GB2333645A

GB2333645A - An antenna located within an artificial tree

Info

Publication number: GB2333645A
Application number: GB9812562A
Authority: GB
Inventors: Ronald Edward Potter
Original assignee: Vodafone Ltd
Current assignee: Vodafone Ltd
Priority date: 1998-06-12
Filing date: 1998-06-12
Publication date: 1999-07-28
Anticipated expiration: 2018-06-12
Also published as: AU3948099A; WO1999066589A1; GB9812562D0; GB2333645B

Abstract

An antenna arrangement comprises an antenna 32 located within a hollow portion 12 of an artificial tree 8.The artificial tree 8 may comprise a hollow steel support column 10 which supports a hollow housing 12 and an omnidirectional antenna 32 located therein. The hollow housing 12 may be formed from glass reinforced plastic material. The steel support column 10 may be bolted to a concrete base 22 which is arranged below ground level. The support column 10 and the hollow housing 12 may be treated to have a tree-bark-like external surface. Artificial branches may be mounted on the top portion of the hollow housing 12 such that they do not interfere with the antenna operation. A base station cabin may be arranged in the centre of an annular embankment and linked to a number of the above antenna arrangements placed around the top of the embankment and may be used in a cellular telephone system.

Description

RADIO SIGNAL TRANSMITTING AND/OR DECEIVING ARRANGEMENTS The invention relates to radio signal transmitting and/or receiving arrangements. Radio signal transmitting and receiving arrangements embodying the invention, and to be described in more detail below by way of example only, are intended to provide base station and antenna arrangements for use with cellular telephone systems and for situation primarily in rural environments, but may be used for other purposes.

According to the invention, there is provided an antenna arrangement comprising an antenna included in a hollow portion of a simulated tree.

According to the invention, there is further provided an antenna arrangement, comprising means simulating a tree in the form of a support portion simulating the lower part of the tree and a hollow upper portion simulating the upper part of the tree and made of non-conducting material enclosing an omni-directional antenna.

According to the invention, there is also provided a radio signal transmitting and/or receiving arrangement, comprising an at least partly circular ground-mounted embankment, at least one simulated tree mounted on the embankment and including a hollow upper portion forming an upper part of the tree and which encloses an antenna, the arrangement including an enclosure for containing circuitry for connection to the antenna and which is embraced and visually obscured by the embankment.

Cellular telephone base stations and antenna arrangements embodying the invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings in which: Figure 1 is a side view of one of the antenna arrangements embodied in a simulated tree; Figure 2 is a diagrammatic enlarged view of part of the simulated tree of Figure 1; Figure 3 is an enlarged view of another part of the simulated tree of Figure 1; Figure 4 is an enlarged view of another part of the simulated tree of Figure 1, with the external surface broken away to show the internal construction; Figure 5 is an enlarged view of another part of the simulated tree of Figure 1; Figure 6 is a side view of another of the arrangements, showing two simulated trees each according to Figure 1, mounted in association with a base station for the cellular telephone system; and Figure 7 is a plan view of the arrangement of Figure 6.

Cellular telephone systems require a number of geographically distributed base stations each having a transmitting and receiving antenna or antennas by means of which radio signals are transmitted to and from mobile cellular telephones temporarily located within the area located by the base station. Such signals include signals to and from the mobile telephone for registering its presence within that particular area and for use in recording that location in a visitor location register or in some other part of the system, signals for authenticating the mobile telephone to enable calls to be made to and from it, signals carrying voice, data or other digital information from the mobile telephone or other such equipment to other telephones (mobile or fixed), and signals carrying voice, data or other digital information from such other telephones to the mobile telephone or other such equipment. When the mobile telephone moves from within the transmitting/receiving area of the antenna of one base station and into the corresponding area of another base station, the mobile is handed over" to the new base station. To provide effective operation of a mobile telephone, it is of course essential that the base stations and their associated antennas be positioned sufficiently close together to provide uninterrupted operation, taking account of the local environment. Particular problems can arise in rural environments. Conventional antenna arrangements may appear visually obtrusive in rural environments, particularly when, for operational reasons, they need to be mounted in high or otherwise prominent positions to provide effective coverage, with the consequent result that objection may be raised by planning authorities or other bodies having regulatory rights in relation to structures to be situated in such environments.

The antenna arrangement shown in Figure 1, and for use in a cellular telephone system, is constructed and designed to have the appearance of a tree 8, a scots pine in this example. It comprises a hollow rigid support column 10, such as made of pressed steel supporting a hollow housing 12 made, for example, of non-electrically conductive material such as glass reinforced plastic (GRP), the junction between the column 10 and the housing 12 being shown at 14. The column 10 may have a height of six metres, for example, and the housing 12 may have a height of 3 metres, for example. The housing 12 supports simulated branches 16, such as made from GRP material and nylon or other suitable materials, as will be described in more detail below.

The column 10 has a rigid plate 18 at its lower end by means of which it is bolted to a concrete base 20 which is situated below the ground level 22 and which thus supports the tree 8. A cover 24, such as made of GRP material and of generally frusto-conical shape can be used to embrace and cover the plate 18 and the fixing bolt and to simulate roots of the tree.

The outside of the column 10 is dressed with resin-based paint or similar material to produce a simulated rough bark effect.

Likewise, the outside of the housing 12 is formed, during the moulding process or afterwards, with suitable surface configurations, again to simulate the bark of the tree.

Figure 2 shows how the GRP housing 12 can be attached to the top of the steel column 10 such as by means of a short hollow tubular insert 26 which is welded to the column 10 and secured to the housing 12 by means of flush set screws 28. However, other suitable fixing means may be used instead.

Figure 3 shows how the steel column 10 may have simulated branch stumps 30, such as made of GRP material, glued to its external surface.

An omni-directional antenna 32 is mounted within the housing 12 as shown in more detail in Figure 4. The antenna 32 is mounted by means of a mounting assembly 34 welded onto the top of the sleeve 26 (see Figure 2). The feeder cable for the antenna 32 is preferably mounted on a wire cable 36 for supporting it and extending down to ground level through the steel column 10 and through hollow ducting shown dotted at 40 in Figure 1.

The wire cable 36 may advantageously be mounted on a pulley 38 and similarly mounted at its lower end, to facilitate assembly and maintenance.

Figure 5 shows, to a larger scale, the construction of one of the branches 16. It comprises a hollow flexible plastic pipe 42, around which is wrapped resin-soaked fabric 44 to simulate a natural branch. Strengthening cords shown at 46, and made of nylon or carbon fibre or other suitable material, may be incorporated for strengthening purposes. The branch may be separately formed and mounted on a cap 48 at the top of the GRP housing 12.

Bristles 50 may be formed from nylon attached to plastic coated wire.

It will be appreciated that the omni-directional antenna 32 is sealed within the hollow interior of the housing 12 and thus protected from weather and ambient conditions. If access is required for maintenance purposes, or during initial installation, the housing 12 may be lifted off the steel column 10, after removing the fixing screws 28 (Figure 2), such as by using a lifting handle 52 (Figure 5). This will of course involve the use of suitable lifting equipment and a ladder or means providing a raised platform. Instead, the steel column 10 may be hingedly attached to the concrete base 20 so that, for maintenance and initial installation purposes, the tree 8 may be laid horizontally on the ground and subsequently raised into its operational position. An inspection hatch 51 may be incorporated in the lower part of the column 10 (see Figure 1).

It is important that the branches 16 be spaced clear of and above the antenna 32, because they might otherwise cause reflections and interference with the correct operation of the antenna, particularly when wet or in icy conditions. Similarly, it is important to avoid the presence of any metal above the column 10, which again could cause interference or reflection.

In this way, an antenna for a cellular telephone system may be mounted in a visually unobtrusive way in a rural environment, the antenna itself being completely enclosed and externally invisible.

The use of an omni-directional antenna 32 is advantageous in that its shape enables it to be incorporated and enclosed in the housing 12. In practice, though, it will be necessary in any particular site to have two such antennas, one for transmitting and one for receiving purposes. Therefore, two such simulated trees, of the form shown in Figure 1, will be needed.

Figure 6 shows an advantageous way in which two such trees 8 and 8A can be mounted on an annularly shaped earth embankment or bund 60. The bund may have a height of two metres, say. The use of the bund is advantageous in that it raises the effective height of each antenna by the height of the bund. In addition, however, the bund provides a hollow interior space 62 in which can be mounted an equipment cabin 64 enclosing the electrical equipment of the base station which is connected to the antennas in the simulated trees 8 and 8A. The cabin 64 is thus externally hidden from view.

Another simulated tree 8B (see Figure 7) can be mounted on the bund as a spare, in case of failure of the antennas in the other two trees 8 and 8A. In addition, natural trees and bushes can be grown on the bund as shown at 66.

As shown in Figure 7, the bund can be of part spiral form with overlapping ends 68 and 70, allowing a passageway 72 for access to the cabin 64 for maintenance purposes. The end portions 68 and 70 can be constructed after the cabin 64 has been installed in position.

Advantageously, the earth of the bund 60 is suitably reinforced to strengthen it and facilitate drainage.

Claims

CLAIMS 1. An antenna arrangement comprising an antenna included in a hollow portion of a simulated tree.
2. An arrangement according to claim 1, in which the antenna is omni-directional.
3. An arrangement according to claim 1 or 2, in which the hollow portion is made of resin material.
4. An arrangement according to claim 3, in which a resin material is glass-reinforced plastics material.
5. An arrangement according to claim 3 or 4, in which the hollow portion is mounted on a rigid metal portion forming the lower part of the simulated tree and through which passes a feeder for the antenna.
6. An arrangement according to claim 5, in which the antenna is an omni-directional antenna.
7. An arrangement according to any preceding claim, in which the two portions are tubular and simulate the trunk of the tree.
8. An antenna arrangement, comprising means simulating a tree in the form of a support portion simulating the lower part of the tree and a hollow upper portion simulating the upper part of the tree and made of non-conducting material enclosing an omnidirectional antenna.
9. An arrangement according to claim 8, in which the lower portion is made of metal and through which a feeder for the antenna passes.
10. An arrangement according to claim 8 or 9, including simulated branches mounted on and extending above the upper portion.
11. An arrangement according to any one of claims 8 to 10, in which the upper portion is made of glass-reinforced plastics material.
12. An arrangement according to any one of claims 8 to 11, in which the simulated tree is mounted on an embankment.
13. An arrangement according to claim 12, in which the embankment is at least partly circular so as to embrace and visibly obscure an enclosure incorporating circuitry for connection to the antenna.
14. A radio signal transmitting and/or receiving arrangement, comprising an at least partly circular ground-mounted embankment, at least one simulated tree mounted on the embankment and including a hollow upper portion forming an upper part of the tree and which encloses an antenna, the arrangement including an enclosure for containing circuitry for connection to the antenna and which is embraced and visually obscured by the embankment.
15. An arrangement according to claim 14, in which the simulated tree comprises a rigid lower portion supporting the hollow upper portion and for receiving feeder cable means for connecting the antenna to the enclosure.
16. An arrangement according to claim 15, in which the rigid lower portion and the hollow upper portion are tubular and together simulate the trunk of the tree and are externally treated to simulate the bark thereof.
17. An arrangement according to claim 16, in which the rigid lower portion is made of metal.
18. An arrangement according to any one of claims 14 to 17, in which the hollow upper portion is made of resin material.
19. An arrangement according to claim 18, in which the resin material is glass-reinforced plastics material.
20. An arrangement according to any one of claims 14 to 19, in which the hollow upper portion supports simulated branches extending upwardly therefrom and away from the aspect of the antenna.
21. An arrangement according to any one of claims 14 to 20, in which the antenna is an omni-directional antenna.
22. An arrangement according to claim 21, including a second said simulated tree on the embankment, the omni-directional antenna in one of the trees being a transmitting antenna and the antenna in the other of the trees being a receiving antenna.
23. An arrangement according to any one of claims 14 to 22, in which the embankment extends completely around the enclosure and the height of the enclosure is not more than the height of the embankment.
24. An arrangement according to claim 23, in which the embankment has two overlapping ends defining an entrance passageway into the space embraced by the embankment for access to the enclosure.
25. An arrangement according to any one of claims 14 to 24, in which the embankment is made of reinforced earth.
26. An arrangement according to any preceding claim, in which the or each antenna is for use with a cellular telephone system.
27. An antenna arrangement, substantially as described with reference to Figure 1 of the accompanying drawings.
28. An antenna arrangement, substantially as described with reference to Figures 1 to 5 of the accompanying drawings.
29. An antenna arrangement, substantially as described, with reference to Figures 6 and 7 of the accompanying drawings.