Antenna feeding network

Abstract

An antenna feeding network for a multi-radiator antenna, the antenna feeding network comprising at least two coaxial lines, wherein each coaxial line comprises an elongated central inner conductor and an elongated outer conductor surrounding the central inner conductor. At least one connector device is configured to interconnect at least a first inner conductor and a second inner conductor of the central inner conductors. The connector device comprises at least one engaging portion, each being configured to engage with at least one corresponding surface portion formed on the envelope surface of the first or second inner conductor. The envelope surface is furthermore provided with at least one recess provided adjacent at least one surface portion.

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 an elongated central inner conductor and an elongated outer conductor surrounding the central inner conductor, further comprising at least one connector device configured to interconnect at least a first inner conductor and a second inner conductor of said central inner conductors, wherein the connector device comprises at least one engaging portion, each being configured to engage with at least one corresponding surface portion formed on an envelope surface of said first or second inner conductor, wherein said envelope surface is provided with at least one recess provided adjacent at least one surface portion, and wherein each engaging portion has a longitudinal length such that it extends at least partly over said at least one recess when said engaging portion engages with said at least one corresponding surface portion.

2. The antenna feeding network according to claim 1, wherein said envelope surface is provided with a recess at an axial end of said surface portion.

3. The antenna feeding network according to claim 1, wherein said envelope surface is provided with recesses at both axial ends of said surface portion.

4. The antenna feeding network according to claim 2, wherein said surface portion has a longitudinal length which is slightly shorter than the longitudinal length of the connector device and/or its engaging portions.

5. The antenna feeding network according to claim 1, wherein at least one of said engaging portions is configured to engage with at least two surface portions formed on said envelope surface, wherein said envelope surface is provided with a recess between said two surface portions.

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

7. The antenna feeding network according to claim 1, wherein said connector device is configured to interconnect first and second inner conductors indirectly.

8. The antenna feeding network according to claim 1, wherein an insulating layer is provided on said at least one engaging portion and/or on said at least one surface portion.

9. The antenna feeding network according to claim 1, wherein said connector device is provided as a snap on element, wherein each engaging portion is formed as a pair of snap on fingers, wherein each pair of snap on fingers are adapted to be snapped onto the first or the second inner conductor.

10. The antenna feeding network according to claim 1, wherein at least two of the outer conductors are provided with an opening, wherein said antenna feeding network further comprises at least one non-conductive holding element configured to be placed in the opening, wherein said non-conductive holding element comprises at least one passage adapted to receive said connector device therein.

11. The antenna feeding network according to claim 1, wherein the connector device is configured to be removably connected to the first inner conductor and the second inner conductor.

12. A multi-radiator antenna comprising: an antenna feeding network comprising: at least two coaxial lines, wherein each coaxial line comprises an elongated central inner conductor and an elongated outer conductor surrounding the central inner conductor, further comprising at least one connector device configured to interconnect at least a first inner conductor and a second inner conductor of said central inner conductors, wherein the connector device comprises at least one engaging portion, each being configured to engage with at least one corresponding surface portion formed on an envelope surface of said first or second inner conductor, wherein said envelope surface is provided with at least one recess provided adjacent at least one surface portion, and wherein each engaging portion has a longitudinal length such that it extends at least partly over said at least one recess when said engaging portion engages with said at least one corresponding surface portion; and radiating elements being connected to said antenna feeding network.

13. The multi-radiator antenna of claim 12, wherein said envelope surface is provided with a recess at an axial end of said surface portion.

14. The multi-radiator antenna according to claim 12, wherein said envelope surface is provided with recesses at both axial ends of said surface portion.

15. The multi-radiator antenna according to claim 13, wherein said surface portion has a longitudinal length which is slightly shorter than the longitudinal length of the connector device and/or its engaging portions.

16. The multi-radiator antenna according to claim 12, wherein at least one of said engaging portions is configured to engage with at least two surface portions formed on said envelope surface, wherein said envelope surface is provided with a recess between said two surface portions.

17. The multi-radiator antenna according to claim 12, wherein said coaxial lines are substantially air filled coaxial lines, each being provided with air between the inner and outer conductors.

18. The multi-radiator antenna to claim 12, wherein said connector device is configured to interconnect first and second inner conductors indirectly.

19. The multi-radiator antenna to claim 12, wherein an insulating layer is provided on said at least one engaging portion and/or on said at least one surface portion.

20. The multi-radiator antenna to claim 12, wherein said connector device is provided as a snap on element, wherein each engaging portion is formed as a pair of snap on fingers, wherein each pair of snap on fingers are adapted to be snapped onto the first or the second inner conductor.

21. The multi-radiator antenna according to claim 12, wherein at least two of the outer conductors are provided with an opening, wherein said antenna feeding network further comprises at least one non-conductive holding element configured to be placed in the opening, wherein said non-conductive holding element comprises at least one passage adapted to receive said connector device therein.

22. The multi-radiator antenna according to claim 12, wherein the connector device is configured to be removably connected to the first inner conductor and the second inner conductor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) 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:

(2) FIG. 1 schematically illustrates a multi-radiator antenna;

(3) FIG. 2 schematically illustrates a perspective view of an embodiment of a multi-radiator antenna according to the second aspect of the invention;

(4) FIG. 3 schematically illustrates a perspective view of an embodiment of an antenna feeding network according to the first aspect of the invention;

(5) FIG. 4 schematically illustrates a perspective view of parts of an embodiment of an antenna feeding network according to the first aspect of the invention; and

(6) FIG. 5 schematically illustrates a perspective view of parts of another embodiment of an antenna feeding network according to the first aspect of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(7) 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. 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.

(8) FIG. 2 illustrates a multi-radiator antenna 1 in a perspective view, the antenna 1 comprising the electrically conductive reflector 4 and radiating elements 6a-c. The electrically conductive reflector 4 comprises a front side 17, where the radiating elements 6a-c are mounted and a back side 19. The shown view is a cross section through the coaxial lines 20a-b, the reflector 4, and the connector device 8.

(9) A first coaxial line 20a 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 has 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.

(10) 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.

(11) 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.

(12) 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.

(13) 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.

(14) In FIG. 3, an enlarged view of the opening 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 engaging portions 30, 30 of the connector device 8 that engage the first and second inner conductors 14a, 14b.

(15) The connector device 8 comprises a bridge portion 32 and two engaging portions, which are provided as 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.

(16) 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.

(17) 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.

(18) FIG. 3 further shows a holding element 41. The holding element is made of plastic, but may in other embodiments be made from other electrically insulating materials. The holding element 41 comprises a body portion having an opening or passage. The body portion is adapted to have a shape that corresponds at least more or less to the shape of the opening 40. The connector device 8 can be installed on the two inner conductors 14 after the holding element 41 is put in place. The connector device 8 is inserted and guided through the opening or passage when the two or more inner conductors are engaged. The holding element fixates the connector device 8 in the axial or lengthwise direction.

(19) FIG. 4 shows a view of parts of an embodiment of the antenna feeding network, which embodiment is similar to the embodiment shown in FIGS. 2-3. A first engaging portion in the form of snap-on fingers 30 of the connector device 8 engage with a surface portion 33 formed on the envelope surface of the second inner conductor 14b. In this embodiment, the surface portion 33 is formed at a portion of the envelope surface which has a smaller diameter than the leftmost and rightmost portions of the second inner conductor shown in the figure. In other embodiments, the envelope surface may however have a uniform diameter. First and second recesses 34a, 34b are formed immediately (axially) adjacent the surface portion 33 at opposite axial ends thereof. A second engaging portion in the form of snap-on fingers 30 of the connector device 8 engage with a surface portion (not shown) formed on the envelope surface of the first inner conductor 14a near an end thereof. Third and fourth recesses are formed immediately (axially) adjacent the surface portion at opposite ends thereof. In the figure, only the third recess 34c is visible. The fourth recess (not visible) is formed at an axial end of the first inner conductor 14a. The recesses are provided as axial segments of the inner conductors 14a, 14b having a smaller diameter than the surface portions. The surface portions both have an axial extension which is slightly shorter than that of the connector device 8 such that any burrs or protrusion at the axial ends of the connector device caused by cutting the connector device into the desired length will be protrude into a corresponding recess 34a-c without making contact with the respective inner conductor. As can be seen in the figure, the engaging portion 30 has a longitudinal length greater than that of the surface portion 33, i.e. the engaging portion 30 has a longitudinal length or extension such that it extends partly over the first and second recesses 34a-b. The engaging portion 30 also has a longitudinal length greater than that of the corresponding surface portion, i.e. the engaging portion 30 has a longitudinal length or extension such that it extends partly over the third and fourth recesses.

(20) FIG. 5 shows a view of parts of an embodiment of the antenna feeding network, which embodiment is similar to the embodiment shown in FIG. 4. A first engaging portion in the form of snap-on fingers 30 of the connector device 8 engage with two surface portions 33a, 33b formed on the envelope surface of the second inner conductor 14b. In this embodiment, the surface portions 33a-b are formed at a portion of the envelope surface which has a smaller diameter than the leftmost and rightmost portions of the second inner conductor shown in the figure. In other embodiments, the envelope surface may however have a uniform diameter. A recess 34d is formed between the surface portions 33a, 33b, i.e. adjacent both surface portions. A second engaging portion in the form of snap-on fingers 30 of the connector device 8 engage with two surface portions (only one is visible: 33c) formed on the envelope surface of the first inner conductor 14a at the end thereof. A recess (not visible) is formed between the surface portions in the same way as on the second conductor 14b. The recesses are provided as axial segments of the inner conductors 14a, 14b having a smaller diameter than the surface portions. In this embodiment, the connector device 8 has been manufactured by moulding, causing a protrusion 8 at the middle (in the axial direction) of the connector device where the mould is divided. The recesses in the inner conductors are positioned and dimensioned such that the portions of the protrusion 8 which extends inwardly from the snap-on fingers 30, 30 extend into the respective recess without making contact with the respective inner conductor. As can be seen in the figure, the engaging portion 30 extends over recess 34d.

(21) In the embodiments shown in FIGS. 4-5, 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.

(22) In the various embodiments described above, the connector device 8 is provided with a thin insulating layer on the connector device 8. The insulating layer may be formed of a polymer material or an electrically isolating oxide layer or a combination thereof, or by any other suitable material which achieves the desired insulating properties. It may however be possible to provide the first and second inner conductors 14a, 14b respectively with a thin insulating layer of a polymer material or an electrically isolating oxide layer or a combination thereof, or by any other suitable material which achieves the desired insulating properties. In embodiments, both the connector device and the first and second inner conductors are provided with insulating layers as described above. In other embodiments, the connector device may be provided without any insulating layer, or the first and second inner conductors may be provided without any insulating layers, i.e. only one of the connector device and first/second inner conductors is provided with an 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. 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.

(23) 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.

(24) 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 device 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.