EP1524720A1 - Antenna system for multiple frequency bands - Google Patents

Abstract

The antenna system has at least 2 quadrifilary helix antennae (3,4) offset from one another by 90 degrees and provided with double coils (R0,R90; T0,T90) having a 90 degree phase shift, both antennae wound about a cooom longitudinal axis and rotated through an angle of 45 degrees to one another, such that the double coils have the same spacing from the longitudinal axis in a given perpendicular plane.

Description

I. Field of application

The invention relates to an antenna system for simultaneous operation in at least two different frequency ranges, in particular for transmission and Receive in full duplex mode, especially for use with submarines.

II. Technical background

In satellite communications between fixed and mobile users from aviation and shipping, thus also among other things in the satellite communication of submarines, antenna structures are commonly used in a circular polarization, a quasi-hemispheric radiation pattern in this case, the need to track the Antenna system to the possibly geostationary satellite systems avoided can be.

According to the current state of knowledge, the only antenna structure that they required Features, a resonant quadrifilar helix antenna. These usually consists of two double helices, which are around a common Longitudinal axis winds, are orthogonal to each other and with 90 ° phase shift be stimulated.

Since it is in such an antenna system to a resonant working System is trading, the usable bandwidth is limited and it is difficult to one Adaptation to broadband usage or use for two different ones To reach frequencies. In cases where one operation in different Frequency ranges is required, therefore, usually on two separate, spatially separated quadrifilar helix antennas are used. This is especially true when operating simultaneously in both frequency ranges should be possible.

An example of such a case is the UHF Satcom satellite communication system, where the transmission and reception of data occurs in different frequency ranges: UHF Satcom reception 240-270 MHz UHF Satcom broadcast 290-320 MHz

It should be considered advantageous if at the same time and independently of each other can be sent and received (so-called full-duplex operation). It is a low coupling, so a low crosstalk between the transmitting / receiving antennas required. This is, as mentioned above, usually necessary that the transmitting and receiving antennas as separate Elements are formed.

However, the dimensions of the antenna system are available through the limited space, so a spatial separation of transmitting and Reception antennas made only with considerable effort.

An example of this is an antenna system of a submarine. In addition to the above-mentioned frequency ranges for satellite communication in the UHF Satcom system, even more frequency ranges are usually required beyond this, for example: Shortwave reception 1 - 30 MHz VHF reception (marine radio) 155-160 MHz Line of sight function 225 - 400 MHz GPS 1575.41 / 1227.6 MHz

In addition to the limited space available, exists in particular another requirement for an antenna system used by submarines in that the entire structure of the antenna due to the positioning the outer skin of the submarine hull and the associated loads must be as compact as possible by the circulating water. At the same time also the greatest possible stability of the antenna system over mechanical To ensure loads, as shock waves in the water short-term Horizontal loads up to 400 G as well as vertical loads up to the area of 150 G can occur.

III. Presentation of the invention a) Technical task

It is therefore the object of the invention, a possible compact antenna system to provide a preferably simultaneous operation in at least two different frequency bands, especially in the field of satellite communications using circularly polarized waves with a quasi-hemispheric radiation characteristic allows.

In this case, such an antenna system is preferably used on a Submarine. However, a user can also operate on conventional Benefit from the benefits of the invention over water or on land.

b) Solution of the task

This object is solved by the characterizing features of claim 1. Advantageous embodiments will be apparent from the dependent claims.

Accordingly, an antenna system for simultaneous operation, in particular for sending and receiving in full-duplex mode, in at least two different ones Frequency ranges, in addition to other existing antennas comprises at least two quadrifilar helix antennas, of each two orthogonal to each other and with 90 ° phase shift has excited double helices. Orthogonal is to be understood as that the two double helices of a helical antenna each with a Offset of 90 ° in the direction of rotation relative to each other about the longitudinal axis of the helical antenna run into each other, so that considered in a radial section plane the imaginary Connecting lines between the intersections of the respective helices a double helix with the plane orthogonal to each other, such as is indicated in Figure 3 by the dashed lines. According to the invention the two helical antennas wind around a common longitudinal axis, with respect to this longitudinal axis by an angle of 45 ° to each other are twisted. The double helices of both helix antennas have this in one any cutting plane transverse to the longitudinal axis in each case the same distance from Longitudinal axis.

This special arrangement of the two helix antennas is characterized by a particularly high symmetry, so that according to the invention, the mutual Influencing the two antennas is minimized.

In a preferred embodiment, the respective double helices of the Both helical antennas also have the same slope, whereby the symmetry of the System can be further improved once again.

Preferably, in this case, the double helices of the two helical antennas on the Mantle surface arranged a rotationally symmetrical to the longitudinal axis of the body. As a rotationally symmetrical body comes here in particular a cylinder in question, However, other geometric bodies such as a cone conceivable.

The feed of the respective helical antenna takes place in a direction transverse to the longitudinal axis extending plane, which lies at one end of the respective helix.

In this feed-in level, the supply of the respective helical antenna takes place usual way, d. H. that the respective double helices with a phase shift be operated by 90 degrees, with the feed of each one Double helix preferably takes place via a suitable balun. When Symmetry members come all known Symmetrieübertäger with windings or from line elements of the known constructions in question, for example Locking pots, balancing loops and pots, slot transfer.

In a preferred embodiment, the symmetrization of each double helix takes place via a balancing transformer in the form of a short-circuit line with λ / 4-length.

The phase-offset feed for generating the circular polarization takes place preferably using hybrid couplings or the like.

In a preferred embodiment, the two feed levels of the two fall Helix antennas together. The common feed-in level of both helix antennas In this case, it may preferably be facing at the direction of radiation End of the helix antennas are. In this case, the preferably used Symmetry transformers easily in a symmetrical arrangement inside the helix antennas are housed.

Preferably, the double helices of at least one helix antenna are not on the excited end open. In this way, over the length of the double helices the respective resonance of the helical antenna are influenced. In this embodiment have the double helices of the two nestled nested Helix antennas have a different length, so the two helix antennas have different resonance frequencies.

In the two frequency ranges in which the two helical antennas of the invention Antenna system can be operated, it may be preferred around the ranges of 210-300 MHz, in particular 240-270 MHz and of 260-350 MHz, in particular 290-320 MHz, act in this way To enable sending and receiving in the UHF Satcom system.

Although the two helical antennas of the antenna system according to the invention preferably can be operated simultaneously, d. H. in so-called full-duplex operation, They can also be used in so-called half-duplex mode where only one of the two antennas is in operation.

Which of the two modes is ultimately used depends on the requirements the user and the electronic equipment of the antenna system from.

Preferably, the two helical antennas are of their geometric dimensions, that is, for example, number of turns or pitch of the turns, but in particular so designed by their ratio of diameter to length that one helix antenna has its resonance in the range of 210-300 MHz, especially 240 - 270 MHz and the second helical antenna resonates in the range from 260 to 350 MHz, in particular 290 to 320 MHz and at the same time for circular (preferably right polarized) polarized waves an omni-hemispheric Radiation characteristic is achieved.

According to a further aspect of the present invention, the inventive Antenna system at least one other antenna coaxial with the two helix antennas, preferably defined by the two helices Interior is arranged.

This at least one further antenna may, for example, at a monopole emitter, in particular to act a rod antenna. However, they are In this case, other types of antenna conceivable, as long as a coaxial arrangement, preferably in the interior, the helical antennas is possible.

To minimize the coupling between the helix antennas on the one hand and on the other hand, to obtain the additional antenna is as coaxial as possible Alignment of the additional antenna in the center of the helix desirable. Accordingly, therefore, the radiators of the additional antenna have a rotationally symmetrical shape.

In a preferred embodiment of the antenna system according to the invention If the other antenna is a rod antenna with a roof capacity in the form of a plate, due to their geometrical dimensions to the Reception in the frequency ranges of 0.5-60 MHz and 125-190 MHz, in particular used in the frequency ranges of 1 - 30 MHz and 155 - 160 MHz can be.

As already indicated above, is a symmetrical arrangement as possible of the antenna system for a decoupling of the individual antennas extremely important to each other. To such a symmetrical arrangement also in the environmental conditions to which the antenna is subjected in use, too is in accordance with another aspect of the present invention a special mechanical structure provided.

Accordingly, the antenna system according to the invention preferably comprises a stable body, on the outer surface of the double windings of the two Helix antennas are fixedly arranged along a longitudinal axis of the body. The double helices may in this case, for example, have the form of wires, which are fastened on the outer surface. Preferably, however, it is tapes made of an electrically conductive material, for example copper tapes, which are arranged flat on the outer surface of the base body.

The basic body consists of any electrically non-conductive material, the desired mechanical properties in terms of stability and / or Having stiffness. Conceivable here are polymers or other plastics, for example Kapton, Mylar or similar.

According to a preferred embodiment, the main body of the antenna system the shape of a hollow cylinder. The feed of the helix antennas takes place on an end face of the base body, preferably from the attachment side of the antenna system seen at the distal end and thus at the Direction of irradiation facing end.

On the front side of the body, the feeding of the double helix is done from a central point that is substantially aligned with the longitudinal axis of the helix antennas and thus the body collapses, radially outward extending segments of conductive material applied on the front side are and lead respectively to the associated double helices.

To prevent that preferably running inside the body Feeders as well as those according to a preferred embodiment each associated Symmetrierrafos in the form of λ / 4 short-circuit lines at mechanical stress on the antenna system change their position and thus their for the decoupling of the two helical antennas necessary, symmetrical arrangement lose, these lines are inventively by a sufficiently rigid Foam material held stationary at their positions. As foam material For example, polyurethane foam, polystyrene, polyvinyl chloride foam, but other foams can be used as long as the Holders of lines necessary rigidity is ensured.

In addition to the necessary stiffness of the foam used should also have special electrical properties, in particular the radiation properties to influence the helix antennas as little as possible. As a result, according to the invention, the foam used preferably has a dielectric constant and a loss factor comparable to that of air are.

Here, the entire hollow interior of the body with the foam material be lined, the lines then by appropriate Channels are guided in the foam material. However, preference is given using one or more cylinders of the corresponding foam material, which are aligned along the longitudinal axis of the main body and on whose lateral surfaces suitable grooves for receiving and storing the corresponding Lines are provided. In this case, the remaining hollow interior remains of the main body free.

Preferably, the lines through the foam used the majority of the length inside the body at a constant distance held. However, this distance will be close to the entry point on the Face of the body is reduced to the lowest possible transition between the respective infeed line and the associated balancing transformer to obtain the best possible symmetrization.

In a preferred embodiment, of course, inside the Foam body Holes for additional lines for the supply of additional Be provided antennas.

To protect the antenna system against water and the usually prevalent Water pressure when using a submarine is the entire Construction according to the invention with a hood e.g. surrounded by plastic. This plastic hood has a substantially cylindrical shape, which at its regarding the attachment of the antenna system to the submarine fuselage distal End is provided with a hemispherical cover and at its proximal End is tightly connected to the plate to be fastened to the fuselage. Of the Outside diameter of this plastic hood is available through the during installation given space. As materials come here for example glass fiber reinforced plastic, epoxy resin or the like in question.

In the case of use on a normal ship or on land, this serves Plastic hood essentially the protection against external environmental influences. There there is no requirement of resistance to pressure in this case, For example, the thickness of the hood may be lower and / or lower requirements the material used is provided.

c) embodiments

Fig. 1:

eine Schnittansicht durch eine Ausführungsform eines erfindungsgemäßen Antennensystems mit zwei quadrifilaren Helixantennen;

Fig. 2:

eine Aufsicht auf die Deckplatte an der Stirnseite des in der in Fig. 1 gezeigten Ausführungsform verwendeten Grundkörpers, auf der die gemeinsame Einspeiseebene der Helixantennen liegt;

Fig. 3:

eine Aufsicht auf die Anschlussplatte der Einspeiseleitungen der in Fig. 1 gezeigten Ausführungsform;

Fig. 4:

eine Schnittansicht der in Fig.2 dargestellten Deckplatte und

Fig. 5:

eine Detailldarstellung eines Teilbereichs von Fig.1.

An embodiment according to the invention is described in more detail below by way of example with reference to the figures. Show it:

Fig. 1:

a sectional view through an embodiment of an antenna system according to the invention with two quadrifilar helical antennas;

Fig. 2:

a plan view of the cover plate on the front side of the base body used in the embodiment shown in Figure 1, on which lies the common feed plane of the helical antennas.

3:

a plan view of the terminal plate of the feed lines of the embodiment shown in Figure 1;

4:

a sectional view of the cover plate shown in Figure 2 and

Fig. 5:

a detailed representation of a portion of Fig.1.

FIG. 1 shows a sectional view through an embodiment of a device according to the invention Antenna system. This comprises two quadrifilar helix antennas 3, 4, arranged on the lateral surface of a base body 1 in the form of a hollow cylinder are.

In the cylindrical base body 1 is at the respect of the attachment of the Antenna system proximal end of a half-open mounting cylinder 6 introduced its closed end in the direction of the radiation of the antenna system shows. In the middle of this end face 61 of the mounting cylinder 6 is a circular recess for receiving a mounting plate 5 is provided which is fastened by means of screws 56 to the mounting cylinder 6.

Fig. 2 shows a top view from below of the mounting plate 5. In addition to the Screw holes 55 for fixing the plate 5 to the mounting cylinder 6 points the plate 5 first four ports 51,52,53,54 for the feed lines the double helices T0, R0, T90, R90 of the two helical antennas 3,4, to which the each of the hybrid couplings 62 (see Fig. 5) of the base module of the antenna system coming supply lines can be connected. These cables are conventional coaxial cables.

To each of these four ports 51,52,53,54 is diametrically opposed to the longitudinal axis of the main body 1, a connection 51 a, 52 a, 53 a, 54 a provided, each of which End of the λ / 4 short-circuit line belonging to the corresponding double helix T0, R0, T90, R90 8 represents. This total of eight ports 51, 52, 53, 54, 51a, 52a, 53a, 54a are symmetrically equiangularly spaced 45 degrees on a circle with a constant distance to the longitudinal axis of the body 1 arranged.

Of the four connections 51,52,53,54 run inside the cylindrical Main body 1 coaxial cable 7 in the direction of the distal end of the body 1, there first the cover plate 2, with the distal end of the body 1 is closed, pierced in a central area. As shown in FIG. 3, in this case, the respective outer conductor of the coaxial cable 7 on the front side of the cover plate 2 with sectors 21,22, 23,24 connected. These exist made of conductive material and lead radially from the central area to the outside, from there the first helix of the respective double helix To feed T0, R0, T90, R90. In the present case, the sectors 21, 22, 23,24 of a copper foil on the cover plate 2 of non-conductive material are applied.

Each diametrically to the sectors 21,22,23,24, each with the outer conductors are connected to the corresponding feed lines 7, there are sectors 21a, 22a, 23a, 24a, which also consist of copper foil and radially from the central Run area radially outward to from there the second coil of the respective Double spiral T0, R0, T90, R90 to feed.

In order to obtain a correct supply of the respective double helices T0, R0, T90, R90, is the respective inner conductor 7a of the feed lines 7 of a double helix T0, R0, T90, R90, as shown in Fig. 4, with the respective corresponding Double helix T0, R0, T90, R90 belonging, diametrically-lying sector 21a, 22a, 23a, 24a and an associated line 8. This line 8 is formed in the present case in each case by the outer conductor of a coaxial cable, which, however, has no inner conductor. The outer conductor of the feed line 7 and the associated line 8 each form a λ / 4 short-circuit line for transforming the unbalanced signal of the feed line 7 in a symmetrical signal at the feed point. The line 8 extends through the Cover plate 2 into the interior of the base body 1, traverses this and is conductive with connected to the plate 2.

Due to the requirement that this λ / 4 short circuit lead to a quarter correspond to the wavelength of the resonance frequency of the respective helical antenna 3,4 must arise, the position of the plate 5 and thus the geometric dimensions the mounting cylinder 6 in the interior of the main body. 1

In the present case, the feed lines 7 and the lines 8 of the Plate 5 starting in the interior of the base body 1 first of three to the longitudinal axis the basic body aligned cylinders 9 made of foam material, and between these cylinders 9 arranged cutting discs 10 is supported. The Cylinders 9 in this case have an identical cross-section, wherein the feed lines 7 and the lines 8 in corresponding grooves in the lateral surfaces the cylinder 9, and guided in through holes in the cutting wheels 10 are. In this way, the lines are 7,8 in their symmetrical arrangement with substantially identical distance to the longitudinal axis of the body 1 held.

Following the third cutting disc 10, the lines are then 7.8 in grooves in the lateral surface of a substantially cone-shaped foam body 9a out, which tapers in the direction of the cover plate 2. At this cone-shaped Foam body 9a is followed by another cutting disc 10a with smaller Radius, which in turn through holes for through Has lines 7,8. Finally, between the cutting disc 10 a and the Cover plate 2, a further cylinder 11 disposed of foam, in turn Has grooves in its lateral surface to the lines leading through 7,8 take.

In this way, the distance between the symmetrical to a double helix can be symmetrical T0, R0, T90, R90 belonging to lines 7,8 are reduced so that a better symmetrization of the illustrated in Fig. 4, exposed area of the inner conductor 7a becomes small with respect to the wavelength λ.

In the present case, a material which preferably has the following physical properties is used as the foam material for the cylinders 9, the conical foam body 9a and the cylinder 11: density <50 kg / m ³ , in particular <35 kg / m ³ permittivity 1.0 - 1.1 for frequencies <26.5 GHz Dielectric loss factor <0.002 for frequencies <10 GHz

For example, a commercially available foam material is used suitable polymethacrylimide (PMI) rigid foam such as Rohacell®31 in question.

The cutting discs 10 and 10a are in the present case of a preferably very stiff material with good breaking strength and suitable dielectric Properties. For example, these requirements of polyvinyl chloride (PVC hard) met.

Furthermore, the cylinders 9, the cone-shaped foam body 9a, the cylinder 11 and the cutting discs 10 and 10a in the present case a central Bore up, so that if necessary centrally on the longitudinal axis of the main body 1 one or more feed lines for additional antennas, for example can be mounted on the cover plate 2, can be performed.

The double helices T0, R0, T90, R90 of the two helix antennas 3,4 are in the present embodiment in each case by corresponding strips of copper foil formed, which are wound on the lateral surface of the base body 1. As a result, are the respective double helices in the present case to that of the feed open at opposite ends. The bands are at the transition area between the cover plate 2 and the lateral surface of the base body 1 electrically conducting with the respective sectors 21, 21 a, 22, 22 a, 23, 23 a, 24, 24 a of the double helixes connected.

The two helical antennas 3, 4 of the antenna system according to the invention can in the selected embodiment in the two ranges of 240-270 MHz or 290-320 MHz, so that sending and receiving in the UHF Satcom system is possible. Because a resonance at a lower frequency connected to a greater length of the corresponding double helices 1, it can be seen that in the present case it is the helix antenna 4, which operates in the range of 240 - 270 MHz.

Depending on the electronics used, the two helical antennas 3,4 in the present embodiment either in full-duplex mode or in half-duplex mode operate.

Due to the inventive symmetrical arrangement of the two in one another wound helical antennas 3,4 can already be insulated in the present case between the two antennas of greater than 15 dB can be achieved. By additional use of filters can further enhance this decoupling be, for example, up to 30 dB.

The typical benefit of the present antenna system with the two helical antennas 3.4 is typically 0 dBi, but 2 dBi can be achieved become. It becomes an omni-hemispheric radiation image in a right-polarized Radiation generated. The antenna impedance is 50 ohms. The maximal Operating power 200 W.

FIG. 5 shows a detailed view of a subregion from FIG. 1 and represents the base region of the antenna system with the mounting cylinder 6. Inside the Mounting cylinder 6 is an additional in the embodiment shown here Antenna housed.

This is a monopoly in the form of a rod antenna with a Top capacity. This monopoly is in the present case by a copper ring 63 formed by means of spacers 64 in a transverse plane of the body 1 is kept and the directly via an isolated connection with the Base module of the antenna system is connected.

The additional rod antenna is in the present case for reception in the frequency ranges of 1 MHz - 30 MHz and 155 MHz - 160 MHz used.

Furthermore, the two 90 ° hybrid couplings are located inside the assembly cylinder 6 62 for generating the phase shift for the feed helix antennas 3,4. These are on a final body 1 Cover 66 arranged on the outside of the terminals 65 are provided are, over which the antenna system with the supply unit, not shown is connected.

The hood for protecting the antenna system against environmental influences is in the present embodiment of a radome made of glass fiber reinforced epoxy resin formed, whose wall thickness of the use, with either one Submarine or over water or ashore, depends.

LIST OF REFERENCE NUMBERS

1

body

2

cover plate

3

helix antenna

4

helix antenna

5

mounting plate

6

mounting cylinder

7

feeder

7a

inner conductor

8th

management

9

foam cylinder

9a

foam cone

10

cutting wheel

10a

cutting wheel

11

small foam cylinder

21, 21 a

sectors

22, 22a

sectors

23, 23a

sectors

24, 24a

sectors

51.51 a

connections

52,52a

connections

53,53a

connections

54,54a

connections

55

screw holes

56

screw

61

Front side of 6

62

hybrid couplings

63

copper ring

64

spacer

65

connections

66

cover

T0

double helix

T90

double helix

R0

double helix

R90

double helix

Claims (11)

Antenna system for simultaneous operation in at least two different frequency ranges, in particular for transmitting and receiving in full-duplex mode, with at least two quadrifilar helix antennas (3,4), each of which two arranged in the direction of rotation with 90 ° offset from each other and with 90 ° phase shift excited double helices (R0, R90, T0, T90),
characterized in that
the two helix antennas (3, 4) wind around the same longitudinal axis, being rotated with respect to the common longitudinal axis at an angle of 45 ° to each other, and the double helices (R0, R90, T0, T90) of both helix antennas (3, 4) in FIG have an arbitrary sectional plane transverse to the longitudinal axis in each case the same distance from the longitudinal axis. Antenna system according to claim 1,
characterized in that the double helices (R0, R90, T0, T90) of the two helix antennas (3, 4) are arranged on the lateral surface of a body which is rotationally symmetrical to the longitudinal axis, and in particular that the rotationally symmetrical body is a cylinder. Antenna system according to one of the preceding claims,
characterized in that the feeding of the respective helix antenna (3, 4) takes place in a plane extending transversely to the longitudinal axis, which lies at one end of the respective helix, in particular that the feed levels of both helix antennas (3, 4) coincide and that in particular, the common feed-in level of both helical antennas (3, 4) lies at the end of the helix antennas (3, 4) facing the emission direction. Antenna system according to one of the preceding claims,
characterized in that the double helices (R0, R90, T0, T90) of at least one helix antenna (3,4) are open at the unexcited end, or that the double helices (R0, R90, T0, T90) of the two helix antennas (3, 4) have the same pitch. Antenna system according to one of the preceding claims,
characterized in that the double helices (R0, R90, T0, T90) of the two helix antennas (3, 4) have different lengths, so that the helix antennas (3, 4) have different resonance frequencies, and in particular, one helical antenna (3, 4) has its resonance in the range of 210-300 MHz, in particular 240-270 MHz, and the second helical antenna (3,4) has its resonance in the range of 260-350 MHz, in particular 290-320 MHz. Antenna system according to one of the preceding claims,
characterized in that
Among other things, the at least two frequency ranges are the ranges of 210-300 MHz, in particular 240-270 MHz and of 260-350 MHz, in particular 290-320 MHz. Antenna system according to one of the preceding claims,
characterized in that
the two helical antennas (3,4) are designed with respect to their geometric dimensions, in particular their ratio of length to diameter, so that they have an omni-hemispherical radiation characteristic for right circularly polarized waves. Antenna system according to one of the preceding claims,
characterized in that coaxial with the two helical antennas (3,4) at least one further antenna is present and in particular that the at least one further antenna is a monopole emitter, in particular a rod antenna (63), due to its geometrical dimensions for reception in the frequency ranges of 0.5-60 MHz and 125-190 MHz, in particular in the frequency ranges from 1 to 30 MHz and 155 to 160 MHz. Antenna system according to one of the preceding claims,
characterized in that the symmetrization of the helix antennas (3, 4) takes place in each case via short-circuit lines, wherein a short-circuit line consists of a feed line (7) and a line (8), and in particular that all supply lines (7) and lines (8) are arranged symmetrically in the longitudinal direction of the antenna system equidistant from the longitudinal axis of the helix antennas (3,4), with one feed line (7) and one associated line (8) diametrically opposite each other and / or that in particular the feed lines (7) and / or lines (8) are held stationary by a foam material (9, 9a, 11) at least over a partial section. Antenna system according to claim 9,
characterized in that the holder of the lines (7,8) in grooves on the lateral surface of separate foam bodies (9,9a, 11) takes place and in particular that the foam bodies (9, 9a, 11) have the shape of cylinders and cones. Antenna system according to claim 9 or 10,
characterized in that between the individual foam bodies (9,9a, 11) plates (10,10a) are arranged from an inflexible material, wherein the lines to be held (7,8) are guided through openings in these plates and / or in particular, the lines (7, 8) are guided essentially at a constant distance from the longitudinal axis and the distance is reduced only near the entry points.

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