EP1972882B1 - Elektromagnetisches Fenster - Google Patents

Elektromagnetisches Fenster Download PDF

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Publication number
EP1972882B1
EP1972882B1 EP08102854.0A EP08102854A EP1972882B1 EP 1972882 B1 EP1972882 B1 EP 1972882B1 EP 08102854 A EP08102854 A EP 08102854A EP 1972882 B1 EP1972882 B1 EP 1972882B1
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EP
European Patent Office
Prior art keywords
supports
window according
networks
electromagnetic
conductive patterns
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
EP08102854.0A
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English (en)
French (fr)
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EP1972882A1 (de
Inventor
Gérard LEFLOUR
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Dassault Aviation SA
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Dassault Aviation SA
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Publication of EP1972882A1 publication Critical patent/EP1972882A1/de
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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/27—Adaptation for use in or on movable bodies
    • H01Q1/28—Adaptation for use in or on aircraft, missiles, satellites, or balloons
    • H01Q1/281—Nose antennas
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F41—WEAPONS
    • F41H—ARMOUR; ARMOURED TURRETS; ARMOURED OR ARMED VEHICLES; MEANS OF ATTACK OR DEFENCE, e.g. CAMOUFLAGE, IN GENERAL
    • F41H5/00—Armour; Armour plates
    • F41H5/26—Peepholes; Windows; Loopholes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
    • F42B10/00—Means for influencing, e.g. improving, the aerodynamic properties of projectiles or missiles; Arrangements on projectiles or missiles for stabilising, steering, range-reducing, range-increasing or fall-retarding
    • F42B10/32—Range-reducing or range-increasing arrangements; Fall-retarding means
    • F42B10/38—Range-increasing arrangements
    • F42B10/42—Streamlined projectiles
    • F42B10/46—Streamlined nose cones; Windshields; Radomes
    • 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
    • H01Q15/14—Reflecting surfaces; Equivalent structures
    • H01Q15/147—Reflecting surfaces; Equivalent structures provided with means for controlling or monitoring the shape of the reflecting surface
    • 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
    • H01Q15/14—Reflecting surfaces; Equivalent structures
    • H01Q15/148—Reflecting surfaces; Equivalent structures with means for varying the reflecting properties

Definitions

  • the present invention relates to an electromagnetic window with variable and controlled electromagnetic transparency and, more particularly, to such a switchable window between first and second so-called passing states and blocked respectively.
  • Such a window can be used, for example, to temporarily protect a device sensitive to a disturbing external electromagnetic field.
  • the blocking of the window makes it possible to erase the radar signature of an antenna, for example, placed behind the window.
  • Such windows are known comprising walls of metallic material, these walls being movable between a closed position in which they stop the electromagnetic radiation and an open position in which they pass this radiation.
  • These windows have several disadvantages. In the first place, the passage from one position to another using mechanical means for moving the metal walls, this results in a relatively long switching time between the two states of the window. In addition, the electrical contact between the different metal walls of the window may be defective and generates leakage of the electromagnetic field through the window.
  • WO 94/00892 A a frequency guide type device which has at least one frequency selection surface and which can be used as an antenna or radome in the communications systems.
  • the frequency selection surface may include first and second rows of electrically conductive elements on a dielectric substrate or dielectric elements on an electrically conductive substrate. By moving the first row of elements relative to the second row of elements, it is possible to adjust the frequency response.
  • Document is known FR 2,711,846 a concealment device for a radar antenna.
  • the device has several hollow elements in the form of concentric mounted cones, which can be moved relative to each other by means of adjusting jacks.
  • the cavities between the concentric cones each communicate with a dielectric fluid reservoir.
  • the adjustment of the cone position is achieved by mechanical means.
  • the device filters certain frequencies.
  • Such a device is specifically adapted to be made in the outer carcass of a flying machine and is expensive to produce.
  • the present invention is specifically intended to provide a switchable electromagnetic window between on and off states that does not have these disadvantages. More specifically, the object of the invention is to provide such a window which is inexpensive and has a very wide bandwidth, for example from 0 to 40 GHz.
  • the window is opaque or transparent to electromagnetic radiation depending on whether these networks are coupled or decoupled.
  • the supports made of dielectric material, on which act the means for arranging them in one position or another make it possible to overcome the problems of electromagnetic leakage of the known devices mentioned above.
  • the means chosen to arrange the supports in one position or another it is possible to achieve switching times between the two very short window states.
  • the invention also relates to the use of such a window for the temporary deletion of the radar signature of a device placed behind this window.
  • FIG. 1 of the accompanying drawing which illustrates the operation of the electromagnetic window according to the present invention. This is switchable between two so-called “passing” and “blocked” states respectively, by means which will be described later.
  • the wave And transmitted by the window F is of amplitude substantially equal to that of the incident wave Ei.
  • the amplitude of Et is almost zero while the amplitude of the reflected wave Er is substantially equal to that of Ei.
  • FIGS. 2A to 2D schematically represent the structure of the essential elements of the window according to the invention.
  • the latter thus comprises first and second planar supports 1 and 3 respectively, made of dielectric material, carrying pattern arrays such as 2 and 4 respectively, of electrically conductive material.
  • these patterns 2 and 4 are in the form of conformal elongated rectangles, arranged in parallel and equidistant lines, each pattern being physically separated, and therefore electrically isolated, from the adjacent patterns so as to constitute an electric conduction island. separate.
  • Such patterns of conductive patterns can be achieved cheaply by conventional photoengraving techniques, well known in the manufacture of printed circuits.
  • the supports 1 and 3 are arranged in such a way that the patterns of conductive patterns they carry are oriented orthogonally to one another. It is conceivable that by superimposing on one another the faces of these supports which carry networks thus oriented (see Figs. 3B and 3D ), an electrical coupling is established between the patterns of the two networks. If the patterns of the two networks are in physical contact with each other, this coupling establishes an electrical conduction between these patterns. If the patterns of the two networks remain opposite, a small distance in a dielectric medium 5, there is established a capacitive effect by electrostatic influence between the two networks.
  • This bandwidth also determines the sizing of the conductive patterns. Thus, the dimensions of these must be less than half the wavelength corresponding to the maximum frequency limiting this bandwidth.
  • the supports 1 and 3 may consist, for example, of a polyimide material of 50 .mu.m thick.
  • the distance or distance 8 between the supports varies from the contact for the blocked state to a distance greater than 1 mm for the on state.
  • FIG. 4 a first embodiment of the window according to the invention, showing the means which act on the window to change it from its state to its off state or vice versa.
  • the supports 1 and 3 and the patterns networks 2 and 4 are shaped as described above and are fixed on jaws 9 and 9 'respectively, of dielectric material, arranged parallel to each other. Cylinders 10, 10 'make it possible to pass their spacing 8, in the medium 5, from a substantially zero value corresponding to the locked state to a predetermined value, advantageously greater than 1 mm, which eliminates any coupling between these networks for establish the passing state.
  • FIG 5 another embodiment of the invention in which the network supports 1 and 3 define, with a flexible membrane 11 device, an enclosure isolated from the surrounding medium.
  • Pneumatic means such as a pump 12 are connected to this chamber to selectively vary the pressure Pi prevailing therein with respect to the external pressure Pe.
  • the enclosure contracts and the two networks of conductive patterns are pressed against each other.
  • the window is then in its locked state.
  • By raising the pressure Pi above Pe it causes the swelling of the enclosure and the separation of the two networks, which restores the passing state of the window.
  • the network supports are rigid.
  • Representatives Figures 6 and 7 another embodiment of the invention wherein these supports must, on the contrary, be flexible.
  • it can then be used to form these supports 1 and 3 a polyimide film of a few tens of microns thick.
  • an enclosure is formed by surrounding the supports 1 and 3 with a flange 13 cooperating with a shim 14 open at 14a resting on the peripheral metallizations 15, 15 'facing the supports on which the pattern gratings are formed. conductors.
  • a pump 12 makes it possible to act on the pressure of the dielectric medium 5 contained in the enclosure with respect to the pressure prevailing outside this enclosure. This is how the supports can move from the schematic position to the figure 6 where they are separated (passing state) at the position of the figure 7 where, thanks to their flexibility, they are joined by a suitable suction developed by the pump 12 (blocked state).
  • the embodiment of the invention whose structure and operation are illustrated by the Figures 8 and 9 is adapted to the protection of an electromagnetic sensor 16 protected by a conically shaped radome 17. This is typically the case of an aircraft radar or guided missile system. When such an installation is inactive, it is often desirable to remove the radar signature. This is precisely the role of the embodiment of the window according to the invention represented by the Figures 8 and 9 .
  • the supports 1 and 3 are thus fixed on the inner face of the radome 17 and on the outer face of a central rigid conical part 18 respectively.
  • the conical part 18 is movable coaxially with the radome 17, by sliding on an axis 19.
  • a sealed enclosure is defined by the radome 17, the part 18 and a flexible peripheral membrane 11.
  • a pump 12 connected to this enclosure by a conduit 20 of dielectric material controls the pressure in the enclosure. It will be noted that this pump 12 is placed behind the sensor 16 so as not to disturb the propagation of electromagnetic waves in the cavity located in front of this sensor.
  • the attenuation in transmission is of the order of -0.5 dB at 10 GHz and of the order of -2.5 dB at 30 GHz.
  • the window structure according to the invention thus very effectively minimizes the lack of transparency in the on state.
  • the present invention makes it possible to achieve the goals announced, namely to provide an electromagnetic window that can be performed cost-cost, while having high performance, especially in terms of bandwidth.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Electromagnetism (AREA)
  • Fluid Mechanics (AREA)
  • Astronomy & Astrophysics (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • General Physics & Mathematics (AREA)
  • Remote Sensing (AREA)
  • Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)
  • Aerials With Secondary Devices (AREA)

Claims (14)

  1. Elektromagnetisches Fenster (F), welches zwischen einem ersten und einem zweiten Zustand, die Durchlass- bzw. Sperr- genannt werden, umschaltbar ist gegenüber der Übertragung von elektromagnetischen Wellen durch das besagte Fenster, welches aufweist mindestens ein erstes (1) und ein zweites (3) Halteelement aus dielektrischem Material, ein erstes und ein zweites Netz an Leitermustern (2, 4) für Strom, die von dem besagten ersten (1) bzw. zweiten (2) Halteelement getragen werden, wobei die Muster (2, 4) von jedem Netz gegeneinander elektrisch isoliert sind, dadurch gekennzeichnet, dass es Mittel aufweist, die auf die besagten Halteelemente (1, 3) wirken, um sie selektiv in der einen oder der anderen von einer ersten und einer zweiten Relativ-Position anzuordnen, die zu dem besagten Durchlass- bzw. Sperr-Zustand korrespondieren, in welchen Positionen die besagten Netze an Leitermustern (2, 4) elektrisch entkoppelt bzw. gekoppelt sind, wobei die besagten Netze das Fließen von elektrischen Strömen an ihrer gesamten Oberfläche erlauben, wenn sie in ihrer zweiten Relativ-Position elektrisch gekoppelt sind.
  2. Elektromagnetisches Fenster gemäß Anspruch 1, dadurch gekennzeichnet, dass in der besagten zweiten Relativ-Position die besagten Netze mittels elektrischen Kontakts gekoppelt sind.
  3. Elektromagnetisches Fenster gemäß Anspruch 1, dadurch gekennzeichnet, dass in der besagten zweiten Relativ-Position die besagten Netze mittels eines kapazitiven Effekts gekoppelt sind.
  4. Elektromagnetisches Fenster gemäß irgendeinem der Ansprüche 1 bis 3, dadurch gekennzeichnet, dass in der besagten ersten Relativ-Position die besagten Netze um eine Entfernung voneinander getrennt sind, die ausreichend ist, um jede merkliche kapazitive Kopplung zu vermeiden.
  5. Elektromagnetisches Fenster gemäß irgendeinem der vorherigen Ansprüche, dadurch gekennzeichnet, dass die Abmessungen der besagten Leitermuster (2, 4) geringer sind als die Hälfte der Wellenlänge der maximalen Betriebs-Frequenz, die dem besagten Fenster zugeordnet ist.
  6. Elektromagnetisches Fenster gemäß irgendeinem der vorherigen Ansprüche, dadurch gekennzeichnet, dass die besagten Leitermuster (2, 4) der besagten Netze in ihrer zweiten Relativ-Position zusammen Trennungsmuster (6) abgrenzen, wo sie nicht überlagert sind, und dadurch, dass der Umfang der besagten Trennungsmuster geringer ist als die kleinste Betriebs-Wellenlänge, die dem besagten Fenster zugeordnet ist.
  7. Elektromagnetisches Fenster gemäß irgendeinem der vorherigen Ansprüche, dadurch gekennzeichnet, dass die besagten Halteelemente (1, 3) der Leitermuster eben und parallel zueinander angeordnet sind.
  8. Elektromagnetisches Fenster gemäß irgendeinem der Ansprüche 1 bis 6, dadurch gekennzeichnet, dass die besagten Halteelement (1, 3) der Leitermuster konisch und koaxial zueinander angeordnet sind.
  9. Elektromagnetisches Fenster gemäß irgendeinem der vorherigen Ansprüche, dadurch gekennzeichnet, dass die besagten Mittel, die auf die Relativ-Position der besagten Halteelemente der Leitermuster wirken, mechanische Mittel (10) sind.
  10. Elektromagnetisches Fenster gemäß irgendeinem der Ansprüche 1 bis 8, dadurch gekennzeichnet, dass die besagten Mittel, die auf die Relativ-Position der besagten Halteelemente der Leitermuster wirken, pneumatische Mittel (12) sind.
  11. Elektromagnetisches Fenster gemäß Anspruch 10, dadurch gekennzeichnet, dass die besagten Halteelemente (1, 3) starr sind.
  12. Elektromagnetisches Fenster gemäß Anspruch 10, dadurch gekennzeichnet, dass die besagten Halteelemente (1, 3) flexibel sind.
  13. Elektromagnetisches Fenster gemäß irgendeinem der vorherigen Ansprüche, welches geeignet ist, um in dem Frequenzband von 0 bis 20 GHz zu funktionieren, dadurch gekennzeichnet, dass die besagten Leitermuster eine rechteckige Form haben mit der Länge (L1) und der Breite (L2), die gleich sind zu 1,75 mm bzw. 0,25 mm, wobei der Abstand (L3) zwischen aneinandergrenzenden Leitermustern 0,25 mm ist.
  14. Verwendung des Fensters gemäß irgendeinem der vorherigen Ansprüche zur temporären Unterdrückung der Radarsignatur einer Vorrichtung, die hinter dem besagten Fenster angeordnet ist.
EP08102854.0A 2007-03-21 2008-03-21 Elektromagnetisches Fenster Active EP1972882B1 (de)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR0702058A FR2914114B1 (fr) 2007-03-21 2007-03-21 Fenetre electromagnetique

Publications (2)

Publication Number Publication Date
EP1972882A1 EP1972882A1 (de) 2008-09-24
EP1972882B1 true EP1972882B1 (de) 2018-10-24

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EP08102854.0A Active EP1972882B1 (de) 2007-03-21 2008-03-21 Elektromagnetisches Fenster

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EP (1) EP1972882B1 (de)
FR (1) FR2914114B1 (de)

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3920110A1 (de) * 1989-06-20 1991-02-07 Dornier Luftfahrt Elektromagnetisches fenster/radarabsorber
WO1994000892A1 (en) * 1992-06-29 1994-01-06 Loughborough University Of Technology A waveguide and an antenna including a frequency selective surface
FR2697679B1 (fr) 1992-10-30 1994-11-25 Thomson Csf Déphaseur d'ondes électromagnétiques et application à une antenne à balayage électronique.
DE4336840C1 (de) * 1993-10-28 1995-02-09 Deutsche Aerospace Abdeckung für Radarantennen
US6300894B1 (en) * 1999-07-09 2001-10-09 Harris Corporation Antenna having electrically controllable radar cross-section

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FR2914114A1 (fr) 2008-09-26
FR2914114B1 (fr) 2009-06-26
EP1972882A1 (de) 2008-09-24

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