High-frequency connector for a coaxial cable for transmitting high-frequency signals

Abstract

The invention relates to a high-frequency connector for a coaxial cable for transmitting high-frequency signals, comprising at least one metal cylindrical housing (1) in which is housed an insulating element (2) into which a connecting pin (3) is inserted, one end of which constitutes the connecting part of the connector onto another connector or onto an apparatus and the other end of which constitutes a part for connection to the conducting wire of the cable. The invention is characterised in that the insulating element (2) consists of a ceramic.

Description

Description Title of the invention: High-frequency connector for coaxial cable for transmitting high-frequency signals

[0001] The present invention relates to the field of cable connectors and in particular to a high-frequency connector of type N, SMA, HN and TNC for coaxial cables for transmitting high-frequency signals and more particularly mineral-insulated coaxial cables.

[0002] An N-type connector is designed to carry signals at frequencies up to 11 GHz, also up to 18 GHz (N-type) and, for SMA-type ones, even up to 65 GHz.

[0003] Such connectors thus make it possible to connect cables, in particular mineral-insulated cables allowing the transmission of high-frequency signals which are used in application areas such as the space sector, the power plant sector, and the military sector. These application areas may be subject to severe conditions of use, pressure, radiation and temperature, in particular severe temperature conditions which may exceed 500°C.

[0004] Mineral insulated armoured cables are coaxial cables consisting of a central metallic conductor and a hollow cylindrical metallic sheath surrounding said central conductor and between which is inserted a powdered refractory insulator such as mineral of the magnesia, alumina or silica type, the outer metallic sheath being made of stainless steel, copper or a nickel alloy such as that known under the trade name Inconel 600.

[0005] Such cables are particularly fire-resistant and used in places that can accommodate the public, such as shopping centers, airports, reception halls, or in industrial environments with risk areas such as military zones, space zones or areas with a high level of cleanliness (Semi-Conductor). They are used in particular in many areas of industry in which sensors, heating elements or electrical signal transmission cables are used which must withstand environments with increasingly severe conditions such as vacuum, pressure, temperature, cryogenics, radiation environment, humidity, etc.

[0006] Such cables are used to connect devices that are spaced apart from each other and it is therefore necessary to provide means of connecting these cables to the devices, or even cables between them.

[0007] Cable connector devices are extremely critical parts of these components since they must ensure the electrical continuity of the conductors, prevent the migration of humidity into the insulation while preserving the dielectric strength of the cable.

[0008] In practice this is often a weak point because it is sometimes difficult to combine all these qualities when you are in a very hot and humid environment.

[0009] When a mineral-insulated cable is stripped to install a connector device, the outer sheath and mineral insulation are removed to reveal the metallic conductor wire so that it can be connected to another component such as a glass-to-metal or ceramic-to-metal passage or feedthrough or any other suitable component forming a connector.

[0010] A connector of this type therefore constitutes a male connection part or a female connection part, comprising a sealed and hermetic feedthrough made of an insulator housed in a metal sheath.

[0011] These connectors comply with the applicable standards MIL-C-39012C / MIL-STD-202 / MIL-STD-348. . ., and typically have an impedance of 50 ohms.

[0012] When using this type of connector under standard temperature conditions, below 200°C, the insulation is preferably PTFE (PolyTetraFluoroEthylene). Such a connector is described in particular in document FR-A-2 700 223. Under higher temperature conditions, a hermetic glass-metal feedthrough is used which typically withstands 400°C.

[0013] This connector is composed of a housing in which is housed an insulating element made of PTFE. This connector comprises a housing, in which is housed an insulating element made of PTFE and in which is inserted the inner conductor of a cable, one end of which in the form of a socket constitutes the connection part on another connector and the other end of which constitutes a connection part with the conductive wire of the cable, the insulating element being made of PTFE.

[0014] As already mentioned, this type of connector requires exposing the cable's conductor wire, thus leaving the possibility of an electric arc forming during operation between the conductor and the shield (outer metal sheath). This risk is all the greater if the power cable operates under high voltage (for example, for a signal transmission cable connected to specific detectors). High voltages are then not applicable for a long time.

[0015] The invention therefore aims to propose a high-frequency connector for connecting signal transmission cables such as HF signals under severe usage conditions, ensuring good signal transmission without risk of signal degradation.

[0016] When transmitting high-frequency signals, it is crucial to ensure the integrity of the signals propagating through cables and connectors. Signals above 100 MHz are affected by the impedance of the circuit components, which, if not properly considered, can cause signal losses at the output of the transmission cable and therefore information losses through the cable.

[0017] When a signal passes from a conductor with a certain impedance to another with the same impedance, it is transmitted optimally without loss of the transmitted signal. On the other hand, if the impedances are different, reflections and attenuations occur which degrade the transmitted signal.

[0018] The impedance of a connector for a signal transmission cable concerned by the present invention is 50 Ohms, and depends on various factors such as the dielectric constant of certain elements within the connector.

[0019] It is therefore important to ensure that, for high frequency signals, a connector guarantees a target impedance value, with a certain tolerance.

[0020] The invention therefore aims to propose a high-frequency connector which has an identical impedance, of 50 ohms for example, along the entire length of said connector, i.e. without any area having a different impedance.

[0021] To this end, the invention relates to a high-frequency connector for a coaxial cable for transmitting high-frequency signals comprising at least one cylindrical metal housing in which is housed an insulating element in which is inserted a connection pin, one end of which constitutes the connection part of the connector to another connector or to a device and the other end of which constitutes a connection part with the conductive wire of the cable, the invention consisting in that the insulating element is made of a ceramic.

[0022] Thus, advantageously, insofar as the insulating element is a ceramic, this is preferably chosen so as to be able to exhibit good mechanical strength at temperatures above 500°C, and the high-frequency connector according to the invention can then be used in environments presenting severe, even extreme, conditions, in particular in terms of temperature conditions which can be above 500°C, even up to 1000°C, and this without alteration or loss of the transmitted signal.

[0023] According to a preferred embodiment, the insulating element is made of a material chosen from oxide or nitride type ceramics such as silicon carbide SiC, aluminum nitride AIN, boron nitride BN, silica SiO2, alumina A12O3, quartz. Preferably, the insulating element is in the form of a disc having a central orifice in which the pin is engaged.

[0024] The impedance of the connector according to the invention must be of a predetermined value, preferably 50 Ohms, the shape such as disc, tube and the dimensions of the insulating element are defined as a function of the dielectric permittivity of the material constituting said insulating element, the frequency of the signal to be transmitted and the temperature of the environment of use, greater than 500°C, so as to obtain an impedance of predetermined value, in this case 50 Q, in the connector.

[0025] Thus, the dimensions of the insulating element are preferably defined using a mathematical formula allowing, from the impedance, the internal and external diameters of said insulating element to be dimensioned according to the relative permittivity of the material and the desired impedance, this formula usually being applied for the definition of coaxial cables: in which: L represents the length and C the capacity of the connector, D being the internal inner diameter of the outer conductor and representing in this case the external diameter of the insulating element d being the external diameter of the inner conductor of the coaxial cable, in this case corresponding to the diameter of the hole for the connection pin to pass through in the insulating element; the units of D and d having to be identical, such that in meters c is the speed of light 299 792 458 ms' 1 So is the permittivity of vacuum of approximately 8.854187817620. . .xlO' 12 F / m 8 r is the relative permittivity of the insulating element.

[0026] Such sizing of the insulating element also has an impact on the cut-off frequency of the connector according to the formula:

[0027] D being the internal inner diameter of the outer conductor and representing in this case the external diameter of the insulating element, d being the external diameter of the inner conductor of the coaxial cable, in this case corresponding to the diameter of the hole for the connection pin to pass through in the insulating element; the units of D and d, which must be identical, are in meters Fc is the cutoff frequency in Hz sr is the relative pennitivity of the insulating element.

[0028] A connector according to the invention consists of either a male connection part or a female connection part. The interface between the male and female connectors according to the invention complies with the applicable standards (MIL-C-39012C / MIL-STD-202 / MIL-STD-348. . .) in order to be connectable also to connectors of the same type, namely SMA type, standard N type (low temperature) such as for example a male N type connector according to the invention with a female standard N type connector.

[0029] To this end, the connector according to the invention therefore comprises a cylindrical metal housing, mainly tubular in shape, the dimensions of which, and in particular the diameter, correspond to these standards.

[0030] As already mentioned, the shape and dimensions of the insulating element are defined as a function of the frequency of the transmitted signal and the operating temperature, to obtain an impedance of predetermined value such as 50 Q, taking into account the dielectric permittivity of the insulating element; the latter being an intrinsic characteristic of said material constituting the insulating element. These two parameters are integrated into the notion of relative permittivity of the material which varies as a function of frequency and temperature. The frequency and temperature to be considered are those of the intended final application. The sizing of the connector is, for example, different for an application at 1 GHz / 20°C and 50 GHz / 400°C.

[0031] Thus, the insulating element may be in particular in the form of a disc whose external diameter is greater than the internal diameter of the cylindrical metal casing, said casing then comprising a receiving housing adapted to said insulating element.

[0032] In order not to modify the connector, which must remain compliant with the standards used, it is planned to offset the insulating element relative to the connection end of the connector. Thus, the insulating element of the connector according to the invention is preferably positioned substantially in the center of the cylindrical housing between the "standard" ends of the connector.

[0033] Thus, a connection element such as a connection pin, preferably metallic, extends through the insulating element having a through-hole for this purpose, housed in the metal housing. Once the metal connection pin is engaged through the insulating element, the ends of the pin are arranged on either side of said insulating element, and allow for one the connection with the conductive wire of a coaxial cable for transmitting high-frequency signals and for the other the connection with another connector or device, according to standard standards.

[0034] The connection ends of the metal connection pin are therefore arranged on either side of said insulating element, and preferably spaced apart from said insulating element, to be able to be positioned in the end zones of the metal housing which allow for one the connection with the cable and for the other, the connection to another connector in compliance with the standards in force.

[0035] The connecting and connecting ends of the pin are therefore spaced apart from said insulating element and from the receiving housing provided in the housing, which creates a defined spacing zone between the insulating element and each end of the connecting pin, in said housing.

[0036] Thus, the connector according to the invention which incorporates a sealed ceramic / metal feedthrough, comprises a metal housing whose end parts are called "standard", namely that the dimensions of these housing ends allow on the one hand the connection with a connector of complementary standard dimensions according to the standards in force, and on the other hand the connection with a cable with high-frequency transmission insulation of also standard type. The metal housing of this connector according to the invention further comprises a part between said ends of the housing, this part defining a receiving housing for the insulating element, which may in particular be of dimensions different from the dimensions of the end parts of said housing.

[0037] Thus, if the insulating element is in the form of a disc with a diameter greater than the internal diameter of the housing, said housing comprises a receiving housing and the connection ends of the connection pin extend on either side of said insulating element, in a manner spaced from said insulating element, so that once the connection has been made on each end of the pin by the other connector and by the cable, a so-called spacing zone is created on each side of said insulating element.

[0038] The spacing area on the connection end side of the pin on a mineral insulated cable defines, between the insulating element and the end of the cable, preferably mineral insulated, a compartment which can advantageously be filled with an electrical insulating material such as a ceramic insulating material, a mineral insulator such as silica, a gas, for example helium, air, which makes it possible to guarantee a predetermined impedance value and as appropriate for a connector according to the invention, namely an impedance of 50 Ohms.

[0039] At the connection end of the pin on a mineral-insulated cable, the pin which has passed through the insulating element has a connection portion around which a sheath is attached to protect said connection portion and define a housing in which the stripped conductive wire of a cable can be accommodated to come into connection with the connection end of the pin, this sheath makes it possible to create the spacing zone between the insulating element and the end of the cable.

[0040] Preferably, the compartment comprises an insulating material, preferably a mineral insulation preferably identical to that constituting the mineral insulation of the cable. The dimensions of this compartment are defined by fixed parameters such as the internal diameter of the housing (fixed by the standard), and by variable parameters such as the length of the spacing zone, the diameter of the sheath to define an impedance of predetermined value, preferably 50 Q of the connector.

[0041] On the other hand, at the connection end to another connector or to a device, the spacer zone allows, during connection, to define an air-filled compartment, which makes it possible to guarantee a predetermined impedance value, for the high-frequency connector, namely a value of 50 Ohms.

[0042] In order to define this spacing zone, the connection pin has, between its connection end to another connector or a device and the insulating element, a portion of pin extending between said connection end and the insulating element, and thus defining in the metallic cylindrical housing, the spacing zone. This spacing zone around this portion of pin is filled with air during connection. The dimensions of this spacing zone are then defined by fixed parameters such as the internal diameter DC of the housing (fixed due to standards), the permittivity of the air contained in this spacing zone and the permittivity of the ceramic material used and by variable parameters such as the length and the diameter of the portion of pin, in order to obtain an impedance of predetermined value of 50Q.

[0043] The dimensions of the spacing zones (length) can thus vary depending on the ceramic used and its permittivity, these dimensions being able to be thousands, in particular, at the level of the spacing zones on the connection end side.

[0044] As already mentioned, according to a preferred embodiment, the insulating element is in the form of a disc with an external diameter greater than the internal diameter of the cylindrical metal housing, said cylindrical metal housing comprising a housing for receiving said insulating element.

[0045] According to a particularly preferred embodiment, the cylindrical metal housing is made up of two assembled housing parts, the junction end of these two housing parts being shaped to constitute the receiving housing which accommodates the insulating element.

[0046] Preferably, the end of a first part of the metallic cylindrical housing has a radially projecting collar provided with a rim delimiting the housing for receiving the insulating element, the end of the second part of the housing having a radially projecting collar which, coming to bear on the rim of the first part of the housing, thus forms a cover which closes the housing for receiving the insulating element.

[0047] Thus, the invention also relates to a mineral-insulated coaxial cable for transmitting high-frequency signals provided at least at one end with a high-frequency connector according to the invention.

[0048] The invention thus relates to a cable, in which the spacing zone, between the insulating element and the end of the mineral-insulated cable, defines a compartment filled with an insulating material such as a ceramic insulating material, a gas, the connection end to another connector or to a device, having a spacing zone which, during a connection, defines a compartment between this connection end and the insulating element, filled with air. These two spacing zones make it possible to guarantee a predetermined impedance value, for the high-frequency connector, namely a value of 50 Ohms, with connectors conforming to the standards. Depending on the insulating element used, it is therefore possible to have a length of these spacing zones which varies between 0 and a value L.

[0049] Thus, it is particularly easy to define a determined impedance of 50 ohms on these spacing zones by adjusting the length and diameter of the pin portion in relation to the dielectric permittivity of the air.

[0050] With such a structure, we obtain a connector which allows resistance to high temperatures while guaranteeing a homogeneous impedance across the entire connector. Thus, each zone of the connector is sized according to the insulation which composes it (air, ceramic, etc.) to obtain an impedance of 50 in each zone.

[0051] The cylindrical metal casing is made of a material suitable for use in corrosive environments and subject to high temperatures chosen from stainless steel such as those of references 304L, 316L, nickel under reference 200, 270, an iron / nickel alloy such as ferronickel, copper, and alloys of the type known under the trade name Inconel.

[0052] Preferably, the connection pin is made of a metallic material of low electrical resistivity, to limit losses by Joule effect, chosen from copper, as designated Cuc2, Cua, Cub (according to standard NFA 51050), stainless steel such as 304L / 316L, nickel 200 / 270, Fe / Ni alloys, alloys of the type known under the trade name Inconel.

[0053] The assembly of the insulating element, the metal housing and the metal pin is carried out by brazing, the type of brazing being chosen according to the predetermined thermal resistance of the connector. This brazing also makes it possible to provide the desired level of sealing and hermeticity. Such assemblies can be carried out by active brazing processes, by direct reactive brazing, by direct eutectic brazing or by diffusion or thermocompression welding.

[0054] Preferably, the connector thus obtained is watertight and hermetic and has a helium seal with a leak level of less than 3.10-8 atm.cm- 3 .s . The connectors according to the invention are designed to adapt specifically to mineral-insulated cables and advantageously make it possible to limit losses in terms of transmission of the transmitted signals as much as possible.

[0055] Preferably, the connection between the connector and the mineral-insulated cable is made by soldering or welding. The outer diameter of the cables is between 0.5 and 10 mm.

[0056] Consequently, the inner diameter of the cylindrical metal casing is chosen to be complementary.

[0057] The connector according to the invention can be advantageously used in many areas of industry with operating environments presenting increasingly severe temperature conditions.

[0058] The invention will now be described in more detail with reference to the drawing in which the figures represent:

[0059] [Fig. 1] a sectional view of a connector according to the invention of the male type;

[0060] [Fig. 2] an exploded perspective view of the connector according to Figure 1;

[0061] [Fig. 3] a sectional view of a connector according to the invention of the female type;

[0062] [Fig. 4] a sectional view of two connectors according to the invention before connection.

[0063] A connector according to the invention, of the male type, is shown in Figure 1 and comprises a cylindrical metal housing 1 consisting of two assembled housing parts 11, 12. This cylindrical metal housing 1 has an internal diameter DC corresponding to the external diameter of a mineral-insulated cable C which can be housed therein and fixed by soldering or welding. These dimensions comply with the standards applicable for this type of connector.

[0064] The joining end of the two housing parts 11, 12 is shaped to constitute a receiving housing 10 which accommodates an insulating element 2 such as a ceramic bushing.

[0065] The insulating element 2 is, in the example described, made of a material such as an alumina ceramic A12O3. The nature of the material constituting the insulator as well as its dimensioning (thickness) are chosen according to the frequency of the transmitted signal, the operating temperatures and the dielectric permittivity of said material in order to produce a connector having an impedance of 50 ohms.

[0066] Preferably, this insulating material provides helium sealing with a leakage level of less than 3.10-8atm.cm' 3 .s as well as mechanical resistance at high temperatures, i.e. above 500°C.

[0067] This insulating element or ceramic bushing 2 has the shape of a disc. Depending on the type of ceramic used, this disc has an external diameter DD which is greater than the internal diameter DC of the metallic cylindrical housing 1. Thus, the end of a first part 11 of the housing 1 has a radially projecting collar 111 provided with a rim 112 delimiting a receiving housing in which the disc constituting the insulating element 2 is housed, the end of the second part of the housing 12 has a radially projecting collar 121 which, bearing on the rim 112, thus forms a cover which closes the receiving housing 10 of the insulating element 2.

[0068] In order to promote the connection between the two housing parts 11, 12, the rim 112 and the rim of the collar 121 are of complementary shape, nestable and connected by welding, for example laser welding.

[0069] The housing 1 is made of an alloy of the type known under the commercial name Inconel or any other metallic material.

[0070] A metal connection pin 3 forming the central contact of the connector, extends through the insulating element 2 in a central passage orifice 21. It thus has on either side of the insulating element 2, a first end 31 of male type (in figure 1) or female type 310 (in figure 3) allowing connection to another connector of complementary type and a second end to form a connection portion 34 with the conductive wire FC of a cable C.

[0071] In addition, between the first connection end 31 and the insulating element, the pin has a pin portion 32 extending between said first end 31 and the insulating element 2, so that the first connection end 31 is spaced from the insulating element 2. The pin further has a pin portion 33 which passes through the insulating element 2 and projects from the opposite side of the insulating element 2 in the form of the connection portion 34.

[0072] The connection end 31 therefore extends into a first housing part 11 forming the connection end with another connector and the connection end 34 extends into the second housing part 12 in which the cable C is engaged. A sheath 4 is provided and surrounds the connection portion of the pin 34 to form a connection end of the connector with the cable.

[0073] The connection end 31 is a male type connection end in the form of a plug-in tip. The connection end may also be a female type connection end 310 in the form of a plug-in housing as seen in FIG. 3.

[0074] The metal connection pin 3 is fixed in the insulating element 2 by soldering and the insulating element 2 is itself fixed in the metal housing 1 by soldering as well. This soldering ensures a seal within the connector.

[0075] As already mentioned, the connection end of the pin 3 with the cable consists of the connection portion 34 surrounded by the sheath 4 defining a receiving housing 41 in which the stripped conductive wire FC of a mineral-insulated cable C can be engaged. This sheath 4 defines between the insulating element 2 and the end of the cable, i.e. the metal sheath and the mineral insulator, a spacing zone ZEC (delimited by dotted lines in FIG. 1) so that said end of the cable having the mineral insulator is kept spaced from the insulating element 2 by said spacing zone ZEC.

[0076] This spacing zone ZEC defines between the insulating element 2 and the end of the mineral-insulated cable, within the housing 1, a compartment into which an insulating material is introduced, preferably a mineral insulator, preferably identical to that constituting the mineral insulator of the cable. The dimensions of this spacing zone ZEC are defined by fixed parameters such as the internal diameter of the housing (fixed by the standard), and by variable parameters such as the diameter of the sheath 4 and the length of this spacing zone ZEC to define an impedance of 50 Q of the connector.

[0077] As can be seen in Figure 3, a connector according to the invention of the female type has a structure similar to that of the male type connector of Figure 1, except that the connection end 310 of the pin 3 has an axial bore in which the connection end 31 can be engaged in the form of a plug-in tip of a male type connector.

[0078] As seen above, between the connection end 31, 310 of the pin 3 and the insulating element 2 extends a portion of pin 32. The spacing zone ZEA (delimited by dotted lines) around this portion of pin 32 is filled with air during connection. The dimensions of this spacing zone ZEA are defined by fixed parameters such as the internal diameter DC of the package (fixed due to standards), the permittivity of the air contained in this spacing zone ZEA and the permittivity of the ceramic material used and variable parameters such as the length of the spacing zone and the diameter of the portion of pin 32, in order to obtain an impedance of 50Q.

[0079] The ceramic insulating element 2 is located in the center of the connector C thus formed. The geometry of the ceramic insulating element 2, namely its outer diameter, its inner diameter, diameter of the passage of the connection pin, are defined to obtain an impedance of 50Q, taking into account the dielectric permittivity of said insulating material. This geometry is defined using the formula, in which: L represents the length and C the capacity of the connector, D being the inner diameter of the outer conductor, representing in this case the outer diameter DD of the insulating element 2 d being the outer diameter of the inner conductor of the coaxial cable, in this case corresponding to the diameter of the central passage hole 21 for the passage of the connection pin 3 in the insulating element 2; c is the speed of light 299 792 458 ms' 1 So is the permittivity of vacuum of approximately 8.854187817620... xlO' 12 F / m 8 r is the relative permittivity of the insulating element.

[0080] The relative permittivity of the insulating material varies with frequency and temperature.

[0081] Thus, with alumina as the ceramic material used for the insulating element, we obtain for an impedance of Z0 = 50Q, an insulating element for which d= 1; DD=14 and 8r=10.

[0082] The connector further comprises fixing means such as a screw nut 5 suitable for cooperating with complementary fixing means provided on another connector. A seal 6, a washer 8, a nut ring 7 are also provided.

Claims

Claims 1. High frequency connector for coaxial cable for transmitting high frequency signals comprising at least one metallic cylindrical housing (1) in which is housed an insulating element (2) in which is inserted a connection pin (3), one end of which constitutes the connection part of the connector on another connector or on a device and the other end of which constitutes a connection part with the conductive wire of the cable, characterized in that the insulating element (2) is made of a ceramic.

2. Connector according to claim 1, characterized in that the insulating element (2) is a ceramic having good mechanical strength at temperatures above 500°C.

3. Connector according to claim 2, characterized in that the insulating element (2) is made of a material chosen from oxide or nitride type ceramics, such as aluminum nitride AIN, silica SiO2, alumina A12O3, boron nitride BN, quartz.

4. Connector according to one of claims 1 to 3, characterized in that the dimensions of the insulating element (2) are defined as a function of the dielectric permittivity of the material constituting said insulating element (2), the frequency of the signal to be transmitted and the temperature of the environment of use, so as to obtain an impedance of predetermined value in the connector.

5. Connector according to one of claims 1 to 4, characterized in that the connection pin (3) extends through the insulating element (2), the connection ends of the connection pin (3) being arranged on either side of the insulating element (2).

6. Connector according to claim 5, characterized in that the connection ends of the connection pin (3) are spaced apart from said insulating element (2), a spacing zone being defined between the insulating element (2) and each connection end of the connection pin (3).

7. Connector according to one of claims 1 to 6, characterized in that, at the connection end of the connection pin (3) on a cable, the connection pin (3) has a connection portion (34) around which a sheath (4) is attached to define a housing in which the stripped conductive wire (FC) of the cable (C) can be housed to come into connection abutment with the connection end of the pin (3).

8. Connector according to claim 7, characterized in that the spacing zone on the connection end side of the connection pin (3) on a cable, defines, between the insulating element (2) and the end of the cable, a compartment whose dimensions are defined by fixed parameters such as the internal diameter of the metallic cylindrical housing (1), and by variable parameters such as the diameter of the sheath and the length of the spacing zone to define an impedance of predetermined value.

9. Connector according to one of claims 1 to 8, characterized in that the spacing area on the connection end side of the connection pin (3) on a cable is filled with an electrical insulating material such as a ceramic insulating material, a mineral insulator such as silica, a gas, such as helium, air.

10. Connector according to one of claims 1 to 9, characterized in that in the spacing zone (ZEA), between the connection end to another connector or a device and the insulating element (2), extends a pin portion (3), this spacing zone (ZEA) being filled with air.

11. Connector according to claim 10, characterized in that the dimensions of this spacing zone (ZEA) are defined by fixed parameters such as the internal diameter DC of the metallic cylindrical housing (1), the permittivity of the air contained in this spacing zone (ZEA) and the permittivity of the ceramic material used for the insulating element (2) and by variable parameters such as the length and the diameter of the pin portion, in order to obtain a predetermined impedance.

12. Connector according to one of claims 1 to 11, characterized in that the insulating element (2) is in the form of a disc whose external diameter (DD) is greater than the internal diameter (DC) of the cylindrical metal housing (1), said cylindrical metal housing (1) comprising a receiving housing (10) adapted to said insulating element (2).

13. Connector according to one of claims 1 to 12, characterized in that the cylindrical metal housing (1) consists of two assembled housing parts (11, 12), the junction end of these two housing parts (11, 12) being shaped to constitute the receiving housing 10 which accommodates an insulating element (2).

14. Mineral insulated coaxial cable provided at one end with a high frequency connector according to one of claims 1 to 13, characterized in that the spacing zone, between the insulating element (2) and the end of the mineral insulated cable, defines a compartment filled with an insulating material such as a ceramic insulating material, a gas, the connection end to another cable or to an appliance, having a spacing zone which, during a connection, defines a compartment filled with air between this connection end and the insulating element (2).

Images