US-12625228-B2 - Radar system for automotive applications

Abstract

A radar system for a vehicle includes: at least one main transmit antenna configured to transmit main radar waves essentially parallel to a road on which the vehicle is standing or driving; at least one main receive antenna configured to receive reflections of the main radar waves off objects on the road; a first street condition monitoring, SCM, transmit antenna configured to transmit first polarized radar waves essentially directed to the road at a first polarization; a second SCM transmit antenna configured to transmit second polarized radar waves essentially directed to the road at a second polarization different from the first polarization; a first SCM receive antenna configured to receive, at the first polarization, reflections of the polarized radar waves off the road; and a second SCM receive antenna configured to receive, at the second polarization, reflections of the polarized radar waves off the road.

Inventors

• Dennis Vollbracht
• Sadam Hussain Kazimi
• Sachit Varma

Assignees

• Aptiv Technologies AG

Dates

Publication Date

20260512

Application Date

20230630

Priority Date

20220705

Claims (19)

1. 1 . A radar system comprising: at least one main transmit antenna configured to transmit main radar waves essentially parallel to a road on which a vehicle is standing or driving; at least one main receive antenna configured to receive reflections of the main radar waves off objects on the road; a first street condition monitoring (SCM) transmit antenna configured to transmit first polarized radar waves essentially directed to the road at a first polarization; a second SCM transmit antenna configured to transmit second polarized radar waves essentially directed to the road at a second polarization different from the first polarization; a first SCM receive antenna configured to receive, at the first polarization, reflections of the first polarized radar waves off the road; and a second SCM receive antenna configured to receive, at the second polarization, reflections of the second polarized radar waves off the road, wherein the first and second SCM transmit and receive antennas are communicatively coupled to a processing device via frequency-selective elements, and wherein the frequency-selective elements include at least one of (a) high-pass filters, (b) step-impedance filters, (c) frequency-selective power dividers connected to filters, (d) dual-resonance filters, and (e) diplexers.
2. 2 . The radar system of claim 1 , wherein the at least one main transmit antenna and the first SCM transmit antenna comprise a same transmit antenna.
3. 3 . The radar system of claim 1 , wherein the at least one main receive antenna and the first SCM receive antenna comprise a same receive antenna.
4. 4 . The radar system of claim 1 , wherein: the at least one main transmit antenna and the first SCM transmit antenna comprise a same transmit antenna; and the at least one main receive antenna and the first SCM receive antenna comprise a same receive antenna.
5. 5 . The radar system of claim 1 , wherein main lobes of beam patterns of the first and second SCM transmit and receive antennas are tilted relative to main lobes of beam patterns of the main transmit and receive antennas.
6. 6 . The radar system of claim 1 , wherein the first and second SCM transmit and receive antennas are configured to cover an elevation angle of −75° to 0° responsive to the radar system being installed at the vehicle.
7. 7 . The radar system of claim 1 , wherein the first and second SCM receive antennas have a higher dynamic range than the at least one main receive antenna.
8. 8 . The radar system of claim 1 , wherein the first and second SCM transmit and receive antennas comprise at least one of slotted substrate-integrated waveguide (SIW) arrays or slotted air waveguide (AWG) arrays.
9. 9 . The radar system of claim 1 , wherein the first and second SCM transmit and receive antennas comprise a one-way co-polarization to cross-polarization isolation of at least 22.4 dB.
10. 10 . The radar system of claim 1 , wherein a gain pattern of the first and second SCM transmit and receive antennas has a half-power beamwidth of at most 45°.
11. 11 . The radar system of claim 1 , further comprising: the processing device, wherein the main transmit and receive antennas and the first and second SCM transmit and receive antennas are communicatively coupled to the processing device.
12. 12 . The radar system of claim 11 , wherein: the main transmit and receive antennas are configured to operate at a first center frequency; and the first and second SCM transmit and receive antennas are configured to operate at a second center frequency different from the first center frequency.
13. 13 . The radar system of claim 12 , wherein the frequency-selective elements comprise high-pass filters configured to separate the first center frequency from the second center frequency.
14. 14 . The radar system of claim 11 , wherein the frequency-selective elements comprise at least one of step-impedance filters, frequency-selective power dividers connected to filters, dual-resonance filters, or diplexers.
15. 15 . The radar system of claim 11 , wherein the first and second SCM transmit and receive antennas are communicatively coupled to the frequency-selective elements via waveguides.
16. 16 . The radar system of claim 11 , wherein the processing device comprises at least one monolithic microwave integrated circuit (MMIC).
17. 17 . The radar system of claim 1 , wherein: the main transmit and receive antennas are configured to operate at a first center frequency; and the first and second SCM transmit and receive antennas are configured to operate at a second center frequency different from the first center frequency.
18. 18 . A vehicle comprising a radar system, the radar system comprising: at least one main transmit antenna configured to transmit main radar waves essentially parallel to a road on which the vehicle is standing or driving; at least one main receive antenna configured to receive reflections of the main radar waves off objects on the road; a first street condition monitoring (SCM) transmit antenna configured to transmit first polarized radar waves essentially directed to the road at a first polarization; a second SCM transmit antenna configured to transmit second polarized radar waves essentially directed to the road at a second polarization different from the first polarization; a first SCM receive antenna configured to receive, at the first polarization, reflections of the first polarized radar waves off the road; and a second SCM receive antenna configured to receive, at the second polarization, reflections of the second polarized radar waves off the road, wherein the first and second SCM transmit and receive antennas are communicatively coupled to a processing device via frequency-selective elements, wherein the frequency-selective elements include at least one of (a) high-pass filters, (b) step-impedance filters, (c) frequency-selective power dividers connected to filters, (d) dual-resonance filters, and (e) diplexers.
19. 19 . A method comprising: transmitting, from at least one main transmit antenna, main radar waves essentially parallel to a road on which a vehicle is standing or driving; receiving, by at least one main receive antenna, reflections of the main radar waves off objects on the road; transmitting, from a first street condition monitoring (SCM) transmit antenna, first polarized radar waves essentially directed to the road at a first polarization; transmitting, from a second SCM transmit antenna, second polarized radar waves essentially directed to the road at a second polarization different from the first polarization; receiving, by a first SCM receive antenna at the first polarization, reflections of the first polarized radar waves off the road; and receiving, by a second SCM receive antenna at the second polarization, reflections of the second polarized radar waves off the road, wherein the first and second SCM transmit and receive antennas are communicatively coupled to a processing device via frequency-selective elements, wherein the frequency-selective elements include at least one of (a) high-pass filters, (b) step-impedance filters, (c) frequency-selective power dividers connected to filters, (d) dual-resonance filters, and (e) diplexers.

Description

INCORPORATION BY REFERENCE This application claims priority to European Patent Application No. EP22183083.9, filed Jul. 5, 2022, the disclosure of which is incorporated by reference in its entirety. BACKGROUND Modern cars often comprise electromagnetic sensors that are for example part of advanced driver-assistance systems (ADAS) such as adaptive cruise control, lane change assistance, intersection assistance to name just a few examples. An example of such an electromagnetic sensor is a radar (radio detection and ranging) sensor which is used for detecting and locating objects such as cars, pedestrians, obstacles, etc. The radar sensor emits an electromagnetic signal, usually as a directed beam, with a specific frequency such as for example 77 GHz. The signal is reflected off an object and the reflected signal (sometimes called an “echo”) is received and detected by the radar sensor and further processed to cause corresponding actions. SUMMARY Example implementations relate to a radar system for automotive applications that are capable of detecting and locating objects as well as allowing for the monitoring of street conditions. Described implementations of a radar system are configured to be installed at a vehicle and comprise at least one main transmit antenna being configured to transmit main radar waves essentially parallel to a road on which the vehicle is standing or driving; at least one main receive antenna being configured to receive reflections of the main radar waves off objects on the road; a first street condition monitoring, SCM, transmit antenna being configured to transmit first polarized radar waves essentially directed to the road at a first polarization; a second SCM transmit antenna being configured to transmit second polarized radar waves essentially directed to the road at a second polarization different from the first polarization; and a first SCM receive antenna being configured to receive, at the first polarization, reflections of the polarized radar waves off the road; and a second SCM receive antenna being configured to receive, at the second polarization, reflections of the polarized radar waves off the road. The main antennas can be used for object detection and location and radiate and receive essentially parallel to the road. Essentially parallel in the context of this application can mean that the longitudinal axis of the main lobe of the antenna's gain pattern is more or less parallel to the street (assuming a flat road), e.g. within ±5°. The SCM antennas are used for street condition monitoring and are essentially directed to the road which means that the longitudinal axes of the main lobes of their gain patterns are tilted and point to the road. The SCM antennas are polarimetric antennas meaning that they are configured to emit and receive at a certain polarization. Examples of such polarization include horizontal and vertical linear polarization as well as left-handed and right-handed circular polarization. The SCM antennas comprise at least one pair of a transmit and a receive antenna having a first polarization and another pair of transmit and a receive antenna having a second polarization different from the first polarization. This allows for street condition monitoring, e.g. determining street surface and precipitation, by measuring the co-polarized and cross-polarized backscattering coefficients as described in European patent application No. Thus, example implementations provide an integrated radar system for automotive applications that is at the same time capable of object detection and location as well as street condition monitoring. This meets the requirements of autonomous driving applications which require reliable and detailed information about the vehicular surroundings. Importantly, by providing a single radar system the integration into the vehicle is simplified and costs are significantly reduced as additional radar systems would require additional space, a separate interface to the vehicle's control systems and additional end of line testing at the original equipment manufacturer (OEM). The at least one main transmit antenna and the first SCM transmit antenna may be the same transmit antenna, and/or the at least one main receive antenna and the first SCM receive antenna may be the same receive antenna. In this way, the number of antennas and the overall form factor of the sensor system may be reduced. The combined (main and SCM) antennas may be configured to select between object detection and location, and street condition monitoring by switching the modulation scheme of the antennas. In one example, the combined antenna may be configured such that the direction of the main lobe of its gain pattern is frequency dependent. Thus, the combined antenna may be steered in a direction essentially parallel to the road or in a direction essentially towards the road depending on the frequency at which the combined antenna is operated. The main lobes of the beam p