Radar sensor device with at least one planar antenna device

Abstract

Radar sensor device (12) with at least one planar antenna device, which has exactly three vertically aligned antenna columns (15b to 15h) arranged as a thinned array (15.2, 15.3) in a plane parallel to one another at specific distances from one another, which each have at least two line-fed patch elements (23), wherein the thinned array (15.2, 15.3) of antenna columns (15b to 15h) is designed as an arrangement of non-equidistant antenna columns such that the set of specific distances of the antenna columns (15b to 15h) from one another in the thinned array (15.2, 15.3) includes all different distances between any two antenna columns (15a) of a corresponding non-thinned array (15.1) a planar antenna device with the same antenna aperture and the same nature of the antenna columns (15a) exactly once, wherein a distance between a first antenna column (15b) and a second antenna column (15c) is 0.5 · wavelength λ in air, a distance between the second antenna column (15c) and a third antenna column (15d) is 1.0 · wavelength λ in air and a distance between the first antenna column (15b) and the third antenna column (15d) is 1.5 · wavelength λ in air.

Description

[0001] The invention relates to a radar sensor device with at least one planar antenna device, which has a plurality of vertically aligned antenna columns arranged as a thinned array in a plane parallel to one another at specific distances, each of which has at least two line-fed patch elements. Furthermore, the invention relates to a device, in particular a driver assistance system of a motor vehicle. State of the art

[0002] Radar sensors are increasingly being used in motor vehicles to detect the traffic environment as part of driver assistance systems, for example, radar-based distance control (Adaptive Cruise Control systems / ACC). One such cruise control system is known, for example, from Robert Bosch GmbH, "Adaptive Cruise Control ACC," Yellow Series, 2002 edition, Technical Information.

[0003] Due to their flat design and ease of manufacture, for example, using etching processes, so-called planar antenna devices or patch antennas are particularly suitable for use in the radar sensors mentioned above. Such antennas consist of a planar arrangement of radiating resonators (antenna elements or patch elements / patches), each with a defined amplitude and phase. The superposition of the radiation patterns of the individual patch elements produces the resulting radiation pattern of the antenna, with the rows responsible for the azimuth characteristics and the columns for the elevation characteristics. The antenna elements are typically arranged in vertically aligned antenna columns.

[0004] Many radar sensors used for environmental detection in the automotive sector utilize such planar antenna concepts. One advantage of planar antenna concepts is the resulting shallow installation depth of the radar sensors. This allows for greater flexibility in the installation location of the radar sensors and opens up new areas of application, for example, by installing them in the side of the vehicle. In addition to size, the manufacturing costs of the radar sensors also play a significant role. Especially for planar antenna concepts that perform signal evaluation on the individual channels (no RF beamforming), the number of mixers used represents a major cost factor. The arrangement or number of antenna patches plays a key role here. Common radar sensors with planar antenna devices typically have the structure of a Uniform Linear Array (ULA).The antenna columns with the patch elements are arranged at equidistant intervals, which are usually in the range of half the wavelength in air (λ / 2).

[0005] To achieve the best possible angular accuracy with radar sensors, the antenna aperture is the decisive factor. The larger the antenna aperture, the better the angular accuracy. If the antenna aperture is equipped with a uniform linear array structure, as in previously known radar sensors, a large number of mixers are required, which leads to increased overall sensor costs.

[0006] DE 100 36 131 A1 proposes a radar sensor for detecting the traffic situation in the vicinity of a motor vehicle, comprising a carrier element and an array of patch antennas in the form of a combination of a filled subarray of patch antennas and a thinned subarray of patch antennas. However, the patch antennas are redundant, meaning the signal relationships are measured multiple times.

[0007] Feger et al.: "A 77-GHz FMCW MIMO Radar Based on an SiGe Single-Chip Transceiver. In: IEEE Transactions on Microwave Theory and Techniques, Vol. 57, 2009, No. 5, pp. 1020-1035. - ISSN 0018-9480" discloses antenna column elements arranged as a thinned array. Disclosure of the invention

[0008] According to the invention, a radar sensor device having the features of patent claim 1 is proposed.

[0009] Through these measures, a very good compromise between the required angular uniqueness and angular accuracy is achieved using so-called minimum redundancy arrays (MRA) of antenna columns. The arrangement of the antenna columns with patch elements is not equidistant, but rather takes into account the principle of minimal redundancy with thinned or sparse arrays. This advantageously leads to a further significant reduction in the number of antenna columns or patch elements and thus also in the number of mixers required, thereby reducing the costs of manufacturing the radar sensor. Because each distance between the antenna columns, i.e. each phase relationship, is present at least once but as rarely as possible, minimal redundancy is achieved. All different distances of any combination of antenna columns of a conventional orNon-thinned arrays of a planar antenna device with the same aperture must be present to ensure uniqueness.

[0010] The specified distances between the antenna slots are each an integer multiple of a constant baseline distance. The constant baseline distance is equal to half the wavelength in air. This results in a unique range of + / - 90 degrees.

[0011] A device, in particular a driver assistance system of a motor vehicle, is specified in claim 2.

[0012] An embodiment of the invention is described in principle below with reference to the drawing.

[0013] They show: Fig. 1 a schematic representation of the essential components of a driver assistance system or an adaptive cruise control device in a motor vehicle; Fig. 2 is a schematic diagram of an array of a planar antenna device with four antenna columns according to the prior art; Fig. 3 a schematic representation of an array of a planar antenna device with three antenna columns for an embodiment of the radar sensor device according to the invention; and Fig. 4 a schematic representation of an array of a planar antenna device with four antenna columns for a non-claimed embodiment. Description of implementation examples

[0014] One in Fig. The motor vehicle 10 shown in Figure 1 with an adaptive cruise control device 11 as a driver assistance system has, as an object detection sensor, a radar sensor device 12 mounted on the front of the motor vehicle 10, in whose housing a control device 14 of the adaptive cruise control device 11 is also housed. The radar sensor device 12 serves to detect objects in the surroundings of the motor vehicle 10. The radar sensor device 12 is connected to the control device 14. The control device 14 is connected via a data bus 16 (CAN, MOST, or the like) to an electronic drive control unit 18, a brake system control unit 20, and an HMI control unit 22 of a human-machine interface.In further embodiments not shown, the control unit 14 and the HMI control unit 22 can also be integrated in a control device of the adaptive cruise control device 11, in particular in a common housing.

[0015] The radar sensor device 12 uses a multi-beam radar to measure the distances, relative speeds, and azimuth angles of objects located in front of the motor vehicle 10 that reflect radar waves. The raw data received at regular intervals, for example, every 10 ms, are evaluated in the control device 14 to identify and track individual objects and, in particular, to detect a vehicle traveling directly ahead in the vehicle's own lane and select it as a target object.

[0016] How to continue Fig. 1, the radar sensor device 12 according to the invention has a planar antenna device with arrays 15.2 or 15.3 of antenna columns 15b to 15h (see Fig. 3 and Fig. 4) appears.

[0017] Fig. Figure 2 shows a planar antenna device or a non-thinned array 15.1 with four vertically aligned antenna columns 15a arranged in a plane parallel to one another at intervals according to the prior art. The antenna columns 15a are arranged at equidistant, ie constant, basic distances corresponding to half the wavelength λ in air. As can be seen from Fig. As can be seen in Figure 2, different distances occur: 0.5 · wavelength λ in air, 1.0 · wavelength λ in air and 1.5 · wavelength λ in air.

[0018] In Fig. 3 shows a planar antenna device for an embodiment of the radar sensor device 12 according to the invention with three vertically aligned antenna columns 15b, 15c and 15d arranged as a thinned array 15.2 in a plane parallel to one another at specific distances, each having a plurality of line-fed patch elements 23. The thinned array 15.2 of antenna columns 15b, 15c and 15d is designed with minimal redundancy such that the set of specific distances of the antenna columns 15b, 15c and 15d to one another in the thinned array 15.2 includes all different distances between any two antenna columns 15a of the corresponding non-thinned array 15.1. Fig. 1 of a planar antenna device with the same antenna aperture and the same nature of the antenna gaps 15a at least once, but in the minimum possible number. As further Fig. As can be seen in Figure 3, a distance of 0.5 wavelength λ in air is provided between the antenna gaps 15b and 15c, and a distance of 1.0 wavelength λ in air is provided between the antenna gaps 15c and 15d. Furthermore, a distance of 1.5 wavelength λ in air remains between the antenna gaps 15b and 15d.

[0019] In Fig. Figure 4 shows a planar antenna device for a non-claimed embodiment of the radar sensor device 12 according to the invention with four vertically aligned antenna columns 15e, 15f, 15g and 15h arranged as a thinned array 15.3 in a plane parallel to each other at specific distances. As can be seen from Fig.As can be seen in Figure 4, a distance of 0.5 wavelength λ in air is provided between antenna gaps 15e and 15f, a distance of 1.5 wavelength λ in air between antenna gaps 15f and 15g, and a distance of 1.0 wavelength λ in air between antenna gaps 15g and 15h. Furthermore, a distance of 2.0 wavelength λ in air remains between antenna gaps 15e and 15g, a distance of 2.5 wavelength λ in air between antenna gaps 15f and 15h, and a distance of 3.0 wavelength λ in air between antenna gaps 15e and 15h.

[0020] The determined distances between the antenna columns 15a to 15g are each an integer multiple of a constant basic distance, namely half the wavelength λ in air.

Claims

[1] Radar sensor device (12) with at least one planar antenna device, which has exactly three vertically aligned antenna columns (15b to 15h) arranged as a thinned array (15.2, 15.3) in a plane parallel to one another at specific distances from one another, which each have at least two line-fed patch elements (23), wherein the thinned array (15.2, 15.3) of antenna columns (15b to 15h) is designed as an arrangement of non-equidistant antenna columns such that the set of specific distances of the antenna columns (15b to 15h) from one another in the thinned array (15.2, 15.3) includes all different distances between any two antenna columns (15a) of a corresponding non-thinned array (15.1) a planar antenna device with the same antenna aperture and the same nature of the antenna columns (15a) exactly once, wherein a distance between a first antenna column (15b) and a second antenna column (15c) is 0.5 · wavelength λ in air, a distance between the second antenna column (15c) and a third antenna column (15d) is 1.0 · wavelength λ in air and a distance between the first antenna column (15b) and the third antenna column (15d) is 1.5 · wavelength λ in air. [2] Device, in particular driver assistance system (11) of a motor vehicle (10) with at least one radar sensor device (12) according to claim 1 for detecting objects in an environment of the motor vehicle (10), and a control device (14) which is connected to the at least one radar sensor device (12).

Images