Self-adjusting electromagnetic thin-film shielding screen

Description

Domaine technique

[0001] The present disclosure relates to the field of self-adapting optically transparent electromagnetic shielding screens with electrically conductive mesh for electromagnetic and / or optical sensor systems to be protected from intense electromagnetic radiation. In the self-adapting optically transparent shielding screens with electrically conductive mesh, the mesh is grounded to a housing containing at least one sensor when an electromagnetic field exceeding a certain critical threshold for the optimal operation of said sensor is perceived by a protective member. Technique antérieure

[0002] The main objective of shielding screens for protection against external electromagnetic (EM) attacks is to protect optronic equipment fitted to vehicles and their optical sensors while ensuring high optical transparency in the UV (ultraviolet), visible and IR (infrared) ranges for optimal operation of said optronic equipment and associated optical sensors. These screens, to date, have a predefined and constant value of shielding effectiveness, determined by the intrinsic parameters of an RF shield made by a micrometric pitch metal mesh of the screen connected to a ground of the equipment.

[0003] With regard to switchable RF shielding with electrically conductive meshes, document WO2018 / 215243 A1 in the name of the applicants proposes a shielding screen with electrically conductive mesh with micrometric pitch directly printed on an internal face of optics or windows (made of silicon, germanium, sapphire, B glass, etc.) of various optronic equipment. The electrically conductive mesh with micrometric pitch is defined by the width of its constituent electrically conductive strips, typically of the order of 10 micrometers, its mesh pitch or period, typically of the order of 100 micrometers and the thickness of the electrically conductive material used, typically of the order of 2 micrometers. The modulation of the shielding effectiveness (EB) is obtained by controlling the value of the contact impedance between this electrically conductive mesh and a ground return of the shielding screen.This control is achieved either by the implantation of localized components such as PIN diodes, MEMS, NEMS or others between the electrically conductive mesh and the ground return; or by the use of printed ribbons based on insulator-metal transition materials, typically VO 2 whose two states ON (electrically conductive) and OFF (electrically insulating) strongly modify the value of the contact impedance of the screen with the ground, and consequently, the value of the EB of the screen, and this in a totally reversible manner.

[0004] This first solution requires a command to activate the variation of the contact impedance of the shield and a power supply preferably external to the device to be protected.

[0005] Furthermore, application FR21 02339 filed on March 10, 2021 by the applicants describes a technical solution consisting of capturing the energy of an external EM attack via a rectifying antenna, and using the direct current generated to activate localized components such as PIN, MEMS, NEMS or other diodes, or even printed ribbons based on insulator-metal transition materials, typically VO 2 , or even actuating a micropump injecting a liquid into a channel between the RF shielding and the ground, in order to dynamically adapt the EB value of the shielding screen, and thus make the RF shielding switchable. The complete system therefore becomes a shielding screen with controlled shielding effectiveness (EB), the EB value of which increases automatically as soon as the external electromagnetic (EM) attack appears, without the need for activation of the system by an operator.This solution does not require a power supply but is effective for high received EM energies, especially if the shielding grounding means require a high current or voltage for activation. Résumé

[0006] The present disclosure aims to make it even easier to produce a self-adaptive electromagnetic shielding device for protecting equipment containing an optoelectronic sensor and proposes an optically transparent self-adaptive electromagnetic shielding device for an optic or a porthole of equipment provided with an electrically conductive enclosure containing at least one optical or RF sensor behind said optic or said porthole, said device comprising on at least one face of said optic or said porthole a shielding screen comprising a switchable RF shielding mesh at least partially surrounded by a border of insulating-metal transition material arranged between said mesh and an electrically conductive shielding surround of said equipment, comprising a susceptor element,arranged opposite or in contact with said insulator-metal transition material and adapted to transform incident electromagnetic energy into a quantity of activation heat of said insulator-metal transition material, said susceptor element being sized to cause said insulator-metal transition material to switch to the conductive state under the action of said electromagnetic energy so as to electrically connect said mesh at low impedance to said electrically conductive surroundings when the incident electromagnetic energy exceeds a given threshold.,

[0007] This allows for an automatic transition of the self-adaptive shielding from a configuration that allows electromagnetic waves to pass through to a shielding configuration that blocks said waves from a given incident electromagnetic energy.

[0008] The RF shielding mesh is preferably micrometric pitch for active shielding at frequencies from several GHz to several tens of GHz.

[0009] The features set out in the following paragraphs may, optionally, be implemented, independently of each other or in combination with each other:

[0010] According to a first embodiment, the switchable RF shielding mesh and the insulator-metal transition material are arranged on one face of said optic or said porthole internal to the equipment while the susceptor element is produced on an external face of said optic or said porthole and comprises a layer of electrically conductive material facing a surface of said insulator-metal transition material.

[0011] The insulator-metal transition material may form a first frame around the mesh, the susceptor element being shaped as a second frame opposite said first frame.

[0012] In this case, an area of ​​the second frame may be greater than or equal to an area of ​​the first frame.

[0013] The susceptor element may comprise a layer of semi-transparent conductive material covering the external face of said optic or said porthole.

[0014] According to a second embodiment, the switchable RF shielding mesh and the insulator-metal transition material are deposited on an external face of said optic or said porthole, the susceptor element comprising a layer of conductive material facing a surface of said insulator-metal transition material and deposited on an electrically insulating layer covering said insulator-metal transition material.

[0015] According to a third embodiment, the switchable RF shielding mesh, the insulator-metal transition material and the susceptor element are arranged on a face of said optic or said porthole internal or external to the equipment, the susceptor element being produced in the form of a frame surrounding the insulator-metal transition material, the latter surrounding the switchable RF shielding mesh.

[0016] According to a fourth embodiment, the switchable RF shielding mesh and the frame made of insulator-metal transition material are deposited on an external face of said optic or said porthole, the susceptor element comprising a layer of conductive material, facing a surface of said insulator-metal transition material, deposited on an electrically insulating layer itself covering said insulator-metal transition material. The switchable RF shielding mesh may in particular be made of insulator-metal transition material deposited on an external face of said optic or said porthole and covering said external face, the susceptor element comprising a layer of conductive material deposited on an insulating layer and covering it, said insulating layer itself covering said insulator-metal transition material.

[0017] Said layer of conductive material and / or said layer of insulating material may in this case comprise an optically transparent mesh covering the switchable RF shielding mesh, in particular in the area of ​​the lens or the porthole facing the sensor of the system to be protected.

[0018] For all solutions, the switchable RF shielding mesh can be a micrometric pitch mesh made of electrically conductive material, the mesh structure can be periodic or aperiodic (Voronoi type).

[0019] The micrometric pitch mesh can be made of a material chosen from a titanium / silver bilayer, an insulator-metal transition material or gold.

[0020] The insulator-metal transition material can be a VO 2 type material with a thickness between 1000 nm and 2000 nm.

[0021] The susceptor element can be a gold film with a thickness of 2 nanometers to 10 nanometers.

[0022] The switchable RF shielding mesh is advantageously sized to provide a shielding effectiveness of 10 dB to 40 dB in a frequency band of 0.1 GHz to 40 GHz when electrically connected at low impedance to the electrically conductive surrounding by the electrically conductive insulator-to-metal transition material.

[0023] The optical transparency of the shielding screen is at least 50% in the visible range whether the shielding is active or inactive. Brève description des dessins

[0024] Other features, details and advantages will become apparent upon reading the detailed description below, and upon analyzing the attached drawings, in which: [ Fig. 1A ] shows a top view of a first exemplary embodiment of self-adaptive shielding of the present disclosure; [ Fig. 1B ] shows a bottom view of the first exemplary embodiment of self-adaptive shielding of the present disclosure; [ Fig. 1C ] a top view of a variant of the figure 1A ; [ Fig. 2 ] shows a schematic view of a sensor device behind a window with self-adaptive shielding under low electromagnetic stress; [ Fig. 3 ] shows a schematic view of the device of the figure 2 under strong electromagnetic constraint of the present disclosure; [ Fig. 4A ] a top view of a second exemplary embodiment of self-adaptive shielding of the present disclosure; [ Fig. 4B ] a bottom view of the example of the self-adaptive shielding of the figure 4A ; [ Fig. 4C ] a top view of a self-adaptive armor variant of the figure 4A ; [ Fig. 5A ] a top view of a third exemplary embodiment of self-adaptive shielding of the present disclosure; [ Fig. 5B ] a bottom view of the example of the self-adaptive shielding of the figure 5A ; [ Fig. 6A ] a side view of a fourth exemplary embodiment of self-adaptive shielding of the present disclosure; [ Fig. 6B ] a side view of a variant of the self-adaptive armor of the figure 6A . Description des modes de réalisation.

[0025] The objective of the present disclosure is to produce an optically transparent self-adaptive electromagnetic shielding screen, i.e. one whose transition from a passing state for electromagnetic radiation to a blocking state for this radiation is automatic upon exceeding a given incident electromagnetic energy threshold and returning to the passing state when the electromagnetic energy falls below said threshold. To do this, the present disclosure proposes a device which comprises, as shown in figure 1B a shielding screen made on an optic or a porthole transparent to light by means of an electrically conductive micrometric mesh 2 surrounded by a frame 3 made of edges made of insulating-metal transition material such as the materials VO 2 , V 2 O 3 , BaVS 3 , PrNiO 3 , NdNiO 3 , Fe 3 O 4 , NiS, LaCoO 3 , SmNiO 3 , NbO 2 , La 5 / 3 Sr 1 / 3 NiO 4 , Ti 2 O 3 , GeTe, Ge 2 Sb 2 Te 5 (pure or doped materials or in solid solution, without this list being exhaustive) comprising a means of increasing the temperature of ribbons made of insulating-metal transition material forming edges constituting said frame in the presence of external electromagnetic aggression until they become electrically conductive for electromagnetic energy greater than a given threshold.

[0026] According to this device: a. - When the edges of the insulator-metal transition material are in the electrically insulating state (called OFF state), for example for a temperature θ VO2 lower than 67°C for a VO 2 material, the electrically conductive mesh with central micrometric pitch has a high contact impedance between the edge of the screen and the mass of the system to be protected. The shielding effectiveness is therefore minimal; b. - When the edges of the insulator-metal transition material are in the electrically conductive state (called ON state) when the temperature θ VO2 is higher than 67°C, the electrically conductive mesh with central micrometric pitch has a low contact impedance between the edge of the screen and the mass of the system to be protected. The shielding effectiveness is then maximal.

[0027] The mesh is thus a micrometric pitch switchable RF shielding mesh which is connected with low contact impedance or not to a ground of equipment depending on the temperature of the insulator-metal transition material strips forming the edges of the frame.

[0028] To actuate the transition of the insulating-metal material, the present device uses a susceptor element 5, arranged opposite said insulating-metal transition material, or even in contact with this material, and adapted to transform incident electromagnetic energy into activation heat of said insulating-metal transition material. The susceptor element is sized and positioned to cause a transition to the conductive state of said insulating-metal transition material under the action of electromagnetic energy greater than a given threshold so as to electrically connect said mesh with low impedance to said electrically conductive surroundings when the incident electromagnetic energy exceeds this given threshold.

[0029] Throughout the application, the terms "facing" mean that the susceptor material is aligned with the insulator-metal transition material in a direction perpendicular to the plane of the window.

[0030] In the case of figures 1A et 1B , which schematically represent a preferred solution, the switchable RF shielding mesh 2 and the insulating-metal transition material 3 are arranged on one face of said optic or said porthole internal to the equipment, while the susceptor element 5 is arranged on an external face of said optic or said porthole 1 and comprises a layer of conductive material forming a frame opposite the surface of the frame formed by the insulating-metal transition material 3. The heat generated by the susceptor element in the presence of electromagnetic energy passes through the optic 1, for example a sapphire porthole and heats the frame of insulating-metal transition material which, if the quantity of heat is sufficient, changes to the conductive state.

[0031] As an example, a test was carried out with a porthole made of a sapphire substrate 0.5 mm thick and measuring 50 mm by 50 mm on which is deposited: a. - on the front face: a frame hollowed out in its center made from an ultra-thin layer of gold 5 nanometers thick and forming a border with a width of 7 mm to produce the susceptor material 5 around a transparent area of ​​the window; b. - on the rear face: a frame 3 made from a thin layer of VO 2 1.5 micrometers thick forming a border with a width equal to 3 mm. The VO 2 frame is in contact on its outer edge with a conductive frame 4 consisting of a titanium / silver (Ti / Ag) bilayer 2.5 mm wide and connecting the frame 3 to an electrically conductive surround of the equipment. The VO 2 frame is connected on its inner edge to a micrometric pitch mesh square made of a titanium / silver (Ti / Ag) bilayer with a ribbon width equal to 10 micrometers, a pitch or period equal to 200 micrometers and a thickness of 5 nanometers / 2 micrometers and a side length equal to 40 mm which forms the switchable RF shielding mesh 2.

[0032] When the VO 2 material frame is in the electrically insulating state (OFF state at a temperature below 67°C), the shielding effectiveness is equal to approximately 15 dB in the 2 GHz - 18 GHz frequency band. When the VO 2 material frame is in the electrically conductive state (ON state at a temperature above 67°C), then the shielding effectiveness is equal to approximately 25 dB in the 2 GHz - 18 GHz frequency band. The optical transparency of the screen in the visible range (from 400 nm to 800 nm) remains greater than 77% regardless of the OFF or ON state of the VO 2 material frame.

[0033] The frame made of VO 2 material has, according to the example, a thickness of the order of 1000 to 2000 nanometers and preferably a thickness of the order of 1400 nanometers to 1600 nanometers, this thickness being able to be chosen differently if another insulator-metal transition material is chosen.

[0034] A reverberation chamber test performed using the method described in CL Holloway, DA Hill, J. Ladbury, G. Koepke, and R. Garzia, "Shielding effectiveness measurements of materials using nested reverberation chambers," IEEE Trans. Electromagn. Compat., vol. 45, no. 2, pp. 350-356, May 2003. doi: 10.1109 / TEMC.2003.809117 experimentally demonstrated that ultrathin gold layers (5 nm to 10 nm thick) subjected to electromagnetic stress over a frequency band of 2.7 GHz to 3.2 GHz and an amplifier output power of 55 W can increase the temperature of the sapphire substrate from 22 °C to a value above 110 °C.

[0035] THE figure 2 And figure 3 schematize equipment comprising an electrically conductive enclosure, in this case: metallic 10 containing an optical or RF sensor 20 facing an optical or porthole 1 carrying the shielding device as described in figures 1 And 2 whose insulator-metal transition material is, for example, the VO 2 material.

[0036] The metal enclosure 10 is provided with a metal surround 11 of the sapphire porthole 1 and which is electrically connected to the conductive frame 4 which surrounds the frame 3 made of VO 2 material. This frame surrounds the switchable RF shielding mesh 2 which is here itself provided with a border 2b for electrical connection with the VO 2 frame on the internal face of the porthole.

[0037] In the configuration of the figure 2 , low-energy RF radiation L irradiates the external face of the porthole and the frame 5 forming the susceptor element. In this configuration, the temperature of the insulator-metal transition material remains low and the latter remains electrically insulating.

[0038] RF and ultraviolet, visible and infrared VI light signals pass through the window and are received by the sensor 20.

[0039] In figure 3 , high-energy RF H signals irradiate the susceptor element, the temperature of which rises. The amount of heat C created is transmitted through the window to the insulator-metal transition material, the temperature of which increases until it reaches the transition temperature if the energy of the electromagnetic radiation is sufficient. Once the transition temperature is reached, the insulator-metal transition material becomes conductive, which allows low-impedance electrical contact between the mesh 2 and the enclosure 10 and blocks the RF signals, while the ultraviolet, visible, and infrared VI light signals can still reach the sensor 20.

[0040] There figure 1C corresponds to a variant of the figure 1A for which the external face of the sapphire substrate forming the porthole 1 is completely covered with an ultra-thin thin layer of the susceptor material 5a, for example a gold layer of 2 to 10 nanometers and preferably 4 to 6 nanometers for a thin porthole as described previously, while the internal face of the porthole remains in the same configuration as that of the figure 1B . This embodiment increases the electromagnetic energy captured by the screen when it is subjected to external electromagnetic aggression, and therefore reduces the electromagnetic energy necessary to obtain a sufficient temperature rise to cause the conductive transition of the insulating material to metal. However, this embodiment reduces the optical transparency of the shielding, the maximum optical transparency of a thin layer of gold 5 nanometers thick on sapphire being close to 50% in the visible range.

[0041] In the case where the insulator-metal transition material is a material other than the VO 2 material or depending on the energy of the RF signal for which the transition is to be triggered, it is possible to increase or reduce the surface covered by the susceptor element.

[0042] Figure 4A , figure 4B et figure 4C are other variants with an electrically conductive mesh with micrometric pitch 32a entirely made of insulating-metal transition material on the rear face of the sapphire substrate 1 surrounded by a frame 31a for connection to the electrically conductive surround 11 of the figure 2 itself made of insulator-metal transition material, for example VO 2 or other insulator-metal transition material as stated previously. A fairly low shielding effectiveness is obtained when the VO 2 material is in the electrically conductive state, approximately 10 dB in the 2 GHz - 18 GHz band, because its electrical conductivity (σ = 3×10 5< S / m approximately) is lower than that of silver (σ = 6.1×10 7< S / m). Nevertheless, the manufacturing process is simplified due to the absence of the micrometric meshed Ti / Ag bilayer. For the external face, the figure 4A provides a frame 51a formed by an ultra-thin layer of gold with a thickness of 4 to 6 nanometers and an internal part of the frame formed by an ultra-thin layer of meshed gold 52a. In the case of a porthole 1 with a small surface area, the ultra-thin layer of meshed gold 52a may be omitted, the frame 51a being sufficient to provide the quantity of heat necessary for the insulator-metal transition of the mesh 32a and the frame 31a made of VO 2 material. The figure 4C plans to cover the entire external face of porthole 1 with a continuous ultra-thin layer of 52b gold which ensures a better temperature rise of porthole 1, however at the expense of its optical transparency.

[0043] The example of the realization of the figure 5A et figure 5B replaces the Ti / Ag bilayer mesh with an ultra-thin 52 micron-pitch gold mesh about 5 nanometers thick. The electrically conductive frame surrounding the VO 2 3 material frame is replaced by a gold frame producing a susceptor material in direct electrical contact with the VO 2 frame. This simplifies the manufacture of the screen and leaves the external face of the porthole 1 bare. However, the shielding effectiveness of such an ultra-thin gold layer, about 30 dB in the 2 GHz - 18 GHz band, is lower than that of the 5 nm / 2 µm thick Ti / Ag layer with a micron-pitch mesh, which is about 30 to 40 dB in the 2 GHz - 18 GHz band.

[0044] Figure 6A et figure 6B are variants where only the external face of the porthole 1 is structured. These embodiments are based on a stack on the external face of the porthole of a first frame comprising a susceptor material 5c, 5d, of a frame of electrically insulating material 6a, 6b such as TiO 2 or Al 2 O 3 of a hundred nanometers thick and of a frame of insulator-metal transition material 3a, 31 around a conductive mesh 2a, or insulator-metal transition 32. In the case of the figure 6A where the mesh is a Ti / Ag mesh as in figure 1 , the shielding effectiveness and optical transparency performance of the screen are maintained with, in addition, an improvement in the switching speed between the ON and OFF states, because the quantity of heat generated by the layer of susceptor material during external EM aggression only has to pass through the thin layer of TiO 2 or Al 2 O 3 , and no longer the window, which is much thicker.

[0045] The manufacture of these variants is nevertheless more complex due to the need to use a new dielectric buffer layer 6a, 6b with high thermal conductivity, for example made of TiO 2 or Al 2 O 4 material with a thickness of the order of 100 nanometers for example. This dielectric buffer layer of TiO 2 or Al 2 O 4 must be interposed between the ultrathin gold layer and the VO 2 layer. When the ultrathin gold layer converts the energy of the electromagnetic wave into heat, the latter is transferred to the thin VO 2 layer through the buffer layer and causes the insulator / metal transition of the VO 2 material. Nevertheless, this gold layer must remain electrically isolated from the VO 2 layer, so that it retains all its susceptor capabilities.

[0046] In the case of the figure 6B , the Ti / Ag mesh is replaced by a VO 2 32 mesh connected to the VO 2 31 frame and the insulating and gold layers are themselves provided with 6c and 5e meshes, respectively.

[0047] This disclosure is not limited to the examples described above, only as an example, but it encompasses all the variants that may be envisaged by those skilled in the art within the framework of the protection sought. In particular, the various solutions described can be combined like the solution of figures 5A et 5B in particular for which the gold mesh can be replaced by a Ti / Ag mesh of the solution of the figure 1B . Similarly, the thicknesses and lateral dimensions announced above are for information purposes only and may vary depending on the level of electromagnetic radiation energy at which self-adaptation of the shielding is desired and the dimensions of the window.

[0048] The frequency range of protection sought against external EM attacks based on electrically conductive mesh with micrometric pitch of the present disclosure covers the band 0.1 GHz to 40 GHz. A mesh pitch of millimetric or even centimetric dimensions could also be considered, however to the detriment of the high protection frequency of said shielding screen.

[0049] The invention is not limited to the examples described above and in particular other combinations for the implantation of the materials are possible provided that the susceptor material is positioned so as to be able to heat, in the presence of a given electromagnetic energy, the insulator-metal transition material itself positioned to allow the switchable RF shielding to be connected to an electrically conductive surround of an optic or a porthole. It is furthermore possible within the scope of the present disclosure to substitute the ultrathin film or layer of gold used as a susceptor with a layer of graphite, stainless steel, molybdenum, or silicon carbide, or even aluminum, without this list being exhaustive.It is also possible within the framework of the present disclosure to replace the metallic mesh with a continuous or meshed thin layer material belonging to the family of transparent and conductive oxides (TCO) such as pure or doped In 2 O 3 (ITO, FTO, etc.); pure or doped ZnO (AZO, etc.) without this list being exhaustive.

Claims

1. Optically transparent self-adaptive electromagnetic shielding device for a lens or for a window (1) of a piece of equipment provided with an electrically conductive enclosure (10) containing an optical or RF sensor (20) behind said lens or said window, said device comprising, on at least one face of said lens or said window, a shielding screen comprising a switchable RF shielding mesh (2, 2a, 32, 32a, 52, 52a) at least partially surrounded by a border of insulator-metal transition material (3, 3a, 31, 31a) arranged between said mesh and an electrically conductive envelope (11) for shielding said piece of equipment, characterized in that it comprises a susceptor element (5, 5a, 5b, 5c, 5d, 5e, 51a, 52b) arranged facing or in contact with said insulator-metal transition material and adapted to transform incident electromagnetic energy (RFH) into an amount of activation heat for said insulator-metal transition material (3, 3a, 31, 31a), said susceptor element being dimensioned to cause a transition to the conductive state of said insulator-metal transition material (3, 3a, 31, 31a, 32, 32a) under the action of said electromagnetic energy so as to electrically connect, at low impedance, said mesh to said electrically conductive envelope when the incident electromagnetic energy exceeds a given threshold.

2. Self-adaptive shielding device according to claim 1, wherein the switchable RF shielding mesh (2) and the insulator-metal transition material (3) are arranged on one face of said lens or of said window, internal to the piece of equipment, while the susceptor element (5, 5a) is implemented on an external face of said lens or of said window (1) and comprises a layer of electrically conductive material which faces a surface of said insulator-metal transition material.

3. Self-adaptive shielding device according to claim 2, wherein the insulator-metal transition material forms a first frame (3) around the mesh, the susceptor element being shaped as a second frame (5) facing said first frame.

4. Self-adaptive shielding device according to claim 3, wherein a surface area of the second frame (5) is greater than or equal to a surface area of the first frame.

5. Self-adaptive shielding device according to claim 2, wherein the susceptor element comprises a layer of semi-transparent conductive material (5a) covering the external face of said lens or of said window (1).

6. Self-adaptive shielding device according to claim 1, wherein the switchable RF shielding mesh (2a) and the insulator-metal transition material (3a) are deposited on an external face of said lens or of said window, the susceptor element comprising a layer of conductive material (5c) facing a surface of said insulator-metal transition material and deposited on an electrically insulating layer (6a) covering said insulator-metal transition material.

7. Shielding device according to claim 1, wherein the switchable RF shielding mesh (52), the insulator-metal transition material (3), and the susceptor element (5b) are arranged on one face of said lens or of said window, internal or external to the piece of equipment, the susceptor element (5b) being implemented in the form of a frame surrounding the insulator-metal transition material, the latter surrounding the switchable RF shielding mesh.

8. Self-adaptive shielding device according to claim 6, wherein the switchable RF shielding mesh (32) is implemented with the insulator-metal transition material deposited on an external face of said lens or of said window and covering said external face, the susceptor element comprising a layer of conductive material (5e) deposited on an insulating layer (6b, 6c) which itself covers said insulator-metal transition material.

9. Self-adaptive shielding device according to claim 8, wherein said layer of conductive material and / or said layer of insulating material comprises an optically transparent mesh covering the switchable RF shielding mesh.

10. Self-adaptive shielding device according to any one of the preceding claims, wherein the switchable RF shielding mesh is a mesh of micrometric pitch made of electrically conductive material.

11. Self-adaptive shielding device according to any one of the preceding claims, wherein the switchable RF shielding mesh is a mesh made of a material chosen among a titanium / silver bilayer, an insulator-metal transition material, or gold.

12. Self-adaptive shielding device according to any one of the preceding claims, wherein the insulator-metal transition material is a VO2 type of material with a thickness between 1000 and 2000 nm.

13. Self-adaptive shielding device according to any one of the preceding claims, wherein the susceptor element is a gold film with a thickness of 2 nanometers to 10 nanometers.

14. Self-adaptive shielding device according to any one of the preceding claims, wherein the switchable RF shielding mesh (2, 2a, 32, 32a, 52, 52a) is dimensioned to provide a shielding effectiveness of 10 dB to 40 dB within a frequency band of 0.1 GHz to 40 GHz when it is electrically connected at low impedance to the electrically conductive envelope (11) by the insulator-metal transition material rendered conductive.

15. Self-adaptive shielding device according to any one of the preceding claims, wherein the optical transparency of the shielding screen is at least 50% in the visible range.