EP0415804A1 - Dismountable and air-transportable antenna for satellite communications - Google Patents

Abstract

The antenna preferably of the offset type comprises several thin and separable parabolic elements (111 to 118) which are joined in a parabolic reflector (1), and several substantially rectangular separable panels (211 to 2114) which are assembled in a frame (2 ) with a prismatic mesh to support the reflector. The panels are substantially perpendicular to the lower base of the trellis and have curvilinear upper edges shaped by overmolding according to the parabolic reflector (1) and separable from the reflector elements (111 to 118). The antenna also includes a telescopic lifting mast (5) and a circular azimuth positioner (6), both articulated to the chassis and removable. The dismantled antenna is transportable in the form of standard packages in the hold of a main line aircraft.

Description

The present invention relates to a transportable antenna for a telecommunications earth mobile station, making it possible to transmit and receive in particular images, sound and data with a telecommunications satellite. In particular, it is used for distant reports in order to retransmit television images and to exchange telephone communications with a television authority in mainland France.

Currently, known mobile antennas, taking into account their shape and their ground seating equipment, never weigh less than two tonnes and cannot be dismantled under conditions satisfying rapid transport, by aircraft to the intervention site. under economically reasonable conditions. It is the same, moreover, for the electronic equipment associated with the antenna, which is confined in a technical protection shelter, called a shelter, of large size whose size and weight are penalizing.

In addition, the weight and size of the equipment and the antenna contributed, by their cost, to prevent any realization of reports of images and sounds at long distance. The users of such antennas, at the forefront of which television channels and private customers, have always considered it impossible to produce such reports.

It should be emphasized that the main disadvantage of these known antennas lies in the fact that they are not removable in relatively small parts allowing their grouping in packages easily transportable in the holds of mainline aircraft. Indeed, the reflector and the frame, of the irregular lattice type of tubes, are not completely separable from each other. The reflector-chassis assembly can be dismantled into a few reflector-chassis parts of which these shapes are diverse and non-standard and which are very bulky. These parts have dimensions exceeding the maximum length, width and height of 3.07 m, 1.8 m and 1.6 m required for packages introduced into mainline aircraft holds. Under these conditions, these known antennas can be air-transported by so-called cargo planes which are specially chartered and whose schedules are completely irregular. This results in a downtime of the equipment and the antenna much longer than the time necessary to transport the reporting team separate from that of the antenna and to complete the reporting. In some cases, the equipment and the antenna cannot even be transported by plane or small helicopter to the precise site where the live reporting takes place.

Furthermore, the existing and dismountable antennas, already too heavy, have a relatively small diameter and therefore insufficient radio performance. The microwave source of the antenna must therefore offer very high power on transmission in order to achieve the quality objectives required for the retransmission of the report. This high power in turn impedes the transportability of the equipment and the antenna and the cost of routing and human service, insofar as the microwave source must be more powerful and therefore the electronic equipment must be heavier. In particular, the equipment requires a very high power supply, increasing the size and weight of the assembly.

The present invention therefore aims to achieve a light antenna, easily removable in various parts of small footprint, and therefore easily air transportable while using a relatively low power supply, to allow rapid reporting anywhere in the world and to retransmit television images in particular to a geostationary satellite.

In particular, the antenna according to the invention can be transported in the hold of a mainline plane at the same time as the reporting team itself.

To this end, an antenna, in particular for bidirectional telecommunications with a satellite, is as defined in claim 1.

The reflector elements and the chassis panels are each inscribed in a predetermined rectangle, preferably approximately 3 mx 1.5 m, and are each of a sandwich structure, composed of a core of synthetic material, or of a honeycomb. bee or light wood, and carbon faces. The areal mass of the reflector elements and of the chassis panels can be less than approximately 11 kg / m², and preferably of the order of 5 kg / m². These dimensional and structural characteristics make it possible to transport the antenna according to the invention in a mainline aircraft hold. The transport cost is reduced, taking into account the low weight of the antenna which overall, including with its accessories such as source carrying mast, lifting mast in elevation and positioner in azimuth, can be less than 400 kg.

The relatively large dimensions of the reflector according to the invention allow a microwave source of low power and a space-saving and light source of electrical energy.

According to a preferred embodiment, the antenna is of the offset type, and therefore offers a higher efficiency than the antennas with reflector with symmetry of revolution commonly used. The antenna comprises a source carrying mast, a lower part of which is fixed laterally to one of the side panels of the chassis and an upper part of which overhangs the reflector is arranged parallel and close to the focal axis of the reflector. This mast can pivot to lie on the antenna and access the source.

The antenna also includes removable and air-transportable means for orienting the reflector both in elevation and in azimuth. For the elevation orientation of the reflector, a removable, preferably telescopic, mast is provided, with one end resting on the ground, a slide sliding along the site mast and articulated to one of the side panels of the chassis, and means for raising the slide along the site mast. For the azimuthal orientation of the reflector are provided two rolling means mounted for rotation under one of the side panels of the chassis and a removable raceway for the rolling means.

The base of the antenna according to the invention is therefore completely different from those traditionally used, of the turret type for azimuth orientation and actuator levers mounted on the turret for orientation in elevation. In particular, the mast on site according to the invention allows the chassis supporting the reflector to be placed on the ground.

• - la Fig. 1 est une vue schématique de côté longitudinal d'un châssis et d'un réflecteur d'une antenne selon une première réalisation de l'invention, en position horizontale ;
• - la Fig. 2 est une vue de dessus schématique de l'antenne selon la Fig. 1 ;
• - la Fig. 3 est une vue de dessus schématique du réflecteur de l'antenne selon la Fig. 1 ;
• - la Fig. 4 est une vue de dessus schématique du châssis conformateur de l'antenne selon la Fig. 1 ;
• - la Fig. 5 est une vue horizontale en coupe prise le long de la ligne V-V de la Fig. 6 montrant une liaison centrale au châssis entre des panneaux internes ;
• - la Fig. 6 est une vue verticale en coupe prise le long de la ligne VI-VI de la Fig. 5 ;
• - les Figs. 7 et 8 sont des vues de dessus de deux liaisons entre panneaux du châssis au niveau d'une arête verticale du châssis, respectivement ;
• - la Fig. 9 est une vue de dessus d'une liaison entre le milieu d'un petit panneau latéral et d'un panneaux interne-axial du châssis ;
• - la Fig. 10 est une superposition des Figs. 3 et 4 ;
• - la Fig. 11 est une vue schématique en perspective du réflecteur sur un moule, et du châssis retourné et en cours de surmoulage, selon la première réalisation ;
• - les Figs. 12 et 13 sont des vues de dessus d'un réflecteur et d'un châssis conformateur selon une seconde réalisation de l'invention, respectivement ;
• - les Figs. 14 et 15 montrent respectivement des vues arrière et de côté longitudinal d'un mât porte-source selon une première réalisation, respectivement ;
• - les Figs. 16 et 17 montrent des vues arrière et de côté longitudinal d'un mât porte-source selon une seconde réalisation, respectivement ;
• - la Fig. 18 est une vue éclatée d'un mât de levée en site de l'antenne ;
• - la Fig. 19 montre schématiquement le mât de levée en site partiellement déployé ;
• - les Figs. 20 et 21 sont des vues de dessus et de face d'une chape d'articulation entre le mât de levée en site et un petit panneau latéral du châssis, respectivement ;
• - les Figs. 22 et 23 montrent schématiquement l'antenne selon la Fig. 1, avec un axe focal du réflecteur parallèle et perpendiculaire au sol, respectivement ;
• - la Fig. 24 est une vue schématique de dessus d'un positionneur en azimut de l'antenne ;
• - la Fig. 25 est une vue latérale d'une poutre de chemin de roulement pour patin-porteur de châssis, inclus dans le positionneur en azimut ;
• - les Figs. 26 et 27 sont des vues verticales et de dessus d'un vérin à vis pour mise à niveau du chemin de roulement, respectivement ;
• - la Fig. 28 est une vue de côté longitudinale d'une bascule pour supporter le chemin de roulement, selon une variante du positionneur en azimut ; et
• - les Figs. 29 et 30 sont des vues schématiques de côté longitudinal et de dessus de l'antenne selon la Fig. 1, munie d'un positionneur en azimut avec bascule selon la Fig. 28, respectivement

Other advantages and characteristics of the invention will appear more clearly on reading the description of several preferred embodiments of the invention with reference to the corresponding appended drawings in which:

• - Fig. 1 is a schematic longitudinal side view of a frame and a reflector of an antenna according to a first embodiment of the invention, in a horizontal position;
• - Fig. 2 is a schematic top view of the antenna according to FIG. 1;
• - Fig. 3 is a schematic top view of the antenna reflector according to FIG. 1;
• - Fig. 4 is a schematic top view of the shaping frame of the antenna according to FIG. 1;
• - Fig. 5 is a horizontal sectional view taken along the line VV of FIG. 6 showing a central connection to the chassis between internal panels;
• - Fig. 6 is a vertical sectional view taken along the line VI-VI of FIG. 5;
• - Figs. 7 and 8 are top views of two connections between chassis panels at a vertical edge of the chassis, respectively;
• - Fig. 9 is a top view of a connection between the middle of a small side panel and of an internal-axial panel of the chassis;
• - Fig. 10 is a superposition of Figs. 3 and 4;
• - Fig. 11 is a schematic perspective view of the reflector on a mold, and of the inverted chassis and during overmolding, according to the first embodiment;
• - Figs. 12 and 13 are top views of a reflector and a shaping frame according to a second embodiment of the invention, respectively;
• - Figs. 14 and 15 respectively show rear and longitudinal side views of a source mast in a first embodiment, respectively;
• - Figs. 16 and 17 show rear and longitudinal side views of a source holder mast according to a second embodiment, respectively;
• - Fig. 18 is an exploded view of a lifting mast in elevation of the antenna;
• - Fig. 19 schematically shows the lifting mast in partially deployed site;
• - Figs. 20 and 21 are top and front views of an articulation yoke between the elevating mast and a small side panel of the chassis, respectively;
• - Figs. 22 and 23 schematically show the antenna according to FIG. 1, with a focal axis of the reflector parallel and perpendicular to the ground, respectively;
• - Fig. 24 is a schematic top view of an azimuth positioner of the antenna;
• - Fig. 25 is a side view of a raceway beam for a chassis skid, included in the azimuth positioner;
• - Figs. 26 and 27 are vertical and top views of a screw jack for leveling the raceway, respectively;
• - Fig. 28 is a longitudinal side view of a rocker for supporting the raceway, according to a variant of the azimuth positioner; and
• - Figs. 29 and 30 are schematic views from the longitudinal side and from above of the antenna according to FIG. 1, provided with an azimuth positioner with rocker according to FIG. 28, respectively

In order to fix the ideas, certain components and dimensions of elements making up an antenna according to the invention are indicated by way of example in the detailed description below.

The antenna according to a preferred embodiment is intended to transmit to a geostationary satellite and to receive from this satellite telecommunications signals SHF in centimeter wave, and more particularly signals in C band, respectively between 3.1 and 4.2 GHz , and 5.925 and 6.425 GHz. Telecommunication signals can support both image, sound and computer data.

As shown schematically in Figs. 1 and 2, the transmitting and receiving antenna essentially comprises five removable assemblies, namely a parabolic reflector 1, a shaping frame 2, a carrier mast 3 of a microwave source 4, a lifting mast on site 5, and an azimuth positioner 6.

The antenna is of the off-center microwave source type, called an "offset antenna". The reflector 1 is a portion without symmetry of revolution and with a substantially elliptical outline of a paraboloid of revolution. The projection of the reflector on a focal plane perpendicular to the axis F′F of the paraboloid is a projection circle passing close to the focal point f of the paraboloid. An offset antenna has the advantage that the carrier mast 3 of the source 4 reduces the losses by mask effect and can comprise a single carrier branch which is aligned with the focal axis, which increases the efficiency of the antenna.

The antenna reflector 1 thus has a substantially elliptical contour with a very small eccentricity. As shown in top view in FIG. 3, X′X and Y′Y designate small and large axes of the elliptical contour in the opening plane of the reflector. The diameter of the projection circle is approximately 5.50 m, and the reflector 1 is seen from the focal point f where the microwave source 4 is located, at an apex angle of 2x40 ° = approximately 80 °. The width and length of the reflector along the axes X′X and Y′Y are of the order of 5.4 m and 5.9 m, which corresponds to an area of approximately 25 m².

The reflector 1 is removable in eight thin parabolic elements, called petals 11 pét to 11₁. The contours of the petals are delimited on the one hand by the minor axis X'X of the reflector and two segments parallel to the minor axis X′X and spaced from it by one quarter of the major axis Y′Y, and on the other hand by the major axis Y′Y itself. The continuity of the reflector surface is ensured by the edge-to-edge junctions of the petals 11ales to 11₁ along their edges parallel to the axes X′X and Y′Y. The petals, and therefore the reflector, are thin, that is to say they are of thin and uniform thickness which facilitates their stacking.

As shown in Fig. 3, the reflector is in fact composed of four almost identical central petals 11₁ to 11₄ shared by the axes X′X and Y′Y and four almost identical petals 11₅ to 11₈ located at the ends of the major axis Y′Y, this which not only facilitates the cost of building the reflector, but also stacking the petals when the reflector is removed. In addition, the pairs of petals 11₅ and 11₆, and 11₇ and 11₈ at the ends of the major axis Y′Y have trapezoidal overhangs 12₁ and 12₂ to form supports for the reflector on the chassis 2, as will be seen below. Each petal has an area of approximately 3 m².

Each of the petals 11₁ to 11₈ consists of a laminated curvilinear panel of the sandwich structure type. Each panel comprises a core which may be made of thermoformable synthetic material, such as polymethymethacrylate foam (PMMA), or of honeycomb, or of light wood such as balsa made waterproof by injection of resin. The foam can be reinforced with carbon fibers or glass fibers. The two sides of the core are covered by one or more layers of carbon fibers impregnated with epoxy resin which, thanks to its almost zero linear expansion, maintains an optimal constant geometry at the petal, whatever the climatic conditions which can vary from -70 ° C to + 70 ° C, or when the reflector is partly in the shade, partly in the sun. The concave face of each petal, constituting a reflecting portion of the antenna reflector, comprises a finely braided metal grid, of aluminum, which is glued to the carbon layers and protected by a Kevlar fabric itself covered with a layer of white paint. According to other embodiments, the metal grid and the layer of Kevlar are eliminated.

When the petals include a balsa core, the thickness of the petals is 14 mm and the reflector has a total mass of approximately 270 kg, or a surface mass of 10.8 kg / m². To obtain the same bending stiffness, the thickness of the petals is 22 mm when they are with a core of PMMA, and the mass of the reflector is much lower, of the order of 135 kg, or 5.4 kg / m².

According to the embodiment illustrated in FIG. 4, the shaping frame 2 has the shape of a straight prism with a symmetrical and irregular hexagonal base. The prism bases are centered around an axis Z′Z central to the reflector 1 and perpendicular to the axes X′X and Y′Y. The chassis bases have an outline resulting from two isosceles trapezoids placed head to tail along the small axis X′X of the reflector 1. The large base of the trapezoids collinear with the axis X′X is substantially equal to half of the small base of the trapezoids, and the height of the trapezoids is equal to half of the major axis Y′Y of the reflector 1. The frame 2 results from the assembly of fourteen panels 21₁ to 21₁₄ arranged vertically according to FIG. 4, and therefore perpendicular to the lower base of the prism. The chassis panels form between them triangular meshes of a polyhedral lattice. The lower longitudinal edges of the panels are coplanar with the lower base of the chassis prism. The upper edges of the panels have a curvilinear profile in accordance with the parabolic convex face of the reflector 1. The triangular structure of the hollow frame 2 has inside, six panels 21₁ to 21₆ connecting the six edges of the frame to the center Z′Z of the latter, two panels 21₇ and 21₈ along the axis Y′Y, and six peripheral side panels 21₉ to 21₁₄ connecting the edges of the chassis two by two. The chassis panels are mainly interconnected by means of a central hub 22 coaxial with the axis Z′Z, and six assemblies with three tubes 23, 24 located at the edges of the chassis.

The eight interior panels 21₁ to 21₈ converge towards the central assembly hub 22. With reference to Figs. 5 and 6, the hub 22 comprises a central tube 221 and two circular flanges 222 and 223 coaxial with the axis Z′Z. The flange 222 is welded to the lower base of the tube 221, while the flange 223 is mounted removable on the upper base of the tube 221. On the upper face of the lower flange 222 are welded eight conical full nipples for centering 224 which are terminated by cylindrical threaded ends 225. In a similar manner, the removable upper flange 223 has eight nipples conical centering hollows 226 welded into holes in the flange 223 and protruding beneath it. The lower pins 224 and upper 226 are aligned two by two parallel to the axis Z′Z, and are distributed on a circle concentric with the axis Z′Z of the tube 221 according to the star distribution of the panels 21₁ to 21₈. The small vertical edges of each of these panels are formed by two tubes 211 coming from molding, the ends of which comprise welded rings with conical bore 212 and 213 intended to cooperate with two aligned conical studs 224 and 226. The stud 224 is kept fitted in the lower ring 212, and the stud 226 is kept engaged in the upper ring 213 by means of a hollow rod 227. The lower threaded end 228 of the rod 227 is screwed onto the end 225 of the lower stud 224. The upper end of the rod 227 passes through the stud 226 and has a square head 229 applied to the upper face of the flange 223. As shown in FIG. 6, the ends of the upper longitudinal edges of the panels 21₁ to 21₈ have a small notch to accommodate the upper flange 223 there under the adjoining reflector petals 11₁ to 11₄.

The assemblies with three tubes located at the edges of the shaping frame 2 are intended to secure the small external tubular edges of three panels according to a mounting substantially similar to the central hub 22.

The two assemblies 23 located at the two end edges of the minor axis X′X are identical, and one of them for securing the large external side panels 21₁₁ and 21₁₂ and the internal panel 21₄ is shown in FIG. 7. The assembly 23 comprises oblong lower and upper flanges 231 each provided with respective conical centering pins 224, 226 so as to align the neighboring tubes 211 of the panels 21₄, 21₁₁ and 21₁₂ parallel to the major axis Y′Y and symmetrically by with respect to the minor axis X′X. Three hollow rods 227 bring together the two flanges which brace the ends of the longitudinal edges of the panels 21₄, 21₁₁ and 21₁₂.

The four assemblies 24 located at the four edges in the sectors delimited by the axes X′X and Y′Y are identical, and one of them relating to the two external side panels 21₁₂ and 21₁₃ and to the internal panel 21₅ is shown in FIG. 8. The assembly 24 comprises lower and upper flanges 241 each having three centering pins 224, 226, like the assembly flanges 231, but offering a bent profile symmetrical with respect to the internal panel 21₅. Three rods 227 with an upper head 229 and a tapped lower end 228 join the panels 21₁₃, 21₁₃ and 21₅ with the flanges 241.

The small external lateral panels 21₁₀ and 21₁₃ have, in their center aligned with the axis Y′Y, a centering tube 211Y embedded during molding and manufacturing in the core of the panel. As shown in Fig. 9, to assemble, for example, one 21₁₃ of these two external panels with the corresponding internal panel 21₈ collinear with the axis Y′Y, lower and upper oblong flanges 25 each have two respective conical centering pins 224, 226 which penetrate at the respective ends of the tube 211Y central to the external panel 21₁₃ and the adjacent extremal tube 211 of the panel 21₈. Two rods 227 secure the flanges 25 to the panels 21₁₃ and 21₈.

The shaping frame 2 thus comprises 8+ (6x3) + (2x2) = 30 sets of tube 211 and connecting rod 227.

In practice, the height of the central hub 22 is approximately 350 mm, and the height of the peripheral panel assemblies 23, 24 and 25 is approximately 900 mm.

When the panels 21₁ to 21₁₄ of the shaping frame 2 are sufficiently thick, typically 20 mm thick, the reflector petals 11₁ to 11₈ are fixed directly to the upper curved edges of the panels. Each petal is thus fixed to the respective underlying panels by means of six nylon screws 13, typically of diameter 8 mm, substantially evenly distributed along the periphery of the petal, as shown in Figs. 3 and 10. Each screw 13 passes through a hole in the petal and is screwed into a cylindrical metal insert, tapped and expandable, implanted in the upper longitudinal edge of a panel which is overmolded, as specified below.

The triangular mesh trellis structure thus produced gives very great rigidity to chassis 2 both in bending and in twisting. The six side panels 21₉ to 21₁₄ perfectly support the petals 11₁ to 11₈, avoiding any overhang. The screws 13 are conical screws in order to permanently ensure perfect jointing of the petals edge to edge and to avoid any risk of crushing during assembly thereof by unqualified personnel. The general architecture of the reflector 1 and of the chassis 2 stiffening the reflector give the antenna excellent resistance to strong winds. The presence of the panels inside the chassis does not allow the winds to rush under the reflector.

Each of the panels 21₁ to 21₁₄ of the chassis 2 also has a sandwich structure composed of a core, preferably of PMMA foam or else of a core of material identical to that of the petals, the faces of which are covered by one or more carbon films. For a PMMA panel core, the mass of chassis 2 is approximately 160 kg.

• a) A partir d'un moule mâle convexe parabolique MA dont la géométrie, qui n'est pas à symétrie de révolution, est préalablement contrôlée, le réflecteur d'antenne 1 est conforme.
• b) Les panneaux 21₁ à 21₁₄ sont découpés au profil désiré et en particulier leur chant supérieur est usiné approximativement en fonction de la face convexe inférieure du réflecteur 1. Puis les panneaux sont reliés les uns aux autres au moyen du moyeu central 22 et des assemblages à flasques 23, 24 et 25.
• c) Le réflecteur d'antenne, toujours sur le moule mâle MA en forme de paraboloïde, reçoit par-dessus le châssis-conformateur retourné qui est positionné convenablement sur le réflecteur, comme montré à la Fig. 11. Toutefois, préalablement à la pose du châssis sur le moule, la face convexe non-active du réflecteur est recouverte d'un film démoulant, et de la résine époxydique est épandue sur le film, approximativement aux jonctions correspondantes entre les panneaux et le réflecteur. La résine peut être largement épandue pour former des cornières surmoulées de largeur déterminée le long et de chaque côté des chants longitudinaux courbes des panneaux raidisseurs 21₁ à 21₁₄. Ces cornières peuvent servir, dans certaines réalisations, à recevoir des vis de fixation de pétale, ou servir comme appui des pétales lorsque les panneaux sont minces.
• d) Après thermodurcissement de la résine de surmoulage, les chants longitudinaux concaves des panneaux de châssis épousent parfaitement la forme parabolique du réflecteur. La position du châssis sur le réflecteur est précisément repérée, et/ou le cas échéant, des perçages et contre-perçages entre les cornières 24 du châssis 2 et les pétales 11₁ à 11₈ du réflecteur 1 sont effectuées pour des vis de fixation 13 notamment.

The manufacture of the reflector 1 and of the shaping frame 2 as just described preferably comprises the following steps, with reference to FIG. 11.

• a) From a parabolic convex male mold MA whose geometry, which is not with symmetry of revolution, is previously checked, the antenna reflector 1 is in conformity.
• b) The panels 21₁ to 21₁₄ are cut to the desired profile and in particular their upper edge is machined approximately as a function of the lower convex face of the reflector 1. Then the panels are connected to each other by means of the central hub 22 and the assemblies with flanges 23, 24 and 25.
• c) The antenna reflector, still on the male mold MA in the form of a paraboloid, receives over the inverted shaping frame which is properly positioned on the reflector, as shown in FIG. 11. However, before installing the chassis on the mold, the non-active convex face of the reflector is covered with a release film, and epoxy resin is spread on the film, approximately at the junctions. between the panels and the reflector. The resin can be widely spread to form molded angles of determined width along and on each side of the curved longitudinal edges of the stiffening panels 21₁ to 21₁₄. These angles can be used, in certain embodiments, to receive petal fixing screws, or serve as support for the petals when the panels are thin.
• d) After thermosetting of the overmolding resin, the concave longitudinal edges of the frame panels perfectly match the parabolic shape of the reflector. The position of the frame on the reflector is precisely identified, and / or where appropriate, holes and counter-holes between the angles 24 of the frame 2 and the petals 11₁ to 11₈ of the reflector 1 are made for fixing screws 13 in particular.

It should be noted that the assembly by mechanical fixing of the antenna reflector and of the shaping frame allows the dismantling of the antenna while guaranteeing the geometry of the reflector determined during molding. The operation of overmolding the edges of the panels and possibly of the angles as well as certain holes and counter-holes must be imperatively carried out before the antenna reflector is separated from its mold.

e) After dismantling the chassis 2 and removing its panels, the molded edges of the panels are cleaned and deburred. Then the reflector is cut to the desired profile into several petals, in this case eight petals 11₁ to 11₈.

The main advantage of the demountable shaping frame independently of the antenna reflector is to offer, after disassembly, the smallest possible volume which facilitates the transport of the panels of the shaping frame, in particular by plane. The mass of each of the elements, reflector petals or chassis panels, does not exceed 20 kg, and the length and width of each of these elements is less than 3 m and 1.5 m, and therefore less than the standard dimensions. of 3.07 mx 1.8 m pallet for main line aircraft. These characteristics allow easy mounting of the frame and the reflector, without ever use of handling equipment, and space-saving stacks of the elements.

Other embodiments of a chassis structure with a convex polygonal lower base can be designed on the basis of the manufacturing and dismantling concepts mentioned above. Figs. 12 and 13 show a chassis 2a having a parallelepiped structure for a reflector 1a similar to the reflector 1. The chassis 2a comprises two pairs of panels 21a₁, 21a₂ and 21a₃, 21a₄ aligned along the axes X′X and Y′Y and assembled by a central hub with 4 branches 22a, two small transverse panels 21a₅ and 21a₆ parallel to the axis X′X and similar to the panels 21₁₀ and 21₁₃, two pairs of longitudinal panels 21a₇, 21a₈ and 21a₉, 21a₁₀ parallel to the axis Y′Y , and four internal panels 21a₁₁ to 21a₁₄ connecting two by two the midpoints of the external sides of the chassis. According to another variant, the panels 21a₁₁ to 21a₁₄ are aligned two by two along the diagonals of the frame rectangle. The panels are assembled by eight pairs of suitable flanges 23a and 24a. Fig. 12 shows the locations of fixing screws 13a of the petals 11a₁ to 11a₈ of the reflector 1a on angles molded onto the concave upper longitudinal edges of the panels 21a₁ to 21a₁₄, assumed here to be thin. Jumpers 14a are provided at the edge-to-edge junctions of the petals 11a₁ to 11a₈ on the contour of the reflector 1a to maintain the surface continuity of the reflector against its own bending.

When mounting the reflector and the chassis in situ, the chassis panels are arranged directly on the ground. Then we proceed with the assembly of the source-carrying mast 3, the lifting mast on site 5 and the azimuth positioner 6.

According to a first embodiment shown in Figs. 14 and 15, the source-carrying mast 3 essentially comprises a beam 31 of the box type overhanging the reflector, this two flat fixing amounts substantially in isosceles triangle 32 and 33. A plate 41 is fixed in the upper part of the beam 31 and carries the microwave source 4. The four parts 31, 32, 33 and 41 are made of a light material similar to that of the petals of the reflector and of the chassis panels, and preferably of the sandwich structure type comprising a core of PMMA foam or of Honeycomb of the NOMEX type manufactured by DU PONT DE NEMOURS, the faces of the core being covered by carbon films.

The beam 31 has a rectangular hollow section having a constant width of 0.4 m and a height decreasing upwards over a length of 3 m. A lower face 34 of the beam 31, which is normally perpendicular to the plane X′XY′Y of the reflector, has an upper end 35 bolted to the higher acute vertices of the uprights 32 and 33. The lower end of the beam face 34 and substantially the middle of the long sides of the uprights 32 and 33 bracing the face 34 are pivotally mounted about an axis 36 substantially coplanar with the plane X′XY′Y and parallel to the axis X′X. This pivot axis 36 is fixed by suitable small angles on one, 21₁₀, of the two side panels of the chassis 2 parallel to the axis X′X. The lower acute peaks 37 of the uprights 32 and 33 are bolted to small angles fixed to the frame panel 21₁₀.

At work, the lower ends 37 of the uprights 32 and 33 are fixed to the chassis 2, and the source carrying mast 3 is stationary as shown in FIG. 1. At this position, the rear face 310 of the beam 31 which is not opposite the reflector 1 is parallel to the focal axis F′F of the parabolic reflector. The face 310 serves as a reference for positioning the plate 41 at the top of the beam.

The plate 41 has on either side of an elbow, a lower flat wing 411 and an upper flat wing 412. The wing 411 is applied to the face 310 and comprises at least one adjustment light 413 parallel to the focal axis F′F and traversed by a bolt 414 fixed to the top of the beam 31 so as to slide the plate 41 parallel to the axis F′F and thus adjust the position of the microwave source 4 which is supported by the other platinum wing 412. The focal length can thus be adjusted.

At rest, the lower ends 37 of the uprights are detached from the chassis 2, and since the axis 36 is substantially above the reflector 2, the mast 3 can tilt around the axis 36 and thus be laid on the reflector 2. At this position, the plate 41, or only the source 4, or even the mast 3 can be separated from the chassis 2 and dismantled, without using ladders and dismantling the lifting mast in site 5 which can be fixed to the same external panel 21₁₀ as the source holder mast 3, as shown in FIG. 1. During the dismantling of the source holder mast 3, the plate 41 is placed in a box with the source 4 without the latter being separated from the plate, and the uprights 32 and 33 are separated from the beam 31 in order to easily store in an aircraft hold.

Another embodiment of source holder mast 3a is shown in FIGS. 16 and 17. The mast 3a then comprises a single thin and full beam which is in fact composed of two plates 31a and 32a connected by suitable angles at an elbow 35a of the mast. The upper plate 31a is parallel to the focal axis F′F when the bottom 37a of the lower plate 32a is fixed against the chassis panel 21₁₀ and parallel to the axis Z′Z. The central part of the plate 32a is pivotally mounted around axes 36a parallel to the axis X′X, like the flanges 32 and 33. The front face of the plate 31a, here opposite the reflector, supports at the top l 'lower wing of a bent plate 41a, similar to plate 41.

With reference to Figs. 18 and 19, the lifting mast on site 5 essentially comprises a lower tube 50 with an external diameter of 80 mm, an upper tube 51 with an external diameter of 100 mm, a slide 52 to be connected to the shaping frame 2 of the antenna, and a set of idler pulleys for an AC winch cable TR.

The lower tube 50 comprises a foot 53 which comprises, in the lower part 501, a yoke 531 with two semi-circular branches to rest on the ground S, and, in the upper part, a tubular end piece 532 which is nestable in the lower end of the tube 50 abutting the base of the yoke 531. The tubular end piece 532 contains a pulley 533 whose axis is radial to the tube 50 and which is positioned substantially above a lower cable passage hole 501 made in the tube 50. In the upper end 502 of the tube 50 is nestable in abutment another tubular end piece 54 which also comprises a pulley 541. The axis of the pulley 541 is substantially offset, to the left according to FIG. 19, relative to the longitudinal axis of the tube 50, so that the pulley 541 projects substantially through an upper slot 503 of the tube 50.

The upper tube 51 also comprises two tubular end pieces with pulleys 55 and 56. The lower end piece 55 is pluggable in abutment in the lower end 511 of the tube 51 and receives the lower tube 50 by axial sliding, through the upper end 502 end piece 54. The end piece 55 includes a pulley 551 whose axis is perpendicular to the axis of the tube 51 and which is located outside the end of the tube 511, in front of a longitudinal slot 513 thereof. The upper end 56 of the second tube 51 has a longitudinal T-profile whose vertical leg is nestable in the upper end 512 of the tube 51. One of the horizontal wings of the T-profile supports a pulley 561 whose axis is parallel to that of the pulley 551 and located at the same distance from the axis of the tube 51. The other wing of the T-piece 56 comprises a hooking device 562 of an upper end of the cable CA. The members 561 and 562 are substantially symmetrical with respect to the tube 51, and more particularly are located above and on either side of a pulley with a radial axis 521 mounted outside the tubular slide 52.

The slide 52 can slide with friction along the upper tube 51, between stops suitable for the ends 511 and 512. An axis 523 is fitted into the slide 52 perpendicular to the longitudinal axis of the tube 51 and to the axis of the pulley 521 and is mounted to rotate in a yoke 524 fixed by a support plate 525 (Figs. 20 and 21) in the lower part of one of the small external panels of the chassis. According to FIG. 1, the yoke 524 is integral with the panel 21₁₀ and situated substantially between and below the uprights 32 and 33 of the source holder mast 3.

The upper tube 51 can slide with friction along and around the lower tube 50, with a stroke limited by appropriate stops between the pulleys 533 and 561.

The foot 53 with rounded ends 531 makes it possible to tilt the mast 5 relative to the ground S, during the lifting of the chassis 2 which rests on two stable support points by means of the azimuth positioner 6, as will be seen below. . These two support points are opposite the foot 53 relative to the central axis Z′Z of the chassis, and of course, the lifting mast in elevation 5 always remains in the mediating plane of these two support points. For example, like shown in Fig. 1, when the mast 5 is fixed via the hinge pin 523 along the vertical axis of the chassis panel 21₁₀, the two other stable points on the ground are located at the level of the chassis edges 24 bordering the opposite panel 21₁₃

According to the diagram in FIG. 19, the cable CA travels from an electric winch TR resting on the ground S, by first entering the lower tube 50 through the hole 501, then bypassing the lower pulley 533. The cable CA runs along the inside the tube 50 and passes over the upper pulley 541 internal to the tube 50. The cable CA leaves the tube 50 through the slot 503 and descends into the lower end 511 of the upper tube 51, along the upper end 502 of the lower tube 50 to finally exit the tube 51 through the lower slot 513 and bypass the external pulley 551 below. The cable CA then extends outside the tube 51, from the pulley 551 to the pulley 561, bypassing this last pulley from below. Finally, the cable descends to bypass the external pulley 521 of the slider 52 from below and rises to fix an upper end of the cable at 562. The elements 561, 521 and 562 thus form a hoist with two simple pulleys fixed to the upper end 56 mast 5.

In a state of rest of the mast 5, the tube 51 almost covers the tube 50, and the slide 52 is in the low position on the tube 51 the frame 2 being almost in the horizontal position. A pull of the cable CA exerted by the winch TR makes it possible to bring the pulley 551 closer to the pulley 541 and therefore to raise the tube 51 by sliding along the tube 50 resting on the ground S, and to bring the pulley 521 closer to the slide 52 toward the upper end 512 of the mast supporting the pulley 561. These two connections can be made one after the other or almost simultaneously, depending on the relative friction between the two tubes 50 and 51 and between the tube 51 and the slide 52. As the traction on the AC cable progresses, the side 21₁₀ of the chassis 2 according to FIG. 1 which is articulated to the slide 52 rises, the axis Y′Y of the chassis becomes more and more inclined with respect to the ground S and the focal axis F′F tends to approach the horizontal, while the mast 5 tilts towards the ground and the foot 53 pivots on the ground.

For tubes 50 and 51 each having a length of 3 m, the elevation angle of the focal axis F′F to point towards a geostationary satellite can vary from 65 ° 30 ′, as shown in FIG. 1, at 17 °. To cover elevation angles of 17 ° to 0 °, a mast extension 57 having a length of approximately 1.8 m extends the upper end 512 of the tube 51 by means of a double tubular end piece 58, as shown in the Fig. 18. In this case, the upper end 572 of the extension receives the T-piece 56. FIG. 22 shows the mast 5 fitted with the extension 57 when the focal axis F′F is placed horizontally; this corresponds for example to an antenna located in a polar region and pointed towards a geostationary satellite with substantially equatorial orbit.

Knowing that the focal axis F′F and therefore the direction of the beam 31 of the source-carrying mast 3 makes an angle of 65 ° 30 ′ with the normally horizontal plane X′XY′Y to which the panels of the chassis 2 are perpendicular, it is necessary to fix the source holder mast 3 against the small chassis panel 21₁₃ opposite to the panel 21₁₀ to which the elevation mast 5 is articulated, so that the elevation angle of the focal axis F′F varies between 65 ° 30 ′ and 90 °. In Fig. 23, for an elevation of 90 ° for the axis F′F, the antenna was for example transported in the equatorial region and pointed towards a geostationary equatorial satellite.

The tubes 50 and 51, the extension 57, the slide 52 and the end pieces 53, 54, 55, 56 and 58 can be tubes of thickness 5 mm in aluminum, or tubes of thickness 2 mm in carbon. The two mast versions 5 offer similar resistances, but the first aluminum version weighs approximately 45 kg, while the second weighs approximately 20 kg.

With the lifting mast on site 5, at least one cable fall arrest and cable reel safety system 58 can be provided, shown diagrammatically in FIG. 19. System 58 functions as a car seat belt. A cable 581 of the system 58 has one end 582 anchored in the ground S, and another end fixed to a cable reel 583 also anchored on the ground S. The cable 581 bypasses a pulley 584 fixed to the upper end 512 of the tube 51, and the strand of the cable anchored to the ground at 582 is integral with the slider 52 by an adequate fixing means 585. In case of sudden relative displacement of the slide 52 or of the tube 51, the system 5 immobilizes these elements 51, 52 in order to keep the mast 5 rigid at a desired length and avoid any sudden fall of the chassis 2 with the reflector 1, following a rupture AC traction cable or pulley, or a malfunction of the TR winch.

As shown in Figs. 1 and 2, the azimuth positioner 6 comprises a curved beam profiled in I 61, two pads 62₁ and 62₂ with one or two rollers, and several screw jacks 63.

The beam 61 is in fact constituted by three identical curved elements 61₁ to 61₃ having an average radius R = 6.25 m substantially greater than the length of the chassis in order to allow, according to FIG. 24 a rotation of the lateral lower ends of the panel 21₁₃ sliding on the ground via the pads 62₁ and 62₂ around the foot 53 of the tube 50 of the lifting mast in elevation 5. The length L of each curved element 61₁ to 61₃ substantially exceeds the half-length of a small side panel 21₁₀, 21₁₃ of the chassis 2 and therefore the half-distance separating the two pads 62₁ and 62₂, and is of the order of 1.76 m. The length L corresponds to a variation in azimuth of 16 °. The division into three elements of the beam 61 offers the double advantage that the beam is air-transportable, and that the use of only three elements allows orientations in azimuth from 0 ° to ± 180 ° of the antenna. Indeed, the chassis 2 is pushed for example to the left according to FIG. 24, and when the chassis 2 and therefore the pads 62₁ and 62₂ are located completely on the elements 61₂ and 61₃, the element 61₁ is removed and then abutted to the element 61₃ to again pivot the chassis by an azimuth angle of 16 °. The elements 61₁ to 61₃ are thus swapped several times to make a complete 360 ° turn of the antenna around a vertical axis passing through the foot 53 of the mast 5.

As shown in Fig. 25, the beam 61 is profiled transversely in I and comprises a central vertical core 611, a support plate 612 in the lower part, and another narrower plate 613 in the upper part.

The plate 613 constitutes a raceway for the pads 62₁ and 62₂. As also shown in FIG. 25, each shoe 62 comprises a roller 620 rolling on the plate 613, and two flanges circular lateral guide 621 laterally bracing the raceway 613 and thus retaining and guiding the shoes on the way 613. A double yoke 623 in the upper part of the shoe 62 receives an articulation axis which is parallel to the axis X′X and therefore forms a cord of the circular raceway 613 and which is fixed in one of two suitable notches made in the chassis, in the lower part of the small panel 21₁₃, in the vicinity of the edges 24 thereof.

The ends and, if necessary, the middle of each of the curved elements 61₁ to 61₃, rest on the ground S by means of three screw jacks or three pairs of screw jacks, such as that 63 shown in Figs. 26 and 27. The jack 63 comprises a circular base 631 with four holes 632 for receiving stakes to be anchored in the ground, a threaded cylindrical body 633 screwed in the center of the base, and a threaded rod 634 to be screwed into the cylinder 633 and having a head formed by a rectangular plate 635. The support plate 612 of an element 61₁ to 61₃ can be fixed by bolts to the plate 635.

The plates 635 of the various jacks 63 are adjusted to the same horizontal level by screwing or unscrewing the rods 634 in order to compensate for the slope of the ground where the antenna is installed and to position the beam of the raceway 61 horizontally. The body cylindrical 633 of each cylinder is removable from the base 631 in order to interchange it with other cylindrical bodies 633₁, 633₂, having different heights, as shown in FIG. 26.

The curved elements 61₁ to 61₃ are preferably of sandwich structure with honeycomb core of the NOMEX type and carbon faces. The pads 62₁ and 62₂ are made of light alloy covered with nylon. The screw jacks 63 are mainly made of aluminum.

According to another variant shown in Figs. 28, 29 and 30 the cylinders 63 are replaced by a rocker 64. The rocker comprises a flat rectangular sole 641, having a length of 3 m, and a support 642 in the form of a plate with vertical U-shaped section, resulting from the junction of two symmetrical U-shaped plates each having a length of 2 m. The support 642 has a supporting beam 643 long enough for an azimuth variation of ± 6 ° approximately and wide enough to fix at least two curved elements 61₁ and 61₂ The vertical sides 644 of the support 642 are cut into an isosceles triangle, the obtuse vertices pointing downwards are mounted for rotation about a horizontal axis 645, transverse and median to the sole 641.

The flip-flop 64 makes it possible to maintain the antenna at a constant position relative to a horizontal plane when the antenna is installed on board a ship capable of undergoing a roll of the order of ± 15 °. The longitudinal axis of the ship is then substantially parallel to the axis 645 of the scale. A triaxial electromechanical servo-control (not shown) of the azimuth rotation of the antenna parallel to the axis Z′Z and along the curved elements 61₂, 61₂, for tilting the rocker 64 parallel to the axis Y′Y, and the inclination of the lifting mast in elevation 5 around the direction X′X can be provided to maintain a determined position of the antenna during yawing, rolling and pitching of the ship.

However, the scale 64 can be used on the ground, to immediately correct the slope of a terrain. In this case, after positioning the antenna in azimuth, and possible balancing of the scale by weights, the inclination of the support beam 643 relative to the sole 641 is maintained by means of two jacks 63 suitably adjusted and applied under the ends of the side member 643, as shown in dotted lines in FIG. 28.

Claims (22)

1 - Telecommunications antenna, comprising several separable elements (11₁ to 11₈) which are assembled to provide a continuous concave parabolic reflector surface (1), characterized in that it comprises several substantially rectangular separable panels (21₁ to 21₁₄) which are assembled in a prismatic lattice frame (2) to support the parabolic reflector, said elements being thin with a substantially uniform thickness and joined, and said panels extending substantially perpendicular to a lower base of the lattice and having curvilinear upper edges which are shaped according to the convex face of the parabolic reflector (1) to support in a separable manner the reflector elements (11₁ to 11₈). 2 - Antenna according to claim 1, characterized in that each of the reflector elements (11₁ to 11₈) is substantially rectangular and has sides respectively to two perpendicular median axes (X′X, X′Y) of the reflector (1 ) and at least one side formed by the substantially circular contour of the reflector. 3 - Antenna according to claim 1 or 2, characterized in that the reflector elements (11₁ to 11₈) and / or the chassis panels (21₁ to 21₁₄) are each inscribed in a predetermined rectangle, preferably 3 mx 1 , About 5 m. 4 - Antenna according to any one of claims 1 to 3, characterized in that the reflector elements (11₁ to 11₈) and / or the chassis panels (21₁ to 21₁₄) are each of sandwich structure composed of a core in synthetic material, or honeycomb or light wood, and carbon faces. 5 - Antenna according to claim 4, characterized in that the concave carbon face of the reflector elements (11₁ to 11₈) is covered with a braided metal grid, and a Kevlar protective fabric. 6 - Antenna according to any one of claims 1 to 5, characterized in that the surface mass of the elements of the reflector (11₁ to 11₈) or of the chassis panels (21₁ to 21₁₄) is less than approximately 11 kg / m², and preferably around 5 kg / m². 7 - Antenna according to any one of claims 1 to 6, characterized in that the base of the frame mesh (2) is convex polygonal, and in that each of the side faces of the frame is constituted by one of said panels (21₉ to 21₁₄) 8 - Antenna according to any one of claims 1 to 7, characterized in that internal panels (21₁ to 21₆) of the chassis connect edges (23, 24) of the trellis to the center (22) of the trellis. 9 - Antenna according to one of claims 1 to 8, characterized in that the edges of the panels (21₁ to 21₁₄) perpendicular to the lower base of the chassis lattice (2) are formed by tubes (211), and in that the frame comprises several removable means (22; 23; 24) for connecting in parallel the edge tubes (211) of several groups of panels converging at the center and towards the edges of the trellis, respectively. 10 - Antenna according to claim 9, characterized in that each means for connecting in parallel panel edge tubes of a group comprises a first flange (222) located at the lower base of the chassis lattice (2) and supporting first centering pins (224), to penetrate into the lower ends (212) of edge tubes (211) of the panels of said group, a second flange (223) located in the vicinity of the underside of the reflector (1) and comprising second centering pins (226) for penetrating upper ends (213) of the tubes of the panels of said group, and means (227) for clamping the tubes of the panels having received said centering pins (224, 226) between the flanges (222, 223). 11 - Antenna according to any one of claims 1 to 10, characterized in that it is of the microwave source type (4) offset (offset) relative to the focal axis (F′F) of the reflector (1 ), and in that it comprises a mast (3) carrying the source (4), a lower part (32, 33) of which is fixed laterally to one (21₁₀; 21₁₃) of side panels of the chassis and one of which upper part (31) overhangs the reflector and is arranged parallel and close to the focal axis (F′F) of the reflector. 12 - Antenna according to claim 13, characterized in that the lower part (32, 33) of the source carrying mast (3) is pivotally mounted (36) against the side frame panel (21₁₀; 21₁₃) in order to lie down the mast (3) on the reflector (1). 13 - Antenna according to any one of claims 1 to 12, characterized in that it comprises a removable site mast (50, 51) having one end (53) resting on the ground (S), a slide (52 ) sliding along the site mast and articulated to one (21₁₀) of the chassis side panels, and means (TR, CA) for raising the slider along the site mast. 14 - Antenna according to claim 13, characterized in ′10 that the site mast (5) is telescopic and comprises a lower tube (50) standing on the ground (5), and an upper tube (51) sliding along of the lower tube and along which slides the slide (52), and in that the means for raising (TR, CA) also raise the upper tube (51) relative to the lower tube (50). 15 - Antenna according to claim 13 or 14, characterized in that the means for raising comprise a winch (TR) on the ground (S), and a cable (A) towed by the winch and traveling from the winch through pulleys ( 533, 541, 551) fixed to the site mast (50, 51) towards a hoist (561, 521, 562) located in the upper part of the site mast and having a central pulley (521) fixed to the slide (52). 16 - Antenna according to any one of claims 13 to 15, characterized in that the site mast (50, 51) and the slide (52) are composed of tubular elements based on aluminum or carbon. 17 - Antenna according to any one of claims 13 to 16, characterized in that it comprises safety means (58) anti-fall of the chassis (2) to block the slide (52) on the site mast ( 5). 18 - Antenna according to any one of claims 1 to 17, characterized in that it comprises two rolling means (62₁, 62₂) pivotally mounted (623) under one (21₁₃) of side panels of the chassis ( 2), and a removable raceway (61) for the rolling means in order to orient the antenna in azimuth. 19 - Antenna according to claim 18, characterized in that the raceway is composed of three separable elements in an arc (61₁, 61₂, 61₃) having a radius (R) preferably substantially greater than the length of the chassis ( 2), and each having a length (L) substantially greater than the half-distance separating the two rolling means (62₁, 62₂) 20 - Antenna according to claim 18 or 19, characterized in that each of the rolling means (62₁, 62₂) comprises a roller (620) comprising two circular guide and retaining flanges (621) which border the raceway (61 ). 21 - Antenna according to any one of claims 18 to 20, characterized in that it comprises means, preferably of the type with screw jacks (63), supporting said raceway (61) to compensate for the gradient of the land where the antenna is installed, in order to horizontally position said raceway (61). 22 - Antenna according to any one of claims 18 to 20, characterized in that it comprises a rocker (64) resting on the ground (S) and supporting the raceway (61) in order to horizontally maintain the raceway rolling.

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