Communications: radio wave antennas – Antennas – Antenna components
Reexamination Certificate
1999-04-23
2001-05-08
Le, Hoanganh (Department: 2821)
Communications: radio wave antennas
Antennas
Antenna components
C343S912000
Reexamination Certificate
active
06229501
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a reflector and a reflector element for antennas for use in outer space.
BACKGROUND
Antenna reflectors for satellites or space vehicles must fulfill a number of requirements. For example, they must be lightweight and have a high accuracy. It is important that they can be stowed in a very small space when transported into space.
For this purpose, reflectors have been developed, which are folded together during transport into orbit and are then deployed in space. Conventional mechanisms, however, are often susceptible to jamming together, which often leads to failure of the reflector to be utilized after it is transported into space. In addition, known reflectors only have a limited size, which is additionally limited, for example, by requirements for accuracy. Further, there is the problem that the reflectors are subjected to high stresses due to thermal effects and by radiation, which in the case of known reflectors often leads to a delay and to a consequent inaccuracy of the reflector surface. Specific requirements are placed on the reflector, depending on the type of application, and thus, the development and manufacture of individual reflectors is associated with high cost.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a reflector for use in space, which can be easily transported into space, can be safely and simply deployed, has a large surface with a high shape stability and can be used for multiple purposes.
According to one aspect of the invention, a reflector is provided for antennas for application in space, which comprises:
a plurality of individual reflector elements,
a rigid central element,
a support structure connecting said individual reflector elements to said central element, said support structure having collapsed and extended states which provide respective collapsed and deployed states for said reflector elements,
said reflector elements in said deployed state adjoining one another to collectively form said reflector.
In this way, it is achieved that the reflector can be stowed in a very small space, and after deployment has a large reflector surface, which is stable and has a high contour accuracy. The reflector returns to its original unfolded state when deployed in the operating state, i.e., without application of external force whereas conventional deployable reflectors are stressed to reach their operating position.
Preferably, the central element is itself a reflector, which forms a part of the overall reflector surface in the operating position. The individual reflectors are preferably hexagonal at their perimetral edges and arranged circumferentially around the central element in the operating position. In this way, a particularly large effective reflector surface is obtained in the operating position.
Preferably, the support structure has rigid support arms, on which flexible elastic elements, such as springs or leaf-spring elements, are arranged to form pivotal connections. In this way a freedom of play of the mechanical elements is achieved, which increases the stability and the surface accuracy of the reflector. The reflector preferably has a securing mechanism such as a clamping device for attaching the individual reflectors in the folded position at one or both sides of the central element. In this way, space is saved, and a self-actuating deployment of the reflector can be obtained without external actuators by virtue of a pre-stress in the pivotal connections when the reflectors are folded.
The number of individual reflectors is variable, whereby, additional individual reflectors can be used, in order to form a modular system. In this way, the reflector size can be expanded and the reflector can be adapted in a simple way to specific requirements. In addition, costs are saves, since the individual reflector elements are preferably identical and the overall reflector is constructed according to a building-block principle.
Preferably, the individual reflectors are folded up like an umbrella and have an approximately cylindrical or truncated-conically shaped outer periphery in the folded state. In this way, the individual reflectors in the folded state can be stored with their longitudinal axes aligned essentially parallel to one another and/or parallel to a surface of the central element. In this way transport into orbit is made possible with a minimum space requirement.
The reflector can be mounted on a main support arm in such a way that it can be displaced on the main support arm in the folded state.
According to another aspect of the invention, a reflector or reflector element is produced for antennas for use in space, which has a heat-stable foldable surface structure, which serves as a reflector surface, the reflector element having a multiple number of ribs for supporting the surface structure and a rigid central structure, which is connected to the ribs by pivotal connections, so that the surface structure can be deployed by pivoting the ribs outwards.
Thus, the reflector element can be stowed in a very small space, and can easily be deployed. The ribs can be aligned essentially parallel to one another in the folded state and they are pivoted in the deployed state, preferably essentially radially outwards from the central structure.
The surface of the reflector is made from CFK. In this way, a high stability is obtained relative to thermal stresses and radiation pressure. The surface can be provided with an RF-effective layer, for example, a metalized Kapton foil. The surface structure is preferably subdivided into individual pre-shaped segments of part-parabolic or part-spherical shape, which can each be held by two ribs and they are arranged, circumferentially around the central part. Preferably, the ribs are connected to the surface structure by means of an elastic joint. This elastic joint can include an intermediate rib element and a slitted profile member to enable a good and easy adaptation to the curvature of the reflector.
The pivotal connections are preferably made of flexible, elastic elements, such as, coil springs or leaf-springs, which are preferably form-stable and have, in particular, a defined buckling direction. The reflector element can also have a detachable clamping device for holding the reflector element in its folded state. In this way, a deployment is possible without an actuator, due to a pre-stressing of the pivotal connections.
According to yet another aspect of the invention, a reflector is provided which comprises one or more reflector elements according to the invention as the individual reflectors as described above.
The process for deployment a reflector according to the invention comprises the steps of:
outwardly swinging a multiple number of folded individual reflectors joined to a central element, from a transport position into an operating position,
deploying the individual reflectors in the operating position so that the individual reflectors adjoin one another to collectively form the overall reflector surface.
The individual reflectors can be moved in pairs into the deployed or operating position. Preferably, the reflectors are released under pre-stress after a securing mechanism is released.
REFERENCES:
patent: 4343005 (1982-08-01), Han et al.
patent: 4562441 (1985-12-01), Beretta et al.
patent: 4769647 (1988-09-01), Herbig et al.
patent: 5198832 (1993-03-01), Higgins et al.
patent: 5966104 (1999-10-01), Massey et al.
patent: 6047928 (2000-04-01), Benilied et al.
Roth Martin
Sperber Franz
Astrium GmbH
Dinh Trinh Vo
Ladas & Parry
Le Hoang-anh
LandOfFree
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