|Número de publicación||WO2002031919 A1|
|Tipo de publicación||Solicitud|
|Número de solicitud||PCT/FI2001/000874|
|Fecha de publicación||18 Abr 2002|
|Fecha de presentación||9 Oct 2001|
|Fecha de prioridad||13 Oct 2000|
|Número de publicación||PCT/2001/874, PCT/FI/1/000874, PCT/FI/1/00874, PCT/FI/2001/000874, PCT/FI/2001/00874, PCT/FI1/000874, PCT/FI1/00874, PCT/FI1000874, PCT/FI100874, PCT/FI2001/000874, PCT/FI2001/00874, PCT/FI2001000874, PCT/FI200100874, WO 0231919 A1, WO 0231919A1, WO 2002/031919 A1, WO 2002031919 A1, WO 2002031919A1, WO-A1-0231919, WO-A1-2002031919, WO0231919 A1, WO0231919A1, WO2002/031919A1, WO2002031919 A1, WO2002031919A1|
|Inventores||Jaakko Talvitie, Pekka Jakkula, Ari Hulkkonen, Pekka Moilanen|
|Solicitante||Pj Microwave Oy|
|Exportar cita||BiBTeX, EndNote, RefMan|
|Citas de patentes (4), Citada por (2), Clasificaciones (9), Eventos legales (6)|
|Enlaces externos: Patentscope, Espacenet|
FIELD OF THE INVENTION
 The invention relates to a phased antenna array by means of which the transmitting and/or receiving direction can be changed.
BACKGROUND OF THE INVENTION
 Directional antennas are used in wireless radio systems so as to direct the antenna towards the transmitter (or receiver) and thus increase the power of the received (or transmitted) signal and decrease interference. In fixed-beam antennas the antenna must be physically directed towards the transmitter (or receiver) or the best receiving direction (or transmitting direction). In order to avoid physical directioning, the prior art utilizes a phased antenna array. The antenna array is planar and comprises a number of antenna elements. Such an antenna array is frequently attached to the outer wall of a building. Particularly in city areas, the antenna beam must be effectively directed both in horizontal and vertical direction when high buildings prevent direct visual connection. In vertical direction there is also need for effective directioning in a case where the antenna array is on top of a skyscraper, and the transmitter or the receiver in data transmission connection with an antenna array is on the street level next to the building. With an ordinary antenna array solution the directioning can only take place at a narrow sector not exceeding the normal of the planar antenna surface by ± 45°. This deteriorates the quality of the connection and the functionality of the system.
 In WLAN networks used indoors, in turn, a wide-beam antenna positioned on the wall or in the corner, is usually used, which antenna can be planar or omnidirectional and cover the whole room. This causes a plurality of problems. Too wide a beam gathers not only the desired signal but all reflections and interferences from the room, which results in a decrease in the transmission capacity. A planar antenna positioned in the corner is also a poor solution from a visual point of view.
BRIEF DESCRIPTION OF THE INVENTION
 An object of the invention is thus to implement an improved antenna array by means of which both good directioning and coverage can be achieved. This is achieved with an antenna array comprising antenna elements and a support structure to which the antenna elements are attached. Further, the antenna array compπses at least two antenna element groups, both with at least one antenna element, the antenna element groups being directed physically in different directions.
 Preferred embodiments of the invention are disclosed in the dependent claims.
 The invention is based on the idea that antenna element groups directed in different directions allow a considerable increase in the directional sector of the antenna.
 A plurality of advantages is achieved with a method and system according to the invention. Since the antenna arrays are in different directions relative to each other, the transmission and/or reception can take place even in a sector of 180° (or greater). Large coverage is also possible. In this way, a good connection can be formed and the functionality of the system can be improved also in difficult conditions, for instance in city or indoors conditions.
BRIEF DESCRIPTION OF THE DRAWINGS
 The invention will now be described in more detail in connection with preferred embodiments, with reference to the attached drawings, in which  Figure 1 shows a planar antenna array;
 Figure 2A shows an antenna array comprising two antenna element arrays directed in different directions;
 Figure 2B shows an antenna array comprising two antenna element arrays directed in different directions;  Figure 3 shows a block diagram of an antenna array;
 Figure 4 shows vertical directioning of an antenna array;
 Figure 5 shows horizontal directioning of an antenna array;
 Figure 6A shows an antenna array used indoors;
 Figure 6B shows an antenna array used indoors, having narrow antenna beams;
 Figure 7A shows an antenna array positioned in the corner of an apparatus;
 Figure 7B shows a slot antenna array;
 Figure 7C shows a slot antenna in the corner of an apparatus housing;  Figure 8A shows a top view of a slot antenna; and  Figure 8B shows a side view of a slot antenna.
DETAILED DESCRIPTION OF THE INVENTION
 A solution according to the invention can be used particularly in the creation of point-to-point connections in the microwave area without, however, confining the invention thereto.
 In the microwave area, in particular, a typical phased antenna array is planar, such as shown in Figure 1. The antenna array comprises antenna elements 100 and a support structure 102 of the antenna elements. The antenna elements can be made of a printed board by etching. The antenna array is directed by changing the phasing of each antenna element in a known manner by means of phase shifters and control logic. This aspect is explained in more detail in Antenna Engineering Handbook by Johnson, R., C, pp. 20-1 ... 20-67, McGraw Hill Inc., 1993, which is incorporated as reference herein. The printed board of which the antenna elements 100 are made are attached to a support structure, which is an aluminium sheet, for example.
 Let us now consider a solution according to the invention by means of Figures 2A and 2B, in which the antenna array comprises two antenna element groups 200 and 202, both comprising at least one antenna element 203. There is an angle between the antenna element groups, whereby the antenna element groups are directed physically in different directions. There may be more than two antenna element groups. In Figure 2A, angle α, which is measured from the backside of the antenna element arrays 200 and 202 (the front side of the antenna arrays 200 and 202 is the side at which the antenna beam or antenna beams are directed), is smaller than 180°. When two planar antenna element arrays are used, the angle is preferably 90°. The angle α between the antenna arrays enables the transmission and/or reception over a large sector of even 180°. The antenna elements of the antenna element groups 200 and 202 are preferably etched on a printed board, and the phase shifters and the control logic control the direction of the beam. The printed boards of which the antenna element groups 200 and 202 are made are preferably attached at a desired angle to the surface of a bent planar aluminium sheet 204. Thus, the directions of the surface normals of the aluminium sheets and antenna element groups 200 and 202 differ from each other by the angle . The aluminium sheet preferably comprises protrusions 205 by which the antenna module can be attached to a holder 206 comprising an RF block, for example. The holder 206 can, in turn, be attached to the wall of a building, for instance.  A beam from the antenna array can be directed over a large sector in the following way. If nothing is sent with the antenna element group 202 and if the beam is directed with an antenna element group 200 as much to the left as possible, the beam is directed in the direction of arrow 208, i.e. for example 45° in the direction of the arrow 208 to the left from the normal N of the antenna element group. If, in turn, nothing is sent with the antenna element group 200 and if the beam is directed with the antenna element group 202 as much to the right as possible, the beam is directed in the direction of arrow
210, i.e. 45° to the right from the normal N2 of the antenna element group. In this way, the sector of total directivity ω is ω = 45° + 45° + α. If α is α = 90°, the total directivity of the sector ω becomes ω = 180°. When both antenna element groups are used, the antenna beam can be directed by phasing antenna elements in a desired direction in said sector of 180°. Further, the antenna beam can be directed towards a large sector in vertical direction. For example, in vertical and horizontal direction, a conventional narrow-sector directioning can be carried out.
 Figure 2B shows an antenna array where the angle between the antenna element arrays 200 and 202, which is measured from the backside of the antenna element arrays 200 and 202, is over 180°. Thus, the antenna arrays 200 and 202 are slightly pointed at each other. Such an antenna array can be applied to a case shown by Figures 6A and 6B.
 Figure 3 shows a block diagram of an antenna array. The antenna array module comprises at least two independent antenna arrays 200 and 202. Both antenna arrays comprise antenna elements, phase shifters and control logic (not shown in Figure 3). The antenna array is connected to an RF block 304, from which a signal of RF frequency is supplied to the antennas during the transmission and which, during the reception, converts the received RF frequency signal into a baseband signal. The antenna module is controlled by a baseband block 306 to which the received signals arrive and from which the signals to be transmitted are fed to the RF block 304. The antenna arrays 200 and 202 are preferably planar, their surface normals being not, however, parallel but there being an angle α between the antenna arrays.
 Figure 4 shows an exemplary case where the vertical directioning of the antenna is needed. The antenna array 400 is mounted on a low building, the antenna array 402 being mounted on a high building. The antenna arrays are mounted on buildings in such a way that the angle between the antenna element arrays opens in vertical direction, such as shown in Figure 4. This allows effective directioning of the antenna in vertical direction. Horizontal directioning can also be carried out.
 Figure 5 shows a case where horizontal directioning of the antenna is needed. The antenna arrays are attached to the buildings in such a way that the angle between the antenna element arrays opens in horizontal direction. Electromagnetic radiation from the transmitting antenna array 500 proceeds through several reflections via two paths to the receiving antenna array 502. The radiation can proceed via more than two paths as well, but Figure 5 shows, for the sake of clarity, only two paths. Since the radiation arrives in the receiving antenna array 502 in the direction of the walls of buildings, the wide-angle reception according to the present solution enables both reception directions to be utilized effectively.
 Figure 6A shows use of antenna arrays particularly indoors. An antenna array according to the present solution can be applied to a base station in a wireless LAN network (Wireless Local Area Network, WLAN). An antenna element array 600 carries out reception and sending in the direction of a beam 604, and an antenna element array 602, in turn, carries out reception and sending in the direction of a beam 606. In this way, two beams in one antenna array can be used to cover the whole room, thus also decreasing interference. Also, the antenna array can well be placed in the corner and is visually suitable.
 Figure 6B shows a situation corresponding to that in Figure 6A, with the difference that the antenna beams 610 to 612 of different antenna element arrays 600 to 602 can be directed narrow towards desired apparatus 614 to 616. Hereby, the interference of the received signal is at the minimum, which enables an increase in transmission capacity. In the case of both Figure 6A and Figure 6B diversity can be utilized.
 Figure 7A shows a solution in which an antenna array 700 is positioned in at least one corner of the apparatus 702. In this way, the apparatus can communicate at the angle of 360° with a narrow or wide beam. In the prior art, the antenna of the apparatus casing is generally a monopole antenna upon the apparatus, prone to breaking or bending. A slot antenna according to the disclosed solution utilizes the apparatus housing, so that there are no protrusive parts. In addition to the practicability, the visual appearance is also good.
 Figure 7B shows a slot antenna array comprising at least two slot antenna elements. Let us first consider a slot antenna array comprising slot antenna elements 710 and 712. The slot antenna elements 710 and 712 are physical slots that are made in an electricity-conducting housing 720 of some electrical device. The material of the housing 720 can be metal, for instance. The slot antenna elements 710 and 712 are separated from each other by a material forming the angle of the housing 720. Since the housing 720 forms a three-dimensional item and the adjacent sides of the housing are at an angle of 90° relative to each other, the beams of the slot antenna elements 710 and 712 point in different directions by 90°. In addition to two slot antenna elements 710 and 712, there may be a third slot antenna element 714 in the housing 720. In this way, the apparatus can receive and/or send through its housing 720 in all of the three different dimensions.
 Figure 7C shows a slot antenna, the slot antenna elements 730 and 732 of which are not separated from each other with material at the angle of the housing, but one physical slot continues from the side of the first wall over to the second wall. Still, the slot antenna elements 730 and 732 on different walls function independently. In such a case, the width of the slot is preferably one wavelength instead of half a wavelength.  Figures 8A and 8B show the relevant parts as regards the operation of the slot antenna element. Figure 8A shows a top view of a slot antenna element. The slot antenna element comprises a slot 800 in an electricity-conducting material 802 and a strip line 804 isolated from the electricity-conducting material 802, connected to the transmitter of receiver via a connector 806. The slot antenna element radiates to the surroundings the electromagnetic radiation fed via the strip line 804 and arranged in the slot 800 and receives via the slot 800 electromagnetic radiation to the strip line 804 in a manner known as such.
 Figure 8B shows a side view of a slot antenna element. The strip line 804 can be made on a printed board, to which the connector 806 is attached. The printed board material 808 isolates the strip line 804 from the electricity-conducting material 802, where the slot 800 is located. In order to prevent the antenna from radiating to the inside of the apparatus, the slot antenna element can be covered with an electricity-conducting material 810, which can be a solid and continuous material layer or a net closer meshed than the operating wavelength of the antenna element.
 In the disclosed solution, the main frequency range of the electromagnetic radiation transmitted or received by the antenna array is measured in GHz, for instance 2.4 to 2.5 GHz or 5 to 6 GHz.
 Although the invention has been described above with reference to the example of the attached drawings, it is obvious that the invention is not confined thereto but can be modified in a plurality of ways within the scope of the inventive idea disclosed in the attached claims.
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|Clasificación internacional||H01Q3/26, H01Q25/00, H01Q21/06|
|Clasificación cooperativa||H01Q21/061, H01Q3/26, H01Q25/00|
|Clasificación europea||H01Q25/00, H01Q3/26, H01Q21/06B|
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