Antenna reflector with adjustable radiant surface

Abstract

The present invention relates to an antenna reflector having adjustable radiating surface which is made up of a sandwich panel rear structure (1) made of composite material, a monolithic reflective radiating surface (2) formed by a sheet made of composite material and a set of bars (3) uniformly distributed between the rear structure (1) and the radiating surface (2), which support the radiating surface (2) in multiple contact areas with respect to the rear structure (1). The bars (3) are longitudinally movable to control the distance of each contact area of the radiating surface (2) with respect to the rear structure (1) to achieve a fine adjustment of the position of the contact areas of the radiating surface (2) of the reflector to achieve uniform curvature across the entire radiating surface with micrometric accuracy in a controlled manner.

Description

OBJECT OF THE INVENTION

[0001] The present invention relates to an antenna reflector with adjustable radiating surface designed such that it allows fine geometric adjustment of the reflector surface at multiple points to achieve the desired surface with micrometric accuracy in a controlled manner.BACKGROUND OF THE INVENTION

[0002] In order to guarantee scientific progress and improved performance in telecommunications services, larger and more accurate antenna-reflector systems are currently required. Specifically, larger and more accurate reflectors allow the efficiency of telecommunications systems to be improved, as well as increase the range and quality of measurements from scientific instruments used to study the Earth or the universe.

[0003] As for large size reflectors, numerous devices have been manufactured and put into orbit. These are manufactured meeting strict surface quality requirements demanded at the time, reaching accuracies of up to 200 microns. However, future missions that are being developed will require even greater accuracy to increase the gain of future space antennas, which poses a challenge and an opportunity simultaneously. Currently, the existence of technologies for the manufacture of these reflectors with the required tolerances is unknown.

[0004] In 2009, the European Space Agency launched the Planck satellite into orbit to study the cosmic microwave background within the scientific program Horizon 2000. The technology used on the Planck satellite, with high resolution and sensitivity, was a major advance compared to previous missions such as NASA's WMAP, which helped generate knowledge about the primordial universe and the cosmic structure. The satellite was equipped with two instruments, LFI (Low Frequency Instrument) and HFI (High Frequency Instrument), which together covered a very wide range of the frequency spectrum of almost 830 GHz. In addition, the satellite manufactured by Astrium had two reflectors, a primary one and a secondary one, both composed of a honeycomb sandwich panel core made of carbon fiber covered by a layer of carbon fiber, having 1.5 m and 1 m in diameter respectively. A surface error range of 7.5 - 50 microns was established for the manufacture of the reflectors.

[0005] However, during the testing and operation of the Planck satellite, periodic mechanical deformations were detected on the surface of the reflectors. On the one hand, due to the differences in mechanical properties between the adhesion of the sandwich with the layer, the carbon fiber membrane on the honeycomb cells turned slightly concave. A second phenomenon called the print-through effect, is added to this phenomenon, called the dimpling effect, wherein in the print-through effect the walls of the honeycomb of the sandwich panel produced a hexagonal pattern on the reflective surface due to the thermoelastic properties of the materials. Both phenomena generated deformations that reduced the quality of the reflected wave.

[0006] Likewise, the EarthCARE (Earth Clouds, Aerosols, and Radiation Explorer) mission of the Living Planet program, the objective of which is to improve knowledge about the interaction between clouds, aerosols and radiation to generate future models that are capable of exactly predicting climate changes, launched a satellite with 4 measuring instruments into orbit. One of these instruments, called Cloud Profiling Radar, was equipped with a deployable reflector having 2.5 m in diameter.

[0007] These types of reflectors are required to be able to obtain scientific data about the Earth and its atmospheric conditions exactly. Specifically, a large aperture reflector was required for this application to guarantee the correct Doppler measurement and adequate sensitivity. It is clear that the increase in interest in analyzing climatological phenomena and the need to monitor and generate models that allow future changes in the Earth's climate to be predicted will require the launch of measurement satellites into orbit, which, in turn, will require large reflectors with high accuracy and stability to guarantee the scientific quality of the studies, and in this way justify the great economic cost they entail.DESCRIPTION OF THE INVENTION

[0008] The antenna reflector having adjustable radiating surface proposed by the present invention allows fine geometric adjustment of the radiating surface of the reflector at multiple points with an accuracy of the order of 0.001 mm after the reflector assembly has been manufactured and thermally stabilized.

[0009] The reflector is made up of a sandwich panel rear structure made of composite material, a monolithic radiating surface formed by a sheet made of composite material separated from the rear structure and a set of bars uniformly distributed between the rear structure and the radiating surface, which, by one of the ends thereof, supports the radiating surface in multiple contact areas with respect to the rear structure.

[0010] Each of said bars in contact with the radiating surface is movable perpendicularly with respect to the rear structure, so the distance of each contact area of the radiating surface with respect to the rear structure can be controlled, in order to achieve the desired uniform curvature across the entire radiating surface with a surface average that can be of the order of one micron.

[0011] Each of the bars is equipped with an outer end and an inner end, wherein the inner end supports the radiating surface in multiple contact areas with respect to the rear structure.

[0012] The bars move longitudinally, preferably by means of corresponding actuators, which can be mechanical or other types, which are linked to the rear structure at multiple points and which define in the movement thereof the extension or retraction of each bar depending on the position to be reached for each contact area of the radiating surface in order to achieve a uniform curvature of said radiating surface with a minimum dimensional error with respect to the desired surface.

[0013] One possible application provides for the radiating surface to be adjusted on the ground before launch or operation, then it is measured using laser trackers, and once the shape of the radiating surface is adjusted to the required measurement, the bars are fixed in position by means of joining means, such as an adhesive or similar, the actuators are then removed, and the excess sections of the bars are trimmed and flushed with the subsequent structure. This makes it possible to achieve a lighter, more stable and accurate structure than in other embodiments.

[0014] In another possible application, the reflector is launched into space with the actuators, and these are controlled remotely, allowing the radiating surface of the reflector to be adjusted once same is in orbit or in operation.

[0015] The rear structure and the rest of the elements behind the radiating surface are designed with dimensions such that they are invisible to the magnetic field, so the magnetic field is not affected by any interaction.

[0016] Additionally, the reflector can incorporate reinforcements in the rear structure that give it greater rigidity and stability.

[0017] Moreover, the reflector can have a film or layer of paint or surface finish on the reflective surface that reduces electrical losses in the normal operation of its radiating surface.DESCRIPTION OF THE DRAWINGS

[0018] As a complement to the description provided herein, and for the purpose of helping to make the features of the invention more readily understandable, in accordance with a preferred practical exemplary embodiment thereof, said description is accompanied by a set of drawings constituting an integral part of the same, wherein by way of illustration and not limitation, the following has been represented: Figure 1 shows a lateral view of the antenna reflector with the actuators acting on the bars which move to adjust the position of the different contact areas of the radiating surface. Figure 2 shows a rear perspective view of the antenna in which the reinforcements of the rear structure can be seen. Figure 3 shows a lateral view of the reflector in which the reflector is observed after disassembling the actuators and trimming the excess sections of the bars in the position in which said bars establish the optimal position of each contact area of the radiating surface with respect to the rear structure. PREFERRED EMBODIMENT OF THE INVENTION

[0019] Next, in view of the figures, a preferred embodiment of the antenna reflector having adjustable radiating surface that constitutes the object of this invention is described.

[0020] As figure 1 shows, the antenna reflector comprises a composite sandwich panel rear structure (1), a reflective monolithic radiating surface (2) formed by a sheet made of composite material separated from the rear structure (1) and a set of bars (3) uniformly distributed between the rear structure (1) and the radiating surface (2), wherein each of the bars (3) supports the radiating surface (2) by one of the ends thereof in multiple areas of contact with respect to the rear structure (1).

[0021] Figure 1 shows that the bars (3) are longitudinally movable by the action of actuators (4) linked to the rear structure (1) to control the distance of each contact area of the radiating surface (2) with respect to the rear structure (1) in order to achieve the required shape of the entire radiating surface (2) within micrometric tolerances.

[0022] This same figure 1 shows that, coupled to one of the ends of the bars (3), plates (5) can be located forming the support surface of the different areas of the radiating surface (2), on which the bars (3) act in the extension or retraction movement thereof depending on the position of the radiating surface (2) to be reached for each of its areas in relation to the adjacent areas in order to minimize the geometric error of the entire radiating surface (2).

[0023] The reflector with the actuators (4) thus mounted is ready to be launched into space when a remote regulation of the position of the radiating surface is to be performed.

[0024] Alternatively, figure 3 shows the reflector in which the actuators (4) have been disassembled, the bars (3) have been trimmed by the excess inner sections thereof, as can be seen in the detail, and said bars (3) have been fixed to the radiating surface (2) and to the rear structure (1) in the optimal extension position by means of joining means such as an adhesive or similar. The reflector thus released from the actuators (4) is ready for launch into space.

[0025] The figures, especially Figure 2, show that the reflector comprises reinforcements (7) on the rear structure (1) that give it greater rigidity and stability.

[0026] Additionally, it has been planned that the reflector incorporates a layer (6) of film or paint or surface finish having minimum tolerance on the radiating surface (2), as can be seen in the detail of Figure 3, which reduces electrical losses in the normal operation of its radiant surface (2).

Claims

1. An antenna reflector having adjustable radiating surface comprising a sandwich panel rear structure (1) made of composite material and a monolithic radiating surface (2) formed by a sheet made of composite material, characterized in that, the radiating surface (2) is separated from the rear structure (1) and the reflector additionally comprises: a set of bars (3) uniformly distributed between the rear structure (1) and the radiating surface (2), wherein each of the bars (3) is equipped with an outer end and an inner end, wherein the outer end supports the radiating surface (2) in multiple contact areas with respect to the rear structure (1), wherein the bars (3) are longitudinally movable to control the distance of each contact area of the radiating surface (2) with respect to the rear structure (1) and achieve the required shape of the entire radiating surface (2) within micrometric tolerances, and means for connecting the bars (3) to the radiating surface (2) and to the rear structure (1) that fix the longitudinal extension of each of the bars (3) and therefore the position of each contact area of the radiant surface (2) with respect to the adjacent areas of the rear structure (1).

2. The reflector of claim 1 additionally comprising actuators (4) linked to the rear structure (1) that act on each of the bars (3) imprinting them with a longitudinal movement of extension or retraction to control the position of each contact area of the radiating surface (2).

3. The reflector of claim 1 additionally comprising plates (5) located between the contact areas of the radiating surface (2) and the outer end of the bars (3).

4. The reflector of claim 1 comprising reinforcements (7) on the rear structure (1) that give greater rigidity and stability to the same.

5. The reflector of claim 1 comprising a layer (6) of film or paint or surface finish having minimum tolerance on the radiating surface (2) that reduces electrical losses in the normal operation of the radiating surface (2).

6. The reflector of claim 1 wherein the joining means are adhesive.

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