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EP0466579B1 - Double reflector with grids - Google Patents

Double reflector with grids Download PDF

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Publication number
EP0466579B1
EP0466579B1 EP19910401907 EP91401907A EP0466579B1 EP 0466579 B1 EP0466579 B1 EP 0466579B1 EP 19910401907 EP19910401907 EP 19910401907 EP 91401907 A EP91401907 A EP 91401907A EP 0466579 B1 EP0466579 B1 EP 0466579B1
Authority
EP
European Patent Office
Prior art keywords
reflector
double
front reflector
grid
stiffeners
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.)
Expired - Lifetime
Application number
EP19910401907
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German (de)
French (fr)
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EP0466579A1 (en
Inventor
Jean-Denis Lefebvre
Olivier Lach
Alain Noir
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Airbus Group SAS
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Airbus Group SAS
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Publication of EP0466579A1 publication Critical patent/EP0466579A1/en
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Publication of EP0466579B1 publication Critical patent/EP0466579B1/en
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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
    • H01Q15/14—Reflecting surfaces; Equivalent structures
    • H01Q15/22—Reflecting surfaces; Equivalent structures functioning also as polarisation filter
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q25/00—Antennas or antenna systems providing at least two radiating patterns
    • H01Q25/001—Crossed polarisation dual antennas

Definitions

  • the present invention relates to a grate bireflector, structure comprising two antenna reflectors, intended for the use of several pairs of radio waves of the same frequency, the waves of a pair being of orthogonal polarizations between them.
  • Antenna systems are known which allow frequency reuse by means of perpendicularly polarized sources and reflectors. Such systems are widely used in the field of satellite applications. For a given frequency, two perpendicularly polarized waves are produced by two separate decoupled sources; this doubles the transmission capacity for the same antenna system, compact and light.
  • the known devices have two reflectors in the form of a parabolic dish.
  • An example of such a device according to the prior art can be seen in FIG. 1, which is also similar to the antenna bireflector described in document GB-A-2 125 633.
  • the first reflector 10 covers the second reflector 12.
  • the cuvettes of the reflectors 10, 12 are for example, each consisting of a honeycomb core formed by a Kevlar fabric (Kevlar is a registered trademark of the EI Dupont Company), sandwiched between two skins, also made of Kevlar.
  • Kevlar is a registered trademark of the EI Dupont Company
  • a grid 14, 16 made of closely spaced parallel conductors which are oriented so that the reflectors reflect waves polarized perpendicularly.
  • the two reflectors 10, 12 are held together by fixing means comprising a peripheral structure 18, for example consisting of a honeycomb core of Kevlar and sandwiched between two Kevlar skins and support ribs 20 formed likewise.
  • Kevlar is chosen for its transparency properties to radio waves. But it is an expensive and difficult material to work: thus obtaining honeycomb structures is long and painful.
  • the known devices have two reflectors provided with different grids.
  • the production of these grids requires very delicate mechanical processes to be implemented.
  • the document FR-A-1 141 476 also describes a system of antennas directed with two reflectors for front and rear, of which the rear reflector, consisting of a single sheet, has no property of selectivity with respect to of the direction of polarization of the radiation to be reflected. This document however does not describe any filtering means between the two reflectors to eliminate any residual component of the polarized radiation intended for the first reflector.
  • the object of the present invention is to overcome these drawbacks: to reduce the cost of manufacturing by reducing the need for Kevlar and simplifying the production of a frequency reuse reflector system using a single reflector provided with a grid, the second reflector does not.
  • the invention recommends the use of a front reflector provided with a grid oriented so as to reflect radio waves linearly polarized in a determined direction of polarization and a rear reflector capable of reflecting radio waves without distinction of polarization .
  • the rear reflector requires only a continuous and reflective surface, without a grid, which can be of less expensive material and having better mechanical characteristics (in particular better rigidity) than Kevlar.
  • the present invention relates to a bireflector according to claim 1.
  • FIG. 2 a schematic representation of an antenna system with a bireflector according to the invention.
  • Two sources S1 and S2 deliver radio signals of the same frequency, linearly polarized and perpendicular to each other. These sources S1 and S2 are arranged on a support 22 which also maintains the bireflector 24.
  • the latter is composed of two reflectors 26, 28, for example in the form of a truncated section of parabola of revolution.
  • the front reflector 26 completely covers the rear reflector 28 and is maintained at a distance determined by assembly means 30. But the overlap of the reflectors 26, 28 can also be partial.
  • the spacing between the reflectors is such that it makes the focal axes of the reflectors parallel to each other without however being confused.
  • the reflectors in the form of a parabola of revolution in the embodiment more particularly shown, are centered and their centers (commonly called vertices) are offset with respect to each other.
  • the front reflector 26 is arranged so as to reflect one of the radio signals (that coming from the source S1 in this example) while it is transparent to the other.
  • the rear reflector 28 is capable of reflecting any radioelectric radiation without distinction of polarization.
  • FIG 3 is a schematic exploded view of a portion of the front reflector.
  • the latter comprises a shell 32 constituted by a honeycomb structure, for example Kevlar or any other material transparent to radio waves and having adequate rigidity qualities.
  • the shell 32 has a thickness eK chosen so as to optimize the radioelectric performance of the bireflector. In the example described and shown, the frequency range from 10 to 14 GHz, the thickness of a Kevlar structure is chosen to be 6.35 mm; in fact, the reflection coefficient of the structure presents approximately a maximum for this value.
  • the shell 32 On its front face, the shell 32 is covered by a skin 34, also made of Kevlar for example.
  • the skin 34 is covered with a grid 36 made of electrical conductors 38 spaced apart so that their projections on a plane perpendicular to the focal axis of the reflector are parallel to each other; moreover, in projection on this plane, the length and the pitch of these conductors are constant.
  • These conductors 38 may for example be copper strips; they are either fixed in a medium transparent to radio frequencies, for example polymides, or directly bonded using an epoxy type glue which does not degas under vacuum.
  • the bireflector comprises a filtering means which makes it possible to eliminate any residual component of the polarized radiation linearly reflected by the front reflector, to avoid its reflection by the rear reflector.
  • the filtering means is composed of a grid 40 of conductors arranged to reflect a linearly polarized radioelectric radiation, parallel to that reflected by the front reflector 26; this grid 40 is supported by the dorsal face of the shell 32 of the front reflector.
  • the projections of the filter conductors in a plane perpendicular to the focal axis of the reflector are parallel to each other and to the projections of the conductors of the front grid 36.
  • This second grid 40 is produced in a similar manner to the front grid 36.
  • a second skin 42 for example made of Kevlar, covers the filtering grid 40.
  • the filtering grid 40 introduces a certain symmetry into the structure of the front reflector 26, which has the advantage of improving its resistance. mechanical and its rigidity.
  • the radioelectric radiation emitted by the source S1 is therefore completely reflected by the front reflector 26.
  • the latter is almost transparent (by construction: choice of materials, positioning of the grids) to the radiation emitted by the source S2 which is reflected by the rear reflector.
  • Figure 4 is a schematic exploded view of a portion of the rear reflector. This one is able to reflect any radioelectric radiation independently of its polarization: it suffices to present a continuous surface reflecting the radio waves. It can therefore be produced without a grid and in less expensive materials, easier to work with, and having better thermomechanical characteristics than Kevlar.
  • the rear reflector 28 consists of a shell 44, having a honeycomb structure of conductive material, for example aluminum, sandwiched between two identical skins 46, each made of four layers 48, for example of carbon fibers.
  • the shell 44 has a thickness eA chosen so as to ensure good thermomechanical behavior of the bireflector.
  • the thickness eA is for example chosen, for an aluminum shell, in a range going from 20 to 40 mm. In the example described, eA is equal to 25 mm.
  • the number of layers 48 making up the skins 46 is also chosen to ensure good thermomechanical behavior of the assembly.
  • the orientation of the carbon fibers of each layer 48 is chosen so as to ensure on the one hand, the mechanical strength of the reflector, but also so that the latter has a coefficient of expansion substantially zero at operating temperatures.
  • Figure 5 shows schematically the assembly means joining the reflectors to each other.
  • This assembly means maintains the spacing between the reflectors. This spacing varies, depending on the position on the circumference of a reflector, from a minimum spacing to a maximum spacing, diametrically opposite.
  • the assembly means consists of a peripheral structure 50, two internal stiffeners 52 in the form of mutually parallel support ribs and spacers 54. These elements are held on the reflector rear 28 by bonding on shims 56, for example made of Kevlar or any other material transparent to radio waves and having the required thermomechanical properties, fixed to the rear reflector.
  • the shims 56 are for example fixed to the rear reflector by mechanical fixing means (not shown) which may or may not be removable.
  • the shims 56 are distributed along the peripheral structure on either side of the internal stiffeners 52 and the spacers 54.
  • the elements constituting the assembly means are bonded using an insulating adhesive which is not loaded on the dorsal face of the front reflector 26.
  • the peripheral structure 50 is made of honeycomb, for example Kevlar.
  • the internal stiffeners 52 also have a honeycomb structure, for example Kevlar. They are perforated so as to reduce their mass. They are arranged so as to disturb the radiation pattern of the reflectors as little as possible.
  • the projection PR of the stiffeners 52 on a plane P perpendicular to the focal axes AF of the reflectors is parallel to the projections PC of the conductors of the grids 38 of the front reflector 26.
  • the projection PR of the stiffeners 52 on the plane P perpendicular to the focal axes AF of the reflectors is perpendicular to the projections PC of the conductors of the grids 38 of the front reflector 26.
  • stiffeners 52 are fixed perpendicular to the dorsal face of the front reflector 26.
  • spacers 54 made of Kevlar or any other material transparent to radio waves and having the required rigidity. These spacers 54 are for example arranged at regular intervals, on an axis parallel to the internal stiffeners 52 and passing through the top of the rear reflector. The spacers 54 fixed to each of the reflectors reduce the thermomechanical deformations of the front reflector by stress by resting on the rear reflector which has a substantially zero coefficient of expansion.
  • a bi-reflector according to the invention thanks to the use of a rear reflector capable of reflecting any radio wave independently of its polarization makes it possible to simplify the construction of the assembly and to reduce costs. On the other hand, the materials used make it possible to obtain better thermomechanical stability of the assembly.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Aerials With Secondary Devices (AREA)

Description

La présente invention a pour objet un biréflecteur à grilles, structure comprenant deux réflecteurs d'antenne, destinée à l'utilisation de plusieurs paires d'ondes radioélectriques de même fréquence, les ondes d'une paire étant de polarisations orthogonales entre-elles.The present invention relates to a grate bireflector, structure comprising two antenna reflectors, intended for the use of several pairs of radio waves of the same frequency, the waves of a pair being of orthogonal polarizations between them.

On connaît des systèmes d'antenne qui permettent la réutilisation de fréquence au moyen de sources et de réflecteurs polarisés perpendiculairement. De tels systèmes sont largement utilisés dans le domaine des applications aux satellites. Pour une fréquence donnée, deux ondes polarisées perpendiculairement, sont produites par deux sources distinctes découplées ; on double ainsi la capacité de transmission pour un même système d'antenne, compact et de faible poids.Antenna systems are known which allow frequency reuse by means of perpendicularly polarized sources and reflectors. Such systems are widely used in the field of satellite applications. For a given frequency, two perpendicularly polarized waves are produced by two separate decoupled sources; this doubles the transmission capacity for the same antenna system, compact and light.

Les demandes de brevet français n° 2 571 898 et 2 590 081 respectivement déposées le 15 Octobre 1985 et le 12 Novembre 1986 décrivent des exemples de réalisation de ce type d'antenne à réutilisation de fréquence.French patent applications Nos. 2,571,898 and 2,590,081, respectively filed on October 15, 1985 and November 12, 1986, describe exemplary embodiments of this type of frequency reuse antenna.

D'une manière générale, les dispositifs connus présentent deux réflecteurs en forme de cuvette parabolique. On peut voir sur la figure 1, un exemple d'un tel dispositif selon l'art antérieur, qui s'apparente également au biréflecteur d'antenne décrit dans le document GB-A-2 125 633.In general, the known devices have two reflectors in the form of a parabolic dish. An example of such a device according to the prior art can be seen in FIG. 1, which is also similar to the antenna bireflector described in document GB-A-2 125 633.

Deux réflecteurs paraboliques 10, 12 sont superposés : le premier réflecteur 10 recouvre le deuxième réflecteur 12.Two parabolic reflectors 10, 12 are superposed: the first reflector 10 covers the second reflector 12.

Les cuvettes des réflecteurs 10, 12 sont par exemple, chacune constituée d'un noyau en nid d'abeilles formé d'un tissu en Kevlar (Kevlar est une marque déposée de la Société E.I. Dupont), pris en sandwich entre deux peaux, elles aussi en Kevlar.The cuvettes of the reflectors 10, 12 are for example, each consisting of a honeycomb core formed by a Kevlar fabric (Kevlar is a registered trademark of the EI Dupont Company), sandwiched between two skins, also made of Kevlar.

A l'intérieur de chaque cuvette, sur la peau la recouvrant, est fixée une grille 14, 16 faite de conducteurs parallèles étroitement rapprochés qui sont orientés de manière à ce que les réflecteurs réfléchissent des ondes polarisées perpendiculairement.Inside each bowl, on the skin covering it, is fixed a grid 14, 16 made of closely spaced parallel conductors which are oriented so that the reflectors reflect waves polarized perpendicularly.

Les deux réflecteurs 10, 12 sont maintenus solidaires par des moyens de fixation comprenant une structure périphérique 18, par exemple constituée d'un noyau en nid d'abeilles en Kevlar et pris en sandwich entre deux peaux en Kevlar et des nervures de support 20 constituées de même.The two reflectors 10, 12 are held together by fixing means comprising a peripheral structure 18, for example consisting of a honeycomb core of Kevlar and sandwiched between two Kevlar skins and support ribs 20 formed likewise.

Le Kevlar est choisi pour ses propriétés de transparence aux ondes radioélectriques. Mais c'est un matériau onéreux et difficile à travailler : ainsi l'obtention des structures en nid d'abeilles est longue et pénible.Kevlar is chosen for its transparency properties to radio waves. But it is an expensive and difficult material to work: thus obtaining honeycomb structures is long and painful.

D'autre part, les dispositifs connus possèdent deux réflecteurs munis de grilles différentes. Or, la réalisation de ces grilles demande des processus mécaniques très délicats à mettre en oeuvre.On the other hand, the known devices have two reflectors provided with different grids. However, the production of these grids requires very delicate mechanical processes to be implemented.

Le document FR-A-1 141 476 décrit également un système d'antennes dirigées à deux réflecteurs de renvoi avant et arrière, dont le réflecteur arrière, constitué d'une simple tôle, n'a aucune propriété de sélectivité vis-à-vis de la direction de polarisation de la radiation à réfléchir. Ce document toutefois ne décrit aucun moyen de filtrage entre les deux réflecteurs pour éliminer toute composante résiduelle du rayonnement polarisé destiné au premier réflecteur.The document FR-A-1 141 476 also describes a system of antennas directed with two reflectors for front and rear, of which the rear reflector, consisting of a single sheet, has no property of selectivity with respect to of the direction of polarization of the radiation to be reflected. This document however does not describe any filtering means between the two reflectors to eliminate any residual component of the polarized radiation intended for the first reflector.

Le but de la présente invention est de pallier ces inconvénients : diminuer le coût de fabrication en diminuant les besoins en Kevlar et simplifier la réalisation d'un système de réflecteurs à réutilisation de fréquence en utilisant un unique réflecteur muni d'une grille, le second réflecteur n'en possédant pas.The object of the present invention is to overcome these drawbacks: to reduce the cost of manufacturing by reducing the need for Kevlar and simplifying the production of a frequency reuse reflector system using a single reflector provided with a grid, the second reflector does not.

Pour cela, l'invention préconise l'utilisation d'un réflecteur avant muni d'une grille orientée de manière à réfléchir des ondes radioélectriques polarisées linéairement suivant une direction de polarisation déterminée et un réflecteur arrière apte à réfléchir des ondes radioélectriques sans distinction de polarisation.For this, the invention recommends the use of a front reflector provided with a grid oriented so as to reflect radio waves linearly polarized in a determined direction of polarization and a rear reflector capable of reflecting radio waves without distinction of polarization .

De cette manière, le réflecteur arrière ne nécessite qu'une surface continue et réfléchissante, sans grille, qui peut être en matériau moins onéreux et présentant de meilleures caractéristiques mécaniques (en particulier une meilleure rigidité) que le Kevlar.In this way, the rear reflector requires only a continuous and reflective surface, without a grid, which can be of less expensive material and having better mechanical characteristics (in particular better rigidity) than Kevlar.

De façon plus précise, la présente invention concerne un biréflecteur suivant la revendication 1.More specifically, the present invention relates to a bireflector according to claim 1.

D'autres caractéristiques et avantages de l'invention ressortiront mieux après la description qui suit, donnée à titre purement illustratif et nullement limitatif, en référence aux figures annexées dans lesquelles :

  • la figure 1, déjà décrite et se rapportant à l'art antérieur, représente schématiquement un système de réflecteurs pour réutilisation de fréquence,
  • la figure 2 est une vue schématique d'un système d'antenne muni d'un biréflecteur conforme à l'invention,
  • la figure 3 est une vue schématique en éclaté d'une portion du réflecteur avant,
  • la figure 4 est une vue schématique en éclaté d'une portion du réflecteur arrière,
  • la figure 5 représente schématiquement le moyen d'assemblage des réflecteurs avant et arrière,
  • les figures 6A et 6B représentent schématiquement le positionnement des raidisseurs internes.
Other characteristics and advantages of the invention will emerge better after the description which follows, given purely by way of illustration and in no way limiting, with reference to the appended figures. in which :
  • FIG. 1, already described and relating to the prior art, schematically represents a system of reflectors for frequency reuse,
  • FIG. 2 is a schematic view of an antenna system provided with a bireflector according to the invention,
  • FIG. 3 is a schematic exploded view of a portion of the front reflector,
  • FIG. 4 is a schematic exploded view of a portion of the rear reflector,
  • FIG. 5 schematically represents the means of assembling the front and rear reflectors,
  • FIGS. 6A and 6B schematically represent the positioning of the internal stiffeners.

On peut voir sur la figure 2 une représentation schématique d'un système d'antenne muni d'un biréflecteur conforme à l'invention.We can see in Figure 2 a schematic representation of an antenna system with a bireflector according to the invention.

Deux sources S1 et S2 délivrent des signaux radioélectriques de même fréquence, polarisés linéairement et perpendiculairement entre-eux. Ces sources S1 et S2 sont disposées sur un support 22 qui maintient aussi le biréflecteur 24. Ce dernier est composé de deux réflecteurs 26, 28, par exemple en forme d'une section tronquée de parabole de révolution.Two sources S1 and S2 deliver radio signals of the same frequency, linearly polarized and perpendicular to each other. These sources S1 and S2 are arranged on a support 22 which also maintains the bireflector 24. The latter is composed of two reflectors 26, 28, for example in the form of a truncated section of parabola of revolution.

Dans l'exemple de réalisation représenté sur la figure 2, le réflecteur avant 26 recouvre totalement le réflecteur arrière 28 et est maintenu à une distance déterminée par des moyens d'assemblage 30. Mais le recouvrement des réflecteurs 26, 28 peut aussi être partiel.In the embodiment shown in Figure 2, the front reflector 26 completely covers the rear reflector 28 and is maintained at a distance determined by assembly means 30. But the overlap of the reflectors 26, 28 can also be partial.

L'écartement entre les réflecteurs est tel qu'il rend les axes focaux des réflecteurs parallèles entre eux sans toutefois être confondus. Les réflecteurs en forme de parabole de révolution dans la réalisation plus particulièrement représentée, sont centrés et leurs centres (couramment appelés sommets) sont décalés l'un par rapport à l'autre.The spacing between the reflectors is such that it makes the focal axes of the reflectors parallel to each other without however being confused. The reflectors in the form of a parabola of revolution in the embodiment more particularly shown, are centered and their centers (commonly called vertices) are offset with respect to each other.

Le réflecteur avant 26 est agencé de manière à réfléchir l'un des signaux radioélectriques (celui provenant de la source S1 dans cet exemple) alors qu'il est transparent à l'autre. Le réflecteur arrière 28 est apte à réfléchir tout rayonnement radioélectrique sans distinction de polarisation.The front reflector 26 is arranged so as to reflect one of the radio signals (that coming from the source S1 in this example) while it is transparent to the other. The rear reflector 28 is capable of reflecting any radioelectric radiation without distinction of polarization.

La figure 3 est une vue schématique en éclaté d'une portion du réflecteur avant. Ce dernier comporte une coque 32 constituée par une structure en nid d'abeilles, par exemple en Kevlar ou en tout autre matériau transparent aux ondes radioélectriques et présentant des qualités de rigidité adéquates. La coque 32 présente une épaisseur eK choisie de manière à optimiser les performances radioélectriques du biréflecteur. Dans l'exemple décrit et représenté, la gamme des fréquences allant de 10 à 14 GHz, l'épaisseur d'une structure en Kevlar est choisie égale à 6,35 mm ; en effet, le coefficient de réflexion de la structure présente approximativement un maximum pour cette valeur. Sur sa face frontale, la coque 32 est recouverte par une peau 34, elle aussi en Kevlar par exemple.Figure 3 is a schematic exploded view of a portion of the front reflector. The latter comprises a shell 32 constituted by a honeycomb structure, for example Kevlar or any other material transparent to radio waves and having adequate rigidity qualities. The shell 32 has a thickness eK chosen so as to optimize the radioelectric performance of the bireflector. In the example described and shown, the frequency range from 10 to 14 GHz, the thickness of a Kevlar structure is chosen to be 6.35 mm; in fact, the reflection coefficient of the structure presents approximately a maximum for this value. On its front face, the shell 32 is covered by a skin 34, also made of Kevlar for example.

La peau 34 est recouverte d'une grille 36 faite de conducteurs électriques 38 écartés de manière à ce que leurs projections sur un plan perpendiculaire à l'axe focal du réflecteur soient parallèles entre-elles ; de plus, en projection sur ce plan, la longueur et le pas de ces conducteurs sont constants. Ces conducteurs 38 peuvent être par exemple des bandes de cuivre ; ils sont soit fixés dans un milieu transparent vis-à-vis des fréquences radioélectriques, par exemple polymide, soit directement collés à l'aide d'une colle de type époxy qui ne dégaze pas sous vide.The skin 34 is covered with a grid 36 made of electrical conductors 38 spaced apart so that their projections on a plane perpendicular to the focal axis of the reflector are parallel to each other; moreover, in projection on this plane, the length and the pitch of these conductors are constant. These conductors 38 may for example be copper strips; they are either fixed in a medium transparent to radio frequencies, for example polymides, or directly bonded using an epoxy type glue which does not degas under vacuum.

Selon une variante de réalisation avantageuse, le biréflecteur comporte un moyen de filtrage qui permet d'éliminer toute composante résiduelle du rayonnement polarisé linéairement réfléchi par le réflecteur avant, pour éviter sa réflexion par le réflecteur arrière.According to an advantageous alternative embodiment, the bireflector comprises a filtering means which makes it possible to eliminate any residual component of the polarized radiation linearly reflected by the front reflector, to avoid its reflection by the rear reflector.

Dans l'exemple de réalisation représenté sur la figure 3, le moyen de filtrage est composé d'une grille 40 de conducteurs agencée pour réfléchir un rayonnement radioélectrique polarisé linéairement, parallèle à celui réfléchi par le réflecteur avant 26 ; cette grille 40 est supportée par la face dorsale de la coque 32 du réflecteur avant. Les projections des conducteurs de filtrage dans un plan perpendiculaire à l'axe focal du réflecteur sont parallèles entre-elles et aux projections des conducteurs de la grille frontale 36. Cette seconde grille 40 est réalisée de manière similaire à la grille frontale 36.In the embodiment shown in Figure 3, the filtering means is composed of a grid 40 of conductors arranged to reflect a linearly polarized radioelectric radiation, parallel to that reflected by the front reflector 26; this grid 40 is supported by the dorsal face of the shell 32 of the front reflector. The projections of the filter conductors in a plane perpendicular to the focal axis of the reflector are parallel to each other and to the projections of the conductors of the front grid 36. This second grid 40 is produced in a similar manner to the front grid 36.

Une seconde peau 42, par exemple en Kevlar, recouvre la grille de filtrage 40.A second skin 42, for example made of Kevlar, covers the filtering grid 40.

Outre qu'elle permet d'éliminer toute composante résiduelle de l'onde réfléchie par le réflecteur avant 26, la grille de filtrage 40 introduit une certaine symétrie dans la structure du réflecteur avant 26, ce qui présente l'avantage d'améliorer sa tenue mécanique et sa rigidité.In addition to eliminating any residual component of the wave reflected by the front reflector 26, the filtering grid 40 introduces a certain symmetry into the structure of the front reflector 26, which has the advantage of improving its resistance. mechanical and its rigidity.

Le rayonnement radioélectrique émis par la source S1 est donc complètement réfléchi par le réflecteur avant 26. Par contre, celui-ci est quasi transparent (par construction : choix des matériaux, positionnement des grilles) au rayonnement émis par la source S2 qui est réfléchi par le réflecteur arrière.The radioelectric radiation emitted by the source S1 is therefore completely reflected by the front reflector 26. On the other hand, the latter is almost transparent (by construction: choice of materials, positioning of the grids) to the radiation emitted by the source S2 which is reflected by the rear reflector.

La figure 4 est une vue schématique en éclaté d'une portion du réflecteur arrière. Celui-ci est à même de réfléchir tout rayonnement radioélectrique indépendamment de sa polarisation : il lui suffit de présenter une surface continue réfléchissant les ondes radioélectriques. Il peut donc être réalisé sans grille et dans des matériaux moins onéreux, plus facile à travailler, et présentant de meilleures caractéristiques thermomécaniques que le Kevlar.Figure 4 is a schematic exploded view of a portion of the rear reflector. This one is able to reflect any radioelectric radiation independently of its polarization: it suffices to present a continuous surface reflecting the radio waves. It can therefore be produced without a grid and in less expensive materials, easier to work with, and having better thermomechanical characteristics than Kevlar.

Dans l'exemple représenté sur la figure 4, le réflecteur arrière 28 se compose d'une coque 44, présentant une structure en nid d'abeilles en matériau conducteur, par exemple en aluminium, prise en sandwich entre deux peaux identiques 46, constituées chacune de quatre couches 48, par exemple en fibres de carbone. La coque 44 présente une épaisseur eA choisie de manière à assurer une bonne tenue thermomécanique du biréflecteur. L'épaisseur eA est par exemple choisie, pour une coque en aluminium, dans une gamme allant de 20 à 40 mm. Dans l'exemple décrit, eA est égale à 25 mm.In the example shown in Figure 4, the rear reflector 28 consists of a shell 44, having a honeycomb structure of conductive material, for example aluminum, sandwiched between two identical skins 46, each made of four layers 48, for example of carbon fibers. The shell 44 has a thickness eA chosen so as to ensure good thermomechanical behavior of the bireflector. The thickness eA is for example chosen, for an aluminum shell, in a range going from 20 to 40 mm. In the example described, eA is equal to 25 mm.

Le nombre de couches 48 composant les peaux 46 est lui aussi choisi pour assurer un bon comportement thermomécanique de l'assemblage.The number of layers 48 making up the skins 46 is also chosen to ensure good thermomechanical behavior of the assembly.

L'orientation des fibres de carbone de chaque couche 48 est choisie de manière à assurer d'une part, la tenue mécanique du réflecteur, mais aussi de façon à ce que ce dernier présente un coefficient de dilatation sensiblement nul aux températures d'utilisation.The orientation of the carbon fibers of each layer 48 is chosen so as to ensure on the one hand, the mechanical strength of the reflector, but also so that the latter has a coefficient of expansion substantially zero at operating temperatures.

La figure 5 représente schématiquement le moyen d'assemblage solidarisant les réflecteurs entre-eux.Figure 5 shows schematically the assembly means joining the reflectors to each other.

Ce moyen d'assemblage permet de maintenir l'écartement entre les réflecteurs. Cet écartement varie, selon la position sur la circonférence d'un réflecteur, d'un écartement minimum à un écartement maximum, diamétralement opposé.This assembly means maintains the spacing between the reflectors. This spacing varies, depending on the position on the circumference of a reflector, from a minimum spacing to a maximum spacing, diametrically opposite.

Dans l'exemple de réalisation représenté, le moyen d'assemblage est constitué d'une structure périphérique 50, de deux raidisseurs internes 52 en forme de nervures de support parallèles entre-elles et d'entretoises 54. Ces éléments sont maintenus sur le réflecteur arrière 28 par collage sur des cales 56, par exemple en Kevlar ou en tout autre matériau transparent aux ondes radioélectriques et présentant les propriétés thermomécaniques requises, fixées sur le réflecteur arrière.In the embodiment shown, the assembly means consists of a peripheral structure 50, two internal stiffeners 52 in the form of mutually parallel support ribs and spacers 54. These elements are held on the reflector rear 28 by bonding on shims 56, for example made of Kevlar or any other material transparent to radio waves and having the required thermomechanical properties, fixed to the rear reflector.

Les cales 56 sont par exemple fixées sur le réflecteur arrière par des moyens mécaniques de fixation (non représentés) démontables ou non.The shims 56 are for example fixed to the rear reflector by mechanical fixing means (not shown) which may or may not be removable.

Les cales 56 sont réparties le long de la structure périphérique de part et d'autre des raidisseurs internes 52 et des entretoises 54.The shims 56 are distributed along the peripheral structure on either side of the internal stiffeners 52 and the spacers 54.

Les éléments constituant le moyen d'assemblage sont collés à l'aide d'une colle isolante non chargée sur la face dorsale du réflecteur avant 26.The elements constituting the assembly means are bonded using an insulating adhesive which is not loaded on the dorsal face of the front reflector 26.

La structure périphérique 50 est en nid d'abeilles, par exemple en Kevlar. Les raidisseurs internes 52 possèdent eux-aussi une structure en nid d'abeilles, par exemple en Kevlar. Ils sont ajourés de manière à réduire leur masse. Ils sont disposés de façon à perturber le moins possible le diagramme de rayonnement des réflecteurs.The peripheral structure 50 is made of honeycomb, for example Kevlar. The internal stiffeners 52 also have a honeycomb structure, for example Kevlar. They are perforated so as to reduce their mass. They are arranged so as to disturb the radiation pattern of the reflectors as little as possible.

Dans l'exemple représenté sur la figure 6A, la projection PR des raidisseurs 52 sur un plan P perpendiculaire aux axes focaux AF des réflecteurs est parallèle aux projections PC des conducteurs des grilles 38 du réflecteur avant 26.In the example shown in FIG. 6A, the projection PR of the stiffeners 52 on a plane P perpendicular to the focal axes AF of the reflectors is parallel to the projections PC of the conductors of the grids 38 of the front reflector 26.

Dans l'exemple représenté sur la figure 6B, la projection PR des raidisseurs 52 sur le plan P perpendiculaire aux axes focaux AF des réflecteurs est perpendiculaire aux projections PC des conducteurs des grilles 38 du réflecteur avant 26.In the example shown in FIG. 6B, the projection PR of the stiffeners 52 on the plane P perpendicular to the focal axes AF of the reflectors is perpendicular to the projections PC of the conductors of the grids 38 of the front reflector 26.

D'autre part, dans les deux cas, les raidisseurs 52 sont fixés perpendiculairement à la face dorsale du réflecteur avant 26.On the other hand, in both cases, the stiffeners 52 are fixed perpendicular to the dorsal face of the front reflector 26.

La compensation des déformations du réflecteur avant dues à des variations de température est obtenue par les entretoises 54, en Kevlar ou tout autre matériau transparent aux ondes radioélectriques et présentant la rigidité requise. Ces entretoises 54 sont par exemple disposées à intervalles réguliers, sur un axe parallèle aux raidisseurs internes 52 et passant par le sommet du réflecteur arrière. Les entretoises 54 fixées sur chacun des réflecteurs réduisent les déformations thermomécaniques du réflecteur avant par contrainte en prenant appui sur le réflecteur arrière qui présente un coefficient de dilatation sensiblement nul.Compensation for deformations of the front reflector due to temperature variations is obtained by spacers 54, made of Kevlar or any other material transparent to radio waves and having the required rigidity. These spacers 54 are for example arranged at regular intervals, on an axis parallel to the internal stiffeners 52 and passing through the top of the rear reflector. The spacers 54 fixed to each of the reflectors reduce the thermomechanical deformations of the front reflector by stress by resting on the rear reflector which has a substantially zero coefficient of expansion.

Un biréflecteur conforme à l'invention, grâce à l'utilisation d'un réflecteur arrière apte à réfléchir toute onde radioélectrique indépendamment de sa polarisation permet de simplifier la construction de l'ensemble et de réduire les coûts. D'autre part, les matériaux utilisés permettent d'obtenir une meilleure stabilité thermomécanique de l'ensemble.A bi-reflector according to the invention, thanks to the use of a rear reflector capable of reflecting any radio wave independently of its polarization makes it possible to simplify the construction of the assembly and to reduce costs. On the other hand, the materials used make it possible to obtain better thermomechanical stability of the assembly.

Claims (8)

  1. Antenna double reflector including:
    - one front reflector (26) composed of a shell (32) supporting a grid (36) of conductors (38) disposed in such a way as to reflect a linearly polarized radioelectric radiation,
    - a rear reflector (28) able to reflect a radioelectric radiation irrespective of its polarization,
    - a mounting device (30) able to keep the front reflector (26) at a specific distance from the rear reflector (28), the front reflector (26) overlapping, at least partially, the rear reflector (28),
    characterized in that it comprises a filtering device (40) disposed between the front reflector (26) and the rear reflector (28) and able to eliminate any residual component of the linearly polarized radiation reflected by the front reflector (26), said filtering device (40) being constituted by a grid of conductors disposed in such a way as to reflect a linearly polarized radioelectric radiation parallel to the one reflected by the front reflector (26), and in that the rear reflector (28) comprises a honeycomb-shaped structure (44) sandwiched between two skins (46) with at least one of said skins being made of a conductive material.
  2. Double reflector according to claim 1, characterized in that the filtering grid is supported by the dorsal face of the shell (32) of the front reflector (26).
  3. Double reflector according to claim 1, characterized in that the rear reflector (28) has an approximately nil coefficient of expansion.
  4. Double reflector according to claim 1, characterized in that said honeycomb structure (44) of the rear reflector has a selected thickness (eA) so as to optimize the thermomechanical behaviour of the double reflector.
  5. Double reflector according to claim 4, characterized in that said honeycomb structure (44) is made of aluminium with a thickness (eA) of between 20 and 40 mm.
  6. Double reflector according to claim 1, the mounting device (30) comprising, fixed firstly onto the dorsal face of the front reflector and secondly onto the front face of the rear reflector, one peripheral structure (50) and at least two rib-shaped internal support stiffeners (52), characterized in that the mounting device further comprises a device (54) to compensate any deformations of the front reflector due to temperature variations, said device to compensate deformations comprising braces (54) made of a material almost transparent to the radioelectric waves, each of these braces (54) being fixed to firstly the dorsal face of the front reflector and secondly to the front face of the rear reflector.
  7. Double reflector according to claim 6, characterized in that said internal stiffeners (52) have a projection (PR) onto a plane (P) perpendicular to the focal axes (AF) of the reflectors (26, 28), this projection being parallel to the projections (PC) of the conductors (38) of the grids (36) of the front reflector (26) and in that the stiffeners (52) are fixed perpendicular to the dorsal face of the front reflector (26).
  8. Double reflector according to claim 6, characterized in that said internal stiffeners (52) have a projection (PR) onto a plane (P) perpendicular to the focal axes (AF) of the reflectors (26, 28), this projection being perpendicular to the projections (PC) of the conductors (38) of the grid (36) of the front reflector (26) and in that the stiffeners (52) are fixed perpendicular to the dorsal face of the front reflector (26).
EP19910401907 1990-07-11 1991-07-09 Double reflector with grids Expired - Lifetime EP0466579B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9008828A FR2664750B1 (en) 1990-07-11 1990-07-11 GRILLE BIREFLECTOR.
FR9008828 1990-07-11

Publications (2)

Publication Number Publication Date
EP0466579A1 EP0466579A1 (en) 1992-01-15
EP0466579B1 true EP0466579B1 (en) 1995-01-04

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EP19910401907 Expired - Lifetime EP0466579B1 (en) 1990-07-11 1991-07-09 Double reflector with grids

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EP (1) EP0466579B1 (en)
JP (1) JP3208154B2 (en)
DE (1) DE69106443T2 (en)
ES (1) ES2067178T3 (en)
FR (1) FR2664750B1 (en)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2709380B1 (en) * 1993-08-23 1995-09-22 Alcatel Espace Bi-beam antenna with electronic scanning.
FR2719162B1 (en) * 1994-04-20 1996-12-06 Henri Sadones Wireless beam antenna with at least two directions of reflection.
DE19713735C1 (en) * 1997-04-03 1998-08-20 Daimler Benz Aerospace Ag Process for the production of polarization-selective reflectors
SE0100345D0 (en) * 2001-02-02 2001-02-02 Saab Ab Antenna system and reflector elements in antenna system
JP5305994B2 (en) * 2009-03-12 2013-10-02 三菱電機株式会社 Antenna device
DE202009003501U1 (en) * 2009-03-13 2009-05-20 Hps High Performance Space Structure Systems Gmbh Reflector system for a polarization-selective antenna with double linear polarization
US9214736B2 (en) * 2012-07-25 2015-12-15 Orbital Sciences Corporation Systems and methods for mitigating disturbances in a dual gridded reflector antenna

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH326809A (en) * 1954-11-11 1957-12-31 Patelhold Patentverwertung Directional antenna system with deflecting mirrors
FR2412961A1 (en) * 1977-12-22 1979-07-20 Thomson Csf CONICAL SCAN ANTENNA SYSTEM FOR TRACKING RADAR
FR2488058A1 (en) * 1980-07-29 1982-02-05 Thomson Csf RADIANT SOURCE COMPACT BI-BAND OPERATING IN THE FIELD OF HYPERFREQUENCIES
US4575726A (en) * 1982-08-16 1986-03-11 Rca Corporation Antenna construction including two superimposed polarized parabolic reflectors

Also Published As

Publication number Publication date
JP3208154B2 (en) 2001-09-10
ES2067178T3 (en) 1995-03-16
FR2664750B1 (en) 1993-01-29
DE69106443T2 (en) 1995-08-10
JPH04253404A (en) 1992-09-09
EP0466579A1 (en) 1992-01-15
DE69106443D1 (en) 1995-02-16
FR2664750A1 (en) 1992-01-17

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