Radar sensor

Abstract

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

Description

radar sensors Technical Field

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

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

[0003] This invention is based on the purpose of specifying 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 designs of the radar sensor according to the invention are specified in the dependent claims.

[0005] Therefore, according to the present invention, at least one antenna element is spatially arranged outside the region located between the focal point and the focal-facing lens side of the radar converging lens.

[0006] A fundamental advantage of the radar sensor according to the invention is that, due to the offset arrangement of at least one antenna element relative to the focal point provided according to the invention, a particularly good formation of the transmit or receive characteristics, hereinafter referred to as the antenna directional characteristics, can be achieved. Specifically, compared to a typical arrangement of antenna elements or elements, and therefore compared to an arrangement in the focal region, the formation of a particularly spherical expansion of the main lobe of the antenna directional characteristics can be achieved.

[0007] For example—depending on the antenna element or the element's offset relative to the focal point—the formation of secondary lobes adjacent to the main lobe is avoided, or the adjacent intervals adjacent to the main lobe merge with the main lobe, such that at the interface between the main lobe and the corresponding adjacent interval, the antenna directivity does not have an inwardly pointing dip in the direction of the antenna element, or at most has a plateau region. In other words, for example, the antenna directivity decreases continuously from its maximum value in the region of the main lobe in the direction of the adjacent interval, and also decreases continuously in the adjacent intervals, so that no intermediate region is formed at the interface where the antenna directivity is smaller than that in the adjacent adjacent intervals and smaller than that 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 1.4 and 1.8 times the focal length, and particularly preferably between 1.5 and 1.7 times the focal length.

[0010] In a preferred design, 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 design, 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] It is advantageous for radar operation if the radar sensor has at least two antenna elements, with the first antenna element electrically connected to the radar transmitting unit and the second antenna element electrically connected to the radar receiving unit.

[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 the last mentioned 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 1.4 and 1.8 times the focal length, particularly preferably between 1.5 and 1.7 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 1.4 and 1.8 times the focal length, particularly preferably between 1.5 and 1.7 times the focal length.

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

[0016] In the last mentioned 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 side of the radar converging lens facing the third antenna element is preferably between 1.4 and 1.8 times the focal length, and particularly preferably between 1.5 and 1.7 times the focal length.

[0018] It is also possible to have more than three antenna elements, thus including a fourth antenna element and other antenna elements. It is also preferably applicable to the last-mentioned antenna element, which is spatially arranged outside the region 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 1.4 and 1.8 times the focal length, particularly preferably between 1.5 and 1.7 times the focal length.

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

[0020] Regarding materials, it is considered advantageous if the radar converging lens consists of a single element made of Teflon or polycarbonate.

[0021] Antenna elements are preferably formed from individual free conductor trace elements (in the technical term also known as conductor trace plates).

[0022] It is advantageous if the conductor trace elements are applied to the same printed circuit board.

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

[0024] Here, the term "distance" between two objects will be understood in its usual sense, that is, the shortest distance between the respective objects in each case. Since in the typical design of radar sensors, antenna elements or components, especially those designed as flat conductor traces and with the lens side of the radar converging lens facing that conductor trace, always have spatial extension, the term "distance" between the antenna element and the lens side facing that antenna element will always be understood in each case as the shortest distance between the respective antenna element and the lens side, and the term "distance" between the antenna element and the focal point will always be understood in each case as the shortest distance between the respective antenna element and the focal point. Attached Figure Description

[0025] The invention will be explained in more detail below based on exemplary embodiments; in the exemplary drawings: FIG1 shows an exemplary embodiment of a radar sensor according to the invention, wherein antenna elements are arranged outside the region between the focal point and the radar converging lens; FIG2 shows the directional characteristics of the antenna elements from FIG1 in more detail; FIG3 shows the directional characteristics of the antenna elements from FIG1 in graphical form, representing antenna directional values ​​as a function of the transmission angle; FIG4 shows the directional characteristics of the antenna elements from FIG1 when they are arranged in the focal point; FIG5 shows the directional characteristics in an exemplary embodiment of a radar sensor according to the invention, wherein two antenna elements are arranged outside the region between the focal point and the radar converging lens; FIG6 shows the directional characteristics of a radar sensor for comparison, wherein two antenna elements are arranged in the focal point; FIG7 shows antenna elements arranged on a printed circuit board of an exemplary embodiment of a radar sensor according to the invention, equipped with three antenna elements; and FIG8 shows the arrangement of antenna elements between the focal point and the radar converging lens in the exemplary embodiment of FIG7 in a cross-sectional view.

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

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

[0028] The antenna element 20 and radar converging lens 30, which are suitable for focusing radar radiation, can be seen. In the exemplary embodiment of FIG1, 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. The radar converging lens 30 is preferably composed of a single element made of Teflon or polycarbonate with low absorption of radar radiation in mind.

[0029] The focal point 40 of the radar converging lens 30 has a focal length FA to the lens side 31 facing the focal point 40.

[0030] Antenna element 20 is spatially arranged outside the intermediate region located 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 1.55 and 1.65 times the focal length FA, and in the case of a planar-convex radar converging lens 30, it is preferably between 1.55 and 1.65 times the focal length FA. Therefore, the following is preferably applicable: in the case of a convex-concave radar converging lens 30, 1.55... FA <A<1.65 FA, and in the case of a planar-convex radar converging lens 30, 1.55 FA <A<1.65 FA.

[0031] In the case of both the convex-concave radar converging lens 30 and the planar-convex radar converging lens 30, the focal length FA is preferably in the range of 15mm and 16mm.

[0032] In the case of a convex-concave radar converging lens 30, and in the case of a planar-convex radar converging lens 30, the focal length FA is, for example, 15.5 mm, where the distance A between the antenna element 20 and the radar converging lens 30 is 24.82 mm. Therefore, 1.6 times the focal length FA is considered optimal.

[0033] Figure 2 illustrates, by way of example, the antenna directional characteristics of antenna element 20 from Figure 1, and thus, its transmit or receive characteristics. It can be seen that, due to the axial offset of the arrangement of antenna element 20 in the direction of the radar converging lens 30, the main transmit lobe 50 of the antenna directional characteristics—compared to the arrangement of antenna element 20 in the focal point 40—is formed with a very spherical expansion.

[0034] The formation of secondary lobes directly adjacent to the main transmit lobe 50 is avoided because the adjacent intervals 50a and 50b adjacent to the main transmit lobe 50 are merged with the main transmit lobe 50, so that at the interface SS between the main transmit lobe 50 and the corresponding adjacent intervals 50a or 50b, the antenna directional characteristics do not have an inwardly pointing concave or contracted direction in the direction of the antenna element 20.

[0035] Figure 3 shows the effect of launch angle. The process of varying antenna directional characteristics in the form of the antenna directional value R. Figures 2 and 3 illustrate the selection of the transmit angle by way of example, such that its value is [value] under maximum transmit or receive strength or under maximum antenna directional effect. =0, therefore it is in the middle of the main emission lobe 50.

[0036] As can be seen in Figure 3, despite the variable rate of increase, for values ​​less than zero... The antenna directional value R increases with increasing The value increases continuously, and although it has a variable rate of decrease, for values ​​greater than zero... It decreases continuously as the value of Φ increases.

[0037] In the region of the interface SS between the main transmit lobe 50 and two directly adjacent intervals 50a and 50b, the antenna directional characteristics change with the transmit angle. The process of change does indeed have a specific plateau region, in which the antenna directional characteristic R varies with the emission angle. The variation is relatively constant; however, no local maximum or local minimum is formed in the region of the main emission lobe 50 and in the regions of the two directly adjacent adjacent intervals 50a and 50b; only one maximum value exists in the middle region of the main emission lobe 50, especially the absolute maximum value.

[0038] In other words, in the exemplary embodiment according to Figures 2 and 3, starting from the maximum value reached by the antenna directional value R in the middle region of the main transmit lobe 50, the antenna directional characteristics decrease without interruption, or at most remain constant in the direction of adjacent intervals 50a and 50b in some intervals and also in the adjacent intervals 50a and 50b themselves. Therefore, the antenna directional value R will be less than the middle region in its adjacent region, which does not form at the interface SS.

[0039] To better understand, Figure 4 illustrates the formation of secondary lobes 51 and 52 when antenna element 20 is positioned at the focal point 40 of radar converging lens 30. As can be seen from Figure 4—compared to Figure 2—there is a clear separation between secondary lobes 51 and 52, and no merging of the main transmit lobe 50 with adjacent sections occurs; the antenna directional characteristics exhibit a clear dip EB or contraction in the direction of antenna element 20. These dip EBs result in objects positioned relative to the angle between the main transmit lobe 50 and one of the adjacent secondary lobes 51 or 52, depending on the sensitivity of radar sensor 10, not being identified.

[0040] Figures 1 and 2 illustrate an exemplary embodiment of the invention with only a single antenna element 20. It is advantageous if the radar sensor 10 has at least two antenna elements, with the first antenna element electrically connected to the radar transmitting unit and serving as the transmitting antenna element 21, and the second antenna element electrically connected to the radar receiving unit and serving as the receiving antenna element 22; an exemplary embodiment of the invention is illustrated in simplified form in Figure 5.

[0041] As can be seen from Figure 5, in the antenna directional characteristics of the transmitting antenna element 21, the adjacent intervals 60a and 60b are merged with the main transmitting lobe 60, and a spherical expansion antenna directional characteristic is achieved without the dip EB between the main transmitting lobe 60 and the adjacent intervals 60a and 60b; this is correspondingly applicable to the main transmitting lobe 70 and its adjacent intervals of the receiving antenna element 22, which are hidden in Figure 5.

[0042] In addition, it can be seen that due to the spherical expansion shape of the antenna directional characteristics, there is only a small indentation EB between the two main lobes 60 and 70, which makes the antenna directional characteristics of the radar sensor 10 generally quasi-constant in the main direction.

[0043] Figure 6 shows the antenna directional characteristics of two antenna elements 23 and 24 arranged in the region of focal point 40 for comparison. For clarity, only the two main lobes 80 and 90 are shown. It can be seen that a significant dip EB occurs between the peaks of the two main lobes 80 and 90, which is significantly larger and deeper than the dip in Figure 5.

[0044] Figure 7 illustrates the components of another exemplary embodiment of the invention, as well as a particularly preferred design and arrangement of the antenna elements. A printed circuit board 100 with three conductor trace elements is shown in the top view, each conductor trace element forming an antenna element.

[0045] One of the conductor trace elements forms a transmitting antenna element 25, which is connected to a radar transmitting unit 110 arranged on the printed circuit board 100 via a conductor trace 101 of the printed circuit board 100.

[0046] Another of the conductor trace elements forms a first receiving antenna element 26, which is connected to a radar receiving unit 120 arranged on the printed circuit board 100 via a conductor trace 102 of the printed circuit board 100.

[0047] The third antenna element 20 forms the second receiving antenna element 27, which is connected to the radar receiving unit 120 arranged on the printed circuit board 100 via the conductor trace 103 of the printed circuit board 100.

[0048] The radar receiving unit is designed to detect the direction of the received radar radiation by evaluating the signals received by the second antenna element 26 and the third antenna element 27, and in particular by evaluating the phase offset between the two received signals.

[0049] Figure 8 shows a cross-section of the printed circuit board 100 from Figure 7, and also shows a radar converging lens 30 and its focal point 40 in cross-section. It can be seen that the plane E of the printed circuit board 100 is arranged perpendicular to the central axis M of the radar lens and outside the intermediate region located between the focal point 40 and the radar converging lens 30.

[0050] The number of antenna elements can also be greater than three. For example, seven antenna elements can be present, each arranged outside the intermediate region 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. Three of the antenna elements can be operated, for example, as transmitting antenna elements, and the other four antenna elements can be operated as receiving antenna elements.

[0051] Finally, it should be noted that the features of all the above exemplary embodiments can be combined with each other as needed to form other different exemplary embodiments of the present invention.

[0052] All features of the dependent claims can also be combined with any other claim, particularly in each case, alone or in any combination with one or more other dependent claims, to obtain other different exemplary embodiments.

[0053] List of reference numerals in the attached figures

[0054] 10 Radar Sensors

[0055] 20 antenna elements

[0056] 21 Transmitting antenna elements

[0057] 22 Receiving antenna elements

[0058] 23 antenna elements

[0059] 24 Antenna Elements

[0060] 25 Transmitting antenna elements

[0061] 26 Receiving antenna elements

[0062] 27 Receiving antenna elements

[0063] 30 Radar converging lens

[0064] 31. Lens side

[0065] 32. Lens side

[0066] 40 Focus

[0067] 50 main emission lobes

[0068] 50a adjacent intervals

[0069] 50b Adjacent intervals

[0070] 51 secondary lobes

[0071] 52 secondary lobes

[0072] 60 main emission lobes

[0073] 60a Adjacent intervals

[0074] 60b Adjacent intervals

[0075] 70 main emission lobes

[0076] 80 main emission lobes

[0077] 90 main emission lobe

[0078] 100 Printed Circuit Boards

[0079] 101 Conductor Traces

[0080] 102 Conductor traces

[0081] 103 Conductor traces

[0082] 110 Radar Transmitting Unit

[0083] 120 Radar Receiving Unit

[0084] A distance

[0085] E plane

[0086] EB depression

[0087] FA focal length

[0088] M central axis

[0089] R antenna direction value

[0090] SS Interface Launch angle

Claims

1. A radar sensor (10) having 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 has a predetermined focal length (FA) at a distance from a lens side (31) of the radar converging lens (30) facing the focal point (40), characterized in that The at least one antenna element (20-22, 25-27) is spatially arranged outside the region 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, characterized in that... 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, characterized in that... 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 1.4 and 1.8 times the focal length (FA).

4. The radar sensor (10) according to any one of the preceding claims, characterized in that... 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).

5. The radar sensor (10) according to any one of claims 1-3, characterized in that... 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).

6. The radar sensor (10) according to any one of the preceding claims, characterized in that... 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 unit (110), and the second antenna element of the at least two antenna elements (21-22, 25-27) is electrically connected to the radar receiving unit (120), wherein the first antenna element and the second antenna element are each spatially arranged outside the region between the focal point (40) and the lens side (31) of the radar converging lens (30) facing the focal point (40).

7. The radar sensor (10) according to claim 6, characterized in that... - 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).

8. The radar sensor (10) according to any one of claims 6-7, characterized in that... - 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 1.4 and 1.8 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 1.4 and 1.8 times the focal length (FA).

9. The radar sensor (10) according to any one of claims 6-8, characterized in that... - The radar receiving unit is additionally electrically connected to the third antenna element (27) of the radar sensor (10), which is also spatially arranged outside the region between the focal point (40) and the lens side (31) of the radar converging lens (30) facing the focal point (40), and - The radar receiving unit is designed to detect the direction of the received radar radiation by evaluating the signals received by the second antenna element and the third antenna element (26, 27).

10. The radar sensor (10) according to claim 9, characterized in that... The distance (A) between the focal point (40) and the third antenna element (27) is at least 10% of the focal length (FA).

11. The radar sensor (10) according to any one of claims 9-10, characterized in that... 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 1.4 and 1.8 times the focal length (FA).

12. The radar sensor (10) according to any one of the preceding claims, characterized in that... - The radar sensor (10) is equipped with four or more antenna elements, - The antenna elements are spatially arranged outside the intermediate region 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.

13. The radar sensor (10) according to claim 12, characterized in that... 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 1.4 and 1.8 times the focal length (FA).

14. The radar sensor (10) according to any one of the preceding claims, characterized in that... The radar converging lens (30) consists of a single element made of Teflon or polycarbonate.

15. The radar sensor (10) according to any one of the preceding claims, characterized in that... - Each of the antenna elements (20-22, 25-27) is formed by a free conductor trace element, - the conductor trace elements are applied to the same printed circuit board (100), and - the plane (E) of the printed circuit board (100) is arranged to be perpendicular to the central axis (M) of the radar converging lens (30) at least in the region of the conductor trace elements.

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