Self-deploying radio frequency antenna

Abstract

Radiofrequency antenna (1) substantially cylindrical along an axis (A), comprising a stacked configuration having a reduced extension (e) along the axis (A) of the cylinder and a deployed configuration having an increased extension (E) along the axis (A) of the cylinder, capable of deploying spontaneously to pass from the stacked configuration to the deployed configuration, comprising at least two substantially toroidal rings (2), the large diameter of the torus defining the diameter of the cylinder, superimposed, the axes of said at least two tori merging with each other and with the axis (A) of the cylinder, and at least one elastically flexible blade (3) fixed substantially to the outer periphery of said at least two rings (2), said at least one blade (3) being shaped so as, in the deployed configuration, to extend along the cylinder along an axis parallel to or merging with the axis (A) of the cylinder and, in the stacked configuration, to fold back on itself under stress,so as to create a recall effort, allowing spontaneous deployment. Application to the spatial domain. Abstract figure: Figure 1,

Description

Title of the invention: Self-deploying radiofrequency antenna Technical field

[0001] The invention relates to the field of self-deployable radiofrequency antennas, more particularly for the space domain. Prior art

[0002] It is known to equip a satellite or a space station with a radiofrequency antenna in order to enable it to communicate with the Earth. Given the frequencies used, such a radiofrequency antenna has a longitudinal extension of the order of a few tens of centimeters in a direction substantially normal to the surface of the satellite. Also, according to one embodiment, such an antenna is advantageously folded or stacked in order to have the smallest possible extension during transport. It is then deployed once the satellite is in its orbit. Also, a radiofrequency antenna is sought that can be stacked and then deployed. Summary of the invention

[0003] For this purpose, the invention relates to a radiofrequency antenna which is substantially cylindrical along an axis, comprising a stacked configuration having a reduced extension along the axis of the cylinder and a deployed configuration having an increased extension along the axis of the cylinder, capable of deploying spontaneously to pass from the stacked configuration to the deployed configuration, comprising at least two substantially toroidal rings, the large diameter of the torus defining the diameter of the cylinder, superimposed, the axes of said at least two toroids merging with each other and with the axis of the cylinder, and at least one elastically flexible blade fixed substantially to the outer periphery of said at least two rings, said at least one blade being shaped so as, in the deployed configuration, to extend along the cylinder, along an axis parallel to or merging with the axis of the cylinder and, in the stacked configuration, to fold back on itself under stress,so as to create a recall effort, allowing spontaneous deployment.

[0004] Particular characteristics or embodiments, usable alone or in combination, are: - said at least one blade forms the radiating element of the radiofrequency antenna, - a blade, when folded in a stacked configuration, is constrained substantially continuously and is arranged inside the cylinder, - a blade has a continuous section of curved shape and concavity facing towards the inside of the cylinder, in order to ensure dynamic self-maintenance of the deployed configuration, - a blade has a discontinuous or interrupted section such that, when it is trapped between two parallel surfaces compressing it, it deforms until it reaches a flat configuration, - a blade is made in one piece from the first ring to the last ring, along the entire length of the cylinder, - a blade is made of a plurality of blade sections from the first ring to the last ring, along the entire length of the cylinder, - the radiofrequency antenna comprises a blade, - the radiofrequency antenna comprises several blades, preferably regularly distributed angularly, still preferably four blades, - a ring comprises on a first surface at least one substantially cylindrical lug with an axis substantially parallel to the axis of the cylinder and, on a second surface opposite the first surface, at least as many substantially cylindrical or preferably conical housings, with an axis substantially parallel to the axis of the cylinder, each housing being capable of receiving a lug of the immediately adjacent and facing ring, - a ring further comprises at least one part thinned in a radial direction, in order to allow elastic deformation of the ring, - a ring has, at the level of the attachment with a blade, a substantially semi-cylindrical section, substantially tangent to the cylinder from the inside and with an axis substantially perpendicular to the axis of the cylinder, so as to guide the blade when it is folded, - a ring / blade attachment includes an anti-slip means, preferably of the pinching type, - said at least two rings are made of dielectric material, preferably a plastic material, even more preferably PEEK, and said at least one blade is made of electrically conductive material, preferably a metal.

[0005] Furthermore, the invention also relates to a spacecraft comprising such a radiofrequency antenna. Brief description of the drawings

[0006] The invention will be better understood on reading the following description, given solely by way of example, and with reference to the appended figures in which:

[0007] [Fig.l] Illustrates an antenna in a first implementation of the deployed configuration,

[0008] [Fig.2] Illustrates an antenna in a second implementation of the deployed configuration,

[0009] [Fig.3] Illustrates an antenna in stacked configuration,

[0010] [Fig.4] Illustrates a single ring,

[0011] [Fig.5] Illustrates a ring and its interfaces with the blades,

[0012] [Fig.6] Illustrates the section of a ring at the interface with a deployed blade,

[0013] [Fig.7] Illustrates a folded blade,

[0014] [Fig.8] Illustrates a first implementation of the section of a blade.

[0015] [Fig.9] Illustrates a second implementation of the section of a blade. Description of the embodiments

[0016] With reference to Figures 1, 2 and 3, the invention relates to a radiofrequency antenna 1 substantially cylindrical along an axis A. This radiofrequency antenna 1 can be in at least two configurations: a stacked configuration, illustrated in [Fig.3], having a reduced extension e along the axis A of the cylinder and a deployed configuration, illustrated in Figures 1 and 2, having an increased extension E along the axis A of the cylinder. The deployed configuration is stable, as described later. On the contrary, the stacked configuration is unstable and the radiofrequency antenna 1 tends, spontaneously, to deploy to pass from the stacked configuration to the deployed configuration.

[0017] For this, the radiofrequency antenna 1 comprises at least two rings 2 of substantially toroidal shape. The large diameter of the torus defines the diameter of the cylinder. The rings 2 are superimposed, “flat”, so that the axes of the tori coincide with each other and with the axis A of the cylinder. The radiofrequency antenna 1 further comprises at least one elastically flexible blade 3. Thus, the radiofrequency antenna 1 may comprise one, two, three or more elastically flexible blades 3. This at least one blade 3 has substantially a ribbon shape. It is fixed substantially to the outer periphery of said at least two rings 2.

[0018] According to an important characteristic, said at least one blade 3 is made of an elastic material. It is shaped to have a default shape corresponding to the deployed configuration. Thus, the deployed configuration is an equilibrium configuration, a rest configuration, a default configuration, to which the antenna 1 tends to return spontaneously.

[0019] Furthermore, the elastic material used to produce said at least one blade 3 is chosen so as to enable it to stand on its own in the deployed configuration. In a particular implementation, each blade 3 is shaped to stand on its own in the deployed configuration. In another particular implementation, at least one blade 3 is shaped to stand on its own in the deployed configuration.

[0020] In the deployed configuration, said at least one blade 3 has a straight or helical shape.

[0021] In its straight form, as illustrated in [Fig.2], said at least one blade 3 extends along the cylinder along an axis parallel to the axis A of the cylinder.

[0022] In its helical shape, as illustrated in [Fig.l], said at least one blade 3 wraps around the cylinder. In this case, the axis of this helix coincides with the axis A of the cylinder.

[0023] The propeller can be either a left-hand propeller or a right-hand propeller. Advantageously, in the case of a plurality of blades 3, all the blades 3 wind in the same direction.

[0024] On the contrary, in the stacked configuration, said at least one blade 3 is folded back on itself. Said at least one blade 3 being elastic, this folding is carried out in a constrained manner, and creates a return force. Also, the stacked configuration is unstable and under the effect of said return force, the radiofrequency antenna 1, when it is left free, spontaneously deploys to join the deployed configuration.

[0025] Also, the radiofrequency antenna 1 advantageously comprises a means for holding it in the stacked position. Such a means may, for example, comprise an axial rod along the axis A securing one end ring to the other end ring. This means may be released when deployment is desired. The release may be achieved by any actuator capable of releasing the holding means.

[0026] In one example, a blade 3 has a width of between 2mm and 100mm. In another example, which can be combined with the previous example, a blade 3 has a thickness of between 0.05mm and 1mm.

[0027] In a particular implementation, the radiofrequency antenna 1 as described advantageously makes it possible to obtain a stacking ratio E / e at least equal to 2. For example, for a length of 20 cm in stacked configuration, it is possible to obtain at least a length of 40 cm in deployed configuration.

[0028] According to another characteristic, said at least one blade 3 advantageously forms the radiating element of the radiofrequency antenna 1. For this, said at least one blade 3 is made of an electrically conductive material merging with the material providing elasticity. Alternatively, said at least one blade 3 comprises a first material ensuring elasticity, associated, for example by covering, with a second material ensuring electrical conduction.

[0029] In addition, the blades 3 are advantageously electrically connected to each other, advantageously by a short-circuit connection, for example at the distal end. At least one of the blades 3 is also advantageously connected, typically by a coaxial cable, to a transmitting and / or receiving radiofrequency device, preferably at the proximal and / or distal end.

[0030] It has been seen that said at least one blade 3 is elastically flexible. Also when it is deformed to be folded so that the radiofrequency antenna 1 is in a stacked configuration, a blade 3 undergoes a stress. As seen previously, the release of this stress allows the spontaneous deployment of the antenna 1.

[0031] According to another characteristic, when a blade 3 is folded, said stress is substantially continuous. This is made possible by winding the blade 3 on itself with a radius of curvature that is substantially constant or at least substantially continuously varied. [Fig. 7] illustrates the detail of a folded blade. This folding is carried out by flexible winding, without abrupt folding, with a generally smallest possible curvature, such as spontaneously obtained by bringing two successive rings 2 together. The blade 3 is still arranged inside the cylinder, as illustrated in [Fig. 7]. During folding, it may be necessary to help a blade 3 to fold by guiding it towards the inside of the cylinder. All the sections of blade 3 between two rings 2 are folded in an identical manner. This ensures axial symmetry of the forces during deployment.

[0032] It has been seen that a blade 3 is elastic and shaped so that its default shape corresponds to the deployed configuration. Also, the elasticity of said at least one blade 3 guarantees, in addition to spontaneous deployment, maintenance in the deployed configuration and this in a dynamic manner. Thus, if a stress deforms the radiofrequency antenna 1 and moves it away from the deployed configuration, the elasticity of said at least one blade 3 tends to bring it back there. This is true for any stress: axial, bending, torsion, etc. Also, this elasticity achieves self-locking in the deployed configuration.

[0033] The flexibility of a blade 3 is also accompanied by damping. Also, upon returning to the deployed configuration following a deforming stress, the oscillations are naturally damped. This is particularly advantageous for spatial use.

[0034] In order to increase the elasticity, which ensures both spontaneous deployment and dynamic self-locking, according to another characteristic, more particularly illustrated in [Fig.8], said at least one blade 3 has a continuous transverse section S of curved shape. Advantageously, the concavity thus created is turned towards the inside of the cylinder. However, in a particular implementation, the concavity is turned towards the outside of the cylinder. Advantageously again, the section profile S is symmetrical. Thus the stiffness of said at least one blade 3 is increased and with them the deployment and / or self-locking return forces.

[0035] In one example, the radius of curvature Ro of the section S of blade 3 is between 1mm and 100mm.

[0036] In another particular implementation, illustrated in [Fig.9], said at least one blade 3 has a discontinuous or interrupted section S such that, when it is trapped between two parallel surfaces compressing it, it deforms until it reaches a flat configuration.

[0037] In the example of [Fig.9], the section S of the blade 3 has a shape of vase consisting of three pieces ah a2 and a3, with a bottom a2 and two walls ai and a3. However, the section S of the blade 3 may comprise one or more pieces which may be straight or curved. For example, the section S of the blade 3 may have a V shape consisting of two pieces.

[0038] According to another characteristic, a blade 3 is made in one piece from the first ring to the last ring, over the entire length of the cylinder.

[0039] However, in a particular implementation, a blade 3 comprises a plurality of blade sections from the first ring to the last ring, over the entire length of the cylinder. For example, a blade 3 may comprise a blade section between each adjacent pair of rings 2. In this particular implementation, the blade sections of a blade 3 are electrically connected to each other so as to ensure electrical continuity from the first ring to the last ring. This arrangement is advantageous when it is desired to produce a large radiofrequency antenna 1, since two or more blade sections may be used to form a blade 3.

[0040] A radiofrequency antenna 1 has been described previously, the number of blades 3 of which is at least equal to one. It is in fact possible to produce such a radiofrequency antenna 1 with a single blade 3.

[0041] It is still possible to increase the number of blades 3. Thus the figures illustrate a preferred number of blades 3 of four. Thus, subject to radiofrequency compatibility, there is nothing to prevent, whether to increase the deployment stiffness, or to increase the surface area and / or the volume / weight of blades, an increase in this number up to ten, or even twenty blades.

[0042] According to another characteristic, in the case of a plurality of blades 3, these are advantageously regularly distributed angularly. Such a characteristic makes it possible to obtain a symmetry of the forces, guaranteeing an axially balanced deployment.

[0043] When, in the deployed configuration, a blade 3 has a helical shape, its helix pitch is, for example, between 10 mm / revolution and 5 m / revolution. In the case of a plurality of blades 3, all the blades 3 advantageously have the same helix pitch.

[0044] The helix pitch of a blade 3 can be further modified to increase or decrease the surface area of ​​the blade 3.

[0045] Depending on the number of blades 3 and the radiofrequency characteristics that one wishes to give to the radiofrequency antenna 1, it may be necessary to modify the helix pitch.

[0046] A radiofrequency antenna 1 comprises any number of rings 2. This number is at least equal to two and is reasonably limited to twenty. The two end rings may be slightly different. This is due, on the one hand, to the fact that they do not have a neighboring ring on one side and therefore do not have to include the interface elements with a neighboring ring 2. This may also be due, on the other hand, to the fact that they possibly provide functions for fixing the antenna 1 to a support (proximal end) or to a component embedded on the end of the antenna 1 (distal end). The figures illustrate, for example, a radiofrequency antenna 1 comprising nine rings.

[0047] The diameter of a ring 2, which substantially determines the diameter of the cylinder, is between 20mm and 500mm.

[0048] The objective being to reduce to a minimum the height e along the axis A of the radiofrequency antenna 1 in stacked configuration, according to another characteristic, in stacked configuration, two immediately adjacent rings 2 are in contact. This is more particularly visible in [Fig.3].

[0049] In the deployed configuration, the distance between the rings 2 is determined by the attachment point on said at least one blade 3.

[0050] The length of the blade portions 3 connecting two neighboring rings 2 is preferably identical for reasons of symmetry of the radiofrequency antenna 1 and deployment forces.

[0051] In the deployed configuration, the distance between two rings 2 is, for example, between 10 mm and 500 mm. This distance is advantageously constant along the entire axis A of the radiofrequency antenna 1.

[0052] According to another characteristic, more particularly visible in Figures 4 and 5, said at least one ring 2 is shaped to assemble with its neighbor, in a stacked configuration. Thus, a ring 2 comprises, on a first surface, facing another ring, at least one lug 4 extending towards said facing ring. This lug 4 is substantially cylindrical with an axis substantially parallel to the axis A of the cylinder.

[0053] The number of lugs 4 may be any. Advantageously, in the case of a plurality of lugs 4, these are angularly regularly distributed around the periphery of the ring 2. For reasons of symmetry, this regular angular distribution advantageously follows that of the blades 3 with a number of lugs 4 that is a multiple or sub-multiple of the number of blades 3.

[0054] Similarly, on a second surface opposite the first surface, facing another ring, the ring 2 comprises as many housings 5 ​​as the facing ring comprises lugs 4. Each housing 5 is angularly arranged so as to be able to accommodate a lug 4. This implies an angular distribution similar to that of the lugs 4, combined with a slight rotation induced during the folding of the blade portion(s) 3 between the two rings 2, due to their helical shape. Also, a housing 5 has a shape complementary to the shape of a homologous lug 4, either substantially cylindrical or preferably conical, with a truncated cone opening, at least at the level of the inlet opening of the housing 5, with an axis substantially parallel to the axis A of the cylinder. Each housing 5 is capable of accommodating a lug 4 of the immediately adjacent and facing ring 2.

[0055] Alternatively, the same surface of a ring 2 may simultaneously comprise at least one lug 4 and at least one housing 5, the neighboring ring additionally comprising a homologous housing 5 for each lug 4 and a homologous lug 4 for each housing 5.

[0056] The preceding characteristic makes it possible to closely secure the rings 2 when the radiofrequency antenna 1 is in a stacked configuration and thus to offer it better mechanical resistance, the lug 4 / housing 5 assemblies making it possible to absorb the forces undergone by the antenna 1.

[0057] According to another characteristic, more particularly visible in Figures 4 and 5, a ring 2 also comprises at least one thinned portion 7. Such thinning 7 is for example achieved by a light pierced in a radial direction. This thinning advantageously makes it possible to reduce the tangential and flexural stiffness of the ring 2, in order to allow elastic deformation of the ring 2. This allows the ring 2 to be more tolerant to the forces undergone by the antenna 1 by offering the possibility of deforming to absorb said forces.

[0058] To achieve the same effect, this thinning 7 can also advantageously be replaced or supplemented by a sloping section 9, relative to the plane of the torus. Such a sloping section 9, in that it has a double angulation, allows deformation, in a direction tangential to the cylinder contained in the plane of the torus.

[0059] A combination of a thinning 7 and a sloping section 9 at the same location advantageously forms a parallelogram allowing parallel deformation.

[0060] A blade 3 is fixed to a ring 2 by any means: riveting, welding, gluing, molding, overmolding, etc. According to the embodiment illustrated by the figures, one possible means is a clip 8, enclosing the blade 3, pressed against the rest of the ring 2, for example by screwing or by pinching.

[0061] According to another characteristic, more particularly visible in figures 6 and 7, at the level of its fixing with a blade 3, a ring 2 has a section 6 substantially semi-cylindrical. Said half-cylinder is substantially tangent to the cylinder by the interior of this cylinder, and oriented substantially perpendicular to the axis A of the cylinder. As more particularly illustrated in [Fig.7], this section shape makes it possible to guide the blade 3 during its folding and to accompany it in the stacked configuration.

[0062] It was observed, during deployment tests, a slight possibility of sliding of the blades 3 relative to the rings 2 at the level of their mutual fixing. Also, according to another characteristic, a ring 2 / blade 3 fixing advantageously comprises an anti-slip means. In one example, the anti-slip means (not shown) is of the pinching type, arranged along an axis normal to the mid-plane of a blade 3, in order to form a resistance to shear in said plane.

[0063] In another example, the anti-slip means (not shown) is of the finger and hole type, arranged along an axis normal to the mid-plane of a blade 3, in order to form a resistance to shearing in said plane. Such a finger may be a screw, a rivet or a pin passing through the blade 3 or made of material with the latter and engaging in a corresponding hole provided in the ring 2.

[0064] In order for this radiofrequency antenna 1, capable of spontaneous deployment, to be able to operate in radiofrequency, certain points must be respected. The rings 2 should be made of a dielectric material, preferably a plastic material, even more preferably PEEK. Similarly, said at least one blade 3 should be made of an electrically conductive material, preferably a metal.

[0065] Such a radiofrequency antenna 1 is particularly suitable for use on a spacecraft, such as an orbital station or a satellite. The radiofrequency antenna 1 can then be stored, in a stacked configuration, throughout the transport: launch, placing in orbit, etc. Once the spacecraft is in place, the radiofrequency antenna 1 can be released. It then spontaneously returns, under the effect of the restoring forces created within said at least one blade 3 during folding, to the deployed configuration. This also deploys said at least one blade 3 and therefore the radiating element of the radiofrequency antenna 1, thus placing the radiofrequency antenna 1 in operational configuration.

[0066] The invention also relates to a spacecraft comprising such a radiofrequency antenna 1.

[0067] The invention has been illustrated and described in detail in the drawings and the preceding description. This should be considered as illustrative and given by way of example and not as limiting the invention to this description alone. Numerous alternative embodiments are possible. List of reference signs

[0068] 1: radiofrequency antenna, 2: ring, 3: blade, 4: spur, 5: housing, 6: semi-cylindrical section, 7: thinning, 8: rider, 9: slope.

Claims

Claims

1. Radiofrequency antenna (1) substantially cylindrical along an axis (A) with at least one radiating element, comprising a stacked configuration having a reduced extension (e) along the axis (A) of the cylinder and a deployed configuration having an increased extension (E) along the axis (A) of the cylinder, said antenna being capable of deploying spontaneously to pass from the stacked configuration to the deployed configuration, and comprising at least two substantially toroidal rings (2), the large diameter of the torus defining the diameter of the cylinder, superimposed, the axes of said at least two toroidal rings each merging with the axis (A) of the cylinder, and two adjacent toroidal rings being in contact in the stacked position of the antenna as well as at least one elastically flexible blade (3) fixed substantially to the outer periphery of said at least two rings (2), characterized in that said at least one blade (3) is shaped to,in the deployed configuration of the antenna, extend along the cylinder along an axis parallel to or coincident with the axis (A) of the cylinder and, in the stacked configuration of the antenna, fold back on itself under stress, so as to create a return force, allowing spontaneous deployment and in that said at least one blade (3) has a section S with a break in the curve comprising one or more curved pieces or several rectilinear portions which are not collinear with each other.,

2. Radiofrequency antenna (1), according to the preceding claim, wherein said at least one blade (3) forms the radiating element of the radiofrequency antenna (1).

3. Radiofrequency antenna (1), according to any one of the preceding claims, wherein said at least one blade (3), when folded in a stacked configuration, is constrained substantially continuously and is arranged inside the cylinder.

4. Radiofrequency antenna (1), according to any one of the preceding claims, wherein said at least one blade (3) has a continuous section (S) of curved shape and concavity facing towards the inside of the cylinder, in order to ensure dynamic self-maintenance of the deployed configuration.

5. Radiofrequency antenna (1), according to any one of the preceding claims, wherein said at least one blade (3) is made in one piece from the first ring (2) to the last ring (2), along the entire length of the cylinder.

6. Radiofrequency antenna (1), according to any one of claims 1 to 4, wherein said at least one blade (3) is made of a plurality of blade sections from the first ring (2) to the last ring (2), over the entire length of the cylinder.

7. Radiofrequency antenna (1), according to any one of the preceding claims, comprising a blade (3).

8. Radiofrequency antenna (1), according to any one of the preceding claims, comprising several blades (3), preferably regularly distributed angularly, still preferably four blades (3).

9. Radiofrequency antenna (1), according to any one of the preceding claims, where at least one of the rings (2) comprises on a first surface at least one substantially cylindrical lug (4) with an axis substantially parallel to the axis (A) of the cylinder and, on a second surface opposite the first surface, at least as many substantially cylindrical or preferably conical housings (5), with an axis substantially parallel to the axis (A) of the cylinder, each housing (5) being capable of receiving a lug (4) of the immediately adjacent and facing ring (2).

10. Radiofrequency antenna (1), according to any one of the preceding claims, wherein at least one of the rings (2) further comprises at least one part thinned in a radial direction, in order to allow elastic deformation of the ring (2).

11. Radiofrequency antenna (1), according to any one of the preceding claims, where at least one of the rings (2) has, at the level of the attachment with a blade (3), a substantially semi-cylindrical section (6), substantially tangent to the cylinder from the inside and with an axis substantially perpendicular to the axis (A) of the cylinder, so as to guide the blade (3) when it is folded.

12. Radiofrequency antenna (1), according to any one of the preceding claims, wherein a ring (2) / blade (3) fixing comprises an anti-slip means, preferably of the pinching type.

13. Radiofrequency antenna (1), according to any one of the preceding claims, wherein said at least two rings (2) are made of dielectric material, preferably a material

14. plastic, preferably PEEK, and said at least one blade (3) is made of electrically conductive material, preferably a metal. Spacecraft characterized in that it comprises a radiofrequency antenna (1) according to any one of the preceding claims.

Images