Radar system with a modified orthogonal linear antenna subarray

Abstract

This document describes the technology and system of a radar system with a modified orthogonal linear antenna subarray and an angle measurement module. The described radar system includes a first one-dimensional (1D) (e.g., linear) subarray; a second 1D subarray positioned orthogonally to the first 1D subarray; and a two-dimensional (2D) subarray. Using the electromagnetic energy received by the first 1D subarray and the second 1D subarray, the azimuth angle and elevation angle associated with one or more objects can be determined. The radar system uses the electromagnetic energy received by the 2D subarray to associate pairs of azimuth angles and elevation angles to corresponding objects. In this way, the described system and technology can reduce the number of antenna elements while maintaining the angular resolution of a rectangular 2D array with a similar aperture size.

Description

Background Art

[0001] Radar systems use antennas to transmit and receive electromagnetic (EM) signals for detecting and tracking objects. In automotive applications, radar antennas can include two-dimensional (2D) arrays of elements to measure azimuth and elevation angles associated with an object. The resolution of these azimuth and elevation angles is generally proportional to the aperture size of the array. Implementing a large aperture using a 2D array may require many antenna elements, which increases cost. It is desirable to maintain the angular resolution of a radar system without adding additional antenna elements and without increasing cost. Summary of the Invention

[0002] This document describes techniques and systems for a radar system with modified orthogonal linear antenna subarrays. These modified subarrays enable an example radar system to have equivalent angular resolution at a lower cost and lower complexity level even with significantly fewer antenna elements compared to conventional radar systems. For example, a radar system includes a processor and an antenna that can receive electromagnetic energy reflected by one or more objects. The antenna includes a first one-dimensional (1D) (e.g., linear) subarray, a second 1D subarray, and a two-dimensional (2D) subarray. The second 1D subarray is positioned orthogonal to the first 1D subarray. The 2D subarray includes at least four antenna elements not encompassed by the first 1D subarray or the second 1D subarray. The processor can use the electromagnetic energy received by the first 1D subarray and the second 1D subarray to determine a first angle and a second angle associated with one or more objects. The processor then uses the electromagnetic energy received by the 2D subarray to associate the first angle and the second angle with a corresponding object among the one or more objects.

[0003] This document also describes methods performed by the systems summarized above and other configurations of the radar system described herein, as well as apparatuses for performing these methods.

[0004] This Summary of the Invention introduces simplified concepts related to a radar system with modified orthogonal linear antenna subarrays, which will be further described in the Detailed Description and the Drawings below. This Summary of the Invention is not intended to identify essential features of the claimed subject matter nor to be used to determine the scope of the claimed subject matter. Brief Description of the Drawings

[0005] In this document, details of one or more aspects of a radar system with modified orthogonal linear antenna subarrays are described with reference to the following drawings. Like numerals are generally used throughout the drawings to refer to like features and components:

[0006] Figure 1 An example environment is shown in which a radar system with modified orthogonal linear antenna subarrays can be implemented;

[0007] Figures 2A to 2F illustrates an example antenna with a modified orthogonal linear antenna subarray;

[0008] Figure 3 illustrates an example flowchart of a radar system with a modified orthogonal linear antenna subarray;

[0009] Figure 4 illustrates an example flowchart of an angle-finding module that associates azimuth and elevation angles with corresponding objects; and

[0010] Figure 5 illustrates an example method of a radar system with a modified orthogonal linear antenna subarray and an angle-finding module. DETAILED DESCRIPTION

[0011] OVERVIEW

[0012] A radar system is an important sensing technology, and some automotive systems rely on it to obtain information about the surrounding environment. A radar system typically includes at least two antennas to transmit and receive EM radiation. Some radar systems include a receiving antenna with a two-dimensional (2D) planar array of antenna elements to measure both the azimuth and elevation angles associated with an object. A large aperture in the azimuth and elevation directions of the receiving antenna can increase the number of antenna elements and the cost of the radar system.

[0013] Some radar systems include a receiving antenna with a two-dimensional (2D) planar array of antenna elements to measure both the azimuth and elevation angles of an object. In a radar system with a 2D planar antenna array, the radar system can use digital beamforming to estimate the angular position of an object. In digital beamforming, the radar system characterizes the angular information of an object by analyzing the relative phases of the antenna elements across the 2D planar array using a 2D fast Fourier transform (FFT). The angular resolution of such a radar system typically depends on the aperture size of the 2D planar array. A larger aperture can improve the angular resolution, but requires additional antenna elements and increased cost.

[0014] Other radar systems include a receiving antenna with two orthogonal linear arrays of antenna elements to occupy the azimuth and elevation directions of the antenna array. The radar system can use the azimuth linear array and the elevation linear array to measure the azimuth and elevation of an object, respectively. These radar systems use a matching algorithm to correlate the azimuth and elevation of each object. Although such systems typically include fewer antenna elements than a planar 2D array, for many applications (including automotive applications), the angle measurement of such systems is too complex. Specifically, the radar system uses a method based on the cross-correlation matrix, which requires multiple data snapshots from the linear array to correlate a single set of angle measurements. Since automotive radar systems generate a single snapshot when the vehicle is moving, such methods are not applicable to automotive applications.

[0015] Some other radar systems with orthogonal linear arrays use frequency-modulated continuous-wave signals. These radar systems use a beam matching method to correlate the azimuth and elevation. The beam matching method transforms the beam matching problem into an image block matching problem in the range-Doppler domain. However, this method is only applicable to applications where there is only a single object in any given range-Doppler bin. If two objects are in the same range-Doppler bin, these radar systems generally cannot accurately pair the azimuth and elevation for each corresponding object. The inability to accurately correlate the azimuth and elevation limits the application of these radar systems in automotive radar applications, where multiple objects can typically be present in the same range-Doppler bin.

[0016] In contrast, this document describes techniques and systems for providing a receiving antenna with orthogonal one-dimensional (1D) subarrays and a 2D subarray to support angle measurement features. For example, a radar system can include an antenna array having a first 1D subarray, a second 1D subarray, and a 2D subarray. The second 1D subarray is positioned orthogonal to the first 1D subarray. The 2D subarray includes at least four antenna elements not included in the first 1D subarray or the second 1D subarray. In this way, the described systems and techniques can reduce the number of antenna elements while maintaining the angular resolution achievable using a rectangular 2D array with a similar aperture size.

[0017] The radar system uses EM energy received by a first 1D sub-array and a second 1D sub-array to determine a first angle and a second angle associated with one or more nearby objects, respectively. The processor can then use the electromagnetic energy received by the 2D sub-array to associate the first angle and the second angle with the corresponding object among one or more objects. In this way, the described radar system has a computational complexity similar to that of a conventional radar system with a conventional 2D planar array in associating the first angle and the second angle with the corresponding object. The described angle measurement techniques can be applied to various configurations of the described orthogonal 1D sub-arrays and 2D sub-arrays.

[0018] This is merely an example of the techniques and systems for the described radar antenna with a modified orthogonal linear array. This document describes other examples and implementations.

[0019] Operating Environment

[0020] Figure 1 An example environment 100 is shown in which a radar system 102 with a modified orthogonal linear antenna sub-array can be implemented. In the depicted environment 100, the radar system 102 is mounted to a vehicle 104 or integrated within the vehicle 104. The radar system 102 can detect one or more objects 106 near the vehicle 104. Although shown as an automobile, the vehicle 104 can represent other types of motor vehicles (e.g., motorcycles, buses, tractors, semi-trailers), non-motor vehicles (e.g., bicycles), rail vehicles (e.g., trains), watercraft (e.g., boats), aircraft (e.g., airplanes), or spacecraft (e.g., satellites). Generally, a manufacturer can mount the radar system 102 to any mobile platform, including mobile machinery or robotic devices.

[0021] In the depicted implementation, the radar system 102 is mounted at the front of the vehicle 104 and illuminates the object 106. The radar system 102 can detect the object 106 from any outer surface of the vehicle 104. For example, a vehicle manufacturer can integrate the radar system 102 into a bumper, side mirror, headlight, taillight, or any other internal or external location where the object 106 needs to be detected. In some cases, the vehicle 104 includes multiple radar systems 102, such as a first radar system 102 and a second radar system 102 that provide a larger field of view. Generally, a vehicle manufacturer can design the location of one or more radar systems 102 to provide a specific field of view that includes the area of interest. Example fields of view include a 360-degree field of view, one or more 180-degree fields of view, one or more 90-degree fields of view, etc., which can overlap or be combined into a field of view of a specific size.

[0022] The object 106 is composed of one or more materials that reflect radar signals. Depending on the application, the object 106 may represent a target of interest. In some cases, the object 106 can be a moving object (e.g., another vehicle) or a stationary object (e.g., a roadside sign).

[0023] The radar system 102 emits EM radiation by transmitting an EM signal or waveform via the antenna element. In the environment 100, the radar system 102 can detect and track the object 106 by transmitting and receiving one or more radar signals. For example, the radar system 102 can transmit EM signals between 100 and 400 gigahertz (GHz), between 4 and 100 GHz, or between approximately 70 and 80 GHz.

[0024] The radar system 102 can include a transmitter 120 and at least one antenna 124 for transmitting EM signals. The radar system 102 can also include a receiver 122 and at least one antenna 124 for receiving the reflected version of the EM signal. The transmitter 120 includes one or more components for transmitting EM signals. The receiver 122 includes one or more components for detecting the reflected EM signal. The transmitter 120 and the receiver 122 can be incorporated together on the same integrated circuit (e.g., a transceiver integrated circuit) or separately on different integrated circuits.

[0025] The radar system 102 also includes one or more processors 126 (e.g., energy processing elements) and a computer-readable storage medium (CRM) 128. The processor 126 can be a microprocessor or a system-on-chip. The processor 126 can execute instructions stored in the CRM 128. For example, the processor 126 can process the EM energy received by the antenna 124 and use the angle measurement module 30 to determine the position of the object 106 relative to the radar system 102. The processor 126 can also generate radar data for at least one automotive system. For example, the processor 126 can control the autonomous driving system or semi-autonomous driving system of the vehicle 104 based on the processed EM energy from the antenna 124.

[0026] The angle measurement module 130 acquires the EM energy received by the antenna 124 and determines the azimuth angle and elevation angle associated with the object 106. The angle measurement module 130 can be implemented as instructions, hardware, software, or a combination thereof in the CRM 128 executed by the processor 126.

[0027] The radar system 102 can determine the distance to the object 106 based on the time it takes for an EM signal to travel from the radar system 102 to the object 106 and back to the radar system 102. The radar system 102 can also use the angle-of-arrival module 130 to determine the position of the object 106 according to the azimuth angle 116 and the elevation angle 118 based on the direction of the maximum amplitude echo signal received by the radar system 102.

[0028] As an example, Figure 1 A vehicle 104 traveling on a road 108 is shown. The radar system 102 detects an object 106 in front of the vehicle 104. The radar system 102 can define a coordinate system having an x-axis 110 (e.g., in the forward direction along the road 108), a y-axis 112 (e.g., perpendicular to the x-axis 110 and along the surface of the road 108), and a z-axis 114 (e.g., perpendicular to the surface of the road 108). The radar system 102 can locate the object 106 according to the azimuth angle 116 and the elevation angle 118. The azimuth angle 116 can represent the horizontal angle from the x-axis 110 to the object 106. The elevation angle 118 can represent the vertical angle from the surface of the road 108 (e.g., the plane defined by the x-axis 110 and the y-axis 112) to the object 106.

[0029] The vehicle 104 can also include at least one automotive system that depends on data from the radar system 102, such as a driver assistance system, an autonomous driving system, or a semi-autonomous driving system. The radar system 102 can include an interface that interfaces with the data-dependent automotive systems. For example, the processor 126 outputs a signal based on the EM energy received by the antenna 124 via the interface.

[0030] Generally, the automotive systems use the radar data provided by the radar system 102 to perform functions. For example, the driver assistance system can provide blind spot monitoring and generate an alert that indicates a potential collision with the object 106 detected by the radar system 102. In such implementations, the radar data from the radar system 102 indicates when it is safe or unsafe to change lanes. The autonomous driving system can move the vehicle 104 to a specific location on the road 108 while avoiding collisions with the object 106 detected by the radar system 102. The radar data provided by the radar system 102 can provide information related to the distance to the object 106 and the position of the object 106 to enable the autonomous driving system to perform emergency braking, perform a lane change, or adjust the speed of the vehicle 104.

[0031] Figures 2A to 2F Examples of antennas 200-1 to 200-6 (collectively referred to as antennas 200 hereinafter) having a modified orthogonal linear antenna subarray are shown. The antenna 200 is Figure 1An example of an antenna 124 of a radar system 102 having similar components. Antenna 200 includes a first 1D sub-array 204 (e.g., azimuth sub-array) on a printed circuit board (PCB) 202, a second 1D sub-array 206 (e.g., elevation sub-array), and a 2D sub-array 208. In operation, antenna 200 can receive EM energy reflected by one or more objects 106.

[0032] In the described implementation, the first antenna sub-array 204 is positioned in the azimuth direction and is hereinafter referred to as the azimuth sub-array 204. The second antenna sub-array 206 is positioned in the elevation direction and is hereinafter referred to as the elevation sub-array 206. The elevation sub-array 206 is positioned orthogonal to the azimuth sub-array 204. The azimuth sub-array 204 and the elevation sub-array 206 can be linear sub-arrays.

[0033] The azimuth sub-array 204 and the elevation sub-array 206 can be arranged in an approximate L-shape, as shown in Figure 2A ; Figure 2E and Figure 2F ; arranged in an approximate T-shape, as shown in Figure 2B and Figure 2C ; or arranged in an approximate cross-shape, as shown in Figure 2D . The radar designer or radar manufacturer can arrange the antenna elements of the azimuth sub-array 204 and the elevation sub-array 206 in other approximate shapes, where the elevation sub-array 206 is positioned orthogonal to the azimuth sub-array 204.

[0034] The antenna elements 210 of the 2D sub-array 208 can be arranged in an approximate rectangular shape, as shown in Figures 2A to 2E . These antenna elements 210 can be positioned close to (e.g., as shown in Figure 2A and Figure 2B ) the azimuth sub-array 204 and / or the elevation sub-array 206, overlap with the azimuth sub-array 204 and / or the elevation sub-array 206 (e.g., as shown in Figure 2C and Figure 2D ), or be separated from the azimuth sub-array 204 and / or the elevation sub-array 206 (e.g., as shown in Figure 2E and Figure 2F ). The antenna elements 210 of the 2D sub-array 208 can also be arranged in a two-dimensional sparse array, as shown in Figure 2F . The specific arrangements of the azimuth sub-array 204, the elevation sub-array 206, and the 2D sub-array 208 can be selected based on the positions and arrangements of other components in the radar system 102.

[0035] The azimuth subarray 204, the elevation subarray 206, and the 2D subarray 208 include a plurality of antenna elements 210. The azimuth subarray 204 may include M antenna elements 210. The elevation subarray 206 may include N antenna elements 210, where N is equal to or not equal to M. The 2D subarray 208 may include P antenna elements 210 not included in the azimuth subarray 204 or the elevation subarray 206. In an automotive application, the number of antenna elements 210 in the 2D subarray 208 may be larger than the expected maximum number of objects 106 to be detected by the radar system 102. The number P of antenna elements 210 in the 2D subarray is typically smaller than the product of M and N (e.g., P << M×N). In some implementations, P is smaller than half of the product of M and N (e.g., P << (M×N) / 2). The total number of antenna elements 210 in the antenna 200 is typically equal to M + N + P - 1, where one antenna element 210 is shared by the azimuth subarray 204 and the elevation subarray 206. The number of antenna elements 210 in the antenna 200 (e.g., M + N + P - 1) is typically much smaller than the number of antenna elements 210 in a rectangular array (e.g., M×N) having the same aperture size.

[0036] In the depicted implementation, the azimuth subarray 204 includes nine antenna elements 210, the elevation subarray 206 includes eight antenna elements 210, and the 2D subarray 208 includes six antenna elements 210 not included in the azimuth subarray 204 or the elevation subarray 206. The antenna 200 includes 22 antenna elements 210, which is much smaller than the 72 antenna elements included in a rectangular array having the same aperture size. In other implementations, the azimuth subarray 204, the elevation subarray 206, or the 2D subarray 208 may include fewer or additional antenna elements 210. The 2D subarray 208 typically includes at least four antenna elements 210 not included in the azimuth subarray 204 or the elevation subarray 206.

[0037] The antenna elements 210 in the azimuth subarray 204 and the 2D subarray 208 are separated by an azimuth distance 212 (d AZ ). Similarly, the antenna elements 210 in the elevation subarray 204 and the 2D subarray 208 are separated by an elevation distance 214 (d EL ). As described with respect to Figure 5 , the angle measurement module 130 associates the elevation angle and the azimuth angle of the object 106 using the azimuth distance 212 and the elevation distance 214.

[0038] The azimuth subarray 204, the elevation subarray 206, and the 2D subarray 208 can be planar arrays that provide high gain and low loss. Due to their small size, planar arrays are well-suited for vehicle integration. For example, the antenna element 210 can be a slot etched or otherwise formed in the plating material on one surface of the PCB 206 for a substrate integrated waveguide (SIW) antenna. The antenna element 210 can also be part of an aperture antenna, a microstrip antenna, or a dipole antenna. For example, the azimuth subarray 204, the elevation subarray 206, and the 2D subarray 208 can include subarrays of patch elements (e.g., microstrip patch antenna subarrays) or dipole elements.

[0039] Figure 3 An example flowchart 300 of a radar system 102 with modified orthogonal linear antenna subarrays and an angle measurement module 130 is shown. For example, Figure 3 the radar system 102 can be Figure 1 the radar system 102. The radar system 102 includes two 1D subarrays and a 2D subarray positioned orthogonal to each other. In the depicted implementation, the radar system 102 includes an azimuth subarray 204, an elevation subarray 206, and a 2D subarray of an antenna 200, and the azimuth subarray 204, the elevation subarray 206, and the 2D subarray of the antenna 200 can be arranged in various positions, including Figures 2A to 2F the arrangement shown in

[0040] At 304, the angle measurement module 130 acquires the EM energy 302 received by the azimuth subarray 204 and determines the azimuth 306 associated with one or more azimuth objects. The azimuth 306 includes where N AZ represents the number of azimuth objects.

[0041] At 310, the angle measurement module 130 acquires the EM energy 308 received by the elevation subarray 206 and determines the elevation 312 associated with one or more elevation objects. The elevation 312 includes where N EL represents the number of elevation objects. Since two or more of the objects 106 can have the same azimuth 306 and / or the same elevation 312, the number N EL of elevation objects can be different from the number N AZ of azimuth objects. For example, the radar system 102 can detect three objects 106 (e.g., three vehicles in front of the vehicle 104), and each object can have the same elevation 312 relative to the radar system 102 but different azimuths 306. As a result, the angle measurement module 130 will identify one elevation object but three azimuth objects.

[0042] The angle measurement module 130 can use various angle measurement functions to determine the azimuth angle 306 and the elevation angle 312 according to the EM energy 302 and the EM energy 308 respectively. As a non-limiting example, the angle measurement module 130 can use pseudo-spectrum functions (including Spatial Alternating Generalized Expectation Maximization (SAGE), Delay and Sum (DS), Minimum Variance Distortionless Response (MVDR), and / or functions based on Multiple Signal Classification (MUSIC)) to calculate the direction of arrival of the EM signals received by the azimuth sub-array 206 and the elevation sub-array 208. As another example, the angle measurement module can use Estimation of Signal Parameters via Rotational Invariance Technique (ESPRIT) or FFT beamforming to calculate the azimuth angle 306 and the elevation angle 312. The angle measurement module 130 can determine the azimuth angle 306 and the elevation angle 312 with relatively low processing complexity and cost.

[0043] At 316, the angle measurement module 130 associates the azimuth angle 306 and the elevation angle 312 with the object 106 using the EM energy 314 received by the 2D sub-array 208. Specifically, the angle measurement module 130 determines the azimuth angle 306 and the elevation angle 312 associated with each of one or more objects 106. Regarding Figure 4 the association between the azimuth angle 306 and the elevation angle 312 is described in more detail.

[0044] Figure 4 An example flowchart 316 of the angle measurement module 130 that associates the azimuth angle 306 and the elevation angle 312 with the corresponding object 106 is shown. For example, Figure 4 the angle measurement module 130 can be Figures 1 to 3 the angle measurement module 130. As described regarding Figure 3 the angle measurement module 130 determines the azimuth angle 306 and the elevation angle 312 associated with the azimuth object and the elevation object respectively.

[0045] At 402, the angle measurement module 130 can define the coordinate system of the antenna elements 210 of the 2D sub-array 208. For example, the angle measurement module 130 can represent the coordinates of the left-bottommost antenna element 210 of the 2D sub-array 208 in the antenna 200-1 as (0,0). The coordinates of the other antenna elements 210 in the 2D sub-array 208 can be represented as where K represents the total number of antenna elements 210 in the 2D sub-array, and and represent the azimuth distance 212 and the elevation distance 214 from the i-th antenna element 210 to the left-bottommost antenna element 210 respectively.

[0046] At 404, the angle measurement module 130 can generate a dictionary matrix 406 of steering vectors using a coordinate system, where the steering vectors include each of the azimuth angles 306 paired with each of the elevation angles 312. If a pair of azimuth angle 306 and elevation angle 312 of a point scatterer is given as then the angle measurement module 130 can generate a K×1 steering vector:

[0047]

[0048] where λ represents the wavelength of the EM signal transmitted and received by the radar system 102.

[0049] The angle measurement module 130 can use the azimuth angle 306 and the elevation angle 312 to form N AZ N EL angle pairs. The angle of the object 106 is included in the N AZ N EL angle pairs.

[0050] For each angle pair (where u ∈ {1, 2, …, N AZ} and v ∈ {1, 2, …, N EL}), the angle measurement module 130 can define the steering vector of the 2D sub-array 208 as:

[0051]

[0052] The angle measurement module 130 can assemble the steering vectors of the angle pairs into a K×N AZ N EL dictionary matrix 406:

[0053]

[0054] At 408, the angle measurement module 130 can use a function based on L1 minimization and the EM energy 314 received by the 2D sub-array 208 to determine the non-zero elements in the selection vector. The non-zero elements in the selection vector represent the actual angle pairs 410 of the dictionary matrix 406 corresponding to the azimuth angle 306 and elevation angle 312 of the corresponding object 106.

[0055] Because the actual pair 410 of the object 106 should be within the N AZ N EL angle pairs, the angle measurement module 130 can use the following equation to identify the actual pair 410:

[0056] y = Ax + η (4)

[0057] where the K×1 vector y represents the measured beam vector of the EM energy 314 received by the 2D subarray 208, N AZ N EL the N×1 vector x represents the analytic vector, and the K×1 vector η represents the measurement noise. The angle-of-arrival module 130 treats x as the selection vector. The steering vectors in A corresponding to the non-zero elements in x represent the actual pairs 410.

[0058] The angle-of-arrival module 130 can solve for x in equation (4) by solving the following L1 minimization:[[]]

[0059]

[0060] where ε limits the amount of noise in the data. The angle-of-arrival module 130 can use, for example, a function based on orthogonal matching pursuit (OMP) to solve equation (5).

[0061] Example method

[0062] Figure 5 illustrates an example method 500 of a radar system 102 having a modified orthogonal linear antenna subarray and an angle-of-arrival module 130. The method 500 is shown as a series of operations (or actions) to be performed, but is not necessarily limited to the order or combination of operations shown herein. Additionally, one or more of the operations can be repeated, combined, or reorganized to provide other methods. In the following discussion, reference may be made to Figure 1 the environment 100 and Figures 1 to 4 the entities detailed in

[0063] merely by way of example. The techniques are not limited to being performed by one entity or multiple entities.

[0064] At 502, the antennas of the radar system receive EM energy reflected by one or more objects. For example, the antennas 200 of the radar system 102 can receive EM energy reflected by one or more objects 106.

[0065] At 506, a second angle associated with one or more second objects is determined using EM energy received by a second 1D subarray of the antenna. The one or more second objects are a second subset of the one or more objects. The second 1D subarray is positioned orthogonally to the first 1D subarray. For example, the processor 126 may use the angle measurement module 130 and the EM energy 308 received by the elevation subarray 206 to determine the elevation angle 312 associated with one or more elevation objects. The one or more elevation objects are a second subset of the one or more objects 106. The elevation subarray 206 is positioned orthogonally to the azimuth subarray 204.

[0066] At 508, the first angle and the second angle are associated with corresponding objects among the one or more objects using EM energy received by the 2D subarray. The 2D subarray includes at least four antenna elements not included in the first 1D subarray or the second 1D subarray. For example, the processor 126 may use the angle measurement module 130 and the EM energy 314 received by the 2D subarray 208 to associate the azimuth angle 306 and the elevation angle 312 with corresponding objects among the one or more objects 106. The 2D subarray 208 includes at least four antenna elements 210 not included in the azimuth subarray 204 and the elevation subarray 206.

[0067] Example

[0068] In the following sections, examples are provided.

[0069] Example 1: A radar system includes: an antenna configured to receive electromagnetic (EM) energy reflected by one or more objects, the antenna including: a first one-dimensional subarray; a second one-dimensional subarray positioned orthogonally to the first one-dimensional subarray; and a two-dimensional subarray including at least four antenna elements not included in the first one-dimensional subarray or the second one-dimensional subarray; and one or more processors configured to: determine a first angle associated with one or more first objects using the EM energy received by the first one-dimensional subarray, the one or more first objects including a first subset of the one or more objects; determine a second angle associated with one or more second objects using the EM energy received by the second one-dimensional subarray, the one or more second objects including a second subset of the one or more objects; and associate the first angle and the second angle with corresponding objects among the one or more objects using the EM energy received by the two-dimensional subarray.

[0070] Example 2: The radar system of Example 1, wherein the one or more processors are configured to associate the first angle and the second angle with the corresponding object among the one or more objects in the following manner: defining a coordinate system of the antenna elements that define the two-dimensional sub-array; using the coordinate system to generate a dictionary matrix of steering vectors, the steering vectors including each of the first angles paired with each of the second angles; and using a function based on L1 minimization and the EM energy received by the two-dimensional sub-array to determine non-zero elements in a selection vector, the non-zero elements in the selection vector representing pairs of the first angle and the second angle in the dictionary matrix, the pairs corresponding to the first angle and the second angle of the corresponding object among the one or more objects.

[0071] Example 3: The radar system of any one of Example 1 or Example 2, wherein the first one-dimensional sub-array is positioned in the azimuth direction, and the second one-dimensional sub-array is positioned in the elevation direction.

[0072] Example 4: The radar system of any one of Example 1 to Example 3, wherein the first one-dimensional array and the second one-dimensional array are linear sub-arrays.

[0073] Example 5: The radar system of Example 4, wherein the first one-dimensional sub-array and the second one-dimensional sub-array are configured to be approximately L-shaped, approximately T-shaped, or approximately cross-shaped.

[0074] Example 6: The radar system of any one of Example 1 to Example 5, wherein the first one-dimensional sub-array includes a first number of antenna elements, and the second one-dimensional sub-array includes a second number of antenna elements, the first number of antenna elements not being equal to the second number of antenna elements.

[0075] Example 7: The radar system of Example 6, wherein the two-dimensional sub-array includes a third number of antenna elements, the third number of antenna elements being less than half the product of the first number of antenna elements and the second number of antenna elements.

[0076] Example 8: The radar system of any one of Example 1 to Example 7, wherein the antenna elements of the two-dimensional sub-array are configured to be approximately rectangular in shape.

[0077] Example 9: The radar system of any one of Example 1 to Example 8, wherein the antenna elements of the two-dimensional sub-array are positioned in a sparse array.

[0078] Example 10: The radar system of any one of Example 1 to Example 9, wherein the number of antenna elements in the two-dimensional sub-array is greater than the expected maximum number of objects of the radar system.

[0079] Example 11: The radar system of any one of Examples 1 to 10, wherein the antenna elements of the two-dimensional subarray are not included in the first one-dimensional subarray or the second one-dimensional subarray.

[0080] Example 12: The radar system of any one of Examples 1 to 11, wherein the first angle and the second angle are determined using at least one of the following: estimation of signal parameters via rotational invariance techniques (ESPRIT), spatial alternating generalized expectation maximization (SAGE), delay and sum (DS), minimum variance distortionless response (MVDR), multiple signal classification (MUSIC), or a function based on fast Fourier transform (FFT) beamforming.

[0081] Example 13: The radar system of any one of Examples 1 to 12, wherein the radar system is configured to be mounted on a vehicle.

[0082] Example 14: A method, the method comprising: receiving, by an antenna of a radar system, electromagnetic (EM) energy reflected by one or more objects; using the EM energy received by a first one-dimensional subarray of the antenna to determine a first angle associated with one or more first objects, the one or more first objects including a first subset of the one or more objects; using the EM energy received by a second one-dimensional subarray of the antenna to determine a second angle associated with one or more second objects, the one or more second objects including a second subset of the one or more objects, the second one-dimensional subarray being positioned orthogonally to the first one-dimensional subarray; and using the EM energy received by a two-dimensional subarray to associate the first angle and the second angle with corresponding objects among the one or more objects, the two-dimensional subarray including at least four antenna elements not included in the first one-dimensional subarray or the second one-dimensional subarray.

[0083] Example 15: The method of Example 14, wherein associating the first angle and the second angle with the corresponding objects among the one or more objects includes: defining a coordinate system for the antenna elements of the two-dimensional subarray; using the coordinate system to generate a dictionary matrix of steering vectors, the steering vectors including each of the first angles paired with each of the second angles; and using a function based on L1 minimization and the EM energy received by the two-dimensional subarray to determine non-zero elements in a selection vector, the non-zero elements in the selection vector representing pairs of the first angle and the second angle in the dictionary matrix, the pairs corresponding to the first angle and the second angle of the corresponding objects among the one or more objects.

[0084] Example 16: The method according to any one of Example 14 or Example 15, wherein the first one-dimensional subarray is positioned in the azimuth direction, and the second one-dimensional subarray is positioned in the elevation direction.

[0085] Example 17: The method according to any one of Examples 14 to 16, wherein the antenna elements of the two-dimensional subarray are positioned in a sparse array.

[0086] Example 18: A computer-readable storage medium, comprising computer-executable instructions that, when executed, cause a processor of a radar system to: receive electromagnetic (EM) energy reflected by one or more objects via an antenna of the radar system; use the EM energy received by a first one-dimensional subarray of the antenna to determine a first angle associated with one or more first objects, the one or more first objects including a first subset of the one or more objects; use the EM energy received by a second one-dimensional subarray of the antenna to determine a second angle associated with one or more second objects, the one or more second objects including a second subset of the one or more objects, the second one-dimensional subarray being positioned orthogonally to the first one-dimensional subarray; and use the EM energy received by the two-dimensional subarray to associate the first angle and the second angle with corresponding objects among the one or more objects, the two-dimensional subarray including at least four antenna elements not included in the first one-dimensional subarray or the second one-dimensional subarray.

[0087] Example 19: The computer-readable storage medium of Example 18, wherein the computer-executable instructions for associating the first angle and the second angle with the corresponding objects cause the processor of the radar system to: define a coordinate system for the antenna elements of the two-dimensional subarray; use the coordinate system to generate a dictionary matrix of steering vectors, the steering vectors including each of the first angles paired with each of the second angles; and use a function based on L1 minimization and the EM energy received by the two-dimensional subarray to determine non-zero elements in a selection vector, the non-zero elements in the selection vector representing pairs of the first angle and the second angle in the dictionary matrix, the pairs corresponding to the first angle and the second angle of the corresponding object among the one or more objects.

[0088] Example 20: The computer-readable storage medium according to any one of Example 18 or 19, wherein the first one-dimensional subarray is positioned in the azimuth direction, and the second one-dimensional subarray is positioned in the elevation direction.

[0089] Example 21: A computer-readable storage medium including computer-executable instructions that, when executed, cause a processor of a radar system to perform the method of any one of Examples 14 to 17.

[0090] Conclusion

[0091] Although various embodiments of the present disclosure have been described in the foregoing description and illustrated in the accompanying drawings, it should be understood that the present disclosure is not limited thereto, but may be implemented in various ways within the scope of the following claims for practice. From the foregoing description, it will be apparent that various changes may be made without departing from the spirit and scope of the present disclosure as defined by the following claims.

Claims

1. A radar system, characterized in that, Comprising: An antenna configured to receive electromagnetic (EM) energy reflected by one or more objects, the antenna comprising: A first one-dimensional subarray; A second one-dimensional subarray positioned orthogonally to the first one-dimensional subarray; and A two-dimensional subarray comprising at least four antenna elements not included in the first one-dimensional subarray or the second one-dimensional subarray; and One or more processors configured to: Use the EM energy received by the first one-dimensional subarray to determine a first angle associated with one or more first objects, the one or more first objects including a first subset of the one or more objects; Use the EM energy received by the second one-dimensional subarray to determine a second angle associated with one or more second objects, the one or more second objects including a second subset of the one or more objects; and Use the EM energy received by the two-dimensional subarray to associate the first angle and the second angle with corresponding objects among the one or more objects.

2. The radar system according to claim 1, wherein The one or more processors are configured to associate the first angle and the second angle with the corresponding objects among the one or more objects in the following manner: Define a coordinate system of the antenna elements of the two-dimensional subarray; Use the coordinate system to generate a dictionary matrix of steering vectors, the steering vectors including each of the first angles paired with each of the second angles; and And Use a function based on L1 minimization and the EM energy received by the two-dimensional subarray to determine non-zero elements in a selection vector, the non-zero elements in the selection vector representing pairs of the first angle and the second angle in the dictionary matrix that correspond to the first angle and the second angle of the corresponding object among the one or more objects.

3. The radar system according to claim 1, characterized in that, The first one-dimensional subarray is positioned in the azimuth direction, and the second one-dimensional subarray is positioned in the elevation direction.

4. The radar system according to claim 1, wherein The first one-dimensional subarray and the second one-dimensional subarray are linear subarrays.

5. The radar system according to claim 4, wherein, The first one-dimensional subarray and the second one-dimensional subarray are configured to approximate an L shape, an approximate T shape, or an approximate cross shape.

6. The radar system according to claim 1, wherein the first one-dimensional subarray includes a first number of antenna elements, and the second one-dimensional subarray includes a second number of antenna elements, and the first number of antenna elements is not equal to the second number of antenna elements.

7. The radar system according to claim 6, wherein The two-dimensional subarray includes a third number of antenna elements, and the third number of antenna elements is less than half of the product of the first number of antenna elements and the second number of antenna elements.

8. The radar system according to claim 1, wherein, The antenna elements of the two-dimensional subarray are configured to approximate a rectangular shape.

9. The radar system according to claim 1, characterized in that, The antenna elements of the two-dimensional subarray are positioned in a sparse array.

10. The radar system according to claim 1, wherein The number of antenna elements in the two-dimensional subarray is greater than the expected maximum number of objects of the radar system.

11. The radar system according to claim 1, wherein, The antenna elements of the two-dimensional subarray are not included in the first one-dimensional subarray or the second one-dimensional subarray.

12. The radar system according to claim 1, characterized in that, The first angle and the second angle are determined using at least one of the following: Estimation of Signal Parameters via Rotational Invariance Techniques (ESPRIT), Space Alternating Generalized Expectation Maximization (SAGE), Delay and Sum (DS), Minimum Variance Distortionless Response (MVDR), Multiple Signal Classification (MUSIC), or a function based on Fast Fourier Transform (FFT) beamforming.

13. The radar system according to claim 1, characterized in that, The radar system is configured to be mounted on a vehicle.

14. A method for a radar system, characterized in that, Comprising: Receiving electromagnetic (EM) energy reflected by one or more objects via an antenna of the radar system; Using the EM energy received by a first one-dimensional subarray of the antenna to determine a first angle associated with one or more first objects, the one or more first objects including a first subset of the one or more objects; Using the EM energy received by a second one-dimensional subarray of the antenna to determine a second angle associated with one or more second objects, the one or more second objects including a second subset of the one or more objects, the second one-dimensional subarray being positioned orthogonally to the first one-dimensional subarray; And Using the EM energy received by a two-dimensional subarray to associate the first angle and the second angle with corresponding ones of the one or more objects, the two-dimensional subarray including at least four antenna elements not included in the first one-dimensional subarray or the second one-dimensional subarray.

15. The method according to claim 14, wherein Associating the first angle and the second angle with the corresponding ones of the one or more objects includes: Defining a coordinate system of the antenna elements of the two-dimensional subarray; Using the coordinate system to generate a dictionary matrix of steering vectors, the steering vectors including each of the first angles paired with each of the second angles; and Using a function based on L1 minimization and the EM energy received by the two-dimensional subarray to determine non-zero elements in a selection vector, the non-zero elements in the selection vector representing pairs of the first angles and the second angles in the dictionary matrix that correspond to the first angle and the second angle of the corresponding one of the one or more objects.

16. The method according to claim 14, wherein The first one-dimensional subarray is positioned in the azimuth direction, and the second one-dimensional subarray is positioned in the elevation direction.

17. The method according to claim 14, wherein The antenna elements of the two-dimensional subarray are positioned in a sparse array.

18. A computer-readable storage medium comprising computer-executable instructions that, when executed, cause a processor of a radar system to: Receive electromagnetic (EM) energy reflected by one or more objects via an antenna of the radar system; Use the EM energy received by a first one-dimensional subarray of the antenna to determine a first angle associated with one or more first objects, the one or more first objects including a first subset of the one or more objects; Use the EM energy received by the second one-dimensional subarray of the antenna to determine a second angle associated with one or more second objects, the one or more second objects including a second subset of the one or more objects, the second one-dimensional subarray being positioned orthogonally to the first one-dimensional subarray; And Use the EM energy received by the two-dimensional subarray to associate the first angle and the second angle with corresponding ones of the one or more objects, the two-dimensional subarray including at least four antenna elements not included by the first one-dimensional subarray or the second one-dimensional subarray.

19. The computer-readable storage medium according to claim 18, wherein, The computer-executable instructions for associating the first angle and the second angle with the corresponding objects cause the processor of the radar system to: Define a coordinate system for the antenna elements of the two-dimensional subarray; Use the coordinate system to generate a dictionary matrix of steering vectors, the steering vectors including each of the first angles paired with each of the second angles; And Use a function based on L1 minimization and the EM energy received by the two-dimensional subarray to determine non-zero elements in a selection vector, the non-zero elements in the selection vector representing pairs of the first angles and the second angles in the dictionary matrix that correspond to the first angles and the second angles of the corresponding ones of the one or more objects.

20. The computer-readable storage medium according to claim 18, wherein The first one-dimensional subarray is positioned in the azimuth direction, and the second one-dimensional subarray is positioned in the elevation direction.

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