JP2560809B2 - Mesh antenna mirror surface using cable network - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a mesh antenna mirror surface, and more particularly to a mesh antenna using a cable network capable of controlling the shape while being resistant to a cable length error and a cable tension error. It is about the mirror surface.

(Prior Art) FIG. 4 shows two typical types of cable networks that form a conventional antenna mirror surface.

Fig. 4 (A) shows a conventional tension truss (reference;
““ Research and Development of the Tension Truss
Antenna ", Preprint 38th IAF, IAF−87−317, K.MIURA et
al. ", 100 is a rigid truss cable with little expansion and contraction, 102 is a node, 104 is a reflector surface, 106 is a tie cable, 1
08 indicates a stretchable backup cable.

The tension truss has a high elongation rigidity of the cable that constitutes the mirror surface, and the number N of them is the number m of nodes on the mirror surface and 3m = N
It is configured to satisfy the following statically determined truss condition. The non-mirrored cable is configured to provide tension to the mirrored cable. When the rigidity of the cable forming the mirror surface is so high that the elongation due to the tension can be ignored, the mirror surface shape is considered to be uniquely determined by the length of the cables and their arrangement, and therefore the shape control is considered to be easy.

FIG. 4 (B) shows a conventional catenary system (reference;
"" Comparison of Tension Stabilized Structures fo
r Large Space Antenna Reffector Proc.27th SDM Part
1.PP752-756, JJ.Herbert, EEBachtell '', 110
Is a surface cord, 112 is a drop cord, 114 is a box truss surface tube member, 116 is a catenary cord, and 118 is a truss standoff.

The catenary system is a cable network that is generally used as a so-called "mesh", and there is no particular condition regarding the rigidity of the cable. Since the shape of this cable network is determined by the balance of the forces applied to stretch the network, the mirror surface is deformed sensitively to changes in the forces.

(Problems to be solved by the invention) FIG. 5 is a result of analyzing the expected value of the mirror surface RMS error with respect to the cable length error normally distributed for the same antenna diameter, the same number of division tension trusses, and the catenary system by Monte Carlo simulation. Is a graph showing the initial strain (initial tension / rigidity) of the cable as a parameter. In the figure, the horizontal axis represents the cable length error deviation and the vertical axis represents the dimensionless amount of the mirror surface RMS error for the given length error deviation by the antenna diameter. The analysis is performed for the antenna with focal length / antenna diameter = 1.5, and the cable tensions in the initial state of all the following analyzes are assumed to be equal. Therefore, a large value of initial strain means a cable with low elongation rigidity, and a small value means a cable with high elongation rigidity. The length error was given only to the cable on the mirror surface.

It can be seen from FIG. 5 that a rigid cable is more vulnerable to length error than a flexible cable, that is, if the cable length is not precisely adjusted, the cable will bend and a large deformation will occur on the mirror surface. This is because the flexible cable absorbs the length error by the initial strain to prevent the cable from bending and reduces the deformation of the mirror surface, but the rigid cable has less strain even if stretched with the same tension, so the length error It is thought that it is not possible to absorb. Therefore, in order to bring all the many rigid cables such as tension trusses into tension, subtle cable length adjustments are required. On the other hand, since the catenary system originally maintains its shape due to the balance of forces, the cable is less likely to bend due to the cable length error, and therefore the deformation amount is smaller than that of the tension truss.

However, on the contrary, since the shape is maintained by the balance of the forces, it largely reacts to the error of the magnitude of the force pulling the node on the mirror surface, that is, the cable error other than the mirror surface portion (6th
Figure). Further, control of the mirror surface shape is complicated because force balance is considered.

As described above, when the antenna mirror surface is configured by the conventional cable network, there is nothing that is strong against both the cable length error and the force error applied to the network and the shape control is simple.

Therefore, an object of the present invention is to provide a mesh antenna using a cable network for antennas which is strong in both of them and whose shape can be easily controlled.

(Means for Solving the Problems) A feature of the present invention for achieving the above-mentioned object is that the elongation rigidity is high, the number of cables C is three-dimensional, or the number n of unfixed nodes is C = 3n, or C. = 2n The backup cable configured to satisfy the two-dimensional statically-determining truss condition and the number of nodes that are not fixed with multiple cables that have lower elongation rigidity and adjustable length compared to the above backup cable The number of cables D and the three-dimensional statically-determining truss condition of D = 3 m are configured so as to satisfy the relation, and a surface cable that forms a mirror surface of the antenna by forming a conductor mesh in the network Consists of a tie cable that connects the nodes to each other in a one-to-one relationship and has high elongation rigidity and adjustable length, and a support structure that applies cable tension. The shape of the antenna mirror surface can be controlled by changing the length of one of the surface cable and the tie cable, and the mirror surface is stable against the error of the cable length and the error of the force that gives tension to the cable. It is on the mirror surface of the antenna using the cable network that forms the.

(Operation) In the antenna according to the present invention, since the surface cable is flexible, it is more resistant to cable adjustment error than a network composed of a rigid cable, and the network is extended because it satisfies the three-dimensional static definite condition. Strong against power error.

Fig. 2 shows the results obtained by correcting the mirror surface deformations of two types of cable networks having the same geometry and having rigid and flexible cable elongation stiffnesses by controlling the surface cable as a rigid body. This result shows that both the deformation of the network composed of a rigid cable and the deformation of a network composed of a flexible cable can be corrected by the same control method assuming that the cable is a rigid body. Of course, a network composed of rigid cables corrects the deformation with less adjustment times than a flexible cable, but even with a flexible cable network, increasing the number of adjustments can improve the shape without considering the balance of forces. You can control.

The backup cable and the tie cable are made of rigid cables, and the surface cable is made of a flexible cable.By changing the tie cable length, the node position on the backup cable side is hardly moved and the node on the mirror surface is not changed. You can move the position. When the surface cable is flexible, the influence of the movement of one node does not spread over the entire mirror surface, so even if the tie cable is adjusted, only a part of the mirror surface can be controlled.

By constructing the mirror surface with such a flexible cable net, it is resistant to cable length errors, and it is also resistant to external force errors when the number of cables and the number of nodes satisfy the static determination condition. It is possible to provide an antenna mirror surface using a cable network that is easy to control the mirror surface shape by changing it, changing the length of the tie cable, or both (in each case, consider the cable as a rigid body) Becomes

 Therefore, the object of the present invention is achieved.

(Embodiment) FIG. 1 shows a first embodiment of the present invention. In the figure, 10 is a flexible cable whose length can be adjusted, where the number N of cables and the number M of nodes 20 are three-dimensional static truss conditions 3M. = N, a surface mesh formed so that a conductor mesh 18 is stretched between the surface cables to form an antenna mirror surface. 12 is a backup cable composed of a rigid cable, 14 is a rigid tie cable with adjustable length connecting the node 20 of the surface cable 10 and the node 22 of the backup cable 12, 16 is a hard point provided by the support structure . The correction of the mirror surface deformation is performed by changing the lengths of the surface cable 10 and the tie cable 14 by using a length adjusting mechanism such as a turnbuckle.
Between the number C of backup cables and the number n of nodes 22, the three-dimensional static definite truss condition C = 3n or the two-dimensional static definite truss condition C = 2n is mixed and satisfied.

FIG. 3 shows a concrete embodiment of the present invention, in which 10 is a surface cable, 12 is a backup cable, 14 is a tie cable, A1 to A14 are hard points provided by the support structure 22, and 30 is a pole for supporting the hard points. Is.

(Effect of the Invention) As described above, in the mesh antenna mirror surface using the cable network according to the present invention, since the mesh antenna mirror surface is resistant to the cable length error and the cable pulling error, the mesh antenna is configured with high accuracy. It is possible to correct the deformation of the mirror surface by a method assuming the cable as a rigid body without considering the complicated force balance.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration example of an antenna mirror surface according to the present invention,
FIG. 2 is a diagram showing a result of correcting the mirror surface deformation of the flexible cable and the rigid cable by a mirror surface adjustment algorithm assuming that the cable is rigid, and FIG. 3 is a diagram showing an embodiment of the present invention.
The figure shows a conventional tension truss and catenary system. Figure 5 shows the mirror surface deformation due to the cable length error. The horizontal axis shows the cable length deviation and the vertical axis shows the mirror surface RMS error with the mirror surface diameter made dimensionless. The solid line shows the tension truss and the dash-dotted line shows the catenary system. Figure 6 shows the result of calculating the mirror surface deformation due to the error of the cable tension force. The horizontal axis shows the force error deviation and the vertical axis shows the mirror surface RMS error. Is a dimensionless quantity. 10; surface cable 12; backup cable 14; tie cable, 16; hard point 18; mesh

Claims (1)

(57) [Claims] 1. A backup configured to satisfy a three-dimensional static truss condition in which the number C of cables and the number n of unfixed nodes having a high elongation rigidity are C = 3n or two-dimensional where C = 2n. The relationship between the cable and the three-dimensional statically-determining truss condition in which the number m of nodes not fixed with multiple cables with low elongation rigidity and adjustable length compared to the above backup cable is the number of cables D and D = 3 m The surface cable that forms the antenna mirror surface by connecting the conductor mesh inside the network and the backup cable and the node of the surface cable are connected to each other in a one-to-one relationship with high elongation rigidity and adjustable length. Consists of a cable and a support structure that imparts cable tension. The antenna using the cable network is characterized in that the shape of the antenna mirror surface can be controlled by changing it, and a stable mirror surface is formed against the error in the length of the cable and the error in the force that gives tension to the cable. Mirror surface.