radio wave reflector

Abstract

Provided is a radio wave reflecting plate capable of reflecting radio waves in an angular range that is narrow in a front direction.　This radio wave reflecting plate includes a first flat surface that reflects radio waves, and a first inclined surface that is connected to at least part of an outer edge of the first flat surface, is inclined with respect to the first flat surface, and reflects radio waves. The area of the first flat surface and the area of the first inclined surface have a relation in which the difference between the maximum value of the intensity of reflected waves of the first flat surface and the maximum value of the intensity of reflected waves of the first inclined surface is a predetermined value or less, and the first inclined surface is inclined relative to the first flat surface such that the angular ranges at a predetermined intensity or more of the reflected waves of the first flat surface and the reflected waves of the first inclined surface overlap each other in the angular distribution of reflected waves with respect to a normal line passing the center of the first flat surface.

Description

Technical Field

[0001] The present disclosure relates to a radio wave reflector.

Background Art

[0002] Conventionally, there is a corner reflector characterized in that a square pyramid-shaped recess for reflecting incident electromagnetic waves or the like in the incident direction is provided on the surface of a sphere (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, the conventional corner reflector enables recursive reflection for a wide range of incident angles by the square pyramid-shaped recess. For this reason, for example, when a conventional corner reflector is used as a reflector of a radar system that reflects radio waves to detect an object and a plurality of corner reflectors are arranged in a narrow space, the reflected waves of adjacent corner reflectors may be recursively reflected, leading to a possibility of false detection of the object.

[0005] Therefore, an object is to provide a radio wave reflector capable of reflecting radio waves within a narrow angular range in the front direction.

Means for Solving the Problems

[0006] The radio wave reflector of the embodiment of the present disclosure includes a first plane that reflects radio waves and a first inclined surface connected to at least a portion of the outer edge of the first plane, inclined with respect to the first plane, and reflecting radio waves, wherein the area of ​​the first plane and the area of ​​the first inclined surface are related such that the difference between the maximum intensity of the reflected wave from the first plane and the maximum intensity of the reflected wave from the first inclined surface is less than or equal to a predetermined value, and the first inclined surface is inclined with respect to the first plane such that, in the angular distribution of the reflected wave with respect to a normal passing through the center of the first plane, the angular range of the reflected wave from the first plane and the reflected wave from the first inclined surface that exceeds the predetermined intensity overlap. [Effects of the Invention]

[0007] A radio wave reflector capable of reflecting radio waves within a narrow angular range in the forward direction can be provided. [Brief explanation of the drawing]

[0008] [Figure 1A] This figure shows an example of the configuration of a radio wave reflector according to the embodiment. [Figure 1B] This figure shows an example of the configuration of a radio wave reflector according to the embodiment. [Figure 1C] This figure shows an example of the angular distribution of reflected waves from a radio wave reflector according to the embodiment. [Figure 1D] This figure shows a magnified portion of Figure 1C. [Figure 2A] This figure shows an example of the configuration of a radio wave reflector in the first modified embodiment. [Figure 2B] This figure shows an example of the configuration of a radio wave reflector in the first modified embodiment. [Figure 2C] This figure shows an example of the angular distribution of reflected waves from a radio wave reflector in a first modified embodiment. [Figure 2D] This figure shows another example of the angular distribution of reflected waves from a radio wave reflector according to a first modified embodiment. [Figure 3A] This figure shows an example of the configuration of a radio wave reflector in a second modified example of the embodiment. [Figure 3B] This figure shows another example of the configuration of a radio wave reflector in a second modified example of the embodiment. [Figure 4A] This figure shows an example of the configuration of a radio wave reflector in another modified embodiment. [Figure 4B] This figure shows an example of the configuration of a radio wave reflector in another modified embodiment. [Figure 4C] This figure shows an example of the configuration of a radio wave reflector in another modified embodiment. [Figure 4D] This figure shows an example of the configuration of a radio wave reflector in another modified embodiment. [Modes for carrying out the invention]

[0009] Embodiments applying the radio wave reflector of this disclosure will be described below. In the following, the same elements may be denoted by the same reference numerals, and redundant explanations may be omitted.

[0010] The following describes the XYZ coordinate system. The directions parallel to the X-axis (X direction), the directions parallel to the Y-axis (Y direction), and the directions parallel to the Z-axis (Z direction) are mutually orthogonal. The XYZ coordinate system is an example of a Cartesian coordinate system. Viewing from the XY plane is called a front view. In the following, the length, width, thickness, etc. of each part may be exaggerated to make the configuration easier to understand. Also, terms such as parallel, right angle, orthogonal, horizontal, vertical, up and down should be used with a degree of deviation that does not impair the effect of the embodiment.

[0011] <Embodiment> Figures 1A and 1B show an example of the configuration of the radio wave reflector 100 according to the embodiment. Figure 1A is a front view, and Figure 1B shows an example of the configuration of the cross-section as seen by arrow AA in Figure 1A.

[0012] The radio wave reflector 100 includes a base 101, a first plane 110, and a first inclined surface 120A. The radio wave reflector 100 reflects radio waves with the first plane 110 and the first inclined surface 120A, and is a radio wave reflector capable of reflecting radio waves within a narrow angular range in the forward direction.

[0013] Here, the origin of the XYZ coordinates is taken as the center of the first plane 110. The first plane 110 is parallel to the XY plane, and the XYZ coordinates are defined such that the normal line passing through the center of the first plane 110 coincides with the Z-axis. That is, the first plane 110 is included in the XY plane. The front direction of the radio wave reflector 100 is the Z direction. The front direction of the radio wave reflector 100 coincides with the extending direction of the normal line of the first plane 110. The front direction of the radio wave reflector 100 is defined by the extending direction of the normal line of the first plane 110. FIG. 1B is a cross-section obtained by cutting the radio wave reflector 100 shown in FIG. 1A along the XZ plane.

[0014] The narrow angular range (narrow angle range) in the front direction is a range defined by a narrow angle centered on the normal line (Z-axis) passing through the center of the first plane 110. More specifically, the narrow angular range (narrow angle range) in the front direction is a plane (here, the XZ plane) parallel to the plane including the direction (here, the X direction) connecting the first plane 110 and the adjacent inclined plane (here, the first inclined plane 120A) and the front direction (Z direction), and is a range defined by a narrow angle centered on the normal line (Z-axis) passing through the center of the first plane 110 within the plane (here, the XZ plane) including the normal line (Z-axis) passing through the center of the first plane 110. As an example, the narrow angular range is an angular range within ±10 degrees centered on the normal line (Z-axis), more preferably an angular range within ±5 degrees centered on the normal line (Z-axis), and even more preferably an angular range within ±3 degrees centered on the normal line (Z-axis).

[0015] <Base 101> The base 101 is a member having the first plane 110 and the first inclined plane 120A formed on the +Z direction side. In FIGS. 1A and 1B, as an example, the base 101 is a bent plate-like member common to the first plane 110 and the first inclined plane 120A, but the base 101 is not limited to a bent plate-like member and may be, for example, a housing such as a box shape. The base 101 may be any member that can form the first plane 110 and the first inclined plane 120A. Also, the portions where the first plane 110 and the first inclined plane 120A are formed on the base 101 may be separately configured.

[0016] The base 101 can be made of, for example, resin, metal, or glass. Since the first flat surface 110 and the first inclined surface 120A, which are the surfaces of the base 101, need to be conductive surfaces, if the base 101 is made of resin or glass, the first flat surface 110 and the first inclined surface 120A can be made of surfaces that have been plated with a conductor or the like. For example, resins such as acrylic, polyvinyl chloride, and polyester can be used. For example, aluminum can be used as the metal.

[0017] <1st plane 110> The first plane 110 is a reflective surface perpendicular to the front direction of the radio wave reflector 100. This is because the front direction of the radio wave reflector 100 is defined by the direction of extension of the normal to the first plane 110. The first plane 110 is a flat surface. In a front view, the first plane 110 is, for example, rectangular. The first plane 110 is the only reflective surface of the radio wave reflector 100 that is perpendicular to the front direction. The length of the first plane 110 in the X direction is a1, and the length in the Y direction is b1.

[0018] Here, as shown in Figure 1B, we define the angle θ (degrees) with respect to the normal (Z-axis) passing through the center of the first plane 110. The angle θ is used to represent the reflection direction of the reflected wave in the XZ plane. As shown in Figure 1B, the angle θ is represented as a positive angle when tilted from the +Z direction to the +X direction in the XZ plane view, and as a negative angle when tilted from the +Z direction to the -X direction in the XZ plane view, on the opposite side of the angle θ shown in Figure 1B.

[0019] Furthermore, the first plane 110 is not limited to a rectangular shape, but may have any shape such as a polygon, circle, or ellipse. Also, the outer edge of the first plane 110 may have a shape corresponding to at least a part of a polygon, circle, or ellipse.

[0020] <1st slope 120A> The first inclined surface 120A is a reflective surface that is connected to the side of the first plane 110 that extends in the Y direction on the +X side, and is inclined with respect to the first plane 110. The lateral length of the first inclined surface 120A as viewed from the direction of extension of the normal n1 (hereinafter referred to as the lateral length of the first inclined surface 120A) is a2, and the length in the Y direction is b2. The area of ​​the first inclined surface 120A may be different from the area of ​​the first plane 110, but it is preferable that the difference between the areas is small. For example, the lateral length a2 of the first inclined surface 120A is equal to the length a1 of the first plane 110 in the X direction, and the Y length b2 of the first inclined surface 120A is equal to the Y length b1 of the first plane 110. For example, the area of ​​the first inclined surface 120A is equal to the area of ​​the first plane 110.

[0021] As shown in Figure 1B, the first inclined surface 120A is inclined with respect to the first plane 110 such that its boundary with the first plane 110 is a valley fold. In other words, in the XZ plane view, the first inclined surface 120A is located on the +X side of the first plane 110 and is inclined to approach the positive Z axis.

[0022] The first inclined surface 120A is, for example, rectangular in shape, with an edge extending in the Y direction on the -X direction side connected to the first plane 110. The first inclined surface 120A is not limited to a rectangular shape; it may also have a polygonal, circular, or elliptical shape. The first inclined surface 120A only needs to be inclined with respect to the first plane 110 while being connected to at least a portion of the outer edge of the first plane 110.

[0023] Such a first inclined surface 120A has the following relationship with the first plane 110. The area of ​​the first plane 110 and the area of ​​the first inclined surface 120A are related such that the difference between the maximum intensity of the reflected wave from the first plane 110 and the maximum intensity of the reflected wave from the first inclined surface 120A is less than or equal to a predetermined value. Furthermore, the first inclined surface 120A is inclined with respect to the first plane 110 such that, in the angular distribution of the reflected wave with respect to the normal passing through the center of the first plane 110, the angular range of the reflected wave from the first plane 110 and the reflected wave from the first inclined surface 120A that exceeds a predetermined intensity overlap.

[0024] <Criteria for evaluating the intensity of reflected waves> As an example of a criterion for evaluating the intensity of reflected waves, RCS (Radar Cross Section) is used. The unit of RCS is dBsm. In this embodiment, the angular distribution of reflected waves from the radio wave reflector 100 is evaluated using the angular distribution of reflected waves with respect to the normal passing through the center of the first plane 110.

[0025] When the direction of the normal coincides with the front direction of the radio wave reflector 100, as in the first plane 110, the RCS of the reflected wave of the first plane 110 in the front direction of the rectangular radio wave reflector 100 is: In numerical representation, it can be expressed by the following equation (1), using the length a1 in the X direction and the length b1 in the Y direction of the first plane 110. Here, λ is the wavelength of the radio wave in free space.

[0026]

number

[0027] Furthermore, in the case of a rectangular first inclined surface 120A, where the direction of the normal n1 makes an angle φ (φ≠0) with respect to the front direction of the radio wave reflector 100, the RCS of the reflected wave from the first inclined surface 120A in the front direction of the radio wave reflector 100 can be expressed by the following equation (2), using the lateral length a2 and the Y-direction length b2 of the first inclined surface 120A. Here, λ is the wavelength of the radio wave in free space. The Z' axis is an axis parallel to the Z axis. Equation (2) is the equation for finding the RCS of the first inclined surface 120A in the front direction of the radio wave reflector 100.

[0028]

number

[0029] Here, in order for the radio wave reflector 100 to reflect radio waves within a narrow angular range in the forward direction, the angle φ of the inclination of the first inclined surface 120A of the radio wave reflector 100 with respect to the forward direction is very small. The absolute value of the angle φ is, for example, about 0.5 to 5 degrees.

[0030] <Angular distribution of reflected waves relative to the normal passing through the center of the first plane 110> Figure 1C shows an example of the angular distribution of reflected waves from the radio wave reflector 100. The angular distribution of reflected waves from the radio wave reflector 100 shown in Figure 1C is the angular distribution of reflected waves with respect to the normal (Z-axis) passing through the center of the first plane 110, and is the result of calculations performed by electromagnetic field simulation. In the simulation, as an example, the angle between the normal n1 of the first inclined surface 120A and the Z-axis was set to 3 degrees. Also, under the condition that the areas of the first plane 110 and the first inclined surface 120A are equal as an example, the RCS was calculated for both the first plane 110 and the first inclined surface 120A using equation (1).

[0031] In Figure 1C, the horizontal axis represents the angle θ (degrees), and the vertical axis represents RCS (dBsm). As shown in Figure 1B, the angle θ on the horizontal axis is positive when it tilts from the +Z direction towards the +X direction in the XZ plane view, and negative when it tilts from the +Z direction towards the -X direction in the XZ plane view.

[0032] Figure 1C shows an example of the angular distribution of reflected waves when radio waves are incident on the radio wave reflector 100 from the -Z direction. The dashed line represents the angular distribution of the intensity of the reflected waves reflected by the first plane 110. The dashed line represents the angular distribution of the intensity of the reflected waves reflected by the first inclined surface 120A. The solid line represents the sum of the angular distributions of the dashed and dashed lines. In other words, the solid line represents the angular distribution of the sum of the intensity of the reflected waves reflected by the first plane 110 and the first inclined surface 120A.

[0033] As shown in Figure 1C, the angular distribution (dashed line) of the intensity of the reflected wave reflected by the first plane 110 shows that the maximum RCS was obtained when the angle θ was 0 degrees. This is thought to be because the first plane 110 reflects radio waves in the +Z direction, resulting in the maximum RCS being obtained at an angle θ of 0 degrees. The maximum RCS was approximately 7.4 dBsm. The intensity of the reflected wave decreased as the absolute value of the angle θ increased, and the RCS was approximately 0 dBsm when the angle θ was approximately +2.3 degrees and when the angle θ was approximately -2.3 degrees. In the angular range where the angle θ was approximately +2.3 degrees or higher, and in the angular range where the angle θ was approximately -2.3 degrees or lower, the RCS was approximately 0 dBsm or lower.

[0034] Furthermore, in the angular distribution of the intensity of the reflected wave reflected by the first inclined surface 120A (dash-dotted line), the maximum RCS was obtained when the angle θ was approximately -3 degrees. The first inclined surface 120A is located on the +X side of the first plane 110 and is inclined to approach the positive Z axis. Therefore, it reflects radio waves more towards the -X direction than the +Z direction, which is why the maximum RCS was obtained in the negative range of angle θ.

[0035] Furthermore, since the areas of the first inclined surface 120A and the first plane 110 are equal, the maximum RCS value of the first inclined surface 120A was approximately 7.4 dBsm.

[0036] The intensity of the reflected wave from the first inclined surface 120A was found to decrease as the angle θ moved away from approximately -3 degrees. The RCS was approximately 0 dBsm at angles θ of approximately -0.7 degrees and approximately -5.3 degrees. In the angular range where the angle θ was approximately -0.7 degrees or greater, and in the angular range where the angle θ was approximately -5.3 degrees or less, the RCS was approximately 0 dBsm or less.

[0037] Furthermore, in the angular distribution (solid line) of the total intensity of the reflected waves reflected from the first plane 110 and the first inclined surface 120A, the maximum RCS is obtained in the range of angle θ from 0 degrees to approximately -3 degrees. As an example, a characteristic is obtained that is like a flat connection between the maximum RCS of the reflected wave from the first plane 110 (θ=0 degrees) and the maximum RCS of the reflected wave from the first inclined surface 120A (θ≒-3 degrees). The maximum RCS was approximately 7.4 dBsm.

[0038] Furthermore, in the angular distribution (solid line) of the total intensity of the reflected waves reflected by the first plane 110 and the first inclined surface 120A, the RCS was approximately 0 dBsm at angles θ of approximately +2.3 degrees and approximately -5.3 degrees. In the angular range where the angle θ is approximately +2.3 degrees or greater, and in the angular range where the angle θ is approximately -5.3 degrees or less, the RCS was approximately 0 dBsm or less.

[0039] Thus, the angular distribution (solid line) of the total intensity of the reflected waves reflected by the first plane 110 and the first inclined surface 120A showed good values, with an RCS of approximately 3 dBsm or more in the angle θ range of approximately -5 degrees to +2.3 degrees. Furthermore, in other ranges (angles θ below approximately -5 degrees and above +2.3 degrees), the RCS decreased sharply, confirming that radio waves can be reflected within a narrow angular range in the forward direction.

[0040] Because the angle φ between the normal n1 of the first inclined surface 120A and the Z-axis is very small, making the areas of the first plane 110 and the first inclined surface 120A equal resulted in a nearly flat and nearly uniform angular distribution of the total intensity of reflected waves in a narrow angle range including the front direction. From this, it was confirmed that it is preferable to have a small difference between the areas of the first plane 110 and the first inclined surface 120A.

[0041] Figure 1D is a magnified view of the range in Figure 1C where the angle θ is within ±10 degrees and the range where the RCS is -10 dBsm or greater. In Figure 1D, the angle θ is shown on the vertical horizontal axis. In the simulation, the first inclined surface 120A was tilted relative to the first plane 110 such that the angle range θ2~θ3 where the intensity of the reflected wave from the first plane 110 is half of its maximum value overlaps with the angle range θ1~θ2 where the intensity of the reflected wave from the first inclined surface 120A is half of its maximum value.

[0042] The angular range in which the intensity of the reflected wave from the first plane 110 is half of its maximum value (approximately 7.4 dBsm) is the angular range θ2 to θ3 in which the intensity of the reflected wave from the first plane 110 is 3 dB lower than its maximum value (approximately 4.4 dBsm). The angular range in which the intensity of the reflected wave from the first inclined surface 120A is half of its maximum value (approximately 7.4 dBsm) is the angular range θ1 to θ2 in which the intensity of the reflected wave from the first inclined surface 120A is 3 dB lower than its maximum value (approximately 4.4 dBsm).

[0043] The angular range θ2~θ3 in which the intensity of the reflected wave from the first plane 110 is half of its maximum value, and the angular range θ1~θ2 in which the intensity of the reflected wave from the first inclined surface 120A is half of its maximum value, overlap at angle θ2. In other words, if the angle φ of the first inclined surface 120A becomes larger than this, the angular range in which the intensity of the reflected wave from the first plane 110 is half of its maximum value and the angular range in which the intensity of the reflected wave from the first inclined surface 120A is half of its maximum value will no longer overlap.

[0044] As the angular ranges θ1 to θ2 and θ2 to θ3 overlap, the angular distribution of the total intensity of the reflected waves (solid line) between the angle θt2 at which the intensity of the reflected wave from the first plane 110 is maximized and the angle θt1 at which the intensity of the reflected wave from the first inclined surface 120A is maximized becomes approximately flat in a narrow angular range that includes the forward direction (θ=0 degrees).

[0045] From this, it was confirmed that by setting the angle φ of the first inclined surface 120A so that the angular ranges corresponding to half the maximum value of the reflected wave intensity overlap, the angular range in which the maximum value of the reflected wave intensity can be obtained can be widened. Furthermore, it was confirmed that the equality of the maximum values ​​of the reflected wave intensity is achieved by the equality of the areas of the first plane 110 and the first inclined surface 120A.

[0046] Furthermore, if the angle φ of the first inclined surface 120A is increased compared to the angle φ obtained in Figures 1C and 1D, the angular ranges of half the maximum value of the reflected wave intensity of the first plane 110 and the first inclined surface 120A will no longer overlap, and a trough lower than the maximum value will be created near the front direction of the angular distribution of the total reflected wave intensity.

[0047] However, if it does not pose a practical problem, a trough lower than the maximum value may occur near the front direction in the angular distribution of the total intensity of the reflected waves. For this reason, the first inclined surface 120A should be inclined with respect to the first plane 110 such that the angular range of the reflected waves from the first plane 110 and the reflected waves from the first inclined surface 120A that are greater than or equal to a predetermined intensity overlap in the angular distribution of the reflected waves with respect to the normal passing through the center of the first plane 110. The predetermined intensity should be greater than or equal to the reflected wave intensity in the trough described above.

[0048] Furthermore, since the areas of the first plane 110 and the first inclined surface 120A are equal, the maximum values ​​of the reflected wave intensities are also equal. It was confirmed that in order to increase the total intensity of the reflected wave near the front direction to a certain extent, it is preferable that the difference between the areas of the first plane 110 and the first inclined surface 120A be small. In other words, it was confirmed that it is preferable that the area of ​​the first plane 110 and the area of ​​the first inclined surface 120A have a relationship such that the difference between the maximum value of the reflected wave intensity of the first plane 110 and the maximum value of the reflected wave intensity of the first inclined surface 120A is less than or equal to a predetermined value.

[0049] <First modified example of the embodiment> Figures 2A and 2B show an example of the configuration of a radio wave reflector 100A of the first modified embodiment. Figure 2A is a front view, and Figure 2B shows an example of the configuration of the cross-section as seen by arrow BB in Figure 2A.

[0050] The radio wave reflector 100A includes a base 101, a first plane 110, a first inclined surface 120A, and a second inclined surface 120B. The first modified radio wave reflector 100A of the embodiment has a configuration in which the second inclined surface 120B is added to the radio wave reflector 100 of the embodiment (see Figures 1A and 1B). The radio wave reflector 100A is a radio wave reflector that reflects radio waves with the first plane 110, the first inclined surface 120A, and the second inclined surface 120B, and is capable of reflecting radio waves within a narrow angular range in the front direction. The differences from the radio wave reflector 100 will be explained below.

[0051] <Base 101> The base 101 of the first modified embodiment is a member having a first plane 110, a first inclined surface 120A, and a second inclined surface 120B formed on the +Z direction side. In Figures 2A and 2B, the base 101 is, for example, a bent plate-like member common to the first plane 110, the first inclined surface 120A, and the second inclined surface 120B, but the base 101 is not limited to a bent plate-like member, and may be a housing such as a box. The base 101 is a member that can form the first plane 110 and the first inclined surface 120A. Also, the base 101 may be constructed with separate parts for which the first plane 110 and the first inclined surface 120A are formed. The material of the base 101 is the same as that of the base 101 shown in Figures 1A and 1B.

[0052] <Second slope 120B> The second inclined surface 120B is located on the opposite side of the first inclined surface 120A, with the first plane 110 in between. The second inclined surface 120B is connected to the side of the first plane 110 that extends in the Y direction on the -X direction side, and is a reflective surface composed of a flat surface inclined with respect to the first plane 110. The area of ​​the second inclined surface 120B may differ from the area of ​​the first plane 110, but it is preferable that the difference between the areas be small. Also, the area of ​​the second inclined surface 120B may differ from the area of ​​the first inclined surface 120A, but it is preferable that the difference between the areas be small.

[0053] For example, the lateral length of the second inclined surface 120B as viewed from the direction of extension of the normal n2 (hereinafter referred to as the lateral length of the second inclined surface 120B) is equal to the length of the first plane 110 in the X direction and is also equal to the lateral length of the first inclined surface 120A. The length of the second inclined surface 120B in the Y direction is equal to the length of the first plane 110 in the Y direction and is also equal to the length of the first inclined surface 120A in the Y direction. Therefore, for example, the area of ​​the second inclined surface 120B is equal to the area of ​​the first plane 110 and the first inclined surface 120A.

[0054] As shown in Figure 2B, the second inclined surface 120B is inclined with respect to the first plane 110 such that its boundary with the first plane 110 is a valley fold. In other words, in the XZ plane view, the second inclined surface 120B is located on the -X side of the first plane 110 and is inclined to approach the + Z axis. The angle of the second inclined surface 120B with respect to the first plane 110 may be different from the angle of the first inclined surface 120A with respect to the first plane 110, but from the viewpoint of symmetry, it is preferable that their inclination angles are equal. In Figure 2B, the angles (inclination angles) of both the second inclined surface 120B and the first inclined surface 120A with respect to the first plane 110 are both φ in absolute value.

[0055] The second inclined surface 120B is, for example, rectangular, with an edge extending in the Y direction on the +X direction side connected to the first plane 110. The second inclined surface 120B is not limited to a rectangular shape, but may have any shape such as a polygon, circle, or ellipse. The second inclined surface 120B only needs to be inclined with respect to the first plane 110 while being connected to at least a part of the outer edge of the first plane 110. From the viewpoint of symmetry, it is most preferable that the shape of the second inclined surface 120B is the same as the shape of the first inclined surface 120A, and in this case, it is most preferable that the areas of the second inclined surface 120B and the first inclined surface 120A are equal and the angles with respect to the first plane 110 are equal.

[0056] Such a second inclined surface 120B has the following relationship with the first plane 110. The area of ​​the first plane 110 and the area of ​​the second inclined surface 120B are related such that the difference between the maximum intensity of the reflected wave from the first plane 110 and the maximum intensity of the reflected wave from the second inclined surface 120B is less than or equal to a predetermined value. Furthermore, the second inclined surface 120B is inclined with respect to the first plane 110 such that, in the angular distribution of the reflected wave with respect to the normal passing through the center of the first plane 110, the angular range of the reflected wave from the first plane 110 and the reflected wave from the second inclined surface 120B that exceeds a predetermined intensity overlap. This is similar to the relationship between the first plane 110 and the first inclined surface 120A.

[0057] <Angular distribution of reflected waves relative to the normal passing through the center of the first plane 110> Figure 2C shows an example of the angular distribution of reflected waves from the radio wave reflector 100A. The angular distribution of reflected waves from the radio wave reflector 100A shown in Figure 2C is the angular distribution of reflected waves with respect to the normal (Z-axis) passing through the center of the first plane 110, and is the result of calculations performed by electromagnetic field simulation. In the simulation, as an example, the angle between the normal n1 of the first inclined surface 120A and the Z-axis was set to 3 degrees in absolute value, and the angle between the normal n2 of the second inclined surface 120B and the Z-axis was set to 3 degrees in absolute value. Also, under the condition that the areas of the first plane 110, the first inclined surface 120A, and the second inclined surface 120B are equal as an example, the RCS was calculated for all of the first plane 110, the first inclined surface 120A, and the second inclined surface 120B using equation (1).

[0058] In Figure 2C, the horizontal axis represents the angle θ (degrees), and the vertical axis represents RCS (dBsm). As shown in Figure 2B, the angle θ on the horizontal axis is positive when tilted from the +Z direction to the +X direction in the XZ plane view, and negative when tilted from the +Z direction to the -X direction in the XZ plane view.

[0059] Figure 2C shows an example of the angular distribution of reflected waves when radio waves are incident on the radio wave reflector 100A from the -Z direction. The dashed line represents the angular distribution of the intensity of the reflected wave reflected by the first plane 110. The dashed line represents the angular distribution of the intensity of the reflected wave reflected by the first inclined surface 120A. The dashed line represents the angular distribution of the intensity of the reflected wave reflected by the second inclined surface 120B. The solid line represents the sum of the angular distributions of the dashed, dashed, and dashed lines. That is, the solid line represents the angular distribution of the sum of the intensity of the reflected waves reflected by the first plane 110, the first inclined surface 120A, and the second inclined surface 120B.

[0060] In Figure 2C, the angular distribution of the intensity of the reflected wave reflected from the first plane 110 (dashed line) and the angular distribution of the intensity of the reflected wave reflected from the first inclined surface 120A (dotted line) are identical to the results shown in Figure 1C.

[0061] Furthermore, the angular distribution of the intensity of the reflected wave reflected by the second inclined surface 120B (dotted line) is symmetric to the angular distribution of the intensity of the reflected wave reflected by the first inclined surface 120A (single dotted line) in the direction in which the angle θ increases or decreases with respect to 0 degrees (θ=0 degrees), which corresponds to the front direction (lateral direction in Figure 2C), and the maximum value was obtained at an angle θ of approximately 3.5 degrees. The second inclined surface 120B is located on the -X side of the first plane 110 and is inclined to approach the Z axis on the + side, and it reflects radio waves more towards the +X direction than the +Z direction, so it is thought that the maximum value of RCS was obtained in the positive range of angle θ.

[0062] Furthermore, since the area of ​​the second inclined surface 120B is equal to that of the first plane 110 and the first inclined surface 120A, the maximum RCS value of the second inclined surface 120B was approximately equal to the maximum values ​​of the first plane 110 and the first inclined surface 120A, which was approximately 7.4 dBsm.

[0063] Furthermore, in the angular distribution (solid line) of the total intensity of the reflected waves reflected from the first plane 110, the first inclined surface 120A, and the second inclined surface 120B, the maximum RCS is obtained in the range of angle θ from approximately -3 degrees to approximately +3 degrees. As an example, a characteristic is obtained that is like a flat connection between the maximum RCS of the reflected wave from the first inclined surface 120A (θ ≈ -3 degrees) and the maximum RCS of the reflected wave from the second inclined surface 120B (θ ≈ +3 degrees). The maximum RCS was approximately 7.4 dBsm.

[0064] Furthermore, in the angular distribution (solid line) of the total intensity of reflected waves reflected from the first plane 110 and the first inclined surface 120A, the RCS was approximately 0 dBsm at angles θ of approximately -5.5 degrees and approximately +5.5 degrees. In the angular range where angle θ is approximately -5.5 degrees or less, and in the angular range where angle θ is approximately +5.5 degrees or more, the RCS was approximately 0 dBsm or less.

[0065] Thus, the angular distribution (solid line) of the total intensity of the reflected waves reflected by the first plane 110, the first inclined surface 120A, and the second inclined surface 120B showed good values ​​where the RCS was approximately 3 dBsm or higher in the angle θ range from approximately -4.8 degrees to +5 degrees. Furthermore, in other ranges (angles θ below approximately -4.8 degrees and above +5 degrees), the RCS decreased sharply, confirming that radio waves can be reflected within a narrow angular range in the forward direction.

[0066] Because the angle φ between the normal to the first inclined surface 120A and the Z-axis is very small, making the areas of the first plane 110, the first inclined surface 120A, and the second inclined surface 120B equal resulted in a nearly flat and nearly uniform angular distribution of the total intensity of reflected waves in a narrow angle range including the front direction. From this, it was confirmed that it is preferable to have a small difference between the areas of the first plane 110, the first inclined surface 120A, and the second inclined surface 120B.

[0067] Furthermore, in the simulation, the first inclined surface 120A was tilted relative to the first plane 110 such that the angular range θ2~θ3 where the intensity of the reflected wave from the first plane 110 is half of its maximum value overlaps with the angular range θ3~θ4 where the intensity of the reflected wave from the second inclined surface 120B is half of its maximum value. Note that the angular range θ2~θ3 where the intensity of the reflected wave from the first plane 110 is half of its maximum value and the angular range θ1~θ2 where the intensity of the reflected wave from the first inclined surface 120A is half of its maximum value overlap, as explained using Figure 1D.

[0068] The angular range in which the intensity of the reflected wave from the second inclined surface 120B becomes half of its maximum value (approximately 7.4 dBsm) is the angular range θ3 to θ4 in which the intensity of the reflected wave from the second inclined surface 120B becomes 3 dB lower than its maximum value (approximately 4.4 dBsm).

[0069] The angular range θ2~θ3 in which the intensity of the reflected wave from the first plane 110 is half of its maximum value, and the angular range θ3~θ4 in which the intensity of the reflected wave from the second inclined surface 120B is half of its maximum value, overlap at angle θ3. In other words, if the absolute value of the angle φ of the second inclined surface 120B becomes larger than this, the angular range in which the intensity of the reflected wave from the second inclined surface 120B is half of its maximum value and the angular range in which the intensity of the reflected wave from the first inclined surface 120A is half of its maximum value will no longer overlap.

[0070] As the angular ranges θ1 to θ2 and θ2 to θ3 overlap, and the angular ranges θ2 to θ3 and θ3 to θ4 also overlap, the angular distribution of the total intensity of the reflected waves (solid line) between the angle θt1 at which the intensity of the reflected wave from the first inclined surface 120A is maximized and the angle θt3 at which the intensity of the reflected wave from the second inclined surface 120B is maximized becomes approximately flat in a narrow angular range that includes the forward direction (θ=0 degrees).

[0071] From this, it was confirmed that by setting the angles φ of the first inclined surface 120A and the second inclined surface 120B so that the angular ranges of half the maximum value of the reflected wave intensity overlap, the angular range in which the maximum value of the reflected wave intensity can be obtained can be widened compared to the radio wave reflector 100 shown in Figures 1A and 1B. Furthermore, it was confirmed that the equality of the three maximum values ​​of the reflected wave intensity is achieved by the equality of the areas of the first plane 110, the first inclined surface 120A, and the second inclined surface 120B.

[0072] Furthermore, if the angle φ of the second inclined surface 120B is made larger than the angle φ obtained in Figure 2C, the angular ranges of half the maximum value of the reflected wave intensity of the first plane 110 and the second inclined surface 120B will no longer overlap, and a trough lower than the maximum value will be created near the front direction of the angular distribution of the total reflected wave intensity.

[0073] However, if it does not pose a practical problem, a trough lower than the maximum value may occur near the front direction in the angular distribution of the total intensity of the reflected waves. For this reason, the second inclined surface 120B should be inclined with respect to the first plane 110 such that the angular range of the reflected waves from the first plane 110 and the reflected waves from the second inclined surface 120B that are greater than or equal to a predetermined intensity overlap in the angular distribution of the reflected waves with respect to the normal passing through the center of the first plane 110. The predetermined intensity should be greater than or equal to the reflected wave intensity in the trough described above. This is also true for the relationship between the first plane 110 and the first inclined surface 120A, as explained using Figures 1A to 1D.

[0074] Furthermore, since the areas of the first plane 110, the first inclined surface 120A, and the second inclined surface 120B are equal, the maximum values ​​of the reflected wave intensities are also equal. In order to increase the total intensity of the reflected wave near the front direction to a certain extent, it was confirmed that it is preferable for the difference between the areas of the first plane 110, the first inclined surface 120A, and the second inclined surface 120B to be small. In other words, it was confirmed that it is preferable for the areas of the first plane 110, the first inclined surface 120A, and the second inclined surface 120B to have a relationship such that the difference between the maximum value of the reflected wave intensity of the first plane 110, the maximum value of the reflected wave intensity of the first inclined surface 120A, and the maximum value of the reflected wave intensity of the second inclined surface 120B is less than or equal to a predetermined value.

[0075] For example, if the maximum intensity of the reflected waves from the first inclined surface 120A and the second inclined surface 120B is greater than the maximum intensity of the reflected wave from the first plane 110, and the maximum intensity values ​​of the reflected waves from the first inclined surface 120A and the second inclined surface 120B are equal, then the characteristics shown in Figure 2D can be obtained.

[0076] Figure 2D shows another example of the angular distribution of reflected waves from the radio wave reflector 100A according to the first modification of the embodiment. The characteristics in Figure 2D were calculated by electromagnetic field simulation, similar to Figure 2C.

[0077] In Figure 2D, the dashed line represents the angular distribution of the intensity of the reflected wave reflected from the first plane 110, the dashed line represents the angular distribution of the intensity of the reflected wave reflected from the first inclined surface 120A, the dashed line represents the angular distribution of the intensity of the reflected wave reflected from the second inclined surface 120B, and the solid line represents the angular distribution of the total intensity of the reflected waves reflected from the first plane 110, the first inclined surface 120A, and the second inclined surface 120B.

[0078] Since the maximum intensity of the reflected waves from the first inclined surface 120A and the second inclined surface 120B is greater than the maximum intensity of the reflected wave from the first plane 110, the areas of the first inclined surface 120A and the second inclined surface 120B are larger than the area of ​​the first plane 110. Also, since the maximum intensity of the reflected waves from the first inclined surface 120A and the second inclined surface 120B are equal, the areas of the first inclined surface 120A and the second inclined surface 120B are equal.

[0079] In such cases, as an example, a distribution is obtained in which the intensity is maximized in the forward direction, as shown by the solid line in Figure 2D.

[0080] <Second Modification of Embodiment> Figure 3A shows an example of the configuration of the radio wave reflector 100B in a second modified example of the embodiment.

[0081] The radio wave reflector 100B has a configuration in which trapezoidal first inclined surfaces 120A to fourth inclined surfaces 120D are provided along the rectangular outer edge (four sides) of the first plane 110. Note that the base 101 has a different shape from the base 101 shown in Figures 1A, 1B, 2A, and 2B in accordance with this configuration.

[0082] More specifically, the radio wave reflector 100B has a configuration in which the first inclined surface 120A and the second inclined surface 120B shown in Figures 2A and 2B are changed to a trapezoidal shape, a trapezoidal third inclined surface 120C is connected to the -Y direction end of the first plane 110, and a trapezoidal fourth inclined surface 120D is connected to the +Y direction end of the first plane 110. The sides of the first inclined surface 120A, the second inclined surface 120B, the third inclined surface 120C, and the fourth inclined surface 120D, corresponding to the top base of the trapezoid, are connected to the four sides of the first plane 110.

[0083] Therefore, the cross-section obtained by cutting the radio wave reflector 100B through the XZ plane passing through the center of the first plane 110 is the same as in Figure 2B, and the cross-section obtained by cutting the radio wave reflector 100B through the XY plane passing through the center of the first plane 110 has the same configuration as in Figure 2B, with the first inclined surface 120A and the second inclined surface 120B replaced by the third inclined surface 120C and the fourth inclined surface 120D.

[0084] The intensity distribution of the reflected waves reflected by the radio wave reflector 100B is such that, in both the XY and XZ cross-sections passing through the center of the first plane 110, the reflected wave intensity is higher on both sides of 0 degrees, as shown in Figure 2C or Figure 2D.

[0085] As an example, the first inclined surface 120A, the third inclined surface 120C, the second inclined surface 120B, and the fourth inclined surface 120D are trapezoidal in shape and are arranged in this order, surrounding the four sides of the rectangular outer edge of the first plane 110 when viewed from the front. The first inclined surface 120A, the third inclined surface 120C, the second inclined surface 120B, and the fourth inclined surface 120D are arranged without gaps along the four sides of the first plane 110 in a mortar-like or tapered shape. As a result, the reflected waves from the first inclined surface 120A and the second inclined surface 120B are combined symmetrically and more uniformly, and the reflected waves from the third inclined surface 120C and the fourth inclined surface 120D are combined symmetrically and more uniformly. This makes it possible to provide a radio wave reflector 100 with high symmetry in the angular distribution in both the XY and XZ cross-sections within a desired angular range (narrow angle range) in the front direction, and with uniform radio wave intensity.

[0086] As an example, the inclination angles of the first inclined surface 120A and the second inclined surface 120B with respect to the first plane 110 may be equal, and the inclination angles of the third inclined surface 120C and the fourth inclined surface 120D with respect to the first plane 110 may be equal. As an example, the inclination angles of the first inclined surface 120A and the third inclined surface 120C with respect to the first plane 110 may be equal. In this case, a distribution is obtained in which the reflected wave intensity is high on both sides of 0 degrees in both the XY and XZ cross-sections passing through the center of the first plane 110, and the angular distribution in both the XY and XZ cross-sections passing through the center of the first plane 110 can be equalized.

[0087] As an example, the inclination angles of the first inclined surface 120A and the second inclined surface 120B with respect to the first plane 110 may be equal, the inclination angles of the third inclined surface 120C and the fourth inclined surface 120D with respect to the first plane 110 may be equal, and the inclination angles of the first inclined surface 120A and the third inclined surface 120C with respect to the first plane 110 may be different. In this case, a distribution is obtained in which the reflected wave intensity is high on both sides of 0 degrees in both the XY and XZ cross-sections passing through the center of the first plane 110, and the angular distribution can be made different in the XY and XZ cross-sections passing through the center of the first plane 110.

[0088] Furthermore, if the reflection direction is deliberately shifted relative to the front direction, the inclination angles of the first inclined surface 120A and the second inclined surface 120B with respect to the first plane 110 do not have to be equal. Similarly, the inclination angles of the third inclined surface 120C and the fourth inclined surface 120D with respect to the first plane 110 do not have to be equal. For example, by setting the inclination angles of the first inclined surface 120A and the second inclined surface 120B with respect to the first plane 110, it is possible to obtain a reflected wave intensity distribution that includes the front direction and is biased towards the +X or -X direction relative to the +Z direction in an XZ plane view. Also, for example, by setting the inclination angles of the third inclined surface 120C and the fourth inclined surface 120D with respect to the first plane 110, it is possible to obtain a reflected wave intensity distribution that includes the front direction and is biased towards the -Y or +Y direction relative to the +Z direction in an XY plane view.

[0089] Furthermore, the areas of the first plane 110, the first inclined surface 120A, the second inclined surface 120B, the third inclined surface 120C, and the fourth inclined surface 120D may be equal. The total reflected wave intensity of the reflected waves from the five reflecting surfaces can be equalized in both the XY and XZ cross-sections within a narrow angle range including the front direction.

[0090] Furthermore, the first inclined surface 120A may be inclined with respect to the first plane 110 such that, in the angular distribution of the reflected wave with respect to the normal passing through the center of the first plane 110, the angular range in which the intensity of the reflected wave from the first plane 110 is half of its maximum value and the angular range in which the intensity of the reflected wave from the first inclined surface 120A is half of its maximum value overlap.

[0091] In this case, the second inclined surface 120B may be inclined with respect to the first plane 110 such that, in the angular distribution of the reflected wave with respect to the normal passing through the center of the first plane 110, the angular range in which the intensity of the reflected wave from the first plane 110 is half of its maximum value overlaps with the angular range in which the intensity of the reflected wave from the second inclined surface 120B is half of its maximum value.

[0092] In this case, the third inclined surface 120C may be inclined with respect to the first plane 110 such that, in the angular distribution of the reflected wave with respect to the normal passing through the center of the first plane 110, the angular range in which the intensity of the reflected wave from the first plane 110 is half of its maximum value and the angular range in which the intensity of the reflected wave from the third inclined surface 120C is half of its maximum value overlap.

[0093] In this case, the fourth inclined surface 120D may be inclined with respect to the first plane 110 such that, in the angular distribution of the reflected wave with respect to the normal passing through the center of the first plane 110, the angular range in which the intensity of the reflected wave from the first plane 110 is half of its maximum value overlaps with the angular range in which the intensity of the reflected wave from the fourth inclined surface 120D is half of its maximum value.

[0094] In these cases, the angular range over which the maximum reflected wave intensity can be obtained can be broadened.

[0095] Furthermore, as shown in Figure 3B, the four corners of the first inclined surface 120A, the third inclined surface 120C, the second inclined surface 120B, and the fourth inclined surface 120D of the radio wave reflector 100B may be chamfered. The trapezoidal shape of the first inclined surface 120A, the third inclined surface 120C, the second inclined surface 120B, and the fourth inclined surface 120D includes such shapes.

[0096] Furthermore, using Figures 3A and 3B, an embodiment in which four first inclined surfaces 120A, third inclined surface 120C, second inclined surface 120B, and fourth inclined surface 120D are provided around the first plane 110 has been described. However, the radio wave reflector 100B may also have a configuration that includes any three of the first inclined surface 120A, third inclined surface 120C, second inclined surface 120B, and fourth inclined surface 120D around the first plane 110.

[0097] <Other variations of Embodiment 1> Figures 4A to 4D show examples of the configurations of radio wave reflectors 100C1 to 100C4, which are other modifications of Embodiment 1. In Figures 4A to 4D, the base 101 is omitted, and only the configuration of the reflective surface is shown in a front view.

[0098] The radio wave reflector 100C1 shown in Figure 4A has a configuration in which the first plane 110, the first inclined surface 120A, and the second inclined surface 120B of the radio wave reflector 100A shown in Figure 2A are deformed into an ellipse shape. The shapes of the first plane 110, the first inclined surface 120A, and the second inclined surface 120B may be circular instead of ellipse. For example, such a shape may be used to suit constraints such as the surrounding configuration of the place where the base 101 is installed.

[0099] The radio wave reflector 100C2 shown in Figure 4B has a configuration in which the first plane 110, the first inclined surface 120A, and the second inclined surface 120B of the radio wave reflector 100A shown in Figure 2A are deformed into hexagons (polygons). The polygon can be any polygon with three or more sides, and in the case of a quadrilateral, it may be a rhombus or the like. Such a shape may be adopted in accordance with constraints such as the surrounding configuration of the place where the base 101 is installed. Note that the positions of the first inclined surface 120A and the second inclined surface 120B with respect to the first plane 110 may be offset in the Y direction.

[0100] The radio wave reflector 100C3 shown in Figure 4C has a configuration in which the first plane 110 and the first inclined surface 120A of the radio wave reflector 100 shown in Figure 1A are deformed into triangles. For example, such a shape may be adopted to suit constraints such as the surrounding configuration of the place where the base 101 is installed.

[0101] The radio wave reflector 100C4 shown in Figure 4D has a configuration in which the first plane 110, first inclined surface 120A, second inclined surface 120B, third inclined surface 120C, and fourth inclined surface 120D of the radio wave reflector 100B shown in Figure 3A are deformed into an ellipse shape. The shapes of the first plane 110, first inclined surface 120A, second inclined surface 120B, third inclined surface 120C, and fourth inclined surface 120D may be circular instead of ellipse. For example, such a shape may be used to suit constraints such as the surrounding configuration of the place where the base 101 is installed.

[0102] Furthermore, while Figures 4A to 4D illustrate configurations in which the reflective surfaces have elliptical, circular, and polygonal shapes with three or more sides, the outer edge of at least one of the multiple reflective surfaces may have a shape corresponding to at least a part of the polygonal, circular, and elliptical shapes. This allows for the provision of radio wave reflectors 100 with a high degree of flexibility in shape to suit various applications and surrounding constraints.

[0103] Furthermore, the first inclined surface 120A may be an inclined surface that surrounds the entire circumference of the outer edge of the first plane 110. For example, if the first plane 110 is circular or elliptical, the first inclined surface 120A may be a bowl-shaped or tapered inclined surface that surrounds the entire circumference of the outer edge of the circular or elliptical first plane 110. For example, such a shape may be adopted to suit constraints such as the surrounding configuration of the place where the base 101 is installed. This allows for the provision of radio wave reflectors 100 with a high degree of freedom in shape to suit various applications and surrounding constraints.

[0104] <Effects> The radio wave reflector 100 includes a first plane 110 that reflects radio waves and a first inclined surface 120A that is connected to at least a portion of the outer edge of the first plane 110, is inclined with respect to the first plane 110, and reflects radio waves. The area of ​​the first plane 110 and the area of ​​the first inclined surface 120A are related such that the difference between the maximum intensity of the reflected wave from the first plane 110 and the maximum intensity of the reflected wave from the first inclined surface 120A is less than or equal to a predetermined value. The first inclined surface 120A is inclined with respect to the first plane 110 such that, in the angular distribution of the reflected wave with respect to the normal passing through the center of the first plane 110, the angular range of the reflected wave from the first plane 110 and the angular range of the reflected wave from the first inclined surface 120A that exceeds the predetermined intensity overlap. As a result, a radio wave reflector 100 having a desired angular range (narrow angle range) in the front direction can be obtained.

[0105] Therefore, it is possible to provide a radio wave reflector 100 that can reflect radio waves within a narrow angular range in the forward direction.

[0106] Furthermore, the first plane 110 may be rectangular in shape. This makes it possible to provide a radio wave reflector 100 that is easy to process and capable of reflecting radio waves within a narrow angular range in the front direction.

[0107] Furthermore, the first inclined surface 120A may be rectangular in shape. This makes it possible to provide a radio wave reflector 100 that is easy to process and capable of reflecting radio waves within a narrow angular range in the front direction.

[0108] Furthermore, the second inclined surface 120B is connected to at least a portion of the outer edge of the first plane 110, is inclined with respect to the first plane 110, and reflects radio waves, and further includes the second inclined surface 120B located on the opposite side of the first inclined surface 120A across the first plane 110, and the area of ​​the first plane 110 and the area of ​​the second inclined surface 120B have a relationship such that the difference between the maximum value of the intensity of the reflected wave from the first plane 110 and the maximum value of the intensity of the reflected wave from the second inclined surface 120B is less than or equal to a predetermined value, and the second inclined surface 120B may be inclined with respect to the first plane 110 such that, in the angular distribution of the reflected wave with respect to the normal passing through the center of the first plane 110, the angular range of the reflected wave from the first plane 110 and the reflected wave from the second inclined surface 120B with respect to a predetermined intensity or greater overlap. Therefore, by combining the reflected waves from the first plane 110, the first inclined surface 120A, and the second inclined surface 120B, it is possible to provide a radio wave reflector 100 with more uniform radio wave intensity in a desired angular range (narrow angle range) in the forward direction.

[0109] Furthermore, the inclination angles of the first inclined surface 120A and the second inclined surface 120B with respect to the first plane 110 may be equal. When the reflected waves from the first plane 110, the first inclined surface 120A, and the second inclined surface 120B are combined, the reflected waves from the first inclined surface 120A and the second inclined surface 120B are combined more symmetrically and uniformly, and a radio wave reflector 100 can be provided that has high symmetry and uniform radio wave intensity in a desired angular range (narrow angle range) in the front direction.

[0110] The areas of the first plane 110 and the first inclined surface 120A may be equal. When the reflected waves from the first plane 110, the first inclined surface 120A, and the second inclined surface 120B are combined, the reflected waves from the first inclined surface 120A and the second inclined surface 120B are combined more symmetrically and uniformly, and a radio wave reflector 100 can be provided that has high symmetry and uniform radio wave intensity in a desired angular range (narrow angle range) in the front direction.

[0111] In the angular distribution of reflected waves with respect to a normal passing through the center of the first plane 110, the first inclined surface 120A may be inclined with respect to the first plane 110 such that the angular range in which the intensity of reflected waves from the first plane 110 is half of its maximum value overlaps with the angular range in which the intensity of reflected waves from the first inclined surface 120A is half of its maximum value. This makes it possible to make the angular distribution of the total intensity of reflected waves in a narrow angular range including the front direction substantially flat and substantially uniform, and to provide a radio wave reflector 100 that has high symmetry in a desired angular range (narrow angular range) in the front direction, and furthermore, has the characteristic of uniform and flat radio wave intensity.

[0112] Although exemplary embodiments of radio wave reflectors of this disclosure have been described above, this disclosure is not limited to the specifically disclosed embodiments, and various modifications and changes are possible without departing from the scope of the claims.

[0113] This international application claims priority based on Japanese Patent Application No. 2023-033934, filed on March 6, 2023, the entire contents of which are incorporated herein by reference. [Explanation of Symbols]

[0114] 100, 100A, 100B, 100C1~100C4 Radio wave reflector 101 Base 110 1st plane 120A 1st slope 120B 2nd slope 120C 3rd slope 120D 4th slope

Claims

1. A first plane that reflects radio waves, A first inclined surface connected to at least a portion of the outer edge of the first plane, inclined with respect to the first plane, and reflecting radio waves Includes, The area of ​​the first plane and the area of ​​the first inclined surface are related such that the difference between the maximum value of the reflected wave intensity of the first plane and the maximum value of the reflected wave intensity of the first inclined surface is less than or equal to a predetermined value. A radio wave reflector in which the first inclined surface is inclined with respect to the first plane such that, in the angular distribution of reflected waves with respect to a normal passing through the center of the first plane, the angular range of the reflected waves from the first plane and the reflected waves from the first inclined surface exceeding a predetermined intensity overlap.

2. The radio wave reflector according to claim 1, wherein the first plane is rectangular in shape.

3. The radio wave reflector according to claim 2, wherein the first inclined surface is rectangular in shape.

4. A second inclined surface connected to at least a portion of the outer edge of the first plane, inclined with respect to the first plane, and reflecting radio waves, further including a second inclined surface located on the opposite side of the first inclined surface across the first plane, The area of ​​the first plane and the area of ​​the second inclined surface are related such that the difference between the maximum value of the reflected wave intensity of the first plane and the maximum value of the reflected wave intensity of the second inclined surface is less than or equal to the predetermined value. The radio wave reflector according to claim 3, wherein the second inclined surface is inclined with respect to the first plane such that, in the angular distribution of reflected waves with respect to a normal passing through the center of the first plane, the angular range of the reflected waves from the first plane and the reflected waves from the second inclined surface that are greater than or equal to the predetermined intensity overlap.

5. The radio wave reflector according to claim 4, wherein the inclination angles of the first inclined surface and the second inclined surface with respect to the first plane are equal.

6. The radio wave reflector according to any one of claims 1 to 5, wherein the areas of the first plane and the first inclined surface are equal.

7. The radio wave reflector according to claim 6, wherein, in the angular distribution of reflected waves with respect to a normal passing through the center of the first plane, the first inclined surface is inclined with respect to the first plane such that the angular range in which the intensity of the reflected waves from the first plane is half of its maximum value overlaps with the angular range in which the intensity of the reflected waves from the first inclined surface is half of its maximum value.

8. A second inclined surface connected to at least a portion of the outer edge of the first plane, inclined with respect to the first plane, and reflecting radio waves, A third inclined surface connected to at least a portion of the outer edge of the first plane, inclined with respect to the first plane, and reflecting radio waves, A fourth inclined surface connected to at least a portion of the outer edge of the first plane, inclined with respect to the first plane, and reflecting radio waves. It further includes, The radio wave reflector according to claim 2, wherein the first inclined surface, the third inclined surface, the second inclined surface, and the fourth inclined surface are trapezoidal in shape and are arranged in this order surrounding the four sides of the rectangular outer edge of the first plane.

9. The inclination angles of the first inclined surface and the second inclined surface with respect to the first plane are equal, The inclination angles of the third and fourth inclined surfaces with respect to the first plane are equal, The radio wave reflector according to claim 8, wherein the inclination angles of the first inclined surface and the third inclined surface with respect to the first plane are different.

10. The inclination angles of the first inclined surface and the second inclined surface with respect to the first plane are equal, The inclination angles of the third and fourth inclined surfaces with respect to the first plane are equal, The radio wave reflector according to claim 8, wherein the inclination angles of the first inclined surface and the third inclined surface with respect to the first plane are equal.

11. The radio wave reflector according to any one of claims 8 to 10, wherein the areas of the first plane, the first inclined surface, the second inclined surface, the third inclined surface, and the fourth inclined surface are equal.

12. In the angular distribution of the reflected wave with respect to the normal passing through the center of the first plane, The first inclined surface is inclined with respect to the first plane such that the angular range in which the intensity of the reflected wave from the first plane is half of its maximum value overlaps with the angular range in which the intensity of the reflected wave from the first inclined surface is half of its maximum value. The second inclined surface is inclined with respect to the first plane such that the angular range in which the intensity of the reflected wave from the first plane is half of its maximum value overlaps with the angular range in which the intensity of the reflected wave from the second inclined surface is half of its maximum value. The third inclined surface is inclined with respect to the first plane such that the angular range in which the intensity of the reflected wave from the first plane is half of its maximum value overlaps with the angular range in which the intensity of the reflected wave from the third inclined surface is half of its maximum value. The radio wave reflector according to claim 11, wherein the fourth inclined surface is inclined with respect to the first plane such that the angular range in which the intensity of the reflected wave from the first plane is half of its maximum value overlaps with the angular range in which the intensity of the reflected wave from the fourth inclined surface is half of its maximum value.

13. The radio wave reflector according to claim 1, wherein the first plane has the shape of a polygon, a circle, or an ellipse, or the outer edge of the first plane has a shape corresponding to at least a part of a polygon, a circle, or an ellipse.

14. The radio wave reflector according to claim 13, wherein the first inclined surface is an inclined surface that surrounds the entire circumference of the outer edge of the first plane.

Images