Communications: radio wave antennas – Antennas – Antenna components
Reexamination Certificate
1999-04-02
2001-01-16
Ho, Tan (Department: 2821)
Communications: radio wave antennas
Antennas
Antenna components
C343S705000
Reexamination Certificate
active
06175341
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an elastically deformable antenna reflector for a spacecraft, such as an artificial satellite or space probe.
2. Description of the Related Art
It is known that the items of equipment, such as the antenna, solar panels, etc, associated with a spacecraft have to be able to be folded in order to be able to be accommodated in a launch vehicle (rocket, shuttle) and to be deployed after ejection out of said launch vehicle, so as to take up their operational configuration.
It is known, moreover, that such equipment has already been produced in such a way that it is elastically deformable, this equipment then being able to take up either a deployed state, or a folded state, elastically deformed. By way of example, mention may be made of:
the U.S. Pat. No. 3,521,290, which describes an antenna reflector in a single piece of an elastically deformable material provided with a rigid central base to which are linked a plurality of radial ribs integral with the convex face of said reflector and elastically articulated to said central base. Thus, said antenna reflector can take up a position folded into the shape of a tulip, which does not risk entailing a permanent deformation of said reflector, and the change from the folded position into the deployed position in the shape of a concave disk can be carried out under the action of the elastic energy stored during the folding of the antenna structure. Controllable retaining means, consisting of a belt with pyrotechnic bolts surrounding said folded reflector and arranged on the opposite side from said central base, are provided in order to hold said reflector and said radial ribs in the folded position under stress;
the U.S. Pat. No. 4,133,501, which describes a solar panel in a single piece for a spacecraft produced in an elastically deformable way in order to take up either a curved folded position under stress in which said solar panel matches the convex outer surface of said spacecraft, or a flat deployed position, clear of said outer surface, the change from the curved, folded position to the flat, deployed position being due to the elastic relaxation of said solar panel. In the curved folded position, the solar panel is held against the outer surface of said spacecraft by latches, carried by the spacecraft; and
the U.S. Pat. No. 4,926,181, which describes an antenna reflector in a single piece of an elastically deformable material, which can be rolled into a cylindrical shape and held in this shape by clamps. An underlying pliable structure can be deployed, in order to serve as a support on which said reflector can unroll and take up its deployed, operating shape, under the action of its elastic relaxation.
Moreover, as demonstrated, for example, by the U.S. Pat. No. 5,644,322, it is usual, for launching said spacecraft, to store it in an elongate casing, for example of cylindrical-conical shape, constituting, for example, the upper nose cone of the launch rocket, the reflector of the antenna or antennae of said spacecraft being arranged laterally with respect to the body of the latter in the peripheral space defined between said body and said casing. In this prior document, the antenna reflector consists of a central rigid base of large surface area surrounded by a peripheral frustoconical ring produced from an elastically deformable material. Hence, by virtue of such a structure, the size of the reflector, within said cylindrical-conical casing, can be slightly reduced by temporarily elastically deforming said peripheral ring, said reflector then taking up the shape, at least approximately, of a bowl laterally encasing said body. The reflector is kept in this bowl shape by a belt, loosening of which is controlled electrically and which surrounds said body and said reflector at the center of said base, this belt folding said elastically deformable ring down onto said body, bearing on two diametrally opposite points of said ring. After ejection in space, said reflector can resume its operating position, by removal of said belt and elastic return of said peripheral ring to its elastically relaxed, stable, deployed position.
It can easily be understood that, in such a device, the saving in size of said reflector in the folded position, by comparison with the deployed position, is limited. This is because, on the one hand, because of the large diameter of said rigid central base, the lateral compression of the reflector can be applied only to the peripheral ring, such that the saving in the lateral size is relatively small. Moreover, this lateral compression not only exerts no reducing action on the longitudinal dimension of said reflector, but also increases said dimension due to the fact that it entails the straightening of the upper part of said peripheral ring outwards. The longitudinal size of the reflector, in the folded position, is thus greater than that of its deployed position. Because of its dimensions, said reflector generally overshoots the upper longitudinal end of the body of said vehicle housed in the cylindrical part of the casing and has to be extended into the conical part thereof. This conical shape thus imposes a limitation on the diameter of the reflector. However, for obvious reasons of performance, it would be advantageous for the reflector to be able to have as large a diameter as necessary, and to match the convergent shape of the conical part of the casing.
Moreover, it will be noted that, in the folded position, the reflector of the U.S. Pat. No. 5,644,322 is not held firmly, such that it is subject to the vibrations induced during the launch. This can result in difficulties of dynamic balancing and of damping of the vibration of said reflector, and even damage to the reflector or to the surrounding objects.
SUMMARY OF THE INVENTION
The object of the present invention is to remedy these drawbacks, while making it possible to increase the dimensions of said antenna reflector.
To this end, according to the invention, the antenna reflector for a spacecraft having to be stored in a casing of cylindrical-conical shape that is elongate along an axis, in such a way that said reflector is arranged laterally with respect to the body of said spacecraft, in the peripheral space defined between said body and the cylindrical part of said casing, and that said reflector exhibits a peripheral part projecting longitudinally into the conical part of said casing from the longitudinal end of said body, said reflector being at least partly elastically deformable in such a way that:
outside said casing, said reflector can take up a stable, deployed state without elastic stress, corresponding to its functional shape;
within said casing, said reflector, by elastic folding around said axis of the casing, can take up a folded state allowing it laterally to envelop said body, said reflector being held in this folded state by virtue of controllable retaining means; and
the change by said reflector from its folded state to its deployed state being due at least in part to the release of the energy stored in said reflector when it was elastically folded in order to make it change from its deployed state to its folded state,
is noteworthy:
in that said reflector is separated into two parts by opposing slot edges; and
in that, in the folded position of said reflector, said opposing edges of said reflector parts move with respect to one another so as to bring said protruding peripheral part of the reflector closer to said longitudinal end of said body.
Moreover, in accordance with another important feature of the present invention, provision is made for said controllable retaining means, in the folded position of the reflector, to secure said reflector parts to the body of said spacecraft.
It is thus easily seen that, according to the present invention, the abovementioned problems of longitudinal size and of vibration are solved.
The arrangement of said the slot edges with respect to the reflector can be varied, provided that it allows the relative movement
Antoine No{umlaut over (e)}l
Cautru Guillaume
Noir Alain
Prud'Hon Christophe
Aerospatiale - Societe Nationale Industrielle
Ho Tan
Stevens Davis Miller & Mosher L.L.P.
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