JP2009006863A - Radar cross-section reducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radar cross-section reducing device capable of reducing the radar cross-section of a radar target. <P>SOLUTION: The radar cross-section reducing device has a cover member 1 in which a plurality of flat reflective surface parts are continuously provided in a corrugated plate shape to reflect the whole or a part of the incident radar wave. The cover member 1 covers the whole or a part of the radar target to reduce the radar cross-section of the radar target. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a radar wave reflection area reduction device that reduces a radar wave reflection area.

  Conventionally, as a technique for reducing the reflection area of a radar wave, for example, “a curtain body made of a sheet material and a radio wave absorber that absorbs radio waves, and the radio wave absorber is divided into a plurality of plates, A stealth curtain characterized by forming a bag-like pocket for housing the radio wave absorber "has been proposed (see, for example, Patent Document 1). In this technique, the opening is covered with a stealth curtain that prevents radio waves from being reflected, and the radar wave reflection area is reduced.

  Further, for example, “a stealth curtain that shields the opening of a ship, a tension applying unit that applies tension to the stealth curtain that shields the opening, and a storage unit that stores the stealth curtain, and a radio wave is transmitted to the stealth curtain. An opening shielding device for a stealth ship characterized by including a radio wave absorber to absorb "has been proposed (see, for example, Patent Document 2). This technique covers an opening using an opening blocking device and suppresses reflection of a radar wave in the front direction as much as possible to reduce a radar wave reflection area.

  Also, for example, “a stealth ship with an upper structure and combat equipment on the exposed deck of the main hull, and a cover member covering the combat equipment during normal times, A stealth ship characterized in that it is configured to move to "is proposed (see, for example, Patent Document 3). This technology is a technology to cover with a cover with stealth, in order to improve the stealth when it is necessary (when using), divided into equipment required during normal times and equipment required during the war. Is moved (moved).

JP 2002-68082 A (Claim 1) JP 2002-19696 A (Claim 1) Japanese Patent Laying-Open No. 2005-125985 (Claim 1)

  In general, a structure or a moving object (for example, a ship) serving as a radar target causes regular reflection or irregular reflection when a radar wave reaches a projection or a plane portion of the structure or the like. (Radar cross-section: RCS) is large, and there is a problem that it is easy to detect a device (hereinafter referred to as “radar”) that detects a radar wave.

  In addition, the conventional radar wave reflection area reduction as described above is to cover the entire equipment so as to absorb the radar wave from the radar, or attach the cover with an inclination and reflect it to the front. Although the radar wave reflection area is reduced by suppressing the radar wave, the radar wave cannot be completely absorbed, and if the positional relationship between the inclined cover and the radar changes, the front of the radar There was a problem that the reflected wave to (the reflected wave returning to the radar) could not be reduced.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain a radar wave reflection area reduction device that can reduce the radar wave reflection area of a radar target.

  A radar wave reflection area reducing device according to the present invention includes a cover member that is formed into a corrugated plate by connecting a plurality of flat reflection surface portions, and that reflects all or part of an incident radar wave, The cover member covers all or part of the radar target and reduces the radar wave reflection area of the radar target.

  Further, in the radar wave reflection area reducing device according to the present invention, the cover member includes a reflected wave in a normal direction of one reflection surface portion of the plurality of reflection surface portions, and one or a plurality of reflections other than the reflection surface portion. The reflected wave in the normal direction of the surface part interferes with the phase and cancels and attenuates, thereby reducing the radar wave reflection area of the radar target.

  Further, in the radar wave reflection area reducing device according to the present invention, the cover member is formed such that at least two of the plurality of reflection surface portions have the same normal direction, and Among the reflection surface portions formed in the same normal direction, the distance difference in the normal direction between adjacent reflection surface portions is a distance at which each reflected wave of the adjacent reflection surface portions is phase-interfered and offset and attenuated. It is formed as follows.

  Further, in the radar wave reflection area reducing device according to the present invention, the cover member is formed such that at least two of the plurality of reflection surface portions have the same normal direction, and Of the reflection surface portions formed in the same normal direction, the distance difference in the normal direction between adjacent reflection surface portions is formed to be a distance corresponding to an odd multiple of a quarter wavelength of the radar wave. Is.

  In the radar wave reflection area reducing device according to the present invention, the cover member covers all or part of the structure of the ship and reduces the radar wave reflection area of the structure.

  Moreover, in the radar wave reflection area reducing device according to the present invention, the cover member is disposed to be inclined with respect to the vertical direction.

  In the radar wave reflection area reducing device according to the present invention, the cover member is provided with a radio wave absorber that absorbs at least a part of the radar wave at a ridge line portion between the reflection surface portions.

  In the radar wave reflection area reducing device according to the present invention, the cover member is formed by a radio wave absorber that absorbs at least a part of the radar wave at a ridge line portion between the reflection surface portions.

  In the radar wave reflection area reducing device according to the present invention, the cover member is composed of a radio wave absorber that absorbs at least a part of the radar wave or a radio wave reflector that reflects the radar wave.

  Further, in the radar wave reflection area reducing device according to the present invention, the cover member is composed of a plate body of wood or honeycomb structure and the radio wave absorber or the radio wave reflector bonded to the surface of the plate body. is there.

  In the radar wave reflection area reducing device according to the present invention, each of the cover members is formed of a flat plate, and the plurality of flat plates are joined to form a corrugated plate.

  The present invention covers a radar target object in whole or in part by a cover member that is formed into a corrugated plate by connecting a plurality of flat reflecting surface portions and reflects all or part of the incident radar wave. As a result, the radar wave reflection area of the radar target can be reduced.

Embodiment 1 FIG.
The radar wave reflection area reduction device according to the present invention includes a cover member, and covers or entirely covers a structure in a ship as a radar target by the cover member, thereby reducing the radar wave reflection area of the structure. Is. Hereinafter, in this Embodiment 1, the case where it applies to a receiving device (offshore receiving device) is demonstrated as a ship structure which reduces a radar wave reflective area. The structure for reducing the radar wave reflection area is not limited to this, and other structures may be used. Further, the radar target is not limited to a ship, but may be another moving body.

FIG. 1 is a schematic configuration diagram of a cover member according to the first embodiment. As shown in FIG. 1, the cover member 1 is a flat plate that constitutes a reflection surface portion, and is formed into a corrugated plate by joining a plurality of cover plates 10 that reflect all or part of incident radar waves. ing. Since this cover plate 10 does not cancel the interference effect of the reflected wave described later, a radio wave absorber 20 that absorbs at least a part of the radar wave is provided on the entire surface of the fifth cover plate 10 (described later). . A radio wave absorber 20 that absorbs at least a part of the radar wave is provided at a ridge line portion (joint portion) between the cover plates 10. The radio wave absorber 20 is made of a conductive material or radio wave absorber that can energetically absorb at least a part of a radar wave, such as ferrite, and is attached or applied to the cover plate 10, for example. The radio wave absorber 20 is not limited to sticking or coating, and for example, the surface layer material (described later) of the cover plate 10 itself may be formed by the radio wave absorber 20. Thereby, the irregular reflection of the electromagnetic wave in the junction part (bending part) of the cover board 10 can be prevented, and the increase in a radar wave reflection area can be suppressed.
In the first embodiment, a case where a plurality of cover plates 10 are joined to form a corrugated cover member 1 will be described. However, the present invention is not limited to this, and for example, a flat plate is formed by bending or the like. It may be formed in a corrugated shape. Further, the cover member 1 may be formed by joining a plurality of bent flat plates.

FIG. 2 is a sectional structural view of the cover plate according to the first embodiment. As shown in FIG. 2, the cover plate 10 includes a plate body 12 and a surface layer material 11 bonded to the surface of the plate body 12, and has a structure in which the plate body 12 is sandwiched between the surface layer materials 11. The surface layer material 11 is made of a conductive material (for example, CFRP: carbon fiber reinforced plastics) or a radio wave absorber (for example, ferrite) that can absorb at least part of the incident radar wave in energy, or incident. It consists of a radio wave reflector that reflects all or part of the radar wave. The surface material 11 can be reduced in weight by using, for example, a resin material. It is also possible to give strength by weaving strength fibers into the resin. The plate body 12 can be formed by using, for example, a metal or resin to form a honeycomb structure, or using wood or resin. As a result, the weight can be reduced as compared with the case where the cover member is made of only metal. With such a structure, the weight of the cover member can be reduced compared to the case where the cover member is made of only metal, and the rigidity against external forces such as waves and winds can be improved.
Next, the arrangement of the cover plates 10 of the cover member 1 will be described with reference to FIG.

  FIG. 3 is a view for explaining the arrangement of the cover plates according to the first embodiment. The cover member 1 is arranged such that at least two or more cover plates 10 among the plurality of cover plates 10 constituting the reflective surface portion have the same normal direction, and are arranged in the same normal direction. Among the cover plates 10, the distance difference in the normal direction between the adjacent cover plates 10 is arranged such that the reflected waves of the adjacent cover plates 10 are phase-interfered and canceled and attenuated. . For example, as shown in FIG. 3, in the cover member 1 according to the first embodiment, among the cover plates 10-1 to 8, the cover plates 10-1, 3, 5, and 7 have the same normal direction. The difference in distance between the cover plates 10-1 and 10-3, the cover plates 10-3 and 10-5, and the cover plates 10-5 and 10-7 in the normal direction is a radar wave. Are arranged at a distance (1 / 4λ) that is a quarter of the wavelength (λ) of. Similarly, the cover plates 10-2, 4, 6, and 8 are also arranged so that their normal directions are the same, and the distance difference in the normal direction is arranged at a distance of 1 / 4λ. Note that the distance difference in the normal direction is not limited to a distance of ¼λ, but may be any distance as long as each reflected wave of the adjacent cover plate 10 is phase-interfered and canceled and attenuated. You may arrange | position so that it may become the distance corresponded to the odd multiple of a wavelength.

  The angles between the cover plates 10 to be joined are joined at the same angle, for example, an angle of 160 °. The angle is not limited to this, and can be arbitrarily set according to the width of the cover member 1. In other words, as described above, the cover plate 10 has the same normal direction, and the distance between the normal directions is an odd multiple of 1 / 4λ. The width of 10 can be arbitrarily set. With such an arrangement of the cover plate 10, radar waves reflected in the normal direction from each cover plate 10 interfere with each other, cancel and attenuate (hereinafter simply referred to as “phase interference”). Can be reduced. Details of this phase interference will be described later.

  Next, the case where the radar wave reflection area reducing device according to the first embodiment is applied to a receiving device (offshore receiving device) 3 installed in a ship will be described.

  FIG. 4 is an external view of the receiving device when the cover member is not attached according to the first embodiment. Moreover, Fig.4 (a) is a top view of the receiving device 3, and is A arrow line view in FIG.4 (c). FIG.4 (b) is a side view of the receiving device 3, and is a B arrow view in FIG.4 (c). FIG. 4C is a front view of the receiving device 3.

  As shown in FIG. 4, the receiving device 3 is attached to the surface of the hull structure of the hull 2, and wire or the like is suspended between the ship and another ship, and supplies and the like are supplied between the ships. It is. The receiving device 3 is disposed with an inclination of, for example, 2 ° to 10 ° in the width direction of the hull with respect to the horizontal plane of the hull 2. The receiving device 3 may be installed with the same inclination in the length direction of the hull, or may be installed vertically with respect to the hull without providing the inclination. Such a receiving device 3 is a device (hereinafter referred to as “radar”) that performs detection by emitting specular reflection or irregular reflection when a radar wave reaches a projection or a plane portion of the device, and radiating the radar wave. It is easy to detect, and the radar wave reflection area is large. The cover member 1 is attached to reduce the irregular reflection of the radar wave at the receiving device 3.

  FIG. 5 is an external view of the receiving device when the cover member is mounted according to the first embodiment. FIG. 5A is a top view of the receiving device 3 when the cover member 1 is mounted, and is a view taken in the direction of arrow A in FIG. FIG. 5B is a side view of the receiving device 3 when the cover member 1 is mounted, and is a view as seen from the direction of arrow B in FIG. FIG. 5C is a front view of the receiving device 3 when the cover member 1 is mounted.

As shown in FIG. 5, when the receiving device 3 is not used, the receiving device 3 is covered with the cover member 1 constituting the radar wave reflection area reducing device on the front surface and both side surfaces. Further, the cover member 1 is disposed inclined with respect to the vertical direction. That is, it is arranged with an inclination of, for example, 2 ° to 10 ° in the width direction of the hull 2 with respect to the horizontal plane of the hull 2. The receiving device 3 may be installed with the same inclination in the length direction of the hull, or may be installed vertically with respect to the hull without providing the inclination. In this way, the receiving device 3 is covered with the cover member 1, and the cover member 1 is further inclined with respect to the horizontal direction, so that the reflected wave in the front direction of the incident radar wave (reflected back to the radar). Wave) and the radar wave reflection area can be reduced.
Next, the relationship between the incident radar wave and the reflected wave will be described with reference to FIGS.

FIG. 6 is a diagram for explaining the reflection direction of the reflected wave according to the first embodiment. In FIG. 6, the principal part of the top view of the cover member 1 is typically shown. As described above, each cover plate 10 is joined in a corrugated shape at a predetermined angle (160 °). As shown in FIG. 6A, the radar wave incident at a predetermined angle θ with respect to the normal direction of the cover plate 10 is totally or partially reflected by the reflection angle θ by specular reflection. That is, it does not return to the radar that emitted the radar wave.
On the other hand, when the incident angle of the radar wave changes due to a change in the navigation direction of the ship or the movement of the radar, and the incident angle becomes the same as the normal direction of the cover plate 10, as shown in FIG. The incident radar wave is totally or partially reflected in the normal direction by specular reflection. That is, the reflected wave returns to the radar that radiates the radar wave.

FIG. 7 is a diagram for explaining the reflection direction of the reflected wave according to the first embodiment. In FIG. 7, the principal part of the side view of the cover member 1 is typically shown. As described above, the cover member 1 is disposed with an inclination of, for example, 2 ° to 10 ° in the width direction of the hull 2 with respect to the horizontal plane of the hull 2. At this time, as shown in FIG. 7A, the radar wave incident from the horizontal direction is incident on the cover plate 10 at an incident angle θ, and is totally or partially reflected by a reflection angle θ by specular reflection. That is, it does not return to the radar that emitted the radar wave.
On the other hand, when the hull 2 is tilted or the incident angle of the radar wave changes due to the movement of the radar or the like, and the incident angle becomes the same as the normal direction of the cover plate 10, as shown in FIG. The incident radar wave is totally or partially reflected in the normal direction by specular reflection. That is, the reflected wave returns to the radar that radiates the radar wave.

In this way, the receiving device 3 is covered with the corrugated plate-like cover member 1, and further, the cover member 1 is arranged with an inclination with respect to the horizontal plane of the hull 2, so that the incident light is incident from other than the normal direction of the cover plate 10. The reflected wave in the front direction of the radar wave thus reflected (the reflected wave returning to the radar) can be reduced, and the radar wave reflection area of the receiving device 3 can be reduced.
Next, the phase interference of the reflected wave incident in the normal direction and returning to the radar will be described in detail.

  FIG. 8 is a diagram for explaining phase interference of the reflected wave according to the first embodiment. In FIG. 8, the principal part of the top view of the cover member 1 is typically shown. As described above, the cover plates 10-1 and 10-3 are arranged so that the normal direction is the same, and the distance difference in the normal direction is 1 / 4λ. At this time, as shown in FIG. 8, radar waves incident from the normal direction of the cover plates 10-1 and 10-3 are reflected as reflected waves Ra and Rb in the normal direction of the cover plate 10, respectively. At this time, the reflected wave Rb reflected by the cover plate 10-3 is 1 / 4λ before the reflected wave Ra reflected by the cover plate 10-1 reaches the reflection surface of the cover plate 10-3, and the cover plate. A path difference of ¼λ is generated before the distance of the reflection surface of the cover plate 10-1 is reached after being reflected by the reflection surface of 10-3, and a phase difference of ½λ is generated between the reflected wave Rb and the reflected wave Ra. . Thereby, the reflected wave Ra and the reflected wave Rb cancel each other and attenuate (phase interference). Similarly, this phase interference is caused by the reflected waves in the normal direction of the cover plates 10-3 and 10-5, the cover plates 10-5 and 10-7, and the cover plates 10-2, 4, 6, and 8 as well. Are phase interfered.

  Thus, the cover member 1 includes the reflected wave in the normal direction of one cover plate 10 among the plurality of cover plates 10 and the reflection in the normal direction of one or more cover plates 10 other than the cover plate 10. When the waves interfere with each other, the reflected wave incident in the normal direction of the cover plate 10 and returning to the radar is attenuated, and the radar wave reflection area of the receiving device 3 can be reduced.

  As shown in FIG. 9, since the distance difference in the normal direction between the first cover plate 10-1 and the fifth cover plate 10-5 is 1 / 2λ of the radar wave, the path difference is It becomes the same as the wavelength (λ) of the radar wave, and the effect of phase interference cannot be obtained between the cover plate 10-1 and the cover plate 10-5. Similarly, since the distance difference in the normal direction between the first cover plate 10-1 and the ninth cover plate 10-9 is λ, the path difference is twice the wavelength (λ) of the radar wave. The effect of phase interference cannot be obtained between the cover plate 10-1 and the cover plate 10-9. As described above, when the cover plate 10 constituting the cover member 1 is composed of four or more, it is desirable to provide the radio wave absorber 20 on the entire reflection surface of the cover plate 10 at intervals of five.

  Next, the effect of reducing the radar wave reflection area by the radar wave reflection area reduction device of the first embodiment as described above will be described with reference to FIG.

FIG. 10 is a diagram showing a calculated value of the radar wave reflection area according to the first embodiment. In FIG. 10, the radar wave with respect to the incident angle of the radar wave when the corrugated cover member 1 according to the first embodiment is used as the cover member (solid line) and when the flat plate is used (dotted line). The calculated value (smooth line) of the reflection area (RCS) is shown. Note that a radio wave reflector is used for each surface layer material 11 of the cover plate 10, and the cover members are arranged with a predetermined inclination with respect to the horizontal plane. In addition, a radio wave absorber 20 is attached to a joint portion of each cover plate 10 in the corrugated cover member 1.
As shown in FIG. 10, the corrugated cover member 1 according to the first embodiment reduces the radar wave reflection area in all directions as compared to the case where the cover member is formed of a flat plate. Is expected in the calculation.

  As described above, in the first embodiment, the cover member 1 formed in the corrugated plate shape covers all or a part of the receiving device 3, thereby suppressing regular reflection or irregular reflection of the radar wave at the device. Thus, the radar wave reflection area can be reduced.

  Further, by arranging the cover member 1 with an inclination with respect to the horizontal plane of the hull 2, a reflected wave in the front direction of the radar wave incident from a direction other than the normal direction of the cover plate 10 (a reflected wave returning to the radar) is generated. The radar wave reflection area of the receiving device 3 can be reduced.

  In addition, the cover member 1 formed in a corrugated plate shape allows the reflected wave in the normal direction of one cover plate 10 among the plurality of cover plates 10 and the one or more cover plates 10 other than the cover plate 10 to be reflected. Phase interference with the reflected wave in the normal direction makes it possible to attenuate the reflected wave that enters from the normal direction of the cover plate 10 and returns to the radar, thereby reducing the radar wave reflection area of the receiving device 3. .

  Further, by making the cover plate 10 a structure in which the plate body 12 is sandwiched between the surface layer materials 11, the cover member 1 can be made lighter than the cover member 1 made of only metal.

  In the first embodiment, the case where the cover member 1 is disposed with an inclination with respect to the horizontal plane of the hull 2 has been described. However, the present invention is not limited to this, and the cover member 1 is perpendicular to the hull 2 without providing an inclination. It may be installed in. Also in this case, the reflected wave in the normal direction of the cover member 1 is attenuated by the above-described phase interference, and the radar wave reflection area can be reduced.

Embodiment 2. FIG.
In the first embodiment, the corrugated cover member 1 in which a plurality of cover plates 10 are joined is used as the cover member 1 that covers the receiving device 3. In the second embodiment, a flat plate having a smooth surface is used. The cover member 1 comprised by these is used.

  FIG. 11 is an external view of the receiving device when the cover member is mounted according to the second embodiment. Moreover, Fig.11 (a) is a top view of the receiving device 3 at the time of cover member 1 mounting | wearing, and is an A arrow view in FIG.11 (c). FIG.11 (b) is a side view of the receiving device 3 at the time of cover member 1 mounting | wearing, and is a B arrow view in FIG.11 (c). FIG. 11C is a front view of the receiving device 3 when the cover member 1 is mounted.

  As shown in FIG. 11, the front surface and both side surfaces of the receiving device 3 according to the second embodiment are covered with a cover member 1 formed of a smooth flat plate. Further, the cover member 1 is disposed inclined with respect to the vertical direction. That is, it is arranged with an inclination of, for example, 2 ° to 10 ° in the width direction of the hull 2 with respect to the horizontal plane of the hull 2. In addition, you may install the receiving device 3 by the same inclination in the length direction of a hull. The cross-sectional structure and material of the cover member 1 in the second embodiment are the same as those of the cover plate 10 in the first embodiment described above. Moreover, you may stick the electromagnetic wave absorber 20 to the junction part of the cover member 1 which covers the front of the receiving device 3, and the cover member 1 which covers a side surface similarly to Embodiment 1 mentioned above.

  Thus, by covering the receiving device 3 with the cover member 1 formed of a flat plate, the regular reflection or irregular reflection of the radar wave at the device can be suppressed and the radar wave reflection area can be reduced. Further, by arranging the cover member 1 with an inclination with respect to the horizontal direction, a reflected wave in the front direction of a radar wave incident from a direction other than the normal direction of the cover member 1 (a reflected wave returning to the radar) is generated. The radar wave reflection area of the receiving device 3 can be reduced.

  Next, the effect of reducing the radar wave reflection area by the radar wave reflection area reduction device of the first embodiment as described above will be described with reference to FIG.

FIG. 12 is a diagram showing a calculated value of the radar wave reflection area according to the second embodiment. In FIG. 12, the radar wave reflection area (RCS) with respect to the incident angle of the radar wave when the cover member 1 according to the second embodiment is used (solid line) and when the cover member 1 is not provided (dotted line). The calculated value (smooth line) is shown. The cover member 1 uses a radio wave reflector.
As shown in FIG. 12, the cover member 1 formed of a flat plate according to the second embodiment is calculated to reduce the radar wave reflection area in all directions compared to the case where the cover member 1 is not provided. Expected above.

  As described above, in the second embodiment, the cover member 1 covers the whole or a part of the receiving device 3, thereby suppressing regular reflection or irregular reflection of the radar wave at the device and increasing the radar wave reflection area. Can be reduced.

  Further, by arranging the cover member 1 with an inclination with respect to the horizontal plane of the hull 2, a reflected wave in the front direction of the radar wave incident from a direction other than the normal direction of the cover plate 10 (a reflected wave returning to the radar) is generated. The radar wave reflection area of the receiving device 3 can be reduced.

  Moreover, compared with the corrugated cover member 1 in the first embodiment, the cover member 1 can be manufactured with a simple structure, and the manufacturing cost can be reduced.

2 is a schematic configuration diagram of a cover member according to Embodiment 1. FIG. 2 is a cross-sectional structure diagram of a cover plate according to Embodiment 1. FIG. 5 is a diagram for explaining the arrangement of cover plates according to Embodiment 1. FIG. It is an external view of the receiving device when the cover member is not attached according to the first embodiment. FIG. 3 is an external view of a receiving device when the cover member is mounted according to the first embodiment. 6 is a diagram for explaining a reflection direction of a reflected wave according to Embodiment 1. FIG. 6 is a diagram for explaining a reflection direction of a reflected wave according to Embodiment 1. FIG. 6 is a diagram for explaining phase interference of a reflected wave according to Embodiment 1. FIG. 6 is a diagram for explaining phase interference of a reflected wave according to Embodiment 1. FIG. It is a figure which shows the calculated value of the radar wave reflective area which concerns on Embodiment 1. FIG. FIG. 6 is an external view of a receiving device when a cover member is mounted according to Embodiment 2. It is a figure which shows the calculated value of the radar wave reflective area which concerns on Embodiment 2. FIG.

Explanation of symbols

  1 cover member, 2 hull, 3 receiving device, 10 cover plate, 11 surface layer material, 12 plate body, 20 radio wave absorber.

Claims (11)

A plurality of flat reflection surface portions are formed into a corrugated plate shape, and includes a cover member that reflects all or part of an incident radar wave,
A radar wave reflection area reducing apparatus, wherein the cover member covers all or part of a radar target and reduces the radar wave reflection area of the radar target. The cover member is
Of the plurality of reflecting surface portions, the reflected wave in the normal direction of one reflecting surface portion and the reflected wave in the normal direction of one or more reflecting surface portions other than the reflecting surface portion interfere with each other and are offset and attenuated. The radar wave reflection area reducing device according to claim 1, wherein the radar wave reflection area of the radar target is reduced. The cover member is
Among the plurality of reflection surface portions, at least two or more reflection surface portions are formed so that their normal directions are the same, and among the reflection surface portions formed in the same normal direction, adjacent reflection surface portions. The distance difference in the normal direction of
3. The radar wave reflection area reduction device according to claim 1, wherein each of the reflected waves of the adjacent reflection surface portions is formed to have a distance that causes phase interference, cancels, and attenuates. The cover member is
Among the plurality of reflection surface portions, at least two or more reflection surface portions are formed so that their normal directions are the same, and among the reflection surface portions formed in the same normal direction, adjacent reflection surface portions. The distance difference in the normal direction of
3. The radar wave reflection area reducing device according to claim 1, wherein the radar wave reflection area reducing device is formed so as to have a distance corresponding to an odd multiple of a quarter wavelength of the radar wave. The cover member is
The radar wave reflection area reducing device according to any one of claims 1 to 4, wherein the radar wave reflection area of the ship is reduced by covering all or part of the structure of the ship. The cover member is
The radar wave reflection area reducing device according to claim 1, wherein the radar wave reflection area reducing device is disposed so as to be inclined with respect to a vertical direction. The cover member is
The radar wave reflection area reduction device according to claim 1, wherein a radio wave absorber that absorbs at least a part of the radar wave is provided at a ridge line portion between the reflection surface portions. The cover member is
The radar wave reflection area reducing device according to any one of claims 1 to 6, wherein a ridge line portion between the reflection surface portions is formed by a radio wave absorber that absorbs at least a part of the radar wave. The cover member is
The radar wave reflection area reducing device according to claim 1, comprising a radio wave absorber that absorbs at least a part of the radar wave or a radio wave reflector that reflects the radar wave. The cover member is
10. The radar wave reflection area reducing device according to claim 9, comprising a plate having a wood or honeycomb structure and the radio wave absorber or the radio wave reflector bonded to the surface of the plate. The cover member is
11. The radar wave reflection area reducing device according to claim 1, wherein each reflection surface portion is formed of a flat plate, and the plurality of flat plates are joined to form a corrugated plate shape.

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