JPH0445283Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field]

The present invention relates to a reflector for a parabolic antenna that receives radio waves sent from a broadcasting satellite and supplies them to a television or the like.

[Conventional technology]

As a measure against difficult viewing, communication systems using broadcasting satellites have become popular. In this communication system, the receiving side requires equipment to receive the SHF band of satellite broadcasting, so a consumer parabolic antenna is used. Consumer parabolic antennas evolved from industrial parabolic antennas. Some industrial parabolic antennas have a reflector with a diameter of several meters, and are designed to be installed at high places and to withstand wind, etc., so they are made of steel or other materials to provide sufficient strength. It is built. It also incorporates a mechanism to automatically control the angle of elevation and azimuth of the reflector. This industrial parabolic antenna is designed to have low radio wave reflection efficiency, and some using mesh iron plates are also known.

[Problem that the invention aims to solve]

If the structure of such an industrial parabolic antenna is directly applied to a consumer antenna, the design will be unsophisticated and unsophisticated. Moreover, assembly and maintenance are difficult tasks for amateurs. For this reason, various improvements are required for each part of the consumer parabolic antenna, including the reflector. In particular, improvements to reflectors are desired in order to efficiently capture radio waves. For example, radio waves sent from a broadcasting satellite at an altitude of 38,000 km with a transmission power of about 100 watts become weak radio waves when they reach a consumer-use parabolic reflector. In order to receive these radio waves, although the efficiency is not required to be as high as that of an industrial parabolic reflector, a high radio wave capturing efficiency is required despite being small and lightweight with a diameter of about 50 to 70 cm. It is also necessary to smooth the surface to eliminate loss and concentrate the radio waves to the primary radiator. By the way, around the time of the vernal and autumnal equinoxes within a year, the direction of the parabolic reflector may coincide with the direction of the sun. In this state, sunlight is reflected in line with the axis of the parabolic reflector and concentrated within the horn of the primary radiator. Therefore, components such as the circularly polarized wave generator and BS converter may be destroyed by the heat of sunlight. This invention was devised with the aim of solving these problems, and by preventing the reflection of sunlight, it prevents thermal damage to parts such as circularly polarized wave generators and BS converters, and improves satellite performance. The purpose of the present invention is to provide a consumer-use parabolic reflector suitable for broadcast reception.

[Means to solve the problem]

In order to achieve this purpose, the parabolic reflector of the present invention has opaque fibers that reflect radio waves arranged at intervals, and the gaps between the fibers are filled with transparent plastic. and a surface layer provided on the surface side of the light-transmitting layer, in which transparent glass fibers are cast in transparent plastic. Here, as the reflective/transparent layer, a stack of multiple layers can be used. Furthermore, a holder layer made of glass fiber reinforced plastics may be laminated on the back side of the reflective/transparent layer.

[Effect]

The parabolic reflector of the present invention is made of a single synthetic resin plate shaped approximately in a bowl shape, and is therefore small and lightweight. Since radio waves are reflected by the plate-like body, the reflection efficiency is superior to that when a metal porous reflector is used. Moreover, since light passes through the plate-like body, thermal damage to the components of the primary radiator due to reflection of sunlight can be prevented. Furthermore, since a surface layer with a smooth surface is formed on the surface side of the reflective/transparent layer, both radio waves and sunlight can pass through the surface layer without causing diffuse reflection on the surface. , reflection and
Radio waves are reflected by the transparent layer and sent to the primary radiator, and sunlight is reflected and transmitted through the transparent layer.

【Example】

Hereinafter, the present invention will be specifically explained by way of examples with reference to the drawings. In this embodiment, as shown in FIG. 1, a primary radiator 2 is arranged at the lower part of the surface side of a plate-shaped body constituting a reflecting mirror of a parabolic antenna device 1. This primary radiator 2 is supported on the back side of the plate-like body 1 via a support arm 3. As shown in FIG. 2, the reflecting mirror is formed by forming a single plate-like member 4 made of synthetic resin into a substantially bowl-shaped offset shape. The plate-like body 4 is a laminate in which a holder layer 5, a reflective/transparent layer 6, and a surface layer 7 are integrated. The holder layer 5 is made of glass fiber reinforced plastic (GFRP), which is made by cross-weaving transparent glass fibers 5a and casting them in a transparent plastic 5b such as acrylic resin. This holder layer 5 is
It has excellent functionality and strength as a structure. In addition, since the glass fibers 5a are cross-woven,
In addition to improving the strength, the glass fibers are placed in close contact with each other within the transparent plastic 5b. Therefore, the straight transmittance of light increases. The thickness of the holder layer 5 is preferably such that it accounts for about 80% of the total thickness of the plate-like body 4 (approximately 3 mm). The reflective/transparent layer 6, as shown in FIG. 3, has opaque fibers 6a hardened with a transparent plastic 6b similar to that of the holder layer 5. The fibers 6a used are, for example, acrylic long fibers with a diameter of 5 μm with a metal such as aluminum coated on the surface by vacuum deposition or the like so that radio waves are reflected. The fibers 6a are randomly wrapped in opaque plastics 6b except for the fibers 6a, which are arranged along the direction perpendicular to the thickness direction of the reflective/transparent layer 6. The reflective/transparent layer 6 is provided on the surface side of the holder layer 5 and has a thickness that accounts for about 15% of the total thickness of the plate-like body 4. In order to increase the radio wave reflection efficiency, it is necessary to create a mesh of 1/100λ wavelength or less between the fibers 6a. For example, if the receiving frequency is 12 GHz and the wavelength is 25 mm, the squares will be 0.25 mm or less. However, when the opaque fibers 6a are brought into close contact with each other, the entire plate-like body 4 becomes opaque and cannot transmit light. Therefore, the opaque fibers 6a are arranged at such a distribution density that the back side of the plate-like body 4 can be seen through it when viewed from the front side, specifically, at a distribution density such that the light transmittance is about 50%. Furthermore, when viewed in the thickness direction from the surface side of the reflective/transparent layer 6, the mutual spacing between the opaque fibers 6a in the first row is as follows:
The mesh size is relatively coarse, specifically about 0.2 to 0.5 mm. The opaque fibers 6a are arranged in many layers in the thickness direction, and the positions of the layers are shifted from each other. That is, the opaque fibers 6a are arranged in a zigzag pattern without adhering to each other, and are evenly distributed within the transparent plastic 6b. Therefore, although the distance between adjacent opaque fibers 6a is relatively large, very fine gaps are formed between the opaque fibers 6a as a whole. Therefore, when considering the total process from when radio waves are incident on the surface of the reflective/transparent layer 6 to when they reach the back surface,
The gap through which the radio waves pass is, for example, the individual fiber 6a.
Even if the distance between adjacent fibers 6a is about 0.25 mm (250 μm), the distance is reduced to about 1/100 to 1/10,000/1 of the gap between each fiber 6a. As a result, the radio wave reflection efficiency is
It can be kept high enough. On the other hand, the wavelength of light is extremely short, 1 to 0.1 μm.
Therefore, the incident light passes through the transparent plastic 6b between the opaque fibers 6a and reaches the back side, as shown by the broken line arrow in FIG. Furthermore, some light having extremely short wavelengths passes straight through between the opaque fibers 6a, as shown by solid arrows in FIG. The transmission of these lights makes the plastic 6b bright, making it easier to see the scenery on the back side. The surface layer 7 is made of plastic 5b of the holder layer 5.
Transparent short glass fibers 7a are cast and hardened in plastics 7b similar to the above. This surface layer 7 has a function as a correction surface to finish the surface of the plate-like body into a smooth surface, and accounts for 5% of the total thickness of the plate-like body 4.
It occupies the following: In a parabolic reflecting mirror having such a structure, radio waves are reflected by the plate 4 as shown by the solid line in FIG. 1, and visible light such as sunlight is transmitted through the plate 4 as shown by the broken line. For example, the radio wave reflection efficiency was 98%, and the visible light transmission efficiency was over 50%. Therefore, the reflected light 1 does not concentrate on the primary radiator 2 even during the vernal equinox, the autumnal equinox, or the season around them, and the components of the primary radiator 2 can be protected from thermal damage. Further, the bowl-shaped plate-like body 4 is formed of a multi-layered fiber-reinforced plastic laminate, and has no holes or the like. Therefore, a small and lightweight reflecting mirror can be provided at low cost. Furthermore, as for the reflecting mirror as a whole, since the scenery on the back side can be seen through the plate-like body 4 from the front side,
The appearance will also be excellent. Note that as the transparent plastic, glass fiber, etc., colored transparent or translucent materials can be used as long as they allow light to pass through. It is preferable that the light transmittance of the plate-like body as a whole is maintained at 50% or more, and the radio wave reflection efficiency is maintained in the range of 97 to 99.7%.

[Effect of the idea]

As explained above, in the present invention, opaque fibers that reflect radio waves are arranged at intervals, and the surface of the reflective/transparent layer is filled with transparent plastic in the gaps between the fibers. Since a surface layer with a smooth surface is formed on the side to serve as a reflecting mirror, radio waves are reflected by the reflecting mirror, but light is transmitted through the reflecting mirror. Therefore, visible light such as sunlight is not reflected and concentrated on the primary radiator, and the components of the primary radiator are protected from thermal damage. Further, due to the distribution of the fibers, the radio wave reflectance and light transmittance are maintained high, and the mirror has sufficient strength despite being small and lightweight.

[Brief explanation of the drawing]

FIG. 1 is a schematic side sectional view showing an embodiment of the present invention, FIG. 2 is a partially enlarged sectional view of a reflecting mirror, and FIG. 3 is an enlarged sectional view of a reflective/light-transmitting layer. DESCRIPTION OF SYMBOLS 1... Parabolic antenna device, 2... Primary radiator, 3... Support arm, 4... Plate-like body, 5... Holder layer, 5a... Glass fiber, 5b... Plastics, 6... Reflection・Transparent layer, 6a... Opaque fiber, 6b... Plastics, 7... Surface layer,
7a...glass fiber, 7b...plastics.

Claims (1)

[Claims for Utility Model Registration] (1) A reflective/transparent layer in which opaque fibers that reflect radio waves are arranged at intervals, and the gaps between the fibers are filled with transparent plastic; A parabolic reflecting mirror characterized by comprising a surface layer formed by casting transparent glass fibers in transparent plastic, which is provided on the surface side of the light-transmitting layer. (2) A parabolic reflecting mirror characterized in that a holder layer made of glass fiber reinforced plastic is provided on the back side of the reflective/transparent layer according to claim 1.