Radar reflector

Abstract

To provide a radar reflector with a simple structure that is easy to manufacture, or a radar reflector that is less affected by wind pressure and easy to install outdoors. [Solution] The reflector body 1 is a corner reflector type with an equilateral triangular opening. The reflector body 1 has a notch 2 formed by cutting out the vertex of a virtual triangular pyramid with the opening surface as the base, and a slit 3 is formed on at least one side surface that communicates with the notch 2 and extends from the notch 2 to the opening. By providing an air passage, the external force received due to wind pressure is reduced.

Description

Technical Field

[0001] The present invention relates to a structure and manufacturing method of a radar reflector used when applying a radar or sensor using radio waves.

Background Art

[0002] In radars and sensors using radio waves, an object with a radar cross section (RCS) that does not change with angles or the like is required to stably measure a detection area. Although a spherical metal exhibits a constant RCS for radio waves from any angle, its reflection cross section is very small and it is difficult to use. Therefore, a corner reflector 41 formed by bonding three metal plates (41a to 41c) of right-angled isosceles triangles as shown in FIG. 15 into a triangular pyramid shape is often used as a standard target. Since the right-angled vertices are aligned and arranged at right angles to each other, one surface becomes an opening surface of an equilateral triangle.

[0003] For a corner reflector, if the length of one side of the adjacent sides of the right-angled isosceles triangle forming one surface is a, the length L of one side of the equilateral triangle forming the opening surface is a√2, and the height h from the opening surface to the apex of the triangular pyramid is a / √3.

[0004] The reflecting surface of the corner reflector as described above is the inner surface of a hollow triangular pyramid, which has a bag-like structure. Therefore, when installed outdoors, if wind flows in from the opening surface, there is no escape space for air, and it receives a high wind pressure. Therefore, there is a possibility of damage or vibration caused by strong wind. Therefore, when installing outdoors, it is necessary to make not only the reflector body but also the fixing members from high-strength materials so that destruction due to wind pressure or the like does not occur.

[0005] For example, measures such as using thick plates as the material for the reflector body, or making the support columns and mounting brackets for fixing the corner reflectors robust enough to withstand their weight and wind pressure, would be necessary. Alternatively, measures such as covering the corner reflectors with radomes to reduce air resistance and mitigate the effects of wind pressure would be required. Such measures have the problem of increasing the cost of manufacturing and installation.

[0006] Furthermore, when manufacturing corner reflectors, it is necessary to join three right-angled isosceles triangular plates together using fasteners such as screws or welding to maintain strength. Fastening with screws requires drilling holes in the plates and screwing in the screws, and welding requires a jig to fix the three plates in place, thus increasing labor costs.

[0007] Regarding the manufacturing method of the corner reflector, as shown in Patent Document 1, there is a method that reduces the number of steps by bending a single metal plate. Figure 16 is a diagram shown in Patent Document 1, with Figure 16(a) showing the unfolded diagram and Figure 16(b) showing the assembled diagram. In this manufacturing method, first, as shown in Figure 16(a), a square metal plate is punched out into the unfolded shape of a triangular pyramid. Then, it is bent along the diagonals A and B of the square, and one side C is joined by welding as shown in Figure 16(b). [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 08-181535 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] The technology described in Patent Document 1 reduces the number of welds required from three to one by incorporating bending. However, even though the number of welds can be reduced, the welding process itself is still necessary. Moreover, since the reflector body in Patent Document 1 is formed from aluminum plate, welding is difficult due to its high thermal conductivity and surface oxide film, requiring advanced welding techniques. Brazing can be used instead of welding, but this requires surface preparation.

[0010] The present invention aims to solve the above problems and provide a radar reflector with a simple structure that is easy to manufacture, or a radar reflector that is less affected by wind pressure and easy to install outdoors. [Means for solving the problem]

[0011] To solve the above problems, a radar reflector according to one embodiment is a radar reflector equipped with a corner reflector type reflector body having an equilateral triangular opening, wherein the reflector body has a notch formed by cutting out the vertex of a virtual triangular pyramid with the opening surface of the opening as the base surface, one of the side walls is divided into a first dividing wall and a second dividing wall, a slit is formed by the sides of the first dividing wall and the second dividing wall facing each other, the slit communicates with the notch and is formed in the range from the notch to the opening. The slit is formed in a straight line, and the width ws of the slit may satisfy the relationship ws / a ≤ 0.05 when a is the length of the side of the virtual triangular pyramid.

[0012] Furthermore, the reflector body may have the shape of a substantially truncated triangular pyramid, where the height of the virtual triangular pyramid is reduced by the notch, and the relationship i / h ≤ 0.3 may be satisfied when the reduced height is i and the height of the virtual triangular pyramid is h. In this case, the slit is straight, and the width ws of the slit may satisfy the relationship ws / a ≤ 0.075, where a is the length of the side of the virtual triangular pyramid.

[0013] Furthermore, in this case, a mounting portion may be provided integrally with the reflector body on a part of the reflector body, and the mounting portion may consist of a wall portion that is continuous with either the first dividing wall or the second dividing wall, and the wall portion may stand substantially perpendicular to the first dividing wall or the second dividing wall, and may have a round hole and an elongated hole whose longitudinal center is an arc centered on the round hole. [Effects of the Invention]

[0014] According to one aspect of the present invention, a radar reflector can be provided that reduces the external force it receives due to wind pressure by providing an air passage. Furthermore, according to another aspect of the present invention, it is possible to provide a weather-resistant radar reflector that reduces the number of components in the angle-adjustable mounting structure, does not require welding or screw connections, and can be easily manufactured, especially from stainless steel plates, thereby reducing the man-hours required for manufacturing and installation. [Brief explanation of the drawing]

[0015] [Figure 1] This is a perspective view showing the reflector body according to the first embodiment. [Figure 2] This is a graph showing the simulation results. [Figure 3] This graph shows the change in the attenuation of the RCS. [Figure 4] This figure shows the manufacturing process of a radar reflector according to the first embodiment. [Figure 5] This is a perspective view showing the reflector body according to the second embodiment. [Figure 6] This is a perspective view showing a modified example of the second embodiment. [Figure 7] This is a graph showing the simulation results. [Figure 8] This graph shows the change in the attenuation of the RCS. [Figure 9] This is a graph showing the simulation results. [Figure 10] This graph shows the change in the attenuation of the RCS. [Figure 11] It is a diagram showing the manufacturing process of a radar reflector according to the second embodiment. [Figure 12] It is a perspective view showing the reflector body according to the third embodiment. [Figure 13] It is a view of the reflector body according to the third embodiment seen from the side. [Figure 14] It is a diagram showing the manufacturing process of a radar reflector according to the third embodiment. [Figure 15] It is a diagram showing a conventional corner reflector. [Figure 16] It is a diagram showing the manufacturing process of a conventional corner reflector.

Modes for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 14. In each of the following embodiments, parts that are identical or equivalent to each other are denoted by the same reference numerals and will be described.

[0017] (First Embodiment) First, the structure and manufacturing method of the first embodiment of the present invention will be described below. [Regarding the Structure] FIG. 1 is a perspective view showing a radar reflector according to the first embodiment of the present invention. As shown in this figure, the reflector body 1 has a shape similar to that of a conventional corner reflector, but one of the three side walls (the inner surface is a reflecting surface) is divided into two dividing walls (A and B), and the side surfaces of these dividing walls face each other to form a slit 3, which is different. That is, conventionally, the space surrounded by the reflecting surface was a container-shaped closed space, but by forming a slit 3 in part, the closed space is opened.

[0018] In other words, the slit 3 provides a passage that allows air flowing into the opening of the reflector body to escape from the inner surface (reflective surface) to the opposite side. The slit for opening the closed space can be provided not only on the side but also at the corner or other arbitrary location. In this embodiment, a slit 3 is formed in a substantially straight line with a substantially constant width ws in the range from the notch 2 to the equilateral triangular opening on one side wall, communicating with the notch 2. This shape reduces air resistance and provides advantageous effects in the manufacturing method described later.

[0019] It should be noted that the reflector body is not strictly the same hollow equilateral triangular pyramid as conventional corner reflectors because it has a notch. However, it has almost the same shape as a virtual hollow equilateral triangular pyramid that can be formed by extending the hypotenuse that is interrupted by the notch.

[0020] For convenience, this specification may also refer to the overall shape of the reflector body as a hollow equilateral triangular pyramid, a hollow triangular pyramid, or simply a triangular pyramid, and hypothetical letters may be added to these terms for comparison with the actual size. Furthermore, the opening is not strictly an equilateral triangle because its outer shape is discontinuous due to the slit. However, the discontinuous portion is small, and if this is ignored, it becomes an equilateral triangle. Therefore, for convenience, this specification describes the shape of the opening or opening surface of the reflector body as an equilateral triangle.

[0021] By the way, the effective reflective cross-sectional area (RCS) of a corner reflector is expressed by Equation 1. σ = 4πa 4 / 3λ 2 ...Formula 1 Here, σ represents the RCS, λ represents the wavelength of the radio wave, and a represents the length of the side. Although the dimensions of the slit are not included in Equation 1, the reduction in area due to the presence of the slit affects the numerator on the right-hand side of Equation 1. That is, the presence of slit 3 reduces the RCS. However, this reduction in RCS can be compensated for by increasing the length a of the side of the virtual hollow equilateral triangular pyramid. In other words, since the RCS can be increased by increasing the reflection area, the amount of radar signal reflected by slit 3 can be compensated for by increasing the length a.

[0022] In this specification, the term "side edge" refers strictly to the side edge of the virtual equilateral triangular pyramid formed by the reflective surface. However, assuming that the thickness of the side walls is thin and their influence on the RCS is negligible, this specification does not distinguish it from the side edge of the virtual equilateral triangular pyramid formed by the outer shape of the three side walls.

[0023] Figure 2 is a graph showing the results of a simulation of how the RCS level changes when the width ws of slit 3 is changed. The reflector body used is made of stainless steel, the frequency is 60 GHz, and the length a is 110mm The graph's vertical axis represents the RCS level, and the horizontal axis represents the radar signal incidence angle Phi. When Phi=0, the radar signal is incident from the front of the reflector body 1. The thin line on the graph represents ws / a=0, the thick line represents ws / a=0.075, the dotted line represents ws / a=0.15, the dashed line represents ws / a=0.225, and the dashed line represents ws / a=0.3.

[0024] Figure 3 is a graph showing the change in RCS attenuation with respect to the change in the ratio of width ws to length a. From this graph, it can be seen that if ws / a ≤ 0.05, the decrease in RCS will be less than 1 dB. From the graph in Figure 2, it can also be seen that the dependence of RCS on the angle (Phi) does not change much. In other words, if the value of width ws is set to a value that satisfies ws / a ≤ 0.05, there will be no problems in practical use. If a decrease in RCS of 1 dB or more is acceptable, then ws / a > 0.05 is also acceptable.

[0025] As described above, the radar reflector according to this embodiment has a slit 3 formed in the reflector body, so even when it is subjected to wind from the front, the air can be released to the rear, thereby reducing air resistance. Therefore, damage and vibration due to wind pressure can be prevented, which is particularly advantageous when used outdoors. For example, if the radar reflector of this embodiment is used for radar ranging, it becomes possible to perform surveying and other tasks without being affected by weather conditions.

[0026] <About the manufacturing method> Figure 4 shows the manufacturing process of a radar reflector according to the first embodiment. First, a punched material is formed from an aluminum plate using a punch press machine in the shape shown in Figure 4(a). This punching process is performed in two stages: a first pressing step in which a circular hole is punched out centered on the intersection of diagonals A and B of a square base plate, and a second pressing step in which a corner of the square is cut out from the circular hole to create the divided wall parts A and B. Here, the circular hole created in the first pressing step is for forming the cutout part 2, improving the workability and accuracy of the bending process that is performed later.

[0027] If a multi-mold system is not used, a punch and die with the shapes of the round hole and notch described above can be prepared, and the punched material can be formed in a single process. Incidentally, the notch 2 appears as a hollow equilateral triangular pyramid with the vertex notched, but for the sake of comparison with Figure 4(b), the location corresponding to the notch 2 is labeled with reference numeral 2 in Figure 4(a).

[0028] Next, the material is bent along diagonals A and B using a press machine to form a triangular pyramid shape as shown in Figure 4(b). During the bending process, care should be taken to bring dividing walls A and B together so that slits 3 are formed at regular intervals from the center of the base of the opening to the notch 2, and to adjust so that the notch 2 is located at the top. The reflector body shown in the figure has an equilateral triangular opening as its front, and the slits 3 and the notch 2 are in communication. The subsequent connection of the reflector body to other parts is done by known methods. However, if the side with the slits 3 is fixed to a support column (not shown) via a mounting bracket (not shown) with a rivet 4 or the like, or directly to a support column (not shown), the slits 3 will not open or narrow further. In other words, the reduction in rigidity due to the provision of slits 3 is compensated for, and the stability of the shape can be ensured even when subjected to wind pressure.

[0029] As described above, the manufacturing method of this embodiment eliminates the need for welding the reflector body, thereby reducing the amount of work required. However, since the manufacturing method of this embodiment utilizes bending, dimensional errors due to springback may occur. However, these dimensional errors can be reduced by known methods such as performing a two-stage bending process or pre-applying V-notches along diagonals A and B.

[0030] Next, the structure and manufacturing method of a second embodiment of the present invention will be described. <About the structure> Figure 5 is a perspective view showing the reflector body of the second embodiment. The difference between this embodiment and the first embodiment is that the notch forms an equilateral triangular opening similar in shape to the opening. As shown in the figure, not only the slit 13 but also the opening formed by the notch 12 provides an additional airflow channel, thus reducing the external force due to wind pressure even in strong winds and preventing damage and vibration of the radar reflector. Due to the presence of the opening formed by the notch 12, the reflector body 11 has a roughly truncated triangular shape.

[0031] However, the reduction in the reflective area due to the notch 12 becomes a problem. According to Equation 1 above, it is certain that if the side a decreases, σ(RCS) also decreases. Therefore, the inventor performed a simulation using the reflector body 21 shown in Figure 6. The reflector body 21 shown in this figure differs from the reflector body 11 shown in Figure 5 in that the opposing sides of the dividing walls A and B are in contact and the slit 23 is closed.

[0032] Figure 7 is a graph showing the results of a simulation of how the RCS level changes when the ratio (i / h) of the height h of the virtual regular triangular pyramid to the height i that decreases at the notch 22 is changed. The material of the reflector body used is stainless steel, the frequency is 60 GHz, and the side length a of the virtual regular triangular pyramid is 110mm The vertical axis of the graph represents the RCS level, and the horizontal axis represents the radar signal incidence angle Phi. When Phi=0, the radar signal is incident from the front of the reflector body 21. On the graph, the thin line shows the case i / h=0 (no notch), the thick dotted line shows the case i / h=0.3, and the thin dotted line shows the case i / h=0.5.

[0033] Figure 8 is a graph showing the change in RCS attenuation with respect to i / h. From this graph, it can be seen that if the height i reduced by the notch 22 is less than or equal to approximately 1 / 3 of the height h (i / h ≤ 0.3), the decrease in RCS is less than or equal to 1 / 2 (-3dB) of the value without the notch 22, and an equivalent RCS can be obtained by increasing the dimension of length a by approximately 1.2 times. Furthermore, it can be seen from the graph in Figure 7 that the dependence of RCS on the angle (Phi) does not change much. Conversely, if the notch exceeds 1 / 3, the decrease in RCS becomes large, and the required size also increases in order to obtain an equivalent RCS. Moreover, when the height i exceeds 1 / 2 of the height h (i / h = 0.5), as shown in the graph in Figure 7, the RCS near the front (Phi = 0 degrees) becomes small, and the angle at which the maximum RCS can be obtained is found at two locations other than the front, making it unsuitable for use as a reflector. If a decrease in RCS of 3dB or more is acceptable, i / h > 0.3 is also acceptable.

[0034] In other words, in the second embodiment, the RCS is reduced by the presence of the notch 22 in the reflector body 21, but if the notch is made to the extent that it reduces the height by about 1 / 3 of the height of the virtual regular triangular pyramid, it will be suitable for practical use.

[0035] Based on the above, in the reflector body 21 shown in Figure 5, the ratio of the height h of the virtual regular triangular pyramid to the height i decreased by the notch 22 (i / h) was fixed at 0.3, and the RCS level was simulated when the width ws of the slit 23 was changed. Figure 9 is a graph showing the results. The material of the reflector body used was stainless steel, the frequency was 60 GHz, and the side length a of the virtual regular triangular pyramid was 110mm The graph's vertical axis represents the RCS level, and the horizontal axis represents the radar signal incidence angle Phi. When Phi=0, the radar signal is incident from the front of the reflector body 1. The thin line on the graph represents ws / a=0, the thick line represents ws / a=0.075, the dotted line represents ws / a=0.15, the dashed line represents ws / a=0.225, and the dashed line represents ws / a=0.3.

[0036] On the other hand, Figure 10 is a graph showing the change in the attenuation of the RCS with respect to the change in the ratio of width ws to length a. From this graph, it can be seen that if ws / a ≤ 0.075, the decrease in RCS will be less than 1 dB. From the graph in Figure 9, it can also be seen that the dependence of the RCS on the angle (Phi) does not change much. In other words, if the value of width ws is set to a value that satisfies ws / a ≤ 0.075, there will be no problems in practical use. If a decrease in RCS of 1 dB or more is acceptable, then ws / a > 0.075 is also acceptable.

[0037] <About the manufacturing method> Figure 11 shows the manufacturing process of a radar reflector according to the second embodiment. First, a punched material is formed from an aluminum sheet using a punch press machine in the shape shown in Figure 11(a). This punching process is performed in two stages: a first pressing step that creates a square corner hole with the intersection of diagonals A and B of the square base sheet as the centroid, and a second pressing step that cuts out a section from the corner hole to one corner of the base sheet to create dividing walls A and B. The corner hole created in the first pressing step is for forming the notch 12, which improves the workability and accuracy of the subsequent bending process and also functions as a ventilation opening.

[0038] If a multi-mold system is not used, a punch and die with the shapes of the square hole and notch described above can be prepared, and the punched material can be formed in a single process. Incidentally, the notch 12 appears as a hollow regular triangular pyramid with its vertex cut out, but for the convenience of comparison with Figure 11(b), the location corresponding to the notch 12 is labeled with reference numeral 12 in Figure 11(a).

[0039] Next, the material is bent along diagonals A and B using a press machine to form a truncated triangular pyramid shape as shown in Figure 11(b). During the bending process, care should be taken to bring dividing walls A and B together so that slits 13 are formed at regular intervals from the center of the base of the opening to the notch 12, and to adjust so that the opening surface formed by the notch 12 becomes the top base of the truncated triangular pyramid. The reflector body shown in the figure has an equilateral triangular opening as its front, and the slits 13 and the notch 12 are in communication. The subsequent connection of the reflector body to other parts is done by known methods, but if it is fixed in the same way as in the first embodiment, the slits 13 will not open or narrow further, and the stability of the shape can be ensured. As described above, the manufacturing method of this embodiment eliminates the need for welding the reflector body, thereby reducing the amount of work required.

[0040] Next, the structure and manufacturing method of a third embodiment of the present invention will be described. <About the structure> Figure 12 is a perspective view showing the reflector body of the third embodiment. The difference between this embodiment and the previous embodiments is that the mounting bracket for fixing the reflector body is integrated into the structure. As shown in the figure, the reflector body 31 has a notch 32 and a slit 33, which is the same as in the second embodiment. That is, the opening formed by the notch 32 and the slit 33 provide a passage for air to escape, so that even in strong winds, the external force due to wind pressure can be reduced and damage or vibration of the radar reflector can be prevented.

[0041] However, unlike the second embodiment, a mounting portion 34 is provided, which serves as a mounting bracket for fixing the reflector body. The mounting portion 34 has opposing surfaces that are continuous with the opposing sides of the dividing walls A and B that form the slit 33, and consists of two wall portions 35, 35 that stand substantially perpendicular to the dividing walls A and B in the direction opposite to the reflective surface, and round holes 36 and elongated holes 37 are formed in these wall portions 35. The round holes 36 are for press-fitting screws or bolts for fixing to a support column (not shown), and the two wall portions 35, 35 are fastened together to the support column with screws or bolts. On the other hand, the elongated holes 37 are provided for angle adjustment and are curved with a certain width. The longitudinal center line of the elongated holes 37 is an arc, and the center of the arc is the same as the center of the round hole 36. The round holes 36, 36 formed in each of these two wall portions 35, 35 have the same diameter and overlap in a side view. Furthermore, the elongated holes 37, 37 formed in each of the two wall portions 35, 35 have the same dimensions and overlap when viewed from the side.

[0042] Because the reflector body 31 of this embodiment has the shape described above, it is rotatable as shown in Figure 13. Figure 13 is a side view of the radar reflector of this embodiment, showing the reflector body 31 attached to the support column 40. The tip of the support column 40 is thin-walled, and the two wall portions 35, 35 of the reflector body 31 are assembled so as to sandwich the thin-walled tip. A screw 38 is inserted into the round hole 36 of the front wall portion 35 shown in the figure, and the screw 38 passes through a hole formed in the support column 40 (not shown) and a round hole 36 in the back wall portion 35 (not shown) and is screwed with a nut (not shown). On the other hand, a screw 39 is inserted into the elongated hole 37, and the screw 39 passes through a hole formed in the support column 40 (not shown) and an elongated hole 37 in the back wall portion 35 (not shown) and is screwed with a nut (not shown).

[0043] Therefore, by loosening the fastenings of screw 38 and nut, and screw 39 and nut, respectively, the reflector body 31 can rotate around screw 38 as an axis, making it possible to tilt it forward as shown by the dotted line or backward as shown by the dashed line. Then, by tightening the fastenings of screw 38 and nut, and screw 39 and nut, respectively, at an appropriate angle depending on the situation, the reflector body 31 can be fixed to the support column 40 at that angle.

[0044] <About the manufacturing method> Figure 14 shows the manufacturing process of a radar reflector according to the third embodiment. First, a punched material is formed from an aluminum plate using a punch press machine in the shape shown in Figure 14(a). This punching process is carried out in three stages: a first pressing step that creates round holes 36 and elongated holes 37 in a square base plate; a second pressing step that creates a square corner hole with the intersection of diagonals A and B as the centroid; and a third pressing step that cuts out from the corner hole to create divided walls A and B and wall sections 35, 35. Here, the corner hole punched out in the second pressing step is for forming a notch 32, which improves the workability and accuracy of the subsequent bending process and also functions as a ventilation opening.

[0045] If the dimensions of the round holes 36 and elongated holes 37 are small, they may be formed by milling or other methods without using a mold. Incidentally, the notch 32 appears when the vertex of the hollow regular triangular pyramid is cut out, but for the convenience of comparison with Figure 14(b), the location corresponding to the notch 32 is labeled with reference numeral 32 in Figure 14(a).

[0046] Next, the base of the wall portion 35 is bent using a press machine to create a mountain fold, and then bent along diagonals A and B to create a valley fold, thereby forming the truncated triangular pyramid shape shown in Figure 14(b). During the bending process, care should be taken to bring the dividing walls A and B together so that slits 33 are formed at regular intervals from the center of the base of the opening to the notch 32, and to adjust so that the opening surface formed by the notch 32 becomes the top base of the truncated triangular pyramid. The reflector body shown in the figure has an equilateral triangular opening as its front, and the slits 33 and the notch 32 are in communication. The wall portions 35, 35 are bent at right angles from the boundary line with the dividing walls A and B and face each other, forming the mounting portion 34. Then, as shown in Figure 13, the mounting portion 34 and the support column 40 are fastened together with screws, so that the slits 33 do not open or narrow further, and the stability of the shape can be ensured.

[0047] As described above, the manufacturing method of this embodiment eliminates the need for welding the reflector body, thereby reducing the amount of work required, and also allows for the easy formation of a mounting section integrated with the reflector body. Furthermore, by providing round holes and elongated holes in the mounting section, it becomes possible to adjust the angle after attaching the reflector body to the support column.

[0048] While embodiments of the present invention have been described above, various modifications are possible based on the spirit of the invention. For example, the slit in the above embodiment was linear in shape, but it is not limited to this and may be zigzag, curved, or other shapes. However, a linear shape requires less design work and makes it easier to attach to supports, etc.

[0049] Furthermore, in the second and third embodiments, the shape of the reflector body was made to be approximately a truncated triangular pyramid, but slight distortions may occur due to processing accuracy, etc., so it should be considered that it may not be a perfectly accurate truncated triangular pyramid. It goes without saying that even if the lengths of the three hypotenuses differ slightly, as long as there is no difference in the effect obtained by the present invention, it will still be within the category of approximately a truncated triangular pyramid.

[0050] Furthermore, although the mounting portion is composed of two wall sections in the third embodiment, it may also be composed of a single wall section following either dividing wall A or B. However, in this case, it is preferable to fix either dividing wall A or B, which has an open end.

[0051] Furthermore, the structure of the present invention is not limited to the material of the metal plate; aluminum plates or iron-based steel plates may be used, but since welding or other joining is unnecessary, it can be easily formed from stainless steel plates. In particular, when formed from stainless steel plates, there is no need to worry about rust or corrosion in outdoor environments, even without post-treatment such as plating or painting. [Explanation of Symbols]

[0052] 1, 11, 21, 31 Reflector body 2, 12, 22, 32 Notches 3, 13, 23, 33 slits 4 rivets 34 Mounting part 35 Wall 36 round holes 37 long hole 38, 39 screws 40 pillars 41 Corner reflector A, B diagonal Side C (welding point) a. Hypotenuse b. The length of the hypotenuse reduced at the notch. h is the height of the virtual triangular pyramid. i. The height of the virtual triangular pyramid is reduced at the notch. ws Slit width (i) First dividing wall B. Second dividing wall

Claims

1. A radar reflector comprising a corner reflector-type reflector body having an equilateral triangular opening, The reflector body has a notch formed by cutting out the vertex of a virtual triangular pyramid with the opening surface of the opening as its base. One of the side walls is divided into a first dividing wall and a second dividing wall. A slit is formed when the sides of the first dividing wall and the second dividing wall face each other. A radar reflector characterized in that the slit communicates with the notch and is formed in the range from the notch to the opening.

2. The slit is formed in a straight line, The width ws of the slit is given by the following equation, where a is the length of the side of the virtual triangular pyramid. ws / a ≤ 0.05 A radar reflector according to claim 1, characterized in that it satisfies the relationship.

3. The reflector body has the shape of a truncated triangular pyramid, with the height of the virtual triangular pyramid reduced by the notch. If the reduced height is i and the height of the virtual triangular pyramid is h, then the following equation i / h ≤ 0.3 A radar reflector according to claim 1, characterized in that it satisfies the relationship.

4. The slit is formed in a straight line, The width ws of the slit is given by the following equation, where a is the length of the side of the virtual triangular pyramid. ws / a≦0.075 A radar reflector according to claim 3, characterized in that it satisfies the relationship.

5. A part of the reflector body is provided with a mounting portion that is integrally formed with the reflector body. The mounting portion consists of a wall portion that is continuous with either the first dividing wall or the second dividing wall. The wall portion rises substantially vertically from the first dividing wall or the second dividing wall, The radar reflector according to claim 4, characterized in that a round hole and an elongated hole whose longitudinal center is an arc centered on the round hole are formed therein.

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