EP2062333B1 - Coaxial connecting element for the microwave range - Google Patents

Abstract

A coaxial connecting element (10) for the microwave range comprises a preferably bar-shaped inner conductor (13), which extends along an axis (24) and is held concentrically in an outer conductor (11, 12, 14) by means of at least one dielectric supporting element (15), wherein the outer conductor (11, 12, 14) has a plurality of radial slots extending in the axial direction distributed around the circumference in the region of the at least one supporting element (15). With such a connecting element, increased stability and precision as well as simplified production and fitting are achieved by virtue of the fact that the supporting element (15) is designed to be integral.

Description

TECHNICAL AREA

The present invention relates to the field of microwave technology. It relates to a coaxial connecting element for the microwave range according to the preamble of claim 1 and a method for producing such a connecting element.

STATE OF THE ART

Coaxial components or connectors for the microwave range (from a few GHz up to 250 GHz) usually comprise an outer conductor extending along an axis, in which an inner conductor is concentrically arranged and held. For holding the inner conductor in the outer conductor one or more dielectric support element (s) are used. Training and the installation of the support elements affect both the electrical and the mechanical properties of the coaxial connection element. On the one hand, the supporting elements should have as little influence as possible on the wave propagation in the connecting element in relation to the air line which is the reference. On the other hand, the mechanical support must be designed so permanently and precisely that many connection cycles can be run through with consistent accuracy.

A connecting element of the type mentioned is known from US 4,456,324 known. Further examples of supporting elements may be, for example, the publications US-A-4,718,864 . US-A-4,867,703 . US-A-4,981,445 or US-A-5,269,702 be removed. Also known is the technology of hermetically sealed glass bushings, in which an inner conductor is held in a concentric metal ring by means of glass, which fills the annular space between the metal ring and inner conductor and is introduced by a melting process.

Another problem caused by the support elements is the excitation of higher transverse modes (in particular TE ₁₁ ) in the area of the support elements, which leads to a distortion of the transmitted signals and limits the area of application of the connection element to lower frequencies.

In the article of R. Fuks, "New Dielectric Bead for Millimeter-wave Coaxial Components", Microwave Journal no. 5, p.318 ff (2001 ) this problem is explained and proposed to solve a new type of support elements which are completely symmetrical in the radial plane and having inclined surfaces with respect to the axis. However, the support elements are manufactured as separate components and then installed, which is at the expense of the precision of the arrangement.

Another type of holder of the inner conductor in the outer conductor is in the document US-A-4,456,324 been proposed. In this known solution, the inner conductor is centered by four curved dielectric plates and which are held in a slotted hollow cylinder of the outer conductor and form the configuration of a Maltese cross, through the center of which leads the inner conductor. This type of holder has the advantage that only very little dielectric material has to be used for the support. Of considerable disadvantage, however, is the complicated and complex assembly of the arrangement, which leads in particular to coaxial arrangements with diameters in the millimeter range to considerable difficulties. In addition, it is difficult to achieve the desired accuracy by the assembly of many items. The slots in the outer conductor serve to receive the dielectric plates. An additional function will not be granted to them.

PRESENTATION OF THE INVENTION

It is an object of the invention to provide a coaxial connecting element for the microwave range, which avoids the disadvantages of known solutions, and is characterized at the same time high precision and mechanical stability by a simplified installation and excellent electrical properties, and to provide a method for producing such a connecting element ,

The object is solved by the entirety of the features of claims 1 and 16. The essence of the invention is to form the support element in one piece and in particular to directly mold or inject to the outer conductor. As a result, with high precision, a high mechanical stability is achieved at the same time simplified production and assembly, without having to make compromises with respect to the electrical properties.

According to a preferred embodiment of the invention, the support element is integrally formed on the outer conductor, in particular molded, wherein preferably the support element is non-detachably connected to the outer conductor.

Another embodiment is characterized in that the outer conductor comprises a housing in which a substantially hollow cylindrical insert is concentrically arranged and held, that the support element is integrally formed on the insert, and that the slots are arranged in the insert, wherein in particular the support element for Fixation of the support element on the insert in the circumferential direction fills the slots in use.

A further embodiment is characterized in that the insert has an annular groove on the outside, and that the support element for fixing the support element on the insert in the axial direction fills the annular groove.

Preferably, the housing of the outer conductor comprises two in the axial direction successively arranged, screwed together housing parts which receive the insert with the molded support member and fix it in the axial direction, wherein in both housing parts in each case an axial through hole is provided, through which extends the inner conductor, and that both through holes have a shoulder on which the insert is supported in the axial direction with the molded-on support element.

In particular, the insert has a third through-hole, and the inner diameter of the three through-holes are the same.

According to another embodiment of the invention, the support element is arranged seen in the axial direction in the central region of the connecting element.

According to the invention, provision is made for the support element to comprise two hollow cylinders arranged concentrically with one another, preferably by radial webs, the inner hollow cylinder receiving the inner conductor and the outer hollow cylinder being connected to the insert, and the preferably radial webs being formed by walls of blind holes , which alternate in the axial direction of both

Extend sides between the two hollow cylinders into the support element. In particular, the blind holes are tapered toward the bottom, wherein the inner conductor in the region of the support member has a portion which receives the inner hollow cylinder of the support member in the axial direction and / or securing against rotation about the axis. This section may be knurled or have a groove (round or triangular or polygonal) or other shape suitable for retention.

According to a further embodiment, two or more slots (26) are provided uniformly distributed over the circumference of the outer conductor of the insert.

Preferably, the support element (15) consists of a liquid-crystalline polymer (LCP) or a thermoplastic PTFE.

BRIEF EXPLANATION OF THE FIGURES

Fig. 1

einen Längsschnitt durch ein koaxiales Verbindungselement gemäss einem bevorzugten Ausführungsbeispiel der Erfindung;

Fig. 2

die perspektivische Seitenansicht des Verbindungselements aus Fig. 1;

Fig. 3

den Querschnitt durch das Verbindungselement aus Fig. 1 in der dort gezeigten Ebene III-III;

Fig. 4

eine perspektivische Seitenansicht des Einsatzes mit angespritztem Stützelement und Innenleiter aus Fig. 1;

Fig. 5

in einer Explosionsdarstellung die einzelnen Elemente der Konfiguration aus Fig. 4;

Fig. 6

in perspektivischer Darstellung einen Längsschnitt durch das Stützelement aus Fig. 5; und

Fig. 7

in einer zu Fig. 5 vergleichbaren Darstellung die einzelnen Elemente aus einer entgegengesetzten Blickrichtung.

The invention will be explained in more detail with reference to embodiments in conjunction with the drawings. Show it

Fig. 1

a longitudinal section through a coaxial connecting element according to a preferred embodiment of the invention;

Fig. 2

the perspective side view of the connecting element Fig. 1 ;

Fig. 3

the cross section through the connecting element Fig. 1 in the level III-III shown there;

Fig. 4

a perspective side view of the insert with molded support member and inner conductor Fig. 1 ;

Fig. 5

in an exploded view of the individual elements of the configuration Fig. 4 ;

Fig. 6

in a perspective view of a longitudinal section through the support element Fig. 5 ; and

Fig. 7

in one too Fig. 5 comparable representation of the individual elements from an opposite direction.

WAYS FOR CARRYING OUT THE INVENTION

Fig. 1 shows a longitudinal section through a coaxial connecting element according to a preferred embodiment of the invention. The coaxial connecting element 10, which may be, for example, a cable connector, comprises a housing consisting of two cylindrical metallic housing parts 11, 12 which extends along an axis 24 and forms the outer conductor of the connecting element 10 together with a cylindrical insert 14 housed in the housing. The two housing parts 11, 12 are screwed together by means of a screw thread 21. The two housing parts 11, 12 and the metallic insert 14 each have a central through hole 16, 17 and 17 'of the same inner diameter, which in the assembled state of the connecting element 10 to a through the entire connecting element 10 reaching through through hole 16, 17, 17' complete. But it is also conceivable that these through holes 16, 17, 17 'have different diameters and so an adjustment between connector series is achieved. The insert 14, which is a dielectric support member 15 is formed for supporting a concentric inner conductor 13 is held between two paragraphs 18 and 19 in the through holes 16 and 17 of the two housing parts 11, 12. The mounted in the support member 15 inner conductor 13 extends at a sufficient distance from the wall through the through hole 16, 17, 17 '. It is for example designed as a metallic pin which ends at one end in a slotted socket 22, and at the other end in a plug pin 23. Other configurations of the inner conductor 13 are also conceivable within the scope of the invention. The same applies to the configuration of the housing 11, 12. At the left end is in in Fig. 1 embodiment shown a rotatable relative to the housing 11, 12 union nut 20 is provided, which allows a releasable connection of the connecting element with a correspondingly shaped connector. The outside view of the connecting element 10 Fig. 1 is in Fig. 2 reproduced, a cross section in the plane III-III, which goes through the support member 15, in Fig. 3 ,

The connecting element 10 is intended for use at frequencies in the two- to three-digit GHz range. Special importance is therefore on the one hand to the precision and mechanical stability, with which the inner conductor 13, which has an outer diameter <1 mm, in the outer conductor 11, 12, 14 is mounted. On the other hand, the excitation of unwanted modes, in particular the TE11 mode, must be suppressed as far as possible in the region of the support element 15 in order to achieve optimum transmission properties for the connection element. Finally, the manufacture and assembly should be so simple that even larger quantities can be provided with high quality and at a reasonable cost.

This is achieved by molding or injecting the support element 15 on the in Fig. 5 and 7 separately shown insert, and the arrangement of preferably extending in the axial direction, in particular radial slots 26 on the circumference of the insert 14 in the region of the support element 15. In the example of Fig. 1-7 four slits 26 are provided offset by 90 °. But there are only two slots offset by 180 °, three or more than four slots conceivable. The slits 26 can also serve as channels for forwarding the injected material during injection of the support member 15 and can be filled with the material of the support member 15 during injection molding (see, eg Fig. 4 .). The slots 26 interrupted the present in TE11 mode ring currents on the outer conductor and thus prevent the excitation of this mode.

For injecting the support member 15 of the insert 14 is inserted into a corresponding injection mold, the support member 15 in the Fig. 6 illustrated form there. The inner conductor 13 can be included in the Anspritzprozess. However, it is also conceivable to mount the inner conductor 13 later in the support element 15. The cylindrical support member 15 comprises in concentric arrangement an inner hollow cylinder 30 with a through hole 31 and an outer hollow cylinder 29. The inner hollow cylinder 30 tightly surrounds the inner conductor 13 in the region of a special embodiment, for example in the form of an annular groove 25 with reduced outer diameter. The outer hollow cylinder 29 abuts the inner wall of the through hole 17 'of the insert 14. The two hollow cylinders 29 and 30 are interconnected by preferably radial webs 34. The preferably radial webs 34 are formed by walls of blind holes 32, 33, which extend into the support element 15 alternately in a preferably axial direction from both sides between the two hollow cylinders 29, 30. For better releasability after injection, the blind holes 32, 33 are preferably tapered towards the bottom. In the illustrated example, each blind offset by 120 ° offset from each side are provided by 3, but there are also other numbers and arrangements of blind holes conceivable. In particular, it is also conceivable to carry out all blind holes starting from one side. Likewise, helical blind holes with corresponding helical ridges are conceivable.

The insert 14 has an annular bead 37 in the region of the slots 26, which is cut through by the slots 26. Behind the annular bead 37, an annular groove 27 is provided with a reduced diameter. The injection mold is designed so that the molded support member 15 in front of the annular bead 37 has a first ring 28, and the annular groove 27 is filled by a second ring 36. Both rings 28, 36 are connected by webs 35, which arise by filling the slots 26, with each other and with the outer hollow cylinder 29 fixed. The two rings 28, 36 with the intermediate annular bead 37 fix the support member in the axial direction, the webs 35 fix the support member 15 in the circumferential direction.

After the injection of the support member 15, the insert 14 is inserted together with the molded support member 15 and the inner conductor 13 held therein to paragraph 19 in the one housing part 12 and the assembly then screwed to the other housing part 11.

The support element 15 preferably consists of a liquid-crystalline polymer (liquid crystal polymer LCP) which has a relative dielectric constant ε _r of about 3. Likewise, however, it is also possible to use thermoplastically processable PTFE or another material. The support member 15 has an axial length in the range of about 2-3 mm at a more than 7 times greater overall length of the connecting element 10th

Overall, with the invention results in a coaxial connecting element, which is suitable for frequencies up to 65 GHz and is characterized by good electrical or transmission properties with ease of manufacture and great mechanical stability. It goes without saying that numerous modifications are possible within the scope of the invention and starting from the exemplary embodiment explained here. In particular, by adjusting the dimensions, the frequency range can be extended up to 250 GHz and more.

LIST OF REFERENCE NUMBERS

10

coaxial connecting element

11.12

Housing part (outer conductor)

13

inner conductor

14

commitment

15

support element

16,17,17 '

Through Hole

18.19

paragraph

20

Nut

21

screw thread

22

Bush (slotted)

23

pin

24

axis

25

ring groove

26

slot

27

ring groove

28

ring

29.30

hollow cylinder

31

Through opening

32.33

blind

34

Wall (bridge)

35

web

36

ring

37

torus

Claims (17)

1. Coaxial connecting element (10) for the microwave band having an inner and preferably rod-shaped conductor (13) which extends along an axis (24) and is held concentrically in an outer conductor (11, 12, 14) by means of at least one dielectric supporting element (15), with the outer conductor (11, 12, 14) having a plurality of slots (26) distributed around the circumference in the area of the at least one supporting element (15), characterized in that the supporting element (15) is formed integrally, that the supporting element (15) has two hollow cylinders (29, 30) which are arranged concentrically in one another and are connected to one another by radial webs (34), with the inner hollow cylinder (30) holding the inner conductor (13) and with the outer hollow cylinder (29) being connected to the insert (14), and in that the preferably radial webs (34) are formed by walls of blind holes (32, 33) which extend into the supporting element (15) between the two hollow cylinders (29, 30) in the axial direction and alternately from both sides.
2. Connecting element according to Claim 1, characterized in that the supporting element (15) is formed integrally, in particular moulded, on the outer conductor (11, 12, 14).
3. Connecting element according to Claim 2, characterized in that the supporting element (15) is non-detachably connected to the outer conductor (11, 12, 14).
4. Connecting element according to Claim 2 or 3, characterized in that the outer conductor (11, 12, 14) has a housing (11, 12) in which an essentially hollow-cylindrical insert (14) is arranged and held concentrically, in that the supporting element (15) is formed integrally on the insert (14) and in that the slots (26) are arranged in the insert (14).
5. Connecting element according to Claim 4, characterized in that the supporting element (15) fills the slots (26) in the insert (14) in the circumferential direction, in order to fix the supporting element (15) on the insert (14).
6. Connecting element according to Claim 4 or 5, characterized in that the insert (14) has an annular groove (17) on the outside, and in that the supporting element (15) fills the annular groove (27) in the axial direction, in order to fix the supporting element (15) on the insert (14).
7. Connecting element according to one of Claims 4 to 6, characterized in that the housing (11, 12) of the outer conductor (11, 12, 14) has two housing parts (11, 12) which are arranged one behind the other in the axial direction, can be screwed to one another, hold the insert (14) with the integrally formed supporting element (15) and fix it in the axial direction.
8. Connecting element according to Claim 7, characterized in that an axial through-hole (16, 17) is provided respectively in the two housing parts (11, 12), through which the inner conductor (13) runs, and in that both through-holes (16, 17) have a step (18, 19) on which the insert (14) together with the integrally formed supporting element (15) is supported in the axial direction.
9. Connecting element according to Claim 8, characterized in that the insert (14) has a third through-hole (17'), and in that the internal diameters of the three through-holes (16, 17, 17') are the same.
10. Connecting element according to one of Claims 1 to 9, characterized in that the supporting element (15) is arranged in the centre area of the connecting element (10) seen in the axial direction.
11. Connecting element according to Claim 1, characterized in that the blind holes (32, 33) taper towards the base.
12. Connecting element according to Claim 1, characterized in that, in the area of the supporting element (15), the inner conductor (13) has a section which holds the inner hollow cylinder (30) of the supporting element (15) fixing it in the axial direction and/or securing it against rotation about the axis (24).
13. Connecting element according to one of Claims 1 to 12, characterized in that two or more slots (26) are provided, distributed uniformly over the circumference of the insert (14).
14. Connecting element according to one of Claims 1 to 13, characterized in that the supporting element (15) is composed of a liquid-crystal polymer (LCP).
15. Connecting element according to one of Claims 1 to 13, characterized in that the supporting element (15) is composed of a thermoplastic PTFE.
16. Connecting element according to one of Claims 1 to 15, characterized in that the supporting element (15) is moulded onto the outer conductor (11, 12, 14) using an injection-moulding method, wherein the supporting element (15) fills the slots (26).
17. Connecting element to Claim 16, characterized in that the outer conductor (11, 12, 14) has a housing (11, 12) in which an essentially hollow cylindrical insert (14) is arranged and held concentrically, in that the supporting element (15) is moulded onto the insert (14) and in that the insert, together with the moulded-on supporting element (15), is installed in the housing (11, 12).

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