ANTENNA FEEDING NETWORK

Abstract

An antenna feeding network for a multi-radiator antenna, the antenna feeding network comprising at least two coaxial lines. Each coaxial line comprises a central inner conductor and an elongated outer conductor surrounding the central inner conductor. At least a first inner conductor and a second inner conductor of the at least two coaxial lines are indirectly interconnected.

Claims

1. An antenna feeding network for a multi-radiator antenna, the antenna feeding network comprising at least two coaxial lines, wherein each coaxial line comprises a central inner conductor and an elongated outer conductor surrounding the central inner conductor, further comprising at least one connector device configured to indirectly interconnect at least a first inner conductor and second inner conductor of said central inner conductors, wherein the connector device is configured to be removably connected to the first inner conductor (14a) and the second inner conductor.

2. The antenna feeding network according to claim 1, wherein the at least two coaxial lines are substantially air filled coaxial lines, each being provided with air between the inner and outer conductors.

3. The antenna feeding network according to claim 1, wherein said at least first and second inner conductors are interconnected capacitively and/or inductively.

4. The antenna feeding network according to claim 1, comprising at least one insulating layer, wherein the insulating layer is arranged on the connector device and/or on the first inner conductor and/or the second inner conductor.

5. The antenna feeding network according to claim 1, comprising at least one insulating layer, wherein the insulating layer is arranged between the connector device and the first inner conductor and/or the second inner conductor.

6. The antenna feeding network according to claim 1 wherein the connector device comprises a core made of an electrically conductive material and an electrically insulating layer arranged around the core.

7. The antenna feeding network according to claim 6, wherein the insulating material is a polymer with a thickness of less than or equal to 50 pm, such as from 1 pm to 20 pm.

8. The antenna feeding network according to claim 1, wherein the connector device is realized as a snap on element comprising at least one pair of snap on fingers and a bridge portion, whereby the snap on fingers are connected to the bridge portion and wherein the snap on fingers are adapted to be snapped onto the first or the second inner conductor.

9. The antenna feeding network according to claim 8, wherein the snap on element comprises two pairs of snap on fingers that are connected by the bridge portion and wherein one of the pairs of snap on fingers are configured to be snapped onto the first inner conductor and the other of the pairs of snap on fingers are configured to be snapped onto the second inner conductor, respectively.

10. The antenna feeding network according to claim 1, wherein the connector device comprises at least two engaging portions, and wherein each of said at least first and second inner conductors comprises corresponding engaging portions, each adapted to engage with a corresponding engaging portion of the connector device, wherein each engaging portion is in the form of a cavity or rod-shaped protrusion.

11. The antenna feeding network according to claim 10, wherein the connector device is provided with three legs, each being provided with an engaging portion at its end to interconnect three inner conductors.

12. The antenna feeding network according to claim 1, wherein one of the first and second inner conductors comprises a cavity and wherein the other inner conductor comprises a rod-shaped protrusion configured to extend into and engage with said cavity, wherein an insulating layer is provided in said cavity and/or on said rod-shaped protrusion, or wherein an insulating layer is provided between said cavity and said rod-shaped protrusion.

13. The antenna feeding network according to claim 10, wherein said protrusion has a length of a quarter of a wavelength.

14. A multi radiator antenna comprising an electrically conductive reflector, at least one radiating element arranged on said reflector and an antenna feeding network, said radiating elements being connected to said antenna feeding network, said antenna feeding network comprising at least two coaxial lines, wherein each coaxial line comprises a central inner conductor and an elongated outer conductor surrounding the central inner conductor, further comprising at least one connector device configured to indirectly interconnect at least a first inner conductor and second inner conductor of said central inner conductors, wherein the connector device is configured to be removably connected to the first inner conductor (14a) and the second inner conductor.

15. The multi radiator antenna according to claim 14, wherein the electrically conductive reflector comprises at least one opening on the front side or the back side adapted to the size of the connector device such that said connector device can be installed via said opening.

16. A method for assembling an antenna feeding network for a multi-radiator antenna, said method comprising: providing at least two coaxial lines, wherein each coaxial line is provided with a central inner conductor and an elongated outer conductor surrounding the central inner conductor; and interconnecting at least a first inner conductor and a second inner conductor of said central inner conductors indirectly providing a connector device; and providing an insulating layer on said connector device and/or on said at least first and second conductors, or providing an insulating layer between said connector device and said at least first and second conductors; wherein said interconnecting comprises connecting said connector device between said at least first and second inner conductors, wherein said connector device is adapted to be removably connected to the first inner conductor and the second inner conductor.

17. The method according to claim 18, wherein said connector device is realized as a snap on element comprising snap on fingers adapted to be snapped onto the at least first and second inner conductors.

18. The multi radiator antenna according to claim 14, wherein the at least two coaxial lines are substantially air filled coaxial lines, each being provided with air between the inner and outer conductors.

19. The multi radiator antenna according to claim 14, wherein said at least first and second inner conductors are interconnected capacitively and/or inductively.

20. The multi radiator antenna according to claim 14, comprising at least one insulating layer, wherein the insulating layer is arranged on the connector device and/or on the first inner conductor and/or the second inner conductor.

21. The multi radiator antenna according to claim 14, comprising at least one insulating layer, wherein the insulating layer is arranged between the connector device and the first inner conductor and/or the second inner conductor.

22. The multi radiator antenna according to claim 14, wherein the connector device comprises a core made of an electrically conductive material and an electrically insulating layer arranged around the core.

23. The multi radiator antenna according to claim 14, wherein the insulating material is a polymer with a thickness of less than or equal to 50 pm, such as from 1 pm to 20 pm.

24. The multi radiator antenna according to claim 14, wherein the connector device is realized as a snap on element comprising at least one pair of snap on fingers and a bridge portion, whereby the snap on fingers are connected to the bridge portion and wherein the snap on fingers are adapted to be snapped onto the first or the second inner conductor.

25. The multi radiator antenna according to claim 24, wherein the snap on element comprises two pairs of snap on fingers that are connected by the bridge portion and wherein one of the pairs of snap on fingers are configured to be snapped onto the first inner conductor and the other of the pairs of snap on fingers are configured to be snapped onto the second inner conductor, respectively.

26. The multi radiator antenna according to claim 14, wherein the connector device comprises at least two engaging portions, and wherein each of said at least first and second inner conductors comprises corresponding engaging portions, each adapted to engage with a corresponding engaging portion of the connector device, wherein each engaging portion is in the form of a cavity or rod-shaped protrusion.

27. The multi radiator antenna according to claim 26, wherein the connector device is provided with three legs, each being provided with an engaging portion at its end to interconnect three inner conductors.

28. The multi radiator antenna according to claim 14, wherein one of the first and second inner conductors comprises a cavity and wherein the other inner conductor comprises a rod-shaped protrusion configured to extend into and engage with said cavity, wherein an insulating layer is provided in said cavity and/or on said rod-shaped protrusion, or wherein an insulating layer is provided between said cavity and said rod-shaped protrusion.

29. The multi radiator antenna according to claim 26, wherein said protrusion has a length of a quarter of a wavelength.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention will now be described, for exemplary purposes, in more detail by way of embodiments and with reference to the enclosed drawings, in which:

[0032] FIG. 1 schematically illustrates a multi-radiator antenna;

[0033] FIG. 2 schematically illustrates a perspective view of an embodiment of a multi-radiator antenna according to the second aspect of the invention;

[0034] FIG. 3 schematically illustrates a perspective view of an embodiment of an antenna feeding network according to the first aspect of the invention;

[0035] FIG. 4 schematically illustrates another perspective view of parts of an embodiment of an antenna feeding network according to the first aspect of the invention;

[0036] FIG. 5 schematically illustrates a front view into two neighbouring coaxial lines of an embodiment of an antenna feeding network according to the first aspect of the invention;

[0037] FIG. 6 schematically illustrates parts of another embodiment of an antenna feeding network according to the first aspect of the invention; and

[0038] FIG. 7 schematically illustrates parts of yet another embodiment of an antenna feeding network according to the first aspect of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0039] FIG. 1 schematically illustrates an antenna arrangement 1 comprising an antenna feeding network 2, an electrically conductive reflector 4, which is shown schematically in FIG. 1, and a plurality of radiating elements 6. The radiating elements 6 may be dipoles.

[0040] The antenna feeding network 2 connects a coaxial connector 10 to the plurality of radiating elements 6 via a plurality of lines 14, 15, which may be coaxial lines, which are schematically illustrated in FIG. 1. The signal to/from the connector 10 is split/combined using, in this example, three stages of splitters/combiners 12 Turning now to FIG. 2, which illustrates a multi-radiator antenna 1 in a perspective view, the antenna 1 comprises the electrically conductive reflector 4 and radiating elements 6a-c.

[0041] The electrically conductive reflector 4 comprises a front side 17, where the radiating elements 6a-c are mounted and a back side 19.

[0042] FIG. 2 shows a first coaxial line 20a which comprises a first central inner conductor 14a, an elongated outer conductor 15a forming a cavity or compartment around the central inner conductor, and a corresponding second coaxial line 20b having a second inner conductor 14b and an elongated outer conductor 15b. The outer conductors 15a, 15b have square cross sections and are formed integrally and in parallel to form a self-supporting structure. The wall which separates the coaxial lines 20a, 20b constitute vertical parts of the outer conductors 15a, 15b of both lines. The first and second outer conductors 15a, 15b are formed integrally with the reflector 4 in the sense that the upper and lower walls of the outer conductors are formed by the front side 17 and the back side 19 of the reflector, respectively.

[0043] Although the first and second inner conductors 14a, 14b are illustrated as neighbouring inner conductors they may actually be further apart thus having one or more coaxial lines, or empty cavities or compartments, in between.

[0044] In FIG. 2 not all longitudinal channels or outer conductors are illustrated with inner conductors, it is however clear that they may comprise such inner conductors.

[0045] The front side 17 of the reflector comprises at least one opening 40 for the installation of the connector device 8. The opening 40 extends over the two neighbouring coaxial lines 20a, 20b so that the connector device 8 can engage the first and second inner conductors 14a, 14b.

[0046] Although the invention is illustrated with two neighbouring inner conductors 14a, 14b it falls within the scope to have an opening (not shown) that extends across more than two coaxial lines 20a, 20b and to provide a connector device 8 than can bridge two or even more inner conductors. Such a connector device (not shown) may thus be designed so that it extends over a plurality of coaxial lines between two inner conductors or over empty cavities or compartments. Such a connector device (not shown) may also be used to connect three or more inner conductors.

[0047] In FIG. 3, an enlarged view of the opening 40 and the connector device 8 arranged therein is illustrated. The connector device 8 is clipped or snapped onto the first inner conductor 14a and the second inner conductor 14b. The connection between the first inner conductor 14a and the second inner conductor 14b is electrically indirect, which means that it is either capacitive, inductive or a combination thereof. This is achieved by providing a thin insulating layer of a polymer material or some other insulating material (e.g. a non-conducting oxide) on the connector device 8. The insulating layer may have a thickness of 1 m to 20 m, such as from 5 m to 15 m, such as from 8 m to 12 m, or may have a thickness of 1 m to 5 m. The insulating layer may cover the entire outer surface of the connector device 8, or at least the portions 30, 30 of the connector device 8 that engage the first and second inner conductors 14a, 14b.

[0048] The connector device 8 comprises a bridge portion 32 and two pairs of snap on fingers 30, 30. One of the two pairs of snap on fingers 30 is arranged close to one end of the bridge portion 32 and the other of the two pairs of snap on fingers 30 is arranged close to the other end of the bridge portion 32. The two pairs of snap on fingers 30, 30 may be connected to the bridge portion 32 via connecting portions configured such that the bridge portion 32 is distanced from the first and second inner conductors 14a, 14b. In other embodiments, the snap on fingers 30, 30 are connected directly to the bridge portion 32. The connecting portions, as well as the other portions of the connector device, are shaped to optimize the impedance matching of the splitter/combiner formed by the connector device and the coaxial lines. The shape, or preferably the diameter of the connecting inner conductors may also contribute to the matching of the splitter/combiner.

[0049] As can be seen from FIG. 3, the vertical separating wall portion 22 is cut down to about two-thirds to three-quarters of its original height in the area of the opening 40 so that the connector device 8 does not protrude over the front side 17 of the electrically conductive reflector 4. In other embodiments, the wall portion 22 is cut down all the way to the floor of the outer conductors. The remaining height of the wall portion is adapted together with the other components, such as the connector device to optimize the impedance match.

[0050] It may be possible (not shown in the figures) to provide only one pair of snap on fingers, for example the pair of snap on fingers 30 engaging the first inner conductor 14a providing an indirect connection, and to let the other end of the bridge portion 32 contact the second inner conductor 14b directly without insulating layer or coating. This direct connection can be provided by connecting the bridge portion 32 to inner conductor 14b by means of a screw connection, or by means of soldering, or by making the bridge portion an integral part of inner conductor 14b, or by some other means providing a direct connection.

[0051] FIG. 4 shows another view of parts of an embodiment of the antenna feeding network. The connector device 8 engages the first and second inner conductors 14a, 14b. The connector device 8 and the inner conductors 14a, 14b together form a splitter/combiner. When operating as a splitter, the inner conductor 14a is part of the incoming line, and the two ends of the inner conductor 14b are the two outputs of the splitter. The U-shaped dielectric element 9 can be moved along the inner conductor 14b, which, together with an outer conductor (not shown), forms first and second coaxial output lines on opposite sides of the connector device 8. The dielectric element thus has various positions along those coaxial output lines.

[0052] We first consider the case when the dielectric element 9 is placed in a central position, equally filling the first and second output coaxial lines. When a signal is entered at the input coaxial line 14a, it will be divided between the first output coaxial line and the second output coaxial line, and the signals coming from the two output coaxial lines will be equal in phase. If the dielectric element 9 is moved in such a way that the first output coaxial line will be more filled with dielectric material than the second output coaxial line, the phase shift from the input to the first output will increase. At the same time the second output coaxial line will be less filled with dielectric, and the phase shift from the input to the second output will decrease. Hence, the phase at the first output will lag the phase at the second output. If the dielectric element is moved in the opposite direction, the phase of the first output will lead the phase of the second output. The splitter/combiner may thus be described as a differential phase shifter.

[0053] FIG. 4 illustrates how the connector device 8 engages the first and second inner conductors 14a, 14b in circumferential recessed areas or grooves 42 of the first and second inner conductors 14a, 14b. These grooves may be used to position the connector device 8 correctly along the longitudinal direction of the inner conductors 14a, 14b.

[0054] FIG. 5 illustrates a view into the first and second coaxial lines 20a, 20b where the connector device 8, bridging the first inner conductor 14a and the second inner conductor 14b is visible. The snap on fingers 30, 30 are not so well visible since the snap on fingers 30, 30 engage the first and second inner conductors 14a, 14b in areas with a smaller diameter than the rest of the first and second inner conductors 14a, 14b. FIG. 5 further illustrates that the bridge portion 32 is not extending beyond the front side 17 of the electrically conductive reflector.

[0055] The embodiment of the connector device 8 has been described having a thin insulating layer on the connector device 8. It may however be possible to provide the first and second inner conductors 14a, 14b respectively with a very thin insulating layer of a polymer material and provide the connector device without any insulating layer. The insulating layer may cover the entire outer surface of the first and second inner conductors 14a, 14b, or at least the portions where snap on fingers 30, 30 of the connector device 8 engage the first and second inner conductors 14a, 14b. In other embodiments, an isolating material in the form of a thin foil is placed between the snap-on fingers 30, 30 and the inner conductor 14.

[0056] Further, the connector device 8 has been described illustrating a first and a second inner conductor 14a, 14b in the antenna arrangement 1. The antenna arrangement 1 may however comprise more than one connector device 8 and a plurality of inner conductors 14a, 14b.

[0057] FIG. 6 schematically illustrates parts of another embodiment of an antenna feeding network according to the first aspect of the invention. In FIG. 6, a cross section view is shown of a first inner conductor 14a and a second inner conductor 14b. The first inner conductor 14a comprises a cavity 50 extending axially into one of its ends. The second inner conductor 14b comprises a rod-shaped protrusion 51 extending axially from one of its ends. The protrusion 51 is adapted to extend into the cavity 50 of the first inner conductor. An insulating layer 52 is provided in and around the cavity to provide an indirect electrical connection between the conductors. In other embodiments, the insulating layer may be provided on the protrusion 51, or as a separate insulating film between the conductors. The insulating layer may be provided as a polymer material or some other insulating material (e.g. a non-conducting oxide) on either or both inner conductors 14a or 14b, completely or partially covering inner conductors 14a or 14ab, or it may be provided as a thin insulating foil inserted between inner conductors 14a and 14b.

[0058] FIG. 7 schematically illustrates parts of yet another embodiment of an antenna feeding network according to the first aspect of the invention. In FIG. 7, a cross section view is shown of three inner conductors 14a, 14b and 14c and a three legged h-shaped connector device 8. Each leg of the connector device 8 is provided with a cavity 50a-c extending axially into their respective ends. The inner conductors 14a-c each comprises a rod-shaped protrusion 51a-c extending axially from one of its ends. The protrusions 51a-c extend into corresponding cavities 50a-c of the connector device. Insulating layers 52a-c are provided in and around the cavities to provide an indirect electrical connection between the conductors. In other embodiments, the insulating layers may be provided on the protrusions, or as separate insulating films between the conductors and the connector device. The h-shaped connector device 8 may be mounted in a similar manner as the connector device 8, i.e. by cutting down a separating wall between two adjacent outer conductors. In other embodiments, the connector device 8 is provided with protrusions, and the inner conductors 14-c are provided with cavities.

[0059] The description above and the appended drawings are to be considered as non-limiting examples of the invention. The person skilled in the art realizes that several changes and modifications may be made within the scope of the invention. For example, the number of coaxial lines may be varied and the number of radiators/dipoles may be varied. Furthermore, the shape of the connector element (if any) and inner conductors and the placement of the insulating layer or coating may be varied. Furthermore, the reflector does not necessarily need to be formed integrally with the coaxial lines, but may on the contrary be a separate element. The scope of protection is determined by the appended patent claims.