Radio frequency device and method for increasing the breakdown power of a radio frequency device

Abstract

This radio frequency device (2), configured to perform at least one radio frequency function, comprises a metallic structure (4) defining an internal volume, at least one power injection element (16) at an inlet of the metallic structure (4), and at least one power extraction element (18) at an outlet of the metallic structure (4), arranged such that an electromagnetic wave is capable of propagating from said power injection element (16) to said power extraction element (18), at least a portion of the internal volume defined by the metallic structure (4) being filled with a solid dielectric foam (24) having a relative dielectric permittivity of less than 1.5. (See Figure 1 for abbreviations.)

Description

Title of the invention: Radiofrequency device and method for increasing the breakdown power of a radiofrequency device Technical field

[0001] The technical field of the invention is radiofrequency devices, i.e. devices whose working frequency is between 3 kilohertz and 300 gigahertz, in particular radiofrequency devices presenting a risk of electric arc. Prior techniques

[0002] The conditions of use of a radiofrequency device may cause a phenomenon of ionization of a dielectric gas present inside or near the radiofrequency device and induce a risk of electric arc, in particular when the power to which the radiofrequency device is subjected is increased.

[0003] It is sometimes not possible to modify the dimensions or shape of the radiofrequency device so as to limit the risk of electric arcing, for example in the case of a radiofrequency device already manufactured or validated within the framework of a particular protocol.

[0004] The radiofrequency device may also be permeable to gases and be subject to pressure variations modifying the risk of electric arcing. Indeed, according to Paschen's law, the breakdown voltage of a gas depends on its pressure.

[0005] In particular, when the radiofrequency device is carried on board a spacecraft such as a rocket and is permeable to gases, the pressure to which the radiofrequency device is subjected decreases during the flight phase of the spacecraft as the altitude of the spacecraft increases.

[0006] Making the radiofrequency device hermetic can be an expensive operation.

[0007] The present invention aims to overcome all or part of the aforementioned drawbacks, and in particular to increase the breakdown power of a radiofrequency device, i.e. the minimum power from which an electric arc can appear in the radiofrequency device by limiting the effects on its performance, and this, at low cost. Statement of the invention

[0008] The present invention relates to a radiofrequency device configured to perform at least one radiofrequency function, the radiofrequency device comprising a metal structure defining an interior volume, at least one power injection member at an input of the metal structure and at least one power extraction member at an output of the metal structure arranged so that an electromagnetic wave is capable of propagating from said power injection member to said power extraction member, at least part of the interior volume defined by the metal structure being filled with a solid dielectric foam having a relative dielectric permittivity of less than 1.5.

[0009] It is understood that for a micro-inhomogeneous dielectric material, it is the effective permittivity which will be considered.

[0010] The interior volume defined by the metal structure may further comprise a dielectric gas. In particular, the dielectric gas may fill cavities formed by solid constituents of the solid dielectric foam.

[0011] The relative dielectric permittivity considered for the solid dielectric foam is therefore the effective permittivity of the solid dielectric foam, i.e. a weighted average of the relative dielectric permittivities of the solid constituents of the solid dielectric foam and of the dielectric gas filling the cavities formed by said solid constituents, the average being weighted according to the volume fraction of said solid constituents and of the dielectric gas.

[0012] For example, the relative dielectric permittivity of a monolithic block of solid Teflon material is about 2.1. The relative dielectric permittivity of a block of the same volume hollowed out so as to reduce its mass by half is about 1.55, corresponding to the average of the relative dielectric permittivity of Teflon and the relative dielectric permittivity of the air filling the recesses of the hollowed-out block.

[0013] The term “radiofrequency device configured to perform at least one radiofrequency function” means that the radiofrequency device is capable of implementing electromagnetic waves in order to perform said radiofrequency function.

[0014] The radiofrequency function performed by the radiofrequency device is, for example, a waveguide, filter, multiplexer, demultiplexer, adder, divider, polarizer, diplexer, triplexer, polarization diplexer, or coupler function.

[0015] The radiofrequency function performed by the radiofrequency device can be broken down, at any point of the device, into a sum of electromagnetic waves.

[0016] The breakdown power, i.e. the minimum power from which an electric arc can appear in the radiofrequency device comprising the solid dielectric foam filling the part of the interior volume, is greater than the minimum power from which an electric arc can appear in the same radiofrequency device whose interior volume comprises only a dielectric gas, and is therefore devoid of solid dielectric foam.

[0017] The solid dielectric foam creates in particular barriers preventing the acceleration of electrons in the interior volume defined by the metallic structure of the radiofrequency device, and increases the dielectric rigidity in the volume that it occupies com- compared to a dielectric gas occupying the same volume.

[0018] The relative dielectric permittivity of less than 1.5 of the solid dielectric foam ensures a frequency response of the radiofrequency device close to the same radiofrequency device whose interior volume comprises only a dielectric gas.

[0019] The metal structure may be permeable to the dielectric gas.

[0020] The radiofrequency device may be intended to undergo pressure variations.

[0021] The radiofrequency device may be intended to equip a spacecraft, in particular a satellite or rocket.

[0022] The dielectric loss tangent of the solid dielectric foam may be less than 5.103, in particular less than 5.104.

[0023] The dielectric loss tangent of the solid dielectric foam less than 5.103 makes it possible to limit the losses of the radiofrequency device.

[0024] The radiofrequency device may be intended to perform at least one radiofrequency function over a working frequency range included in an interval between 3 kilohertz and 300 gigahertz, the relative dielectric permittivity of the solid dielectric foam being less than 1.5 over the working frequency range of the radiofrequency device.

[0025] The relative dielectric permittivity of the solid dielectric foam may be at least equal to 1.01, in particular over the working frequency range of the radiofrequency device.

[0026] Preferably, the relative dielectric permittivity of the solid dielectric foam is at least equal to 1.01 and at most equal to 1.20, in particular over the working frequency range of the radiofrequency device. More preferably still, the relative dielectric permittivity of the solid dielectric foam is at least equal to 1.01 and at most equal to 1.08, in particular over the working frequency range of the radiofrequency device.

[0027] Optionally, the solid dielectric foam fills the entire interior volume defined by the metal structure.

[0028] The solid dielectric foam can be bonded to the metal structure.

[0029] The metal structure may comprise at least one resonator.

[0030] The metal structure may comprise at least one elongated metal resonator, the solid dielectric foam being in contact with said elongated metallic resonator.

[0031] According to a particular design, said elongated metal resonator may extend projecting from a first metal wall of the metal structure towards a second metal wall so that the free end of said elongated metal resonator remains at a distance from the second metal wall of the metal structure, the solid dielectric foam being at least in contact with the free end of said re- elongated metal sonator.

[0032] The metal structure may form at least one resonant cavity, the solid dielectric foam at least partially filling said resonant cavity.

[0033] According to a particular design, the metal structure comprises a succession of large segments and small segments, each of the large segments constituting a resonant cavity, at least a portion of at least one of these small or large segments being filled with solid dielectric foam.

[0034] The metal structure can form at least one waveguide, the solid dielectric foam internally filling at least part of said waveguide.

[0035] The present invention also relates to a method for increasing a breakdown power of a radiofrequency device configured to perform at least one radiofrequency function, the radiofrequency device comprising a metal structure defining an interior volume, at least one power injection member at an inlet of the metal structure and at least one power extraction member at an outlet of the metal structure arranged so that an electromagnetic wave is able to propagate from said power injection member to said power extraction member, the method comprising at least one step of filling at least a portion of the interior volume defined by the metal structure with a solid dielectric foam having a relative dielectric permittivity of less than 1.5.

[0036] By filling the part of the interior volume defined by the metal structure with the solid dielectric foam, a volume of dielectric gas initially present in the interior volume is replaced by solid dielectric foam so as to increase the dielectric strength of the dielectric medium present in the interior volume defined by the metal structure of the radiofrequency device. Thus, the minimum power for the occurrence of an electric arc in the radiofrequency device is increased.

[0037] Solid dielectric foam represents a simple to implement, inexpensive and lightweight solution to increase the breakdown power of the radiofrequency device.

[0038] The method may comprise a prior step of digital simulation of a mapping of an electromagnetic field in the interior volume defined by the metal structure entirely filled with the dielectric gas, the filling step then being carried out so that the solid dielectric foam is arranged at least at the locations of the interior volume defined by the metal structure at which the simulated electromagnetic field exceeds a predetermined threshold.

[0039] The radiofrequency device may be a radiofrequency device as defined previously.

[0040] The solid dielectric foam may be a solid dielectric foam as defined above. Brief description of the drawings

[0041] Other aims, characteristics and advantages of the invention will appear on reading the following description, given solely by way of non-limiting example and made with reference to the appended drawings in which:

[0042] [Fig.l] schematically illustrates a radiofrequency device according to a first exemplary embodiment of the invention;

[0043] [Fig.2] illustrates the radiofrequency device of [Fig.l] after assembly of the frame metallic with top and bottom covers;

[0044] [Fig.3] is a simulation of S parameters in dB of the radiofrequency device of [Fig.2] without solid dielectric foam for frequencies between 1.8 and 3.0 GHz;

[0045] [Fig.4] is a simulation of S parameters in dB of the radiofrequency device of [Fig.2] comprising the solid dielectric foam for frequencies between 1.8 and 3.0 GHz;

[0046] [Fig.5] schematically illustrates the metallic structure of a radiofrequency device according to a second exemplary embodiment of the invention;

[0047] [Fig.6] schematically illustrates the metallic structure of a radiofrequency device according to a third exemplary embodiment of the invention;

[0048] [Fig.7] schematically illustrates the metallic structure of a radiofrequency device according to a fourth exemplary embodiment of the invention;

[0049] [Fig.8] schematically represents a method for increasing the dielectric strength of a radiofrequency device according to an exemplary embodiment of the invention; and

[0050] [Fig.9] illustrates the step of numerical simulation of a mapping of an electromagnetic field for the radiofrequency device of [Fig.l]. Detailed description

[0051] [Fig.l] represents a radiofrequency device 2, in particular an interdigital radiofrequency filter.

[0052] The radiofrequency device 2 comprises a metallic structure 4 composed of a metallic frame 6 formed of first, second, third and fourth metallic walls 8, 10, 12, 14.

[0053] The second metal wall 10 of the frame 6 is opposite the first metal wall 8 of the frame 6, and extends at a distance from the first metal wall 8, here parallel.

[0054] The fourth metal wall 14 of the frame 6 is opposite the third metal wall metal 12 of the frame 6, and extends at a distance from the third metal wall 12, here parallel.

[0055] The third and fourth metal walls 12, 14 of the frame 6 each join the first and second metal walls 8, 10 of the frame 6, being here orthogonal to the first and second metal walls 8, 10 of the frame 6.

[0056] The radiofrequency device 2 comprises a power injection member 16 arranged at an input of the radiofrequency device 2 and passing through the third metal wall 12 of the frame 6, and a power extraction member 18 arranged at an output of the radiofrequency device 2 and passing through the fourth metal wall 14 of the frame 6.

[0057] The metallic structure 4 of the radiofrequency device 2 comprises a first group of elongated metallic resonators 20 and a second group of elongated metallic resonators 22.

[0058] The first group of elongated resonators 20 comprises a plurality of elongated resonators 20, here three elongated resonators 20, each extending projecting from the first metal wall 8 of the frame 6 towards the second metal wall 10 of the frame 6.

[0059] The second group of elongated resonators 22 comprises a plurality of elongated resonators 22, here two elongated resonators 22, each extending projecting from the second metal wall 10 of the frame 6 towards the first metal wall 8 of the frame 6.

[0060] The elongated resonators 20, 22 of the first and second groups of elongated resonators 20, 22 are arranged in the frame 6 in an alternating manner. Thus, by traveling through the frame 6 in the direction from the third metal wall 12 to the fourth metal wall 14, one encounters alternately an elongated resonator 20 of the first group of elongated resonators 20, then an elongated resonator 22 of the second group of elongated resonators 22.

[0061] The thickness of each elongated resonator 20, 22 is greater than or equal to 0.5 times the width of the elongated resonator 20, 22 and less than or equal to 2.0 times the width of the elongated resonator 20, 22, the length of the elongated resonator 20, 22 being greater than its thickness and its width.

[0062] A space is provided between each elongated resonator 20 of the first group of elongated resonators 20 and the second metal wall 10, the free end of each elongated resonator 20 of the first group of elongated resonators 20 remaining at a distance from the second metal wall 10.

[0063] A space is provided between each elongated resonator 22 of the second group of elongated resonators 22 and the first metal wall 8, the free end of each elongated resonator 22 of the second group of elongated resonators 22 remaining at a distance from the first metal wall 8.

[0064] The frame 6 also comprises a plurality of tapped holes 26 for assembling the frame 6 with other elements.

[0065] As visible in [Fig. 2], the metal structure 4 of the radiofrequency device 2 further comprises an upper metal cover 28 and a lower metal cover 30 fixed to the metal frame 6, for example by means of screws and a part of the tapped holes 26 of the frame 6, the metal frame 6 thus being arranged between the upper cover 28 and the lower cover 30. The metal frame 6 and the upper and lower covers 28, 30 form a metal casing. Each elongated resonator 20, 22 of the metal structure 4 remains here at a distance from the upper and lower covers 28, 30.

[0066] The power injection and power extraction members 16, 18 are arranged so that an electromagnetic wave is able to propagate from the power injection member 16 to the power extraction member 18, in particular by interacting with the elongated resonators 20, 22 of the metal structure 4. The power injection and power extraction members 16, 18 each comprise, for example, a coaxial cable whose core is used as a power injection or extraction member 16, 18. Alternatively, the power injection member 16 and / or the power extraction member 18 could comprise an antenna, a waveguide, an iris or any other element making it possible to inject power into the radiofrequency device 2 or to extract power from the radiofrequency device 2.

[0067] The radiofrequency device 2 is thus adapted to implement electromagnetic waves.

[0068] The metal structure 4 comprising the metal frame 6, the first and second groups of elongated metal resonators 20, 22 and the upper and lower metal covers 28, 30 internally defines an interior volume comprising a dielectric gas whose relative dielectric permittivity is substantially equal to 1.00, the relative dielectric permittivity or dielectric constant linking the permittivity of the gas to the permittivity of the vacuum e0. When the radiofrequency device 2 is subjected to too high an input power, an electric arc can form in the interior volume, in particular around the free end of an elongated resonator 20, 22, through the dielectric gas.

[0069] In order to increase the minimum breakdown power of the radiofrequency device 2, the latter further comprises foam 24 formed from a solid dielectric material filling each of the spaces provided between the free end of an elongated resonator 20, 22 of the metal structure 4 and a metal wall 8, 10 of the frame 6, here in the form of blocks of solid dielectric foam 24.

[0070] The solid dielectric foam 24 has a relative dielectric permittivity lower than 1.5. The solid constituents of the solid dielectric foam 24 internally form cavities trapping the dielectric gas, making it possible to increase the dielectric strength of the dielectric present in the radiofrequency device and thus increase the minimum breakdown power of the radiofrequency device 2.

[0071] A Rohacell® radiofrequency solid dielectric foam is, for example, used. Such a solid dielectric foam 24 has, for example, a relative dielectric permittivity of between 1.03 and 1.07, in particular depending on the density of the solid dielectric foam 24. Other references of solid dielectric foam 24 may be suitable, for example those from the supplier LAIRD®.

[0072] In the example shown, each block of foam 24, in particular obtained by machining a solid dielectric foam, is in contact on the one hand with the free end of an elongated resonator 20, 22 of the metal structure 4, and on the other hand with a metal wall 8, 10 of the frame 6, the block of solid dielectric foam 24 being bonded to the metal structure 4. Alternatively, the solid dielectric foam 24 could be machined so as to surround each elongated resonator 20, 22 of the metal structure 4. As a variant, the solid dielectric foam 24 could be machined so as to be complementary to the metal structure 4, that is to say so as to fill the entirety of the interior volume defined by the metal structure 4 comprising the metal frame 6, the first and second groups of metal elongated resonators 20, 22 and the upper and lower metal covers 28 and 30.

[0073] Advantageously, the dielectric loss tangent of the solid dielectric foam 24, corresponding to the tangent of the ratio between the imaginary part and the real part of the complex dielectric permittivity of the dielectric translating the losses of the dielectric at the frequency of interest, is less than 5.103, and more advantageously less than 5.104. Thus, the behavior of the radiofrequency device 2 is close to the radiofrequency device 2 without the solid dielectric foam 24.

[0074] The radiofrequency device 2 is in particular intended to equip a spacecraft, in particular a rocket or a satellite, for example intended to equip a radiofrequency transmitter of the spacecraft.

[0075] The radiofrequency device 2, in particular the metal casing formed by the metal frame 6 and the upper and lower covers 28, 30, is permeable to gases due to the method of assembling the radiofrequency device 2 itself or the connection of the radiofrequency device 2 with another radiofrequency device. Thus, during the flight of the spacecraft, the pressure in the interior volume varies. When the altitude of the spacecraft increases, the pressure in the interior volume decreases, the minimum breakdown voltage of the radiofrequency device 2 decreasing accordingly. The presence of the solid dielectric foam 24 in the interior volume defined by the metallic structure 4 can prevent the occurrence of an electric arc in the radiofrequency device 2 without having to modify its internal structure or its dimensions to take into account the variation in pressure in the interior volume, nor make the device hermetic.

[0076] [Fig. 3] represents numerical simulations of transmission and reflection of an electromagnetic field at the input and output ports of the radiofrequency device 2 illustrated in [Fig. 2], i.e. at the level of the power injection member 16 and the power extraction member 18, when the radiofrequency device 2 is devoid of solid dielectric foam 24. More precisely, [Fig. 3] represents simulations of parameters S, namely the parameters Su and S2p

[0077] The simulations were carried out for frequencies ranging from 1.8 to 3.0 gigahertz, an input and output impedance of 50 Ohms, the results being represented in decibels.

[0078] Curve 32 in thick line represents a digital simulation of the reflection of the electromagnetic field at the input of the radiofrequency device 2, curve 34 in thin line representing a digital simulation of the transmission of the electromagnetic field from the power injection member 16 to the power extraction member 18.

[0079] As shown, the radiofrequency device 2 here has a bandpass filter function, the input reflection curve 32 being attenuated by more than 10 decibels for frequencies between 2.16 gigahertz and 2.52 gigahertz, the transmission curve 34 being attenuated by more than 10 decibels for frequencies below 2.08 gigahertz and for frequencies above 2.62 gigahertz. In addition, between 2.16 gigahertz and 2.52 gigahertz, the transmission curve 34 is attenuated by less than 0.5 decibels.

[0080] The input reflection curve 32 has a plurality of resonances whose frequency positions are determined at least by the arrangement of the elongated resonators 20, 22, and therefore by the couplings between the elongated resonators 20, 22 and between the elongated resonators 20, 22, the metal walls 8, 10, 12, 14 of the metal frame 6 and the upper and lower metal covers 28, 30.

[0081] [Fig.4] represents numerical simulations of transmission and reflection of an electromagnetic field at the input and output ports of the radiofrequency device 2 illustrated in [Fig.2] when the radiofrequency device 2 comprises the solid dielectric foam blocks 24. More precisely, [Fig.4] represents simulations of S parameters, namely the parameters Su and S2i.

[0082] The simulations were carried out for frequencies ranging from 1.8 to 3.0 gigahertz, an input and output impedance of 50 Ohms, the results being represented in decibels.

[0083] Curve 36 in thick line represents a digital simulation of the reflection of the electromagnetic field at the input of the radiofrequency device 2, curve 38 in thin line representing a digital simulation of the transmission of the electromagnetic field from the power injection member 16 to the power extraction member 18.

[0084] As shown, the radiofrequency device 2 comprising the solid dielectric foam blocks 24 has a behavior close to the radiofrequency device 2 without solid dielectric foam 24. In particular, the radiofrequency device 2 comprising the solid dielectric foam blocks 24 also has a bandpass filter function, the input reflection curve 36 being attenuated by more than 10 decibels for frequencies between 2.14 gigahertz and 2.50 gigahertz, the transmission curve 38 being attenuated by more than 10 decibels for frequencies lower than 2.06 gigahertz and for frequencies higher than 2.60 gigahertz. In addition, between 2.16 gigahertz and 2.52 gigahertz, the transmission curve 38 is attenuated by less than 0.5 decibels.

[0085] [Fig. 5] represents the metallic structure 4 of a radiofrequency device 2, in particular of a corrugated filter, the metallic structure 4 comprising a succession of hollow parallelepiped segments of different dimensions jointly forming a hollow elongated envelope.

[0086] The metal structure 4 comprises a first hollow tubular segment here of rectangular section forming a first waveguide at a first end, a second hollow tubular segment here of rectangular section forming a second waveguide at a second end, and a plurality of hollow segments of different dimensions, in particular a plurality of hollow segments each of rectangular section, forming the impedance matching and the corrugations of the radiofrequency device 2 and arranged between the first and second tubular segments. Each corrugation of the radiofrequency device 2 constitutes a resonant cavity 40 whose dimensions partly define the resonant frequency of the radiofrequency device 2. Alternatively, all or some of the hollow segments of the metal structure 4 could be of different shapes, for example of circular, elliptical, square section, etc.

[0087] The radiofrequency device 2 also comprises a power injection member (not shown) connected to the first tubular segment, and a power extraction member (not shown) connected to the second tubular segment.

[0088] The metal structure 4 defines an interior volume in which solid dielectric foam 24 is arranged. The shape of the solid dielectric foam 24 is here complementary to the interior volume defined by the metal structure 4.

[0089] [Fig.6] represents the metallic structure 4 of a radiofrequency device 2, in particular of a bent rectangular section waveguide, the metallic structure 4 forming a hollow bent envelope filled with solid dielectric foam 24. Alternatively, the radiofrequency device 2 could be a bent waveguide of circular or elliptical section, a straight waveguide, a corrugated waveguide, a twisted waveguide, a ridged waveguide or "ridged waveguide" in Anglo-Saxon terms, or any other waveguide geometry.

[0090] [Fig.7] represents the metallic structure 4 of a radiofrequency device 2, in particular a “magic tee”, the metallic structure 4 being provided with three hollow parallelepiped segments arranged in the same plane, one of the three parallelepiped segments being orthogonal to the other two so as to form a “T” shaped structure, and a fourth hollow tubular segment orthogonal to the three parallelepiped segments and in contact with the three parallelepiped segments.

[0091] The metal structure 4 defines an interior volume in which solid dielectric foam 24 is arranged. The shape of the solid dielectric foam 24 is here complementary to the interior volume defined by the metal structure 4.

[0092] The radiofrequency device 2 also comprises a plurality of power injection members and a plurality of power extraction members (not shown) each connected to one of the parallelepiped segments of the metal structure 4, each segment being adapted to form an input or output port of the radiofrequency device 2. In a known manner, the “magic tee” radiofrequency device 2 is adapted to perform several radiofrequency functions, for example to sum two signals of equal amplitude, to divide a signal into two in-phase signals or to divide a signal into two signals of opposite phase.

[0093] [Fig.8] represents a method for increasing the dielectric strength of a radiofrequency device 2 without the solid dielectric foam 24, the dimensions of the radiofrequency device 2 without the solid dielectric foam 24 being previously determined and not being able to be modified to take into account a risk of electric arc.

[0094] Preferably, one begins with a step of digital simulation 42 of a mapping of the electromagnetic field in the radiofrequency device 2 without the solid dielectric foam 24 in order to determine the locations of the radiofrequency device 2 at which the simulated electromagnetic field is the highest. Such a digital simulation is represented in [Fig.9] for the radiofrequency device 2 illustrated in [Fig.l]. In this case, the simulated electromagnetic field is the highest at the free ends of the elongated resonators 20, 22 and along the projecting edges of the elongated resonators 20, 22. These are therefore the locations most conducive to the occurrence of an electric arc.

[0095] A threshold representative of the risk of breakdown of the radio device is then determined. frequency 2 as a function of the established electromagnetic field mapping, the dielectric gas present in the interior volume defined by the metallic structure 4 and the pressure of said dielectric gas. For example, the representative threshold is defined as a function of an input power of the radiofrequency device 2 used to simulate the mapping and a potential difference value obtained by integration of the electromagnetic field along a segment of a given length.

[0096] Then, a step 44 is carried out for filling at least a portion of the interior volume defined by the metal structure 4 of the radiofrequency device 2 with solid dielectric foam 24. For example, the solid dielectric foam 24 is placed at the locations of the radiofrequency device 2 at which the simulated electromagnetic field exceeds the threshold determined in the dielectric gas. Alternatively, the interior volume defined by the metal structure 4 is completely filled with solid dielectric foam 24.

[0097] Advantageously, the filling step 44 comprises a sub-step of machining the solid dielectric foam 24 so that the solid dielectric foam 24 is of a shape suitable for filling all or part of the interior volume defined by the metal structure 4, in particular so that the solid dielectric foam 24 is of a shape suitable for the locations of the radiofrequency device 2 at which the simulated electromagnetic field exceeds the threshold determined in the dielectric gas.

[0098] Optionally, the filling step 44 comprises a sub-step of bonding the solid dielectric foam 24 to a wall of the metal structure 4.

Claims

Claims

1. Radiofrequency device (2) configured to perform at least one radiofrequency function, the radiofrequency device (2) comprising a metal structure (4) defining an interior volume, at least one power injection member (16) at an input of the metal structure (4) and at least one power extraction member (18) at an output of the metal structure (4) arranged so that an electromagnetic wave is able to propagate from said power injection member (16) to said power extraction member (18), characterized in that at least a portion of the interior volume defined by the metal structure (4) is filled with a solid dielectric foam (24) having a relative dielectric permittivity of less than 1.

5.

2. Radiofrequency device (2) according to claim 1, wherein the dielectric loss tangent of the solid dielectric foam (24) is less than 5.103, in particular less than 5.

104.

3. Radiofrequency device (2) according to one of claims 1 and 2, in which the relative dielectric permittivity of the solid dielectric foam (24) is at least equal to 1.01 and at most equal to 1.20, in particular at least equal to 1.01 and at most equal to 1.

08.

4. Radiofrequency device (2) according to any one of claims 1 to 3, in which the solid dielectric foam (24) fills the entire interior volume defined by the metallic structure (4).

5. Radiofrequency device (2) according to any one of claims 1 to 4, wherein the solid dielectric foam (24) is bonded to the metal structure (4).

6. Radiofrequency device (2) according to any one of claims 1 to 5, wherein the metallic structure (4) comprises at least one elongated metallic resonator (20, 22), the solid dielectric foam (24) being in contact with said elongated metallic resonator (20, 22).

7. Radiofrequency device (2) according to any one of claims 1 to 6, in which the metallic structure (4) forms at least one resonant cavity (40), the solid dielectric foam (24) at least partially filling said resonant cavity (40).

8. Radiofrequency device (2) according to any one of claims 1 to 7, in which the metallic structure (4) forms at least one waveguide, the solid dielectric foam (24) internally filling at least part of said waveguide.

9. Method for increasing a breakdown power of a radiofrequency device (2) configured to perform at least one radiofrequency function, the radiofrequency device (2) comprising a metal structure (4) defining an interior volume, at least one power injection member (16) at an inlet of the metal structure (4) and at least one power extraction member (18) at an outlet of the metal structure (4) arranged so that an electromagnetic wave is able to propagate from said power injection member (16) to said power extraction member (18), characterized in that it comprises at least one step of filling (44) at least a portion of the interior volume defined by the metal structure (4) with a solid dielectric foam (24) having a relative dielectric permittivity of less than 1.

5.

10. Method according to claim 9, comprising a prior step of digital simulation (42) of a mapping of an electromagnetic field in the interior volume defined by the metallic structure (4) entirely filled with the dielectric gas, the filling step then being carried out so that the solid dielectric foam (24) is arranged at least at the locations of the interior volume defined by the metallic structure (4) at which the simulated electromagnetic field exceeds a predetermined threshold.

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