Waveguide antenna, radar sensor and vehicle

Abstract

The invention relates to a waveguide antenna (1), in particular for a radar sensor (20), comprising a radome (2), a waveguide (3), wherein the waveguide (3) is at least partly formed by a recess in the radome (2), which recess has a metallisation (4) at least in some parts, and at least one beam element (5a, 5b, 5c) is provided which is arranged within the radome (2) and extends from the waveguide (3), wherein the beam element (5a, 5b, 5c) comprises a non-metallised end face (11a, 11b, 11c).

Description

[0001] Waveguide antenna, radar sensor and vehicle

[0002] The present invention relates to a waveguide antenna for a radar sensor, a radar sensor with a waveguide antenna according to the invention for a vehicle and a vehicle which has a radar sensor according to the invention.

[0003] Technological background

[0004] Modern means of transport such as cars or motorcycles are increasingly being equipped with driver assistance systems that use sensor systems to detect the surroundings, recognize traffic situations, and assist the driver, e.g., by braking or steering intervention or by issuing a visual or acoustic warning. Radar sensors, lidar sensors, camera sensors, or similar sensor systems are regularly used for environmental detection. Conclusions about the surroundings can then be drawn from the data acquired by the sensors. Environmental detection using radar sensors is based on the emission of bundled electromagnetic waves, their reflection, e.g., by other road users, obstacles on the roadway, or the buildings along the edge of the road, and their reception. The detection of pedestrians is often carried out using camera sensors, but radar sensors are also increasingly being used for this purpose.

[0005] The radar sensors are also used in fusion with sensors using other technologies, such as camera or lidar sensors. Radar sensors have the advantage, among other things, that they work reliably even in bad weather conditions and can measure not only the distance between objects but also their radial relative velocity using the Doppler effect. The transmission frequencies used are generally 24 GHz, 77 GHz and 79 GHz. Due to the increasing functional scope of such systems, the requirements are constantly increasing, particularly with regard to the maximum detection range. In addition to environmental detection of motor vehicles for systems of the type described above, the focus is now also on interior monitoring of motor vehicles, e.g. to detect which seats are occupied; frequencies in the 60 GHz range, for example, are used for this.

[0006] Generic radar sensors can use waveguide antennas to transmit and receive radar beams. These antennas consist of one or more layers as individual components. The layers can be made of a plastic material with a metallized exterior. The waveguides are sealed within the antenna layers or with the circuit board, which carries, for example, the radar sensor's power electronics. Radomes are then used to seal the sensors above the antenna. In particular, the radome can cause additional losses in radar performance. A critical dimension here is the distance between the radome and the antenna surface – this distance must be precisely maintained to ensure the radome's influence on the overall system is as minimal as possible.However, this additional component results in greater costs and manufacturing effort. There is therefore a particular need to improve the interaction between radar antenna and radome so that the losses in radar performance, which have a negative impact on the antenna gain, are reduced. Antenna gain usually refers to the directivity and efficiency of an antenna, whereby this indicates the ratio of the radiated power density (in the main direction) emitted or received by an antenna and that of an idealized, lossless reference antenna with the same antenna feed power, e.g., an antenna gain of 0 dB. The antenna gain (in dB) can be specified as a function of the angle at which the radar radiation is emitted or received.

[0007] Printed state of the art

[0008] EP 3 336 575 B1 discloses a radar sensor for a motor vehicle comprising a radome, a circuit board, and at least one antenna element. The antenna element comprises a dielectric resonator formed by a portion of the radome and a slot antenna for feeding straight, square dielectric resonators or antenna elements. The slot antenna is formed in the circuit board. In particular, the radar sensor can also comprise a plurality of antenna elements arranged in a so-called array along a line, thereby increasing the antenna gain and allowing the radiation pattern to be focused in the elevation direction. Furthermore, this configuration achieves high side lobe suppression in the elevation direction.

[0009] Object of the present invention

[0010] Based on the state of the art, the task of the present

[0011] The invention is to provide a generic radar sensor with which an improvement in radar performance can be achieved in a simple and cost-effective manner.

[0012] Solution to the task

[0013] The above object is achieved by the entire teaching of claim 1 and the subordinate claims. Advantageous embodiments of the invention are claimed in the subclaims.

[0014] According to the invention, the waveguide antenna, which is particularly suitable for a radar sensor that can be used in the field of driver assistance systems for environmental detection, comprises a radome, preferably made of plastic, and a waveguide. The waveguide is at least partially formed by a recess in the radome, which at least partially has a metallization. For example, the metallization can be produced by physical vapor deposition (PVD), sputter deposition, thermal evaporation, chemical vapor deposition (CVD), or plasma-enhanced chemical vapor deposition (PECVD), thermal spraying, electroplating (plastic electroplating), and / or the like.Furthermore, at least one radiator element, preferably two or more radiator elements, is provided, which is arranged within the radome and extends (in the radiation direction) from the waveguide, wherein the radiator element comprises a non-metallized end face so that radar beams can be transmitted and received. The radome can therefore be used as a type of lens in the area of ​​the individual radiators, which contributes to improving radar performance. Furthermore, significantly more precise directional characteristics can be formed than with a separate radome above an antenna with multiple radiator elements. By applying metallization in the radome, tolerance problems regarding the distance between the antenna and radome are overcome. Likewise, the radome no longer has to adhere to a specified dimension over a very large area, but only has to adhere to the specified dimensions in the area of ​​the individual radiators or radiator elements.

[0015] The waveguide antenna can be a slot antenna, a horn antenna, or an OEWG (center fed open ended waveguide) antenna.

[0016] The radiating element preferably has at least one non-metallized wall region and one metallized wall region. This structural feature is particularly well-suited for influencing the directional characteristics of the antenna and improving the antenna gain. The desired directional characteristics can be achieved by carefully selecting non-metallized wall regions and metallized wall regions within the individual beam or radiating element.

[0017] The radiator element can expediently have a cavity which is surrounded by non-metallized wall areas in a plane or an area in the direction of extension of the radiator element.

[0018] According to an advantageous embodiment of the waveguide antenna according to the invention, it is provided that the metallized wall regions engage or extend into the radiator element at least up to one third, in particular up to half, the height of the radiator element (in the direction of extension).

[0019] Furthermore, the radome can have one or more radiator projections arranged above the radiator element or elements in the radiation direction. The radiator elements can expediently have a corresponding profile of the radiator projection, so that several radiator projections (i.e., one radiator projection for each radiator element) are provided, or one radiator projection that encompasses or covers all radiator elements.

[0020] Conveniently, the radiator projection(s) can also have a wall arranged above the radiator element(s) in the radiation direction, wherein the radiator projection(s) has a thinner wall thickness in the region of the wall in order to define and / or improve the directional characteristic and / or directivity of the antenna. Advantageously, losses can be further reduced by designing the individual radiators with a thinner wall at the front.

[0021] Preferably, the waveguide is further formed by a circuit board that delimits the waveguide on at least one side of the recess. The circuit board can be, for example, a substrate, a plastic plate, a metal plate, an additional antenna layer, or a printed circuit board with electronic components arranged thereon (e.g., chips, lines, power electronics, semiconductor components, IC modules, transistors, and / or the like). In a practical manner, the circuit board can be mounted on the underside of the radome, or the radome can be attached to one side of the circuit board (e.g., soldered, glued, screwed, and / or the like), whereby the circuit board can project beyond the radome in dimensions, can be smaller, or, preferably, can be flush with it. This allows a practical design to be achieved in a particularly simple manner.In addition, the special design of the circuit board can improve the antenna effect of the waveguide, so that the antenna performance can be further improved by the special design of the circuit board.

[0022] Of course, the circuit board can also be made of metal or have a metallization.

[0023] Furthermore, the present invention comprises a radar sensor, in particular for object detection for a vehicle, with a high-frequency component for generating and / or receiving RF signals or radar signals and a waveguide antenna according to the invention for coupling and / or decoupling the RF signals or for transmitting and receiving radar beams or radar signals.

[0024] In addition, the present invention claims a motor vehicle or vehicle which has a radar sensor according to the invention.

[0025] Description of the invention based on exemplary embodiments

[0026] The invention is described in more detail below using practical examples. They show:

[0027] Fig. 1 is a simplified schematic representation of an embodiment of a waveguide antenna according to the invention (viewed towards the predominantly metallized side of the waveguide antenna);

[0028] Fig. 2 is a simplified schematic representation of a further embodiment of the waveguide antenna according to the invention (viewed towards the non-predominantly metallized side of the waveguide antenna);

[0029] Fig. 3 shows a simplified schematic representation of a further embodiment of the waveguide antenna according to the invention (viewed toward the partially metallized side of the waveguide antenna); Fig. 4 shows a simplified schematic representation of a further embodiment of the waveguide antenna according to the invention (viewed toward the predominantly non-metallized side of the waveguide antenna);

[0030] Fig. 5 is a simplified schematic representation of the waveguide antenna from Fig. 4 with the printed circuit board mounted (looking at the non-metallized side of the waveguide antenna);

[0031] Fig. 6 is a simplified schematic representation of an enlarged section of a radiator element from Fig. 3;

[0032] Fig. 7A is a simplified schematic exploded view of an embodiment of the waveguide antenna according to the invention with chamfers with internal radiator elements and metallization;

[0033] Fig. 7B is a simplified schematic exploded view of the design of the waveguide antenna according to the invention from Fig. 7A with metallization shown separately;

[0034] Fig. 8A is a simplified schematic representation of an embodiment of a radiating element of a waveguide antenna according to the invention;

[0035] Fig. 8B is a simplified schematic representation of a further embodiment of a radiating element of a waveguide antenna according to the invention;

[0036] Fig. 9 is a simplified representation of an embodiment of a vehicle according to the invention;

[0037] Fig. 10 is a simplified representation of the antenna gain resulting in elevation of a waveguide antenna according to the invention according to Fig. 1 [frequency 76.5 GHz; 0 = 90°], and

[0038] Fig. 11 is a simplified representation of the antenna gain in azimuth of a waveguide antenna according to the invention as shown in Fig. 1 [frequency 76.5 GHz; <P = 0°]. Ein grundlegender Aspekt der Erfindung ist, dass das im Stand der Technik eigentlich flach ausgebildete Radom eines Radarsensors eine zweckmäßige 3D-Strukur erhält, wobei ein Teil der 3D Struktur bzw. eine Ausnehmung im Radom den Holleiter bildet, der nach unten bzw. zu der nicht abstrahlenden Seite hin geöffnet ist. Dieser geöffnete Bereich kann dann mit einer weiteren Schicht (Kunststoff, Substrat, Metall oder dergleichen) oder direkt mit einer Leiterplatte geschlossen werden. Am anderen Ende des Hohlleiters im Radom sind Antennenstrukturen, wie Einzelstrahler bzw. Strahlerelemente bzw. Schlitzstrahler im Hohlleiter oder auch Hornantennen angebracht, die sich vom Hohlleiter aus erstrecken.At least the inside of the radome is metallized with the exception of the antenna openings, whereby the individual radiators / radiator elements radiate directly through the radome.

[0039] Fig. 1 shows a waveguide antenna 1 according to the invention with a radome 2 made of plastic (viewed towards the underside of the radome, i.e. the side opposite the radiation direction), wherein the radome 2 has a recess which forms a waveguide 3. The waveguide 3 is fed from the opening 3a. The waveguide 3 is further formed by closing it from below (i.e. the non-radiating side of the radar sensor), e.g. with a metal surface or a substrate, which can be, for example, a circuit board or another antenna layer (not shown in Fig. 1). Furthermore, the waveguide antenna 1 has a metallization 4 which is arranged on the entire underside of the radome 2. In addition, three non-metallized rectangular regions are arranged which extend from the waveguide 3 and form the slotted antennas, so-called "slotted waveguides", or three radiator elements 5a, 5b, 5c.However, the geometric shape of these radiating elements 5a, 5b, 5c can be configured depending on the desired directional characteristic of the antenna and can thus also have a different configuration. According to the invention, the internal metallization 4 of the radome 2 allows a portion of the radome 2 to be used as part of an antenna structure, the feed line of which can be formed and used by means of a waveguide.

[0040] Fig. 2 shows an embodiment of a waveguide antenna 1 according to the invention, viewed from above onto the radome 2, wherein the radome 2 has three radiator projections 6a, 6b, 6c arranged in the region of the underside radiator elements 5a, 5b, 5c. Conveniently, the raised slot opening of the three individual radiators or radiator elements 5a, 5b, 5c has a different radome thickness or wall thickness than that provided around the waveguide 3. This allows the directional characteristic of the waveguide antenna 1 to be shaped like a type of lens. Fig. 3 shows a further embodiment of a waveguide antenna 1 according to the invention (viewed from the underside), wherein the underside of the radome 2 is only partially metallized or has a metallization 4 only in the region of the waveguide 3. Furthermore, Fig.4 shows an embodiment of a waveguide antenna 1 according to the invention, in which the radiator elements 5a, 5b, 5c are arranged beneath a continuous radiator projection 6 of the radome 2. This embodiment has advantages with regard to the manufacturing method of the radome 2. In the same way as the radiator projections 6a, 6b, 6c, the radiator projection 6 in the region of the radiator elements 5a, 5b, 5c can also have a thinner or smaller wall thickness than is provided around the waveguide 3 (i.e., has a smaller wall thickness) in order to determine the directional characteristic and at the same time improve the antenna performance. Furthermore, FIG. 5 shows an embodiment of a waveguide antenna 1 according to the invention, in which the underside of the radome 2 is closed with a circuit board 7.The circuit board 7 can be a substrate, a plastic plate, a metal plate, an additional antenna layer or a printed circuit board with electronic components arranged thereon (e.g. chips, lines, power electronics, semiconductor components, IC, transistors or the like - not shown in Fig. 5 for the sake of clarity).

[0041] Fig. 6 shows an enlarged view of the radiator elements 5a, 5b from Fig. 3. The wall of the radiator elements 5a, 5b is only partially metallized and thus has a non-metallized wall region 8a, 8b and a metallized wall region 9a, 9b. This creates a cavity 10a, 10b or an air opening in the upper end of the radiator element 5a, 5b (i.e. the end of the radiator element 5a, 5b located at the front in the radiation direction), which is surrounded by a non-modernized wall (wall region 8a, 8b). By designing the radiator element 5a, 5b with such a cavity 10a, 10b at the end in the radiation direction (so to speak above the antenna or as an antenna termination), the antenna performance can be significantly improved. Likewise, the tolerances in the distance between the antenna and the radome can be optimized or compensated.

[0042] 7A and 7B show a further embodiment of a waveguide antenna 1 according to the invention, wherein the waveguide antenna 1 partially has chamfers on the edges of the radome 2, which are essentially due to the manufacturing process (e.g., because plastic parts can be manufactured using an injection molding process and chamfers are provided to make it easier to remove the injection-molded parts from the injection molding tool). Furthermore, the radiation direction of the waveguide antenna 1 is shown as an arrow in Figure 7A (accordingly, the radiator projection 6 is located on the upper side of the waveguide antenna 1). Fig. 7B shows, in a highly simplified form, the metallization 4 detached from the rest of the radome 2 for illustrative purposes, including the metallized wall regions 9a, 9b, 9c, which are preferably provided and at least partially extend or engage into the radiator elements 5a, 5b, 5c of the radome 2.In an exploded view, which is of course located within the radome 2, as shown in Fig. 7A. In Figs. 7A and 7B it can be seen that the metallization 4 is provided inside the radome 2 to form the waveguide 3. The individual radiators or radiator elements 5a, 5b, 5c are arranged inside the radiator projection 6 of the radome 2. These can be formed, for example, during the injection molding process or by subsequent processing (milling, laser, etc.) in the radome 2. The metallization 4 can be created on the radome 2 using various coating techniques during production, such as CVD (chemical vapor deposition) coating, electroplating, sputter deposition, thermal spraying or the like.

[0043] In practical terms, the inner walls of the radiator elements 5a, 5b, 5c can be left uncoated or only partially coated or metallized. Preferably, the inner walls of the radiator elements are only partially coated or metallized, so that a space or cavity 10a, 10b, 10c remains above the coating within the respective radiator element 5a, 5b, 5c, which is surrounded by uncoated walls or unmetallized wall regions 8a, 8b, 8c. Furthermore, the region of the wall of the radiator element 6 located above the radiator elements 5a, 5b, 5c can, contrary to the illustration in Fig. 7A and Fig. 7B, also be designed with much thinner walls than the remaining wall of the radiator projection 6.The partial metallization of the inner walls of the radiator elements 5a, 5b, 5c can be achieved, for example, by only partially metallizing the wall areas during the metallization step, or by first metallizing the interior of the radome 2, preferably completely, and then removing the metallization within the radiator elements 5a, 5b, 5c (for example, by milling, laser, or the like). During this processing, the last section or cavity 10a, 10b, 10c can also be created (in whole or in part) by laser or milling, so that the uppermost area of ​​the respective radiator element 5a, 5b, 5c is also produced with a non-metallized wall area 8a, 8b, 8c.

[0044] Fig. 8A shows a simplified representation of an embodiment of the radiator element 5a of a waveguide antenna according to the invention, wherein the radiation direction of the waveguide antenna is shown by the arrow (accordingly, in the radiation direction, the side on which the end face 11a is located is referred to as the radiation side or top side - furthermore, the radiator element extends from the waveguide 3 in the radiation direction). The radiator element 5a has an inner wall and is hollow. The inner wall is characterized in particular in that it has a non-metallized wall region 8a and a metallized wall region 9a. The non-metallized wall region 8a surrounds the cavity 10a in a plane or a region in the radiation direction or extension direction of the radiator element 5a (starting from the waveguide 3). Furthermore, the end face 11a of the individual radiator orRadiating element 5a is not metallized, so that the radar radiation can pass directly through the wall or the end face 11a. Of course, radar beams can be transmitted in the radiation direction and received from the radiation direction, depending on whether signals are to be transmitted or received. In order to achieve the desired directional characteristic of the antenna and to improve the radar transmission or radar reception (i.e. in particular to improve the antenna performance and the antenna gain), the wall 12 of the radiator projection 6 above the radiator element 5a can be designed with much thinner walls than the remaining wall of the radiator projection 6, as shown in Fig. 8A. Furthermore, Fig. 8B shows a further embodiment of the radiator element 5a of a waveguide antenna according to the invention, wherein the cavity 10a surrounded by the non-metallized wall 8a has a smaller (or possibly(also the same) size as the area surrounded by the metallized wall 9a. This can be achieved, for example, by milling. This design ensures that the metallization is not damaged if the cavity 10a is subsequently milled or if metallization that has reached wall 8a during production (e.g., if the interior of the radome 2 is initially completely metallized during production) is removed from the wall 8a.

[0045] Fig. 9 shows a vehicle 20 according to the invention with a control device 21 (ECU, Electronic Control Unit or ADCU, Assisted and Automated Driving Control Unit). The control device 21 can carry out sensor control, sensor data fusion, environment and / or object recognition, trajectory planning and / or vehicle control, in particular (semi-) autonomously. For vehicle control, the control device 21 can access various actuators (steering 22, engine 23, brake 24). Furthermore, the vehicle 20 has a radar sensor 25 according to the invention, a lidar sensor 26, a camera 27 and ultrasonic sensors 28a-28d for environment detection. The sensor data can advantageously be used for environment and object recognition, so that various assistance functions, such as emergency brake assist (EBA), distance control (ACC, Adaptive Cruise Control), lane keeping control ora lane keeping assistant (LKA, Lane Keep Assist) or the like can be implemented.

[0046] Furthermore, the assistance functions can also be carried out via the control device 21 or another control unit provided for this purpose.

[0047] Fig. 10 and Fig. 11 show the antenna gain in elevation and azimuth of the waveguide antenna 1 from Fig. 1 and Fig. 2.

[0048] In summary, the advantages of the invention are that by applying metallization to the radome, tolerance problems regarding the distance between the antenna and the radome can be overcome. Likewise, the radome no longer has to adhere to a predetermined dimension over a very large area, but only has to adhere to the specified dimensions in the area of ​​the individual radiators or radiator elements. The radome in the area of ​​the individual radiators can also be used as a type of lens. This allows much more precise directional characteristics to be formed than with a separate radome over an antenna with multiple radiator elements. The radome can also advantageously be made thinner where the individual radiators are, which can further reduce losses. The invention can also advantageously be used for all radar sensors in the area of ​​Car-2-X orCar-to-car communication for higher frequencies and in all radio systems that use waveguide antennas.

[0049] LIST OF REFERENCE SYMBOLS

[0050] 1 waveguide antenna

[0051] 2 Radome

[0052] 3 waveguides

[0053] 3a Opening

[0054] 4 Metallization

[0055] 5a, 5b, 5c Radiator element

[0056] 6 spotlight projection

[0057] 6a, 6b, 6c spotlight projection

[0058] 7 circuit board

[0059] 8a, 8b, 8c non-metallized wall area

[0060] 9a, 9b, 9c metallized wall area

[0061] 10a, 10b, 10c Cavity 11a, 11b, 11c Front side 12 Wall

[0062] 20 vehicles

[0063] 21 Control device

[0064] 22 Steering

[0065] 23 Engine

[0066] 24 Brake

[0067] 25 Radar sensor

[0068] 26 Lidar sensor

[0069] 27 Camera

[0070] 28a, 28b, 28c, 28d Ultrasonic sensor

Claims

PATENT CLAIMS 1. Waveguide antenna (1), in particular for a radar sensor (20), comprising a radome (2), a waveguide (3), wherein the waveguide (3) is at least partially formed by a recess in the radome (2) which at least partially has a metallization (4), and at least one radiator element (5a, 5b, 5c) is provided which is arranged within the radome (2) and extends from the waveguide (3), wherein the radiator element (5a, 5b, 5c) comprises a non-metallized end face (11a, 11b, 11c).

2. Waveguide antenna (1) according to claim 1, characterized in that the waveguide antenna (1) is a slot antenna or a horn antenna or an OEWG antenna.

3. Waveguide antenna (1) according to claim 1 or 2, characterized in that the radiating element (5a, 5b, 5c) has at least one non-metallized wall region (8a, 8b, 8c) and one metallized wall region (9a, 9b, 9c).

4. Waveguide antenna (1) according to claim 3, characterized in that the radiating element (5a, 5b, 5c) has a cavity (10a, 10b, 10c) which is surrounded in a plane by non-metallized wall regions (8a, 8b, 8c).

5. Waveguide antenna (1) according to one of the preceding claims, characterized in that the metallized wall regions (9a, 9b, 9c) extend into the radiating element (5a, 5b, 5c) at least up to one third, in particular up to half, of the height of the latter.

6. Waveguide antenna (1) according to one of the preceding claims, characterized in that the radome (2) has one or more radiator projections (6a, 6b, 6c) which are arranged above the radiator element or elements (5a, 5b, 5c) in the radiation direction.

7. Waveguide antenna (1) according to claim 6, characterized in that the radiator projection (6) or the radiator projections (6a, 6b, 6c) have a Wall (12) which is arranged above the radiator element or the radiator elements (5a, 5b, 5c) in the radiation direction, wherein the radiator projection (6) or the radiator projections (6a, 6b, 6c) have a smaller wall thickness in the region of the wall (12).

8. Waveguide antenna (1) according to one of the preceding claims, characterized in that the waveguide (3) is further formed by a circuit board that delimits the waveguide (3) on at least one side of the recess.

9. Radar sensor (25), in particular for object detection for a vehicle (20), comprising a waveguide antenna (1) according to one of the preceding claims.

10. Vehicle (20) comprising a radar sensor (25) according to claim 9.

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