EP4439861A1 - Improved transition between a central contact of a coaxial component and a transmission line, especially a radio frequency (rf) transmission line. - Google Patents

Abstract

The invention relates to a transition (1) between a central contact (2) of a coaxial component (10), and a transmission line (30) of a circuit (3, 3', 3"), in particular radiofrequency (RF), the central contact comprising a cylindrical front part (23) and a rear part (21), in the extension of its front part, in contact and fixed to the transmission line by a solder (B), the rear part (21) comprising at least one material recess (22), delimiting a volume forming a reserve for the solder (RB).

Description

Technical field

The present invention relates to the field of circuits whose operating frequencies can be broadband ranging from CC (acronym for Direct Current) or DC (acronym for “Direct Current”) to radio frequencies (RF).

It relates more particularly to a transition between a central contact of a radio frequency (RF) coaxial component and an RF transmission line.

In the context of the invention, the term "transition" should be understood as designating a passive connection making it possible to pass from a coaxial medium for propagating a signal in a wide band ranging from DC to radio frequencies (RF), to another non-coaxial medium. By radio frequency, we mean the usual meaning, namely an electromagnetic wave frequency located between 3 KHz and 300 GHz. The frequency band concerned may be DC-67GHz, DC-70 GHz, DC-100 GHz or beyond.

The invention aims to improve such a transition, in particular for very small central contact diameters and transmission line dimensions.

Typically this can be a center contact outer diameter of less than 0.8mm.

Typically, the transmission line propagates the electromagnetic wave according to the Transverse Electro-Magnetic (TEM) mode.

Although described with particular reference to an application between a coaxial line and a planar line, the invention applies to all passive or active devices with central contact of a coaxial component, in particular RF, such as an attenuator, divider, combiner, load, coupler and to all transmission line circuits, such as a strip line, a micro-strip, a coplanar line or a suspended line.

A stripline is a transmission line surrounded by a dielectric material and suspended between two ground planes on the inner layer(s) of a printed circuit board (PCB).

A microstrip line is a transmission line routed on an outer layer of a printed circuit board and isolated from a ground plane by a dielectric material.

A coplanar line is a transmission line on a dielectric material, formed by a conductive track bordered on each side by a conductive return line.

A suspended line is a transmission line routed on an outer layer of a printed circuit board, surrounded by a layer of air on each side of the circuit board. Each layer of air is itself covered by an outer ground plane.

Prior art

In the field of radio frequency (RF) signal transmission, it is known to use attenuators and loads with coaxial center contact and transmission lines in the form of a planar line.

It should be remembered here that an attenuator is used to reduce the power of the RF signal, in particular to protect electronic equipment, while a load's primary function is to absorb an RF signal and dissipate it in the form of heat.

Currently, coaxial attenuators and loads are designed with ceramic substrate circuits, such as _Al2O3 , AlN or _quartz .

We have represented to the Figures 1 and 1A , a transition, generally designated by the reference numeral 1, as currently implemented in an existing RF coaxial attenuator.

The transition 1 between a central contact 2 in the form of a cylindrical pin in its front part and a strip line 30 of the circuit 3 comprises a solder B. More precisely, the central contact 2 comprises a semi-cylindrical rear part delimited by a flat 20 which is soldered by means of the solder B on the strip line 30.

Then, these components linked by the transition 1 thus formed are secured to a component, called cartridge 4, by means of another solder on conductive lines 31 at the periphery of the dielectric support 32 of the circuit 3. These soldered lines 31 suspend the circuit 3 in the ground conductor constituted by the cartridge 4.

The attenuator further comprises another central contact in the form of a socket 5 in which pin 2 is connected and a spacer 6 around these two central contacts 2, 5.

For many applications, there is a need to design attenuators and loads that can transmit signals at increasingly higher frequencies, particularly up to 67 GHz or even beyond.

This increase in frequency implies a reduction in the diameters of the central contacts, typically less than 0.8 mm, and in the dimensions of the transmission lines of the circuits, which generates a greater relative impact on the volumes of solder and their associated quantity, with various related drawbacks which the inventors may have been confronted with.

First, transitions 1 such as those shown in figure 1 require significant control of the solder B, particularly its quantity, because this parameter strongly influences the frequency response, i.e. the RF parameters of the attenuator or the load depending on the frequency of the transmitted signal.

Indeed, the variations in the amount of solder B generate a geometric variation around the rear part of the central contact 2 which is coated by the solder B, which results in a significant variation in the RF performance of the attenuator. This is illustrated in Figures 2 to 3B in which the Figures 2 to 2B show a first brazing B of different volume and shape from the second brazing B shown in Figures 3 to 3B .

The limitations of current technologies make it difficult, if not impossible, to control the quantity of solder sufficiently to ignore the influence on the frequency response.

Furthermore, the axial position in the cartridge 4, of the transmission line 30 brazed to the central contact 2 is difficult to control with very good precision. Thus, the variations in electrical impedance (adaptation variations), which are linked to the machining tolerances and the relative positions of the parts, and which make it possible to optimize the Standing Wave Ratio (SWR), cannot therefore be precise. This causes significant dispersions introducing large variations in electrical performance. This phenomenon is all the more significant at high frequency.

In more detail, the relative position of the central contact 2 with respect to the edge of the dielectric substrate 32 of the circuit 3 may be imprecise, due to the method of cutting the substrates. Indeed, the cutting of the circuits is carried out by grooving then breaking between the different circuits of the same dielectric substrate plate. However, a break has an irregular profile, which in fact induces a positioning of the central contact 2 with respect to the circuit 3, which is not reproducible both in distance and in angle. This is illustrated in Figures 4A and 4B showing two different configurations of relative position of central contact 2 relative to circuit 3, respectively without space between the lateral edge of circuit 3 and central contact 2, and with a space E between them.

These central contact position defects result in variations in the characteristic impedance of the RF line comprising the transmission line 30 and the central contact 2, which reduces the signal transmission performance, even more so at very high frequencies. Finally, the dimensional reduction of the attenuator parts, imposed by the increase in frequency as mentioned above, leads to a reduction in the contact areas intended to receive the brazing and therefore to a reduction in the quantities of brazing B. The reduction in these areas, and therefore in the surfaces facing the brazed parts, results in a reduction in their mechanical strength.

There is therefore a need to improve the transitions, particularly radio frequency (RF), between a central contact of a coaxial component and a transmission line, particularly in order to overcome the aforementioned drawbacks.

The invention aims to meet all or part of this need.

Disclosure of the invention

To do this, the invention relates, according to one of its aspects, to a transition between a central contact of a coaxial component and a transmission line of a circuit, in particular radiofrequency (RF), the central contact comprising a cylindrical front part and a rear part, in the extension of its front part, in contact and fixed to the transmission line by a solder, the rear part comprising at least one material recess, delimiting a volume forming a reserve for the solder.

According to an advantageous embodiment, the flat rear part integrating the material recess is delimited by two flat and parallel faces.

According to an advantageous embodiment, the rear part is a right parallelepiped or a trapezoidal cross-section shape.

Preferably, the height between the two flat and parallel faces being between 0.1 and 0.3 mm, preferably between 0.13 and 0.18 mm.

Advantageously, the material recess opens out depending on the height.

According to an advantageous embodiment variant, the material recess also opens onto at least one free end of the rear part of the central contact.

According to an advantageous embodiment variant, the emerging material recess is at least partly cylindrical or parallelepipedal in shape.

Preferably, the cylindrical front part being distant from the circuit.

Advantageously, the distance between the cylindrical part of the central contact and the edge of the facing circuit is between 0.1 and 0.8 mm, preferably between 0.35 and 0.45 mm.

• le circuit peut être du type à micro-ruban suspendu, comprenant un substrat diélectrique dont une face principale comprend la ligne de transmission sous la forme d'un micro-ruban, et des lignes conductrices de masse destinées à être brasées avec une pièce du composant coaxial, de sorte à suspendre le circuit dans un conducteur de masse constitué par ladite pièce;
• le circuit peut être du type coplanaire, comprenant un substrat diélectrique dont une face principale comprend la ligne de transmission sous la forme d'un ruban, insérée dans un plan de masse coplanaire et à distance S du ruban.

Several advantageous configurations can be considered:

• the circuit may be of the suspended microstrip type, comprising a dielectric substrate of which a main face comprises the transmission line in the form of a microstrip, and ground conductive lines intended to be soldered with a part of the coaxial component, so as to suspend the circuit in a ground conductor constituted by said part;
• the circuit may be of the coplanar type, comprising a dielectric substrate of which a main face comprises the transmission line in the form of a strip, inserted in a coplanar ground plane and at a distance S from the strip.

The transition according to the invention is advantageously configured to operate from direct current (DC) to 100 GHz, preferably from DC to 70 GHz.

The invention also relates to a passive or active electronic device, in particular radiofrequency (RF), comprising at least one transition as described above.

A passive electronic device constituting a coaxial component selected from an attenuator, a divider, a coupler, a combiner, a load.

According to an advantageous embodiment, the device according to the invention, in particular as an attenuator, comprises a cartridge, as a part of the coaxial component, delimited by a side wall comprising at least one electrically conductive region and inside which the circuit is fixed, at least one of the conductive ground lines being connected to said electrically conductive region by at least one electrical connection provided by a solder, said side wall being crossed by a through-hole extending over the thickness of said side wall and providing direct access to the electrical connection to establish or control said electrical connection there.

The access hole(s) in the side wall of the cartridge allow(s) easy access to the electrical connection area, to establish or check the latter, which is particularly advantageous when high quality electrical contact must be guaranteed between the component and the cartridge.

Thus, the invention essentially consists of a transition between a central contact of a coaxial component and a transmission line of a circuit, in particular radiofrequency (RF), with a central contact whose rear part comprises a material recess delimiting a volume forming a solder reserve and is positioned directly on the transmission line, to establish the electrical contact. The connection of the central contact to the transmission line is made by means of a solder.

• un moindre impact de la brasure sur les performances RF du composant qui intègre la transition, du fait de l'évidement de matière qui définit la réserve de brasure ;
• une meilleure maîtrise de la forme de la brasure solidarisant le contact central à la ligne de transmission, grâce à la forme plate de la partie arrière du contact central comprenant des faces planes et parallèles ; ce qui induit une réduction des variations des performances sur le signal transmis, notamment RF ;
• une meilleure tenue mécanique de la transition par l'augmentation possible de longueur des arêtes de contact entre partie arrière du contact central et ligne de transmission, par la présence de l'évidement de matière débouchant ;
• une réduction de l'effet du positionnement du contact central relativement au circuit supportant la ligne de transmission, du fait de la longueur de la partie arrière plate du contact central qui peut être ajustée pour éloigner la partie cylindrique de ce dernier.

The advantages of the invention compared to transitions according to the state of the art are numerous, among which we can cite:

• a lower impact of the solder on the RF performance of the component integrating the transition, due to the material recess which defines the solder reserve;
• better control of the shape of the solder securing the central contact to the transmission line, thanks to the flat shape of the rear part of the central contact comprising flat and parallel faces; which induces a reduction in variations in performance on the transmitted signal, particularly RF;
• better mechanical resistance of the transition by the possible increase in the length of the contact edges between the rear part of the central contact and the transmission line, by the presence of the emerging material recess;
• a reduction in the effect of the positioning of the central contact relative to the circuit supporting the transmission line, due to the length of the flat rear portion of the central contact which can be adjusted to move the cylindrical portion away from the latter.

Other advantages and characteristics of the invention will become more apparent upon reading the detailed description of examples of implementation of the invention given for illustrative and non-limiting purposes with reference to the following figures.

Brief description of the drawings

• [ Fig 1 ] there figure 1 represents in partial longitudinal section and in perspective view of a part of a coaxial load with a transition between central contact and RF transmission line, according to the state of the art.
• [ Fig 1A ] there Figure 1A is a partial longitudinal sectional view of the figure 1 .
• [ Fig 2], [Fig 2A], [Fig 2B ] THE Figures 2, 2A, 2B are perspective, longitudinal and rear section views of a state-of-the-art transition with a first brazing.
• [ Fig 3], [Fig 3A], [Fig 3B ] THE Figures 3, 3A, 3B are perspective views, in longitudinal and rear section of a transition according to the state of the art with a second brazing different from the first brazing, resulting from imperfect mastery of the brazing.
• [ Fig 4A], [Fig 4B ] THE Figures 4A and 4B are partial longitudinal sectional views of a portion of a coaxial attenuator with a transition between center contact and RF transmission line, according to the state of the art, showing two different configurations of relative position between the components, resulting from an imperfect control of the position of the rear part of the center contact on the circuit.
• [ Fig 5 ] there figure 5 is a partial perspective view of a portion of a coaxial attenuator with two transitions between central contact and RF transmission line, according to the invention.
• [ Fig 5A ] there Figure 5A is a detailed view of the figure 5 .
• [ Fig 6 ] there figure 6 resumes the figure 5 with further, in longitudinal section view, the cartridge and the spacers arranged coaxially around the transitions according to the invention.
• [ Fig 7 ] there figure 7 is a longitudinal sectional view of a coaxial attenuator in its entirety with two transitions as per the figures 5 And 6 .
• [ Fig 8A], [Fig 8B ] THE Figures 8A and 8B are partial perspective views of a transition according to the invention.
• [ Fig 9 ] there figure 9 is a partial perspective view illustrating the contact edge between the rear portion of a center contact without a material recess and a transmission line for making a solder transition.
• [ Fig 10 ] there figure 10 is a partial perspective view illustrating the contact edge between the flat rear portion of a central contact with a material recess emerging therefrom and a transmission line for producing a solder transition according to the invention.
• [ Fig 11 ] there figure 11 illustrates in partial longitudinal sectional view a portion of a coaxial attenuator with a transition according to the invention showing a relative position configuration between the components.
• [ Fig 12 ] there figure 12 illustrates in the form of a curve a simulation of a Standing Wave Ratio (SWR) according to the frequency, as obtained with a transition according to the state of the art and according to the invention.
• [ Fig 13], [Fig 14 ], [ Fig 15 ] THE figures 13, 14 , 15 illustrate, in partial perspective, a transition according to the invention with different variants of embodiment of material recess opening into the rear part of a central contact.
• [ Fig 16 ] there figure 16 is a cross-sectional view of a coplanar line according to a first circuit variant in accordance with the invention.
• [ Fig 17 ] there figure 17 is a cross-sectional view of a suspended microstrip line, according to a second circuit variant in accordance with the invention.
• [ Fig 18 ] there figure 18 illustrates in perspective an advantageous variant embodiment of a cartridge of a coaxial attenuator with at least one transition according to the invention.

Detailed description

Throughout the present application, the terms "front" and "rear" are to be understood in relation to a coaxial component implementing at least one transition between a central contact and a transmission line of a circuit according to the invention. Thus, the front part of a central contact is that intended to be coupled with another central contact.

For the sake of clarity, the same numerical reference is used for the same element of a transition according to the state of the art and a transition according to the invention.

THE Figures 1 to 4B have already been described in detail in the preamble. They will therefore not be commented on below.

It has been represented on the Figures 5 and 5A a part of a coaxial RF attenuator with two transitions according to the invention.

Each transition 1 between a central contact 2 in the form of a cylindrical pin in its front part and a suspended microstrip line 30 of an RF circuit 3 comprises a solder B.

More specifically, according to the invention, the central contact 2 comprises a flat rear part 21, in the form of a right parallelepiped, which is brazed by means of the brazing B on the line 30 in the form of a suspended micro-strip. The edges of the flat part 21 may be cylindrical.

The flat part 21 is positioned directly on the RF line, to establish the electrical contact and the connection of the contact on the line 30 is finalized by the solder B.

The circuit 3 is of the suspended microstrip type: it thus comprises a dielectric substrate 32, a main face of which supports both the transmission line 30 and two conductive ground lines 31 which extend to the periphery, each along a longitudinal edge of the substrate 32.

1. i/ dépôt d'une brasure B sur la ligne de transmission 30 en bord du circuit 3,
2. ii/ pose du contact central 2 avec sa partie arrière plate 21 sur la brasure B en bord du circuit 3,
3. iii/ passage en four pour réaliser le brasage et ainsi former la transition 1.

The method for carrying out a transition 1 according to the invention consists of the following steps:

1. i/ depositing a solder B on the transmission line 30 at the edge of the circuit 3,
2. ii/ installation of the central contact 2 with its flat rear part 21 on the solder B at the edge of the circuit 3,
3. iii/ passage in the oven to carry out the brazing and thus form transition 1.

Then, as shown in the figure 6 , these components linked by the transition 1 thus formed are secured to a component, called cartridge 4, for example by means of another solder on the conductive lines 31 at the periphery of the dielectric support 32 of the circuit 3. These ground lines 31 are intended to be soldered with a cartridge 4 of the coaxial attenuator, so as to suspend the circuit 3 in a ground conductor constituted by the cartridge 4.

The attenuator further comprises another central contact in the form of a male-type socket 5 at its free end, in which is connected the pin 2 of one of the two central contacts 2 and a spacer 6 around at least a portion of the central contact 2 and of the socket 5.

Pin 2 of the other of the two central contacts is connected to a female-type socket 50 at its free end, a spacer 6 also surrounding at least a portion of pin 2 and socket 50.

As illustrated in the figure 7 , the coaxial attenuator 10 further comprises two insulators 11. One of the insulators 11 is interposed between the pin 5 and a ground body 12 which is aligned with a first metal fixing body 13. The other of the insulators 11 is interposed between the socket 50 and a second metal fixing body 14.

Preferably, the rear part 21 of the central contact 2 has a material recess 22 opening over the entire height of this rear part 21.

In the illustrated example of the Figures 8A and 8B , this material recess 22 also opens onto the free end of the rear part 21 and has the shape of a straight parallelepiped groove.

These Figures 8A and 8B illustrate one of the advantages of a transition 1 according to the invention.

As can be seen, having a flat shape 21 limits the rise of the solder B along the height of this rear part 21 of the central contact. The existence of a sharp edge at the intersection 210 of the upper flat face and the free edge stops the propagation of the solder over the height of the rear part of the central contact. Indeed, generally the solder B will be limited to the height H of the flat, preferably of the order of 0.1 to 0.3 mm, preferably 0.13 to 0.18 mm. The variations in the height of the solder B are limited. This gives better control over the shape of the meniscus of the solder B than in the case of a semicylindrical rear part with a flat 20 as shown in Figures 2 to 3B . This reduces the variations in RF performance from one transition 1 to another. In other words, thanks to the flat part 21 of the central contact 2, reproducibility of the RF performance from one coaxial attenuator 10 to another produced using the same method is obtained.

The emerging material recess 22 also makes it possible to provide a volume which serves as a reserve for the solder RB. This reserve can therefore be more or less filled when the central contact 2 is placed on the solder. The level of this reserve filling has no effect on the RF performance of the coaxial attenuator 10. Indeed, this reserve RB, by absorbing more or less the excess solder B, makes it possible to greatly limit the impact of the quantity of solder on the performance of the attenuator 10.

Furthermore, the flat part 21 makes it possible to obtain good mechanical strength. The value of this strength is given by the length of the peripheral edges A of contact between this part 21 and the transmission line 30, as shown in the figure 9 .

As shown in the figure 10 , the through groove 22 makes it possible to increase the contact length A and therefore to increase the mechanical strength of the central contact 2 on the circuit 3.

Another advantage obtained by a transition 1 according to the invention is illustrated in figure 11 . The flat portion 21 of the central contact 2 is extended beyond the circuit 3, which makes it possible to guarantee the distance, or in other words the offset D, of the cylindrical portion 23 of the central contact 2 of the circuit 3. The offset is induced by a position of the central contact 2 relative to the edge of the circuit 3 which can vary according to a distance D. Preferably, the offset between the circuit edge and the cylindrical contact portion 23 is between 0.1 and 0.8 mm, preferably between 0.35 and 0.45 mm.

This offset thus makes transition 1 less sensitive to position defects of both the central contact 2 relative to the edge of circuit 3 and of the circuit subassembly 3 and central contact 2 secured by transition 1 relative to cartridge 4 of attenuator 10. It also makes it possible to avoid the finishing levels of the edges of circuit 3.

The variation in electrical impedance in zone Z at the free edge of circuit 3 is therefore not influenced by the relative position of the central contact with respect to the edge of circuit 3, as symbolized by the circled zone on the figure 11 . This helps to reduce the influence of the position of the central contact 2 on the RF performance of the attenuator 10.

The inventors simulated the standing wave ratio (SWR) as a function of frequency, for a coaxial attenuator 10 integrating two transitions 1 according to the invention, in comparison with a coaxial attenuator integrating two transitions according to the state of the art. The result of this simulation is shown in figure 12 .

There figure 12 shows two curves C1 and C2. Curve C1 represents the standing wave ratio for a coaxial attenuator comprising two transitions according to the state of the art, namely, for example with a central contact with a flattened semi-cylindrical rear part. Curve C2 represents the standing wave ratio for a coaxial attenuator comprising two transitions according to the invention. Curve C2 shows an improvement in the RF performance of the attenuator, over the frequency range DC - 70 GHz, since, for a given frequency, the standing wave ratio of C2 is lower than the standing wave ratio of C1 and approaches the value 1.

• l'extrémité libre 24 de la partie arrière 21 en forme de T délimitant deux rainures débouchantes de part et d'autre, chacune de forme substantiellement parallélépipédique,
• une rainure débouchante 25 sous la forme d'un cylindre creux au sein de la partie arrière 21,
• une rainure débouchante 26 sous la forme d'un cylindre creux débouchant sur la ligne de transmission 30 par un prolongement de forme parallélépipédique droite.

Different variations of material recess shapes emerging are illustrated in Figures 13 to 15 which show respectively:

• the free end 24 of the rear part 21 in the shape of a T delimiting two grooves opening out on either side, each of substantially parallelepiped shape,
• a through groove 25 in the form of a hollow cylinder within the rear part 21,
• a through groove 26 in the form of a hollow cylinder opening onto the transmission line 30 by a straight parallelepiped-shaped extension.

The coaxial attenuator 10 as previously described implements a suspended micro-strip type circuit 3.

Other circuit variants can be implemented within the scope of the invention.

There figure 16 shows a circuit 3' of the coplanar type on which a transition 1 according to the invention can be produced. This circuit 3' thus comprises a dielectric substrate 32, a main face of which comprises the transmission line 30 in the form of a strip, inserted in a coplanar ground plane 34 and at a distance S from the strip. The other main face opposite that of the transmission line 30, comprises a ground plane 33.

There figures 17 shows a 3" circuit of the suspended micro-strip type on which a transition 1 according to the invention can be produced. The 3" circuit in fact comprises a dielectric substrate 32, a main face of which comprises the transmission line 30 in the form of a strip, and which is inserted between two ground planes 33, 35.

There figure 18 shows an advantageous variant embodiment of a cartridge 4 integrating within it at least one transition 1 according to the invention. Here, at least one side wall 40 comprises a through hole 41 extending over the thickness of the side wall 40 and providing direct access to an electrical connection made by soldering between one of the ground lines 31 of the circuit 3 of the transition and an electrically conductive region 42 of the side wall. Direct access thus makes it possible to establish or control said electrical connection.

Other variations and improvements may be provided without departing from the scope of the invention.

If in the examples illustrated, the rear part 21 of the central contact 2 is a right parallelepiped, other shapes with parallel flat faces, one of which is in contact with the transmission line, can be envisaged.

Other forms of material hollowing out than those illustrated can be envisaged.

Claims (15)

Transition (1) between a central contact (2) of a coaxial component (10), and a transmission line (30) of a circuit (3, 3', 3"), in particular radiofrequency (RF), the central contact comprising a cylindrical front part (23) and a rear part (21), in the extension of its front part, in contact and fixed to the transmission line by a solder (B), the rear part (21) comprising at least one material recess (22), delimiting a volume forming a reserve for the solder (RB), adapted to absorb more or less the excess solder (B). Transition (1) according to claim 1, the rear part (21) integrating the material recess being flat, delimited by two flat faces, preferably parallel. Transition (1) according to claim 2, the rear part (21) being a right parallelepiped or a trapezoidal cross-sectional shape. Transition (1) according to claim 2 or 3, the height between the two flat faces being between 0.1 and 0.3 mm, preferably between 0.13 and 0.18 mm. Transition (1) according to one of the preceding claims, the material recess opening out according to the height. Transition (1) according to claim 5, the material recess further opening onto at least one free end of the rear part of the central contact. Transition (1) according to claim 5 or 6, the emerging material recess being at least partly cylindrical or parallelepipedal in shape. Transition (1) according to one of the preceding claims, the cylindrical front part (23) of the central contact (2) being distant from the circuit. Transition (1) according to claim 8, the distance D between the cylindrical part of the central contact (2) and the edge of the facing circuit being between 0.1 and 0.8 mm, preferably between 0.35 and 0.45 mm. Transition (1) according to one of the preceding claims, the circuit (3) being of the suspended micro-strip type, comprising a dielectric substrate (32) of which a main face comprises the transmission line (30) in the form of a micro-strip, and conductive ground lines (31) intended to be soldered with a part of the coaxial component, so as to suspend the circuit in a ground conductor constituted by said part. Transition (1) according to one of claims 1 to 9, the circuit (3') being of the coplanar type, comprising a dielectric substrate (32) of which a main face comprises the transmission line (30) in the form of a strip, inserted in a coplanar ground plane (34) and at a distance S from the strip. Transition (1) according to one of claims 1 to 11, configured to operate from direct current (DC) to 100 GHz, preferably from DC to 70 GHz. Passive or active electronic device, in particular radiofrequency (RF), comprising at least one transition (1) according to one of the preceding claims. Passive electronic device according to claim 13, constituting a coaxial component (10) selected from an attenuator, a divider, a combiner, a coupler and a load. Electronic device according to claim 14 in combination with claim 10, in particular as an attenuator, comprising a cartridge (4), as a part of the coaxial component, delimited by a side wall (40) comprising at least one electrically conductive region (42) and inside which the circuit (3) is fixed, at least one of the conductive ground lines (31) being connected to said electrically conductive region by at least one electrical connection provided by a solder, said side wall being crossed by a through-hole (41) extending over the thickness of said side wall and providing direct access to the electrical connection to establish or control said electrical connection there.

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