Patent Publication Number: US-2022227657-A1

Title: Quartz fibre with hydrogen barrier layer and method for the production thereof

Description:
Examples of the invention relate to concepts for transmitting high-frequency electromagnetic signals and applications related to this, and in particular to a cable and a method for manufacturing the same. 
     A plurality of options exists for transmitting data. Beginning with symmetric and asymmetric transmission forms, even hollow waveguides and optical fibres are customary. Another option is transmission via dielectric waveguides. Dielectric waveguides operate without a share of a conductive constituent in the transmission medium. On account of their transmission principle also they should be arranged dose to the optical fibres. 
     When transmitting high-frequency signals, the conductivity of a metal, for example, is used. The energy is carried in this case between two metal conductor surfaces inside a dielectric insulation material. Energy transportation in the hollow waveguide takes place inside a hollow conductive structure coordinated in size to the desired frequency. High frequencies coordinated to the geometry of the hollow waveguide are necessary here to produce a wave mode that is capable of propagation. Symmetric and asymmetric lines up to the lower GHz range can be used for this (e.g. even up to 25 GHz). 
     In coaxial structures, the maximum operating frequency range is limited by what is termed the “cut-off” frequency, above which additional modes propagate. For higher frequencies, the hollow waveguide accordingly represents a more suitable transmission medium. 
     A disadvantage underlies all the aforesaid transmission principles, however. The energy of the transmission is always carried by means of metal conductors. Here the resistance increases at high frequencies due to the skin effect, leading to a rise in transmission losses. At frequencies in the range from a few GHz up to more than 100 GHz the losses are so great that a sufficiently long distance can no longer be spanned in the application. Moreover, hollow waveguides are inflexible and have a high weight. 
     Another means of data transmission is constituted by an optical fibre. In this case, data is sent in a structure consisting of an optical core with a surrounding “cladding”. The frequencies used here are so high that they are in the range of light (several hundred terahertz). One disadvantage of this transmission form is that an electrical signal always has to be converted first into a light signal and the materials involved in the transmission must meet high optical demands (e.g. purity, transparency and refractive index). 
     The technologies presented above are little suited to transmitting data in a frequency range from a few dozen GHz up to a few hundred GHz. This is where the dielectric waveguide comes into play. This line consists of non-conductive materials. It is important here to provide layering of different dielectric constants. A very high-frequency signal injected into the dielectric waveguide adheres to the boundary layer between high and lower ε r (=relative dielectric constant) and is transmitted in the propagation direction with little loss. 
     There are dielectric waveguides in the prior art that are part of circuit boards and are is adapted to the conditions predetermined by the respective circuit boards. Here materials are used on the one hand that do not meet automotive requirements in relation to flexibility and mechanical installation and cannot be manufactured in any length on the other hand. 
     Another limitation should be seen in the fact that on account of their pronounced field pattern outside of the inner region with a large ε r , waveguides easily experience crosstalk with adjacent systems. In a waveguide system, for example, two dielectric waveguides, each with a high ε r  and a circular or at least virtually circular cross section are arranged adjacent to one another in a plastic sheath with a lower ε r . A high-frequency signal injected into one of these dielectric waveguides is accompanied by electromagnetic fields, which also penetrate the adjacent dielectric waveguide (second waveguide positioned in the vicinity) and produce a signal in this that overlays a useful signal injected into this (second) dielectric waveguide and influences this. 
     Cables with dielectric waveguides must where possible be optimised with regard to a reduction in electromagnetic coupling. It is nonetheless desirable to form cables with a small spatial extension. 
     A requirement may exist for providing concepts for cables with dielectric waveguides that experience less mutual interference and at the same time do not take up any more space. 
     Such a requirement can be met by the subject matter of the claims. 
     According to a first aspect of the invention, a cable is provided. The cable has a dielectric medium. The dielectric medium forms a chamber. The chamber can also be filled by the dielectric medium. The cable further has a first dielectric waveguide element. The cable also has a second dielectric waveguide element. The first dielectric waveguide element is spaced at a distance from the second dielectric waveguide element. The first dielectric waveguide element runs along a longitudinal direction of the cable through the chamber formed by the dielectric medium. The second dielectric waveguide element runs along the longitudinal direction of the cable through the chamber formed by the dielectric medium. A preferred polarisation direction of the first dielectric waveguide element differs from a preferred polarisation direction of the second dielectric waveguide element. 
     Due to the different preferred polarisation directions, fewer electromagnetic fields are coupled from the first into the second waveguide element and at the same time a space-saving cable is provided. 
     Each waveguide element can form a waveguide together with the dielectric medium. The waveguide element can serve here as the transmission medium. 
     The first and second dielectric waveguide element can run/be arranged in parallel along the chamber or the cable. 
     The first and second dielectric waveguide element can each be formed to transmit a as high-frequency signal. For example, the first dielectric waveguide element can be used as a transmitting path and the second dielectric waveguide element as a receiving path or vice versa. The first and the second dielectric waveguide element can be used in just the same way as transmitting path or receiving path. 
     The dielectric medium can surround the first and second dielectric waveguide elements running in the chamber. The dielectric medium can surround the first and the second dielectric waveguide element respectively here so that at end pieces of the cable, the first and second dielectric waveguide element is connectable to a complementary end piece of a cable or plug. Inside the chamber the dielectric medium can fill a section between the first and second waveguide elements. 
     The preferred polarisation direction of the first dielectric waveguide element can be predetermined by a cross section of the first dielectric waveguide element. The preferred polarisation direction of the second dielectric waveguide element can be predetermined by a cross section of the second dielectric waveguide element. The preferred polarisation direction of the first dielectric waveguide element can differ from the preferred polarisation direction of the second dielectric waveguide element by an s angle of at least 45° (or 60° or 75° or 90°), in particular by an angle of 90°. The cross sections of the first and second dielectric waveguide element can be twisted relative to one another for this. This means that the first and second dielectric waveguide element can be e.g. not point-symmetric and/or axisymmetric. For example, the dielectric waveguide elements and the waveguides thus formed are not optical fibres or hollow waveguides. 
     The cross sections of the first and second dielectric waveguide elements can be at least substantially identical. By twisting them relative to one another, it can be avoided that waves unintentionally penetrate the respectively other waveguide element and are capable of propagation there. 
     The cross section of the first and/or second dielectric waveguide element can be elliptical or rectangular. The elliptical cross section can have a main axis a and a secondary axis b. The rectangular cross section can have two side lengths a and b. The main axis a and the side length a can be greater than the secondary axis b and the side length b. In particular, the main axis a and the side length a can be 1.25 times (or 1.5 times or 2 times or 3 times or 4 times) greater than the secondary axis b and the side length b. 
     The ratio of a to b can predetermine the preferred polarisation direction of the first and second dielectric waveguide element. If the first and second waveguide elements are arranged twisted relative to one another in the cable, coupling into the respectively other dielectric waveguide element can be reduced hereby, as the preferred polarisation directions of the first and second dielectric waveguide element are different and have a preferred polarisation predetermined by the geometry, which prevents electromagnetic waves of another polarisation direction from being able to link in. 
     A spacing between the first and second dielectric waveguides can be smaller than 4 times (or 3 times or 2 times) a side length a or main axis a of the first and/or second dielectric waveguide element. Furthermore, a spacing between the first and second dielectric waveguides can correspond to at least a side length a or main axis a of the first and/or second dielectric waveguide element. 
     Dielectric constants of the first and second dielectric waveguide elements can be at least substantially identical. The dielectric medium can have a different dielectric constant from the first and second dielectric waveguide element. The dielectric constant of the dielectric medium can be lower than at least one of the dielectric constants of the first and second dielectric waveguide element. The dielectric constants of the first and/or second dielectric waveguide element can deviate at most between 0.5% and 5% from one another, for example. 
     The cable can also have a jacket. The jacket can surround the chamber. The cable can be made more weather-resistant by this. The jacket can likewise end at the end pieces of the cable. 
     The jacket can be at least partly conductive. Electromagnetic coupling can be avoided hereby. In addition or alternatively, the jacket can be at least partly non-conductive. For example, the jacket can be provided with metal armour. 
     The jacket can also end flush with the dielectric medium. Water and oxygen inclusions can be avoided hereby, whereby the cable is made more durable. 
     The cable can further have a third dielectric waveguide element. The third dielectric waveguide element can be spaced at a distance from the first and second dielectric waveguide elements. The preferred polarisation direction of the first dielectric waveguide element can correspond to a preferred polarisation direction of the third dielectric waveguide element. The preferred polarisation directions of the first, second and third dielectric waveguide element can differ respectively by an angle of 60° from one another. 
     The cable can further have a fourth dielectric waveguide element. The fourth dielectric waveguide element can be spaced at a distance from the first, second and third dielectric waveguide elements. The preferred polarisation direction of the second dielectric waveguide element can correspond to a preferred polarisation direction of the fourth dielectric waveguide element. 
     Using several waveguides formed by the waveguide elements and the dielectric medium can provide a greater transmission rate and more throughput. At frequencies of over 100 GHz (without light), a higher bandwidth can likewise be provided. 
     A respective distance between the first and second waveguide element, and the second and third waveguide element, and the third and fourth waveguide element as well as the fourth and first waveguide element can be identical. This distance can correspond to a value A. 
     A distance between the first and third waveguide element can correspond to a distance between the second and fourth waveguide element. This distance can correspond to a value B. 
     B can be √2*A. Even if the first and third or the second and fourth waveguide element have the same preferred polarisation direction, coupling into the respectively other waveguide element can be reduced by the greater distance (√2 times greater), 
     The respective distance between the waveguide elements can be determined starting out from a centre of a respective cross section of the waveguide elements in the same cross-sectional plane of the cable. 
     The chamber can further comprise several segments. In this case, the dielectric medium can likewise be divided into several segments. Each segment of the dielectric medium can enclose/surround one of the (first/second/third/fourth) waveguide elements separately (in the chamber). The segments can be mutually in contact. The segments can each contact the jacket. 
     According to a second aspect of the invention, a method is provided for manufacturing a cable according to the first aspect. The method comprises provision of a first and second dielectric waveguide element. The first and second dielectric waveguide element are spaced at a distance from one another. The first dielectric waveguide element is twisted compared with the second dielectric waveguide element, so that a preferred polarisation direction of the first dielectric waveguide element differs from a preferred polarisation direction of the second dielectric waveguide element in the cable. The method can further comprise embedding of the first and second dielectric waveguide element in a chamber made of a dielectric medium. Alternatively, the embedding can comprise embedding of the first and second dielectric waveguide element in respective segments of the dielectric medium. The chamber can be formed by stranding of the segments. 
     Even if some of the aspects described above were described with reference to methods, these aspects can also apply to the cable. In just the same way, the aspects described above in relation to the cable can apply in a corresponding manner to the method. 
     It is likewise understood that the terms used here only serve to describe individual embodiments and are not intended to be considered a limitation. Unless otherwise defined, all technical and scientific terms used here have the meaning that corresponds to the general understanding of the expert in the specialist field relevant for the present disclosure; they should be interpreted neither too broadly nor too narrowly. If specialist terms are used here incorrectly and thus do not give expression to o the technical idea of the present disclosure, these should be replaced by specialist terms that convey a correct understanding to the expert. The general terms used here should be interpreted on the basis of the definition found in the dictionary or according to the context; too narrow an interpretation should be avoided in this case. 
     It should be understood here that terms such as e.g, “comprise” or “have” etc. signify the presence of the described features, numbers, operations, actions, components, parts or their combinations and do not exclude the presence or the possible addition of one or more other features, numbers, operations, actions, components, parts or their combinations. 
     Although terms such as “first” or “second” etc. are possibly used to described various components, these components should not be restricted to these terms. A component is only to be distinguished from the others using the above terms. For example, a first component can be described as a second component without departing from the protective scope of the present disclosure; likewise a second component can be termed a first component. The term “and/or” comprises both combination of the several objects connected to one another and any object of this plurality of the described plurality of objects. 
     The preferred embodiments of the present disclosure are described below with reference to the enclosed drawings; components of the same kind are always provided here with identical reference characters. In the description of the present disclosure, detailed explanations of known connected functions or constructions are dispensed with if these deviate unnecessarily from the sense of the present disclosure; such functions and constructions are comprehensible to the expert, however. The enclosed drawings of the present disclosure serve to illustrate the present disclosure and should not be understood as a limitation. The technical idea of the present disclosure should be interpreted in such a way that in addition to the enclosed drawings it comprises also all such modifications, changes and variants. 
    
    
     
       Further objectives, features, advantages and application possibilities result from the following description of exemplary embodiments, which are not to be understood as restrictive, with reference to the associated drawings. Here all features described and/or depicted show by themselves or in any combination the subject matter disclosed here, even independently of their grouping in the claims or their references. The dimensions and proportions of the components shown in the figures are not necessarily to scale in this case; they may diverge in embodiments to be implemented from what is shown here. 
         FIG. 1  shows a schematic representation of a cable with two waveguides; 
         FIG. 2  shows a schematic representation of a cable with four waveguides in a first arrangement; 
         FIG. 3  shows a schematic representation of a cable with four waveguides in a second arrangement; 
         FIG. 4  shows a schematic representation of a method for manufacturing a cable; 
         FIG. 5 a    shows an S-parameter result for a cable with two waveguides according to  FIG. 1 ; 
         FIG. 5 b    shows an S-parameter result for a cable with four waveguides according to  FIG. 2 ; 
         FIG. 5 c    shows an S-parameter result for a cable with four waveguides according to  FIG. 2 ; 
         FIG. 5 d    shows an S-parameter result for a cable with four waveguides according to  FIG. 2 ; and 
         FIG. 6  shows a schematic representation of a cable with four waveguide elements each enclosed by a separate part of the dielectric medium. 
     
    
    
     The cable and the method are now described on the basis of exemplary embodiments. 
     Specific details are set out below, without being restricted thereto, to supply a complete understanding of the present disclosure. It is dear to an expert, however, that the present disclosure can be used in other exemplary embodiments that may deviate from the details set out below. 
       FIG. 1  shows a schematic representation of a cable  100  with two waveguides, which are formed by dielectric waveguide elements  110  and  120  together with a dielectric medium  150 . The dielectric medium  150  forms a chamber. The chamber can also be filled by the dielectric medium  150 . The cable  100  further has a first dielectric waveguide element  110 . The cable  100  further has a second dielectric waveguide element  120 . The first dielectric waveguide element  110  is spaced at a distance from the second dielectric waveguide element  120 . The first dielectric waveguide element  110  runs along a longitudinal direction of the cable through the chamber formed by the dielectric medium. The longitudinal direction runs into the drawing plane in  FIG. 1 . The chamber formed can be just a part of the cable  100  here, for example, or extend over the entire length of the cable  100 . The second dielectric waveguide element  120  also runs along the longitudinal direction of the cable  120  through the chamber formed by the dielectric medium  150 . A preferred polarisation direction of the first dielectric waveguide element  110  differs from a preferred polarisation direction of the second dielectric waveguide element  120 . In  FIG. 1 , the preferred polarisation directions are in the y-direction in the case of the first dielectric waveguide element  110  and in the x-direction in the case of the second dielectric waveguide element  120 . 
     Due to the different preferred polarisation directions, fewer electromagnetic fields can be coupled from the first waveguide element  110  into the second waveguide element  120  and at the same time a space-saving cable  100  can be provided. 
     In the example from  FIG. 1 , each waveguide element  110 ,  120  forms a waveguide together with the dielectric medium  150 . In this case the waveguide element  110 ,  120  can serve as the transmission medium. 
     The first and the second dielectric waveguide element  110 ,  120  can run/be arranged in parallel along the chamber or the cable  100 . According to the example from  FIG. 1 , the first and second dielectric waveguide elements  110 ,  120 , run in parallel into the drawing plane. They are surrounded here by the dielectric medium  150 . Two waveguides are formed hereby along the cable  100 . 
     The first and the second dielectric waveguide element  110 ,  120  can each be formed to transmit a high-frequency signal. For example, the first dielectric waveguide element  110  can be used as a transmitting path and the second dielectric waveguide element  120  can be used as a receiving path or vice versa. The first and the second dielectric waveguide element  110 ,  120  can be used in exactly the same way as transmitting path or receiving path. 
     In the example from  FIG. 1 , the dielectric medium  150  surrounds the first and second dielectric waveguide elements  110 ,  120  running in the chamber. The dielectric medium  150  can surround the first and the second dielectric waveguide element  110 ,  120  respectively here so that the first and the second dielectric waveguide element  110 ,  120  is connectable at end pieces of the cable  100  to a complementary end piece of a cable  100  or plug. Inside the chamber the dielectric medium  150  can fill a section between the first and second waveguide elements. 
     The preferred polarisation direction of the first dielectric waveguide element  110  can be predetermined by a cross section of the first dielectric waveguide element  1100  The preferred polarisation direction of the second dielectric waveguide element  120  can be predetermined by a cross section of the second dielectric waveguide element  120 . The preferred polarisation direction of the first dielectric waveguide element  110  can differ from the preferred polarisation direction of the second dielectric waveguide element  120  by an angle of at least 45° (or 60° or 75° or 90°), in particular by 90°. In the example from  FIG. 1 , the preferred polarisation directions of the first dielectric waveguide element  110  and the second dielectric waveguide element  120  differ by 90°. To this end the cross sections of the first and second dielectric waveguide elements  110 ,  120  can be twisted relative to one another. In the example from  FIG. 1 , the cross sections of the first and second dielectric waveguide element  110 ,  120  are twisted by 90° relative to one another. Due to the twisting relative to one another it can be avoided that waves penetrate unintentionally into the respectively other waveguide element  110 ,  120  and are capable of propagation there. This means that the first and second dielectric waveguide element  110 ,  120  can be e.g. not point-symmetric and/or axis-symmetric. For example, the dielectric waveguide elements  110 ,  120  and the waveguides formed thus are not optical fibres or hollow waveguides. 
     The cross sections of the first and second dielectric waveguide element  110 ,  120  are identical in  FIG. 1  purely as an example. 
     The cross section of the first and/or second dielectric waveguide element  110 ,  120  can be elliptical or, as shown by way of example in  FIG. 1 , rectangular. The elliptical cross section can have a main axis a and a secondary axis b. The rectangular cross section can have two side lengths a and b. The main axis a or the side length a can be greater than the secondary axis b or the side length b. In particular, the main axis a or the side length a can be 1.25 times (or 1.5 times or 2 times or 3 times or 4 times) greater than the secondary axis b or the side length b. 
     The ratio of a to b can determine the preferred polarisation direction of the first and second dielectric waveguide element  110 ,  120 . If the first and second dielectric waveguide elements  110 ,  120  are arranged twisted relative to one another in the cable, as is shown in  FIG. 1 , the interference in the respectively other dielectric waveguide element  110 ,  120  can be reduced hereby, as the preferred polarisation directions of the first and second dielectric waveguide element  110 ,  120  are different and have a preferred polarisation predetermined by the geometry that prevents electromagnetic waves of another polarisation direction from being able to link in. 
     A distance between the first and second dielectric waveguides  110 ,  120  can be smaller than 4 times (or 3 times or 2 times) a side length a or main axis a of the first and/or second dielectric waveguide element  110 ,  120 . Furthermore, a distance between the first and second dielectric waveguides  110 ,  120  can equal at least a side length a or main axis a of the first and/or second dielectric waveguide element  110 ,  120 . 
     The dielectric constants of the first and second dielectric waveguide element  110 ,  120  can be substantially identical. The dielectric medium  150  can have a different dielectric constant than the first and second dielectric waveguide element  110 ,  120 . The dielectric constant of the dielectric medium  150  can be lower than at least one of the dielectric constants of the first and second dielectric waveguide element  110 ,  120 . The dielectric constants of the first and/or second dielectric waveguide element  110 ,  120  can deviate at most between 0.5% and 5% from one another, for example. 
     In the example from  FIG. 1 , the cable  100  further has a jacket  160 . The jacket  160  can surround the chamber. The cable  100  can be made more weather-resistant hereby. The jacket  160  can likewise end at the end pieces of the cable  100 . 
     The jacket  160  can likewise be conductive. Electromagnetic couplings can be avoided hereby. 
     The jacket  160  can also end flush with the dielectric medium  150 . Water and oxygen inclusions can be avoided hereby, whereby the cable  100  is rendered more durable. 
     The waveguide elements  110 ,  120  named herein can each consist of a material with a high ε r . This can be polyethylene (PE), polypropylene (PP), ethylene-tetrafluoroethylene copolymer (ETFE), fluorinated ethylene propylene (FEP), polytetrafluoroethylene (PTFE), polyester (PES), polyethylene terephthalate (PET) or also quartz glass. 
     The waveguide elements  110 ,  120  in  FIG. 1  each have a rectangular shape by way of example, but can also have an oval shape. The axis ratio (thus height to width) here is e.g. at least 1 to 1.4 to 4 (thus maximally 4 times wider than high). This axis ratio can determine the preferred polarisation. 
     The respective waveguide elements  110 ,  120  can be surrounded by the dielectric medium  150  with a lower ε r . This dielectric medium  150  has a lower ε r  than that of the respective waveguide element  110 ,  120 , in order to form the waveguide. Foamed materials (thus mixtures of a gas and a plastic) are preferably used for this, PE, PP, ETFE, FEP, PTFE or also PES can be used here as a polymer. The plastics can be foamed in processing. The foaming can take place here due to a chemical or physical process. The gas bubbles can be smaller than Lambda/4 of a wavelength of a useful frequency of the cable  100  in this case. Another option for the dielectric medium  150  is a banding of expanded PTFE. With this a significantly lower ε r  than that of the respective waveguide elements  110 ,  120  can likewise be achieved. 
     The two waveguide elements  110 ,  120  (also termed wave-carrying elements or also transmission elements), which are rectangular in  FIG. 1 , are oriented differently in  FIG. 1 . For example, the two wave-carrying elements  110 ,  120  are twisted relative to one another by an angle of 90°, as shown by way of example in  FIG. 1 . This means in detail that the wide side of one element points to the narrow side of the other element and vice versa. This orientation can avoid mutual interference of the two waveguide elements  110 ,  120  in the cable. Polarised wave types can be injected into the rectangular (or oval) waveguide elements  110 ,  120 . These are characterised in that they are only capable of propagation in one position, e.g. in the width of one of the waveguide elements  110 ,  120 . Although the waves projecting into the dielectric medium  150  also intersect the other waveguide element  110 ,  120  twisted by 90° after a distance, they cannot propagate in the length therein, as the height of the waveguide element  110 ,  120 , does not match the frequency of the disruptive coupling 
     Further details and aspects are mentioned in connection with the exemplary embodiments described below. The exemplary embodiment shown in  FIG. 1  can have one or more optional additional features, which correspond to one or more aspects which are mentioned in connection with the proposed concept or one or more exemplary embodiments described below (e.g.  FIGS. 2-6 ). 
       FIG. 2  shows a schematic representation of a cable  200  with four waveguides, which are formed by a dielectric medium  150  and four waveguide elements  110 ,  120 ,  130 ,  140 . In addition to the elements and components of the cable  100  from  FIG. 1 , the cable  200  further has a third dielectric waveguide element  130 . According to the example from  FIG. 1 , the third dielectric waveguide element  130  is spaced at a distance from the first and second dielectric waveguide elements  110 ,  120 . The preferred polarisation direction of the first dielectric waveguide element  110  corresponds in the example from  FIG. 2  to a preferred polarisation direction of the third dielectric waveguide element  130 . In the case of only three waveguide elements  110 ,  120 ,  130 , the preferred polarisation directions of the first, second and third dielectric waveguide element  110 ,  120 ,  130  can each differ from one another by an angle of 60°. 
     The cable  200  further has a fourth dielectric waveguide element  140 . The fourth dielectric waveguide element  140  is spaced at a distance from the first, second and third dielectric waveguide elements  110 ,  120 ,  130  according to the example from  FIG. 2 . The preferred polarisation direction of the second dielectric waveguide element  120  corresponds in the example from  FIG. 2  to a preferred polarisation direction of the fourth dielectric waveguide element  140 . 
     Using several waveguides formed by the waveguide elements  110 ,  120 ,  130  and  140  and the dielectric medium  150  can provide a greater transmission rate and more throughput. At frequencies of over 100 GHz (without light), a higher bandwidth can likewise be provided. 
     A distance between the first and second waveguide element  110 ,  120 , and the second and third waveguide element  120 ,  130 , and the third and fourth waveguide element  130 ,  140  and also the fourth and first waveguide element  140 ,  110 , is identical hi the example from  FIG. 2 . This distance is termed value A. 
     A distance between the first and third waveguide element  110 ,  130  corresponds in the example from  FIG. 2  to a distance between the second and fourth waveguide element  120 ,  140 . This distance can be termed value B. 
     B can be √2*A. Even if the first and third waveguide element  110 ,  130  and the second and fourth waveguide element  120 ,  140  have the same preferred polarisation direction, a coupling to the respectively other waveguide element can be reduced by the greater distance (√2 times greater). 
     The respective distance between the waveguide elements can be determined starting out from a centre of a respective cross section of the waveguide elements in the same cross-sectional plane of the cable  200 . 
     In the case of a cable  200  with four waveguides  110 ,  120 ,  130 ,  140  inside the cable  200  (formed by four waveguide elements and a dielectric medium  150  around the same), the conditions are comparable with the case of a cable  200  with two waveguides (formed by two waveguide elements and a dielectric medium  150  around the same, see  FIG. 1 ). The directly adjacent waveguide elements can be rotated by 90° as shown in  FIG. 2 , diagonally opposed waveguide elements having an identical orientation. Since diagonally opposed waveguide elements have a spacing that is greater by √2, however, the crosstalk is attenuated even here thereby. 
     Further details and aspects are mentioned in connection with the exemplary embodiments described above or below. The exemplary embodiment shown in  FIG. 2  can have one or more optional additional features, which correspond to one or more aspects, which are mentioned in connection with the proposed concept or one or more exemplary embodiments described above (e,g.  FIG. 1 ) or below (e.g.  FIGS. 3-6 ). 
       FIG. 3  shows a schematic representation of a cable  300  with four waveguides in a second arrangement similar to  FIG. 2 , but with another orientation of the four waveguide elements  110 ,  120 ,  130 ,  140 . The dielectric medium  150  can have a sufficiently large diameter here to guarantee that the field components of the propagating mode in the lossy jacket material are negligible (if a jacket is used). The jacket structure to be recognised in the illustration is used here to protect against environmental influences (dirt, water and other environmental influences). 
     Further details and aspects are mentioned in connection with the exemplary embodiments described above or below. The exemplary embodiment shown in  FIG. 3  can have one or more optional additional features, which correspond to one or more aspects, which are mentioned in connection with the proposed concept or one or more exemplary embodiments described above (e.g.  FIGS. 1-2 ) or below (e.g.  FIGS. 4-6 ). 
       FIG. 4  shows a schematic representation of a method for manufacturing a cable. The method comprises provision S 410  of a first and second dielectric waveguide element. The first and second dielectric waveguide element are spaced at a distance from one another. The first dielectric waveguide element is twisted by comparison with the second dielectric waveguide element, so that a preferred polarisation direction of the first dielectric waveguide element differs from a preferred polarisation direction of the second dielectric waveguide element in the cable. The method can further comprise embedding S 420  of the first and second dielectric waveguide element in a chamber made of a dielectric medium. 
     In addition, the method can comprise the separate embedding of the first and second (as well as third and fourth) dielectric waveguide elements in segments of the dielectric medium. Furthermore, the method can comprise stranding of the first and second (as well as third and fourth) dielectric waveguide elements embedded in this way to form a waveguide with two (four) waveguides. Sheathing can take place as a separate step to join the stranded elements together to form the cable. 
     Further details and aspects are mentioned in connection with the exemplary embodiments described above or below. The exemplary embodiment shown in  FIG. 4  can have one or more optional additional features, which correspond to one or more aspects, which are mentioned in connection with the proposed concept or one or more exemplary embodiments described above (e.g.  FIGS. 1-3 ) or below (e.g.  FIGS. 5-6 ). 
       FIG. 5 a    shows an S-parameter result for a cable with two waveguides. Curve  5   a   1  describes the insertion loss (IL). Curve  5   a   2  describes the near end crosstalk (NEXT), Curve  5   a   3  describes the far end crosstalk (FEXT). 
       FIG. 5 b    shows an S-parameter result for a cable with four waveguides according to the first arrangement. Here the three FEXT curves  5   b   1 ,  5   b   2  and  5   b   3  are shown in  FIG. 5 b   , which result by measurement during supplying of one of the waveguide elements. 
       FIG. 5 c    shows an S-parameter result for a cable with four waveguides according to the first arrangement Here the three NEXT curves  5   c   1 ,  5   c   2  and  5   c   3  are shown in  FIG. 5 c   , which result by measurement during supplying of one of the waveguide elements. 
       FIG. 5 d    shows an S-parameter result for a cable with four waveguides according to  FIG. 2 . The insertion loss is provided in  FIG. 5 d    by  5   d   1 . The FEXT curve  5   b   1  further corresponds to the FEXT curve  5   d   3 . The NEXT curve  5   c   1  also corresponds to the NEXT curve  5   d   2 . 
       FIG. 6  shows a schematic representation of a cable  600  with four waveguides  110 ,  120 ,  130 ,  140  each surrounded by a separate part of a dielectric medium  150 . The chamber in the example from  FIG. 6  comprises several segments of the dielectric medium  150 , as described above. In this case the dielectric medium  150  is divided into several segments. Each segment of the dielectric medium  150  encloses/surrounds one of the (first/second/third/fourth) waveguide elements  110 ,  120 ,  130 ,  140  separately (in the chamber) in the example from  FIG. 6 . The segments can be in mutual contact. The segments can each likewise contact the jacket  160 . 
     If great mechanical loads act on the cable  600 , it can be advantageous to strand the waveguides (formed by a respective segment of the dielectric medium and a corresponding waveguide element  110 ,  120 ,  130 ,  140 ). Here each waveguide element  110 ,  120 ,  130 ,  140  can be fabricated together with the dielectric medium  150  as a separate (individual) waveguide of the cable  600 . Several individual waveguides of the cable  500  can then be stranded with one another. Stranding with reverse twist can be used in this case. It is thereby guaranteed that the orientations of the waveguides and also of the corresponding waveguide elements  110 ,  120 ,  130 ,  140  are not displaced to one another. 
     Moreover, a torsion of the transmission elements  110 ,  120 ,  130 ,  140  negatively affecting the transmission properties can be avoided. It is not absolutely necessary here, however, that the dielectric medium  150  has a round outer contour. A roughly rectangular contour has advantages in the assignment to one another here. This is because round surfaces easily twist in relation to one another, while faces brace one another. A continuation consists in a segmented outer form of the individual components. 
     Further details and aspects are mentioned in connection with the exemplary embodiments described above. The exemplary embodiment shown in  FIG. 6  can have one or more option&amp; additional features, which correspond to one or more aspects, which are mentioned in connection with the proposed concept or one or more exemplary embodiments described above (e.g.  FIGS. 1-5 ). 
     According to one or more of the aforesaid aspects, a cable optimised for crosstalk can be provided with two or four waveguides in a common jacket. The waveguide elements contained in the cable can each have a rectangular or oval cross section (height to width ratio between 1:1.4 to 4). The dielectric medium  150  used in the cable can be one part (common element for all waveguide elements) or a plurality of parts. Each part can then surround a respective waveguide element separately. The parts surrounding the corresponding waveguide elements can then be stranded with one another, e.g, with reverse twist during production, to retain the orientation. These individual parts can have a rectangular or segmented cross section. 
     The cable described above can have the following advantages. A dielectric waveguide can be very light and flexible. It does not break, for example, even in the event of maximum reverse bending demands. In addition, a transmission frequency can be extremely high, e.g. in the range of 100 GHz to 150 GHz, or also over 50 GHz, over 70 GHz, over 90 GHz, over 100 GHz, over 120 GHz, over 130 GHz or over 140 GHz. An extremely large data bandwidth can be provided thereby. Moreover, it can be made possible with the structure described to double or quadruple the transmissible bandwidth with respect to a structure with only one. transmission element without channels significantly influencing one another. 
     Furthermore, cables of this kind have the advantage of being able to carry no current. Since no conductor is present, therefore, there cannot be any sparks either. A damage risk can be reduced and electromagnetic compatibility improved by this. 
     The aspects and features that were mentioned and described together with one or more of the examples and figures described in detail above can further be combined with one or more of the other examples to replace a similar feature of the other example or to introduce the feature additionally into the other example. 
     The present disclosure is not limited in any way to the embodiments described previously. On the contrary, many opportunities for modifications thereto are evident to an average expert without departing from the fundamental idea of the present disclosure as defined in the enclosed claims.