Radar sensor

Abstract

The radar sensor includes a layer including at least one active area and at least one passive area. The active area includes a plurality of antenna elements configured to transmit and receive radar waves, and the passive area is free of antenna elements. A respective dual-purpose structure is associated with each antenna element of the active area, wherein each dual-purpose structure is configured to isolate the associated antenna element from the other antenna elements for transmitted and received radar waves. At the same time, each dual-purpose structure is configured to suppress and redirect reflections of incident radar waves.

Description

Technical Field

[0001] The present disclosure relates to a radar sensor, which may be an automotive radar sensor mounted on a vehicle. Background Art

[0002] The internal components of an automotive radar sensor are typically mounted in a sensor housing, with a radome placed on top of it. The housing and radome encapsulate and protect the internal sensor components from environmental factors such as dust, moisture, corrosion, rust, and mechanical damage. For aerodynamic and aesthetic reasons, automotive radar sensors are often integrated into or hidden behind other vehicle components, i.e., behind the vehicle's exterior. Such vehicle components can include bumpers, dashboards, and vehicle emblems.

[0003] For example, if another vehicle component is placed in front of the antenna of an automotive radar sensor, the performance of the radar sensor may be degraded relative to its ideal performance. This may be due to the fact that the placement of the radar sensor behind the vehicle component may cause interference and undesirable effects, including radome insertion and transmission loss, boresight error, antenna mainlobe ripple, beamwidth and field of view of the radar sensor are reduced, sidelobe level increases, depolarization effects, etc. Therefore, the design and integration of the radome is a critical and challenging task in automotive radar technology.

[0004] Even if the radar sensor's radome is properly designed and integrated into the vehicle, most of the aforementioned interference effects may still remain, for example due to destructive interference caused by specular multi-reflection between metallic planar surfaces of the radar sensor and vehicle components. Such metallic surfaces can have a high reflectivity for radar waves and can be present within the radar sensor at the antenna plate and / or the top surface of the radome, as well as at other vehicle components, such as the vehicle's bumper or dashboard.

[0005] If metal waveguide antenna technology is used in radar sensors, such as air waveguide (AWG), ridge gap waveguide (RGW), or slotted waveguide (GGW) antennas, reflections between the radar sensor's metallic surfaces must also be considered. Metal waveguide antenna technology is often compromised by its significant structural radar cross section (RCS) due to the highly reflective metallic planar surfaces present in such radar sensors.

[0006] To overcome the interference effects described above, known radar sensors may include a highly dissipative dielectric material as an absorber layer, for example, on top of the antenna plate. Such a material can achieve good isolation between antenna elements and effectively absorb surface waves and multiple bounce reflections. However, the use of such absorbers can increase the cost of the radar sensor.

[0007] Therefore, it is desirable to have a radar sensor that mitigates the interfering effects of the radar sensor when it is mounted behind or adjacent to another component in a vehicle. Summary of the Invention

[0008] The present disclosure provides a radar sensor and a vehicle according to the independent claims. Embodiments are given in the dependent claims, the description and the drawings.

[0009] In one aspect, the present disclosure relates to a radar sensor comprising a layer including at least one active region and at least one passive region. The active region includes a plurality of antenna elements configured to transmit and receive radar waves, and the passive region is devoid of antenna elements. A respective dual-purpose structure is associated with each antenna element in the active region, wherein each dual-purpose structure is configured to isolate the associated antenna element from the other antenna elements with respect to transmitted and received radar waves. Simultaneously, each dual-purpose structure is configured to suppress and deflect reflections of incident radar waves, i.e., reflections that reach the dual-purpose structure.

[0010] The radar sensor may include various layers, including, for example, a layer or board for electronic components such as an MMIC (monolithic microwave integrated circuit), a layer forming a bottom cover for the antenna, a layer forming a top cover for the antenna, and a layer forming a radome. Within the layer forming the top cover for the antenna, a corresponding dual-purpose structure associated with one of the antenna elements may be arranged, for example, on both sides of the corresponding antenna element.

[0011] Dual-purpose structures can include elements that prevent surface waves from propagating through the corresponding structure. By properly aligning the structures between antenna elements, the dual-purpose structures can isolate the associated antenna element from the other antenna element with respect to the propagation of radar waves therebetween. Consequently, interference effects between antenna elements can be reduced or avoided.

[0012] At the same time, the elements of the dual-purpose structure are capable of suppressing and deflecting reflections of incoming radar waves, which can be generated, for example, by a multi-bounce effect. Incoming radar waves can be suppressed by deflecting these radar waves and / or by canceling out back-reflected radar waves due to destructive interference (which can also be referred to as "180° out-of-phase cancellation"). For example, radar waves reaching the dual-purpose structure can be deflected outside the spatial region corresponding to the field of view of the radar sensor, and these radar waves can also be suppressed by destructive interference.

[0013] In this way, the dual-purpose structure associated with the respective antenna element reduces the structural radar cross section in the boresight direction. In addition, the radar sensor does not require different expensive materials, such as for absorbers, and thus has a highly cost-effective design.

[0014] In summary, the dual-purpose structure performs the dual functions of isolating the antenna elements from one another and suppressing unwanted radar waves through deflection and / or cancellation via destructive interference. Consequently, the dual-purpose structure reduces interference effects on radar sensor performance. This improves the radar sensor's angle-finding performance, and can improve both azimuth and elevation coverage. This also applies if the radar sensor operates at different frequencies, such as within the entire 76 to 81 GHz bandwidth currently used in automotive radar sensors, as well as for frequencies exceeding 100 GHz, such as the frequency band around 120 GHz associated with advanced automotive radar sensors.

[0015] According to an embodiment, each dual-purpose structure may include a corresponding set of corrugations, and each corrugation may include protrusions and depressions. Each set of corrugations may include at least one angled corrugation, which may include at least one portion extending in a direction different from the predefined alignment direction of the associated antenna element.

[0016] Because each set of corrugations can include at least one angled corrugation, specular reflections can be reduced and the concentration of reflected energy at the boresight can be lowered. Furthermore, a corresponding set of corrugations can be arranged on both sides of a corresponding antenna element. In this way, the corrugations can form an air waveguide that isolates the corresponding antenna element from other antenna elements within the active area.

[0017] According to another embodiment, a corresponding set of corrugations can be at least partially covered by a dielectric layer. For example, a material with a dielectric constant greater than that of air can be positioned atop the corrugations. This allows the operating wavelength of radar waves to be smaller within the dielectric layer compared to the "free space" wavelength in air. Consequently, the depth between protrusions and depressions, as well as the distance between adjacent protrusions and depressions, can be reduced. This can lead to a more compact design for the entire radar sensor. Furthermore, a portion of the energy of the incident radar wave can be dissipated within the dielectric layer, potentially further reducing the radar cross section of the structure.

[0018] A pair of protrusions on the corrugations adjacent to the corresponding antenna elements can extend parallel to the predefined alignment direction of the corresponding antenna elements. In other words, the first two corrugations surrounding each antenna element can have protrusions that extend parallel to or in a straight line along the corresponding antenna elements. This allows for the isolation between the antenna elements in the active area to be achieved and maintained, while at the same time, the angled corrugations reduce the structural radar cross section of the entire layer.

[0019] At least one angled corrugation may include two side portions that are arranged at opposite angles greater than zero relative to a predefined alignment direction of the associated antenna element. One of the opposite angles may be positive, while the other of the opposite angles may be negative, relative to the predefined alignment direction of the associated antenna element. In other words, the side portions may be tilted to the same side relative to the alignment direction. The magnitude or absolute value of the opposite angles may be the same. The two side portions that are angled or tilted relative to the alignment direction of the antenna element may reduce the effect of specular multi-reflections on the radar signal detected by the radar sensor because the specular multi-reflections are deviated from the boresight direction by the angled or tilted side portions of the angled corrugation.

[0020] At least one of the angled corrugations may further include a central portion extending parallel to a predefined alignment direction of the associated antenna element, such that side portions may extend from respective ends of the central portion. Since the central portion extends along the associated antenna element, the corresponding antenna element may be appropriately isolated from one or more adjacent antenna elements. However, the side portions may alternatively be directly connected to one another without a central portion therebetween.

[0021] Within each side portion of at least one angled corrugation, corresponding protrusions and corresponding depressions may extend parallel to one another. More than one angled corrugation having such parallel protrusions and depressions may be arranged adjacent to one another, and all groups of corrugations may include such angled corrugations having such parallel protrusions and depressions. The protrusions and depressions within the side portions of the angled corrugations may be provided with a consistent tilt angle. Reflections from the outer edges of the corrugations may be directly deflected due to the consistent tilt. Furthermore, the structural radar cross section of the radar sensor may be reduced by destructive interference of radar waves between the angled corrugations.

[0022] Alternatively, within each side portion of at least one angled corrugation, the corresponding protrusions and corresponding depressions may be arranged at opposite angles. Similarly, one or more angled corrugations having such protrusions and depressions arranged at opposite angles may be adjacent to each other, and within each set of corrugations associated with a corresponding antenna element, such angled corrugations may have protrusions and depressions at opposite angles in their side portions. The opposite inclination angles of the corresponding protrusions and depressions may have the same magnitude or absolute value. Furthermore, due to the opposite inclination angles, the ends of the protrusions and depressions of the corresponding side portions may be connected to each other. Due to the oppositely angled protrusions and depressions within the side portions, the back reflections of radar waves can be canceled out through destructive interference.

[0023] Furthermore, the height of a protrusion relative to an adjacent depression (i.e., its maximum height when the angle of inclination between them is opposite) can be equal to one-quarter the wavelength of the radar wave emitted by the corresponding antenna element (i.e., the operating wavelength), with a height tolerance of one-sixteenth of the wavelength. This can achieve a phase cancellation effect for radar waves reaching the dual-purpose structure, reducing the structure's radar cross section. Furthermore, isolation requirements can be fully met or maintained along each antenna element.

[0024] A corresponding set of corrugations can also be a metallic antenna waveguide structure for an associated antenna element. Due to the metallic structure, expensive dielectric materials, for example as an absorption layer, may not be required. As a result, the layers of the radar sensor can be compatible with die-cast molding production techniques, which require low costs. However, as mentioned above, a dielectric layer can also be located on top of the corrugations in order to enhance the dissipation of incident radar waves. The group of corrugations can be considered as an air waveguide (AWG). However, the concept of angled corrugations can also be applied to radar sensors using ridge gap waveguide (RGW) technology and / or slot gap waveguide (GGW) technology.

[0025] According to another embodiment, the passive region can be provided with a diffraction grating surface. Due to this diffraction grating surface, the effects of specular multi-reflection reflections can be scattered outside the radar cone corresponding to the radar sensor's field of view. Furthermore, this diffraction grating surface can be tuned and optimized with respect to the radar wave's scattering pattern. As a result, the radar cross section of the structure in the boresight direction is reduced by deflecting higher diffraction modes outside the radar sensor's field of view.

[0026] A diffraction grating surface can include a surface profile in which the maxima and minima of the surface profile are periodically arranged. Such a surface profile can function as a diffraction grating and can therefore be considered a cross-diffraction grating surface. Consequently, the effects of specular multi-reflection can be scattered by the periodic profile into a radar cone corresponding to the radar sensor's field of view. Surface structures including periodic maxima and minima can be manufactured at low cost. Alternatively, the passive region can also include a flat surface that can be provided with an internal structure that functions as a diffraction grating.

[0027] The maximum and minimum values of the surface profile can have the same periodicity in two perpendicular directions. In other words, the surface profile can be symmetrical with respect to the two perpendicular directions. With such a surface profile, the scattering behavior of the passive region can be independent of the polarization of the radar wave. Therefore, such a passive region with the same periodicity in the maximum and minimum values in two perpendicular directions is suitable for dual-polarization radar sensors that use two different polarization modes.

[0028] Alternatively, the maxima and minima of the surface profile can have different periodicities for two directions perpendicular to each other. This configuration of the surface profile in the passive region may be relevant for automotive radars that have a wider field of view in azimuth than in elevation. For such a configuration, the periodicity along one axis can be increased, while the periodicity along the perpendicular axis can be decreased, compared to the symmetrical surface profile described above. Due to the different periodicities of the maxima and minima along the two perpendicular directions or axes, more diffraction modes can be excited in azimuth, where automotive radars can have a wider field of view, for example. This can lead to a better distribution of the scattered energy outside the radar cone or field of view, enabling enhanced suppression of specular reflections. Such a concept can be applicable to applications using single polarization.

[0029] The surface profile can be sinusoidal for two directions perpendicular to each other. This can be true for both symmetrical and asymmetrical surface profiles, ie for surface profiles with the same periodicity of maxima and minima in two perpendicular directions, and for surface profiles with different periodicities.

[0030] The periodicity of the maxima and minima of the surface profile can be adapted to at least two diffraction modes of the radar waves, such that the radar waves associated with the at least two diffraction modes can be scattered outside a predefined field of view of the radar sensor. The periodicity of the maxima and minima can relate to one or two dimensions or directions within the surface profile.

[0031] For example, if the surface profile is formed as a one-dimensional grating, that is, having a periodic structure along only one axis, then in addition to the zero-order specular reflection, there are also first-order positive and negative diffraction modes. Therefore, the periodicity of the one-dimensional grating can be configured so that radar waves of the two first-order diffraction modes are scattered out of the radar sensor's field of view. As a second example, if the surface profile is formed as a two-dimensional grating with a periodic structure along two perpendicular axes, there are four first-order diffraction modes. In this case, the periodicity of the two-dimensional grating can be configured in two directions so that radar waves of the four first-order diffraction modes are scattered out of the radar sensor's field of view.

[0032] If the surface profile is sinusoidal in two directions, the periodicity can be represented by the frequency of the sine or cosine curves of the surface that define the surface profile in the corresponding perpendicular direction. Therefore, by adjusting the periodicity of the maxima and minima within the surface profile accordingly, a desired number of diffraction patterns of radar waves can be scattered out of the field of view of the radar sensor. In detail, the diffraction angle of the corresponding diffraction pattern can be directly influenced by the corresponding periodicity along at least one direction. Therefore, the effect of the cross-grating profile on the energy of the incident wave and the effect on the mitigation of the specular multi-rebound reflection effect can be controlled and optimized. In addition, the distance between the maximum and minimum values (i.e., the height of the surface profile) can determine or define the power or energy distribution on different diffraction patterns.

[0033] According to another embodiment, at least one group of corrugations in the active area may include at least one angled corrugation, and for the at least one angled corrugation, the protrusions and depressions of the corresponding side portions of the angled corrugation may be arranged at opposite angles, and at the same time, the inactive area may be provided with a surface profile, wherein the maximum and minimum values of the surface profile may have the same periodicity for two directions perpendicular to each other.

[0034] Alternatively, at least one set of corrugations in the active area may include at least one angled corrugation, wherein the protrusions and depressions of corresponding side portions of the angled corrugation extend parallel to each other, and at the same time, the inactive area may be provided with a surface profile, wherein the maximum and minimum values of the surface profile may have different periodicities for two directions perpendicular to each other.

[0035] With such a configuration, the active and passive areas can synergistically contribute to mitigating specular multi-reflection effects, for example, between the antenna plate or layer and the radar sensor's radome, and, if the radar sensor is mounted in a vehicle, between the radar sensor itself and other vehicle components, such as the dashboard or bumper. Due to this synergistic effect with respect to mitigating interfering effects, the structural radar cross section can be significantly reduced in the boresight direction of the radar sensor.

[0036] In another aspect, the present disclosure relates to a vehicle comprising a vehicle component and a radar sensor as described above arranged near the vehicle component. For example, the vehicle component may be a dashboard, a bumper, or a vehicle emblem. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Exemplary embodiments and functionality of the present disclosure are described herein in conjunction with the following drawings, which schematically illustrate:

[0038] Figure 1 It is a radar sensor installed in the vehicle.

[0039] Figure 2 Yes Figure 1 Exploded view of the radar sensor shown,

[0040] Figure 3 is as follows Figure 1 and 2 Details of the radar sensor shown,

[0041] Figure 4 is an embodiment of a radar sensor comprising corrugations in an active region of an antenna layer,

[0042] Figure 5 is another embodiment of a radar sensor comprising corrugations in the active region of the antenna layer,

[0043] Figure 6 is the ripple covered by the dielectric layer,

[0044] Figure 7 is another embodiment of a radar sensor comprising a sinusoidal surface profile in a passive region of an antenna layer,

[0045] Figure 8 is the configuration of the sinusoidal surface profile and its diffraction characteristics for radar waves, and

[0046] Figure 9 It is another configuration of the sinusoidal surface profile and its diffraction characteristics for radar waves. DETAILED DESCRIPTION

[0047] Figure 1 A schematically illustrates a radar sensor 100 mounted in a vehicle 110 behind a vehicle component 120, such as a bumper or dashboard of the vehicle 110. For aesthetic and aerodynamic reasons, automotive radar sensors, such as radar sensor 100, are typically located behind the exterior of the vehicle 110.

[0048] exist Figure 1 B shows an enlarged perspective view of radar sensor 100. Radar sensor 100 includes a housing 140, in which the various boards or layers of the radar sensor are mounted as internal components. These include a board 150 for electronic components (e.g., a monolithic microwave integrated circuit (MMIC)) and a board or layer 160 for an air waveguide (AWG) antenna. Additionally, radar sensor 100 includes a radome 170. Housing 140 and radome 170 enclose and protect the internal components (e.g., boards 150, 160 of radar sensor 100) from environmental factors (e.g., dust, moisture, corrosion, rust, and mechanical damage).

[0049] The surface of the vehicle component 120 and the surfaces of some plates or layers of the radar sensor 100 are formed as metal plane surfaces. Therefore, these surfaces have high reflectivity for the radar waves emitted by the sensor 100. Therefore, specular multi-reflection occurs, which is Figure 1 As shown by the arrows 130 in A and 1B, specular multi-bounce reflections 130 can occur between radar sensor 100 and vehicle component 120. Furthermore, specular multi-bounce reflections 130 can also occur between the planar metal surface of radome 170 and the layer or plate 160 containing the AWG antenna. Reflections 130 are accompanied by unwanted disruptive effects on the performance of radar sensor 100, such as radome insertion and transmission loss, boresight error, antenna mainlobe ripple, reduction in beamwidth and field of view of radar sensor 100, increased sidelobe levels, and depolarization effects.

[0050] Even if the radome 170 is properly designed and installed to minimize such unwanted interference effects, most of these interference effects may remain due to specular reflections. Therefore, the radar sensor 100 according to the present disclosure is configured to reduce such interference effects as much as possible.

[0051] Figure 2 An exploded view of radar sensor 100 is shown including housing 140, electronics board 150, two antenna boards 160, and radome 170. Antenna board 160 includes an AWG antenna bottom cover or bottom layer 162 and an AWG antenna top cover or top layer 164, which includes antenna element 312 and corrugation 314 described in detail below.

[0052] Figure 3A Shown is an enlarged view of AWG antenna top cover or top layer 164. Layer 164 includes an active region 310, where antenna or radiator elements 312 of all transmit and receive (Tx and Rx) antennas of radar sensor 100 are located, and a passive region 320, which is devoid of antenna or radiator elements 312.

[0053] On either side of each antenna element 12, a number of corrugations 314 are located within the active area 310. Thus, a corresponding set of corrugations 314 is associated with each antenna element 312 of the active area 310. The corresponding set of corrugations 314 is also represented as a dual-purpose structure 313, the two purposes of which will be explained in detail below.

[0054] exist Figure 3B In FIG. 1 , another embodiment of layer 164 is shown. This embodiment includes Figure 3A The same elements of the embodiment make Figure 3A Description of Figure 3Bis also valid. The only difference relates to the arrangement of active region 310, which includes two spatially separated portions. Thus, active region 310 is not necessarily a continuous region within layer 164, but may include distinct regions separated by a portion of inactive region 320, which may be located between the distinct regions of active region 310.

[0055] like Figure 3C As shown, each corrugation 314 of the structure 313 includes a protrusion 315 and a recess 316 extending along the alignment direction of the corresponding antenna element 312 .

[0056] The corrugations 314 prevent surface waves from propagating through the corresponding isolation structure 313 formed by the corrugations 314 disposed between a pair of antenna elements 312 (see also FIG. Figure 3C ) to provide cross isolation between adjacent antenna elements 312. Figure 3C As shown by arrows 317 in FIG, the corrugations 314 prevent the propagation of radar waves perpendicular to the direction in which the protrusions 315 and recesses 316 of the corrugations 314 extend. In contrast, the propagation of radar waves is unimpeded in the direction parallel to the direction in which the protrusions 315 and recesses 316 extend (i.e., parallel to the alignment direction of the antenna element 312). This is due to Figure 3C Indicated by arrow 318 in FIG.

[0057] In other words, if Figure 3C The structure 313 shown, including the corrugations 314, can be considered an electromagnetically soft surface in the direction indicated by arrow 317 extending perpendicular to the protrusions 315 and recesses 316, and can be considered an electromagnetically hard surface in the direction indicated by arrow 318 extending along the protrusions 315 and recesses 316. That is, the protrusions 314 serve as air wave guides (AWGs) for radar waves emitted by the antenna element 312.

[0058] To provide adequate isolation between antenna elements 312 by blocking surface wave propagation, an isolation structure 313 having at least three corrugations 314 is required for each operating wavelength. Furthermore, the height H of protrusions 315, or the depth of depressions 316, is equal to one-quarter of the operating wavelength of the radar wave, with a tolerance of approximately one-sixteenth of the operating wavelength for height H. Furthermore, the distance, or pitch P, between adjacent protrusions 315 is selected to be less than or equal to one-third of the operating wavelength.

[0059] In order to alleviate the above Figure 1 In the context of the interference effect of the mirror multi-reflection 130 described above, an embodiment of the radar sensor 100 is provided with Figure 4 and 5 3. Modified corrugations 400 are shown. That is, at least some of the corrugations 400 are modified relative to the straight corrugations 314 shown in FIG.

[0060] Figure 4 A shows a perspective view of a portion of layer 164, including an active region 310 and a portion of an inactive region 320. Within active region 310, isolation structures 313 are located at locations associated with respective antenna elements 312. That is, respective isolation structures 313 are disposed on both sides of each antenna element 312. In addition to straight corrugations 314 having straight protrusions extending parallel to respective antenna elements 312, the isolation structures also include corrugations 400 having two angled side portions 412, 414 in addition to a central portion 410.

[0061] Due to the angled side portions 412, 414 of the corrugations 400, the isolation structure 313 is able to deflect the incident radar waves and cancel the incident radar waves by destructive interference, as will be seen in FIG. Figure 4 D. In addition to isolating the corresponding associated antenna element 312 from the other antenna elements 312 of the radar sensor 312, the structure 313 is also configured to suppress and redirect reflections of incident radar waves due to the corrugations 314, 400. Therefore, the structure 313 including the corrugations 314, 400 is denoted as a dual-purpose structure 313. Furthermore, the corrugations 400 are denoted as angled corrugations 400 due to their angled side portions 412, 414.

[0062] Figure 4 B shows a side view of one of the angled corrugations 400, which includes a middle portion 410 extending parallel to the alignment direction 420 of the corresponding antenna element 312 (see also FIG. Figure 4 C) and angled or inclined side portions 412, 414 extending from respective ends of the middle portion 410. The direction in which the angled side portions 412, 414 of the corrugation 400 extend is indicated by 422, and the angle of inclination between the direction 422 of extension of the side portion 412 and the alignment direction 420 of the antenna element 312 is indicated by a double arrow 424.

[0063] Figure 4 C also shows a perspective view of another portion of layer 164 including a portion of the active region 310 and the inactive region 320, i.e., in the same manner as Figure 4 A in a similar manner. However, the antenna element 312 is Figure 4 Arranged side by side in the section shown in C. Figure 4 C also shows the alignment direction 420 of the corresponding antenna element 312, the extension direction 422 of the side portion 412, and the tilt angle 424.

[0064] The two side portions 412, 414 are arranged at opposite angles 424 relative to a predefined alignment direction 420 of the respective antenna element 312 associated with a respective set of corrugations 314, 400, which surround the antenna element 312 in a direction perpendicular to the alignment direction 420 of the antenna element 312. For the present embodiment, the tilt angle 424 is approximately 7 degrees. However, this value is merely an arbitrary choice related to the design of the active area 310. Larger or smaller tilt angles 424 may also be applied to provide similar technical effects. Thus, in Figure 4 B and 4C show a tilt angle 424 greater than 7 degrees.

[0065] like Figure 4 The angled corrugations 400 of the illustrated embodiment have a consistent inclination angle 424 for all side portions 412, 414. That is, the protrusions 315 and recesses 316 of the angled protrusions 400 extend parallel to each other over the entire length of the corresponding angled corrugations 400, as shown. Figure 4 This is most clearly shown in B.

[0066] The distance H between the top of the protrusion 315 and the bottom of the recess 316 is uniformly equal to one quarter of the operating wavelength of the radar wave emitted by the antenna element 312, so as to maintain the cross isolation function between the antenna elements 312, wherein the height H has a tolerance of approximately one sixteenth of the operating wavelength. The isolation function of the structure 313 is also provided by Figure 4 This is indicated by arrow 317 in D. In the direction of arrow 317 , the structure 313 is an electromagnetically soft surface, ie over the entire length of the corrugations 400 in the middle portion 410 and the side portions 412 , 414 .

[0067] In order to maintain the isolation function in a similar manner to the active area 310 comprising only straight corrugations 314 as shown in FIG3 , the protrusions 315 of the corrugations 314 adjacent to the respective antenna elements 312 on both sides (see Figure 4 A and Figure 4 C) remains unchanged, i.e., no angled side portions 412, 414 are provided. In other words, a straight corrugation 314 is directly adjacent to the corresponding antenna element 312, so that the protrusion 315 of the adjacent corrugation 314 of the corresponding antenna element 312 extends parallel to the antenna element 312 over its entire length.

[0068] exist Figure 4 In the lower part of D, a dual-purpose structure 313 is shown (see Figure 4 A) is a perspective view of the top portion of the embodiment. For the sake of clarity, the straight corrugations 314 have been omitted so that only three angled corrugations 400 are shown. In the upper portion, the same structure is shown in a more schematic and simplified manner.

[0069] Due to the angled side portions 412, 414 of the corrugations 314, specular multi-rebound reflections are directly deflected, resulting in a reduction in the structural radar cross section of layer 164. This is illustrated by waves 440 reflected at the respective angled side portions 412, 414 of the angled corrugations 400. Furthermore, due to destructive interference, out-of-phase cancellation occurs for the waves 440 reflected at the protrusions 315 and depressions 316 of each angled corrugation 400, respectively. This destructive interference also occurs for the wave 450 reflected at the center portion 410. In summary, due to the deflection at the side portions 412, 414 and due to destructive interference in all portions 410, 412, 414, the incident radar wave is suppressed by the angled corrugations 400 of the structure 313.

[0070] Further reduction of the radar cross section of the structure is achieved by the central region 430 (see Figure 4 C), where oppositely angled side portions 412, 414 of different groups of corrugations 400 face each other. For this embodiment, passive region 320 of layer 164 remains unchanged relative to the reference model of radar sensor 100, as shown in FIG3 . That is, passive region 320 comprises a flat and uniform surface.

[0071] exist Figure 5 , another embodiment of layer 164 of radar sensor 100 is shown. Figure 4 The illustrated embodiments provide a description of the Figure 5 The illustrated embodiment is also valid, so that the description of the corresponding features will not be repeated. Figure 5 A and 5C show respective perspective views of a portion of layer 164, while Figure 5 B shows a side view of the angled corrugations 400 according to this embodiment, and Figure 5 D shows a perspective view of structure 313 .

[0072] like Figure 5 The embodiment shown is similar to Figure 4 The embodiment shown differs in that within the structure 313, i.e. within the group of corrugations 314, 400 associated with some antenna elements 312, the angled corrugations 400 have side portions 412, 414 in which the protrusions 315 and recesses 316 are arranged at opposite inclination angles 424. Figure 5 As shown in the side view of FIG. 4B , the protrusions 315 and recesses 316 of the angled corrugations 400 have corresponding inclined portions 512 , 513 that are arranged at opposite angles of inclination relative to the alignment direction 420 of the antenna element 312 .

[0073] Since the protrusions 315 and recesses 316 have opposite inclination angles 424, the protrusions 315 and recesses 316 of these angled corrugations 400 are connected to each other at the respective ends of the corrugations 400 along the respective antenna elements 312. In the middle region 410 of the corrugations 400 having such opposite inclination angles of the protrusions 315 and recesses 316 in their side portions 412, 414, the height H of the protrusions relative to the recesses 316 is still equal to one quarter of the operating wavelength of the radar waves emitted by the antenna elements 312. This distance equal to one quarter of the wavelength maintains the isolation function of the corrugations 314 in the middle region 410. The height H has a tolerance of approximately one sixteenth of the wavelength. The isolation function is again provided by Figure 5 This is shown by arrow 317 in the middle portion 410 shown in D.

[0074] Due to these opposite inclination angles 424 of the inclined portions 512, 513, the back reflections of the incident radar waves are deflected into different directions, e.g. Figure 5 D is shown by waves 520 and 530. Figure 5 Waves reflected from the same deflection angles as shown in wave pairs 520, 530, and 540 in D are canceled out by destructive interference of radar waves. This is effective for both the central portion 410 and the side portions 412 and 414. For the side portions 412 and 414, the corresponding distance 515 between the inclined portion 512 of the protrusion 315 of one of the side portions 412 and 414 and the inclined portion 513 of the recess 316 of the opposite side portion 412 and 414 is also approximately one-quarter of the operating wavelength, with a tolerance of one-sixteenth of the wavelength. This facilitates destructive interference between wave pairs 520 and 530. In summary, the structural radar cross section of layer 164 is further reduced through deflection and destructive interference.

[0075] Furthermore, for this embodiment, the inclination angle 424 of the protrusions 315 and recesses 316, which are oppositely inclined relative to the alignment direction 420 of the antenna element 312, is again approximately 7 degrees. As mentioned above, this value is again an arbitrary choice related to the design of the active area 310, and larger or smaller inclination angles 424 may also be applied to provide similar technical effects. Therefore, for illustrative purposes, Figure 5 A tilt angle 424 greater than 7 degrees is shown.

[0076] According to Figure 6 In another embodiment shown, the dual-purpose structure 313 and the corresponding set of corrugations 314, 400 are at least partially covered by a dielectric layer 600. Figure 6 On the left side of FIG. 4 , three angled corrugations 400 are shown, which have uniformly inclined protrusions 315 and depressions 316, i.e., according to FIG. Figure 4 In contrast, in the embodiment shown Figure 6On the right side, three angled corrugations 400 are shown, which have oppositely inclined protrusions 315 and depressions 316, i.e., relative to the Figure 5 The alignment directions 420 of the antenna elements 312 of the illustrated embodiment are arranged at opposite angles.

[0077] Therefore, a material with a dielectric constant greater than that of air is positioned atop the corrugations. Consequently, the operating wavelength of radar waves is smaller within the dielectric layer compared to the "free space" wavelength in air. Consequently, the depth H ( FIG. 3 ) of the depressions 316 between protrusions 315 and the corresponding distance P between adjacent protrusions 315 and depressions 316 can be reduced compared to embodiments in which corrugations 314 , 400 are not covered by dielectric layer 600. This results in a more compact design for the entire radar sensor 100. Furthermore, a portion of the energy of the incident radar wave is dissipated within dielectric layer 600, further reducing the radar cross section of the structure.

[0078] Figure 7 、 8 9 show further embodiments of radar sensors 100 in which the passive region 320 of the layer 164 (see also FIG. 3 ) has a diffraction grating surface profile 700 , 800 , 900 , so that the scattering pattern of the radar waves at the passive region is optimized in a special manner. Figure 7 、 8 In the embodiment shown in FIG. 9 , the surfaces 700, 800, 900 of the passive region 320 are perpendicular to each other in two directions (i.e., along the direction shown in FIG. Figure 7 The length l shown x and l y ) is a sinusoidal curve. The sinusoidal surface profile 700 of the passive region 320 can be analytically described by the following equation:

[0079]

[0080] Where z represents the local height of the surface profile 700 relative to the planar surface (xy plane), h is the amplitude or height factor of the profile, and P x is the period length along the x-axis, and P y is the period length along the y-axis. Therefore, P x and P y Determine the periodicity or frequency along the sinusoidal profile in two directions perpendicular to each other.

[0081] This sinusoidal surface profile 700 acts as a crossed diffraction grating, deflecting radar waves reflected from, for example, a radome, dashboard, or bumper, outside the radar sensor's field of view over a wide angular range. Generally, a surface profile with a periodic structure in two perpendicular directions is suitable for achieving this technical effect of deflecting radar waves by diffraction. Therefore, surface profile 700 need not be sinusoidal. Instead, a regular or periodic structure of maxima 702 and minima 704 is sufficient for surface profile 700.

[0082] exist Figure 7 , radar cone 710 corresponds to the field of view of radar sensor 100. Incident wave 720, which may be caused by reflections at the radome, dashboard, or bumper, causes specular reflection 730 within the field of view or radar cone 710, i.e., the (0,0) order diffraction mode 730, while higher order diffraction modes 732 are deflected out of the radar cone or field of view 710 of the radar sensor due to their diffraction of the radar wave at surface profile 700. Therefore, the energy or intensity of specular reflection 730 is greatly reduced because the higher order diffraction modes 732 are scattered or deflected out of radar cone 710. Therefore, specular multi-reflection 130 (see Figure 1 ) is also greatly reduced by the surface profile 700 of the inactive region 320.

[0083] The sinusoidal surface profile 700, as described by equation (1) above, provides the ability to tune the scattering pattern of the diffraction pattern and optimize the diffraction pattern to be outside the radar cone or field of view of the radar sensor 100. Generally, such a scattering pattern of a structured metal surface can be described by the periodic reflectarray theorem, or the anomalous reflection of a diffraction grating structure can be described by the generalized Snell's law in the reflection mechanism.

[0084] When considering the analytical formula (1) provided above, there are three parameters that can optimize the scattering pattern of the surface profile 700. The amplitude or height factor h directly affects the power distribution on the different diffraction modes. The period length P along the x-axis and y-axis x and P y The number of possible diffraction modes and the diffraction angles along the x-axis and along the y-axis are defined, respectively.

[0085] For Figure 8 In the embodiment of the radar sensor 100 shown, the surface profile 800 of the passive region 320 is provided with the same periodicity or period length along the x-axis and the y-axis, namely P x =P y Therefore, the surface profile 800 can also be referred to as a symmetrical sinusoidal profile. Figure 8 and 9 In , the angle θ represents the azimuth angle, and the angle ψ represents the elevation angle relative to the boresight direction along the z-axis.

[0086] exist Figure 8 The respective intensities of the different diffraction modes are shown in FIG via respective polar coordinate representations, where the intensity of the specular reflection is represented by 820 and the respective intensity of the higher diffraction mode is represented by 830. As shown in FIG Figure 8 As can be appreciated in FIG, most of the incident wave intensity is transferred to the higher diffraction modes. Therefore, the intensity 820 of the specular reflection is greatly reduced compared to the incident intensity.

[0087] Due to the same periodicity P of the surface profile 800 along the x-axis and the y-axis x 、P y Surface profile 800 of passive region 320 has a scattering behavior that is independent of the polarization of the emitted radar wave. Therefore, surface profile 800, which is a symmetrical sinusoid with respect to a spatial period, is suitable for a dual-polarity radar sensor using two different polarization modes.

[0088] Since many automotive radar sensors have a wider field of view in azimuth than in elevation, Figure 9 Another embodiment of the radar sensor 100 shown includes a surface profile 900 of the passive region 320 having different periodicities along the x-axis and the y-axis. Figure 8 Equal periodicity of the two axes shown, periodicity or period length P y increases along the y-axis, while the periodicity or period length P x Decreases along the x-axis.

[0089] Sinusoidal surface profile 900 thus has an asymmetric design with respect to the periodicity of the maxima and minima in the x- and y-directions. This allows for the excitation of more diffraction modes in azimuth, resulting in an increase in the intensity of the higher diffraction modes scattering out of the radar cone or field of view of radar sensor 100. This can be seen by the polar coordinate representation of the intensity of the higher diffraction modes, respectively denoted by 930. Thus, as in the example Figure 8 The intensity of the specular reflection represented by 920 is even more suppressed than the intensity 820 shown. Figure 9 The illustrated asymmetric surface profile 900 is suitable for use with a radar sensor 100 that utilizes a single polarization mode.

[0090] To investigate the feasibility of the above concept, the top antenna cover or layer 164 has been simulated for different models over the entire relevant frequency band from 76 GHz to 81 GHz (see Figure 2 and the corresponding bistatic radar cross section (RCF) of 3). For this simulation, incident waves illuminated from boresight and purely horizontal polarization have been assumed as prerequisites.

[0091] Model 1 (M1) used as a reference model is, for example, Figure 3A3B and has straight ripples 314 only in the active region 310 and a flat profile in the inactive region 320. Model 2 (M2) Figure 8 and has a symmetrical sinusoidal surface profile 800 only in the passive region 320, but has only straight corrugations 314 and no angled corrugations 400 in the active region. Model 3 (M3) Figure 5 , and has corrugations 400 only in the active region 310, with protrusions 315 and depressions 316 at opposite tilt angles 424, but a flat passive region 320 without a diffraction grating surface. Model 4 (M4) is as follows Figure 5 and Figure 8 Thus, M4 has a symmetrical sinusoidal surface profile 800 in the passive region 320 (see Figure 8 ), and having a corrugation 400 with protrusions 315 and depressions 316 with opposite inclination angles 424 in the active area 310 (see Figure 5 ).

[0092] Model 5 (M5) has an asymmetric sinusoidal surface profile 900 only in the passive region 320 (see Figure 9 ), but has only straight corrugations 314 and no angled corrugations 400 in the active area 310. In contrast, Model 6 (M6) has corrugations 400 with a uniform tilt angle 424 only in the active area 310 (see Figure 4 ), but with a flat surface profile without any diffraction grating surface in the passive region 320. Finally, Model 7 (M7) is as follows Figure 9 and Figure 4 Thus, M7 has an asymmetric sinusoidal surface profile 900 in the passive region 320 (see Figure 9 ), and having angled corrugations 400 with a uniform tilt angle 424 in the active region 310 (see Figure 4 ).

[0093] The simulation results for different models M1 to M7 are summarized in the table below. As can be seen from the results for models M2, M3, M5, and M6, the embodiments with tilted corrugations 400 in the active region 310 or sinusoidal surface profiles 800 or 900 in the passive region 320 have already resulted in a significant reduction in RCS values. However, models M4 and M7, which have a sinusoidal surface profile in the passive region and tilted corrugations in the active region 310, have a significantly reduced structural radar cross-section ratio (RCSR ratio), i.e., an RCSR ratio of approximately 10 dB across the entire frequency band from 76 GHz to 81 GHz. It should be noted that model M4, which has a symmetrical sinusoidal surface profile 800 and oppositely tilted corrugations 400, and model M7, which has an asymmetrical sinusoidal surface profile 900 and uniformly tilted corrugations 400, show the best results.

[0094]

[0095] In addition, the influence of the instrument panel on the azimuth and elevation coverage has been simulated for the above-mentioned models M1 to M7. For the simulation, the radar sensor 100 comprising the models M1 to M7, respectively, has been combined with an instrument panel having a reflectivity of -14 dB and an elevation pitch of -4°. It has been demonstrated that the model M2 (see FIG. 1 ) having a symmetrical sinusoidal surface profile 800 in the passive region 320 has a Figure 8 ) has improved azimuth and elevation coverage, i.e., even without Figure 4 and Figure 5 Angled corrugations 400 are shown. In addition, corrugations 400 having a symmetrical sinusoidal surface profile 800 and protrusions 315 and depressions 316 with opposite inclination angles in the passive region 320 (see Figure 5 )'s Model M4 further improves the radar integration results of the relevant technologies provided by Model M1.

[0096] Thus, radar sensor 100 having angled corrugations 400 in active region 310 and / or one of sinusoidal surface profiles 800 , 900 in passive region 320 exhibits improved capabilities with respect to angle finding.

[0097] According to the present disclosure, a radar sensor may include a layer comprising at least one active region and at least one passive region, the active region including multiple antenna elements configured to transmit and receive radar waves, and the passive region being devoid of antenna elements. A respective dual-purpose structure is associated with each antenna element in the active region, wherein each dual-purpose structure may be configured to isolate the associated antenna element from the other antenna elements with respect to both transmitted and received radar waves. Furthermore, the dual-purpose isolation structure may be configured to suppress and redirect reflections of incident radar waves.

[0098] According to various embodiments, each deflection isolation structure may include a corresponding set of corrugations, each corrugation including a protrusion and a recess. Each set of corrugations may include at least one angled corrugation including at least one portion extending in a direction different from a predefined alignment direction of the associated antenna element.

[0099] According to various embodiments, a respective set of corrugations may be at least partially covered by a dielectric layer.

[0100] According to various embodiments, a pair of protrusions of the corrugations adjacent to the respective antenna element may extend parallel to the predefined alignment direction of the respective antenna element.

[0101] According to various embodiments, at least one angled corrugation may include two side portions, which may be arranged at opposite angles greater than zero with respect to a predefined alignment direction of an associated antenna element.

[0102] According to various embodiments, the respective protrusions and the respective recesses within each side portion of the at least one angled corrugation may extend parallel to each other.

[0103] According to various embodiments, the respective protrusions and the respective recesses within each side portion of the at least one angled corrugation may be arranged at opposite angles.

[0104] According to various embodiments, a respective set of corrugations may be a metallic antenna waveguide structure for an associated antenna element.

[0105] According to various embodiments, the passive region may be provided with a diffraction grating surface.

[0106] According to various embodiments, the diffraction grating surface may include a surface profile, wherein maxima and minima of the surface profile are periodically arranged.

[0107] According to various embodiments, the maximum and minimum values of the surface profile may have the same periodicity for two directions perpendicular to each other.

[0108] According to various embodiments, the maximum and minimum values of the surface profile may have different periodicities for two directions perpendicular to each other.

[0109] According to various embodiments, the surface profile may be sinusoidal for two directions perpendicular to each other.

[0110] According to various embodiments, the periodicity of the maxima and minima of the surface profile may be adapted to at least two diffraction modes of radar waves such that radar waves associated with the at least two diffraction modes may be scattered out of a predefined field of view of the radar sensor.

[0111] According to various embodiments, at least one group of corrugations in the active area may include at least one angled corrugation, for which the protrusions and recesses of corresponding side portions of the angled corrugation may be arranged at opposite angles, and the inactive area may be provided with a surface profile, wherein the maximum and minimum values of the surface profile may have the same periodicity for two directions perpendicular to each other.

[0112] According to various embodiments, at least one group of corrugations in the active area may include at least one angled corrugation, for which the protrusions and recesses of corresponding side portions of the angled corrugation extend parallel to each other, and the inactive area may be provided with a surface profile, wherein the maximum and minimum values of the surface profile may have different periodicities for two directions perpendicular to each other.

[0113] Furthermore, the vehicle may include a vehicle component and a radar sensor as described above may be arranged near the vehicle component.

[0114] Reference Signs List

[0115] 100 radar sensors

[0116] 110 vehicles

[0117] 120 Vehicle parts, such as dashboards or bumpers

[0118] 130 mirror multi-rebound reflection

[0119] 140 shell

[0120] 150 electronic board

[0121] 160 antenna layer

[0122] 162 antenna bottom cover

[0123] 164 antenna cover

[0124] 170 radome

[0125] 310 active area

[0126] 312 antenna elements

[0127] 313 dual-purpose structure

[0128] 314 straight corrugation

[0129] 315 protrusion

[0130] 316 Depression

[0131] 317 electromagnetic soft surface

[0132] 318 electromagnetic hard surface

[0133] 400° angled corrugations

[0134] 410 middle part

[0135] 412 side part

[0136] 414 side part

[0137] 420 Alignment direction of antenna elements

[0138] 422 The direction of extension of the angled corrugation

[0139] 424 tilt angle

[0140] 430 Region with oppositely inclined side portions

[0141] 440 Waves deflected at the sides

[0142] 450 deflects the wave in the middle

[0143] 512, 513 oppositely inclined parts

[0144] 520 Waves deflected at the sides

[0145] 530 Waves deflected at the sides

[0146] 540 Waves deflected in the middle

[0147] 600 dielectric layer

[0148] 700 Sinusoidal surface profile of the passive area

[0149] 710 Radar cone or field of view

[0150] 720 incident wave

[0151] 730 Specular reflection or zero-order diffraction pattern

[0152] 732 higher diffraction mode

[0153] 800 symmetrical sinusoidal profile

[0154] 820 Specular reflection intensity

[0155] 830 Intensity of higher diffraction modes

[0156] 900 asymmetrical sinusoidal profile

[0157] 920 Specular reflection intensity

[0158] 930 Intensity of higher diffraction modes

Claims

1. A radar sensor comprising: A layer (164) comprising at least one active region (310) including a plurality of antenna elements (312) configured to transmit and receive radar waves and at least one passive region (320) having no antenna elements (312), A respective dual-purpose structure (313) is associated with each antenna element (312) of the active area (310), each dual-purpose structure (313) being configured to isolate the associated antenna element (312) from other antenna elements (312) with respect to transmitted and received radar waves, and to suppress and redirect reflections of incident radar waves.

2. The radar sensor (100) according to claim 1, wherein Each dual-purpose structure (313) includes a corresponding set of corrugations (314, 400), each corrugation (314, 400) includes a protrusion (315) and a depression (316), and Each set of corrugations (314, 400) includes at least one angled corrugation (400) including at least one portion (412, 414, 512, 513) extending in a direction different from a predefined alignment direction (420) of an associated antenna element (312).

3. The radar sensor (100) according to claim 2, wherein The respective set of corrugations (314, 400) is at least partially covered by a dielectric layer (600).

4. The radar sensor (100) according to claim 2 , wherein A pair of protrusions (315) of the corrugation (314) adjacent to a corresponding antenna element (312) extends parallel to a predefined alignment direction (420) of the corresponding antenna element (312).

5. The radar sensor (100) according to any one of claims 2 to 4, wherein The at least one angled corrugation (400) includes two side portions (412, 414) arranged at opposite angles (424) greater than zero relative to the predefined alignment direction (420) of the associated antenna element (312).

6. The radar sensor (100) according to claim 5, wherein In each side portion (412, 414) of the at least one angled corrugation (400), a respective protrusion (315) and a respective recess (316) extend parallel to each other.

7. The radar sensor (100) according to claim 5, wherein Within each side portion (412, 414) of the at least one angled corrugation (400), a corresponding protrusion (315) and a corresponding recess (316) are arranged at opposite angles (424).

8. The radar sensor (100) according to any one of claims 1 to 7, wherein The passive region (320) is provided with a diffraction grating profile (700, 800, 900).

9. The radar sensor (100) according to claim 8, wherein The diffraction grating profile (700, 800, 900) comprises a surface profile (700, 800, 900), wherein The maximum values (702) and the minimum values (704) of the surface profile (700, 800, 900) are arranged periodically.

10. The radar sensor (100) according to claim 8 or 9, wherein The periodicity of the maxima (702) and the minima (704) of the surface profile (700, 800, 900) is adapted to at least two diffraction patterns (732) of radar waves, such that radar waves associated with the at least two diffraction patterns (732) are scattered out of a predefined field of view of the radar sensor (100).

11. The radar sensor (100) according to any one of claims 8 to 10, wherein The maximum value (702) and the minimum value (704) of the surface profile (800) have the same periodicity in two directions perpendicular to each other.

12. The radar sensor (100) according to any one of claims 8 to 10, wherein The maximum value (702) and the minimum value (704) of the surface profile (900) have different periodicities with respect to two directions perpendicular to each other.

13. The radar sensor (100) according to any one of claims 2 to 5 or 7, wherein In the active area (310), at least one set of corrugations (314, 400) includes at least one angled corrugation (400), for which the protrusions (315) and the recesses (316) of corresponding side portions (412, 414) of the angled corrugation (400) are arranged at opposite angles, and The passive region (320) is provided with a surface profile (800), wherein: The maximum value (702) and the minimum value (704) of the surface profile (800) have the same periodicity in two directions perpendicular to each other.

14. The radar sensor (100) according to any one of claims 2 to 6, wherein In the active area (310), at least one set of corrugations (314, 400) includes at least one angled corrugation (400), for which the protrusions (315) and the recesses (316) of corresponding side portions (412, 414) of the angled corrugation (400) extend parallel to each other, and The passive region (320) is provided with a surface profile (900), wherein: The maximum value (702) and the minimum value (704) of the surface profile (900) have different periodicities with respect to two directions perpendicular to each other.

15. A vehicle (110), comprising: a vehicle component (120), and The radar sensor (100) according to any one of claims 1 to 14, which is arranged near the vehicle component (120).

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