Radar sensor with decoupling means for surface waves

Abstract

The invention relates to a radar sensor (10) having a waveguide antenna (12) for emitting and / or receiving radar waves (14) relative to a sensor environment (16) of the radar sensor (10), the waveguide antenna having a base body (18), an antenna surface (20) on the base body (18), a first antenna element (24) and a second antenna element (34), the antenna surface facing the sensor environment (16) and having an electrically conductive surface material (22), the first antenna element being embodied as at least one opening (26) in the antenna surface (20), the second antenna element (34) being embodied as at least one further opening (36) in the antenna surface (20), wherein the waveguide antenna (12) has a decoupling device (38) at least between the first and second antenna elements (24, 34), the decoupling device being set up for at least changing the transmission of surface waves (40) of the radar waves (14) extending as surface layers between the first and second antenna elements (24, 34).

Description

Technical Field

[0001] The present invention relates to a radar sensor according to the preamble of claim 1. Background Technology

[0002] A radar sensor having a waveguide antenna made by injection molding is described in DE 10 2022 202 140 A1.

[0003] DE 10 2018 218 253 A1 describes a radar sensor having an antenna structure and a coupling structure for selectively coupling surface waves output from the antenna structure. The coupled surface waves are absorbed by an absorber in a radome. This improves the radiation characteristics of the radar sensor. Summary of the Invention

[0004] According to the present invention, a radar sensor having the features described in claim 1 is provided. This reduces crosstalk between antenna elements. Antenna elements can be more effectively decoupled from each other. The radar sensor can operate more reliably and can be implemented more cost-effectively. The measurement accuracy of the radar sensor can be improved.

[0005] Radar sensors can be deployed in vehicles, especially motor vehicles, trucks, and / or two-wheeled vehicles. Radar sensors can also be deployed in mobile robots.

[0006] Radar waves can be electromagnetic waves in the millimeter wave band.

[0007] A waveguide antenna can be constructed from multiple components. These components can be constructed from different materials. A waveguide antenna can be a receiving antenna and / or a transmitting antenna for radar waves.

[0008] The first and second antenna elements are structural components of a waveguide antenna that transmits electromagnetic energy between the radar sensor and its environment. The first and / or second antenna elements can be implemented as slots.

[0009] Within the substrate, multiple waveguides for transmitting radar waves can be implemented as waveguides. The substrate can be arranged on a circuit board.

[0010] The first antenna element and / or the second antenna element may be connected to at least one waveguide in the waveguide for transmitting radar waves. The substrate may be formed from a substrate material. The substrate can be manufactured by injection molding and / or 3D printing. The substrate may be at least partially, and especially completely, preferably coated with a surface material. The substrate may be constructed from a plastic, especially a thermoplastic or thermosetting plastic. The plastic may be filled with carbon.

[0011] Protective components can protect radar sensors from environmental influences, particularly dirt, moisture, and / or water. These protective components can be radomes, housings, and / or decorative elements, especially vehicle bumpers or body panels. They can be constructed from plastics and / or composite materials to allow radar waves to pass through.

[0012] The antenna surface can form at least a section of the radar sensor surface. Protective components can also form part of the sensor surface.

[0013] The surface material can be metal or metal alloy.

[0014] Surface waves are radar waves that extend primarily and / or at least in the initial propagation path from the generation of the surface wave within and / or along the physical structure of the radar sensor, for example, relative to the surface layer of the substrate and / or antenna surface.

[0015] Decoupling devices are introduced as an adjunct to antenna elements and should be distinguished from the antenna elements. Decoupling devices can be arranged at least segmentally in the direct connection between the first antenna element and the second antenna element. Decoupling devices can be centered relative to the extension of the connection or arranged outside the center of the connection. Decoupling devices can be arranged on the main part of the connection segment. Decoupling devices can be adapted in at least one dimension, particularly in multiple dimensions, preferably in all dimensions, to set the impedance and / or phase and / or amplitude changes of the surface wave of the decoupling device, said dimensions being, for example, length, width, depth, or height.

[0016] The adaptation of the first antenna element can be adapted to the adaptation of the second antenna element through a suitable arrangement and / or sizing of the decoupling device, or specifically set in a manner deviating from the adaptation of the second antenna element. The adaptation of the first antenna element can be the transmission coefficient, reflection coefficient, and / or return current attenuation of the corresponding antenna element, particularly frequency-dependent, where the return current attenuation is particularly frequency-dependent. This adaptation can include a target frequency range in which at least one of the previously mentioned parameters is set below a threshold. The decoupling device can implement the target frequency range at the first antenna element, which is either angulated or misaligned relative to the target frequency range of the second antenna element. In the case of a misaligned target frequency range, the bandwidth of the radar sensor can be increased.

[0017] The waveguide antenna may have a third antenna element, which is implemented as at least one additional opening in the antenna surface. In addition to a decoupling device arranged between the first and second antenna elements as a first decoupling device, the waveguide antenna may have a second decoupling device structured between or between the second and third antenna elements, configured to modify the transmission of surface waves, which appear as surface-extended radar waves in the waveguide antenna, between the second and third antenna elements or between the first and third antenna elements. The first and second decoupling devices may be implemented and / or arranged such that the remaining transmission of the surface waves via the first decoupling device is aligned with the remaining transmission of the surface waves via the second decoupling device. This generally homogenizes the transmission of the surface waves.

[0018] In an advantageous embodiment of the invention, the decoupling device is configured to suppress, in particular block, the propagation of surface waves. The propagation of surface waves can be suppressed by scattering, reflection, and / or absorption of surface waves.

[0019] In a particular embodiment of the invention, it is advantageous that the decoupling device is implemented as a structured decoupling device on the antenna surface. This directly alters the propagation of surface waves between the first and second antenna elements. The surface waves can be at least partially deflected into the substrate by the decoupling device.

[0020] In a preferred embodiment of the invention, it is advantageous that the decoupling device has at least one sub-volume in the substrate, a void and / or a recess and / or a protrusion relative to the antenna surface in the antenna surface. The void, recess, and / or protrusion may have at least one inclined sidewall.

[0021] In an advantageous embodiment of the invention, the sub-volumes, empty portions, recesses, and / or protrusions are provided with a filling material and / or a surface material relative to the sensor environment, the surface material being different from the original surface material. The conductivity of the surface material may be greater than that of the filling material and / or the surface material. The complex capacitance and / or complex permeability of the surface material may be greater than or less than that of the filling material and / or the surface material. The surface material may correspond to or differ from the filling material.

[0022] In a preferred embodiment of the invention, the material of the surface layer and / or the filler material is different from the matrix material of the substrate. The filler material and / or the material of the surface layer can be thermoplastic or thermosetting plastic. At least one bottom surface, one sidewall, preferably all sidewalls, of the sub-volume, the empty portion, the recessed portion, and / or the protrusion, can have a surface material, a matrix material, a surface layer material, and / or a filler material.

[0023] In an advantageous embodiment of the invention, the decoupling device is implemented within a substrate. The decoupling device may be a void that is at least partially, and particularly completely, surrounded by the substrate. The void may be open or closed relative to the sensor environment. The decoupling device may be partially or completely filled with a filler material.

[0024] In a preferred embodiment of the invention, the decoupling device is configured to scatter, reflect, and / or absorb surface waves into the sensor environment. This can suppress the propagation of surface waves between the first antenna element and the second antenna element. The decoupling device can also selectively scatter the surface waves of the first antenna element before or in a region of the second antenna element, for example, to modify the adaptation to the second antenna element. The decoupling device can also selectively scatter the surface waves of the second antenna element before or in a region of the first antenna element, for example, to modify the adaptation to the first antenna element. The decoupling device can also modify the surface waves themselves, such as the amplitude, phase, and / or frequency of the surface waves.

[0025] In an advantageous embodiment of the invention, the waveguide antenna has an absorbing device for absorbing surface waves. This attenuates the surface waves. The absorbing device may at least partially have an absorbing material different from the surface material. The absorbing device can be formed of at least one material that absorbs radar waves, particularly having a loss factor describing dielectric loss greater than 0.01, especially greater than 0.1. The absorbing material may correspond to or differ from the filler material and / or the matrix material.

[0026] In a particular embodiment of the invention, it is advantageous that the absorbing device is at least regionally formed through the substrate. This allows for the cost-effective and space-saving implementation of the radar sensor. The absorbing device can be predominantly formed from the substrate. The decoupling device can have multiple absorbing devices.

[0027] Other advantages and advantageous configurations of the invention will become apparent from the accompanying drawings and description. Attached Figure Description

[0028] The present invention will now be described in detail with reference to the accompanying drawings. The drawings show in detail: Figure 1Cross-section of a radar sensor in a particular embodiment of the present invention.

[0029] Figure 2 Cross-section of a radar sensor in another specific embodiment of the invention.

[0030] Figure 3 Cross-section of a radar sensor in another specific embodiment of the invention. Detailed Implementation

[0031] Figure 1 A cross-section of a radar sensor in a particular embodiment of the invention is shown. The radar sensor 10 includes a waveguide antenna 12 for emitting and / or receiving radar waves 14 relative to a sensor environment 16. The radar sensor 10 may be disposed in a vehicle. The waveguide antenna 12 includes a substrate 18 and an antenna surface 20 on the substrate 18, the antenna surface facing the sensor environment 16, the antenna surface having at least sectionally conductive surface material 22.

[0032] Furthermore, the waveguide antenna 12 includes at least one first antenna element 24, which is implemented as an opening 26 in the antenna surface 20. Radar waves 14 are generated and / or processed by a sensor chip 28. The sensor chip 28 is connected to the first antenna element 24 via a waveguide channel 30, which is at least sectionally implemented as a waveguide, for transmitting radar waves 14. The sensor chip 28 is disposed on a circuit board 32, which is housed in a substrate 18.

[0033] Figure 2 A cross-section of a radar sensor in another specific embodiment of the invention is shown. The radar sensor 10 includes a waveguide antenna 12 having a substrate 18 and an antenna surface 20 on the substrate 18, the antenna surface having a conductive surface material 22. The surface material 22 may be a metal or a metal alloy and is applied as a surface layer onto the substrate 18.

[0034] The first antenna element 24 is implemented as an opening 26 in the antenna surface 20. In addition, the waveguide antenna 12 includes a second antenna element 34 spaced apart from the first antenna element 24, which is implemented as another opening 36 in the antenna surface 20.

[0035] The waveguide antenna 12 includes a structured decoupling device 38 configured to alter the propagation of surface waves 40, which are radar waves extending from the surface layer, between the first antenna element and the second antenna elements 24, 34. The surface waves 40 can originate from the first antenna element and the second antenna elements 24, 34, respectively. The decoupling device 38 is structured on the antenna surface 20 and includes a gap 42 in the antenna surface 20 between the first antenna element and the second antenna elements 24, 34, at least one additional gap 44 in the antenna surface 20 adjacent to the first antenna element 24, and at least one additional gap 46 in the antenna surface 20 adjacent to the second antenna element 34. The gaps 42, 44, 46 here specifically interrupt the surface material 22.

[0036] The empty portion 42 is adjacent to a sub-volume 48 in the substrate 18, which is filled with a filler material 50 that is different from the surface material 22 and, in particular, from the substrate material of the substrate 18. The sub-volume 48 extends into the substrate 18 at a depth 52 and has a surface material 53 relative to the sensor environment 16, which corresponds to the filler material 50.

[0037] A further empty portion 44 adjacent to the first antenna element 24 has a sub-volume 54 filled with a filling material 50. The further empty portion 44 is larger than the empty portion 42 relative to the antenna surface 20, and the sub-volume 54 extends at least partially below the antenna surface 20 within the substrate 18. Similarly, a further empty portion 46 adjacent to the second antenna element 34 has a sub-volume 56 filled with a filling material 50. The further empty portion 46 is larger than the empty portion 42 relative to the antenna surface 20, and the sub-volume 56 extends at least partially below the antenna surface 20 within the substrate 18.

[0038] Radar wave 14 from the first antenna element 24 is emitted into the sensor environment 16. This generates a surface wave 40, which is a surface extension of the radar wave originating from the first antenna element 24. The propagation of the surface wave 40 to the second antenna element 34 is suppressed by a decoupling device 38, in that the surface wave 40 is scattered into the sensor environment 16, for example, at the sub-volume 48. The surface wave 40 emitted from the first antenna element 24 in the opposite direction to the second antenna element 34 is scattered into the sensor environment 16 by the sub-volume 54. Additionally, the substrate 18 may at least regionally constitute an absorbing device 58 for the surface wave 40, which at least partially absorbs the surface wave 40. The sub-volume 54 may also be at least partially filled to form the absorbing device 58.

[0039] The surface wave 40 originating from the second antenna element 34 in the direction of the first antenna element 24 is also impeded by the sub-volume 48 in its further propagation to the first antenna element 24, and is scattered, for example, into the sensor environment 16. This reduces crosstalk between the first antenna element and the second antenna elements 24, 34 caused by the surface wave 40.

[0040] The surface wave 40 emitted from the second antenna element 34 in the opposite direction to the first antenna element 24 is impeded in further transmission by the sub-volume 56 and scattered into the sensor environment 16. Additionally, the sub-volume 56 may at least regionally constitute an absorbing device 58 for the surface wave 40, which at least partially absorbs the surface wave 40.

[0041] Figure 3 A cross-section of a radar sensor in another specific embodiment of the invention is shown. The decoupling device 38 is implemented as a recess 60 in the antenna surface 20. Here, surface material 22 is also disposed in the recess 60. The recess 60 is recessed relative to the antenna surface 20 at a depth 52. The bottom surface 61 and sidewall 62 of the corresponding recess 60 are covered by the surface material 22. The sidewall 62 is implemented at an angle to scatter surface waves 40 into the sensor environment 16.

Claims

1. A radar sensor (10), the radar sensor having A waveguide antenna (12) for emitting and / or receiving radar waves (14) relative to a sensor environment (16) of the radar sensor (10), the waveguide antenna having a substrate (18), an antenna surface (20) on the substrate (18), a first antenna element (24) and a second antenna element (34), the antenna surface facing the sensor environment (16) and having a conductive surface material (22), the first antenna element being implemented as at least one opening (26) in the antenna surface (20), and the second antenna element (34) being implemented as at least one additional opening (36) in the antenna surface (20). Its features are, The waveguide antenna (12) has at least a decoupling device (38) between the first antenna element and the second antenna element (24, 34), the decoupling device being configured to at least alter the transmission of the surface wave (40) of the radar wave (14) as a surface extension between the first antenna element and the second antenna element (24, 34).

2. The radar sensor (10) according to claim 1, characterized in that, The decoupling device (38) suppresses the transmission of the surface wave (40).

3. The radar sensor (10) according to claim 1 or 2, characterized in that, The decoupling device (38) is implemented as a structured decoupling device (38) on the antenna surface (20).

4. The radar sensor (10) according to any one of the preceding claims, characterized in that, The decoupling device (38) has at least one sub-volume (48, 54, 56) in the substrate (18), a void (42) and / or a recess (60) in the antenna surface (20) and / or a protrusion relative to the antenna surface (20).

5. The radar sensor (10) according to claim 4, characterized in that, The sub-volumes (48, 54, 56), the empty portion (42), the recess (60) and / or the protrusion have a filling material (50) and / or a surface material (53) relative to the sensor environment (16), the surface material being different from the surface material (22).

6. The radar sensor (10) according to claim 5, characterized in that, The material of the surface layer (53) and / or the filling material (50) is different from the matrix material of the substrate (18).

7. The radar sensor (10) according to any one of the preceding claims, characterized in that, The decoupling device (38) is implemented within the substrate (18).

8. The radar sensor (10) according to any one of the preceding claims, characterized in that, The decoupling device (38) is configured to scatter the surface wave (40) into the sensor environment (16), reflect and / or absorb the surface wave (40).

9. The radar sensor (10) according to any one of the preceding claims, characterized in that, The waveguide antenna (12) has an absorbing device (58) for absorbing the surface wave (40).

10. The radar sensor (10) according to claim 9, characterized in that, The absorption device (58) is formed at least regionally through the substrate (18).

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