radar equipment

Abstract

To provide a radar system capable of improving the angle measurement accuracy or resolution.SOLUTION: The radar system includes: a transmission circuit that transmits transmission signals using multiple transmission antennas; and a receiving circuit that receives reflected wave signals that are transmission signals reflected by an object using multiple receiving antennas. Either multiple transmission antennas or multiple receiving antennas include a first antenna group arranged in a first direction and a second antenna group arranged in a second direction different from the first direction. The remaining one of multiple transmission antennas or multiple receiving antennas includes: a third antenna group arranged in a third direction with the spacing between adjacent antennas being at least one wavelength of the transmission signal, and a fourth antenna group arranged in a fourth direction different from the third direction, with the spacing between adjacent antennas being at least one wavelength of the transmission signal. The third direction is the same as the first direction, and the fourth direction is different from the second direction.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] This disclosure relates to radar equipment. [Background technology]

[0002] In recent years, research has been progressing on radar systems that use short-wavelength radar transmission signals, including microwaves or millimeter waves, which can achieve high resolution. Furthermore, in order to improve safety outdoors, there is a need for the development of radar systems (for example, called wide-angle radar systems) that can detect small objects such as pedestrians in a wide-angle range, in addition to vehicles.

[0003] One configuration for a radar system with a wide detection range is one in which an array antenna, composed of multiple antennas (also called antenna elements), receives reflected waves from a target (or object), and estimates the direction of arrival of the reflected wave (also called the angle of arrival) based on the received phase difference with respect to the element spacing (antenna spacing). (Angle of arrival estimation method; Direction of Arrival (DOA) estimation)

[0004] For example, methods for estimating the angle of arrival include the Fourier method (FFT (Fast Fourier Transform) method), or, as a method that can obtain high resolution, the Capon method, MUSIC (Multiple Signal Classification), and ESPRIT (Estimation of Signal Parameters via Rotational Invariance Techniques).

[0005] Furthermore, a radar system has been proposed that includes multiple antennas (array antennas) on both the receiving and transmitting sides, and performs beam scanning by signal processing using the transmitting and receiving array antennas (sometimes called MIMO (Multiple Input Multiple Output) radar) (see, for example, Non-Patent Document 1). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2021-081282 [Non-patent literature]

[0007] [Non-Patent Document 1] J. Li, and P. Stoica, "MIMO Radar with Colocated Antennas", Signal Processing Magazine, IEEE Vol. 24, Issue: 5, pp. 106-114, 2007 [Non-Patent Document 2] Kazuo Shirakawa et al., "3D Scan Millimeter-Wave Radar for Automobiles," Fujitsu Ten Technical Review, Vol. 30, No. 1, 2012. [Non-Patent Document 3] M. Kronauge, H.Rohling,"Fast two-dimensional CFAR procedure", IEEE Trans. Aerosp. Electron. Syst., 2013, 49, (3), pp. 1817-1823 [Non-Patent Document 4] Direction-of-arrival estimation using signal subspace modeling Cadzow, JA; Aerospace and Electronic Systems, IEEE Transactions on Volume: 28 , Issue: 1 Publication Year: 1992 , Page(s): 64 - 79 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] However, there is room for further investigation into methods to improve the angular accuracy or resolution of radar systems (e.g., MIMO radar).

[0009] Non-limiting embodiments of this disclosure contribute to providing radar devices capable of improving angular accuracy or resolution. [Means for solving the problem]

[0010] A radar device according to one embodiment of the present disclosure comprises a transmitting circuit that transmits a transmission signal using a plurality of transmitting antennas, and a receiving circuit that receives a reflected wave signal obtained by reflecting the transmission signal off an object using a plurality of receiving antennas, wherein either the plurality of transmitting antennas or the plurality of receiving antennas includes a first antenna group arranged in a first direction and a second antenna group arranged in a second direction different from the first direction, and the remaining of the plurality of transmitting antennas or the plurality of receiving antennas includes a third antenna group arranged in a third direction different from the first and second directions, wherein the distance between adjacent antennas is an interval of one wavelength or more of the transmission signal.

[0011] These comprehensive or specific embodiments may be implemented as systems, devices, methods, integrated circuits, computer programs, or recording media, or as any combination of systems, devices, methods, integrated circuits, computer programs, and recording media. [Effects of the Invention]

[0012] According to one embodiment of the present disclosure, the angular accuracy or resolution of a radar device can be improved.

[0013] Further advantages and effects of one embodiment of this disclosure will be made apparent from the specification and drawings. Such advantages and / or effects are provided by several embodiments and features described in the specification and drawings, but not all of them are necessarily provided in order to obtain one or more identical features. [Brief explanation of the drawing]

[0014] [Figure 1] Diagram showing an example of MIMO antenna placement. [Figure 2] A diagram showing an example of direction estimation results. [Figure 3] A diagram showing an example of a subarray antenna configuration. [Figure 4] A diagram showing an example of direction estimation results. [Figure 5] A diagram showing an example of direction estimation results. [Figure 6] Block diagram showing an example of radar system configuration. [Figure 7] This figure shows an example of a transmitted signal and a reflected wave signal when using chirp pulses. [Figure 8] Diagram showing an example of MIMO antenna placement related to Placement Example 1. [Figure 9] A diagram showing an example of the virtual receiving array configuration for Configuration Example 1. [Figure 10] Figure showing an example of direction estimation results related to arrangement example 1. [Figure 11] A diagram showing an example of MIMO antenna placement for comparative arrangement 1. [Figure 12] A diagram showing an example of the direction estimation results related to comparative arrangement 1. [Figure 13] Diagram showing an example of MIMO antenna placement for comparative arrangement 2. [Figure 14] A diagram showing an example of the direction estimation results related to comparative arrangement 2. [Figure 15] This figure shows an example of MIMO antenna placement according to Modification Example 1 of Placement Example 1. [Figure 16] This figure shows an example of the arrangement of a virtual receiving array related to Modification Example 1 of Arrangement Example 1. [Figure 17] This figure shows an example of the direction estimation result related to Modification Example 1 of Arrangement Example 1. [Figure 18] This figure shows another example of MIMO antenna placement related to Modification Example 1 of Placement Example 1. [Figure 19] This figure shows another example of the arrangement of the virtual receiving array related to Modification Example 1 of Arrangement Example 1. [Figure 20] This figure shows an example of MIMO antenna placement according to Modification Example 1 of Placement Example 1. [Figure 21] This figure shows an example of MIMO antenna placement related to Modification Example 2 of Placement Example 1. [Figure 22]This figure shows an example of the arrangement of a virtual receiving array related to a modified example 2 of arrangement example 1. [Figure 23] This figure shows an example of the arrangement of a virtual receiving array related to a modified example 2 of arrangement example 1. [Figure 24] This figure shows an example of the direction estimation results related to Modification Example 2 of Arrangement Example 1. [Figure 25] This figure shows an example of the direction estimation results related to Modification Example 2 of Arrangement Example 1. [Figure 26] This figure shows an example of MIMO antenna placement related to Modification Example 3 of Placement Example 1. [Figure 27] This figure shows an example of the arrangement of a virtual receiving array related to Modification Example 3 of Arrangement Example 1. [Figure 28] This figure shows an example of the direction estimation results related to Modification Example 3 of Arrangement Example 1. [Figure 29] This figure shows an example of MIMO antenna placement related to Modification Example 4 of Placement Example 1. [Figure 30] This figure shows an example of MIMO antenna placement related to Modification Example 4 of Placement Example 1. [Figure 31] This figure shows an example of MIMO antenna placement related to Modification Example 4 of Placement Example 1. [Figure 32] This figure shows an example of MIMO antenna placement related to Modification Example 4 of Placement Example 1. [Figure 33] This figure shows an example of the arrangement of a virtual receiving array related to Modification 4 of Arrangement Example 1. [Figure 34] This figure shows an example of the arrangement of a virtual receiving array related to Modification 4 of Arrangement Example 1. [Figure 35] This figure shows an example of the arrangement of a virtual receiving array related to Modification 4 of Arrangement Example 1. [Figure 36] This figure shows an example of the arrangement of a virtual receiving array related to Modification 4 of Arrangement Example 1. [Figure 37] This figure shows an example of the direction estimation results related to Modification 4 of Arrangement Example 1. [Figure 38] This figure shows an example of the direction estimation results related to Modification 4 of Arrangement Example 1. [Figure 39] This figure shows an example of the direction estimation results related to Modification 4 of Arrangement Example 1. [Figure 40] This figure shows an example of the direction estimation results related to Modification 4 of Arrangement Example 1. [Figure 41]This figure shows an example of MIMO antenna placement related to Modification Example 5 of Placement Example 1. [Figure 42] This figure shows an example of MIMO antenna placement related to Modification Example 5 of Placement Example 1. [Figure 43] This figure shows an example of MIMO antenna placement related to Modification Example 5 of Placement Example 1. [Figure 44] This figure shows an example of MIMO antenna placement related to Modification Example 5 of Placement Example 1. [Figure 45] This figure shows an example of the arrangement of a virtual receiving array related to Modification Example 5 of Arrangement Example 1. [Figure 46] This figure shows an example of the arrangement of a virtual receiving array related to Modification Example 5 of Arrangement Example 1. [Figure 47] This figure shows an example of the arrangement of a virtual receiving array related to Modification Example 5 of Arrangement Example 1. [Figure 48] This figure shows an example of the arrangement of a virtual receiving array related to Modification Example 5 of Arrangement Example 1. [Figure 49] This figure shows an example of the direction estimation results related to Modification Example 5 of Arrangement Example 1. [Figure 50] This figure shows an example of the direction estimation results related to Modification Example 5 of Arrangement Example 1. [Figure 51] This figure shows an example of the direction estimation results related to Modification Example 5 of Arrangement Example 1. [Figure 52] This figure shows an example of the direction estimation results related to Modification Example 5 of Arrangement Example 1. [Figure 53] This figure shows an example of MIMO antenna placement related to Modification Example 5 of Placement Example 1. [Figure 54] This figure shows an example of the arrangement of a virtual receiving array related to Modification Example 5 of Arrangement Example 1. [Figure 55] This figure shows an example of the direction estimation results related to Modification Example 5 of Arrangement Example 1. [Figure 56] This figure shows an example of MIMO antenna placement related to Modification Example 6 of Placement Example 1. [Figure 57] This figure shows an example of MIMO antenna placement related to Modification Example 6 of Placement Example 1. [Figure 58] This figure shows an example of MIMO antenna placement related to Modification Example 6 of Placement Example 1. [Figure 59] This figure shows an example of MIMO antenna placement according to Modification Example 7 of Placement Example 1. [Figure 60] This figure shows an example of MIMO antenna placement according to Modification Example 7 of Placement Example 1. [Figure 61] This figure shows an example of MIMO antenna placement according to Modification Example 7 of Placement Example 1. [Figure 62] This figure shows an example of MIMO antenna placement according to Modification Example 7 of Placement Example 1. [Figure 63] This figure shows an example of the arrangement of a virtual receiving array related to Modification Example 7 of Arrangement Example 1. [Figure 64] This figure shows an example of the arrangement of a virtual receiving array related to Modification Example 7 of Arrangement Example 1. [Figure 65] This figure shows an example of the arrangement of a virtual receiving array related to Modification Example 7 of Arrangement Example 1. [Figure 66] This figure shows an example of the arrangement of a virtual receiving array related to Modification Example 7 of Arrangement Example 1. [Figure 67] This figure shows an example of the direction estimation results related to Modification Example 7 of Arrangement Example 1. [Figure 68] This figure shows an example of the direction estimation results related to Modification Example 7 of Arrangement Example 1. [Figure 69] This figure shows an example of the direction estimation results related to Modification Example 7 of Arrangement Example 1. [Figure 70] This figure shows an example of the direction estimation results related to Modification Example 7 of Arrangement Example 1. [Figure 71] This figure shows an example of MIMO antenna placement related to Modification Example 8 of Placement Example 1. [Figure 72] This figure shows an example of the arrangement of a virtual receiving array related to Modification Example 8 of Arrangement Example 1. [Figure 73] This figure shows an example of the direction estimation result related to Modification Example 8 of Arrangement Example 1. [Figure 74] This diagram shows an example of the placement of the MIMO antenna and virtual receiving array according to placement condition 1. [Figure 75] This diagram shows an example of the placement of the MIMO antenna and virtual receiving array according to placement condition 1. [Figure 76] This diagram shows an example of the placement of the MIMO antenna and virtual receiving array according to placement condition 1. [Figure 77] This diagram shows an example of the placement of the MIMO antenna and virtual receiving array according to placement condition 1. [Figure 78]This diagram shows an example of the placement of the MIMO antenna and virtual receiving array according to placement condition 1. [Figure 79] This diagram shows an example of the placement of the MIMO antenna and virtual receiving array according to placement condition 1. [Figure 80] Diagram showing an example of MIMO antenna placement related to Placement Example 2. [Figure 81] This figure shows an example of the virtual receiving array configuration related to Configuration Example 2. [Figure 82] Figure showing an example of direction estimation results related to arrangement example 2. [Figure 83] This figure shows an example of MIMO antenna placement and direction estimation results related to comparative arrangement 2a. [Figure 84] This figure shows an example of MIMO antenna placement and direction estimation results related to comparative arrangement 2b. [Figure 85] This figure shows an example of MIMO antenna placement and direction estimation results related to comparative arrangement 2c. [Figure 86] This figure shows an example of MIMO antenna placement and direction estimation results related to comparative placement 2d. [Figure 87] A diagram showing an example of MIMO antenna placement related to placement example 2a. [Figure 88] A diagram showing an example of the virtual receiving array configuration related to configuration example 2a. [Figure 89] A diagram showing an example of the direction estimation results related to arrangement example 2a. [Figure 90] This figure shows an example of MIMO antenna placement related to placement example 2b. [Figure 91] This figure shows an example of the virtual receiving array configuration related to configuration example 2b. [Figure 92] Figure showing an example of direction estimation results related to arrangement example 2b. [Figure 93] This figure shows an example of MIMO antenna placement related to Modification 4 of Placement Example 2. [Figure 94] This figure shows an example of MIMO antenna placement related to Modification 4 of Placement Example 2. [Figure 95] This figure shows an example of MIMO antenna placement related to Modification 4 of Placement Example 2. [Figure 96] This figure shows an example of MIMO antenna placement related to Modification 4 of Placement Example 2. [Figure 97] This diagram shows an example of the placement of the MIMO antenna and virtual receiving array according to placement condition 2. [Figure 98] This diagram shows an example of the placement of the MIMO antenna and virtual receiving array according to placement condition 2. [Figure 99] This diagram shows an example of the placement of the MIMO antenna and virtual receiving array according to placement condition 2. [Figure 100] This diagram shows an example of the placement of the MIMO antenna and virtual receiving array according to placement condition 2. [Figure 101] This diagram shows an example of the placement of the MIMO antenna and virtual receiving array according to placement condition 2. [Modes for carrying out the invention]

[0015] MIMO radar transmits multiplexed signals (radar transmission waves) from multiple transmitting antennas (or transmitting array antennas) using methods such as time division, frequency division, or code division. MIMO radar then receives signals reflected from surrounding objects (radar reflection waves) using multiple receiving antennas (or receiving array antennas), and separates and receives the multiplexed transmission signals from each received signal. Through this process, MIMO radar can obtain a propagation path response represented by the product of the number of transmitting antennas and the number of receiving antennas, and performs array signal processing on these received signals as a virtual receiving array.

[0016] In MIMO radar, by optimizing the arrangement of antenna elements in the transmitting and receiving array antennas, it is possible to construct a virtual receiving array antenna (hereinafter referred to as a virtual receiving array, MIMO virtual receiving array, virtual receiving antenna, or virtual receiving array antenna) whose number of elements is equal to the product of the number of transmitting antenna elements. This allows for an increase in the effective aperture length of the array antenna with a small number of elements, thereby improving angular measurement accuracy or resolution.

[0017] In addition to one-dimensional scanning (angle measurement) in the vertical or horizontal direction, MIMO radar can also be applied when performing beam scanning (angle measurement) in two dimensions in the vertical and horizontal directions (see, for example, Non-Patent Document 2).

[0018] As an example, (a) of FIG. 1 shows a transmit array antenna including four transmit antennas (Tx#1 to Tx#4) arranged in the vertical direction (the vertical direction in (a) of FIG. 1), and a receive array antenna including four receive antennas (Rx#1 to Rx#4) arranged in the horizontal direction (the horizontal direction in (a) of FIG. 1). In (a) of FIG. 1, the transmit antennas are arranged at equal intervals (d V ) in the vertical direction, and the receive antennas are arranged at equal intervals (d H ) in the horizontal direction (see, for example, Non-Patent Document 2).

[0019] (b) of FIG. 1 shows a virtual receive array including the transmit and receive array antennas with the antenna arrangement shown in (a) of FIG. 1. The virtual receive array shown in (b) of FIG. 1 is composed of a 16-element virtual antenna (VA#1 to VA#16) in which four antennas are arranged in a rectangular shape in the horizontal direction and four antennas are arranged in the vertical direction. In (b) of FIG. 1, the element intervals in the horizontal and vertical directions of the virtual receive array are d H , d V respectively. The aperture lengths A H , A V in the horizontal and vertical directions of the virtual receive array are A H = 3d H , A V = 3d V respectively.

[0020] (a) and (b) of FIG. 2 show Fourier beam patterns directed in the horizontal 0° and vertical 0° directions when the element interval d H = 0.5λ in the horizontal direction and the element interval d V = 0.5λ in the vertical direction in the antenna arrangement of the MIMO radar shown in (a) of FIG. 1. Here, λ represents the wavelength of the radar carrier wave.

[0021] As shown in Figures 2(a) and 2(b), a main beam (main lobe) is formed in the horizontal 0° and vertical 0° directions. Here, the narrower the beam width of the main beam, the better the angular separation performance for multiple targets. For example, in Figures 2(a) and 2(b), a beam width of approximately 26° corresponds to a power value of 3 dB. Also, as shown in Figures 2(a) and 2(b), side lobes are generated around the main beam. In radar systems, side lobes can be a source of false detection as virtual images. Therefore, the lower the peak level of the side lobes, the lower the probability of false detection as virtual images in the radar system. In Figures 2(a) and 2(b), for example, the power ratio of the side lobes to the peak level normalized by the peak level of the main beam (Peak Sidelobe Level Ratio (PSLR)) is approximately -13 dB (however, this is when equal amplitude beamweighting is used).

[0022] To increase the detection range in radar systems, using a high-gain antenna is effective. For example, antenna gain can be improved by narrowing the antenna's directivity (beam width). Antenna directivity narrows as the aperture of the antenna widens. Therefore, narrowing the antenna's directivity tends to increase the antenna size.

[0023] For example, in radar equipment mounted on vehicles (also called automotive radar), a sub-array antenna, which consists of multiple antenna elements arranged vertically, may be used to narrow the vertical directivity. By narrowing the vertical directivity with a sub-array antenna, the vertical antenna gain can be improved, and reflected waves from unwanted directions such as the road surface can be reduced.

[0024] The vertical direction refers to the height direction of the vehicle on which the radar device is mounted (or installed). The horizontal direction refers to the direction of the vehicle's straight-line movement, the direction perpendicular to the vehicle's straight-line movement, or the direction perpendicular to the vehicle's height direction.

[0025] Furthermore, the vertical direction may be the direction of gravity, for example, when a radar device is mounted (or installed) on a signaling device, and the horizontal direction may be the direction perpendicular to the direction of gravity.

[0026] For example, Figure 3 shows an example of a subarray in which eight planar patch antennas are arranged vertically (vertical direction in Figure 3) and one horizontally (horizontal direction in Figure 3). In Figure 3, H ANT This indicates the vertical antenna size, W ANT The horizontal antenna size is indicated. Note that the subarray configuration is not limited to the configuration shown in Figure 3; for example, the number of elements in the vertical and horizontal directions may differ from the numbers shown in Figure 3.

[0027] Here, when a sub-array antenna is used as an antenna element constituting a transmitting array antenna or a receiving array antenna, the antenna elements of the array antenna cannot be spaced closer together than the size of the sub-array antenna. For example, when the antenna elements constituting a sub-array antenna are arranged vertically, the size of the sub-array antenna can be one wavelength or more. Therefore, for example, when a sub-array antenna is used vertically in the MIMO radar shown in Figure 1(a) (when it is sub-arrayed vertically), the vertical element spacing d V This will extend the wavelength beyond one wavelength.

[0028] Figures 4 and 5 show the vertical element spacing d in the transmit / receive antenna arrangement of the MIMO radar shown in Figure 1(a). V When the wavelength (λ) is set to 1 wavelength or longer, an example of a Fourier beam pattern directed towards the horizontal 0° and vertical 0° directions is shown. Note that in Figures 4 and 5, the directivity of individual antenna elements in a vertical sub-array is not considered.

[0029] In Figure 4, the vertical element spacing d v =λ, horizontal element spacing d H = 0.5λ, and in Figure 5, the vertical element spacing d V =2λ, horizontal element spacing d H = 0.5λ.

[0030] As shown in Figures 4 and 5, the main beam (main lobe) is oriented in the horizontal 0° and vertical 0° directions, and compared to the side lobes in Figure 2(a) and Figure 2(b), for example, higher-level side lobes (e.g., grating lobes) are generated in the vertical direction around the main beam. In Figures 4 and 5, the ratio of the peak level of the grating lobe to the peak level of the main lobe (peak-side lobe ratio) is 0 dB. Also, in Figure 5(d V In Figure 4(d) = 2λ), V Compared to λ, the angular spacing at which high levels of side lobes (e.g., grating lobes) occur in the vertical direction becomes narrower. That is, the element spacing d in the vertical direction V The wider the field of view, the narrower the angular interval at which side lobes (e.g., grating lobes) are generated.

[0031] Thus, the larger the vertical antenna size of a radar system, the wider the vertical spacing between elements, making it more likely for grating lobes to occur at angles relatively close to the main beam. Therefore, if the detection angle range assumed by the radar system is wider than the angle at which grating lobes occur, the probability of the radar system mistakenly detecting false peaks caused by grating lobes as targets increases within the detection angle range, potentially degrading the radar system's detection performance.

[0032] Furthermore, even if a grating lobe is outside the detection angle range assumed by the radar system, if the power of the reflected wave arriving from the direction of the grating lobe is sufficiently large, the radar system is likely to mistakenly detect that a target has arrived within its field of view, potentially degrading the radar system's detection performance. For example, if the element spacing is one wavelength or more, a grating lobe will always occur within a range of ±90 degrees, making it easy for radar systems with a narrow field of view to experience degradation of radar detection performance due to false detections caused by grating lobes.

[0033] On the other hand, for example, the wider the element interval in the vertical direction, the narrower the beam width in the vertical direction, and the angular measurement accuracy or angular resolution in the vertical direction of the radar device can be improved. For example, comparing the element intervals in the vertical direction in FIGS. 2, 4, and 5, they are 0.5λ, λ, and 2λ respectively. When comparing the main lobes in the Fourier beam pattern, it can be confirmed that the wider the element interval in the vertical direction, the narrower the beam width in the vertical direction, and a sharper beam is formed. Thus, the narrower the beam width in the vertical direction, the more the angular measurement accuracy or angular resolution in the vertical direction of the radar device can be improved.

[0034] Similarly, for example, the wider the element interval in the horizontal direction, the narrower the beam width in the horizontal direction, and the angular measurement accuracy or angular resolution in the horizontal direction of the radar device can be improved. On the other hand, the wider the element interval in the horizontal direction, the more likely grating lobes are to occur. For example, when the detection angle range assumed by the radar device is wider than the angle at which grating lobes occur, the radar device has an increased probability of erroneously detecting a false peak caused by a grating lobe as a target within the detection angle range, and the detection performance of the radar device may deteriorate.

[0035] Therefore, in one non-limiting embodiment of the present disclosure, an antenna arrangement capable of suppressing grating lobes while widening the element interval in at least one of the vertical and horizontal directions will be described. By realizing such an antenna arrangement, the angular measurement accuracy or resolution can be improved with a smaller number of antennas.

[0036] Note that the radar device according to an embodiment of the present disclosure may be mounted on a moving body such as a vehicle, for example. The radar device mounted on the moving body can be used, for example, as a sensor for an advanced driver assistance system (ADAS: Advanced Driver Assistance System) that enhances collision safety or for monitoring the surroundings of the moving body during autonomous driving.

[0037] Furthermore, a radar device according to one embodiment of the present disclosure may be mounted on a relatively high structure, such as a roadside utility pole or traffic light. Such a radar device can be used, for example, as a sensor in a support system that enhances the safety of passing vehicles or pedestrians.

[0038] Furthermore, the uses of radar equipment are not limited to these, and it may be used for other purposes as well.

[0039] Hereinafter, an embodiment according to one example of the present disclosure will be described in detail with reference to the drawings. In the embodiment, the same reference numerals are used for the same components, and their descriptions will be omitted as they would be redundant.

[0040] The following describes a radar system in which a transmitting branch sends out different transmission signals that are code-division multiplexed from multiple transmitting antennas, and a receiving branch separates and processes each transmission signal (in other words, a MIMO radar configuration). However, the configuration of the radar system is not limited to this; it may also be a configuration in which a transmitting branch sends out different transmission signals that are frequency-division multiplexed from multiple transmitting antennas, and a receiving branch separates and processes each transmission signal. Similarly, the radar system may also be configured in which a transmitting branch sends out transmission signals that are time-division multiplexed from multiple transmitting antennas, and a receiving branch processes the reception.

[0041] Similarly, the transmitting branch may send out different transmission signals that are Doppler division multiplexed from multiple transmitting antennas, and the receiving branch may separate and process each transmission signal. Or, similarly, the transmitting branch may send out transmission signals that are multiplexed using a combination of at least two methods, such as code division multiplexing, time division multiplexing, and Doppler division multiplexing, from multiple transmitting antennas, and the receiving branch may separate and process each transmission signal.

[0042] Furthermore, the configuration of a radar system using frequency-modulated pulse waves, such as chirp pulses (also known as fast chirp modulation), will be described below as an example. However, the modulation method is not limited to frequency modulation. For example, one embodiment of this disclosure is also applicable to radar systems using single pulses or coded pulses.

[0043] (Embodiment 1) [Radar system configuration] Figure 6 is a block diagram showing an example configuration of the radar device 10 according to this embodiment.

[0044] The radar device 10 includes a radar transmitting unit (transmitting branch) 100 and a radar receiving unit (receiving branch) 200.

[0045] The radar transmitter 100 generates a radar signal (radar transmission signal) and transmits to multiple transmitting antennas 106 (for example, N tx A transmitting array antenna, composed of (1) units, is used to transmit radar transmission signals at a specified transmission period.

[0046] The radar receiver 200 receives the reflected wave signal, which is the radar transmission signal reflected by a target (not shown), using a receiving array antenna that includes a plurality of receiving antennas 202 (for example, Na). The radar receiver 200 processes the reflected wave signal received by each receiving antenna 202 to perform signal processing, for example, detecting the presence or absence of a target, or estimating the arrival distance, Doppler frequency (in other words, relative velocity), and direction of arrival of the reflected wave signal, and outputs information related to the estimation result (in other words, positioning information).

[0047] The target is an object detected by the radar device 10, and includes, for example, vehicles (including four-wheeled and two-wheeled vehicles), people, blocks, or curbs.

[0048] [Configuration of radar transmitter 100] The radar transmission unit 100 includes a radar transmission signal generation unit 101, a code generation unit 104, a phase rotation unit 105, and a transmitting antenna 106.

[0049] The radar transmission signal generation unit 101 generates radar transmission signals. The radar transmission signal generation unit 101 includes, for example, a modulation signal generation unit 102 and a VCO (Voltage Controlled Oscillator) 103. The components of the radar transmission signal generation unit 101 will be described below.

[0050] The modulation signal generation unit 102 generates a sawtooth-shaped modulation signal (in other words, a modulation signal for VCO control) for each radar transmission period Tr.

[0051] Based on the modulated signal output from the modulated signal generation unit 102, the VCO 103 generates a frequency modulated signal (hereinafter referred to as, for example, a frequency chirp signal or chirp signal) as shown in Figure 7(a), and outputs it to the phase rotation unit 105 and the radar receiving unit 200 (mixer unit 204, which will be described later).

[0052] The code generation unit 104 generates a different code for each transmitting antenna 106 that performs code multiplexing transmission. The code generation unit 104 outputs the phase rotation amount corresponding to the generated code to the phase rotation unit 105. The code generation unit 104 also outputs information about the generated code to the radar receiving unit 200 (output switching unit 209, which will be described later).

[0053] The phase rotation unit 105 applies a phase rotation amount, input from the code generation unit 104, to the chirp signal input from the VCO 103, and outputs the phase-rotated signal to the transmitting antenna 106. For example, the phase rotation unit 105 includes, for example, a phase shifter and a phase modulator (not shown). The output signal of the phase rotation unit 105 is amplified to a specified transmission power and radiated into space from each transmitting antenna 106. In other words, the radar transmission signal is code-multiplexed and transmitted from multiple transmitting antennas 106 by applying a phase rotation amount corresponding to the code.

[0054] Next, an example of a code (for example, an orthogonal code) set in the radar device 10 will be described.

[0055] The code generation unit 104 generates different codes for each transmission antenna 106 that performs code multiplexing transmission, for example.

[0056] For example, hereinafter, the number of transmission antennas 106 that perform code multiplexing transmission is set to "Nt", and the code multiplexing number is set to "N" CM ". In FIG. 6, N CM = Nt.

[0057] The code generation unit 104 selects N [[ID={18]] allcode (hereinafter, sometimes described as N allcode (Loc)) orthogonal codes from among the N CM orthogonal codes included in a code sequence of code length (in other words, the number of code elements) Loc (for example, an orthogonal code sequence having an orthogonal relationship with each other (or simply referred to as a code or an orthogonal code)) and sets them as codes for code multiplexing transmission.

[0058] For example, the code multiplexing number N CM is set to be less than or equal to the number of orthogonal codes N allcode , and N CM ≦ N allcode . For example, the N CM orthogonal codes of code length Loc are represented as Code ncm = [OC ncm (1), OC ncm (2),..., OC ncm (Loc)]. Here, "OC ncm (noc)" represents the noc-th code element in the ncm-th orthogonal code Code ncm . Also, "ncm" represents the index of the orthogonal code used for code multiplexing, and ncm = 1,..., N [[ID=

[50] ] CM . Also, "noc" is the index of the code element, and noc = 1,..., Loc.

[0059] As described above, the N CMThe orthogonal codes are, for example, mutually orthogonal codes (in other words, uncorrelated codes). For example, a Walsh-Hadamard code sequence may be used for an orthogonal code sequence. The code length of a Walsh-Hadamard code is a power of 2, and each code length contains the same number of orthogonal codes as the code length. For example, Walsh-Hadamard codes with code lengths of 2, 4, 8, or 16 contain 2, 4, 8, or 16 orthogonal codes, respectively.

[0060] In the following example, the number of codes N CM The code length Loc of each orthogonal code sequence is set to satisfy equation (1) below.

number

[0061] Here, ceil[x] is the operator (ceiling function) that outputs the smallest integer greater than or equal to x. In the case of a Walsh-Hadamard code of code length Loc, N allcode The relationship (Loc)=Loc holds. For example, Walsh-Hadamard codes with code lengths Loc=2, 4, 8, or 16 contain 2, 4, 8, or 16 orthogonal codes, respectively, so N allcode (2) = 2, N allcode (4) = 4, N allcode (8)=8, and N allcode (16)=16 holds true. The code generation unit 104 generates, for example, N included in the Walsh-Hadamard code of code length Loc. allcode Of the (Loc) codes, N CM Use orthogonal codes.

[0062] Below, each code multiplex number N CM An example of orthogonal codes in this context will be described.

[0063] For example, the code multiplicity N CM If =3, the code generation unit 104 determines, for example, three orthogonal codes from among Walsh-Hadamard codes with code length Loc=4 to be used as codes for code multiplexing transmission. For example, the code generation unit 104 may select Code1=WH4(3)=[1,1, -1, -1], Code2=WH4(4)=[1,-1, -1, 1], and Code3=WH4(2)=[1,-1, 1, -1].

[0064] For example, the code generation unit 104 generates N Walsh-Hadamard codes with code length Loc shown in equation (2). CM N orthogonal codes may be selected as codes for code multiplexing transmission. In this case, N CM ≤Loc=N allcode (Loc)

number

[0065] Furthermore, the elements that make up an orthogonal code sequence are not limited to real numbers; complex values ​​may also be included.

[0066] Furthermore, the code may be any other orthogonal code different from the Walsh-Hadamard code. For example, the code may be an orthogonal M-sequence code or a pseudo-orthogonal code.

[0067] Above, each code multiplex number N CM An example of orthogonal codes in this context was described.

[0068] Next, an example of a phase rotation amount based on the code for code multiplexing transmission generated in the code generation unit 104 will be described.

[0069] The radar device 10 performs code multiplexing transmission using different orthogonal codes for each of the transmitting antennas Tx#1 to Tx#Nt that perform code multiplexing transmission. Therefore, the code generation unit 104 generates an orthogonal code Code to be assigned to the nth transmitting antenna Tx#ncm in the mth transmission period Tr. ncm Phase rotation amount ψ based on ncm (m) is set and output to the phase rotation unit 105. Here, ncm = 1, ..., N CM That is the case.

[0070] For example, the phase rotation amount ψ ncm (m) is the orthogonal code Code, as shown in equation (3) below, for each transmission period of code length Loc times. ncm Each of the Loc code elements OC ncm (1), ..., OC ncm A phase quantity equivalent to (Loc) is applied cyclically.

number

[0071] Here, angle(x) is an operator that outputs the radian phase of a real number x, where angle(1)=0, angle(-1)=π, angle(j)=π / 2, and angle(-j)=-π / 2. j is the imaginary unit. Also, OC_INDEX is the orthogonal code sequence Code ncm This is an orthogonal code element index that indicates the elements, and it cyclically varies from 1 to Loc in the range shown in equation (4) below for each transmission period (Tr).

number

[0072] Here, mod(x,y) is the modulo operator, a function that outputs the remainder after x is divided by y. Also, m = 1, ..., Nc. Nc is a predetermined number of transmission cycles used by the radar device 10 for radar positioning (hereinafter referred to as the "number of radar transmission signals"). The radar device 10 also transmits a number of radar transmission signals Nc that is an integer multiple of Loc (for example, Ncode times). For example, Nc = Loc × Ncode.

[0073] Furthermore, the code generation unit 104 outputs the orthogonal code element index OC_INDEX to the output switching unit 209 of the radar receiver unit 200 for each transmission cycle (Tr).

[0074] The phase rotation unit 105 is, for example, N txEach of the transmitting antennas 106 is equipped with a corresponding phase shifter or phase modulator. The phase rotation unit 105, for example, for each transmission period Tr, receives a phase rotation amount ψ from the code generation unit 104 in relation to the chirp signal input from the radar transmission signal generation unit 101. ncm (m) is assigned to each.

[0075] For example, the phase rotation unit 105 assigns an orthogonal code to the nth transmission antenna Tx#ncm for each chirp signal input from the radar transmission signal generation unit 101 for each transmission period Tr. ncm Phase rotation amount ψ based on ncm Assign (m). Here, ncm = 1, ..., N CM Therefore, m=1,..,Nc.

[0076] N tx The output from the phase rotation unit 105 for each transmitting antenna 106 is, for example, amplified to a predetermined transmission power, and then N tx The signal is radiated into space from each of the 106 transmitting antennas (for example, a transmitting array antenna).

[0077] As an example, the number of transmitting antennas N Tx =3, and code multiplicity N CM This section explains the case of code multiplexing transmission at =3. Note that the number of transmitting antennas Nt and the code multiplexing number N are given. CM These values ​​are not limited to these.

[0078] For example, the phase rotation amounts ψ1(m), ψ2(m), and ψ3(m) are output from the code generation unit 104 to the phase rotation unit 105 for each m-th transmission period Tr.

[0079] The first phase rotation unit 105 (ncm=1) (in other words, the phase shifter corresponding to the first transmitting antenna 106 (for example, Tx#1)) applies a phase rotation to the chirp signal generated in the radar transmission signal generation unit 101 for each transmission period Tr, as shown in equation (5) below. The output of the first phase rotation unit 105 is transmitted from the transmitting antenna Tx#1. Here, cp(t) represents the chirp signal of the mth transmission period Tr.

number

[0080] Similarly, the second phase rotation unit 105 (ncm=2) applies a phase rotation to the chirp signal generated in the radar transmission signal generation unit 101 for each transmission period Tr, as shown in equation (6) below. The output of the second phase rotation unit 105 is transmitted from the transmitting antenna Tx#2.

number

[0081] Similarly, the third phase rotation unit 105 (ncm=3) applies a phase rotation to the chirp signal generated in the radar transmission signal generation unit 101 for each transmission period Tr, as shown in equation (7). The output of the third phase rotation unit 105 is transmitted from the transmitting antenna Tx#3.

number

[0082] Furthermore, when the radar device 10 performs radar positioning continuously, it sets an orthogonal code for each radar positioning (for example, every Nc transmission cycles (Nc × Tr)). ncm The sign used may be set to be variable.

[0083] The above describes an example configuration of the radar transmission unit 100.

[0084] [Configuration of radar receiver 200] In Figure 6, the radar receiver 200 is equipped with Na receiving antennas 202 (also represented as Rx#1 to Rx#Na, for example) and constitutes an array antenna. The radar receiver 200 also includes Na antenna system processing units 201-1 to 201-Na, a CFAR (Constant False Alarm Rate) unit 211, a code multiplexing / decomposition unit 212, and a direction estimation unit 213.

[0085] Each receiving antenna 202 receives a reflected wave signal, which is a radar transmission signal reflected from the target, and outputs the received reflected wave signal as a received signal to the corresponding antenna system processing unit 201.

[0086] Each antenna system processing unit 201 includes a receiving radio unit 203 and a signal processing unit 206.

[0087] The receiving radio unit 203 includes a mixer unit 204 and an LPF (low-pass filter) 205. The mixer unit 204 mixes the received reflected wave signal with the chirp signal, which is the transmission signal input from the radar transmission signal generation unit 101. The LPF 205 applies LPF processing to the output signal of the mixer unit 204, thereby outputting a beat signal with a frequency corresponding to the delay time of the reflected wave signal. For example, as shown in the lower part of Figure 7, the difference frequency between the frequency of the transmitted chirp signal (transmitted frequency modulated wave) and the frequency of the received chirp signal (received frequency modulated wave) is obtained as the beat frequency.

[0088] Each antenna system processing unit 201-z (where z=1 to Na) has a signal processing unit 206 comprising an AD conversion unit 207, a beat frequency analysis unit 208, an output switching unit 209, and a Doppler analysis unit 210.

[0089] The signal output from the LPF205 (for example, a beat signal) is converted into discrete sample data by the AD conversion unit 207 in the signal processing unit 206.

[0090] The beat frequency analysis unit 208 analyzes the N obtained within a defined time range (range gate) for each transmission period Tr. data The discrete sample data is subjected to FFT processing. As a result, the signal processing unit 206 outputs a frequency spectrum in which a peak appears at the beat frequency corresponding to the delay time of the reflected wave signal (radar reflected wave). The beat frequency analysis unit 208 may multiply the FFT processing by a window function coefficient, such as a Han window or a Hamming window. The radar device 10 can suppress side lobes that occur around the beat frequency peak by using a window function coefficient. data If the number of discrete sample data is not a power of two, the beat frequency analysis unit 208 may perform the FFT with an FFT size of a power of two, for example, by including zero-padding data.

[0091] Here, the beat frequency response output from the beat frequency analysis unit 208 in the z-th signal processing unit 206 obtained by transmitting the m-th chirp pulse is RFT z (f b Let it be expressed as , m). Here, f b This represents the beat frequency index and corresponds to the index (bin number) of the FFT. For example, f b =0,…,(N data ( / 2)-1, z=1,...,Na, m=1,...,N C This is the beat frequency index f. b The smaller the value, the smaller the delay time of the reflected wave signal (in other words, the closer the distance to the target) the beat frequency indicates.

[0092] Also, the beat frequency index f b The distance information R(f) is calculated using the following equation (8). b It is acceptable to convert it to ). Therefore, in the following, the beat frequency index f b to "distance index f b It is also called "".

number

[0093] Here, B w represents the frequency modulation bandwidth within the range gate in the chirp signal, and C0 represents the speed of light.

[0094] Based on the orthogonal code element index OC_INDEX output from the code generation unit 104, the output switching unit 209 selectively switches and outputs the output of the beat frequency analysis unit 208 for each transmission period to the OC_INDEX-th Doppler analysis unit 210 among the Loc Doppler analysis units 210. In other words, the output switching unit 209 selects the OC_INDEX-th Doppler analysis unit 210 in the m-th transmission period Tr.

[0095] The signal processing unit 206 has Loc Doppler analysis units 210-1 to 210-Loc. For example, data is input to the noc-th Doppler analysis unit 210 every Loc transmission periods (Loc×Tr) by the output switching unit 209. Therefore, the noc-th Doppler analysis unit 210 uses the data of Ncode transmission periods out of Nc transmission periods (for example, the beat frequency response RFT z (f b , m)) to perform Doppler analysis for each distance index f b . Here, noc is the index of the code element, and noc = 1,..., Loc.

[0096] For example, when Ncode is a power of 2 value, FFT processing may be applied in the Doppler analysis. In this case, the FFT size is Ncode, and the maximum Doppler frequency without aliasing derived from the sampling theorem is ±1 / (2Loc×Tr). Also, the Doppler frequency interval of the Doppler frequency index f s is 1 / (Ncode×Loc×Tr), and the range of the Doppler frequency index f s is f s = -Ncode / 2,..., 0,..., Ncode / 2 - 1.

[0097] For example, the output VFT of the Doppler analysis unit 210 of the z-th signal processing unit 206 z noc (f b , f s ) is shown in the following equation (9). Here, j is the imaginary unit, and z = 1 to Na. [Equation]

[0098] Also, when Ncode is not a power of 2, for example, zero-padding data can be included to perform FFT processing with a data size (FFT size) of a power of 2. For example, when the FFT size in the Doppler analysis unit 210 including zero-padding data is N codewzero the output VFT of the Doppler analysis unit 210 in the z-th signal processing unit 206 z noc (f b , f s ) is shown in the following equation (10). [Equation]

[0099] Here, noc is the index of the symbol element, and noc = 1,..., Loc. Also, the FFT size is N codewzero and the maximum Doppler frequency without aliasing derived from the sampling theorem is ±1 / (2Loc×Tr). Also, the Doppler frequency interval of the Doppler frequency index f s is 1 / (N codewzero ×Loc×Tr), and the range of the Doppler frequency index f s is f s =-N codewzero / 2,..., 0,..., N codewzero / 2 - 1.

[0100] Hereinafter, as an example, the case where Ncode is a power of 2 will be described. When zero-padding is used in the Doppler analysis unit 210, in the following description, Ncode is replaced with N codewzeroBy replacing it with this, it can be applied similarly and the same effect can be obtained.

[0101] Furthermore, the Doppler analysis unit 210 may multiply by window function coefficients, such as a Han window or a Hamming window, during the FFT processing. By applying a window function, the radar device 10 can suppress side lobes that occur around the beat frequency peak.

[0102] The processing in each component of the signal processing unit 206 has been described above.

[0103] In Figure 6, the CFAR unit 211 uses the outputs of Loc Doppler analysis units 210 of each of the 1st to Nath signal processing units 206 to perform CFAR processing (in other words, adaptive threshold determination) and obtains a distance index f that gives a peak signal. b_cfar and Doppler frequency index f s_cfar Extract it.

[0104] The CFAR unit 211, for example, as shown in equation (11) below, is the output VFT of the Doppler analysis unit 210 of the 1st to Nath signal processing unit 206. z noc (f b , f s The power is added to perform a CFAR process that is either a two-dimensional CFAR process consisting of a distance axis and a Doppler frequency axis (corresponding to relative velocity), or a CFAR process that combines a one-dimensional CFAR process. For the CFAR process that combines a two-dimensional CFAR process or a one-dimensional CFAR process, for example, the process disclosed in Non-Patent Document 3 may be applied.

number

[0105] The CFAR unit 211 adaptively sets a threshold and determines the distance index f that results in a received power greater than the threshold. b_cfar , Doppler frequency index f s_cfar , and received power information PowerFT(f b_cfar , f s_cfar The following is output to the code multiplexing and separation unit 212:

[0106] Next, an example of the operation of the code multiplexing separation unit 212 will be described.

[0107] The code multiplexing unit 212, for example, extracts the distance index f in the CFAR unit 211. b_cfar and Doppler frequency index f s_cfar Based on this, the code multiplexed signal separation process is performed.

[0108] For example, the code multiplexing unit 212 uses the distance index f extracted in the CFAR unit 211, as shown in equation (12) below. b_cfar and Doppler frequency index f s_cfar The Doppler component VFTALL is the output of the corresponding Doppler analysis unit 210. z (f b_cfar , f s_cfar Sign separation is performed on the result.

number

[0109] Here, ToMul z ncm (f b_cfar , f s_cfar ) is the distance index f of the Doppler analysis unit 210 in the z-th antenna system processing unit 201. b_cfar and Doppler frequency index f s_cfar Orthogonal code for the output ncm This is the output (e.g., the code-separated result) of a code-multiplexed signal using [a specific method / tool]. Note that z=1,...,Na and ncm=1,...,N CM That is the case. Also, in equation (12),

number

number

number

[0110] In equation (12), α(f s_cfar ) represents the "Doppler phase correction vector". Doppler phase correction vector α(f s_cfar ) is, for example, the Doppler frequency index f extracted in the CFAR section 211. s_cfar However, when the output range of the Doppler analysis unit 210 (in other words, the Doppler range) is set to exclude Doppler aliasing, the Doppler phase rotation caused by the time difference in Doppler analysis between Loc Doppler analysis units 210 is corrected.

[0111] For example, the Doppler phase correction vector α(f s_cfar The Doppler phase correction vector α(f) shown in equation (14) is expressed as follows: s_cfar ) is, for example, the output VFT of the first Doppler analysis unit 210. z 1 (f b_cfar , f s_cfar Based on the Doppler analysis time of the second Doppler analysis unit 210, the output VFT z 2 (f b_cfar , f s_cfar ) Output VFT of the Loc-th Doppler analysis unit 210 z Loc (f b_cfar , f s_cfar The Doppler frequency index f is generated by the time delay of Tr, 2Tr, ..., (Loc-1)Tr in each of the following: s_cfar This is a vector whose elements are Doppler phase correction coefficients that correct the phase rotation in the Doppler component.

number

[0112] Furthermore, in equation (12), VFTALL z (f b_cfar , f s_cfar For example, as shown in equation (15), the output VFT of Loc Doppler analysis units 210 in the z-th antenna system processing unit 201 is obtained. z noc (f b , f s ) Among these, the distance index f extracted in the CFAR section 211 b_cfar and Doppler frequency index f s_cfar VFT corresponding component z noc (f b_cfar , f s_cfar Represent ) (where noc=1,…,Loc) in vector form.

number

[0113] The above describes an example of the operation of the code multiplexing and separation unit 212. The configuration shown in Figure 6 describes the operation of the code multiplexing and separation unit 212 assuming that the target detected by the radar device 10 is within the range of ±1 / (2Loc×Tr), which is derived from the sampling theorem.

[0114] The configuration of the radar device 10 is not limited to the configuration shown in Figure 6, and the detectable Doppler frequency range can be further expanded. For example, the output of the Doppler analysis unit disclosed in Figure 1 of Patent Document 1 may be provided with an aliasing determination unit that determines whether the output contains Doppler frequency components exceeding the maximum Doppler frequency ±1 / (2Loc×Tr), and an aliasing determination process may be performed. The result of this determination may then be used to perform code multiplexing in the code multiplexing separation unit.

[0115] However, in order to perform the reversal determination process in the reversal determination unit of Patent Document 1, the code multiplexing number N of the code generated by the code generation unit in the radar transmission unit is required. CM The orthogonal code number N allcode To make it less than N CM <N allcode In other words, the code length Loc of an orthogonal code is equal to the code multiplicity N. CM Make it larger than that.

[0116] By using this configuration, the detectable Doppler range can be further expanded, for example, the maximum detectable Doppler frequency can be set to ±1 / (2×Tr). Therefore, it becomes possible to operate the code multiplexing and decoupling unit assuming that the targets detected by the radar system are within the Doppler frequency range of ±1 / (2×Tr).

[0117] In the radar device 10, for example, an arrangement of the transmitting antenna 106 and receiving antenna 202 may be adopted that suppresses grating lobes or side lobes and improves angular resolution by increasing the array gain and increasing the aperture length with a virtual receiving array.

[0118] The following describes an example of the antenna arrangement of the transmitting antenna 106 and the receiving antenna 202, and an example of the direction estimation process in the direction estimation unit 213 when each arrangement example is applied.

[0119] Furthermore, in the following arrangement examples and modifications, the arrangement of the transmitting antenna 106 may be replaced with the arrangement of the receiving antenna 202, and the arrangement of the receiving antenna 202 may be replaced with the arrangement of the transmitting antenna 106. In the radar device 10, even if the antenna arrangements of the transmitting antenna 106 and the receiving antenna 202 are swapped, the same effects as in the following arrangement examples can be obtained.

[0120] Furthermore, the arrangement may also be one in which the horizontal and vertical directions are swapped in the following arrangement examples and modifications. When the horizontal and vertical directions are swapped in the antenna arrangement, the radar device 10 can obtain the effect of swapping the horizontal and vertical directions in the following arrangement example.

[0121] In the example configuration, the horizontal and vertical directions do not need to be precisely aligned. The entire configuration may be tilted at a predetermined angle while maintaining the relative positional relationship between the transmitting and receiving antennas included in the configuration. In this case as well, the relative positional relationship between the transmitting and receiving antennas included in the configuration is maintained, and the same effect can be obtained.

[0122] The antenna arrangement of the radar device 10 (for example, MIMO antenna arrangement) may be an arrangement that satisfies the following arrangement conditions, for example.

[0123] [Placement condition 1] N Tx The transmitting antennas 106 are arranged in a predetermined orientation at intervals of one wavelength or more. If three or more antennas are arranged, they may be arranged at equal intervals. Tx Some of the individual transmitting antennas 106 may be arranged at different intervals. Also, the radar device 10 is N Tx It may include transmitting antennas other than the 106 transmitting antennas.

[0124] The Na receiving antennas 202 include a "first oblique antenna group" arranged in a "first oblique direction" and a "second oblique antenna group" arranged in a "second oblique direction," and the first oblique direction and the second oblique direction are not parallel. In other words, the first oblique direction and the second oblique direction are different directions. The radar device 10 may also include receiving antennas other than the Na receiving antennas 202. Furthermore, some of the Na receiving antennas 202 may be arranged at different intervals.

[0125] The first oblique antenna group and the second oblique antenna group may each include at least two receiving antennas 202.

[0126] Furthermore, the first diagonal direction and the second diagonal direction do not have to coincide with the predetermined arrangement direction of the transmitting antenna 106. In other words, the first diagonal direction (for example, the first direction) in which the first group of diagonal antennas (for example, the first antenna group) is arranged, the second diagonal direction (for example, the second direction) in which the second group of diagonal antennas (for example, the second antenna group) is arranged, and multiple (for example, N Tx The directions in which the individual transmitting antennas 106 are positioned (for example, corresponding to the third direction) may be different from each other.

[0127] By arranging the first and second oblique antenna groups, which satisfy arrangement condition 1, at arbitrary positions, grating lobes can be suppressed. For example, as shown in the following arrangement example or modification, by arranging the first and second oblique antenna groups so that their horizontal positions do not overlap, antenna elements with large vertical dimensions can be arranged.

[0128] The following describes an example of placement condition 1. Below, we will describe an example of a placement that satisfies placement condition 1, and an example of the direction estimation result obtained by computer simulation in that placement example.

[0129] In the following, we will describe an example of the orientation in which multiple transmitting antennas 106 are arranged, specifically in a direction that coincides with the horizontal direction. However, the orientation of the transmitting antennas 106 is not limited to that which coincides with the horizontal direction. For example, Modification 8 of Arrangement Example 1, described later, shows an example of arrangement in a direction different from the horizontal direction.

[0130] <Layout example 1> Figure 8 shows an example of the arrangement of the transmitting antenna 106 (e.g., denoted as Tx) and the receiving antenna 202 (e.g., denoted as Rx) according to arrangement condition 1 (e.g., an example of a MIMO antenna arrangement). In Figure 8, the scales on the horizontal and vertical axes are, for example, the basic horizontal interval D. H , and the basic vertical spacing D VThis will be the case. Note that the scales on the horizontal and vertical axes are the same for MIMO antenna configurations in the other examples below. For example, D H and D V A spacing of 0.5 wavelengths is sufficient.

[0131] In the example shown in Figure 8, the number of transmitting antennas N Tx There are 6 (e.g., Tx#1, Tx#2, Tx#3, Tx#4, Tx#5, and Tx#6), and the number of receiving antennas Na is 8 (e.g., Rx#1, Rx#2, Rx#3, Rx#5, Rx#6, Rx#7, and Rx#8).

[0132] In Figure 8, N Tx The six transmitting antennas Tx#1~#6 are arranged at equal intervals horizontally (for example, in a predetermined arrangement direction) with a spacing of 1.5 wavelengths. In other words, in arrangement example 1, multiple (for example, N Tx All of the transmitting antennas 106 may be arranged in a predetermined direction (for example, corresponding to the third direction). Also, in arrangement example 1, for example, the spacing between adjacent transmitting antennas of the multiple transmitting antennas 106 may be at least one wavelength of the radar transmission signal.

[0133] Furthermore, in Figure 8, Na = 8 receiving antennas Rx#1~#8 include the first oblique antenna group Rx#1~#4 arranged in the first oblique direction and the second oblique antenna group Rx#5~#8 arranged in the second oblique direction. Here, in Figure 8, the first oblique direction and the second oblique direction are not parallel but different directions, satisfying arrangement condition 1. Also, as shown in Figure 8, the first oblique direction, the second oblique direction, and the arrangement direction of the transmitting antenna 106 (e.g., the horizontal direction) are not parallel and are different from each other. Also, for example, as shown in Figure 8, the first oblique direction and the second oblique direction are different directions with respect to the vertical and horizontal directions.

[0134] For example, the first oblique antenna group Rx#1 to #4 shown in Figure 8 are shifted horizontally from left to right in the figure by 0.5 wavelengths, and simultaneously shifted downward vertically by 0.5 wavelengths. Similarly, the second oblique antenna group Rx#5 to #8 shown in Figure 8 are shifted horizontally from right to left in the figure by 0.5 wavelengths, and simultaneously shifted downward vertically by 0.5 wavelengths.

[0135] Thus, in Figure 8, the antenna arrangement of the first oblique antenna group positioned in the first oblique direction and the antenna arrangement of the second oblique antenna group positioned in the second oblique direction are symmetrical with respect to a line perpendicular to the third direction, or a line parallel to the vertical direction. In other words, the first oblique antenna group Rx#1~#4 and the second oblique antenna group Rx#5~#8 are arranged in a way that is inverted symmetry (or left-right inverted symmetry, or mirror symmetry) in the horizontal direction.

[0136] Furthermore, in Figure 8, the spacing between adjacent antennas is equal in each of the multiple transmitting antennas Tx#1~#6, the first oblique antenna group Rx#1~#4, and the second oblique antenna group Rx#5~#8.

[0137] Figure 9 shows an example of the arrangement of a virtual receiving array obtained by the antenna arrangement shown in Figure 8. In Figure 9, the scales on the horizontal and vertical axes are, for example, the basic horizontal interval D. H , and the basic vertical spacing D V This will be the case. The scales on the horizontal and vertical axes are the same for the virtual receiver array configurations in the other examples below.

[0138] Here, the arrangement of the virtual receiving array may be expressed as shown in equation (16) below, based on, for example, the position of the transmitting antenna 106 that constitutes the transmitting array antenna (e.g., the position of the feed point) and the position of the receiving antenna 202 that constitutes the receiving array antenna (e.g., the position of the feed point).

number

[0139] Here, the position coordinates of the transmitting antenna 106 (e.g., Tx#n) that constitutes the transmitting array antenna are (X T_#n ,Y T_#n )(For example, n=1,.., N Tx ) is expressed as, and the position coordinates of the receiving antenna 202 (for example, Rx#m) that constitutes the receiving array antenna are (X R_#m ,Y R_#m (For example, m=1,.., Na) and the position coordinates of the virtual antenna VA#k that constitutes the virtual receiving array are (X V_#k ,Y V_#k )(For example, k=1,.., N Tx It is written as ×Na).

[0140] In equation (16), for example, VA#1 is represented as the position reference (0,0) of the virtual receive array.

[0141] For example, from the arrangement of transmitting antennas Tx#1 to Tx#6 and receiving antennas Rx#1 to Rx#8 as shown in Figure 8, the position coordinates of the virtual antennas VA#1 to #48 that constitute the virtual receiving array antenna can be calculated from equation (16). As an example, the position coordinates of virtual antennas VA#1 to #16 are (X V_#1 ,Y V_#1 )=(0,0), (X V_#2 ,Y V_#2 )=(D H ,- D V ), (X V_#3 ,Y V_#3 )=(2D H , -2D V ), (X V_#4 ,Y V_#4 )=(3D H ,-3D V ), (X V_#5 ,Y V_#5 )=(18D H , 0), (X V_#6 ,Y V_#6 )=(17D H , -D V ), (X V_#7 ,Y V_#7 )=(16D H , -2D V ), (X V_#8 ,YV_#8 )=(15 D H , -3D V ), (X V_#9 ,Y V_#9 )=(3D H ,0), (X V_#10 ,Y V_#10 )=(4D H , -D V ), (X V_#11 ,Y V_#11 )=(5D H , -2D V ), (X V_#12 ,Y V_#12 )=(6D H , -3D V ), (X V_#13 ,Y V_#13 )=(21D H , 0), (X V_#14 ,Y V_#14 )=(20D H , -D V ), (X V_#15 ,Y V_#15 )=(19D H , -2D V ), (X V_#16 ,Y V_#16 )=(18D H , -3D V )

[0142] In Figure 9, VA#16 and VA#44 are placed in the same position and overlap. Also, VA#8 and VA#36 are placed in the same position and overlap.

[0143] Here, in the case of Figures 8 and 9, D H and D V The following describes the case where each value is set to 0.5λ, but for example, each value may be set to a value of approximately 0.45λ to 0.8λ (for example, any value in the range of 0.5 to 0.8 times the wavelength of the radar transmission signal). H and D V These can be set according to the horizontal or vertical field of view of the radar device 10. For example, if the horizontal or vertical field of view is in the range of ±70 to 90 degrees, D H Or D VIt may be set to about 0.5λ. Alternatively, if the horizontal or vertical field of view is in the range of ±20 to 40 degrees, D H Or D V The interval may be wider, for example, about 0.7λ. H and D V The same settings apply to subsequent configuration examples (or variations). Note that λ represents the wavelength of the carrier frequency of the radar transmission signal. For example, when using a chirp signal as the radar transmission signal, λ is the wavelength of the center frequency in the frequency sweep bandwidth of the chirp signal.

[0144] Next, we will describe an example of the direction estimation process in the direction estimation unit 213 when the above-described antenna arrangement is applied.

[0145] In Figure 1, the direction estimation unit 213 receives the distance index f from the code multiplexing unit 212. b_cfar and Doppler frequency index f s_cfar The sign separation result for the output of the Doppler analysis unit 210 corresponding to DeMul z ncm (f b_cfar , f s_cfar Based on this, the target direction estimation process is performed.

[0146] For example, the direction estimation unit 213 calculates the virtual received array correlation vector h(f) shown in equation (17). b_cfar , f s_cfar It generates a ) and performs direction estimation processing.

[0147] Virtual Receive Array Correlation Vector h(f b_cfar , f s_cfar ) is the number of transmitting antennas N Tx N is the product of the number of receiving antennas, Na. Tx Contains ×Na elements. Virtual receive array correlation vector h(f b_cfar , f s_cfar This is used to perform direction estimation based on the phase difference between each receiving antenna 202 for the reflected wave signal from the target. Here, z = 1, ..., Na.

[0148] For example, in the MIMO antenna configuration of Configuration Example 1, in the example of Figure 8, N Tx Since =6 and Na=8, the virtual received array correlation vector h(f b_cfar , f s_cfar ) contains 48 elements, each corresponding to the received signal at VA#1 to VA48 in the virtual receiver array configuration shown in Figure 9. For example, VA#1 is h(f b_cfar , f s_cfar The first element of the column vector elements of ) DeMul1 1 (f b_cfar , f s_cfar ) corresponds to the received signal of VA#2, ..., and the 48th element corresponds to the received signal of VA#48.

number

[0149] Next, the direction estimation unit 213 calculates, for example, the virtual receive array correlation vector h(f) which is the received signal of the virtual receive array composed of the transmit and receive antenna arrangement described above. b_cfar , f s_cfar The horizontal and vertical direction estimation process is performed using ).

[0150] For example, the direction estimation unit 213 calculates the virtual receive array correlation vector h(f) as shown in equation (18) below. b_cfar , f s_cfar ) is corrected for the phase deviation and amplitude deviation between the transmitting array antennas and the receiving array antennas by an array correction value h_cal. [y] By multiplying by this, the virtual received array correlation vector h corrected for inter-antenna deviation is obtained. _after_cal (f b_cfar , f s_cfar The output is ). Then, the direction estimation unit 213 performs direction estimation processing in the horizontal and vertical directions based on the phase difference between the receiving antennas of the incoming reflected wave. Here, y=1,.., (N Tx It is ×Na).

number

number

[0151] Furthermore, CA includes array correction coefficients that correct phase and amplitude deviations between transmitting and receiving antennas, and coefficients that reduce the effects of inter-element coupling between antennas (N Tx ×Na) is the following square matrix. If coupling between antennas in the virtual receiving array is negligible, CA becomes a diagonal matrix, and the diagonal elements are array correction values ​​h_cal that correct for the phase deviation and amplitude deviation between transmitting and receiving antennas. [y] It includes.

[0152] virtual receive array correlation vector h corrected for inter-antenna deviation _after_cal (f b_cfar , f s_cfar ) is N Tx This results in a column vector with ×Na elements. In the following explanation of the direction estimation process, each element is denoted as follows. Each element is a complex value and represents the amplitude and phase components received by each virtual receiving antenna.

number

[0153] The direction estimation unit 213 calculates the virtual received array correlation vector h corrected for the inter-antenna deviation. _after_cal (f b_cfar , f s_cfar The direction estimation in the horizontal and vertical directions is performed using the following: In the horizontal and vertical direction estimation, the direction estimation unit 213 uses, for example, the incoming direction estimation evaluation function value P(θ, Φ, f b_cfar , f s_cfar The spatial profile is calculated by making the azimuth direction θ and elevation angle direction Φ within a defined angular range variable. The direction estimation unit 213 extracts a predetermined number of maximum peak directions of the calculated spatial profile in descending order, and outputs the azimuth direction and elevation angle direction of each maximum peak as estimated arrival direction values ​​(e.g., positioning output).

[0154] Note that the estimated direction of arrival evaluation function value P(θ, Φ, f b_cfar , f s_cfar There are various methods for estimating the direction of arrival, depending on the direction of arrival algorithm. For example, the estimation method using an array antenna disclosed in Non-Patent Document 4 may be used.

[0155] For example, the beamformer method can be expressed as shown in equation (19), where the superscript H is the Hermitian transpose operator. Other methods such as Capon and MUSIC can also be applied in a similar manner.

number

[0156] Here, the azimuth direction θ u This is a vector obtained by varying the range θmin to θmax within the azimuth range for direction estimation by the azimuth interval β1. For example, θ u It will be set as follows: θ u =θmin + uβ1, u=0,…, NU NU = floor[(θmax-θmin) / β1] Here, floor(x) is a function that returns the largest integer value not exceeding the real number x.

[0157] Also, in the elevation direction Φ v This is a vector obtained by varying the range Φmin~Φmax within the azimuth range for direction estimation by the azimuth interval β2. For example, Φ v It will be set as follows: Φ v =Φmin + vβ2, v=0,…, NV NV = floor[(Φmax - Φmin) / β2]

[0158] In this embodiment, the radar device 10 is configured, for example, with a virtual receiving array arrangement VA#1, ..., VA#(N Tx Based on ×Na), the direction vector a(θ) u ,Φ v The direction vector a(θ) may be calculated in advance. u,Φ v ) is a complex response of a virtual receiving array antenna when radar reflected waves arrive from the azimuth direction θ and the elevation angle direction Φ, with (N) as its elements. Tx ×Na) is the following column vector. The complex response a(θ) of a virtual receiving array antenna. u ,Φ v ) represents the phase difference calculated geometrically and optically based on the spacing between elements in the antenna.

[0159] For this example, we will use the direction perpendicular to the front of the antenna surface shown in Arrangement Example 1 as the reference (azimuth θ = 0 degrees, elevation angle Φ = 0 degrees).

[0160] Next, we will explain an example of the direction estimation result (computer simulation result) when the antenna arrangement described in the above-mentioned arrangement example 1 is applied.

[0161] Figure 10 shows the MIMO array configuration of configuration example 1 (D H = 0.5λ, D V The direction estimation results when the beamformer method is used as the direction estimation algorithm for the direction estimation unit 213 are shown using (= 0.5λ). In Figure 10, as an example, the output of the direction estimation evaluation function values ​​in the horizontal ±90 degree range and the vertical ±90 degree range, when the target true value is set to 0 degrees horizontally and 0 degrees vertically, are plotted. Here, the results shown are for each transmitting antenna and receiving antenna to be omnidirectional, and the direction estimation results (computer simulation results) in the following other examples also show results for omnidirectional antennas.

[0162] Figure 10(a) is a grayscale color map showing normalized power values ​​in a two-dimensional direction, with the horizontal axis representing the horizontal direction and the vertical axis representing the vertical direction. Figure 10(b) is a grayscale color map of Figure 10(a), with the horizontal axis representing the horizontal direction and the vertical axis representing the normalized power values. In Figure 10, the normalized power values ​​may be shown, for example, as decibel values ​​(dB) normalized by peak power, and the same applies to plotting the direction estimation results in the other examples below.

[0163] In the example arrangement shown in Figure 8, the transmitting antennas 106 are spaced at intervals of 1.5 wavelengths (1.5λ) in the horizontal direction, and the receiving antennas 202 are spaced at intervals of 6 wavelengths or more in the horizontal direction. In the virtual receiving array arrangement shown in Figure 9, each virtual antenna is spaced at intervals of 1 wavelength or more in the horizontal direction. Therefore, the antenna spacing is such that grating groves can occur. For example, if the target direction is 0 degrees horizontally, grating groves can occur at -41.8 degrees and 41.8 degrees horizontally.

[0164] In example configuration 1, the receiving antennas 202 are arranged, for example, at intervals of 6.5 wavelengths or more in the horizontal direction. Even if the virtual antennas in the virtual receiving array configuration are spaced at intervals of 1 wavelength or more in the horizontal direction, grating lobes can still be suppressed. For example, as shown in Figure 10, it can be seen that grating lobes are suppressed in a direction different from the peak direction of the target true value direction.

[0165] The principle of suppressing grating lobes by the MIMO antenna configuration in Configuration Example 1 will be explained below.

[0166] Figure 11 shows the antenna configuration (hereinafter referred to as "comparison configuration 1") using the first oblique antenna group Rx#1~#4 of the receiving antenna 202 shown in Figure 8, for comparison with configuration example 1. Figure 12 shows the direction estimation results using the beamformer method when comparison configuration 1 is applied. In Figure 12, as in Figure 10, the output of the arrival direction estimation evaluation function values ​​in the horizontal ±90 degree range and the vertical ±90 degree range, with the target true value set to horizontal 0 degrees and vertical 0 degrees, is plotted.

[0167] Furthermore, as shown in comparative configuration 1, the virtual receiving array configuration when using the first oblique antenna group Rx#1~#4 among the receiving antennas 202 of configuration example 1 corresponds to VA#1~#4, #9~#12, #17~#20, #25~#28, #33~#36, and #41~#44 in Figure 9.

[0168] Similarly, Figure 13 shows the antenna configuration (hereinafter referred to as "comparison configuration 2") when using the second oblique antenna group Rx#5~#8 of the receiving antenna 202 shown in Figure 8 for comparison with configuration example 1. Figure 14 shows the direction estimation results using the beamformer method when comparison configuration 2 is applied. In Figure 14, as in Figure 10, the output of the arrival direction estimation evaluation function values ​​in the horizontal ±90 degree range and the vertical ±90 degree range, with the target true value set to horizontal 0 degrees and vertical 0 degrees, is plotted.

[0169] Furthermore, as shown in comparative arrangement 2, the virtual receiving array arrangement when using the second oblique antenna group Rx#5~#8 among the receiving antennas 202 of arrangement example 1 corresponds to VA#5~#8, #13~#16, #21~#24, #29~#32, #37~#40, and #45~#48 in Figure 9.

[0170] For example, when using the first oblique antenna group Rx#1~#4 of the receiving antenna 202 in the arrangement example 1 shown in Figure 8, as in comparison arrangement 1 shown in Figure 11, the direction estimation results (for example, Figures 12(a) and (b)) obtained by the direction estimation unit 213 using the beamformer method as the direction of arrival estimation algorithm for the target true value (for example, 0 degrees horizontal, 0 degrees vertical) show that grating lobes occur in two directions (-41.8 degrees horizontal, -41.8 degrees vertical) and (+41.8 degrees horizontal, +41.8 degrees vertical).

[0171] Furthermore, for example, when using the second oblique antenna group Rx#5~#8 of the receiving antenna 202 in arrangement example 1 shown in Figure 8, as in comparative arrangement 2 shown in Figure 13, the direction estimation results (for example, Figures 14(a) and (b)) obtained by the direction estimation unit 213 using the beamformer method as the direction of arrival estimation algorithm for the target true value (for example, 0 degrees horizontal, 0 degrees vertical) show that grating lobes occur in two directions (-41.8 degrees horizontal, +41.8 degrees vertical) and (+41.8 degrees horizontal, -41.8 degrees vertical).

[0172] Here, the orientation of the receiving antennas Rx#1~#4 (corresponding to, for example, the first oblique antenna group) in comparison configuration 1 shown in Figure 11 is different from the orientation of the receiving antennas Rx#5~#8 (corresponding to, for example, the second oblique antenna group) in comparison configuration 2 shown in Figure 13, and they are not parallel. Therefore, as shown in Figures 12 and 14, comparison configuration 1 and comparison configuration 2 have the property that the horizontal and vertical two-dimensional angular directions in which the grating lobe is generated do not coincide and are shifted.

[0173] On the other hand, as shown in Figures 12 and 14, the angular direction of the main lobe corresponding to the target true value (e.g., horizontal 0 degrees, vertical 0 degrees) is the same in comparison configuration 1 and comparison configuration 2.

[0174] Therefore, as shown in Figure 8, in arrangement example 1, which includes the first and second oblique antennas, the direction of generation (two-dimensional angular direction) of the grating lobes generated in comparative arrangement 1, which includes the first group of oblique antennas, and the direction of generation of the grating lobes generated in comparative arrangement 2, which includes the second group of oblique antennas, do not coincide and tend to be dispersed. For this reason, in arrangement example 1, as shown in Figures 10(a) and (b), the peak level in the direction of the grating lobes tends to be suppressed compared to the peak in the direction of the target true value.

[0175] For example, as shown in Figure 8, if the arrangement directions of the first and second oblique antenna groups are horizontally inverted symmetric, then the virtual receiving array arrangements corresponding to comparison arrangement 1 and comparison arrangement 2 will also be horizontally inverted symmetric. As a result, in both comparison arrangement 1 and comparison arrangement 2, the horizontal and vertical two-dimensional directions in which the grating lobe occurs will be horizontally inverted symmetric, and as shown in Figures 12 and 14, the angular displacement in the horizontal and vertical two-dimensional directions in which the grating lobe occurs will become larger.

[0176] Therefore, in arrangement example 1, for example, as shown in Figure 8, if the arrangement directions (e.g., diagonal directions) of the first and second diagonal antenna groups are horizontally inverted symmetric, then, as shown in Figure 10, the direction in which grating groves are generated will be horizontally inverted symmetric, and the spacing (or shift) of the suppressed grating groves will tend to be larger.

[0177] Such an arrangement in which the orientations of the first and second oblique antenna groups are horizontally inverted symmetric is preferable, for example, when the number of antennas in the radar device 10 is small. For example, the fewer the number of antennas in the radar device 10, the wider the beamwidth of the main beam in direction estimation tends to be. Therefore, when the directions of the grating groves to be suppressed are close together, the fewer the number of antennas in the radar device 10, the greater the beamwidth expansion, which can cause the grating grove power to overlap and increase the grating grove power. Therefore, the fewer the number of antennas in the radar device 10, the worse the grating grove suppression performance becomes, and the higher the probability of false detection in the radar device 10. Thus, when the number of antennas in the radar device 10 is small, for example, by arranging the orientations of the first and second oblique antenna groups in horizontally inverted symmetric, the overlap of grating grove power can be suppressed, thereby improving the grating grove suppression performance.

[0178] Furthermore, as shown in Figure 8, in arrangement example 1, the transmitting antenna 106 is arranged in a single horizontal line, and the receiving antenna 202 is arranged in a single diagonal line. In other words, as shown in Figure 8, in arrangement example 1, both the transmitting antenna 106 and the receiving antenna 202 are arranged so that their antenna elements do not overlap in the vertical direction. For this reason, in arrangement example 1, it is possible to arrange antenna elements with a larger vertical size (for example, a size of one wavelength or more).

[0179] Therefore, in arrangement example 1, for example, by using a subarray antenna configured by arranging multiple antenna elements in the vertical direction, the vertical antenna gain can be improved by narrowing the vertical directivity.

[0180] The distance between the transmitting antenna 106 and the receiving antenna 202 may be sufficiently wider than the size of the antenna elements, or they may be arranged in a horizontally shifted configuration so that they do not overlap vertically.

[0181] As described above, in arrangement example 1, antenna elements of any vertical size (e.g., vertical) can be used, and it is also an antenna arrangement that can suppress grating lobes that occur in the virtual receiving array.

[0182] Furthermore, the same grating lobe suppression effect can be obtained even if the first and second oblique antenna groups shown in Figure 8 are placed in any location. For example, in arrangement example 1, by setting the arrangement of the first oblique antenna group Rx#1 to Rx#4 and the second oblique antenna group Rx#5 to Rx#8 so that their horizontal positions do not overlap, it becomes possible to arrange antenna elements with larger vertical sizes.

[0183] The above describes an example of the direction estimation results (computer simulation results) in arrangement example 1, and the effects of arrangement example 1.

[0184] In Figure 6, the direction estimation unit 213 outputs, for example, the direction estimation result, and further outputs the distance index f as the positioning result. b_cfar Distance information based on (e.g., information transformed based on equation (8)), target Doppler frequency index f s_cfar The system may output target Doppler velocity information based on this. The direction estimation unit 213 may output the positioning results to, for example, a vehicle control device in the case of an in-vehicle radar (not shown), or an infrastructure control device in the case of an infrastructure radar.

[0185] Doppler frequency index f s_cfar The relative velocity component v d (f s_cfarTo convert to ), the following equation (20) may be used. Here, λ is the wavelength of the carrier frequency of the RF signal output from the transmitting radio unit (not shown). Also, Δ f Δ is the Doppler frequency interval in the FFT processing in the Doppler analysis unit 210. For example, in this embodiment, Δ f = 1 / {Loc × N} code ×T r}

number

[0186] The above describes an example of the operation of the radar device 10.

[0187] As described above, in arrangement example 1, the receiving antenna 202 of the radar device 10 includes, for example, a first oblique antenna group arranged in a first oblique direction and a second oblique antenna group arranged in a second oblique direction. Furthermore, in the antenna arrangement of the radar device 10, the first oblique direction, the second oblique direction, and the predetermined direction (for example, the horizontal direction) in which the multiple transmitting antennas 106 are arranged are different directions from each other.

[0188] This antenna configuration allows the radar device 10 to use antenna elements of any vertical size (e.g., vertical size) in a MIMO array configuration, and also suppresses grating lobes that occur in the virtual receiving array.

[0189] Furthermore, in arrangement example 1, as described above, the grating lobe suppression effect can be obtained due to the difference in the arrangement direction of the first and second oblique antenna groups in the receiving antenna 202. For this reason, in arrangement example 1, for example, the element spacing of the transmitting antenna 106 can be set arbitrarily. Similarly, in arrangement example 1, the spacing between the first and second oblique antenna groups can be set arbitrarily. As a result, for example, the aperture length of the virtual receiving array can be expanded depending on the setting of at least one of the element spacing of the transmitting antenna 106 and the spacing between the first and second oblique antenna groups, thereby improving the vertical and horizontal angle measurement accuracy and angle separation performance of the radar device 10.

[0190] Therefore, according to arrangement example 1, grating lobes can be suppressed, and the angle measurement accuracy or resolution of the radar device 10 can be improved.

[0191] In arrangement example 1, additional antenna elements may be added to at least one of the transmitting antenna 106 and the receiving antenna 202 compared to the antenna configuration shown in Figure 8. In other words, each of the transmitting antenna 106 and the receiving antenna 202 of the radar device 10 should include the antenna elements arranged in Figure 8. In this case, for example, a virtual antenna is added additively at the position shown in equation (16). For example, by adding an antenna element to at least one of the transmitting antenna 106 and the receiving antenna 202, another virtual antenna is added to the virtual receiving array arrangement shown in Figure 9. Even in antenna arrangements including such arrangement example 1, the effects of arrangement example 1 described above are retained, and the same effects as arrangement example 1 can be obtained.

[0192] For example, additional antennas may be added to the antenna configuration of Arrangement Example 1. Adding antennas further reduces the grating lobe or side lobe level suppressed by Arrangement Example 1, thereby reducing false detections during angle measurement by the radar device 10 and improving angle measurement performance. The addition of antennas can be applied similarly to subsequent arrangement examples or modifications, yielding similar effects.

[0193] Furthermore, in the MIMO array configuration of Configuration Example 1, a configuration in which the horizontal and vertical directions are swapped may be applied. In this case, the virtual receiving array configuration will be one in which the horizontal and vertical directions are swapped, and angle separation performance with the horizontal and vertical directions swapped will be obtained. Note that the swapping of the horizontal and vertical directions in the MIMO array configuration can also be applied to subsequent configuration examples or modifications, and the virtual receiving array configuration in subsequent configuration examples will be one in which the horizontal and vertical directions are swapped.

[0194] The following describes a variation of arrangement example 1.

[0195] [Modification 1 of arrangement example 1] In Modification 1 of Arrangement Example 1, for example, the distance between the first oblique antenna group and the second oblique antenna group (for example, the minimum distance) is N Tx The aperture length may be wider than that of the individual transmitting antenna 106.

[0196] For example, in the case of arrangement example 1, as shown in Figure 8, the minimum spacing between the first oblique antenna group Rx#1~#4 and the second oblique antenna group Rx#5~#8 (for example, the spacing between Rx#4 and Rx#8) is N Tx It is narrower than the aperture length of each transmitting antenna 106 (for example, the distance between Tx#1 and Tx#6).

[0197] In Modification 1 of Arrangement Example 1, for example, as shown in Figure 15 (hereinafter also referred to as "Arrangement Example 1-1"), the minimum spacing between the first oblique antenna group Rx#1~#4 and the second oblique antenna group Rx#5~#8 (for example, the spacing between Rx#4 and Rx#8) is N Tx The aperture length may be wider than that of the individual transmitting antennas 106 (for example, corresponding to the third antenna group) (for example, the distance between Tx#1 and Tx#6).

[0198] For example, in the case of arrangement example 1-1 shown in Figure 15, the minimum distance between the first oblique antenna group and the second oblique antenna group (the distance between Rx#4 and Rx#8) is N Tx=The spacing is set to be wider than the aperture length of the six transmitting antennas 106 (for example, the distance between Tx#1 and Tx#6). Note that, in the arrangement example 1-1 shown in Figure 15, the setting for the spacing between the first oblique antenna group and the second oblique antenna group may be the same as in arrangement example 1 (for example, Figure 8).

[0199] Based on the arrangement of transmitting antennas Tx#1 to Tx#6 and receiving antennas Rx#1 to Rx#8 as shown in Figure 15, the position coordinates of the virtual antennas VA#1 to #48 that constitute the virtual receiving array antenna are calculated based on equation (16).

[0200] Figure 16 shows an example of the arrangement of a virtual receiving array obtained by the antenna arrangement shown in Figure 15. As shown in Figure 16, the horizontal aperture length of the virtual receiving array is wider compared to Figure 9.

[0201] Next, we will explain an example of the direction estimation result (computer simulation result) when applying the antenna arrangement described in the above-mentioned arrangement example 1-1.

[0202] Figure 17 shows the MIMO array configuration of configuration example 1-1 (D H = 0.5λ, D V The direction estimation results when the beamformer method is used as the direction estimation algorithm for the direction estimation unit 213 are shown using (= 0.5λ). In Figure 17, as an example, the output of the direction estimation evaluation function values ​​in the horizontal ±90 degree range and the vertical ±90 degree range when the target true value is set to 0 degrees horizontally and 0 degrees vertically are plotted.

[0203] Figure 17(a) is a grayscale color map showing normalized power values ​​in a two-dimensional direction, with the horizontal axis representing the horizontal direction and the vertical axis representing the vertical direction. Figure 17(b) is a grayscale color map of Figure 17(a), with the horizontal axis representing the horizontal direction and the vertical axis representing the normalized power values. In Figure 17, the normalized power values ​​may be shown, for example, as decibel values ​​(dB) normalized by peak power.

[0204] As shown in Figures 17(a) and (b), in Arrangement Example 1-1, similar to Arrangement Example 1 (for example, Figure 10), the peak level in the grating lobe direction is suppressed compared to the peak in the target true value direction.

[0205] Furthermore, in arrangement example 1-1, compared to arrangement example 1, the virtual receiving array arrangement (for example, the aperture length of the virtual receiving array) is wider in the horizontal direction. As shown in Figure 17, the peak in the target true value direction becomes sharper in the horizontal direction compared to Figure 10, thus enabling an improvement in the horizontal angle measurement accuracy or estimation accuracy of the radar device 10.

[0206] As shown in Figure 17, in Arrangement Example 1-1, a side lobe of approximately -10 dB may occur next to the peak in the target true value direction (horizontally), compared to Arrangement Example 1 (for example, Figure 10). The occurrence of this side lobe is due, for example, to an increased spacing between the first and second oblique antenna groups (for example, the minimum spacing) compared to Arrangement Example 1.

[0207] Thus, in arrangement example 1-1, increasing the distance between the first and second oblique antenna groups improves the horizontal angle measurement accuracy or estimation accuracy, while increasing the lateral (horizontal) sidelobe level of the peak in the target true value direction. For example, the distance between the first and second oblique antenna groups (e.g., the minimum distance) may be set within a suitable range depending on requirements such as the detection target assumed by the radar device 10.

[0208] Furthermore, the placement direction (e.g., diagonal direction) of the first and second oblique antenna groups may be reversed relative to the arrangement in Figure 15, or they may be inverted left and right (e.g., horizontally), or they may be inverted up and down (e.g., vertically). In these cases as well, the same effects as in the arrangement example 1-1 described above can be obtained. The changes in the placement direction of the first and second oblique antenna groups can also be applied to subsequent arrangement examples.

[0209] As an example, Figure 18 shows an arrangement in which the orientations of the first and second oblique antenna groups in arrangement example 1-1 shown in Figure 15 are reversed (hereinafter referred to as "arrangement example 1-1a").

[0210] In the case of arrangement example 1-1 shown in Figure 15, the first and second oblique antenna groups are arranged horizontally symmetrically. Therefore, arrangement example 1-1a shown in Figure 18 is an arrangement in which the orientation of the first and second oblique antenna groups of arrangement example 1-1 is reversed horizontally, and also an arrangement in which the first and second oblique antenna groups of arrangement example 1-1 are reversed vertically.

[0211] Based on the arrangement of transmitting antennas Tx#1 to Tx#6 and receiving antennas Rx#1 to Rx#8 shown in Figure 18, the position coordinates of the virtual antennas VA#1 to #48 that constitute the virtual receiving array antenna are calculated based on equation (16). For example, Figure 19 shows an example of the arrangement of the virtual receiving array obtained by the antenna arrangement shown in Figure 18.

[0212] Furthermore, in arrangements such as those in arrangement example 1-1 or arrangement example 1-1a, even if the vertical size of the transmitting antenna 106 is large, the receiving antenna 202 can be placed on both sides of the transmitting antenna 106 (for example, both sides in the horizontal direction), thus reducing the antenna mounting area.

[0213] [Modification 2 of arrangement example 1] In Modification 2 of Arrangement Example 1, for example, the distance between the first oblique antenna group and the second oblique antenna group (e.g., the minimum distance) may be closer than in Arrangement Example 1. Also, in Modification 2 of Arrangement Example 1, for example, one antenna included in the multiple receiving antennas 202 may be included in both the first oblique antenna group and the second oblique antenna group. In other words, the first oblique antenna group and the second oblique antenna group may include one or more antennas that are shared.

[0214] For example, in the case of arrangement example 1, as shown in Figure 8, the minimum spacing between the first oblique antenna group Rx#1~#4 and the second oblique antenna group Rx#5~#8 (for example, the spacing between Rx#4 and Rx#8) is N Tx It is narrower than the aperture length of each transmitting antenna 106 (for example, the distance between Tx#1 and Tx#6).

[0215] In the modified example 2 of arrangement example 1, for example, as shown in Figure 20 (hereinafter referred to as "arrangement example 1-2a"), the minimum distance between the first oblique antenna group Rx#1~#4 and the second oblique antenna group Rx#5~#8 (for example, the distance between Rx#4 and Rx#8) may be brought even closer compared to Figure 8.

[0216] Alternatively, in Modification 2 of Arrangement Example 1, for example, as shown in Figure 21 (hereinafter referred to as "Arrangement Example 1-2b"), some antennas (for example, Rx#4) of the first oblique antenna group Rx#1~#4 and the second oblique antenna group Rx#4~#7 may overlap.

[0217] For example, in the case of arrangement example 1-2a shown in Figure 20, N Tx The transmitting antennas Tx#1~#6 are spaced 4.5 wavelengths apart (for example, 9D H They are arranged at equal intervals in the horizontal direction, and the minimum distance between the first and second oblique antenna groups (for example, the distance between Rx#4 and Rx#8) is the horizontal basic interval D H It is set to this. In Figure 20, the aperture length of the receiving antenna 202 (Rx#1~#8) in the horizontal direction (for example, 7D H ) is the element spacing of the transmitting antenna 106 (for example, 9D H It is narrower than ).

[0218] Also, for example, in the case of arrangement example 1-2b shown in Figure 21, N Tx The transmitting antennas Tx#1~#6 are spaced 3.5 wavelengths apart (for example, 7D HThe receiving antennas Rx#1~#7 are arranged at equal intervals horizontally, and in the Na=7 receiving antennas Rx#1~#7, the first oblique antenna group includes Rx#1~#4, and the second oblique antenna group includes Rx#4~#7. In Figure 21, the aperture length (e.g., 6D) of the receiving antennas 202 (Rx#1~#7) is shown horizontally. H ) is the element spacing of the transmitting antenna 106 (for example, 7D H It is narrower than ).

[0219] Based on the arrangement of transmitting antennas Tx#1 to Tx#6 and receiving antennas Rx#1 to Rx#8 as shown in Figure 20, the position coordinates of the virtual antennas VA#1 to #48 that constitute the virtual receiving array antenna are calculated based on equation (16). Figure 22 shows an example of the arrangement of the virtual receiving array obtained by the antenna arrangement shown in Figure 20.

[0220] Furthermore, based on the arrangement of transmitting antennas Tx#1 to Tx#6 and receiving antennas Rx#1 to Rx#7 as shown in Figure 21, the position coordinates of the virtual antennas VA#1 to #42 that constitute the virtual receiving array antenna are calculated based on equation (16). Figure 23 shows an example of the arrangement of the virtual receiving array obtained by the antenna arrangement shown in Figure 21.

[0221] Next, we will explain an example of the direction estimation result (computer simulation result) when applying the antenna arrangements described in the above-mentioned arrangement examples 1-2a and 1-2b.

[0222] Figures 24 and 25 show the respective MIMO array configurations (D) for configuration example 1-2a and configuration example 1-2b. H = 0.5λ, D V The direction estimation results when the beamformer method is used as the direction estimation algorithm for the direction estimation unit 213 are shown using (= 0.5λ). As an example, Figures 24 and 25 plot the output of the direction estimation evaluation function values ​​in the horizontal ±90 degree range and the vertical ±90 degree range, when the target true value is set to 0 degrees horizontally and 0 degrees vertically.

[0223] Figures 24(a) and 25(a) are grayscale color maps showing normalized power values ​​in a two-dimensional direction, with the horizontal axis representing the horizontal direction and the vertical axis representing the vertical direction. Figures 24(b) and 25(b) are grayscale color maps showing the normalized power values ​​in a two-dimensional direction, with the horizontal axis representing the horizontal direction and the vertical axis representing the normalized power values. In Figures 24 and 25, the normalized power values ​​may be shown, for example, as decibel values ​​(dB) normalized by peak power.

[0224] As shown in Figures 24 and 25, in configuration examples 1-2a and 1-2b, the peak level in the grating lobe direction is suppressed compared to the peak in the target true value direction, similar to configuration example 1 (for example, Figure 10).

[0225] In arrangements such as those shown in arrangement examples 1-2a and 1-1b, even if the vertical size of the transmitting antenna 106 is large, for example, the receiving antenna 202 can be placed between the elements of the transmitting antenna 106, thus reducing the antenna mounting area.

[0226] Furthermore, in arrangements such as those in arrangement example 1-2a and arrangement example 1-1b, the virtual antennas are arranged without overlap, so the element spacing of the transmitting antenna 106 is wider than the horizontal aperture length of the receiving antenna 202. As a result, the horizontal aperture length of the virtual antenna is widened, the peak in the target true value direction becomes sharper in the horizontal direction, and the horizontal angle measurement accuracy or resolution is improved. In addition, compared to the case where the element spacing of the transmitting antenna 106 is widened in arrangement example 1, the arrangements in arrangement examples 1-2a and 1-1b can further suppress the variation in the horizontal spacing of the virtual antennas, and also have the effect of further reducing the rise of side lobes near the main lobe.

[0227] Furthermore, in arrangement example 1-2a, the element spacing of the transmitting antenna 106 is wider than in arrangement example 1-2b, and the horizontal aperture length in the virtual receiving array arrangement is increased. Therefore, in arrangement example 1-2a, the increased element spacing of the transmitting antenna 106 makes the peak in the target true value direction sharper in the horizontal direction, thus improving the horizontal angle measurement accuracy or estimation accuracy of the radar device 10. Although increasing the element spacing of the transmitting antenna 106 may generate more grating lobes, as shown in Figure 24, it can be confirmed that grating lobes are suppressed in arrangement example 1-2a.

[0228] Furthermore, arrangement example 1-2b has fewer receiving antennas 202 compared to arrangement example 1-2a. Therefore, in arrangement example 1-2b, the antenna configuration in the radar device 10 is simplified and grating lobes can be suppressed by reducing the number of receiving antennas 202.

[0229] Note that Figure 21 illustrates the case where the antennas at the ends of the first and second oblique antenna groups (for example, Rx#4) overlap. However, the explanation is not limited to this case; for example, the antennas included in both the first and second oblique antenna groups may be different from the antennas at the ends of each oblique antenna group.

[0230] [Modification 3 of arrangement example 1] The inclination of the first and second oblique antenna groups (for example, the change in position in the vertical direction relative to the horizontal direction) is not limited to the example shown in Figure 8, and other inclinations may be set.

[0231] For example, in Modification Example 3 of Arrangement Example 1, we will describe an example in which the inclination of the first and second oblique antenna groups is set more gently than in Arrangement Example 1.

[0232] For example, in arrangement example 1, as shown in Figure 8, the first oblique antenna group Rx#1~#4 is positioned with a horizontal shift of 0.5 wavelengths from left to right in the figure, and simultaneously shifted downwards in the vertical direction by 0.5 wavelengths. The second oblique antenna group Rx#5~#8 is positioned with a horizontal shift of 0.5 wavelengths from right to left in the figure, and simultaneously shifted downwards in the vertical direction by 0.5 wavelengths.

[0233] In Modification 3 of Arrangement Example 1, for example, as shown in Figure 26 (hereinafter referred to as "Arrangement Example 1-3"), the first oblique antenna group Rx#1~#4 is shifted horizontally from left to right in the figure by an interval of 1 wavelength, and simultaneously shifted downward vertically by an interval of 0.5 wavelengths. Also, as shown in Figure 26, the second oblique antenna group Rx#5~#8 is shifted horizontally from right to left in the figure by an interval of 1 wavelength, and simultaneously shifted downward vertically by an interval of 0.5 wavelengths. Note that in Arrangement Example 1-3 shown in Figure 26, settings different from the inclination of the first and second oblique antenna groups may be the same as in Arrangement Example 1 (for example, Figure 8).

[0234] Thus, in Figure 26, compared to Figure 8, the vertical position change relative to the horizontal direction between adjacent antennas in the first and second oblique antenna groups is smaller. In other words, in Figure 26, the inclination of the first and second oblique antenna groups is gentler compared to Figure 8.

[0235] Based on the arrangement of transmitting antennas Tx#1 to Tx#6 and receiving antennas Rx#1 to Rx#8 as shown in Figure 26, the position coordinates of the virtual antennas VA#1 to #48 that constitute the virtual receiving array antenna are calculated based on equation (16).

[0236] Figure 27 shows an example of the arrangement of a virtual receiving array obtained by the antenna arrangement shown in Figure 26. The aperture length of the virtual receiving array shown in Figure 27 is wider than that of arrangement example 1 (Figure 9) due to the gentler inclination of the first and second oblique antenna groups.

[0237] Next, we will explain an example of the direction estimation result (computer simulation result) when applying the antenna arrangement described in the above-mentioned arrangement example 1-3.

[0238] Figure 28 shows MIMO array configurations for configuration examples 1-3 (D H = 0.5λ, D V The direction estimation results when the beamformer method is used as the direction of arrival estimation algorithm for the direction estimation unit 213 are shown using (= 0.5λ). In Figure 28, as an example, the output of the direction of arrival estimation evaluation function values ​​in the horizontal ±90 degree range and the vertical ±90 degree range when the target true value is set to 0 degrees horizontally and 0 degrees vertically are plotted.

[0239] Figure 28(a) is a grayscale color map showing normalized power values ​​in a two-dimensional direction, with the horizontal axis representing the horizontal direction and the vertical axis representing the vertical direction. Figure 28(b) is a grayscale color map of Figure 28(a), with the horizontal axis representing the horizontal direction and the vertical axis representing the normalized power values. In Figure 28, the normalized power values ​​may be shown, for example, as decibel values ​​(dB) normalized by peak power.

[0240] As shown in Figure 28, in arrangement examples 1-3, similar to arrangement example 1 (Figure 10), the peak level in the grating lobe direction is suppressed compared to the peak in the target true value direction.

[0241] Furthermore, in arrangement examples 1-3, compared to arrangement example 1, the virtual receiving array arrangement (for example, the aperture length of the virtual receiving array) is wider in the horizontal direction. As shown in Figure 28, the peak in the target true value direction becomes sharper in the horizontal direction, which improves the horizontal angle measurement accuracy or estimation accuracy of the radar device 10.

[0242] Furthermore, in arrangement examples 1-3, the effect is obtained that antenna arrangements are possible not only when the vertical antenna size of the transmitting antenna 106 is large (e.g., 1 wavelength or more), but also when the horizontal antenna size is large (e.g., 1 wavelength or more). For example, the larger the horizontal antenna size, the narrower the horizontal field of view and the improved directivity gain, thereby improving radar performance in detecting more distant targets within a narrower (e.g., limited) horizontal field of view.

[0243] As shown in Figure 28, in arrangement examples 1-3, a side lobe of approximately -10 dB may occur next to the peak in the target true value direction (horizontally) compared to arrangement example 1 (for example, Figure 10). The occurrence of this side lobe is due, for example, to an increased spacing (for example, the minimum spacing) between the first oblique antenna group and the second oblique antenna group compared to arrangement example 1.

[0244] For example, by increasing the distance between the first and second oblique antenna groups, it is possible to improve the horizontal angle measurement accuracy or estimation accuracy, while increasing the lateral (horizontal) sidelobe level of the peak in the target true value direction. Depending on requirements such as the detection target assumed by the radar device 10, the distance between the first and second oblique antenna groups (e.g., the minimum distance) may be set within a suitable range.

[0245] Furthermore, while Figure 26 describes the case where the distance between the first oblique antenna group and the second oblique antenna group (for example, the minimum distance) is wider than the aperture length of the transmitting antenna 106, the case is not limited to this, and the distance between the first oblique antenna group and the second oblique antenna group (for example, the minimum distance) may be set to be less than or equal to the aperture length of the transmitting antenna 106.

[0246] Furthermore, while Modification 3 of Arrangement Example 1 describes a case where the inclination of the first and second oblique antenna groups is set more gently than in Arrangement Example 1, it is not limited to this, and the inclination of the first and second oblique antenna groups may be set steeper than in Arrangement Example 1. If the inclination of the first and second oblique antenna groups is to be steeper, Modification 4 of Arrangement Example 1 or Arrangement Example 2, described later, may be applied.

[0247] [Modification 4 of arrangement example 1] For example, in arrangement example 1 shown in Figure 8, the case where the first oblique antenna group Rx#1~#4 and the second oblique antenna group Rx#5~#8 are arranged in a horizontally inverted symmetrical configuration was described. However, the explanation is not limited to this, and the first and second oblique antenna groups do not necessarily have to be arranged in a horizontally inverted symmetrical configuration. For example, the arrangement direction of the first oblique antenna group and the arrangement direction of the second oblique antenna group do not need to be parallel but different directions.

[0248] For example, as shown in Figure 29 (hereinafter referred to as "Arrangement Example 1-4a"), the first oblique antenna group Rx#1~#4 and the second oblique antenna group Rx#5~#8 may have asymmetrical inclinations (for example, changes in position in the vertical direction relative to the horizontal direction), or different antenna spacings may be set in the horizontal and vertical directions, respectively.

[0249] Furthermore, as shown in Figure 30 (hereinafter referred to as "Arrangement Example 1-4b"), the positions of the first oblique antenna group and the second oblique antenna group may be shifted vertically.

[0250] Furthermore, as shown in Figure 31 (hereinafter referred to as "Arrangement Example 1-4c"), the number of antennas included in the first oblique antenna group and the second oblique antenna group may be different.

[0251] Furthermore, a combination of any two or three of the following configurations may be used: configuration example 1-4a (asymmetrical tilt), configuration example 1-4b (vertically shifted position), and configuration example 1-2c (number of antennas). For example, Figure 32 (hereinafter referred to as "configuration example 1-4d") shows a configuration that combines configuration examples 1-4a, 1-4b, and 1-4c.

[0252] Furthermore, as shown in Figure 29, if the first and second oblique antenna groups have asymmetrical inclinations, for example, the arrangement of the first and second oblique antenna groups may be rotationally symmetrical by about 90 degrees. In this case, for example, the direction in which grating groves are generated due to the relationship between the transmitting antenna 106 and the first oblique antenna group, and the direction in which grating groves are generated due to the relationship between the transmitting antenna 106 and the second oblique antenna group, are rotationally symmetrical by about 90 degrees in the horizontal and vertical two-dimensional planes, so the spacing between grating groves tends to be larger.

[0253] An arrangement in which the orientation of the first oblique antenna group and the orientation of the second oblique antenna group are rotationally symmetrical to each other by about 90 degrees is preferable, for example, when the number of antennas in the radar device 10 is small. For example, the fewer antennas in the radar device 10, the wider the beamwidth of the main beam in direction estimation tends to be. Therefore, when the directions of suppressed grating groves are close together, the fewer antennas in the radar device 10, the more the suppressed grating grove powers overlap due to the beamwidth widening, potentially increasing the grating grove power. Consequently, the fewer antennas in the radar device 10, the more the grating grove suppression performance deteriorates, and the higher the probability of false detection in the radar device 10. Therefore, when the number of antennas in the radar device 10 is small, for example, an arrangement in which the orientation of the first oblique antenna group and the orientation of the second oblique antenna group are rotationally symmetrical to each other by about 90 degrees can suppress the overlap of grating grove powers, thereby improving the grating grove suppression performance.

[0254] Based on the arrangement of transmitting antennas Tx#1 to Tx#6 and receiving antennas Rx#1 to Rx#8 or receiving antennas Rx#1 to Rx#7 as shown in Figures 29 to 32, the position coordinates of the virtual antennas VA#1 to VA#48 or VA#1 to VA#42 that constitute the virtual receiving array antenna are calculated based on equation (16).

[0255] Figures 33 to 36 show examples of virtual receiving array configurations obtained by the antenna configurations shown in Figures 29 to 32, respectively.

[0256] Next, we will explain an example of the direction estimation result (computer simulation result) when applying the antenna configurations described above for each of the configuration examples 1-4a to 1-4d.

[0257] Figures 37 to 40 show MIMO array configurations (D) for configuration examples 1-4a (Figure 29) to 1-4d (Figure 32). H = 0.5λ, D V The direction estimation results when the beamformer method is used as the direction of arrival estimation algorithm for the direction estimation unit 213 are shown using (= 0.5λ). As an example, Figures 37 to 40 plot the output of the direction of arrival estimation evaluation function values ​​in the horizontal ±90 degree range and the vertical ±90 degree range when the target true value is set to 0 degrees horizontally and 0 degrees vertically.

[0258] Figures 37 to 40(a) show normalized power values ​​in a two-dimensional direction, with the horizontal axis representing the horizontal direction and the vertical axis representing the vertical direction, as a grayscale color map. Figures 37 to 40(b) are similar to Figures 37 to 40(a), but with the horizontal axis representing the horizontal direction and the vertical axis representing the normalized power values, and the normalized power values ​​are shown as a grayscale color map. In Figures 37 to 40, the normalized power values ​​may be shown, for example, as decibel values ​​(dB) normalized by peak power.

[0259] As shown in Figures 37 to 40, according to arrangement examples 1-4, similar to arrangement example 1 (Figure 10), the peak level in the grating lobe direction is suppressed to approximately -5 dB compared to the peak in the target true value direction.

[0260] [Modification 5 of Arrangement Example 1] In arrangement example 1 and modified examples 1-4, for example, the transmission antenna spacing is set to the basic horizontal spacing D. H Set to an integer multiple of the basic interval D in the horizontal direction, and set the diagonal tilt of the receiving antenna 202 to the basic interval D in the horizontal direction. H Set to an integer multiple of and the basic interval D in the vertical direction V The case where the value is set to an integer multiple was explained.

[0261] That is, N Tx The transmitting antennas 106 are positioned horizontally, with a transmitting antenna spacing of dT × D H It will be placed there.

[0262] Furthermore, in the Na receiving antennas 202, the first oblique antenna group and the second oblique antenna group are arranged in different oblique directions. Also, the first oblique antenna group is arranged horizontally in dRH1 × D H It shifts at intervals of D, and simultaneously shifts vertically as well. V They are arranged diagonally, shifted at intervals of . In addition, the second diagonal antenna group is dRH2×D in the horizontal direction. H It shifts at intervals of D, and simultaneously shifts vertically as well. V They are positioned diagonally, shifting at intervals of [number].

[0263] Here, dT is an integer greater than or equal to 2, and dRH1 and dRH2 are each integers greater than or equal to 1. Also, the basic interval D H and basic interval D VFor example, dRH1 can be a value within the range of 0.45 to 0.8 times the wavelength of the radar transmission signal. Note that dRH1 and dRH2 may be the same or different. Also, dRH1 and dRH2 are sometimes collectively represented as "dRH". For example, if dRH1 = dRH2, the first and second oblique antenna groups will be arranged symmetrically in the horizontal direction. If dRH1 ≠ dRH2, the first and second oblique antenna groups will be arranged asymmetrically in the horizontal direction.

[0264] For example, Figures 41 to 44 each show antenna configuration examples where dRH1=dRH2 and dT=2,4,5,7. Also, Figures 41 to 43 show the case where dRH1=dRH2=1, and Figure 44 shows the case where dRH1=dRH2=2. Hereafter, each of the antenna configuration examples in Figures 41 to 44 will also be referred to as "Configuration Example 1-5a," "Configuration Example 1-5b," "Configuration Example 1-5c," and "Configuration Example 1-5d."

[0265] Here, the larger dT is, the more likely it is that the direction of the grating lobe generated by the relationship between the transmitting antenna 106 and the first oblique antenna group will coincide with the direction of the grating lobe generated by the relationship between the transmitting antenna 106 and the second oblique antenna group. Therefore, for example, as shown in Figures 41 to 44, the larger dT is, the closer the first oblique antenna group and the second oblique antenna group may be placed. By placing the first oblique antenna group and the second oblique antenna group closer together, the spacing between adjacent virtual antennas in the virtual receiving array can be narrowed, making it possible to suppress the grating lobe.

[0266] Based on the arrangement of transmitting antennas Tx#1 to Tx#6 and receiving antennas Rx#1 to Rx#8 as shown in Figures 41 to 44, the position coordinates of the virtual antennas VA#1 to VA#48 that constitute the virtual receiving array antenna are calculated based on equation (16).

[0267] Figures 45 to 48 show examples of virtual receiving array configurations obtained by the antenna configurations shown in Figures 41 to 44.

[0268] Next, we will explain an example of the direction estimation result (computer simulation result) when applying the antenna arrangements described in the above-mentioned arrangement examples 1-5a to 1-5d.

[0269] Figures 49 to 52 each show MIMO array configurations (D) of configuration examples 1-5a to 1-5d shown in Figures 41 to 44. H = 0.5λ, D V The direction estimation results when the beamformer method is used as the direction estimation algorithm for the direction estimation unit 213 are shown using (= 0.5λ). As an example, Figures 49 to 52 plot the output of the direction estimation evaluation function values ​​in the horizontal ±90 degree range and the vertical ±90 degree range when the target true value is set to 0 degrees horizontally and 0 degrees vertically.

[0270] Figures 49 to 52(a) show normalized power values ​​in a two-dimensional direction, with the horizontal axis representing the horizontal direction and the vertical axis representing the vertical direction, as a grayscale color map. Figures 49 to 52(b) are similar to Figures 49 to 52(a), but with the horizontal axis representing the horizontal direction and the vertical axis representing the normalized power values, and the normalized power values ​​are shown as a grayscale color map. In Figures 49 to 52, the normalized power values ​​may be shown, for example, as decibel values ​​(dB) normalized by peak power.

[0271] As shown in Figures 49 to 52, according to arrangement examples 1-5a to 1-5d, similar to arrangement example 1 (Figure 10), the peak level in the grating lobe direction is suppressed compared to the peak in the target true value direction.

[0272] Furthermore, as shown in, for example, arrangement examples 1-5a (dT=2), 1-5b (dT=4), 1-5c (dT=5), and 1-5d (dT=7), the larger dT, the wider the virtual receiving array arrangement (for example, the aperture length of the virtual receiving array) becomes in the horizontal direction. As a result, as shown in Figures 49 to 52, the peak in the target true value direction becomes sharper in the horizontal direction, which improves the horizontal angle measurement accuracy or estimation accuracy of the radar device 10.

[0273] Furthermore, for example, the larger dT, the closer the interval between grating groves, making it easier for more grating groves to occur. However, as shown in Figures 49 to 52, it can be confirmed that in each of the arrangement examples 1-5a to 1-5d, the grating groves are suppressed to approximately -3dB to 6dB.

[0274] Furthermore, the tilt of the first and second oblique antenna groups is dRH1 × D in the horizontal direction. H Alternatively, dRH2×D H It shifts at intervals of D, and simultaneously shifts vertically as well. V An interval that is an integer multiple of the interval (for example, dRV × D V Shifting by dRV (when dRV is an integer greater than or equal to 2) makes it easier for the direction of the vertical grating lobe generated by the relationship between the transmitting antenna 106 and the first oblique antenna group to coincide with the direction of the vertical grating lobe generated by the relationship between the transmitting antenna 106 and the second oblique antenna group.

[0275] Therefore, for example, the first oblique antenna group has dRH1 × D in the horizontal direction. H It shifts at intervals of D, and simultaneously shifts vertically as well. V interval (or dRV × D V (and when dRV=1) the antennas are positioned diagonally and shifted, and the second diagonal antenna group is positioned horizontally with dRH2×D H It shifts at intervals of D, and simultaneously shifts vertically as well. V interval (or dRV × D V (and if dRV=1) they may be positioned diagonally to shift.

[0276] Furthermore, regarding the tilt of the first and second oblique antenna groups, dRH1 × D in the horizontal direction. H Alternatively, dRH2×D H It shifts at intervals of D, and simultaneously shifts vertically as well. VIf the shift is an integer multiple of the interval, for example, arrangement example 1-4a, or arrangement example 2 and its modifications described later may be applied. The virtual receiving array using arrangement example 2 and its modifications described later has a wider vertical antenna spacing and an increased vertical aperture length, which improves the vertical angle measurement accuracy or resolution of the radar device 10 (examples will be described later).

[0277] Note that in arrangement example 1 and modified examples 1-5, the transmitting antenna spacing is the horizontal basic spacing D. H Set to an integer multiple of and the diagonal tilt of the receiving antenna 202 is set to the horizontal basic interval D. H Set to an integer multiple of the vertical, and the vertical direction is the basic vertical spacing D V We have explained an example using an interval set to an integer multiple of D, but this is not limited to this, V , D H The arrangement may not be an integer multiple of the given number.

[0278] For example, N Tx The transmitting antennas 106 are positioned horizontally, with a transmitting antenna spacing of αD H They may be arranged as follows. Also, for example, Na receiving antennas 202 may be arranged in different oblique directions, with the first oblique antenna group and the second oblique antenna group not parallel, and βD in the horizontal direction. H It shifts at intervals of γD, and simultaneously shifts vertically as well. V They may be positioned diagonally, shifted at intervals of .

[0279] Here, α, β, and γ represent positive real values, and αD H It is 1 wavelength or longer, and βD H and γD V The actual value may be 0.45 to 0.8 wavelengths or greater, and the same effect as in the embodiment of this disclosure described above can be obtained.

[0280] As an example, in the antenna configuration shown in Figure 53 (hereinafter referred to as "configuration example 1-5e"), D V =0.5 wavelength, D H =0.5 wavelength, αD H =2.7 wavelength, βD V=0.45 wavelength, γD H It is set to =0.6 wavelength.

[0281] Based on the arrangement of transmitting antennas Tx#1 to Tx#6 and receiving antennas Rx#1 to Rx#8 as shown in Figure 53, the position coordinates of the virtual antennas VA#1 to #48 that constitute the virtual receiving array antenna are calculated based on equation (16). Figure 54 shows an example of the arrangement of the virtual receiving array obtained by the antenna arrangement shown in Figure 53.

[0282] Next, we will explain an example of the direction estimation result (computer simulation result) when applying the antenna arrangement described in the above-mentioned arrangement example 1-5e.

[0283] Figure 55 shows the MIMO array configuration of arrangement examples 1-5e shown in Figure 53 (D H = 0.5λ, D V The direction estimation results when the beamformer method is used as the direction of arrival estimation algorithm for the direction estimation unit 213 are shown using (= 0.5λ). In Figure 55, as an example, the output of the direction of arrival estimation evaluation function values ​​in the horizontal ±90 degree range and the vertical ±90 degree range when the target true value is set to 0 degrees horizontally and 0 degrees vertically are plotted.

[0284] Figure 55(a) is a grayscale color map showing normalized power values ​​in a two-dimensional direction, with the horizontal axis representing the horizontal direction and the vertical axis representing the vertical direction. Figure 55(b) is a grayscale color map of Figure 55(a), with the horizontal axis representing the horizontal direction and the vertical axis representing the normalized power values. In Figure 55, the normalized power values ​​may be shown, for example, as decibel values ​​(dB) normalized by peak power.

[0285] As shown in Figure 55, according to arrangement examples 1-5e, similar to arrangement example 1 (Figure 10), the peak level in the grating lobe direction is suppressed compared to the peak in the target true value direction.

[0286] [Modification 6 of arrangement example 1] In at least one of the transmitting antenna 106 and the receiving antenna 202 (for example, the first oblique antenna group and the second oblique antenna group), the spacing between adjacent antennas is not limited to equal spacing, but may include one or more unequal spacings.

[0287] In the antenna arrangement example shown in Figure 56 (hereinafter referred to as "arrangement example 1-6a"), the transmitting antennas 106 may be arranged at unequal (or non-uniform) intervals. In Figure 56, settings different from the arrangement interval of the transmitting antennas 106 may be the same as in arrangement example 1 (for example, Figure 8).

[0288] Furthermore, in the antenna arrangement example shown in Figure 57 (hereinafter referred to as "arrangement example 1-6b"), the first oblique antenna group and the second oblique antenna group may be arranged at unequal (or non-uniform) intervals. In Figure 57, the arrangement intervals of the first oblique antenna group and the second oblique antenna group may be set differently from those in arrangement example 1 (for example, Figure 8).

[0289] Furthermore, in the antenna arrangement example shown in Figure 58 (hereinafter referred to as "arrangement example 1-6c"), the transmitting antenna 106, the first oblique antenna group, and the second oblique antenna group may be arranged at unequal (or non-uniform) intervals. In Figure 58, the arrangement intervals of the transmitting antenna 106, the first oblique antenna group, and the second oblique antenna group may be different from those in arrangement example 1 (for example, Figure 8).

[0290] Even with the antenna configurations shown in Figures 56 to 58, the peak level in the grating lobe direction is suppressed compared to the peak in the target true value direction.

[0291] Furthermore, the arrangement is not limited to the above-described examples. For example, either the first group of oblique antennas or the second group of oblique antennas may be arranged at uneven intervals, or either the first group of oblique antennas or the second group of oblique antennas may be arranged at uneven intervals from the transmitting antenna 106.

[0292] [Modification 7 of arrangement example 1] In Modification 7 of Arrangement Example 1, for example, a multi-stage antenna arrangement described in Arrangement Example 1 and Modifications 1 to 6 of Arrangement Example 1 may be applied.

[0293] Examples of multi-stage configurations include a configuration in which the transmitting antenna 106 is arranged in two vertical stages, a configuration in which the transmitting antenna 106 is arranged in two horizontal stages, a configuration in which the first and second oblique antenna groups of the receiving antenna 202 are arranged in two vertical stages, and a configuration in which the first and second oblique antenna groups of the receiving antenna 202 are arranged in two horizontal stages. Alternatively, the multi-stage configuration may be a combination of these configurations.

[0294] Even in the case of a multi-stage configuration, the effects related to the above-described arrangement example 1 can be maintained. Furthermore, a horizontal multi-stage configuration expands the aperture length of the horizontal virtual receiving array, thereby improving the horizontal angle measurement accuracy or resolution of the radar device 10. Also, for example, a vertical multi-stage configuration expands the aperture length of the vertical virtual receiving array, thereby improving the vertical angle measurement accuracy or resolution of the radar device 10. Furthermore, for example, a vertical and horizontal multi-stage configuration expands the aperture lengths of the vertical and horizontal virtual receiving arrays, thereby improving the vertical and horizontal angle measurement accuracy or resolution of the radar device 10.

[0295] In the case of a multi-stage configuration, the common arrangement of the transmitting antenna Tx or the receiving antenna Rx may be configured in multiple stages in at least one of the vertical and horizontal directions, or different arrangements of the transmitting antenna Tx or the receiving antenna Rx may be configured in multiple stages in at least one of the vertical and horizontal directions.

[0296] The following describes examples of antenna placement in arrangement example 1-7.

[0297] For example, in Figure 59 (hereinafter referred to as "arrangement example 1-7a"), Tx#1 to Tx#6 and Tx#7 to Tx#12, which have the same arrangement as Tx#1 to Tx#6, are arranged in multiple stages with a vertical shift. That is, in Figure 59, the multiple transmitting antennas 106 have multiple sets of six antennas arranged horizontally (for example, sets of Tx#1 to #6 and sets of Tx#7 to #12).

[0298] Furthermore, for example, in Figure 60 (hereinafter referred to as "arrangement example 1-7b"), Rx#1 to Rx#8 and Rx#9 to Rx#16, which have the same arrangement as Rx#1 to Rx#8, are arranged in multiple stages with a horizontal shift. That is, in Figure 60, the multiple receiving antennas 202 have multiple sets of first oblique antenna groups and second oblique antenna groups (for example, a set of Rx#1 to #8 and a set of Rx#9 to #16).

[0299] Furthermore, for example, in Figure 61 (hereinafter referred to as "Arrangement Example 1-7c"), Rx#1 to Rx#8 and Rx#9 to Rx#16, which are arranged differently from Rx#1 to Rx#8, are arranged in multiple stages in the vertical direction. That is, in Figure 61, the multiple receiving antennas 202 have multiple sets of first oblique antenna groups and second oblique antenna groups (for example, a set of Rx#1 to #8 and a set of Rx#9 to #16).

[0300] Furthermore, for example, in Figure 62 (hereinafter referred to as "Arrangement Example 1-7d"), Tx#1 to Tx#6 and Tx#7 to Tx#8, which have the same arrangement as Tx#1 to Tx#6, are arranged in multiple stages with a vertical shift, and Rx#1 to Rx#8 and Rx#9 to Rx#16, which have a different arrangement from Rx#1 to Rx#8, are arranged in multiple stages in the vertical direction. That is, in Figure 62, the multiple transmitting antennas 106 have multiple sets of six antennas arranged horizontally (for example, sets of Tx#1 to #6 and sets of Tx#7 to #12). Also, in Figure 62, the multiple receiving antennas 202 have multiple sets of a first oblique antenna group and a second oblique antenna group (for example, sets of Rx#1 to #8 and sets of Rx#9 to #16).

[0301] Based on the arrangement of transmitting and receiving antennas shown in Figures 59 to 62, the position coordinates of the virtual antennas constituting the virtual receiving array antenna are calculated based on equation (16).

[0302] Figures 63 to 66 show examples of virtual receiving array configurations obtained by the antenna configurations shown in Figures 59 to 62.

[0303] Next, we will explain an example of the direction estimation result (computer simulation result) when applying the antenna arrangements corresponding to each of the above-mentioned arrangement examples 1-7a to 1-7d.

[0304] Figures 67 to 70 each represent the MIMO array configurations (D) of configuration examples 1-7 shown in Figures 59 to 62. H = 0.5λ, D V The direction estimation results when the beamformer method is used as the direction estimation algorithm for the direction estimation unit 213 are shown using (= 0.5λ). As an example, Figures 67 to 70 plot the output of the direction estimation evaluation function values ​​in the horizontal ±90 degree range and the vertical ±90 degree range when the target true value is set to 0 degrees horizontally and 0 degrees vertically.

[0305] Figures 67 to 70(a) show normalized power values ​​in a two-dimensional direction, with the horizontal axis representing the horizontal direction and the vertical axis representing the vertical direction, as a grayscale color map. Figures 67 to 70(b) are similar to Figures 67 to 70(a), but with the horizontal axis representing the horizontal direction and the vertical axis representing the normalized power values, and the normalized power values ​​are shown as a grayscale color map. In Figures 67 to 70, the normalized power values ​​may be shown, for example, as decibel values ​​(dB) normalized by peak power.

[0306] As shown in Figures 67 to 70, in arrangement examples 1-7a to 1-7d, similar to arrangement example 1 (Figure 10), the peak level in the grating lobe direction is suppressed compared to the peak in the target true value direction.

[0307] Furthermore, in arrangement example 1-7a (Figure 59), compared to arrangement example 1 (Figure 8), the number of transmitting antennas Tx is increased, and the elements of the transmitting antenna 106 are shifted vertically and arranged in multiple stages. As a result, in arrangement example 1-7a, the vertical aperture length of the virtual receiving array is widened, and as shown in Figure 67, the peak in the target true value direction becomes sharper in the vertical direction, making it possible to improve the vertical angle measurement accuracy or estimation accuracy of the radar device 10.

[0308] Furthermore, in arrangement example 1-7b (Figure 60), compared to arrangement example 1 (Figure 8), the number of receiving antennas Rx increases, and the elements of the receiving antenna 202 are shifted horizontally and arranged in multiple stages. As a result, in arrangement example 1-7b, the horizontal aperture length of the virtual receiving array is widened, and as shown in Figure 68, the peak in the target true value direction becomes sharper in the horizontal direction, making it possible to improve the horizontal angle measurement accuracy or estimation accuracy of the radar device 10.

[0309] Furthermore, in arrangement example 1-7c (Figure 61), compared to arrangement example 1 (Figure 8), the number of receiving antennas Rx increases, and the elements of the receiving antenna 202 are shifted vertically and arranged in multiple stages. As a result, in arrangement example 1-7c, the vertical aperture length of the virtual receiving array is widened, and as shown in Figure 69, the peak in the target true value direction becomes sharper in the vertical direction, making it possible to improve the vertical angle measurement accuracy or estimation accuracy of the radar device 10.

[0310] Furthermore, in arrangement example 1-7d (Figure 62), compared to arrangement example 1 (Figure 8), the number of transmitting antennas Tx and receiving antennas Rx increases, and elements of both transmitting antenna 106 and receiving antenna 202 are shifted vertically and arranged in multiple stages. As a result, in arrangement example 1-7d, the vertical aperture length of the virtual receiving array is widened, and as shown in Figure 70, compared to arrangement example 1-7a (for example, Figure 59), the peak in the target true value direction becomes sharper in the vertical direction, making it possible to improve the vertical angle measurement accuracy or estimation accuracy of the radar device 10.

[0311] In addition, different antenna elements (for example, antenna elements of different sizes) may be used in the multi-stage configuration shown in arrangement example 1-7. For example, multiple transmitting antennas 106 may include long-range (LR) antenna elements and short-range (SR) antenna elements. Here, the LR antenna elements have a higher directional gain than the SR antenna elements by narrowing the directivity in the vertical direction, the horizontal direction, or both. By using LR antenna elements, the radar device 10 can increase the received signal level of reflected waves from targets at greater distances compared to when using SR antenna elements, thereby enabling the detection of targets at greater distances. In order to further increase the directional gain in the vertical direction, the horizontal direction, or both, the physical size of the LR antenna elements is larger in the vertical direction, the horizontal direction, or both compared to the size of the SR antenna elements.

[0312] For example, in a multi-stage configuration, long-range (LR) antenna elements may be used in the first stage, and short-range (SR) antenna elements may be used in combination with them in the second stage. For example, as shown in Figure 59, if the transmitting antenna 106 is arranged in a two-stage multi-stage configuration in the vertical direction, long-range (LR) antenna elements may be used in the first stage (e.g., Tx#1 to Tx#6), and short-range (SR) antenna elements may be used in the second stage (e.g., Tx#7 to Tx#12).

[0313] Furthermore, if the vertical and horizontal dimensions of the long-range (LR) antenna elements are large, the elements of one stage may be shifted horizontally so that the first stage transmitting antenna 106 and the second stage transmitting antenna 106 do not overlap.

[0314] Thus, when using both an LR antenna and an SR antenna for the transmitting antenna 106, for example, an SR antenna (e.g., an antenna with a wide field of view) may be applied to the receiving antenna 202. This allows for the detection range of both LR and SR modes while maintaining the effectiveness of the arrangement example 1.

[0315] [Modification 8 of arrangement example 1] Regarding placement condition 1, N Tx We have described the case where the orientation of the individual transmitting antennas 106 is horizontal, but N Tx The orientation of each transmitting antenna 106 does not have to strictly coincide with the horizontal direction.

[0316] For example, as shown in Figure 71 (hereinafter referred to as "Arrangement Example 1-8"), the transmitting antenna group Tx#1~#6 are arranged horizontally from left to right in the figure at intervals of one wavelength (for example, 2D H ) is shifted by 0.25 wavelengths (for example, 0.5D) in the vertical direction as well. V ) may be shifted upwards. For example, if the tilt of the transmitting antenna 106 with respect to the horizontal is as gentle as shown in Figure 71, the antenna arrangement shown in Figure 71 may be included in the arrangements that satisfy arrangement condition 1. Note that the arrangement of receiving antennas Rx#1 to Rx#8 is not limited to the example shown in Figure 71, and other arrangements are also possible.

[0317] Based on the arrangement of transmitting antennas Tx#1 to Tx#6 and receiving antennas Rx#1 to Rx#8 as shown in Figure 71, the position coordinates of the virtual antennas VA#1 to #48 that constitute the virtual receiving array antenna are calculated based on equation (16). Figure 72 shows an example of the arrangement of the virtual receiving array obtained by the antenna arrangement shown in Figure 71.

[0318] Next, we will explain an example of the direction estimation result (computer simulation result) when applying the antenna arrangement described in the above-mentioned arrangement example 1-8.

[0319] Figure 73 shows MIMO array configurations for configuration examples 1-8 (D H = 0.5λ, D VThe direction estimation results when the beamformer method is used as the direction of arrival estimation algorithm for the direction estimation unit 213 are shown using (= 0.5λ). In Figure 73, as an example, the output of the direction of arrival estimation evaluation function values ​​in the horizontal ±90 degree range and the vertical ±90 degree range when the target true value is set to 0 degrees horizontally and 0 degrees vertically are plotted.

[0320] Figure 73(a) is a grayscale color map showing normalized power values ​​in a two-dimensional direction, with the horizontal axis representing the horizontal direction and the vertical axis representing the vertical direction. Figure 73(b) is a grayscale color map of Figure 73(a), with the horizontal axis representing the horizontal direction and the vertical axis representing the normalized power values. In Figure 73, the normalized power values ​​may be shown, for example, as decibel values ​​(dB) normalized by peak power.

[0321] As shown in Figure 73, in arrangement examples 1-8, similar to arrangement example 1 (for example, Figure 10), the peak level in the grating lobe direction is suppressed compared to the peak in the target true value direction.

[0322] Furthermore, in arrangement examples 1-8, the transmitting antenna 106 is positioned at a gentler angle to the horizontal compared to arrangement example 1 (for example, Figure 8). In other words, in arrangement examples 1-8, the arrangement of the transmitting antenna 106 also extends vertically. As a result, the vertical aperture length is wider in the virtual receiving array arrangement, and as shown in Figure 73, the peak in the target true value direction becomes sharper in the vertical direction, enabling an improvement in the vertical angle measurement accuracy or estimation accuracy of the radar device 10. Note that in arrangement example 1-8, because the transmitting beam direction is tilted at a gentle angle, the grating lobe generation range tends to expand horizontally.

[0323] The above describes a modified version of arrangement example 1.

[0324] [Example of the minimum antenna configuration and arrangement when the number of antennas is small under arrangement condition 1] The following describes the minimum antenna configuration that satisfies arrangement condition 1, and examples of arrangements when the number of antennas satisfying arrangement condition 1 is small. Note that similar effects can be obtained by modifying the antenna arrangements described below in accordance with the modifications of arrangement example 1 described above.

[0325] The minimum number of antennas for arrangement condition 1 is, for example, the number of transmitting antennas N. Tx This is the case when =2 and the number of receiving antennas Na=3. In other words, there are 2 transmitting antennas 106, and the total number of antennas in the first and second oblique antenna groups is 3.

[0326] Figure 74 shows the minimum number of antennas (number of transmitting antennas N) under arrangement condition 1. Tx An example of an antenna configuration with =2 and the number of receiving antennas Na=3 is shown. Figure 74(a) shows an example of a MIMO antenna configuration, and Figure 74(b) shows an example of a virtual receiving array configuration composed of the MIMO antenna configuration shown in Figure 74(a). Also, in Figure 74, the scales of the horizontal and vertical axes are, for example, D H , D V Let's assume that.

[0327] In Figure 74, the first oblique antenna group includes Rx#1 and Rx#2, and the second oblique antenna group includes Rx#2 and Rx#3.

[0328] Furthermore, Figures 75 to 79 show examples of antenna configurations when the number of antennas satisfying configuration condition 1 is small. Figures 75 to 79(a) show an example of a MIMO antenna configuration, and Figures 75 to 79(b) show an example of a virtual receiving array configuration composed of the MIMO antenna configuration shown in Figures 75 to 79(a). Also, in Figures 75 to 79, the scales on the horizontal and vertical axes are, for example, D H , D V Let's assume that.

[0329] For example, Figures 75 and 76 show the number of transmitting antennas N. TxAn example of antenna arrangement is shown for cases where =2 and the number of receiving antennas Na=4. In Figures 75 and 76, the first oblique antenna group includes Rx#1 and Rx#2, and the second oblique antenna group includes Rx#3 and Rx#4.

[0330] Also, for example, Figure 77 shows the number of transmitting antennas N. Tx An example of antenna arrangement when =3 and the number of receiving antennas Na=3 is shown. In Figure 77, the first oblique antenna group includes Rx#1 and Rx#2, and the second oblique antenna group includes Rx#2 and Rx#3.

[0331] Furthermore, for example, Figures 78 and 79 show the number of transmitting antennas N. Tx Examples of antenna configurations for cases where =3 and the number of receiving antennas Na=4 are shown. In Figures 78 and 79, the first oblique antenna group includes Rx#1 and Rx#2, and the second oblique antenna group includes Rx#3 and Rx#4.

[0332] The above explains an example of placement condition 1.

[0333] [Placement condition 2] N Tx Each transmitting antenna 106 includes a "first oblique antenna group" positioned in a "first oblique direction" and a "second oblique antenna group" positioned in a "second oblique direction," where the first oblique direction and the second oblique direction are not parallel. In other words, the first oblique direction and the second oblique direction are in different directions. The Na receiving antennas 202 include a "third oblique antenna group" positioned in a "third oblique direction" and a "fourth oblique antenna group" positioned in a "fourth oblique direction," where the third and fourth oblique directions are not parallel. In other words, the third and fourth oblique directions are in different directions.

[0334] Each of the first oblique antenna group (for example, corresponding to the third antenna group) and the second oblique antenna group (for example, corresponding to the fourth antenna group) may include at least two transmitting antennas 106. Also, each of the third oblique antenna group (for example, corresponding to the first antenna group) and the fourth oblique antenna group (for example, corresponding to the second antenna group) may include at least two receiving antennas 202.

[0335] By arranging the first and second oblique antenna groups, which satisfy arrangement condition 2, at arbitrary positions, grating lobe suppression is possible. For example, as shown in the following arrangement example or modification, by arranging the first and second oblique antenna groups so that their horizontal positions do not overlap, it becomes possible to arrange transmitting antenna elements with a large vertical size.

[0336] Similarly, grating lobes can be suppressed by placing the third and fourth oblique antenna groups, which satisfy placement condition 2, at arbitrary positions. For example, as shown in the following arrangement example or modification, by arranging the third and fourth oblique antenna groups so that their horizontal positions do not overlap, it becomes possible to arrange receiving antenna elements with a large vertical size.

[0337] In arrangement condition 2, for example, the transmitting antenna 106 includes a first group of oblique antennas arranged in a first oblique direction and a second group of oblique antennas arranged in a second oblique direction. Compared to arrangement condition 1, the vertical aperture length of the virtual receiving array can be increased, thereby improving the vertical angle measurement accuracy or resolution of the radar device 10.

[0338] Furthermore, under arrangement condition 2, for example, the vertical grating lobe that occurs when the inclination in the first to fourth diagonal directions is made steeper, for example, with respect to the horizontal direction, can be suppressed. This suppression effect of the grating lobe allows for a larger vertical aperture length, further improving the vertical angle measurement accuracy or resolution of the radar device 10.

[0339] The following describes an example of placement condition 2. Below, we will describe an example of a placement that satisfies placement condition 2, and an example of the direction estimation result obtained by computer simulation in that placement example.

[0340] <Layout example 2> Figure 80 shows an example of the arrangement of the transmitting antenna 106 (e.g., denoted as Tx) and the receiving antenna 202 (e.g., denoted as Rx) according to arrangement example 2 (e.g., an example of a MIMO antenna arrangement). In Figure 80, the scales on the horizontal and vertical axes are, for example, the basic horizontal interval D. H , and the basic vertical spacing D V This will be the case. Note that the scales on the horizontal and vertical axes are the same for MIMO antenna configurations in the other examples below. For example, D H and D V A spacing of 0.5 wavelengths is sufficient.

[0341] In the example shown in Figure 80, the number of transmitting antennas N Tx There are 6 (e.g., Tx#1, Tx#2, Tx#3, Tx#4, Tx#5, and Tx#6), and the number of receiving antennas Na is 8 (e.g., Rx#1, Rx#2, Rx#3, Rx#5, Rx#6, Rx#7, and Rx#8).

[0342] In Figure 80, N Tx The six transmitting antennas Tx#1 to #6 include the first oblique antenna group Tx#1 to #3, which is arranged in the first oblique direction, and the second oblique antenna group Tx#4 to #6, which is arranged in the second oblique direction. In Figure 80, the first oblique direction and the second oblique direction are not parallel, but are different directions from each other.

[0343] Furthermore, in Figure 80, Na = 8 receiving antennas Rx#1~#8 include the third oblique antenna group Rx#1~#4 arranged in the third oblique direction, and the fourth oblique antenna group Rx#5~#8 arranged in the fourth oblique direction. In Figure 80, the third oblique direction and the fourth oblique direction are not parallel but are different directions from each other.

[0344] Based on these findings, the antenna arrangement in arrangement example 2 shown in Figure 80 satisfies arrangement condition 2.

[0345] Furthermore, in arrangement example 2, as shown in Figure 80, the first to fourth diagonal directions are not parallel to each other, but are in different directions.

[0346] For example, the first oblique antenna group Tx#1 to #3 shown in Figure 80 are shifted horizontally from left to right in the figure by 1.5 wavelengths, and simultaneously shifted vertically upward by 0.5 wavelengths. Similarly, the second oblique antenna group Tx#4 to #6 shown in Figure 80 are shifted horizontally from left to right in the figure by 1.5 wavelengths, and simultaneously shifted vertically downward by 0.5 wavelengths.

[0347] Thus, in Figure 80, the antenna arrangement of the first oblique antenna group positioned in the first oblique direction and the antenna arrangement of the second oblique antenna group positioned in the second oblique direction are symmetrical with respect to a line parallel to the vertical direction (a line perpendicular to the horizontal direction). In other words, the first oblique antenna group Tx#1~#3 and the second oblique antenna group Tx#4~#6 are arranged in a way that is inverted symmetry (or left-right inverted symmetry or mirror symmetry) in the horizontal direction.

[0348] In this configuration, the transmitting antenna 106 in configuration example 1 (for example, Figure 8) is positioned horizontally. On the other hand, the transmitting antenna 106 in configuration example 2 is positioned diagonally, as shown in Figure 80. In other words, since the transmitting antenna 106 in configuration example 2 is positioned two-dimensionally, horizontally and vertically, the vertical aperture can be enlarged more in configuration example 2 compared to configuration example 1.

[0349] Furthermore, for example, the third oblique antenna group Rx#1 to #4 shown in Figure 80 are shifted horizontally from right to left in the figure by 0.5 wavelengths, and simultaneously shifted downward vertically by 1 wavelength. Similarly, the fourth oblique antenna group Rx#5 to #8 shown in Figure 80 are shifted horizontally from left to right in the figure by 0.5 wavelengths, and simultaneously shifted downward vertically by 1 wavelength.

[0350] Thus, the antenna arrangement of the third oblique antenna group, positioned in the third oblique direction, and the antenna arrangement of the fourth oblique antenna group, positioned in the fourth oblique direction, are symmetrical with respect to a line parallel to the vertical direction (a line perpendicular to the horizontal direction). In other words, the third oblique antenna group Rx#1~#4 and the fourth oblique antenna group Rx#5~#8 are arranged in a horizontal inversion symmetrical manner.

[0351] For example, the third oblique antenna group Rx#1~#4 and the fourth oblique antenna group Rx#5~#8 in arrangement example 2 shown in Figure 80 have a steeper inclination with respect to the horizontal compared to the first oblique antenna group Rx#1~#4 and the second oblique antenna group Rx#5~#8 in arrangement example 1 (for example, Figure 8), thus allowing for a larger vertical aperture.

[0352] Furthermore, for example, in the arrangement example 2 shown in Figure 80, the third oblique antenna group Rx#1~#4 and the fourth oblique antenna group Rx#5~#8 are each arranged at intervals of one wavelength or more in the vertical direction. Therefore, the element spacing of the third and fourth oblique antenna groups is such that grating lobes can occur in the vertical direction. In arrangement example 2, for example, the oblique directions of the first to fourth are not parallel but different directions, so by making the two-dimensional directions in which grating lobes occur (vertical and horizontal) different, it is possible to suppress grating lobes in the vertical direction.

[0353] Figure 81 shows an example of the arrangement of a virtual receiving array obtained by the antenna arrangement shown in Figure 80.

[0354] Here, the arrangement of the virtual receiving array may be expressed as shown in equation (16), for example, based on the position of the transmitting antenna 106 that constitutes the transmitting array antenna (e.g., the position of the feed point) and the position of the receiving antenna 202 that constitutes the receiving array antenna (e.g., the position of the feed point).

[0355] The position coordinates of the transmitting antenna 106 (e.g., Tx#n) that constitutes the transmitting array antenna are (X T_#n ,Y T_#n )(For example, n=1,.., NTx ) is expressed as, and the position coordinates of the receiving antenna 202 (for example, Rx#m) that constitutes the receiving array antenna are (X R_#m ,Y R_#m (For example, m=1,.., Na) and the position coordinates of the virtual antenna VA#k that constitutes the virtual receiving array are (X V_#k ,Y V_#k )(For example, k=1,.., N Tx This is expressed as ×Na). Note that in equation (16), for example, VA#1 is represented as the position reference (0,0) of the virtual receive array.

[0356] For example, from the arrangement of transmitting antennas Tx#1 to Tx#6 and receiving antennas Rx#1 to Rx#8 as shown in Figure 80, the position coordinates of the virtual antennas VA#1 to #48 that constitute the virtual receiving array antenna can be calculated from equation (16). For example, the position coordinates of virtual antennas VA#1 to #16 are (X V_#1 ,Y V_#1 )=(0,0), (X V_#2 ,Y V_#2 )=(-D H ,-2D V ), (X V_#3 ,Y V_#3 )=(-2D H , -4D V ), (X V_#4 ,Y V_#4 )=(-3D H ,-6D V ), (X V_#5 ,Y V_#5 )=(17D H , 0), (X V_#6 ,Y V_#6 )=(18D H , -2D V ), (X V_#7 ,Y V_#7 )=(19D H , -4D V ), (X V_#8 ,Y V_#8 )=(20 D H , -6D V ), (X V_#9 ,Y V_#9 )=(3D H , D V ), (X V_#10 ,YV_#10 )=(2D H , -D V ) , (X V_#11 ,Y V_#11 )=(D H , -3D V ), (X V_#12 ,Y V_#12 )=(0, -5D V ), (X V_#13 ,Y V_#13 )=(20D H , D V ), (X V_#14 ,Y V_#14 )=(21D H , -D V ), (X V_#15 ,Y V_#15 )=(22D H , -3D V ), (X V_#16 ,Y V_#16 )=(23D H , -5D V )

[0357] Here, in the case of Figures 80 and 81, D H and D V The following describes the case where each value is set to 0.5λ, but for example, they may also be set to values ​​of approximately 0.45λ to 0.8λ. Note that λ represents the wavelength of the carrier frequency of the radar transmission signal. For example, when using a chirp signal as the radar transmission signal, λ is the wavelength of the center frequency in the frequency sweep bandwidth of the chirp signal.

[0358] Next, we will describe an example of the direction estimation process in the direction estimation unit 213 when the above-described antenna arrangement is applied.

[0359] For example, the direction estimation unit 213 processes the code multiplexed signal transmitted from the transmitting antenna 106 to obtain a received signal (or the code separation result) DeMul z ncm (f b_cfar ,f s_cfar Using ), the virtual receive array correlation vector h(f) of the transmitting antenna 106 shown in equation (17) is obtained. b_cfar , f s_cfarIt generates a ) and performs direction estimation processing.

[0360] Virtual Receive Array Correlation Vector h(f b_cfar , f s_cfar ) is the number of transmitting antennas N Tx N is the product of the number of receiving antennas, Na. Tx Contains ×Na elements. Virtual receive array correlation vector h(f b_cfar , f s_cfar This is used for estimating the direction of the reflected wave signal from the target based on the phase difference between each receiving antenna 202.

[0361] For example, in the MIMO antenna arrangement example of arrangement example 2, in the example of Figure 80, N Tx Since =6 and Na=8, the virtual received array correlation vector h(f b_cfar , f s_cfar ) contains 48 elements, each corresponding to the received signals at VA#1 to VA48 in the virtual receiver array configuration shown in Figure 81.

[0362] The direction estimation unit 213 calculates, for example, the virtual receive array correlation vector h(f), which is the received signal of the virtual receive array composed of the transmit and receive antenna arrangement described above. b_cfar , f s_cfar The horizontal and vertical direction estimation process is performed using the ). Note that the operation of the direction estimation unit 213 thereafter is the same as the operation when using arrangement example 1, so the explanation is omitted.

[0363] Next, we will explain an example of the direction estimation result (computer simulation result) when applying the antenna arrangement described in the above-mentioned arrangement example 2.

[0364] Figure 82 shows MIMO array configuration (D) for configuration example 2. H = 0.5λ, D VThe direction estimation results when the beamformer method is used as the direction of arrival estimation algorithm for the direction estimation unit 213 are shown using (= 0.5λ). In Figure 82, as an example, the output of the direction of arrival estimation evaluation function values ​​in the horizontal ±90 degree range and the vertical ±90 degree range when the target true value is set to 0 degrees horizontally and 0 degrees vertically are plotted.

[0365] Figure 82(a) shows the normalized power values ​​in a two-dimensional direction, with the horizontal axis representing the horizontal direction and the vertical axis representing the vertical direction, as a grayscale color map. Figure 82(b) is the same as Figure 82(a), but with the horizontal axis representing the horizontal direction and the vertical axis representing the normalized power values, and the normalized power values ​​are similarly shown as a grayscale color map. Figure 82(c) is the same as Figure 82(a), but with the horizontal axis representing the vertical direction and the vertical axis representing the normalized power values, and the normalized power values ​​are similarly shown as a grayscale color map. In Figure 82, the normalized power values ​​may be shown, for example, as decibel values ​​(dB) normalized by peak power, and the same applies to plotting the direction estimation results in the other examples below.

[0366] Here, as shown in Figure 80, the antenna spacing between the first oblique antenna group Tx#1~#3 and the second oblique antenna group Tx#4~#6 in the transmitting antenna 106 of arrangement example 2 is more than one wavelength apart, and therefore, grating lobes can occur. Also, as shown in Figure 80, the antenna spacing between the third oblique antenna group Rx#1~#4 and the fourth oblique antenna group Rx#5~#8 in the receiving antenna 202 of arrangement example 2 is more than one wavelength apart, and therefore, grating lobes can occur.

[0367] Furthermore, as shown in Figure 81, in the virtual receiving array configuration, each virtual antenna is spaced at intervals of one wavelength or more in both the horizontal and vertical directions, which is an interval at which grating lobes can occur.

[0368] In arrangement example 2, the grating lobe is suppressed by devising the arrangement of the transmitting antenna 106 and the receiving antenna 202. For example, as shown in Figure 82, it can be seen that the grating lobe is suppressed to about -7.5 dB or less in a direction different from the peak direction of the target true value.

[0369] The principle of suppressing grating lobes using the MIMO antenna configuration in Configuration Example 2 will be explained below.

[0370] For example, Figure 83(a) shows the antenna configuration (hereinafter referred to as "comparison configuration 2a") using the first oblique antenna group Tx#1~#3 and the third oblique antenna group Rx#1~#4 from configuration example 2 shown in Figure 80, for comparison with configuration example 2. Figures 83(b), (c), and (d) show the direction estimation results using the beamformer method for the antenna configuration shown in Figure 83(a). In Figures 83(b), (c), and (d), as in Figure 82, the output of the arrival direction estimation evaluation function values ​​in the horizontal ±90 degree range and the vertical ±90 degree range, with the target true value set to horizontal 0 degrees and vertical 0 degrees.

[0371] Note that the virtual receiver array configuration when using comparison configuration 2a corresponds to VA#1~#4, #9~#12, and #17~#20 in Figure 81.

[0372] Similarly, Figure 84(a) shows the antenna configuration (hereinafter referred to as "comparison configuration 2b") using the second oblique antenna group Tx#4~#6 and the fourth oblique antenna group Rx#5~#8 from configuration example 2 shown in Figure 80, for comparison with configuration example 2. Figures 84(b), (c), and (d) show the direction estimation results using the beamformer method for the antenna configuration shown in Figure 84(a). In Figures 84(b), (c), and (d), as in Figure 82, the output of the arrival direction estimation evaluation function values ​​in the horizontal ±90 degree range and the vertical ±90 degree range, with the target true value set to horizontal 0 degrees and vertical 0 degrees, is plotted.

[0373] Note that the virtual receive array configuration when using comparison configuration 2b corresponds to #29~#32, #37~#40, and #45~#48 in Figure 81.

[0374] Furthermore, Figure 85(a) shows the antenna configuration when using the first oblique antenna group Tx#1~#3 and the fourth oblique antenna group Rx#5~#8 from Configuration Example 2 shown in Figure 80 (hereinafter referred to as "comparison configuration 2c") for comparison with Configuration Example 2. Also, Figures 85(b), (c), and (d) show the direction estimation results using the beamformer method for the antenna configuration shown in Figure 85(a). Note that in Figures 85(b), (c), and (d), as in Figure 82, the output of the arrival direction estimation evaluation function values ​​in the horizontal ±90 degree range and the vertical ±90 degree range when the target true value is set to horizontal 0 degrees and vertical 0 degrees.

[0375] Note that the virtual receive array configuration when using comparison configuration 2c corresponds to #5~#8, #13~#16, and #21~#24 in Figure 81.

[0376] Furthermore, Figure 86(a) shows the antenna configuration (hereinafter referred to as "comparison configuration 2d") when using the first oblique antenna group Tx#4~#6 and the third oblique antenna group Rx#1~#4 from configuration example 2 shown in Figure 80, for comparison with configuration example 2. Also, Figures 86(b), (c), and (d) show the direction estimation results using the beamformer method for the antenna configuration shown in Figure 86(a). Note that in Figures 86(b), (c), and (d), as in Figure 82, the output of the arrival direction estimation evaluation function values ​​in the horizontal ±90 degree range and the vertical ±90 degree range, when the target true value is set to horizontal 0 degrees and vertical 0 degrees.

[0377] Note that the virtual receive array configurations when using comparison configuration 2d correspond to #25~#28, #33~#36, and #41~#44 in Figure 81.

[0378] For example, we will explain the case where the first oblique antenna group Tx#1~#3 and the third oblique antenna group Rx#1~#4 are used, as shown in comparative configuration 2a in Figure 83(a), and the case where the second oblique antenna group Tx#4~#6 and the fourth oblique antenna group Rx#5~#8 are used, as shown in comparative configuration 2b in Figure 84(a).

[0379] The orientation of the transmitting antennas Tx#1~#3 (for example, corresponding to the first oblique antenna group) in comparison configuration 2a shown in Figure 83(a) is different from the orientation of the transmitting antennas Tx#4~#6 (for example, corresponding to the second oblique antenna group) in comparison configuration 2b shown in Figure 84(a). Furthermore, the orientation of the receiving antennas Rx#1~#4 (for example, corresponding to the third oblique antenna group) in comparison configuration 2a is different from the orientation of the receiving antennas Rx#5~#8 (for example, corresponding to the fourth oblique antenna group) in comparison configuration 2b. As a result, as shown in Figures 83(b) and 84(b), the horizontal and vertical two-dimensional angular directions in which grating lobes are generated do not coincide and are shifted between comparison configuration 2a and comparison configuration 2b.

[0380] On the other hand, as shown in Figure 83(b) and Figure 84(b), the angular direction of the main lobe corresponding to the target true value (e.g., horizontal 0 degrees, vertical 0 degrees) is the same in comparison configuration 2a and comparison configuration 2b.

[0381] Therefore, as shown in Figure 80, in arrangement example 2, which includes the first to fourth oblique antenna groups, the direction of generation (two-dimensional angular direction) of the grating lobes generated in comparative arrangement 2a, which includes the first and third oblique antenna groups, and the direction of generation of the grating lobes generated in comparative arrangement 2b, which includes the second and fourth oblique antenna groups, do not coincide and tend to be dispersed. For this reason, in arrangement example 2, as shown in Figure 82(a), the peak level in the grating lobe direction tends to be suppressed compared to the peak in the target true value direction.

[0382] Next, we will explain the case where, for example, the first oblique antenna group Tx#1~#3 and the fourth oblique antenna group Rx#5~#8 are used, as shown in comparative configuration 2c in Figure 85(a), and the case where the second oblique antenna group Tx#4~#6 and the third oblique antenna group Rx#1~#4 are used, as shown in comparative configuration 2d in Figure 86(a).

[0383] The orientation of the transmitting antennas Tx#1~#3 (for example, corresponding to the first oblique antenna group) in comparison configuration 2c shown in Figure 85(a) is different from the orientation of the transmitting antennas Tx#4~#6 (for example, corresponding to the second oblique antenna group) in comparison configuration 2d shown in Figure 86, and they are not parallel. Also, the orientation of the receiving antennas Rx#5~#8 (for example, corresponding to the fourth oblique antenna group) in comparison configuration 2c is different from the orientation of the receiving antennas Rx#1~#4 (for example, corresponding to the third oblique antenna group) in comparison configuration 2d, and they are not parallel. Therefore, as shown in Figures 85(b) and 86(b), the horizontal and vertical two-dimensional angular directions in which the grating lobe is generated do not coincide and are shifted between comparison configuration 2c and comparison configuration 2d.

[0384] On the other hand, as shown in Figures 85(b) and 86(b), the angular direction of the main lobe corresponding to the target true value (e.g., 0 degrees horizontal, 0 degrees vertical) is the same for comparison configuration 2c and comparison configuration 2d.

[0385] Therefore, as shown in Figure 80, in arrangement example 2, which includes the first to fourth oblique antenna groups, the direction of generation (two-dimensional angular direction) of the grating lobes generated in comparative arrangement 2c, which includes the first and fourth oblique antenna groups, and the grating lobes generated in comparative arrangement 2d, which includes the second and third oblique antenna groups, do not coincide and tend to be dispersed. For this reason, in arrangement example 2, as shown in Figure 82(a), the peak level in the grating lobe direction is more easily suppressed compared to the peak in the target true value direction.

[0386] Here, the virtual receiver array configuration shown in Figure 81 is the same configuration as the virtual receiver array partially composed of virtual receiver arrays corresponding to comparison configurations 2a, 2b, 2c, and 2d. Therefore, the direction estimation result using the virtual receiver array configuration shown in Figure 81 suppresses grating lobes in directions different from the peak direction of the target true value, as shown in Figure 82(a). In other words, in configuration example 2, the angular directions in which grating lobes are generated are dispersed in different directions by the multiple oblique antenna groups included in each of the transmitting antenna 106 and receiving antenna 202. For this reason, for example, as shown in Figure 82(b), in configuration example 2, the normalized power value of the grating lobes tends to be suppressed to a lower value than the normalized power value of the main lobe relative to the target true value. For example, in Figure 82(b), it can be seen that peaks in directions different from the peak direction of the target true value are suppressed to about -7.5 dB or less.

[0387] For example, in the antenna arrangement example 2 shown in Figure 80, the arrangement directions of the first and second oblique antenna groups are horizontally inverted symmetric, and the arrangement directions of the third and fourth oblique antenna groups are horizontally inverted symmetric. In this case, the virtual receiving array arrangements corresponding to comparison arrangement 2a and comparison arrangement 2b are horizontally inverted symmetric. As a result, for example, as shown in Figure 83(b) and Figure 84(b), in comparison arrangement 2a and comparison arrangement 2b, the horizontal and vertical two-dimensional directions in which the grating lobe occurs are horizontally inverted symmetric, and the angular displacement in the horizontal and vertical two-dimensional directions in which the grating lobe occurs becomes larger.

[0388] Similarly, for example, in the antenna arrangement of arrangement example 2 shown in Figure 80, the arrangement directions of the first and second oblique antenna groups are horizontally inverted symmetric, and the arrangement directions of the third and fourth oblique antenna groups are horizontally inverted symmetric. In this case, the virtual receiving array arrangements corresponding to comparison arrangement 2c and comparison arrangement 2d are horizontally inverted symmetric. As a result, for example, as shown in Figure 85(b) and Figure 86(b), in comparison arrangement c and comparison arrangement d, the horizontal and vertical two-dimensional directions in which the grating lobe occurs are horizontally inverted symmetric, and the angular displacement in the horizontal and vertical two-dimensional directions in which the grating lobe occurs becomes larger.

[0389] Therefore, in arrangement example 2, if the arrangement directions of the first and second oblique antenna groups are horizontally symmetrical, and the arrangement directions of the third and fourth oblique antenna groups are also horizontally symmetrical, then, for example, the closer the oblique inclination of each of the first to fourth oblique antenna groups is to 45 degrees with respect to the horizontal, the larger the two-dimensional angular spacing (or displacement) in the horizontal and vertical directions that generates grating lobes tends to be.

[0390] Furthermore, for example, if the arrangement directions of the first and second oblique antenna groups are not horizontally symmetrical, or if the arrangement directions of the third and fourth oblique antenna groups are not horizontally symmetrical, the closer the oblique inclination of the first to fourth oblique antenna groups is to 45 degrees with respect to the horizontal, the larger the two-dimensional angular spacing in the horizontal and vertical directions at which grating lobes occur tends to be.

[0391] Antenna arrangements that result in larger gaps in the two-dimensional angular directions (horizontal and vertical) where such grating lobes occur are preferable, for example, when the number of antennas in the radar device 10 is small. For example, the fewer the number of antennas in the radar device 10, the wider the beamwidth of the main beam in direction estimation tends to be. Therefore, when the directions of the suppressed grating lobes are close together, the fewer the number of antennas in the radar device 10, the greater the overlap of the grating lobe power due to the beamwidth expansion, which can increase the power of the grating lobes. Therefore, the fewer the number of antennas in the radar device 10, the worse the grating lobe suppression performance becomes, and the higher the probability of false detection in the radar device 10. Thus, when the number of antennas in the radar device 10 is small, for example, arrangement example 2, in which the arrangement directions of the first and second oblique antenna groups are horizontally inverted symmetric, and the arrangement directions of the third and fourth oblique antenna groups are horizontally inverted symmetric, can suppress the overlap of grating lobe power, thereby improving the grating lobe suppression performance.

[0392] As described above, under arrangement condition 2, the transmitting antenna 106 includes a first oblique antenna group arranged in a first oblique direction and a second oblique antenna group arranged in a second oblique direction. Therefore, compared to arrangement condition 1, the vertical aperture length of the virtual receiving array can be increased, and the vertical angle measurement accuracy or resolution of the radar device 10 can be improved.

[0393] Furthermore, under arrangement condition 2, as described above, by distributing the direction in which grating lobes are generated within a two-dimensional plane consisting of horizontal and vertical elements, it is possible to suppress the vertical grating lobes that occur when the inclinations in the first to fourth diagonal directions are set steeper with respect to the horizontal direction. This allows for a larger vertical aperture length of the virtual receiving array, thereby improving the vertical angle measurement accuracy or resolution of the radar device 10.

[0394] For example, even if the second and fourth oblique antenna groups of comparison configuration 2b are placed at arbitrary locations relative to the first and third oblique antenna groups of comparison configuration 2a, a similar grating lobe suppression effect can be obtained. Similarly, even if the second and third oblique antenna groups of comparison configuration 2d are placed at arbitrary locations relative to the first and fourth oblique antenna groups of comparison configuration 2c, a similar grating lobe suppression effect can be obtained.

[0395] Therefore, in arrangement example 2, for example, the first oblique antenna group and the second oblique antenna group can be arranged so that their horizontal positions do not overlap, and it is possible to arrange transmitting antenna elements with a larger vertical size (for example, a size of one wavelength or more).

[0396] Similarly, in arrangement example 2, for example, the third oblique antenna group and the fourth oblique antenna group can be arranged so that their horizontal positions do not overlap, and it is possible to arrange receiving antenna elements with larger vertical sizes (e.g., sizes of one wavelength or more).

[0397] Therefore, in arrangement example 2, the antenna elements of the transmitting antenna 106 and the receiving antenna 202 can be arranged in a single line diagonally, making it possible to arrange antenna elements with a large vertical size (for example, antenna elements with a size of one wavelength or more).

[0398] Furthermore, even if the relative positions of the transmitting antenna 106 and the receiving antenna 202 differ in the arrangement of the virtual receiving array, the same virtual receiving array arrangement can be configured. Therefore, the relative positions of the transmitting antenna 106 and the receiving antenna 202 are not limited to the antenna arrangement example shown in Figure 80, but can be set arbitrarily. This is also true for other arrangement configuration examples described below. For example, the distance between the transmitting antenna 106 and the receiving antenna 202 may be sufficiently wider than the size of the antenna elements, or they may be arranged in a horizontally shifted configuration so that they do not overlap vertically.

[0399] As described above, in arrangement example 2, the radar device 10 includes, for example, a first oblique antenna group arranged in a first oblique direction and a second oblique antenna group arranged in a second oblique direction. The receiving antenna 202 includes, for example, a third oblique antenna group arranged in a third oblique direction and a fourth oblique antenna group arranged in a fourth oblique direction. Furthermore, in the antenna arrangement of the radar device 10, the first oblique direction and the second oblique direction are different directions from each other, and the third oblique direction and the fourth oblique direction are different directions from each other.

[0400] This antenna configuration allows for the application of antenna elements of any vertical size (e.g., vertical) in the MIMO array configuration of the radar device 10, and also suppresses grating lobes that occur in the virtual receiving array.

[0401] Furthermore, in arrangement example 2, as described above, the grating lobe suppression effect can be obtained due to the difference in the arrangement direction of the first to fourth oblique antenna groups in the transmitting antenna 106 and the receiving antenna 202. For this reason, in arrangement example 2, for example, the element spacing of the transmitting antenna 106 and the receiving antenna 202 can be set arbitrarily. This makes it possible to expand the aperture length of the virtual receiving array depending on the setting of at least one of the element spacing of the transmitting antenna 106 and the element spacing of the receiving antenna 202, thereby improving the vertical and horizontal angle measurement accuracy and angle separation performance of the radar device 10.

[0402] Therefore, according to arrangement example 2, the angle measurement accuracy or resolution of the radar device 10 can be improved while suppressing grating lobes.

[0403] In arrangement example 2, additional antenna elements may be added to at least one of the transmitting antenna 106 and the receiving antenna 202 compared to the antenna configuration shown in Figure 80. In other words, each of the transmitting antenna 106 and the receiving antenna 202 of the radar device 10 should include at least the antenna elements arranged in Figure 80. In this case, for example, the virtual antenna is added additively to the virtual receiving array arrangement shown in equation (16). For example, by adding an antenna element to at least one of the transmitting antenna 106 and the receiving antenna 202, another virtual antenna is added to the virtual receiving array arrangement shown in Figure 80. Even in antenna arrangements including such arrangement example 2, the effects of arrangement example 2 described above are maintained, and the same effects as arrangement example 2 can be obtained.

[0404] For example, additional antennas may be added to the antenna configuration of Arrangement Example 2. Adding antennas further reduces the grating lobe or side lobe level suppressed by Arrangement Example 2, thereby reducing false detections during angle measurement by the radar device 10 and improving angle measurement performance. The addition of antennas can be applied similarly to subsequent arrangement examples or modifications, yielding similar effects.

[0405] Furthermore, in the MIMO array configuration of Configuration Example 2, a configuration in which the horizontal and vertical directions are swapped may be applied. In this case, the virtual receiving array configuration will be one in which the horizontal and vertical directions are swapped, and angle separation performance with the horizontal and vertical directions swapped will be obtained. Note that the swapping of the horizontal and vertical directions in the MIMO array configuration can also be applied to subsequent configuration examples or modifications, and the virtual receiving array configuration in subsequent configuration examples will be one in which the horizontal and vertical directions are swapped.

[0406] Furthermore, in the MIMO antenna configuration of Configuration Example 2, the configuration of the transmitting antenna 106 and the receiving antenna 202 may be swapped. In this case, for example, the configuration of the receiving antenna 202 shown in Configuration Example 2 may be used as the configuration of the transmitting antenna 106, and the configuration of the transmitting antenna 106 shown in Configuration Example 2 may be used as the configuration of the receiving antenna 202. Even if the configuration of the transmitting antenna 106 and the receiving antenna 202 are swapped, the configuration of the virtual receiving array will remain the same, and similar effects can be obtained. Note that the swapping of the configuration of the transmitting antenna 106 and the receiving antenna 202 can also be applied to the transitional configuration example or modified example.

[0407] <Layout example 2a> Figure 87 shows an example of the arrangement of the transmitting antenna 106 (represented as Tx, for example) and the receiving antenna 202 (represented as Rx, for example) according to arrangement example 2a (for example, an example of a MIMO antenna arrangement).

[0408] In the example shown in Figure 87, the number of transmitting antennas N Tx There are 6 (e.g., Tx#1, Tx#2, Tx#3, Tx#4, Tx#5, and Tx#6), and the number of receiving antennas Na is 8 (e.g., Rx#1, Rx#2, Rx#3, Rx#5, Rx#6, Rx#7, and Rx#8).

[0409] In Figure 87, N Tx The six transmitting antennas Tx#1 to #6 include the first oblique antenna group Tx#1 to #3, which is arranged in the first oblique direction, and the second oblique antenna group Tx#4 to #6, which is arranged in the second oblique direction. In Figure 87, the first oblique direction and the second oblique direction are not parallel, but are in different directions from each other.

[0410] Furthermore, in Figure 87, Na = 8 receiving antennas Rx#1~#8 include the third oblique antenna group Rx#1~#4, which is arranged in the third oblique direction, and the fourth oblique antenna group Rx#5~#8, which is arranged in the fourth oblique direction. In Figure 87, the third oblique direction and the fourth oblique direction are not parallel, but are different directions from each other.

[0411] Based on these findings, the antenna arrangement in arrangement example 2a shown in Figure 87 satisfies arrangement condition 2.

[0412] Furthermore, in arrangement example 2a, as shown in Figure 87, the arrangement direction of the first oblique antenna group and the arrangement direction of the fourth oblique antenna group coincide and are parallel. Also, in arrangement example 2a, as shown in Figure 87, the arrangement direction of the second oblique antenna group and the arrangement direction of the third oblique antenna group coincide and are parallel. That is, in Figure 87, the first oblique direction and the fourth oblique direction are in the same direction, and the second oblique direction and the third oblique direction are in the same direction.

[0413] Thus, in an antenna arrangement that satisfies arrangement condition 2, the first diagonal direction may be set to an inclination that coincides with the third or fourth diagonal direction, and the second diagonal direction may be set to an inclination that coincides with the third or fourth diagonal direction.

[0414] For example, the first oblique antenna group Tx#1~#3 shown in Figure 87 is shifted horizontally from left to right by an interval of two wavelengths, and simultaneously shifted vertically upward by an interval of two wavelengths. Similarly, the second oblique antenna group Tx#4~#6 shown in Figure 87 is shifted horizontally from left to right by an interval of two wavelengths, and simultaneously shifted vertically downward by an interval of two wavelengths. In other words, the first oblique antenna group Tx#1~#3 and the second oblique antenna group Tx#4~#6 are arranged in a horizontally inverted symmetrical manner.

[0415] In this configuration, the transmitting antenna 106 in configuration example 1 (for example, Figure 8) is positioned horizontally. On the other hand, the transmitting antenna 106 in configuration example 2a is positioned diagonally, as shown in Figure 87. In other words, since the transmitting antenna 106 in configuration example 2a is positioned two-dimensionally, horizontally and vertically, configuration example 2a can achieve a larger vertical aperture compared to configuration example 1.

[0416] Furthermore, for example, the third oblique antenna group Rx#1~#4 shown in Figure 87 is shifted horizontally from right to left in the figure by 0.5 wavelengths, and simultaneously shifted vertically upward by 0.5 wavelengths. Similarly, the fourth oblique antenna group Rx#5~#8 shown in Figure 87 is shifted horizontally from left to right in the figure by 0.5 wavelengths, and simultaneously shifted vertically upward by 0.5 wavelengths. In other words, the third oblique antenna group Rx#1~#4 and the fourth oblique antenna group Rx#5~#8 are arranged in a horizontally inverted symmetrical manner.

[0417] Figure 88 shows an example of the arrangement of a virtual receiving array obtained by the antenna arrangement shown in Figure 87. The position coordinates of the virtual antennas VA#1 to #48 that constitute the virtual receiving array antenna are calculated from equation (16) based on the arrangement of the transmitting antennas Tx#1 to Tx#6 and the receiving antennas Rx#1 to Rx#8.

[0418] Next, we will explain an example of the direction estimation result (computer simulation result) when applying the antenna arrangement described in the above-mentioned arrangement example 2a.

[0419] Figure 89 shows the MIMO array configuration of configuration example 2a (D H = 0.5λ, D V The direction estimation results when the beamformer method is used as the direction of arrival estimation algorithm for the direction estimation unit 213 are shown using (= 0.5λ). In Figure 89, as an example, the output of the direction of arrival estimation evaluation function values ​​in the horizontal ±90 degree range and the vertical ±90 degree range when the target true value is set to 0 degrees horizontally and 0 degrees vertically are plotted.

[0420] Figure 89(a) shows the normalized power values ​​in a two-dimensional direction, with the horizontal axis representing the horizontal direction and the vertical axis representing the vertical direction, as a grayscale color map. Figure 89(b) is the same as Figure 89(a), but with the horizontal axis representing the horizontal direction and the vertical axis representing the normalized power values, and the normalized power values ​​are similarly shown as a grayscale color map. Figure 89(c) is the same as Figure 89(a), but with the horizontal axis representing the vertical direction and the vertical axis representing the normalized power values, and the normalized power values ​​are similarly shown as a grayscale color map. Note that in Figure 89, the normalized power values ​​may be shown as decibel values ​​(dB) normalized by peak power, and the same applies to plotting the direction estimation results in the other examples below.

[0421] As shown in the virtual receiver array configuration in Figure 88, each virtual antenna is spaced with many intervals of one wavelength or more in both the horizontal and vertical directions, and the spacing of the virtual antennas is such that grating lobes can occur. In contrast, as shown in Figure 89, it can be seen that grating lobes are suppressed to about -6 dB or less in a direction different from the peak direction of the target true value.

[0422] For example, in the antenna arrangement example 2a shown in Figure 87, the arrangement directions of the first and second oblique antenna groups are horizontally symmetrical, and the arrangement directions of the third and fourth oblique antenna groups are horizontally symmetrical. For example, the inclination of the first to fourth oblique directions is 45 degrees with respect to the horizontal. In this case, as shown in Figure 89(a), the arrangement results in the widest possible spacing in the two-dimensional angular directions of the horizontal and vertical where grating lobes are generated.

[0423] Antenna arrangements that result in larger gaps in the two-dimensional angular directions (horizontal and vertical) where such grating lobes occur are preferable, for example, when the number of antennas in the radar device 10 is small. For example, the fewer the number of antennas in the radar device 10, the wider the beamwidth of the main beam in direction estimation tends to be. Therefore, when the directions of the suppressed grating lobes are close together, the fewer the number of antennas in the radar device 10, the greater the overlap of the grating lobe power due to the beamwidth expansion, which can increase the power of the grating lobes. Therefore, the fewer the number of antennas in the radar device 10, the worse the grating lobe suppression performance becomes, and the higher the probability of false detection in the radar device 10. Thus, when the number of antennas in the radar device 10 is small, for example, arrangement example 2, in which the arrangement directions of the first and second oblique antenna groups are horizontally inverted symmetric, and the arrangement directions of the third and fourth oblique antenna groups are horizontally inverted symmetric, can suppress the overlap of grating lobe power, thereby improving the grating lobe suppression performance.

[0424] Furthermore, in arrangement example 2a, the orientation of the first oblique antenna group coincides with the orientation of the fourth oblique antenna group, making them parallel. Also, in arrangement example 2a, the orientation of the second oblique antenna group coincides with the orientation of the third oblique antenna group, making them parallel. Thus, in arrangement example 2a, the first oblique direction is set to an inclination that coincides with the third or fourth oblique direction, and the second oblique direction is set to an inclination that coincides with the third or fourth oblique direction, thereby achieving a grating lobe suppression effect similar to that of arrangement example 2.

[0425] Furthermore, in arrangement example 2a, as shown in Figure 87, the antenna elements of the transmitting antenna 106 and the receiving antenna 202 can be arranged in a single line diagonally, making it possible to arrange antenna elements with a large vertical size (for example, antenna elements with a size of one wavelength or more).

[0426] As described above, in arrangement example 2a, similar to arrangement example 2, antenna elements of any vertical size (e.g., vertical) can be applied in the MIMO array arrangement of the radar device 10, and grating lobes generated in the virtual receiving array can be suppressed.

[0427] <Layout example 2b> In arrangement example 2b, for example, either the first diagonal direction or the second diagonal direction that satisfies arrangement condition 2 may coincide with and be parallel to the third or fourth diagonal direction, while the other of the first and second diagonal directions may not coincide with and be different from the third and fourth diagonal directions.

[0428] Figure 90 shows an example of the arrangement of the transmitting antenna 106 (represented as Tx, for example) and the receiving antenna 202 (represented as Rx, for example) according to arrangement example 2b (for example, an example of a MIMO antenna arrangement).

[0429] In the example shown in Figure 90, the number of transmitting antennas N Tx There are 6 (e.g., Tx#1, Tx#2, Tx#3, Tx#4, Tx#5, and Tx#6), and the number of receiving antennas Na is 8 (e.g., Rx#1, Rx#2, Rx#3, Rx#5, Rx#6, Rx#7, and Rx#8).

[0430] In Figure 90, N Tx The six transmitting antennas Tx#1 to #6 include the first oblique antenna group Tx#1 to #3, which is arranged in the first oblique direction, and the second oblique antenna group Tx#4 to #6, which is arranged in the second oblique direction. In Figure 90, the first oblique direction and the second oblique direction are not parallel, but are different oblique directions from each other.

[0431] Furthermore, in Figure 90, the Na=8 receiving antennas Rx#1~#8 include the third oblique antenna group Rx#1~#4, which is arranged in the third oblique direction, and the fourth oblique antenna group Rx#5~#8, which is arranged in the fourth oblique direction. In Figure 90, the third oblique direction and the fourth oblique direction are not parallel but are different directions from each other.

[0432] Based on these findings, the antenna arrangement in arrangement example 2b shown in Figure 90 satisfies arrangement condition 2.

[0433] Furthermore, in arrangement example 2b, as shown in Figure 90, the arrangement direction of the first oblique antenna group and the arrangement direction of the fourth oblique antenna group do not coincide and are in different directions. On the other hand, as shown in Figure 90, the arrangement direction of the second oblique antenna group and the arrangement direction of the third oblique antenna group coincide and are parallel. In other words, in Figure 90, the first oblique direction and the fourth oblique direction are in the same direction, while the second oblique direction and the third oblique direction are in different directions.

[0434] Thus, even if either the first diagonal direction or the second diagonal direction is set to an inclination that coincides with the third diagonal direction or the fourth diagonal direction, the arrangement condition 2 is still satisfied.

[0435] For example, the first oblique antenna group Tx#1 to #3 shown in Figure 90 is shifted horizontally from left to right by an interval of two wavelengths, and simultaneously shifted vertically upward by an interval of two wavelengths. Similarly, the second oblique antenna group Tx#4 to #6 shown in Figure 90 is shifted horizontally from left to right by an interval of two wavelengths, and simultaneously shifted vertically downward by an interval of two wavelengths. In other words, the first oblique antenna group Tx#1 to #3 and the second oblique antenna group Tx#4 to #6 are arranged in a horizontally inverted symmetrical manner.

[0436] In this configuration, the transmitting antenna 106 in configuration example 1 (for example, Figure 8) is positioned horizontally. On the other hand, the transmitting antenna 106 in configuration example 2b is positioned diagonally, as shown in Figure 90. In other words, since the transmitting antenna 106 in configuration example 2b is positioned two-dimensionally, horizontally and vertically, the vertical aperture can be enlarged more in configuration example 2b compared to configuration example 1.

[0437] Furthermore, for example, the third oblique antenna group Rx#1~#4 shown in Figure 90 is shifted horizontally from right to left in the figure by 0.5 wavelengths, and simultaneously shifted vertically upward by 0.5 wavelengths. Similarly, the fourth oblique antenna group Rx#5~#8 shown in Figure 90 is shifted horizontally from left to right in the figure by 0.5 wavelengths, and simultaneously shifted vertically upward by 1 wavelength. In other words, the third oblique antenna group Rx#1~#4 and the fourth oblique antenna group Rx#5~#8 are not horizontally inverted symmetrical in their arrangement.

[0438] Figure 91 shows an example of the arrangement of a virtual receiving array obtained by the antenna arrangement shown in Figure 90. The position coordinates of the virtual antennas VA#1 to #48 that constitute the virtual receiving array antenna are calculated from equation (16) based on the arrangement of the transmitting antennas Tx#1 to Tx#6 and the receiving antennas Rx#1 to Rx#8.

[0439] Next, we will explain an example of the direction estimation result (computer simulation result) when applying the antenna arrangement described in the above-mentioned arrangement example 2b.

[0440] Figure 92 shows the MIMO array configuration of configuration example 2b (D H = 0.5λ, D V The direction estimation results when the beamformer method is used as the direction of arrival estimation algorithm for the direction estimation unit 213 are shown using (= 0.5λ). In Figure 92, as an example, the output of the direction of arrival estimation evaluation function values ​​in the horizontal ±90 degree range and the vertical ±90 degree range when the target true value is set to 0 degrees horizontally and 0 degrees vertically are plotted.

[0441] Figure 92(a) shows the normalized power values ​​in a two-dimensional direction, with the horizontal axis representing the horizontal direction and the vertical axis representing the vertical direction, as a grayscale color map. Figure 92(b) is the same as Figure 92(a), but with the horizontal axis representing the horizontal direction and the vertical axis representing the normalized power values, and the normalized power values ​​are similarly shown as a grayscale color map. Figure 92(c) is the same as Figure 92(a), but with the horizontal axis representing the vertical direction and the vertical axis representing the normalized power values, and the normalized power values ​​are similarly shown as a grayscale color map. Note that in Figure 92, the normalized power values ​​may be shown as decibel values ​​(dB) normalized by peak power, and the same applies to plotting the direction estimation results in the other examples below.

[0442] As shown in the virtual receiver array configuration in Figure 91, each virtual antenna is spaced at intervals of one wavelength or more in both the horizontal and vertical directions, and the spacing between the virtual antennas is such that grating lobes can occur. In contrast, as shown in Figure 92, it can be seen that grating lobes are suppressed to about -4dB or less in a direction different from the peak direction of the target true value.

[0443] In arrangement example 2b, for example, the orientation of the first oblique antenna group and the orientation of the fourth oblique antenna group do not coincide and are in different directions, but the orientation of the second oblique antenna group and the orientation of the third oblique antenna group coincide and are parallel. In this way, even if either the first oblique direction or the second oblique direction has an inclination that coincides with the third oblique direction or the fourth oblique direction, arrangement condition 2 is satisfied and a grating lobe suppression effect similar to that in arrangement example 2 can be obtained.

[0444] Furthermore, in arrangement example 2b, as shown in Figure 90, the antenna elements of the transmitting antenna 106 and the receiving antenna 202 can be arranged in a single line diagonally, making it possible to arrange antenna elements with a large vertical size (for example, antenna elements with a size of one wavelength or more).

[0445] As described above, in arrangement example 2b, similar to arrangement example 2, antenna elements of any vertical size (e.g., vertical) can be applied in the MIMO array arrangement of the radar device 10, and grating lobes generated in the virtual receiving array can be suppressed.

[0446] The following describes a modified version of arrangement example 2.

[0447] For example, modifications 1-4, 6, and 7 of Configuration Example 1 may be applied similarly to the receiving antenna of Configuration Example 2 (or Configuration Examples 2a, 2b). Even when modifications 1-4, 6, and 7 of Configuration Example 1 are applied to Configuration Example 2, the same effects as Configuration Example 2 can be obtained. For example, "Configuration Example 1" in the explanations of each of the modifications 1-4, 6, and 7 of Configuration Example 1 may be replaced with "Configuration Example 2," and the "first oblique antenna group" and "second oblique antenna group" of Configuration Example 1 may be replaced (interpreted) with the "third oblique antenna group" and "fourth oblique antenna group" of Configuration Example 2, respectively. In this way, Configuration Example 2 can also obtain the same effects as the modifications 1-4, 6, and 7 of Configuration Example 1. Note that the explanation of applying the same modifications 1-4, 6, and 7 of Configuration Example 1 to Configuration Example 2 is omitted.

[0448] The following describes additional parts of the same content as in Modification Examples 1-4, 6, and 7 of Arrangement Example 1, but applied to the "first oblique antenna group" and "second oblique antenna group" included in the transmitting antenna 106 of Arrangement Example 2.

[0449] The following describes the additional parts of Modifications 1-4, 6, and 7 of Configuration Example 2, which correspond to Modifications 1-4, 6, and 7 of Configuration Example 1.

[0450] [Modification 1 of arrangement example 2] In Modification 1 of Arrangement Example 2, the spacing between the first oblique antenna group and the second oblique antenna group (for example, the minimum spacing) may be wider than, for example, that in Arrangement Example 2 (or Arrangement Examples 2a, 2b).

[0451] For example, in the case of arrangement example 2, as shown in Figure 80, the minimum distance between the first oblique antenna group and the second oblique antenna group (for example, the distance between Tx#3 and Tx#4) is N a The spacing is set to be narrower than the horizontal aperture length of the individual receiving antennas 202 (for example, the spacing between Rx#4 and Rx#8). In Modification 1 of Arrangement Example 2, for example, the minimum spacing between the first oblique antenna group and the second oblique antenna group (for example, the spacing between Tx#3 and Tx#4) is N a The aperture length may be set wider than the horizontal aperture length of the individual receiving antennas 202. In this case as well, the same effect as in arrangement example 2 can be obtained.

[0452] Furthermore, by widening the minimum distance between the first and second oblique antenna groups, the peak in the target true value direction in the horizontal direction becomes sharper, thereby improving the horizontal angle measurement accuracy or estimation accuracy of the radar device 10. In modification 1 of arrangement example 2, similar to modification 1 of arrangement example 1, the lateral (horizontal) sidelobe level of the peak in the target true value direction can be increased. Therefore, depending on requirements such as the detection target assumed by the radar device 10, the distance between the first and second oblique antenna groups (for example, the minimum distance) may be set within a suitable range.

[0453] [Modification 2 of arrangement example 2] In Modification 2 of Arrangement Example 2, for example, the distance between the first oblique antenna group and the second oblique antenna group (e.g., the minimum distance) may be closer compared to Arrangement Example 2 (or Arrangement Examples 2a, 2b). Also, in Modification 2 of Arrangement Example 2, for example, some of the antennas included in the first oblique antenna group and the second oblique antenna group may overlap.

[0454] For example, in the case of arrangement example 2, as shown in Figure 80, the minimum distance between the first oblique antenna group Tx#1~#3 and the second oblique antenna group Tx#4~#6 (the distance between Tx#3 and Tx#4) is N a This is narrower than the horizontal aperture length of the individual receiving antennas 202 (for example, the distance between Rx#4 and Rx#8).

[0455] In the modified example 2 of the arrangement example, for example, the minimum distance between the first oblique antenna group Tx#1~#3 and the second oblique antenna group Tx#4~#6 (the distance between Tx#3 and Tx#4) may be brought even closer together.

[0456] Alternatively, in the modified example 2 of arrangement example 2, for example, some of the antennas in the first oblique antenna group and the second oblique antenna group may be arranged to overlap.

[0457] Even in these cases, the same effects as in Arrangement Example 2, and the same effects as in Modification Example 2 of Arrangement Example 1, can be obtained.

[0458] [Modification 3 of arrangement example 2] In Modification 3 of Arrangement Example 2, for example, the inclination of the first and second oblique antenna groups (e.g., the change in position in the vertical direction relative to the horizontal direction) may be set more gently than in Arrangement Example 2. Even in this case, the same effects as in Arrangement Example 2 and the same effects as Modification 3 of Arrangement Example 1 can be obtained.

[0459] [Modification 4 of arrangement example 2] For example, in the arrangement example 2 shown in Figure 80, the case where the first oblique antenna group Tx#1~#3 and the second oblique antenna group Tx#4~#6 are arranged in a horizontally inverted symmetrical configuration was described. However, the explanation is not limited to this, and the first and second oblique antenna groups do not necessarily have to be arranged in a horizontally inverted symmetrical configuration. For example, the first oblique direction and the second oblique direction do not need to be parallel but different directions. This allows for the same effect as in arrangement example 2 to be obtained.

[0460] For example, a) the first oblique antenna group and the second oblique antenna group may have asymmetrical inclinations, or different antenna spacings may be set in the horizontal and vertical directions, respectively.

[0461] Alternatively, for example, b) the positions of the first oblique antenna group and the second oblique antenna group may be shifted vertically.

[0462] Furthermore, for example, the number of antennas included in the first oblique antenna group and the second oblique antenna group may be different.

[0463] Furthermore, for example, the arrangement of the first and second oblique antenna groups may be a combination of any two or three of the following: a) an arrangement in which the first and second oblique antenna groups have asymmetrical inclinations, b) an arrangement in which the number of antennas included in the first and second oblique antenna groups are different, and c) an arrangement in which the positions of the first and second oblique antenna groups are shifted vertically.

[0464] These measures make it possible to obtain the same effects as in Arrangement Example 2, and the same effects as in Modification Example 4 of Arrangement Example 1.

[0465] Furthermore, variations in the arrangement of the first and second oblique antenna groups included in the transmitting antenna 106, as described above, may be combined with variations in the arrangement of the third and fourth oblique antenna groups included in the receiving antenna 202.

[0466] Figure 93 shows an example (referred to as "Configuration Example 2-4a") in which the first oblique antenna group Tx#1~#3 and the second oblique antenna group Tx#4~#6 are arranged with horizontally symmetrical inclinations, while the third oblique antenna group Rx#1~#4 and the fourth oblique antenna group Rx#5~#8 are arranged asymmetrically in the horizontal direction. Even in the case of Configuration Example 2-4a, the same effect as in Configuration Example 2 can be obtained.

[0467] Figure 94 shows an example (referred to as "Configuration Example 2-4b") in which the first oblique antenna group Tx#1~#3 and the second oblique antenna group Tx#4~#6 are arranged with an asymmetrical tilt in the horizontal direction, and the third oblique antenna group Rx#1~#4 and the fourth oblique antenna group Rx#5~#8 are arranged symmetrically in the horizontal direction. Even in the case of Configuration Example 2-4b, the same effect as in Configuration Example 2 can be obtained.

[0468] Figure 95 shows an example (referred to as "Configuration Example 2-4c") in which the first oblique antenna group Tx#1~#3 and the second oblique antenna group Tx#4~#6 are arranged with an asymmetrical tilt in the horizontal direction, and the third oblique antenna group Rx#1~#4 and the fourth oblique antenna group Rx#5~#8 are also arranged with an asymmetrical tilt in the horizontal direction. Even in the case of Configuration Example 2-4c, the same effect as in Configuration Example 2 can be obtained.

[0469] Furthermore, in arrangement condition 2, either the first diagonal direction or the second diagonal direction may be arranged horizontally. Also, in arrangement condition 2, either the third diagonal direction or the fourth diagonal direction may be arranged horizontally.

[0470] For example, Figure 96 shows an example where the first oblique antenna group Tx#1~#3 is arranged obliquely and the second oblique antenna group Tx#4~#6 is arranged horizontally (for example, referred to as "arrangement example 2-4d"). In Figure 96, for example, the arrangement of the third oblique antenna group Rx#1~#4 and the fourth oblique antenna group Rx#5~#8 is a horizontally inverted symmetrical arrangement. In this way, even if either the first oblique direction or the second oblique direction is arranged horizontally, the same effect as in arrangement example 2 can be obtained.

[0471] [Modification 6 of arrangement example 2] In at least one of the transmitting antenna 106 (for example, the first and second oblique antenna groups) and the receiving antenna 202 (for example, the third and fourth oblique antenna groups), the spacing between adjacent antennas is not limited to equal spacing, but may be unequal.

[0472] For example, at least one of the first, second, third, and fourth oblique antenna groups may be set to an unequal spacing antenna arrangement. This also yields the same effect as in arrangement example 2.

[0473] [Variation 7 of arrangement example 2] In Modification 7 of Arrangement Example 2, for example, a multi-stage antenna arrangement described in Arrangement Example 2 and Modifications 1 to 4 and 6 of Arrangement Example 2 may be applied.

[0474] Examples of multi-stage configurations include a configuration in which the first and second oblique antenna groups included in the transmitting antenna 106 are arranged in two vertical stages or two horizontal stages, and a configuration in which the third and fourth oblique antenna groups included in the receiving antenna 202 are arranged in two vertical stages or two horizontal stages. Alternatively, the multi-stage configuration may be a combination of these configurations.

[0475] Even in the case of a multi-stage configuration, the effects related to the above-described arrangement example 2 can be maintained. Furthermore, for example, a horizontal multi-stage configuration can widen the aperture length of the horizontal virtual receiving array, thereby improving the horizontal angle measurement accuracy or resolution of the radar device 10. Furthermore, for example, a vertical multi-stage configuration can widen the aperture length of the vertical virtual receiving array, thereby improving the vertical angle measurement accuracy or resolution of the radar device 10. Furthermore, for example, a vertical and horizontal multi-stage configuration can widen the aperture lengths of the vertical and horizontal virtual receiving arrays, thereby improving the vertical and horizontal angle measurement accuracy or resolution of the radar device 10.

[0476] In the case of a multi-stage configuration, the common arrangement of the transmitting antenna Tx or the receiving antenna Rx may be configured in multiple stages in at least one of the vertical and horizontal directions, or different arrangements of the transmitting antenna Tx or the receiving antenna Rx may be configured in multiple stages in at least one of the vertical and horizontal directions.

[0477] Furthermore, different antenna elements may be used in combination in the multi-stage configuration described above. For example, the multiple transmitting antennas 106 may include long-range (LR) antenna elements and short-range (SR) antenna elements.

[0478] For example, in a multi-stage configuration, long-range (LR) antenna elements may be used in the first stage, and short-range (SR) antenna elements may be used in combination with them in the second stage. For example, if the transmitting antenna 106 is arranged in a two-stage vertical configuration, long-range (LR) antenna elements may be used in the first stage, and short-range (SR) antenna elements may be used in the second stage.

[0479] Furthermore, if the vertical and horizontal dimensions of the long-range (LR) antenna elements are large, the elements of one stage may be shifted horizontally so that the first stage transmitting antenna 106 and the second stage transmitting antenna 106 do not overlap.

[0480] Thus, when using both an LR antenna and an SR antenna for the transmitting antenna 106, for example, an SR antenna (for example, an antenna with a wide field of view) may be applied to the receiving antenna 202. This allows for the detection range of both LR and SR modes while maintaining the effectiveness of the arrangement example 2.

[0481] The above describes a modified version of arrangement example 2.

[0482] Next, we will describe a modified example specific to arrangement condition 2.

[0483] [Variation of arrangement condition 2] In arrangement example 2 and the modified version of arrangement example 2, for example, the diagonal inclination of the transmitting antenna 106 and the receiving antenna 202 is set to the basic interval D in the horizontal direction. H Set to an integer multiple of and the basic interval D in the vertical direction V The case where the value is set to an integer multiple was explained.

[0484] That is, N Tx In the transmitting antenna 106, the first oblique antenna group and the second oblique antenna group are arranged in different oblique directions. Furthermore, the first oblique antenna group is arranged horizontally in a dTH1 × D H It shifts at intervals of dTV1×D, and simultaneously in the vertical direction as well. VThey are arranged diagonally, shifted at intervals of . In addition, the second group of diagonal antennas is dTH2×D in the horizontal direction. H It shifts at intervals of , and simultaneously in the vertical direction as well. V They are positioned diagonally, shifting at intervals of [number].

[0485] Furthermore, in the Na receiving antennas 202, the third oblique antenna group and the fourth oblique antenna group are arranged in different oblique directions. Also, the third oblique antenna group is arranged horizontally in dRH1 × D H Shifts at intervals of dRV1×D, and simultaneously shifts vertically as well. V They are arranged diagonally, shifted at intervals of . In addition, the fourth diagonal antenna group is dRH2×D in the horizontal direction. H Shifts at intervals of dRV2×D, and simultaneously shifts vertically as well. V They are positioned diagonally, shifting at intervals of [number].

[0486] Here, dTH1 and dTV1 are integers greater than or equal to 1, and dTH2 and dTV2 are integers greater than or equal to 1. Also, dRH1 and dRV1 are integers greater than or equal to 1, and dRH2 and dRV2 are integers greater than or equal to 1.

[0487] For example, if dTH1 = dTH2 and dTV1 = dTV2, the first and second oblique antenna groups will be horizontally symmetrically arranged. Also, for example, if dTH1 ≠ dTH2 or dTV1 ≠ dTV2, the first and second oblique antenna groups will be horizontally asymmetrically arranged.

[0488] Similarly, for example, if dRH1=dRH2 and dRV1=dRV2, the third and fourth oblique antenna groups will be horizontally symmetrically arranged. Also, for example, if dRH1≠dRH2 or dRV1≠dRV2, the third and fourth oblique antenna groups will be horizontally asymmetrically arranged.

[0489] In addition, in arrangement example 2 and the modified version of arrangement example 2, the diagonal inclination of the transmitting antenna 106 and the receiving antenna 202 is the basic interval D in the horizontal direction. HIt is set to an integer multiple of and the basic interval D in the vertical direction. V Not limited to cases where it is set to an integer multiple of D V , D H The interval may be set to one that is not an integer multiple of the given interval. Even with this arrangement, arrangement condition 2 is satisfied, and the same effect as arrangement example 2 can be obtained.

[0490] [Example of the minimum antenna configuration and arrangement when the number of antennas is small under arrangement condition 2] The following describes the minimum antenna configuration that satisfies arrangement condition example 2, and arrangement examples when the number of antennas satisfying arrangement condition 2 is small. Note that similar effects can be obtained by modifying the antenna arrangement described below in accordance with the modified example of arrangement example 2 described above.

[0491] The minimum number of antennas for arrangement condition 2 is, for example, the number of transmitting antennas N. Tx This is the case when =3 and the number of receiving antennas Na=3. In other words, the total number of antennas in the first and second oblique antenna groups is 3, and the total number of antennas in the third and fourth oblique antenna groups is 3.

[0492] Figure 97 shows the minimum number of antennas (number of transmitting antennas N) for arrangement condition 2. Tx Figure 97(a) shows an example of an antenna configuration with 3 receiving antennas (Na=3). Figure 97(b) shows an example of a MIMO antenna configuration, and Figure 97(a) shows an example of a virtual receiving array configuration composed of the MIMO antenna configuration shown in Figure 97(a). Also, in Figure 97, the scales on the horizontal and vertical axes are, for example, D H , D V Let's assume that.

[0493] In Figure 97, the first oblique antenna group includes Tx#1 and Tx#2, and the second oblique antenna group includes Tx#2 and Tx#3. Also in Figure 97, the third oblique antenna group includes Rx#1 and Rx#2, and the fourth oblique antenna group includes Rx#2 and Rx#3.

[0494] Furthermore, Figures 98 to 101 show examples of antenna configurations when the number of antennas satisfying configuration condition 2 is small. Figures 98 to 101(a) show an example of a MIMO antenna configuration, and Figures 98 to 101(b) show an example of a virtual receiving array configuration composed of the MIMO antenna configuration shown in Figures 98 to 101(a). Also, in Figures 98 to 101, the scales on the horizontal and vertical axes are, for example, D H , D V Let's assume that.

[0495] For example, Figures 98 and 99 show the number of transmitting antennas N. Tx An example of antenna arrangement for the case where =3 and the number of receiving antennas Na=4 is shown. In Figures 98 and 99, the first oblique antenna group includes Tx#1 and Tx#2, the second oblique antenna group includes Tx#2 and Tx#3, the third oblique antenna group includes Rx#1 and Rx#2, and the fourth oblique antenna group includes Rx#3 and Rx#4.

[0496] For example, in the antenna arrangement example shown in Figure 98, even if the vertical size of the transmitting antenna 106 is large, the receiving antennas 202 are placed on both sides of the transmitting antenna 106, thus reducing the antenna mounting area.

[0497] Furthermore, in the antenna arrangement example shown in Figure 99, for example, even if the vertical size of the transmitting antenna 106 is large, the transmitting antenna 106 is positioned on both sides of the receiving antenna 202, thus reducing the antenna mounting area.

[0498] Furthermore, for example, Figures 100 and 101 show the number of transmitting antennas N. Tx An example of antenna arrangement when =4 and the number of receiving antennas Na=4 is shown. In Figures 100 and 101, the first oblique antenna group includes Tx#1 and Tx#2, the second oblique antenna group includes Tx#3 and Tx#4, the third oblique antenna group includes Rx#1 and Rx#2, and the fourth oblique antenna group includes Rx#3 and Rx#4.

[0499] For example, in the antenna arrangement examples shown in Figures 100 and 101, even if the vertical size of the transmitting antenna 106 is large, the receiving antennas 202 are placed on both sides of the transmitting antenna 106, thus reducing the antenna mounting area.

[0500] An embodiment of the present disclosure has been described above.

[0501] In one embodiment of this disclosure, the case in arrangement condition 1 (for example, Figure 8) where the receiving antenna 202 is positioned in two different directions (e.g., diagonal directions) was described, but the receiving antenna 202 may be positioned in three or more different directions. Similarly, in arrangement condition 2 (for example, Figure 80), the case in which the respective positions of the transmitting antenna 106 and the receiving antenna 202 (e.g., diagonal directions) are two different directions was described, but the respective positions of the transmitting antenna 106 and the receiving antenna 202 may be positioned in three or more different directions. Even in these cases, as described above, the direction of grating lobe generation corresponding to each arrangement direction becomes more easily dispersed, so grating lobe can be suppressed in the same way as described above.

[0502] Furthermore, the configuration of the radar device according to one embodiment of this disclosure is not limited to the configuration shown in Figure 6. For example, the radar device does not need to include the CFAR unit 211.

[0503] Furthermore, the number of transmitting antennas N in the antenna arrangement described in one embodiment of this disclosure Tx Parameters such as the number of receiving antennas Na, or the antenna spacing are just examples, and other different values ​​may be used.

[0504] Furthermore, at least two variations of arrangement example 1 described in one embodiment of this disclosure may be combined and implemented. Similarly, at least two variations of arrangement example 2 may be combined and implemented. For example, the settings such as the number of antennas, inclination, element spacing, or spacing between the diagonal antenna groups for the first and second diagonal antenna groups in arrangement example 1, and the first to fourth diagonal antenna groups in arrangement example 2, may be determined by combining at least two variations of arrangement example 1 or arrangement example 2.

[0505] In a radar device according to one embodiment of the present disclosure, the radar transmitter and the radar receiver may be individually arranged in physically separate locations. Furthermore, in a radar receiver according to one embodiment of the present disclosure, the direction estimation unit and the other components may be individually arranged in physically separate locations.

[0506] A radar system according to one embodiment of the present disclosure, although not shown, includes, for example, a CPU (Central Processing Unit), a storage medium such as ROM (Read Only Memory) storing a control program, and working memory such as RAM (Random Access Memory). In this case, the functions of each of the above-mentioned parts are realized by the CPU executing the control program. However, the hardware configuration of the radar system is not limited to this example. For example, each functional part of the radar system may be realized as an integrated circuit (IC). Each functional part may be individually integrated into a single chip, or a part or all of them may be integrated into a single chip.

[0507] Although various embodiments have been described above with reference to the drawings, it goes without saying that this disclosure is not limited to such examples. It is clear to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these will naturally also fall within the technical scope of this disclosure. Furthermore, the components of the above embodiments may be combined in any way without departing from the spirit of the disclosure.

[0508] Furthermore, the notation "...part" in the above-described embodiment may be replaced with other notations such as "...circuitry," "...assembly," "...device," "...unit," or "...module."

[0509] In the embodiments described above, the disclosure has been explained using examples configured with hardware, but the disclosure can also be implemented with software in conjunction with hardware.

[0510] Furthermore, each functional block used in the description of the above embodiments is typically implemented as an integrated circuit (LSI). The integrated circuit controls each functional block used in the description of the above embodiments and may have input and output terminals. These may be individually integrated into a single chip, or some or all of them may be integrated into a single chip. Here, we refer to it as an LSI, but depending on the degree of integration, it may also be called an IC, system LSI, super LSI, or ultra LSI.

[0511] Furthermore, the method of integrated circuit implementation is not limited to LSIs; it may also be implemented using dedicated circuits or general-purpose processors. After LSI manufacturing, FPGAs (Field Programmable Gate Arrays) that can be programmed, or reconfigurable processors that allow for the reconfiguration of the connections or settings of circuit cells inside the LSI, may also be used.

[0512] Furthermore, if advances in semiconductor technology or other derived technologies lead to the emergence of integrated circuit technologies that can replace LSIs, then naturally, functional blocks can be integrated using those technologies. The application of biotechnology, for example, is a possibility.

[0513] <Summary of this disclosure> A radar device according to one embodiment of the present disclosure comprises a transmitting circuit that transmits a transmission signal using a plurality of transmitting antennas, and a receiving circuit that receives a reflected wave signal obtained by reflecting the transmission signal off an object using a plurality of receiving antennas, wherein either the plurality of transmitting antennas or the plurality of receiving antennas includes a first antenna group arranged in a first direction and a second antenna group arranged in a second direction different from the first direction, and the remaining of the plurality of transmitting antennas or the plurality of receiving antennas includes a third antenna group arranged in a third direction different from the first and second directions, wherein the distance between adjacent antennas is an interval of one wavelength or more of the transmission signal.

[0514] In one embodiment of the present disclosure, the radar device is installed on a vehicle, and the first and second directions are different from the vertical direction, which is the height direction of the vehicle, and the horizontal direction, which is the straight-line direction of the vehicle and the direction perpendicular to the straight-line direction of the vehicle.

[0515] In one embodiment of the present disclosure, the first direction and the second direction are different from the vertical direction, which is the direction of gravity, and the horizontal direction, which is perpendicular to the direction of gravity.

[0516] In one embodiment of the present disclosure, the third direction is a direction that coincides with the horizontal direction.

[0517] In one embodiment of the present disclosure, the minimum distance between the first antenna group and the second antenna group is wider than the aperture length of the third antenna group.

[0518] In one embodiment of the present disclosure, the first antenna group and the second antenna group include one or more antennas that are shared.

[0519] In one embodiment of the present disclosure, the antenna arrangement included in the first antenna group and the antenna arrangement included in the second antenna group are symmetrical with respect to a line perpendicular to the third direction.

[0520] In one embodiment of the present disclosure, the distance between adjacent antennas of the third antenna group in the horizontal direction is dT × D H Therefore, the distance between adjacent antennas in the first antenna group in the horizontal direction is dRH1 × D H Therefore, the distance between adjacent antennas included in the first antenna group in the vertical direction is dRV × D V Therefore, the distance between adjacent antennas in the second antenna group in the horizontal direction is dRH2 × D H Therefore, the distance between adjacent antennas included in the second antenna group in the vertical direction is dRV × D V And the above D H and the aforementioned D V The value of is within the range of 0.45 to 0.8 times the wavelength of the transmitted signal, the value of dT is 2 or greater, and each of the values ​​of dRH1 and dRH2 is 1 or greater.

[0521] In one embodiment of the present disclosure, the distance between adjacent antennas is equal in each of the third antenna group, the first antenna group, and the second antenna group.

[0522] In one embodiment of the present disclosure, in at least one of the third antenna group, the first antenna group, and the second antenna group, the spacing between adjacent antennas includes one or more unequal spacings.

[0523] In one embodiment of the present disclosure, the third antenna group has a plurality of sets of at least some antennas arranged in the third direction.

[0524] In one embodiment of the present disclosure, either the plurality of transmitting antennas or the plurality of receiving antennas comprises a plurality of the first antenna group and the second antenna group.

[0525] In one embodiment of the present disclosure, the plurality of transmitting antennas include at least two types of antenna elements of different sizes.

[0526] In one embodiment of the present disclosure, the remaining of the plurality of transmitting antennas or the plurality of receiving antennas includes a fourth group of antennas arranged in a fourth direction different from the third direction.

[0527] In one embodiment of the present disclosure, the remaining of the plurality of transmitting antennas or the plurality of receiving antennas includes a fourth group of antennas arranged in a fourth direction different from the third direction, The third and fourth directions are different from the horizontal and vertical directions.

[0528] In one embodiment of the present disclosure, the first direction, the second direction, the third direction, and the fourth direction are different from each other.

[0529] In one embodiment of the present disclosure, the third antenna group and the fourth antenna group include one or more antennas that are shared.

[0530] In one embodiment of the present disclosure, the spacing between adjacent antennas of the third antenna group in the horizontal direction is dTH1 × D H Therefore, the distance between adjacent antennas included in the third antenna group in the vertical direction is dTV1 × D V Therefore, the spacing between adjacent antennas in the fourth antenna group in the horizontal direction is dTH2 × D H Therefore, the spacing between adjacent antennas included in the fourth antenna group in the vertical direction is dTV2 × D V Therefore, the distance between adjacent antennas in the first antenna group in the horizontal direction is dRH1 × D H Therefore, the distance between adjacent antennas included in the first antenna group in the vertical direction is dRV1 × D V Therefore, the distance between adjacent antennas in the second antenna group in the horizontal direction is dRH2 × D H Therefore, the spacing between adjacent antennas included in the second antenna group in the vertical direction is dRV2 × D V And the above D H and the aforementioned D VThe value is within the range of 0.45 to 0.8 times the wavelength of the transmitted signal, and each of the values ​​of dTH1, dTV1, dTH2, dTV2, dRH1, dRV1, dRH2, and dRV2 is 1 or greater.

[0531] A radar device according to one embodiment of the present disclosure comprises a transmitting circuit that transmits a transmission signal using a plurality of transmitting antennas, and a receiving circuit that receives a reflected wave signal obtained by reflecting the transmission signal off an object using a plurality of receiving antennas, wherein either the plurality of transmitting antennas or the plurality of receiving antennas includes a first antenna group arranged in a first direction and a second antenna group arranged in a second direction different from the first direction, and the remaining one of the plurality of transmitting antennas or the plurality of receiving antennas includes a third antenna group arranged in a third direction, wherein the distance between adjacent antennas is one wavelength or more of the transmission signal, and a fourth antenna group arranged in a fourth direction different from the third direction, wherein the distance between adjacent antennas is one wavelength or more of the transmission signal, and the third direction is the same direction as the first direction, and the fourth direction is the same direction as the second direction. [Industrial applicability]

[0532] This disclosure is suitable as a radar device for detecting a wide-angle range. [Explanation of Symbols]

[0533] 10 Radar equipment 100 Radar Transmitter 101 Radar transmission signal generation unit 102 Modulated signal generation unit 103 VCO 104 Code generator 105 Phase rotation section 106 Transmitting Antenna 200 Radar Receiver 201 Antenna System Processing Unit 202 Receiving Antenna 203 Receiving Radio Unit 204 Mixer Section 205 LPF 206 Signal Processing Unit 207 AD Conversion Unit 208 Beat Frequency Analysis Unit 209 Output switching section 210 Doppler Analysis Unit 211 CFAR Department 212 Code demultiplexer 213 Direction estimation part

Claims

1. A transmitting circuit that transmits a transmission signal using multiple transmitting antennas, A receiving circuit that uses multiple receiving antennas to receive reflected wave signals that are reflected off an object from the transmitted signal, It is equipped with, Either the plurality of transmitting antennas or the plurality of receiving antennas is A first group of antennas arranged in the first direction, The system includes a second group of antennas arranged in a second direction different from the first direction, The remaining of the aforementioned plurality of transmitting antennas or the plurality of receiving antennas, The distance between adjacent antennas is an interval of one wavelength or more of the transmitted signal, and a third group of antennas is arranged in the third direction, A fourth group of antennas is arranged in a fourth direction different from the third direction, and the distance between adjacent antennas is an interval of one wavelength or more of the transmitted signal. Includes, The third direction is the same as the first direction. The aforementioned fourth direction is different from the aforementioned second direction, The third antenna group and the fourth antenna group include one or more antennas that are shared. Radar device.

2. The radar device is installed on the vehicle, The first and second directions are different from the vertical direction, which is the height direction of the vehicle, and the horizontal direction, which is the straight-ahead direction of the vehicle and the direction perpendicular to the straight-ahead direction of the vehicle. The radar device according to claim 1.

3. The first and second directions are different from the vertical direction, which is the direction of gravity, and the horizontal direction, which is perpendicular to the direction of gravity. The radar device according to claim 1.

4. Either the third direction or the fourth direction is a direction that coincides with the horizontal direction. The radar device according to claim 2 or 3.

5. The third and fourth directions are different from the horizontal and vertical directions. The radar device according to claim 2 or 3.

6. The minimum distance between the first antenna group and the second antenna group is wider than the aperture length of the third antenna group or the fourth antenna group. The radar device according to claim 1.

7. The first antenna group and the second antenna group include one or more antennas that are shared. The radar device according to claim 1.

8. The antenna arrangement included in the first antenna group and the antenna arrangement included in the second antenna group are symmetrical with respect to the vertical direction. The radar device according to claim 2 or 3.

9. The spacing between adjacent antennas in the first antenna group in the horizontal direction is a first integer multiple of DH. The spacing between adjacent antennas in the second antenna group in the horizontal direction is a second integer multiple of DH. The spacing between adjacent antennas in the third antenna group in the horizontal direction is a third integer multiple of DH. The spacing between adjacent antennas in the fourth antenna group in the horizontal direction is a fourth integer multiple of DH. The spacing between adjacent antennas in the first antenna group in the vertical direction is a fifth integer multiple of DV. The spacing between adjacent antennas in the second antenna group in the vertical direction is a sixth integer multiple of DV. The spacing between adjacent antennas in the third antenna group in the vertical direction is a seventh integer multiple of DV. The spacing between adjacent antennas in the fourth antenna group in the vertical direction is an integer multiple of the eighth of DV. The values ​​DH and DV are within the range of 0.45 to 0.8 times the wavelength of the transmitted signal. The radar device according to claim 2 or 3.

10. A transmitting circuit that transmits a transmission signal using a plurality of transmitting antennas, A receiving circuit that uses multiple receiving antennas to receive reflected wave signals that are reflected off an object from the transmitted signal, It is equipped with, Either the plurality of transmitting antennas or the plurality of receiving antennas is A first group of antennas arranged in the first direction, The system includes a second group of antennas arranged in a second direction different from the first direction, The remaining of the aforementioned plurality of transmitting antennas or the plurality of receiving antennas, The distance between adjacent antennas is an interval of one wavelength or more of the transmitted signal, and a third group of antennas is arranged in the third direction, A fourth group of antennas is arranged in a fourth direction different from the third direction, and the distance between adjacent antennas is an interval of one wavelength or more of the transmitted signal. Includes, The third direction is the same as the first direction. The aforementioned fourth direction is different from the aforementioned second direction, In each of the first, second, third, and fourth antenna groups, the distance between adjacent antennas is equal. Radar device.

11. In at least one of the first antenna group, the second antenna group, the third antenna group, and the fourth antenna group, the spacing between adjacent antennas includes one or more unequal spacings. The radar device according to claim 1.

12. Either the plurality of transmitting antennas or the plurality of receiving antennas comprises a plurality of the first antenna group and the second antenna group. The radar device according to claim 1.

13. The aforementioned plurality of transmitting antennas include at least two types of antenna elements of different sizes. The radar device according to claim 1.

Images