A SYSTEM FOR A COAXIAL TO STRIPLINE CONNECTION

Description

BACKGROUND OF THE INVENTION

Field of the invention

[0001] The present invention relates to a system for a coaxial to stripline connection. A coaxial cable comprises: an outer insulating jacket, a conducting shield generally made of a braid, a dielectric layer, and an inner conductor. A stripline is a radiofrequency transmission line that comprises an inner conductor and two parallel ground planes. The inner conductor of a stripline is a flat strip of metal which is placed in between the two parallel ground planes. The flat strip of metal is separated of both ground planes by two dielectric layers. The invention more peculiarly concerns the striplines wherein the dielectric layer is air.

[0002] Connecting a coaxial cable to a stripline implies:

• connecting the shield of the coaxial cable to both ground planes of the stripline;
• and connecting the inner conductor of the coaxial cable to the inner conductor of the stripline.

[0003] For instance, the system according to the invention can be used in a wireless network base station. A base station antenna is built with at least one array of radiating elements, connected to a feeding network (power dividers and phase shifters) by means of striplines wherein the dielectric layers are air.
The market of wireless network base stations requires more and more complex antennas: Dual polarization, multiband (pentaband or more), and multi-input-multi-output (MIMO) arrays of radiating elements. In very complex antennas, each radiating element comprises a short line that is generally connected to a stripline of a feeding network by means of a coaxial cable, because it is almost impossible to obtain satisfactory Passive Inter Modulation (PIM) performances if several striplines or printed circuit board microstriplines are interleaved for constructing the feeding network.

[0004] The most efficient feeding network technology is stripline, and preferably air stripline, as air is the minimum loss and cheapest dielectric available. So there are many coaxial to stripline connections in an antenna of a base station.
The inner conductor of a stripline and the inner conductor of a coaxial cable are generally made of a copper alloy, so there is no problem to connect them by means of tin solder.
The shield of a coaxial cable is often made of copper alloy that can be tin soldered. But the subcomponents of an antenna, in particular the two ground planes of a stripline, are made of materials that cannot be tin soldered (For instance, aluminum alloys that are much cheaper than copper alloys). So the shield and a ground plane cannot be connected by means of tin solder. So another kind of junction is needed to connect a ground plane of a stripline and the shield of a coaxial cable.

[0005] A first problem to be solved for this junction is to obtain satisfactory PIM performances.
A second problem to be solved is to obtain a very low manufacturing cost because, in such a complex antenna, there are a lot of these connections. For example, in a pentaband antenna, there are more than one hundred such coaxial cable to stripline connections.

Description of the prior art

[0006] There are two known families of solutions for connecting a coaxial cable to a stripline:

1. Manufacturing the ground planes of the stripline with a conductive material on which the shield of a coaxial cable can be soldered: Brass or copper. Provided that a good soldering process is used, the PIM performances are good, but the cost of the material is a problem. Huge brass or copper plates are necessary, and these materials are expensive (Three times more than the aluminum cost), and there is a regular increase of the cost for copper and copper alloys.

2. Manufacturing the ground planes of the stripline with a conductive material that cannot be soldered, for example aluminum. In this case, a grounding interface part is soldered on the shield of the coaxial cable, and this grounding interface part is then placed between the two ground plates of the strip line, and is tightened to both of these ground plates with one or two screws. It must be made from hard material because a hard material avoids collapsing during the screw tightening operation, which would generate PIM immediately. So it is not possible to use a material that can be easily molded, although molding technologies are cheaper than high quality machining. For example zamac is too smooth, and would collapse and generate PIM when tightening the screw(s) in order to reach the necessary contact pressure. Unfortunately the known grounding interface parts have complex shapes. Since molding is not possible, the known grounding interface parts need a high quality machining that is expensive.

[0007] Furthermore prior art document JPS4868789U discloses a system for connecting a shield 172 of a coaxial cable 16 to a ground plane 11; and prior art documents US2015/311605A1 and US2014/011399A1 present other systems to connect the shield of a coaxial cable to ground planes. In US2015/311605A1 the shield 22 of a coaxial cable is connected to a ground track 38 through a middle plate 56. In US2014/011399A1 a solder 601 is used to electrically connect a shield of a coaxial cable 102 to a ground plane 101.

[0008] Thus, there is a need to provide a less expensive solution for connecting a coaxial cable to a strip line.

SUMMARY OF THE INVENTION

[0009] The object of the invention is a system comprising a coaxial cable (CO) and a first and second ground planes (GP1, GP2), for connecting the shield of the coaxial cable to a first ground plane of a stripline, this system further comprising a grounding interface part, a solder, and tightening means; said grounding interface part comprising a first area that can be soldered to the shield of the coaxial cable by means of said solder, a second area and a third area that can be respectively pressed onto the first and second ground planes by the tightening means so that the second area is in electrical contact with the first ground plane and the third area is in electrical contact with the second ground plane;
characterized in that:

• said grounding interface part comprises a cylindrical conductive tube such that:

  -- the first area of said grounding interface part comprises the outer cylindrical surface of the cylindrical conductive tube, this outer cylindrical surface being soldered to the shield of the coaxial cable so that the axis of revolution of the cylindrical conductive tube is orthogonal to the longitudinal axis of the coaxial cable;

  -- the second area of said grounding interface part comprises a first end of the cylindrical conductive tube, this first end being plane and orthogonal to the axis of revolution of said conductive cylindrical tube;

  -- the third area comprises a second end of the cylindrical conductive tube, this second end being plane and orthogonal to the axis of revolution of said cylindrical conductive tube;

• said grounding interface part further comprises a cylindrical centering tube closely fitting into the cylindrical conductive tube and having a length lower than or equal to the length of the cylindrical conductive tube;
• the tightening means comprise:

  -- a threaded rod closely fitting into the centering cylindrical tube, this threaded rod having a length greater than the length of the cylindrical conductive tube,

  -- and at least one bolt that is screwed on said treaded rod.

[0010] The main part of the grounding interface part is the cylindrical conductive tube. This cylindrical conductive tube must be made from hard material. The hard material avoids collapsing during the screw tightening operation, which would generate PIM immediately. The advantage of a cylindrical conductive tube with respect to the second family of known solutions, is that the simplicity of the cylindrical shape allows low manufacturing cost, since the cylindrical conductive tube can be manufactured by a mere cutting operation of a standard pipe.

[0011] The centering tube can be made of cheap molded plastic. Thus the grounding interface part comprises very few parts and they are cheap, while providing the pressure needed for a good contact, i. e. preventing the creation of PIM.

[0012] Other features and advantages of the present invention will become more apparent from the following detailed description of embodiments of the present invention, when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to illustrate in detail features and advantages of embodiments of the present invention, the following description will be with reference to the accompanying drawings. If possible, like or similar reference numerals designate the same or similar components throughout the figures thereof and description, in which:

• Figure 1 represents a first view of a first embodiment of the system according to the invention.
• Figure 2 represents a second view of this first embodiment.
• Figure 3 represents only the threaded rod and the dielectric cylindrical tube of this first embodiment.
• Figure 4 represents a perspective view of a second embodiment further comprising a cable guide.
• Figures 5 and 6 represent two perspective views of the cable guide used in the second embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] On Figures 1 and 2, a first embodiment of the system according to the invention is connecting the shield SH of a coaxial cable CO to the two parallel ground planes of a stripline. For the sake of clarity, only one ground plane GP1 is represented on Figures 1-3.
The coaxial cable CO comprises:

• an outer insulating jacket J,
• a conducting shield SH that is a braid made of a material that can be tin soldered: copper or copper alloy for instance, and that is stripped on a length sufficient for soldering the braid on the grounding interface without damaging the plastic jacket.
• a dielectric layer DL that is stripped on appropriate length to keep the correct impedance for the connection (generally the cable nominal impedance).
• an inner conductor IC1 that is made of a material that can be tin soldered: copper or copper alloy for instance, and that is stripped on a length sufficient to permit a good soldering on the inner conductor (not represented) of the stripline.

[0015] This first embodiment of the system according to claim 1 comprises a grounding interface part GIP that is soldered to the shield SH by a tin solder TS, and that is pressed onto both ground plates by tightening means comprising a thread rod TR. In this example, the threaded rod TR is a stud welded to the ground plane GP1 (It could be a bolt or a screw as well), and a skirt nut (not represented on Figures 1-3) screwed onto of the threaded rod TR and pressing on the second ground plate (not represented).
The grounding interface part GIP comprises:

• A cylindrical conductive tube T1 made of a material that can be tin soldered (Copper or copper alloy for instance) and that has sufficient hardness to avoid collapsing of the grounding interface part GIP during the tightening operation. The cylindrical conductive tube T1 comprises:

  -- An external cylindrical surface A1 that is soldered, by a tin solder TS, to the shield SH of the coaxial cable CO, in a position such that the axis of revolution AA of the cylindrical conductive tube T1 is orthogonal to the longitudinal axis BB of the coaxial cable CO; and so that the inner conductor IC1 of the coaxial cable CO is at a predetermined distance with respect to the ground plane GP1. This distance is chosen so that the inner conductor IC1 of the coaxial cable CO will be at an appropriate distance for being soldered to the inner conductor of the stripline.

  -- Two plane ends A2 and A3, orthogonal to the axis of revolution AA of the cylindrical conductive tube T1. The plane end A2 will be pressed against the ground plane GP1. The ground plane A3 will be pressed onto the second ground plane (not represented) by the skirt nut that will be screwed, above the second ground plate, on the threaded rod TR of the stud.

  -- A cylindrical centering tube T2, preferably made of a dielectric material, closely fitting inside the cylindrical conductive tube T1 and having a length lower than or equal to the length of the cylindrical conductive tube T1. The threaded rod TR is closely fitting into the dielectric cylindrical tube T2, and this threaded rod TR having a length greater than the length of the cylindrical conductive tube T1. This cylindrical centering tube T2 maintains the revolution axis of the threaded rod TR in coincidence with the revolution axis AA of the cylindrical conductive tube T1.

[0016] The manufacturing of this first embodiment comprises the following operations:
For instance, the cylindrical conductive tube T1 can be portion of a standard tube (for example a standard brass tube 6 x 8 mm). The machining process is reduced to cutting the tube (this is a low cost operation).
The braid constituting the shield SH is directly soldered on the side of the cylindrical conductive tube T1 at a well defined position, by means of positioning tool. The soldering operation can be automated (with an induction soldering machine) to reduce the process cost.
Then the centering tube T2 is inserted around the threaded rod TR: Its action will be to ensure that the contact is uniformly done on a clean and flat surface of the ground plates and not on the side of the hole, which would generate immediately PIM. It can be made from any kind of plastic, by a molding operation, so the cost is extremely low.
Figure 3 only represents the threaded rod TR and the dielectric cylindrical tube T2 of this first embodiment, after the dielectric cylindrical tube T2 has been slip on the threaded rod TR, and before the cylindrical conductive tube T1 (soldered to the shield SH) has been slip on the cylindrical centering tube T2.
Then the cylindrical conductive tube T1, soldered to the shield SH, is inserted around the centering tube T2.
Then the second ground plate (not represented on the figures 1-3) will be placed in front of the first ground plate GP1, and the threaded rod TR will be traversing the second ground plate, so that the cylindrical conductive tube T1 will be pressed between the two ground plates when a skirt nut is screwed on the threaded rod TR. The cylindrical conductive tube T1 will constitute a spacer that defines the width between the two ground plates.

[0017] Figure 4 represents a perspective view of a second embodiment further comprising a cable guide CG. It shows a stripline SL comprising:

• An inner conductor IC2, the end of which is tin soldered to the inner conductor IC1 of a coaxial cable CO.
• Two parallel ground plates GP1, GP2, each one having the shape of a flat U. They are face to face so that they almost constitute a tube, having a rectangular section. Each side wall of the ground plate GP1 is almost in contact with the corresponding side wall of the ground plate GP2. They are only separated by a narrow slot ST1 non one side, respectively ST2 on the other side. The end of the inner conductor IC2 makes an angle of about thirty degrees with the longitudinal axis of both ground plates GP1, GP2.

[0018] This second embodiment comprises a grounding interface part GIP similar to the one that has been described with reference to Figures 1-3. It is installed between the two ground plates GP1 and GP2. The cylindrical conductive tube of this grounding interface GIP constitutes a spacer between the parallel ground plates GP1, GP2 and is in electrical contact with both of them. This cylindrical conductive tube has been tin soldered to the shield SH of the coaxial cable CO, as explained with reference to the Figures 1-3.

[0019] This second embodiment further comprises a cable guide CG that guides the coaxial cable CO while traversing a side wall of the ground plate GP2, through a rectangular opening O. This cable guide CG holds the coaxial cable CO with an angle of about thirty degrees with respect to the longitudinal axis of the two ground plates GP1, GP2, so that it aligned with the end of the inner conductor IC2 of the stripline SL.
A first benefit of this coaxial cable guide CG is to avoid a rotation of the coaxial cable CO and of the cylindrical conductive tube T1 of the grounding interface GIP, around the threaded rod TR, during the soldering operation of the inner conductor IC1 of the coaxial cable CO at the end of the inner conductor IC2 of the stripline SL.
A second benefit is to maintain the inner conductor IC2 of the stripline SL at the right distance between the two ground plates GP1 and GP2, thus avoiding the need of a specific tool during assembly process. The result is a quicker and more reliable assembly process.
A third benefit is also to protect the jacket J and the shield SH of the coaxial cable CO against a damaging by the edges of the ground plates GP1, GP2, in the opening O.

[0020] Figures 5 and 6 represent two perspective views of the cable guide CG used in the second embodiment. It is made of a molded plastic material, and it comprises a plane base B that lies on the inner face of the grounding plate GP1. It comprises a through hole H having a diameter slightly greater than the diameter of the cylindrical conductive tube T1 of the grounding interface part GIP. This through hole H enables to insert the cable guide CG around the grounding interface part GIP, before soldering the inner conductors IC1 and IC2 together. The base plane B also comprises two teeth T1 and T2 that are destinated to be snapped into two corresponding holes (Not represented) in the inner face of the grounding plate GP1. These teeth T1 and T2 prevent any rotation of the cable guide CG around the grounding interface part GIP.

[0021] An edge of the base B comprises a part S that is thicker than the rest of the plane base B. This part S is U shaped because it comprises a notch N, such that the bottom of the notch has a thickness lower or equal to the width of the slot ST1, and its width is slightly greater that the thickness of a side wall of the ground plate GP2. When the cable guide CG is installed in the stripline SL, the U shaped part S straddles the side wall SW2 of the ground plate GP2.
The U shaped part S comprises a second notch at an angle of thirty degrees with the first notch N. This second notch creates a pit P1 on one side of the notch N, and a second pit P2 on the other side of the notch N. These two pits P1 and P2 create a passage way through the U shaped part S, for the coaxial cable CO. This passage way guides the coaxial cable CO.

[0022] These two embodiments provide the following advantages:

• The cylindrical conductive tube T1 of the grounding interface part GIP must be made from an alloy with sufficient hardness to avoid collapsing of the part at tightening operation. However this part is manufactured very cheaply by simple cutting operation of a standard pipe.
• The centering tube T2 can be made of cheap molded plastic.

[0023] So the grounding interface part GIP comprises very few parts and they are cheap. However a single screw or stud, with a nut, is enough for providing the pressure needed for a good contact, i. e. preventing the creation of PIM.

[0024] The system according to the invention has been described in the context of a wireless base station, but this system can be used in any kind of device comprising coaxial cables connected to striplines, in any frequency band.

Claims

1. A system comprising a coaxial cable (CO) and a first and second ground planes (GP1, GP2), for connecting the shield (SH) of the coaxial cable (CO) to the first and second ground planes (GP1, GP2) of a stripline (SL), this system further comprising a grounding interface part (GIP), a solder (TS), and tightening means (TR, NT); said grounding interface part (GIP) comprising a first area (A1) that can be soldered to the shield (SH) of the coaxial cable by means of said solder (TS), a second area (A2) and a third area (A3) that can be respectively pressed onto the first and second ground planes (GP1, GP2) by the tightening means (TR, NT) so that the second area (A2) is in electrical contact with the first ground plane (GP1) and the third area (A3) is in electrical contact with the second ground plane (GP2);
characterized in that:

- said grounding interface part (GIP) comprises a cylindrical conductive tube (T1) such that:

-- the first area (A1) of said grounding interface part (GIP) comprises the outer cylindrical surface of the cylindrical conductive tube (T1), this outer cylindrical surface being soldered to the shield (SH) of the coaxial cable (CO) so that the axis of revolution (AA) of the cylindrical conductive tube (T1) is orthogonal to the longitudinal axis (BB) of the coaxial cable (CO);

-- the second area (A2) of said grounding interface part (GIP) comprises a first end of the cylindrical conductive tube (T1), this first end being plane and orthogonal to the axis of revolution (AA) of said conductive cylindrical tube (T1);

-- the third area (A3) comprises a second end of the cylindrical conductive tube (T1), this second end being plane and orthogonal to the axis of revolution (AA) of said cylindrical conductive tube;

- said grounding interface part (GIP) further comprises a cylindrical centering tube (T2) closely fitting into the cylindrical conductive tube (T1) and having a length lower than or equal to the length of the cylindrical conductive tube (T1);

- the tightening means comprise:

-- a threaded rod (TR) closely fitting into the centering cylindrical tube (T2), this threaded rod having a length greater than the length of the cylindrical conductive tube (T1),

-- and at least one bolt (BT) that is screwed on said treaded rod (TR).

2. A system according to claim 1 further comprising a cable guide (CG) for guiding the coaxial cable (CO) while traversing a side wall (SW2) of a ground plates (GP2) of said stripline (SL), through an opening (O), this cable guide (CG) holding the coaxial cable (CO) with a fixed angle with respect to the longitudinal axis of the two ground plates (GP1, GP2), so that it avoids a rotation of the coaxial cable (CO) around the grounding interface (GIP), and holds the coaxial cable (CO) at a predetermined distance between the two ground plates (GP1, GP2) of the stripline (SL).

Ansprüche

1. System, umfassend ein Koaxialkabel (CO) und eine erste und eine zweite Grundplatte (GP1, GP2) zum Verbinden der Abschirmung (SH) des Koaxialkabels (CO) mit der ersten und der zweiten Grundplatte (GP1, GP2) einer Streifenleitung (SL), wobei dieses System weiterhin umfasst ein Erdungsschnittstellenteil (GIP), Lötmetall (TS) und Befestigungsmittel (TR, NT); wobei besagtes Erdungsschnittstellenteil (GIP) einen ersten Bereich (A1) umfasst, der mit der Abschirmung (SH) des Koaxialkabels verlötet werden kann mittels besagten Lötmetalls (TS), und einen zweiten Bereich (A2) und einen dritten Bereich (A3), die jeweils auf die erste und zweite Grundplatte (GP1, GP2) gedrückt werden können mittels der Befestigungsmittel (TR, NT), sodass sich der zweite Bereich (A2) in elektrischem Kontakt mit der ersten Grundplatte (GP1) befindet und der dritte Bereich (A3) sich in elektrischem Kontakt befindet mit der zweiten Grundplatte (GP2); dadurch gekennzeichnet, dass:

- besagter Erdungsschnittstellenteil (GIP) ein zylindrisches leitendes Rohr (T1) umfasst, sodass:

- der erste Bereich (A1) von besagtem Erdungsschnittstellenteil (GIP) die äußere zylindrische Oberfläche des zylindrischen leitenden Rohres (T1) umfasst, wobei diese äußere zylindrische Oberfläche mit der Abschirmung (SH) des Koalxialkabels (CO) verlötet ist, sodass die Drehachse (AA) des zylindrischen leitenden Rohres (T1) orthogonal zur Längsachse (BB) des Koaxialkabels (CO) steht;

- der zweite Bereich (A2) von besagtem Erdungsschnittstellenteil (GIP) ein erstes Ende des zylindrischen leitenden Rohres (T1) umfasst, wobei dieses erste Ende plan ist und orthogonal zur Drehachse (AA) besagten leitenden zylindrischen Rohres (T1) steht;

- der dritte Bereich (A3) ein zweites Ende des zylindrischen leitenden Rohres (T1) umfasst, wobei diese zweite Ende plan ist und orthogonal zur Drehachse (AA) besagten zylindrischen leitenden Rohres steht;

- besagtes Erdungsschnittstellenteil (GIP) weiterhin umfasst ein zylindrisches Zentrierrohr (T2), das eng im zylindrischen leitenden Rohr (T1) anliegt und eine geringere oder gleiche Länge aufweist wie die Länge des zylindrischen leitenden Rohres (T1);

- die Befestigungsmittel umfassen:

- eine Gewindestange (TR) eng in dem zylindrischen Zentrierrohr (T2) anliegt, wobei diese Gewindestange eine größere Länge aufweist als die Länge des zylindrischen leitenden Rohres (T1),

- und mindestens einen Bolzen (BT), der auf besagte Gewindestange (TR) geschraubt ist.

2. System nach Anspruch 1, weiterhin umfassend eine Kabelführung (CG) zum Führen des Koaxialkabels (CO), während es eine Seitenwand (SW2) einer Grundplatte (GP2) besagter Streifenleitung (SL) durchläuft, durch eine Öffnung (O), wobei dieses Kabelführung (CG) das Koaxialkabel (CO) in einem festen Winkel in Bezug auf die Längsachse der zwei Grundplatten (GP1, GP2) hält, sodass er eine Rotation des Koaxialkabels (CO) um die Erdungsschnittstelle (GIP) verhindert und das Koaxialkabel (CO) in einem vorbestimmten Abstand zwischen den zwei Grundplatten (GP1, GP2) der Streifenleitung (SL) hält.

Revendications

1. Système comprenant un câble coaxial (CO) et un premier et un deuxième plan de masse (GP1, GP2), destiné à connecter le blindage (SH) du câble coaxial (CO) aux premier et deuxième plans de masse (GP1, GP2) d'une ligne à ruban (SL), ce système comprenant en outre une partie d'interface de mise à la masse (GIP), une brasure (TS), et des moyens de serrage (TR, NT) ; ladite partie d'interface de mise à la masse (GIP) comprenant une première zone (A1) qui peut être soudée au blindage (SH) du câble coaxial au moyen de ladite brasure (TS), une deuxième zone (A2) et une troisième zone (A3) qui peuvent être respectivement pressées contre le premier et le deuxième plan de masse (GP1, GP2) par les moyens de serrage (TR, NT) de sorte que la deuxième zone (A2) soit en contact électrique avec le premier plan de masse (GP1) et que la troisième zone (A3) soit en contact électrique avec le deuxième plan de masse (GP2) ;
caractérisé en ce que :

- ladite partie d'interface de mise à la masse (GIP) comprend un tube conducteur cylindrique (T1) de sorte que :

- la première zone (A1) de ladite partie d'interface de mise à la masse (GIP) comprend la surface cylindrique extérieure du tube conducteur cylindrique (T1), cette surface cylindrique extérieure étant soudée au blindage (SH) du câble coaxial (CO) de sorte que l'axe de révolution (AA) du tube conducteur cylindrique (T1) soit orthogonal à l'axe longitudinal (BB) du câble coaxial (CO) ;

- la deuxième zone (A2) de ladite partie d'interface de mise à la masse (GIP) comprend une première extrémité du tube conducteur cylindrique (T1), cette première extrémité étant plane et orthogonale à l'axe de révolution (AA) dudit tube conducteur cylindrique (T1) ;

- la troisième zone (A3) comprend une deuxième extrémité du tube conducteur cylindrique (T1), cette deuxième extrémité étant plane et orthogonale à l'axe de révolution (AA) dudit tube conducteur cylindrique ;

- ladite partie d'interface de mise à la masse (GIP) comprend en outre un tube de centrage cylindrique (T2) s'ajustant étroitement dans le tube conducteur cylindrique (T1) et présentant une longueur inférieure ou égale à la longueur du tube conducteur cylindrique (T1) ;

- les moyens de serrage comprennent :

- une tige filetée (TR) s'adaptant étroitement dans le tube de centrage cylindrique (T2), cette tige filetée présentant une longueur supérieure à la longueur du tube conducteur cylindrique (T1), et

- au moins un écrou (BT) qui est vissé sur ladite tige filetée (TR).

2. Système selon la revendication 1 comprenant en outre un guide-câble (CG) destiné à guider le câble coaxial (CO) lorsqu'il traverse une paroi latérale (SW2) d'un plan de masse (GP2) de ladite ligne à ruban (SL), via une ouverture (O), ce guide-câble (CG) maintenant le câble coaxial (CO) selon un angle fixe par rapport à l'axe longitudinal des deux plans de masse (GP1, GP2), de façon à éviter une rotation du câble coaxial (CO) autour de l'interface de mise à la masse (GIP) et maintient le câble coaxial (CO) à une distance prédéterminée entre les deux plans de masse (GP1, GP2) de la ligne à ruban (SL).

Drawing