JP7028437B2 - Radar and artificial satellites equipped with radar - Google Patents

Description

Application of Article 30, Paragraph 2 of the Patent Law 1. National University Corporation Chiba University Press Release Date: June 12, 2017 2.2017 IEEE AP-S Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting Date: July 9, 2017-. 2017 IEEE International Geoscience and Remote Sensing Symposium Date: July 23-28, 2017 4.2nd International Convention on Geosciences Date 20th May 11th, 2017

The present invention relates to a radar and an artificial satellite equipped with a radar.

Artificial satellites using radar (SAR) that acquire images and information on the surface of the earth using electromagnetic waves have been developed. The following Patent Document 1 describes an artificial satellite equipped with an elliptical / circular polarization synthetic aperture radar (SAR). An artificial satellite equipped with a synthetic aperture radar has the advantage of being able to observe the state of the earth's surface regardless of the weather and day and night.

Japanese Unexamined Patent Publication No. 2016-80710

Existing artificial satellites have a mass of several hundred kilograms to several tons, and due to their mass and shape, there is a problem that the rocket that carries them into outer space becomes extremely expensive.

An object of the present invention is to provide a small and lightweight radar and an artificial satellite equipped with a radar in order to solve the above problems.

According to one aspect of the present invention, in order to solve the above problems, the radar can be transformed from the retracted state to the deployed state, and a plurality of ribs attached to a core provided in the center of the antenna and the above-mentioned It has an antenna with a mesh attached to a rib and composed of fine metal wires and a feeder that radiates electromagnetic waves, the electromagnetic waves radiated from the feeder are reflected by the mesh, and the ribs are around the core of the antenna. It was attached so that it could be wrapped around.

Further, according to another aspect of the present invention, the radar can be transformed from the retracted state to the deployed state, and the plurality of ribs attached to the core provided in the center of the antenna and the metal attached to the ribs. It has an antenna including a mesh composed of threads and a feeder that radiates electromagnetic waves, and the electromagnetic waves radiated from the feeder are reflected by the mesh, and the ribs are used as a spring steel plate as a spring material and a composite material. The structure was combined.

Further, according to another aspect of the present invention, in order to solve the above-mentioned problems, a plurality of ribs that can be transformed from a stored state to an expanded state and are attached to a core provided in the center of the antenna, and the ribs. It has an antenna equipped with a mesh made of a metal thread attached to the mesh and a feeder that radiates an electromagnetic wave, and the electromagnetic wave radiated from the feeder is reflected by the mesh, and the mesh is tensioned in either a vertical or horizontal direction. Even if the above is added, the electrical characteristics are assumed to change linearly and isotropically.

Further, according to another aspect of the present invention, the radar can be transformed from the retracted state to the deployed state, and the plurality of ribs attached to the core provided in the center of the antenna and the metal attached to the ribs. It has an antenna including a mesh composed of threads and a feeder that radiates electromagnetic waves, and the electromagnetic waves radiated from the feeder are reflected by the mesh, and the mesh is made into a net structure.

Further, according to another aspect of the present invention, the above radar is mounted on the artificial satellite.

According to the present invention, it is possible to provide a small and lightweight radar and an artificial satellite equipped with the radar.

It is a figure which shows the outline of the whole artificial satellite of this Example. It is a figure which shows the outline when the antenna of this Example is seen from the top. It is a figure which shows the outline when the antenna of this Example is seen from the side. It is a figure which shows the deployment process of the antenna of this Example. It is a figure which shows the outline of the shape of the antenna of this Example seen from the side. It is a figure (the 1) which shows the deployment process of the antenna of this Example. It is a figure (the 2) which shows the deployment process of the antenna of this Example. It is a figure (the 3) which shows the deployment process of the antenna of this Example. It is a figure which shows the place where the mesh of this Example is manufactured with a loom.

Hereinafter, embodiments and examples of the present invention will be described, but the embodiments of the present invention are not limited to the embodiments and examples described below. Further, in the following description, an example in which a radar is mainly mounted on an artificial satellite will be described, but the radar of the present invention can also be mounted and used in an aircraft, a UAV, or a vehicle.

In this embodiment, the antenna part uses a mesh (only 50 g per 1 m ² ) made of fine gold-plated metal thread from conventional aluminum, reinforced plastic, etc., and the frame is changed to a lightweight spring material. By doing so, the weight of the artificial satellite, which used to have a mass of several hundred kilograms to several tons, has been reduced to 120 kg or less.

Normally, when tension is applied to a mesh, the shape of the stitches of the mesh is deformed non-linearly, a non-linear change in electromagnetic wave transmission performance occurs, and there is a problem that it is difficult to obtain stable electromagnetic wave transmission characteristics. Therefore, in the present invention, the weaving method of the mesh is improved so that the electrical characteristics change linearly and isotropically even if tension is applied in either the vertical or horizontal direction, thereby having stable communication performance. did.

Also, in the normal Wrap-Rib (a method of bending the rib so that the rib wraps around the center of the antenna when the antenna is stowed), the ribs are arranged in the radial direction so that they can be bent in the radial direction. When storing compactly around, it is necessary to provide a hinge at the base of the rib, and to fold it small, it is necessary to provide two or more hinges. In the present invention, the rib can be used as a spring material so that the rib can be wound around the core. This eliminates the need for hinges when winding and enables compact storage.

FIG. 1 is a diagram showing the entire artificial satellite of this embodiment. The solar cell 1 converts sunlight into electrical energy to obtain energy for operating an artificial satellite. The antenna 2 has a feeder 22, a rib 23, and a mesh 21. Electromagnetic waves are radiated from the feeder 22 toward the mesh 21, and the electromagnetic waves reflected from the mesh 21 are transmitted to the surface of the earth. The electromagnetic wave reflected from the ground surface is received by the mesh 21, and the state of the ground surface is observed by analyzing the electromagnetic wave. That is, this artificial satellite has a radar function for observing the state of the earth's surface by transmitting and receiving electromagnetic waves. In the present embodiment, the feeder is attached to the tip of the center of the antenna, but the present invention can also be used for an antenna in which the feeder is attached to the base of the center of the antenna and the submirror is attached to the tip of the center of the antenna. Applicable. The housing 3 houses a control unit that controls each part of the artificial satellite, a power source that supplies electric power to each part of the artificial satellite, and the like. A mesh 21 is attached to the rib 23. Normally, the mirror surface of the antenna 2 is composed of a plate of aluminum and reinforced plastic, but in this embodiment, the diameter is about several tens of μm (for example, about 1 μm to 10 μm in thickness) plated with gold. , A metal mesh made of molybdenum fine wire with a diameter of about 10 μm to 50 μm) is used to significantly reduce the weight of the antenna. A mesh 23 is attached to a core (not shown) in the center of the antenna. The size of the stitches of the mesh is, for example, about 1 mm to 10 mm.

Further, usually, when tension is applied to the mesh 23, the shape of the stitches of the mesh is deformed and the isotropic property is broken, a non-linear change in the electromagnetic wave transmission performance occurs, and it is difficult to obtain stable electromagnetic wave transmission characteristics. Therefore, in this embodiment, the weaving method of the mesh is improved, a special knitting method is performed using a traditional Japanese knitting machine, and the electrical characteristics are linear and isotropic regardless of whether tension is applied in either the vertical or horizontal direction. It was made to change in a positive manner, thereby having stable communication performance.

The structure of the mirror surface of the antenna 2 is a Wrap-Rib type, in which the mesh 21 is attached to the radial rib 23. The rib 23 is wound around the central hub when it is stored, and returns to its original shape due to the spring rigidity of the rib when it is deployed.

The rib 23 has a structure in which a spring steel plate as a spring material and a composite material (multilayer structure) as a lightweight structural member are combined. The structural members are designed and selected so that they can be bent so that they can be restored to their original shape while maintaining the rigidity of the structural members.

FIG. 2 is a schematic view of the antenna of the present embodiment when viewed from above, and FIG. 3 is a schematic view of the antenna of the present embodiment when viewed from the side.

FIG. 4 is a diagram showing an unfolding process seen from above the antenna of this embodiment, and at the time of unfolding, the rib is deformed from the state of 31 to the unfolded state of 33 through the state of 32.

FIG. 5 is an outline of the shape of the rib 23 as seen from the side. The width of the rib 23 becomes smaller toward the tip. Since the need for maintaining the strength of the rib 23 decreases toward the tip, the width of the tip of the rib 23 is reduced in order to reduce the weight.

In the method of arranging the ribs in the radial direction so that they can be folded in the radial direction or extending the ribs, when storing compactly around the center of the antenna, a hinge is provided at the base of the ribs and the ribs are folded to store or store. The ribs are extended by a motor or another deployment mechanism is required. In this embodiment, the rib can be used as a spring material so that the rib can be wound around the core. As a result, when the rib is wound around the core, a deployment mechanism such as a hinge or a motor is not required, and the rib can be miniaturized and stored. In addition, the ribs are integrated with the antenna support structure and the expansion spring to reduce the number of parts, thereby simplifying and reducing the weight.

6, 7, and 8 are diagrams showing the process of deploying the antenna. In FIG. 6, the rib 23 is fixed by a fixing means such as a wire (not shown), and the antenna is compactly housed. When the fixing means releases the fixing from this state, the rib 23 is deformed by the spring rigidity (action of the leaf spring) of the rib, and the rib 23 is in the expanded state as shown in FIG. 8 through the state of FIG.

FIG. 9 is a diagram showing a mesh being manufactured on a traditional Japanese loom. In this embodiment, unlike the conventional mesh, the shape of the stitches does not change easily even if it is pulled in either the vertical or horizontal direction, and it is made the same as a mirror surface without holes so that the linearity of the communication characteristics is maintained. In addition, the mesh is used as a net structure. Therefore, stable electromagnetic wave transmission characteristics are maintained.

The present invention can be industrially used as a radar and an artificial satellite equipped with a radar.

1 Solar cell 2 Antenna 21 Mesh 22 Feeder 23 Rib 24 Core 31, 32, 33 Rib

Claims (5)

It can be transformed from the stored state to the deployed state, and has a plurality of ribs attached to the core provided in the center of the antenna, a mesh made of metal threads attached to the ribs, and a feeder that radiates electromagnetic waves. A radar having an antenna provided, electromagnetic waves radiated from the feeder are reflected by the mesh, and the ribs can be wound around the core of the antenna and stored at the time of storage. It can be transformed from the stored state to the deployed state, and has a plurality of ribs attached to the core provided in the center of the antenna, a mesh made of metal threads attached to the ribs, and a feeder that radiates electromagnetic waves. A radar having an antenna provided, electromagnetic waves radiated from the feeder are reflected by the mesh, and the ribs have a structure in which a spring steel plate as a spring material and a composite material are combined. It can be transformed from the stored state to the deployed state, and has a plurality of ribs attached to the core provided in the center of the antenna, a mesh made of metal threads attached to the ribs, and a feeder that radiates electromagnetic waves. A radar that has an antenna and the electromagnetic waves radiated from the feeder are reflected by the mesh, and the mesh changes its electrical characteristics linearly and isotropically even when tension is applied in either the vertical or horizontal direction . It can be transformed from the stored state to the deployed state, and has a plurality of ribs attached to the core provided in the center of the antenna, a mesh attached to the ribs and composed of metal threads, and a feeder that radiates electromagnetic waves. A radar having an antenna provided, electromagnetic waves radiated from the feeder are reflected by the mesh, and the mesh is used as a net structure. An artificial satellite equipped with the radar according to any one of claims 1 to 4.

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