WO2013026204A1

WO2013026204A1 - Antenna assembly

Info

Publication number: WO2013026204A1
Application number: PCT/CN2011/078890
Authority: WO
Inventors: Stephen Haworth
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2011-08-25
Filing date: 2011-08-25
Publication date: 2013-02-28
Also published as: EP2676328B1; EP2676328A1; EP2676328A4; CN103718378A; CN103718378B

Abstract

The present invention relates to an antenna assembly for wireless communication systems, comprising an antenna part and an antenna signal processing part together forming an integrated antenna assembly; said antenna part comprising at least one antenna element adapted for receiving/transmitting wireless communication signals, and said antenna signal processing part comprising at least one processing unit adapted for signal processing communication signals to and/or from said at least one antenna element; wherein said antenna part and said antenna signal processing part being attached to each other and separated from each other by means of an intermediate cover (C) located between said antenna part and said antenna signal processing part; and said antenna assembly further comprises a first gasket (G1) and a second gasket (G2) for sealing said antenna assembly, said first gasket (G1) being arranged to act in a first direction (D1) on said intermediate cover (C), and said second gasket (G2) being arranged to act in a second direction (D2) on said intermediate cover (C), said second direction (D2) being substantially opposite to said first direction (D1).

Description

ANTENNA ASSEMBLY

Technical Field

The present invention relates to an antenna assembly for wireless communication systems, and more especially to an integrated antenna assembly.

Background of the Invention

Traditionally, an antenna is a passive component in a wireless communication system. Communication cables from the antenna feed radio frequency signals to a Remote Radio Unit (RRU) which is located a distance from the antenna. The further the RRU from the antenna the larger the loss in the signal reception and transmission due to e.g. resistance in the communication cables. Typical functionalities of a RRU is e.g. filtering and converting of analogue radio frequency signals to digital signals, baseband processing of incoming data, signal processing, and signal strength boosting of transmission signals, etc. Figure 1 schematically shows a traditional antenna system with a passive antenna unit connected to a RRU via a communication cable.

Therefore, to reduce mentioned signal loss and improve overall performance and power consumption so called active antenna systems has been proposed. An active antenna system integrates one or more of the functionalities of a RRU with the passive antenna and allows for other performance enhancements. In this respect, the RRU comprises active electronics, such as power amplifiers, signal processing devices, AD converters, high speed fibre optic devices and power supply. However, the inclusion of active electronics within the integrated antenna requires that the antenna housing has the same environmental protection classification required as for the RRU.

In prior art passive antenna designs, the housing simply encases the antenna array from the outdoor environment, since the antenna is a passive part of the network and does not house active electronics. Passive antennas require a level of outdoor environmental protection to prevent corrosion of elements and contacts, but it does not need to be fully sealed against water or dust ingress as there are no active electrical components in a passive antenna. However, active antennas having active electronics have to be sealed against water and dust ingress. Furthermore, the introduction of active electronics into the antenna also require cooling of the electronics, which adds a further level of complexity to the antenna design, including the incorporation of a heat sink which is exposed to the air to allow for natural convection cooling of the active components of the antenna. The height of such antenna array is often over 1 meter in height and manufacturing tolerances of long heat sinks increase the risk that gaps will appear between the cover (radome) and the heat sink leading to water and dust ingress that cannot be solved by traditional antenna construction techniques. This additional level of complexity to the antenna design requires even a higher level of environmental protection from dust and water ingress.

Summary of the Invention

The object of the present invention is to provide an antenna assembly which mitigates and/or solves the disadvantages of prior art solutions. The invention especially aims to solve the problem of sealing integrated active antennas.

According to an aspect of the invention, the objects are achieved with an antenna assembly for wireless communication systems, comprising an antenna part and an antenna signal processing part together forming an integrated antenna assembly;

- said antenna part comprising at least one antenna element adapted for receiving/transmitting wireless communication signals, and

- said antenna signal processing part comprising at least one processing unit adapted for signal processing communication signals to and/or from said at least one antenna element; wherein

- said antenna part and said antenna signal processing part being attached to each other and separated from each other by means of an intermediate cover (C) located between said antenna part and said antenna signal processing part; and

- said antenna assembly further comprises a first gasket (Gl) and a second gasket (G2) for sealing said antenna assembly,

- said first gasket (Gl) being arranged to act in a first direction (Dl) on said intermediate cover (C), and

- said second gasket (G2) being arranged to act in a second direction (D2) on said intermediate cover (C), said second direction (D2) being substantially opposite to said first direction (Dl). Different embodiments of the antenna assembly are disclosed in the appended dependent claims. The present invention provides a water tight seal which protects the internal electronics built into integrated antennas from being damaged by moisture or dust ingress into the antenna unit. The seal provides protection against moisture and dust ingress to sensitive electronics and allows for an embodiment with a heat sink to aid with the cooling of the aforementioned electronics.

Furthermore, the use of gasket seals according to the invention allows for maintenance operations to be performed by being easier to separate the parts of the antenna for repair, upgrade and for recycling when the antenna reaches the end of its useable life. Further applications and advantageous of the invention will be apparent from the following detailed description.

Brief Description of the Drawings

The appended drawings are intended to clarify and explain different embodiments of the present invention in which:

Figure 1 schematically shows a traditional antenna system with a passive antenna unit connected to RRU;

Figure 2 schematically shows a first embodiment of an antenna assembly according to the present invention;

- Figure 3 schematically shows a part of a second embodiment of an antenna assembly according to the invention; and

Figure 4 schematically shows an antenna assembly viewed from above.

Detailed Description of the Invention

As aforementioned, with the introduction of active antennas in wireless communication systems there is a need for proper environmental protection of such antennas. Therefore, the present invention relates to an integrated antenna assembly comprising a passive antenna part and an active antenna signal processing part. The former comprising at least one antenna element (but often an array of antenna elements for antenna beam control in cellular communication systems) for receiving/transmitting wireless communication signals, and the latter comprising one or more signal processing units or any other active component for processing wireless communication signals. The two parts are in communication with each other by means of one or more communication interfaces, such as communication cables. It should be understood that a processing unit in this disclosure should have a wide interpretation and may incorporate such as Digital Signal Processor (DSP), power amplifier, AD or DA converters, etc.

The antenna part and the antenna signal processing part are attached to each other by means of an intermediate cover C located between the two parts, which also separates mentioned two parts. It should be noted that the intermediate cover C may comprises suitable connection means/interfaces for transmission of signals between the antenna elements and the signal processing unit in the two different parts.

Moreover, the antenna assembly further comprises a first gasket Gl and a second gasket G2 for sealing the antenna assembly against water and dust. The first gasket Gl is arranged to act in a first direction Dl on the intermediate cover C, and the second gasket G2 is arranged to act in a second direction D2 on the intermediate cover C, wherein the second direction D2 is substantially opposite to the first direction Dl .

Figure 2 schematically shows an embodiment of an antenna assembly according to the invention. The integrated antenna assembly in figure 2 is shown in cross section. The upper part is the antenna signal processing part and the lower part is the antenna part. As shown in the figure an intermediate cover C is located between the upper and lower parts. The mentioned three parts may be attached to each other by means of suitable fastening means, such as bolts, screws, rivets or adhesives. The main radiation direction of the antenna is also illustrated in figure 2.

So as to seal the integrated antenna assembly, a first Gl and a second G2 gasket are provided in a first Grl and a second Gr2 groove, respectively. The first gasket Gl acts on the intermediate cover C in a first direction Dl, while the second gasket G2 acts on the intermediate cover C in a second direction D2 opposite to the first direction Dl. In this case on the opposite sides of the elongated flat intermediate cover C according to an embodiment. Thereby, a water tight and dust free seal is provided as the force acting on the intermediate cover C from the first gasket Gl is balanced by the force acting on the intermediate cover C from the second gasket G2 which results in a tight fit. This is especially the case when the intermediate cover C is made of a material, such as sheet metal of aluminium that may deflect when a force acts on it.

The gaskets Gl, G2 are made of a compressible material, such as silicon rubber or any other suitable material with the compression and sealing properties. It should further be noted that the first Grl and second Gr2 grooves in which the gaskets Gl, G2 run extend along the circumference of respective parts so as to achieve extra good sealing.

Hence, the invention allows an antenna to be integrated with a radio processing unit (such as a RRU) and at the same time providing a water and dust proof seal which complies with the environmental protection standard qualification required for this type of antennas. Figure 3 schematically shows a cross section of a part of another embodiment of an antenna assembly according to the invention. It has been mentioned that with the integration of active circuits in an antenna assembly, proper cooling is need. An effective and reasonable priced solution is the use of heat sinks HS made of aluminum. The drawback is however that these heat sinks HS have to be of considerable size if the cooling should be effective. With the size there is a risk that gaps appear between the heat sink HS and the other part of the antenna assembly which destroys the sealing.

The embodiment in figure 3 comprises a heat sink HS (of which only a part is shown) made of aluminum having one or more cooling flanges (not shown). The heat sink HS also functions as a cover for the antenna signal processing part in this embodiment. The antenna assembly in figure 3 further comprises a (plastic) radome R protecting the antenna part. In this preferred embodiment, the first groove Grl is located in the heat sink HS, while the second groove Gr2 is located in the radome R. Further, the first groove Grl extends on the inside of the fastening means (in this case screws) while the second groove Gr2 extends along the outside of said fastening means. That is, the two grooves Grl, Gr2 extend on different sides of the fastening means, and this particular embodiment has proven to have very good sealing properties. Figure 4 illustrates the antenna assembly from above. The dotted lines illustrate the first Grl and second Gr2 grooves, respectively, and it is noted that the two grooves Grl, Gr2 extend on two different distances dl, d2 in relation to the edge of the antenna assembly.

The antenna assembly is preferably used as base station antenna in cellular wireless communication systems and therefore adapted for radio frequencies in such systems. Examples of such systems are: GSM, UMTS, LTE, and LTE -Advanced. However, the present invention is not limited to the embodiments described above, but also relates to and incorporates all embodiments within the scope of the appended independent claim.

Another aspect of the use of heat sinks in antennas is its weight. It is well known that it is preferable if the antenna assembly has a low weight as possible. The inventors have realized that the surface area that the heat sinks cover may be less then the surface area of the intermediate cover C so as to reduce weight. The cooling of the active components may still be achieved. A drawback with this solution is the asymmetry introduce by the different surface areas which complicates the sealing of such antennas further. The present invention has proved in tests that it is possible to provide a satisfactory seal and reduce the number of fasteners using the sealing arrangement described in the application which also means that time and cost can be reduced when producing antenna assemblies according to the invention. However, the benefits of using opposing forces according to the invention decrease the smaller the heat sink and the greater the offset between the two gaskets Gl, G2.

Claims

1. Antenna assembly for wireless communication systems, comprising an antenna part and an antenna signal processing part together forming an integrated antenna assembly; - said antenna part comprising at least one antenna element adapted for receiving/transmitting wireless communication signals, and

- said antenna signal processing part comprising at least one processing unit adapted for signal processing communication signals to and/or from said at least one antenna element; characterised in that

- said second gasket (G2) being arranged to act in a second direction (D2) on said intermediate cover (C), said second direction (D2) being substantially opposite to said first direction (Dl).

2. Antenna assembly according to claim 1, wherein

- said first (Gl) and second (G2) gaskets run in a first groove (Grl) and in a second groove (Gr2), respectively,

- said first groove (Grl) being located on said antenna signal processing part and said second groove (Gr2) being located on said antenna part.

3. Antenna assembly according to claim 2, wherein said antenna signal processing part further comprises at least one heat sink (HS), and said first groove (Grl) is at least partly located in said heat sink (HS).

4. Antenna assembly according to claim 3, wherein said heat sink (HS) also function as a cover for said antenna signal processing part.

5. Antenna assembly according to claim 3, wherein said heat sink (HS) has one or more cooling flanges and/or is made of metal, such as aluminium.

6. Antenna assembly according to claim 2, wherein said antenna part further comprises a radome (R) covering said antenna part, and said second groove (Gr2) is at least partly located in said radome (R).

7. Antenna assembly according to claim 2, wherein

- said first groove (Grl) extends along the circumference of said antenna signal processing part, and/or

- said second groove (Gr2) extends along the circumference of said antenna part.

8. Antenna assembly according to claim 1, wherein said first (Gl) and second (G2) gaskets are made of a compressible material, such as silicon rubber.

9. Antenna assembly according to claim 1, wherein said intermediate cover (C) is made of sheet metal.

10. Antenna assembly according to claim 1, wherein said antenna part, said antenna signal processing part and said intermediate cover (C) are attached to each other by means of one or more fastening means, such as screws, bolts, rivets and adhesives.

11. Antenna assembly according to claim 1 , wherein

- said first gasket (Gl) acts on a first side of said intermediate cover (C), and

- said second gasket (G2) acts on a second side of said intermediate cover (C), said first and second sides being opposite sides of said intermediate cover (C).

12. Antenna assembly according to claim 1, wherein said first direction (Dl) is in the main radiation direction of said antenna assembly.

13. Antenna assembly according to claim 1, wherein said antenna processing part covers a surface area less than the surface area of the intermediate cover (C).

14. Antenna assembly according to claim 1, wherein said antenna assembly is adapted for cellular wireless communication systems, such as GSM, UMTS, LTE and LTE advanced.

15. Antenna assembly according to claim 1, wherein said antenna assembly is a base station antenna.