JP5598879B2 - Linear polarization control method and apparatus - Google Patents

Description

  The present invention relates to a linearly polarized wave control method and apparatus, and more particularly to a linearly polarized wave control method and apparatus that can be used in a high frequency band and has a wide band and high specific strength.

  A polarization grating used in polarization diversity is a polarizer that transmits only radio waves polarized in a specific direction. A typical example of the polarization grating is a wire grid, and this wire grid has a large number of conductor wires arranged in parallel. When linearly polarized waves (vertical / horizontal polarized waves) are incident on these many conductor wires (metal wires and tapes are common), the direction of the polarization and the direction of the conductor wires are orthogonal In the case of transmission polarization, the radio wave is almost transmitted, and when the direction of polarization and the direction of the wire of the conductor are parallel, that is, in the same direction (in the case of shielded polarization), the radio wave is attenuated.

  Other conventional polarization gratings include those formed by etching a linear metal piece on a printed circuit board and those formed by punching a metal plate. Furthermore, metal filaments are arranged at predetermined intervals on either the warp or the weft of a woven fabric formed using a non-metallic fiber that can be fixed to a synthetic resin as disclosed in Patent Document 1. And forming a polarization-selective woven fabric having polarization selection characteristics of electromagnetic waves, and the polarization-selective woven fabric is composed of a single metal or a non-metallic fiber that can be fixed to a synthetic resin. There is a polarization grating characterized in that it is formed by curing with synthetic resin in combination with woven fabric or cotton.

Japanese Utility Model Publication No. 61-149413

  However, the conventional polarization grating has a problem that the band is narrow. In addition, since the conventional polarization grating is configured by the above-described method, there are problems that the number of manufacturing steps is large and the cost is high.

  Also, in the high frequency band, especially in the frequency band above the millimeter wave band such as millimeter wave and submillimeter wave, if the wire diameter of the conductor of the polarization grating is thick, the transmission amount of the transmission polarization decreases. There is a problem, and there is a problem that the shielding amount of the shielding polarization decreases when the wire interval of the conductor wire is wide. Therefore, in order to obtain sufficient characteristics as a polarization grating in the high frequency band, that is, when both the low loss characteristic during transmission and the shielding characteristic during blocking are satisfied, the wire diameter is reduced and the line spacing is reduced. Need to be narrowed. Generally, it is necessary to set the wire diameter to 1/10 or less of the wavelength and the line interval to 1/4 or less of the wavelength.

  A problem when trying to satisfy this condition in the high frequency band will be described by taking as an example a case where a linear metal piece is formed on a printed board by etching. When the 100 GHz band is used as the high frequency band, it is necessary to make the metal wire diameter 300 μm or less and the line spacing 750 μm or less even if simply calculated. Actually, since the synthetic resin has a wavelength shortening effect on the substrate, a thinner wire diameter and a narrower wire spacing are required. Therefore, even in the 100 GHz band, fine processing on the order of 100 μm or less is required, so that it is very difficult to manufacture, and even if it can be manufactured, there is a problem that the cost is further increased.

  Also, taking the invention described in Patent Document 1 as an example, when trying to satisfy this condition in the 100 GHz band, it is less than 100 μm to satisfy the same thin wire diameter (300 μm or less) and narrow line spacing (750 μm or less). Although fine processing on the order is required, the line spacing in this case is the line spacing of the metal wire. As described above, the invention described in Patent Document 1 includes metal filaments woven at regular intervals between non-metallic fibers, so even when the metal filaments are arranged most closely. It is necessary to interweave metal filaments and non-metallic fibers alternately. Considering the line spacing between the metal wire strips and the non-metallic fiber, a narrower line spacing is required, which makes it very difficult to manufacture in terms of technology.

  Furthermore, in the invention described in Patent Document 1, when a metal filament is woven, minute irregularities are generated by weaving. When this unevenness occurs, there is a problem in that the line spacing of the metal filaments slightly changes. Further, in order to obtain sufficient characteristics as a polarization grating particularly in a high frequency band, it is necessary to make the line intervals uniform and to keep a minute gap. Therefore, the invention described in Patent Document 1 also has a problem that polarization control is difficult in a high frequency band.

Moreover, this patent document 1 discloses that carbon fiber can also be used as a metal filament. CFRP (Carbon Fiber) is used to fix carbon fiber to synthetic resin.
Reinforced Plastics (carbon fiber reinforced plastic) is common. This CFRP is formed by evenly coating finely cut carbon fiber on plastic or other resin, or by infiltrating carbon fiber into plastic or other resin while keeping the fiber oriented. It is a material with high strength, that is, high specific strength.

  However, when the fiber direction of the carbon fiber to be used is unidirectional, CFRP is strong in pulling the carbon fiber in the fiber direction but weak in pulling in the direction perpendicular to the fiber (there is anisotropy in strength). There is a problem. For this reason, CFRP, which is generally used in general, is formed by laminating a plurality of plate-like fiber layers with different fiber directions, making the fibers themselves three-dimensional, and stitching between fiber layers. That is, it is configured by combining a plurality of carbon fibers having different fiber directions and knitting them so as to be orthogonal to form a mesh. The CFRP molded in this way is used in place of metal, taking advantage of its high specific strength, and is used for applications such as radio wave reflectors.

  Even if the carbon fiber used in this CFRP is used as a metal filament in the invention described in Patent Document 1, it is not a patent if the carbon fiber is simply replaced in place of the metal filament. It does not contribute at all to the solution of the above problems in the invention described in Document 1. Therefore, even if carbon fiber is used as the metal wire in the invention described in Patent Document 1, in the high frequency band, particularly in the frequency band of the millimeter wave band or higher, the production is technically difficult, and the cost is high. In addition, there is a problem in that it is difficult to satisfy the performance as a polarization grating and it is difficult to control polarization.

  The present invention has been made in view of the above-described problems. The structure and the manufacturing method are simple, low cost, can be used in a high frequency band, and have a high specific strength and a broadband linearly polarized wave. It is an object to provide a control method and an apparatus therefor.

In the invention according to claim 1, the fiber directions of the carbon fibers of the conductor are all uniformly distributed in a single direction, and the carbon fibers arranged in the single direction are immersed in the resin to improve the strength. when the formed fiber reinforced plastic using a fiber-reinforced plastic plate formed by molding into a plate, linearly polarized electric wave of high frequency band (above the millimeter-wave band) is incident on the fiber-reinforced plastic plate, carbon fiber When the direction of the fiber and the direction of polarization of the linearly polarized wave are orthogonal, the radio wave is transmitted. When the direction of the fiber of the carbon fiber and the direction of polarization of the linearly polarized wave are the same direction, the radio wave is attenuated. This is a method for controlling the characteristic linearly polarized wave.

According to the second aspect of the present invention, the fiber directions of the carbon fibers of the conductor are all uniformly distributed in a single direction, and the carbon fibers arranged in the single direction are immersed in the resin so as to improve the strength. formed by molding a fiber reinforced plastic formed in a plate shape made of fiber-reinforced plastic plate, when linearly polarized radio wave in the high frequency band (above the millimeter-wave band) is incident on the fiber-reinforced plastic plate, carbon fiber Radio waves are transmitted when the fiber direction and the polarization direction of the linearly polarized wave are orthogonal to each other, and when the fiber direction of the carbon fiber and the polarization direction of the linearly polarized wave are the same direction, the radio wave is attenuated. Is a polarization grating for controlling the linear polarization.

In the invention according to claim 3 , the fiber directions of the carbon fibers of the conductor are all uniformly distributed in a single direction, and the carbon fibers arranged in the single direction are immersed in the resin to improve the strength. fiber reinforced plastic in which the first fiber-reinforced plastic plate fiber reinforced plastic obtained by molding into a plate shape formed, the fibers of the radio wave transparent dielectric is formed so as to improve the strength immersed in the resin the consists of a second fiber reinforced plastic plate formed by molding into a plate, on both surfaces or one surface of the first fiber-reinforced plastic plate, a second fiber-reinforced plastic plate is laminated, the first fiber-reinforced plastic plate And a second fiber reinforced plastic plate are molded into an integral fiber reinforced plastic plate, and a fiber reinforced plastic in which linearly polarized radio waves in a high frequency band (millimeter wave band or higher) are integrated. When incident on the plate, the radio wave is transmitted, the polarization direction and the same direction of the fiber direction and the linear polarization of the carbon fibers when the the polarization direction of the fiber direction and the linear polarization of the carbon fibers orthogonal In this case, the radio wave is a polarization grating that controls linearly polarized waves, which is characterized by attenuation.

In the invention according to claim 4 , the fiber directions of the carbon fibers of the conductor are uniformly distributed in a single direction, and both sides or one side of the carbon fiber layer arranged in a single direction and formed into a plate shape is provided. A dielectric layer that is transparent to radio waves is laminated, and the carbon fiber layer and dielectric layer of a conductor arranged in a single direction are immersed in a resin to improve the strength and are integrally formed in a plate shape The fiber direction of the carbon fiber and the polarization direction of the linearly polarized wave when the linearly polarized radio wave in the high frequency band (millimeter wave band or more) is incident on the fiber reinforced plastic plate. Is a radome that controls linearly polarized waves, characterized in that radio waves are transmitted when they are orthogonal to each other, and when the fiber direction of carbon fiber and the polarization direction of linearly polarized waves are the same, the radio waves are attenuated. is there.

In the invention according to claim 5 , the fiber directions of the carbon fibers of the conductor are all uniformly distributed in a single direction, and the carbon fibers arranged in the single direction are immersed in the resin so as to improve the strength. A first fiber reinforced plastic plate formed by forming a fiber reinforced plastic into a plate shape, and a fiber reinforced plastic formed so as to improve strength by mixing electromagnetically transparent dielectric fibers into the resin. A second fiber reinforced plastic plate formed into a plate shape, and the first fiber reinforced plastic plate and the second fiber reinforced plastic plate are laminated on both sides or one side of the first fiber reinforced plastic plate. The fiber-reinforced plastic plate is molded so that the fiber-reinforced plastic plate is integrated with the fiber-reinforced plastic plate and linearly polarized radio waves in the high frequency band (millimeter wave band or higher) are integrated. When incident on the plate, the radio wave in the case where the polarization direction of the fiber direction and the linear polarization of the carbon fibers orthogonal to transmitted, if the polarization direction of the fiber direction and the linear polarization of the carbon fibers in the same direction Is a radome that controls linearly polarized waves characterized in that radio waves are attenuated.

The invention according to claim 6 is the radome for controlling linearly polarized waves according to any one of claims 4 to 5 , wherein the radio wave transparent dielectric is a glass fiber .

Since the invention according to claim 1, claim 2 and claim 3 is configured as described above, it is possible to control linearly polarized waves with a simple and simple structure and at low cost. Furthermore, it is broadband. In addition, while the fibers themselves are conductive, each individual fiber is surrounded by resin and does not conduct, so that it is possible to satisfy a narrow wire diameter and a narrow line spacing. Waves can be controlled and can operate as a polarization grating. Furthermore, it has excellent high specific strength, and polarization selection characteristics of 20 dB or more can be easily obtained. Further, since the direct current resistance of the fiber itself is several Ω to several tens of Ω, the direct current has conductivity, but for alternating current, each one operates as a fiber and does not have conductivity. Therefore, the linearly polarized wave can be blocked or transmitted, and at the same time, when the electrostatic discharge or lightning strikes, the current can be safely released.

Since the invention according to claim 6 is configured as described above, it has the same effect as the invention according to claims 1, 2 and 3 . Furthermore, it has excellent high specific strength, and polarization selection characteristics of 20 dB or more can be easily obtained.

Since the inventions according to claims 4 and 5 are configured as described above, a radome having the effects of the inventions according to claims 1, 2, and 3 can be obtained.

FIG. 5 is a diagram illustrating an example of the present invention and a result of transmission attenuation of a polarization grating using the linearly polarized wave control method according to the present invention. FIG. 5 is a diagram illustrating an example of the present invention and a result of transmission attenuation of a polarization grating using the linearly polarized wave control method according to the present invention. FIG. 4 is a schematic diagram showing a method for measuring the transmission attenuation of the polarization grating with respect to the angle between the fiber direction of the polarization grating and the polarization direction of the radio wave when the polarization grating is rotated. is there. FIG. 7 is a diagram illustrating an example of the present invention, and is a diagram illustrating a result of transmission attenuation of a polarization grating with respect to an angle between a fiber direction of the polarization grating and a polarization direction of a radio wave when the polarization grating is rotated. FIG. 5 is a schematic diagram illustrating an embodiment of the present invention, in which a polarization grating using the linearly polarized wave control method according to the present invention is applied to a radome.

  A first fiber reinforced plastic plate in which a fiber reinforced plastic formed so as to improve the strength by immersing the conductor fiber in the resin is formed into a plate shape and a dielectric fiber transparent to the radio wave in the resin. And a second fiber reinforced plastic plate formed into a plate of fiber reinforced plastic formed so as to improve the strength by mixing in the fiber, the fiber direction of the conductor fiber is unidirectional, and the first fiber reinforced A second fiber reinforced plastic plate is laminated on both sides or one side of the plastic plate, and the first fiber reinforced plastic plate and the second fiber reinforced plastic plate are formed into an integral fiber reinforced plastic plate, When the struck radio waves are incident on the integrated fiber reinforced plastic plate, if the fiber direction and the polarization direction of the linear polarization are orthogonal, the radio wave is almost transmitted, and the polarization of the fiber direction and the linear polarization is Radome If the direction is the same direction radio wave having a polarization grating and its polarization grating to control the linear polarization, characterized in that the attenuation. The conductor fiber is carbon fiber, and the radio wave transparent dielectric is glass fiber.

An embodiment of the present invention will be described in detail with reference to FIG.
FIG. 1 shows an embodiment of the present invention, and is a diagram showing a result of transmission attenuation of a polarization grating using the linearly polarized wave control method according to the present invention. Here, FIG. 1 is a diagram showing the results when the measurement frequency range is 400 MHz to 6 GHz.

  First, the inventors prepared a CFRP (Carbon Fiber Reinforced Plastics) plate necessary for forming a polarization grating using the linearly polarized wave control method according to the present invention. This CFRP plate is not a CFRP plate that is generally used, that is, a combination of a plurality of carbon fibers having different fiber directions, which are knitted so as to be orthogonal to each other and formed into a mesh shape. The CFRP plate necessary for forming a polarization grating using the linearly polarized wave control method according to the present invention has a single fiber direction of carbon fiber. In addition, as described above, the carbon fiber having a unidirectional fiber direction is weak in tensile in the direction perpendicular to the fiber (there is anisotropy in strength), so the CFRP plate used in this example is measured. For this purpose, a CFRP plate formed into a mesh shape that is generally used for convenience is reinforced with an outer frame. In this embodiment, the CFRP plate necessary for the polarization grating is a CFRP plate having a thickness of 0.1 mm. The carbon fiber wire diameter of the CFRP plate is 10 μm or less, and the carbon fiber is uniformly distributed on the CFRP plate. The inventors measured the direct current resistance in the direction perpendicular to the fiber direction of the carbon fiber of the CFRP plate, and the direct current resistance was several Ω to several tens of Ω.

  Next, the inventors prepared an electromagnetically shielded case (hereinafter simply referred to as a shield case), and measured the transmission attenuation of this CFRP plate necessary for forming a polarization grating. . The shielding case is provided with an opening, and a CFRP plate is set so as to close the opening, and an oscillator is installed inside the shielding case, and a radio wave transmitted through the CFRP plate from the opening of the shielding case is received by the receiving antenna. The attenuation by the CFRP plate was measured. The measurement results of transmission attenuation with this CFRP plate are shown in FIG.

In FIG. 1, the horizontal axis represents frequency, and the vertical axis represents transmission attenuation by the CFRP plate. FIG. 1 shows the results when the measurement frequency range is 400 MHz to 6 GHz. In FIG.
-○-○-is a characteristic when the radio wave is horizontally polarized and the fiber direction of the CFRP plate is vertical, that is, when the polarization and the fiber direction of the CFRP plate are orthogonal,
― ■ ― ■-is a characteristic when the radio wave is horizontally polarized and the fiber direction of the CFRP plate is horizontal, that is, when the polarization and the fiber direction of the CFRP plate are the same direction,
― ● ― ●-is the characteristic when aluminum plate is used instead of CFRP plate. This aluminum plate has almost the same electrical conductivity as the CFRP plate, and corresponds to the properties of a commonly used CFRP plate, that is, a CFRP plate formed in a mesh shape. Is also shown.

  From the results shown in FIG. 1, when the radio wave is horizontally polarized and the fiber direction of the CFRP plate is vertical, the transmission attenuation is 6 dB or less, while the radio wave is horizontally polarized and the fiber direction of the CFRP plate is also In the horizontal case, the transmission attenuation is 20 dB to 40 dB.

  Further, in FIG. 1, when the radio wave is horizontally polarized and the fiber direction of the CFRP plate is vertical, that is, when the polarization is perpendicular to the fiber direction of the CFRP plate, the radio wave is horizontally polarized and the CFRP plate. When the fiber direction is horizontal, that is, when the polarization and the fiber direction of the CFRP plate are in the same direction, the difference in the characteristic is 20 dB in any frequency band of the measurement frequency range 400 MHz to 6 GHz. That is all.

  Therefore, the linearly polarized wave control method according to the present invention transmits almost all of the fibers of the CFRP plate, that is, the polarization orthogonal to the fiber direction of the polarization grating, and can greatly attenuate the polarization from the same direction. In addition, it has a polarization selection characteristic of 20 dB or more. In addition, the measurement frequency range of 400 MHz to 6 GHz is about 4 octaves, and has the polarization selection characteristics as described above within this range. The wave grating has been found to be sufficiently broadband.

A second embodiment of the present invention will be described in detail with reference to FIG. In the second embodiment of the present invention, as described in the first embodiment, the broadband linear polarization control method according to the present invention having a polarization selection characteristic in the range of 4 octaves has a wider bandwidth. In order to confirm, transmission attenuation was measured in the millimeter wave band as in the first embodiment.
The same parts as those in the first embodiment are denoted by the same names and the same numbers, and the description thereof is omitted.

  FIG. 2 shows an embodiment of the present invention, and is a diagram showing the results of transmission attenuation of a polarization grating using the linearly polarized wave control method according to the present invention, as in FIG. Here, FIG. 2 is a figure which shows a result in case the measurement frequency range is 75 GHz-110 GHz band.

  In this example, a CFRP plate similar to that of the first example was prepared. As a measurement method, a free space method was used in which a transmission antenna and a reception antenna are placed facing each other in an anechoic chamber, and a transmission loss is measured by installing a CFRP plate in front of the reception antenna. And the transmission attenuation amount by the CFRP board was measured in the measurement frequency range in the millimeter wave band (W band 75 GHz to 110 GHz).

In FIG. 2, as in FIG. 1, the horizontal axis represents frequency, and the vertical axis represents transmission attenuation by the CFRP plate. FIG. 2 shows the results when the measurement frequency range is 75 GHz to 110 GHz. In FIG.
The solid line part is a characteristic when the radio wave is horizontally polarized and the fiber direction of the CFRP plate is vertical, that is, when the polarization and the fiber direction of the CFRP plate are orthogonal,
The broken line portion indicates the characteristics when the radio wave is horizontally polarized and the fiber direction of the CFRP plate is horizontal, that is, when the polarization and the fiber direction of the CFRP plate are in the same direction.

  As shown in FIG. 2, when the radio wave is horizontally polarized and the fiber direction of the CFRP plate is vertical, the transmission attenuation is 5 dB to 10 dB. On the other hand, when the radio wave is horizontally polarized and the fiber direction of the CFRP plate is also horizontal, the transmission attenuation is 40 dB or more. However, as shown in FIG. 2, the measurement system used for measurement in this example has a measurement limit of about 40 dB. Therefore, in reality, when the radio wave is horizontally polarized and the fiber direction of the CFRP plate is also horizontal, that is, when the polarization and the fiber direction of the CFRP plate are the same direction, the transmission attenuation will be larger. It is done.

  Further, in FIG. 2, as in FIG. 1 in the first embodiment, the characteristics when the polarization and the fiber direction of the CFRP plate are orthogonal to each other, and the case where the polarization and the fiber direction of the CFRP plate are the same direction. When compared with the above characteristics, the difference in the characteristics is 30 dB to 40 dB or more in any frequency band of the measurement frequency range of 75 GHz to 110 GHz. Therefore, the linearly polarized wave control method according to the present invention has a polarization selection characteristic of 30 dB to 40 dB or more in the measurement frequency range of 75 GHz to 110 GHz even in consideration of the measurement limit.

  From the first embodiment and the second embodiment described above, the polarization grating using the linearly polarized wave control method according to the present invention has a very wide band from the UHF band (300 MHz to 3 GHz) to the millimeter wave band. It has polarization selection characteristics in the frequency range and can operate as a very wide band polarization grating. Further, since the carbon fiber wire diameter of the CFRP plate used as the polarization grating in the first and second embodiments is 10 μm or less as described above, it is theoretically polarized up to about 3000 GHz. It can be used as a grid. Therefore, theoretically, it can be used as a polarization band having a very wide band with an operating range of several MHz to 3000 GHz.

A third embodiment of the present invention will be described in detail with reference to FIGS.
The third embodiment of the present invention is a polarization grating with respect to the angle between the fiber direction of the polarization grating and the polarization direction of the radio wave when the polarization gratings of the first and second embodiments are rotated. This is a measurement of the transition of transmission attenuation.
In addition, about the same part as the 1st Example and the 2nd Example, the same name and the same number are used and the description is abbreviate | omitted.

  FIG. 3 shows an embodiment of the present invention. The angle between the fiber direction of the polarization grating and the polarization direction of the radio wave when the polarization gratings of the first and second embodiments are rotated. FIG. 4 is a schematic diagram showing a method for measuring the transmission attenuation of the polarization grating with respect to FIG. 4, and FIG.

  In FIG. 3, the inventors enter a linearly polarized radio wave 2 into the polarization grating 1, rotate the polarization grating 1, and the polarization direction of the incident radio wave 2 with the fiber direction 3 of the polarization grating 1. The transmission attenuation by the polarization grating 1 at an angle 5 with the direction 4 was measured. The polarization grating 1 is the same as the first and second embodiments (CFRP plate). In this embodiment, the frequency of the incident wave to the polarization grating 1 is 4.4 GHz, and the transmission attenuation is measured by rotating the polarization grating 1 in steps of 15 degrees.

  The measurement results are shown in FIG. In FIG. 4, the horizontal axis indicates the angle between the fiber direction of the polarization grating and the polarization direction of the radio wave. When the fiber direction of the polarization grating and the polarization direction of the radio wave are parallel, that is, in the same direction. Is defined as 0 degree, and 90 degrees when the fiber direction of the polarization grating and the polarization direction of the radio wave are orthogonal to each other. In FIG. 4, the vertical axis indicates the transmission attenuation amount by the polarization grating 1.

  From FIG. 4, the linear polarization control method according to the present invention transmits almost when the fiber direction of the polarization grating 1 and the polarization direction are orthogonal to each other, and the fiber direction of the polarization grating 1 and the polarization direction are When it is in the same direction, it has a characteristic of greatly attenuating, and the transmission attenuation characteristic between the case where the fiber direction of the polarization grating 1 and the polarization direction are orthogonal to the case of the same direction also changes stepwise. Turned out to be.

  In the third embodiment, one polarization grating is rotated, and the attenuation is changed depending on the angle between the fiber direction of the polarization grating and the polarization direction of the radio wave incident on the polarization grating. However, it is not limited to this aspect. For example, by combining two polarization gratings, the incident radio wave is configured such that the fiber direction of one polarization grating and the fiber direction of the other polarization grating can be rotated from the same direction to a direction orthogonal to each other. You may make it change the transmission attenuation amount with respect to.

A fourth embodiment of the present invention will be described in detail with reference to FIG.
The fourth and subsequent embodiments of the present invention are embodiments that describe application examples of the polarization gratings of the first to third embodiments. In addition, about the same part as 1st Example-3rd Example, the same name and the same number are used and the description is abbreviate | omitted.

  The fourth embodiment of the present invention is an application example in which the polarization gratings of the first to third embodiments are used for a radome.

FIG. 5 shows an embodiment of the present invention, and is a schematic diagram when a polarization grating using the linearly polarized wave control method according to the present invention is applied to a radome.
In FIG. 5, the radome 10 includes a polarization grating 11 and a reinforcing portion 12. As in the first to third embodiments, the polarization grating 11 uses CFRP in which the fiber direction of the carbon fiber is unidirectional. However, unlike the first to third embodiments, the polarization grating 11 of this embodiment is reinforced by using a generally used mesh-shaped CFRP plate as an outer frame. Not in. Accordingly, as described above, the polarization grating 11 is weak (is anisotropic in strength) in tension in a direction orthogonal to the fiber direction of the carbon fiber.

The reinforcing portion 12 is formed on both surfaces of the polarization grating 11 in order to reinforce the polarization grating 11. In this embodiment, the reinforcing portion 12 is made of GFRP (Glass Fiber) which is relatively inexpensive and excellent in radio wave transmission.
Reinforced Plastics (glass fiber reinforced plastic) is used. The reinforcing portion 12 is not limited to the GFRP, and is excellent in radio wave transmission, that is, a dielectric member that is transparent in radio waves, and is weak in the polarization grating 11 having strength anisotropy. What is necessary is just to have the intensity | strength which reinforces intensity | strength.

  By configuring the radome 10 as described above, only the linearly polarized radio wave polarized in the direction orthogonal to the fiber direction of the polarization grating 11 is transmitted to the incident radio wave 2 and polarized from the same direction. Has a polarization selection characteristic that can be significantly attenuated, and provides a radome with a wide band and excellent high specific strength. Further, since the radome 10 has the polarization selection characteristic, it is not necessary to prepare an antenna having the polarization selection characteristic when performing polarization diversity reception. Since an antenna having polarization selection characteristics is complicated and expensive, the radome 10 has polarization selection characteristics, so that the cost of the antenna and radome as a whole can be reduced with a simple structure.

  In addition, since the DC grating has a DC resistance in the direction orthogonal to the fiber direction of the carbon fiber of the CFRP plate used in the polarization grating 11 as described above, the polarization grating 11 has conductivity in this direction. Therefore, although direct current has electrical conductivity, each of the alternating currents operates as a fiber and does not have electrical conductivity, so that it can block or transmit linearly polarized waves, and at the same time In the event of electrostatic discharge or lightning strike, these currents can be safely released. On the other hand, a generally used polarization grating using a metal wire has conductivity in the direction of the metal wire, but does not have conductivity in a direction perpendicular to the direction of the metal wire. Therefore, when it is configured to have conductivity in a direction perpendicular to the line direction of the metal wire as in the present application, a conductor such as a metal wire is required to ensure conductivity in this direction. However, in the case of such a configuration, a polarization grating using a generally used metal wire cannot operate as a polarization grating.

  In this embodiment, the reinforcing portions 12 are formed on both surfaces of the polarization grating 11. However, the reinforcing portions 12 may be formed only on one surface of the polarization grating 11 as long as sufficient strength can be secured. Further, when the radome 10 is constructed, the reinforcing portion 12 is used on both sides or one side of a layer of a plate-like carbon fiber (fiber direction is unidirectional) in the CFRP plate used in the polarization grating 11. The radome 10 may also be configured by laminating a plate-like glass fiber layer in the GFRP, and then immersing the carbon fiber layer and the glass fiber layer together in a resin and molding it as a reinforced plastic. Good.

  In the third and subsequent embodiments, application examples using a polarization grating for controlling linearly polarized waves according to the present invention are exemplarily shown. However, the present invention is not limited to this. The method for controlling linear polarization and the polarization grating using this method according to the present invention can be applied to all applications using the polarization grating.

  The linearly polarized wave control method and apparatus according to the present invention can be widely used in the technical field of performing polarization diversity reception and transmitting / receiving by selecting only a specific linearly polarized wave.

1, 11 Polarization grating 10 Radome

Claims (6)

A fiber reinforced plastic plate is formed so that the fiber direction of the carbon fiber of the conductor is uniformly distributed in a single direction, and the carbon fiber arranged in the single direction is immersed in the resin to improve the strength. Using a fiber reinforced plastic plate molded into a shape,
When linearly polarized radio waves in the high frequency band (millimeter wave band or higher) are incident on the fiber reinforced plastic plate,
When the fiber direction of the carbon fiber and the polarization direction of the linear polarization are orthogonal, the radio wave is transmitted,
The method of controlling linear polarization, wherein the radio wave is attenuated when the fiber direction of the carbon fiber and the polarization direction of the linear polarization are the same direction. A fiber reinforced plastic plate is formed so that the fiber direction of the carbon fiber of the conductor is uniformly distributed in a single direction, and the carbon fiber arranged in the single direction is immersed in the resin to improve the strength. It consists of a fiber reinforced plastic plate molded into a shape,
When linearly polarized radio waves in the high frequency band (millimeter wave band or higher) are incident on the fiber reinforced plastic plate,
When the fiber direction of the carbon fiber and the polarization direction of the linear polarization are orthogonal, the radio wave is transmitted,
The polarization grating for controlling linear polarization, wherein the radio wave is attenuated when the fiber direction of the carbon fiber and the polarization direction of the linear polarization are the same direction. A fiber reinforced plastic plate is formed so that the fiber direction of the carbon fiber of the conductor is uniformly distributed in a single direction, and the carbon fiber arranged in the single direction is immersed in the resin to improve the strength. A first fiber-reinforced plastic plate formed into a shape;
It consists of a second fiber reinforced plastic plate formed by molding a fiber reinforced plastic formed so as to improve the strength by immersing a dielectric fiber transparent in radio waves into a resin,
One or both sides of said first fiber-reinforced plastic plate, said second fiber-reinforced plastic plate is laminated, the first fiber-reinforced plastic plate and the second fiber-reinforced plastic plate and is integral with the fiber-reinforced plastic Molded into a plate,
When a linearly polarized radio wave in the high frequency band (millimeter wave band or higher) is incident on the integrated fiber reinforced plastic plate,
When the fiber direction of the carbon fiber and the polarization direction of the linear polarization are orthogonal, the radio wave is transmitted,
The polarization grating for controlling linear polarization, wherein the radio wave is attenuated when the fiber direction of the carbon fiber and the polarization direction of the linear polarization are the same direction. Conductor carbon fiber fiber direction is uniformly distributed in a single direction, and is disposed in a single direction and is transparent in radio waves on both sides or one side of a plate-shaped carbon fiber layer. The fiber reinforced plastic is formed in a single plate shape so as to improve the strength by immersing the carbon fiber layer of the conductor disposed in the unidirectional direction and the dielectric layer in a resin. Made of plates,
When linearly polarized radio waves in the high frequency band (millimeter wave band or higher) are incident on the fiber reinforced plastic plate,
When the fiber direction of the carbon fiber and the polarization direction of the linear polarization are orthogonal, the radio wave is transmitted,
The radio wave is attenuated when the fiber direction of the carbon fiber and the polarization direction of the linearly polarized wave are in the same direction. A fiber reinforced plastic plate is formed so that the fiber direction of the carbon fiber of the conductor is uniformly distributed in a single direction, and the carbon fiber arranged in the single direction is immersed in the resin to improve the strength. A first fiber-reinforced plastic plate molded into a shape;
It consists of a second fiber-reinforced plastic plate that is formed from a fiber-reinforced plastic that is formed so as to improve strength by mixing dielectric fibers transparent to radio waves into the resin,
One or both sides of said first fiber-reinforced plastic plate, said second fiber-reinforced plastic plate is laminated, the first fiber-reinforced plastic plate and the second fiber-reinforced plastic plate and is integral with the fiber-reinforced plastic Molded into a plate,
When a linearly polarized radio wave in the high frequency band (millimeter wave band or higher) is incident on the integrated fiber reinforced plastic plate,
When the fiber direction of the carbon fiber and the polarization direction of the linear polarization are orthogonal, the radio wave is transmitted,
The radio wave is attenuated when the fiber direction of the carbon fiber and the polarization direction of the linearly polarized wave are in the same direction. The radome for controlling linearly polarized waves according to any one of claims 4 to 5 , wherein the radio wave transparent dielectric is a glass fiber.

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