Communications: radio wave antennas – Antennas – Antenna components
Reexamination Certificate
1999-07-01
2001-04-17
Ho, Tan (Department: 2821)
Communications: radio wave antennas
Antennas
Antenna components
C343SDIG002
Reexamination Certificate
active
06219010
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an elastically deformable antenna reflector for a spacecraft, such as an artificial satellite or space probe.
It is known that the items of equipment, such as the antennas, 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.
DESCRIPTION OF THE PRIOR ART
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 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 side opposite said central base, are provided in order to hold said reflector and said radial ribs in folded position under stress;
the U.S. Pat. No. 4,133,501, which describes a solar panel for a spacecraft produced in a single elastically deformable piece in order to be able to take up either a curved, folded position under stress for 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 curved, folded position, the solar panel is held against the outer surface of said spacecraft by latches, carried by this surface; and
the U.S. Pat. No. 4,926,181, which describes a single-piece antenna reflector 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;
the U.S. Pat. No. 5,644,322, which describes an antenna reflector consisting of a central rigid base of large surface area, surrounded by a peripheral frustoconical ring, produced from an elastically deformable material. This prior document shows, moreover, that it is usual, for launching a spacecraft, to store it in an elongate casing, for example of cylindrical-conical shape, constituting, for example, the upper nosecone of the launch rocket, the reflector of the antenna or antennas of said spacecraft being arranged laterally with respect to the body of the latter in the peripheral space bounded between said body and said casing. 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 than taking up the shape, at least approximately, of a bowl laterally enveloping 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 in the central region 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 into 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 folded position, by comparison with the deployed position, is limited. This is because, due to 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, it will be noted that, in folded position, the reflector of 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 its surrounding objects; and
the U.S. Pat. No. 5,574,472 and the Patent EP-A-0 534 110 describe an antenna reflector in a single piece of an elastically deformable material, which can take up a bowl-shaped folded position with a rounded section by virtue of a controllably frangible tensile link arranged between two diametrally opposed points of the periphery of said reflector. It will be noted that, in this position folded into the bowl shape, the reflector, because of its relative rigidity, cannot follow the lateral contour of said body as closely as it might. It results therefrom that the size of the reflector in folded position cannot be optimal. Moreover, it will be noted that the tensile link constitutes an obstacle, or at least an impediment, in arranging the body of the spacecraft in the concave space of the reflector in folded position, and that the production of said reflector in a single piece allows neither precise control of the shape of the reflector in folded position, nor optimal enveloping of the body of the spacecraft.
SUMMARY OF THE INVENTION
The object of the present invention is to remedy these drawbacks, and to allow said antenna reflector to envelope said body of the spacecraft as well as possible, and thus minimize the peripheral size of said reflector, while best controlling the shape and the vibrations of the reflector in folded position.
To this end, according to the invention, the antenna reflector for a spacecraft having to be stored in a casing of elongate shape 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 bounded between said body and said casing, said reflector being 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 is elastically folded in order to make it change from its deployed state to its folded state, is noteworthy in that said reflector includes at least one fold line, the general direction of which is at least approximately parallel to said axis of the casing and about which said reflector is folded into its folded state.
Moreover, in accordance with another important feature of the present invention, provision is made for said controllable retaining means to fasten said reflector firmly to the body of said spacecraft.
It is thus easily seen that, according to the present invention, the abovementioned problems of peripheral size and of vibration are solved. This is because, by virtue of said fold line or lines, it is possible to obtain sharp angles of fold which allow said reflector to match the lateral contour of said body as well as possible (particularly if the latter is of rectangular parallelepipedal form as is u
Cautru Guillaume
Chieusse Nathalie
Noir Alain
Prud'Hon Christophe
Aerospatiale - Societe Nationale Industrielle
Alemu Ephrem
Ho Tan
Stevens Davis Miller & Mosher LLP
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