EP0236160B1 - Small-size radar antenna - Google Patents

Small-size radar antenna Download PDF

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Publication number
EP0236160B1
EP0236160B1 EP87400131A EP87400131A EP0236160B1 EP 0236160 B1 EP0236160 B1 EP 0236160B1 EP 87400131 A EP87400131 A EP 87400131A EP 87400131 A EP87400131 A EP 87400131A EP 0236160 B1 EP0236160 B1 EP 0236160B1
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EP
European Patent Office
Prior art keywords
reflector
axis
source
longitudinal axis
antenna
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Expired - Lifetime
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EP87400131A
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German (de)
French (fr)
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EP0236160A1 (en
Inventor
Bernard Estang
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Thales SA
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Thomson CSF SA
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    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q3/00—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
    • H01Q3/12—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system using mechanical relative movement between primary active elements and secondary devices of antennas or antenna systems
    • H01Q3/16—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system using mechanical relative movement between primary active elements and secondary devices of antennas or antenna systems for varying relative position of primary active element and a reflecting device
    • H01Q3/18—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system using mechanical relative movement between primary active elements and secondary devices of antennas or antenna systems for varying relative position of primary active element and a reflecting device wherein the primary active element is movable and the reflecting device is fixed

Definitions

  • the invention relates to airborne and onboard radar antennas, for monitoring and for air-surface firing control, placed in a radome.
  • Maritime surveillance radars and air-sea missile fire control radars have their antenna installed in a radome, located under the fuselage of the aircraft when it is airborne. This arrangement allows 360 ° surveillance. For reasons of cost and simplicity of aircraft and in particular aircraft, it is desirable that the radome is not retractable but installed at a fixed position under the fuselage.
  • the dimensions of the radome are defined by the additional allowable aerodynamic drag caused by the radome and by the space available between the lower part of the fuselage and the ground, during landing. Once these dimensions are fixed, the radome, and therefore the radar, must have the largest antenna possible in the available volume of the radome.
  • a surveillance radar makes a predetermined movement from its line of sight, which is the straight line joining the center of the antenna to the target. Two axes of articulation are then sufficient in the mechanical orientation of the antenna.
  • a fire control radar permanently measures the angular difference between the target and the missile in a horizontal plane.
  • the measurement must be independent of aircraft movements, and therefore the antenna must be stabilized along three axes.
  • a third mechanical axis is then necessary in order to be able to maintain the line of sight oriented on the missile whatever the movements of the aircraft.
  • the antenna in order to allow, after firing, the aircraft to make an evasive curve while continuing the guidance of the missile, the antenna must be stabilized in roll in order to keep the plane horizontal measurement.
  • a vertical axis allows a rotational movement to perform the 360 ° exploration and to counteract the yaw movements of the aircraft.
  • a rotation around the horizontal transverse axis makes it possible to compensate for the pitching movements.
  • a rotational movement around a longitudinal horizontal axis makes it possible to compensate for a rolling movement of the aircraft.
  • the reflector having a transversely elongated shape
  • the beam emitted by the antenna offers a higher resolution along the Y axis than along the Z axis. This is why, when 'a movement of the plane, it is essential to keep horizontal the direction in which the measurement provides maximum resolution by, for example, rotating the reflector.
  • Radar antennas already existing include a parabolic reflector and a monopulse energy source, better known by the Anglo-Saxon name "rear feed".
  • the source is the main active element, the parabolic element acting only as a reflector, both for transmission and for reception.
  • the source is fixed relative to the reflector.
  • the latter undergoes the movement of rotation around the transverse axis and the movement of rotation around the longitudinal axis.
  • the shape of the reflector looks like a strip cut from a paraboloid of revolution and placed vertically in the radome.
  • the last rotational movement around the longitudinal axis means that there must be a large space for the reflector to perform this third movement.
  • the size of the radome is determined, the size of the reflector is considerably reduced, and consequently the detection range of the radar is also reduced.
  • the object of the invention is to remedy this drawback by constructing an antenna of sufficient cross section and making it possible to carry out fire control, while keeping a small footprint.
  • An object of the invention is a radar antenna, more particularly intended to be installed in a radome on board an aircraft, and used for surveillance, tracking or fire control, comprising a transmitting source, a parabolic reflector of revolution around an axis passing through said source to form a beam of rays, means for orienting said beam along a first longitudinal axis called the roll axis and means for orienting along a second transverse axis called the pitch axis, l 'set being rotated about a third vertical axis called yaw axis.
  • the antenna is characterized in that the orientation means along the first longitudinal axis are constituted by means for rotating said source around the longitudinal axis.
  • the reflector remains fixed in roll with respect to the aircraft.
  • FIG 1 there is shown in perspective an antenna as it exists in the prior art.
  • the energy necessary for the emitting source is brought via a conduit 1, for example a waveguide, to a diffusion element 2 called in the following description: the source.
  • This assembly is integral with a reflector 4.
  • This reflector is a parabolic surface of revolution around a first axis R passing through the source which is placed at the focal point of the parabola. This axis represents the orientation of the aircraft, and is parallel to the longitudinal axis of the aircraft.
  • the reflector is placed behind the source.
  • the reflector and the source can pivot around a second axis Y also called transverse axis.
  • This rotation takes place with respect to an armature 5 which may consist of two arms 6 and 7 and which thus supports the source-reflector assembly.
  • This set is pivotally mounted around a third axis X perpendicular to the transverse axis Y, parallel to the axis A and which is called the longitudinal axis.
  • This new assembly is itself pivotally mounted around a fourth axis Z which is vertical. This last rotation is made relative to the aircraft.
  • the assembly consisting of the source 2 and the reflector 4 can therefore, as can be seen in FIG. 1, perform a complete rotation around the vertical axis Z in order to ensure a 360 ° exploration necessary for the monitoring function of the radar. It also allows yaw movements.
  • the rotation around the transverse axis Y is mechanically limited by the aircraft, and on the other hand by the bottom wall 9 of the radome 8 inside which the antenna is installed. This rotation compensates for pitching movements.
  • the rotation around the longitudinal axis X makes it possible to compensate for the roll movements of the aircraft, in particular while the latter is making turns such as the necessary evasive curves after a shot.
  • the rotation of the reflector 4 around the longitudinal axis X can only take place insofar as the shape of the reflector, once rotated with the armature 5, describes a space contained inside the radome 8
  • the height H delimiting the permitted height of the radome is imposed by the lower part of the fuselage and the ground during the landing. The shape of the reflector is therefore limited by this rotation around the longitudinal axis X.
  • FIG 2 there is shown simultaneously, and from the front, two different surfaces 14 and 15.
  • the first 14, symbolizes the surface of the reflector 4 according to the prior art.
  • the shape drawn is substantially that of a square.
  • two surfaces 18 are shown which are identical to the surface 14 and symbolize the size of the reflector 4 when it rotates around the longitudinal axis X.
  • the height H being imposed, it is easily understood that the shape of the reflector l 'is also.
  • the second surface 15 symbolizes the surface of the reflector 12 according to the invention. This almost completely fills the cross section of radome 8.
  • the antenna according to the invention is designed in the context of equipment with great performances.
  • the area of the reflector must be larger.
  • this reflector 12 also has a parabolic shape of revolution around the longitudinal axis X, coincident with the axis R of FIG. 1, but extends over almost the entire cross section of the radome.
  • This FIG. 3 also shows the trace 16 on the reflector 12 of the beam emitted by the source 2. Since the reflector has a transversely elongated shape, the beam emitted by the antenna has a very elongated shape vertically, and could be compared to a knife blade placed vertically.
  • the guide 1 is mounted integral with the source 2 rotating inside ball bearings 20. This rotation is obtained using a servo motor 21.
  • the reflector 12 remaining fixed and being a surface of revolution, when the source rotates around the X axis, making the beam pivot on itself with respect to the reflector, one obtains a rotation of the emission diagram of the antenna analogous to the rotation obtained in the prior art, when the source-reflector assembly rotated.
  • the invention makes it possible for a radome of determined size to obtain the largest possible antenna by replacing the roll stabilization of a large element which is the reflector, by the roll stabilization of an element much smaller than is the source.
  • the size of the servomotors and stabilization circuits is reduced, the power consumption is lower and the mass also lower.
  • the increase in the size of the reflector makes it possible to directly increase the detection range of the radar in a proportional manner.
  • the elimination of the rolling movement of the reflector makes it possible to reduce the useful height of the radome under the aircraft, and therefore to increase the ground clearance at the time of landing. For a determined detection range, the antenna is therefore compact.
  • the energy balance of the radar can be satisfied with a smaller antenna surface.
  • the rotation of the source can be brought to roll values which could not be obtained by rotation of the source-reflector assembly of the prior art. This allows the aircraft to take a much tighter turn.
  • the illumination of the source 2 in normal position forms on the reflector 12 an ellipse 16 having the width of the reflector for its major axis, and the height of the reflector for its minor axis.
  • the ellipse rotates around the same axis X while continuing to illuminate the reflector according to a trace 17.
  • the reflector is a paraboloid of revolution, the shape, and the characteristics of the beam, that is to say the antenna pattern, do not deform, and rotate around the same X axis, as if the reflector-source assembly rotated.
  • the lighting is partially outside the reflector.
  • the antenna gain is then decreases.
  • the fire control which requires roll rotation, being at close range, the reduced energy balance therefore allows a smaller antenna surface.
  • surveillance mode the search for a distant target requires the largest possible surface. This is then possible since in this mode, the rotation in roll of the source is not necessary and the reflector is fully lit.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Astronomy & Astrophysics (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • General Physics & Mathematics (AREA)
  • Remote Sensing (AREA)
  • Radar Systems Or Details Thereof (AREA)
  • Variable-Direction Aerials And Aerial Arrays (AREA)
  • Details Of Aerials (AREA)
  • Aerials With Secondary Devices (AREA)

Description

L'invention concerne les antennes radar aéroportées et embarquées, de veille et de conduite de tir air-surface, placées dans un radome.The invention relates to airborne and onboard radar antennas, for monitoring and for air-surface firing control, placed in a radome.

Les radars de surveillance maritimes et de conduite de tir de missiles air-mer, ont leur antenne installée dans un radome, situé sous le fuselage de l'aéronef lorsqu'il est aéroporté. Cette disposition permet une surveillance de 360°. Pours des raisons de coût et de simplicité des aéronefs et en particulier des avions, il est souhaitable que le radome ne soit pas rétractable mais installé à un poste fixe sous le fuselage.Maritime surveillance radars and air-sea missile fire control radars have their antenna installed in a radome, located under the fuselage of the aircraft when it is airborne. This arrangement allows 360 ° surveillance. For reasons of cost and simplicity of aircraft and in particular aircraft, it is desirable that the radome is not retractable but installed at a fixed position under the fuselage.

Dans ces conditions, les dimensions du radome sont définies par le supplément de traînée aérodynamique admissible provoqué par le radome et par l'espace disponible entre la partie inférieure du fuselage et le sol, lors de l'atterissage. Une fois ces dimensions fixées, le radome, et par conséquent le radar, doit posséder la plus grande antenne possible dans le volume disponible du radome.Under these conditions, the dimensions of the radome are defined by the additional allowable aerodynamic drag caused by the radome and by the space available between the lower part of the fuselage and the ground, during landing. Once these dimensions are fixed, the radome, and therefore the radar, must have the largest antenna possible in the available volume of the radome.

Un radar de surveillance effectue un mouvement prédéterminé de sa ligne de visée, qui est la droite joignant le centre de l'antenne à la cible. Deux axes d'articulation sont alors suffisants dans la mécanique d'orientation de l'antenne.A surveillance radar makes a predetermined movement from its line of sight, which is the straight line joining the center of the antenna to the target. Two axes of articulation are then sufficient in the mechanical orientation of the antenna.

Par contre, un radar de conduite de tir mesure en permanence dans un plan horizontal l'écart angulaire entre la cible et le missile. La mesure doit être indépendante des mouvements de l'avion, et par conséquent, l'antenne doit être stabilisée suivant trois axes. Un troisième axe mécanique est alors nécessaire pour pouvoir maintenir la ligne de visée orientée sur le missile quels que soient les mouvements de l'aéronef. En effet, afin de permettre, après le tir, à l'aéronef de faire une courbe évasive en continuant le guidage du missile, l'antenne doit être stabilisée en roulis afin de garder le plan de mesure horizontal. Pour résumer, un axe vertical permet un mouvement de rotation pour effectuer l'exploration de 360° et pour contrecarrer les mouvements de lacet de l'aéronef. Une rotation autour de l'axe horizontal transversal permet de compenser les mouvements de tangage. De même, un mouvement de rotation autour d'un axe horizontal longitudinal permet la compensation d'un mouvement de roulis de l'aéronef.On the other hand, a fire control radar permanently measures the angular difference between the target and the missile in a horizontal plane. The measurement must be independent of aircraft movements, and therefore the antenna must be stabilized along three axes. A third mechanical axis is then necessary in order to be able to maintain the line of sight oriented on the missile whatever the movements of the aircraft. Indeed, in order to allow, after firing, the aircraft to make an evasive curve while continuing the guidance of the missile, the antenna must be stabilized in roll in order to keep the plane horizontal measurement. To summarize, a vertical axis allows a rotational movement to perform the 360 ° exploration and to counteract the yaw movements of the aircraft. A rotation around the horizontal transverse axis makes it possible to compensate for the pitching movements. Likewise, a rotational movement around a longitudinal horizontal axis makes it possible to compensate for a rolling movement of the aircraft.

D'autre part, en référence à la figure 1, le réflecteur ayant une forme allongée transversalement, le faisceau émis par l'antenne offre une résolution supérieure suivant l'axe Y que suivant l'axe Z. C'est pourquoi, lors d'un mouvement de l'avion, il est indispensable de garder horizontale la direction suivant laquelle la mesure apporte une résolution maximale en faisant, par exemple, tourner le réflecteur.On the other hand, with reference to FIG. 1, the reflector having a transversely elongated shape, the beam emitted by the antenna offers a higher resolution along the Y axis than along the Z axis. This is why, when 'a movement of the plane, it is essential to keep horizontal the direction in which the measurement provides maximum resolution by, for example, rotating the reflector.

Les antennes de radar existant déjà comprennent un réflecteur parabolique et une source d'énergie monopulse, plus connue sous l'appellation anglo-saxonne "rear feed". Dans un tel système la source est l'élément actif principal, l'élément parabolique n'agissant que comme réflecteur, tant pour l'émission que pour la réception. La source est fixe par rapport au réflecteur. Par contre, ce dernier subit le mouvement de rotation autour de l'axe transversal et le mouvement de rotation autour de l'axe longitudinal. En général, la forme du réflecteur s'apparente à une bande découpée dans un paraboloïde de révolution et placée verticalement dans le radome. Le dernier mouvement de rotation autour de l'axe longitudinal fait que l'on doit ménager un espace important pour que le réflecteur puisse effectuer ce troisième mouvement. L'encombrement du radome étant déterminé, la taille du réflecteur est considérablement réduite, et par conséquence la portée de détection du radar l'est également.Radar antennas already existing include a parabolic reflector and a monopulse energy source, better known by the Anglo-Saxon name "rear feed". In such a system, the source is the main active element, the parabolic element acting only as a reflector, both for transmission and for reception. The source is fixed relative to the reflector. On the other hand, the latter undergoes the movement of rotation around the transverse axis and the movement of rotation around the longitudinal axis. In general, the shape of the reflector looks like a strip cut from a paraboloid of revolution and placed vertically in the radome. The last rotational movement around the longitudinal axis means that there must be a large space for the reflector to perform this third movement. As the size of the radome is determined, the size of the reflector is considerably reduced, and consequently the detection range of the radar is also reduced.

Autrement dit, pour un avion de patrouille maritime ou terrestre avec un radome ventral de dimension déterminée, la nécessité, en mode de conduite de tir, de stabiliser l'antenne en direction de la cible, dans l'espace du radome, réduit considérablement la taille de l'antenne du fait du mouvement de rotation autour de l'axe longitudinal.In other words, for a maritime or land patrol aircraft with a ventral radome of determined size, the need, in fire control mode, to stabilize the antenna direction of the target, in the space of the radome, considerably reduces the size of the antenna due to the rotational movement around the longitudinal axis.

Le but de l'invention est de remédier à cet inconvénient en construisant une antenne d'une section transversale suffisante et permettant d'effectuer de la conduite de tir, tout en gardant un faible encombrement.The object of the invention is to remedy this drawback by constructing an antenna of sufficient cross section and making it possible to carry out fire control, while keeping a small footprint.

Un objet de l'invention est une antenne radar, plus particulièrement destinée à être installée dans un radome à bord d'un aéronef, et utilisée pour la surveillance, la poursuite ou la conduite de tir, comprenant une source émettrice, un réflecteur parabolique de révolution autour d'un axe passant par ladite source pour former un faisceau de rayons, des moyens d'orientation dudit faisceau selon un premier axe longitudinal appelé axe de roulis et des moyens d'orientation selon un deuxième axe transversal appelé axe de tangage, l'ensemble étant mis en rotation autour d'un troisième axe vertical appelé axe de lacet. L'antenne est caractérisée en ce que les moyens d'orientation selon le premier axe longitudinal sont constitués par des moyens de mise en rotation de ladite source autour de l'axe longitudinal. Le réflecteur reste fixe en roulis par rapport à l'aéronef.An object of the invention is a radar antenna, more particularly intended to be installed in a radome on board an aircraft, and used for surveillance, tracking or fire control, comprising a transmitting source, a parabolic reflector of revolution around an axis passing through said source to form a beam of rays, means for orienting said beam along a first longitudinal axis called the roll axis and means for orienting along a second transverse axis called the pitch axis, l 'set being rotated about a third vertical axis called yaw axis. The antenna is characterized in that the orientation means along the first longitudinal axis are constituted by means for rotating said source around the longitudinal axis. The reflector remains fixed in roll with respect to the aircraft.

L'invention et ses caractéristiques seront mieux comprises à la lecture de la description qui suit et qui est annexée des figures suivantes :

  • Fig.1, une vue représentant une antenne selon l'art antérieur ;
  • Fig.2, un schéma du problème résolu par l'invention ;
  • Fig.3, une vue d'une antenne selon l'invention ;
  • Fig.4, une vue en coupe d'une partie de l'antenne selon l'invention.
The invention and its characteristics will be better understood on reading the description which follows and which is annexed to the following figures:
  • Fig.1, a view showing an antenna according to the prior art;
  • Fig.2, a diagram of the problem solved by the invention;
  • Fig.3, a view of an antenna according to the invention;
  • Fig.4, a sectional view of part of the antenna according to the invention.

Sur la figure 1, on a représenté en perspective une antenne telle qu'elle existe dans l'art antérieur. L'énergie nécessaire à la source émettrice est amenée par l'intermédiaire d'un conduit 1, par exemple un guide d'ondes, jusqu'à un élément de diffusion 2 appelé dans la suite de la description : la source. Cet ensemble est solidaire d'un réflecteur 4. Ce réflecteur est une surface parabolique de révolution autour d'un premier axe R passant par la source qui est placée au foyer de la parabole. Cet axe représente l'orientation de l'aéronef, et est parallèle à l'axe longitudinal de l'aéronef. Le réflecteur est placé derrière la source. Le réflecteur et la source peuvent pivoter autour d'un deuxième axe Y appelé également axe transversal. Cette rotation s'effectue par rapport à une armature 5 qui peut être constituée de deux bras 6 et 7 et qui supporte ainsi l'ensemble source-réflecteur. Cet ensemble est monté pivotant autour d'un troisième axe X perpendiculaire à l'axe transversal Y, parallèle à l'axe A et qui est appelé axe longitudinal. Ce nouvel ensemble est lui-même monté pivotant autour d'un quatrième axe Z qui est vertical. Cette dernière rotation se fait par rapport à l'aéronef.In Figure 1, there is shown in perspective an antenna as it exists in the prior art. The energy necessary for the emitting source is brought via a conduit 1, for example a waveguide, to a diffusion element 2 called in the following description: the source. This assembly is integral with a reflector 4. This reflector is a parabolic surface of revolution around a first axis R passing through the source which is placed at the focal point of the parabola. This axis represents the orientation of the aircraft, and is parallel to the longitudinal axis of the aircraft. The reflector is placed behind the source. The reflector and the source can pivot around a second axis Y also called transverse axis. This rotation takes place with respect to an armature 5 which may consist of two arms 6 and 7 and which thus supports the source-reflector assembly. This set is pivotally mounted around a third axis X perpendicular to the transverse axis Y, parallel to the axis A and which is called the longitudinal axis. This new assembly is itself pivotally mounted around a fourth axis Z which is vertical. This last rotation is made relative to the aircraft.

L'ensemble constitué de la source 2 et du réflecteur 4 peut donc, comme on le voit sur la figure 1, effectuer une rotation complète autour del'axe vertical Z afin d'assurer une exploration de 360° nécessaire à la fonction de surveillance du radar. Elle permet également d'effectuer des mouvements de lacet. La rotation autour de l'axe transversal Y est limitée mécaniquement par l'aéronef, et d'autre part par la paroi inférieure 9 du radome 8 à l'intérieur duquel est installée l'antenne. Cette rotation permet de compenser les mouvements de tangage. Enfin, la rotation autour de l'axe longitudinal X permet de compenser les mouvements de roulis de l'aéronef, notamment pendant que celui-ci effectue des virages tels que les courbes évasives nécessaires après un tir.The assembly consisting of the source 2 and the reflector 4 can therefore, as can be seen in FIG. 1, perform a complete rotation around the vertical axis Z in order to ensure a 360 ° exploration necessary for the monitoring function of the radar. It also allows yaw movements. The rotation around the transverse axis Y is mechanically limited by the aircraft, and on the other hand by the bottom wall 9 of the radome 8 inside which the antenna is installed. This rotation compensates for pitching movements. Finally, the rotation around the longitudinal axis X makes it possible to compensate for the roll movements of the aircraft, in particular while the latter is making turns such as the necessary evasive curves after a shot.

La rotation du réflecteur 4 autour de l'axe longitudinal X ne peut s'effectuer que dans la mesure où, la forme du réflecteur, une fois mis en rotation avec l'armature 5, décrit un espace contenu à l'intérieur du radome 8. La hauteur H délimitant la hauteur permise du radome est imposée par la partie inférieure du fuselage et le sol lors de l'atterrissage. La forme du réflecteur est donc limitée par cette rotation autour de l'axe longitudinal X.The rotation of the reflector 4 around the longitudinal axis X can only take place insofar as the shape of the reflector, once rotated with the armature 5, describes a space contained inside the radome 8 The height H delimiting the permitted height of the radome is imposed by the lower part of the fuselage and the ground during the landing. The shape of the reflector is therefore limited by this rotation around the longitudinal axis X.

Sur la figure 2, on a représenté simultanément, et de face, deux surfaces différentes 14 et 15. La première 14, symbolise la surface du réflecteur 4 selon l'art antérieur. La forme dessinée est sensiblement celle d'un carré. En traits interrompus, ont été représentées deux surfaces 18 identiques à la surface 14 et symbolisant l'encombrement du réflecteur 4 lorsqu'il tourne autour de l'axe longitudinal X. La hauteur H étant imposée, on comprend aisément que la forme du réflecteur l'est également. La deuxième surface 15 symbolise la surface du réflecteur 12 selon l'invention. Celle-ci remplit presque complètement la section transversale du radome 8.In Figure 2, there is shown simultaneously, and from the front, two different surfaces 14 and 15. The first 14, symbolizes the surface of the reflector 4 according to the prior art. The shape drawn is substantially that of a square. In dashed lines, two surfaces 18 are shown which are identical to the surface 14 and symbolize the size of the reflector 4 when it rotates around the longitudinal axis X. The height H being imposed, it is easily understood that the shape of the reflector l 'is also. The second surface 15 symbolizes the surface of the reflector 12 according to the invention. This almost completely fills the cross section of radome 8.

L'antenne selon l'invention est conçue dans le cadre de matériels à grandes performances. La surface du réflecteur doit être plus importante. Etant donné l'encombrement imposé du radome 8, selon l'invention, on propose d'utiliser un réflecteur dont la surface, plus importante vue de face, remplit en grande partie la section du radome, comme représenté sur la figure 2 où cette surface est repérée 12.The antenna according to the invention is designed in the context of equipment with great performances. The area of the reflector must be larger. Given the space requirement of radome 8, according to the invention, it is proposed to use a reflector whose surface, larger seen from the front, largely fills the section of the radome, as shown in FIG. 2 where this surface is marked 12.

En référence à la figure 3, ce réflecteur 12 a également une forme parabolique de révolution autour de l'axe longitudinal X, confondu avec l'axe R de la figure 1, mais s'étend sur presque toute la section transversale du radome. Sur cette figure 3, on a également représenté la trace 16 sur le réflecteur 12 du faisceau émis par la source 2. Etant donné que le réflecteur a une forme allongée transversalement, le faisceau émis par l'antenne a une forme très allongée verticalement, et pourrait être assimilé à une lame de couteau placée verticalement.With reference to FIG. 3, this reflector 12 also has a parabolic shape of revolution around the longitudinal axis X, coincident with the axis R of FIG. 1, but extends over almost the entire cross section of the radome. This FIG. 3 also shows the trace 16 on the reflector 12 of the beam emitted by the source 2. Since the reflector has a transversely elongated shape, the beam emitted by the antenna has a very elongated shape vertically, and could be compared to a knife blade placed vertically.

Selon l'invention, pour réaliser le mouvement de rotation du faisceau autour de l'axe longitudinal X, on prévoit de faire tourner la source émettrice 2, c'est-à-dire l'éclairement du réflecteur symbolisé par la trace 16. Le faisceau émis par l'antenne pourra donc rester vertical en permanence, même si l'aéronef effectue un virage, et plus particulièrement, une évasive après le tir. Cette rotation autour de l'axe longitudinal X est obtenue par un dispositif représenté succinctement sur la figure 4. Sur la figure 3 n'apparaît qu'un boîtier 3 placé derrière le réflecteur 12, et monté pivotant autour de l'axe transversal Y par rapport à l'armature 5. L'ensemble est monté pivotant autour de l'axe vertical Z, par rapport à l'aéronef représenté par la pièce 10. Des systèmes à motoréducteurs 11 et 13 assurent la mise en rotation autour des axes verticaux X et transversaux Y.According to the invention, in order to carry out the rotation movement of the beam around the longitudinal axis X, provision is made to rotate the emitting source 2, that is to say the illumination of the reflector symbolized by the trace 16. The the beam emitted by the antenna can therefore remain vertical at all times, even if the aircraft makes a turn, and more particularly, an evasive action after firing. This rotation around the longitudinal axis X is obtained by a device succinctly shown in Figure 4. In Figure 3 appears only a housing 3 placed behind the reflector 12, and pivotally mounted about the transverse axis Y by relative to the frame 5. The assembly is pivotally mounted about the vertical axis Z, relative to the aircraft represented by the part 10. Geared motor systems 11 and 13 ensure the rotation around the vertical axes X and transverse Y.

Sur la figure 4, à l'intérieur du boîtier 3, on a monté le guide 1 solidaire de la source 2 tournant à l'intérieur de paliers à billes 20. Cette rotation est obtenue à l'aide d'un moteur asservi 21. Le réflecteur 12 restant fixe et étant une surface de révolution, lorsque la source tourne autour de l'axe X, faisant pivoter le faisceau sur lui-même par rapport au réflecteur, on obtient une rotation du diagramme d'émission de l'antenne analogue à la rotation obtenue dans l'art antérieur, lorsque l'ensemble source-réflecteur tournait.In FIG. 4, inside the box 3, the guide 1 is mounted integral with the source 2 rotating inside ball bearings 20. This rotation is obtained using a servo motor 21. The reflector 12 remaining fixed and being a surface of revolution, when the source rotates around the X axis, making the beam pivot on itself with respect to the reflector, one obtains a rotation of the emission diagram of the antenna analogous to the rotation obtained in the prior art, when the source-reflector assembly rotated.

L'invention permet pour un radome de taille déterminée, d'obtenir la plus grande antenne possible en remplaçant la stabilisation roulis d'un élément de grande dimension qu'est le reflecteur, par la stabilisation en roulis d'un élément beaucoup plus petit qu'est la source. La taille des servomoteurs et des circuits de stabilisation est réduite, la consommation électrique est plus faible et la masse également plus faible. L'augmentation de la taille du réflecteur permet d'accroître de façon directement proportionnelle la portée de détection du radar. La suppression du mouvement de roulis du réflecteur permet de réduire la hauteur utile du radome sous l'avion, et donc d'augmenter la garde au sol au moment de l'atterrissage. Pour une portée de détection déterminée, l'antenne est donc d'un faible encombrement.The invention makes it possible for a radome of determined size to obtain the largest possible antenna by replacing the roll stabilization of a large element which is the reflector, by the roll stabilization of an element much smaller than is the source. The size of the servomotors and stabilization circuits is reduced, the power consumption is lower and the mass also lower. The increase in the size of the reflector makes it possible to directly increase the detection range of the radar in a proportional manner. The elimination of the rolling movement of the reflector makes it possible to reduce the useful height of the radome under the aircraft, and therefore to increase the ground clearance at the time of landing. For a determined detection range, the antenna is therefore compact.

En mode de conduite de tir, le bilan énergétique du radar peut se contenter d'une surface antenne plus faible. La rotation de la source peut être portée à des valeurs de roulis qui ne pouvaient être obtenues par rotation de l'ensemble source-réflecteurde l'art antérieur. Ceci permet à l'aéronef de prendre un virage beaucoup plus serré.In fire control mode, the energy balance of the radar can be satisfied with a smaller antenna surface. The rotation of the source can be brought to roll values which could not be obtained by rotation of the source-reflector assembly of the prior art. This allows the aircraft to take a much tighter turn.

En référence à la figure 3, l'éclairement de la source 2 en position normale forme sur le réflecteur 12 une ellipse 16 ayant pour grand axe la largeur du réflecteur, et pour petit axe la hauteur du réflecteur. Lorsque la source tourne autour de l'axe longitudinal X, d'un angle A pour des raisons de stabilisation en roulis, l'ellipse tourne autour du même axe X en continuant à éclairer le réflecteur selon une trace 17. Comme le réflecteur est un paraboloïde de révolution, la forme, et les caractéristiques du faisceau, c'est-à-dire le diagramme d'antenne, ne se déforment pas, et pivotent autour du même axe X, comme si l'ensemble réflecteur-source pivotait.With reference to FIG. 3, the illumination of the source 2 in normal position forms on the reflector 12 an ellipse 16 having the width of the reflector for its major axis, and the height of the reflector for its minor axis. When the source rotates around the longitudinal axis X, by an angle A for reasons of stabilization in roll, the ellipse rotates around the same axis X while continuing to illuminate the reflector according to a trace 17. As the reflector is a paraboloid of revolution, the shape, and the characteristics of the beam, that is to say the antenna pattern, do not deform, and rotate around the same X axis, as if the reflector-source assembly rotated.

Au-delà d'une certaine valeur de roulis, l'éclairement se fait partiellement en dehors du réflecteur. Le gain d'antenne est alors diminué. La conduite de tir, qui impose la rotation en roulis, se faisant à distance proche, le bilan énergétique plus réduit autorise donc une surface d'antenne plus faible. Par contre, en mode se surveillance, la recherche de cible lointaine exige la plus grande surface possible. Ceci est alors possible puisque dans ce mode, la rotation en roulis de la source n'est pas nécessaire et le réflecteur est éclairé dans sa totalité.Above a certain roll value, the lighting is partially outside the reflector. The antenna gain is then decreases. The fire control, which requires roll rotation, being at close range, the reduced energy balance therefore allows a smaller antenna surface. On the other hand, in surveillance mode, the search for a distant target requires the largest possible surface. This is then possible since in this mode, the rotation in roll of the source is not necessary and the reflector is fully lit.

Les avantages obtenus avec l'antenne selon l'invention sont considérables lorsque celle-ci est utilisée à bord d'un aéronef. On envisage, en outre, de l'utiliser sur les bateaux.The advantages obtained with the antenna according to the invention are considerable when it is used on board an aircraft. There are also plans to use it on boats.

Claims (5)

  1. A radar antenna used for monitoring, tracking or missile-guiding, comprising an emitter source (2), a parabolic reflector (12), symmetrical about a first longitudinal axis (X) and having a substantially elliptical shape, said axis passing through said source, in order to create a radiation beam, means for directing said beam along said first longitudinal axis called rolling axis, and means for directing said beam according to a second transversal axis (Y) called pitching axis, the unit being rotated about a third vertical axis (Z) called mast axis, characterized in that the source illuminates said reflector according to a diagram of substantially elliptical shape identical to the shape of the reflector and that the means for directing the source according to the first axis (X) are constituted by means allowing to rotate said source about said first axis (X) with respect to the reflector.
  2. A radar antenna according to claim 1, characterized in that the reflector (12) is stationary about the longitudinal axis (X).
  3. A radar antenna according to claim 1 or 2, characterized in that it is used in a radom (8) aboard an aircraft.
  4. An antenna according to claim 2, characterized in that the surface of the reflector (12) is close to the section of the radom (8).
  5. An antenna according to any one of the preceding claims, characterized in that the energy of the source (2) is conveyed through a duct (1) passing through the reflector, the means for rotating the source about the longitudinal axis (X) being constituted by a servomotor (21) which rotates the unit constituted by the duct and the source inside ball bearings (20), the motor being placed in a casing (3) integral with the reflector and placed behind the latter, the unit being mounted pivotably about the second transversal axis due to the means for directing the source according to the transversal axis.
EP87400131A 1986-01-28 1987-01-20 Small-size radar antenna Expired - Lifetime EP0236160B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8601173A FR2593646B1 (en) 1986-01-28 1986-01-28 LOW-DIMENSIONAL RADAR ANTENNA.
FR8601173 1986-01-28

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EP0236160A1 EP0236160A1 (en) 1987-09-09
EP0236160B1 true EP0236160B1 (en) 1991-09-11

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EP87400131A Expired - Lifetime EP0236160B1 (en) 1986-01-28 1987-01-20 Small-size radar antenna

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US (1) US4933681A (en)
EP (1) EP0236160B1 (en)
DE (1) DE3772797D1 (en)
FR (1) FR2593646B1 (en)

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Also Published As

Publication number Publication date
FR2593646B1 (en) 1988-07-29
EP0236160A1 (en) 1987-09-09
DE3772797D1 (en) 1991-10-17
US4933681A (en) 1990-06-12
FR2593646A1 (en) 1987-07-31

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