Antenna system assembly with built-in self-supporting antenna, and corresponding antenna system

FREESTANDING ANTENNA FOR BASE STATION AND ASSEMBLY FOR AN ANTENNA SYSTEM INTEGRATING SUCH ANTENNA.

The invention relates to the field of cellular telephony and more particularly to the base stations of a cellular or mobile telephone network.

A cellular network has a central transceiver at the level of each cell, called a "base station". A base station allows the mobile phone to connect to the network to send and receive communications. The connection between the user's mobile phone and the base station is via a radio link.

A base station conventionally consists of a relay antenna and an electronic cabinet responsible for managing communications.

The relay antenna is mounted on a mast which should be placed on an elevated site to cover as large an area as possible.

Conventionally, an antenna of a base station comprises an outer envelope, commonly called a radome, which is elongated in shape and which delimits a cavity in which a plurality of radiating elements are provided, an energy distribution system between the radiating elements and a reflector device.

The outer casing may be made of a composite material or of ASA or of polycarbonate.

The advantage of composite materials is that they have good mechanical strength. However, they are materials that are not very transparent to radio waves. Conversely, ASA and polycarbonate have limited mechanical strength properties but are transparent to radio waves.

Moreover, whether or not the antenna installation is partially pre-assembled before its installation, its assembly is complex. This is due to the multiplicity of elements to be handled. This complexity which is increased by the sizing of the parts.

Finally, the analysis of antennas on the market shows that manufacturers have successively developed antennas for each technology or particular application. This results in a multiplicity of antennas having very different dimensions and profiles. This considerably limits the modularity of antenna systems as well as their possibility of adaptation, when new antennas have to be installed on an existing mast.

It is understood that, in these antenna systems, the mast is an essential element since it is this which ensures the mechanical resistance of the assembly. Antenna systems must withstand strong winds, such as up to 200 km / h. This is why the diameter of the masts can be greater than 600 mm. The importance of this diameter contributes to the visual bulk of conventional antenna systems.

The installation of an antenna on a mast requires of course the fixing of the latter on a mast, but also its orientation in azimuth. This orientation may be imposed by the structure of the network.

Many solutions have been proposed for securing an antenna to a mast. These fastening systems are sometimes very bulky and require moving the antenna away from the mast to a considerable extent.

In any case, a relatively large distance must be provided between the mast and the antenna in order to be able to orient the antenna in azimuth.

Throughout the present application, the term “mast” will be understood to mean an elongated support, made in particular of metal, intended to be installed so as to extend vertically and to carry telecommunications antennas.

In addition, these are generally three antennas which are fixed on a mast, substantially at 120 ° from each other.

Consequently, the antenna (s) of a base station are bulky and environmental standards impose increasing constraints on their installation.

Camouflage systems have thus been developed intended to at least partially cover the antenna. However, these systems are extremely fragile and have a relatively short lifespan, given the climatic constraints undergone. They are also ineffective in preserving the environment.

This is why it has been proposed antenna systems integrating the three antennas in a single housing of substantially cylindrical shape.

Thus, document EP-1 606 855 describes an antenna system comprising an upper active part with the antennas and a lower service part.

In the upper part, the antennas and the carrier core are placed in a casing or radome of cylindrical shape.

Such a system makes it possible to give a cylindrical shape to the antenna system and therefore to limit its visual impact on the environment.

However, the azimuth adjustment of each antenna, as well as their maintenance, prove to be extremely difficult, if not impossible, due to the presence of this external housing.

Moreover, this case constitutes an additional part which only fulfills an aesthetic function. Thus, such an antenna system has a much higher cost price than that of the elements which compose it.

In addition, such a housing can interfere with the operation of the antennas.

Finally, such an antenna system must be pre-assembled before being put in place, for example on a building roof. However, such a system is bulky and cumbersome to handle, which makes its installation extremely complex, especially in an urban environment.

The object of the invention is therefore to overcome the drawbacks of the state of the art by proposing an antenna which is designed to simplify its installation, even offering the possibility of eliminating the presence of the support mast, and, in all cases , by allowing an antenna system comprising one or more antennas according to the invention to limit visual nuisance in the environment, thanks to its compactness. In addition, this antenna allows the successive installation, on existing base stations, of new antennas intended for different technologies.

Thus, the invention relates to an antenna for a base station of a cellular telephone network, comprising an outer envelope of determined height, delimiting a cavity closed by two end walls, and in which is provided a reflector device associated with. radiating elements.

According to the invention, the outer casing further comprises stiffening means, such that the antenna is self-supporting.

This particular structure of the antenna makes it possible to lighten the structure of the mast to which it is fixed, or even to eliminate it completely.

The antenna system according to the invention will therefore be extremely simplified compared to conventional systems.

Preferably, the stiffening means are mechanically independent of the reflector device.

In conventional antenna systems, the means for connecting to the mast are generally connected to the reflector and not to the external envelope of the antenna. This is due to the fact that the reflector is conventionally made of aluminum and has greater mechanical strength than the casing itself. This type of fixing makes it possible to use the mechanical resistance of the reflector. However, it has a major drawback which is the absence of separation between the electrical and mechanical functions. However, significant differences in expansion can occur, during use, between the reflector and the mast on which the antenna is fixed. This causes significant stresses on the reflector, stresses which can affect the electrical function of the reflector and therefore the reliability of the antenna itself.

These drawbacks are avoided when the stiffening means are mechanically independent of the reflector device.

In addition, in conventional antenna systems, the reflector is generally given a greater weight than that strictly necessary for its electrical function. This of course has consequences on the overall weight of the antenna and on its manufacturing cost.

With the antenna according to the invention, the reflector device can be considerably lightened and the stiffening means do not add excess weight to the antenna.

Finally, when the reflector device does not have to perform a mechanical function, its design is not limited by constraints linked to a high level of mechanical resistance.

These stiffening means can be integrated into the casing or attached to it.

Preferably, they extend over substantially the entire height of the antenna.

The invention also relates to an assembly for producing an antenna system intended for a base station, this assembly comprising:

an antenna as defined above, a mast, and means for connecting the antenna to the mast, these means being designed to bear both on the end walls of the antenna and on the mast, so as to tighten the antenna.

Thus, such an assembly makes it possible to mount the antenna on a mast of simplified structure, insofar as the antenna itself is self-supporting. In addition, the connection means do not lead to an increase in the bulk generated by the antenna and the mast themselves.

In fact, they are not placed between the antenna and the mast, as in the antenna systems according to the state of the art, these connecting means leading to a separation of the antenna and the mast.

Thus, an antenna system produced from such an assembly is compact compared to a conventional antenna system and therefore reduces visual nuisance on the environment.

The mast may have a shape complementary to that of the antenna, so that after connection between the antenna and the mast, the latter have a compact outer shape.

This embodiment makes it possible to further reduce the visual disturbances of an antenna system made from this assembly.

Also with this objective in mind, the antenna and the mast are designed to present, once linked, an exterior shape that is substantially continuous and rounded.

The invention also relates to an assembly intended for obtaining an antenna system for a base station, said assembly comprising at least two antennas as defined above and connection means designed to be supported on the walls of the base station. end of each antenna, so as to enclose said at least two antennas and ensure their connection.

This assembly makes it possible to obtain an antenna system radically different from those known in the state of the art, since it does not require any mast.

The elimination of such a mast is allowed, because each antenna has stiffening means which make it self-supporting.

An antenna system produced from such an assembly is therefore particularly compact and its impact on the environment is reduced compared to conventional antenna systems.

The shape of the antennas can also be chosen so that they, once assembled, have a continuous and rounded outer shape.

Preferably, the connection means are substantially planar.

Preferably, the connection means are designed to allow the orientation in azimuth of each antenna.

In certain cases, and in particular when the antenna system must be placed in a geographical area exposed to strong winds, the assembly according to the invention can also include a mast, the connection means then also being designed to be fixed on said mast.

When an assembly according to the invention comprises a mast which is part of an already existing installation, the connecting means are segmented.

The invention also relates to an assembly for an antenna system intended for a base station further comprising at least one section, intended to be mounted between two antennas.

Preferably, the height of this profile corresponds substantially to that of the antennas.

This profile can have, after assembly of the assembly, two different functions.

This section can first of all have a stiffening function and it is particularly useful when groups of complementary antennas have to be added above an already existing group of antennas.

In this case, the structure of the profile is designed so that it can perform this stiffening function.

Such a profile inserted between two antennas may also have the function of giving the assembly formed by the antennas and the profile a substantially continuous and rounded outer shape. In this case, the profile does not need to have significant mechanical strength. It has the effect of reducing the visual nuisance of the antenna system obtained.

The invention also relates to an antenna system for a base station of a telephone network, comprising at least one antenna as defined above.

This system can comprise at least two antennas according to the invention, intended for different networks, said at least two antennas being placed at different heights in said system and each antenna being fixed by connecting means bearing at least on the walls. end of said antenna, so as to grip it.

These networks can be of the WIMAX, GSM, UMTS or PMR type for example.

This antenna system may include a mast.

In a conventional embodiment, the antenna installation comprises at least two groups of three antennas, placed at different heights of the system.

Preferably, this antenna system comprises at least one section between two antennas intended for the same network.

The invention will be better understood and other aims, advantages and characteristics thereof will emerge more clearly on reading the description which follows and which is given in relation to the appended drawings which represent examples of embodiments of the invention and on which ones :

Figure 1 is a schematic sectional view of an antenna according to the invention, Figure 2 is a side view of an antenna according to the invention being mounted on a mast, Figure 3 is a sectional view according to line III-III of FIG. 2, FIG. 4 is a view similar to FIG. 3 which illustrates two extreme positions of the antenna during its orientation in azimuth, FIG. 5 illustrates a variant of the mast shown in FIGS. 2 to 4, with a detail A, FIG. 6 shows a system of two antennas according to the invention assembled without a mast and associated with two profiles, FIG. 7 illustrates, in cross section, a system of three antennas according to the invention, FIG. 8 represents an antenna system comprising three groups of antennas, intended for different networks and produced from an antenna according to the invention, FIG. 9 is a perspective view of a detail of FIG. 8, Figure 10 is a cross section of an antenna system comprising profiles, Figure 11 is a perspective view of Figure 12, and Figure 12 is an alternative embodiment of Figure 7.

For reasons of simplification, the elements common to the various figures will be designated by the same references.

With reference first of all to FIG. 1, the antenna 1 according to the invention comprises an outer casing 10 or radome which delimits a cavity 11 which is closed by two end walls 12 (shown in FIG. 2).

Inside this cavity, there is provided a reflector device 13, for radiating elements not shown in FIG. 1. The reflector device can consist of a single reflector or of a plurality of reflectors. In the cavity 11, there are also provided stiffening means 14.

In the example illustrated in FIG. 1, these stiffening means are attached to the outer casing 10 of the antenna. They could also be designed to be directly integrated into the outer casing.

In the example illustrated in FIG. 1, the stiffening means are designed to be able to come into contact with at least part of the internal wall 100 of the casing. They have two symmetrical elements which are arranged on either side of the axis of symmetry XX 'of the antenna. The stiffening means are here connected together by end plates (not shown) and are not limited to this exemplary embodiment.

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The length of the stiffening means can correspond to the height of the antenna, so as to be the most effective.

The reflector device 13 is fixed in the cavity 11, by means of fixing means on the stiffening means 14. This fixing can in particular be carried out by gluing. This allows slight relative movements between the reflector and the stiffening means. Such movements may in particular be due to differences in expansion between the various elements forming the antenna 1.

The mounting of the antenna illustrated in Figure 1 will now be described with reference to Figures 2 and 3.

These figures show the antenna 1, a mast 2 and means 3 for connecting the antenna to the mast.

These connecting means 3 comprise two elements 3a and 3b. Each of them has a substantially planar part

30, here in the form of wings or an open V, and legs 31 each extending a branch of the V, in a plane substantially perpendicular to part 30.

In each branch of the V, an opening 32 is provided.

These two tabs surround a zone 33 corresponding to the base of the V and which is intended to come into contact with the mast, as illustrated in FIG. 3.

Element 3a is symmetrical with respect to an axis ZZ 'passing through the center of wall 32.

Each element 3a or 3b is mounted on the mast 2 by any suitable means, in particular by means of a collar.

The mounting of the antenna 1 on the mast 2 is carried out as follows.

The element 3a is first of all fixed on the mast 2.

The antenna is fitted on each of its end walls

12, two projecting threaded elements 15, one of them being illustrated in FIG. 2.

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The two elements 15, located on the wall 12 which will be the lower wall of the antenna once mounted, are then introduced into the two openings 32 of the element 3a.

When the antenna is in a vertical position, substantially parallel to the mast 2, retaining means 17, such as nuts, are screwed onto the elements 15 to ensure their retention in the openings 32. As will be seen later, this retention n 'not impede the sliding movement of the elements 15 in the openings 32 of oblong shape.

Finally, the connecting element 3b is positioned above the antenna 1, as illustrated in FIG. 3. It is then made to slide along the mast, in the direction illustrated by the arrow F until the elements 15, placed on the wall 12 in the upper position after mounting the antenna, are inserted into the openings 32 of the connecting element 3b.

As before, retaining means 17 are then placed on the elements 15 to hold them in the openings 32 while allowing them to slide inside these openings.

Of course, the attachment of the connecting elements to the end walls of the antenna could be ensured anywhere other suitable means.

FIG. 4 illustrates two extreme positions of the antenna 1, relative to the mast 2.

These two extreme positions are defined with respect to the median position illustrated in FIG. 3, in which the axis of symmetry XX 'of the antenna coincides with the axis of symmetry ZZ' of the connecting element 3a.

In position A, the antenna is tilted to the left with respect to the plane of the figure, so that its axis of symmetry XX 'forms an angle a with the axis of symmetry ZZ' of the element 3a. In this position, the element 17 located on the left of the figure is in abutment against the bottom 320 of the corresponding opening 32, while the element 17 located on the right part of the figure is in abutment against the bottom 321 the opening 32 located on the right part of the figure.

Conversely, when the antenna is in position B, the element 17 located on the left part of FIG. 4 is located in abutment against the bottom 321 of the opening 32 on the left part, while the element 17 located on the right part of FIG. 4 is in abutment against the bottom 320 of the corresponding opening 32.

In this position B, the axis of symmetry XX 'of the antenna 1 also forms an angle a with the axis of symmetry ZZ' of the element 3a.

Of course, the antenna 1 can take all the intermediate positions between the positions A and B illustrated in FIG. 4. Moreover, what has just been described for the element 3a and the antenna 1 is directly transposable to the movement. relative of antenna 1 of element 3b.

It is therefore understood that the openings 32 and the sliding mounting of the antenna 1 in the openings 32 allow the azimuth adjustment of the antenna 1.

This adjustment is carried out very simply and without having to move the antenna away from the mast 2.

Reference is now made to FIG. 5 which illustrates an alternative embodiment of the antenna illustrated in FIG. 3.

FIG. 5 is a top view of an antenna 1, mounted on a mast 20, by means of connection means, an element 4b of which is illustrated in FIG. 5.

The mast 20 differs from the mast 2 illustrated in FIG. 3 in that it has not a cylindrical section but a semi-spherical section.

In the exemplary embodiment illustrated in FIG. 5, the mast 20 comprises an outer casing 200 delimiting a cavity 201.

In the casing 200, on the wall 202 intended to be placed opposite the antenna 1, grooves are formed, here four in number.

FIG. 5 shows that, thanks to this particular profile of the mast 20, after mounting the antenna and the mast, the latter have a shape that is not only compact but also substantially continuous and rounded. This helps to limit the visual impact of the antenna and the mast on the environment.

The connecting means associated with the antenna 1 and with the mast 20 differ from those illustrated in FIG. 3 in that they carry nuts 204 intended to be able to be inserted into the grooves 203. These nuts are, for example, pressure nuts. or quarter turn nuts.

FIG. 6 illustrates two antennas 1 assembled by means of connection means according to the invention.

FIG. 6 is therefore a view similar to FIG. 5 which shows, seen from above, two antennas 1 according to the invention which are arranged so that their bottoms 16 are placed opposite.

The two antennas 1 are mounted together by means of connection means, an element 5b of which is illustrated in FIG. 6.

The connecting element 5b is supported on two end walls 12 of the antennas 1. The element 5b is located at the top of the antennas mounted and installed on a base station. The element which is symmetrically arranged on the lower end walls of the two antennas 1 is not visible in FIG. 6.

The element 5b is substantially planar and has, in this exemplary embodiment, two axes of symmetry Υ-ιΥ-i 'and Y2Y2' After assembly of the antennas and the connecting element 5b and in the middle position of the antennas, the 'axis of symmetry Y1Y1' of the element 5b coincides with the axis of symmetry XX 'of the antennas, while the axis of symmetry Y2Y2' of the connecting element 5b constitutes an axis of symmetry between the two antennas 1.

The connecting element 5b has a generally rectangular shape, comprising four openings 52 of oblong shape. The openings are symmetrical two by two with respect to the axes Y ^ - and Y2Y2 '· In these openings, can be placed the retaining elements 17 for the protruding elements 15 of each antenna.

As explained previously with reference to FIGS. 3 and 4, the cooperation between the retaining means 17 and the openings 52 allows the adjustment of the azimuth orientation of each antenna 1. This adjustment is carried out for each antenna independently.

Of course, after adjustment of the orientation in azimuth, the axis of symmetry of each antenna can no longer coincide with the axis of symmetry Y1Y1 '.

In the embodiment illustrated in FIG. 6, the system with two antennas according to the invention also comprises two sections 50. Each section has an elongated shape and their height preferably corresponds substantially to that of the two antennas, so as to be able to extend between the connecting means.

Of course, the shape of these sections 50 is chosen so as to be able to be inserted between the two antennas, without hindering their movement during the adjustment of their orientation in azimuth.

As shown in Figure 6, the wall 500, which constitutes the outer wall of the profiles 50 after insertion between the two antennas, has a rounded shape. Thus, thanks to these sections 50, the system with two antennas according to the invention has a substantially continuous and rounded outer shape. Consequently, these profiles 50 again make it possible to reduce the visual impact in the environment of the antenna system according to the invention.

The example illustrated in FIG. 6 shows that the antenna according to the invention makes it possible to produce a system of two antennas without a mast being necessary. This is made possible by the presence of stiffening means provided in the antenna itself, stiffening means which make it self-supporting.

Reference is now made to FIG. 7 which illustrates a system of three antennas 1 according to the invention.

The three antennas 1 are placed substantially at 120 ° to each other and clamped between connecting means which bear on their end faces 12.

Each element 6a, 6b of the connecting means has a substantially planar shape and comprises three branches 60, 61 and 62 substantially at 120 ° from each other. On each branch 60, 61 and 62, two vis-à-vis openings 600, 610 and 620 are provided. As described previously with regard to FIG. 3, these openings have an oblong shape corresponding to that of the antenna 1, so as to allow the antennas to be adjusted in azimuth.

Furthermore, each element of the connecting means comprises a central opening 6 intended in particular for the passage of cables.

The three antennas 1 are mounted in such a way that an antenna is connected between two branches of the fixing element 6b.

The connection between an antenna and the element 6b is made by means of projecting elements 15 carried by each antenna, openings provided in each branch of the connecting element and retaining means 17, similar to those which have been illustrated. previously.

Of course, the mounting of the antennas 1 on the connecting element 6a is carried out in the same way as for the element 6b.

Thus, the system of three antennas according to the invention comprises only three antennas and connection means for their assembly, the strength of the system being ensured by the stiffening means provided in each antenna.

Figure 7 illustrates how the antennas can be adjusted in azimuth independently of each other.

Thus, FIG. 7 illustrates three half-lines a1, a, 2, a3 each corresponding to an axis of symmetry between two branches of the connecting element 6b. Thus, the half-lines α1, a2, respectively a3 are the axes of symmetry of the branches 60 and 61, 60 and 62, respectively 61 and 62 of the fixing element 6b.

FIG. 7 shows that the azimuth adjustment of one of the antennas 1 leads to positioning it so that its axis of symmetry coincides with the half-line a.2.

The orientation of the other two antennas leads to their axis of symmetry being shifted by an angle a with respect to the axes of symmetry a1, respectively a3.

Of course, FIG. 7 is only an example of the relative positioning of the three antennas resulting from their orientation in azimuth. Other relative positions of the antennas of the system illustrated in FIG. 7 can be envisaged, depending on the environment in which the antenna system is installed.

In a variant of the embodiment illustrated in FIG. 7, a mast could be provided.

Reference is now made to FIGS. 8 and 9 which illustrate another antenna system according to the invention.

As shown in FIG. 8, this antenna system comprises three groups 80, 81 and 82. In this example, all the antennas are antennas according to the invention. They are therefore self-supporting and the illustrated antenna system has no mast.

Reference 84 designates a service box disposed at the lower part of the antenna system. This box 84 is used both for placing cables, for example, and for raising the antenna system, if this proves to be necessary in view of the environment in which it is placed.

This antenna system has different antenna groups, each of them dedicated to a particular technology.

FIG. 8 shows that an antenna system according to the invention is upgradeable and that it can be modified over time to add an additional antenna group.

Figure 9 is a perspective view which shows the region between the two groups of antennas 80 and 81 shown in Figure 8.

The assembly of the antennas illustrated in FIG. 8 is carried out as follows. First of all, the group of antennas 80 is assembled using the connecting means 80a and 80b, as has been described above, in particular with regard to FIG. 7. In the embodiment illustrated in FIGS. 8 and 9, the connecting elements are in the form of a disc and include openings 800 allowing the azimuth adjustment of the antennas, independently of one another.

When the base station must be usable for a technology other than that corresponding to the first group of antennas 80, a second group of antennas 81 is mounted on the first.

For this purpose, interconnection means 85 are placed between the upper connecting element 80b of the first group 80 and the lower connecting element 81a of the second group of antennas 81. They are provided to allow access to the elements. of restraint and therefore the adjustment of the antennas in azimuth. In addition, they make it possible to adjust the relative positioning of two groups of antennas.

The second group of antennas 81 is then mounted, by enclosing the three antennas between the connecting elements 81a and 81b.

The connecting elements 81a and 81b also have openings 810, thanks to which the antennas can be oriented in azimuth, as illustrated in FIG. 9.

Finally, if this also proves necessary, a third antenna is mounted on the second group 81, by first placing an interconnection element 86 between the connection elements 81b and 82a.

In a manner identical to what has been described above, the antennas of the third group 82 are thus clamped between the two connecting elements 82a and 82b.

FIG. 10 illustrates a preferred embodiment of the antenna system illustrated in FIG. 8.

FIG. 10 is a sectional view which therefore shows the three antennas 1 as well as the lower connecting element 80a. Reference 820 designates a cavity made in the connecting element 80a for the passage of cables. It will be understood that the upper link element 80b also comprises such a cavity around which the connection element 85 will be arranged.

FIG. 10 shows that between each antenna 1, a section 9 is provided. The shape of the sections 9 is designed not to interfere with the azimuth adjustment of the antennas. It has a length which can be much greater than the height of the antennas and contributes to reinforcing the mechanical resistance of the group of antennas 80.

These profiles 9 may prove useful in an antenna system such as that illustrated in FIG. 8, comprising several groups of antennas and therefore having a significant overall height.

Such profiles can also be provided in the other groups of antennas 81 and 82.

Reference is now made to FIGS. 11 and 12 which illustrate an alternative embodiment of FIG. 7.

ίο This is again a set of three antennas 1 which are mounted on a mast 2, at approximately 120 ° (b) from each other.

The antenna assembly differs from that illustrated in FIG. 7, in that the connecting element is segmented.

Indeed, instead of being composed of a single substantially planar element, like the element 6b illustrated in FIG. 7, the connecting element is here composed of three elements 7b separated from each other. In practice, each of these elements 7b corresponds to an element 3a illustrated in FIG. 3. They will therefore not be described in more detail.

As has already been described previously, the mounting of each antenna 1 in an element 7b_; by means of the retaining means 17 cooperating with the openings 70, allows the azimuth adjustment of each antenna, independently of the other two.

This variant embodiment of the connecting elements is used when a set of antennas according to the invention is to be mounted on an existing mast. In fact, in this situation, it is difficult to insert a single element, such as element 6b, on a mast already installed. It is then preferable to proceed with the individual assembly of three segmented elements 7b.

The reference signs inserted after the technical characteristics appearing in the claims are intended only to facilitate understanding of the latter and cannot limit their scope.