls released to lock the shaft  618 . 
     In a second, alternative method, only the pawls  636 ,  638  may be released, allowing the shaft  618  to be steered in direction RD 1 . The resiliently biased pawls  640 ,  642  “ride over” the teeth of the ratchet as the shaft  618  is rotated, but also inhibit reserve rotation in direction RD 2 . Similarly, only the pawls  640 ,  642  may be released for rotation in direction RD 2 . 
     It will be noted that in this embodiment, the shaft can be rotated by ±60 degrees at most. 
     A controller may be provided to undergo the operational steps discussed above, including a step of applying the force PF to the required pawls and rotating the antenna with an electric motor. 
     In a further modification, a third pawl may be provided on each side of the ratchet. The third pawl may be configured with a phase offset of 
               A   ⁢   1     4         
degrees, providing (in this embodiment) 2.5 degrees of resolution.
 
Variations
 
     It will be noted that the provision of pawls at different, and phase offset circumferential positions per the fifth embodiment may be employed with the ratchet configuration of the sixth embodiment (noting that the pawls will still need to be axially adjacent for packaging reasons). Similarly, pawls which are positioned at the same circumferential position but with the phase offset effected by the configuration of the teeth (the sixth embodiment) may be used with e.g. the fifth embodiment. What is important is that the pawls are provided having a phase offset. 
     Clamping Mechanisms 
       FIG. 32  onwards show four different types of clamp mechanism which can be used to attach the steering and locking apparatuses  100 ,  200 ,  300 ,  400 ,  500 ,  600  to a mast. Each clamp is configured for attachment to different types of mast component as follows:
         Clamp  1106  ( FIGS. 32 to 37 ) for attachment to a right-angle section;   Clamp  1206  ( FIGS. 38 to 41 ) for attachment to a square section;   Clamp  1306  ( FIGS. 42 to 43 ) for attachment to a circle section; and,   Clamp  1406  ( FIGS. 44 to 45 ) for attachment to a horizontal square section.       

     The traditional antenna mounting system is shown in  FIG. 1 . The pole  20  is typically attached to the mast via a pair of antenna supports, which are usually in the form of a pair of vertically spaced-apart, horizontal supports. This has several drawbacks. 
     Firstly, the antenna supports and pole are all metal components (typically steel) and add considerable weight load to the mast. 
     Secondly, because the pole needs to be spaced-apart from the mast to allow access by the riggers, the supports create a moment arm for wind loads on the antenna. As such, the mast is put under greater stress from wind loading. 
     Thirdly, both part and installation cost is high with this approach, as several components need to be manufactured and assembled. 
     Fourthly, the supports require holes to be drilled in the mast, which is undesirable and time consuming. 
     The following mechanisms seek to mitigate these problems, and thereby present a suitable mounting arrangement for the steering and locking mechanisms mentioned in the present application. In particular, the combination of the ratchet arrangements hereinbefore described with the following clamp concepts reduce the risk of wind loads moving the antennas out of position. They also facilitate easier set up and positioning. 
     Clamp  1106  ( FIGS. 32 to 37 ) for Attachment to a Right-Angle Section 
     Referring to  FIGS. 32 to 37 , an antenna  1100  is attached to a mast  1102  via a first mounting assembly  1104  comprising a first clamp  1106  and a first steering and locking apparatus  1108 , and a second mounting assembly  1110  comprising a second clamp  1112  and a second steering steering and locking apparatus  1114 . 
     Antenna 
     The antenna  1100  is a cellular antenna—that is an antenna configured to receive and transmit mobile telephone and data signals primarily for portable devices such as cellular phones, tablets, Mi-Fi devices etc. Such antennas are well known in the art, and will not be described in detail here. 
     Mast 
     The mast  1102  is also generally well-known in the art and comprises at least one upright or vertical member  1116  which is configured as an “L” shape in section, having a first leg  1118 , second leg  1120  and an apex  1122  ( FIG. 34 ). The vertical member  1116  is an integral, load-bearing part of the mast. 
     Referring to  FIG. 34 , each leg  1118 ,  1120  has an equal width A. 
     Clamps 
     The first clamp  1106  and second clamp  1112  are identical, and as such only the first clamp  1106  will be described here. 
     Referring to  FIG. 33 , the first clamp  1106  comprises a mounting member  1124  and a clamp member  1126 . 
     The mounting member  1124  is generally L-shaped in cross-section having a first leg  1128  and a second leg  1130 . An apex  1132  is defined between the first and second legs  1128 ,  1130 . 
     The first leg  1128  comprises two clamping bores  1134  spaced at the opposite end of the first leg  1128  to the apex  1132 . The clamping bores  1134  are arranged vertically in use (i.e. parallel to the azimuth steering axis as defined below). The first leg  1128  further comprises two mounting bores  1136 , which are arranged horizontally in use, with one proximate the apex, and one midway between the two clamping bores  1134 . The mounting bores  1136  are countersunk, opening towards a concave (mast) side of the mounting member  1124 . 
     The second leg  1130  is a mirror image of the first leg  1128 . It comprises two clamping bores  1138  spaced at the opposite end of the first leg  1130  to the apex  1132 . The clamping bores  1138  are arranged vertically in use (i.e. parallel to the azimuth steering axis as defined below). The first leg  1130  further comprises two mounting bores  1140 , which are arranged horizontally in use, with one proximate the apex, and one midway between the two clamping bores  1138 . The mounting bores  1140  are countersunk, opening towards a concave (mast) side of the mounting member  1124 . 
     Referring to  FIG. 34 , each leg  1128 ,  1130  has a width C, and a distance between mounting bores  1136  of E. 
     The clamp member  1126  is generally L-shaped in cross-section having a first leg  1142  and a second leg  1144 . An apex  1146  is defined between the first and second legs  1142 ,  1144 . 
     The first leg  1142  comprises two clamping bores  1148  spaced at the opposite end of the first leg  1142  to the apex  1146 . The clamping bores  1148  are arranged vertically in use (i.e. parallel to the azimuth steering axis as defined below). 
     The second leg  1144  comprises two clamping bores  1150  spaced at the opposite end of the second leg  1144  to the apex  1146 . The clamping bores  1150  are arranged vertically in use (i.e. parallel to the azimuth steering axis as defined below). 
     The clamp member  1126  has a thickness D shown in  FIG. 34 . 
     Steering and Locking Apparatuses 
     The steering and locking apparatuses  1108 ,  1112  are identical. The steering and locking apparatuses comprise a locking subassembly according to the invention. 
     Installation 
     The first step is to attach one (or more) steering and locking apparatuses  1108  to the mounting member  1124 . This is achieved by passing mechanical fasteners (bolts) from the concave (mast) side of the mounting member  1124 , through the mounting bores  1136 , and through aligned openings on the steering and locking apparatus  1108 . Nuts are used to fasten the steering and locking apparatus  1108  to the mounting member  1124 . 
     The second step is to attach the assembled steering and locking apparatus  1108  and mounting member  1124  to the mast  1102 . This is achieved by clamping the mast member  1116  between the mounting member  1124  and the clamp member  1126  as shown in  FIG. 33  (the steering unit  1108  is not shown for clarity). Mechanical fasteners in the form of bolts  1170  through the clamping bores  1134  and clamping bores  1148 . Nuts  1172  are used to fasten the legs  1128 ,  1142  together. Mechanical fasteners in the form of bolts  1174  through the clamping bores  1138  and clamping bores  1150 . Nuts  1176  are used to fasten the legs  1130 ,  1144  together. As such, the mast member  1116  is clamped or sandwiched between the mounting member  1124  and the clamp member  1126 . 
     The same process is repeated for the second steering and locking apparatus  1114  and second clamp  1112 , on the same mast member  1116  except axially offset from the first steering unit  1108  and first clamp  1106 . 
     The antenna  1100  is then mounted to the respective antenna mounting flanges of the steering and locking apparatus  108 ,  112  as shown in  FIG. 32 . 
     Multiple Antennas 
     As shown in  FIG. 36 , a further antenna  1100 ′ can be attached to the second leg of the mounting member  1124 , thus facing 90 degrees to the first (at zero steering angle). 
     Spacers 
     Referring to  FIG. 37 , in a further implementation of the invention, if it is desirable to provide more distance between the mast and the antenna  1100 , a spacer  1178  may be positioned between the first clamp  1106  and the first steering and locking apparatus  1110 . The spacer  1178  may be e.g. a tubular metal section. 
     It will be noted that the first embodiment relies exclusively on friction to hold the clamp on the mast member. There are no e.g. mechanical fasteners passing through apertures in the mast member to secure the clamp thereto. The fasteners holding the clamp together are all offset from the mast member, and all pass through the clamp members at an overlap/overhanging region of the clamp members relative to the mast member. 
     Clamp  1206  ( FIGS. 38 to 41 ) for Attachment to a Square Section 
     Referring to  FIG. 38 , an antenna  1200  is attached to a mast  1202  via a first mounting assembly  1204  comprising a first clamp  1206  and a first steering and locking apparatus  1208 , and a second mounting assembly  1210  comprising a second clamp  1212  and a second steering and locking apparatus  1214 . 
     Antenna 
     The antenna  1200  is identical to the antenna  1100 . 
     Mast 
     The mast  1202  is also generally well-known in the art and comprises at least one upright or vertical member  1216  which is configured as a tubular square section. The vertical member  1216  is an integral, load-bearing part of the mast. 
     Clamps 
     The clamps  1206 ,  1212  are the main difference between the first and second embodiments. The clamps  1206 ,  1212  are identical, and as such only the clamp  1206  will be described with reference to  FIGS. 40 and 41 . 
     The clamp  1206  comprises a mounting member  1224 , a clamp member  1226  and an angle bracket  1228 . 
     The mounting member  1224  is a flat plate comprising four clamping bores  1230  at each corner. Two mounting bores  1232  are provided through the plate, being on the mast-side in use. Two angle bracket attachment bores  1233  are also provided through the plate. The angle bracket attachment bores  1233  are positioned on either side of one of the mounting bores  1232 . 
     The clamp member  1226  is identical to the mounting member  1224 . 
     The angle bracket  1228  is L-shaped in cross section comprising a first leg  1234  and a second leg  1236 . The second leg  1236  has a pair of attachment bores  1238  defined therethrough. 
     Steering and Locking Apparatus 
     The steering and locking apparatus  1208 ,  1212  are identical to the steering and locking apparatuses  1108 ,  1112 . 
     Installation 
     The first step is to attach one (or more) steering and locking apparatuses  1208  to the mounting member  1224 . This is achieved by passing mechanical fasteners (bolts) from the mast side of the mounting member  1224 , through the mounting bores  1230 , and through aligned openings on the mounting flange of the steering and locking apparatus  1208 . Nuts are used to fasten the steering and locking apparatus  1208  to the mounting member  1224 . 
     The second step is to attach the angle bracket  1228  to the mounting member  1224 . Bolts  1274  are passed through the bracket attachment bores  1233 , through the attachment bores  1238  and secured with nuts  1276 . 
     The third step is to attach the assembled steering and locking apparatus  1208  and mounting member  1224  to the mast  1202 . This is achieved by clamping the mast member  1216  between the mounting member  1224  and the clamp member  1226  as shown in  FIGS. 40 and 41  (the steering unit  1208  is not shown for clarity). Mechanical fasteners in the form of bolts  1270  are secured through the clamping bores  1230  of both the mounting member  1224  and clamp member  1226 . Nuts  1272  are used to fasten the mounting member  1224  and clamp member  1226  together. As such, the mast member  1216  is clamped or sandwiched between the mounting member  1224  and the clamp member  1226 . 
     The same process is repeated for the second steering unit  1214  and second clamp  1212 , on the same mast member  1216  except axially offset from the first steering and locking apparatus  1208  and first clamp  1206 . 
     The antenna  1200  is then mounted to the respective antenna mounting flanges of the steering and locking apparatuses  1208 ,  1212  as shown in  FIG. 38 . 
     Clamp  1306  ( FIGS. 42 to 43 ) for Attachment to a Circle Section 
     Referring to  FIG. 43 , an antenna  1300  is attached to a mast via a first mounting assembly  1304  comprising a first clamp  1306  and a first steering and locking apparatus  1308 , and a second mounting assembly  1310  comprising a second clamp  1312  and a second steering and locking apparatus (not visible). 
     Antenna 
     The antenna  1300  is identical to the antenna  1100 . 
     Mast 
     The mast is generally well-known in the art and comprises at least one upright or vertical member  1316  which is configured as a tubular circle section. 
     Clamps 
     The clamps  1306 ,  1312  are the main difference between the second and third embodiments. The clamps  1306 ,  1312  are identical, and as such only the clamp  1306  will be described with reference to  FIG. 43 . 
     The clamp  1306  comprises a first clamp member  1326  and a second clamp member  1328 . Each clamp member  1326 ,  1328  is identical, comprising a semi-circular concave pole receiving formation  1330  on one side. This enables the clamp members  1326 ,  1328  to be secured together to clamp the member  1316  therebetween. 
     The steering and locking apparatus  1308  is attached to the first clamp member  1326 . 
     Clamp  1406  ( FIGS. 44 to 45 ) for Attachment to a Horizontal Square Section 
     Referring to  FIG. 44 , an antenna  1400  is attached to a mast  1402  via a first clamp  1406 , a second clamp  1408 , a backplate  1410 , a first steering and locking apparatus  1412  and a second steering and locking apparatus  1414 . 
     Antenna 
     The antenna  1400  is identical to the antenna  1100 . 
     Mast 
     The mast  1402  is generally well-known in the art and comprises at least a first horizontal member  1416  and a second horizontal member  1418 , both of which are configured as a tubular square section. 
     Clamps 
     The clamps  1406 ,  1408  are are identical, and as such only the clamp  1406  will be described with reference to  FIG. 45 . 
     The clamp  1406  comprises a first U-shaped clamp member  1420 , a second U-shaped clamp member  1422 . The U-shaped clamp members  1420 ,  1422  are secured together either side (top and bottom) of the horizontal member  1416  with mechanical fasteners to clamp it therebetween. 
     Backplate 
     The backplate is an elongate, flat extruded component. Once both clamps  1406 ,  1408  are in place, the backplate  1410  is attached to them, and extends vertically between them. 
     Steering and Locking Apparatus 
     The steering and locking apparatus  1412 ,  1414  are identical to the steering and locking apparatuses  1108 ,  1112 . They are attached to the backplate  1410  to allow steering and locking of the antenna  1400  as described above. 
     The clamping solutions improve the aerodynamics of the mast at tower top (where the antennas and antenna near products are installed), thus improving static performance of the whole mast structure. 
     The tower aerodynamic is improved as the effective surface area at tower top (where the antennas are located) is reduced since the antennas are moved closer to the mast structure without losing functionality (i.e. their azimuth steering capabilities). 
     Use of the clamps also reduces the antenna system weight at tower top. 
     It will be noted that the azimuth steering and locking apparatuses (top-bottom) need to be vertically aligned at the installation phase so as not to twist the antenna. Vertical alignment is achieved with the aforementioned clamps, since their azimuth mounting screw holes can be CNC machined with very low degrees of tolerance.