JP2015190810A - Radar device and radar method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radar device capable of improving efficiency.SOLUTION: A radar device comprises: an antenna unit including a lens antenna or a reflector antenna or an array antenna; and a cover for covering a portion or a whole of the antenna unit. The antenna unit and the cover are configured so as to suppress reflection in the cover of beams transmitted from the antenna.

Description

  The present invention relates to a radar apparatus and a radar method.

  In recent years, with the diversification of safety device functions of automobiles, sensor devices with various specifications are required to achieve many applications. In the forward direction monitoring sensor, a reduction in cost and a space saving are simultaneously demanded while an extension of the detection distance and a wide angle of field of view are required as compared with the conventional apparatus.

  Here, “extension of detection distance” and “widening of the visual field range” have a contradictory relationship regardless of the type of sensor device. For example, multiple sensor devices are installed according to the monitoring area. It is possible to do. However, such a system cannot realize cost reduction and space saving. Therefore, Patent Document 1 proposes a sensor device in which a plurality of sensors suitable for each region are modularized (see Patent Document 1). In this technique, in order to detect an object at a long distance, a radio wave type radar excellent in long-distance propagation and weather resistance and an ultrasonic sensor capable of covering a wide range at a relatively low cost are applied.

  On the other hand, Patent Document 2 proposes to unify two sensors by the same radio wave radar system (see Patent Document 2). In this technique, one common fixture is formed by integrating antennas suitable for two areas.

  By the way, as recent sensor mounting conditions, modularization into a vehicle interior or a side mirror has been promoted from the viewpoint of freedom of installation, design (designability), and sharing with camera sensor devices. Patent Document 3 proposes a method of installing a combined device of a radio wave radar and a camera sensor on an upper part of a windshield in a vehicle interior (see Patent Document 3). Patent Document 4 proposes a method of installing a device on a side mirror. Thus, the diversification of the installation place of an apparatus is progressing (refer patent document 4).

[About miniaturization and cost reduction of composite sensor device that can cover multiple detection areas]
There are several problems with composite sensor devices that can cover multiple detection (sensing) areas.
For example, in an example of the prior art (referred to as the first prior art), a plurality of sensors (radio wave radars) having different specifications are mounted. There is no degree and lacks in design. In addition, since a plurality of sensor units are required and the number of installation steps increases, the overall cost is unavoidable.
On the other hand, in another example of the conventional technique (referred to as the second conventional technique), a plurality of sensor devices having different detection areas are modularized. Unlike the first conventional technique, the sensor apparatus is configured by one sensor unit. Therefore, it is good in terms of space saving. However, the detection method according to this technique uses two types of radio wave radar and ultrasonic sensor, and the component configuration is completely different. Furthermore, since the parts used cannot be shared, the cost merit associated with modularization cannot be expected so much.

[Composite sensor performance and space saving]
In the second conventional technique, the two methods are modularized, and space is saved compared to the first conventional technique. However, since a relatively inexpensive ultrasonic sensor is used in the middle / short-distance region, it is not possible to ensure performance higher than that of the radio wave radar. Specifically, sound waves propagating in the air are significantly attenuated compared to radio waves, and are greatly affected by climatic conditions. In addition, in the case of an ultrasonic sensor, resolution higher than that of a general millimeter wave radio wave radar cannot be obtained in view of the element size and wavelength. Since sound waves have a slower propagation speed than radio waves, it can be said that these conditions are not suitable for medium and short-range sensors that require high-speed response in recent years.

  In another example of the prior art (referred to as “third prior art”), a method using a sensor for a plurality of regions, both of which are configured by radio wave radar, can share a printed circuit board array antenna as an antenna (antenna element). This saves more space than the first prior art. Further, in the third conventional technique, the problem described with respect to the second conventional technique can be solved for the middle and short distances. However, in the patch array antenna, since the radiation efficiency is remarkably lowered as compared with the first conventional technique, the system gain in the same aperture area is extremely low. Therefore, the third prior art is not suitable for long-distance stable detection. In order to increase the antenna gain, it is necessary to increase the aperture of the antenna, but it is easy to increase the gain of the antenna by sharpening the beam that does not meet the specifications, narrowing the field of view, generating an antenna grating lobe, etc. I can't. Further, in the third prior art, structural complexity is also a problem, such as a common substrate, but different substrate specifications for each antenna.

[Installation and degree of freedom of compound sensor device]
For example, when a sensor device is installed in a vehicle interior, a side mirror, or the like, the area in the direction in which the sensor is installed is greatly limited from the viewpoints of visibility (considering laws and regulations) and design. On the contrary, there is a tendency that a relatively margin is generated in the depth dimension. From this condition, it can be said that it is physically difficult to apply the first conventional technique to the passenger compartment or the like.
Note that when a radiating element is installed in a vehicle interior or side mirror, a dielectric cover (such as a windshield or resin cover) is always present in front of the radiating element. Considering this, in order to apply the third prior art, it is necessary to further increase the size of the antenna aperture, so it can be said that application under this condition is difficult. Similarly, in the ultrasonic sensor, since the sound wave is significantly attenuated by the dielectric cover, further reduction in resolution and sensitivity is inevitable.

  Therefore, as a method for suppressing attenuation by the dielectric cover, Patent Document 3 proposes reduction of attenuation by a reflection matching refractive block or a conductive plate, but these are in the vicinity of the radiating element. Since the occupying volume of the radiating element is reduced, the maximum antenna aperture cannot be secured, resulting in a decrease in gain. Similarly, in Patent Document 4, it is difficult to cover a region far from the side mirror in a radar device to which a planar antenna using a high-frequency substrate is applied, and furthermore, it is possible to control the reflection loss due to the resin cover of the side mirror. Can not.

International Publication No. 2006-034893 JP 2013-088364 A Special table 2012-505115 gazette JP 2013-160607 A

  Conventional radar devices have been required to be highly efficient. In particular, the efficiency may be reduced due to reflection of a beam (radio wave signal) communicated by the radar device when it passes through a windshield of a vehicle.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a radar apparatus and a radar method capable of improving efficiency.

  (1) In order to solve the above-described problem, a radar apparatus according to an aspect of the present invention includes an antenna unit including a lens antenna, a reflector antenna, or an array antenna, and a cover that covers part or all of the antenna unit. The antenna unit and the cover are configured such that reflection of the beam communicated by the antenna unit on the cover is suppressed.

  (2) One aspect of the present invention is the radar apparatus according to (1) described above, wherein the antenna unit includes the lens antenna or the reflector antenna, and the lens antenna or the reflector antenna is a lens or It may be configured to have multi-beam characteristics by designing the shape of the reflecting mirror, or by scanning in the electronic or mechanical radial direction.

  (3) One aspect of the present invention is the radar apparatus according to (1) described above, wherein the antenna unit includes a plurality of the array antennas, and the plurality of the array antennas are offset. Also good.

  (4) One aspect of the present invention is the radar device according to (1) described above, wherein the antenna unit includes a plurality of the array antennas, and the plurality of the array antennas include a phase shifter, different wiring lengths, Alternatively, the beam may be controlled by one or more of the receivers.

  (5) According to one aspect of the present invention, in the radar device according to any one of (1) to (4), reflection of the beam communicated by the antenna unit on the cover is suppressed. As a configuration, a configuration may be used in which the directivity of the beam in a predetermined direction with respect to the surface facing the cover is an angle at which reflection at the cover is suppressed.

  (6) According to one aspect of the present invention, in the radar device according to any one of (1) to (5) described above, a configuration in which total transmission is realized as a configuration in which the reflection is suppressed. It is good also as the structure used.

  (7) One aspect of the present invention may be configured such that, in the radar device according to any one of (1) to (6), the cover is a dielectric cover.

  (8) According to one aspect of the present invention, in the radar device according to any one of (1) to (7), the cover is a dielectric component in a vehicle provided with the radar device. It is good also as a structure comprised from a part or all.

  (9) According to one aspect of the present invention, in the radar device according to any one of (1) to (8) described above, the radar apparatus further includes a dielectric component that adjusts the angle of the beam. Also good.

  (10) One aspect of the present invention may be configured such that in the radar device according to (9) described above, the dielectric component has a film shape or a block shape.

  (11) One aspect of the present invention is the radar device according to any one of (9) and (10), wherein the dielectric component is configured such that one surface of the dielectric component is the cover. It is good also as a structure provided in contact with one side of these.

  (12) According to one aspect of the present invention, in the radar device according to any one of (9) to (11), the cover has a flat plate shape, and the dielectric component is The surface on the cover side may be parallel to the surface of the cover, and the surface opposite to the cover side may be parallel or non-parallel to the surface of the cover.

  (13) In order to solve the above-described problem, a radar method according to an aspect of the present invention includes an antenna unit including a lens antenna, a reflector antenna, or an array antenna, and a cover that covers part or all of the antenna unit. The beam is communicated by the antenna unit of the radar apparatus in which the antenna unit and the cover are configured so that reflection of the beam communicated by the antenna unit on the cover is suppressed.

  According to the present invention, efficiency can be improved in the radar apparatus and the radar method.

1 is a diagram illustrating a schematic configuration of a vehicle according to an embodiment of the present invention. It is a figure which shows an example of the relationship between the incident angle and reflection angle of a beam with respect to a glass surface, and a reflection coefficient. It is a figure which shows schematic structure of the antenna of the radar apparatus which concerns on one Embodiment of this invention. It is a figure which shows an example of the directivity characteristic of the multi-beam in the lens antenna which concerns on one Embodiment of this invention. It is a figure which shows schematic structure of the antenna which concerns on the other structural example of the radar apparatus which concerns on one Embodiment of this invention. (A) And (B) is a figure which shows the example of the structure which adjusts the phase of a signal. It is a figure which shows schematic structure of the antenna which concerns on the other structural example of the radar apparatus which concerns on one Embodiment of this invention. (A) is a figure which shows an example of the patch array antenna for transmission, (B) is a figure which shows an example of the surface patch array antenna for reception. It is a figure which shows schematic structure of an antenna part and a DBF part. It is a figure which shows an example of the schematic structure of the dielectric component which adjusts the direction of a beam. (A) And (B) is a figure which shows the schematic structure of the dielectric component which concerns on the other structural example.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Outline of vehicle equipped with radar device according to this embodiment]
FIG. 1 is a diagram showing a schematic configuration of a vehicle 1 according to an embodiment of the present invention.
A vehicle 1 according to this embodiment is an automobile and includes a windshield 11 and side mirrors 12 and 13. In the present embodiment, the windshield 11 of the vehicle 1 includes the radar device 21 according to the present embodiment.
In the present embodiment, the radar device 21 is provided in the central portion (or substantially central portion) in the left-right direction of the windshield 11 and in the central portion or the upper portion in the vertical direction. In the present embodiment, the radar device 21 is provided on the side of the vehicle interior of the windshield 11.
The radar device 21 may be provided at various positions on the windshield 11. Further, the radar device 21 may be provided in a place other than the windshield 11 in the vehicle 1.
The radar apparatus 21 according to the present embodiment is for in-vehicle use and has a radio wave radar function.

[About reflection on the glass surface]
FIG. 2 is a diagram showing an example of the relationship between the incidence angle and reflection angle of a beam with respect to the glass surface and the reflection coefficient. In this example, the glass surface is the surface of the windshield 11. This glass has a dielectric material, and the relative dielectric constant in the vicinity of this glass is 8.
In the graph shown in FIG. 2, the horizontal axis represents the incident angle and the reflection angle [deg] with respect to the glass surface, and the vertical axis represents the reflection coefficient (absolute value). A TM incident characteristic 1001 and a TE incident characteristic 1002 are shown. In the TM incident characteristic 1001, there is a total transmission angle 1011 (an angle in the vicinity of 70 deg in the example of the graph of FIG. 2) at which the reflection coefficient is zero (0).

Here, in TM incidence, the electric field direction of the beam is perpendicular to the glass surface. The reflection coefficient R _TM at the time of TM incidence is expressed by equation (1).
In TE incidence, the electric field direction of the beam is horizontal with respect to the glass surface. The reflection coefficient R _TE at the time of TE incidence is expressed by equation (2).

In the equations (1) and (2), when the beam passes through the medium 1 and is reflected by the medium 2 (the boundary between the medium 1 and the medium 2), μ ₁ represents the magnetic permeability of the medium 1, and μ ₂ is Represents the magnetic permeability of the medium 2, n represents the relative complex refractive index of the medium 2 with respect to the medium 1, θ _i represents the incident angle of the beam, E _i represents the electric field of the incident wave, and _Er represents the electric field of the reflected wave. Represents.

  As shown in FIG. 2, in the TM incident characteristic 1001, there are an incident angle and a reflection angle (total transmission angle 1011) through which all power is transmitted without any reflection of the beam on the glass surface. Therefore, in this embodiment, the antenna is configured so that the antenna beam (plane wave) is incident on the total transmission angle 1011.

[Outline of Antenna of Radar Device According to this Embodiment]
FIG. 3 is a diagram showing a schematic configuration of the antenna of the radar apparatus 21 according to the embodiment of the present invention. FIG. 3 schematically shows a state in which the windshield 11 and its periphery are viewed from the lateral direction of the vehicle 1.
In the example of FIG. 3, the radar apparatus 21 includes a multi-beam lens antenna. This lens antenna includes a primary radiator 101 and a lens 102. As the primary radiator 101, for example, a patch antenna is used. A multifocal lens is used as the lens 102.
Here, this lens antenna is separately provided with a plurality of primary radiators that radiate each of a plurality of beams (multi-beams). In the example of FIG. 3, only one primary radiator 101 is provided for convenience of explanation. Is illustrated. The same applies to the other primary radiators.

FIG. 3 shows the central axis 121 of the lens 102. In the example of FIG. 3, the surface of the windshield 11 and the central axis 121 of the lens 102 are not orthogonal to each other, and the multi-beam incident angle is adjusted.
Specifically, the shape of the lens 102 and the primary radiator are formed so that a beam (light ray) emitted from the primary radiator 101 forms a plane wave ray 131 that travels in a predetermined direction after passing through the lens 102. The position 101 and the position of the lens 102 are designed. The arrangement of the lens antenna (the primary radiator 101 and the lens 102) with respect to the windshield 11 is designed so that the plane wave ray 131 forms the plane wave ray 132 after passing through the windshield 11. In this case, the angle at which the plane wave ray 131 is incident on the windshield 11 is designed to be a total transmission angle (or an angle close thereto). As a result, the plane wave ray 131 is totally transmitted through the windshield 11 (or transmitted close thereto), and the resulting plane wave ray 132 propagates.
In the present embodiment, the windshield 11 has a flat plate shape (or a shape close thereto).

  As described above, the lens antenna according to the example of FIG. 3 can radiate a plane wave beam in the desired direction (radiation direction) during transmission. Further, by using a similar configuration, it is possible to receive a plane wave beam (light beam) in the desired direction (arrival direction) in reception.

  In the example of FIG. 3, the Brewster angle of the glass (front glass 11) is φ. The sweep angle from the glass surface is radiated at the same angle as the incident angle when the glass is a normal single glass. On the other hand, in the example of FIG. 3, since the in-vehicle glass is a laminated glass, the angle φ at the time of incidence and the angle θ at the time of radiation are slightly different. In the example of FIG. 3, the incident angle of the beam is determined or adjusted in consideration of such a laminated glass.

FIG. 4 is a diagram showing an example of the multi-beam directivity characteristic 1101 in the lens antenna according to the embodiment of the present invention.
In the graph shown in FIG. 4, the horizontal axis represents the radiation angle [deg], and the vertical axis represents the gain (Gain) [dB]. The radiation angle is an angle in which the angle in the direction of the central axis 121 of the lens 102 is zero (0).
In the example of FIG. 4, the beam can be directed in the direction of an angle of 10.5 [deg], that is, the plane wave is radiated (swept) in the direction of this angle.

Thus, by adjusting the angle between the direction of the beam radiated from the antenna of the radar device 21 (the lens antenna in the example of FIG. 3) and the surface of the windshield 11, the beam passes through the windshield 11. The reflection loss at the time can be reduced, and the efficiency can be improved. For example, it is possible to adjust the angle so that the power of the beam becomes maximum, or to adjust the angle so that the power of the beam exceeds a predetermined threshold.
The degree of reducing the reflection loss is preferably, for example, total transmission or a degree close to total transmission. However, as another configuration example, it is possible to reduce the reflection loss to another degree. .

Here, the radar apparatus 21 may include, for example, a lens and antenna cover in which the lens 102 of the lens antenna and the redm (cover) of the radar apparatus 21 are integrated.
As an example, the lens / antenna cover has a lens 102 and a cover unit integrated with each other, and is a redm (cover) that covers the entire transmission / reception circuit unit of the radar device 21. The lens 102 and the cover portion are each configured using a dielectric material (for example, resin). The lens 102 and the cover portion may be configured using the same material, or may be configured using different materials.

  In the present embodiment, the windshield 11 can also be regarded as a kind of cover of the radar device 21. In this case, for example, the radar device 21 may be partially covered by the windshield 11, or the radar device 21 may be covered by the windshield 11 (and other parts if necessary). All may be covered. Further, the windshield 11 may be configured to be integrated with a part or all of the lens and the cover in the lens / antenna cover of the radar device 21.

In addition, regarding the lens antenna, as another configuration example, instead of a configuration including a plurality of primary radiators, a plurality of primary radiators can be changed by changing the position and angle of one primary radiator in a time-sharing manner. It is also possible to emit a beam similar to that provided.
As another configuration example, a reflector antenna (for example, a parabolic antenna) including a primary radiator and a reflector may be used instead of the lens antenna.

[Outline of antenna according to another configuration example]
FIG. 5 is a diagram illustrating a schematic configuration of an antenna according to another configuration example of the radar apparatus 21 according to an embodiment of the present invention.
In the example of FIG. 5, a plurality of (four in the example of FIG. 5) array antennas 201-1 to 201-4 and a receiving unit 202 are provided on the substrate (for example, a printed circuit board) of the radar device 21. The plurality of array antennas 201-1 to 201-4 constitutes a single (one) antenna group (here, a reception antenna group).

The array antenna 201-1 is configured by connecting a plurality of antennas (only one antenna 221 is labeled) in a column, and is a printed array antenna.
The array antenna 201-2 is a printed array antenna that is configured by connecting a plurality of antennas (only one antenna 222 has a reference numeral) in a column.
The array antenna 201-3 is configured by connecting a plurality of antennas (only one antenna 223 has a reference numeral) in a column, and is a printed array antenna.
The array antenna 201-4 is configured by connecting a plurality of antennas (only one antenna 224 has a reference numeral) in a column, and is a printed array antenna.

Each of the array antennas 201-1 to 201-4 and the receiving unit 202 are connected via a microstrip line (MSL).
The receiving unit 202 can receive signals of four channels (for example, reception 1ch to reception 4ch) using the four array antennas 201-1 to 201-4.
As the receiving unit 202, a component of an MMIC (Monolithic Microwave Integrated Circuit) element is used.
Note that patch antennas are used as the antennas (antennas 221 to 224 and the like) of all the array antennas 201-1 to 201-4.

Here, in the example of FIG. 5, the antenna portions of the four array antennas 201-1 to 201-4 arranged at a predetermined interval (for example, equal intervals) are arranged in a direction perpendicular to the arrangement direction ( These four array antennas 201-1 to 201-4 are arranged shifted (offset) by a predetermined distance dv (dv is a value greater than 0) in the (EL direction). Further, the angle direction formed by the four array antennas 201-1 to 201-4 formed by such an offset arrangement (here, the antennas 221 to 224 at the tips of the array antennas 201-1 to 201-4 are connected). The directivity of all the antennas of the array antennas 201-1 to 201-4 is directed in a direction perpendicular to the direction of the straight line. With such a configuration, in the antenna group including the four array antennas 201-1 to 201-4, the beam can be transmitted in a desired direction (here, an angle direction in which the directivity of all the antennas described above is directed). The plane phase is aligned.
For example, it is possible to adjust the angle so that the power of the beam becomes maximum, or to adjust the angle so that the power of the beam exceeds a predetermined threshold.

As described above, in the array antennas 201-1 to 201-4 according to the example of FIG. 5, similarly to the lens antenna according to the example of FIG. 3, in the transmission, a plane wave beam (light ray) in a desired direction (radiation direction). ) Can be emitted. Further, by using a similar configuration, it is possible to receive a plane wave beam (light beam) in the desired direction (arrival direction) in reception.
In this way, the beam can be tilted using the array antennas 201-1 to 201-4.

  In the antenna group according to the example of FIG. 5, in response to the four array antennas 201-1 to 201-4 being offset, the signals passing through the array antennas 201-1 to 201-4 are offset. In order to align the phases, the length (wiring length) of the microstrip line connecting each of the array antennas 201-1 to 201-4 and the receiving unit 202 is adjusted. In the example of FIG. 5, the lengths of the microstrip lines between the antenna portions (portions where a plurality of antennas are arranged) of the array antennas 201-1 to 201-4 and the receiving unit 202 are adjusted to different lengths. Has been.

FIGS. 6A and 6B are diagrams illustrating an example of a configuration for adjusting the phase of a signal.
FIG. 6A illustrates a plurality (n) of radiating elements (antennas) 301-1 to 301-n and wirings 321-1 to 321- (n-1) between two adjacent radiating elements. An example of a configuration for connection is shown by connecting. In this example, by adjusting the length of the wirings 321-1 to 321- (n-1), the phase of the signal (beam) in the array antenna having the plurality of radiating elements 301-1 to 301-n is adjusted. be able to.

FIG. 6B illustrates a plurality (n) of radiating elements (antennas) 401-1 to 401-n and wirings 421-1 to 421- (n-1) between two adjacent radiating elements. An example of a configuration in which the phase shifters 441-1 to 441-n are connected to each other and connected to the wirings 421-1 to 421- (n-1) is shown. In this example, the lengths of the wirings 421-1 to 421- (n-1) are adjusted, and signals that pass through the phase shifters 441-1 to 441-n by the phase shifters 441-1 to 441-n. By adjusting the phase, the phase of the signal (beam) in the array antenna having the plurality of radiating elements 401-1 to 401-n can be adjusted. As another configuration example, a phase shifter may be provided in only a part of the plurality of wirings.
In this way, in the array antenna, the phase of the beam (signal) is adjusted by connecting one or more electronic elements (for example, wiring, phase shifter, etc.) capable of array operation in the vertical direction (longitudinal direction). Is possible.

As another configuration example, a plurality of array antennas are arranged without an offset arrangement as shown in the example of FIG. 5 without an offset. For example, a plurality of array antennas are arranged in the vertical direction (vertical direction). A configuration in which digital beam forming (DBF: Digital Beam Forming) processing (for example, software processing in the reception unit) is performed in the horizontal direction (lateral direction) may be used.
In the example of FIG. 5, array antennas 201-1 to 201-4 having an element arrangement in a single direction in the vertical direction are used, but for example, a horizontal array antenna may be used.

FIG. 7 is a diagram illustrating a schematic configuration of an antenna according to another configuration example of the radar apparatus 21 according to an embodiment of the present invention. FIG. 7 schematically shows a state in which the windshield 511 and its periphery are viewed from the lateral direction of the vehicle.
FIG. 7 shows the XYZ axes that are a three-dimensional orthogonal coordinate system for convenience of explanation.
In the example of FIG. 7, the radar device 21 includes a reception surface patch array antenna 501 on the inner side of the vehicle with respect to the windshield 511.
In the example of FIG. 7, an incoming wave 522 is incident on the windshield 511 from the outside of the vehicle, passes through the glass surface, and is incident on a receiving surface patch array antenna 501 provided inside the vehicle.
The surface patch array antenna 501 is installed so that the angle (antenna angle) of the surface patch array antenna 501 and the angle (arrival angle) of the incoming wave 522 are good (preferably optimal). As a specific example, the angle (relative angle) between the surface patch array antenna 501 and the incoming wave 522 is adjusted according to the angle of the glass surface of the windshield 511, and the surface patch array antenna 501 is installed.
In the example of FIG. 7, the windshield 511 has a flat plate shape (or a shape close to it).

FIG. 8A shows an example of a patch array antenna 501T for transmission.
In the example of FIG. 8A, the transmission patch array antenna 501T includes a plate-like substrate having a square (eg, rectangular or square) surface, and a total of 5 (= 5 × 1) pieces on the surface. Equipped with a radiator. Specifically, the patch array antenna 501T for transmission includes a total of five patch antennas (5 in the vertical direction (or horizontal direction as another example) with respect to one side on the surface. Only one patch antenna 601 among the patch antennas is provided with a reference numeral). Each patch antenna 601 includes one radiator at the center of a square surface.
FIG. 8A shows XYZ axes corresponding to those shown in FIG. 7 for convenience of explanation.
As an example of the configuration, a patch array antenna 501T for transmission shown in FIG. 8A is installed instead of the surface patch array antenna 501 shown in FIG. In this case, instead of the incoming wave 522 shown in FIG. 7, an output wave radiated from the patch array antenna 501T for transmission and output through the windshield 511 is assumed.
In such a transmission configuration, the transmission patch array antenna 501T is installed so that the angle of the output wave is good (preferably optimum). As a specific example, the patch array antenna 501T for transmission is installed by adjusting the angle (relative angle) of the patch array antenna 501T for transmission according to the angle of the glass surface of the windshield 511.
In this manner, in the example of FIG. 8A, the beam can be tilted in a direction perpendicular to the glass surface of the windshield 511 by scanning the antennas for transmission in an array.

FIG. 8B is a diagram illustrating an example of a surface patch array antenna 501R for reception.
In the example of FIG. 8B, the receiving surface patch array antenna 501R includes a plate-like substrate having a square surface, and includes a total of 25 (= 5 × 5) radiators on the square surface. . Specifically, the receiving surface patch array antenna 501R includes a total of 25 square patch antennas (25 in a vertical direction and a horizontal direction with respect to one side in the square surface). Of the patch antennas, only one patch antenna 602 is provided with a reference numeral). Each patch antenna 602 includes one radiator at the center of a square surface.
FIG. 8B shows XYZ axes corresponding to those shown in FIG. 7 for convenience of explanation.
As an example of the configuration, a reception surface patch array antenna 501R shown in FIG. 8B is installed as the surface patch array antenna 501 shown in FIG.

  Note that a surface patch array antenna may be used as the transmitting antenna. In this case, from two or more radiators (for example, an array antenna composed of two or more radiators arranged linearly in a vertical direction or a horizontal direction) among a plurality of radiators included in the surface patch array antenna. Radiates radio waves.

FIG. 9 is a diagram illustrating a schematic configuration of the antenna unit 701 and the DBF unit 702.
As an example, an antenna unit 701 having an array antenna (for example, a surface patch array antenna) on a substrate (for example, a printed circuit board) of the radar device 21 and a functional unit included in a DBF unit 702 (for example, a transmission unit or a reception unit). ). The array antenna constitutes a single (one) antenna group (here, a transmission antenna group or a reception antenna group).

The antenna unit 701 (array antenna) and the DBF unit 702 are connected via a microstrip line (MSL).
The DBF unit 702 can execute digital beam forming (DBF) processing on a signal (a signal to be transmitted or a signal to be received) communicated by the antenna unit 701 (array antenna).
A component of an MMIC element is used as the DBF unit 702 (for example, a transmission unit or a reception unit including the DBF unit 702).

  By performing digital beam forming by the DBF unit 702, the directivity can be adjusted to a beam having a plane phase aligned in a desired direction. For example, adjusting the desired direction (angle) so that the power of the beam is maximized, or adjusting the desired direction (angle) so that the power of the beam exceeds a predetermined threshold. Is possible.

Thus, in the array antenna according to the example of FIG. 7 as well, for example, similarly to the lens antenna according to the example of FIG. 3, a plane wave beam (light ray) is radiated in a desired direction (radiation direction) in transmission. Can do. Further, by using a similar configuration, it is possible to receive a plane wave beam (light beam) in the desired direction (arrival direction) in reception.
In this way, the beam can be tilted using the array antenna and the DBF unit 702.

In the example of FIG. 7, the surface (glass surface) of the windshield 511 and the directivity formed by the surface patch array antenna 501 are not orthogonal to each other, and the beam incident angle is adjusted. ing.
Specifically, with regard to reception, the directivity formed by the DBF by the DBF unit 702 is that when a plane wave ray (arrival wave 522) passes through the windshield 511 from the outside of the vehicle and enters the inside of the vehicle. The directivity of the DBF with respect to the windshield 511 is designed so as to match the directivity. In this case, the angle at which the light beam (arrival wave 522) from the outside of the vehicle enters the windshield 511 is designed to be a total transmission angle (or an angle close thereto). Thereby, the light rays (arrival wave 522) from the outside of the vehicle are totally transmitted through the windshield 511 (or transmitted close thereto).

  Similarly, with regard to transmission, the directivity of the DBF with respect to the windshield 511 (so that the light emitted from the antenna becomes a plane wave ray when passing through the windshield 511 from the inside of the vehicle and exiting the vehicle) The directivity formed by the DBF by the DBF unit 702 is designed. In this case, the angle at which the light beam from the inside of the vehicle enters the windshield 511 is designed to be the total transmission angle (or an angle close thereto). Thereby, the light rays from the inside of the vehicle are totally transmitted through the windshield 511 (or transmitted close thereto).

[Adjustment of beam direction by dielectric parts]
In the present embodiment, for example, by applying a multi-beam function, it is realized that the plane wave in the directional direction is adjusted to be incident on the windshield near the Brewster angle. However, since the Brewster angle of the windshield is uniquely determined by the dielectric constant of the glass and the direction of the incident electric field, in reality, depending on the circumstances of the design, the desired angle (incident angle and radiation angle) Misalignment may occur.
Normally, the beam width in the vertical direction is given a margin and the amount of deviation is absorbed, but further adjustment may be necessary. As a specific example, when the Brewster angle is adjusted inside the vehicle (inside the vehicle interior) in the method described in Patent Document 3 or the proposed method, the refraction angle is adjusted outside the vehicle as necessary. It may be preferable to make adjustments.

Therefore, here, a configuration in which a dielectric component for adjusting a refraction angle (refraction direction) is provided outside the vehicle is shown.
Various shapes may be used as the shape of the dielectric component. For example, a dielectric film having a film shape may be used as the dielectric component, or a dielectric block having a block shape may be used.

FIG. 10 is a diagram illustrating an example of a schematic configuration of the dielectric component 812 for adjusting the beam direction. FIG. 10 schematically shows a state in which the windshield 811 (the cross section thereof), the dielectric component 812 (the cross section thereof) and the periphery thereof are viewed from the lateral direction of the vehicle.
In the example of FIG. 10, the radar apparatus 21 includes a surface patch array antenna 801 using a microstrip line (MSL) inside the vehicle with respect to the windshield 811. Further, the radar device 21 includes a dielectric component 812 configured using a dielectric material in contact with the glass surface of the windshield 811 outside the vehicle.

In the example of FIG. 10, the dielectric component 812 is a thin film sheet (dielectric film) having a surface parallel to the glass surface of the windshield 811, and the glass surface and the parallel surface are brought into contact with each other. Is provided. The dielectric component 812 may be attached to the windshield 811 by various methods, for example, may be affixed, or may be fixed at several points on the peripheral edge. For example, the dielectric component 812 may be formed integrally with the windshield 811.
Various shapes may be used for the dielectric component 812 when viewed from the front of the windshield 811 (front shape). For example, a shape such as a square, a rectangle, or a circle may be used. Good. The shape of the front surface of the dielectric component 812 has such a size that all or a necessary amount of light rays (radio waves) communicated by the surface patch array antenna 801 pass through the dielectric component 812.

  By providing such a dielectric component 812, the radar apparatus 21 can adjust the radiation angle (final radiation direction) of the beam (light beam 822) to the outside of the vehicle with respect to transmission. Similarly, by providing such a dielectric component 812, the radar apparatus 21 can adjust the incident angle (final incident direction) of the incoming wave with respect to reception.

Here, the passage route of the light beam 822 will be described in the example of FIG.
The angle formed by the normal direction with respect to the surface (front surface) of the dielectric component 812 and the direction of the light beam 822 outside the vehicle and outside the dielectric component 812 is θ1. Inside the dielectric component 812, an angle formed by the normal direction with respect to the surface (front surface) of the dielectric component 812 and the direction of the light beam 822 is φ1.
Inside the windshield 811, the angle formed by the normal direction with respect to the glass surface of the windshield 811 (in the example of FIG. 10, the same direction as the normal direction with respect to the surface (front) of the dielectric component 812) and the direction of the light beam 822. Is φ2.
On the inner side of the vehicle, an angle formed by the normal direction with respect to the glass surface of the windshield 811 and the direction of the light ray 822 is θ2.
As the dielectric constant, the dielectric constant ε (glass) of the windshield 811, the dielectric constant ε (film) of the dielectric part 812, the air Air (Outside) outside the vehicle and the air Air (Inside) inside the vehicle. There is ε (air).

From the Fresnel formula, find the Brewster angle and determine the beam direction of the antenna. Basically, when the light is incident from a low dielectric constant to a high dielectric constant, the incident angle> the transmission angle (Snell's law). In the example of FIG. 10, the Brewster angle is tilted from the horizontal plane by about several degrees.
When radio waves are transmitted from the air layer inside the vehicle to the glass layer of the windshield 811, θ2> φ2 is satisfied due to ε (air) <ε (glass).
When radio waves are transmitted from the glass layer of the windshield 811 to the dielectric film layer of the dielectric component 812, φ2 <φ1 is satisfied by setting ε (glass)> ε (film). Although it is considered preferable to use a dielectric component 812 that satisfies ε (glass)> ε (film) as in the present embodiment, as another example, ε (glass) <ε (film). A dielectric component 812 may be used.
When radio waves are transmitted from the dielectric film layer of the dielectric component 812 to the air layer outside the vehicle, φ1 <θ1 because ε (film)> ε (air).
In accordance with such a condition, for example, by adjusting the dielectric constant of the dielectric component 812 and the angle of the sweep surface so that θ1 becomes a desired beam direction, the beam sweep direction is reduced while reducing loss due to glass reflection. Can be adjusted.

  Here, as the thickness of the dielectric component 812 (thickness in the direction perpendicular to the front surface, in the example of FIG. 10, the thickness in the same direction as the thickness direction of the windshield 811), there are various thicknesses. As a preferable example, in order to suppress internal reflection, it may be designed to have a thickness that is an integral multiple of λ / 4 (λ is the wavelength of light).

In the example of FIG. 10, a film shape is used as the shape of the dielectric component 812, but other shapes such as a block shape may be used as another configuration example.
In the example of FIG. 10, the dielectric component 812 is provided outside the vehicle. However, as another configuration example, a configuration in which the dielectric component 812 is provided inside the vehicle, or two dielectric components 812 are respectively provided in the vehicle. A configuration in which one piece is provided on each of the outer side and the inner side may be used.

  In the example of FIG. 10, the dielectric component 812 having a plane parallel to the glass surface of the windshield 811 is used. However, as another configuration example, depending on necessary conditions (for example, conditions of incidence and dielectric constant). Thus, a design in which the angle of the radiation or incident surface of the dielectric component 812 (the surface disposed on the side opposite to the windshield 811) and the angle of the glass surface of the windshield 811 are different, that is, for example, the dielectric component 812, for example. However, the other surface of the dielectric component 812 may be configured not to be parallel to the glass surface of the windshield 811.

FIG. 11A and FIG. 11B are diagrams showing schematic configurations of dielectric parts 901 and 902 according to other configuration examples, respectively.
FIGS. 11A and 11B each show a windshield 811 for convenience of explanation.
In the dielectric component 901 in the example of FIG. 11A and the dielectric component 902 in the example of FIG. 11B, the surface that is brought into contact with the glass surface of the windshield 811 is parallel to the glass surface. The surface facing the surface is not parallel to the glass surface (not parallel).

[Summary of this embodiment]
As described above, the radar apparatus 21 according to the present embodiment has a configuration in which reflection on the cover of a beam communicated (transmitted or received) by the antenna unit (portion having the antenna) is suppressed. Thereby, in the radar apparatus 21 according to the present embodiment, for example, when a beam is transmitted or received through the surface of a cover (for example, glass), the reflection loss on the surface can be reduced. , Efficiency can be achieved. In addition, the radar device 21 according to the present embodiment includes dielectric parts 812 and 901 to 902 for adjusting the beam direction with respect to the cover, whereby the direction of the beam communicated by the antenna unit is set to a desired value. It is possible to adjust the angle.
As an example, the radar device 21 according to the present embodiment can realize an in-vehicle radar device capable of improving efficiency when provided on a windshield of a vehicle.
In the present embodiment, the radar configuration and processing method (radar method) in the radar apparatus 21 can be provided.

<Measures at the place where the antenna is surrounded by a dielectric>
(First configuration example)
As an example of the configuration, the radar apparatus 21 includes a multi-beam lens antenna or a lens antenna capable of scanning the radiation direction. As another configuration example, the radar device 21 includes a reflector antenna.
A multi-beam lens antenna can be realized with the lens shape design itself, for example, using multiple radiators, or, as another example, electronic or mechanical, using a single radiator. Realized by radial scanning.
In the radar apparatus 21, the directivity of the beam in the vertical direction (or a predetermined direction such as the horizontal direction) with respect to the surface facing the dielectric cover (for example, glass such as the windshield of the vehicle) is Scanning is performed at an angle that can suppress reflection from the body cover.
(Second configuration example)
As an example of the configuration, the radar apparatus 21 includes an array antenna using a linear (for example, monopole or dipole) or patch type print antenna, and a phase shifter (or a predetermined direction such as a horizontal direction) in a phase shifter ( A beam control (for example, phase control) is performed by applying a phase adjuster), a different wiring length, or a receiver (for example, a digital beam forming function). In this case, in the radar apparatus 21, the directivity of the beam in the vertical direction (or a predetermined direction such as the horizontal direction) with respect to the surface facing the dielectric cover (for example, glass such as the windshield of the vehicle) is hard. Or scanning at an angle that can suppress reflection from the dielectric cover.
(Third configuration example)
As an example of the configuration, the radar device 21 has a linear shape (for example, a predetermined direction such as a vertical direction) on a surface facing a dielectric cover (for example, glass such as a windshield of a vehicle) in a linear shape (for example, Monopoles, dipoles, etc.) or patch-type printed antenna arrays are each tilted (for example, offset) in the vertical direction (or a predetermined direction such as the horizontal direction). In this case, in the radar device 21, each receiving element is provided with a phase shifter (phase adjuster), a different wiring length, a receiver (for example, a function of digital beam forming), or the like, and beam control (for example, phase shift). Control) may be performed. In the radar apparatus 21, the directivity of the beam in the vertical direction (or a predetermined direction such as the horizontal direction) with respect to the surface facing the dielectric cover is reflected by the hardware or software on the dielectric cover. Are scanned at an angle that can suppress the above.

<Effects of countermeasures at antenna installation locations surrounded by dielectrics>
In the radar apparatus 21 according to the present embodiment, a dielectric (for example, glass such as a windshield of a vehicle) that covers the antenna by realizing multi-beam characteristics by a lens antenna (or a reflector antenna). It is possible to obtain the effect of reducing unnecessary reflection loss due to. In the radar apparatus 21 according to the present embodiment, the reflection coefficient is greatly reduced by setting the incident angle of the radiated electromagnetic wave (beam) to the dielectric cover to the total transmission angle (or an angle close thereto). Can do. The radar apparatus 21 according to the present embodiment directs the beam of the multi-beam lens antenna (or the reflector antenna) so that the plane wave can be swept at an appropriate incident angle.
In the radar apparatus 21 according to the present embodiment, for example, it is possible to eliminate the angle adjustment of the sensor apparatus itself (for example, physically swinging the radar angle), which is a general countermeasure. Further, since the radar device 21 according to the present embodiment uses the secondary effect of the radiation antenna, for example, a refraction block or a conductive plate for adjusting the incident angle (see, for example, Patent Document 3). ) Can be eliminated. In the radar apparatus 21 according to the present embodiment, for example, by using scanning of an electric beam, even in a narrow space where physical adjustment cannot be performed (or difficult), it is arbitrary within a range where lens design is possible. The incident angle can be easily adjusted.
In the radar apparatus 21 according to the present embodiment, for example, a configuration in which a feeding phase in a vertical direction (or a predetermined direction such as a horizontal direction) of a linear or patch type printed antenna can be adjusted, and a beam And the angle of incidence on the dielectric cover (for example, a glass such as a windshield of a vehicle) can be optimized.

For example, the radar device 21 may be an array antenna for controlling a directivity and a gain with respect to a patch type (or linear) printed antenna, or a directivity synthesis process (for example, by hardware) , Processing for forming desired directivity) may be performed, or directivity synthesis processing (for example, processing for forming desired directivity) may be performed using digital beam forming by software. .
For example, the radar apparatus 21 may include a component (for example, a dielectric waveguide or a metal flare component) for controlling directivity and gain on a patch type (or linear) printed antenna.

In the present embodiment, the vehicle windshield is used as the dielectric cover, but other components in the vehicle may be used as another configuration example. For example, when assuming an omnidirectional radar, a resin cover in a side mirror of a vehicle may be used as a dielectric cover, or a resin cover on the back of a bumper on the rear of the vehicle may be used. Good. Further, for example, in the case where an anti-theft radar is assumed, a cover such as the back side of an interior part in the vehicle (inside the vehicle) may be used as the dielectric cover. A cover inside the room, a cover on the interior light, a cover inside the wheel, a cover under the metal on the ceiling, or the like may be used. As described above, various dielectric covers in the exterior or interior of the vehicle may be used as the dielectric cover.
In the present embodiment, the configuration in which the radar device is provided in the vehicle is shown. However, as another configuration example, the radar device may be provided in various places other than the vehicle.

[Summary of the above embodiments]
As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the concrete structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the summary of this invention are included.

  Further, a program for realizing the functions of each device and each processing unit (for example, transmission unit, reception unit) according to the above-described embodiment is recorded on a computer-readable recording medium, and the recording medium is recorded on this recording medium. Processing may be performed by reading the recorded program into a computer system and executing it.

The “computer system” herein may include hardware such as an operating system (OS) and peripheral devices.
The “computer-readable recording medium” means a flexible disk, a magneto-optical disk, a ROM (Read Only Memory), a writable nonvolatile memory such as a flash memory, a portable medium such as a DVD (Digital Versatile Disk), A storage device such as a hard disk built in a computer system.

Further, the “computer-readable recording medium” refers to a volatile memory (for example, DRAM (DRAM) inside a computer system that becomes a server or a client when a program is transmitted through a network such as the Internet or a communication line such as a telephone line. Dynamic Random Access Memory)) that holds a program for a certain period of time is also included.
The program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the “transmission medium” for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line.
Further, the above program may be for realizing a part of the functions described above. Further, the above program may be a so-called difference file (difference program) that can realize the above-described functions in combination with a program already recorded in the computer system.

DESCRIPTION OF SYMBOLS 1 ... Vehicle, 11, 511, 811 ... Windshield, 12, 13 ... Side mirror, 21 ... Radar apparatus, 101 ... Primary radiator, 102 ... Lens, 121 ... Central axis, 131-132, 822 ... Ray, 201- DESCRIPTION OF SYMBOLS 1-201-4 ... Array antenna, 202 ... Reception part, 221-224 ... Antenna, 301-1 to 301-n, 401-1 to 401-n ... Radiation element, 321-1 to 321- (n-1) , 421-1 to 421- (n-1) ... wiring, 441-1 to 441- (n-1) ... phaser, 501, 501R, 801 ... plane patch array antenna, 501T ... patch array antenna, 522 ... coming. Wave, 601-602 ... Patch antenna, 701 ... Antenna part, 702 ... DBF part, 812, 901-902 ... Dielectric part, 1001-1002, 1101 ... Characteristic, 1 11 ... total transmission angle

Claims (13)

An antenna unit including a lens antenna, a reflector antenna, or an array antenna, and a cover that covers part or all of the antenna unit,
The antenna unit and the cover are configured so that reflection of the beam communicated by the antenna unit on the cover is suppressed.
Radar device. The antenna unit includes the lens antenna or the reflector antenna,
The lens antenna or the reflector antenna has multi-beam characteristics by designing the shape of the lens or reflector, or by scanning in the electronic or mechanical radial direction.
The radar apparatus according to claim 1. The antenna unit includes a plurality of the array antennas,
The plurality of array antennas are arranged offset,
The radar apparatus according to claim 1. The antenna unit includes a plurality of the array antennas,
For the plurality of the array antennas, beam control is performed by one or more of a phase shifter, a different wiring length, or a receiver.
The radar apparatus according to claim 1. As a configuration in which the reflection of the beam communicated by the antenna unit on the cover is suppressed, a configuration in which the directivity of the beam in a predetermined direction with respect to the surface facing the cover is an angle at which the reflection on the cover is suppressed Used,
The radar apparatus according to any one of claims 1 to 4. As a configuration in which the reflection is suppressed, a configuration in which total transmission is realized was used.
The radar apparatus according to any one of claims 1 to 5. The cover is a dielectric cover;
The radar apparatus according to any one of claims 1 to 6. The cover is composed of a part or all of dielectric parts in a vehicle provided with the radar device.
The radar apparatus according to any one of claims 1 to 7. Furthermore, a dielectric component for adjusting the angle of the beam is provided.
The radar apparatus according to any one of claims 1 to 8. The dielectric component has a film shape or a block shape,
The radar apparatus according to claim 9. The dielectric component is provided such that one surface of the dielectric component is brought into contact with one surface of the cover.
The radar device according to claim 9. The cover has a flat plate shape,
The dielectric component has a surface on the side of the cover parallel to the surface of the cover, and a surface opposite to the side of the cover is parallel or non-parallel to the surface of the cover.
The radar apparatus according to any one of claims 9 to 11. An antenna unit including a lens antenna, a reflector antenna, or an array antenna, and a cover that covers part or all of the antenna unit, so that reflection of a beam communicated by the antenna unit on the cover is suppressed. A beam is communicated by the antenna unit of the radar device in which the unit and the cover are configured,
Radar method.

Images