Coaxial connector

Abstract

The present disclosure relates to a coaxial connector (1) for connecting a coaxial cable (23). The coaxial connector (1) comprises an outer conductor (3) in form of a base element (4) which comprises a through hole (5) which extends along a longitudinal axis (x) from a first end (6) to a second end (7) of the base element 5 (4). The coaxial connector (1) further comprises a dielectric spacer (8) in form of a dielectric sleeve (9) which is arranged within the through hole (5) of the base element (4) and extends along the longitudinal axis (x). The coaxial connector (1) further comprises an inner conductor (10) in form a spring element (11) which is arranged within the dielectric sleeve (9) and extends along the longitudinal axis 10 (x) and comprises at least at a first end (12) and / or a second end (13) a contact element (14).

Description

[0001] Coaxial Connector

[0002] FIELD OF THE DISCLOSURE

[0003] The present disclosure relates to a coaxial connector with a spring contact, an array of coaxial connectors, a cable assembly, a coaxial connector assembly and a filter element.

[0004] BACKGROUND OF THE DISCLOSURE

[0005] US7556503B2 published on 07.07.2009 on behalf of Ardent Concepts Inc. relates to a compliant electrical contact and an assembly employing a plurality of the contacts that provides an interface between two electrical devices. The contact has a convoluted spring with convolutions and a contact point at each end.

[0006] US8926342B2 published on 06.01.2015 on behalf of Ardent Concepts Inc. relates to an apparatus for terminating a controlled-impedance cable using compliant electrical contacts to provide an interface to another device. The terminator includes a conductive ground block for securing the cable by its ground shield and providing a common ground. Once the cable is anchored in the ground block, the block face and cable ends are dressed to make a reliable electrical contact with the compliant signal contact that electrically connects the cable center conductor to the device.

[0007] US8926379B2 published on 06.01.2015 on behalf of Ardent Concepts Inc. relates to a compliant electrical contact and an assembly employing a plurality of the contacts. The contact has several embodiments, all of which include a spring with convolutions, a contact point at each end, and a shunt that is generally parallel to the spring and that spans the convolutions longitudinally.

[0008] SUMMARY OF THE DISCLOSURE

[0009] Multi line connectivity with a small form factor has become a growing need in applications where the number of radio frequency signal lines increases. There is especially an increased interest in multi line coaxial connectivity solutions. A possible field of application is in today’s quantum computer set-ups, where hundreds or even thousands of coaxial lines are needed to control the qubits in a cryogenic environment. Quantum computers typically operate in cryogenic environments where interface signals need to be routed through a cascade of multiple temperature levels. The cooling power at the lowest temperature stage where the quantum processor is located is limited to cooling power of some milliwatts and so have to operate with significantly less energy, compared to so called “supercomputers”, which typically comprise a large number of individual processors that can access shared peripherals and a partially shared main memory.

[0010] Modem quantum computers comprise processors which are typically built around a single wafer not much larger than that of a laptop. The hardware system of a quantum computer is about the size of a car and consists mainly of cooling systems to maintain the cold operating temperature of the superconducting processor. A classical processor uses bits to perform its operations. A quantum computer in comparison uses qubits (CUE bits) to execute multidimensional quantum algorithms. Some quantum processors are operated about a hundredth of a degree above absolute zero. To achieve this, cooled superfluids, which lead to superconduction in certain materials of the processor, are used typically.

[0011] To allow hundreds or even thousands of connections under the given space constraints, the goal is to keep the cable pitch, which is the distance measured between the center of one conductor to the center of the neighboring conductor, as small as possible. To minimize the crosstalk between neighboring lines, circumferential shielding is desirable as provided by coaxial transmission lines. The coaxial connectors thus need to be designed with emphasize on the size. At the same time, the connections made with the coaxial connector need to provide a connection with a stable impedance of typically e.g. 50 Q. It is desired to provide a connection with a radio frequency (RF) behavior, which is difficult to achieve. In addition, e.g. for applications in quantum computers, the components of the coaxial connectors need to be adapted to an environment of close to zero Kelvin, usually in a range of 10 mK to 4 K.

[0012] An objective of the present disclosure can therefore be seen in providing a coaxial connector, cable assembly and coaxial connector assembly with minimum space requirements aiming to get a pitch distance between neighboring coaxial connectors as close as possible to the cable diameter while using the smallest possible cable diameter limited by the radio frequency loss allowed in the respective application. Another objective of the present disclosure is the provision of a filter element having such properties. A coaxial connector according to the present disclosure is typically used for connecting a coaxial cable. The coaxial connector typically comprises an outer conductor in form of a base element, which comprises a through hole, which extends along a longitudinal axis from a first end to a second end of the base element. The base element can be a connector housing for connecting a single coaxial cable or for connecting a cascade of coaxial cables. The base element can be a rotational symmetrical connector element which can be mated with a mating base element of a mating coaxial connector, e.g. by a form fit, like a snap connection or friction-locked. Alternatively, the first end of the base element can have a flat front surface for making an essentially full surface contact in the connected state of the coaxial connector. This can be beneficial for connecting the base element to a flat assembly, e.g. a printed circuit board.

[0013] To be able to provide a high connection density, another aspect of the present disclosure is to provide an array of coaxial connectors wherein the coaxial connectors are arranged parallel to each other with respect to the longitudinal axis in a matrix configuration. The coaxial connectors of the array of coaxial connectors may share a common base element. The base element may be in form of cubical connector body, which can have a flat front surface for making full surface contact in the connected state of the coaxial connector. The base element is typically made of a conductive material and electrically connected to the outer conductor of at least one coaxial cable. The base element may comprise a cascade of through holes, which extend parallel to each other, each along a longitudinal axis from the first end to the second end of the base element. A cost efficient design which is in addition easy to manufacture can be achieved when the base element is machined from a solid part. Alternatively, additive manufacturing methods like 3D-printing may be used.

[0014] The coaxial connector is typically part of a cable assembly, which comprises at least one coaxial connector or an array of coaxial connectors as described herein and at least one coaxial cable. The coaxial cable can be attached to the outer conductor of the coaxial connector by soldering, gluing (conductive or non-con- ductive) and / or clamping the outer conductor of the coaxial cable to the base element. An end section of the at least one coaxial cable is therefore typically arranged within the at least one through hole of the base element of the coaxial connector. The outer conductors of multiple coaxial cables may be soldered in form of an array of coaxial cables such that the pitch is only increased compared to the cable diameter by a small separation wall in the base element and the minimum clearance needed as solder gap.

[0015] The coaxial connector typically further comprises a dielectric spacer to separate the outer conductor from a therein arranged inner conductor. The dielectric spacer is designed as a dielectric sleeve, which is arranged within the through hole of the base element and extends along the longitudinal axis. The spacer can function as both, electrical isolation between outer conductor and inner conductor and guide for the inner conductor which is typically in form of a spring element (further described herein below). The through hole can comprise a step, which acts as a stop for the dielectric sleeve, which extends from the first end of the base element to the step. This design allows that the dielectric spacer can be readily assembled by inserting the dielectric sleeve into the through hole in a disconnected state of the coaxial connector. In the connected state of the coaxial connector the dielectric sleeve can be secured in position between the step and a mating coaxial connector or an equivalent assembly.

[0016] The coaxial connector typically further comprises an inner conductor in form a spring element, which is arranged within the dielectric sleeve and extends along the longitudinal axis and comprises at least at a first end and / or at a second end a contact element. The spring element ensures that a reliable connection is achieved between, e.g. the inner conductor of a coaxial cable, which is attached to the coaxial connector, and the inner conductor of a coaxial cable of a connected mating coaxial connector or a printed circuit board or similar components, such as attenuators or filters (see further below). Known coaxial connectors with axial spring elements attempt to overcome impedance variation by electrically contacting each spring coil with their neighboring spring coils. The problem of these known solutions is the limitation in their downwards scalability in narrowing pitch while still providing sufficient axial alignment tolerance compensation. The reliability of such multiple contact points requires tight manufacturing tolerances and may cause abrasive degradation of the contact resistance during operation by micro movements caused by vibration and deviation of thermal expansion coefficient from the different used materials. For coaxial cables with targeted small diameters, the so far used spring elements get too delicate or even impossible to manufacture and still provide a reliable contact.

[0017] Good results to obtain a reliable connection with a constant impedance at the desired small dimensions can be achieved when the segment spacing of the spring element along the longitudinal axis is chosen such that in the connected state of the coaxial connector neighboring segments do not come in contact with each other. The segment spacing is thereby the distance between the individual spring segments. E.g. in case of a coil spring between the individual spring coils or in case of a planar spring element between the individual windings. The spring element is in a disconnected state of the coaxial connector typically extended along the longitudinal axis. This state is called the rest position of the spring element. In a connected state, the spring element is typically compressed along the longitudinal axis. In the compressed state the spring element is compressed and exerts a force, typically onto the inner conductor of the coaxial connector at a first end of the spring element and onto the inner conductor of the mating coaxial connector or electrical component at a second end. In a disconnected state of the coaxial connector, and therefore extended state of the spring element, the spring element may extend above the front surface of the base element. Furthermore, the spring element may extend at least partially beyond the dielectric sleeve.

[0018] The segment spacing of the spring element along the longitudinal axis can be chosen such that in the connected state of the coaxial connector the distance between neighboring segments is at least three times the structural diameter of the spring element, preferably four times, more preferably five times. The structural diameter of the spring element is the diameter of the structure making up the element. By way of example, for a coil spring the structural diameter is the diameter of the wire. For a planar spring element the structural diameter is for instance the thickness of the sheet formed into the planar spring element. A planar spring element is typically made of a band with a rectangular cross section which is wound, e.g. having a zigzag or wavelike geometry. The structural diam- eter is hereby the thickness of the band. It has been found that if a minimal distance between neighboring segments of at least three times the structural diameter of the spring element is respected, the influence on return loss, insertion loss, time delay and crosstalk between the segments can be substantially eliminated. For a comprehensive parametric analysis for designing serpentine structures using strip-line structures, see Datta et al., 2016 IEEE Dallas Circuits and Systems Conference (DCAS), DOI: 10.1109 / DCAS.2016.7791125.

[0019] Furthermore, good results are achieved when the lateral deflection of the segments of the spring element from the longitudinal axis is less than 12 mm, preferably less than 3 mm, more preferably less than 0.6 mm, even more preferably less than 0.1 mm. It has been found that these lateral deflections from the longitudinal axis of the spring element cause a stop band due to their periodicity and negative feedback. At about half the frequency of this stop band, the impedance of the waveguide changes and relevant disturbances occur. Consequently, these disturbances can be avoided, if the following condition is fulfilled (see Heeseok et al. IEEE Transactions on Advanced Packaging 2002, 25(2), 215-222).

[0020] DL < 12 mm ■ GHz I fmax

[0021] Wherein DL is the lateral deflection and fmax is the maximum frequency in GHz.

[0022] It follows that for a maximum frequency of 1 GHz the lateral deflection should be less than 12 mm. For a maximum frequency of 20 GHz the lateral deflection should be less than 0.6 mm. The spring element can be a planar spring element with a sinusoidal pattern along the longitudinal axis. In such an embodiment, the segment spacing between the local maxima of the sinusoidal pattern along the longitudinal axis can be chosen such that the in the connected state of the coaxial connector neighboring segments do not come in contact with each other. Furthermore, the distance between the local maxima of the sinusoidal pattern along the longitudinal axis can be chosen such that in the connected state of the coaxial connector the distance between neighboring local maxima is at least three times the structural diameter of the planar spring element, preferably four times, more preferably five times. Moreover, the amplitude of the sinusoidal pattern can be less than 12 mm, preferably less than 3 mm, more preferably less than 0.6 mm, even more preferably less than 0.1 mm. With regard to those features, reference is made to the above general discussion.

[0023] A wiggly shaped spring element similar to US7556503B2 but guided in a dielectric sleeve without shortening contacts between the convolutions provides a secure axial contact. When positioning the spring element within the dielectric sleeve and an outer conductor element in such a manner, that the cross section would represent a stripline with the desired (e.g. 50 Q) impedance, the RF-be- havior is hardly effected from the compression amplitude as long as the lines keep some line width away from their neighbors. In an embodiment where the spring element is a planar spring element, adjacent to the first end of the base element, the through hole and the therein arranged dielectric sleeve may have a rectangular cross section. A dielectric sleeve with a rectangular cross section can provide a guide for the planar spring element and ensure that the elastic deformation of the spring takes place essentially only along the longitudinal direction and avoids lateral wobbling of the spring element.

[0024] Alternatively, the spring element can be a coil spring with the coils being wound about the longitudinal axis. The segment spacing of the coil spring is then the spring pitch and the segments are spring coils. In such an embodiment, the segment spacing can be chosen such that in the connected state of the co-axial connector neighboring spring coils do not come in contact with each other. Furthermore, the segment spacing, in case of a coil spring typically the spring pitch, can be chosen such that in the connected state of the coaxial connector the distance between neighboring segments respectively spring coils is at least three times the wire diameter of the spring element, preferably four times, more preferably five times. Moreover, the radius of the coil spring can be less than 12 mm, preferably less than 3 mm, more preferably less than 1 mm, more preferably less than 0.5 mm. With regard to those features, reference is made to the above general discussion.

[0025] Preferably, an outer surface of the spring element can lie on a cylindrical surface with the longitudinal axis as a center axis and a radius, which identical to the outer radius of the coil spring, wherein the cross section of the spring wire is preferably rectangular. In other words, spring coils can be realized in a planar shape guided in the dielectric sleeve. Alternative to the planar stripline design, such a convolutional design with a flat coil spring opposite to the cylindrical boring in the housing represents a microstrip cross section which can be designed to the desired impedance (e.g. 50 Q) is effected from variating compression. In case of a coil spring, adjacent to the first end of the base element, the through hole and the therein arranged dielectric sleeve may have a round, preferably circular, cross section. A dielectric sleeve with a round cross section can provide a guide for the coil spring.

[0026] The spring element may alternatively be a cylindrical spring element with a meandering pattern along the longitudinal axis. In combination with a cylindrical dielectric sleeve the cylindrical outer contour of the spring element is beneficial for a smooth compression and extension of the spring element. A cylindrical spring element is insensitive to twisting as it is not prone to tilting. The segment spacing between the bends of the meandering pattern along the longitudinal axis can be chosen such that in the connected state of the coaxial connector neighboring segments do not come in contact with each other. The segment spacing between the bends of the meandering pattern along the longitudinal axis may be chosen such that in the connected state of the coaxial connector the distance between neighboring bends is at least three times the structural diameter of the cylindrical spring element, preferably four times, more preferably five times. With regard to those features, reference is made to the above general discussion.

[0027] The cylindrical spring element can be made by milling. More specifically, the segments can be made by milling recesses into the cylinder. The recesses can be arranged opposite with respect to the longitudinal axis and arranged alternating with respect to each other. The lateral deflection of the meandering pattern can be less than 12 mm, preferably less than 3 mm, more preferably less than 0.6 mm, even more preferably less than 0.1 mm. Adjacent to the first end of the base element the through hole and the therein arranged dielectric sleeve can have a circular cross section.

[0028] The shape of the spring element can provide a degressive spring load, so the contact force is less influenced by the axial tolerances. Due to the “wiggly line stripline” approach, the S-parameter is only marginally influenced by axial variation and / or misalignment. Radial dimension can be reduced without jeopardizing the axial movement, as this could be compensated by length of the spring element.

[0029] The contact elements of the spring element may be designed as tongues which extend parallel to the longitudinal direction and into opposite directions. In a disconnected state, at least the first end of the spring element typically extends beyond the flat front surface of the base element.

[0030] A geometry of the spring element according to the present disclosure allows the miniaturization especially in radial direction by still keeping the mechanical properties needed to cope with still large axial tolerances by keeping sufficient length of the spring along the longitudinal axis.

[0031] The spring element can be manufactured of any suitable spring elastic material. In addition, an optional coating at least at the contact elements can provide an improved conductivity, in particular for non-conductive base materials. Depending on the material, multiple low cost production methods are possible, such as punch bending or stamping. Depending on the field of application, the spring element can be made of superconductive materials such as metallic glasses. Some metallic glasses become superconductive at targeted operation temperature and can hinder dissipative heating in cryogenic environments.

[0032] The spring element can be used to connect signal lines between coaxial cables and / or quasi coax components like e.g. coaxial connectors, PCB-waveguides including striplines, microstrips, attenuators, or waveguide components - with direct or indirect (additional part) connection.

[0033] Although spring steel or beryllium-copper provide excellent spring properties, their relatively high Young’s modulus causes comparatively high spring loads, which in multi-line connections may sum-up to undesirable forces in the connectivity system. Therefore, for certain applications materials with lower Young’s modules are desirable, such as polymers or metallic glasses. Thermoplastic polymers and / or metallic glasses can be produced with alternative production methods, such as injection molding and 3D-printing. Especially in cryogenic applications, like e.g. quantum computing, some metallic glasses become superconductive. For these applications thermalization is key. In order to eliminate noise photons, the temperature of signal lines close to the quantum chip must be cooled to values well below some Millikelvins (mK). Even very low losses of the spring element could cause thermal heating and cooling is only possible on the small contact points to the other devices.

[0034] To achieve a space saving and low-loss connection, the end section of the coaxial cable can be arranged in the through hole of the base element and may in the mounted state in contact with the dielectric sleeve which acts as a stop for the coaxial cable. Adjacent to the second end of the base element the diameter of the through hole may be larger than the outer diameter of the coaxial cable and the clearance between coaxial cable and through hole may be filled with an adhesive (conductive or nonconductive) or solder.

[0035] A coaxial connector assembly according to the present disclosure typically comprises a coaxial connector, an array of coaxial connectors or a cable assembly as described herein above. A base element of the coaxial connector and the base element of the mating coaxial connector - or arrays thereof - may be one piece. An intermediate element may be arranged between a first inner conductor of the coaxial connector and a second inner conductor of a mating coaxial connector. The intermediate element may be arranged in a recess with an opening perpendicular to the longitudinal direction (x).

[0036] Preferably, the intermediate element is attached to base element in a way to provide good thermal contact, as for example with a thermal conductive adhesive. To improve the thermal conductivity from the intermediate element to the baseelement, it can also be advantageous to fill a dielectric compound of the intermediate element directly into the recess (e.g. by dispensing or injection molding) to achieve high thermal contact between the dissipative compound end the base element.

[0037] The intermediate element may be a signal attenuator which comprises a substrate layer and a first and second signal contact tab and at least one further ground contact tab. A signal attenuator is an electronic device which is configured to reduce the power of a signal without appreciably distorting its waveform. An attenuator is therefore effectively the opposite of an amplifier. While an amplifier provides gain, an attenuator provides loss, or gain less than 1 . The attenuator can be used to lower voltage, dissipate power, and / or to improve impedance matching.

[0038] The first and second contact tab may in the connected state of the coaxial connector assembly be contacted by the spring elements of the first coaxial connector and the mating coaxial connector. In the connected state of the coaxial connector assembly the first contact tab can be contacted by the spring element of the first coaxial connector and the second contact tab can be contacted by the spring element of the mating coaxial connector. The at least one ground contact tab can be attached with an adhesive (preferable conductive adhesive) or solder to the base element providing ground contact and good thermal heat transfer. Especially at lowest temperature stages, where solder becomes superconducting, the thermal conductivity can become poor, so e.g. silver filled conductive adhesive may provide significant better thermal conductivity, which is key to keep the thermal noise generated from the attenuator at the requested lowest levels.

[0039] The intermediate element of the coaxial connector assembly may be a filter element, in particular a low-pass filter element, as described in the following in more detail.

[0040] The present disclosure further relates to a filter element comprising a conductor with a sinusoidal or meandering pattern along a longitudinal axis. While the above-described spring elements are preferably conceived such that disturbances are avoided, by designing the lateral deflections from the longitudinal axis of the spring element to cause a stop band due to their periodicity and negative feedback, a filter element can be provided in a manner to allow disturbances to occur and thereby achieve a low-pass desired filter effect for certain frequency rages. Resonances, cross talk and destructive interference increase transmission losses above a frequency which is defined by the geometry of the meandering pattern. While the spring element is typically designed to avoid these disturbances, the filter element is designed to make use of these disturbances.

[0041] The conductor can be a planar spring element, typically made of a band with a rectangular cross section which is wound, e.g. having a zigzag or wavelike geometry. The structural diameter is hereby the thickness of the band. The segment spacing between the local maxima of the sinusoidal pattern or the bends of the meandering pattern along the longitudinal axis is preferably chosen such that the distance between neighboring local maxima is at most five times the structural diameter of the conductor, preferably four times, more preferably three times. For a comprehensive parametric analysis for designing serpentine structures using strip-line structures, see Datta et al., 2016 IEEE Dallas Circuits and Systems Conference (DCAS), DOI: 10.1109 / DCAS.2016.7791125.

[0042] The amplitude of the sinusoidal pattern or lateral deflection of the meandering pattern may be more than 3 mm divided by the square root of the relative permittivity srof the surrounding dielectric.

[0043] DL > 3 mm / VE? A conductor with a sinusoidal or meandering pattern along a longitudinal axis shows an improved filter effect compared to known dissipative filters with a coaxial structure comprising a linear conductor and filled with a dissipative dielectric. Typically, the amplitude of the sinusoidal pattern or lateral deflection of the meandering pattern is more than 0.1 mm, preferably more than 0.5 mm, more preferably more than 1 mm, even more preferably more than 3 mm.

[0044] The pathlength between two neighboring local maxima of the sinusoidal or meandering pattern is defined by the segment spacing (periodicity) and the lateral deflection (amplitude). By choosing the pathlength constructive or destructive interferences can be created. Good filtering results have been observed, when the pathlength either equals lambda / 2 or lambda.

[0045] The conductor can have a sinusoidal or meandering pattern with constant precocity (i.e. segment spacing and amplitude or lateral deflection, respectively) over its length. Alternatively, the conductor can also have several segments with varying periodicity (segment spacing and / or amplitude / lateral deflection, depending on the requirements for the stop band).

[0046] The conductor can be embedded in a compound, preferably a dielectric polymer. The compound can comprise metallic or dielectric lossy particles causing a variation of complex permittivity (E’(W) + i E”(W)) with the frequency of a signal sent through the filter element. In other words, the effect of the particles being embedded in the dielectric polymer is that the dampening effect becomes frequency dependent. With higher frequency a higher damping effect occurs. This effect has been observed with known coaxial filter elements with a linear center conductor: See Scheller et al., 2014 Applied Physics Letters, Volume 104, Issue 21 , 211106 (2014): Silver-epoxy microwave filters and thermalizers for millikelvin experiments. Scheller et al. propose a silver-epoxy (Ag-epoxy) cryogenic filter, uniting desirable microwave attenuation with increased thermalization, suitable for low temperature electronic measurements.

[0047] See Ivanov et al., 2018 Applied Physics Letters, Volume 123, Issue 20, 204001 (2023): Robust cryogenic matched low-pass coaxial filters for quantum computing applications. Ivanov et al. propose cryogenic matched low-pass coaxial filters for quantum computing applications. Disclosed are filters of different lengths with compound of Cu powder and Stycast commercial resin demonstrating favorable matching.

[0048] The coaxial connector assembly according to the present disclosure can comprise a coaxial connector, an array of coaxial connectors or a cable assembly and an intermediate element, which may be arranged between a first inner conductor of the coaxial connector and a second inner conductor of a mating coaxial connector. The intermediate element can be a filter element as described above noted. The base element of the coaxial connector and the base element of the mating coaxial connector may be one piece. The intermediate element can be arranged in a recess with an opening perpendicular to the longitudinal direction.

[0049] It is to be understood that both the foregoing general description and the following detailed description present embodiments are intended to provide an overview or framework for understanding the nature and character of the disclosure. The accompanying drawings are included to provide a further understanding, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments, and together with the description serve to explain the principles and operation of the concepts disclosed.

[0050] BRIEF DESCRIPTION OF THE DRAWINGS The herein described disclosure will be more fully understood from the detailed description given herein below and the accompanying drawings, which should not be considered limiting to the disclosure described in the appended claims. The drawings are showing:

[0051] Fig. 1 a perspective view of a first variation of the cable assembly comprising an array of coaxial connectors and coaxial cables;

[0052] Fig. 2 a front view of the first variation of the cable assembly according to Fig. 1 in Fig. 2a and a sectional view thereof in Fig. 2b;

[0053] Fig. 3 an exploded sectional perspective view of the first variation of the cable assembly according to Fig. 1 ; Fig. 4 a perspective view of a first variation of the coaxial connector assembly comprising a coaxial connector and a mating coaxial connector;

[0054] Fig. 5 a front view of the first variation of the coaxial connector assembly according to Fig. 4 in Fig. 5a and a sectional view thereof in Fig. 5b; Fig. 6 an exploded sectional perspective view of the first variation of the coaxial connector assembly according to Fig. 5;

[0055] Fig. 7 a sectional perspective view of a second variation of the cable assembly comprising a coaxial connector and a coaxial cable; Fig. 8 an exploded sectional perspective view of the second variation of the cable assembly according to Fig. 7;

[0056] Fig. 9 a first variation of the spring element in a sectional perspective view in Fig. 9a and as a lateral view in Fig. 9b;

[0057] Fig. 10 a second variation of the spring element in a sectional perspective view in Fig. 10a and as a lateral view in Fig. 10b;

[0058] Fig. 11 a third variation of the spring element in a perspective view in Fig. 11 a and as a lateral view in Fig. 11 b;

[0059] Fig. 12 a first variation of the filter element in a sectional perspective view in Fig. 12a and as a lateral view in Fig. 12b; Fig. 13 a second variation of the coaxial connector assembly in a perspective view in Fig. 13a, in a sectional perspective view in Fig. 13b and in a detailed sectional perspective view in Fig. 13c; Fig. 14 a third variation of the coaxial connector assembly in a perspective view in Fig. 14a, in a sectional perspective view in Fig. 14b and in a detailed sectional perspective view in Fig. 14c.

[0060] DESCRIPTION OF THE EMBODIMENTS

[0061] Reference will now be made in detail to certain embodiments, examples of which are illustrated in the accompanying drawings, in which some, but not all features are shown. Indeed, embodiments disclosed herein may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Whenever possible, like reference numbers will be used to refer to like components or parts.

[0062] Figures 1 to 3 show a first variation of the cable assembly 22 comprising an array of coaxial connectors 21 and coaxial cables 23 (shown as cable stumps). As can be obtained from Figure 1, showing a perspective view, the cable assembly 22 comprises a number of coaxial connectors 1 arranged in an array 21 of coaxial connectors. A coaxial cable 23 is connected to each coaxial connector 1 . The shown coaxial cables 23 are attached to the outer conductor 3 of each coaxial connector 1 by soldering, gluing and / or clamping the respective outer conductor 24 of the coaxial cable 23 to the base element 4. The shown coaxial connectors 1 are arranged parallel to each other with respect to the longitudinal axis x in a matrix configuration and share a common base element 4. As can be obtained from the front view of Figure 2a and sectional view of Figure 2b, the coaxial connector 1 comprises an outer conductor 3 in form of a base element 4. The shown base element 4 comprises a through hole 5, which extends along a longitudinal axis x from the first end 6 to the second end 7 of the base element 4. The dielectric spacer 8 in form of a dielectric sleeve 9 is arranged within the through hole 5 and extends along the longitudinal axis x. The inner conductor 10 in form a spring element 11 is arranged within the dielectric sleeve 9 and extends along the longitudinal axis x and comprises at its first end 12 and at its second end 13 a contact element 14.

[0063] As can be seen, the shown spring element 11 is in the connected state compressed along the longitudinal axis x. Also in the connected state, the second end 13 is in contact with the inner conductor 24 of the coaxial cable 23 and the first end 12 is in contact with an external assembly, in the shown variation with a printed circuit board. The shown spring element 11 is a planar spring element 16 with a sinusoidal pattern along the longitudinal axis x. In a disconnected state (not shown) of the coaxial connector 1 , the spring element 11 extends at least partially beyond the dielectric sleeve 9. The shown base element 4 has a flat front surface 20 for making an essentially full surface contact in the connected state of the coaxial connector 1 . An end section 25 of the coaxial cable 23 is arranged in the through hole 5 of the base element 4 and is in the shown mounted state in contact with the dielectric sleeve 9 which acts as a stop 26 for the coaxial cable 23.

[0064] Figure 3 shows an exploded sectional perspective view of the first variation of the cable assembly. The diameter DH of the through hole 5 is adjacent to the second end 8 of the base element 4 larger than the outer diameter DC of the coaxial cable 23 and the clearance between coaxial cable 23 and through hole 5 is filled with solder or an adhesive. Adjacent to the first end 6 of the base element 4, the through hole 5 and the therein arranged dielectric sleeve 9 both have a rectangular cross section CS. The contact elements 14 of the spring element 11 are designed as tongues 18 which extend parallel to the longitudinal direction x and into opposite directions. The through hole 5 comprises a step 19, which acts as a stop for the dielectric sleeve 9 which extends from the first end 6 of the base element 4 to the step 19. In a disconnected state, at least the first end 12 of the spring element 11 extends beyond the flat front surface 20.

[0065] Figures 4 to 6 show a first variation of the coaxial connector assembly 27 comprising a first array 23 of cable assemblies 22 and a mating second array 23’ of cable assemblies 22’. As can be obtained from Figures 5, showing a front view of the first variation of the coaxial connector assembly 27 in Figure 5a and a sectional view thereof in Figure 5b, intermediate elements 28 are arranged between a first inner conductor 10 of the coaxial connector 1 and a second inner conductor 10’ of a mating coaxial connector 29. The coaxial cables 23, 23’ are attached to the respective outer conductor 3, 3’ by soldering and / or clamping the outer conductors 24, 24’ of the coaxial cables 23, 23’ to the base elements 4, 4’. The coaxial connectors 1 of the array of coaxial connectors 21 are arranged parallel to each other with respect to the longitudinal axis x in a matrix configuration.

[0066] The shown coaxial connector 1 and mating coaxial connector 29 each comprise an outer conductor 3, 3’ in form of a base element 4, 4’ comprising a through holes 5, 5’ which each extend along a longitudinal axis x from a first end 6, 6’ to a second end 7, 7’ of the base elements 4, 4’. The dielectric spacers 8, 8’ are in form of dielectric sleeves 9, 9’ which are arranged within the through holes 5, 5’ of the base elements 4, 4’ and each extend along the respective longitudinal axis x. The inner conductors 10, 10’ are in form spring elements 11 , 11 ’, which are arranged within the dielectric sleeves 9, 9’, each extend along a longitudinal axis x and comprise at a first end 12, 12’ and a second end 13, 13’ contact elements 14, 14’.

[0067] The spring elements 11 , 1 T are in the shown connected state of the coaxial connectors 1 , 29 compressed along the longitudinal axis x. The segment spacing of the spring elements 11 , 1 T is chosen such that in the connected state of the coaxial connectors 1 , 29 neighboring segments do not come in contact with each other. The spring elements 11 , 1 T are planar spring elements 16, 16’ with a sinusoidal pattern along the longitudinal axis x. Adjacent to the first end 6, 6’ of the base element 4, 4’ each of the through holes 5, 5’ and the therein arranged dielectric sleeves 9, 9’ have a rectangular cross section. The contact elements 14, 14’ of the spring elements 11 , 1 T are designed as tongues which extend parallel to the longitudinal direction x and into opposite directions. In the shown variation, the second ends 13, 13’ of the spring elements 11 , 1 T each contact the inner conductor of a coaxial cable 23, 23’ and the first ends 12, 12’ each contact an intermediate element 28.

[0068] The through holes 5, 5’ each comprise a step 19, 19’ which acts as a stop for the respective dielectric sleeve 9, 9’ which extends from the first end 6, 6’ of the base element 4, 4’ to the step 19, 19’. The first ends 6, 6’ of the base elements 4, 4’ of the coaxial connector 1 as well as of the mating coaxial connector 29 each have a flat front surface 20, 20’ for making an essentially full surface contact in the connected state. The shown end sections 25, 25’ of the coaxial cables 23, 23’ are arranged in the through holes 5, 5’ of the base elements 4, 4’ of the coaxial connector 1 and the mating coaxial connector 29. They are in the mounted state in contact with the dielectric sleeves 9, 9’ which act as stops 26, 26’ for the coaxial cables 23, 23’. The diameters of the through holes 5, 5’ are adjacent to the second end 7, 7’ of the base elements 4, 4’ larger than the outer diameters of the coaxial cables 23, 23’ and the clearance C between coaxial cables 23, 23’ and through holes 5, 5’ are filled with solder.

[0069] As can be obtained from Figure 6 showing an exploded sectional perspective view of the first variation of the coaxial connector assembly 27, the intermediate elements 28 are signal attenuators 30, which comprise a substrate layer 31 and a first and second contact tab 32, 33. In the connected state of the coaxial connector assembly 27, the first and second contact tabs 32, 33 are contacted by the spring elements 11 , 1 T of the first coaxial connector 1 and the mating coaxial connector 29. In the connected state of the coaxial connector assembly 27, the first contact tab 32 is contacted by the spring element 11 of the first coaxial connector 1 and the second contact tab 33 is contacted by the spring element 1 T of the mating coaxial connector 29. In a disconnected state, at least the first end 12 of the spring element 11 extends beyond the flat front surface 20.

[0070] Figures 7 and 8 show a second variation of the cable assembly comprising a coaxial connector 1 and a coaxial cable 23. Figure 7 shows a sectional perspective view of a second variation of the cable assembly 22 comprising a coaxial connector 1 and a coaxial cable 23. The shown cable assembly 22 comprises a coaxial connector 1 with a rotational symmetrical base element 4. The shown coaxial cable 23 is attached to the outer conductor 3 by soldering and / or clamping an outer conductor 24 of the coaxial cable 23 to the base element 4. The shown rotational symmetrical base element 4 is configured to be connected to a mating coaxial connector 29 by means of a plug connection, thereby contacting the contact pin of the mating coaxial connector 29.

[0071] The shown base element 4 comprises a through hole 5 which extends along a longitudinal axis x from a first end 6 to a second end 7 of the base element 4. A dielectric spacer 8 in form of a dielectric sleeve 9 is arranged within the through hole 5 of the base element 4. A spring element 11 is arranged within the dielectric sleeve 9 and extends along the longitudinal axis x. The shown spring element 11 is in form of a coil spring 17 which comprises at its first end 12 and second end 13 contact elements 14. The spring element 11 is in a disconnected state of the coaxial connector 1 extended along the longitudinal axis x and in a connected state compressed along the longitudinal axis x.

[0072] The segment spacing, which equals the spring pitch of the spring element 11 is chosen such that in the connected state of the coaxial connector 1 neighboring spring coils 15 do not come in contact with each other. The shown spring coils 15 are wound about the longitudinal axis x and arranged in the dielectric spacer 8. Adjacent to the first end 6 of the base element 4 the through hole 5 and the therein arranged dielectric sleeve 9 have a round, preferably circular, cross section. The contact elements 14 of the spring element 11 are designed as tongues 18 which extend parallel to the longitudinal direction x and into opposite directions. The through hole 5 comprises a step 19 which acts as a stop for the dielectric sleeve

[0073] 9 and extends from the first end 6 of the base element 4 to the step 19.

[0074] As can be obtained from Figure 8, showing an exploded sectional perspective view of the second variation of the coaxial connector assembly 27, a stump or end section 25 of the coaxial cable 23 is arranged in the through hole 5 of the base element 4 and is in the mounted state in contact with the dielectric sleeve 9 which acts as a stop 26 for the coaxial cable 23. The diameter DH of the through hole 5 is adjacent to the second end 7 of the base element 4 larger than the outer diameter DC of the coaxial cable 23 and the clearance C between coaxial cable 23 and through hole 5 is filled with solder. In a disconnected state of the coaxial connector 1 , the spring element 11 extends at least partially beyond the dielectric sleeve 9. The outer surface 34 of the spring element 11 lies on a cylindrical surface with the longitudinal axis x as a center axis and a radius, which is identical to the outer radius of the coil spring 17 with the cross section of the spring wire being preferably rectangular.

[0075] Figures 9 and 10 show two variations of the spring element 11 . Both variations of the spring element 11 is in a disconnected state of the coaxial connector extended along the longitudinal axis x. In a connected state the spring elements 11 are compressed along the longitudinal axis x. The spring pitch P of the spring elements 11 is chosen such that in the connected state of the coaxial connector 1 neighboring spring coils 15 do not come in contact with each other. The contact elements 14 of the spring element 11 are designed as tongues 18 which extend parallel to the longitudinal direction x and into opposite directions. As can be obtained from Figure 9, the respective spring element 11 is a planar spring element 16 which has a sinusoidal pattern along the longitudinal direction x. The segment spacing P between the local maxima of the sinusoidal pattern along the longitudinal axis x is chosen such that the in the connected state of the coaxial connector 1 neighboring segments do not come in contact with each other. Furthermore, the segment spacing distance P between the local maxima of the sinusoidal pattern along the longitudinal axis x is chosen such that the in the connected state of the coaxial connector 1 the distance between neighboring local maxima is at least three times the structural diameter of the planar spring element DS. The sinusoidal pattern has the lateral deflection or amplitude DL.

[0076] Figure 10 shows a second variation of the spring element 11 in form of a coil spring being wound about the longitudinal axis x. The spring has a pitch P which is chosen such that in the connected state of the coaxial connector 1 the distance between neighboring spring coils is at least three times the wire diameter DS of the spring element 11 . Furthermore, the spring pitch P is chosen such that in the connected state of the coaxial connector 1 neighboring spring coils do not come in contact with each other. An outer surface 34 of the spring element lies on a cylindrical surface with the longitudinal axis x as a center axis and a radius, which is identical to the outer radius of the coil spring 17. In the present example, the cross section of the spring wire is rectangular. The segment spacing, being equivalent to the pitch is chosen such that in the connected state of the coaxial connector the distance between neighboring spring coils is at least three times the wire diameter of the spring element, preferably four times, more preferably five times. The radius of the shown coils is typically less than 12 mm, preferably less than 3 mm, more preferably less than 1 mm, more preferably less than 0.5 mm. The outer surface 34 of the spring element 11 lies on a cylindrical surface SC with the longitudinal axis as a center axis and a radius R, which is identical to the outer radius of the coil spring, which also corresponds to the lateral deflection DL. The spring coils are realized in a planar shape guided in the dielectric sleeve.

[0077] Figure 11 shows a third variation of the spring element 11. The spring element 11 is in form of a cylindrical spring element 35 with a meandering pattern along the longitudinal axis x. The segment spacing P between the bends of the meandering pattern along the longitudinal axis x is chosen such that in the connected state of the coaxial connector, neighboring segments do not come in contact with each other. The segment spacing P between the bends of the meandering pattern along the longitudinal axis x is further chosen such that in the connected state of the coaxial connector, the distance between neighboring bends is at least three times the structural diameter DS of the cylindrical spring element 35, preferably four times, more preferably five times. The lateral deflection DL of the meandering pattern is less than 12 mm, preferably less than 3 mm, more preferably less than 0.6 mm, even more preferably less than 0.1 mm.

[0078] Figure 12 shows a first variation of a filter element 37 comprising a conductor 38 with a meandering pattern along a longitudinal axis x. The segment spacing P between the bends of the meandering pattern along the longitudinal axis x is chosen such that neighboring segments do not come in contact with each other. The segment spacing P between the bends of the meandering pattern along the longitudinal axis x is further chosen such that the distance between neighboring bends is at most five times the structural diameter DS of the planar spring element, preferably four times, more preferably three times. The conductor 38 is embedded in a compound 39, preferably a dielectric polymer. The compound 39 comprises metallic or dielectric lossy particles causing a variation of complex permittivity (E’(W) + i E”(W)) with the frequency of a signal sent through the filter element. Furthermore, the filler particles improve significantly the thermal conductivity of the compound, which allows to transport the dissipated RF-energy aways keeping the temperature increase to a minimum.

[0079] Figure 13 and Figure 14 show two variations of the coaxial connector assembly 27 with a one-pieced base element 4, 4’. Instead of having a coaxial connector 1 and a mating coaxial connector 29 with separate base elements, the base element 4 of the coaxial connector 1 and the base element 4’ of the mating coaxial connector 29 are one piece made of a material, preferably a metal with high thermal conductivity, especially in the range from 10mK to 4K (e.g. copper or copper alloys). This means that metals which become superconductive should be avoided, as superconductivity reduces thermal conductivity by orders of magnitude. Further the base element 4’ should avoid any non-functional boring or recesses, reducing thermal conductivity from the dissipative insert to the cooling plate of the dilution refrigerator to keep the temperature increase of the dissipative insert ideally below 1 K, better 100mK, better 10mK compared to the cooling plate of the dilution refrigerator. The integral base element 4, 4’ is foreseen for connecting an array of coaxial cables 23, 23’ whereby each coaxial cable 23, 23’ is attached to the outer conductor 3 in form of the base element 4 by gluing an outer conductor 24 of the respective coaxial cable 23, 23’ to the base element 4. The coaxial connector assembly 27 further comprises an array of mating coaxial connectors 29, whereby each coaxial cable 23, 23’ is also attached to the base element 4’ by gluing an outer conductor 24 of the coaxial cable 23, 23’ to the base element 4’.

[0080] The common base element 4, 4’ functions as an outer conductor 3 and comprises a number of through holes 5 which each extends along a longitudinal axis x from a first end 6 to a second end 7 of the base element 4, 4’. The through holes 5 are arranged as an array, whereby the through holes 5 of the array are arranged in parallel with respect to each other. In each through hole 5 a dielectric spacer in form of a dielectric sleeve 9 is arranged, which extends along the respective longitudinal axis x. The inner conductors are in form of spring elements 11 , which are arranged within the respective dielectric sleeve 9 and extend along the longitudinal axis x.

[0081] The shown spring elements 11 are cylindrical spring elements 35, as described with respect to Figure 11 in more detail. Between each coaxial connector 1 and mating coaxial connector 27 an intermediate element 28 is arranged. In Figures 13a to 13c, the shown intermediate element 28 is a filter element 37, as described with respect to Figure 12 in more detail. The filter elements 37 are each arranged in a recess 36 with an opening perpendicular to the longitudinal direction x. To improve the thermal conductivity from the dissipative filter to the baseelement 4’, it can be advantageous to fill the lossy dielectric compound directly into the recesses (e.g. by dispensing or injection molding) to achieve high thermal contact between the dissipative compound end the base element 4’. The variation shown in Figure 14a to 14c is essentially similar to the variation shown in Figure 13. The key difference is that instead of filter elements 37, intermediate elements 28 in form of signal attenuators 30 are arranged. Preferably, the intermediate elements 28 are attached to base element 4’ in a way to provide good thermal contact, as for example with a thermal conductive adhesive.

[0082] Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without depart- ing from the Spirit and scope of the disclosure.

[0083] LIST OF DESIGNATIONS

[0084] I Coaxial connector 22 Cable assembly

[0085] 23 Coaxial cable

[0086] 3 Outer conductor 24 Outer conductor (coaxial

[0087] 4 Base element cable)

[0088] 5 Through hole 30 25 End section (coaxial ca¬

[0089] 6 First end (base element) ble)

[0090] 7 Second end (base ele26 Stop ment) 27 Coaxial connector as¬

[0091] 8 Dielectric spacer sembly

[0092] 9 Dielectric sleeve 35 28 Intermediate element

[0093] 10 Inner conductor 29 Mating coaxial connector

[0094] I I Spring element 30 Signal attenuator

[0095] 12 First end (spring element) 31 Substrate layer

[0096] 13 Second end (spring ele32 First contact tab ment) 40 33 Second contact tab

[0097] 14 Contact element 34 Outer surface coil spring

[0098] 15 Spring coils 35 Cylindrical spring element

[0099] 16 Planar spring element 36 Recess (base element)

[0100] 17 Coil spring 37 Filter element

[0101] 18 Tongues 45 38 Conductor

[0102] 19 Step 39 Compound

[0103] 20 Front surface 40 Particles

[0104] 21 Array of coaxial connectX Longitudinal axis ors P Segment spacing CS Cross section 5 DC Diameter (Coaxial cable)

[0105] DS Structural diameter C Clearance

[0106] DL Lateral deflection SC Cylindrical surface

[0107] DH Diameter (Through hole) R Radius

Claims

PATENT CLAIMS1 . A coaxial connector (1 ) for connecting a coaxial cable (23), the coaxial connector (1 ) comprising a. an outer conductor (3) in form of a base element (4) comprising a through hole (5) which extends along a longitudinal axis (x) from a first end (6) to a second end (7) of the base element (4), and b. a dielectric spacer (8) in form of a dielectric sleeve (9) which is arranged within the through hole (5) of the base element (4) and extends along the longitudinal axis (x), and c. an inner conductor (10) in form of a spring element (11 ) which is arranged within the dielectric sleeve (9) and extends along the longitudinal axis (x) and comprises at least at a first end (12) and / or at a second end (13) a contact element (14).

2. The coaxial connector (1 ) according to claim 1 , wherein the spring element (11 ) is in a disconnected state of the coaxial connector (1 ) extended along the longitudinal axis (x) and in a connected state compressed along the longitudinal axis (x).

3. The coaxial connector (1 ) according to one of the preceding claims, wherein the segment spacing (P) of the spring element (11 ) along the longitudinal axis (x) is chosen such that in the connected state of the coaxial connector (1 ) neighboring segments do not come in contact with each other.

4. The coaxial connector (1 ) according to claim 3, wherein the segment spacing (P) of the spring element (11 ) along the longitudinal axis (x) is chosen such that in the connected state of the coaxial connector (1 ) the distance between neighboring segments is at least three times the structural diameter (DS) of the spring element (11 ), preferably four times, more preferably five times.

5. The coaxial connector (1 ) according to one of the preceding claims, wherein the lateral deflection (DL) of the segments of the spring element (11 ) from the longitudinal axis (x) is less than 12 mm, preferably less than 3 mm, more preferably less than 0.6 mm, even more preferably less than 0.1 mm.

6. The coaxial connector (1 ) according to one of the preceding claims, wherein the spring element (11 ) is a planar spring element (16) with a sinusoidal pattern along the longitudinal axis (x).

7. The coaxial connector (1 ) according to claim 6, wherein the segment spacing (P) between the local maxima of the sinusoidal pattern along the longitudinal axis (x) is chosen such that in the connected state of the coaxial connector (1 ) neighboring segments do not come in contact with each other.

8. The coaxial connector (1 ) according to claim 7, wherein the segment spacing (P) between the local maxima of the sinusoidal pattern along the longitudinal axis (x) is chosen such that in the connected state of the coaxial connector (1 ) the distance between neighboring local maxima is at leastthree times the structural diameter (DS) of the planar spring element, preferably four times, more preferably five times.

9. The coaxial connector (1 ) according to one of claims 6 to 8, wherein the amplitude (DL) of the sinusoidal pattern is less than 12 mm, preferably less than 3 mm, more preferably less than 0.6 mm, even more preferably less than 0.1 mm.

10. The coaxial connector (1 ) according to one of claims 6 to 9, wherein adjacent to the first end (6) of the base element (4) the through hole (5) and the therein arranged dielectric sleeve (9) have a rectangular cross section (CS).

11. The coaxial connector (1 ) according to one of claims 1 to 5, wherein the spring element (11 ) is a coil spring (17) with the coils being wound about the longitudinal axis (x) and wherein the segment spacing (P) is a spring pitch.

12. The coaxial connector (1 ) according to claim 11 , wherein the segment spacing (P) is chosen such that in the connected state of the coaxial connector (1 ) neighboring spring coils do not come in contact with each other.

13. The coaxial connector (1 ) according to claim 12, wherein the segment spacing (P) is chosen such that in the connected state of the coaxial connector (1 ) the distance between neighboring segments is at least three times the wire diameter of the spring element (11 ), preferably four times, more preferably five times.

14. The coaxial connector (1 ) according to one of claims 11 to 13, wherein an outer surface (34) of the spring element lies on a cylindrical surface (SC) with the longitudinal axis (x) as a center axis and a radius (R), which is identical to the outer radius of the coil spring (17), wherein the cross section of the spring wire is preferably rectangular.

15. The coaxial connector (1 ) according to one of claims 11 to 14, wherein the radius of the coil spring (17) is less than 12 mm, preferably less than 3 mm, more preferably less than 0.6 mm, even more preferably less than 0.1 mm.

16. The coaxial connector (1 ) according to one of claims 11 to 15, wherein adjacent to the first end (6) of the base element (4) the through hole (5) and the therein arranged dielectric sleeve (9) have a round, preferably circular, cross section (CS).

17. The coaxial connector (1 ) according to one of claims 1 to 5, wherein the spring element (11 ) is a cylindrical spring element (35) with a meandering pattern along the longitudinal axis (x).

18. The coaxial connector (1 ) according to claim 17, wherein the segment spacing (P) between the bends of the meandering pattern along the longitudinal axis (x) is chosen such that in the connected state of the coaxial connector (1 ) neighboring segments do not come in contact with each other.

19. The coaxial connector (1 ) according to claim 18, wherein the segment spacing (P) between the bends of the meandering pattern along the longitudinal axis (x) is chosen such that in the connected state of the coaxialconnector (1 ) the distance between neighboring bends is at least three times the structural diameter (DS) of the cylindrical spring element, preferably four times, more preferably five times.

20. The coaxial connector (1 ) according to one of claims 17 to 19, wherein the lateral deflection (DL) of the meandering pattern is less than 12 mm, preferably less than 3 mm, more preferably less than 0.6 mm, even more preferably less than 0.1 mm.21 . The coaxial connector (1 ) according to one of claims 17 to 20, wherein adjacent to the first end (6) of the base element (4) the through hole (5) and the therein arranged dielectric sleeve (9) have a circular cross section (CS).

22. The coaxial connector (1 ) according to one of the preceding claims, wherein the contact elements (14) of the spring element (11 ) are designed as tongues (18) which extend parallel to the longitudinal direction (x) and into opposite directions.

23. The coaxial connector (1 ) according to one of the preceding claims, wherein the through hole (5) comprises a step (19) which acts as a stop for the dielectric sleeve (9) which extends from the first end (6) of the base element (4) to the step (19).

24. The coaxial connector (1 ) according to one of the preceding claims, wherein in a disconnected state of the coaxial connector (1 ), the spring element (11 ) extends at least partially beyond the dielectric sleeve (9).

25. The coaxial connector (1 ) according to one of the preceding claims, wherein the first end (6) of the base element (4) has a flat front surface (20) for making an essentially full surface contact in the connected state of the coaxial connector (1 ).

26. The coaxial connector (1 ) according to claim 25, wherein in a disconnected state, at least the first end (12) of the spring element (11 ) extends beyond the flat front surface (20).

27. An array of coaxial connectors (21 ) according to one of the preceding claims, wherein the coaxial connectors (1 ) are arranged parallel to each other with respect to the longitudinal axis (x) in a matrix configuration.

28. The array of coaxial connectors (21 ) according claim 27, wherein the coaxial connectors (1 ) share a common base element (4).

29. A cable assembly (22) comprising a coaxial connector (1 ) according to one of claims 1 to 26 or an array of coaxial connectors (21 ) according one of claims 27 or 28 and at least one coaxial cable (23), wherein the coaxial cable (23) is attached to the outer conductor (3) by soldering, gluing and / or clamping an outer conductor (24) of the coaxial cable (23) to the base element (4).

30. The cable assembly (22) according to claim 29, wherein an end section (25) of the coaxial cable (23) is arranged in the through hole (5) of the base element (4) and is in the mounted state in contact with the dielectric sleeve (9) which acts as a stop (26) for the coaxial cable (23).31 . The cable assembly (22) according to claim 29 or 30, wherein the diameter (DH) of the through hole (5) is adjacent to the second end (7) of the base element (4) larger than the outer diameter (DC) of the coaxial cable (23) and the clearance (C) between coaxial cable (23) and through hole (5) is filled with solder or an adhesive.

32. A coaxial connector assembly (27) comprising a coaxial connector (1 ) according to any one of claims 1 to 26, an array of coaxial connectors (23) according to any one of claims 27 or 28 or a cable assembly (22) according to any one of claims 29 to 31 , wherein an intermediate element (28) is arranged between a first inner conductor (10) of the coaxial connector (1 ) and a second inner conductor (10’) of a mating coaxial connector (29).

33. The coaxial connector assembly (27) according to claim 32, wherein a base element (4) of the coaxial connector (1 ) and the base element (4’) of the mating coaxial connector (29) are one piece.

34. The coaxial connector assembly (27) according to claim 32 or 33, wherein the intermediate element (28) is arranged in a recess with an opening perpendicular to the longitudinal direction (x).

35. The coaxial connector assembly (27) according to one of claims 32 to 34, wherein the intermediate element (28) is a signal attenuator (30) which comprises a substrate layer (31 ) and a first and second signal contact tab (32, 32), which are in the connected state of the coaxial connector assembly(27) contacted by the spring elements (11 , 1 T) of the first coaxial connector(1 ) and the mating coaxial connector (29).

36. The coaxial connector assembly (27) according to claim 35, wherein in the connected state of the coaxial connector assembly (27) the first contact tab (32) is contacted by the spring element (11 ) of the first coaxial connector (1 ) and the second contact tab (33) is contacted by the spring element (1 T) of the mating coaxial connector (29).

37. A filter element (37) comprising a conductor (38) with a sinusoidal or meandering pattern along a longitudinal axis (x).

38. The filter element (37) according to claim 37, wherein the segment spacing (P) between the local maxima of the sinusoidal pattern or the bends of the meandering pattern along the longitudinal axis (x) is chosen such that the distance between neighboring local maxima is at most five times the structural diameter (DS) of the conductor (38), preferably four times, more preferably three times.

39. The filter element (37) according to one of claims 37 or 38, wherein the amplitude (DL) of the sinusoidal pattern or lateral deflection (DL) of the meandering pattern is more than 3 mm divided by the square root of the relative permittivity (sr) of the surrounding dielectric.

40. The filter element (37) according to one of claims 37 to 39, wherein the conductor (38) is embedded in a compound (39), preferably a dielectric pol- ymer.41 . The filter element (37) according to claim 40, wherein the compound (39) comprises metallic or dielectric lossy particles causing a variation of complex permittivity (E’(W) + i E”(W)) with the frequency of a signal sent through the filter element.

42. The coaxial connector assembly (27) according to one of claims 32 to 36, wherein the intermediate element (28) is a filter element (37) according to one of claims 37 to 41.

43. A coaxial connector assembly (27) comprising a coaxial connector (1 ), an array of coaxial connectors (23) or a cable assembly (22), wherein an intermediate element (28) is arranged between a first inner conductor (10) of the coaxial connector (1 ) and a second inner conductor (10’) of a mating coaxial connector (29), wherein the intermediate element (28) is a filter element (28) according to one of claims 37 to 41 .

44. The coaxial connector assembly (27) according to claim 43, wherein a base element (4) of the coaxial connector (1 ) and the base element (4’) of the mating coaxial connector (29) are one piece.

45. The coaxial connector assembly (27) according to one of claims 43 or 44, wherein the intermediate element (28) is arranged in a recess with an opening perpendicular to the longitudinal direction (x).

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