WO1999060333A1

WO1999060333A1 - Device for measuring a tilt angle, and an antenna means including a tilt angle measuring device

Info

Publication number: WO1999060333A1
Application number: PCT/SE1999/000832
Authority: WO
Inventors: Tord Liljevik
Original assignee: Allgon Ab
Priority date: 1998-05-15
Filing date: 1999-05-14
Publication date: 1999-11-25
Also published as: SE9801727L; SE9801727D0; SE512078C2; AU4405299A

Abstract

An inclinometer (4) for measuring the tilt angle of a directional antenna (1), comprising a base body (41) having means adapted for fastening the base body to the antenna (1), and a transparent tube (51), having a curved shape. The tube (51) is fixed to the base body (41) so that in use the tube (51) extends essentially in a tilt angle adjustment plane of the antenna (1). An indicator body (52) is accommodated in the tube (51), and takes under influence of gravity force a position in the tube (51) depending on the tilt angle. A scale means (45) is provided for the reading of the position of the indicator body. An antenna provided with an inclinometer is also disclosed.

Description

DEVICE FOR MEASURING A TILT ANGLE, AND AN ANTENNA MEANS INCLUDING A TILT ANGLE MEASURING DEVICE.

FIELD AND BACKGROUND OF THE INVENTION The invention relates to an inclinometer, especially an inclinometer for measuring the tilt angle of a directional antenna, and a directional antenna means provided with an inclinometer .

Directional antennas, e.g. antennas in cellular telephone systems, e.g. base station antennas, are often mounted in high locations, in order to cover a large area. Such location could for example be on a mast, tower, pole or building. When the antenna is located high above the units with which it communicates, the antenna must be tilted, so that a tilt angle is provided between the longitudinal axis of the antenna and the vertical line in order to cover the area close to the antenna. Usually a tilt angle in the range 0-45° is selected. In extreme cases, e.g. in areas with very high call intensity, where the antennas are located close to each other, tilt angles in the range 45-90° can be selected. This results in small cells.

When directional antennas are mounted, the tilt angle is adjusted to a predefined, calculated value, specific for each antenna, depending on its location. This can be made by adjusting the angle at a pivot joint between two links, whereof one is fastened to a supporting structure, and the other is fastened to a top portion of the antenna, whereas the bottom portion of the antenna is fastened with a pivot joint to the supporting structure. The pivot joint between the arms is then provided with a scale for reading an angle. Alternatively, when the links are replaced by two grooved plates which are pressed together by means of screws, and the hole for the respective screw in one of the plates is elongate in order to provide for possibility of adjustment, an angle indicating scale can be arranged on one side of the elongate hole .

Such methods of adjusting the tilt angle have several drawbacks. The scales are usually impossible to read from more than one direction. Further, the angle read on the scale has to be translated, depending on the height of the antenna, the point on the supporting structure where the link is fastened, and the length of the links.

RELATED ART

US-A-2, 411, 165 discloses a clinometer including a body provided with a curved slot in which one or two balls are confined. The slot is covered with a transparent cover plate provided with a scale for reading the position of the ball. The reading of an angle can thus be done only from one direction. The disclosed means for mounting the clinometer is a rotable joint. In order to achieve a reliable result when reading an angle by means of such a clinometer, it has to be checked that the clinometer has been swung to its correct position. Since a rotable joint is used, dust, dirt and other foreign matter, as well as wear of the joint affects the possibility to achieve the correct position.

US-A-2, 384, 453 discloses an inclinometer comprising a tube of a translucent material, and a ball enclosed in the tube. Graduations are associated with the tube, and the tube is supported at its ends by brackets connected with a base. SUMMARY OF THE INVENTION

A main object of the invention is to provide an inclinometer which is adapted for measuring the tilt angle of a directional antenna, and which is simple to attach, simple to read from different directions, and which gives an angle value without the need of translation.

It is also an object of the invention to provide an inclinometer which is adapted for measuring the tilt angle of a directional antenna, which gives accurate measurement values, and is simple in its design and is suited for manufacturing cost-effectively in large quantities.

These objects are attained by an inclinometer according to the appended claims .

Through the arrangement of a transparent second tube, having a curved form, on the base body so that it in use extends in a plane essentially perpendicular to a tilt angle adjustment plane of the antenna, and by accommodating a second indicator body in the second tube, it is achieved an inclinometer, with which an angle of inclination in a plane perpendicular to a tilt angle adjustment plane of the antenna also can be measured. This is especially advantageous when the antenna is to be mounted on a wall, since it then can be mounted vertically, before the tilt angle adjustment, so that the tilt angle adjustment plane will be vertical.

Through the arrangement of a fastening means including a planar surface, and arranging the tube so that it extends in a direction essentially perpendicular to said surface, it is achieved an inclinometer which is simple to attach in a correct position.

By the feature that the tube(s) is (are) filled with a liquid it is achieved a damping of the movements of the respective indicator body and a prevention of moisture from entering the tube(s), which could cause problems at temperatures below 0° C

Through the arrangement of a guide surface being essentially perpendicular to the planar surface of the fastening means it is achieved an inclinometer which is simple to attach in a correct vertical position.

By the features that a radius of curvature is greater for a portion of the first and/or the second tube than for other portion (s) of the tube(s), it is achieved an increased resolution of angle indication at the portion having the greater radius of curvature.

Through the arrangement of the base body so that a part of it extends in parallel with the tilt angle adjustment plane for at least a portion of the length of the tube, and that said part of the base body supports the first tube it is achieved a stable and robust inclinometer.

Through the arrangement of the base body so that a part of it extends in parallel with the second tube for at least a portion of the length of the tube, and that said part of the base body supports the second tube it is achieved a stable and robust inclinometer which can be used for measuring two angles . Through the arrangement of the scale means for the reading of the position of the respective indicator body on the respective tube it is achieved an inclinometer which is simple to read from different directions.

It is also an object of the invention to provide an antenna means which is simple to mount in a correct tilt angle.

These objects are attained by an antenna means according to the appended claims 16 and 17.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a diagrammatic view of a directional antenna with a tilt mechanism having means for measuring the tilt angle according to prior art.

Figure 2 is an enlarged view of the tilt angle measuring means in Figure 1.

Figure 3 is diagrammatic view of a second type of tilt mechanism having means for measuring the tilt angle according to prior art.

Figure 4 is diagrammatic view of a directional antenna, with a tilt mechanism, having an inclinometer for measuring the tilt angle according to the invention.

Figure 5 is a diagrammatic view of a first embodiment of an inclinometer for measuring the tilt angle of a directional antenna according to the invention. Figure 6 is a diagrammatic view of a second embodiment of an inclinometer for measuring the tilt angle of a directional antenna according to the invention.

Figure 7 is a diagrammatic view from the back of an inclinometer for measuring the tilt angle of a directional antenna according to the invention.

Figure 8 is partial view of a directional antenna, with a tilt mechanism, having an inclinometer for measuring the tilt angle according to the invention.

Figure 9 is a diagrammatic view of a further embodiment of an inclinometer for measuring the tilt angle of a directional antenna according to the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

With reference to fig 1, a directional antenna 1 mounted on a pole or mast 2 is shown. Actually it is the support or the housing of the antenna which is seen. Inside the housing, the radiating elements with feeding means are arranged. In its bottom the directional antenna 1 is mounted by means of a bracket 22 and a pivot joint 14. The top of the directional antenna 1 is mounted by means of a bracket 21, a pivot joint 23, a tilt mechanism 3 and a pivot joint 12. The tilt mechanism 3 is provided with a tilt angle indicating means 30, commonly used today when adjusting the tilt angle.

In Figure 2, which is an enlarged view of a part of the tilt mechanism 3, the tilt angle indicating means 30 is shown in detail. The two links 31, 32 of the tilt mechanism 3 are joined in a pivot joint by means of a screw 33. To read the angle of the pivot joint, a scale 34 on link 32 is read on a reference mark 35 on link 31. To achieve the tilt angle value, the so read value has to be translated by means of a table, since the tilt angle also depends on the size (height) of the directional antenna 1 and on the lengths of the links.

By tilt angle is meant, in connection with this invention, the angle α between the longitudinal axis 10 of the directional antenna 1 and a vertical line 11. A tilt angle adjustment plane refers to a plane through the longitudinal axis 10 of the directional antenna 1 and a vertical line 11, or a plane parallel thereto.

A second tilt mechanism 3 frequently used is shown in Figure 3. This tilt mechanism 3 includes two plates with transverse grooves. The plates are pressed together, with the grooved surfaces facing each other, by means of screws. The hole for the respective screw in one of the plates is elongate, whereas the hole in the other plate is circular, in order to provide for possibility of adjustment. To enable the reading of a value indicating the tilt angle, a scale is arranged on one side of the elongate hole. The scale is read at the position of the screw. Even in this case the read value has to be translated with respect to the antenna size (height) by means of a table, in order to obtain the value of the tilt angle.

In Figure 4 a directional antenna 1 mounted on a pole or mast 2, and provided with an inclinometer 4 according the invention, is shown. By means of this inclinometer the correct tilt angle can be read directly, without any translation of read values. Figure 5 shows a first embodiment of an inclinometer 4 for measuring the tilt angle of a directional antenna according to the invention. The inclinometer 4 includes a base body 41 adapted for fastening to the antenna. The base body 41 is preferably made of a polymer material, and has a surface 42 adapted to the surface 13 of the antenna 1 on which it is to be mounted. The surface 42 is preferably planar, and an adhesive e.g. a double-sided adhesive tape or other suitable means can be applied on the surface, for the attachment of the inclinometer 4 to the antenna 1. The base body can, as an alternative or addition, be provided with holes 44, and the inclinometer 4 can then be attached to the antenna 1 by means of screws, rivets or the like.

A transparent tube 51 is fixedly attached, by means of for example an adhesive or fusing, to the base body 41, possibly supported by a part 43 of the base body 42. The tube preferably has a circular cross section, and as seen in the figure, the tube 51 is curved and encloses an indicator body 52 in the form of a rolling body (ball) 52. Due to gravity force and the curve of the tube 51 the ball 52 takes a position in the tube 51 depending on the orientation of the tube 51. The tube 51 should be attached to the base body 41 so that when the inclinometer 4 is mounted on the antenna 1, the tube extends in a tilt angle adjustment plane of the antenna. On the part 43 of the base body angle indicating marks 45 are arranged to enable the reading of the position of the ball 52. If the marks are graded in degrees the actual tilt angle can be read directly, without any translation.

A second curved transparent tube 53 can be arranged in a plane essentially perpendicular to the tilt angle adjustment plane in order to enable measurement of an inclination angle in a vertical plane essentially perpendicular to the tilt angle adjustment plane. The second tube preferably has a circular cross section, and accommodates a second indicator body 54 in the form of a rolling body (ball) 54. The operation of the second tube and the second ball are analogous to that of the first body and the first ball. A scale 46 is arranged on the base body for the reading of the position of the ball 54. The second tube 52 is fixedly attached, by means of for example an adhesive or fusing, to the base body 41, and possibly to the first tube 51.

The arrangement of the second tube is especially advantageous when the antenna is to be mounted on a wall, since the antenna can be mounted vertically, before the tilt angle adjustment, so that the tilt angle adjustment plane will be vertical. Also when the antenna is to be mounted on a pole or a post, the second tube with its indicator body can be used to adjust the pole or post in a vertical position.

The transparent tubes 51, 53 are made of a transparent material e.g. a polymer or glass. The rolling bodies (balls) are preferably made of glass or metal, e.g. steel. It is to prefer that the rolling bodies (balls) have a colour diverging form the surroundings, in order to facilitate the reading of the ball position. The balls are for example made dark, preferably black. When the tubes are fixed to each other there should be no connections between the interiors of the tubes. Each tube is preferably sealed and filled with a liquid having a density being lower than that of the indicator body, e.g. an oil or spirit. This will dampen the movement of the balls, and prevents moisture to enter the tubes, which can affect the movements of the balls, especially at temperatures around and below 0° C. It is important that the clearance between the inner surface of each tube and the respective ball is large enough to allow movements of the balls without to high dampening of the balls. The clearance should preferably be 10- 50 % e.g. 20-40 % of the inner diameter of the tube.

As seen in Figure 5 the angle indication marks are provided on the base body. They can continue on the tubes, and as shown in Figure 6 they can extend over the whole free circumferences of the tubes.

In Figure 7 the back of an inclinometer according to embodiments the invention is shown. In a first embodiment of the invention, the surface 42 is planar and the inclinometer is attached to the antenna 1 on the surface 13 (Figure 4) as described above. However, to facilitate the vertical alignment of the inclinometer, the base body 41 can be provided with a guide surface 47, 48 arranged on a rib or protrusion. It is sufficient with only one of the guide surfaces shown in Figure 7. To use the guide surface 47 the antenna has to be provided with a corresponding recess. The guide surface 48 is used when the inclinometer is to be attached on the side of the of an antenna, i.e. at an edge or corner 12 (Figure 4) of the antenna 1.

Figure 8 shows a further embodiment of the invention, and a way of its mounting. Here, the base body 41 includes a plate and a support 43, in the form of a plate, on which the tubes 51, 53 are attached in a manner similar to what is mentioned above. The plate is provided with holes 44 for its mounting with the screws or bolts 15 used to mount the tilt mechanism 3 on the antenna. This is especially advantageous when the antenna comes with holes for tilt mechanism mounting bolts or screws 15, or with screws or bolts attached 15. The holes 44 are adapted to the positions of the screws or bolts 15 so that the inclinometer will be attached to the antenna in the right position. Preferably the base body 41 is mounted between the fastening plate 36 of the tilt mechanism 3 and the antenna 1. The reference numeral 16 denotes an elastic sealing or bushing. Further parts of the inclinometer 4 are the same as described above.

Figure 9 shows a further embodiment of the invention, where the inclinometer is adapted to protrude over the top of the antenna. In this embodiment, the inclinometer is made of an electrically conductive material. It preferably has a pointed top portion. When the inclinometer is connected with ground it can act as a part of a lightning conductor. This is especially advantageous, since lightning strokes can damage the antenna severely. The inclinometer is connected to ground via the links and the pole or mast, a special conductor, or via conductive parts inside the antenna housing, the bottom fastening means and the post or pole.

Although the invention is described by means of the above examples, naturally, many variations are possible within the scope of the invention. Although it has been described, in connection with the embodiments above, the mounting of an antenna on a pole or mast, the antenna could be mounted on a tower, a building or similar.

Claims

1. An inclinometer for measuring the tilt angle of a directional antenna (1), characterised in that it comprises: a base body (41) having means adapted for fastening the base body (41) to the antenna (1), a transparent first tube (51), having a curved shape, being fixed to the base body (41) so that in use the first tube (51) extends essentially in a tilt angle adjustment plane of the antenna, a first indicator body (52) accommodated in the first tube

(51), which under influence of gravity force takes a position in the first tube (51) depending on the tilt angle, and a first scale means (45) provided for the reading of the position of the first indicator body.

2. An inclinometer according to claim 1, wherein said means for fastening include a surface (42) which is plane, and the first tube (51) extends in a direction essentially perpendicular to said surface (42) .

3. An inclinometer according to claim 1 or 2, wherein a transparent second tube (53) having a curved form is fixed to the base body so that in use it extends in a plane essentially perpendicular to a tilt angle adjustment plane of the antenna, a second indicator body (54) is accommodated in the second tube (53) , which under influence of gravity force takes a position in the second tube (53) depending on an angle of inclination in a plane perpendicular to a tilt angle adjustment plane of the antenna, and a second scale means (46) is provided for the reading of the position of the second indicator body (54).

4. An inclinometer according to any of claims 1-3, wherein each indicator body (52, 54) is a rolling body.

5. An inclinometer according to any of claims 1-4, wherein each tube (51, 53) is filled with a liquid having a density being lower than that of the accommodated indicator body (52, 54).

6. An inclinometer according to any of claims 1-5, wherein a clearance between an inner surface of each tube (51, 53) and the corresponding indicator body (52, 54) is chosen so as to obtain a movement of the indicator body with selected damping.

An inclinometer according to any of claims 1-6, wherein the base body (41) is provided with holes (44) for attachment means selected from a group consisting of screws, bolts and rivets.

An inclinometer according to any of claims 2-5, wherein said means for fastening include at least one guide surface (47, 48) being essentially perpendicular to said plane surface (42) .

9. An inclinometer according to any of claims 1-8, wherein a radius of curvature is greater for a portion of the first (51) and/or the second (53) tube, if present, than for other portion (s) of the tube(s), in order to increase the resolution of angle indication.

10. An inclinometer according to any of claims 1-9, wherein a part of the base body extends in parallel with the tilt angle adjustment plane for at least a portion of the length of the first tube (51), said part of the base body supporting the first tube (51) .

11. An inclinometer according to any of claims 3-10, wherein a part of the base body extends in parallel with the second tube (53) for at least a portion of the length of the tube, said part of the base body supporting the second tube (53) .

12. An inclinometer according to any of claims 1-11, wherein the scale means (45, 46) for the reading of the position of the respective indicator body (52, 54) is arranged on the respective tube (51, 53) .

13. An inclinometer according to any of claims 1-12, wherein the scale means (45, 46) for the reading of the position of the respective indicator body (52, 54) is arranged on the respective part of the base body supporting the respective tube (51, 53) .

14. An inclinometer according to any of claims 1-13, wherein the base body (41) includes a first plate (41) adapted for fastening to the antenna.

15. An inclinometer according to any of claims 1-14, wherein the base body (41) includes a second plate (43) to which the first tube (51) is attached.

16. An inclinometer according to any of claims 1-15, wherein the base body (41) is made of an electrically conductive material, possibly with a pointed portion at the end facing upwards when in use, and adapted to be connected with ground.

17. A directional antenna means characterised in that it is provided with an inclinometer (4) according to any of claims 1-16.

18. A directional antenna means comprising an elongated support means, at least two radiating elements supported by said support means, and feed connection means for feeding said radiating elements, said radiating elements being located in relation to said support means so as to define an angle of tilt and an angle of inclination characterised in that it is provided with an inclinometer (4 according to any of claims 1-16.