KR910008947B1 - Antenna - Google Patents

Abstract

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Description

antenna

1 is a perspective view of a parabolic antenna which is an embodiment of the present invention.

2 is a partial cross-sectional view of the antenna of FIG.

3 is a schematic diagram showing an apparatus for testing the amount of reflection attenuation of an antenna.

4 is a graph showing the relationship between the angle A and the reflection attenuation amount R of the incident wave electron vector coming in opposite to the axial direction of the short carbon fibers included in the reflecting layer of the reflector.

5 is a graph showing the relationship between the length L and the reflection attenuation amount R of the short carbon fibers in the reflective layer.

6 shows the contents of the fiber X = W ₃ / (W ₃ + W ₁₂ ), where W ₃ is the weight of short carbon fibers 3 mm long and W ₁₂ is the weight of short carbon fibers 12 mm long and Graph showing the relationship between reflection attenuation (R).

7 is a graph showing the relationship between the density (D) and the amount of reflection attenuation (R) of the short carbon fibers in the reflective layer.

8 shows the relationship between the frequency (F) and the reflection attenuation amount R of the reflection layer A made of a resin in which 50% of short carbon fibers having a length of 3 mm and 50% of short carbon fibers having a length of 12 mm are dispersed and frequency ( A graph showing the relationship between F) and the reflection attenuation amount R of the reflective layer B made of a resin in which 100% of short carbon fibers having a length of 24 mm are dispersed.

9 is a rear view of the backing layer arranged in two directions such that glass fibers intersect at about 90 °.

10 is a rear view of the backing layer arranged in four directions such that glass fibers can intersect at about 45 °.

11 is a rear view of the backing layer in which the fabric is used.

* Explanation of symbols for main parts of the drawings

2: reflector 3: primary radiator

6: resin 7: short carbon fiber

8: parabolic surface 9: reflective layer

10: support layer

The present invention relates to an antenna, in particular, a parabolic antenna, that is, an antenna made of a reflector formed with a parabolic front face to transmit and receive a microwave or millimeter wave, such as a cassgrainian antenna. A reflector formed of a parabolic surface (radio wave reflecting surface) and a parabolic antenna composed of a primary radiator, that is, a caseinian antenna, are known in the past.

The reflector is formed of a reflective layer made of carbon fiber reinforced resin, and the resin is reinforced by a plate in which carbon fiber strands are arranged in parallel in a single direction, or reinforced by a fabric of carbon fiber.

However, these conventional antennas have a drawback in that the effect of transmission and reception is not constant due to the anisotropy of the wave to be received because the parabolic anisotropy of conductivity is so great.

In addition, polarization occurs because carbon yarns that transmit the conductivity of the radio waves to the reflectors are arranged in two directions, for example, along the axes of the yarns extending in the 0 ° and 90 ° directions. The parabolic antenna is made of 0.5mm thick carbon fiber reinforced resin and consists of a reflector having four reflective layers of layers arranged in parallel in a single direction.

When the fiber axes of the four plates described above are arranged to be 0 °, 90 °, or 90 °, 0 °, they are formed by the electron vector of the incoming wave opposite to the axial direction of the carbon fiber that constitutes the reflective layer. The relationship between the angle θ and the reflection attenuation amount R can be expressed as a dotted line in FIG. 4 to be described later. This relationship indicates that the amount of reflection attenuation is highly dependent on the direction of the carbon fibers.

To eliminate this drawback, parabolic surfaces are sometimes covered with aluminum foil, coated with nickel, or forming a thermal sprayed coating with zinc.

This type of antenna can eliminate the problem of electrical anisotropy because the metal is isotropic to conductivity. However, this type of antenna has a drawback in that durability is degraded because the metal is weak in weatherability, which may damage the coating or the thermal sprayed coating.

Accordingly, an object of the present invention is to provide an antenna that is highly durable and minimizes the effect of the transmission and reception of waves due to polarization in order to eliminate the aforementioned drawbacks of conventional antennas.

This object is achieved by the antenna of the present invention consisting of a parabolic surface and a reflector formed with a primary radiator. The foregoing reflector consists of a reflective layer formed of a parabolic surface and a backing layer attached to the rear surface of the reflective layer.

The foregoing reflector is formed of a base layer made of resin and short fibers (hereinafter referred to as short carbon fibers) of carbon fibers dispersed in the base layer, and the axes of the aforementioned fibers are actually parallel to the parabolic surface.

The composite of short carbon fiber and resin is a kind of carbon fiber reinforced resin. The primary radiator described above is located at the focal point of the paraboloid.

The length of the above-mentioned short carbon fiber is 5-25 mm, and it is preferable that the above-mentioned short carbon fiber is not sprayed from being separated or aggregated from each other.

The carbon fiber is a mixture of fibers having an average length of 5-25 mm and fibers having an average length of 1-5 mm. The antenna configured as described above according to the present invention is such that the reflecting layer of the reflector consists of a mixture of short carbon fibers and resin and the short carbon fibers are dispersed therein and extend in any direction, but are actually parallel to the parabolic plane. It retains phosphorus conductivity.

Therefore, in this antenna, the effect of wave transmission and reception hardly changes depending on the polarization direction.

In other words, the effects of wave transmission and reception are hardly affected by the direction of the polarization. When short carbon fibers having an average length of 5-25 mm and short carbon fibers having an average length of 1-5 mm are mixed, the conductivity becomes more isotropic, and the effect of transmitting and receiving waves will be even higher. However, since the carbon fiber composite has high weather resistance and does not degrade even when exposed to wind, rain and sun, the antenna according to the present invention can be said to be almost permanent.

Moreover, since the composite of carbon fiber and resin can be molded very easily, it is possible to mass-produce at a low price by drawing process.

Hereinafter, these objects and effects of the present invention will become more apparent based on the accompanying drawings.

FIG. 1 shows a parabolic antenna according to an embodiment of the present invention, which comprises a reflector 2 formed of a parabolic surface 8 and a primary radiator 3 located at the focal point of the parabolic surface 8. The guide wave 4 of the wave is provided to guide the microwave or millimeter wave from the primary radiator 3 to a continuous device such as a water pipe. 5 in the figure is a mount.

As shown in FIG. 2, the reflector 2 forms a parabolic surface 8 and includes a reflective layer 9 formed of a composite of short carbon fibers and a resin, and a glass fiber reinforced resin attached to the rear surface of the reflective layer 9. It consists of the support layer 10 formed.

Accordingly, the reflector 2 is composed of a reflective layer 9 of a composite of short carbon fiber and resin and a layered layer of the backing layer 10 of short glass fiber reinforced resin.

However, the composite of carbon fiber and resin may be a thermosetting resin (6) such as an epoxy resin, an unsaturated polyester resin, a phenol resin or a polyimide resin, or a thermoplastic resin (6) such as a polyamide resin or a polyalkyl resin and an average length of 5 It consists of -25 mm short carbon fibers 7, which are dispersed in a base layer made of the resin described above so that each fiber axis is actually parallel to the parabolic plane 8 described above. On the other hand, in the glass fiber reinforced resin described above, short glass fibers 11 having an average length of 10-50 cm are used, and the short glass fibers 11 are also arranged so that each fiber axis is parallel to the parabolic plane 8 actually described. It disperse | distributes to the resin 6 mentioned above.

The short carbon fiber 7 in the composite of the short carbon fiber and the resin serves as a conductive material for transmitting the conductivity to the reflective layer 9. It is also theoretically clear that the longer the carbon fiber 7 is, the better it is to ensure high conductivity.

However, too long fibers result in uneven dispersion, low conductivity and difficulty in forming. Therefore, the length of the carbon fiber 7 is preferably 25 mm or less. On the other hand, if the fiber is too short, the molding is good, but the conductivity decreases.

Therefore, the average length of the short carbon fibers 7 is preferably 5-25 mm, more preferably 10-20 mm. In terms of conductivity, the larger the ratio of the short carbon fibers 7 included in the composite of the carbon fibers and the resin, the better.

However, if the proportion of the carbon fiber is too large, the moldability is reduced, so a suitable ratio thereof is preferably 40-60% by volume based on the total volume of the reflective layer 9.

For short carbon fibers and resin composites, short carbon fibers with an average length of 5-25 mm are mixed with short carbon fibers with an average length of 1-5 mm and left by short carbon fibers with an average length of 5-25 mm in such composites. The space is filled with short carbon fibers having an average length of 1-5 mm. This composite not only reduces the anisotropy of the conductivity but also increases the conductivity of the parabolic surface 8.

In addition, short carbon fibers having an average length of 1-5 mm have little effect on formability. In order to ensure high molding, it is appropriate that the mixture of the carbon fibers described above is composed of 1-3 fibers having an average length of 1-5 mm with respect to one fiber having an average length of 5-25 mm in weight.

However, glass fiber reinforced resin using glass fiber serves to transmit mechanical force to the antenna. In the illustrated embodiment, glass fibers 11 with an average length of 10-50 cm are suitable in view of the moldable surface.

However, other structures of glass fibers may also be employed. Glass fibers are in the form of mats bound by a binder.

The weight per unit area of the mat is suitably 3-100 g / m 2. The glass thread plates 12 arranged in parallel in a single direction are layered, and the fiber axis direction of the glass thread plates 12 described above is about 0 °, 90 ° or 10 degrees as shown in FIG. It is arranged to be about 0 °, 45 °, -45 °, 90 ° as shown.

However, the use of fiberglass or thread is not inevitable. Fibers or yarns of alumina, silicon carbide or polyaramid may be used as well as glass fibers or yarns. The thread can also be used in the form of the fabric 13 shown in FIG. That is, glass fiber fabrics, alumina fiber fabrics, silicon carbide fiber fabrics, polyaramid fiber fabrics may also be used. Instead of fibre-reinforced resins, aluminum honeycomb or artificial honeycomb forms (such as honeycomb forms of paper made of poly-M-phenyline isophthalide) may also be used.

Antennas according to the invention can be manufactured in various ways and one of them is described herein. A short carbon fiber layer bound to a binder is formed on a glass fiber SMC (Sheet Molding Compound) having a thickness of several millimeters. It is a short carbon fiber mat layer and is manufactured by a general papermaking process.

Accordingly, the density (weight per unit area) of the short carbon fiber mat is suitably 30-100 g / m 2.

The unsaturated polyester resin film that has not yet been cured is then placed on this short carbon fiber mat and pressurized and heated to install and integrate the complete component into a molding formed into a parabolic surface, thereby producing a reflector. One antenna is produced when the wave guide, the primary radiator and the frame are attached to the reflector.

The antenna according to the present invention is useful for various purposes.

For example, it is used for microwave or millimeter wave communication via satellite and receiving antennas for broadcasting, radar, and television broadcasting.

Now, a laboratory example of reflection attenuation will be described below to account for all of the thresholds indicated above.

In the experiment, the reflection attenuation was measured as follows. SYNTHESIZED SIGNAL GENERATOR The high frequency signal generated by the HP 8672 A (12 ') is introduced into the wave guide using the adapter HP x 281 (13) from the Hewlett Packard. Transformed into microwaves.

The wave transmitted through the wave guide tube and taken out from the sample or blank copper plate 20 was divided into two parts by a directional coupler 14, one of which is an insulator. Impedance matching was carried out by the EH tuner 16 through 15, transformed into a current signal by a crystal stage 17, and detected by a YHP 4041 B pico-ammeter 18. .

The insulator 15 and the directional coupler 14 used here are products of Shimada Rika K. K., Ltd. The overall measurement system is controlled by a microcomputer ″ Apple II ″ 19, while the synthesized signal generator 12 ′ and the electrically pico-ammeter 18 are connected by GP-IB. The frequency is sweeped every 100 MHz by the synthesized signal generator 12 '. As detected by the pico-ammeter 18, the measured force of the reflected wave from the empty copper plate 20 at the primary and the reflected force from the sample at the secondary are memorized and, finally, each The reflectance (dB) of the sample minus the reflectance (dB) of the copper plate 20 at the frequency was calculated as the amount of reflection attenuation of the specimen, such as the output of the microcomputer.

In Test Examples 2 and 3 and 4, which will be described later, the data at 12 MHz are average values for 16 points taken at 100 MHz with a time from 11.5 Hz to 12.5 Hz.

As shown in FIG. 3, the sample and copper plate 20 were measured inserted between the flanges of the wave guide tube.

As indicated by the cross section of Fig. 3, they were fixed to the flange as bolts and nuts through holes 21 drilled at four edge points. The back side of the sample was terminated by non-reflective clusters 22 to suppress continuous reflected waves.

In the specimen and the copper plate 20, carbon fibers cut to different lengths (" Toraya " manufactured by Toray Industries, Inc.) were used by a general papermaking process, and a polyester resin was used in the binding machine.

The short carbon fiber mat produced in this way was saturated with epoxy resin No. 2500 manufactured by Toray Industries, Inc., and was heated under pressure to form a neil plate. When the mat has a density of about 50 g / m 2, the molded product is thickened to about 0.2 mm.

Carbon fibers were found to be 75% by weight and the remaining 25% were binders. The parameters and experimental results in the experiment are as follows.

Experimental Example 1

The change in the amount of reflection attenuation R with the electron vector angle θ of the linear polarized wave was measured and the result is shown in FIG. 4 and the solid line C in FIG. And the dotted line D relates to the conventional antenna mentioned above.

As shown in FIG. 4, the reflector according to the present invention has excellent reflectivity without directivity.

Experimental Example 2

The measurement of the reflection attenuation R was carried out by the fibers of the mat cut into lengths of 3, 6, 12, 24 and 48 mm, the frequency of 12 Hz and the mat density of about 50 g / m 2.

As shown in FIG. 5, when the cut length of the fiber is 25 mm or less, very good reflectivity is shown. The measured data are averages for 20 samples.

Experimental Example 3

It was measured using a mat produced experimentally with a mixture of carbon fibers cut to 3 mm and 12 mm. The mixed fiber mat had a density of about 50 g / m 2 and a frequency of 12 Hz.

The measured data are averages for 20 samples.

The results in FIG. 6 show that the best reflectivity is obtained in a 50%: 50% fiber blend system.

Experimental Example 4

When the density was changed to 10, 30, 50, 70, 90 g / m 2, the amount of reflection attenuation (R) on the 12 mm fiber mat was measured. The frequency was 12 Hz and the measured data were averaged over 20 samples.

The results are shown in Fig. 7, which shows that the higher the density, the better the reflectivity. The performance is excellent when the surface density is 50g / ㎡. The mat begins to saturate when the density is about 70 g / m 2.

Experimental Example 5

The amount of reflection attenuation according to the frequency is increased by making the mat (A) consisting of 50% of fiber having a length of 3 mm and 50% of fiber having a length of 12 mm and the mat (B) consisting of 100% of fiber having a length of 24 mm having a density of 50 g / m 2 ) Was compared.

The results are shown in FIG. The reflection attenuation amount R is preferably -0.2 dB or more.

The results of the experiment indicate that measurements at mat (B) are actually around the line of -0.2 (dB) while measurements of mat (A) are at the line of -0.2 (dB) at the same frequency.

This proves that the performance of the mat A is excellent as a reflector for a parabolic antenna.

While only one embodiment of the present invention has been described in detail, those skilled in the art can make many modifications to the embodiment without departing from the advantages and novel techniques of the present invention.

Claims (22)

A reflective layer 9 having a parabolic surface 8, dispersed in a base layer formed of a resin 6, and composed of short carbon fibers 7 parallel to the parabolic surface of each fiber axis, and the reflective layer And an reflector (2) formed of a backing layer (10) attached to the back surface and a primary radiator (3) positioned at the focal point of the parabolic surface. The antenna according to claim 1, wherein the average length of the carbon fibers (7) is 5-25 mm. The antenna according to claim 2, wherein the average length of the carbon fibers (7) is 10-20 mm. The base layer formed of the resin 6 has a parabolic surface 8, and a single carbon fiber having an average length of 1-5 mm and 5-25 mm is dispersed, and a reflective layer having parallel to the parabolic surface of each fiber axis ( 9), a reflector (2) composed of a backing layer (10) attached to the rear surface of the reflecting layer, and an antenna formed from a primary radiator (3) located at the focal point of the parabolic surface. The antenna according to claim 4, wherein the mixing ratio of the average length of the carbon fibers (7) of 5-25 mm and 1-5 mm is 1: 1 by weight. The antenna according to claim 1 or 4, wherein the carbon fibers (7) are contained in the reflective layer (9) in the form of a mat (MAT). The antenna according to claim 6, wherein the weight of the mat is 30-100 g / m2. The antenna according to claim 1 or 4, wherein the carbon fiber (7) is included in the reflective layer in the range of 40-60% of the volume based on the total volume of the reflective layer (9). 5. Antenna according to claim 1 or 4, characterized in that each of the single carbon fibers 7 is actually independent, is not agglomerated, does not overlap with each other, and does not intersect with neighboring fibers. . The antenna according to claim 1 or 4, wherein the resin (6) is a thermosetting resin. The antenna according to claim 10, wherein said thermosetting resin is selected from the group consisting of an epoxy resin, an unsaturated polyester resin, a phenol resin, and a polyamide resin. The antenna according to claim 1 or 4, wherein the resin (6) is a thermoplastic resin. 13. The antenna of claim 12 wherein the thermoplastic resin is selected from the group consisting of polyamide resins and polyalkyl resins. The antenna according to claim 1 or 4, wherein the support layer (10) is made of short fiber reinforced resin selected from the group consisting of glass fiber (11), alumina fiber, silicon carbide fiber and polyaramid fiber. 15. Antenna according to claim 14, characterized in that the carbon fibers (7) are randomly dispersed in the backing layer (10) and each fiber axis is actually parallel to the parabolic surface (8). 15. The antenna according to claim 14, wherein the average length of the glass fibers (11) is 10-50 cm. The antenna according to claim 1 or 4, wherein the support layer (10) is made of a thread yarn reinforced resin selected from the group consisting of glass thread, alumina thread, silicon carbide thread, and polyaramid thread. 18. Antenna according to claim 17, characterized in that the threads are arranged in two directions so that they can cross each other at about 90 [deg.], With the axes of each thread actually being parallel to the parabolic plane (8). 18. Antenna according to claim 17, characterized in that the threads are arranged in four directions so that they can intersect each other at about 45 [deg.], And the axes of each thread are actually parallel to the parabolic plane (8). The antenna according to claim 1 or 4, wherein the supporting layer (10) is a fabric reinforcement resin selected from the group consisting of glass fiber fabric, alumina fiber fabric, silicon carbide fabric and polyaramid fiber fabric. 5. Antenna according to claim 1 or 4, characterized in that the backing layer (10) is in the form of an aluminum honeycomb. The antenna according to claim 1 or 4, characterized in that the supporting layer (10) is artificially honeycombed.

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