Base station antenna with a movably mounted radome wall

Abstract

A base station antenna (1) according to the invention comprises a support structure (2), a first end-cap (3) that is mounted to a first end of the support structure (2), a second end-cap (4) that is mounted to a second end of the support structure (2) wherein the first end is an opposite ends of the second end, and a radome wall (5) that is aligned in between the first end-cap (3) and the second end-cap (4) to at least partially enclose the support structure (2), wherein the radome wall (5) is extending in a first direction (20) from the first end-cap (3) to the second end-cap (4). The support structure (2) comprises a first mounting section (6), wherein the radome wall (5) is mounted to the first mounting section (6) such that at least a portion of the radome wall (5) is movable relative to the first mounting section (6) in the first direction (20) to allow a thermal expansion of the radome wall (5).

Description

[0001] Base station antenna with a movably mounted radome wall

[0002] Technical field

[0003] The invention concerns a base station antenna, in particular a base station antenna for a cellular network,

[0004] Current mobile communication antennas are typically designed with GFRP radomes (glassfibre reinforced plastic). The inner structure is typically made of aluminum, which has a very similar thermal expansion as GFRP. In addition to that, GFRP can be clamped with screws so it makes it very easy to connect the housing parts with the internal carrying structure.

[0005] A base station antenna according to the art is disclosed by WO2021167718A1 , which discloses a base station antenna with a radome that has a base made of a light weight material.

[0006] A base station antenna according to the invention comprises a support structure, a first end-cap that is mounted to a first end of the support structure, a second end-cap that is mounted to a second end of the support structure wherein the first end is an opposite end of the second end, and a radome wall that is aligned in between the first end-cap and the second end-cap to at least partially enclose the support structure, wherein the radome wall is extending in a first direction from the first end-cap to the second end-cap, wherein the support structure comprises a first mounting section, and wherein the radome wall is mounted to the first mounting section such that at least a portion of the radome wall is movable relative to the first mounting section in the first direction to allow a thermal expansion of the radome wall.

[0007] The base station antenna is preferably a macro base station. The support structure is a structural component of the base station antenna and preferably extends over a full length of the base station antenna between the first end-cap and the second end-cap. The support structure is typically covered by a housing of the antenna and is protected from environmental influences. The housing preferably comprises the first end-cap, the second end-cap and the radome wall. Optionally, antennas or antenna arrays are mounted on the support structure. The support structure is preferably a metallic structure, in particular a metallic structure that comprises aluminium components. The radome wall is a unit of the base station antenna that comprises at least a portion that is designed to allow a passing of electromagnetic waves. Therefore, the radome wall preferably comprises at least a portion that is made of a dielectric material or the entire radome wall is made of a dielectric material. Preferably, the dielectric material is a plastic, in particular a thermoplastic. The mounting of the radome wall allows that a thermoplastic radome can be realized without beeing glued on end-caps. Also, a different thermal expansion of aluminum / steel of the support structure and the thermoplastic radome wall can be handled.

[0008] The radome wall is aligned in between the first end-cap and the second end-cap to at least partially enclose the support structure. In particular, the first end-cap and the second end-cap are both in contact with the radome wall to form a housing of the base station antenna. The radome wall is enclosing the support structure. This means that the radome wall is at least partially surrounding the support structure in one plane.

[0009] The radome wall is extending in a first direction from the first end-cap to the second end-cap. That is, the radome wall is extending from the first end-cap to the second end-cap and this direction from the first end-cap to the second end-cap is also referred to as the first direction. Preferably, the support structure is also extending from the first end-cap to the second end-cap and is therefore also extending in the first direction.

[0010] The support structure comprises a first mounting section. The mounting section is a portion or component of the support structure that allows a mounting of the radome wall to the support structure.

[0011] The radome wall is mounted to the first mounting section such that at least a portion of the radome wall is movable relative to the first mounting section in the first direction. In particular, the radome wall is mounted to the first mounting section such that at least a portion of the radome wall is movable over a first distance relative to the first mounting section in the first direction and is movable over a second distance relative to the first mounting section in a second direction, wherein the second direction is perpendicular to the first direction, wherein the second distance is smaller than the first distance. Preferably, the radome wall is mounted to the first mounting section such that the radome wall is held in a fixed distance from the support structure.

[0012] The portion that is movable relative to the first mounting section in the first direction is an area of the radome wall that is adjacent to the support structure. The movement is typically a movement that is caused by a thermal expansion or contraction of the radome wall. That is, the radome wall expands or contracts due to thermal influences that are applied to the radome wall. Because of such an expansion or contraction, the radome wall will increase or decrease in its size. The first mounting section allows that the radome wall to change size, as the radome wall is not held in a fixed position relative to the support structure.

[0013] The dependent claims define preferable embodiments of the invention.

[0014] Preferably, the first end-cap is mounted in a fixed position relative to the support structure and the radome wall is mounted to the first mounting section such that the radome wall is movable relative to the first end-cap and / or the second end-cap is mounted in a fixed position relative to the support structure and the radome wall is mounted to the first mounting section such that the radome wall is movable relative to the second end-cap. A mounting in a fixed position is applied when there are no options for a relative movement foreseen in the connection. As the radome wall is mounted to the first mounting section such that the radome wall is movable relative to the first end-cap and / or the second end-cap, the radome wall is able to expand towards the endcaps or to contract without building up tensions between the end-caps and the radome wall that might lead to a damage of any of these components. Preferably, the radome wall is mounted to the first mounting section such that the radome wall is movable relative to both of the first endcap and the second end-cap, in particular to be moveable as a whole relative to both of the first end-cap and the second end-cap. In the alternative, the radome wall is fixed to one of the endcaps and is mounted to be movable relative to the other one of the end-caps. In this case, the radome wall can expand in at least one direction towards the end-cap that allows the relative movement.

[0015] Preferably, the first end-cap comprises a first sidewall that is overlapping with the radome wall in the first direction, and / or the second end-cap comprises a second sidewall that is overlapping with the radome wall in the first direction. The first sidewall is preferably a circumferential wall that is mounted to a base of the first end-cap. The first sidewall is preferably forming a ring that is enclosing the radome wall on a side of the first end of the support structure, wherein the first sidewall is preferably aligned parallel to the radome wall. The second sidewall is preferably a circumferential wall that is mounted to a base of the second end-cap. The second sidewall is preferably forming a ring that is enclosing the radome wall on a side of the second end of the support structure, wherein the second sidewall is preferably aligned parallel to the radome wall.

[0016] Preferably, the radome wall is mounted to the first mounting section such that the radome wall is not movable relative to the first mounting section in a third direction, wherein the third direction is a direction that is perpendicular to an outer surface of the radome wall. The outer surface of the radome wall is a surface of the radome wall that is forming an outside of a housing of the base station antenna. Preferably, the support structure is a reflector plate unit. Optionally, antenna elements are mounted on the reflector plate unit, wherein the antenna elements are radiating elements of the base station antenna, for example dipoles. Thus, the support structure can serve multiple purposes.

[0017] Preferably, the radome wall is forming a tube, wherein the tube is closed on one end by the first end-cap and on the other end by the second end-cap. Thus, a closed housing for the base station antenna can be provided by the radome wall in combination with the end-caps.

[0018] Preferably, the first mounting section is configured for mounting the base station antenna to a carrier structure. The carrier structure is an external structure that is not part of the base station antenna, such as a mounting pole. Therefore, a single opening in the radome wall can be shared in use for mounting the base station antenna to the carrier structure and for mounting the radome wall to the support structure. Preferably, the base station comprises multiple mounting sections that are configured for mounting the base station antenna to a carrier structure and for mounting the radome wall to the support structure.

[0019] Preferably, the radome wall comprises a first hole, wherein a rod of the first mounting section is extending through the first hole, wherein the rod has a cross section with a shape and size that allows the rod to move in the first direction. The rod is part of the support structure and is therefore mounted in a fixed position relative to the other parts of the support structure and relative to one or both of the end-caps. Thus, it is possible to mount the support structure to the carrier structure without inhibiting a relative movement of the radome wall in relation to the support structure. The first hole is a through-hole that is connecting an inner side of the radome wall with an outer side of the radome wall. Preferably, the rod comprises a section that does not allow the rod to pass through the hole or has an additional component mounted to the rod that does not allow the rod to pass through the hole on both sides of the hole, such that the radome wall is fixed to the rod for a movement in an axial direction of the rod. Preferably, the rod is the shaft of a screw or bolt.

[0020] Preferably, the first hole is a longhole, wherein the longhole has a maximum diameter in the first direction and a minimum diameter in a second direction, wherein the second direction is perpendicular to the first direction, wherein a cross section of the rod is of a shape and size to allow the radome wall more movement in the first direction than in the second direction. Preferably, the rod has a circular cross section in a portion that is aligned inside the hole. The maximum diameter in the first direction allows a further movement of the rod in the first direction than in the second direction. Preferably, a length of the radome wall in the first direction is larger than a length of the radome wall in the second direction. The greater length in the first direction leads to a larger movement of the radome wall because of thermal expansion and contraction. The longhole allows that sufficient freedom of movement is provided in the first direction while ensuring sufficient support in the second direction. Optionally, the rod is of a shape and size to allow the radome wall no movement in the second direction.

[0021] Preferably, a sleeve is mounted to the rod, wherein the sleeve has a length that is equal to or longer than a thickness of the radome wall adjacent to the first hole. A sleeve is a tubular element. The sleeve has a length that is equal to or longer than a thickness of the radome wall adjacent to the first hole. In other words, the sleeve has an axial length that is equal to or larger than the depth of the first hole. In case the axial length of the sleeve is larger than the depth of the hole, this means that the sleeve will stand out of the first hole on at least one side once positioned within the first hole. The sleeve is suitable to avoid that the radome wall is squeezed in between components that are mounted to the rod. Therefore, objects can be mounted on the rod and the sleeve will ensure that a certain distance will be maintained between these objects, wherein the certain distance is the length of the sleeve. This will avoid that pressure is applied to the radome wall by any components of the first mounting section, which in particular allows to use a radome wall that has an air incorporating structure, as it is avoided that the air incorporating structure is compressed and potentially damaged. A cross section of the sleeve inside of the first hole is preferably of a shape and size to allow the radome wall more movement in the first direction than in the second direction. Preferably, the sleeve has a circular cross section in an area that is aligned inside the hole. Optionally, the sleeve is connected to the rod, for example by means of an inside thread and an outside thread that is formed by the rod and the sleeve, which allows to movably connect the support structure to the radome wall. Optionally, the sleeve is clamped in between a widened portion of the rod, for example a screw head, and the further support structure to movably connect the support structure to the radome wall via the sleeve.

[0022] Preferably, a sealing pad is aligned over the first hole, and the rod is extending through a hole in the sealing pad. Preferably, the sealing pad is clamped in between a widened portion of the rod, for example a screw head, and the sleeve. The sealing pad can move with the sleeve and the rod in the first direction and optionally in the second direction and is of a size to cover the entire hole in all possible positions of the sleeve.

[0023] Preferably, the radome wall comprises a guiding channel that is extending over the entire radome wall in the first direction, wherein the first mounting section comprises a gliding element that has a size and shape to fit into the guiding channel such that the gliding element can be moved along the guiding channel in the first direction, wherein the rod is extending through an opening of the gliding element. As the rod is extending through an opening of the gliding element, in particular a through hole in the gliding element, the gliding element is configured to move together with the rod, as the gliding element can be moved along the guiding channel in the first direction. The gliding element has a size and shape to fit into the guiding channel such that the gliding element can be moved along the guiding channel in the first direction. In particular, the gliding element that has a size and shape to fit into the guiding channel such that the gliding element is able to transfer a force between the rod and the radome wall in the second direction. Therefore, the gliding element is configured to hold the radome wall in a fixed position relative to the support structure in the second direction.

[0024] Preferably, the radome wall comprises multiple segments. The multiple segments can be of the same material or can be made of different materials. As thermal expansions in relation to the support structure can be handled by the mounting section, large freedom in the combination of materials of the radome wall is possible in a design phase.

[0025] Preferably, the radome wall is made of a thermoplastic material. Such material often leads to relatively large thermal expansion of the radome wall. A use of the thermoplastic material in combination with the first mounting section that allows a relative movement of the radome wall can avoid damage of the radome wall.

[0026] Preferably, the radome wall has an air incorporating structure. Air incorporating structures, such as multi-wall sheets, can lead to relative large thermal expansion of the radome wall and have to be able to move in the mounting position to avoid damages in the structure. The air incorporating structure also makes the radome wall more sensitive for damages that are caused by contact-pressure that results from a thermal expansion of the radome wall. Therefore, it is specifically advantageous to ensure that a movement is possible for the radome wall that allows to avoid a build up of contact pressure at the mounting points of the radome wall when the radome wall is expanding.

[0027] Preferably, the support structure comprises a second mounting section, wherein the radome wall is mounted to the second mounting section such that at least a portion of the radome wall is movable relative to the second mounting section in the first direction, or wherein the radome wall is mounted to the second mounting section such that at least a portion of the radome wall is in a fixed position relative to the second mounting section. Preferably, the second mounting section comprises all characteristics of the first mounting section. In case that the radome wall is mounted to the second mounting section such that at least a portion of the radome wall is movable relative to the second mounting section in the first direction, a freedom of movement of the radome wall in relation to the support structure is optimized. Preferably, the radome wall is mounted to the support structure such that the entire radome wall is movable relative to the support structure. Thus, a floating mounting of the radome wall is achieved.

[0028] Brief description of the drawings

[0029] Fig. 1 shows a base station antenna according to an embodiment of the invention, fig. 2 shows a schematic view of a mounting section of the base station antenna, fig. 3 shows a schematic view of an exemplary segment of a radome wall that has an air incorporating structure comprises and a guiding channel, and fig. 4 shows a schematic view of a mounting section of the base station antenna.

[0030] Detailed description

[0031] Figure 1 shows a cross section of a base station antenna 1 according to an embodiment of the invention. The base station antenna 1 is an antenna of a macro base station of a cellular communication network.

[0032] The base station antenna 1 comprises a support structure 2. The support structure 2 comprises a reflector plate unit 10. The support structure 2 is a structure that is providing a structural basis for mounting different components of the base station antenna 1. For example, multiple antenna elements of the base station antenna 1 are mounted on the reflector plate unit 10. The support structure 2 is a metallic structure, in particular a metallic structure that comprises aluminium components. In particular, the reflector plate unit 10 is a metallic unit.

[0033] A first end-cap 3 is mounted to a first end of the support structure 2, which is an upper end in figure 1. A second end-cap 4 is mounted to a second end of the support structure 2, which is an lower end in figure 1. Thus, the first end is an opposite end of the second end and the end-caps 3, 4 are mounted to opposite ends of the support structure 2.

[0034] The first end-cap 3 is mounted in a fixed position relative to the support structure 2. That is, the first end-cap 3 is non-movably connected to the support structure 2. For example, the end-cap 3 is screwed, glued, riveted or welded to the support structure 2 by one or more first screws 16. The second end-cap 4 is mounted in a fixed position relative to the support structure 2. That is, the second end-cap 4 is non-movably connected to the support structure 2. For example, the second end-cap 4 is screwed, glued, riveted or welded to the support structure 2 by one or more second screws 17. A radome wall 5 is aligned in between the first end-cap 3 and the second end-cap 4 to at least partially enclose the support structure 2. The radome wall 5 is forming a tube, wherein the tube is closed on one end by the first end-cap 3 and on the other end by the second end-cap 4.

[0035] Thus, the radome wall 5 is extending from the first end-cap 3 to the second end-cap 4, wherein this direction is referred to as a first direction 20. The first direction is an up-down direction in figure 1, as also indicated by the arrow 30, which is representing possible movement directions of the radome wall 5 relative to the support structure 2.

[0036] The radome wall 5 is made of a thermoplastic material and has an air incorporating structure. For example, the radome wall has a multi-wall structure, wherein the multi-wall structure forms channels that extend inside the radome wall 5 from the first end-cap 3 to the second end-cap 4. Optionally, the radome wall 5 comprises multiple segments.

[0037] As the radome wall 5 is made of a thermoplastic material and the support structure 2 is a metallic structure, these entities have different expansion factors. That is, the support structure 2 and the radome wall 5 will expand and contract differently under thermal influences. This could lead to undesirable forces on connection points between the support structure 2 and the radome wall 5 that can potentially lead to a damage of the radome wall 5. To avoid such damages, the radome wall 5 is mounted movably relative to the support structure 2 and movably relative to the end-caps 3, 4.

[0038] The first end-cap 3 has a base surface that is of a shape and a size that corresponds to the opening of the tube that is formed by the radome wall 5. A first sidewall 7 is extending on a border of the base surface and is forming a circumferential wall. The first sidewall 7 is parallel to the radome wall 5 and is overlapping with the radome wall 5 in the first direction 20. The first sidewall 7 is not connected to the radome wall 5 such that a relative movement between the first sidewall 7 and the radome wall 5 in the first direction 20 is possible.

[0039] The second end-cap 4 has a base surface that is of a shape and a size that corresponds to the opening of the tube that is formed by the radome wall 5. A second sidewall 8 is extending on a border of the base surface and is forming a circumferential wall. The second sidewall 8 is parallel to the radome wall 5 and is overlapping with the radome wall 5 in the first direction 20. The second sidewall 8 is not connected to the radome wall 5 such that a relative movement between the second sidewall 8 and the radome wall 5 in the first direction 20 is possible.

[0040] The support structure 2 comprises a first mounting section 6 and a second mounting section 18. The radome wall 5 is mounted to the first mounting section 6 such that at least a portion of the radome wall 5 is movable relative to the first mounting section 6 in the first direction 20. The portion that is movable relative to the first mounting section 6 is a portion of the radome wall 5 that is adjacent to the first mounting section 6. The radome wall 5 is further mounted to the second mounting section 18 such that at least a portion of the radome wall 5 is movable relative to the second mounting section 18 in the first direction 20. The portion that is movable relative to the second mounting section 18 is a portion of the radome wall 5 that is adjacent to the second mounting section 18. In this embodiment, the entire radome wall 5, is movable relative to the first mounting section 6 and the second mounting section 18 in the first direction 20.

[0041] The radome wall 5 is mounted to the first mounting section 6 such that the radome wall 5 is movable relative to the first mounting section 6 in the first direction 20 and is also movable relative to the first mounting section 6 in a second direction 21 , wherein the second direction 21 is perpendicular to the first direction 20. Both of the first direction 20 and the second direction 21 are parallel to a surface of the radome wall 5 in the area of the first mounting section 6. The radome wall 5 is movable relative to the first mounting section 6 and is able to move a larger distance in the first direction 20 than in the second direction 21. Therefore, the radome wall 5 is mounted to the first mounting section 6 such that the radome wall 5 is movable over a first distance relative to the first mounting section 6 in the first direction 20 and is movable over a second distance relative to the first mounting section 6 in the second direction 21 , wherein the second distance is smaller than the first distance. The radome wall 5 is mounted to the first mounting section 6 such that the radome wall 5 is held in a fixed position in a third direction 22, wherein the third direction 22 is a direction perpendicular to an outer surface of the radome wall 5 in the area of the first mounting section 6. The third direction 22 is perpendicular to the first direction 20 and the second direction 21 .

[0042] The radome wall 5 is mounted to the first mounting section 6 such that the portion of the radome wall 5 that is movable relative to the first mounting section 6 in the first direction 20 is not movable in a direction that is perpendicular to an outer surface of the radome wall 5. The direction that is perpendicular to an outer surface of the radome wall 5 is also referred to as the third direction 22. Referring to figure 1 , this means that the portion of the radome wall 5 that is adjacent to the first mounting section 6 can move up and down relative to the support structure 2 but is not able to move away from the support structure 2 in a left-right direction.

[0043] The radome wall 5 is mounted to the second mounting section 18 such that the radome wall 5 is movable relative to the second mounting section 18 in the first direction 20 and is also movable relative to the second mounting section 18 in the second direction 21 , wherein the second direction 21 is perpendicular to the first direction 20. Both of the first direction 20 and the second direction 21 are parallel to a surface of the radome wall 5 in the area of the second mounting section 18. The radome wall 5 is movable relative to the second mounting section 18 and is able to move a larger distance in the first direction 20 than in the second direction 21. Therefore, the radome wall 5 is mounted to the second mounting section 18 such that the radome wall 5 is movable over a first distance relative to the second mounting section 18 in the first direction 20 and is movable over a second distance relative to the second mounting section 18 in the second direction 21 , wherein the second distance is smaller than the first distance. The radome wall 5 is mounted to the second mounting section 18 such that the radome wall 5 is held in a fixed position in the third direction 22, wherein the third direction 22 is a direction perpendicular to an outer surface of the radome wall 5 in the area of the second mounting section 18. The third direction 22 is perpendicular to the first direction 20 and the second direction 21.

[0044] The radome wall 5 is mounted to the second mounting section 18 such that the portion of the radome wall 5 that is movable relative to the second mounting section 18 in the first direction 20 is not movable in a direction that is perpendicular to an outer surface of the radome wall 5, that is the third direction 22. Referring to figure 1 , this means that the portion of the radome wall 5 that is adjacent to the second mounting section 18 can move up and down relative to the support structure 2 but is not able to move away from the support structure 2 in a left-right direction.

[0045] The radome wall 5 is connected to the support structure 2 only via the first mounting section 6 and the second mounting section 18. As both of these mounting sections 6, 18 allow a movement of the radome wall 5 in the first direction 20 and in the second direction 21 and do not allow a movement in the third direction 22, a floating movement of the radome wall 5 in a plane that is spanned by the first direction 20 and the second direction 21 is achieved. The radome wall 5 is mounted to the support structure 2 such that the entire radome wall 5 is movable relative to the support structure 2 in the first direction 20 and in the second direction 21 , wherein a movement over a larger distance is possible in the first direction 20 when compared to a movement in the second direction 21.

[0046] The radome wall 5 is mounted to the first mounting section 6 such that the radome wall 5 is movable relative to the first end-cap 3. That is, the first mounting section 6 and the second mounting section 18 allow a movement of the radome wall 5 relative to the support structure 2. As the relative position of the support structure 2 to the first end-cap 3 is fixed, the radome wall 5 is not connected to the first end-cap 3 and a movement of the radome wall 5 relative to the support structure 2 is possible, this leads to the effect that a movement of the radome wall 5 relative to the first end-cap 3 is possible.

[0047] The radome wall 5 is mounted to the second mounting section 18 such that the radome wall 5 is movable relative to the second end-cap 4. That is, the first mounting section 6 and the second mounting section 18 allow a movement of the radome wall 5 relative to the support structure 2. As the relative position of the support structure 2 to the second end-cap 4 is fixed, the radome wall 5 is not connected to the second end-cap 4 and a movement of the radome wall 5 relative to the support structure 2 is possible, this leads to the effect that a movement of the radome wall 5 relative to the second end-cap 4 is possible.

[0048] The mounting of the radome wall 5 allows a relative movement of the radome wall 5 relative to the support structure 2 and the end-caps 3, 4 and therefore allows the radome wall 5 to expand or to contract under thermal influences that might be caused by environmental conditions and / or by the operation of the base station antenna.

[0049] The first mounting section 6 and the second mounting section 18 are configured for mounting the base station antenna 1 to a carrier structure such as an antenna pole, wherein further components, for example an antenna mounting kit, can be mounted to the mounting sections 6, 18.

[0050] Figure 2 shows details of the first mounting section 6 according to aspects of the invention. The second mounting section 18 corresponds to the first mounting section 6. Thus, figure 2 can also be read as showing details of the second mounting section 18. Two different views of the same first mounting section 6 are shown in figure 2, wherein a cross sectional view through the cutting layer A, which is indicated on the left side of figure 2, is depicted on the right side of figure 2.

[0051] The radome wall 5 comprises a first hole 9 in an area of the first mounting section 6, which allows the first mounting section 6 to engage with the radome wall 5. The radome wall 5 further comprises a second hole in an area of the second mounting section 18, which allows the second mounting section 18 to engage with the radome wall 5.

[0052] The first mounting section 6 comprises a rod 11 that is configured to be connected to the reflector plate unit 10. The rod 11 is a threaded part of a screw that is screwed into a corresponding thread in the reflector plate unit 10. The rod 11 allows to connect an antenna mounting kit to the base station antenna 1. For example, a mounting bracket 14 can be mounted to the base station antenna 1 via the rod 11, wherein the mounting bracket 14 can be connected to the antenna mounting kit.

[0053] The rod 11 of the first mounting section 6 is extending through the first hole 9, wherein the rod 11 has a cross section with a shape and size that allows the rod to move in the first direction 20. The first hole 9 is a longhole. The rod 11 has a circular cross section in the plane of the radome wall 5. The longhole has a maximum diameter 23 in the first direction 20 and a minimum diameter 24 in the second direction 21, wherein the second direction 21 is perpendicular to the first direction 20. A diameter of the rod 11 in the plane of the radome wall 5 is smaller than the minimum diameter 24. Therefore, the cross section of the rod 11 is of a shape and size that allows the radome wall 5 more movement in the first direction 20 than in the second direction 21.

[0054] In this embodiment, a sleeve 12 is mounted to the rod 11. The sleeve 12 has a circular cross section in the plane of the radome wall 5. The sleeve is enclosing the rod 11 and is therefore limiting the available range for a movement of the rod 11 in the first hole 9. To allow a movement of the radome wall 5 relative to the support structure 2, the diameter of the sleeve 12 in the plane of the radome wall 5 is smaller than the minimum diameter of the first hole 9. Consequently, the cross section of the sleeve 12 is of a shape and size that allows the radome wall 5 more movement in the first direction 20 than in the second direction 21 .

[0055] The sleeve 12 has the shape of a tube and the rod 11 is aligned inside the tube. The sleeve 12 is preferably a metallic element. The mounting bracket 14 is clamped between the head of the screw that comprises the rod 11 and the sleeve 12. For example, the mounting bracket 14 comprises a through hole that is suitable for mounting the rod 11 of the screw while not allowing that the head of the screw is passing through the through hole of the mounting bracket 14. The sleeve 12 is clamped between the head of the screw that comprises the rod 11 and the reflector plate unit 10. More specifically, the sleeve 12 is clamped between the mounting bracket 14 and the reflector plate unit 10. Therefore, a pressure force that results from tightening the screw is transmitted from the head of the screw through the sleeve 12 towards the reflector plate unit 10. This leads to the effect that this pressure force is not, or at least not fully, applied to the radome wall 5, avoiding a potential damage of the radome wall 5.

[0056] As the cross section of the sleeve 12 in the plane of the radome wall 5 is smaller than the minimum diameter 24 of the first hole 9, the radome wall 5 is able to move in relation to the rod 11 and the sleeve 12 in the first direction 20 and in the second direction 21. However, the sleeve 12 is not able to move relative to the radome wall 5 in the third direction 22, which is the direction perpendicular to an outer surface of the radome wall 5 and is a direction that is equivalent to an axial direction 25 of the rod 11 , as this movement is either blocked by the reflector plate unit 10 or by a gliding element 15, which is mounted to the rod 11. For mounting the gliding element 15 to the rod 11 , the gliding element 15 comprises a through hole and the rod 11 is passing through the through hole of the gliding element 15. Optionally, the through hole of the gliding element 15 allows a relative movement of the rod 11 in the second direction 21.

[0057] The gliding element 15 is movably mounted to the radome wall 5, wherein the gliding element 15 is movable relative to the radome wall 5 in the first direction 20 but is in a fixed relative position to the radome wall 5 in the second direction 21 and the third direction 22. For the mounting of the gliding element 15, the radome wall 5 comprises a guiding channel 19 that is extending over the entire radome wall 5 in the first direction. During mounting, the gliding element 15 is slided through the guiding channel 19 and is positioned such that the through hole of the gliding element 15 is aligned with the first hole 9, which allows a mounting of the rod 11, preferably in combination with mounting the sleeve 12 and the mounting bracket 14. When mounted, wherein the rod 11 is extending through an opening of the gliding element 15, that is through the through hole of the gliding element 15. The gliding element 15 is held together with the radome wall 5 in between the head of the screw that comprises the rod 11 and the reflector plate unit 10. That is, a movement of the gliding element 15 and the radome wall 5 in the axial direction 25 of the rod 11 is limited such that the gliding element 15 and the radome wall 5 are held in position in the axial direction 25 of the rod 11. At the same time, a pressure that is applied to the gliding element 15 and the radome wall 5 is limited or avoided by the sleeve 12, which allows an acting of forces in between head of the screw to the reflector plate unit 10.

[0058] The gliding element 15 that has a size and shape to fit into the guiding channel 19 such that the gliding element 15 can be moved along the guiding channel 19 in the first direction 20 but does not allow a relative movement of the gliding element 15 in the second direction 21 or the third direction 22. That is, a transfer of forces between the gliding element 15 and the radome wall 5 is the second direction 21 and the third direction 22 is possible. Therefore, the radome wall 5 can be held in a fixed relative position relative to the support structure 2 in the third direction 22 via the gliding element 15, which is held in a fixed position relative to the support structure 2 in the third direction 22. The gliding element 15 allows to increase a contact surface between the first mounting section 6 and the radome wall 5, which allows to avoid a movement of the radome wall 5 along the axial direction 25 of the rod 11 while avoiding that a high pressure is applied to small areas of the radome wall 5 and while allowing the relative movement of the radome wall 5 in the first direction 20.

[0059] A relative position of the rod 11 to the sleeve 12 is fixed. In particular, the sleeve 12 is clamped between a portion of the rod 11 that is outside of the radome wall 5, for example a screw head, and a portion of the rod 11 that is inside of the radome wall 5 or is clamped between a portion of the rod 11 that is outside of the radome wall 5 and the reflector plate unit 10. As the relative position of the rod 11 and the sleeve 12 is fixed, and the sleeve 12 is not able to move relative to the radome wall 5 in the third direction 22, the radome wall 5 is not able to move relative to the rod 11, and therefore relative to the support structure 2, in the third direction 22.

[0060] Preferably, a sealing pad 13 is aligned in between the mounting bracket 14 and the radome wall 5. The sealing pad 13 is made of an elastic material, for example rubber, and the rod 11 and the sleeve 12 are extending though a through hole in the sealing pad 13. The sealing pad 13 has a size that allows the sealing pad 13 to cover the entire first hole 9, independent of the position of the rod 11 within the first hole 9. Therefore, the sealing pad 13 is closing the entire first hole 9, even though the sealing pad 13 is moving together with the rod 11 and the sleeve 12 is movable relative to the radome wall 5 in the first direction 20 and in the second direction 21.

[0061] In the described embodiment, the radome wall 5 is mounted to the second mounting section 18 such that at least a portion of the radome wall 5 is movable relative to the second mounting section 18 in the first direction 20. In alternative embodiments, the radome wall 5 is mounted to the second mounting section 18 such that at least a portion of the radome wall 5 is in a fixed position relative to the second mounting section 18. Referring back to figure 1 , this means that the radome wall 5 can be fixed non movably at one position to the support structure 2, as long as the other mounting sections allow a relative movement of the radome wall 5 relative to the support structure 2, as this will still allow the radome wall 5 to expand in all directions.

[0062] Figure 3 is showing a portion of the radome wall 5 that is made of a thermoplastic material and has an air incorporating structure, wherein the radome wall has a multi-wall structure. Figure 3 is depicting one segment of the radome wall 5, wherein the segment is a segment that is mounted to the first mounting section 6. The radome wall 5 comprises further segments that are not depicted in Figure 3. It can be seen that the guiding channel 19 is formed into the thermoplastic material of the multi-wall structure. The guiding channel 19 is formed as a single piece with the segment of the radome wall 5. It is noted that the depicted cross section is not in the area of the first or second mounting section 6, 18, as such a cross section would show the first hole 9 or the second hole in the radome wall 5.

[0063] Figure 4 is showing the first mounting section 6 of figure 2 in further detail, wherein the radome wall 5 of figure 3 is mounted to the support structure 2.

[0064] Referring to all embodiments, it is noted that the number of mounting sections is variable and that not necessarily all mounting sections are on the same side of the base station antenna 1 , as depicted in Figure 1. Preferable, mounting sections according to the invention are provided on opposite sides of the base station antenna 1 , wherein the mounting sections in combination allow a relative movement of the radome wall 5 relative to the support structure 2 in the first direction 20, optionally also in the second direction 21 , and fix the radome wall 5 relative to the support structure 2 in the third direction 30. In this case, the third direction can be different for different mounting sections, wherein the third direction is a direction that corresponds to the axial direction of the corresponding rod 11 of each mounting section, respectively. Further referring to all embodiments, it is noted that one mounting section can comprise two rods 11 , wherein the two rods extend through two adjacent first holes 9 in the radome wall 5. In this case, the two rods are preferably extending through two holes of the same gliding element 15, which allows to avoid that the gliding element 15 might rotate in the guiding channel 19, which might lead to a block of the movement of the gliding element 15 in the guiding channel 19.

[0065] Summarizing the above, the base station antenna 1 preferably comprises an internal carrying structure including the end-caps 3, 4, with a “free floating” radome, that is the radome wall 5, that is supported by inner supports, wherein the inner supports are described as mounting sections. Therefore, the radome is contained by the end-caps 3, 4 and two or more slotted holes for mounting and carrying accessories. All antenna parts except the radome wall 5 are fixed to the carrying structure. Thermal expansion of the radome wall 5 is covered by an overlap of the endcaps 3, 4 to the radome wall 5. The sealing between the radome wall 5 and mounting hardware can be done with a rubber pad. A sealing between the end-caps 3, 4 and the radome wall 5 can be a labyrinth seal or a rubber seal. With this, it is possible to realize a housing without the need of additional gluing processes. All components can be screwed on. Also, easy access to inner components of the base station antenna 1 without destroying components is possible. The radome wall 5 can move and shift within the antenna structure, without damage to any parts due to thermal expansion.

[0066] Preferably, there is need for glued connections in the antenna housing. This makes it much easier for the antenna production because gluing processes are more complex to control. The radome can be made from multiple parts because it is constrained by the end-caps 3, 4. Since the radome wall 5 is not clamped by screws the radome can be made from other / new materials, like air filled materials or air-filled structures, which help the electrical performance.

Claims

Claims1. A base station antenna (1), the base station antenna (1) comprising: a support structure (2); a first end-cap (3) that is mounted to a first end of the support structure (2); a second end-cap (4) that is mounted to a second end of the support structure (2) wherein the first end is an opposite end of the second end; and a radome wall (5) that is aligned in between the first end-cap (3) and the second end-cap (4) to at least partially enclose the support structure (2), wherein the radome wall (5) is extending in a first direction (20) from the first end-cap (3) to the second end-cap (4); wherein the support structure (2) comprises a first mounting section (6); and wherein the radome wall (5) is mounted to the first mounting section (6) such that at least a portion of the radome wall (5) is movable relative to the first mounting section (6) in the first direction (20) to allow a thermal expansion of the radome wall (5).

2. The base station antenna (1) according to claim 1 , wherein the first end-cap (3) is mounted in a fixed position relative to the support structure (2) and the radome wall (5) is mounted to the first mounting section (6) such that the radome wall (5) is movable relative to the first end-cap (3); and / or wherein the second end-cap (4) is mounted in a fixed position relative to the support structure (2) and the radome wall (5) is mounted to the first mounting section (6) such that the radome wall (5) is movable relative to the second end-cap (4).

3. The base station antenna (1) according to any one of the previous claims, wherein the first end-cap (3) comprises a first sidewall (7) that is overlapping with the radome wall (5) in the first direction (20), and / or wherein the second end-cap (4) comprises a second sidewall (8) that is overlapping with the radome wall (5) in the first direction (20).

4. The base station antenna (1) according to any one of the previous claims, wherein the radome wall (5) is mounted to the first mounting section (6) such that the radome wall (5) is not movable relative to the first mounting section (6) in a third direction (22), wherein the third direction (22) is a direction that is perpendicular to an outer surface of the radome wall (5).

5. The base station antenna (1) according to any one of the previous claims, wherein the support structure (2) is a reflector plate unit (10).

6. The base station antenna (1) according to any one of the previous claims, wherein the radome wall (5) is forming a tube, wherein the tube is closed on one end by the first end-cap (3) and on the other end by the second end-cap (4).

7. The base station antenna (1) according to any one of the previous claims, wherein the first mounting section (6) is configured for mounting the base station antenna (1) to a carrier structure.

8. The base station antenna (1) according to any one of the previous claims, wherein the radome wall (5) comprises a first hole (9); wherein a rod (11) of the first mounting section is extending through the first hole (9), wherein the rod (9) has a cross section with a shape and size that allows the rod to move in the first direction (20).

9. The base station antenna (1) according to claim 8, wherein the first hole is a longhole, wherein the longhole has a maximum diameter (23) in the first direction (20) and a minimum diameter (24) in a second direction (21), wherein the second direction (21) is perpendicular to the first direction (20), wherein a cross section of the rod (1) is of a shape and size to allow the radome wall (5) more movement in the first direction (20) than in the second direction (21).

10. The base station antenna (1) according to any one of the previous claims, wherein a sleeve(12) is mounted to the rod (11), wherein the sleeve has a length that is equal to or longer than a thickness of the radome wall (5) adjacent to the first hole (9).

11. The base station antenna (1) according to any one of the previous claims, wherein a sealing pad (13) is aligned over the first hole (9), and wherein the rod (11) is extending through a hole in the sealing pad (13).

12. The base station antenna (1) according to any one of the previous claims, wherein the radome wall (5) comprises a guiding channel (19) that is extending over the entire radome wall (5) in the first direction,wherein the first mounting section (6) comprises a gliding element (15) that has a size and shape to fit into the guiding channel (19) such that the gliding element (15) can be moved along the guiding channel (19) in the first direction (20), and wherein the rod (11) is extending through an opening of the gliding element (15).

13. The base station antenna (1) according to any one of the previous claims, wherein the radome wall (5) is made of a thermoplastic material, and / or wherein the radome wall (5) has an air incorporating structure.

14. The base station antenna according to any one of the previous claims, wherein the support structure (2) comprises a second mounting section (18); wherein the radome wall (5) is mounted to the second mounting section (18) such that at least a portion of the radome wall (5) is movable relative to the second mounting section (18) in the first direction (20), or wherein the radome wall (5) is mounted to the second mounting section (18) such that at least a portion of the radome wall (5) is in a fixed position relative to the second mounting section (18).

15. The base station antenna (1) according to any one of the previous claims, wherein the radome wall (5) is mounted to the support structure such that the entire radome wall (5) is movable relative to the support structure (2).

Images