EP2912671A1 - Microwave cable and method for producing and using such a microwave cable - Google Patents

Abstract

A microwave cable (10), intended for a frequency range from 0 Hz up to at least a few 10 GHz, comprises a central inner conductor (11), a dielectric (12) concentrically surrounding the inner conductor, an outer conductor (13, 14) concentrically enclosing the dielectric (12), and a sheathing concentrically enclosing the microwave cable (10) externally. Stable electrical and mechanical properties, particularly when making up cables, are achieved in that the outer conductor has two electrically conducting bands (13, 14) wound over each other, in that the bands (13, 14) are each wound in an overlapping manner and in that the bands (13, 14) are wound progressively in opposite directions.

Description

 Microwave cable and method for making and using such a microwave cable

 TECHNICAL FIELD The present invention relates to the field of microwave technology. It relates to a microwave cable according to the preamble of claim 1. It further relates to a method for producing and the use of such a microwave cable.

STATE OF THE ART

From the technology of cables, a variety of solutions are known, such as such a cable, if it includes inner conductor and outer conductor, may be constructed.

In the document US 2,669,168, for example, a telephone cable is described, which in addition to a plurality of inner conductors has two mutually insulated outer conductor, which are constructed as bandings of a metal foil. The outer conductors are used for separate transmission of signals. US Pat. No. 2,447,168 discloses a high-frequency cable in which two inner conductors are enclosed by a dielectric and two bandings made of metallized paper are applied to one another on the dielectric.

From document US Pat. No. 5,214,243 a coaxial cable is known having a central inner conductor, a dielectric, a layer of wound PTFE tape applied thereon, a metal wire braid applied over it, an overlying one Braid made of polyamide fibers, and finally two bands of PTFE tape wound in overlapping fashion.

Finally, US Pat. No. 6,201,190 shows a coaxial cable in which the dielectric surrounding the inner conductor is enclosed by two film strips lying one above the other. The film strips are designed as aluminum-polyester-aluminum laminates.

Especially in M ikrowellen frequency range at frequencies of 40 G Hz and more, these solutions have the disadvantage that no prefabricated (coaxial) cable with optima len electrical parameters are feasible.

In the case of a single-wound tape, the insertion loss becomes unstable during bending or twisting as the windings of the tape shift or loosen, and a cable attached to the cable end can not be adapted to such a condition because the tape can be detached after stripping the cable end, and therefore no longer fits tightly.

Although a detachment of the winding (banding) can be largely prevented at one end of the cable when the tape is wound overlapping, because at the cable end from which the winding proceeds in the cable longitudinal direction, the tape end is fixed by the overlap. At the other end of the cable, however, such a fixation is not present, so that there slightly loosens the banding or even peels off.

The H F matching to the connector is thereby degraded, and the stability of this cable portion with the band loosened is also impaired PRESENTATION OF THE INVENTORY

It is therefore an object of the invention to provide a M ikrowellenkabel which avoids the disadvantages of known cables in a simple manner and can be assembled in particular without deterioration of the mechanical and electrical properties.

It is a further object of the invention to provide a method for producing such a cable, as well as to propose an application.

This is an economical solution to be shown how to make a populated flexible coaxial cable insensitive makes against instability of insertion loss in bending or torsion. In addition to optimum electrical parameters in the microwave range, good mechanical flexibility is a prerequisite.

These and other objects are achieved by the features of claims 1, 11 and 14.

The microwave cable according to the invention, which is provided for a frequency range from 0 Hz to at least some 10 Hz, comprises a central inner conductor, a dielectric concentrically surrounding the inner conductor, an outer conductor concentrically surrounding the dielectric, and a microwave conductor concentrically surrounding the outer microwave cable Sheathing.

It is characterized in that the outer conductor comprises two superposed, electrically conductive banding, that the bandages are each wound in an overlapping manner, and that the bandages are wound progressively in opposite directions. According to one embodiment of the microwave cable according to the invention, the bandings are wound in opposite directions of rotation.

According to another embodiment of the M ikrowellenkabels according to the invention, a concentric wire mesh is disposed between the outer conductor and the sheath.

A further embodiment of the invention is characterized in that the bandings are each constructed from a metal band.

In particular, the metal bands have the same width and the same thickness.

For applications in which many microwave cables have to be used in a confined space, such as, for example, test constructions for microprocessors or other highly integrated circuits with high clock frequencies, an embodiment of the inven tion is advantageous in which the microwave cable has an outside diameter of a few millimeters , in particular about 1, 5 mm, the metal strips each have a width of a few millimeters, in particular about 1, 5 mm, and the thickness of the metal strips each a few 1/1 00 mm, in particular about 0.035 mm.

Another embodiment of the invention is characterized dad urch that the Metallbän consist of the same material.

In particular, the metal strips are made of copper and are silvered on the surface.

According to another embodiment of the microwave cable according to the invention, the metal strips are each wound with an overlap of about 45% and with an offset per revolution of about 0.8 mm. Yet another embodiment is characterized in that the sheathing is made of FEP.

The method according to the invention for producing a microwave cable according to the invention comprises the following steps:

Providing an output arrangement of the inner conductor surrounded by the dielectric, which output arrangement extends with a predetermined length between a first cable end and a second cable end;

Applying the first banding by overlapping the output assembly with a first metal band, starting at the first cable and progressing towards the second cable end;

Applying the second banding by overlapping the initial banding provided with the initial banding with a second metal band, beginning at the second cable end and progressing to the first cable end; and

Applying the jacket to the output arrangement provided with the two bandings.

An embodiment of the method according to the invention is characterized in that the first banding is applied with a first direction of rotation and that the second banding is applied with a second direction of rotation opposite to the first direction of rotation.

Another embodiment is characterized in that before the last step, the output arrangement provided with the two bandings is enveloped by a concentric wire mesh. According to the invention, the microwave cable is used in a connection cable which has a coaxial connector at the ends, wherein its outer conductor is electrically conductively connected to the exposed outer conductor of the microwave cable.

According to one embodiment, the outer conductors of the coaxial connectors are each soldered to the outer conductor of the microwave cable.

In particular, when the M ikrowellenkabel between the outer conductor and the sheath a concentric wire mesh is arranged, the outer conductor of the coaxial connector respectively soldered to the outer conductor of the M ikrowellenkabels through the wire mesh through.

KU RZE EXPLANATION OF FIGURES

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

1 shows the cross section through a M ikrowellen cable according to an embodiment of the invention.

FIG. 2 shows a connection cable with a microwave cable according to the invention and coaxial connectors attached to the cable ends; FIG.

3A-C show various steps in the production of a microwave cable according to an embodiment of the invention; FIG. 4 shows in a section the parameters which determine banding in the microwave cable according to the invention; FIG. and

5 shows the stabilizing effect of the bandages according to the invention during assembly or cutting to length of the microwave cable at both ends.

WAY TO RUNNING THE INVENTORY

Fig. 1 shows the cross section through a microwave cable 1 0 according to an embodiment of the invention. In the center of M ikrowellenkabels 1 0 a central inner conductor 1 1 is arranged, which may for example consist of a silvered copper wire. The inner conductor 1 1 is concentrically surrounded by a dielectric 1 2, for which the usual materials in the H F-technique, for. As PTFE, come into question. The dielectric 1 2 is in the radial direction successively concentrically surrounded by a first banding 1 3 and a second banding 1 4, which will be discussed in more detail. This is followed by a concentric wire mesh 1 5, which is constructed for example of silver-plated copper wire. This concentric layer arrangement is finally surrounded on the outside by a protective U mmantelung 1 6, which preferably consists of a FEP (Fluorinated Ethylene Propylene).

The bandings 1 3, 1 4 are each composed of a metal strip 2 1, 22 (see FIG. 3). The two metal bands 2 1, 22 may be formed fundamentally different in material, thickness and width. However, they preferably have the same width B (see Fig. 4) and the same thickness. In particular, the metal bands 2 1, 22 also consist of the same material, preferably of copper, which is silvered on the surface.

For complex and compact applications, where the smallest dimensions of the cable are particularly important, the microwave cable 1 0 can have an outside diameter D (see Fig. 2) of a few millimeters, in particular about 1.5 mm. The metal strips 21, 22 for the banding 13 and 14 then preferably each have a width B of a few millimeters, in particular about 1, 5 mm. The thickness of the metal strips 21, 22 is then each a few 1/100 mm, in particular about 0.035 mm.

In such a (miniaturized) microwave cable, the metal strips 21, 22 in the banding 13 and 14 according to Figure 4 each with an overlap of about 45% (overlap area 23) and with one offset per revolution (step size w) of about 0, 8 mm wound.

According to the invention, the decisive difference lies in the fact that the overlapping wound stripings 13 and 14 are wound progressively in opposite directions with respect to the cable, as clearly shown in FIG.

In the method steps illustrated in FIGS. 3A-C, an output arrangement is first provided from the inner conductor 11 surrounded by the dielectric 12 (FIG. 3A), which may have a predetermined length L, which can be, for example, several kilometers, between a first cable end 19 and a second cable end 20 extends;

According to FIG. 3B, the lower first banding 13 is applied to this output arrangement 11, 12 by overlapping the output arrangement 11, 12 with a first metal band 21, beginning at the first cable end 19 and progressively (see directional arrow) to the second cable end 20. The sense of rotation when wrapping is in the illustrated example in the direction of arrow counterclockwise. If the first banding 13 is completely applied, according to FIG. 3C, the second bandage 14 is applied by overlapping the initial bandage 13, which is provided with the first bandage 13, with a second metal band 21, beginning at the second cable end 20 and advancing (FIG. see direction arrow) to the first cable end 19. The direction of rotation when wrapping is seen in the example shown in the arrow direction in clockwise direction.

Subsequently, the microwave cable 10 can be completed by applying further layers (wire mesh 15, sheath 16).

In principle, it is conceivable to choose the direction of rotation when applying the two bandings. However, the stability of the cable is even greater when the second band 14 is applied with a direction of rotation of the first banding 13 opposite direction of rotation.

The metal bands 21, 22 are preferably made of the same material (silvered Cu film), have the same width B and have the same thickness. With an outer diameter D of the microwave cable of a few millimeters, in particular approximately 1.5 mm, the metal strips 21, 22 preferably each have a width B of a few millimeters, in particular approximately 1.5 mm. Their thickness is preferably in each case a few 1/100 mm, in particular about 0.035 mm.

It has been proven in practice to wrap the metal strips 21, 22 each with an overlap of about 45% and with an offset per revolution of about 0.8 mm.

The effect of double and reverse banding during assembly can be seen in the illustration in Figures 5 and 6: If the microwave cable at a cable end 20a cut to length (Fig. 5) and for attaching a coaxial connector (eg 1 8 in FIG. 2) is prepared by shortening the U mmantelung 1 6 and the wire mesh 1 5 exposed the second, outer banding 1 4 on a stretch. By (in Fig. 5 to the left progressing) overlapping winding of the banding 1 4 is effectively prevented, however, that the metal strip of the banding 1 4 unwind or peel off by itself. As a result, however, at the same time the underlying first banding 1 3 is fixed and prevents their detachment.

If the microwave cable is cut to length on the other end of the cable 1 9a (FIG. 6) and prepared for the attachment of a coaxial connector (eg 1 7 in FIG. 2), again the sheath 1 6 and the wire mesh 1 5 are shortened the second, outer banding 1 4 exposed on a stretch. In this case, although the metal strip of the second banding unwind, because a fixation by the overlap at this end is not given. However, this does not apply to the underlying first banding 1 3: Here occurs due to the opposite direction of winding, the same fixing effect by the overlap, as in the banding 1 4 at the other cable end 20 a. Since the electrical properties of the cable are determined essentially by the inner first banding 1 3, the detachment of the banding 1 4 at the cable end 1 9a is not critical.

On the whole, the microwave cable 10 can be assembled or cut to length at both ends on the basis of the specially wound bandings 1 3 and 1 4 and provided with a connector, without unintentional deterioration of the internal banding 1 3 determining the electrical properties Properties occurs.

Overall, the peculiarities and advantages of the invention can be summarized as follows: The cable outer conductor consists of two overlapping metal bands, which are not only wound in opposite directions, but are also reversed in the winding direction compared to the prior art. The winding of the second banding begins at the cable end of the first band (wound forward / backward).

This construction offers insensitivity of insertion loss when bending, as well as good protection against high frequency radiation. In addition, the prerequisite for optimum high-frequency matching between cable and connector is created: the difference in diameter between the cable entry of the connector and the outer conductor of the cable (= double band) can be reduced to a minimum. This allows for good insertion and centering of the cable to the connector. This reduces H F reflections (return loss) because impedance deviations are thus minimized.

The oppositely wound banding (double band) with opposite winding direction bring advantages in the assembly: at both ends of the cable is always a winding self-fixing due to Ü overlapping. In the same winding direction or single band, however, only one end of the cable would be self-fixing. Without this self-fixing, the tape is cut when the cable is cut to length, so the diameter becomes larger. A connector assembly is then possible only under the condition that the cable entry of the connector has a sufficiently large diameter. However, then the centering of the cable in the connector over the tape is no longer given, which can lead to impedance deviations and thus H F reflections. In addition, the larger inner diameter of the absorbed banding is also an electrical H F impurity (impedance deviation), resulting in H F reflections. The relaxed band may also cause insertion loss instabilities. • The double belt also provides much more (mechanical) stability than a polymer skin over the belt.

• The double band of metal has over a fixation by means of insulating

Band (eg Kapton ^® ) in the connector assembly the advantage of much simpler packaging (soldering). Both metal bands are soldered together. On the other hand, a Kapton ^® tape or polymer skin would first have to be stripped off in a separate process (by hand or by laser) so that the underlying metal strip can be soldered.

• The microwave cable can be used for B. in cable assemblies used for test & measurement, especially in the context of multiple coaxial connectors, as described in WO 2009/1 1 1 895 A 1.

Overall, the invention results in an H F coaxial cable with high requirements for stability of the insertion loss, optimum H F adaptation to the connector, economical assembly and very good shielding attenuation.

LIST OF REFERENCE NUMBERS

 10 microwave cables

11 inner conductor

 12 dielectric

 13.14 Banding

 15 wire mesh

16 sheathing

17,18 coaxial connector

19,20 cable end

 19a, 20a cable end

 21.22 metal band

 23 overlap area

24 connection cable

B width

 D outer diameter

L length

w increment

Claims

claims A microwave cable (10) for a frequency range from 0 Hz to at least a few 10 GHz, comprising a central inner conductor (11), a dielectric (12) concentrically surrounding the inner conductor, an outer conductor (13, 14) concentrically surrounding the dielectric (12) ), and a jacket (16) surrounding the microwave cable (10) concentrically outside, characterized in that the outer conductor comprises two electrically conductive bandings (13, 14) wound one above the other, such that the bandings (13, 14) are each wound in an overlapping manner, and that the bandings (13, 14) are progressively wound in opposite directions. 2. microwave cable according to claim 1, characterized in that the bandings (13, 14) are wound in opposite directions of rotation. 3. microwave cable according to claim 1, characterized in that between the outer conductor (13, 14) and the sheath (16) a concentric wire mesh (15) is arranged. 4. microwave cable according to any one of claims 1-3, characterized in that the bandings (13, 14) each composed of a metal strip (21, 22) are constructed. 5. microwave cable according to claim 4, characterized in that the metal strips (21, 22) have the same width (B) and the same thickness. 6. microwave cable according to claim 5, characterized in that the microwave cable (10) has an outer diameter (D) of a few millimeters, in particular 1, 5 mm, that the metal strips (21, 22) each have a width (B) of a few millimeters, in particular about 1, 5 mm, and that the thickness of the metal strips (21, 22) each some 1 / 100 mm, in particular about 0.035 mm. Microwave cable according to claim 4, characterized in that the metal strips (21, 22) consist of the same material. Microwave cable according to claim 7, characterized in that the metal strips (21, 22) consist of copper and are surface silvered. Microwave cable according to claim 6, characterized in that the metal strips (21, 22) are each wound with an overlap of about 45% and with an offset per revolution of about 0.8 mm. Microwave cable according to claim 1, characterized in that the Ummante- ment (16) consists of FEP. A method for producing a microwave cable (10) according to claim 1, comprising the following steps: a) providing an output arrangement (11, 12) from the inner conductor (11) surrounded by the dielectric (12), which output arrangement (11, 12) adjoins with one predetermined length (L) between a first cable end (19) and a second cable end (20) extends; b) applying the first banding (13) by overlapping the output assembly (11, 12) with a first metal band (21), starting at the first cable end (19) and progressing towards the second cable end (20); c) applying the second banding (14) by overlapping the initial banding (13) provided with the first banding (11, 12) with a second metal band (21) starting at the second cable end (20) and progressing towards the first cable end (19) ; and d) applying the sheathing (16) to the output arrangement (11, 12) provided with the two bandings (13, 14). A method according to claim 11, characterized in that the first banding (13) is applied with a first direction of rotation, and that the second banding (14) is applied with a second direction of rotation opposite to the first direction of rotation. 13. The method according to claim 11 or 12, characterized in that before the last step (d) with the two bandings (13, 14) provided with the output arrangement (11, 12) is coated with a concentric wire mesh (15). 14. Application of the microwave cable (10) according to claim 1 with a connecting cable (24), which at the ends in each case a coaxial connector (17, 18), characterized in that the outer conductor with the exposed outer conductor (13, 14) of the Microwave cable (10) is electrically connected. Application according to Claim 14, characterized in that the outer conductors of the coaxial connectors (17, 18) are each soldered to the outer conductor (13, 14) of the microwave cable (10). 16. Application according to claim 15, characterized in that the microwave cable (10) between the outer conductor (13, 14) and the sheath (16) a concentric wire mesh (15) is arranged, and that the outer conductor of Coaxial connector (17, 18) in each case with the outer conductor (13, 14) of the microwave cable (10) through the wire mesh (15) are soldered through.