Radar sensor having a holding element with a destruction means

Abstract

The invention relates to a radar sensor (10) having an antenna element (12) with at least one antenna opening (16), located on an environment-facing antenna surface (14), for emitting and / or receiving radar waves (R), and a carrier element (30), wherein a holding element (18) which mechanically fastens the antenna element (12) with respect to the carrier element (30) is disposed, and the holding element (18) has destruction means (34) for destructive interference of incoming reflected radar waves (R', R'', S', S'').

Description

[0001] R. 417702

[0002] - 1 -

[0003] Description

[0004] title

[0005] Radar sensor with a retaining element containing a destructive agent

[0006] The invention relates to a radar sensor according to the preamble of claim 1.

[0007] State of the art

[0008] German patent DE 102018218253 A1 describes a radar sensor comprising an antenna structure and a coupling structure for the targeted extraction of surface waves from the antenna structure. The extracted surface waves are radiated onto an absorber and absorbed in a directional pattern different from that of the antenna structure.

[0009] Disclosure of the invention

[0010] According to the present invention, a radar sensor with the features of claim 1 is proposed. This allows unwanted reflections of the incoming radar waves at the radar sensor to be reduced.

[0011] The radar sensor can be located in a vehicle, a robot, or a device.

[0012] Radar waves can be electromagnetic waves, particularly in the millimeter band. In destructive interference, incoming reflected radar waves with a phase difference, ideally 180°, can be superimposed and thus weakened. Destructive interference can also occur with phase differences that deviate slightly from 180°, for example, by 10°.

[0013] The antenna element can have several antenna openings on its surface for coupling radar waves into the environment and / or for receiving R. 417702

[0014] - 2 -

[0015] The antenna element can be a plastic component, particularly one containing metal components.

[0016] The incoming radar waves can be radar waves previously emitted through the antenna opening, at least one further antenna opening, another antenna element, and / or another radar sensor, and in particular, subsequently reflected. The incoming radar waves can originate from the vicinity of the antenna element, in particular from the vicinity of the radar sensor. The incoming radar waves can be reflected by the mounting element and / or the antenna surface.

[0017] The retaining element can attach the antenna element, preferably directly, to the support element. The support element and the antenna element can additionally be electrically connected and / or for transmitting the radar waves. The retaining element can position the antenna element laterally and / or in the normal direction relative to the support element.

[0018] The retaining element for attaching the antenna element to the support element can be rigid, flexible, and / or spring-loaded. The retaining element can secure the antenna element to the support element by means of a spring force.

[0019] The retaining element can be connected to the antenna element by positive locking, force locking, and / or material locking. The retaining element can be clipped to the antenna element or connected by an interference fit. The retaining element can be configured as a hold-down and / or clamping element. The retaining element can be connected to the antenna element and / or the support element by injection molding. The retaining element can be detachably connected to the antenna element.

[0020] The retaining element can be connected to the support element by form-fit, force-fit, and / or material-fit connection. The retaining element can be clipped to the support element or connected by an interference fit. The retaining element can be detachably connected to the support element. The retaining element and the support element can be directly connected to each other. R. 417702

[0021] - 3 -

[0022] The mounting element can attach another antenna element to the support element in addition to the antenna element itself. The mounting element can align the antenna element and the other antenna element relative to each other.

[0023] The mounting element can be positioned above the antenna surface in a normal direction. Alternatively, the mounting element can be positioned laterally next to the antenna element.

[0024] The retaining element can further secure the support element to a housing. The retaining element can be made of plastic, preferably a plastic containing metal components, and / or metal. The retaining element can be a single piece or multi-part. The retaining element can be made of at least two different materials, for example, metal and plastic.

[0025] Lateral refers to a directional reference, and lateral direction refers to a direction in the plane that has the normal direction as its normal.

[0026] The destructive agents can cause destructive interference of the incoming reflected radar waves of one or more wavelengths.

[0027] The retaining element can incorporate an absorber material for absorbing electromagnetic energy from radar waves incident on the retaining element. The absorber material can have a loss factor greater than 0.01, particularly greater than 0.1, describing the dielectric losses. The absorber material can be positively, force-, and / or material-bonded to the retaining element. The absorber material can be a plastic, a carbon-based material, a conductive polymer, a foam, and / or a ceramic material.

[0028] In a preferred embodiment of the invention, it is advantageous if the retaining element has at least one recess that does not cover the antenna surface, and if the area of ​​the antenna surface of the at least one recess and the area of ​​the antenna surface covered by the retaining element are equal to each other. The area sizes can be equal to each other by being the same size or by differing from each other by at most 20%, preferably at most 10%. This allows the R. 417702

[0029] - 4 -

[0030] The proportion of the incoming reflected radar waves is balanced.

[0031] In a particular embodiment of the invention, it is advantageous if the retaining element has recesses spaced apart from each other in at least one lateral direction. The recesses can be fully enclosed. The recesses can also be spaced apart from each other in a further lateral direction perpendicular to the lateral direction.

[0032] In an advantageous embodiment of the invention, the destructive means are formed by at least one dimension of the retaining element. This dimension can be a multiple of 2 / 4, particularly an odd multiple. This multiple can be a natural number greater than or equal to 1, particularly an odd multiple.

[0033] In total, the wavelength denotes the radar waves emitted and / or received by the antenna element in air.

[0034] A preferred embodiment of the invention is advantageous in which the dimension of the retaining element is a height difference of at least one recess in a region of the retaining element facing away from the antenna surface. The height difference of the recess relative to the region of the element can be a multiple of 2 / 4, particularly an odd multiple. The retaining element can have several recesses. The recesses can be arranged alternately in a lateral direction.

[0035] In a particular embodiment of the invention, it is advantageous if the destructive means are formed by a distance between a surface area of ​​the retaining element facing away from the antenna surface and the antenna surface. This distance can be a multiple of 2 / 4, particularly an odd multiple. The multiple can be a natural number greater than or equal to 1, particularly an odd multiple.

[0036] In a preferred embodiment of the invention, it is advantageous if the destructive means are characterized by a transit time difference of the radar waves propagating within the holding element compared to those outside the holding element. R. 417702

[0037] - 5 -

[0038] The retaining element material is formed by the radar waves propagating through it. The time-of-flight difference can cause a phase difference of 180° between the parallel radar waves. The height of the retaining element and / or the dielectric constant of the retaining element material can be adjusted such that the path length of the radar waves propagating within the retaining element and the parallel path length of the radar waves outside the retaining element exhibit a time-of-flight difference that results in destructive interference. The retaining element has a dielectric constant that differs from that of air.

[0039] The incoming reflected radar waves may have passed through the holding element, at least partially, before reflection leading to destructive interference.

[0040] In an advantageous embodiment of the invention, the retaining element has a surface structure that promotes the scattering of incident radar waves. The surface structure can be specifically designed to scatter the radar waves. The surface structure can be formed by a roughened area. The surface structure can have a roughness adapted to a specific wavelength of the radar waves. The roughness can have a mean roughness value R. a exhibiting a roughness greater than or equal to A / 8. For example, the roughness can have a mean roughness value greater than 100 pm for radar waves in the millimeter band.

[0041] The surface structure can exhibit multiple surface angles relative to the normal direction over at least one lateral direction. This allows the overall angular range of reflections to be broadened, thus distributing the power of the reflections more evenly across the entire area. The angle-related impairment of the radar sensor by the reflections can therefore be reduced.

[0042] In a particular embodiment of the invention, it is advantageous if the antenna element is a waveguide antenna with a waveguide structure connected to the antenna opening for transmitting the radar waves. The waveguide structure can be connected to the antenna opening for transmitting the radar waves. The transmission of the radar waves can proceed from the waveguide structure to the antenna opening and / or from the antenna opening to the waveguide structure. R. 417702

[0043] - 6 -

[0044] In a preferred embodiment of the invention, the carrier element is designed as a printed circuit board, in particular with at least one radar chip, for generating and coupling the radar waves into the antenna element and / or for receiving and processing the radar waves from the antenna element, or as a protective cover. The printed circuit board can have several radar chips. The protective cover can be a radome. The protective cover can be formed by a vehicle component. The antenna element can be attached to the carrier element by a retaining element and to the protective cover by a further retaining element, or vice versa.

[0045] The support element can be arranged above and / or below the antenna element in the normal direction.

[0046] Further advantages and advantageous embodiments of the invention will become apparent from the description of the figures and the illustrations.

[0047] Character description

[0048] The invention is described in detail below with reference to the illustrations. These show, in detail:

[0049] Figure 1: A top view of a radar sensor in a special embodiment of the invention.

[0050] Figures 2 to 15: A cross-section of a radar sensor, each in a specific embodiment of the invention.

[0051] Figure 1 shows a top view of a radar sensor in a particular embodiment of the invention. The radar sensor 10 comprises an antenna element 12 with several antenna openings 16 arranged on an external antenna surface 14, at least for emitting radar waves. Some of the antenna openings 16 may also be configured to receive reflected radar waves. R. 417702

[0052] - 7 -

[0053] The antenna element 12 is mechanically fastened to a support element (not visible here) by a retaining element 18. The retaining element 18 is arranged above the antenna surface 14 in a normal direction 20 of the antenna surface 14.

[0054] The retaining element 18 has cutouts 22 in the normal direction 20 that do not cover the antenna openings 16, in order to allow the radar waves emanating from the antenna openings 16 to be emitted and, if necessary, also received unimpeded. The surface area of ​​the antenna surface 14 of the cutouts 22 and the surface area of ​​the antenna surface 14 covered by the retaining element 18 are preferably equal to each other.

[0055] The radar sensor 10 in Figure 2 comprises an antenna element 12 with at least one antenna opening 16 arranged on an ambient antenna surface 14 at least for emitting radar waves R and a circuit board 24 with at least one radar chip (not shown here) for processing received radar waves and / or for generating radar waves, which are transmitted, for example, via a waveguide structure 26 of the antenna element 12 designed as a waveguide antenna 28 to the antenna opening 16.

[0056] A retaining element 18 is arranged on an external antenna surface 14 of the antenna element 12. The antenna element 12 is mechanically attached to a support element (not shown) via the retaining element 18. The support element is, for example, a protective cover, in particular a radome, for the radar sensor 10. The support element can be formed by a vehicle component.

[0057] The retaining element 18 has destructive means 34 for the destructive interference of reflected radar waves R' arriving at the antenna surface 14 and reflected radar waves R" arriving at the retaining element 18. The destructive means 34 are formed by at least a distance 36 between a region surface 38 of the retaining element 18 facing away from the antenna surface 14 and the antenna surface 14. The distance 36 is, for example, an odd multiple of 2 / 4 and can thus be used to prevent interference of the reflected radar waves R' arriving at the region surface 38 and the antenna surface 14. 417702

[0058] - 8 -

[0059] Radar waves R', R" with a phase difference of 180° cause cancellation.

[0060] The radar sensor 10 in Figure 3 corresponds to that in Figure 2 except for the following differences. The retaining element 18 has, as a destructive means 34, at least one recess 40 in a surface area 38 of the retaining element 18 facing away from the antenna surface 14. The height difference 42 of the recess 40 relative to the surface area 38 is preferably a multiple of 2 / 4. This allows reflected radar waves S' arriving at the surface area 38 and reflected radar waves S" arriving at the recesses 40 to interfere destructively.

[0061] The recesses 40 are arranged alternately in a lateral direction 44. This allows reflections of radar waves S' at the surface 38 and of radar waves S" at the recesses 40 to occur offset from each other along the lateral direction 44, resulting in destructive interference. Additionally, the distance 36 between the surface 38 and the antenna surface 14, as described in Figure 2, can act as a destructive means 34 for the destructive interference of radar waves R', R" of another wavelength that reflect at the antenna surface 14 and the surface 38. By appropriately adjusting the distance 36 and the height difference 42, destructive interference of two different wavelengths, and thus frequencies, of the radar waves can be achieved.

[0062] The radar sensor 10 in Figure 4 has the retaining element 18, which attaches the antenna element 12 to the support element 30, here the protective cover 32, and to the circuit board 24. The destructive means 34 are formed by a retaining element material that causes a time difference between the radar waves R' propagating in the retaining element 18 and the radar waves R" propagating outside the retaining element 18. The retaining element material can be a plastic. The height 46 of the retaining element 18 and the dielectric constant of the retaining element material are preferably adapted such that the time difference between the radar waves R' propagating in the retaining element 18 and the time difference between the radar waves R" propagating parallel outside the retaining element 18 results in destructive interference. R. 417702

[0063] - 9 -

[0064] The radar sensor 10 in Figure 5 corresponds to that in Figure 4, except that the mounting elements 18 are inclined with respect to the normal direction 20. This allows for angle-dependent destructive interference of radar waves R', R" reflected obliquely with respect to the antenna surface 14. The inclination angle 48 of the mounting elements 18 can be adjusted depending on the desired angle of incidence.

[0065] The height of the holding element 18 is preferably adapted such that a path length W of the radar waves R' passing in the holding element 18 and a parallel path length of the radar waves R" outside the holding element 18 have a time difference to the destructive interference upon reflection at the antenna surface 14.

[0066] The radar sensor 10 in Figure 6 corresponds to that in Figure 4; however, the retaining element 18 further comprises a cover element 50, made, for example, of metal or plastic, which is connected to spacer elements 52 made of a retaining element material. The retaining element 18 has alternating recesses 54 in at least one lateral direction 44, which are distributed in a predetermined pattern.

[0067] The destructive means 34 are formed, on the one hand, by the height 46 of the spacer elements 52 and, on the other hand, by the dielectric constant of the holding element material, in order to cause a time-of-flight difference of the radar waves R', R" to cause destructive interference. The recesses 54, in turn, can cause destructive interference for radar waves S', S" with at least one other wavelength and / or a predetermined angle of incidence upon reflections at the surface of the spacer elements 52 and the area surface 38 of the cover element 50. Thus, the radar sensor 10 can implement destructive interference at several wavelengths and / or depending on the angle.

[0068] The radar sensor 10 in Figure 7 includes the retaining element 18. The retaining element 18 can be made of a plastic enriched with metal components and have a surface structure 58 that promotes the scattering 56 of incoming reflected radar waves. The surface structure 58 can have several surface angles 60 with respect to the normal direction 20 over at least one lateral direction 44. This allows the angular range of the total reflections to be broadened and thus the performance of the total reflections to be increased. R. 417702

[0069] - 10 -

[0070] They are more spatially distributed. The angle-related impairment caused by reflections can be reduced.

[0071] The sub-areas 62 of the surface structure 58, which may have a normal to the normal direction 20 of the area surface 38, have a distance 36 to the antenna surface 14 as shown in Figure 2.

[0072] The radar sensor 10 in Figure 8 comprises the retaining element 18 with a surface structure 58 that promotes the scattering 56 of incoming reflected radar waves. The surface structure 58 is formed by a roughened area surface 38. A roughness adapted to a specific wavelength of the radar waves can be implemented. The roughness can have a mean roughness value R. a of greater than or equal to A / 8. For example, the roughness should have a mean roughness value R a exhibiting radar waves in the millimeter band of greater than 100 pm.

[0073] The retaining element 18 can have a distance 36 to the antenna surface 14 as described in Figure 2.

[0074] In the radar sensor 10 shown in Figure 9, the retaining element 18 has separating elements 64 between the antenna openings 16. These separating elements reduce coupling between the antenna openings 16 by the transmission of radar waves R', in particular surface waves, which are generated in addition to the radar waves R emitted through the antenna openings 16. The separating elements 64 can absorb and / or emit the surface waves and are preferably made of the same material as a cover element 50 arranged on the separating elements 64. The cover element 50 can be located at a distance 36 from the antenna surface 14, as described in Figure 2.

[0075] The radar sensor 10 in Figure 10 corresponds to that in Figure 9, however, the separating elements 64 run obliquely to the antenna surface 14 and can thus cause a targeted radiation characteristic of the antenna openings 16.

[0076] The radar sensor 10 in Figure 11 corresponds to that in Figure 10; however, the separating elements 64 of the retaining element 18 project into the antenna surface 14 of the antenna element 12 and can thus reliably attenuate surface waves between the antenna openings 16. A distance between the R. 417702

[0077] - 11 -

[0078] Interference between the separating elements 64 and the antenna surface 14, which would impair the shielding of the surface waves, can be reliably prevented.

[0079] The radar sensor 10 in Figure 12 corresponds to that in Figure 9, except that the cover element 50 is made of a different material than the separating elements 64. For example, the cover element 50 is made of metal and the separating elements 64 are made of plastic. The material of the separating elements 64 can be an absorber material for absorbing electromagnetic energy from the incoming radar waves.

[0080] The radar sensor 10 in Figure 13 is similar to that in Figure 10, except that the cover element 50 and the separating elements 64 are made of different materials. For example, the cover element 50 is made of metal and the separating elements 64 are made of plastic. The material of the separating elements 64 can be an absorber material for absorbing electromagnetic energy from the incoming radar waves.

[0081] The radar sensor 10 in Figure 14 corresponds to that in Figure 11, except that the cover element 50 and the separating elements 64 are made of different materials. For example, the cover element 50 is made of metal and the separating elements 64 are made of plastic. The material of the separating elements 64 can be an absorber material for absorbing electromagnetic energy from the incoming radar waves.

[0082] The radar sensor 10 in Figure 15 includes the retaining element 18 for mechanically attaching the antenna element 12 to the carrier element 30, which is designed as a circuit board 24. The retaining element 18 is attached laterally to the antenna element 12 as a hold-down device.

[0083] The retaining element 18 has destructive means 34 for destructive interference of reflected radar waves R' arriving at the retaining element 18 and reflected radar waves R" arriving at the antenna surface 14. The destructive means 34 are formed by at least a distance 36 between a region surface 38 of the retaining element 18 facing the antenna surface 14 and the antenna surface 14. The distance 36 is, in particular, a multiple of 2 / 4 and can thus be used in the event of interference of the radar waves R' arriving at the region surface 38 and R''. 417702

[0084] - 12 -

[0085] Antenna surface 14 incoming reflected radar waves R', R" cause cancellation of the incoming reflected radar waves.

Claims

R. 417702 - 13 - Patent claims 1. Radar sensor (10) comprising an antenna element (12) with at least one antenna opening (16) arranged on an ambient antenna surface (14) for transmitting and / or receiving radar waves (R) and a support element (30), characterized by the fact that a retaining element (18) is arranged which mechanically fastens the antenna element (12) to the support element (30), wherein the retaining element (18) has destructive means (34) for destructive interference of incoming reflected radar waves (R', R“, S', S“).

2. Radar sensor (10) according to claim 1, characterized in that the retaining element (18) has at least one clearance (22) which does not cover the antenna surface (14) and the area of ​​the antenna surface (14) of the at least one clearance (22) and the area of ​​the antenna surface (14) covered by the retaining element (18) are aligned with each other.

3. Radar sensor (10) according to claim 1 or 2, characterized in that the retaining element (18) has recesses (54) spaced apart from each other in at least one lateral direction (44).

4. Radar sensor (10) according to one of the preceding claims, characterized in that the destructive means (34) are formed by at least one dimension of the retaining element (18).

5. Radar sensor (10) according to claim 4, characterized in that the dimension of the retaining element (18) allows for a height difference (42) of at least R. 417702 - 14 - a recess (40) in one of the area surfaces (38) of the retaining element (18) facing away from the antenna surface (14).

6. Radar sensor (10) according to one of the preceding claims, characterized in that the destructive means (34) are formed by a distance (36) between a region surface (38) of the retaining element (18) facing away from the antenna surface (14) and the antenna surface (14).

7. Radar sensor (10) according to one of the preceding claims, characterized in that the destructive means (34) are formed by a retaining element material which causes a time-of-flight difference of the radar waves (R') passing in the retaining element (18) compared to the radar waves (R") passing outside the retaining element (18).

8. Radar sensor (10) according to one of the preceding claims, characterized in that the retaining element (18) has a surface structure (58) that promotes the scattering (56) of incident radar waves.

9. Radar sensor (10) according to one of the preceding claims, characterized in that the antenna element (12) is a waveguide antenna (28) with a waveguide structure (26) connected to the antenna opening (16) for transmitting the radar waves (R).

10. Radar sensor (10) according to one of the preceding claims, characterized in that the carrier element (30) is designed as a circuit board (24) for generating and coupling the radar waves (R) into the antenna element (12) and / or for receiving and processing the radar waves from the antenna element (12) or as a protective cover (32).

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