JP7099861B2 - Radar device - Google Patents

Description

An embodiment of the disclosure relates to a radar device.

Conventionally, there is known a technique of providing an uneven shape in a radar device to suppress radio wave reflection (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2008-249678

However, in the above technique, the height of the convex portion is single, the range of the incident angle that can suppress the radio wave reflection is narrow, and it is difficult to suppress the radio wave reflection in a wide angle range. That is, there is room for improvement in the above technique in terms of improving the transparency of radio waves in a wide angle range.

One aspect of the embodiment is made in view of the above, and an object of the present invention is to provide a radar device that improves the transparency of radio waves in a wide angle range.

The radar device according to one embodiment includes an antenna, a radome, and a plurality of protrusions. The radome is formed to cover the antenna. The plurality of protrusions are provided on at least one of the inside and the outside of the radome, and the height varies depending on the incident angle of the radio wave.

According to one aspect of the embodiment, the transparency of radio waves can be improved in a wide angle range.

FIG. 1 is a cross-sectional view of a radar device according to an embodiment. FIG. 2 is a perspective view showing a part of the radome. FIG. 3 is a diagram showing reflection characteristics in the radome device according to the comparative example. FIG. 4 is a diagram showing reflection characteristics in protrusions having different heights. FIG. 5 is a diagram showing radio wave transmission characteristics in the radar device according to the comparative example and the radar device according to the embodiment.

Hereinafter, the radar device disclosed in the present application will be described with reference to the accompanying drawings. The present invention is not limited to the embodiments shown below.

The radar device is mounted in the front grill of the vehicle, for example, and detects a target (for example, another vehicle (vehicle), a bicycle, a pedestrian (person), etc.) existing in the traveling direction of the own vehicle. The radar device may be mounted on the windshield, the rear grille, the left and right side parts (for example, the left and right door mirrors), the inside of the bumper, and the like, as long as it can detect a target existing around the own vehicle. Further, the radar device may be mounted on an aircraft, a ship, or the like in addition to the vehicle.

The radar device 1 according to the embodiment will be described with reference to FIG. FIG. 1 is a cross-sectional view of the radar device 1 according to the embodiment.

The radar device 1 includes a housing 2, an antenna 3, a radome 4, and a protrusion 5.

A transceiver (not shown) is housed in the housing 2, and is attached to, for example, a vehicle.

The antenna 3 is provided on the surface of the dielectric substrate 6. The antenna 3 includes a transmitting antenna 3a and a receiving antenna. Here, the transmitting antenna 3a will be described as an example of the antenna 3. Further, in FIG. 1, the receiving antenna is omitted for the sake of explanation. A plurality of transmitting antennas 3a and a plurality of receiving antennas may be provided.

The transmitting antenna 3a is formed by extending in one direction. Here, one direction will be described as the Y direction. Further, the plane direction of the dielectric substrate 6 and the direction orthogonal to one direction will be described as the X direction.

The radome 4 is attached to the housing 2 so as to cover the transmitting antenna 3a, and forms a predetermined gap between the radome 4 and the dielectric substrate 6. The predetermined gap is, for example, a gap having a length of 1.5 times the free space wavelength.

The radome 4 includes a flat plate portion 4a facing the transmitting antenna 3a and a frame portion 4b formed so as to surround the peripheral edge of the flat plate portion 4a. The frame portion 4b is attached to the housing 2.

The radome 4 is formed of, for example, a PBT (Polybutylene terephthalate) resin. The thickness of the radome 4 is 1/2 of the wavelength in the tube of the radome material, for example, 1 mm.

A plurality of protrusions 5 are formed on the flat plate portion 4a of the radome 4. The protrusion 5 may be integrally formed with the radome 4.

The protrusions 5 are formed on the inside and outside of the radome 4. Specifically, the protrusions 5 are formed on both sides of the flat plate portion 4a. The protrusion 5 is formed into, for example, a cone or a quadrangular pyramid.

The protrusions 5 are formed side by side in the X direction and the Y direction. That is, a plurality of protrusions 5 having a moth-eye structure are formed on the radome 4. The protrusions 5 are formed so that the distance between the adjacent protrusions 5 is ½ or less of the free space wavelength. For example, the distance between the adjacent protrusions 5 is 1 mm.

The protrusion 5 is composed of a first protrusion 5a and a second protrusion 5b having a height lower than that of the first protrusion 5a. A plurality of first protrusions 5a and second protrusions 5b are formed. The first protrusion 5a and the second protrusion 5b are arranged according to the incident angle.

The incident angle is an angle at which the radio wave emitted from the transmitting antenna 3a is incident on the first protrusion 5a or the second protrusion 5b. The incident angle is an angle with respect to the front surface of the transmitting antenna 3a, and is an angle between the line connecting the apex of the first protrusion 5a or the second protrusion 5b and the transmitting antenna 3a and the reference line. .. The reference line is a line perpendicular to the plane direction of the transmitting antenna 3a and extends in front of the transmitting antenna 3a. The angle of incidence on the reference line is 0 degrees.

When the antenna 3 is a receiving antenna, the incident angle is, for example, the angle at which the radio wave reflected by the target is incident on the receiving antenna from the first protrusion 5a or the second protrusion 5b.

The first protrusion 5a is formed in a front region where the incident angle of the radio wave emitted from the transmitting antenna 3a is equal to or less than a predetermined angle. The second protrusion 5b is formed in a wide-angle region where the incident angle is larger than a predetermined angle.

The predetermined angle is a preset angle, and is an angle capable of suppressing the reflection of radio waves by changing from the first protrusion 5a to the second protrusion 5b.

As shown in FIG. 2, the first protrusion 5a and the second protrusion 5b are formed side by side in the X direction and the Y direction. FIG. 2 is a perspective view showing a part of the radome 4.

As described above, in the radar device 1 according to the embodiment, the first protrusion 5a and the second protrusion 5b having different heights depending on the incident angle are formed on the radome 4.

For example, in the radar device according to the comparative example in which the heights of the protrusions are all the same, the reflection characteristics with respect to the incident angle are as shown in FIG. FIG. 3 is a diagram showing reflection characteristics in the radar device according to the comparative example. Note that FIG. 3 shows that the smaller the reflection characteristic, the more the reflection of the radio wave at the protrusion is suppressed.

In the radar device according to the comparative example, the radome is made of PBT resin, the dielectric constant of the radome is 3.7, and the thickness of the radome is 1 mm. Further, in the radar device according to the comparative example, the shape of the protrusions is a cone, the height of the protrusions is 1.5 mm, and the distance between the adjacent protrusions is 1 mm.

As shown in FIG. 3, in the radar device according to the comparative example, the reflection characteristic of the radome depends on the frequency and the angle of incidence, and the frequency at which the reflection characteristic can be reduced and the angle of incidence are limited.

In the radar device according to the comparative example, when the frequency band used in the radar device is higher than the center of the frequency shown in FIG. 3, the reflection characteristic is small in the range where the incident angle is small, and the radio wave transmission is transmitted. Is excellent. However, in the radar device according to the comparative example, when the incident angle becomes large, the reflection characteristic becomes large and the transparency of the radio wave decreases.

As described above, in the radar device according to the comparative example, the transparency of the radio wave on the wide-angle side where the incident angle is large is lowered, and it is difficult to detect the target in a wide angle range.

Further, in radar devices having different heights of protrusions, as shown in FIG. 4, even if the frequencies are the same, the reflection characteristics change according to the height of the protrusions. That is, the radar device can adjust the reflection characteristics by changing the height of the protrusion. FIG. 4 is a diagram showing reflection characteristics in protrusions having different heights. FIG. 4 shows the reflection characteristics of the protrusions having a height of 1.5 mm and the protrusions having a height of 0.5 mm, and the reflection characteristics when the height of the protrusions is 1.5 mm are shown by solid lines. The reflection characteristics when the height of the protrusion is 0.5 mm are shown by broken lines.

Therefore, in the radar device 1 according to the embodiment, the first protrusions 5a and the second protrusions 5b having different heights are formed on the radome 4 according to the incident angle. Specifically, in the radar device 1, the first protrusion 5a is formed in the front region where the incident angle is small, and the second protrusion 5b is formed in the wide-angle region where the incident angle is large.

In the radar device 1 according to the embodiment, the radome 4 is formed of PBT resin, the dielectric constant of the radome 4 is 3.7, and the thickness of the radome 4 is 1 mm. Then, a first protrusion 5a having a height of 1.5 mm is formed in the front region, and a second protrusion 5b having a height of 0.5 mm is formed in the wide-angle region. Further, the distance between the adjacent protrusions 5 is 1 mm. The configuration of the radar device 1 described above is an example, and is not limited to the above configuration.

Here, FIG. 5 shows the transmission characteristics of radio waves in the radar device according to the comparative example and the radar device 1 according to the embodiment. FIG. 5 is a diagram showing radio wave transmission characteristics in the radar device according to the comparative example and the radar device 1 according to the embodiment. In addition, in FIG. 5, it is shown that the smaller the transmission characteristic is, the larger the reflection of the radio wave in the protrusion is.

In the radar device according to the comparative example, the transmission characteristic of the radio wave becomes smaller and the transmission becomes lower as the angle becomes wider. On the other hand, the radar device 1 according to the embodiment has a larger radio wave transmission characteristic on the wide-angle side than the radar device according to the comparative example.

That is, the radar device 1 according to the embodiment can improve the transparency of radio waves in a wider angle range than the radar device according to the comparative example, and can detect a target in a wide angle range.

The radar device 1 according to the embodiment has protrusions 5 having different heights depending on the angle of incidence. Specifically, the radar device 1 according to the embodiment has the first protrusion 5a in the front region where the incident angle of the radio wave emitted from the transmitting antenna 3a is small, and in the wide angle region where the incident angle is larger than the front region. It has a second protrusion 5b that is taller than the first protrusion 5a.

As a result, the radar device 1 can suppress radio wave reflection in a wide angle range, and can improve the transmission of radio waves in a wide angle range. Therefore, the radar device 1 can detect a target in a wide angle range. In particular, the radar device 1 can improve the transparency of the radio wave emitted from the transmitting antenna 3a on the wide-angle side, and can improve the detection accuracy of the target on the wide-angle side.

In the radar device 1 according to the embodiment, the distance between the adjacent protrusions 5 is set to ½ or less of the free space wavelength. This makes it possible to suppress the reflection of radio waves and improve the transparency of radio waves.

In the radar device 1 according to the above embodiment, the transmitting antenna 3a is taken as an example of the antenna 3, and the height of the protrusion 5 is changed according to the incident angle of the transmitting antenna 3a. You may change the height of.

Further, the radar device 1 according to the above embodiment has a first protrusion 5a and a second protrusion 5b having different heights of the protrusions 5, but the radar device 1 is not limited thereto. For example, the radar device 1 has a third protrusion between the first protrusion 5a and the second protrusion 5b, which is lower in height than the first protrusion 5a and higher than the second protrusion 5b. May have.

Further, the radar device 1 may lower the height of the protrusion 5 toward the wide-angle side. That is, the protrusion 5 is on the wide-angle side, and for example, when the incident angle with respect to the front surface of the antenna 3 becomes large, the height becomes low.

The radar device 1 only needs to be able to improve the transparency of radio waves in a wide angle range, and the height of the protrusion 5 is set according to the frequency band used in the radar device 1, the material of the radome 4, and the like. Therefore, if the height of the protrusion 5 in the front region can be made lower than the height of the protrusion 5 in the wide-angle region to improve the transmission of radio waves in a wide angle range, the protrusion 5 in the front region can be improved. The height may be lower than the height of the protrusion 5 in the wide-angle region. That is, the radar device 1 may have protrusions 5 having different heights depending on the incident angle.

Further, the radar device 1 may have different heights of the protrusion 5 formed inside the radome 4 and the protrusion 5 formed outside the radome 4. For example, the heights of the protrusions 5 at the same positions in the X direction and the Y direction may be different between the front surface and the back surface of the flat plate portion 4a of the radome 4.

Further, the protrusion 5 may be formed only on the inside or the outside of the radome 4. That is, the radar device 1 may have a protrusion 5 on at least one of the inside and the outside of the radome 4.

Further effects and variations can be easily derived by those skilled in the art. For this reason, the broader aspects of the invention are not limited to the particular details and representative embodiments described and described above. Thus, various modifications can be made without departing from the spirit or scope of the overall concept of the invention as defined by the appended claims and their equivalents.

1 Radar device.
2 Housing 3 Antenna 3a Transmitting antenna 4 Radome 5 Protrusion 5a First protrusion 5b Second protrusion

Claims (3)

With the antenna
A radome formed to cover the antenna and
It is provided on at least one of the inside and the outside of the radome, and is provided with a plurality of protrusions having different heights depending on the incident angle of the radio wave .
The plurality of protrusions
As the incident angle with respect to the front of the antenna increases, the height decreases.
A radar device characterized by that . The distance between the adjacent protrusions is
The radar device according to claim 1, wherein the radar device is set to 1/2 or less of the free space wavelength. The antenna is
The radar device according to claim 1 , wherein the radar device is a transmitting antenna.

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