AN ANTENNA SYSTEM FOR A BASE STATION

TECHNICAL FIELD

Generally, the present invention relates to the field of wireless communications. More specifically, the present invention relates to an antenna system for a base station of a wireless communication network and a method of manufacturing such an antenna system.

BACKGROUND

Antenna systems (or short antennas) for base stations used in mobile communication networks are typical array antennas which consist of several dipoles (i.e. radiation elements) in a cross configuration for generating a +45° and -45° polarization of radio frequency (RF) signals. In some antenna designs, the radiation elements are connected directly or in groups to a signal distribution network (SDN). The SDN (sometimes also referred to as phase shifter) may be configured to alter the phase of the signals for exciting the dipoles electronically. A cavity defined by a metal housing of an antenna system for receiving a SDN has to be closed, i.e. "RF sealed" over the whole length of the antenna array. Usually, only small openings are possible.

Figure 1 shows different views of manufacturing stages of a conventional antenna system comprising a metal housing 10 and a reflector 11 defining a top portion of the housing 10, wherein radiation elements (e.g. dipoles) are arranged above the reflector 11. The housing 10 defines a cavity for receiving a SDN 13 in the form of a sheet metal or printed circuit board (PCB). For the conventional antenna system shown in figure 1 the SDN 13 is inserted into the cavity defined by the housing 10 via a side opening of the housing. Once the SDN 13 has been fully inserted into the cavity defined by the housing 10, the SDN 13 is moved upwards such that connection portions 13a of the SDN 13 extend through apertures 11 a of the reflector 11. These connection portions 13a may be connected to the dipole elements on top of the reflector 11 via a further PCB 14 soldered to the connection portions 13a for connecting the SDN 13 with the dipole elements.

An issue with this conventional way of manufacturing an antenna system is illustrated in figure 2, which shows schematic views of a portion of the antenna system during two different manufacturing stages. More specifically, an upper portion of figure 2 illustrates a schematic cross section of the housing 10 during a first manufacturing stage, where the SDN 13 is inserted sidewards into the cavity defined by the housing 10. A lower portion of figure 2 illustrates a schematic cross section of the housing 10 during a second manufacturing stage, where the SDN 13 is moved upwards in the direction of the reflector 11 so that the plurality of connection portions 13a of the SDN 13 extend through the plurality of apertures 11 a of the reflector 11 (as already described in the context of figure 1). As will be appreciated, once the SDN 13 has reached its final position illustrated in the lower portion of figure 2, there will be a clearance 16 between the bottom portion of the SDN 13 and the bottom wall of the housing 10 resulting in a bulky antenna system.

SUMMARY

It is an objective of the present disclosure to provide a compact antenna system, for instance, for a base station of a wireless communication network and a method of manufacturing such an antenna system.

The foregoing and other objectives are achieved by the subject matter of the independent claims. Further implementation forms are apparent from the dependent claims, the description and the figures.

According to a first aspect an antenna system for emitting and receiving radio frequency, RF, waves is provided. The antenna system comprises a plurality, e.g. an array of electrically conductive radiation elements (also referred to as antenna elements) configured to emit and receive RF waves.

Moreover, the antenna system comprises an extended metallic reflector, wherein the plurality of radiation elements are arranged on a top side of the reflector such that the RF waves emitted by the plurality of electrically conductive radiation elements are reflected by the reflector into a main radiation direction of the antenna system.

The antenna system further comprises a housing comprising a plurality of metallic solid side walls defining a cavity on a bottom side of the reflector, wherein a signal distribution network (SDN) is arranged within the cavity and configured to feed a plurality of electrical signals to the plurality of radiation elements. The extended metallic reflector comprises a plurality of reflector apertures for galvanically or capacitively connecting, i.e. coupling the signal distribution network arranged within the cavity with the plurality of radiation elements. The signal distribution network comprises a plurality of connection portions, wherein each connection portion is configured to galvanically or capacitively connect through a respective reflector aperture a respective radiation element of the plurality of radiation elements on the top side of the reflector with the signal distribution network housed within the cavity defined by the housing on the bottom side of the reflector.

The housing further comprises a flexible foil capacitively coupled to a top portion or a bottom portion of the housing for closing the cavity that is housing the signal distribution network and electrically decoupling the signal distribution network inside the housing. The flexible foil capacitively coupled to a top portion or a bottom portion of the housing for closing the cavity allows for a very compact design of the housing and, thus, the overall antenna system.

In a further possible implementation form, the flexible foil is capacitively coupled to the top portion of the housing, wherein first portions of the flexible foil are capacitively coupled to portions of the top surface of the reflector and second portions of the flexible foil are capacitively coupled to the top portion of the housing for closing the cavity housing the signal distribution network. This allows an efficient RF sealing of the top portion of the housing and, thus, the SDN within the cavity.

In a further possible implementation form, the flexible foil is bonded to the housing. This allows fixing the flexible foil to the housing in an efficient and robust manner.

In a further possible implementation form, the housing is an extrusion profile or sheet metal. This allows providing the housing in an efficient manner.

In a further possible implementation form, the housing comprises an aluminium metal.

This allows providing a light-weight housing having the desired electrical properties.

In a further possible implementation form, the reflector has a substantially planar top surface facing the plurality of radiation elements. This allows providing the reflector in an efficient manner. In a further possible implementation form, the main radiation direction of the antenna system substantially corresponds to a normal direction of the substantially planar top surface of the reflector.

In a further possible implementation form, the signal distribution network comprises a planar printed circuit board, PCB, metallized foil, or sheet metal and wherein the plurality of metallic solid side walls extend substantially in parallel with the planar PCB. This allows providing the SDN in an efficient manner.

In a further possible implementation form, a height of the plurality of metallic solid side walls is substantially identical to a height of the planar PCB. This allows for a very compact design of the housing and, thus, the antenna system.

In a further possible implementation form, the flexible foil comprises a first foil layer and a second foil layer, wherein the first foil layer comprises a dielectric material and is in contact with the bottom portion or the top portion of the housing for holding the signal distribution network within the housing and wherein the second foil layer comprises a metal material.

In a further possible implementation form, the respective connection portion of the plurality of connection portions of the signal distribution network is soldered or capacitively coupled to a connection portion of a respective radiation element.

In a further possible implementation form, the plurality, e.g. the array of electrically conductive radiation elements comprises one or more dipole elements.

According to a second aspect an access point, i.e. base station for a mobile communication network is provided comprising an antenna system according to the first aspect.

According to a third aspect a method for manufacturing an antenna system is provided. The method comprises the steps of: arranging a plurality of electrically conductive radiation elements configured to emit and receive radio frequency, RF, waves on a top side of an extended metallic reflector such that the RF waves emitted by the plurality of electrically conductive radiation elements are reflected by the extended metallic reflector into a main radiation direction of the antenna system, wherein the extended metallic reflector comprises a plurality of reflector apertures; arranging a housing on a bottom side of the reflector, wherein the housing comprises a plurality of metallic solid side walls defining a cavity; inserting a signal distribution network into the cavity via an open bottom portion or an open top portion of the housing, wherein the signal distribution network comprises a plurality of connection portions, wherein each connection portion is configured to galvanically or capacitively connect through a respective reflector aperture a respective radiation element of the plurality of radiation elements on the top side of the reflector with the signal distribution network and configured to feed one or more electrical signals to the plurality of radiation elements; and closing the open bottom portion or the open top portion of the housing by capacitively coupling a flexible foil to the bottom portion or the top portion of the housing for holding, e.g. fixing the signal distribution network within the housing.

Details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description, drawings, and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, embodiments of the present disclosure are described in more detail with reference to the attached figures and drawings, in which:

Fig. 1 shows different views of portions of a conventional antenna system during different manufacturing stages;

Fig. 2 illustrates an issue of conventional antenna system of figure 1 ;

Fig. 3 shows different views of portions of an antenna system according to an embodiment during different manufacturing stages; Fig. 4 illustrates some further details of the antenna system of figure 3;

Fig. 5 shows different views of portions of an antenna system according to a further embodiment during different manufacturing stages; and

Fig. 6 is a flow diagram illustrating a method for manufacturing an antenna system according to an embodiment.

In the following identical reference signs refer to identical or at least functionally equivalent features.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the following description, reference is made to the accompanying figures, which form part of the disclosure, and which show, by way of illustration, specific aspects of embodiments of the present disclosure or specific aspects in which embodiments of the present disclosure may be used. It is understood that embodiments of the present disclosure may be used in other aspects and comprise structural or logical changes not depicted in the figures. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present disclosure is defined by the appended claims.

For instance, it is to be understood that a disclosure in connection with a described method may also hold true for a corresponding device or system configured to perform the method and vice versa. For example, if one or a plurality of specific method steps are described, a corresponding device may include one or a plurality of units, e.g. functional units, to perform the described one or plurality of method steps (e.g. one unit performing the one or plurality of steps, or a plurality of units each performing one or more of the plurality of steps), even if such one or more units are not explicitly described or illustrated in the figures. On the other hand, for example, if a specific apparatus is described based on one or a plurality of units, e.g. functional units, a corresponding method may include one step to perform the functionality of the one or plurality of units (e.g. one step performing the functionality of the one or plurality of units, or a plurality of steps each performing the functionality of one or more of the plurality of units), even if such one or plurality of steps are not explicitly described or illustrated in the figures. Further, it is understood that the features of the various exemplary embodiments and/or aspects described herein may be combined with each other, unless specifically noted otherwise. Figure 3 shows different views of portions of an antenna system according to an embodiment during different manufacturing stages of the antenna system. The antenna system comprises a plurality of radiation elements configured to emit and receive radio frequency (RF) waves. In an embodiment, the plurality of radiation elements may comprise one or more dipole elements. In an embodiment, the antenna system may be a component of a base station for a wireless communication network, such as a 3GPP or IEEE 802.11 wireless communication network.

As will be described in more detail in the following under reference to figure 3, the antenna system further comprises a reflector 110, wherein the plurality of radiation elements, e.g. dipole elements are arranged on a top side of the reflector 110 such that the RF waves emitted by the plurality of radiation elements are reflected by the reflector 110 into a main radiation direction of the antenna system. In an embodiment, the reflector 110 may have a substantially planar top surface. For such an embodiment, the main radiation direction of the antenna system substantially corresponds to a normal direction of the substantially planar top surface of the reflector 110.

The antenna system further comprises a housing 100 with a plurality of metallic solid side walls 100a defining a cavity on a bottom side of the reflector 110. As can be taken from the middle and the right portion of figure 3, a signal distribution network (SDN) 130 is arranged within the cavity defined by the housing 100 and configured to feed a plurality of electrical signals to the plurality of radiation elements located above the top surface of the reflector 110. In an embodiment, the SDN 130 may be implemented as a phase shifter configured to alter the phases of the respective electrical signals for the dipoles in a controlled manner.

As illustrated by the left portion of figure 3, the SDN 130 is inserted from the bottom into the cavity defined by the housing 100. In an embodiment, the SDN 130 may be implemented as a planar printed circuit board, PCB, metallized foil, or sheet metal such that the plurality of metallic solid side walls 110a of the housing 100 extend substantially in parallel with the planar PCB 130, as illustrated in figure 3. In an embodiment, the height of the plurality of metallic solid side walls 110a of the housing 100 is substantially identical to a height of the planar PCB 130 (without the connection portions 130a described in more detail below). In the embodiment shown in figure 3, the housing 100 comprises in addition to the plurality of metallic solid side walls 100a one or more top walls 100b extending at least partially in parallel with the planar reflector 110 (wherein apertures are provided in the one or more top walls 100b corresponding in size and/or location to the plurality of reflector apertures 110a of the reflector 110). In an embodiment, an insulating layer may be provided between the one or more top walls 110b and the planar reflector 110. In an embodiment, the housing 100 may be an extrusion profile or sheet metal. In an embodiment, the housing 100 may comprise an aluminium metal.

In order to allow the SDN 130 to feed a plurality of electrical signals to the plurality of radiation elements located above the top surface of the reflector 110, the reflector 110 comprises a plurality of reflector apertures 110a (only one shown in the schematic cross- sectional views of figure 3) for receiving correspondingly shaped connection portions 130a defining an upper portion of the SDN 130. Each connection portion 130a of the SDN 130 is configured to couple a respective radiation element of the plurality of radiation elements through a respective reflector aperture 110a with the SDN 130. In an embodiment, a respective connection portion of the plurality of connection portions 130a of the SDN 130 may be soldered or capacitively coupled to a respective radiation element.

As can be taken from the right portion of figure 3, the antenna system further comprises a flexible foil 120 capacitively coupled to a bottom portion of the housing 100 for closing the cavity accommodating the SDN 130. Some further details of the flexible foil 120 and the capacitively coupling of the flexible foil 120 to the bottom portion of the housing 100 are illustrated in figure 4. In an embodiment, the flexible foil 120 may be bonded to the bottom portion of the housing 100. As illustrated in the right portion of figure 4, the flexible foil 120 may comprise a first foil layer 120b and a second foil layer 120a, wherein the first foil layer 120b comprises a dielectric isolating material and is in contact with the bottom portion of the housing 100 for holding the SDN 130 within the housing 100 and wherein the second foil layer 120a comprises a metal material. In an embodiment, the metalized flexible foil 120 creates a capacitive contact over the whole length of the housing 100. In embodiment, the metalized flexible foil 120 defines connection with low tolerances between the connecting layers (i.e. housing surface to flexible foil 120). The flexibility of the foil 120 may eliminate these tolerances.

Figure 5 shows different views of portions of an antenna system according to a further embodiment during different manufacturing stages. The main difference between the embodiment shown in figure 5 and the embodiment shown in figures 3 and 4 is that in the embodiment shown in figure 5 the SDN 130 is inserted via an opening in the reflector 110 and the top portion of the housing 100 into the cavity defined by the housing 100. As will be appreciated from the cross-sectional schematic views shown in figure 5, for inserting the planar SDN 130 from the top into the cavity defined by the housing 100 the opening in the reflector 110 and the top portion of the housing 100 must be larger than the width of the planar SDN 130. The bottom portion of the housing 100 may be completely closed by a bottom wall 100c.

Once the SDN 130 has been inserted from the top into the cavity defined by the housing 100, the flexible foil 120 is capacitively coupled to the top portion 100b of the housing 100. In an embodiment, first portions of the flexible foil 120 are capacitively coupled to portions of the top surface of the reflector 110, while second portions of the flexible foil 120 are capacitively coupled to the top portion 100b of the housing 100 for closing the cavity accommodating the SDN 130.

Figure 6 is a flow diagram illustrating a method 600 for manufacturing an antenna system according to an embodiment. The method 600 comprises a step 601 of arranging a plurality of radiation elements, e.g. dipole elements configured to emit and receive RF waves on a top side of the reflector 110 such that the RF waves emitted by the plurality of radiation elements are reflected by the reflector 110 into a main radiation direction of the antenna system. As already described above, the reflector 110 comprises a plurality of reflector apertures 110a.

The method 600 comprises a further step 603 of arranging the housing 100 on a bottom side of the reflector 110, wherein the housing 100 comprises a plurality of metallic solid side walls 100a defining a cavity.

Moreover, the method 600 comprises a step 605 of inserting the signal distribution network 130 into the cavity via an open bottom portion or an open top portion of the housing 100. The SDN 130 comprises a plurality of connection portions 130a, wherein each connection portion is configured to couple through a respective reflector aperture 110a a respective radiation element of the plurality of radiation elements with the signal distribution network 130 and configured to feed one or more electrical signals to the plurality of radiation elements. The method 600 comprises a further step 607 of closing the open bottom portion or the open top portion of the housing 100 by capacitively coupling the flexible foil 120 to the bottom portion or the top portion of the housing 100 for holding the SDN 130 within the housing 100.

The person skilled in the art will understand that the "blocks" ("units") of the various figures (method and apparatus) represent or describe functionalities of embodiments of the present disclosure (rather than necessarily individual "units" in hardware or software) and thus describe equally functions or features of apparatus embodiments as well as method embodiments (unit = step).

In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus, and method may be implemented in other manners. For example, the described embodiment of an apparatus is merely exemplary. For example, the unit division is merely logical function division and may be another division in an actual implementation. For example, a plurality of units or components may be combined or integrated into another system, or some features may be ignored or not performed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections may be implemented by using some interfaces. The indirect couplings or communication connections between the apparatuses or units may be implemented in electronic, mechanical, or other forms.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one position, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the objectives of the solutions of the embodiments.

In addition, functional units in the embodiments of the invention may be integrated into one processing unit, or each of the units may exist alone physically, or two or more units are integrated into one unit.