JP2013175800A - Radar reflector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radar reflector that has a generally planar structure and can achieve a high radar cross-sectional area over a wide angle range.SOLUTION: A plurality of radar reflection elements reflecting an electric wave entered from a specific angle region in an incident direction thereof are arranged in a substantially planar shape. The plurality of radar reflection elements differ from each other in center direction of the specific angle region. The radar reflection elements are reflect arrays. The radar reflection elements are obtained by disposing a metal pattern on a transparent film.

Description

  The present invention relates to a radar reflector that reflects radar waves.

  In order to reflect the radar wave radiated from the ship radar, the ship is equipped with a radar reflector. In order to improve the visibility by the marine radar, it is desirable to mount a radar reflector having a large radar cross section indicating the reflection intensity of the radar wave. Various types of radar reflectors have been put into practical use. For example, a corner reflector shown in Non-Patent Document 1 is often used.

  FIG. 6 shows a three-surface corner reflector configured by combining triangular metal plates shown in FIG. 8-30 (b) of Non-Patent Document 1. In the figure, reference numerals 6a, 6b and 6c denote reflectors. The radio wave incident on the radar reflector is reflected by the reflectors 6a, 6b and 6c and reflected in the incident direction, and has a characteristic of having a large radar cross section. This radar reflector is not effective for all incident angles, and the angle range having a large radar cross-sectional area is 40 around the direction of θ = 54.7 degrees and φ = 45 degrees of the polar coordinate system shown in the figure. It is known to be a conical region of degrees (20 degrees on each side with respect to the axis).

G.T.Ruck et al., “Radar Cross Section Handbook, Volume 2”, Plenum Press 1970, p.591

  The radar reflector of the three-surface corner reflector type shown in FIG. 6 has a large radar cross-sectional area, but is limited to the above-mentioned angle range alone. As a method of realizing a scatterer having a high radar cross-sectional area in a wide angle range, a method including a plurality of three-surface corner reflectors whose central axes are directed in a plurality of directions is conceivable. Due to restrictions on the physical size of the surface corner reflector and restrictions on the overall size of the plurality of three-surface corner reflectors oriented in a plurality of directions, it is difficult to reduce the thickness and there is a problem that the installation location is restricted.

  The present invention has been made to solve the above-described problems, and an object thereof is to obtain a radar reflector having a substantially planar structure and capable of realizing a high radar cross section over a wide angular range.

The radar reflector according to the present invention is
There is a radar reflector in which a plurality of radar reflecting elements that reflect radio waves incident from a specific angle region in the incident direction are arranged substantially in a plane,
The center direction of the specific angular region is different from each other in the plurality of radar reflecting elements.

  According to the present invention, there is an effect that a radar reflector having a substantially planar structure and capable of realizing a high radar cross section over a wide angle range can be obtained.

Configuration diagram showing a radar reflector according to a first embodiment of the present invention Configuration diagram showing a radar reflecting element of a radar reflector according to a second embodiment of the present invention Configuration diagram showing a radar reflecting element of a radar reflector according to a second embodiment of the present invention Configuration diagram showing a radar reflecting element of a radar reflector according to a second embodiment of the present invention The figure which shows the example of the reflective element used for the radar reflector by Embodiment 2 of this invention Configuration diagram showing a conventional radar reflector

Embodiment 1 FIG.
1 is a block diagram showing a radar reflector according to Embodiment 1 of the present invention. In the figure, 1a, 1b and 1c are radar reflecting elements, and 2 is a support structure. In FIG. 1, two or more arbitrary numbers of radar reflecting elements 1 a to 1 c are supported by a support structure 2, and have a generally planar structure as a whole.

  The x direction of the orthogonal coordinate system shown in the figure represents the front direction of the planar structure of the radar reflector described above, and indicates one direction of the horizontal plane when the radar reflector is installed vertically. Further, the y direction indicates another direction in the horizontal plane (lateral direction of the radar reflector), and the z direction indicates the vertical direction (vertical direction of the radar reflector). Further, the angle θ in the polar coordinate system represents the deflection angle of the direction vector from the z-axis, and the angle φ represents the deflection angle in the y-axis direction from the x-axis when the direction vector is projected onto the xy plane.

  Here, each of the radar reflecting elements 1a to 1c is a radar reflector having a high radar cross-sectional area in a specific angular region, and considering all the angular ranges of these radar reflecting elements, in a wider angular range, The radar reflector has a high radar cross section.

  For example, a case will be described in which 1a to 1c are three radar reflecting elements and configured on one side (+ x axis side) in a horizontal plane (xy plane) within a limited angular range in a vertical plane.

  The radar reflecting element 1a is a region 1 (60 ° ≦ θ ≦ 120 °, −90 ° ≦ φ ≦ −30 °) centered in the direction 1 (θ = 90 °, φ = −60 °), and the radar reflecting element 1b is In a region 2 (60 ° ≦ θ ≦ 120 °, −30 ° ≦ φ ≦ + 30 °) centering on the direction 2 (θ = 90 °, φ = 0 °), the radar reflecting element 1c is in the direction 3 (θ = 90). In a region 3 (60 ° ≦ θ ≦ 120 °, + 30 ° ≦ φ ≦ + 90 °) centering around °, φ = + 60 °, each is designed to have a high radar cross section. At this time, the radar cross-sectional area of the entire structure including the three radar reflecting elements has an angular range of 60 ° ≦ θ ≦ 120 °, −90 ° ≦ φ ≦ + 90 °), that is, in a horizontal plane (xy plane). A high radar cross-sectional area can be realized in a region on one side (+ x axis side).

  Here, an example in which three radar reflecting elements 1a to 1c are configured has been shown, but it is obvious that the radar reflecting elements can be configured by an arbitrary number of two or more radar reflecting elements.

  In FIG. 1, the radar reflection elements 1a to 1c are arranged on a straight line, but may be arranged in a two-dimensional manner with a substantially planar structure.

  In the above embodiment, the radar reflector effective on one side (+ x axis side) in the horizontal plane is shown in a limited angular range in the vertical plane. That is, in each of the radar reflecting elements 1a to 1c, the center of the direction indicating the effective high radar cross-sectional area, the directions 1 to 3 are all set in the horizontal plane (xy plane) (θ = 90 °).

  Since radio waves incident on the radar reflector often arrive from the vicinity in the horizontal plane, an efficient radar reflector can be obtained by setting the center direction of the direction showing a high radar cross section in the horizontal plane. In this case, the same effect can be obtained even when the direction is within approximately ± 20 degrees from the horizontal plane (70 ° ≦ θ ≦ 110 °).

  However, the present invention is not limited to this, and a radar reflector that is effective at an arbitrary angle in the vertical plane can be used. In this case, at least a part of the center of the direction showing the high radar cross-sectional area, direction 1 to direction 3 is not limited to the xy plane, and may be other than θ = 90 °, and other than 70 ° ≦ θ ≦ 110 °. It may be set in the direction.

  In the above embodiment, a planar radar reflector in which the support structure 2 is a planar structure has been shown. However, the present invention is not limited to this, and if it is substantially planar, it has a smooth curved surface or a slight inclination. Various shapes such as a combination of a plurality of planes may be used.

  According to the present embodiment, a radar reflector having a high radar cross-sectional area can be realized with a substantially planar structure in a wide angle range, so that the radar reflector can be installed in various places. effective.

Embodiment 2. FIG.
In the second embodiment, a specific configuration method of each radar reflecting element in the radar reflector shown in FIG. 1 will be described. FIG. 2 is a configuration example of the radar reflecting element shown in 1a of FIG. In FIG. 2, 3a to 3e are circular microstrip patches, 4 is a dielectric substrate, and 5 is a metal base plate. Here, the same microstrips 3a to 3e are arranged side by side in the vertical direction.

  The structure shown in FIG. 2 is known as a reflect array, and can be reflected in an arbitrary direction by changing the size and interval of the circular microstrip and controlling the reflection amplitude and phase of each element. For example, the parabolic surface of the reflector antenna can be replaced with a planar structure reflectarray.

  In the reflect array of FIG. 2, the size and interval of the microstrip patches are determined so as to reflect in the incident direction and have a high radar cross-sectional area, so that the reflector array can be operated.

  As shown in the example of the first embodiment, a case will be described in which 1a to 1c are three radar reflecting elements and configured on one side (+ x axis side) in the horizontal plane (xy plane).

  FIG. 2 corresponds to the radar reflecting element 1a, and region 1 (60 ° ≦ θ ≦ 120 °, −90 ° ≦ φ ≦ −30 °) centering on direction 1 (θ = 90 °, φ = −60 °). 3 corresponds to the radar reflecting element 1b, and region 2 (60 ° ≦ θ ≦ 120 °, −30 ° ≦ φ ≦ + 30 °) centering on direction 2 (θ = 90 °, φ = 0 °). 4 corresponds to the radar reflecting element 1c and has a region 3 (60 ° ≦ θ ≦ 120 °, + 30 ° ≦ φ ≦ + 90 °) centered on the direction 3 (θ = 90 °, φ = + 60 °). ), Each is designed to have a high radar cross section.

  At this time, the radar cross-sectional area of the entire structure including the three radar reflecting elements has an angular range of 60 ° ≦ θ ≦ 120 °, −90 ° ≦ φ ≦ + 90 °), that is, in a horizontal plane (xy plane). A high radar cross-sectional area can be realized in a region on one side (+ x axis side).

  In the reflect array, there is no precedent example used as a radar reflector, and a structure used as a radar reflecting element that reflects in a plurality of directions is not known.

  In the above, attention is paid to the pattern of the radar cross section in the horizontal plane. In FIG. 2, the microstrips in the vertical direction have the same shape. However, when the radar reflection element including the radar cross section pattern in the vertical plane is used. For this, microstrips with different sizes and intervals in the vertical direction can be used.

  FIG. 2 shows an example of a circular microstrip, but the present invention does not depend on the shape or the like of the reflecting element, and a radar reflecting element using any reflecting element is possible. For example, in addition to the circular microstrip patches shown in 3a to 3e, various shapes of reflective elements as shown in FIGS. 5 (a) to 5 (g) can be used.

  5, (a) is a rectangular patch, (b) is a dipole, (c) is a circular patch similar to FIG. 2, (d) is a cross dipole, (e) is a Jerusalem cross, (f) is a rectangular loop, (G) is a circular loop. Furthermore, shapes other than these and combinations of various shapes can be used, and the effects of the present invention can be obtained.

  Furthermore, in FIGS. 2 to 4, the reflect array using the metal ground plane 5 is shown for the radar reflecting elements 1 a to 1 c, but the ground plane 5 is not necessarily required, and a radar reflecting element without the ground plane 5 may be used. .

  Moreover, it can be affixed on substantially transparent members, such as a glass surface of a substantially planar structure, by using what arranged and printed the metal pattern used as a reflective element on a substantially transparent film. In this case, since the space between the reflecting elements is almost transparent and the field of view is secured, the radar reflector can be installed at a place where the field of view is required to be secured.

1a, 1b, 1c Radar reflector, 2 Support structure, 3a, 3b, 3c, 3d, 3e Circular microstrip, 4 Dielectric substrate, 5 Ground plane, 6a, 6b, 6c Reflector

Claims (5)

There is a radar reflector in which a plurality of radar reflecting elements that reflect radio waves incident from a specific angle region in the incident direction are arranged substantially in a plane,
2. A radar reflector according to claim 1, wherein a central direction of the specific angle region is different from each other in the plurality of radar reflecting elements.   The radar reflector according to claim 1, wherein the radar reflecting element is a reflect array.   3. The radar reflector according to claim 1, wherein the radar reflecting element is formed by arranging a metal pattern on a transparent film.   The radar reflector according to any one of claims 1 to 3, wherein a center direction of the specific angle region in the radar reflection element is a horizontal plane vicinity direction.   The radar reflector according to any one of claims 1 to 4, wherein a center direction of the specific angle region in the radar reflecting element is a direction other than a vicinity of a horizontal plane.

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