JP4876941B2 - Deployable antenna - Google Patents

Description

  The present invention relates to a deployable antenna mounted on a space device such as an artificial satellite or a spacecraft.

  As space antennas are used in space, a large-sized object having a larger aperture diameter that can be used for mobile terminals for satellite communication and high-accuracy radio wave observation is desired. On the other hand, since such an antenna has a limited launcher storage space when launched, it is housed in a rocket fairing with a diameter of about 2 m to 4 m in a small folded state, and the antenna is deployed on the orbit after launch, Construct a reflecting mirror surface.

  As an example of such a deployable antenna, conventionally, a deployable frame truss structure is used in which six beams are arranged radially and can be folded or deployed with the center as a pivot point. Is known (see, for example, Patent Document 1). In this deployable antenna, a mesh mirror surface is stretched on an extension mast constituting a beam, and tension is applied to a cable network that forms a mirror surface shape of the mesh mirror surface.

Japanese Patent Laying-Open No. 2006-80578 (FIG. 1)

  In a conventional deployable antenna, an extension mast (beam) that supports a cable network is composed of a plurality of deployment ribs and a deployment hinge. At this time, the number of hinge points of the unfolding hinge is as large as several hundreds. When deploying an antenna on an orbit, a failure of the deployment mechanism has a fatal effect on the formation of the reflecting mirror surface. In the deployable antenna, it is essential that all the deployable hinges are unfolded. Therefore, if the number of unfolded hinge points becomes enormous, the failure probability increases.

  In addition, the entanglement of the cable network when deploying the antenna has a fatal effect on the formation of the reflecting mirror surface. In order to prevent this entanglement, conventionally, a mirror mesh and an anti-entanglement film are arranged opposite to each other to form a closed space, in which a hard part such as a cable network node or cable bundling part does not enter. Was. However, when the number of the deployment hinge points becomes enormous, there is a problem that the possibility that the cable and the mirror mesh are entangled with the deployment rib and the deployment hinge in a complicated manner increases.

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to obtain a deployable antenna that reduces the number of hinge points and improves deployment reliability in a beam supporting a cable network. And

The deployable antenna according to the present invention is deployed from a metal mesh that constitutes a radio wave reflection surface of the antenna, a cable that retains the shape, the metal mesh and the cable in a folded state, and after deployment, the metal mesh and the cable network. A deployment antenna having a deployment mast that is radially arranged to hold the deployment mast, a deployment hinge that deploys the deployment mast, and a center hub that holds the deployment mast. The cable is bundled at a plurality of node points. The cable network is composed of two sub-cable networks of a front cable network and a rear cable network that are arranged to face each other with the deployment mast interposed therebetween, and the two sub-cable networks Each node point of A number of tie cables are bundled in a direction to pierce the radio wave reflecting surface, and some nodes located on the inner peripheral side of the cable network are held and fixed to the center hub, and are located on the outer peripheral side of the cable network. The node of each part is held and fixed to a support bar provided at the tip of the unfolded mast, and the unfolded mast is a single shaft having a 180 degree of freedom of rotation so that it can be bent in two to three stages. together are composed of ribs plurality of stages connected to each other by expansion hinge constituted by the rotation mechanism, the deployment mast is accommodated bent to fold successively inward from the tip ribs prior to deployment, the track Above, it is comprised so that an electromagnetic wave reflective surface may be formed by expand | deploying from a storage state.

  According to the present invention, the number of hinge points constituting the deployment mast is drastically reduced, and the possibility of failure is greatly reduced. Therefore, there is an effect that the reliability is greatly improved.

  Further, since the deployment mast is a simple and smooth mechanism in which two to three ribs are combined, there is an effect that the possibility that the deployment hinge, the deployment rib, the cable, and the mesh are entangled is reduced.

  Further, by covering the periphery of the deployment hinge with a film-like member, there is an effect that the possibility that the deployment hinge, the rib, the cable, and the mesh are entangled is significantly reduced.

Embodiment 1 FIG.
The deployable antenna according to the first embodiment of the present invention has a deployable hinge that connects between a deployable rib and a deployable rib that can bend the metal mesh and the beam supporting the cable network constituting the antenna reflector in two or three stages. By constructing with the developed mast, it is possible to obtain a deployable antenna that can be folded compactly during storage and can be easily deployed on the track.

Embodiment 1 according to the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing an example of a deployable antenna according to the first embodiment. 2A and 2B are diagrams showing the structure of the deployment mast of the deployment antenna. FIG. 2A is a sectional view showing the structure of the deployment mast, and FIG. 2B is a partial detail view showing the configuration of the deployment hinge in the deployment mast. It is.

  In the figure, the deployable antenna includes a metal mesh 1, a cable 2, a center hub 3, a deployable mast 4, a deployable hinge 5, a sub-reflecting mirror 10, and a feeding horn 12. The center hub 3 has a cylindrical shape, and the center hub 3 is fixed to a satellite structure (not shown). The root portion of the deployment mast 4 is rotatably supported by the deployment hinge 5, and the deployment hinge 5 is fixed to the center hub 3. As a result, the deployment mast 4 is held by the center hub 3. Six deployment masts 4 are arranged radially with the center hub 3 as the center.

  The cable 2 is bundled at a plurality of node points and stretched in a mesh shape so as to face the reflecting mirror surface of the deployable antenna, thereby forming a hexagonal cable network as a whole. The cable network is composed of two sub-cable networks, a front cable network 201 and a rear cable network 202, which are arranged to face each other with the deployment mast 4 interposed therebetween. In the front cable network 201, the cable 2 is stretched along the reflecting mirror surface of the deployable antenna, and tension is applied to each cable. In the rear cable network 202, the cable 2 is stretched so as to form a curved surface having a concave surface opposite to the front cable network 201, and tension is applied to each cable. Node points of the two sub-cable networks are bundled in a direction to pierce the reflecting mirror surface of the deployable antenna by a plurality of tie cables 203, and tension is applied to each cable. Some nodes located on the inner periphery side of the cable network are held and fixed to the center hub 3. In addition, some nodes located on the outer peripheral side of the cable network are each held and fixed to a support bar 205 provided at the tip of the deployment mast 4. Thus, the deployment mast 4 functions as a beam that supports the cable network.

  Some nodes of the metal mesh 1 are bound to the cable 2 and held by the front cable network 201. Further, the back cable network 202 holds an entanglement prevention film (not shown), and some nodes thereof are bound to the cable 2. Thereby, the metal mesh 1 forms a curved surface close to an ideal paraboloid, and this curved surface functions as a reflecting mirror surface (reflector) of the deployable antenna. The sub-reflecting mirror 10 and the feeding horn 12 are held by the center hub 3. The sub-reflecting mirror 10 is arranged in the center of the deployable antenna as viewed from the antenna reflecting mirror surface so as to face the root of the deployable mast 4 disposed radially. The power feeding horn 12 is arranged at the center of the center hub 3 so that the opening of the horn protrudes from the end face of the center hub 3.

  The deployment mast 4 includes a plurality of (two to four) deployment ribs 20 and a deployment hinge 21 that rotatably supports the deployment ribs 20. Adjacent deployment ribs 20 are connected to each other by a deployment hinge 21. In the example of FIGS. 1 and 2, three deployment ribs 20 are connected by a deployment hinge 21 to form one deployment mast 4. Thereby, the unfolding mast 4 can be configured with a simple structure. It should be noted that the deployment mast 4 is preferably configured in two to four stages depending on the size of the antenna. If the diameter is about 10 m, it is preferable that the size of the single development rib 20 is about 2 to 4 m, and the rib is composed of three stages. The development rib 20 is formed of a thin cylindrical pipe formed of, for example, CFRP (carbon fiber reinforced plastics). The cylindrical pipe is formed by laminating a plurality of layers by intersecting carbon fibers in a 60 ° orientation and containing a resin. At this time, the thickness of the cylindrical pipe may be about 1 mm. It is desirable that the deployment mast 4 is constructed so that the pipe diameter gradually decreases from the deployment rib 20 at the base portion to the deployment rib 20 at the tip portion. Further, when the unfolded mast 4 is folded and stored, each unfolded rib 20 is preferably constituted by a straight pipe so as to increase the storage efficiency.

  As shown in FIG. 2 (b), the unfolding hinge 21 and unfolding hinge 5 are constituted by a rotation mechanism having a uniaxial rotational degree of freedom. A torquer 23 is provided on the deployment hinge 21 and the deployment hinge 5. For the torquer 23, for example, a coil spring that generates rotational torque is used. In this way, it is possible to apply a rotational torque for causing the adjacent development ribs 20 to rotate relative to each other and causing the development ribs 20 to be deployed. Needless to say, a direct drive motor may be used as the ToruCa. The periphery of the deployment hinge 21 and the deployment hinge 5 is protected by being surrounded by the mesh film 7. As a result, the possibility that the cable 2 is entangled with the deployment hinge 21 and the deployment hinge 5 is greatly reduced.

  FIG. 3 is a diagram showing a deployment operation of a deployment antenna in which a deployment mast is configured by a three-stage deployment rib 20. FIG. 3A is a diagram showing a storage state, FIG. 3B is a diagram showing a state in the middle of deployment, and FIG. 3C is a diagram showing a state of being fully deployed.

  The deployable antenna is mounted in the launcher fairing together with the satellite body mounted in the retracted state. At this time, the development rib 20 in the middle part (middle stage) is rotated and folded in the direction toward the center of the antenna with respect to the development rib 20 in the root part (final stage). Further, the deployment rib 20 at the tip (first stage) is further rotated and folded in the direction toward the center of the antenna with respect to the deployment rib 20 at the base. As a result, the unfolded rib 20 at the tip is rotated 360 ° with respect to the unfolded rib 20 at the base portion and folded so as to be wound around the unfolded rib 20 at the intermediate portion. It is folded in a state rotated by 180 ° with respect to the development rib 20 at the root portion.

  After launching the launcher, the main body of the satellite is released from the launcher into outer space and put into a desired orbit. Thereafter, the unfolding hinge 5 and the unfolding hinge 21 give the unfolding torque to the unfolding rib 20 to unfold the unfolding mast 4, and the unfolding antenna reflector is in a half-open state. In this case, the development rib 20 at the tip portion is developed to a state rotated 90 ° with respect to the development rib 20 at the middle portion, and the development rib 20 at the middle portion is rotated 90 ° with respect to the development rib 20 at the root portion. Expand to state.

  Subsequently, the unfolding hinge 5 and the unfolding hinge 21 impart unfolding torque to the unfolding rib 20 to unfold the unfolding mast 4, and the unfolding antenna reflector is unfolded to a large diameter. In this case, the deploying rib 20 at the distal end is expanded to a state rotated 180 ° with respect to the deploying rib 20 at the intermediate portion, and the deploying rib 20 at the intermediate portion is rotated 180 ° with respect to the deploying rib 20 at the root portion. Expand to state. Finally, the unfolding operation is completed when the unfolding rib 20 at the distal end rotates approximately 360 ° with respect to the unfolding rib 20 at the base. At this time, in accordance with the deployment of the deployment mast 4, the deployment ribs 20 are released by the deployment hinges in the order in which the tension is applied to the cable 2. Needless to say, the torque of the unfolding hinge 21 is appropriately adjusted so that the unfolding ribs 20 of the six unfolding masts 4 are unfolded sequentially at substantially the same rotation angle and angular velocity.

  In general, in a conventional deployable antenna using an extension mast, the number of deployment ribs and deployment hinges constituting the extension mast is as large as several hundreds. Here, with reference to FIG. 4, the structure of the hinge portion is compared between the conventional deployable antenna using the extension mast and the deployable antenna according to the first embodiment using the deployable mast. FIG. 4 (a) shows the structure of a normal extension mast, and FIG. 4 (b) shows the structure of a deployment mast using the rib 20 and the deployment hinge 21 according to the first embodiment.

  In FIG. 4 (a), with respect to one extension mast, the development rib 50 is indicated by a solid line, and the development hinge 51 is indicated by a circle. Although the drawing shows a simplified illustration of an extension mast, the extension mast constitutes a truss structure, so that there are still 32 deploying hinges for one extension mast. Therefore, when there are a plurality of extension masts, for example, six extension masts, the number of unfolding hinges is about 200. Practically, it is necessary to increase the number of hinges.

  On the other hand, in FIG. 4 (b), it is clear that the number of hinges can be greatly reduced as compared with FIG. 4 (a). In the deployable antenna, it is indispensable that all the unfolded hinges 21 are unfolded. Therefore, if the number of hinge points becomes enormous, the probability of causing a failure increases. In other words, reducing the number of hinges can reduce failures and increase reliability. In the first embodiment, a simple structure with few failure modes can be obtained by providing the development ribs 20 that form at least three stages of the beams and the development hinges 21 that relatively rotate the adjacent development ribs 20. . As a result, the deployment reliability can be further increased. Furthermore, since the configuration is simple, it is easy to reduce the size and weight. In addition, since there are few hinge points, the probability that the cable 2 is entangled with the deployment hinge 21 can be significantly reduced.

  Next, the metal mesh 1 which comprises a reflective mirror surface is demonstrated. In order to reflect radio waves, a reflective material is required on the mirror surface. In the case of a large deployable antenna, a mesh is often used for weight reduction. As this mesh, it is necessary to minimize the influence of the membrane surface on the tension state of the cable network. For this reason, by using a mesh-like knitted fabric with a small in-plane rigidity, the membrane surface can be stretched with a very small force, and the influence on the tension state of the cable network is kept small. In a knitted fabric, the fibers are knitted in a loop shape, so when a load is applied in the plane, the loop deforms and extends, so that the in-plane rigidity is not significantly affected by the axial rigidity of the fiber used. A low film can be obtained.

  In addition, when the reflective mirror surface corresponding to a high frequency band is comprised, the request | requirement with respect to a mirror surface accuracy becomes high with high frequency. In the L band and S band, the requirements for specular accuracy are relatively loose. However, in the Ku band and Ka band where the frequency band is higher, the requirement for specular accuracy is one order of magnitude smaller than in the L band and S band. For this reason, there is a limit to using a metal mesh in high frequency bands such as the Ku band and the Ka band. Therefore, the mirror surface accuracy may be improved by using a membrane material as a member constituting the reflecting mirror surface instead of the metal mesh 1. The membrane material is a flexible member that can maintain the shape at the time of molding, but can be folded by folding the membrane surface during storage. As the membrane material, for example, a material obtained by impregnating a silicon resin into a carbon fiber thinly woven into a plain weave may be used. By including silicon, the flexibility is improved, and the storage property is improved like the mesh.

  As described above, in the deployable antenna according to the first embodiment, the deployable mast is composed of a plurality of ribs connected to each other by deployable hinges so that it can be bent in two to three steps, The reflector is folded and stored so as to be sequentially folded inward from the rib, and the reflector is formed by unfolding from the stored state on the track.

  As a result, the number of hinge points constituting the deployment mast is drastically reduced, and the possibility of failure is greatly reduced. Thus, there is an effect that the reliability is greatly improved. Further, since the deployment mast is a simple and smooth mechanism in which two to three ribs are combined, there is an effect that the possibility that the deployment hinge, the deployment rib, the cable, and the mesh are entangled is reduced. Further, by covering the periphery of the deployment hinge with a film-like member, there is an effect that the possibility that the deployment hinge, the rib, the cable, and the mesh are entangled is significantly reduced.

  In the conventional deployable antenna, a canister or an extruding mechanism is required to extend the extension mast constituting the truss structure, and there is a problem that the overall weight becomes heavy because the mechanism is provided. . However, since the deployable antenna according to the first embodiment uses a deployment mast that deploys a plurality of beam members (deployment ribs), a canister or an extruding mechanism for extending the deployment rib is not required, and the overall weight is reduced. Can be made lighter.

Embodiment 2. FIG.
The second embodiment according to the present invention will be described below with reference to the drawings.
FIG. 5 is a view showing another embodiment of the deployable antenna according to the present invention. 5 (a) and 5 (b) are diagrams showing a deployment sequence of the deployable antenna reflector. Although it is the same structure as FIG. 3, the mirror surface mesh and the cable network are not described here. Further, only one unfolded mast is shown.

  This deployable antenna is mounted on the launcher in a stored state, and after being launched on the track, it is deployed to a large diameter by the deploying rib 20 and the deploying hinge 21. At this time, the development rib 20 at the distal end is disposed outside the development rib 20 at the intermediate portion, and is folded so that the development rib 20 at the intermediate portion is disposed outside the development rib 20 at the root portion. The unfolding operation becomes smooth and the reliability of the unfolding is further improved. That is, not only the movement distance of the metal mesh or cable network accompanying the deployment is smaller than that of the first embodiment, but also the movement of the metal mesh or cable network and the movement of the deployment rib are easily separated. For example, in the example of FIG. 5, the unfolding operation is completed when the unfolding rib 20 at the distal end is rotated by approximately 180 ° with respect to the unfolding rib 20 at the root portion. Therefore, as compared with the example of FIG. 3, the half of the rotation angle of the deployment rib 20 at the tip is sufficient, so that the operational reliability during deployment is further improved.

Embodiment 3 FIG.
The third embodiment according to the present invention will be described below with reference to the drawings.
FIG. 6 is a view showing another embodiment of the deployable antenna according to the present invention, FIG. 6 (a) shows an external view, and FIG. 6 (b) shows a folded state of the sub-reflecting mirror. It is.
In the figure, the sub-reflecting mirror 10 is supported by the extension structure portion 14. The feeding horn 12 is connected to a feeding unit (not shown). In this example, the extension structure portion 14 is configured to be foldable by a link mechanism, and the sub-reflecting mirror 10 can be folded to a position close to the tip of the feeding horn 12. The extension structure portion 14 includes three rods, and each rod includes three hinges 11 and links 15 connected to the hinges 11. Although the figure shows a link mechanism in which the bent portion has a one-stage configuration, it is possible to increase the number of hinges 11 and links 15 to configure a link mechanism in which the bent portion has a multi-stage configuration. Nor. Of course, as shown in FIG. 2B of the first embodiment, the periphery of the hinge 11 may be covered with a film surface to prevent entanglement with the cable.

  At the time of launching, the link 15 rotates and the extension structure portion 14 is bent, and the sub-reflecting mirror 10 is stored in the vicinity of the power feeding horn 12. By extending the extension structure portion 14 on the orbit, the sub-reflecting mirror 10 and the feeding horn 12 are positioned in front of the reflecting mirror, so that a center feed Cassegrain antenna can be configured. Moreover, since the link 15 of the extension structure part 14 is folded and the sub-reflection mirror 10 is accommodated at the time of launch, the arrangement space of the sub-reflection mirror 10 can be reduced.

Embodiment 4 FIG.
The fourth embodiment according to the present invention will be described below with reference to the drawings.
FIG. 7 is a view showing another embodiment of the deployable antenna according to the present invention, and FIG. 7 (a) is a view showing a state in which the unfolded mast attached to the satellite structure is shifted from the housed state to the unfolded state. FIG. 7B is a diagram showing an arrangement example of the reflecting mirror and the sub-reflecting mirror of the deployable antenna attached to the satellite structure after deployment.

  In the figure, one end of the deployment boom 16 is connected to the lower part (one end) of the satellite structure 13. The other end of the deployment boom 16 is connected to the deployment hinge 5. The deployment boom 16 connects the deployment mast 4 to the satellite body. The power feeding unit 17 includes a power feeding horn. In FIG. 7 (a), only one deployment mast is shown, and a mirror mesh and a cable network are omitted.

In this embodiment, first, the deployment boom 16 is deployed from the satellite body, and then the deployment ribs 20 are sequentially deployed to form the antenna reflector on the satellite side surface. In addition, an offset reflector can be configured by configuring the power feeding unit 17 at the upper part (the other end) of the satellite structure 13.

It is a figure which shows the structure of the expansion | deployment antenna by Embodiment 1 of this invention. (A) It is sectional drawing which shows the structure of the expansion | deployment mast by Embodiment 1 of this invention, (b) The partial detail figure which shows the structure of the expansion | deployment hinge by Embodiment 1 of this invention. It is a figure which shows the expansion | deployment operation | movement of the expansion | deployment antenna by Embodiment 1 of this invention. It is a figure for demonstrating the difference of the structure of the hinge part of the expansion | deployment antenna by Embodiment 1 of this invention, and the conventional expansion | deployment antenna. It is a figure which shows the accommodation state of the expansion | deployment mast by Embodiment 2 of this invention. It is a figure which shows the extension structure part of the sub-reflecting mirror by Embodiment 3 of this invention. It is a figure which shows the example of arrangement | positioning of the expansion | deployment antenna by the satellite body by Embodiment 4 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Metal mesh, 2 Cable, 3 Center hub, 4 Deployment mast, 5 Deployment hinge, 6 Storage cable, 10 Sub reflector, 11 Extension structure part, 12 Feeding horn, 13 Satellite structure, 20 Deployment rib, 21 Deployment hinge, 23 ToruCa, 16 deployment boom, 17 power feeding section.

Claims (6)

A metal mesh constituting the radio wave reflection surface of the antenna;
A cable that retains its shape;
Expand the metal mesh and cable from a folded state, and after deployment, a deployment mast arranged radially to hold the metal mesh and cable network;
A deployment hinge for deploying the deployment mast;
A center hub for holding the deployment mast;
In a deployable antenna having
The cable is bundled at a plurality of node points to form a cable network,
The cable network is composed of two sub-cable networks, a front cable network and a back cable network, which are arranged to face each other so as to sandwich the deployment mast,
Each node point of the two sub-cable networks is bound in a direction to pierce the radio wave reflection surface by a plurality of tie cables,
Some nodes located on the inner periphery side of the cable network are held and fixed to the center hub,
Some nodes located on the outer peripheral side of the cable network are each held and fixed to a support bar provided at the tip of the deployment mast,
The unfolding mast is composed of a plurality of ribs connected to each other by unfolding hinges composed of a single-axis rotating mechanism having a degree of freedom of rotation of 180 ° so that the unfolding mast can be bent in two to three steps. At the same time, the deployment mast was folded and stored so as to be sequentially folded inward from the tip side rib before deployment, and configured to form a radio wave reflection surface by deploying from the stored state on the track. Deployable antenna characterized by. 2. The deployable antenna according to claim 1, wherein the periphery of the deployable hinge is surrounded by a film. The deployable antenna according to claim 2, wherein the film is a mesh-shaped film. The deployment die according to any one of claims 1 to 3, wherein the deployment hinge is provided with a torquer that provides a rotational force for deploying the ribs by relatively rotating adjacent ribs. antenna. 5. The deployable antenna according to claim 4, wherein the torquer includes a coil spring. 5. The deployable antenna according to claim 4, wherein the ToruCa includes a direct drive.

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