JPS5937881B2 - Gravity tilt stabilized deployable antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a large, lightweight deployable antenna oriented toward the earth in satellite orbit.

Conventional satellite orbiting antennas are either non-deployable, consisting of a shell or beam structure, or deployable, which deploy in space, have a relatively rigid support. Its shape was maintained by the rigidity of the structure itself.

For this reason, due to the size and weight constraints of launch vehicles, the size was limited to several meters for non-deployable types and more than ten meters for deployable types.

Some parts are launched into orbit multiple times,
A method of constructing a large antenna by assembling these antennas has also been proposed, but in this case, considerable rigidity and strength are required to resist disturbance forces caused by gravitational tilt and solar radiation. When building an antenna, it is necessary to create a structure that weighs several thousand tons.

The present invention achieves weight reduction and ease of deployment by utilizing the force caused by gravitational tilt, which has traditionally been a disadvantageous factor, and makes it possible to inexpensively produce antennas with diameters of several kilometers to hundreds of kilometers. This figure will be explained in detail below.

In outer space, if two mass points 1 and 2 are connected by a cable 3 as shown in Figure 1 and are on a satellite orbit with an orbital angular velocity of ω, both mass points will be included due to the action of gravity and centrifugal force. It is stabilized in the direction in which the axis 4 coincides with the center of the gravitational field.

At this time, the cable 3 has a distance t1 between the center of gravity G of this system and the mass point 1, and 3 ml 11ω which is proportional to the mass m1 of the mass point 1.
2 tension acts.

FIG. 2 shows one embodiment of the antenna of the present invention, in which the reflector 5 is connected to the satellite main body 6 including the power feeding section by a large number of cables 7.The direction connects the center of gravity of the reflector 5 and the satellite main body 6. points towards the center of Earth E and becomes stable.

Note that 6A is a power supply section. The reflector 5 has a structure that can be folded at the time of launch, and as shown in FIG. It is composed of a reflective material 9.

Depending on the component and direction of the tension from the cable 7, the rigid member 8 may receive a compressive force due to the force due to the gravitational inclination (Journal of the Aeronautical Society Vol. 15, No. 159, April 1967,
112-123, "Attitude Control of Artificial Satellite Utilizing Gravity Gravitational Inclination"), it is made of something that has rigidity to prevent buckling, such as an aluminum cylinder with a diameter of 2 to 57 nm.

The rigid members 8 are interconnected by hinges 10 that are free to rotate in all directions, and cables 7 are tied to each hinge.

Further, the radio wave reflecting material 9 is attached to the rigid member 8 and forms a radio wave reflecting surface.

FIG. 4 shows the principle by which the reflective mirror surface is maintained in a desired shape.

Centrifugal force and gravity act on the reflecting mirror, and the vector sum of these acts as shown by the arrow in the figure and balances the cable tension and the internal force of the member 8.

Since the hinge 10 connecting each member 8 is free to rotate, the position of each hinge is uniquely determined by the length of the cable 7.

Therefore, by adjusting the length of each cable, the position of each hinge point in the direction perpendicular to the mirror surface can be independently controlled.
The shape, direction, etc. of the reflective mirror surface can be set arbitrarily.

The cable length can be adjusted, for example, by winding and unwinding one end of each cable using a micromotor or the like, and driving the micromotor in response to a command from the ground.

As another example of the present invention, (1) as shown in FIG. (ii)
As shown in FIG. 6, a large rigid beam 6B extends from the satellite body 6.
Or, by decentering the center of gravity of the reflector 5, the direction of stability can be moved from the direction connecting the satellite and the center of the reflector so that the satellite body comes out of the antenna beam, or the beam direction can be changed to the center of the earth. As shown in FIG. 7, a configuration in which the power supply section 6A and the like are further connected to the earth side from the satellite main body 6 to increase stability is conceivable.

As explained above, in the antenna of the present invention, the only structural member to maintain the shape of the reflector is a rigid member (beam) that can withstand a compressive force of only a few grams. Can keep weight down.

Another advantage is that it can be easily folded when transported to orbit by a rocket, and unfolding requires almost no effort.

Furthermore, since the stability provided by gravitational inclination is utilized, there is the advantage that only a minimum amount of active attitude control is required, such as solar panels, fine beam direction adjustments, etc.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of a satellite with stable gravity tilt, Fig. 2 is a schematic diagram of an embodiment of the antenna of the present invention installed on an artificial satellite, and Fig. 3 is a partially enlarged perspective view of the reflector shown in Fig. 2. , FIG. 4 is a schematic cross-sectional view of the reflecting mirror shown in FIG. 2, and FIGS. 5 to 7 are schematic views showing other embodiments of the present invention. 5...Reflector, 6...Satellite body, 6A
...Power supply section, 7...Cable, 8...
... Rigid member, 9 ... Radio wave reflecting material, 10.
...Hinge.

Claims (1)

[Scope of Claims] 1. A rigid member connected in a net shape by rotatable hinges, a radio wave reflecting material attached to the rigid member and forming a reflective mirror surface, and one end of each of which is connected to a plurality of hinges,
A horsepower tilt stabilized deployable antenna comprising a plurality of cables whose other ends are connected to a satellite body or a member rigidly connected thereto. 2. The gravity tilt stabilized deployable antenna as described in the preceding paragraph, characterized in that the lengths of the cables are individually adjustable.