The invention relates to an HF coaxial cable that comprises a cable inner conductor and a cable outer conductor, as well as an angular plug connection at at least one of its two cable ends.
HF angular plug connections of the above type allow a substantially loss-free HF signal redirection, preferably by 90°, and are typically used for purposes of HF signal coupling into or HF signal coupling out of HF device components. Particularly advantageous is the only small overall height of such angular plug connections, which enables a reliable HF signal connection for the first time, principally in narrow installation spaces, as are often prevalent on the rear walls of devices.
An HF coaxial angular plug connector of the generic type is described in the published document DE 198 54 503 C1, which provides a plug connector inner conductor, which is centered by means of an insulating support of dielectric material within a metal housing, which at the same time constitutes the plug connector outer conductor. A receptacle opening for an HF coaxial cable assembled at the front is provided at right angles to a housing axis that can be allocated to the metallic housing. For the purpose of securely joining the cable inner and outer conductors to the corresponding inner and outer conductor regions provided on the housing side, an access opening that can be closed at the side on the metallic housing is provided, through which soldered connections between the respective inner and outer conductors have to be undertaken, but which are viewed as complicated installation steps and thus contribute a considerable portion of the production costs.
An angular plug connection for high-frequency coaxial cables is known from DE 38 36 141 A1, which can be realized with lower production costs owing to the simpler construction thereof. The known angular plug connection to this end provides a flexible HF coaxial cable. The cable outer conductor is a wire mesh and the assembled cable end thereof is connected to a specially shaped straight plug connector. The plug connector has a contact sleeve surrounding the cable outer conductor, which has a sleeve opening, which makes it possible to bend the sleeve region including the inner coaxial cable through 90°. The bending of the sleeve regions ensures that the cable inner conductor retains its insulation in the region of the angling. The radius of curvature of cable inner conductor and cable outer conductor is dimensioned such that the wave impedance of the coaxial cable remains constant, particularly in the region of the kink. For the purposes of plug stabilization, protection and also improved handling, the ready-installed plug is encapsulated with a corresponding plastic coating.
The coaxial cable described in the published document DE 103 50 763 A1 provides a similarly simple construction with an angular plug connection, in which the redirection through 90° for the HF signal line is realized by bending a flexible coaxial cable. In this case, the assembled coaxial cable end is connected to a straight plug connector, which is known per se. The HF coaxial cable set thereof, which protrudes directly out of the plug connector, has a 90° bend. A moulded part of a thermoplastic is used for maintaining the shape thereof. The flexible HF coaxial cable has an outer conductor formed from a metal mesh.
The published document DE 18 01 189 A discloses a right-angled coaxial-cable connector, with reduced electrical losses. Reference is expressly made to the fact that electrical losses increase in the case of deformations of a coaxial cable with radii that are too narrow. It is suggested to bend the coaxial cable in a gentle arc. A slot-shaped recess additionally is introduced in a plug housing part. Through the recess the cable is formed in the forming region into a gentle arc to the greatest extent possible.
The published document FR 2 503 942 A1 is concerned with the production of a bent semi-rigid cable, avoiding mechanical and electrical discontinuities in the outer conductor, which can occur in the form of microtears due to the deformation process, to the greatest extent possible. It is suggested to electrolytically coat the outer conductor after the bending of the semi-rigid cable, e.g. with a layer thickness of 2.2 mm, in order to improve the electrical properties.
Finally, the published document DE 30 48 781 A1 discloses a flexible coaxial cable with an outer-conductor mesh constructed as an outer conductor. It is suggested to remove the outer layer of the coaxial cable in the bending region, so that the outer conductor mesh is exposed. Subsequently, the coaxial cable is bent and the bend is fixed by a setting material. Solders or resin-based adhesives are preferred as setting material.
The invention is based on developing a HF coaxial cable, particularly in the form of a corrugated sheath cable, with a cable inner conductor and cable outer conductor and also an angular plug connection at at least one of the two cable ends thereof in such a manner that the production outlay should be reduced considerably, whereby the high-frequency signal transmission properties are improved significantly, particularly at high frequencies, for example greater than 4 GHz. It is necessary that the sizes, that is to say particularly the overall heights of hitherto-known angular plug connectors are not exceeded, but rather are reduced. It should be possible to implement all of the measures to be met for this using, in terms of process engineering, simple means, particularly of assembling factories. Also, the diversity of parts required to be stocked for producing the angular plug connection, the logistics and storage outlay should be reduced considerably.
The solution of the object on which the invention is based is specified in Claim 1. The subject matter of Claim 8 is a method for producing an angular plug connection. Features which advantageously form the idea according to the solution are the subject of the subclaims and also to be drawn from the further description, particularly with reference to the illustrated exemplary embodiments.
A HF coaxial cable constructed according to the solution having the features of the preamble of Claim 1 is characterised by a conventional corrugated sheath cable, which is known per se, having a cable outer conductor constructed as a metal corrugated tube and a cable inner conductor, to which a line impedance Zk and also a minimum bending radius rk,min, which is for the most part determined by the cable manufacturer, are allocated. A straight plug connector is attached at at least one cable end. For connection to the plug connector, the at least one cable end of the corrugated sheath cable is assembled, that is to say the cable inner conductor exposed at the end is joined with an inner conductor of the straight plug connector and the cable outer conductor is joined with an outer conductor of the straight plug connector. Directly or indirectly following the straight plug connector, the corrugated sheath cable has a bend that has a bending radius rα, which is significantly smaller than the minimum bending radius rk,min predetermined by the cable manufacturer. In accordance with the invention, significantly smaller means a bending radius rα, for which the following applies: 0.2 rk,min≦rα≦0.9 rk,min, preferably 0.3 rk,min≦rα≦0.7 rk,min, particularly preferably 0.4 rk,min≦rα≦0.6 rk,min.
In addition, the bent corrugated sheath cable dimensioned according to the invention has a line impedance Zα, for which the following applies:
|Zα−Zk|≦1 Ω
That is in spite of bending the corrugated sheath cable with a significantly smaller bending radius than that which is predetermined as the minimum bending radius by the manufacturer, the HF coaxial cable with angular plug connection according to the invention has HF transmission qualities, which correspond or at least substantially correspond to those of an undeformed corrugated sheath cable. The HF coaxial cable according to the invention is therefore characterized in particular by a bend with the bending radius rα, which is produced by cold forming the corrugated sheath cable with the introduction of a bending force transversely to the corrugated sheath cable and also a tensile force along the corrugated sheath cable. By means of the mutually adjusted introduction of force with reference to the bending and tensile forces, it is ensured that the corrugated sheath cable geometry, which is characteristic for a loss-free HF signal propagation along the corrugated sheath cable, is not or at least is not appreciably changed by the bending. The corrugated sheath geometry characteristic for the HF signal propagation is in particular understood to mean an electrically effective diameter of the corrugated sheath cable, which corresponds to half the sum of one maximum and minimum diameter in each case that can be allocated to the cable outer conductors, which are constructed in a corrugated manner. For an unhindered HF signal propagation along the corrugated sheath cable section bent according to the invention, the electrical diameter of the corrugated sheath cable deviates in the region of the bending radius rα by less than 10% from the electrical diameter in the remaining, that is a non-bent or -shaped corrugated sheath cable region.
Due to the bending of the corrugated sheath cable according to the invention with the required bending radii far below the minimum bending radii specified by the manufacturer, although the concept according to the invention uses the known HF coaxial cable angular plug connections, in which the HF signal propagation direction at 90° is realized by bending a correspondingly flexibly configured coaxial cable. The concept according to the invention goes beyond in a targeted manner the technically acceptable use limits imposed by the manufacturer in the case of corrugated sheath cables with respect to not undershooting a predetermined minimum bending radii. The significant undershooting of the bending radius initially creates the prerequisite of creating compact overall heights for the construction of an angular plug connection based on a corrugated sheath cable, which has overall heights comparable with the overall heights of conventional angular plug connections. However, due to the use of corrugated sheath cables bent according to the invention, in contrast with conventional coaxial cables with angular plug connections, in addition to a simpler installation or production of the angular connection, explained hereinafter, significantly better signal transmission qualities result, particularly in the case of frequencies of greater than 4 GHz.
The HF coaxial cable with an angular plug connection according to the invention can fundamentally be realized with corrugated sheath cables of all standardized diameter classes from ⅛″ to ⅝″. Thus, for corrugated sheath cables with a nominal diameter of ⅛″, a minimum bending radii rα of 4 mm to 10 mm can be realized according to the invention with the minimum bending radius rk,min specified by the manufacturer typically being specified as 18 mm. In the case of ¼″ corrugated sheath cables, minimum bending radii rα of 5 mm to 15 mm can be realized with rk,min typically being 25 mm. For corrugated sheath cables with a nominal diameter of ⅜″, a minimum bending radii rα of 7 mm to 20 mm can be realized, for which a minimum bending radius rk,min of 25 mm being specified by the manufacturer. Finally, for ½″ corrugated sheath cables, a minimum bending radii rα between 9 and 25 mm can be realized with rk,min at 32 mm being specified by the manufacturer. All commercially available corrugated sheath cables are fundamentally suitable for realizing a HF coaxial cable with angular plug connector according to the invention which relates to standardized corrugated sheath cables, particularly also super-flexible corrugated sheath cables, which have a spiral-corrugated outer conductor contour, that is with a pitch.
To produce the HF coaxial cable with angular plug connection according to the invention, at least one cable end needs to be assembled initially and the cable outer conductor and also the cable dielectric are trimmed with respect to the cable inner conductor. If present, the cable sheath protecting the HF corrugated sheath cable is likewise trimmed in certain areas.
In a next step, a straight plug connector is securely connected to the previously explained prepared cable end by joining the cable inner conductor to the inner conductor of the straight plug connector and the cable outer conductor to an outer conductor of the straight plug connector, preferably by soldering, crimping or similar joining methods. Of course, releasably secure joining techniques can also be used. For example, the cable inner conductor can be connected to a plug-side inner conductor structure by laminating or spring-loaded contacting. The installation outlay required for this is far lower compared to angular plug connectors composed of a plurality of components, as are known from the published document DE 198 54 503 C1 discussed above.
Subsequently, it is necessary to bend the corrugated sheath cable emanating from the plug connector in a straight line in one region which preferably directly follows the plug connector. The bending process takes place by means of cold forming under the action of a bending force directed transversely to the longitudinal extension of the HF corrugated sheath cable and a tensile force orientated longitudinally to the HF corrugated sheath cable, in such a manner that the corrugated sheath cable experiences a permanent bend with a bending radius rα, where rα≦rk,min, directly or indirectly following the straight plug connector. This bending alters the line impedance Zk of the straight-running, undeformed corrugated sheath cable by a maximum of 1 ohm, as a result of which the return loss ar of the conventional corrugated sheath cable can be changed as a function of the frequency by up to 2% due to the bend of the bending radius rα.
The tensile force additionally acting along the corrugated sheath cable as a function of the bending force acting on the corrugated sheath cable is chosen under the proviso of stretching the corrugation contour of the cable outer conductor facing radially inwards to the bending radius on the one hand, so that a direct mutual bearing of adjacent corrugated structure side faces is counteracted. But on the other hand, the formation of tears, owing to overextension or overstretching, on the outer conductor surface radially outwardly facing the bend is eliminated.
Optionally, the cold formed bending region of the corrugated sheath cable is provided with an envelope, which exerts both a protection and support function for the bent region of the HF corrugated sheath cable. The bent cable region with the plug connector connected thereto is advantageously inserted into a correspondingly prefabricated casting mould and in the context of a subsequent moulding process, provided with a corresponding envelope using a suitably chosen thermoplastic material. Depending on the functional demand, the bent corrugated sheath cable region can alternatively be protectively surrounded with a hot adhesive, a shrink-fit hose or a suitably constructed protective sleeve.
With the previously described method, HF angular plug connectors can be realized, which are characterized by the use according to the invention of a HF corrugated sheath cable whose bend according to the invention, which is created by cold forming, has a significantly smaller bending radius than the minimum bending radius permitted by the manufacturer in each case. Thus, for example, an angular plug connector constructed according to the invention using a ¼″ corrugated sheath cable has an overall height of just approx. 40 mm. Although an overall height of this type can be realized with conventional angular plug connections, it cannot be realised using a conventional straight plug connection on a corrugated sheath cable, which would be bent minimally in accordance with manufacturer instructions and would furthermore permanently have HF transmission qualities that comply with the technical standard.
In another embodiment, the region of the cable is not bent directly following the straight plug connector along the corrugated sheath cable. Instead, the bend is rather in a suitable region, which lies spaced apart from the at least one plug connector attached to the cable at the end. Although the main aspect of the HF coaxial cable with angular plug connection according to the invention typically provides a bending angle β of 90° with a tolerance range of ±5°, i.e. 85°≦β≦95°, bends along the corrugated sheath cable are also conceivable with bending angles, β, which deviate therefrom, for example β=60°.
The dimensional shape of the angular plug connection and associated therewith the bending angle can be permanently fixed, for example by providing thermoplastically injection moulded geometries at the manufactured angular plug connection like webs, bulges, lobes, sieve-like structures. These geometries do not require additional effort and can be used for further functions like labels, attached caps, embedded functional parts etc.
Also, a plurality of bending regions can clearly be provided along a HF corrugated sheath cable, too, using the suggested cold forming method.
The invention is described by way of example in the following without limitation of the general inventive idea on the basis of exemplary embodiments with reference to the drawings. In the figures:
a-c show a sequential image illustration for cold forming according to the invention of the corrugated sheath cable with straight plug connector;
The cable end of the corrugated sheath cable 1 of
The novelty of the angular plug connection illustrated in
The actually achievable bending radius rα is dimensioned on a circumferential contour facing the inward bend along the cable outer conductor 2, which comes into contact with a correspondingly fitted bending tool, as is also described below. Additional application-specific properties can be realized with the envelope.
The bending of the corrugated sheath cable 1 takes place in a cold forming process, which is performed with sufficient care to not impair the electrically effective diameter de. The electrically effective diameter de for a corrugated sheath cable 1, which has a decisive influence on the HF signal transmission along the corrugated sheath cable 1, is composed of half of the sum of the maximum and minimum diameter of the corrugated sheath cable 1 results from the corrugated cable outer conductor structure thereof.
The dielectric diameter de is illustrated with two dashed lines l1 and l2 in
To produce the angular plug connection according to the invention, a straight end of a corrugated sheath cable 1 is prepared and provided by trimming the outer cable sheath 5 as far as the cable sheath end 51 of the cable outer conductor 2 and of the cable dielectric 3, as it were, with respect to the cable inner conductor 4 (cf.
Subsequently, a conventional straight plug connector S can be joined to the assembled cable end, the plug inner conductor 42 being securely connected, for example soldered or crimped, to the exposed cable inner conductor 4. Subsequently, the plug outer conductor 6 is pushed on or alternatively screwed on and soldered, clamped, welded or otherwise securely connected to the cable outer conductor 2. In this case, the straight plug connector S can be completed in advance, for example using a union nut 8, an insulating component 7 or, if necessary, using a seal 9. Alternatively, the straight plug connector S can be a plug, as a coupler or in a hybrid manner.
The cold-forming procedure takes place in the next step, which is explained with reference to the
The bending process is ended as soon as the clamping/tensioning element 15 has cold formed the corrugated sheath cable 1 by 90°, as is illustrated in
The bending guide 14 advantageously has a concavely constructed contact surface, using which the bending guide 14 comes into contact with at least one eighth, preferably up to a half of the circumferential edge of the corrugated cable outer conductor of the corrugated sheath cable 1. The concave construction of the bending guide 14 supports the shape retention of the cross-sectional geometry of the corrugated sheath cable 1 and, connected therewith, the constant electrically effective diameter de during the cold forming process.
The adaptation of the forces Fz and Fr acting on the corrugated sheath cable 1 during the cold forming process is of central importance. In particular, during the choice of the tensile force Fz acting along the corrugated sheath cable 1, it is necessary to note that the inner surfaces 16 and 17 of two corrugated guides (cf.
In
Starting from a straight, unbent corrugated sheath cable, to which a straight connector is attached to feed in a HF signal, VSWR values from close to 1 up to 1.04 maximum are shown. Using a corrugated sheath cable bent according to the invention, VSWR values in the range of 1 and maximum of 1.08 in the specified frequency range of 0 to 6000 MHz can be achieved. By contrast, in the case of a corrugated sheath cable conventionally assembled with an angular plug, a clear increase of the VSWR value is shown at frequencies from approximately 4500 MHz.
In addition, the simple structure of the angular plug connector formed according to the invention opens up, in view of a reduced number of parts, a significant reduction of intermodulation risks that occur definitely in conventionally formed angular plug connectors already due to their complex and multi-component structure.
Number | Date | Country | Kind |
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10 2012 014 425.3 | Jul 2012 | DE | national |
Reference is made to German Application DE 102 012 4425.3, filed Jul. 20, 2012 and PCT Application PCT/EP2013/002153, filed on Jul. 19, 2013, which applications are incorporated herein by reference in their entirety.
Filing Document | Filing Date | Country | Kind |
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PCT/EP2013/002153 | 7/19/2013 | WO | 00 |