According to a second aspect, the present invention relates to an antenna element manufactured according to said method.

Background of the Invention The document US-A1-2001/0028325 discloses a plane antenna compris- ing a conducting layer of foil that forms a ground plane, a conducting foil element placed at a distance from the ground plane, and a dielectric substrate that sepa- rates the foil element from the ground plane. The dielectric substrate is manufac- tured from an extruded plastic material having a cellular configuration in cross- section. The corrugated plastic has a plurality of properties making it extraordinar- ily suitable for use in a plane antenna. The structure of the material provides a plane surface, which is particularly suitable for application of adhesive or other lamination substances or material.

The document WO-A1-00/76024 shows an antenna module for mobile telephony. The antenna module comprises an extruded section, which may be manufactured from aluminium. The extruded section comprises a tubular basic body. Furthermore, the antenna module comprises a number of antenna units. In figure 3 in this document, a cross-section of an antenna unit is shown. The antenna units are mounted on an outer side of the extruded section.

The document WO-98/27614 discloses an antenna system configured for various functions at a first and a second polarisation and comprises a transforma- tion to third and fourth polarisations. The antenna system comprises, among other things, an extruded part that constitutes the rear plane of the system and a support structure for holding the printed board assembly in place.

Document WO-99/19937 shows an antenna system consisting of vertically piled dipoles, which are fed in parallel. The antenna system comprises a mast manufactured from, for instance, extruded aluminium. The dipole antenna consists of a pair of coaxial cylinders, coaxially mounted on a conducting antenna mast.

The document US-6 133 877 discloses in particular micro-strip antennas for suppression of undesired modes. The document also discloses group antennas having improved characteristics, in particular regarding avoiding coupling between different antenna elements. A waveguide structure of extruded aluminium is installed on the back side of the antenna along two connection lines.

The document US-5 940 044 shows an antenna system comprising four dipole elements that preferably are placed in a diamond shape on a rear plate of the antenna system. The rear plate may, for instance, be manufactured from extruded aluminium.

The document WO-00/28620 discloses different methods for manufactur- ing an array antenna, by manufacturing a plurality of extruded (of metal or plastic) sections forming a waveguide structure of an array antenna when they have been mounted; arranging said plurality of extruded sections for forming the waveguide structure; and joining said plurality of extruded sections at the respective ends thereof in order to form the array antenna.

The document WO-99/27607 shows a frame and antenna structure for a mobile telephone or another device that utilizes high-frequency radio communica- tion. The frame structure and radiator constitute an integral component and may, for instance, be manufactured from extruded aluminium.

The above shown documents explain that parts of a plurality of different antennas may be manufactured from extruded material. However, the extrusion technique is not utilized completely with the feasible potential thereof, in particular not as regards antenna systems for, for instance, base station masts.

Summary of the Invention It is an object of the present invention to solve the above-mentioned prob- lems.

According to the present invention, according to a first aspect, a method is provided for manufacturing antenna elements intended to be used in an antenna system for transmitting and receiving electromagnetic signals. The method com- prises the steps of: - extruding an antenna element profile; and - by means of machining member machining the antenna element profile in order to obtain a plurality of antenna elements.

An advantage of this method is that it has few processing steps and expensive stages, as bending, welding, soldering etc are avoided. Furthermore, with this method, a very stable antenna element that keeps the shape thereof is obtained.

In this connection, an additional advantage is obtained if the method fur- thermore comprises the steps of: - cutting the antenna element profile into pieces; and - applying the pieces in a machining member.

An additional advantage is obtained in this connection if the machining member consists of milling member, laser member, water-cutting member or punching member.

In this connection, an additional advantage is obtained if the antenna ele- ment profile is manufactured from aluminium.

An additional advantage is obtained in this connection if each antenna element comprises a pair of cross-polarized dipoles having a first dipole having two hollow double-walled arms and a second dipole having two hollow double- walled arms.

In this connection, an additional advantage is obtained if each antenna element comprises a vertically polarized dipole having two hollow double-walled arms.

An additional advantage is obtained in this connection if each antenna element consists of two mirror-inverted halves.

In this connection, an additional advantage is obtained if each antenna element comprises a horizontally polarized dipole having two hollow double-walled arms.

An additional advantage is obtained in this connection if each antenna element comprises cold pressing members for joining with, for instance, a reflector element included in the antenna system.

In this connection, an additional advantage is obtained if the cold pressing members consist of score-provided projections for joining with elongated grooves on, for instance, a reflector element.

An additional advantage is obtained in this connection if the score-pro- vided projections have a maximum width that is greater than the width of the grooves.

In this connection, an additional advantage is obtained if the cold pressing members consist of grooves for joining with score-provided projections on, for instance, a reflector element.

According to a second aspect of the present invention, an antenna ele- ment is provided manufactured according to the above-mentioned method. An advantage of said antenna element is that it becomes very stable and keeps the shape thereof. Another advantage is that the antenna element entirely lacks poorly conducting welds, solders and blind riveting joints.

It should be pointed out that the term"comprises/comprising"when it is used in this application should be regarded as defining the presence of defined properties, steps or components, but does not exclude the presence of one or more other properties, parts, step, components or groups thereof.

Embodiments of the invention will now be described with reference to the accompanying drawings, where: Brief Description of the Drawings Figure 1 shows a flow chart of a first embodiment of a method for manu- facturing antenna elements according to the present invention; Figure 2 shows a flow chart of a second embodiment of a method for manufacturing antenna elements according to the present invention; Figure 3 shows a side view of a first embodiment of an antenna element 20 manufactured according to any one of the methods shown in figure 1 and figure 2; Figure 4 shows a view from above of the antenna element 20 shown in figure 3; Figure 5 shows a cross-section view of the profile that is used for manu- facturing the antenna element 20 shown in figure 3 and figure 4; Figure 6 shows a side view of a second embodiment of an antenna ele- ment 20'manufactured according to any one of the methods shown in figure 1 and figure 2; Figure 7 shows a view from above of the antenna element 20'shown in figure 6; Figure 8 shows a cross-section view of the profile that is used for manu- facturing the antenna element 20'shown in figure 6 and figure 7;

Figure 9 shows a perspective view of a vertically polarized dipole 50 manufactured according to any one of the methods shown in figure 1 and figure 2; Figure 10 shows a side view of the dipole 50 shown in figure 9; Figure 11 shows a perspective view of a horizontally polarized dipole 60 manufactured according to any one of the methods shown in figure 1 and figure 2; and Figure 12 shows a side view of the dipole 60 shown in figure 11.

Detailed Description of Embodiments In figure 1, a flow chart is shown of a first embodiment of a method for manufacturing antenna elements intended to be used in an antenna system for transmitting and receiving electromagnetic signals. The method begins at the block 10. The method then continues, at the block 12, with the step of: extruding an antenna element profile. Then the method continues, at the block 14, with the step of: by means of machining member machining the antenna element profile in order to obtain a plurality of antenna elements. Then the method is terminated at the block 16.

In figure 2, a flow chart is shown of a second embodiment of a method for manufacturing antenna elements intended to be used in an antenna system for transmitting and receiving electromagnetic signals. The method begins at the block 100. Then the method continues, at the block 102, with the step of: extruding an antenna element profile. Next, the method continues, at the block 104, with the step of: cutting the antenna element profile into pieces. Then the method contin- ues, at the block 106, with the step of: applying the pieces in a machining member.

Next, the method continues, at the block 108, with the step of: by means of the machining member machining the pieces in order to obtain a plurality of antenna elements. Then the method is terminated at the block 110.

According to a preferred embodiment of the method, the machining mem- ber consists of milling member, laser member, water-cutting member or punching member.

According to a preferred embodiment of the method, the antenna element profile is manufactured from aluminium.

According to a preferred embodiment of the method, each antenna ele- ment comprises a pair of cross-polarized dipoles having a first dipole having two

hollow double-walled arms and a second dipole having two hollow double-walled arms. Compare figure 3-figure 5.

According to an embodiment of the method, each antenna element con- sists of two mirror-inverted halves. Compare figure 6-figure 8.

According to another embodiment of the method, each antenna element comprises a vertically polarized dipole having two hollow double-walled arms.

Compare figure 9-figure 10.

According to additionally another embodiment of the method, each antenna element comprises a horizontally polarized dipole having two hollow dou- ble-walled arms. Compare figure 11-figure 12.

According to a preferred embodiment of the method, each antenna ele- ment comprises cold pressing members for joining with, for instance, a reflector element included in the antenna system.

According to a preferred embodiment of the method, the cold pressing members consist of score-provided projections for joining with elongated grooves on, for instance, a reflector element.

According to a preferred embodiment of the method, the score-provided projections have a maximum width that is greater than the width of the grooves.

According to a preferred embodiment of the method, the cold pressing members consist of grooves for joining with score-provided projections on, for instance, a reflector element.

In figure 3, a side view is shown of a first embodiment of a dipole element 20 manufactured according to any one of the methods shown in figure 1 and figure 2. In figure 4, a view from above is shown of the dipole element 20 shown in figure 3. In figure 5, a cross-section view is shown of the profile that is used for manu- facturing the dipole element 20 shown in figure 3 and figure 4. As is most clearly seen in figure 4, each dipole element 20 comprises a first dipole 201 having two hollow, double-walled, downwardly bent arms (compare figure 3 and figure 5).

Each dipole element 20 furthermore comprises a second dipole 202 having two hollow, double-walled, downwardly bent arms (compare figure 3 and figure 5).

Each dipole element 20 furthermore comprises two parallel, elongated fastening members 40 in the form of score-provided projections 40 (compare figure 5) for cold pressing in the grooves of the reflector element. Furthermore, each dipole element 20 comprises four hollow, double-walled legs 421, 422 wherein the feed

network partly may be arranged. The profile shown in figure 5 is manufactured from extruded aluminium. The shown dipole element 20 is milled out from the pro- file shown in figure 5.

In figure 6, a side view is shown of a second embodiment of a dipole element 20'manufactured according to any one of the methods shown in figure 1 and figure 2. In figure 7, a view from above is shown of the dipole element 20' shown in figure 6. As is seen in figure 6 and figure 7, each dipole element 20' comprises two mirror-inverted halves, each having two hollow, double-walled, downwardly bent arms. Furthermore, each half comprises two parallel, elongated fastening members 40'in the form of score-provided projections 40'for cold pressing in the grooves of the reflector element. Each half comprises, furthermore, two hollow, double-walled legs 421', 422'wherein the feed network partly may be arranged. The two halves constitute two cross-polarized dipoles 201', 202'where each half contributes to the two dipoles 201', 202'.

In figure 8, a cross-section view is shown of the profile that is used for manufacturing the dipole element 20'shown in figure 6 and figure 7. Said profile is only"half'in relation to the profile shown in figure 5. This means that a complete dipole element 20'consists of two mirror-inverted halves, placed with the legs fac- ing each other. Furthermore, each half of the dipole element 20'comprises two parallel, elongated fastening members 40'in the form of score-provided projec- tions 40'for cold pressing in the grooves of the reflector element.

In figure 9, a perspective view is shown of a vertically polarized dipole 50 manufactured according to any one of the methods shown in figure 1 and figure 2.

The dipole 50 comprises two arms 52 as well as two hollow, double-walled legs 54. As is seen, the legs 54 and the arms 52 are arranged in the same plane. The dipole 50 comprises furthermore two score-provided projections 56.

In figure 10, a side view is shown of the dipole 50 shown in figure 9. As is seen in this figure, the arms 52 have a circular cross-section.

In figure 11, a perspective view is shown of a horizontally polarized dipole 60. The dipole 60 comprises two arms 62 as well as two hollow, double-walled legs 64. Furthermore, the dipole 60 comprises two score-provided projections 66.

In figure 12, a side view is shown of the dipole 60 shown in figure 11.

The invention is not limited to the above-described embodiments. It is evi- dent that many feasible modifications are feasible within the scope of the following claims.