WO2016055126A1

WO2016055126A1 - Spacer for reducing pim in an antenna

Info

Publication number: WO2016055126A1
Application number: PCT/EP2014/071789
Authority: WO
Inventors: Johann Obermaier
Original assignee: Huawei Technologies Co.,Ltd
Priority date: 2014-10-10
Filing date: 2014-10-10
Publication date: 2016-04-14
Also published as: CN106797068B; CN106797068A

Abstract

The present invention provides a spacer (101) for being arranged between a frame (103) and a reflector (102) of an antenna (100). The spacer (101) is configured to separate the reflector (102) and the frame (103), while the reflector (102) is inserted into a hull of the antenna (100), and allows at least one contact area (104) of the reflector (102) to touch at least one contact area (605) of the frame (103), when the reflector (102) is attached to the frame (103). A surface of the spacer 101 is chosen such that abrasion of the frame (103) is prevented, while the reflector (102) is inserted into the hull. The present invention provides further an antenna (100) comprising the spacer 101 between a frame (103) and a reflector (102), and provides a method (1000) of assembling such an antenna (100).

Description

SPACER FOR REDUCING PIM IN AN ANTENNA

TECHNICAL FIELD The present invention is directed to a spacer for being arranged between a frame and a reflector of an antenna, to an antenna including the spacer, and to a method of assembling the antenna by using the spacer. In particular, the spacer proposed by the present invention is also referred to as a Passive Inter Modulation (PIM) shoe with the purpose of addressing PIM issues caused during antenna assembly.

BACKGROUND

For antennas, particularly for base station antennas, one key criterion of a high performance is a low PIM level. For base station antennas the required industry standard for the PIM level is, for instance, lower than -150dBc. Additionally, long term stability of the PIM level is mandatory.

A too high PIM level would cause a severe degradation of the antenna, and thus the network performance. Therefore, when installing a base station antenna, the PIM level is typically measured. Problematic PIM levels are therefore likely to be recognized by the customer.

There are several sources for PIM in antennas, which are known in the state of the art. For example, one prominent source of PIM is loose metal particles within an assembled antenna. The loose metal particles cause a low and not stable PIM performance. Even worse, if such loose metal particles are the source for PIM, the PIM level can even change randomly, due to vibration or transport of the antenna and the inevitable movement of the loose metal particles. Therefore, also the antenna performance will change randomly. This effect can even happen on stock.

Loose metal particles can, for example, be soldering bubbles, chipping from milling or stamping, die-casting burs, or can be caused by contamination brought into the antenna from the outside. Additionally, loose metal particles can be caused by abrasion, i.e. when metal parts slide against each other or over abrasive surfaces. As shown in Fig. 11, at the assembly process of a conventional base station antenna 1100, all relevant components 1104 are fixed to a reflector 1102. The fixing operation includes, for example, screwing, snapping and soldering. Normally, these fixing operations do not cause any movement between metal parts, and thus there is normally no danger of abrasion that creates loose metal particles.

However, in one of the last steps of the assembly process of the conventional antenna 1100, the reflector 1102 with all the components 1104 will be pushed, as shown in Fig. 11, into the antenna hull 1101. The antenna hull 1101 consists typically of a front side 1105, which is made of a fiber reinforced plastic, and an aluminum frame 1106 on the rear side. The result is that while pushing the reflector 1102, a metal reflector foot 1103 arranged between the reflector 1102 and the antenna hull 1001 slides over the aluminum frame 1106. This results in abrasion of the frame 1106 and the reflector foot 1103, respectively, and consequently creates loose metal particles within the antenna after its assembly.

Conventional solutions propose to prevent such metal abrasion during the sliding step of the antenna assembly by using a foil, which is added to the reflector foot before antenna assembly. However, the disadvantage of this conventional approach is that the force of a screw, which screws the reflector to the frame, will inevitably cause a yielding of the foil. As a result, the pretension of the screw is reduced, and the screw will get loose under dynamic load. Thus, on the one hand side the antenna may fall down. On the other hand side, screw connections in an antenna are always designed as face contact, because only such face contacts can be PIM stable. However, having a current run through a thread or a loose screw will create PIM. Therefore, the conventional approach is not well suited to address the above-mentioned problems.

SUMMARY

In view of the above-mentioned disadvantages and problems, the present invention aims to improve the state of the art. In particular, the object of the present invention is to provide a concept which improves the performance of an antenna by reducing its PIM level. In particular, the present invention desires to avoid, or at least strongly reduce the amount of, loose metal particles within the antenna after its assembly. Therefore, the present invention addresses the cause of such loose metal particles, namely abrasion between surfaces sliding against each other during assembly. In other words, the present invention is directed to avoiding a sliding contact between metal parts or abrasion.

The above-mentioned object of the present invention is achieved by the solution provided in the enclosed independent claims. Advantageous implementations of the present invention are further defined in the respective dependent claims. In particular, the core idea of the present invention is a spacer arranged between a frame and reflector of the antenna, which prevents abrasion, when the reflectors is inserted into a hull of the antenna, but allows a good face contact between the frame and the reflector, when the antenna is assembled.

A first aspect of the present invention provides a spacer for being arranged between a frame and a reflector of an antenna, the spacer being configured to separate the reflector and the frame, while the reflector is inserted into a hull of the antenna, and to allow at least one contact area of the reflector to touch at least one contact area of the frame, when the reflector is attached to the frame, and wherein a surface of the spacer is chosen such that abrasion of the frame is prevented, while the reflector is inserted into the hull. Due to the fact that the spacer separates the reflector and the frame, while the reflector is inserted into the hull, and the further fact that the surface of the spacer is selected such that abrasion of the frame is prevented, while the reflector is inserted into the hull, no loose metal particles will be created during the antenna assembly. Thus, the PIM level of the final antenna can be lowered, and the performance of the antenna decisively increased. Further, due to the fact that the spacer allows the one or more contact areas of the reflector and the frame to touch, it allows a good face contact after antenna assembly, and thus good PIM stability. In a first implementation form of the spacer according to the first aspect, the spacer is configured to be in sliding contact with the frame, while the reflector is inserted into the hull. Due to the sliding contact, the reflector can be precisely inserted into the hull in a well controlled manner. However, no abrasion of the frame occurs during the sliding, and thus no loose metal particles are created.

In a second implementation form of the spacer according to the first aspect as such or according to the first implementation form of the first aspect, at least the surface of the spacer comprises a softer material than the frame, so that abrasion of the frame is prevented, while the reflector is inserted into the hull.

By means of the spacer' s softer material, an abrasion of the frame (whereas the frame is preferably made of or at least comprises a conductive material like a metal) is prevented, and thus the performance of the antenna can be increased by lowering the PIM level.

In a third implementation form of the spacer according to the first aspect as such or according to any previous implementation forms of the first aspect, the spacer comprises at least one aperture, through which the at least one contact area of the reflector touches the at least one contact area of the frame, when the reflector is attached to the frame. The at least one aperture in the spacer allows a good face contact between the contact areas of the reflector and the frame, respectively, i.e. ensures a face contact that is PIM stable and has a low PIM level.

In a fourth implementation form of the spacer according to the first aspect as such or according to any previous implementation forms of the first aspect, the spacer comprises at least one protruding elastic element, which is configured to remain substantially undeformed, while the reflector is inserted into the hull, so that the reflector is separated from the frame. Substantially undeformed means in this respect that the at least one protruding elastic element can still separate reflector and frame. Due to this separation, abrasion of the frame is prevented as described above. In a fifth implementation form of the spacer according to the fourth implementation form of the first aspect, the at least one elastic element is configured to be deformed, when the reflector is attached to the frame, so that the at least one contact area of the reflector touches the at least one contact area of the frame. The elastic element thus ensures separation of the frame and the reflector during antenna assembly, but allows good face contact between the contact areas of reflector and frame in the assembled antenna. Such an elastic element, may be a spring a force of which is strong enough to separate reflector and frame, when the reflector is moved into the hull. However, when the reflector is fixed to the frame, a corresponding fixing element will apply a stronger fixing force such that the spring is pressed together and the reflector touches the frame, when the reflector and frame are fixed to each other.

In a sixth implementation form of the spacer according to the first aspect as such or according to any of the first to third implementation forms of the first aspect, the spacer comprises at least one protrusion, which is arranged to protrude in direction of the frame beyond the at least one contact area of the reflector, so that the reflector is separated from the frame, while the reflector is inserted into the hull.

By the separation of the frame and the reflector by the protrusion, abrasion of the frame and/or spacer during assembly, particularly during the insertion step of the reflector into the hull is prevented.

In a seventh implementation form of the spacer according to the first aspect as such or according to any previous implementation forms of the first aspect, at least the surface of the spacer is made of a non-conductive material.

If the spacer or at least its surface is made of a non-conductive material, PIM sources in the antenna can be avoided, even if some unintended or intended abrasion of the spacer occurs. This is due to the fact that PIM is only caused by loose conductive (e.g. metal) particles, but not non-conductive particles.

A second aspect of the present invention provides an antenna comprising a hull including a frame, a reflector, and a spacer according to the first aspect as such or according to any of the previous implementation forms of the first aspect, wherein the spacer is arranged in the hull between the frame and the reflector, so that the at least one contact area of the reflector touches the at least one contact area of the frame. The spacer prevents on the one hand side loose particles caused by abrasion during antenna assembly to remain within the antenna, and ensures on the other hand side a good face contact between the reflector and the frame after antenna assembly. Thereby, the PIM level of the antenna is lowered, and consequently its performance increased. In particular, the spacer allows the at least one contact area of the reflector and the at least one contact area of the frame to touch in a manner, such that a low impedance connection between reflector and frame is established.

In a first implementation form of the antenna according to the second aspect, the reflector comprises a reflector board and at least a further spacer attached to the reflector board, wherein the further spacer is attached to the frame, the at least one contact area of the reflector is provided on the further spacer, and the spacer at least partially surrounds the at least one contact area of the reflector and the at least one contact area of the frame. The at least one further spacer is, for example, at least one reflector foot provided on the reflector board. The at least one reflector foot separates the reflector and the frame in the antenna, but establishes an electrical contact between the two components.

In a second implementation form of the second aspect or according to the first implementation form of the second aspect, the reflector is attached to the frame by at least one fixing element through an opening in the at least one contact area of the reflector and an opening in the at least one contact area of the frame. The at least one fixing element may, for example, be one or more screws. The at least one fixing element provided through the opening ensures a good face contact between the contact areas of frame and reflector, respectively, and consequently a PIM stable connection.

In a third implementation form of the antenna according to the second implementation form of the second aspect, the spacer comprises at least one elastic element being configured to apply a first force between the reflector and the frame acting to separate the reflector and the frame, and wherein the at least one fixing element is configured to apply a second force acting to bring the reflector and the frame into contact, the second force being larger than the first force, such that the at least one contact area of the reflector touches the at least one contact area of the frame, when the fixing element is applied. These respective forces ensure that the at least one fixing element does not loosen, after the antenna has been assembled. Thereby, the antenna is firstly prevented from falling down, and secondly the at least one fixing element ensures a good and stable face connection between reflector and frame, and thus a PIM stable connection. Preferably, a force required to substantially deform the one or more elastic elements is larger than a force caused by the weight of the reflector, so that the one or more elastic elements can carry the weight of the reflector while inserting it into the hull of the antenna.

In a fourth implementation form of the antenna according to the second aspect as such or according to the first or second implementation forms of the second aspect, the spacer comprises at least one protrusion, which is protruding in direction of the frame beyond the at least one contact area of the reflector, and the frame comprises at least one recess, which is configured to receive the at least one protrusion of the spacer, when the reflector is attached to the frame, so that the at least one contact area of the reflector touches the at least one contact area of the frame.

When the at least one protrusion is received in the at least one recess, a good face contact between the contact areas of the reflector and the frame is established, respectively. In a fifth implementation form of the antenna according to the fourth implementation form of the second aspect, the spacer comprises multiple protrusions, the frame comprises multiple recesses, each recess being designed to receive one dedicated protrusion of the spacer, and the multiple protrusions and recesses are respectively configured so that an insertion of a protrusion into a not dedicated recess is prevented.

The multiple protrusions and recesses can, for example, be arranged in a staggered arrangement, so that during the assembly of the antenna a certain protrusion is never received in a not dedicated recess. Alternatively, different matching shapes can be selected for different protrusion-recess-pairs, wherein the protrusion has a shape that fits only in the paired dedicated recess. Thereby, an easy insertion of the reflector into the frame is enabled, and after antenna assembly, a good face contact is established between the two components.

A third aspect on the present invention provides a method of assembling an antenna, comprising providing a reflector with at least one spacer according to the first aspect as such or according to any implementation form of the first aspect, inserting the reflector into a hull, whereby the at least one spacer separates the reflector and a frame of the hull, and attaching the reflector to the frame, whereby the spacer is arranged in the hull between frame and reflector, so that the at least one contact area of the reflector touches the at least one contact area of the frame.

In a first implementation form of the method according to the third aspect, the reflector comprises a reflector board and at least a further spacer attached to the reflector board, the further spacer is attached to the frame, the at least one contact area of the reflector is provided on the further spacer, and the spacer is provided to at least partially surround the at least one contact area of the reflector and the at least one contact area of the frame.

In a second implementation form of the method according to the third aspect as such or according to the first implementation form of the third aspect, the reflector is attached to the frame by at least one fixing element through an opening in the at least one contact area of the reflector and an opening in the at least one contact area of the frame.

In a third implementation form of the method according to the second implementation form of the third aspect, the spacer is provided with at least one elastic element being configured to apply a first force between the reflector and the frame acting to separate the reflector and the frame, and wherein the at least one fixing element is provided to apply a second force acting to bring the reflector and the frame into contact, the second force being larger than the first force, such that the at least one contact area of the reflector touches the at least one contact area of the frame, when the fixing element is applied.

In a fourth implementation form of the method according to the third aspect as such or according to the first or second implementation form of the third aspect, the spacer is provided with at least one protrusion, which is protruding in direction of the frame beyond the at least one contact area of the reflector, the frame is provided with at least one recess, which is configured to receive the at least one protrusion of the spacer, when the reflector is attached to the frame, so that the at least one contact area of the reflector touches the at least one contact area of the frame.

In a fifth implementation form of the method according to the fourth implementation form of the third aspect, the spacer is provided with multiple protrusions, the frame is provided with multiple recesses, each recess being designed to receive one dedicated protrusion of the spacer, and the multiple protrusions and recesses are respectively designed so that an insertion of a protrusion into a not dedicated recess is prevented.

The method of the third aspect provides the same advantages as the spacer and antenna of the first aspect and second aspect, respectively. Particularly, the method of the third aspect results in a lower PIM level of the assembled antenna compared to the prior art, and consequently in an increased performance of the antenna.

It has to be noted that all devices, elements, units and means described in the present application could be implemented in the software or hardware elements or any kind of combination thereof. All steps which are performed by the various entities described in the present application as well as the functionalities described to be performed by the various entities are intended to mean that the respective entity is adapted to or configured to perform the respective steps and functionalities. Even if, in the following description of specific embodiments, a specific functionality or step to be full formed by eternal entities not reflected in the description of a specific detailed element of that entity which performs that specific step or functionality, it should be clear for a skilled person that these methods and functionalities can be implemented in respective software or hardware elements, or any kind of combination thereof.

BRIEF DESCRIPTION OF DRAWINGS

The above-described aspects and implementation forms of the present invention will be explained in the following description of specific embodiments in relation to the enclosed drawings, in which

Fig. la, lb show a basic embodiment of a spacer and an antenna, respectively, according to the present invention.

Fig. 2 shows a first specific embodiment of a spacer according to the present invention and its application.

Fig. 3a, 3b show a section view through the first specific embodiment of a spacer according to the present invention and its application.

Fig.4a-4d show a first specific embodiment of an assembly method according to the present invention.

Fig. 5a, 5b show in a section view the first specific embodiment of an assembly method according to the present invention.

Fig. 6a-6c show in another section view the first specific embodiment of an assembly method according to the present invention. Fig.7 shows a second specific embodiment of a spacer and an antenna, respectively, according to the present invention.

Fig. 8a, 8b show a section view of a second specific embodiment of an assembly method according to the present invention.

Fig.9 shows another section view of the second specific embodiment of a spacer and an antenna, respectively, according to the present invention. Fig. 10 shows a flow diagram of a basic embodiment of an assembly method according to the present invention.

Fig. 11 shows a conventional assembly method of an antenna.

DETAILED DESCRIPION OF EMBODIMENTS

Figs, la and lb show how a spacer 101 according to a basic embodiment of the present invention may be used during the assembly of an antenna 100. The spacer 101 is arranged between a frame 103 of the antenna 100 and a reflector 102 of the antenna 100. Both the reflector 102 and the frame 103 are preferably made at least partly (e.g. at least one the surface) of a metal or another conductive material, in order to establish an electrical connection between the reflector 102 and the frame 103 in the assembled antenna 100. For example, the frame 103 is preferably made at least partly of aluminum.

The spacer 101 is specifically designed to separate the reflector 102 and the frame 103, while the reflector 102 is inserted into a hull of the antenna 100. Fig. la and lb show how the frame 102 is particularly inserted into the hull of the antenna 100 by pushing the reflector 102 in direction of the arrow shown in Fig. la, so as to reach a position shown in Fig. lb. During the insertion of the reflector 102, the spacer 101 is preferably in sliding contact with the frame 103.

When the reflector 102 is inserted into the frame 103, as shown in Fig. lb, the reflector 102 may be attached to the frame 103, and the spacer 101 will allow, in the attached state, at least one contact area 104 of the reflector 102 to touch at least one contact area 605 (shown only in Figs. 6a and 6b due to better visibility) of the frame 103.

Since the spacer 101 may be in sliding contact with the frame 103 during insertion, the spacer 101 or at least a surface of the spacer 101 is made of a material that is selected such that abrasion of the frame 103 is prevented, while the reflector 102 is pushed into the antenna hull. For example, the spacer 101 as a whole, or at least a part of the spacer 101 like its surface, may be made of a softer material than the frame material, so that abrasion of the frame 103 is prevented. Preferably, the spacer 101 is made of a non- conductive material, while the frame 103 is made of a conductive material like a metal. For example, the spacer 101 can be made of plastic, which is firstly softer than metal, and which even when abraded only causes non-conductive loose particles in the assembled antenna, which do not influence the PIM level of the antenna. Fig. 2 shows a detailed view of a first specific embodiment of the spacer 101, which is based on the basic embodiment shown in the Figs, la and lb. In particular, Fig. 2 shows a spacer 101, which is provided with at least one protruding elastic element 202 for separating the reflector 102 and the frame 103 during antenna assembly, and for being pressed together in a final assembly state to allow good face contact between reflector 102 and frame 103. The spacer 101 shown in Fig. 2 is provided, as an example, with six protruding elastic elements 202. The elastic elements 202 are preferably configured to remain substantially undeformed, while the reflector 102 is inserted into the hull of the antenna 100, which means that the elastic elements 202 are at least together strong enough to separate the reflector 102 and the frame 103, even though the weight of the reflector 102 or the frame 103 acts on the elastic elements 202. Hence, the number of elastic elements 202 for a spacer 101 can be chosen in dependence on the number of spacer 101 used between reflector 102 and frame 103, the material of the elastic elements 202 and the weight of the reflector board (e.g. with antenna elements, such as dipoles, arranged on it).

Furthermore, as can be seen in this and the following examples, the spacer 101 can be produced made from a single piece. This achieves very low productions costs, as there are not assembly costs for the spacer 101 itself are involved. The spacer 101 is further provided with at least one aperture 201, in order to allow at least one contact area 104 of the reflector 102 to touch at least one contact area 605 of the frame 103, when the reflector 102 is attached to the frame 103. The spacer 101 shown in Fig. 2 is provided, as an example, with two apertures 201, the reflector 102 is accordingly provided with two contact areas 104. The two contact areas 104 can touch contact areas 605 of the frame 103 through the two apertures 201, when the reflector 102 is attached to the frame 103. The two contact areas 104 are to this end preferably provided as protrusions protruding from the reflector 102, and have a shape corresponding to the apertures 201, so that they can each fit through one aperture 201 of the spacer 101. The number of apertures 201 in the spacer 101 can be chosen in dependence on the required face contact and also in dependence on the size of the apertures 201.

The reflector 102 may comprise a reflector board and at least a further spacer 203, which is preferably designed as at least one reflector foot. In Fig. 2 specifically one reflector foot is shown. The reflector foot is attached to the reflector board by a fixing element 204, preferably a screw, and may be attached to the frame 103 by another fixing element, preferably another screw, when the antenna 100 is assembled. The contact areas 104 of the reflector 102 may be provided, as shown in Fig. 2, on the reflector foot. The spacer 101 is preferably designed to at least partially surround the contact areas 104 of the reflector 102, particularly by, for example, being able to partially surround the reflector foot as shown in Fig. 2. When the antenna 100 is assembled, the spacer 101 also preferably surrounds at least partially the contact areas 605 of the frame 103.

Fig. 3a and 3b show more details in this respect. In particular, Fig. 3a and 3b show an intersection through the spacer 101 and the reflector foot of Fig. 2, respectively, and show how the spacer 101 can be provided on the reflector 102, in order to separate the reflector 102 and the frame 103 during antenna assembly. That is, in Figs. 3a and 3b the spacer 101 is fixed to the reflector foot by partially surrounding it, and while the reflector 102 is not attached to the frame 103, the elastic elements 202 of the spacer 101 push it away from the reflector foot in direction of the frame 103. In particular, as can be seen in the Figs. 4a - 4c showing steps of assembly of the antenna 100, the elastic elements 202 of the spacer 101 are configured to apply a force between the reflector 102 and the frame 103, which acts to separate the reflector 102, i.e. particularly the reflector foot, and the frame 103. Thus, the reflector 102 can be pushed into the antenna hull as shown in the Figs. 4a-4c, whereby the spacer 101 is preferably in a sliding contact with the frame 103. When the reflector 102 reaches the final assembly position within the hull, as shown in Fig. 4d, the reflector 102 can be attached to the frame 103 by at least one fixing element 401, preferably at least one screw. In Fig. 4d specifically, as an example, two screws are used, each provided through one contact area 104 of the reflector 102 and one contact area 605 of the frame 103 and through one aperture 201 of the spacer 101.

The screws are preferably configured to apply a force, which acts to bring the reflector 102, i.e. particularly the reflector foot, and the frame 103 into contact, i.e. to make their contact areas 104 and 605, respectively, touch. Thereby, the force of the screws is preferably selected to be larger than the force provided by the elastic elements 202, so that the contact areas 104 of the reflector 102 and the contact areas 605 of the frame 103 not only touch, but also establish a good face contact. In other words, the elastic elements 202 are preferably strong enough to carry the weight of the reflector 102 and/or the frame 103. But the fixing elements 401 are chosen to overcome the force of the elastic elements 202 such that a good face contact between reflector 102 and frame 103 is established.

Figs. 5a and 5b show a further intersection through the reflector 102, the spacer 101 and the frame 103. In Fig. 5a the reflector 102 is not yet attached to the frame 103, and the spacer 101 still separates the frame 103 from the reflector 102, particularly the reflector foot, by means of the elastic elements 202. The same is shown in Fig. 5b. It can also be seen that the reflector foot is connected to the reflector board of the reflector 102 by a fixing element 204, preferably a screw, and that the frame 103 is provided preferably with a bracket 501, which is suitable to mount the antenna 100 (e.g. to an antenna pole).

In the Figs. 6a - 6c is shown how one of the fixing elements 401 shown in fig. 4d, which are designed as screws, is provided through an opening in one of the contact areas 104 of the reflector 102, of the apertures of the spacer 101 and an opening in one of the contact areas 605 of the frame 103, in order to attach the frame 103 to the reflector 102, particularly to the reflector foot. When the screws are fixed, the elastic elements 202 of the spacer 101 are substantially deformed, i.e. are pressed together, so that the contact areas 104 and 605 of respectively reflector 102 and frame 103 touch. The contact areas 104 and 605 are preferably each provided with a silver layer or are otherwise refined, in order to allow a low impedance connection between the frame 103 and the reflector 102. Preferably, a roughness of the contact areas 104 and 605 is eliminated, or at least lowered. When pressed together, the contact areas 104 and 605 of the reflector 102 and the frame 103, respectively, provide a low impedance connection, which leads to a PIM stable contact between the frame 103 and the reflector 102. In order to allow such a stable and low impedance contact, the force of the fixing elements (e.g. screws) 401 is preferably at least 100 times higher, more preferably at least 200 times higher, even more preferably at least 500 times higher than the force of the elastic elements 202, so that no pretension of the screws is lost.

Fig. 7 shows a second specific embodiment of the spacer 101, which is based on the basic embodiment of Figs la and la, for assembling the antenna 100. The second specific embodiment of the spacer 101 is identical to a large extent to the first specific embodiment of the spacer 101 shown in Fig. 2. However, instead of elastic elements 202, the spacer 101 of the second embodiment is provided with at least one protrusion 701. Specifically, in Fig. 7 the spacer 101 is, as an example, provided with two protrusions designed as overlapping knobs. The two protrusions 701 prevent the contact areas 104 of the reflector 102 and the contact areas 605 of the frame 103 to touch, while the reflector 102 is moved into the antenna hull. In particular, the protrusions 701 are arranged to protrude in direction of the frame 103 beyond the contact areas 104 of the reflector 102, so that the reflector 102 is separated from the frame 103, while the reflector 102 is inserted into the hull. Fig. 7 shows the situation while inserting the reflector 102 into the hull, as indicated by the arrow. The protrusions 701 are preferably in sliding contact with the frame 103, but the contact areas 104 do not touch the frame 103. The frame 103 in this embodiment further has at least one recess 702, which is configured to receive the at least one protrusion 701 of the spacer 101, when the reflector 102 is attached to the frame 103. Generally, the frame 103 has at least the same number of recesses 702 as the number of protrusions 701 provided on the spacer 101. Accordingly, Fig. 7 specifically shows, as an example, two recesses 702 in the frame 103. As with the embodiments before, the number of protrusions 701 and the number of apertures of the spacer 101 can be chosen in dependence on the application of the spacer 101.

Fig. 7 further shows that the reflector 102 preferably comprises a reflector board and a further spacer 203, designed for example as a reflector foot, which is preferably attached to the reflector board by a screw 204. On the reflector board at least one dipole 704 may be provided. The reflector board 102 is pushed into a radome 703 of the antenna 100, which comprises the frame 103. In Fig. 7, as a part of the screws for attaching the reflector 102 to the frame 103, a nut is shown, which may even be an integral part of the further spacer 203. In Fig. 8a, the reflector 102 is pushed further into the hull, whereby the spacer 101 slides with the protrusions 701 touching the frame 103. When in Fig. 8a the reflector 102 reaches the final position within the hull, the protrusions 701 of the spacer 101 slide into the recesses 702 of the frame 103, which may be simple cavities in the frame 103. This leads to the contact areas 104 of the reflector 102 and the contact areas 605 of the frame 103 to touch. Hence, the depths of the recesses 702 are chosen to be at least as large as the heights of their dedicated protrusions 701.

In Fig. 9 the final assembly position is shown, in which the reflector 102 may be fixed to the frame 103 by the fixing elements 401 designed as screws. The protrusions 701 are within the recesses 702 and allow the contact areas 104 of the reflector 102, which are provided on the further spacer 203, to touch the contact areas 605 of the frame 103. Due to the force of the screws, a low impedance connection can be established.

The spacer 101 may also comprise a plurality of protrusions 701, which are designed to be inserted into a plurality of recesses 702. That means each recess 702 may be designed to receive one dedicated protrusion 701 of the spacer 101. In order to prevent that such multiple protrusions 701 and recesses 702 hinder the insertion of the reflector 102 into the hull, the multiple protrusions 701 and recesses 702 are preferably configured such that insertion of a certain protrusion 701 is not possible into a not dedicated recess 702. For example, each protrusion 701 may have a corresponding recess 702, which has a form that can receive only the corresponding protrusion 701. Other protrusion-recess-pairs may be designed differently, i.e. have different forms. The protrusions 701 on the spacer 101 and/or the recesses 702 on the frame 103 can also (e.g. additionally or instead) be arranged in a staggered manner, so that protrusions 701 can only be inserted into specific dedicated recesses 702, when the reflector 102 is inserted fittingly into the hull.

Fig. 10 shows a basic assembling method 1000 of an antenna 100 by using a spacer 101 according to the embodiments described above. In a first step 1001, the reflector

102 is provided with the spacer 101. In a second step 1002, the reflector 102 is inserted into the hull of the antenna 100. The hull includes a frame 103. The spacer 101 is designed to separate the reflector 102 and the frame 103, while the reflector 102 is inserted into the hull. In a third step 1003, the reflector 102 and the frame 103 are attached to another, whereby the spacer 101 is arranged in the hull between the frame

103 and the reflector 102, and allows at least one contact area 104 of the reflector 102 to touch at least one contact area 605 of the frame 103. A surface of the spacer 101 is chosen such that abrasion of the frame 103 is prevented, while the reflector 102 is inserted into the hull.

By the above-described embodiments of the present invention, an antenna 100 with improved performance due to a lower PIM level is provided. This is particularly due to the fact that the spacer prevents abrasion of reflector 102 and frame 103 during assembly, and thus prevents that loose particles remain in the assembled antenna 100, which may be the cause of PIM, specifically if made of conductive materials like metal.

The present invention has been described in conjunction with various embodiments as examples as well as implementations. However, other variations can be understood and effected by those persons skilled in the art and practicing the claimed invention, from the studies of the drawings, this disclosure and the independent claims. In the claims as well as in the description the word "comprising" does not exclude other elements or steps and the indefinite article "a" or "an" does not exclude a plurality. A single element or other unit may fulfill the functions of several entities or items recited in the claims. The mere fact that certain measures are recited in the mutual different dependent claims does not indicate that a combination of these measures cannot be used in an advantageous implementation.

Claims

1. Spacer (101) for being arranged between a frame (103) and a reflector (102) of an antenna (100),

the spacer (101) being configured to separate the reflector (102) and the frame (103), while the reflector (102) is inserted into a hull of the antenna (100), and to allow at least one contact area (104) of the reflector (102) to touch at least one contact area (605) of the frame (103), when the reflector (102) is attached to the frame (103); and wherein a surface of the spacer (101) is chosen such that abrasion of the frame

(103) is prevented, while the reflector (102) is inserted into the hull.

2. Spacer (101) according to claim 1, wherein

the spacer (101) is configured to be in sliding contact with the frame (103), while the reflector (102) is inserted into the hull.

3. Spacer (101) according to claim 1 or 2, wherein

at least the surface of the spacer (101) comprises a softer material than the frame (103), so that abrasion of the frame (103) is prevented, while the reflector (102) is inserted into the hull.

4. Spacer (101) according to one of the claims 1 to 3, wherein

the spacer (101) comprises at least one aperture (201), through which the at least one contact area (104) of the reflector (102) touches the at least one contact area (605) of the frame (103), when the reflector (102) is attached to the frame (103).

5. Spacer (101) according to one of the claims 1 to 4, wherein

the spacer (101) comprises at least one protruding elastic element (202), which is configured to remain substantially undeformed, while the reflector (102) is inserted into the hull, so that the reflector (102) is separated from the frame (103).

6. Spacer (101) according to claim 5, wherein the at least one elastic element (202) is configured to be deformed, when the reflector (102) is attached to the frame (103), so that the at least one contact area (104) of the reflector (102) touches the at least one contact area (605) of the frame (103).

7. Spacer (101) according to one of the claims 1 to 4, wherein

the spacer (101) comprises at least one protrusion (701), which is arranged to protrude in direction of the frame (103) beyond the at least one contact area (104) of the reflector (102), so that the reflector (102) is separated from the frame (103), while the reflector (102) is inserted into the hull.

8. Spacer (101) according to one of the claims 1 to 7, wherein

at least the surface of the spacer (101) is made of a non-conductive material.

9. Antenna (100) comprising

a hull including a frame (103);

a reflector (102); and

a spacer (101) according to one of the preceding claims, wherein the spacer (101) is arranged in the hull between the frame (103) and the reflector (102), so that the at least one contact area (104) of the reflector (102) touches the at least one contact area (605) of the frame (103).

10. Antenna (100) according to claim 9,

wherein the reflector (102) comprises a reflector board and at least a further spacer (203) attached to the reflector board,

wherein the further spacer (203) is attached to the frame (103),

wherein the at least one contact area (104) of the reflector (102) is provided on the further spacer (203), and

wherein the spacer (101) at least partially surrounds the at least one contact area (104) of the reflector (102) and the at least one contact area (605) of the frame (103).

11. Antenna (100) according to claim 9 or 10, wherein the reflector (102) is attached to the frame (103) by at least one fixing element (401) through an opening in the at least one contact area (104) of the reflector (102) and an opening in the at least one contact area (605) of the frame (103).

12. Antenna (100) according to claim 11,

wherein the spacer (101) comprises at least one elastic element (202) being configured to apply a first force between the reflector (102) and the frame (103) acting to separate the reflector (102) and the frame (103), and

wherein the at least one fixing element (401) is configured to apply a second force acting to bring the reflector (102) and the frame (103) into contact, the second force being larger than the first force, such that the at least one contact area (104) of the reflector (102) touches the at least one contact area (605) of the frame (103), when the fixing element (401) is applied.

13. Antenna (100) according to one of claims 9 to 11, wherein

the spacer (101) comprises at least one protrusion (701), which is protruding in direction of the frame (103) beyond the at least one contact area (104) of the reflector (102),

the frame (103) comprises at least one recess (702), which is configured to receive the at least one protrusion (701) of the spacer (101), when the reflector (102) is attached to the frame (103), so that the at least one contact area (104) of the reflector (102) touches the at least one contact area (605) of the frame (103).

14. Antenna (100) according to claim 13, wherein

the spacer (101) comprises multiple protrusions (701),

the frame (103) comprises multiple recesses (702), each recess (702) being designed to receive one dedicated protrusion (701) of the spacer (101), and

the multiple protrusions (701) and recesses (702) are respectively configured so that an insertion of a protrusion (701) into a not dedicated recess (702) is prevented.

15. Method (1000) of assembling an antenna (100), comprising

providing (1001) a reflector (102) with at least one spacer (101) according to one of the claims 1 to 7, inserting (1002) the reflector (102) into a hull, whereby the at least one spacer (101) separates the reflector (102) and a frame (103) of the hull, and

attaching (1003) the reflector (102) to the frame (103), whereby the spacer (101) is arranged in the hull between frame (103) and reflector (102), so that the at least one contact area (104) of the reflector (102) touches the at least one contact area (605) of the frame (103).