Magnetic core, method for manufacturing a magnetic core and balun with a magnetic core

Abstract

Magnetic core for a balun, balun with a magnetic core and method for manufacturing a magnetic core. In particular, a magnetic core is provided comprising multiple core elements, wherein the individual core elements are concentrically arranged. Furthermore, a heat sink is arranged between two adjacent core elements. By using multiple core elements for a magnetic core, the individual core elements can be adapted to different frequency ranges. In this way, the magnetic core may be used for a balun having a broad frequency range. Furthermore, thermal energy generated in the magnetic core can be dissipated by the heat sinks between the individual core elements. In this way, the power handling capability of the magnetic core can be increased.

Claims

1. A magnetic core for a balun, the magnetic core comprising: a number of at least three core elements; at least two heat sinks; and a cooler thermally coupled with the at least two heat sinks, wherein the cooler is adapted to dissipate thermal energy from the at least two heat sinks, wherein the number of core elements and the at least two heat sinks are arranged concentrically, and wherein each of the at least two heat sinks is arranged between two adjacent core elements, and wherein the number of core elements and has a cylindrical shape or a hollow cylindrical shape, wherein each core element of the number of core elements is adapted to achieve a predetermined bandwidth of the balun, wherein a length or a thickness of the individual core elements is adapted to respective frequencies, which magnetize the corresponding core elements.

2. The magnetic core of claim 1, wherein each core element of the number of core elements comprises a ferrite.

3. The magnetic core of claim 1, wherein each core element of the number of core elements comprises a same material.

4. The magnetic core of claim 1, wherein the materials of each core element of the number of core elements are different.

5. The magnetic core of claim 1, wherein the at least one heat sink comprises a metallic material.

6. The magnetic core of claim 1, wherein the at least one heat sink comprises a ceramic material.

7. The magnetic core of claim 1, wherein the at least one heat sink has a cylindrical shape or a hollow cylindrical shape.

8. The magnetic core of claim 1, wherein each of the at least one heat sinks is arranged in thermal connection with two adjacent core elements.

9. The magnetic core of claim 1, wherein the cooler comprises a liquid cooling device.

10. The magnetic core of claim 1, wherein the cooler comprises an air cooling device.

11. A balun, the balun comprising: a magnetic core comprising a number of at least three core elements, at least two heat sinks and a cooler thermally coupled with the at least two heat sinks, wherein the cooler is adapted to dissipate thermal energy from the at least two heat sinks, wherein the number of core elements and the at least two heat sinks are arranged concentrically, wherein each of the at least two heat sinks is arranged between two adjacent core elements, and wherein the number of core elements has a cylindrical shape or a hollow cylindrical shape or a hollow cylindrical shape, wherein each core element of the number of core elements is adapted to achieve a predetermined bandwidth of the balun, wherein a length or a thickness of the individual core elements is adapted to respective frequencies, which magnetize the corresponding core elements.

12. The balun of claim 11, wherein the balun is a symmetrical balun.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) For a more complete understanding of the present invention and advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings. The invention is explained in more detail below using exemplary embodiments which are specified in the schematic figures of the drawings, in which:

(2) FIG. 1 shows a cross-section of a magnetic core according to an embodiment of the present invention;

(3) FIG. 2 shows a cross-section of a magnetic core according to another embodiment of the present invention;

(4) FIG. 3 shows schematic view of a magnetic core according to an embodiment of the present invention;

(5) FIG. 4 shows a circuit diagram of a balun according to an embodiment of the present invention;

(6) FIG. 5 shows a circuit diagram of a balun according to a further embodiment of the present invention; and

(7) FIG. 6 shows a block diagram of an embodiment of a method according to the present invention.

(8) The appended drawings are intended to provide further understanding of the embodiments of the invention. They illustrate embodiments and, in conjunction with the description, help to explain principles and concepts of the invention. Other embodiments and many of the advantages mentioned become apparent in view of the drawings. The elements in the drawings are not necessarily shown to scale.

(9) In the drawings, like, functionally equivalent and identically operating elements, features and components are provided with like reference signs in each case, unless stated otherwise.

DETAILED DESCRIPTION

(10) FIG. 1 shows a cross-section of a magnetic core 1 according to an embodiment. The magnetic core 1 may be used, for example for a balun. As can be seen in FIG. 1, the magnetic core 1 may comprise a number of at least two core elements 11, 12. Furthermore, the magnetic core 1 comprises at least one heat sink 21. The heat sink 21 is arranged between the two core elements 11, 12. The core elements 11, 12 may be manufactured as hollow cylinders. Accordingly, the heat sink 21 may be also have a shape of a hollow cylinder. In particular, the dimensions of the two core elements 11, 12 and the heat sink 21 may be such that the individual elements fit right into each other. In other words, the outer diameter of the inner core element 11 almost corresponds to the inner diameter of the heat sink 21. Accordingly, the inner diameter of the outer core element 12 almost corresponds to the outer diameter of the heat sink 21. In this way, a thermal connection between the heat sink 21 and the core elements 11, 12 can be achieved.

(11) For example, the core elements 11, 12 and the heat sink 21 may be pressed together. However, it may be also possible that a thermal conductive glue may be used to combine the core elements 11, 12 and the heat sink 21. Furthermore, a thermal compound may be used for thermally coupling the heat sink 21 and the core elements 11, 12.

(12) As can be further seen in FIG. 1 the innermost core element 11 may be a hollow cylinder, i.e. the innermost core element 11 may have an inner opening. In this way, one or more conductors may be put through this opening when building a balun.

(13) FIG. 2 shows a further embodiment of a magnetic core 1. The magnetic core 1 according to FIG. 2 mainly corresponds to the previously described magnetic core 1. Thus, explanation in connection with FIG. 1 also applies to the magnetic core 1 of FIG. 2, and vice versa, the explanation in connection with FIG. 2 may be also applied to the magnetic core of FIG. 1.

(14) The magnetic core 1 in FIG. 2 differs from the previously described magnetic core 1 in that the magnetic core 1 according to FIG. 2 comprises a further core element 13 and a further heat sink 22. However, it is understood that the present invention is not limited to only two or three magnetic core elements 11, 12, 13 and one or two heat sinks 21, 22. Furthermore, any appropriate number of core elements 11, 12, 13 and any appropriate number of heat sinks 21, 22 may be used. In particular, the number of core elements 11, 12, 13 may be one greater than the number of heat sinks 21, 22.

(15) The individual core elements 11, 12, 13 may be all manufactured by a same material. In particular, an appropriate ferrite, such as a soft magnetic ferrite may be used for the core elements 11, 12, 13. However, it is understood that any other appropriate material for a magnetic core may be also used. By adapting the size of the individual core elements 11, 12, 13, the characteristic properties of the individual core elements may be adapted. For example, if a signal is transmitted through the inner opening of the magnetic core 1, the higher frequencies will only magnetize the innermost core element 11. Hence, the dimensions of the innermost core element 11 may be adapted based on the desired properties for the higher frequency components. Furthermore, lower frequency components of a signal which is guided through the inner opening of the magnetic core 1 will magnetize not only the innermost core element 11, but also further core elements 12 and 13. Thus, the dimensions of the further core elements 12, 13 may be adapted depending on the respective frequencies which magnetize the corresponding core elements 12, 13. Hence, a length and/or a thickness of the individual core elements 11, 12, 13 may be adapted depending on the respective frequencies.

(16) Alternatively, it may be also possible to use different materials for the core elements 11, 12, 13. For example, a different material may be used for each of the core elements 11, 12, 13. For example, customized materials for magnetic cores are available from Ferroxcube. However, any other appropriate material for a magnetic core, in particular customized materials for magnetic cores may be also used. As already explained above, higher frequencies will only magnetize inner magnetic cores 11, and lower frequencies may also magnetize outer magnetic cores 13. Thus, by selecting appropriate materials for each of the magnetic core elements 11, 12, 13, the frequency characteristics of the magnetic core 1 may be adapted accordingly. For example, Ferroxcube 4C5 may be used for an inner core which is magnetized by higher frequencies, and Ferroxcube N30 may be used for an outer core element 12 or 13 which is also magnetized by lower frequencies.

(17) The heat sinks 21, 22 may comprise any appropriate material for conducting the thermal energy which is generated in the magnetic core 1. For example, the heat sinks 21, 22 may comprise a metal and/or a ceramic. However, any other appropriate material, for example a polymer such as polytetrafluoroethylene (PTFE, Teflon) may be also used as a heat sink. The heat sinks 21, 22 may dissipate the thermal energy generated in the core elements 11, 12, 13. For example, parasitic resonances may be eliminated and the energy of these parasitic resonances may be converted to thermal energy which is dissipated by the heat sinks 21, 22.

(18) In case the heat sinks 21, 22 may comprise electrically conductive material, e.g. a metal, the heat sinks 21, 22 may also provide a shield against stray fields. In this way, the shielding may provide a further improvement with respect to the high frequency performance.

(19) FIG. 3 shows a schematic drawing of a magnetic core 1 according to a further embodiment. Further to the core elements 11, 12, 13 and the heat sinks 21, 22 as described above, the core element 1 in this embodiment comprises an additional cooler 30. The cooler 30 may be thermally coupled with the heat sinks 21, 22. Accordingly, cooler 30 may dissipate the thermal energy which is conducted from the core elements 11, 12, 13 to the cooler 30. Cooler 30 may be a passive cooler comprising cooling elements for emitting the thermal energy. Alternatively, cooler 30 may be an active cooler. For example, cooler 30 may comprise a fan for providing a forced air cooling. In another embodiment, cooler 30 may be a cooler comprising a fluid cooling system. For example, water or another fluid may be used for dissipating the thermal energy from the heat sink to the environment. For this purpose, a pump (not shown) may be used for pumping around the fluid. However, it is understood that any other kind of cooler 30 may be also applied for dissipating the thermal energy.

(20) FIG. 4 shows a schematic circuit diagram of a balun 2 according to an embodiment. As can be seen in FIG. 4, the balun 2 comprises an unbalanced port 100. A first terminal 101 of the unbalanced port may be grounded. Another terminal 102 of the unbalanced port 100 may be connected with a signal line. For example, the unbalanced port may be connected with a coaxial cable 300. However, any other cable may be also used. The cable 300 may be arranged in the inner part of the magnetic core 1. The other end of the cable 300 may be connected with a balanced port 200. The balanced port 200 may comprise a first terminal 201 and a second terminal 202. For example, the first terminal 201 may be connected with an inner conductor of the coaxial cable 300 and the second terminal 202 may be connected with the shielding of the coaxial cable 300.

(21) FIG. 5 shows a further embodiment of a balun 2. The balun 2 according to FIG. 5 comprises two cables 301, 302. A first terminal 101 of the unbalanced port 100 may be connected with an inner connector of the second coaxial cable 302. A second terminal 102 of the unbalanced port 100 may be connected with an inner connector of the first coaxial cable 301 and the shielding of the second coaxial cable 302. Furthermore, the shielding of the first coaxial cable 301 and the second coaxial cable 302 may be connected with each other at the position of the balanced port 200. Furthermore, the inner connector of the first coaxial cable 301 may be connected with a first terminal 201 of the balanced port 200, and the inner connector of the second coaxial cable 302 may be connected with the second terminal 202 of the balanced port 200. A magnetic core 1 may be arranged around each of the coaxial cables 301 and 302.

(22) The above described embodiments of a balun according to FIG. 4 and FIG. 3 only show two exemplary embodiments. However, it is understood that the present invention is not limited to the above-mentioned baluns 2. Furthermore, the magnetic core 1 according to the present invention may be used for any other kind of balun for coupling an unbalanced line with a balanced line.

(23) For the sake of clarity in the following description of the method based on FIG. 6, the reference signs above in the description of the magnetic core 1 and the balun 2 based on FIGS. 1 to 5 will be maintained.

(24) FIG. 6 shows a block diagram of a method for manufacturing a magnetic core for a balun. The method comprises a step S1 of providing a number of at least two core elements 11, 12, 13, and a step S2 of providing at least one heat sink 21, 22. Further, the method comprises a step S3 of arranging the number of core elements 11, 12, 13 and the at least one heat sink 21, 22 concentrically. In particular, the at least one heat sink 21, 22 is arranged between the number of core elements 11, 12, 13.

(25) The method may further comprise a step of thermally coupling a cooler 30 with the at least one heat sink 21, 22.

(26) Summarizing, the present invention relates to a magnetic core for a balun and a balun with such a magnetic core. In particular, a magnetic core is provided comprising multiple core elements, wherein the individual core elements are concentrically arranged. Furthermore, a heat sink is arranged between two adjacent core elements. By using multiple core elements for a magnetic core, the individual core elements can be adapted to different frequency ranges. In this way, the magnetic core may be used for a balun having a broad frequency range. Furthermore, thermal energy generated in the magnetic core can be dissipated by the heat sinks between the individual core elements. In this way, the power handling capability of the magnetic core and the balun with such a magnetic core is enhanced.

(27) In the foregoing specification, the invention has been described with reference to specific examples of embodiments of the invention. It will, however, be evident that various modifications and changes may be made therein without departing from the broader spirit and scope of the invention as set forth in the appended claims. For example, the connections between various elements as shown and described with respect to the drawings may be a type of connection suitable to transfer signals from or to the respective nodes, units or devices, for example via intermediate devices. Accordingly, unless implied or stated otherwise the connections may for example be direct connections or indirect connections.

(28) In the description, any reference signs shall not be construed as limiting the claim. The word “comprising” does not exclude the presence of other elements or steps then those listed in a claim. Furthermore, the terms “a” or “an”, as used herein, are defined as one or more than one. Also, the use of introductory phrases such as “at least one” and “one or more” in the claims should not be construed to imply that the introduction of another claim element by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim element to inventions containing only one such element, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an.” The same holds true for the use of definite articles. Unless stated otherwise, terms such as “first” and “second” are used to arbitrarily distinguish between the elements such terms describe. Thus, these terms are not necessarily intended to indicate temporal or other prioritization of such elements. The mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to advantage. The order of method steps as presented in a claim does not prejudice the order in which the steps may actually be carried out, unless specifically recited in the claim.

(29) Skilled artisans will appreciate that the illustrations of chosen elements in the drawings are only used to help to improve the understanding of the functionality and the arrangements of these elements in various embodiments of the present invention. Also, common and well understood elements that are useful or necessary in a commercially feasible embodiment are generally not depicted in the drawings in order to facilitate the understanding of the technical concept of these various embodiments of the present invention. It will further be appreciated that certain procedural stages in the described methods may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required.