# US 12,762,202 B2 · Sparse antenna arrays for automotive radar

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- Number: US 12,762,202 B2
- Document ID: US12762202B2
- Status: Granted
- Kind: B2
- Application number: 17/582,437
- Filed: 2022-01-24
- Published: 2022-10-13
- Granted: 2026-10-13
- Earliest claimed: 2021-01-22
- Assignees: Robert Bosch GmbH
- Applicants: Uhnder, Inc.
- Inventors: Suleyman Gokhun Tanyer; Paul Dent; Murtaza Ali; Curtis Davis
- Web page: https://patentgrep.com/patent/US12762202B2

## CPC

- G06F 17/16: Matrix or vector computation {, e.g. matrix-matrix or matrix-vector multiplication, matrix factorization (matrix transposition G06F7/78)}
- G01S 7/023: {Interference mitigation, e.g. reducing or avoiding non-intentional interference with other HF-transmitters, base station transmitters for mobile communication or other radar systems, e.g. using electro-magnetic interference [EMI] reduction techniques (auxiliary means for detecting or identifying radar signals or the like G01S7/021; means for anti-jamming G01S7/36)}
- G01S 7/0231: {Avoidance by polarisation multiplex}
- G01S 7/0232: {Avoidance by frequency multiplex}
- G01S 7/0234: {Avoidance by code multiplex}
- G01S 7/0236: {Avoidance by space multiplex}
- G01S 7/2813: {Means providing a modification of the radiation pattern for cancelling noise, clutter or interfering signals, e.g. side lobe suppression, side lobe blanking, null-steering arrays (specially adapted to secondary radar systems G01S13/762; aerials or aerials systems H01Q21/29, H01Q25/00)}
- G01S 7/354: {Extracting wanted echo-signals (Doppler systems G01S13/50)}
- G01S 7/358: {using I/Q processing}
- G01S 7/4004: {of parts of a radar system}
- G06F 7/4812: {Complex multiplication}
- G06F 17/141: {Discrete Fourier transforms}
- H04B 1/0057: {using diplexing or multiplexing filters for selecting the desired band}
- H04B 1/1081: {Reduction of multipath noise (by equalising H04B7/005)}
- G01S 13/931: of land vehicles
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- H04B: TRANSMISSION

## Abstract

An exemplary radar sensing system utilizing a sparse array antenna structure provides an enhanced angular resolution to detect multiple targets with improved accuracy beyond the abilities of conventional radar. The exemplary radar system uses sparsely located antenna array elements allowing improved FOV, angular resolution, beam width, and side lobes using fewer physical antenna elements. Sparse antenna arrays allow the use of physically larger elements, larger separation between transmitter and receiver elements to reduce mutual coupling, and fewer elements to reduce necessary computations.

## Claims

### Claim 1

A radar sensing system comprising:
a transmit antenna array and a receive antenna array;
a plurality of transmitters configured to transmit radio signals, wherein each transmitter is communicatively coupled to an associated transmit antenna of the transmit antenna array;
a plurality of receivers configured to receive radio signals that include transmitted radio signals transmitted by the transmitters and reflected from objects in an environment, wherein each receiver is communicatively coupled to an associated receive antenna of the transmit antenna array;
wherein at least one of the transmit antenna array and the receive antenna array is arranged as a sparse antenna array configured to provide an angular resolution sufficient to detect multiple targets, wherein the sparse antenna array comprises antenna elements which are arranged as sparsely located antenna array elements with selected separation distances for a selected angular resolution for the transmitters and receivers, wherein the selected separation distances of the sparsely located antenna array elements define at least in part an arrangement of the sparsely located antenna array elements for the selected angular resolution, wherein the sparse antenna array comprises physical antenna elements and virtual antenna elements, wherein the sparse antenna array is configured such that the arrangement of the sparsely located antenna array elements comprises a random arrangement of virtual antenna elements of the sparse antenna array, and wherein the random arrangement of virtual antenna elements is an arrangement of virtual antenna elements randomly selected from a plurality of virtual antenna element arrangements.

### Claim 2 (depends on 1)

The radar sensing system of claim 1, wherein the arrangement of the sparsely located antenna array elements results in a selected field of view (FOV), angular resolution, beam width, and side lobes using fewer physical antenna elements than in an alternate physical antenna element arrangement defined by minimum separation distance or spacing requirements for the desired angular resolution.

### Claim 3 (depends on 2)

The radar sensing system of claim 2, wherein each of the sparsely located antenna array elements are each physically larger than the elements of the alternate physical antenna element arrangement, wherein a selected separation of transmitter elements and receiver elements of the sparsely located antenna array elements reduces mutual coupling.

### Claim 4 (depends on 1)

The radar sensing system of claim 1, wherein the sparsely located antenna array elements are arranged to form corresponding virtual elements which are spread irregularly in the azimuthal and elevation directions to minimize sidelobes.

### Claim 5 (depends on 4)

The radar sensing system of claim 4, wherein the sparsely located antenna array elements comprise physical elements which are positioned with no physical overlaps on grids formed by a minimum spacing value of design, which design is smaller than this physical size of physical element arrangement, and wherein the virtual elements are spread to a selected antenna aperture to increase angular resolution, and wherein virtual transmitter groups and virtual receiver groups are separated on the selected antenna aperture to reduce mutual coupling.

### Claim 6 (depends on 1)

The radar sensing system of claim 1, wherein each of the antennas of at least one of the transmit antenna array and the receive antenna array comprise multiple antenna elements.

### Claim 7 (depends on 6)

The radar sensing system of claim 6, wherein the multiple antenna elements of an antenna are arranged as a linear array to provide radar target resolution only in azimuth.

### Claim 8 (depends on 6)

The radar sensing system of claim 6, wherein the multiple antenna elements of an antenna are arranged as a two-dimensional array to provide target resolution in both azimuth and elevation, separately.

### Claim 9 (depends on 1)

The radar sensing system of claim 1, wherein each receiver of the plurality of receivers comprises:
a low-noise amplifier configured to amplify a received radio signal of the received radio signals;
a local oscillator configured to commonly drive I-Q mixers configured to downconvert the amplified radio signal to a quadrature (IQ) baseband signal;
a filter configured to baseband filter the baseband signal; and
a programmable gain adjustment module configured to adjust the gain of the filtered baseband signal.

### Claim 10 (depends on 1)

The radar sensing system of claim 1, wherein each of the receivers is configured to process the received radio signals to correlate received signal samples to digital values representing each transmitters modulation to produce a different number or set of correlations corresponding to different echo delays, wherein there exists one set of correlations for each receiver-transmitter combination.

### Claim 11 (depends on 1)

The radar sensing system of claim 1, wherein the transmit antenna array and the receive antenna array are a first antenna array that is time shared between the transmitters and the receivers, wherein the first antenna array is configured as the transmit antenna array when the transmitters are transmitting, and wherein the first antenna array is configured as the receive antenna array when the receivers are receiving, and wherein the transmitters and receivers operate in separate, alternating, operational periods of time.

### Claim 12

A method for selecting an arrangement of physical antenna elements and a randomly selected arrangement of virtual antenna elements for a proposed antenna array that is an optimum array arrangement selection for the proposed antenna array, wherein the method comprises:
defining selected antenna array properties comprising at least one of dimension, available number of physical antenna elements, beam width, and maximum sidelobe level;
calculating inter-element spacings and aperture lengths for the proposed antenna array as defined by a selected field-of-view (FOV) and beamwidth (BW), respectively;
calculating reference full-grid element locations as defined by the selected FOV and BW;
finding candidate element locations for a plurality of candidate element arrangements of the virtual antenna elements as defined by the selected antenna array properties and calculated inter-element spacing and aperture lengths;
randomly selected a candidate element arrangement of virtual element locations from among a plurality of candidate element arrangements of virtual element locations that meet the defined selected antenna array properties and the calculated inter-element spacings and aperture lengths;
calculating maximum sidelobe level (SLL) in the FOV for the randomly selected candidate element arrangement of the virtual antenna elements;
randomly selecting additional candidate element arrangements of virtual element locations from among the plurality of candidate element arrangements of virtual element locations for an updated candidate element arrangement of the virtual antenna elements and recalculating the SLL for each updated candidate element arrangement of the virtual antenna elements until a selected candidate element arrangement of the virtual antenna elements is reached that meets the desired FOV and BW and has a resultant SLL that is below a threshold value;
stopping the random selection of additional candidate element arrangements of virtual element locations of the virtual antenna elements and defining the selected candidate element arrangement as the selected arrangement of virtual antenna elements and physical antenna elements of the proposed antenna array when the selected candidate element arrangement of the virtual antenna elements results in a calculated SLL that is within a difference threshold value of an SLL value from the previous random candidate element arrangement of virtual element locations selection step, wherein the optimum array arrangement of virtual antenna elements and physical antenna elements is the selected arrangement of virtual antenna elements and physical antenna elements of the proposed antenna array; and
providing for a radar system, an antenna array that comprises the selected arrangement of virtual antenna elements and physical antenna elements of the proposed antenna array.

### Claim 13 (depends on 12)

The method of claim 12, wherein each of the plurality of candidate element arrangements of virtual element locations comprises one or more required element locations that are a priori determined to be required locations as defined by the optimum array arrangement, and wherein the required element locations are selected before any other element locations are selected and before a candidate element arrangement of virtual element locations is randomly selected.

### Claim 14 (depends on 12)

The method of claim 12, wherein additional antenna array properties comprise at least one of physical size limitations for transmit elements and receive elements, forbidden mutual coupling zone between transmit and receive element, and a list of required element locations that are a priori determined to be required as defined by the element arrangement.

### Claim 15 (depends on 12)

The method of claim 12, wherein additional antenna array properties comprise physical element size limitations.

### Claim 16 (depends on 12)

The method of claim 12, wherein the optimum array solution for a sparse antenna array is further defined by at least a selected FOV, BW, and number of elements, and resultant SLL, and wherein each of the randomly selected candidate element arrangements of virtual element locations are evaluated with at least the selected FOV, BW, and number of elements, and resultant SLL, such that the optimum array solution for the selected arrangement of the physical antenna elements of the proposed antenna array and its arrangement of virtual antenna elements will be defined by at least the selected FOV, BW, and number of elements, and the resultant SLL for the proposed antenna array and its arrangement of virtual antenna elements.