Radar sensor

Abstract

The invention relates to a radar sensor (10) comprising at least one antenna element (20-22, 25-27) and a radar converging lens (30); a focal point (40) of the radar converging lens (30) for radar radiation is at a predetermined focal length (FA) from a lens side (31) of the radar converging lens (30) facing the focal point (40). According to the invention, at least one antenna element (20-22, 25-27) is spatially arranged between the focal point (40) and a lens side (31) of the radar converging lens (30) facing the focal point (40).

Description

Technical Field

[0001] The present invention relates to a radar sensor comprising at least one antenna element and a radar converging lens, wherein the focal point of the radar converging lens is at a predetermined focal length from the lens side facing the focal point. Background Technology

[0002] Such radar sensors are generally known and are sold, for example, by Pepperl+Fuchs SE. Summary of the Invention

[0003] This invention is based on the purpose of detailing a radar sensor with particularly good transmission and reception characteristics.

[0004] According to the invention, this objective is achieved by a radar sensor having the features described in claim 1. Advantageous configurations of the radar sensor according to the invention are provided in the dependent claims.

[0005] Therefore, the present invention provides at least one antenna element spatially arranged between the focal point and the focal point-facing lens side of the radar converging lens.

[0006] The main advantage of the radar sensor according to the invention can be seen in the fact that a particularly advantageous shaping of the transmission and / or reception characteristics, hereinafter referred to as antenna directional characteristics, can be achieved by offsetting at least one antenna element relative to the focal point according to the invention. Specifically, compared with the conventional arrangement of antenna elements, i.e., compared with the arrangement in the focal region, a configuration of the main lobe of the antenna directional characteristics that is particularly spherically expanded can be achieved.

[0007] For example, depending on the offset of the antenna element relative to the focal point, it is possible to avoid the formation of side lobes next to the main lobe, or the merging of adjacent portions with the main lobe, such that at the interface between the main lobe and the corresponding adjacent portion, the antenna directivity does not have an inwardly pointing depression in the direction of the antenna element, or at most a plateau region. In other words, for example, it is possible to achieve, in this way, that the antenna directivity decreases continuously from its maximum value in the main lobe region in the direction of the adjacent portion and within the adjacent portion, that is, no intermediate region is formed at the interface in which the antenna directivity is less than the antenna directivity in the adjacent portion and less than the antenna directivity in the adjacent region of the main lobe.

[0008] It is considered advantageous if the distance between the focal point and at least one antenna element is at least 10% of the focal length.

[0009] It is particularly advantageous if the distance between at least one antenna element and the lens side of the radar converging lens facing the at least one antenna element is between 0.5 and 0.9 times the focal length, especially preferably between 0.65 and 0.85 times the focal length, and particularly between 0.7 and 0.8 times the focal length.

[0010] In a preferred configuration, the radar converging lens is concave on the lens side facing at least one antenna element and convex on the lens side facing away from at least one antenna element.

[0011] In another preferred configuration, the radar converging lens is planar on the lens side facing at least one antenna element and convex on the lens side facing away from at least one antenna element.

[0012] For radar operation, it is advantageous if the radar sensor has at least two antenna elements, with the first antenna element electrically connected to the radar transmitting device and the second antenna element electrically connected to the radar receiving device.

[0013] The distance between the focal point and the first antenna element is preferably at least 10% of the focal length, and the distance between the focal point and the second antenna element is also preferably at least 10% of the focal length.

[0014] In a later embodiment, it is advantageous if the distance between the first antenna element and the lens side of the radar converging lens facing the first antenna element is between 0.5 and 0.9 times the focal length, particularly preferably between 0.65 and 0.85 times the focal length, especially between 0.7 and 0.8 times the focal length, and the distance between the second antenna element and the lens side of the radar converging lens facing the second antenna element is between 0.5 and 0.9 times the focal length, particularly preferably between 0.65 and 0.85 times the focal length, especially between 0.7 and 0.8 times the focal length.

[0015] Regarding direction determination, it is considered advantageous if the radar receiver is additionally grounded to the third antenna element of the radar sensor and the radar receiver is configured to detect the direction of the received radar radiation by evaluating the received signals of the second and third antenna elements.

[0016] In a later embodiment, it is advantageous if the distance between the focal point and the third antenna element is at least 10% of the focal length.

[0017] The distance between the third antenna element and the lens side of the radar converging lens facing the third antenna element is preferably between 0.5 and 0.9 times the focal length, particularly preferably between 0.65 and 0.85 times the focal length, and especially between 0.7 and 0.8 times the focal length.

[0018] More than three antenna elements may also exist, i.e., a fourth and additional antenna elements. For the latter antenna elements, it is preferable that the antenna elements are spatially arranged between the focal point and the lens side of the radar converging lens facing the focal point. The distance between the focal point and the corresponding antenna element is preferably at least 10% of the focal length, or the distance between the corresponding antenna element and the lens side of the radar converging lens facing that antenna element is preferably between 0.5 and 0.9 times the focal length, particularly preferably between 0.65 and 0.85 times the focal length, and especially between 0.7 and 0.8 times the focal length.

[0019] For example, if there are seven antenna elements, three of which operate as transmitting antennas and four as receiving antennas, it is advantageous for radar sensor operation.

[0020] In terms of materials, it is considered advantageous if the radar converging lens is composed of a monolithic element made of Teflon or polycarbonate.

[0021] Antenna elements are preferably formed from individual free conductor trace elements (also known in industry terminology as conductor trace pads).

[0022] It is advantageous if the conductor trace components are mounted on the same printed circuit board.

[0023] The plane of the printed circuit board, at least in the area of ​​the conductor trace element, is preferably arranged perpendicular to the central axis of the radar lens.

[0024] The term "distance" between two objects should be understood in its conventional sense, that is, in each case, as the shortest distance between the respective objects. Since in the conventional configuration of radar sensors, antenna elements, especially those configured as planar conductor trace pads, and where the lens side of the radar converging lens facing the antenna element always has a spatial range, the term "distance" between the antenna element and the lens side facing the antenna element should therefore be understood in each case as always referring to the shortest distance between the respective antenna element and the lens side; and the term "distance" between the antenna element and the focal point should also be understood in each case as always referring to the shortest distance between the respective antenna element and the focal point. Attached Figure Description

[0025] The invention will now be explained in more detail based on exemplary embodiments; in this case, as an example: Figure 1 An exemplary embodiment of a radar sensor according to the present invention is shown, wherein an antenna element is arranged between the focal point and the radar converging lens. Figure 2A more detailed description is provided based on Figure 1 The directional characteristics of the antenna elements, Figure 3 The diagram illustrates the antenna directional values ​​relative to the transmission angle. Figure 1 The directional characteristics of the antenna elements, Figure 4 To illustrate the comparison, the following is shown: Figure 1 The directional characteristics of the antenna element when the element is positioned at the focal point. Figure 5 The directional characteristics of an exemplary embodiment of a radar sensor according to the present invention are shown, wherein two antenna elements are arranged between the focal point and the radar converging lens. Figure 6 To illustrate the comparison, the directional characteristics of a radar sensor with two antenna elements positioned at the focal point are shown. Figure 7 An exemplary embodiment of a radar sensor according to the present invention, equipped with three antenna elements, is shown arranged on a printed circuit board. Figure 8 The cross-sectional view shows the results according to Figure 7 The arrangement of antenna elements between the focal point and the radar converging lens in an exemplary embodiment.

[0026] In the accompanying drawings, for clarity, the same reference numerals are always used for the same or equivalent components. Detailed Implementation

[0027] Figure 1 The components of an exemplary embodiment of the radar sensor 10 according to the present invention are shown in cross-section.

[0028] This reveals antenna element 20 and radar converging lens 30, which are suitable for focusing radar radiation. According to... Figure 1 In an exemplary embodiment, the radar converging lens 30 is concave on the lens side 31 facing the antenna element 20 and convex on the lens side 32 facing away from the antenna element 20. Regarding low absorption of radar radiation, the radar converging lens 30 is preferably composed of a monolithic element made of Teflon or polycarbonate.

[0029] The focal point 40 of the radar converging lens 30 is separated from the lens side 31 facing the focal point 40 by a focal length FA.

[0030] Antenna element 20 is spatially arranged between focal point 40 and radar converging lens 30. In the case of a convex-concave radar converging lens 30, the distance A between antenna element 20 and radar converging lens 30 is preferably between 0.75 and 0.79 times the focal length FA, and in the case of a planar convex radar converging lens 30, it is preferably between 0.74 and 0.78 times the focal length FA, that is, the following are preferably true: In the case of a convex-concave radar converging lens 30, 0.75 FA <A<0.79 FA, and In the case of a planar convex radar converging lens 30, 0.74 FA <A<0.78 FA.

[0031] The focal length FA is preferably in the range of 22mm to 26mm in the case of a convex-concave radar converging lens 30, and preferably in the range of 16mm to 20mm in the case of a planar convex radar converging lens 30.

[0032] In the case of the convex-concave radar converging lens 30, the focal length FA is, for example, 24 mm, and the distance A between the antenna element 20 and the radar converging lens 30 is 18.496 mm, which is 0.7707 times the focal length FA, and is considered optimal.

[0033] In the case of a planar convex radar converging lens 30, the focal length FA is, for example, 18 mm, and the distance A between the antenna element 20 and the radar converging lens 30 is 13.6215 mm, which is 0.75675 times the focal length FA and is considered optimal.

[0034] Figure 2 An example illustrates the following: Figure 1 The antenna directional characteristics of the antenna element 20, i.e., its transmission and / or reception characteristics. It can be recognized that, due to the axial offset arrangement of the antenna element 20 in the direction of the radar converging lens 30, compared with the arrangement of the antenna element 20 at the focal point 40, the main beam lobe 50 exhibits a very spherically expanded configuration of the antenna directional characteristics.

[0035] This avoids the formation of side lobes directly next to the main beam lobe 50, because the adjacent portions 50a and 50b adjacent to the main beam lobe 50 merge with the main beam lobe 50, so that at the interface SS between the main beam lobe 50 and the corresponding adjacent portions 50a and 50b, the antenna directional characteristics do not have an inwardly pointing concave or contracted direction in the direction of the antenna element 20.

[0036] Figure 3 Antenna directional value R relative to the transmission angle The curves representing the antenna's directional characteristics are shown in the form of [symbol / form]. Figure 2 and Figure 3 The example demonstrates how to select the emission angle to achieve its value. =0 is at the maximum transmit and / or receive strength or maximum antenna directivity, that is, in the middle of the main beam lobe 50.

[0037] exist Figure 3 It is possible to recognize that for values ​​below zero The value, as... As the value increases, the antenna directional value R increases continuously, despite having a variable gradient rate, and for values ​​above zero... The value, as... As the value increases, the antenna directional value R continuously decreases, despite having a variable rate of decrease.

[0038] In the region of the interface SS between the main beam lobe 50 and the two directly adjacent portions 50a and 50b, the antenna directional characteristics relative to the emission angle... The curve has a plateau region where the antenna directional value R is relative to the transmission angle. It is relatively constant; however, there is no formation of local maximum or local minimum values, neither in the region of the main beam lobe 50 nor in the regions of the two directly adjacent adjacent parts 50a and 50b; there is only one maximum value, especially the absolute value in the middle region of the main beam lobe 50.

[0039] In other words, based on Figure 2 and Figure 3 In an exemplary embodiment, this achieves that, starting from the maximum value reached by the antenna directional value R in the region at the center of the main beam lobe 50, the antenna directional characteristics decrease uninterruptedly in the directions of adjacent portions 50a and 50b, and also within the adjacent portions 50a and 50b themselves, or remain most constant in these portions. Therefore, at the interface SS, no intermediate region is formed in which the antenna directional value R will be less than the antenna directional value R in the adjacent region.

[0040] To better understand, Figure 4 The formation of side lobes 51 and 52 is shown when antenna element 20 is positioned at the focal point 40 of radar converging lens 30. Figure 4 It is obvious that, with Figure 2Conversely, there is a clear separation between the side lobes 51 and 52, and no merging of the main beam lobe 50 with the adjacent portion occurs; the antenna directional characteristics exhibit a significant dip EB or contraction in the direction of the antenna element 20. These dip EBs can lead to situations where, depending on the sensitivity of the radar sensor 10, objects located at an angle between the main beam lobe 50 and one of the adjacent side lobes 51 or 52 are not identified in certain circumstances.

[0041] Figure 1 and Figure 2 An exemplary embodiment of the invention with only a single antenna element 20 is shown. It is advantageous if the radar sensor 10 has at least two antenna elements, wherein the first antenna element is electrically connected to the radar transmitting device and acts as a transmitting antenna element 21, and the second antenna element is electrically connected to the radar receiving device and acts as a receiving antenna element 22; Figure 5 Such an exemplary embodiment of the invention is illustrated in simplified diagrams.

[0042] exist Figure 5 It can be recognized that, given the antenna directional characteristics of the transmitting antenna element 21, adjacent portions 60a and 60b merge with the main beam lobe 60, and what is achieved is a spherically expanded antenna directional characteristic without a dip EB between the main beam lobe 60 and the adjacent portions 60a and 60b; this also applies to the main beam lobe 70 of the receiving antenna element 22 and its adjacent portions, which in Figure 5 It is hidden in the middle.

[0043] Furthermore, it can be recognized that, due to the spherical expansion shape of the antenna directional characteristics between the two main lobes 60 and 70, there is only a very small indentation EB, which makes the antenna directional characteristics of the radar sensor 10 as a whole actually constant, as seen in the main direction.

[0044] Figure 6 To compare, the antenna directional characteristics of two antenna elements 23 and 24 arranged in the region of focus 40 are shown. For clarity, only the two main lobes 80 and 90 are shown. It can be recognized that a significant dip EB appears between the maximum values ​​of the two main lobes 80 and 90, which is significantly larger than... Figure 5 Larger and deeper.

[0045] Figure 7 The illustration shows components of another exemplary embodiment of the invention, as well as a particularly preferred configuration and arrangement of the antenna elements. The illustration shows a printed circuit board 100 with three conductor trace elements, each conductor trace element forming an antenna element, in plan view.

[0046] One of the conductor trace elements forms a transmitting antenna element 25, which is connected to a radar transmitting device 110 arranged on the printed circuit board 100 via a conductor trace 101 of the printed circuit board 100.

[0047] Another of the conductor trace elements forms a first receiving antenna element 26, which is connected to a radar receiving device 120 arranged on the printed circuit board 100 via a conductor trace 102 of the printed circuit board 100.

[0048] The third antenna element 20 forms the second receiving antenna element 27, which is connected to the radar receiving device 120 arranged on the printed circuit board 100 via the conductor trace 103 of the printed circuit board 100.

[0049] The radar receiver is designed to detect the direction of received radar radiation by evaluating the received signals of the second antenna element 26 and the third antenna element 27, and in particular by evaluating the phase offset between the two received signals.

[0050] Figure 8 The cross-section shows the results according to Figure 7 The printed circuit board 100 is shown, and the radar converging lens 30 and its focal point 40 are also shown in cross-section. It can be appreciated that the plane E of the printed circuit board 100 is arranged perpendicular to the central axis M of the radar lens, and is also arranged between the focal point 40 and the radar converging lens 30.

[0051] The number of antenna elements can also be greater than three. For example, seven antenna elements can be present, arranged in each case between the focal point 40 and the lens side 31 of the radar converging lens 30 facing the focal point 40. The antenna elements are preferably formed from conductor trace elements of the same printed circuit board. For example, three of the antenna elements can operate as transmitting antenna elements, and the remaining four can operate as receiving antenna elements.

[0052] Finally, it should be mentioned that the features of all the above exemplary embodiments can be combined with each other as needed to further form additional exemplary embodiments of the present invention.

[0053] Furthermore, all features of the dependent claims can be individually combined with any other claim, specifically, either alone or in any combination with one or more other dependent claims, to further obtain additional exemplary embodiments.

[0054] List of reference numerals in the attached figures

[0055] 10 Radar Sensors

[0056] 20 antenna elements

[0057] 21 Transmitting antenna elements

[0058] 22 Receiving antenna elements

[0059] 23 Antenna Components

[0060] 24 Antenna Elements

[0061] 25 Transmitting antenna elements

[0062] 26 Receiving antenna elements

[0063] 27 Receiving antenna elements

[0064] 30 Radar converging lens

[0065] 31. Lens side

[0066] 32. Lens side

[0067] 40 Focus

[0068] 50 main beamlobes

[0069] 50a Adjacent part

[0070] 50b Adjacent part

[0071] 51 sidelobes

[0072] 52 side lobes

[0073] 60 main beam lobes

[0074] 60a Adjacent part

[0075] 60b Adjacent part

[0076] 70 main beam lobe

[0077] 80 main beam lobe

[0078] 90 main beam lobe

[0079] 100 Printed Circuit Boards

[0080] 101 Conductor Traces

[0081] 102 Conductor traces

[0082] 103 Conductor traces

[0083] 110 Radar Transmitting Devices

[0084] 120 Radar Receiver

[0085] A distance

[0086] E plane

[0087] EB depression

[0088] FA focal length

[0089] M central axis

[0090] R antenna direction value

[0091] SS Interface Launch angle

Claims

1. A radar sensor (10) comprising at least one antenna element (20-22, 25-27) and a radar converging lens (30), wherein the focal point (40) of the radar converging lens (30) for radar radiation is located at a predetermined focal length (FA) at a distance of 31 from the lens side (31) facing the focal point (40). Its features The at least one antenna element (20-22, 25-27) is spatially arranged between the focal point (40) and the lens side (31) of the radar converging lens (30) facing the focal point (40).

2. The radar sensor (10) according to claim 1. Its features The distance (A) between the focal point (40) and the at least one antenna element (20-22, 25-27) is at least 10% of the focal length (FA).

3. The radar sensor (10) according to any one of the preceding claims. Its features The distance (A) between the at least one antenna element (20-22, 25-27) and the lens side (31) of the radar converging lens (30) facing the at least one antenna element (20-22, 25-27) is between 0.5 and 0.9 times the focal length (FA).

4. The radar sensor (10) according to any one of the preceding claims. Its features The distance (A) between the at least one antenna element (20-22, 25-27) and the lens side (31) of the radar converging lens (30) facing the at least one antenna element (20-22, 25-27) is between 0.65 and 0.85 times the focal length (FA).

5. The radar sensor (10) according to any one of the preceding claims. Its features The radar converging lens (30) is concave on the lens side (31) facing the at least one antenna element (20-22, 25-27) and convex on the lens side (32) facing away from the at least one antenna element (20-22, 25-27).

6. The radar sensor (10) according to any one of claims 1-4. Its features The radar converging lens (30) is planar on the lens side (31) facing the at least one antenna element (20-22, 25-27) and convex on the lens side (32) facing away from the at least one antenna element (20-22, 25-27).

7. The radar sensor (10) according to any one of the preceding claims. Its features The radar sensor (10) has at least two antenna elements (21-22, 25-27), the first antenna element of the at least two antenna elements (21-22, 25-27) is electrically connected to the radar transmitting device (110), and the second antenna element of the at least two antenna elements (21-22, 25-27) is electrically connected to the radar receiving device (120).

8. The radar sensor (10) according to claim 7. Its features - The distance (A) between the focal point (40) and the first antenna element (21, 25) is at least 10% of the focal length (FA), and - The distance (A) between the focal point (40) and the second antenna element (22, 26) is also at least 10% of the focal length (FA).

9. The radar sensor (10) according to any one of claims 7-8. Its features - The distance (A) between the first antenna element (21, 25) and the lens side (31) of the radar converging lens (30) facing the first antenna element (21, 25) is between 0.5 and 0.9 times the focal length (FA), and - The distance (A) between the second antenna element (22, 26) and the lens side (31) of the radar converging lens (30) facing the second antenna element (22, 26) is between 0.5 and 0.9 times the focal length (FA).

10. The radar sensor (10) according to any one of claims 7-9. Its features - The distance (A) between the first antenna element (21, 25) and the lens side (31) of the radar converging lens (30) facing the first antenna element (21, 25) is between 0.65 and 0.85 times the focal length (FA), and - The distance (A) between the second antenna element (22, 26) and the lens side (31) of the radar converging lens (30) facing the second antenna element (22, 26) is between 0.65 and 0.85 times the focal length (FA).

11. The radar sensor (10) according to any one of claims 7-10. Its features - The radar receiver is additionally electrically connected to the third antenna element (27) of the radar sensor (10), and - The radar receiver is designed to detect the direction of received radar radiation by evaluating the received signals of the second and third antenna elements (26, 27).

12. The radar sensor (10) according to claim 11. Its features The distance (A) between the focal point (40) and the third antenna element (27) is at least 10% of the focal length (FA).

13. The radar sensor (10) according to any one of claims 11 to 12. Its features The distance (A) between the third antenna element (27) and the lens side (31) of the radar converging lens (30) facing the third antenna element (27) is between 0.5 and 0.9 times the focal length (FA).

14. The radar sensor (10) according to any one of claims 11-13. Its features The distance (A) between the third antenna element (27) and the lens side (31) of the radar converging lens (30) facing the third antenna element (27) is between 0.65 and 0.85 times the focal length (FA).

15. The radar sensor (10) according to any one of the preceding claims. Its features - The radar sensor (10) is equipped with four or more antenna elements. - The antenna element is spatially arranged between the focal point (40) and the lens side (31) of the radar converging lens (30) facing the focal point (40), and - The distance (A) between the focal point (40) and each of the antenna elements is at least 10% of the focal length (FA) in each case.

16. The radar sensor (10) according to claim 15. Its features The distance (A) between each of the antenna elements and the lens side (31) of the radar converging lens (30) facing the antenna element is, in each case, between 0.5 and 0.9 times the focal length (FA).

17. The radar sensor (10) according to any one of the preceding claims. Its features - The distance (A) between each of the antenna elements and the lens side (31) of the radar converging lens (30) facing the antenna element is, in each case, between 0.65 and 0.85 times the focal length (FA).

18. The radar sensor (10) according to any one of the preceding claims. Its features The radar converging lens (30) is composed of an integral element made of Teflon or polycarbonate.

19. The radar sensor (10) according to any one of the preceding claims. Its features - The antenna elements (20-22, 25-27) are each formed by a free conductor trace element. - The conductor trace elements are mounted on the same printed circuit board (100), and - At least in the region of the conductor trace element, the plane (E) of the printed circuit board (100) is arranged perpendicular to the central axis (M) of the radar converging lens (30).

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