EP1052724A1 - Structure inductive grillagée - Google Patents
Structure inductive grillagée Download PDFInfo
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- EP1052724A1 EP1052724A1 EP00401264A EP00401264A EP1052724A1 EP 1052724 A1 EP1052724 A1 EP 1052724A1 EP 00401264 A EP00401264 A EP 00401264A EP 00401264 A EP00401264 A EP 00401264A EP 1052724 A1 EP1052724 A1 EP 1052724A1
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- elementary
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
- H01Q15/0006—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices
- H01Q15/0013—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices said selective devices working as frequency-selective reflecting surfaces, e.g. FSS, dichroic plates, surfaces being partly transmissive and reflective
- H01Q15/0026—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices said selective devices working as frequency-selective reflecting surfaces, e.g. FSS, dichroic plates, surfaces being partly transmissive and reflective said selective devices having a stacked geometry or having multiple layers
Definitions
- the invention relates to the field of inductive structures screened.
- the inductive mesh structures can be used as microwave short circuit for the protection of optical equipment or optronics against electromagnetic aggression so that the equipment behaves approximately like a Faraday cage.
- the electromagnetic aggression can be of the radio, radar, weapon type microwave, strong field, electromagnetic pulse, lightning ...
- optronic equipment can include all types of equipment having an optical opening closed by a window guaranteeing the mechanical closing of equipment.
- the porthole must then also realize to some extent the electrical shutdown of the equipment by presenting a low impedance on a given microwave spectral domain.
- the porthole must then have the following properties, on the one hand the microwave screening property of screening substantially in a given microwave spectral domain, by example from 2 to 18 GHz, and on the other hand the property of optical transmission consisting of being substantially transparent in a spectral domain given optics, for example ranging from ultraviolet to infrared, and present a good modulation transfer function in the field optical spectral.
- a problem to be solved by the portholes is that of a good compromise between microwave properties and optical properties, that is to say between the microwave screen and the optical transmission which will be called in the following the “microwave / optical compromise”. Indeed, these properties are difficult to reconcile and often good screening microwave can only be obtained at the expense of transmission optical, whether at the level of optical transparency, i.e. amount of energy transmitted or else at the level of the transfer function of modulation, that is to say the quality of the energy transmitted, and vice versa. In depending on the type of application envisaged, different solutions are possible.
- a window comprising a thick layer of semiconductor.
- Selective doping in the form of semiconductor layer grid provides the property of screening. Due to the low electrical conductivity of semiconductors, good microwave screening can only be achieved with a thick semiconductor layer, which has the effect degrade optical transparency and therefore optical transmission. In in the case of severe constraints, the microwave / optical compromise achieved will be insufficient. Furthermore, it is difficult to find a semiconductor material having good optical transparency in the field optical spectral of the visible.
- a window comprising a thin layer of material with high electrical conductivity.
- the thin film material must have a strong electrical conductivity and therefore a high extinction coefficient even at optical wavelengths, thus degrading the optical transparency and therefore the optical transmission. In the case of severe constraints, the microwave / optical compromise achieved will be insufficient.
- a structure is provided inductive biperiodic grid of the grid type with square patterns for example.
- the square character ensures symmetry of polarity as well as relative simplicity of the grid.
- the material of the grid is electrically conductive, it is for example a metal or a semiconductor. Either during the period or pitch of the network and 2d the wire width of the grid. The 2d / a influence of importantly the microwave screen. A high 2d / a ratio is translates into good microwave screening and vice versa. Now a report 2d / a high implies a recovery rate, i.e. a ratio between conductive area and total area for the grid, which is also high.
- This high recovery rate is a source of diffraction phenomenon which degrades the quality of optical transmission by deteriorating the function modulation transfer.
- the microwave / optical compromise achieved will be insufficient. It remains possible at constant 2d / a ratio, to decrease the pitch a of the grid and consequently the 2d width of grid wire. Wavelengths in the spectral range being higher than the wavelengths in the domain spectral optics, the decrease in step a at constant 2d / a affects more microwave wavelengths than optical wavelengths. While the cutoff frequency in the spectral range increases and as the microwave screen improves, the diffraction phenomenon is little modified and the optical transmission is therefore degrades little. However, in the case of severe constraints, the Microwave / optical compromise achieved will still be insufficient.
- the invention is based on a very clear improvement in compromise microwave / optical.
- the invention uses an inductive structure screened in particular with good microwave shielding as well than a more uniform spatial distribution of the optical diffraction energy, i.e. diffraction energy in the optical spectral range.
- the quality of the optical transmission of the mesh inductive structure and the entire optical window in which the grid can be included, in is then clearly improved, since a more uniform spatial distribution of optical diffraction energy improves the transfer function of modulation.
- the invention also has the advantage of proposing a solution wide band for the optical spectral range, because the screened nature of the inductive structure allows optical transmission in the field optical spectral to be little dependent on the optical wavelength.
- an inductive grid structure is provided. with elementary stitches, the sides of which are made of wire electrically conductive, the average mesh recovery rate on the one hand being sufficiently high so that the structure substantially screens in a given microwave spectral domain and on the other hand sufficiently weak so that the structure is substantially transparent in a given optical spectral range, characterized in that the sides of the meshes are oriented so irregular enough to distribute more evenly in space that in the case of a single periodic grid, the diffraction energy in the optical spectral domain.
- Figure 1 makes it possible to specify some general definitions concerning the elementary meshes of any grid.
- the example shown relates to a grid with square patterns composed of several elementary meshes m like the grids according to the third prior art.
- the elementary meshes m are represented in dotted lines.
- Each elementary mesh has a surface sv of void or of electrically nonconductive material surrounded by sides c of electrically conducting wire constituting the surface sf of wire.
- 2d represents the width of the wire and has the pitch of the stitch.
- the rate of vacuum or electrically non-conductive material is equal to sv / a 2 and the recovery rate is equal to (a 2 -sv) / a 2 , sv being equal here (a-2d) 2 .
- the elementary mesh surface is worth a 2 .
- the sides of elementary meshes of the inductive grid structure are oriented from more irregular than the sides of the basic stitches of a single periodic grid such as for example a grid with square patterns or circular.
- a single periodic grid such as for example a grid with square patterns or circular.
- the microwave spectral domain it for the inductive mesh structure, to keep as much as possible periodic character of a single periodic grid.
- the inductive grid structure according to the invention takes advantage of the fact that the wavelengths of the domain optical spectrum are lower and often significantly lower than wavelengths of the microwave spectral range.
- This more spatial distribution uniform optical diffraction energy allows for an energy globally equivalent diffracted, by delocalizing this energy by spatial distribution, thereby decreasing the intensity of the diffraction peaks of the diffraction pattern of the inductive grid structure, to improve considerably the modulation transfer function and therefore the quality of optical transmission.
- the first type uses several inductive mesh structures, for example grids, each of which may have an important periodic character, but of which the arrangement and arrangement reduce the periodicity of the whole constituted by the different structures.
- This solution is relatively simple to perform but its effectiveness is not completely optimized.
- the first type corresponds to the first two modes of production.
- the second type uses a single screen structure, the aperiodic character is important. This solution is more complex to achieve but is likely to yield even better results.
- the second type corresponds to the third embodiment.
- the solutions of the two types of devices can of course be combined for a efficiency further increased at the cost, however, of a complexity of construction which increases.
- the first type of device uses an inductive structure mesh with several elementary grids each diffracting according to a diffraction peak figure, the diffraction peak figures being substantially spatially offset from each other.
- the optimum is reached when the diffraction peaks from one figure to another are spatially distinct, that is to say, do not overlap at all; however, a slight recovery can lead to a solution that is still satisfactory, depending on the type and severity of the constraints imposed by the application considered.
- the more spatially offset the diffraction patterns the more the diffraction energy in the optical spectral domain is spatially evenly distributed, the better the quality of the transmission optical.
- the intensity of the corresponding diffraction peaks remains substantially constant preference from one figure to another. So the energy of diffraction in the optical spectral domain is distributed so substantially identical between the different diffraction patterns corresponding to the different elementary grids. The higher the intensity of the peaks diffraction from one figure to another is constant, the more the diffraction energy in the optical spectral domain is uniformly spatially distributed.
- the structure has functionally several grids elementaries with virtually each a diffraction pattern, but these elementary grids preferentially all occupy the same surface and preferably structurally form a single grid. In the case of plane elementary grids, all elementary grids will then be in the same plan and assembled to each other so as no longer structurally form a single resulting grid. If the different grids elementary each have a very marked periodic character, for example have regularly spaced square patterns, the arrangement of these elementary grids will be such that the periodic character of the grid resulting will be much less marked, its patterns then being for example more or less regular polygons.
- the advantage of such a structure screened is to have an optical transmission comparable to that of one elementary grids while presenting a microwave screen markedly improved.
- the elementary grids In the preferential case where the elementary grids are substantially parallel to each other but where they do not belong to the same surface, the elementary grids must be close enough from each other, that is to say that the distance between the grids elementary must remain sufficiently weak so that the irregular character of the orientation of the sides of the elementary meshes results in a more uniform spatial distribution of optical diffraction energy.
- a structure made up of two elementary orientation grids different, square patterns, and separated by enough space important compared to optical wavelengths, will diffract mainly in two directions as a single periodic grid.
- the grids elementaries have substantially the same recovery rate.
- the optimum being reached when the recovery rate is identical.
- Grates elementary advantageously have elementary meshes of form substantially square.
- the substantially square character of the meshes elementary offers a good compromise between simplicity, screen microwave, optical transmission and polarization symmetry, even if the intensity of the diffraction peaks remains higher than with grids elementary whose patterns have a more "irregular" shape.
- FIG. 2 schematically represents a first mode particular embodiment of an inductive grid structure according to the invention.
- the structure has several elementary grids, here two grids elementary marked G1 and G2.
- Grid G2 is shown in dashed lines while the grid G1 is shown in dotted lines.
- elementary grids belong to substantially parallel surfaces between them, advantageously flat.
- the grids elementaries are in the same plane and their elementary mesh sides are intersect so as to form only a single mesh structure.
- Each of the elementary grids has an elementary mesh surface substantially constant and the elementary mesh surfaces are substantially different between elementary grids.
- the two elementary grids G1 and G2 have elementary meshes of substantially square shape.
- the elementary grid G1 has a step a1 different from the step a2 of the elementary grid G2.
- Grates advantageously all have the same orientation, that is to say that the sides of the elementary stitches of one of the grids are respectively parallel to the sides of the elementary meshes of the others elementary grids. This will be the case for all numerical examples preferential relating to the first embodiment.
- the two grids elementary G1 and G2 have elementary mesh sides which are respectively parallel to the two axes X and Y perpendicular to each other.
- the different peaks of n order diffraction are angularly located, from the center of the spot central diffraction, at angles equal to n ⁇ / a1.
- orders from diffraction of order m corresponding to the second elementary grid G2 are located angularly, from the center of the central diffraction spot, at angles equal to m ⁇ / a2. If, as is the case, the steps a1 and a2 respectively elementary grids G1 and G2 are different, the diffraction peaks, although located in the same directions X and Y, are however for the most of them, distinct from each other.
- these recoveries should not produce that for high orders of diffraction so that the energy resulting from the sum of the two corresponding diffraction peaks is less than the optical diffraction energy of the first peaks of diffraction of at least one of the elementary grids.
- the steps of the different elementary grids are chosen so that any diffraction peak resulting from the total or partial superposition of several peaks of diffraction from different elementary grids has an intensity that is less than or substantially equal to the upper bound of all intensities of first order diffraction peaks of all grids elementary. So the diffraction peaks resulting from the coupling between diffraction orders of several elementary grids, then correspond to high diffraction orders and consequently low energy. So, these diffraction peaks resulting from the coupling between elementary grids are not not limiting, since lower in intensity than the first diffraction peaks at least one of the elementary grids.
- the steps of the different elementary grids are also preferably chosen so that any diffraction peak resulting from the total or partial superposition of several peaks of diffraction coming from different elementary grids and whose intensity is greater than or substantially equal to the upper bound of all the intensities first order diffraction peaks of all elementary grids, is located outside the field of the optical window in which the mesh structure is integrated.
- Diffraction peaks resulting from coupling between orders of diffraction of several elementary grids, then corresponding to diffraction orders located outside the field of the optronic window are only not limiting, since excluded from the image of the scene observed through the optronic window.
- the diffraction order is indicated with the corresponding grid or structure in brackets: for example 2 (G2) means “second diffraction order for the elementary grid G2.
- the vacuum rate of a grid being the ratio between the vacuum surface and the total surface, the grids G1 and G2 respectively have a vacuum rate of 64% and 71%, while the inductive grid structure, denoted SIG, has a vacuum rate of 47%.
- the energies are noted in arbitrary relative units, with the value 1 corresponding to the energy of the central diffraction spot.
- the sixth diffraction order for the inductive structure SIG mesh corresponds respectively to the third and fourth orders diffraction for the first G1 and second G2 elementary grids.
- the energy of this sixth order of diffraction for the inductive structure grid SIG corresponds approximately to the sum of the energy of third and fourth diffraction orders for the first G1 and second G2 elementary grids respectively.
- this remaining sum lower than the second order diffraction energy for the structure inductive mesh corresponding to the first diffraction order of the first grid G1 the sixth order diffraction peak for the inductive mesh structure is not limiting.
- a good quality optical transmission corresponds to a ratio between the energy of the first diffraction peak and the energy of the central diffraction spot which is low on the optical spectral range, here the optical range ranging for example from the ultraviolet infrared. This ratio will be noted E1.0 / E0.0.
- Good microwave screening corresponds to attenuation on a given microwave band, here the band going for example from 2 to 18 GHz. This attenuation is noted T2-18GHz.
- the elementary grid G1 has a pitch a1 equal to 200 ⁇ m, a width of wire 2d equal to 1 ⁇ m and a ratio of surface of wire to total surface equal to 0.005.
- the elementary grid G2 has a pitch a2 equal to 220 ⁇ m, a width of wire 2d equal to 1 ⁇ m and a ratio of surface of wire to total surface equal to 0.0045.
- the ratio E1.0 / E0.0 and the attenuation T2-18GHz are respectively given in relative value and in decibel (dB), for each of the elementary grids G1 and G2 as well as for the inductive grid SIG structure constituted by these two grids elementary.
- G1 G2 GIS E1.0 / E0,0 2.5x10 -5 2.1x10 -5 2.5x10 -5 T2-18GHz -25.4 -24.5 -31.4
- the gain in microwave screening is 6dB, which is important. The compromise thus achieved between microwave screening and the quality of optical transmission is thus clearly improved.
- the position of the elementary grids in relation to each other in the same plan has no significant influence on the quality of the optical transmission. Indeed, when the two elementary grids G1 and G2 are offset from each other, the variation of the ratio between the total energy diffracted in the higher orders and the energy of the spot central diffraction is negligible, on the order of a fraction of a percent.
- the energies are noted in arbitrary relative value, the reference value 1 corresponding to the incident energy.
- the microwave screen corresponds to an attenuation on a given microwave band, here the band going for example from 2 to 18 GHz. This attenuation is noted T2-18GHz, it is given in dB.
- the elementary grid G1 has a pitch a1 equal to 2mm, a wire width 2d equal to 2 ⁇ m and a ratio of wire surface to total surface equal to 0.001.
- the elementary grid G2 has a pitch a2 being 2.1 mm, a width of wire 2d being worth 2 ⁇ m and a ratio surface of wire on total surface being worth 0.00095.
- the third table shows that for a quality of diffraction similar to that of each of the elementary grids G1 and G2, the screen microwave is improved by about 5dB.
- the “Equivalent grid” Geqhyp presents a relationship between the maximum energy of a higher order diffraction peak and the energy of the central spot of diffraction on the optical spectral domain, which is four times higher, this which represents a much lower quality of optical transmission.
- a fourth table gathers above the numerical results of a fourth numerical example.
- the notations of the third numerical example described above are preserved.
- Several elementary grids G1, G2, G3, G4, G5, G6 are considered, their respective steps are a1 being 2mm, a2 being 2.1mm, a3 being 2.2mm, a4 being 2.3mm, a5 being 2.4mm, a6 worth 2.5mm.
- Several inductive lattice structures containing two to six elementary grids are analyzed.
- the fourth table contains two additional grids of respective pitches worth 0.46mm and 2mm as well as wire surface to total surface ratios worth 0.0043 and 0.001 respectively, respectively denoted Geqhyp for "grid equivalent to the inductive grid structure in the microwave spectral range "and Geqopt for" grid equivalent to the inductive grid structure in the optical spectral range ".
- Eoptique E0,0 Ei, 0 / E0,0 T2-18GHz GIS G1 to G2 0.996 0,992 10 -6 -13 GIS (G1 to G3) 0,994 0.988 10 -6 -15.4 GIS (G1 to G4) 0,992 0,985 10 -6 -17.5 GIS (G1 to G5) 0.99 0.982 10 -6 -19.1 GIS (G1 to G6) 0.988 0.979 10 -6 -20.5 Geqhyp 0.991 0.983 1.9x10 -5 -20.5 Geqopt 0,998 0.996 10 -6 -8.2
- the microwave shielding gains 12 dB while the ratio between the maximum energy of a higher order diffraction peak and the energy of the central diffraction spot on the optical spectral domain remains at level of 10 -6 .
- the inductive grid structure comprising six elementary grids achieves a very good microwave / optical compromise.
- the gain at the relative maximum intensity level of the diffraction peaks represented by the ratio Ei, 0 / E0.0 which is a key parameter translating the optical transmission quality, reaches a factor of 19.
- the gain at the microwave screen reaches 12dB which corresponds to a factor of 16.
- optical transparency represented by the value of the overall optical transmission E0,0 drops very slightly, around 1% between the inductive grid structure including six elementary grids and the "optical equivalent grid" Geqopt.
- the number of grids is not a real performance parameter limiting, since only the width of the wire is technologically limiting.
- FIG. 3 schematically represents a second mode particular embodiment of an inductive grid structure according to the invention.
- the structure has several elementary grids, here two grids elementary marked G1 and G2.
- the two elementary grids G1 and G2 are shown in solid lines.
- the elementary grids belong to surfaces that are substantially parallel to each other, advantageously flat.
- the elementary grids are in the same plane and their elementary mesh sides intersect so to form no more than a single mesh structure.
- Each of the grids elementary has a substantially constant elementary mesh surface and the elementary mesh surfaces are substantially offset angularly between them.
- the elementary grids G1 and G2 are angularly offset by an angle ⁇ .
- the two elementary grids G1 and G2 have elementary meshes substantially square in shape.
- the elementary grids G1 and G2 have steps respective a1 and a2.
- the elementary grids advantageously all have the not even, that is to say that the sides of the elementary meshes of one of the grids are respectively of length equal to that of the sides of the meshes other elementary grids. This will be the case for the fifth preferred numerical example relating to the second mode of production.
- the elementary grid G1 has elementary mesh sides which are respectively parallel to the two axes x and y perpendicular between them, while the elementary grid G2 has elementary mesh sides which are respectively parallel to the two axes X and Y perpendicular between them.
- the inductive grid structure can have more than two grids elementary.
- the structure comprising N elementary grids, the grids elementary are preferably offset between them by an angle equal to substantially ⁇ / 2N, especially when there are three or more elementary grids.
- the grids are shifted by ⁇ / 4 and it can appear the same problem of overlap of diffraction peaks as in the case of Figure 2, but in a very attenuated because recoveries can only occur between the secondary peaks of one grid and the main peaks of the other.
- the pics diffraction principal correspond to the energy diffracted in the directions parallel to the sides of the grid, while secondary peaks of diffraction correspond to the energy diffracted in the directions not parallel to the sides of the grid, this energy being much lower the more often to that of the main diffraction peaks.
- Each of the elementary grids diffracts, at least mainly, along different axes.
- the elementary grid G1 diffracts mainly along the x and y directions, while the elementary grid G2 diffracts mainly along the X and Y directions.
- the optical diffraction energy is spatially distributed more evenly than in the case of a single grid, and even more uniformly than in the case of grids elementaries of the same orientation as in the case of FIG. 2, since here not only the diffraction figures of the elementary grids little or no overlap, but the very directions in which they extend are distinct.
- Optical diffraction energy is spatially distributed in many directions and no longer only mainly in two privileged directions as in the case of figure 2.
- the screen microwave appears best around 6dB, which represents a very clear improvement in the microwave / optical compromise.
- the superposition of two elementary grids each presenting a screen -16dB microwave does not result in screenings resulting from -32dB which would be the sum of the previous screens, because the distance between the elementary grids is sufficiently weak (here it is even zero since the grids are in the same plane) so that the two grids elementals interact on the waves that pass through them.
- FIG. 4 schematically represents a third mode particular for producing an inductive grid structure according to the invention comprising at least one grid like that shown in Figure 4.
- the FIG. 4 represents a Gap grid whose aperiodic character is important.
- the elementary meshes have substantially the same surface and the same shape.
- the size elementary mesh is sufficiently small in front of the lengths of wave microwave so that the elementary meshes appear all similar when viewed by wavelengths microwave.
- the Gap grid has microwave properties comparable to those of a single periodic grid such as for example a grid with square patterns, and it can in the same way screen substantially in the microwave domain.
- a grid single periodic generally has peaks of intensity diffractions relative high.
- the sides of the stitches are oriented so that the diffraction zones of the structure are spatially distributed so substantially homogeneous.
- the irregularity of the orientation of elementary meshes destroyed "at the optical wavelength scale", at least to some extent the periodicity of grid G.
- the diffraction energy optical is for example spatially distributed in more than two directions and / or according to non-rectilinear shapes and / or according to larger areas that the very localized diffraction peaks of a single periodic grid, thus resulting in a substantially homogeneous spatial distribution.
- the grid G does not have an acute angle between adjacent sides of elementary mesh, because the acute angles between meshes elementary are at the source of local diffraction phenomena but intense. All the angles between adjacent sides of elementary mesh are advantageously substantially equal to ⁇ / 2.
- Two adjacent sides of the elementary mesh mj are for example c1 and c2.
- the preferred shape of the grid G shown in FIG. 4 is a grid whose elementary meshes are angular sectors of concentric rings.
- the grid G comprises a central circular zone O comprising one or more elementary meshes, here two.
- Around this central circular area O are a set of concentric rings, here three.
- the concentric rings P, Q and R which are here the first, second and third peripheral rings, each comprise several elementary meshes of the type of the mid mesh or of the mesh mj.
- the crowns have widths which are substantially constant and substantially equal to each other.
- the central circular zone O can be considered as the central crown in the formula below.
- the M th peripheral ring starting from the central crown advantageously comprises K (2M + 1) elementary meshes.
- the elementary meshes all have substantially the same surface and the same shape as the meshes mi and mj.
- the third peripheral crown will then have fourteen.
- the grid G preferably has roughly an axial symmetry, as for example in FIG. 4, for reasons of polarization symmetry.
- the grid G can present, on the scale optical wavelengths, elementary mesh sides whose irregularity of the orientation is more marked than in the case of line segments joining the interior and exterior perimeters of the same crowned.
- the sides of the elementary meshes connecting the interior perimeters and outside of the same crown can then advantageously be inclined from normal to the perimeters of the crowns.
- These sides elementary stitches can also not be rectilinear. for example arcs of a circle between the perimeters of the crowns would allow better yet spatially distribute the optical diffraction energy in space.
- Another solution could use at least one grid made up by a set of elliptical shapes whose major axes all have different lengths and / or different directions. So almost none sides of the elementary meshes would not be parallel between them and the optical diffraction energy would be spatially distributed so all the more uniform.
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Abstract
Description
- la figure 1 représente schématiquement une maille élémentaire d'une grille à motifs carrés selon le troisième art antérieur ;
- la figure 2 représente schématiquement un premier mode particulier de réalisation d'une structure inductive grillagée selon l'invention ;
- la figure 3 représente schématiquement un deuxième mode particulier de réalisation d'une structure inductive grillagée selon l'invention ;
- la figure 4 représente schématiquement un troisième mode particulier de réalisation d'une structure inductive grillagée selon l'invention.
Ordre de diffraction | G1 | G2 | SIG |
0(G1) ; 0(G2) ; 0(SIG) | 1 | 1 | 1 |
1(G2) ; 1(SIG) | ≈0 | 0,029 | 0,03 |
1(G1) ; 2(SIG) | 0,064 | ≈0 | 0,067 |
2(G2) ; 3(SIG) | ≈0 | 0,025 | 0,024 |
2(G1) ; 4SIG) | 0,037 | ≈0 | 0,032 |
3(G2) ; 5(SIG) | ≈0 | 0,024 | 0,02 |
3(G1) ; 4(G2) ; 6(SIG) | 0,023 | 0,011 | 0,039 |
G1 | G2 | SIG | |
E1,0/E0,0 | 2,5x10-5 | 2,1x10-5 | 2,5x10-5 |
T2-18GHz | -25,4 | -24,5 | -31,4 |
G1 | G2 | SIG | Geqhyp | |
Eoptique | 0,998 | 0,998 | 0.996 | 0,996 |
E0,0 | 0,996 | 0,996 | 0,992 | 0,992 |
Ei,0/E0,0 | 10-6 | 9,1x10-7 | 10-6 | 4x10-6 |
T2-18GHz | -8,2 | -7,8 | -13 | -13 |
Eoptique | E0,0 | Ei,0/E0,0 | T2-18GHz | |
SIG(G1 à G2) | 0,996 | 0,992 | 10-6 | -13 |
SIG(G1 à G3) | 0,994 | 0,988 | 10-6 | -15,4 |
SIG(G1 à G4) | 0,992 | 0,985 | 10-6 | -17,5 |
SIG(G1 à G5) | 0,99 | 0,982 | 10-6 | -19,1 |
SIG(G1 à G6) | 0,988 | 0,979 | 10-6 | -20,5 |
Geqhyp | 0,991 | 0,983 | 1,9x10-5 | -20,5 |
Geqopt | 0,998 | 0,996 | 10-6 | -8,2 |
G1 | G2 | SIG | |
E1,0/E0,0 | ≈10-5 | ≈10-5 | ≈10-5 |
T2-18GHz | -16 | -16 | -22,1 |
Claims (22)
- Structure inductive grillagée (SIG) comportant des mailles (mi, mj) élémentaires dont les côtés (c1, c2) sont en fil électriquement conducteur, le taux de recouvrement moyen des mailles élémentaires étant d'une part suffisamment élevé pour que la structure écrante substantiellement dans un domaine spectral hyperfréquence donné et d'autre part suffisamment faible pour que la structure soit substantiellement transparente dans un domaine spectral optique donné, caractérisé en ce que les côtés des mailles (mi, mj) sont orientés de manière suffisamment irrégulière pour répartir spatialement de manière plus uniforme que dans le cas d'une grille unique périodique, l'énergie de diffraction dans le domaine spectral optique.
- Structure selon la revendication 1, caractérisé en ce que la structure (SIG) comporte plusieurs grilles élémentaires (G1, G2) diffractant chacune selon une figure de pics de diffraction et en ce que les figures de pics de diffraction sont substantiellement décalées spatialement entre elles.
- Structure selon la revendication 2, caractérisé en ce que l'intensité des pics de diffraction correspondants reste sensiblement constante d'une figure à l'autre.
- Structure selon l'une quelconque des revendications 2 à 3, caractérisé en ce que les grilles élémentaires (G1, G2) sont au nombre de deux.
- Structure selon l'une quelconque des revendications 2 à 4, caractérisé en ce que les grilles élémentaires (G1, G2) ont sensiblement le même taux de recouvrement et ont des mailles élémentaires de forme substantiellement carrée.
- Structure selon l'une quelconque des revendications 2 à 5, caractérisé en ce que les grilles élémentaires (G1, G2) appartiennent à des surfaces sensiblement parallèles et sont substantiellement décalées angulairement entre elles.
- Structure selon les revendications 5 et 6, caractérisé en ce que les grilles élémentaires (G1, G2) ont toutes le même pas (a1, a2).
- Structure selon l'une quelconque des revendications 6 à 7, caractérisé en ce que la structure (SIG) comportant N grilles élémentaires (G1, G2), les grilles élémentaires sont décalées entre elles d'un angle (a) valant sensiblement π/2N.
- Structure selon l'une quelconque des revendications 2 à 5, caractérisé en ce que les grilles élémentaires (G1, G2) appartiennent à des surfaces sensiblement parallèles et ont chacune une surface de maille élémentaire sensiblement constante, et en ce que les surfaces de maille élémentaire sont substantiellement différentes entre grilles élémentaires (G1, G2).
- Structure selon la revendication 9, caractérisé en ce que les grilles élémentaires (G1, G2) ont toutes la même orientation.
- Structure selon les revendications 5 et 10, caractérisé en ce que les pas des différentes grilles élémentaires (G1, G2) sont choisis de manière à ce que tout pic de diffraction résultant de la superposition totale ou partielle de plusieurs pics de diffraction provenant de grilles élémentaires (G1, G2) différentes a une intensité qui est inférieure ou sensiblement égale au majorant de l'ensemble des intensités des pics de diffraction au premier ordre de toutes les grilles élémentaires (G1, G2).
- Fenêtre optique comportant une structure selon les revendications 5 et 10 ou selon la revendication 11, caractérisé en ce que les pas (a1, a2) des différentes grilles élémentaires (G1, G2) sont choisis de manière à ce que tout pic de diffraction résultant de la superposition totale ou partielle de plusieurs pics de diffraction provenant de grilles élémentaires (G1, G2) différentes et dont l'intensité est supérieure ou sensiblement égale au majorant de l'ensemble des intensités des pics de diffraction au premier ordre de toutes les grilles élémentaires (G1, G2), est situé hors du champ de la fenêtre optique.
- Structure selon la revendication 1, caractérisé en ce que les mailles élémentaires (mi, mj) ont sensiblement la même surface et la même forme et en ce que les côtés des mailles sont orientés de manière à ce que les zones de diffraction de la structure soient spatialement réparties de façon sensiblement homogène.
- Structure selon la revendication 13, caractérisé en ce que la structure (SIG) ne comporte pas d'angle aigu entre côtés adjacents (c1, c2) de maille élémentaire (mj).
- Structure selon la revendication 14, caractérisé en ce que tous les angles entre côtés adjacents (c1, c2) de maille élémentaire (mj) sont sensiblement égaux à π/2.
- Structure selon l'une quelconque des revendications 13 à 15, caractérisé en ce que la structure (SIG) comporte au moins une grille (Gap) dont les mailles élémentaires (mi, mj) sont des secteurs angulaires de couronnes concentriques (O, P, Q, R).
- Structure selon la revendication 16, caractérisé en ce que les couronnes (O, P, Q, R) ont des largeurs (I) sensiblement constantes et sensiblement égales entre elles.
- Structure selon la revendication 17, caractérisé en ce que la couronne centrale (O) comportant K mailles élémentaires, la Mième couronne périphérique (P, Q, R) à partir de la couronne centrale (O) comporte K(2M+1) mailles élémentaires.
- Structure selon l'une quelconque des revendications 16 à 18, caractérisé en ce que les côtés (c2) des mailles élémentaires (mj) reliant les périmètres (p1, p2) d'une même couronne (R) sont inclinés par rapport à la normale aux périmètres (p1, p2) de la couronne (R).
- Structure selon l'une quelconque des revendications 16 à 19, caractérisé en ce que les côtés (c2) des mailles élémentaires (mj) reliant les périmètres (p1, p2) d'une même couronne (R) ne sont pas rectilignes.
- Structure selon l'une quelconque des revendications 13 à 15, caractérisé en ce que la structure (SIG) comporte au moins une grille constituée par un ensemble de formes elliptiques dont les grands axes ont tous des longueurs différentes et/ou des directions différentes.
- Structure selon l'une quelconque des revendications 13 à 21, caractérisé en ce que la structure (SIG) présente une symétrie axiale dans le plan de la structure (SIG).
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR9906001A FR2793645B1 (fr) | 1999-05-11 | 1999-05-11 | Structure inductive grillagee |
FR9906001 | 1999-05-11 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP1052724A1 true EP1052724A1 (fr) | 2000-11-15 |
EP1052724B1 EP1052724B1 (fr) | 2003-07-09 |
Family
ID=9545467
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP20000401264 Expired - Lifetime EP1052724B1 (fr) | 1999-05-11 | 2000-05-09 | Structure inductive grillagée |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP1052724B1 (fr) |
DE (1) | DE60003753T2 (fr) |
FR (1) | FR2793645B1 (fr) |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0468623A1 (fr) * | 1990-07-24 | 1992-01-29 | British Aerospace Public Limited Company | Assemblage stratifié de surfaces sélectives en fréquence et procédé adapté de modulation des caractéristiques de puissance et fréquence |
JPH04349422A (ja) * | 1991-05-27 | 1992-12-03 | Kuraray Co Ltd | 光学的ローパスフィルタおよびそれを備えた撮像装置 |
US5793505A (en) * | 1986-03-11 | 1998-08-11 | The United States Of America As Represented By The Secretary Of The Army | Fabry-Perot multiwavelength infrared filter with artificial dielectric |
FR2767018A1 (fr) * | 1997-07-29 | 1999-02-05 | Thomson Csf | Reseau bi-periodique a proprietes optiques optimisees |
-
1999
- 1999-05-11 FR FR9906001A patent/FR2793645B1/fr not_active Expired - Fee Related
-
2000
- 2000-05-09 EP EP20000401264 patent/EP1052724B1/fr not_active Expired - Lifetime
- 2000-05-09 DE DE2000603753 patent/DE60003753T2/de not_active Expired - Lifetime
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5793505A (en) * | 1986-03-11 | 1998-08-11 | The United States Of America As Represented By The Secretary Of The Army | Fabry-Perot multiwavelength infrared filter with artificial dielectric |
EP0468623A1 (fr) * | 1990-07-24 | 1992-01-29 | British Aerospace Public Limited Company | Assemblage stratifié de surfaces sélectives en fréquence et procédé adapté de modulation des caractéristiques de puissance et fréquence |
JPH04349422A (ja) * | 1991-05-27 | 1992-12-03 | Kuraray Co Ltd | 光学的ローパスフィルタおよびそれを備えた撮像装置 |
FR2767018A1 (fr) * | 1997-07-29 | 1999-02-05 | Thomson Csf | Reseau bi-periodique a proprietes optiques optimisees |
Non-Patent Citations (1)
Title |
---|
PATENT ABSTRACTS OF JAPAN vol. 017, no. 210 (P - 1526) 23 April 1993 (1993-04-23) * |
Also Published As
Publication number | Publication date |
---|---|
FR2793645A1 (fr) | 2000-11-17 |
FR2793645B1 (fr) | 2001-08-10 |
DE60003753T2 (de) | 2004-06-03 |
EP1052724B1 (fr) | 2003-07-09 |
DE60003753D1 (de) | 2003-08-14 |
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