Antenna fixing system

TECHNICAL FIELD

The invention relates to the field of antenna fixing systems, and more particularly to antenna fixing systems providing a device for adjusting an antenna tilting angle.

BACKGROUND Base station antennas are commonly fixed to a fixture device, e.g. a pole, in such a manner that an antenna tilting angle which is the angle between the antenna and a vertical is adjustable. For this reason, the antennas are provided with antenna fixing systems being adjustable. After the adjustment, a set antenna tiling angle is secured by clamping a joint of an articulated lever arrangement comprising two joint levers usually attached at an upper region of the antenna.

A joint angle of the two levers is secured by clamping the levers with respect to one another. In order to ensure a safe clamping, multiple (usually three) bolts are used for clamping the levers by a friction force between clamped planar contacting faces of the levers.

Therefore, excessive work, in particular when working on a high platform, is to be performed since too may bolts are to be operated which takes too much time to adjust and lock the tilt of the antenna.

SUM MARY

It is therefore an object of the present invention to provide an improved antenna fixing sys- tern.

The object is achieved by the features of the independent claim. Further developments of the invention are apparent from the dependent claims, the description and the figures. According to an aspect, an antenna fixing system comprises a twistable lever arrangement of at least a first and a second lever connected by a joint for adjusting a tilting angle controlled by the two levers, wherein the joint comprises a set of a first shell comprising a first predetermined circular embossed elevation in direction of the joint axis and being connected to the first lever rotatable around the joint axis and a second shell comprising a second predetermined circular embossed elevation in direction of the joint axis and being connected to the second lever rotatable around the joint axis, wherein the first elevation and the second elevation correspond to one another in a predetermined contacting diameter range around the joint axis, wherein the first and second shells are arranged in a staggered manner such that the shells are in a surface contact at least in the contacting diameter range, and a straight line, intersecting the joint axis and tangentially touching the elevation or lying in the elevation in the predetermined contacting diameter range, and a line radially extending from the joint axis enclose a predetermined angle, and a clamping device comprising at least a bolt configured to exert a clamping force to the set in direction of the joint axis. Due to the configuration having circular embossed elevations contacting each other in a predetermined contacting diameter range around the joint axis, compared to a conventional arrangement of multiple clamping bolts, an appropriate friction force between the first elevation and the second elevation and, therefore, between the first and second lever, is provided by at least a bolt so that a holding torque by one bolt for holding a weight of the antenna can be increased and a quick and safe tightening of the adjusted joint is enabled. Therefore, the holding torque can be provided with merely one clamping bolt which decreases workload for adjusting and tightening the joint. Hence, an improved antenna fixing system is provided enabling a quick and safe adjustment of a tilting angle of an antenna.

According to a first implementation of the antenna fixing system according to the aspect, the predetermined angle is in a range of 40 to 80 degrees.

By providing this angular range, a relationship between a clamping torque applied to the bolt for generating the clamping force and the friction force between the first elevation and second elevation is enhanced. Due to the lower limit, a sufficient friction force is enabled and, due to the upper limit, self-retention is prevented. Alternatively, the predetermined angle can also be in another angular range. Then, the limits should be set according to an appropriate function depending on the surface roughness. According to a second implementation of the antenna fixing system according to the aspect or to the first implementation, the antenna fixing system comprises a further set, wherein the clamping device is configured to exert the clamping force to both of the sets.

By providing the further set, the holding torque of the antenna fixing system can be further increased upon applying an equal clamping torque. Alternatively, additional further sets may be provided.

According to a third implementation of the antenna fixing system according to the second implementation, the sets are oriented such that the elevations of the shells are facing each other. When arranging the sets such that the elevations of the shells are facing each other, an entire width of the antenna fixing system is low such that, even when the further set is provided, the installation space can be maintained small, e.g. due to optical design reasons.

According to a fourth implementation of the antenna fixing system according to the second implementation, the sets are oriented such that the elevations of the shells are averted from each other.

By arranging the sets such that the elevations of the shells are averted from each other, components of the antenna, e.g. cables, can be installed between the shells.

According to a fifth implementation of the antenna fixing system according to any of the second to fourth implementation, the clamping device comprises a sleeve around the bolt, the sleeve, by having a length adapted to provide a spacer located between the elevations and contacting the elevations, being configured such that the two sets can be clamped by one clamping device.

The sleeve maintains a distance between the elevations and transmits the clamping force of the bolt to both of the sets. According to a sixth implementation of the antenna fixing system according to any of the aspect or the preceding implementations, the clamping device comprises a threaded bolt and a nut. The clamping force is generated by tightening the nut on the threaded bolt. However, the clamping force can also by applied by another principle.

According to a seventh implementation of the antenna fixing system according to the sixth implementation, the nut comprises a handwheel. By providing the handwheel, no tools are necessary for clamping the antenna fixing system so that the operation for adjusting the joint is enhanced and facilitated.

According to an eighth implementation of the antenna fixing system according to any of the aspect or the second to fifth implementation, the clamping device comprises a quick release skewer. By providing the quick release skewer, also, no tools are necessary for clamping the antenna fixing system and the process of clamping is shortened so that the operation for adjusting the joint is enhanced and facilitated.

According to a ninth implementation of the antenna fixing system according to any of the aspect or the preceding implementations, at least one of the elevations of the set is provided with a bead directed away from another of the elevations. The bead is directed away from another of the elevations in order not to contact the other elevation such that the surface contact in the predetermined contacting diameter range around the joint axis is maintained.

The bead increases stiffness of the elevation such that a deformation of the elevation and, therefore, a stroke for clamping the clamping device is reduced. According to a tenth implementation of the antenna fixing system according to the ninth implementation, each of the elevations of the set is provided with a bead.

Due to the provision of each of the elevations with a bead, compared to the provision of only one elevation having a bead, stiffness of the sets is further increased.

According to a eleventh implementation of the antenna fixing system according to anyone of the aspect or the preceding implementations, a surface of one of the shells facing another of the set comprise a slide-blocking surface in the predetermined contacting diameter range.

When providing a slide-blocking surface in the predetermined contacting diameter range, the friction force between the first elevation and the second elevation can be further enhanced so that the clamping torque can be reduced and the tightening of the clamping device is facilitated.

According to a twelfth implementation of the antenna fixing system according to anyone of the aspect or the preceding implementations, the joint comprises a scale around the joint axis configured to enable informing about a set antenna tilting angle.

By providing the scale indicating the antenna tilting angle, adjustment of the antenna can be further facilitated.

BRIEF DESCRIPTION OF THE DRAWINGS In the following detailed portion of the present disclosure, the invention will be explained in more detail with reference to the exemplary embodiment shown in the drawings, in which:

Fig. 1 schematically shows a portion of a conventional antenna fixing system;

Fig. 2 shows a portion of an antenna fixing system according to an embodiment the invention; Fig. 3 shows a sectional view of a set of shells of the antenna fixing system from

Fig- 2;

Fig. 4 shows an exploded view of the set of shells, a further set of shells and a clamping device of the antenna fixing system according to an embodiment the invention; Fig. 5 shows the exploded view of Fig. 4 depicting a modification of the clamping device;

Fig. 6 shows the exploded view of Fig. 4 depicting a further modification of the clamping device; and

Fig. 7 shows a front view of the portion of the antenna fixing system according to an embodiment the invention illustrated with a variety of modifications of the shells.

Identical reference signs are used for identical or at least functionally equivalent features. DETAILED DESCRIPTION OF THE DRAWINGS

Fig. 1 schematically shows a portion of a conventional antenna fixing system 100 having a twistable lever arrangement 200. The lever arrangement 200 is provided with a first lever 300 and a second lever 400. The levers 300, 400 are clamped by a clamping device 1000 including three bolts 1100. One of the bolts 1100 is provided in a joint axis A and the other two bolts are provided having a spacing form the joint axis A (whereas only can be seen in Fig. 1 as the rear bolt is covered by the front bolt).

In a statics analysis, for the configuration shown in Fig. 1, eq uation (1) results: μ · Fv Sl + μ - Fv · S2 = M (1) wherein: μ is a static friction coefficient,

Fv is a bolt pre-tightening force,

51 is a bolt spacing from the joint axis A,

52 is a lever arm of the friction force at the center bolt 1100, the lever arm being related to a hole diameter and a diameter of a head of the bolt or a member, attached to the bolt, contacting the lever surface, and

M is a holding moment.

Fig. 2 shows a portion of an antenna fixing system 1 according to the invention. The antenna fixing system 1 comprises a twistable lever arrangement 2 of at least a first lever 3 and a sec- ond lever 4 connected by a joint 5 for adjusting a tilting angle controlled by the two levers 3, 4. The joint 5 comprises the joint axis A. The lever arrangement 2 is exemplarily attached to a fixture device 30 (e.g. an antenna pole 30) by means of a bracket 31 comprising a fixing device 32 for fixing the lever arrangement 2. The lever arrangement 2 is exemplarily connected to an antenna 33. The joint 5 further optionally comprises a scale 20 around the joint axis A configured to enable information about a set antenna tilting angle.

As shown in Fig. 3, the joint 5 comprises a set of a first shell 6 comprising a first predetermined circular embossed elevation 7 in direction of a joint axis A and being connected to the first lever 3 (Fig. 2) rotata ble around the joint axis A and a second shell 8 comprising a second predetermined circular em bossed elevation 9 in direction of the joint axis A and being connected to the second lever 4 (Fig. 2) rotata ble around the joint axis A. The first elevation 7 and the second elevation 8 correspond to one another in a predetermined contacting diameter range around the joint axis A. The first and second shells 6, 8 are arranged in a staggered manner such that the shells 6, 8 are in a surface contact at least in the contacting diameter range. A straight line L, intersecting the joint axis A and tangentially touching the elevation 8, 9 or lying in the elevation 8, 9 in the predetermined contacting diameter range, and a line L' radially extending from the joint axis A enclose a predetermined angle Θ. Furthermore, the joint 5 comprises a clamping device 10 comprising at least a bolt 11 configured to exert a clamping force to the set in direction of the joint axis A. In the em bodiment, the predetermined angle Θ is in a range of 40 to 80 degrees.

A surface of one of the shells 6, 8 facing another shell of the set comprises a slide-blocking su rface 21 in the predetermined contacting diameter range. The sl ide-blocking surface 21 is e.g. made by hot-galvanizing or electroplating.

Referring to Fig. 3, in a statics analysis, for this configuration, equ ation (2) results: μ · Fv' · cos Θ · SI + μ · Fv' · S2 = M ... (2) wherein : μ is a static friction coefficient,

Fv' is a bolt pre-tighten ing force,

Θ is an included angle,

SI' is a lever arm of the friction force between the predetermined circular em bossed elevations 7, 9,

S2' is a lever arm of the friction force at the center bolt 11, the lever arm being related to a diameter of a hole 12 and a diameter of a bushing 13, around the bolt 11, exerting the clamping force to the elevation 7, and

M is a holding moment.

By com bining equation (1) and equation (2), relation (3) results:

Fv' SI + S2

... (3)

Fv SI · cos Q + S2' According to the relation, it can be concluded that by increasing the diameter of the predetermined circular embossed elevations, increasing the pre-tightening force Fv', and adjusting the angle Θ, the same resu lt can be achieved with one bold as by providing the three bolts 1100 as in the conventional solutions.

Fig. 4 shows an exploded view of the set of shells 6, 8, of a further set of shells 6', 8' and of the clamping device 10 of the antenna fixing system 1.

The shells 6, 8 comprise the predetermined circular embossed elevations 7, 9 and the shells 6', 8' comprise the predetermined embossed elevations 7', 9'. The antenna fixing system 1 comprises the further set, wherein the clamping device 10 is configured to exert the clamping force to both of the sets. The sets are oriented such that the elevations of the shells are facing each other.

The clamping device comprises the bolt 11 and, optionally, the bushing 13, a washer 14, and a nut 15. Furthermore, the clamping device 10 comprises a sleeve 16 around the bolt 11. The sleeve 16, by having a length adapted to provide a spacer located between the elevations 9, 9' and contacting the elevations 9, 9', is configured such that the two sets can be clamped by one clamping device 10.

In Fig. 4, the clamping device 10 comprises a threaded bolt 10 and the optional nut 15.

Fig. 5 is the exploded view of Fig. 4 depicting a modification of the clamping device 10. The clamping device 10 is provided with a nut 15 comprising a hand wheel 17.

Fig. 6 is the exploded view of Fig. 4 depicting a further modification of the clamping device 10. Here, the clamping device 10 is provided with a quick release skewer 18.

Fig. 7 shows a front view of the portion of an antenna fixing system 1 illustrated with a variety of modifications of the elevations 7, 9, 7', 9', 7", 9", 7'", 9'" of the shells 6, 8, 6', 8'. The elevations 7, 9, 7', 9' facing each other as already shown in Fig. 4 are depicted. In a modification, the elevations 7", 9" and 7"', 9"' of the shells 6', 8' are averted from each other.

In a further modification, at least one of the elevations 7, 9, 7', 9', 7", 9", 7"', 9"' of the set is provided with a bead 19 directed away from another of the elevation. In another further modification, each of the elevations 7, 9, T, 9', 7", 9", 7"', 9"' of the set is provided with the bead.

In use, for adjusting the antenna tilting angle, the only one nut, optionally by the hand wheel, or the only one quick release skewer is loosed . Subsequently, the antenna tilting angle is ad- justed, which is optionally performed by means of the scale 20 around the joint axis A. Finally, the only one nut or quick release skewer is retightened .

Although the present invention has been described with reference to specific features and embodiments thereof, it is evident that various modifications and combinations can be made thereto without departing from the spirit and scope of the invention. The specification and drawings are, accordingly, to be regarded simply as an illustration of the invention as defined by the appended claims, and are contemplated to cover any and all modifications, variations combinations or equivalents that fall within the scope of the present invention.