JPH0572122B2 - - Google Patents

Description

[Detailed description of the invention]

This invention relates to a method of manufacturing a reinforced plastic parabolic antenna. Conventional parabolic antennas manufactured by press working or sheet metal processing on metal plates such as aluminum or iron have problems with corrosion resistance and light weight, so recently, instead of the metal plates mentioned above, wire mesh or carbon fiber pine are being used. Parabolic antennas using reinforced plastic and reinforced with reinforced plastic began to be developed. For example, JP-A-56-149802 discloses a structure in which a conductive reflective material such as wire mesh or carbon fiber mat is layered on reinforced plastic and molded into a certain shape. In addition, Japanese Utility Model Application Publication No. 55-3574 discloses that, as an antenna reflector, surfacing cloth, conductive cloth, multiple sheets of glass cloth, and surfacing cloth are laminated in order from the concave side, and each of these layers is made of resin. discloses an integrated unit that is bonded by thermocompression. However, in the former case, contact pressure or pressure from the mold is applied to the reflective material during molding, causing the reflective material to shift or partially break, reducing the functionality of the antenna. Ta. On the other hand, in the latter case, the presence of the surfacing cloth on the concave side acts as a buffer material during molding, reducing the positional shift of the reflective material. This surfacing cloth uses a surfacing cloth that is woven in an array, and the elasticity of this surfacing cloth is different in the thread direction and the inclination direction, that is, the elasticity has a directionality. There is a problem in that distortion occurs in the parabolic antenna of the product, and for example, when the parabolic antenna is placed face down on a flat surface, a large gap is formed in a part of the periphery, which deteriorates the antenna performance.
In addition, the surfacing cloth mentioned above bundles a large number of fibers into a thread that is thicker and harder than the fibers themselves, and uses this for the warp and weft, so the basis weight is large, and there is also resin between the fibers. There were problems such as difficulty in impregnating the product, resulting in poor smoothness of the product surface after molding, making painting difficult, and damaging the shear edge of the mold during molding. This invention eliminates the positional shift of the reflective material during manufacturing of the parabolic antenna, and has good workability.
The present invention provides a method for manufacturing a parabolic antenna that does not cause distortion in the parabolic antenna product. That is, the present invention provides a conductive reflective material having a basis weight of 10 to 100 g/m2, which is formed by stacking glass fibers or organic fibers to a uniform thickness in any direction on at least the concave side of a conductive reflective material, and bonding the fibers to each ^other at contact points. This is a method for manufacturing a reinforced plastic parabolic antenna characterized by disposing and molding a mat-like cushioning material. Although various methods are known for molding a reinforced plastic parabolic antenna, an example of a manufacturing method using a pair of male and female molds will be explained with reference to the drawings. 1 is a male mold having a convex surface, and 2 is a female mold having a concave surface. The male mold 1 forms the concave surface of the parabolic antenna, and the female mold 2 forms the convex surface of the parabolic antenna. After the convex surface of the male mold 1 and the concave surface of the female mold 2 are treated with a release agent, a concave gel coat layer 1a and a convex gel coat layer 2a are formed. A concave cushioning material 3 is provided on the concave gel coat layer 1a.
a. The conductive reflective material 4 and the convex cushioning material 3b are stacked and impregnated with a resin liquid. Next, a sheet molding compound or glass fiber mat impregnated with a resin liquid is laminated to a desired thickness to form a molding material 5, and a female mold 2 is assembled thereon, and then heated to harden and molded. . In the hand lay-up method and the spray-up method in which only the male die 1 is used as a mold, the convex cushioning material 3b on the convex side of the reflective material 4 may be omitted. The cushioning material used in this invention is a mat made of glass fiber or organic fiber, that is, the fiber length of the glass fiber or organic fiber is preferably 50 to 400.
It is a type of non-woven fabric made by stacking mm short fibers to a uniform thickness in any direction and bonding the contact points between the fibers to maintain the sheet form, and its basis weight is 10~
It is 100g/ ^m2 . If the area weight is less than 10g/ ^m2 , it will not be effective as a cushioning material;
If it exceeds 100g/ ^m2 , a large amount of resin for impregnation will be required, although the buffering effect will not improve.
It becomes heavy and uneconomical. In this invention, conventional molding methods are used. When using thermosetting resins such as unsaturated polyester resins, epoxy resins, and methyl methacrylate resins, hand lay-up methods, spray-up methods, prepreg methods, etc. are suitable, especially for unsaturated polyester resins and short glass fibers. Using a relatively inexpensive sheet molding compound (SMC) made from pine as the molding material 5,
The SMC method, which involves compression molding within a mold, is optimal.
Furthermore, when using thermoplastic resins such as polyamide, polyethylene terephthalate, and polypropylene, injection molding is suitable. The above conductive reflective material includes aluminum,
A wire mesh made of iron or the like, a flat material such as carbon fiber mat, or a conductive filler such as metal-coated glass fiber chop or carbon black is used. The following describes embodiments of the invention. Example 1 After treating the convex surface of the mold (male mold) with a release agent, a gel coat layer of unsaturated polyester resin was formed thereon, and glass fiber mat (fabric weight 30 g/m ² ) was formed on this gel coat layer. was layered as a cushioning material, and then an aluminum wire mesh (wire diameter 0.2 mm, 16 meshes) was layered on top of that as a reflective material, and the unsaturated polyester resin liquid was impregnated from the top. Next, chopped strand mats made of glass fiber and roving cloth are stacked one on top of the other, and unsaturated polyester resin liquid containing a catalyst is applied with a brush and roller until the desired thickness (4.5 to 5.0 mm) is reached. Then, it was hardened and molded using the so-called hand lay-up method. After that, the mold was removed and trimmed to create a parabolic antenna with a diameter of 1.8 m. Attach the antenna of Example 1 above to a mount, connect the horn, waveguide and converter,
When we measured the radio wave gain by emitting radio waves with a frequency of 4 GHZ in the form of a beam from a transmitting antenna (metal reference parabolic antenna) located 200 meters away, we found that
I got a result of 35.0dB. On the other hand, the antenna of Comparative Example 1, which was made in exactly the same manner as Example 1 except for omitting the above-mentioned buffer material, had a radio wave gain.
It was 33.5dB. That is, in Example 1, the radio wave gain was improved by 1.5 dB by providing the buffer material. In addition, when a parabolic antenna of Comparative Example 2 was manufactured in the same manner as in Example 1 except that the weight of the glass fiber mat as a cushioning material was increased to 230 g/ ^m2 , the radio wave gain was was 34.5 dB, which is 0.5 dB lower than in Example 1.
When we cut this antenna and observed the cross section, we found that the concave side of the reflective material (aluminum wire mesh)
A 0.9 mm resin and glass fiber layer was formed. Example 2 The glass fiber mat of Example 1 (fabric weight 30 g/m ² ) as a cushioning material and the carbon fiber mat (fabric weight 30 g/m ² ) as a conductive reflective material were placed in a pair of male and female molds.
were stacked, polypropylene was injected and press-fitted into the mold (thickness: 3 to 3.5 mm), and cooled to obtain a parabolic antenna with a diameter of 1 m. When the radio wave gain of the antenna of Example 2 was measured using the reference antenna of Example 1 for transmission, it was found that at a distance of 2000 m and a frequency of 12 GHZ.
It was 39.8dB. On the other hand, the radio wave gain of Comparative Example 3 in which the above-mentioned buffer material was omitted was 38.0 dB. That is, by providing the buffer material of Example 2, the radio wave gain was improved by 1.8 dB. Note that when the antenna of Example 2 was laid down on a flat surface, the maximum gap created around it was 0.3 mm. On the other hand, the maximum gap in Comparative Example 4, in which the cushioning material in Example 2 was replaced with glass fiber cloth (basis weight 30 g/m ² ), was as follows:
0.6mm, and its radio wave gain is higher than that of Example 2.
It was 39.2dB, which is 0.6dB lower. In addition, the above Example 2
In this case, the basis weight of glass fiber pine is 5g/m ²
A parabolic antenna of Comparative Example 5 was manufactured in the same manner as in Example 2, except that the radio wave gain was lower than that of Comparative Example 3 in which the glass fiber mat was omitted.
It was the same as 38.0dB. That is, compared to Comparative Examples 1 and 2, Example 1 had
Furthermore, the radio wave gain of Example 2 was improved by 0.5 dB or more compared to Comparative Examples 3, 4, and 5. Example 3 A parabolic antenna of Example 3 was manufactured in the same manner as Example 2 except that the weight of the glass fiber mat was set to 50 g/m ² and the diameter was set to 75 cm in the parabolic antenna of Example 2 above. did.
In addition, the antenna of Comparative Example 6 was prepared in the same manner except that the basis weight of the glass fiber mat in Example 3 was changed to 9 g/m ² , and the basis weight of the glass fiber mat was changed to 9 g/m ² The antenna of Comparative Example 7 was prepared in the same manner, and the antenna of Comparative Example 8 was prepared in the same manner except that glass fiber cloth (basis weight 50 g/m ² ) was used instead of the above glass fiber mat. Antennas of Comparative Example 9 were manufactured in the same manner except that . The above Example 3 antenna was installed on the ground, and a transmitting antenna with a diameter of 40 cm was installed 100 m away from the antenna, and radio waves with a frequency of 12 GHZ were radiated in a beam shape to measure the radio wave gain. Comparative examples 6 to 9
The radio wave gain was similarly measured for the antenna. The results are shown in Table 1 below.

[Table] As is clear from Table 1 above, Comparative Example 6 uses too little glass fiber pine for the cushioning material, Comparative Example 7 uses too much fiberglass, and Comparative Example 8 uses cloth instead of pine. , and Comparative Example 9, in which no buffer material was used, both had lower radio wave gains than Example 3, and in particular, Comparative Examples 6 and 9 were significantly inferior. As described above, in this invention, a buffer material made of glass fiber or organic fiber is provided at least on the concave side of the conductive reflective material, so that the positional shift of the conductive reflective material does not occur during molding. Therefore, the antenna performance is improved by at least 1% compared to the case where no buffer material is used. In addition, since a pine-like material with a basis weight of 10 to 100 g/ ^m2 is used as a cushioning material, the weight increase of the antenna can be reduced compared to the case of using cloth as a cushioning material, and there is no directionality. , the occurrence of distortion is reduced, the antenna performance is improved, and furthermore, it is easy to impregnate with resin and is easy to process.

[Brief explanation of drawings]

The drawing is a sectional view of the main part of a mold showing an embodiment of the present invention. 1...male type, 2...female type, 3a, 3b...pine-shaped cushioning material, 4...conductive reflective material, 5...molding material.

Claims (1)

[Claims] 1. The basis weight obtained by stacking glass fibers or organic fibers to a uniform thickness in any direction on at least the concave side of a conductive reflective material, and bonding the fibers to each other at contact points.
1. A method for manufacturing a reinforced plastic parabolic antenna, characterized in that a pine-shaped cushioning material of 10 to 100 g/m ² is disposed and molded.