Patent Application
20100182213
The invention relates to an antenna arrangement, in particular for a mobile radio base station, as claimed in the preamble of claim 1.
An antenna arrangement of this kind is known from EP 1 588 454 B1. According to this anticipatory document the use of, for example, an antenna arrangement, which can be vertically oriented, having a reflector is described, on the vertical lateral limiting lines of which two lateral webs are formed transversely, and in particular perpendicularly, to the reflector plane so as to protrude in the direction of radiation. The dual-polarized radiators arranged one above the other in the vertical direction sit between these lateral webs. According to this anticipatory document also, the base of the supporting mechanism and/or balancing means of the associated radiator assembly is capacitively connected (i.e. without electrical-galvanic contact) to the reflector or coupled thereto by connecting a cap in series, for which purpose the reflector has a recess in which the non-conductive cap engages and is secured and in turn holds the supporting mechanism and/or balancing means or the base of the supporting mechanism and/or balancing means of the dual-polarized radiator. The internal conductor can be installed as is described in the above-mentioned prior art in this case.
A flat antenna can also be gathered as known from DE 697 25 874 T2 and comprises a ground plane layer that is capacitively coupled to a base unit. A dielectric layer is provided between these two layers.
Antenna arrangements, in particular for a mobile radio base station, are also known for example from WO 00/039894 A1. This anticipatory document describes a reflector that can be vertical oriented and on the two vertical and mutually parallel outer, laterally located limits of which a lateral web is formed that protrudes in the direction of radiation and therefore transversely to the reflector plane. A plurality of dipolar arrangements consisting of what are known as vector dipoles and radiating in two mutually perpendicularly oriented polarization planes is provided one above the other in the vertical direction. In terms of construction these vector dipoles are similar to dipole squares. Nevertheless feeding takes place in such a way that despite the horizontally or vertically oriented dipoles, overall the dipole arrangement acts as an X-polarized antenna in which the two polarization planes that are perpendicular to each other are oriented at an angle of +45° or −45° with respect to the vertical or horizontal.
It can be gathered from WO 2005/060049 A1 that the dual-polarized radiators, which sit upstream of a reflector, may be provided with a capacitive outer conductor coupling. Axial holes that run perpendicular to the reflector plane are therefore introduced in each half of the two supporting mechanisms and/or balancing means that are rotated by 90° with respect to each other. Rod-shaped coupling elements 21 that are galvanically connected to the reflector project into these holes and are surrounded by cylindrical insulators onto which the pairs of supporting halves of the dual-polarized radiator assembly that are arranged rotated by 90° with respect to each other can be placed with the total of four axial holes. An internal conductor for feeding the two mutually perpendicular polarizations of the radiator assembly can be laid inside two rod-shaped coupling elements from the back of the reflector in each case.
Finally, antenna arrangements with reflectors are known on the longitudinal lateral regions of which, i.e. on the longitudinal or vertical lateral surfaces of which, longitudinal webs that protrude forwards from the reflector plane are provided, as may be gathered for example from the anticipatory documents WO 99/62138 A1, U.S. Pat. No. 5,710,569 A or EP 0 916 169 B1.
An alternative embodiment according to this anticipatory document discloses that instead of an electrically conductive reflector, conventionally in the form of a metal sheet, a printed circuit board may also be used on which the reflector is constructed. In this case the electrically conductive ground plane is preferably omitted on one side of the printed circuit board or the cap is also provided with insulation in this region.
By contrast, the object of the present invention is to create an improved antenna arrangement which includes beam shaping possibilities and still has a simple construction.
According to the invention the object is achieved in accordance with the features disclosed in claim 1. Advantageous developments of the invention are disclosed in the subclaims.
The invention creates an improved antenna arrangement that can be easily and highly accurately produced with exactly predetermined radiation properties while avoiding potential sources of disruption such as undesirable intermodulations.
It has previously been conventional in the prior art to usually use reflectors made from a metal sheet, the radiator modules being constructed on the reflectors. The longitudinal lateral limits in the form of longitudinal webs and which protrude transversely to the reflector plane can be constructed at a suitable location as a result of the radiators arranged between the lateral external limit of the reflector plane and the, as a rule, centrally arranged radiators. These longitudinal webs could be adjusted for example between a perpendicular orientation with respect to the reflector plane through to an angular orientation in such a way that desired beam shaping was possible.
If, by contrast, one wanted to use reflectors in the form of printed circuit boards (what are referred to as PCBs) which were provided on one side with an electrically conductive ground plane, then this required the webs needed for beam shaping to be connected to the ground plane of the printed circuit board by means of screw connections or soldered joints in order to achieve a definite galvanic connection here. In addition to being laborious this assembly work caused ever potential intermodulation sources or disruption.
By contrast it is now proposed, starting from a printed circuit board which is preferably provided on its radiator side with an electrically conductive ground plane and a insulating layer located above it, to place a reflector frame thereon which is provided with a coupling surface parallel to the ground plane of the printed circuit board, the desired longitudinal and/or transverse webs that are required for diagram shaping in turn being constructed on this coupling surface. In other words, according to the invention a capacitive reflector frame coupling is proposed that allows the longitudinal and/or transverse webs required for diagram shaping to be capacitively coupled to a ground plane sitting on a printed circuit board.
In a preferred embodiment the reflector frame provided according to the invention can be made from an electrically conductive metal, for example aluminum. In particular a reflector frame of this kind can be produced by way of all suitable production processes, for example by a casting process, by shaping, milling, etc. It is also possible to produce a reflector frame of this kind from an electrically non-conductive material, for example plastics material, which is coated with an electrically conductive layer.
In a particularly preferred embodiment the reflector frame is produced from a punching, in particular from a metal sheet, by means of a punching/bending process. In the process it is possible by way of suitable punching and subsequent canting to produce an appropriate three-dimensionally shaped reflector frame from a metal sheet in which the lateral limits or webs are assembled from the metal sheet plane by canting and orientation transverse to the reflector plane. At the same time mutually offset transverse webs can be provided in the add-on direction, whereby the individual radiators or radiator groups are delimited from each other. These transverse webs can also be assembled transversely, and in particular perpendicularly, to the reflector plane by punching and canting or bending.
In a particularly preferred embodiment tongues are formed on the outside of the thus formed transverse webs so as to project away from each other in the axial extension. The tongues can engage in corresponding slotted recesses in the longitudinal lateral limitations if the longitudinal lateral limit has also been assembled in corresponding transverse orientation to the reflector plane following the punching and canting process.
Capacitive coupling of the reflector frame on a printed circuit board without galvanic connection between reflector and printed circuit board ground plane is therefore provided within the scope of the invention. The invention is characterized by a stable intermodulation-free connection. A clearly defined spacing and/or a clearly definable size of the coupling surfaces means that an exactly defined coupling between ground plane of the printed circuit board and the reflector frame may also primarily be ensured within the scope of the invention.
Finally quick and uncomplicated assembly is also possible within the scope of the invention, whereby sources of error are reduced and above all soldered joints are omitted on the reflector.
The completely assembled unit, comprising reflector frame and printed circuit board, forms a self-supporting unit. The reflector frame can be connected to the printed circuit board using any suitable means, for example by means of clips, a double-sided adhesive tape, separate adhesives, etc.
The ground plane on the printed circuit board is preferably originally provided with an insulating layer, for example in the form of paint, in particular a solder resist, a film or some other plastics material layer, which allows metallic isolation from the reflector frame. If the reflector frame is glued by means of a double-sided adhesive tape then this already provides an insulation and therewith metallic isolation between the electrically conductive reflector frame on the one hand and the ground frame on the printed circuit board on the other, so a separate insulating layer can even be omitted on the ground plane.
Further advantages, details and features of the invention emerge from the following embodiments described with reference to figures, in which, in detail:
Basically however any radiator or radiator type can be used within the scope of the invention, in particular dipole radiators and/or patch radiators, as are known for example from anticipatory documents DE 197 22 742 A1, DE 196 27 015 A1, U.S. Pat. No. 5,710,569 A, WO 00/039894 A1 or DE 101 50 150 A1.
The dual-polarized radiator shown in
As also emerges in particular from the exploded view in
The ground plane 7 is conventionally covered with an insulating layer 8, which is indicated in
Building thereon an arrangement 11 that is separately reproduced in
The reflector frame 11 is preferably an electrically conductive material, for example a metal cast part (aluminum, although other materials can also be considered here). This can also be a plastics part which is then metalized, i.e. has been coated with a metallically conductive surface. In particular when producing the reflector frame 11 from metal other production processes may be considered, for example production of the reflector frame by deep-drawing, milling or the like.
From the illustration according to
To assemble the antenna arrangement the radiator assembly 3 is, for example, firstly mounted on the printed circuit board 5, i.e. in particular mechanically fixed, for example by fixing a screw that is to be screwed in from the back of the printed circuit board, or by other clip-like fastening elements, the supporting mechanism and/or balancing means 21, via which the radiator elements 3a of the dual-polarized radiator 3 are held, being capacitively coupled to the ground plane 7 of the printed circuit board 5 located underneath. The reflector frame 11 can also be connected to the printed circuit board for example by the above-described or other suitable mechanical measures.
As the printed circuit board 5, i.e. the ground plane 7 provided thereon, is covered by means of an insulating layer 8 (for example in the form of a paint layer), a capacitive coupling is produced between the underside of the supporting mechanism and/or balancing means 21 (i.e. between the electrically conductive base 21a of the radiator assembly 3 and the ground plane 7) and between the electrically conductive coupling surface 13 and the ground plane 7, i.e. a d.c. or galvanic connection of these parts is reliably avoided. In other words, the paint layer applied to the ground plane would be completely adequate as an insulator, so an additional insulating layer is not necessary to achieve the capacitive coupling.
However the reflector frame 11 is preferably fastened to the top of the printed circuit board 5 by means of double-sided adhesive film 9, the adhesive film 9 being provided with a window-like cut-out 9′, the size and positioning of which matches or approximates the cut-out 13a in the coupling surface 13 of the reflector frame 11. As the insulating layer 8 is conventionally always provided on the ground plane 7 in the form of a paint layer, this insulating layer primarily being used as corrosion protection for the ground plane which is often made of copper, said double-sided adhesive film would be glued to this insulating or paint layer 8. In such a case the ground plane 7 could also not be provided with an insulating layer 8 however.
The adhesive tape 9 can comprise said recess 9′ as it is irrelevant for the electrical functions whether the radiator device in the form of what is referred to as a vector dipole is also likewise held by means of said adhesive tape 9 with respect to the ground plane 7 or printed circuit board 5. The dipole is capacitively coupled (in this case via the lower base 21a) to the ground plane 7 employing the same principles as in relation to the reflector frame 11, so the spacing may also vary to a certain extent (for example 0.5 mm). This being the case, the adhesive film 9 could also be formed so as to be continuous and without window 9′, although this would have certain drawbacks in terms of internal conductor assembly for the radiator assembly 3 as in this case the internal conductor which is to be laid in the radiator device would have to be inserted through the adhesive tape 9. This being the case, the window-like recess 9′ is preferably provided in the adhesive tape 9. In the process the radiator is mounted on the printed circuit board by separate fixing measures while maintaining the capacitive coupling.
If the insulating layer 8 on the ground plane 7 should also be provided with a window, so the insulating layer 8 is omitted in the region of this window (it being possible for this region, where the insulating layer 8 is omitted on the ground plane, to comparably match the size and/or arrangement of the other window 9′ with respect to the double-sided adhesive device 9 and/or recess 13a in the coupling surface 13), the ground plane 7 would be “blank” in this region. In this case the base 21a, i.e. the underside of the supporting mechanism and/or balancing means 21, could also be galvanically connected to the ground plane 7. Holes and are formed in the printed circuit board and axial holes that align therewith are formed in the base 21a of the supporting mechanism and/or balancing means 21 of the radiator assemblies in order to upwardly guide a respective internal conductor, which is used for feeding, from the back of the printed circuit board and to galvanically couple, or inductively couple, as described for example in WO 2005/060049, it via a section of a bridge to the respective diagonally opposite second half 3a of the radiator device 3 located above. This being the case, reference is also made in this regard to the above anticipatory document with respect to the mode of operation.
Following the thus effected pre-assembly the reflector frame 11 is then positioned from above, the radiator assembly 3 then being guided through the recess 13a in the coupling surface 13 and through the recess 9′ in the double-sided adhesive device 9.
Any conceivable connecting methods may be considered to ensure a secure connection between the coupling surface 13, i.e. a secure connection between the reflector frame 11 and the printed circuit board. Thus for example glue can be applied to the top of the printed circuit board (i.e. the ground plane or the insulating layer 8 that covers the ground plane) and/or to the underside of the coupling surface 13. However clip-like parts that mesh when positioned and produce a latching are also possible.
The above-mentioned double-sided adhesive tape 9 is preferably used however, whereby a strictly predefined spacing between the coupling surface 13 and the ground plane 7 is ensured and a mechanically secure connection is produced at the same time. As a result of this type of connection the reflector frame 11 with the printed circuit board 5 constitutes a securely connected, self-supporting unit.
A capacitive coupling is ensured thereby which also ensures the desired capacitive connection of the ground plane for the longitudinal and/or transverse webs 15, 17.
If the longitudinal and transverse webs 15, 17 are not securely connected to each other in their corner regions 19, they can be bent toward or away from one another by different bending, in particular if the reflector frame is made from a metal sheet, whereby the radiation diagram of the antenna can be changed and/or adjusted to the desired extent.
With reference to
It can be seen from the plane developed view according to
Following the effected punching process according to
As may also be seen from
Otherwise the thus formed reflector frame 11 is positioned in the described manner, optionally with separate insertion of an insulating layer or film 9 on the ground plane 7, i.e. ultimately on the printed circuit board 5, and is suitably fixed thereto, as described preferably with insertion of a double-sided adhesive tape 9.
It is clear from the illustration that in this embodiment the window-like recess 13a is not just square but, in contrast, is also larger as once the transverse web 17 has been lifted up a corresponding rectangular portion is removed from the coupling surface. This being the case, the recess 13a is T-shaped in this instance. Only in the illustration according to
In contrast to
Feeding conventionally takes place by means of a coaxial cable which runs from the underside of the reflector through an axial hole 103 leading in the supporting mechanism or balancing means 21 to the plane of the actual dipole and/or radiator halves 3a. The coaxial cable is stripped at the upper end of this axial hole at the level of the dipole and/or radiator halves 3a, so the external conductor, which is insulated in the axial hole 103 from the supporting mechanism and/or balancing means 21, is exposed and in the upper region is then electrically/galvanically connected for example by means of a soldering 201, to the inner end of an associated dipole or radiator half 3a. The drawings in
Alternatively or preferably however a coaxial feeder cable is connected in such a way that the external conductor is held at the lower end of the hole 103, for example at a soldering point 201′, and the internal conductor 101b is held only by an insulator and is separately upwardly guided in the hole 103. The hole in the supporting mechanism therefore acts as an external conductor that surrounds the internal conductor 101b so a more or less coaxial feeder is formed hereby, via which the dipole and/or radiator halves, which as a rule are electrically-galvanically conductively connected to the supporting mechanism as a joint component, are fed.
If one dipole half (which is not fed via the internal conductor) is not fed by an electrical-galvanic coupling, for example in the region of the hole in the supporting mechanism, but for example by soldering-on of an external conductor of a coaxial cable, appropriate feeding can also be brought about capacitively, for example by a capacitive coupling between the base of the supporting mechanism and the ground plane or reflector surface. Therefore the associated feeder, usually the external conductor of a coaxial cable, is conventionally connected in a region underneath the supporting mechanism which, in plan view, is located perpendicularly to the reflector, preferably in the region underneath the dipole or radiator half that is fed thereby.
The internal conductor 101b which is conventionally connected to the internal conductor of a coaxial cable is usually bent substantially at the level of the dipole and/or radiator halves 3a by 90° or substantially 90° and leads to the adjacent inner end of the associated second dipole and/or radiator half 3a and is conventionally electrically connected there by means of soldering 203.
In the case of a dual-polarized radiator, feeding of the dipole and/or radiator halves 3a that are mutually offset by 90° takes place accordingly, the second internal conductor, running so as to cross the first internal conductor 101b, is arranged on a different plane so the two internal conductors do not touch in the middle but bypass each other.
In the case of a simply polarized radiator with just one polarization plane, only one feeder, which is also called an internal conductor, is required.
The embodiment according to
Other types of feeding are also possible.
It is mentioned purely for the sake of completeness that it may also be seen from
| Number | Date | Country | Kind |
|---|---|---|---|
| 102006037518.1 | Aug 2006 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP07/06638 | 7/26/2007 | WO | 00 | 2/6/2009 |
