JP4524170B2 - Satellite antenna - Google Patents

Description

  The present invention relates to an antenna mounted on an artificial satellite, and more particularly to a technique that is effective when applied to an antenna extending in the spin axis direction in a spin-stabilized satellite.

  An artificial satellite is equipped with an antenna for the purpose of measuring geomagnetism or the like or for the purpose of communication. In general, an antenna mounted on a satellite has a structure that can be stored so as to withstand the acceleration at the time of launch, and the antenna is extended after the satellite is stabilized in orbit. The following methods are known as methods for extending the antenna.

  When the artificial satellite is a spin stable system, a wire antenna can be adopted as an antenna that extends in a direction parallel to the spin plane. The wire antenna uses a conductive wire such as a metal having one end fixed to the peripheral surface of the artificial satellite and a mass body at the other end. Since the wire antenna can be extended in the radial direction by utilizing the centrifugal force caused by the spin, a driving device (actuator) for extension is unnecessary, and the antenna structure can be simplified and reduced in weight. Considering the recent trend of satellite miniaturization, the advantages of weight reduction are extremely large.

As an antenna extending in a direction perpendicular to the spin plane (spin axis direction), an STEM (Storable Tubular Extendible Member) type, a multistage cylindrical type, or an inflatable structure antenna is known. For example, Non-Patent Document 1 discloses the STEM type, Non-Patent Document for the multistage cylindrical type, and Non-Patent Document 3 for the inflatable structure, for example. These antennas that extend in the direction of the spin axis cannot use the centrifugal force due to the spin, and therefore must have a self-deployment function for extension.
Saito, Kasaba, Maezawa, Kojima, "SCOPE Planning Satellite System Study Overview", Space Science Symposium (3rd), January 9-10, Institute of Space Science MW Thomson, "Deployable and Retractable Telescoping Tubular Structure Development", 28 th Aerospace Mechanisms Symposium, May 18-20 1994. D. Lichodziejewski, G. Veal, R. Helms, R. Freeland, M. Kruer "Inflatable Rigidizable Solar Array for Small Satellite", 44 th IAA / ASME / ASCE / AHS Structures, Structural Dynamics, and Materials Conference, 7-10 April 2003, Norfork Virginia, AIAA2003-1898.

  The STEM type antenna is formed by bending a strip-like or tape-like sheet in the short side direction so as to form a hollow cylinder in a free-standing state. A conductive metal material having a high spring constant such as beryllium copper alloy is adopted so that a certain degree of mechanical strength is maintained in a free-standing state. In the free stand state, a curved and cylindrical sheet is developed in the short side direction against stress, and the storage state is realized by winding the sheet around a roll in the long side direction. When this is extended, a separate mechanism for feeding the sheet from the roll is provided, and the portion separated from the roll by this feeding is bent in the short side direction due to internal stress and becomes a hollow cylindrical state having mechanical strength to function as an antenna. It becomes like this.

  A multi-stage cylindrical antenna is an antenna that is extended by coaxially arranging a plurality of cylinders made of a conductive metal material or the like, and sequentially sending an adjacent outer cylinder from the inner cylinder to the outside. Similar to the STEM type, a mechanism for feeding the cylinder to the outside is required.

  An inflatable antenna is an antenna that realizes extension by sending gas into an extremely lightweight and flexible tube and expanding the tube by gas pressure. In the case of an antenna having this structure, it is not preferable that gas be present inside the tube in the state of use, and therefore it is necessary to harden the tube after extension to remove the internal gas. A curing agent is used for curing the tube.

  In the STEM type and multistage cylindrical type antennas described above, since the antenna having a cylindrical structure is adopted, the mechanical strength can be maintained not only after the deployment but also during the deployment. However, a feeding mechanism for feeding out the sheet or the concentric cylinder is necessary, and parts having a relatively large mass such as a motor must be used for these feeding mechanisms, so that the mass of the whole antenna mechanism becomes large. There is. Further, since a metal material is used as the antenna material, the weight is also increased. For this reason, although it can be put into practical use for a 1200 kg-class artificial satellite in which the mass of the whole antenna mechanism is relatively small, the relative mass becomes large for a 100 kg-class small artificial satellite, and the flight stability of the satellite cannot be secured. There is sex.

  An inflatable antenna uses a gas pressure as its extension mechanism and uses a light tube as an antenna material. For this reason, there is a high possibility that the weight of the entire antenna mechanism can be significantly reduced, and it is promising as a technique to be applied to a 100 kg class small satellite. However, inflatable antennas are flexible during deployment, and the behavior during deployment can adversely affect the orbital stability of the satellite. Moreover, there are many problems to be solved in the curing method after development, and the situation has not been put into practical use.

  An object of the present invention is to provide a lightweight satellite-mounted antenna that does not adversely affect the satellite orbit at the time of extension and does not have a problem of hardening after extension.

The invention disclosed in this specification is as follows. That is, mounted on a spin-stabilized satellite, and is housed when the satellite is launched, and is a satellite-mounted antenna configured to extend in the spin axis direction of the satellite after orbit stabilization,
An outer shell structure having a strength maintaining member, and a conductive member bonded to the strength maintaining member, and having a hollow cylindrical shape in the extended state;
An inflatable having a tube having one end sealed and the other end opened, and a gas introduction pipe inserted into the opening of the tube, wherein the opening of the tube is sealed at the outer periphery of the gas introduction pipe Structure and
Gas supply means for supplying gas to the gas introduction pipe,
By supplying the gas to the inside of the tube through the gas introduction pipe, the tube is extended into the hollow portion of the outer shell structure, and the outer shell structure is extended to the satellite of the satellite as the tube extends. This is a satellite antenna that extends in the spin axis direction.

  That is, the mechanical strength during and after extension of the antenna is ensured by the outer shell structure, and the inflatable structure is used as the extension mechanism (actuator) of the outer shell structure. Since an inflatable structure is used for the actuator, there is no need to provide a feeding mechanism required by the conventional STEM type and multistage cylindrical type, and a problem in terms of mass can be avoided. On the other hand, since the inflatable structure is used only for the actuator, the flexibility at the time of deployment and the curing method after deployment will not be a problem.

  The outer shell structure is curled in the short side direction due to its internal stress in the extended state, and in the stored state, the curl in the short side direction is developed and wound into a roll in the long side direction. A STEM type outer shell structure which is a film or a tape-like film or sheet can be applied. Alternatively, as the outer shell structure, a multi-stage cylindrical outer shell structure in which a plurality of hollow cylindrical structures are coaxially arranged and ends of the hollow cylindrical structures are coupled in an extended state can be applied.

  The strength maintaining member may be a fiber reinforced plastic (FRP), polyimide, or other plastic material, and the conductor may be a metal nonwoven fabric. Employing plastics such as FRP and polyimide film for the strength maintaining member can realize further weight reduction, and the metal nonwoven fabric can ensure the conductivity required for the antenna.

  According to the invention of the present application, the outer shell structure ensures the mechanical strength at the time of extension and after extension, so that it does not adversely affect the satellite orbit at the time of extension, and there is no problem of hardening after extension, A satellite-mounted antenna can be provided.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an exploded perspective view showing an example of a main part of an artificial satellite mounted antenna according to an embodiment of the present invention. FIG. 2 is a side view showing the main part of the antenna for satellite installation of FIG. The satellite mounting antenna of the present embodiment has an outer shell structure 1 and an inflatable structure 2. As shown in FIG. 2, at least the tip portion of the inflatable structure 2 is inserted into the hollow cylindrical portion of the outer shell structure 1.

  The outer shell structure 1 is a sheet that is wound around a roll 3 in the stored state. The outer shell structure 1 has an internal stress that is curved in the short side direction, and curls into a cylindrical shape at a portion away from the roll 3 as illustrated. In the present embodiment, the entire outer shell structure 1 (sheet) is not wound around the roll 3, and the end surface 5 on which the tube of the inflatable structure 2 (to be described later) abuts the tip portion 4. Have At the end face 5, the outer shell structure 1 is wound and fixed in a hollow cylindrical shape, and as the end face 5 moves away from the roll 3, the outer shell structure 1 that is separated from the roll 3 has a hollow cylindrical shape as if it is in the vicinity of the end face 5 due to its internal stress. Will come to do.

  The inflatable structure 2 includes a tube 6 and a gas introduction pipe 7. The tube 6 is sealed at one end and has an opening at the other end, and has a cylindrical shape when inflated. The tube 6 is made of a flexible organic film such as polyethylene or rubber, and can be housed by covering the outer periphery of the gas introduction tube 7. A gas introduction pipe 7 is inserted into the opening of the tube 6, and the opening is sealed to the outer periphery of the gas introduction pipe 7 by a seal member 8. The material of the gas introduction pipe 7 and the seal member 8 is arbitrary as long as appropriate mechanical strength and sealing performance are ensured. A gas cylinder 10 is connected to the gas introduction pipe 7 via a valve 9, and a rare gas such as carbon dioxide, nitrogen, argon, or an inert gas is supplied from the gas cylinder 10.

  The extension operation of such an antenna for satellite installation will be described. First, the outer shell structure 1 is wound around the roll 3, and the antenna is housed in a state where the tube of the inflatable structure 2 is put on the outer periphery of the gas introduction pipe 7. When the valve 9 is opened from this state, gas is supplied from the gas cylinder 10 through the gas introduction pipe 7 into the tube 6. The tube 6 covered on the outer periphery of the gas introduction pipe 7 expands under the pressure of the gas and starts to expand in the direction of the arrow 11. When the tip of the tube 6 reaches the end surface 5 of the outer shell structure 1, the end surface 5 receives the pressure from the tube 6 and extends the outer shell structure 1 in the direction of the arrow 11. FIG. 2 illustrates the initial stage of the start of extension. Extension is completed at the stage where the design length (for example, 5 m) has been extended.

  FIG. 3 is a partial cross-sectional view showing an example of the outer shell structure 1. The outer shell structure is a composite member composed of the strength maintaining member 12, the conductive member 13, and the adhesive member 14. Examples of the strength maintaining member 12 include a polyimide film and a fiber reinforced plastic (FRP) film. The thickness of the film is, for example, 0.1 mm. Examples of the conductive member 13 include a metal nonwoven fabric and a metal foil. The adhesive member 14 is for attaching the strength maintaining member 12 and the conductive member 13 together, but is not particularly necessary when the strength maintaining member 12 and the conductive member 13 can be integrally formed.

  For example, when the strength maintaining member 12 is made of a polyimide film and the conductive member 13 is made of a metal non-woven fabric, the two materials can be bonded together using a thermosetting adhesive and wound on a cylindrical surface, and then heat is applied to realize adhesion. it can. In this case, the roll of the outer shell structure 1 is made in the manufacturing process, and the stress is generated by the adhesive member 14. Alternatively, when the strength maintaining member 12 is FRP and the conductive member 13 is a metal nonwoven fabric, the fiber material (fiber) and the nonwoven fabric are wound around the outer circumference of the cylinder, and then FRP material such as unsaturated polyester resin is applied and predetermined curing is performed. The outer shell structure 1 can be manufactured through the steps. In this case, the adhesive member is not particularly required, and the stress for curling is obtained by the FRP material.

  FIG. 4 is a perspective view showing a state where the artificial satellite mounting antenna of the present embodiment is mounted on the artificial satellite. The satellite-mounted antenna of the present embodiment is arranged at the center of the small artificial satellite 16 that rotates in the direction of the arrow 15, and the outer shell structure 1 extends in the direction of the spin axis (arrow 17). FIG. 4 shows a state in which the outer shell structure 1 has completed extension. FIG. 4 shows a state in which two satellite mounting antennas shown in FIGS. 1 and 2 are arranged so that the extending directions of the outer shell structure 1 are opposite to each other.

  According to the satellite-mounted antenna of the present embodiment, since the outer shell structure 1 is provided, sufficient mechanical strength is ensured not only after the extension is completed but also during the extension. For this reason, there is no problem of flexibility during the extension and curing problems that existed in conventional inflatable structure antennas. Further, in the satellite mounted antenna according to the present embodiment, the inflatable structure 2 is used for the extension actuator of the outer shell structure 1. For this reason, the outer shell structure 1 can be extended without using parts such as a heavy motor. As a result, the entire antenna structure can be reduced in weight to such an extent that sufficient orbital stability can be ensured even in a 100 kg class small satellite.

  Although the present invention has been specifically described above, it is needless to say that the present invention is not limited to the above-described embodiment and can be variously modified without departing from the gist thereof. For example, in the above-described embodiment, the STEM type is exemplified as the outer shell structure 1, but a multi-stage cylindrical type in which a plurality of cylindrical members 18 as shown in FIG. 5 are concentrically arranged can also be adopted for the outer shell structure. It is. FIG. 5 shows the extended state, and it goes without saying that electrical contact of each cylindrical member 18 and prevention of separation of the cylindrical member 18 can be realized by providing the junction portion 19 with an appropriate connection structure.

  The present invention relates to an antenna mounted on a satellite, and is an invention that can be applied to the entire satellite field and the aerospace industry.

It is the disassembled perspective view which showed an example of the principal part of the antenna for artificial satellites which is one embodiment of this invention. It is the side view which showed the principal part of the antenna for artificial satellite mounting of FIG. 1 is a partial cross-sectional view showing an example of an outer shell structure 1. FIG. It is the perspective view which showed the state which mounted the artificial antenna mounting antenna which is one embodiment of this invention in the artificial satellite. It is the perspective view which showed the other example of the outer shell structure.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Outer shell structure, 2 ... Inflatable structure, 3 ... Roll, 4 ... Tip part, 5 ... End surface, 6 ... Tube, 7 ... Gas introduction pipe, 8 ... Seal member, 9 ... Valve, 10 ... Gas cylinder, 12 ... Strength Maintenance member, 13 ... conductive member, 14 ... adhesive member, 16 ... small satellite, 18 ... cylindrical member, 19 ... junction part.

Claims (3)

Mounted on a spin-stabilized satellite, housed when the satellite is launched, and mounted on a satellite-mounted antenna configured to extend in the spin axis direction of the satellite after orbit stabilization,
Fiber-reinforced plastic (FRP) or polyimide other strength retention member made of a plastic material, having a conductive member made of beauty metals nonwoven or foil Oyo, bonded together with the conductive member and the strength maintaining member with an adhesive, An outer shell that is formed by winding around a cylindrical surface and applying heat, or by winding the conductive member around the outer periphery of the cylinder and applying and curing a material that becomes the strength maintaining member, and forming a hollow cylindrical shape in the extended state Structure and
An inflatable having a tube having one end sealed and the other end opened, and a gas introduction pipe inserted into the opening of the tube, wherein the opening of the tube is sealed at the outer periphery of the gas introduction pipe Structure and
Gas supply means for supplying gas to the gas introduction pipe;
Have
By supplying the gas to the inside of the tube through the gas introduction pipe, the tube is extended into the hollow portion of the outer shell structure, and the outer shell structure is extended to the satellite of the satellite as the tube extends. Satellite antenna that extends in the direction of the spin axis.   The outer shell structure is curled in the short side direction by the internal stress in the extended state, and in the stored state, the curl in the short side direction is unfolded and wound into a roll in the long side direction. The satellite antenna according to claim 1, wherein the antenna is a tape-like film or sheet.   2. The artificial satellite according to claim 1, wherein the outer shell structure is a multistage cylindrical structure in which a plurality of hollow cylindrical structures are coaxially arranged and end portions of the plurality of hollow cylindrical structures are coupled in an extended state. Antenna.

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