radar equipment

Abstract

To improve the detection performance of a radar device.SOLUTION: A radar device includes: a radar transmitting circuit that transmits a radar signal using a transmitting array antenna; and a radar receiving circuit that receives a reflected wave signal which is the radar signal reflected from a target, using a receiving array antenna. One of the transmitting array antenna and the receiving array antenna is composed of a plurality of first antennas, and the plurality of first antennas are arranged based on a first interval in a first direction and a second interval in a second direction perpendicular to the first direction. The other of the transmitting array antenna and the receiving array antenna is composed of at least two or more second antenna groups, and a plurality of second antennas constituting each of the second antenna groups are arranged based on the first interval.SELECTED DRAWING: Figure 4

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 (hereinafter referred to as "wide-angle radar systems") that can detect objects (targets), including pedestrians, in addition to vehicles, over a wider angle range.

[0003] For example, pulse radar devices that repeatedly emit pulse waves are known as radar devices. The received signal of a wide-angle pulse radar device that detects vehicles / pedestrians over a wider angle range tends to be a signal that is a mixture of multiple reflected waves from targets at close range (e.g., vehicles) and targets at long range (e.g., pedestrians). For this reason, (1) the radar transmitter is required to transmit pulse waves or pulse-modulated waves having autocorrelation characteristics that result in low range sidelobes (hereinafter referred to as low range sidelobe characteristics), and (2) the radar receiver is required to have a wide reception dynamic range.

[0004] The following two configurations are possible for wide-angle radar systems.

[0005] The first configuration involves transmitting a radar wave by mechanically or electronically scanning a pulsed or modulated wave using a narrow-angle directional beam (for example, a beam width of a few degrees) compared to the detection angle assumed by the radar device, and receiving the reflected wave using the same narrow-angle directional beam. In this configuration, many scans are required to obtain high resolution, which degrades the tracking ability for fast-moving targets.

[0006] The second configuration uses an array antenna composed of multiple antennas (antenna elements) to receive reflected waves, and estimates the angle of arrival of the reflected wave using a signal processing algorithm based on the received phase difference with respect to the element spacing (antenna spacing) (Direction of Arrival (DOA) estimation). In this configuration, even if the scanning angle interval of the transmitted beam is reduced, the angle of arrival can be estimated at the received branch, thus shortening the scanning time and improving tracking performance compared to the first configuration. For example, methods for estimating the direction of arrival include Fourier transforms based on matrix operations, Capon and LP (Linear Prediction) methods based on inverse matrix operations, or MUSIC (Multiple Signal Classification) and ESPRIT (Estimation of Signal Parameters via Rotational Invariance Techniques) based on eigenvalue operations.

[0007] Furthermore, a radar system has been proposed that includes multiple antennas (array antennas) in both the receiving and transmitting branches, 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).

[0008] 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 the virtual receiving array) that is equal to the product of the number of transmitting antenna elements and the number of receiving antenna elements. This has the effect of increasing the effective aperture length of the array antenna with a small number of elements, thereby improving the angular resolution.

[0009] Furthermore, MIMO radar can be applied not only to one-dimensional scanning (angle measurement) in the vertical or horizontal direction, but also to two-dimensional beam scanning in the vertical and horizontal directions (see, for example, Non-Patent Document 2). [Prior art documents] [Non-patent literature]

[0010] [Non-Patent Document 1] J. Li, P. Stoica, "MIMO Radar with Colocated Antennas," Signal Processing Magazine, IEEE Vol. 24, Issue: 5, pp. 106-114, 2007 [Non-Patent Document 2] PP Vaidyanathan, P. Pal,Chun-Yang Chen, "MIMO radar with broadband waveforms: Smearing filter banks and 2D virtual arrays," IEEE Asilomar Conference on Signals, Systems and Computers, pp.188 - 192, 2008. [Non-Patent Document 3] J. Wenger, "Automotive mm-wave radar: status and trends in system design and technology," IEE Colloquium on Automotive Radar and Navigation Techniques (Ref. No. 1998 / 230), pp. 144-147, 1998. [Non-Patent Document 4] M. Harte, T. Mahler, T. Schipper, A. Ziroff, and T. Zwick, “2-D antenna array geometries for MIMO radar imaging by digital beamforming,” 2013 European Microwave Conference, pp. 1695 - 1698, 2013. [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] However, depending on the antenna configuration of the transmit and receive branches in a MIMO radar, the detection performance of the radar equipment may be degraded.

[0012] Non-limiting embodiments of this disclosure contribute to the provision of radar devices capable of improving detection performance. [Means for solving the problem]

[0013] A radar device according to one embodiment of the present disclosure comprises a radar transmitting unit that transmits a radar signal using a transmitting array antenna, and a radar receiving unit that receives a reflected wave signal of the radar signal reflected at a target using a receiving array antenna, wherein the transmitting array antenna is composed of a plurality of transmitting antenna groups, each of the plurality of transmitting antenna groups includes a plurality of transmitting antennas arranged at a second interval which is an integer multiple of a first interval in a first direction, and at a fourth interval which is an integer multiple of a third interval in a second direction orthogonal to the first direction, and the receiving array antenna is composed of a plurality of receiving antenna groups, each of the plurality of receiving antenna groups includes a plurality of receiving antennas arranged at a fifth interval which is an integer multiple of a first interval in the first direction, and at a sixth interval which is an integer multiple of a third interval in a second direction, the difference between the second interval and the fifth interval is the first interval, and the difference between the fourth interval and the sixth interval is the third interval.

[0014] 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]

[0015] According to one embodiment of the present disclosure, the detection performance of a radar device can be improved.

[0016] 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]

[0017] [Figure 1A] Diagram showing an example of the arrangement of transmitting and receiving antennas. [Figure 1B] Diagram showing an example of a virtual receiver array configuration. [Figure 2A] Diagram showing the directional pattern of a virtual receiving array (dV=0.5λ) [Figure 2B] Diagram showing the directional pattern of a virtual receiving array (dV=0.5λ) [Figure 3A] Diagram showing the directional pattern of a virtual receiving array (dV=λ) [Figure 3B] Diagram showing the directional pattern of a virtual receiving array (dV=2λ) [Figure 4] Block diagram showing the configuration of the radar system. [Figure 5] A diagram showing an example of a radar transmission signal. [Figure 6] Block diagram showing other configurations of the radar transmission signal generation unit. [Figure 7] This diagram shows an example of the transmission timing and measurement range of radar transmission signals. [Figure 8] Diagram showing an example of antenna placement for Basic Arrangement 1. [Figure 9A] A diagram showing an example of a subarray configuration. [Figure 9B] A diagram showing an example of a subarray configuration. [Figure 9C] A diagram showing an example of a subarray configuration. [Figure 10] This diagram shows an example configuration of a transmitting array antenna using sub-arrays. [Figure 11A] This figure shows an example of direction estimation results using the transmit / receive antenna configuration related to basic configuration 1. [Figure 11B]Figure 1A shows an example of direction estimation results using the transmit / receive antenna configuration. [Figure 12] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 1. [Figure 13] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 1. [Figure 14] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 1. [Figure 15] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 1. [Figure 16] This figure shows an example of antenna placement related to Modification 2 of Basic Placement 1. [Figure 17] This figure shows an example of antenna placement related to Modification 2 of Basic Placement 1. [Figure 18] This figure shows an example of antenna placement related to Modification 2 of Basic Placement 1. [Figure 19] This figure shows an example of antenna placement related to Modification 2 of Basic Placement 1. [Figure 20] This figure shows an example of antenna placement related to Modification 2 of Basic Placement 1. [Figure 21] This figure shows an example of antenna placement related to Modification 3 of Basic Placement 1. [Figure 22] This figure shows an example of antenna placement related to Modification 3 of Basic Placement 1. [Figure 23] This figure shows an example of antenna placement related to Modification 3 of Basic Placement 1. [Figure 24] This figure shows an example of antenna placement related to Modification 3 of Basic Placement 1. [Figure 25A] This figure shows an example of the subarray configuration related to Modification 3 of Basic Arrangement 1. [Figure 25B] This figure shows an example of a transmitting array antenna configuration using a sub-array related to Modification 3 of Basic Configuration 1. [Figure 25C] This figure shows an example of a transmitting array antenna configuration using a sub-array related to Modification 3 of Basic Configuration 1. [Figure 26] This figure shows an example of an antenna arrangement combining Modification 3 of Basic Arrangement 1 and Modification 1. [Figure 27] This figure shows an example of an antenna arrangement combining Modification 3 of Basic Arrangement 1 and Modification 1. [Figure 28] This figure shows an example of an antenna arrangement combining Modification 3 of Basic Arrangement 1 and Modification 1. [Figure 29] This figure shows an example of an antenna arrangement combining Modification 3 of Basic Arrangement 1 and Modification 1. [Figure 30] This figure shows an example of an antenna arrangement combining Modification 3 of Basic Arrangement 1 and Modification 1. [Figure 31] This figure shows an example of an antenna configuration that combines Modification 3 and Modification 2 of Basic Configuration 1. [Figure 32] This figure shows an example of an antenna configuration that combines Modification 3 and Modification 2 of Basic Configuration 1. [Figure 33] This figure shows an example of an antenna configuration that combines Modification 3 and Modification 2 of Basic Configuration 1. [Figure 34] Diagram showing an example of antenna placement related to Basic Arrangement 2. [Figure 35] Diagram showing an example of the sub-array configuration related to basic arrangement 2. [Figure 36] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 2. [Figure 37] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 2. [Figure 38] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 2. [Figure 39] This figure shows an example of antenna placement related to Modification 2 of Basic Placement 2. [Figure 40] This figure shows an example of antenna placement related to Modification 2 of Basic Placement 2. [Figure 41] This figure shows an example of antenna placement related to Modification 2 of Basic Placement 2. [Figure 42] This figure shows an example of antenna placement related to Modification 2 of Basic Placement 2. [Figure 43] This figure shows an example of antenna placement related to Modification 2 of Basic Placement 2. [Figure 44] This figure shows an example of antenna placement related to Modification 3 of Basic Placement 2. [Figure 45] This figure shows an example of antenna placement related to Modification 3 of Basic Placement 2. [Figure 46] This figure shows an example of antenna placement related to Modification 3 of Basic Placement 2. [Figure 47] This figure shows an example of antenna placement related to Modification 3 of Basic Placement 2. [Figure 48] This figure shows an example of an antenna arrangement combining Modification 3 of Basic Arrangement 2 and Modification 2. [Figure 49] This figure shows an example of an antenna arrangement combining Modification 3 of Basic Arrangement 2 and Modification 2. [Figure 50A] This figure shows an example of an antenna arrangement combining Modification 3 of Basic Arrangement 2 and Modification 2. [Figure 50B] This figure shows an example of an antenna arrangement combining Modification 3 of Basic Arrangement 2 and Modification 2. [Figure 51A] This figure shows an example of an antenna arrangement combining Modification 3 of Basic Arrangement 2 and Modification 2. [Figure 51B] This figure shows an example of an antenna arrangement combining Modification 3 of Basic Arrangement 2 and Modification 2. [Figure 52A] Diagram showing an example of antenna placement related to basic configuration 3. [Figure 52B] Diagram showing an example of antenna placement related to basic configuration 3. [Figure 52C] Diagram showing an example of antenna placement related to basic configuration 3. [Figure 52D] Diagram showing an example of antenna placement related to basic configuration 3. [Figure 53A] Diagram showing an example of antenna placement related to basic configuration 3. [Figure 53B] Diagram showing an example of antenna placement related to basic configuration 3. [Figure 53C] Diagram showing an example of antenna placement related to basic configuration 3. [Figure 53D] Diagram showing an example of antenna placement related to basic configuration 3. [Figure 54A] Diagram showing an example of antenna placement related to basic configuration 3. [Figure 54B] Diagram showing an example of antenna placement related to basic configuration 3. [Figure 54C] Diagram showing an example of antenna placement related to basic configuration 3. [Figure 54D] Diagram showing an example of antenna placement related to basic configuration 3. [Figure 55A] Diagram showing an example of antenna placement related to basic configuration 3. [Figure 55B] Diagram showing an example of antenna placement related to basic configuration 3. [Figure 55C] Diagram showing an example of antenna placement related to basic configuration 3. [Figure 55D] Diagram showing an example of antenna placement related to basic configuration 3. [Figure 56A] This figure shows an example of a transmitting array antenna configuration using a sub-array related to basic configuration 3. [Figure 56B] This figure shows an example of a transmitting array antenna configuration using a sub-array related to basic configuration 3. [Figure 57] This figure shows an example of direction estimation results using the transmit / receive antenna arrangement related to basic configuration 3. [Figure 58] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 3. [Figure 59] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 3. [Figure 60] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 3. [Figure 61] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 3. [Figure 62] This figure shows an example of direction estimation results using the transmit / receive antenna arrangement related to Modification 1 of Basic Arrangement 3. [Figure 63] This figure shows an example of antenna placement related to Modification 2 of Basic Placement 3. [Figure 64] This figure shows an example of antenna placement related to Modification 2 of Basic Placement 3. [Figure 65] This figure shows an example of antenna placement related to Modification 2 of Basic Placement 3. [Figure 66] This figure shows an example of antenna placement related to Modification 2 of Basic Placement 3. [Figure 67] This figure shows an example of antenna placement related to Modification 2 of Basic Placement 3. [Figure 68A] This figure shows an example of antenna placement related to Modification 2 of Basic Placement 3. [Figure 68B] This figure shows an example of antenna placement related to Modification 2 of Basic Placement 3. [Figure 69] Diagram showing an example of antenna placement related to basic configuration 4. [Figure 70A]This figure shows an example of a transmitting array antenna configuration using a sub-array related to basic configuration 4. [Figure 70B] This figure shows an example of a transmitting array antenna configuration using a sub-array related to basic configuration 4. [Figure 71] This figure shows an example of direction estimation results using the transmit / receive antenna arrangement related to basic configuration 4. [Figure 72] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 4. [Figure 73] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 4. [Figure 74] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 4. [Figure 75] This figure shows an example of direction estimation results using the transmit / receive antenna arrangement related to Modification 1 of Basic Arrangement 4. [Figure 76] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 4. [Figure 77] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 4. [Figure 78] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 4. [Figure 79] An example of direction estimation results using the transmit / receive antenna arrangement related to Modification 1 of Basic Arrangement 4. [Figure 80] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 4. [Figure 81] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 4. [Figure 82] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 4. [Figure 83] This figure shows an example of antenna placement related to Modification 2 of Basic Placement 4. [Figure 84] This figure shows an example of antenna placement related to Modification 2 of Basic Placement 4. [Figure 85] This figure shows an example of antenna placement related to Modification 2 of Basic Placement 4. [Figure 86] This figure shows an example of antenna placement related to Modification 2 of Basic Placement 4. [Figure 87] This figure shows an example of antenna placement related to Modification 2 of Basic Placement 4. [Figure 88A] This figure shows an example of antenna placement related to Modification 2 of Basic Placement 4. [Figure 88B] This figure shows an example of antenna placement related to Modification 2 of Basic Placement 4. [Figure 89] Diagram showing an example of antenna placement related to basic configuration 5. [Figure 90A] Diagram showing an example of antenna placement related to basic configuration 5. [Figure 90B] Diagram showing an example of antenna placement related to basic configuration 5. [Figure 91A] Diagram showing an example of antenna placement related to basic configuration 5. [Figure 91B] Diagram showing an example of antenna placement related to basic configuration 5. [Figure 92A] Diagram showing an example of antenna placement related to basic configuration 5. [Figure 92B] Diagram showing an example of antenna placement related to basic configuration 5. [Figure 92C] Diagram showing an example of antenna placement related to basic configuration 5. [Figure 92D] Diagram showing an example of antenna placement related to basic configuration 5. [Figure 93A] This figure shows an example configuration of a transmitting array antenna using a sub-array related to the basic arrangement 5. [Figure 93B] This figure shows an example configuration of a transmitting array antenna using a sub-array related to the basic arrangement 5. [Figure 94] This figure shows an example of direction estimation results using the transmit / receive antenna arrangement related to basic configuration 5. [Figure 95] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 5. [Figure 96] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 5. [Figure 97] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 5. [Figure 98] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 5. [Figure 99] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 5. [Figure 100A] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 5. [Figure 100B]This figure shows an example of antenna placement related to Modification 1 of Basic Placement 5. [Figure 101] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 5. [Figure 102] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 5. [Figure 103] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 5. [Figure 104] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 5. [Figure 105] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 5. [Figure 106A] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 5. [Figure 106B] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 5. [Figure 107] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 5. [Figure 108] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 5. [Figure 109] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 5. [Figure 110] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 5. [Figure 111] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 5. [Figure 112A] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 5. [Figure 112B] This figure shows an example of antenna placement related to Modification 1 of Basic Placement 5. [Modes for carrying out the invention]

[0018] As mentioned above, MIMO radar, which constitutes a virtual receiving array, can be applied not only to one-dimensional scanning (angle measurement) in the vertical or horizontal direction, but also to two-dimensional beam scanning in the vertical and horizontal directions.

[0019] As an example, FIG. 1A shows a transmitting array antenna including four transmitting antennas (Tx#1 to Tx#4) arranged in the vertical direction (the longitudinal direction in FIG. 1A), and a receiving array antenna including four receiving antennas (Rx#1 to Rx#4) arranged in the horizontal direction (the lateral direction in FIG. 1A). In FIG. 1A, the transmitting antennas are arranged at equal intervals (d V ) in the vertical direction, and the receiving antennas are arranged at equal intervals (d H ) in the horizontal direction (see, for example, Non-Patent Document 4).

[0020] FIG. 1B shows a virtual receiving array including the transmitting and receiving array antennas of the antenna arrangement shown in FIG. 1A. The virtual receiving array shown in FIG. 1B is composed of a 16-element virtual receiving antenna (VA#1 to VA#16) in which four antennas are arranged in the horizontal direction and four antennas are arranged in the vertical direction in a rectangular shape. In FIG. 1B, the element intervals in the horizontal and vertical directions of the virtual receiving array are d H , d V respectively. That is, the aperture lengths D H , D V in the horizontal and vertical directions of the virtual receiving array are 3d H , 3d V respectively.

[0021] FIGS. 2A and 2B show Fourier beam patterns directed in the horizontal 0° and vertical 0° directions in the antenna arrangement of the MIMO radar shown in FIGS. 1A and 1B, where the element interval d H in the horizontal direction is set to 0.5λ, and the element interval d V in the vertical direction is set to 0.5λ. Here, λ represents the wavelength of the radar carrier wave.

[0022] As shown in Figures 2A and 2B, 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 2A and 2B, a beam width of approximately 13° corresponds to a power value of 3dB. Also, as shown in Figures 2A and 2B, 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 2A and 2B, 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 -13dB.

[0023] To expand 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, for example. Therefore, to narrow the antenna's directivity, the antenna size must be increased.

[0024] For example, in radar devices mounted on vehicles (also called automotive radar), a sub-array antenna is used, which consists of multiple antenna elements arranged vertically, in order to narrow the vertical directivity (see, for example, Non-Patent Document 3). By narrowing the vertical directivity, the vertical antenna gain can be improved, and reflected waves in unwanted directions such as the road surface can be reduced.

[0025] However, when using sub-array antennas as antenna elements in a transmitting or receiving array antenna, the spacing between elements in the array antenna cannot be narrower 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 using a sub-array antenna vertically in the MIMO radar shown in Figure 1A, the vertical element spacing d V This will extend the wavelength beyond one wavelength.

[0026] Figures 3A and 3B show the vertical element spacing d in the transmit / receive antenna arrangement of the MIMO radar shown in Figure 1A. V Examples of Fourier beam patterns directed at 0° horizontally and 0° vertically are shown when the wavelength (λ) is 1 wavelength (λ) or longer. Note that the directivity of individual antenna elements in a vertical sub-array is not considered in Figures 3A and 3B.

[0027] Furthermore, in Figure 3A, the vertical element spacing d V =λ, horizontal element spacing d H = 0.5λ, and in Figure 3B, the vertical element spacing d V =2λ, horizontal element spacing d H = 0.5λ.

[0028] As shown in Figures 3A and 3B, the main beam (main lobe) is oriented in the horizontal 0° and vertical 0° directions, and compared to the side lobes in Figures 2A and 2B, for example, a higher level of grating lobe is generated in the vertical direction around the main beam. In Figures 3A and 3B, the ratio of the peak level of the grating lobe to the peak level of the main lobe is 0 dB. Also, in Figure 3B (d V In Figure 3A(d) = 2λ), V Compared to (λ), the angular spacing at which high levels of grating lobes occur in the vertical direction is narrower. That is, the element spacing d in the vertical direction V It can be observed that the wider the area, the narrower the angular interval at which grating lobes occur.

[0029] Thus, as the vertical antenna size of a radar system increases, the vertical spacing between elements widens, making it easier 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.

[0030] One embodiment of the present disclosure enables the suppression of grating lobes and improvement of vertical or horizontal angular resolution when performing beam scanning in two dimensions, vertical and horizontal, using MIMO radar, even when the vertical or horizontal antenna size (or element size) is one wavelength or larger.

[0031] 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.

[0032] In the following description, we will explain a radar system configuration in which the transmitting branch sends out different transmission signals that are code-division multiplexed from multiple transmitting antennas, and the receiving branch separates each transmission signal for reception processing. However, the configuration of the radar system is not limited to this, and it may also be configured in which the transmitting branch sends out different transmission signals that are frequency-division multiplexed from multiple transmitting antennas, and the receiving branch separates each transmission signal for reception processing. Similarly, the radar system may also be configured in which the transmitting branch sends out transmission signals that are time-division multiplexed from multiple transmitting antennas, and the receiving branch performs reception processing.

[0033] [Embodiment 1] [Radar system configuration] Figure 4 is a block diagram showing the configuration of the radar device 10 according to this embodiment.

[0034] The radar device 10 includes a radar transmitting unit (transmitting branch) 100, a radar receiving unit (receiving branch) 200, and a reference signal generation unit 300.

[0035] The radar transmitter 100 generates a high-frequency (radio frequency) radar signal (radar transmission signal) based on a reference signal received from the reference signal generation unit 300. The radar transmitter 100 then transmits the radar transmission signal at a predetermined transmission cycle using a transmission array antenna composed of multiple transmitting antennas 106-1 to 106-Nt.

[0036] The radar receiver 200 receives the reflected wave signal, which is the radar transmission signal reflected from a target (not shown), using a receiving array antenna that includes multiple receiving antennas 202-1 to 202-Na. The radar receiver 200 performs synchronized processing with the radar transmitter 100 by using a reference signal received from the reference signal generation unit 300 to perform the following processing operations. Specifically, the radar receiver 200 processes the reflected wave signal received by each receiving antenna 202 to perform at least one of the following processes: detection of the presence or absence of a target and estimation of its direction. The target is an object that the radar device 10 detects, and includes, for example, vehicles (including four-wheeled and two-wheeled vehicles) or people.

[0037] The reference signal generation unit 300 is connected to the radar transmission unit 100 and the radar reception unit 200, respectively. The reference signal generation unit 300 supplies a reference signal as a reference signal to the radar transmission unit 100 and the radar reception unit 200, and synchronizes the processing of the radar transmission unit 100 and the radar reception unit 200.

[0038] [Configuration of radar transmitter 100] The radar transmission unit 100 includes radar transmission signal generation units 101-1 to 101-Nt, transmission radio units 105-1 to 105-Nt, and transmission antennas 106-1 to 106-Nt. In other words, the radar transmission unit 100 has Nt transmission antennas 106, and each transmission antenna 106 is connected to an individual radar transmission signal generation unit 101 and transmission radio unit 105.

[0039] The radar transmission signal generation unit 101 generates a timing clock by multiplying the reference signal received from the reference signal generation unit 300 by a predetermined number of times, and generates a radar transmission signal based on the generated timing clock. The radar transmission signal generation unit 101 then repeatedly outputs the radar transmission signal at a predetermined radar transmission period (Tr). The radar transmission signal is r z (k, M=I z (k, M) + j Q z This is represented by (k, M), where z represents the number corresponding to each transmitting antenna 106, and z = 1, ..., Nt. Also, j represents the imaginary unit, k represents discrete time, and M represents the ordinal number of the radar transmission period.

[0040] Each radar transmission signal generation unit 101 includes a code generation unit 102, a modulation unit 103, and an LPF (Low Pass Filter) 104. The following describes each component of the radar transmission signal generation unit 101-z corresponding to the z-th (z=1,...,Nt) transmitting antenna 106.

[0041] For example, the code generation unit 102 generates a code a(z) of a code sequence with code length L for each radar transmission period Tr. n (n=1,…,L)(pulse code) is generated. The code a(z) generated in each code generation unit 102-1 to 102-Nt is n The codes used for (z=1,…,Nt) are those that are lowly correlated or uncorrelated with each other. Examples of code sequences include Walsh-Hadamard codes, M-sequence codes, and Gold codes.

[0042] The modulation unit 103 outputs a code sequence (for example, code a(z)) from the code generation unit 102.n Pulse modulation (amplitude modulation, ASK (Amplitude Shift Keying), pulse shift keying) or phase modulation (Phase Shift Keying) is applied to the signal, and the modulated signal is output to LPF104.

[0043] The LPF104 outputs signal components below a predetermined limited bandwidth from the modulated signal output from the modulation unit 103 to the transmitting radio unit 105 as a baseband radar transmission signal.

[0044] The z-th (z=1,…,Nt) transmitting radio unit 105 performs frequency conversion on the baseband radar transmission signal output from the z-th radar transmission signal generation unit 101 to generate a radar transmission signal in the carrier frequency (Radio Frequency: RF) band, amplifies it to a predetermined transmission power P [dB] using a transmitting amplifier, and outputs it to the z-th transmitting antenna 106.

[0045] The z-th (z=1,…,Nt) transmitting antenna 106 radiates the radar transmission signal output from the z-th transmitting radio unit 105 into space.

[0046] Figure 5 shows the radar transmission signals transmitted from the Nt transmitting antennas 106 of the radar transmitter 100. The code transmission section Tw contains a pulse code sequence with code length L. During each radar transmission period Tr, the pulse code sequence is transmitted during the code transmission section Tw, and the remaining section (Tr-Tw) is a no-signal section. One pulse code (a(z) n Pulse modulation is applied using No samples per unit, so that each code transmission section Tw contains signals from Nr (= No × L) samples. That is, the sampling rate in the modulation section 103 is (No × L) / Tw. Also, the no-signal section (Tr-Tw) contains Nu samples.

[0047] The radar transmission unit 100 may also include a radar transmission signal generation unit 101a, as shown in Figure 6, instead of the radar transmission signal generation unit 101. The radar transmission signal generation unit 101a does not have the code generation unit 102, modulation unit 103, and LPF 104 shown in Figure 4, but instead includes a code storage unit 111 and a DA conversion unit 112. The code storage unit 111 stores the code sequences generated by the code generation unit 102 (Figure 4) in advance and reads out the stored code sequences sequentially in a cyclical manner. The DA conversion unit 112 converts the code sequences (digital signals) output from the code storage unit 111 into analog signals (baseband signals).

[0048] [Configuration of radar receiver 200] In Figure 4, the radar receiver 200 is equipped with Na receiving antennas 202, forming an array antenna. The radar receiver 200 also has Na antenna system processing units 201-1 to 201-Na and a direction estimation unit 214.

[0049] Each receiving antenna 202 receives a reflected wave signal, which is a radar transmission signal reflected from a target (object), and outputs the received reflected wave signal as a received signal to the corresponding antenna system processing unit 201.

[0050] Each antenna system processing unit 201 includes a receiving radio unit 203 and a signal processing unit 207.

[0051] The receiving radio unit 203 includes an amplifier 204, a frequency converter 205, and a quadrature detector 206. The receiving radio unit 203 generates a timing clock obtained by multiplying the reference signal output from the reference signal generation unit 300 by a predetermined number of times, and operates based on the generated timing clock. Specifically, the amplifier 204 amplifies the received signal output from the receiving antenna 202 to a predetermined level, the frequency converter 205 frequency-converts the high-frequency band received signal to the baseband band, and the quadrature detector 206 converts the baseband band received signal into a baseband band received signal including the I signal and the Q signal.

[0052] The signal processing unit 207 includes AD conversion units 208 and 209, and separation units 210-1 to 210-Nt.

[0053] The AD converter 208 receives the I signal from the quadrature detector 206, and the AD converter 209 receives the Q signal from the quadrature detector 206. The AD converter 208 converts the I signal into digital data by performing discrete-time sampling on the baseband signal including the I signal. The AD converter 209 converts the Q signal into digital data by performing discrete-time sampling on the baseband signal including the Q signal.

[0054] Here, in the sampling of the AD conversion units 208 and 209, Ns discrete samples are taken for each subpulse time Tp (=Tw / L) in the radar transmission signal. In other words, the number of oversamples per subpulse is Ns.

[0055] In the following explanation, the baseband received signal at discrete time k of the Mth radar transmission period Tr[M], as the output of the AD converters 208 and 209, is represented as the complex number signal x(k, M) = Ir(k, M) + j Qr(k, M), using the I signal Ir(k, M) and the Q signal Qr(k, M). Furthermore, in the following, the discrete time k is based on the start timing of the radar transmission period (Tr) (k=1), and the signal processing unit 207 operates periodically up to the sample point k=(Nr+Nu)Ns / No, which is before the end of the radar transmission period Tr. That is, k=1,...,(Nr+Nu)Ns / No. Here, j is the imaginary unit.

[0056] The signal processing unit 207 includes Nt separation units 210, which are equal to the number of systems corresponding to the number of transmitting antennas 106. Each separation unit 210 has a correlation calculation unit 211, an addition unit 212, and a Doppler frequency analysis unit 213. The configuration of the z-th (z=1,...,Nt) separation unit 210 will be described below.

[0057] The correlation calculation unit 211 calculates, for each radar transmission period Tr, a discrete sample value x(k, M) including discrete sample values ​​Ir(k, M) and Qr(k, M) received from the AD conversion units 208 and 209, and a pulse code a(z) with code length L transmitted by the radar transmission unit 100. n (However, correlation calculation is performed with z=1,...,Nt, n=1,...,L). For example, the correlation calculation unit 211 performs correlation calculation with discrete sample values ​​x(k, M) and pulse code a(z) n A sliding correlation calculation is performed. For example, the correlation value AC of the sliding correlation calculation of discrete time k in the Mth radar transmission period Tr[M]. (z) (k, M) is calculated based on the following formula.

number

[0058] In the above equation, the asterisk (*) represents the complex conjugate operator.

[0059] The correlation calculation unit 211 performs correlation calculations over periods k=1, ..., (Nr+Nu)Ns / No, for example, according to equation (1).

[0060] Furthermore, the correlation calculation unit 211 is not limited to performing correlation calculations for k=1,…,(Nr+Nu)Ns / No, but may limit the measurement range (i.e., the range of k) according to the range of the target being measured by the radar device 10. This makes it possible for the radar device 10 to reduce the amount of computational processing required by the correlation calculation unit 211. For example, the correlation calculation unit 211 may limit the measurement range to k=Ns(L+1),…,(Nr+Nu)Ns / No-NsL. In this case, as shown in Figure 7, the radar device 10 does not perform measurements in the time interval corresponding to the code transmission section Tw.

[0061] As a result, even when the radar transmission signal directly feeds back into the radar receiver 200, the radar device 10 does not perform processing by the correlation calculation unit 211 during the period when the radar transmission signal feeds back (at least for a period less than τ1), thus enabling measurement that eliminates the effects of feedback. Furthermore, when limiting the measurement range (range of k), the same method of limiting the measurement range (range of k) can be applied to the processing of the summing unit 212, the Doppler frequency analysis unit 213, and the direction estimation unit 214, which will be described below. This reduces the amount of processing in each component and lowers the power consumption of the radar receiver 200.

[0062] The summing unit 212 outputs the correlation calculation value AC from the correlation calculation unit 211 at each discrete time k of the Mth radar transmission period Tr. (z) Using (k, M), the correlation calculation value AC is calculated over a predetermined number of times (Np times) of the radar transmission period Tr over a period of (Tr × Np). (z) (k, M) are added (coherent integral). The process of adding (coherent integral) the number Np over a period of time (Tr × Np) is expressed by the following equation.

number

[0063] Here, CI (z) (k, m) represents the sum of the correlation calculation values ​​(hereinafter referred to as the correlation sum), Np is an integer value of 1 or greater, and m is an integer of 1 or greater that indicates the ordinal number of additions when the number of additions Np in the addition unit 212 is considered as one unit. Also, z = 1, ..., Nt.

[0064] The adder 212 performs Np additions, using the output of the correlation calculation unit 211, obtained with the radar transmission period Tr as the unit, as one unit. In other words, the adder 212 calculates the correlation calculation value AC (z) (k, Np(m-1)+1)~AC (z) The correlation value CI is calculated by summing (k, Np×m) as a unit, while aligning the timing of discrete time points k. (z)(k, m) is calculated at discrete time intervals k. As a result, the summing unit 212 can improve the SNR (Signal to Noise Ratio) of the reflected wave signal in the range where the reflected wave signal from the target has a high correlation, due to the effect of adding the correlation calculation values ​​over Np times. Therefore, the radar receiver unit 200 can improve its measurement performance in estimating the arrival distance of the target.

[0065] Furthermore, in order to obtain an ideal summation gain, it is necessary that the phase components of the correlated calculation values ​​align within a certain range during the summation interval of the number of summations Np of the correlated calculation values. In other words, it is preferable that the number of summations Np be set based on the assumed maximum moving speed of the target being measured. This is because the greater the assumed maximum speed of the target, the greater the fluctuation in the Doppler frequency contained in the reflected wave from the target. As a result, the time period with high correlation becomes shorter, the number of summations Np becomes a small value, and the gain improvement effect of summation by the summing unit 212 becomes smaller.

[0066] The Doppler frequency analysis unit 213 uses the CI, which is the Nc output of the summation unit 212 obtained at discrete time k intervals. (z) (k, Nc(w-1)+1)~CI (z) Using (k,Nc×w) as a unit, coherent integration is performed by aligning the timing of discrete time k. For example, the Doppler frequency analysis unit 213 corrects the phase variation Φ(fs) = 2πfs(Tr×Np)ΔΦ corresponding to 2Nf different Doppler frequencies fsΔΦ, as shown in the following equation, and then performs coherent integration.

number

[0067] Here, FT_CI (z) Nant(k, fs, w) is the w-th output of the Doppler frequency analysis unit 213 and represents the coherent integral result of the Doppler frequency fsΔΦ at discrete time k in the Nant-th antenna system processing unit 201. Here, Nant = 1 to Na, fs = -Nf + 1, ..., 0, ..., Nf, k = 1, ..., (Nr + Nu)Ns / No, w is an integer greater than or equal to 1, and ΔΦ is the phase rotation unit.

[0068] As a result, each antenna system processing unit 201 calculates the FT_CI, which is the coherent integral result corresponding to 2Nf Doppler frequency components at discrete time intervals k. (z) Nant (k, -Nf+1,w),…, FT_CI (z) Nant (k, Nf-1, w) is obtained at multiple Np × Nc periods (Tr × Np × Nc) of the radar transmission period Tr. Note that j is the imaginary unit, and z = 1, ..., Nt.

[0069] When ΔΦ = 1 / (Nc × Tr × Np), the processing of the Doppler frequency analysis unit 213 described above is equivalent to performing a Discrete Fourier Transform (DFT) on the output of the summing unit 212 with a sampling interval Tm = (Tr × Np) and a sampling frequency fm = 1 / Tm.

[0070] Furthermore, by setting Nf to a power of 2, the Doppler frequency analysis unit 213 can apply Fast Fourier Transform (FFT) processing, thereby reducing the amount of computation. Note that when Nf > Nc, CI occurs in the region where q > Nc. (z) By performing zero-padding (k, Nc(w-1)+q)=0, the same FFT process can be applied, reducing the amount of computation required.

[0071] Furthermore, instead of FFT processing, the Doppler frequency analysis unit 213 may perform sequential multiply-accumulate operations as shown in equation (3) above. In other words, the Doppler frequency analysis unit 213 calculates the CI, which is the Nc output of the summation unit 212 obtained at each discrete time k. (z) For (k, Nc(w-1)+q+1), the coefficients corresponding to fs=-Nf+1,…,0,…,Nf-1 are exp[-j2πf s T r N p Alternatively, we can generate qΔφ and perform sequential sum-of-products operations. Here, q = 0 to Nc-1.

[0072] In the following explanation, the wth output FT_CI obtained by performing the same processing in each of the Na antenna system processing units 201 is described. (z) 1 (k, fs, w), FT_CI (z) 2 (k, fs, w),…, FT_CI (z) Na The (k, fs, w) is expressed as the virtual receive array correlation vector h(k, fs, w) as shown in the following equation. The virtual receive array correlation vector h(k, fs, w) contains Nt × Na elements, which is the product of the number of transmitting antennas Nt and the number of receiving antennas Na. The virtual receive array correlation vector h(k, fs, w) is used later to explain the process of estimating the direction of the reflected wave signal from the target based on the phase difference between the 202 receiving antennas. Here, z = 1, ..., Nt and b = 1, ..., Na.

number

number

[0073] The processing in each component of the signal processing unit 207 has been described above.

[0074] The direction estimation unit 214 applies an array correction value h_cal to the virtual received array correlation vector h(k, fs, w) of the w-th Doppler frequency analysis unit 213 output from the antenna system processing units 201-1 to 201-Na. [y] The virtual received array correlation vector h is obtained by correcting the phase deviation and amplitude deviation between the antenna system processing units 201 using this method. _after_cal Calculate (k, fs, w). Virtual received array correlation vector h _after_cal (k, fs, w) are expressed by the following equation. Note that y = 1, ..., (Nt × Na).

number

[0075] virtual receive array correlation vector h corrected for inter-antenna deviation _after_cal (k, fs, w) is a column vector consisting of Na × Nr elements. Below, the virtual receive array correlation vector h _after_cal Each element (k, fs, w) is h1(k, fs, w), ..., h Na×Nr The notation (k, fs, w) is used to explain the direction estimation process.

[0076] [Antenna arrangement in radar device 10] The arrangement of Nt transmitting antennas 106 and Na receiving antennas 202 in the radar device 10 having the above configuration will now be described.

[0077] <Basic layout 1> Figure 8 shows an example of the arrangement of the transmitting antenna 106 and receiving antenna 202 in the basic configuration 1, and an example of the arrangement of the virtual receiving array.

[0078] Note that the horizontal spacing D used in the following explanation (for example, the horizontal direction in Figure 8) H , and the vertical spacing D (for example, the vertical direction in Figure 8) V For example, they are considered identical. Note that interval D H , and interval D V They may be different.

[0079] (1) Arrangement of transmitting and receiving antennas In Figure 8, the number of transmitting antennas 106 in the transmitting array antenna is set to Nt = 4 (Tx#1, Tx#2, Tx#3, and Tx#4), and the number of receiving antennas 202 in the receiving array antenna is set to Na = 4 (Rx#1, Rx#2, Rx#3, and Rx#4).

[0080] The transmitting array antenna shown in Figure 8 consists of a "first transmitting antenna group" (Tx#2, Tx#4 in Figure 8) and a "second transmitting antenna group" (Tx#1, Tx#3 in Figure 8). Each transmitting antenna group is positioned identically in the vertical direction, and the antenna spacing in the horizontal direction (lateral direction in Figure 8) is 2D. H It includes two transmitting antenna elements. Furthermore, the vertical distance (vertical direction in Figure 8) between the "first transmitting antenna group" and the "second transmitting antenna group" is, for example, 3D V This is the result.

[0081] Furthermore, the receiving array antenna shown in Figure 8 consists of a "first receiving antenna group" (Rx#2, Rx#4 in Figure 8) and a "second receiving antenna group" (Rx#1, Rx#3 in Figure 8). Each receiving antenna group is positioned identically in the vertical direction, and the antenna spacing in the horizontal direction is 3D H It includes two receiving antenna elements. The vertical distance between the "first receiving antenna group" and the "second receiving antenna group" is, for example, 2D V This is the result.

[0082] In other words, in Figure 8, the vertical spacing between the transmitting antenna groups (in Figure 8, 3D V ) and the horizontal antenna spacing within each receiving antenna group (3D in Figure 8) H ) is the same. Also, in Figure 8, the horizontal antenna spacing within each transmitting antenna group (2D in Figure 8) H ) and the vertical spacing between the receiving antenna groups (2D in Figure 8) H ) is identical to this.

[0083] Furthermore, in Figure 8, the spacing between the transmitting antenna groups is 3D. V (or, 3D antenna spacing within the receiving antenna group) H ) and the 2D spacing between antennas within the transmitting antenna group. H (or, 2D spacing between receiving antenna groups) V The difference between this and D H or D V That is the case.

[0084] Furthermore, in Figure 8, the antenna spacing within the transmitting antenna group is 2D. H (D H (Intervals that are integer multiples of the interval) and the 3D antenna spacing within the receiving antenna group H (D H The difference between (an integer multiple of) is D H Furthermore, in Figure 8, the spacing between the multiple transmitting antenna groups is 3D. V (D V (Intervals that are integer multiples of the interval) and the spacing at which multiple receiving antenna groups are arranged 2D V (D V The difference between (an integer multiple of) is D V That is the case.

[0085] (2) Arrangement of virtual receiver array The arrangement of the virtual receiving array (virtual antennas VA#1 to VA#16) formed by the transmitting and receiving antenna arrangement shown in Figure 8 above has the following characteristics.

[0086] Here, the arrangement of the virtual receiving array can be expressed as follows, based on the positions of the transmitting antennas (feed points) that make up the transmitting array antenna, and the positions of the receiving antennas (feed points) that make up the receiving array antenna.

number

[0087] Note that mod(x,y) is an operator that calculates the remainder after division (modulo operation) and returns the remainder when x is divided by y. Also, ceil(x) is an operator that returns the value rounded to the nearest integer greater than or equal to x. In Equation (7), the X-axis corresponds to the horizontal direction (lateral direction) shown in FIG. 8, and the Y-axis corresponds to the vertical direction (longitudinal direction) shown in FIG. 8.

[0088] Here, the position coordinates of the transmission antenna 106 constituting the transmission array antenna are (X T_#n ,Y T_#n )(where n = 1,..., Nt), the position coordinates of the reception antenna 202 constituting the reception array antenna are (X R_#m ,Y R_#m )(where m = 1,..., Na), and the position coordinates of the virtual antenna constituting the virtual reception array are (X V_#k ,Y V_#k )(where k = 1,..., Nt×Na). Note that in Equation (7), VA#1 is represented as the position reference (0,0) of the virtual reception array.

[0089] As an example, the case of the antenna arrangement shown in FIG. 8 will be described.

[0090] The position coordinates of the transmission antenna 106 constituting the transmission array antenna are based on the position coordinates (X T_#1 ,Y T_#1 ) of the transmission antenna Tx#1. The position coordinates of the transmission antenna Tx#2 are (X T_#2 ,Y T_#2 )=(X T_#1 ,Y T_#1 +3D V ), the position coordinates of the transmission antenna Tx#3 are (X T_#3 ,Y T_#3 )=(X T_#1 +2D H ,Y T_#1 ), and the position coordinates of the transmission antenna Tx#4 are (X T_#4 ,Y T_#4 )=(X T_#1 +2D H ,Y T_#1 +3D V ) and are represented as such.

[0091] Similarly, the position coordinates of receiving antenna 202, which constitutes the receiving array antenna, are the position coordinates (X) of receiving antenna Rx#1. R_#1 ,Y R_#1 ) is used as the reference point for the position coordinates (X) of the receiving antenna Rx#2. R_#2 ,Y R_#2 )=(X R_#1 ,Y R_#1 +2D V ), position coordinates (X) of receiving antenna Rx#3 R_#3 ,Y R_#3 )=(X R_#1 +3D H ,Y R_#1 ), and the position coordinates (X) of the receiving antenna Rx#4. R_#4 ,Y R_#4 )=(X R_#1 +3D H ,Y R_#1 +2D V ) is expressed as.

[0092] With this arrangement of transmitting array antennas and receiving array antennas, the position coordinates (X) of the virtual receiving array VA#1~VA#16 are determined. V_#1 ,Y V_#1 )~(X V_#16 ,Y V_#16 ) are as follows: (0,0), (0, 3D V ), (2D H , 0), (2D H , 3D V ), (0, 2D V ), (0, 5D V ), (2D H , 2D V ), (2D H , 5D V ), (3D H ,0), (3D H , 3D V ), (5D H , 0), (5D H , 3D V ), (3D H , 2D V ), (3D H , 5D V ), (5D H, 2D V ), (5D H , 5D V )

[0093] Thus, in the virtual receiver array arrangement shown in Figure 8, each virtual receiver array element is positioned at a different location without overlap. Therefore, the aperture length of the virtual receiver array can be expanded, narrowing the main lobe and improving the angular resolution.

[0094] Furthermore, as shown in Figure 8, the virtual array elements VA#4, VA#7, VA#10, and VA#13 located near the center of the virtual receiving array are horizontally oriented D H Spacing, vertically D V They are densely arranged at intervals. For example, in Figure 8, interval D H and interval D V When the value is set to approximately 0.5λ, the virtual array elements VA#4, VA#7, VA#10, and VA#13 are positioned horizontally in the D direction. H = 0.5λ intervals, vertically in the direction D V They are spaced at 0.5λ intervals. This reduces grating lobes. The effect of reducing grating lobes will be discussed later.

[0095] Furthermore, there is no dependency on the relative positions of the transmitting array antenna and the receiving array antenna in the arrangement of the virtual receiving array. Therefore, the relative positions of the transmitting array antenna and the receiving array antenna are not limited to the arrangement shown in Figure 8, but can be set arbitrarily. The same applies to other arrangement configurations described below.

[0096] Furthermore, similar effects can be obtained by changing the horizontal and vertical arrangement of the transmitting and receiving array antennas shown in Figure 8 to a vertical and horizontal arrangement (for example, an arrangement rotated 90 degrees from the arrangement in Figure 8). The same applies to other arrangement configurations described below.

[0097] Furthermore, in the antenna configuration shown in Figure 8, the configurations of the transmitting array antennas and the receiving array antennas may be swapped. For example, the receiving array antenna configuration shown in Figure 8 may be used as the transmitting array antenna configuration, and the transmitting array antenna configuration shown in Figure 8 may be used as the receiving array antenna configuration. Even if the transmitting array antenna configurations and the receiving array antenna configurations are swapped, the configuration of the virtual receiving array remains the same, and similar effects can be obtained. The same applies to other configurations described below.

[0098] Here, as an example, in Figure 8, interval D H and interval D V Let's explain the case where the value is approximately 0.5λ. As shown in Figure 8, in both the transmitting antenna array and the receiving antenna array, the spacing between each antenna element is 2D H , 3D H , 2D V and 3D V It is one of the following. In other words, in Figure 8, the spacing between the transmitting antenna groups is 3D. V , 3D antenna spacing within the receiving antenna group H , antenna spacing within the transmitting antenna group 2D H , and the spacing between receiving antenna groups 2D V This interval is longer than one wavelength of the radar transmission signal (e.g., radar carrier wave). Therefore, in Figure 8, the horizontal and vertical element sizes of the transmitting antenna 106 and the receiving antenna 202 can be designed to be approximately 1λ or larger.

[0099] This allows, for example, an antenna using four elements arranged in a sub-array, such as the one shown in Figure 9A, where two planar patch antennas are arranged vertically and two horizontally, to be applied to at least one antenna element of the transmitting array antenna and the receiving array antenna shown in Figure 8. However, in Figure 9A, the antenna width W ANT < 2D H , and antenna height H ANT <2D V That is the case.

[0100] Furthermore, in the case of Figure 8, the vertical antenna spacing of the transmitting array antenna is 3DV The horizontal antenna spacing is 2D. H It is wider than that. Therefore, for example, an antenna using six elements as a sub-array, such as the one shown in Figure 9B, which consists of three planar patch antennas arranged vertically and two horizontally, can be applied to each antenna element of the transmitting array antenna shown in Figure 8. However, in Figure 9B, the antenna width W is ANT < 2D H , and antenna height H ANT < 3D V That is the case.

[0101] Furthermore, in the case of Figure 8, the horizontal antenna spacing of the receiving array antenna is 3D H The vertical antenna spacing is 2D. V It is wider than that. Therefore, for example, an antenna using six elements as a sub-array, such as the one shown in Figure 9C, which consists of two planar patch antennas arranged vertically and three horizontally, can be applied to each antenna element of the receiving array antenna shown in Figure 8. However, in Figure 9C, the antenna width W is ANT < 3D H , and antenna height H ANT <2D V That is the case.

[0102] In the antenna arrangement shown in Figure 8, using an antenna with a sub-array configuration as shown in Figures 9A, 9B, or 9C can improve the directional gain of the antenna and thus improve the detection performance (e.g., detection distance) of the radar device 10. Note that the sub-array configuration applied to the antenna elements shown in Figure 8 is not limited to the configurations shown in Figures 9A, 9B, and 9C; any sub-array configuration that allows the antenna elements (in other words, the antenna system) to be positioned at the location shown in Figure 8 is acceptable.

[0103] As an example, Figure 10 shows an example where the sub-array shown in Figure 9B is applied to each antenna element of the transmitting array antenna shown in Figure 8. As shown in Figure 10, the transmitting array antenna has a vertical size of 3D V , horizontal size 2D H It is composed of each antenna element in a subarray configuration.

[0104] Thus, according to basic configuration 1, for example, a size of 1λ or more (for example, D H =D V Antenna elements can be applied (for the case of =0.5λ), and in the virtual receiving array, the virtual antennas can be densely arranged in the horizontal and vertical directions (for example, D H or D V They can be placed at intervals. Therefore, it is possible to reduce (in other words, suppress) grating lobes while improving the directional gain of the antenna.

[0105] The above describes an example of antenna arrangement in the radar device 10.

[0106] The direction estimation unit 214 uses the received signals of a virtual receiving array (see, for example, Figure 8) obtained from the arrangement of the transmitting and receiving antennas described above (see, for example, Figure 8) to perform horizontal and vertical direction estimation processing as follows.

[0107] The element number (VA# number) of the above virtual receiving array is the virtual receiving array correlation vector h corrected for the inter-antenna deviation shown in equation (6). _after_cal This corresponds to the element index of the column vector (k, fs, w). For example, VA#1 shown in Figure 8 is h _after_cal This corresponds to the first element h1(k, fs, w) of the column vector element (k, fs, w). The same applies to the other VA#2 to VA#16 shown in Figure 8.

[0108] In estimating the direction of arrival in the horizontal and vertical directions, the direction estimation unit 214 calculates a spatial profile by making the azimuth direction θ and elevation angle direction φ in the direction estimation evaluation function value P(θ, φ, k, fs, w) variable within a predetermined angular range. The direction estimation unit 214 extracts a predetermined number of maximum peaks from the calculated spatial profile in descending order and outputs the azimuth direction and elevation angle direction of the maximum peaks as the estimated direction of arrival values.

[0109] The evaluation function value P(θ, φ, k, fs, w) can be calculated using various methods depending on the direction of arrival estimation algorithm. For example, the estimation method using an array antenna disclosed in the reference non-patent document may be used.

[0110] (Reference Non-Patent Document) 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

[0111] For example, the beamformer method can be expressed as follows. Other methods such as Capon and MUSIC can also be applied in a similar manner.

number

[0112] Here, the superscript H is the Hermitian transpose operator. Also, a(θ u ,φ v ) indicates the direction vector of the virtual receiving array for the arriving wave in the azimuth direction θ and elevation direction φ.

[0113] As described above, the direction estimation unit 214 outputs the calculated estimated direction of arrival along with the discrete time k and Doppler frequency fsΔΦ at the time of calculation of the estimated direction of arrival as radar positioning results.

[0114] Also, the azimuth direction θ u This is a vector obtained by changing the azimuth range used for estimating the direction of arrival by a predetermined 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]+1 Here, floor(x) is a function that returns the largest integer value not exceeding the real number x.

[0115] Also, φ v This is the elevation angle range used for estimating the direction of arrival, which is changed by a predetermined azimuthal interval β2. For example, φ v It will be set as follows: φ v =φmin + vβ2, v=0,…, NV NV = floor[(φmax - φmin) / β2] + 1

[0116] In this embodiment, the direction vector a(θ) of the virtual receive array is determined based on the virtual receive array arrangement VA#1, ..., VA#(Nt×Na). u ,φ v The direction vector a(θ) is calculated in advance. u ,φ v ) is a column vector of the order (Nt×Na) whose elements are the complex response of the virtual receiving array when radar reflected waves arrive from the azimuth direction θ and the elevation angle direction φ. u ,φ v ) represents the phase difference calculated geometrically and optically based on the spacing between elements in the antenna.

[0117] Furthermore, the time information k mentioned above may be converted into distance information and output. The following equation can be used to convert the time information k into distance information R(k). Here, Tw represents the code transmission interval, L represents the pulse code length, and C0 represents the speed of light.

number

[0118] Furthermore, the Doppler frequency information (fsΔΦ) may be converted to a relative velocity component and output. To convert the Doppler frequency fsΔΦ to a relative velocity component vd(fs), the following equation may be used. Here, λ is the wavelength of the carrier frequency of the RF signal output from the transmitting radio unit 105.

number

[0119] Figures 11A and 11B show an example of direction estimation results when the beamformer method is used as the direction estimation algorithm for the direction estimation unit 214. In Figures 11A and 11B, the output of the direction estimation evaluation function values ​​in the horizontal ±90 degree range and the vertical ±90 degree range, with the target true value set to 0 degrees horizontally and 0 degrees vertically, is plotted. Note that the directivity of each antenna is calculated as omnidirectional.

[0120] Figure 11A shows the transmit / receive antenna configuration shown in Figure 8 (for example, a MIMO array configuration) (where D H =0.5λ, D V An example of direction estimation results using (=0.5λ) is shown. Specifically, in Figure 11A, the conditions are that the horizontal and vertical antenna spacing of the transmitting antenna 106 is 1λ or more, and the horizontal and vertical antenna spacing of the receiving antenna 202 is also 1λ or more.

[0121] Furthermore, Figure 11B, for comparison with Figure 11A, shows an example of the MIMO radar antenna arrangement shown in Figure 1, where the vertical antenna spacing of the transmitting antennas is λ and the horizontal antenna spacing of the receiving antennas is λ (i.e., d V =λ, d H The direction estimation result for (λ) is shown.

[0122] In Figure 11B, grating lobes are generated horizontally and vertically in directions other than the horizontal and vertical 0 degrees of the target true value. In contrast, in Figure 11A, it can be seen that the grating lobes are reduced in directions other than the horizontal and vertical 0 degrees of the target true value. For example, in Figure 11A, the ratio (PSLR) of the peak power value of the highest side lobe excluding the main lobes in directions other than horizontal and vertical 0 degrees to the peak power value of the main lobe in the horizontal and vertical 0 degrees directions is approximately 0.44.

[0123] As described above, by using the MIMO array configuration shown in Figure 8, even if the vertical or horizontal element size of the antennas used in the transmitting and receiving array antennas is about 1λ, the antennas in the virtual receiving array can be arranged to include element spacings of about 0.5λ in the horizontal and vertical directions, thereby reducing grating lobes. Furthermore, as shown in Figure 8, for example, since each virtual array element of the virtual receiving array is arranged without overlap, the aperture length of the virtual receiving array can be expanded, improving the angular resolution.

[0124] Furthermore, the antenna elements used in the transmitting antenna 106 and the receiving antenna 202 can be sub-array antennas with element sizes of at least 1λ in the vertical and horizontal directions. This improves the directional gain of the antennas and enhances the detection performance (e.g., detection distance) of the radar device 10.

[0125] Note that the MIMO array configuration is not limited to the example shown in Figure 8. For example, a configuration in which the horizontal and vertical directions of the antenna configuration shown in Figure 8 are swapped may be used. In this case, the virtual receiving array configuration will be the configuration in Figure 8 with the horizontal and vertical directions swapped. This will result in the angular separation performance shown in Figure 8 and the configuration in Figure 8 with the horizontal and vertical directions swapped. Similarly, a configuration in which the horizontal and vertical directions are swapped may be used in the MIMO array configuration described below.

[0126] <Modification 1 of Basic Arrangement 1> Basic configuration 1 (for example, Figure 8) describes the case where the number of transmitting antennas 106 is 4 elements (Nt=4) and the number of receiving antennas 202 is 4 elements (Nat=4). However, the number of transmitting antennas Nt and the number of receiving antennas Na are not limited to these numbers.

[0127] In Modification 1 of Basic Configuration 1, the transmitting array antennas are arranged similarly to Basic Configuration 1, for example, with a 3D vertical spacing. VThis configuration consists of a first transmitting antenna group and a second transmitting antenna group. Furthermore, similar to the basic configuration 1, each transmitting antenna group has the same vertical position, and the antenna spacing in the horizontal direction is 2D. H It includes multiple transmitting antenna elements.

[0128] Furthermore, in Modification 1 of Basic Configuration 1, the receiving array antennas are arranged similarly to Basic Configuration 1, for example, with a vertical spacing of 2D V It consists of multiple receiving antenna groups. Furthermore, each receiving antenna group has the same position vertically, and the antenna spacing is 3D horizontally. H It includes multiple receiving antenna elements.

[0129] In other words, in Modification 1 of Basic Configuration 1, the vertical spacing between the transmitting antenna groups is the same as in Basic Configuration 1 (here, 3D V ) and the horizontal antenna spacing within each receiving antenna group (here, 3D H ) is the same. Also, the horizontal antenna spacing within each transmitting antenna group (here, 2D H ) and the vertical spacing between the receiving antenna groups (here, 2D H ) is identical to this.

[0130] Furthermore, in the following, the number of transmitting antenna groups is referred to as "N". TxGroup " is expressed as "N TxGroup_ANT It is expressed as "N". Also, the number of receiving antenna groups is expressed as "N". RxGroup " is expressed as "N RxGroup_ANT It is expressed as ".

[0131] In Modification 1 of Basic Arrangement 1, N TxGroup_ANT and N RxGroup Depending on the value of this parameter, it becomes possible to increase the number of antennas in the MIMO array.

[0132] Figure 12 shows N TxGroup_ANT =4, N RxGroupAn example of the arrangement of the transmitting antenna 106 and receiving antenna 202, and an example of the arrangement of the virtual receiving array, are shown for the case where = 2.

[0133] Figure 13 shows N TxGroup_ANT =2, N RxGroup An example of the arrangement of the transmitting antenna 106 and receiving antenna 202, and an example of the arrangement of the virtual receiving array, are shown for the case where =3.

[0134] Figure 14 shows N TxGroup_ANT =4, N RxGroup An example of the arrangement of the transmitting antenna 106 and receiving antenna 202, and an example of the arrangement of the virtual receiving array, are shown for the case where =3.

[0135] Note that in Figures 12, 13, and 14, N TxGroup = 2, N RxGroup_ANT = 2

[0136] In each MIMO array configuration shown in Figures 12, 13, and 14, for example, D H and D V By setting the value to approximately 0.5λ, the horizontal and vertical element sizes of the transmitting antenna 106 and the receiving antenna 202 can be designed to be approximately 1λ or larger.

[0137] Furthermore, for example, in the virtual receiving arrays shown in Figures 12, 13, and 14, each virtual array element is arranged in a different position without overlap, which allows for an expansion of the aperture length of the virtual receiving array and an improvement in angular resolution.

[0138] Furthermore, the virtual array elements located near the center of each virtual receiving array shown in Figures 12, 13, and 14 are D H , D V They can be placed close together at intervals. Also, D H , D V The number of virtual array elements densely arranged at intervals is N TxGroup_ANT and N RxGroup It increases depending on the situation.

[0139] For example, in a virtual receiving array, in the horizontal direction, (N TxGroup_ANT ×NRxGroup_ANT The virtual array element of )-2 is D H They are spaced apart, and in the vertical direction (N RxGroup ×N TxGroup The virtual array element of )-2 is D V They are arranged at intervals. D is located near the center of the virtual receiving array. H , D V The more densely spaced virtual array elements there are, the better the reduction effect on grating lobes and side lobes can be achieved.

[0140] Also, N TxGroup_ANT , N RxGroup_ANT The larger N is, the greater the number of virtual array elements arranged horizontally, which in turn expands the aperture length of the horizontal virtual receiving array and improves the horizontal angular resolution. Similarly, N RxGroup , N RxGroup The larger the value, the greater the number of virtual array elements arranged vertically, which allows for an expansion of the aperture length of the vertical virtual receiving array and improves the vertical angular resolution.

[0141] Figure 15 shows, for example, a MIMO array configuration (Nt=8) with a number of transmitting antennas 106 and a number of receiving antennas 202 Na=6, as shown in Figure 14. TxGroup_ANT =4, N TxGroup =2, N RxGroup =3, N RxGroup_ANT =2, D H =0.5λ, D V An example of the direction estimation result when using the beamformer method as the direction estimation algorithm for the direction estimation unit 214, with (=0.5λ) used, is shown. Note that the directivity of each antenna is calculated as omnidirectional.

[0142] Figure 15 plots the output of the estimated direction of arrival evaluation function values ​​within a range of ±90 degrees horizontally and ±90 degrees vertically, when the target true value is set to 0 degrees horizontally and 0 degrees vertically.

[0143] In Figure 15, it can be seen that the grating lobe is reduced in directions other than horizontal 0 degrees and vertical 0 degrees of the target true value, compared to, for example, Figure 11A. For example, in Figure 15, the ratio of the peak power value of the highest side lobe excluding the main lobe to the peak power value of the main lobe in the horizontal 0 degrees and vertical 0 degrees directions (PSLR) is approximately 0.22.

[0144] From here, in the case of Figure 14 (N TxGroup_ANT =4, N RxGroup =3) shows Figure 8(N TxGroup_ANT =2, N RxGroup In the case of =2) (see, for example, Figure 11A), compared to (in both figures, N TxGroup =2, N RxGroup_ANT =2), N TxGroup_ANT and N RxGroup By increasing the value, an improvement in the reduction effect of the side lobes can be observed. Also, in Figure 15, the peak of the main lobe is sharper compared to Figure 11A, and N TxGroup_ANT and N RxGroup The increase in [the specified value] indicates an improvement in angular resolution.

[0145] <Modification 2 of Basic Arrangement 1> The following describes antenna placement methods 1-2A and 1-2B in modified example 2 of basic configuration 1.

[0146] (Placement method 1-2A) In Modification 1 of Basic Configuration 1, the number of receiving antenna groups included in the receiving array antenna is N. RxGroup We explained the case where the number of virtual array elements arranged vertically is increased by increasing N. RxGroup If ≥ 3 is satisfied, then the number of transmitting antenna groups N in the transmitting array antenna. TxGroup Increasing this value can also increase the number of virtual array elements arranged vertically in the virtual receiver array.

[0147] In this case, the vertical antenna spacing of the transmitting antenna group is set to a constant value (e.g., 3D V ) may be used, but the number of receiving antenna groups NRxGroup Depending on this, the virtual receiver array configuration may result in an arrangement where virtual array elements overlap.

[0148] Therefore, in order to ensure that the virtual receiver array arrangement does not contain any overlapping virtual array elements, for example, the following spacing D can be added to the even-numbered antenna spacings in the vertical direction of the transmitting antenna group. TxGroupV You may use this.

number

[0149] For example, N RxGroup If =3, D TxGroupV =3D V N RxGroup If =4, D TxGroupV =5D V This is the result.

[0150] For example, the number of transmitting antennas N TxGroup If =3, the spacing between the three transmitting antenna groups is {3D V , D TxGroupV Let's assume the number of transmitting antenna groups is N. TxGroup If =4, the spacing between the four transmitting antenna groups is {3D V , D TxGroupV , 3D V Let's assume the number of transmitting antenna groups is N. RxGroup_ANT If = 5, the spacing between the 5 transmitting antenna groups is {3D V , D TxGroupV , 3D V , D TxGroupV Let's assume that.

[0151] Figure 16 shows N TxGroup =4, N TxGroup_ANT =4, N RxGroup =3, N RxGroup_ANT Figure 16 shows an example of the arrangement of the transmitting antenna 106 and receiving antenna 202, and an example of the arrangement of the virtual receiving array, when D = 2. TxGroupV =3D V This is the result.

[0152] Also, Figure 17 shows N TxGroup =4, N TxGroup_ANT =4, N RxGroup =4, N RxGroup_ANT Figure 17 shows an example of the arrangement of the transmitting antenna 106 and the receiving antenna 202, and an example of the arrangement of the virtual receiving array, when D = 2. TxGroupV =5D V This is the result.

[0153] Note that there are unequal intervals (for example, D) near the center of the virtual receiving array. H and D V If arrangements with a larger spacing than D are allowed, TxGroupV This value may be greater than the value in equation (11).

[0154] (Placement method 1-2B) In variation 1 of the basic configuration, the number of transmitting antennas included in each transmitting antenna group of the transmitting array antenna is N. TxGroup_ANT We explained the case where the number of virtual array elements arranged horizontally is increased by increasing N. TxGroup_ANT If ≥3 is satisfied, then the number of receiving antennas N in the receiving array antenna is RxGroup_ANT Increasing this value can also increase the number of virtual array elements arranged horizontally in the virtual receiver array.

[0155] In this case, the horizontal spacing between the receiving antennas is set to a constant value (e.g., 3D H ) may be used, but the number of transmitting antennas included in the transmitting antenna group N TxGroup_ANT Depending on this, the virtual receiver array configuration may result in an arrangement where virtual array elements overlap.

[0156] Therefore, in order to ensure that the virtual receiving array arrangement does not contain any overlapping virtual array elements, for example, the following interval D can be set between even-numbered antennas in the horizontal antenna spacing of the receiving antennas included in the receiving antenna group. RxAntH You may use this.

number

[0157] For example, N TxGroup_ANT If =3, D RxAntH =3D H N TxGroup_ANT If =4, D RxAntH =5D H This is the result.

[0158] For example, the number of receiving antennas in a receiving antenna group N RxGroup_ANT If =3, the antenna spacing of the three receiving antennas is {3D H , D RxAntH Let's assume}. Also, the number of receiving antennas N RxGroup_ANT If =4, the antenna spacing of the 4 receiving antennas is {3D H , D RxAntH , 3D H Let's assume the number of receiving antennas is N. RxGroup_ANT If = 5, the antenna spacing of the 5 receiving antennas is {3D H , D RxAntH , 3D H , D RxAntH Let's assume that.

[0159] Figure 18 shows N TxGroup =2, N TxGroup_ANT =3, N RxGroup =2, N RxGroup_ANT Figure 18 shows an example of the arrangement of the transmitting antenna 106 and receiving antenna 202, and an example of the arrangement of the virtual receiving array, when D = 4. RxAntH =3D H This is the result.

[0160] Figure 19 shows N TxGroup =2, N TxGroup_ANT =4, N RxGroup =2, N RxGroup_ANT Figure 19 shows an example of the arrangement of the transmitting antenna 106 and receiving antenna 202, and an example of the arrangement of the virtual receiving array, when D = 4. RxAntH =5D H This is the result.

[0161] Note that there are unequal intervals (for example, D) near the center of the virtual receiving array. H and DV If arrangements with a larger spacing than D are allowed, RxAntH This value may be greater than the value in equation (12).

[0162] The above describes the arrangement methods 1-2A and 1-2B in modified example 2 of basic arrangement 1.

[0163] For example, in the transmit / receive antenna configuration shown in Figures 16 to 19 (e.g., MIMO array configuration), D H and D V By setting the value to approximately 0.5λ, the horizontal and vertical element sizes of the transmitting antenna 106 and the receiving antenna 202 can be designed to be approximately 1λ or larger.

[0164] Furthermore, for example, in each virtual receiving array shown in Figures 16 to 19, each virtual array element is arranged in a different position without overlap, so the aperture length of the virtual receiving array can be expanded and the angular resolution can be improved.

[0165] Furthermore, for example, a virtual array element located near the center of the virtual receiving array shown in Figures 16 to 19 is D H , D V They can be placed close together at intervals. Also, D H , D V The number of virtual array elements densely arranged at intervals is N TxGroup , N TxGroup_ANT , N RxGroup and N RxGroup_ANT It increases depending on the situation.

[0166] For example, in a virtual receiving array, in the horizontal direction, (N TxGroup_ANT ×N RxGroup_ANT The virtual array element of )-2 is D H They are spaced apart, and in the vertical direction (N RxGroup ×N TxGroup The virtual array element of )-2 is D V They are arranged at intervals. D is located near the center of the virtual receiving array. H , D V The more densely spaced virtual array elements there are, the better the reduction effect on grating lobes and side lobes can be.

[0167] Also, N TxGroup_ANT , N RxGroup_ANT The larger N is, the greater the number of virtual array elements arranged horizontally, which in turn expands the aperture length of the horizontal virtual receiving array and improves the horizontal angular resolution. Similarly, N TxGroup , N RxGroup The larger the value, the greater the number of virtual array elements arranged vertically, which allows for an expansion of the aperture length of the vertical virtual receiving array and improves the vertical angular resolution.

[0168] Furthermore, in variation 2 of basic arrangement 1, arrangements combining arrangement methods 1-2A and 1-2B are also possible. Figure 20 shows N TxGroup =4, N TxGroup_ANT =4, N RxGroup =4, N RxGroup_ANT Figure 20 shows an example of the arrangement of the transmitting antenna 106 and receiving antenna 202 for equation (11) = 4, and an example of the arrangement of the virtual receiving array. TxGroupV =5D H And so, D in equation (12) RxAntH =5D H This results in the combined effect of arrangement methods 1-2A and 1-2B.

[0169] <Modification 3 of Basic Arrangement 1> The following describes the antenna placement methods 1-3A, 1-3B, and 1-3C in modified example 3 of basic configuration 1.

[0170] (Placement method 1-3A) Basic configuration 1 described the case where the horizontal positions of the transmitting antennas included in each transmitting antenna group are the same in a transmitting array antenna. However, the case is not limited to this, and the horizontal positions of the transmitting antennas included in each transmitting antenna group may differ.

[0171] For example, in a transmitting array antenna, each transmitting antenna included in the first transmitting antenna group and the second transmitting antenna group, respectively, has a horizontal position D HThey may be positioned with a slight offset (in other words, shifted).

[0172] D in the horizontal direction H The direction of the shift may be either to the right or to the left for each transmitting antenna in the second transmitting antenna group relative to each transmitting antenna in the first transmitting antenna group.

[0173] Figure 21 shows a transmitting array antenna where each transmitting antenna in the second transmitting antenna group (e.g., Tx#1, Tx#3) is positioned to the right relative to each transmitting antenna in the first transmitting antenna group (e.g., Tx#2, Tx#4). H Examples of the arrangement of the transmitting antenna 106 and receiving antenna 202 when they are shifted, and an example of the arrangement of the virtual receiving array are shown.

[0174] In Figure 21, the horizontal positions of Tx#1 and Tx#2 are D H They are different. Also, the horizontal positions of Tx#3 and Tx#4 are D H different.

[0175] (Placement method 1-3B) Basic configuration 1 described the case where the horizontal positions of the receiving antennas included in each receiving antenna group are the same in a receiving array antenna. However, the horizontal positions of the receiving antennas included in each receiving antenna group may differ.

[0176] For example, in a receiving array antenna, each receiving antenna included in the first receiving antenna group and the second receiving antenna group, respectively, has a horizontal position D H They may be placed at an angle.

[0177] D in the horizontal direction H The direction of the shift may be either to the right or to the left for each receiving antenna in the second receiving antenna group relative to each receiving antenna in the first receiving antenna group.

[0178] Figure 22 shows a receiving array antenna where each receiving antenna in the second receiving antenna group (e.g., Rx#1, Rx#3) is positioned to the right of each receiving antenna in the first receiving antenna group (e.g., Rx#2, Rx#4). H Examples of the arrangement of the transmitting antenna 106 and receiving antenna 202 when they are shifted, and an example of the arrangement of the virtual receiving array are shown.

[0179] In Figure 22, the horizontal positions of Rx#1 and Rx#2 are D H They are different. Also, the horizontal positions of Rx#3 and Rx#4 are D H different.

[0180] (Placement method 1-3C) Arrangement method 1-3C is a combination of arrangement methods 1-3A and 1-3B.

[0181] For example, in a transmitting array antenna, the transmitting antennas between the first transmitting antenna group and the second transmitting antenna group are positioned horizontally at D H They are positioned offset from each other. Similarly, in a receiving array antenna, the receiving antennas between the first receiving antenna group and the second receiving antenna group are positioned horizontally at a distance D H They are positioned with an offset.

[0182] Note that D in the horizontal direction H The direction of the shift can be, for example, to the right or left of each transmitting antenna in the second transmitting antenna group relative to each transmitting antenna in the first transmitting antenna group. Also, the horizontal direction D H The direction of the shift may be, for example, to the right or left of each receiving antenna in the second receiving antenna group relative to each receiving antenna in the first receiving antenna group.

[0183] Figure 23 shows an example of the arrangement of the transmitting antenna 106 and receiving antenna 202 according to arrangement method 1-3C, and an example of the arrangement of the virtual receiving array. In Figure 23, in the transmitting array antenna, each transmitting antenna (e.g., Tx#1, Tx#3) included in the second transmitting antenna group is positioned to the left of each transmitting antenna (e.g., Tx#2, Tx#4) included in the first transmitting antenna group. H They are positioned offset from each other. Also, in Figure 23, in the receiving array antenna, each receiving antenna in the second receiving antenna group (e.g., Rx#1, Rx#3) is positioned to the left of each receiving antenna in the first receiving antenna group (e.g., Rx#2, Rx#4). H They are positioned with an offset.

[0184] Figure 24 shows an example of the arrangement of the transmitting antenna 106 and receiving antenna 202 according to arrangement method 1-3C, and an example of the arrangement of the virtual receiving array. In Figure 24, in the transmitting array antenna, each transmitting antenna (e.g., Tx#1, Tx#3) included in the second transmitting antenna group is positioned to the left of each transmitting antenna (e.g., Tx#2, Tx#4) included in the first transmitting antenna group. H They are positioned offset from each other. Also, in Figure 24, in the receiving array antenna, each receiving antenna in the second receiving antenna group (e.g., Rx#1, Rx#3) is positioned to the right of each receiving antenna in the first receiving antenna group (e.g., Rx#2, Rx#4). H They are positioned with an offset.

[0185] For example, between the receiving antenna group and the transmitting antenna group, the horizontal direction is D H Compared to an arrangement where the direction of shifting is different (for example, Figure 24), the receiving antenna group and the transmitting antenna group have a horizontal D H An arrangement where the shifting direction is the same (for example, Figure 23) is more preferable because the virtual receiver array elements are more densely arranged near the center of the virtual receiver array arrangement.

[0186] The above explains the arrangement methods 1-3A to 1-3C.

[0187] For example, in the transmit / receive antenna configuration shown in Figures 21 to 24 (e.g., MIMO array configuration), D H and D V By setting the value to approximately 0.5λ, the horizontal and vertical element sizes of the transmitting antenna 106 and the receiving antenna 202 can be designed to be approximately 1λ in size.

[0188] As a result, in Modification 3 of Basic Arrangement 1, for example, an antenna is used in which four elements are arranged in a subarray by arranging two planar patch antennas vertically and horizontally, as shown in Figure 9A (where the antenna width W ANT < 2D H Antenna height H ANT <2D V ) can be applied (not shown).

[0189] Furthermore, the vertical spacing between the transmitting antenna groups is 3D V The horizontal spacing between transmitting antennas within each transmitting antenna group is 2D H Therefore, the transmitting array antenna has a wider vertical spacing than horizontal spacing. For this reason, in modification 3 of the basic configuration 1, for example, an antenna is used as a sub-array, which consists of 6 elements arranged in a 3 vertical and 2 horizontal plane patch antenna configuration, as shown in Figure 9B (where the antenna width W is...). ANT < 2D H Antenna height H ANT <3D V ) can be applied.

[0190] Furthermore, in Modification 3 of Basic Configuration 1, the horizontal positions of the transmitting antennas included in each transmitting antenna group or the receiving antennas included in each receiving antenna group are different from each other in at least one of the transmitting array antenna and receiving array antenna. Therefore, in Modification 3 of Basic Configuration 1, the lateral direction W of the subarray is different. ANT The element size is D H If it is smaller than that, the vertical element size of the subarray can be any size.

[0191] For example, Figure 25A shows an example of a subarray with eight planar patch antennas arranged vertically and one horizontally. Note that the subarray configuration is not limited to the one shown in Figure 25A.

[0192] Figure 25B also shows an example of applying the sub-array shown in Figure 25A to the transmitting antenna array shown in Figure 23 or Figure 24. In addition to the transmitting array antenna shown in Figure 25B, a parasitic element (dummy element) may be placed as shown in Figure 25C. The parasitic element can equalize the effect of inter-antenna coupling by adjacent antennas across each antenna, thereby equalizing the directional characteristics of each transmitting antenna (Tx#1~#4). Furthermore, by installing the parasitic element, the effects of electrical characteristics such as antenna radiation, impedance matching, or isolation can be made uniform. Note that the placement of the parasitic element is not limited to Figure 25C, and it may be placed in a position and size that does not physically interfere with each antenna.

[0193] Thus, in the antenna arrangement according to the modified example 3 of the basic arrangement 1, by using a sub-array configuration antenna, the directional gain of the antenna can be improved, and the detection performance (e.g., detection distance) of the radar device 10 can be improved.

[0194] Furthermore, in modification 3 of the basic arrangement 1, each virtual array element of the virtual receiving array is arranged without overlap, which allows for an expansion of the aperture length of the virtual receiving array and an improvement in angular resolution.

[0195] (Combination of Variation 3 and Variation 1) Furthermore, Modification 3 of Basic Configuration 1 may be combined with Modification 1 of Basic Configuration 1.

[0196] For example, with respect to the arrangement of the transmitting array antenna according to Modification 1 of the basic arrangement 1, the horizontal position of each transmitting antenna included in the transmitting antenna group is further defined as D between the transmitting antenna group. H A staggered arrangement is acceptable.

[0197] Similarly, for example, with respect to the arrangement of the receiving array antenna according to Modification 1 of the basic arrangement 1, the horizontal position of each receiving antenna included in the receiving antenna group is further defined as D between the receiving antenna group. H A staggered arrangement is acceptable.

[0198] Figures 26 to 30 show an example of antenna arrangement in a combination of Modification 3 and Modification 1.

[0199] Figure 26 shows N TxGroup =2, N TxGroup_ANT =4, N RxGroup =3, N RxGroup_ANT Let = 2, and the horizontal position of each transmitting antenna included in the transmitting antenna group be D H Examples of the arrangement of the transmitting antenna 106 and receiving antenna 202 in a staggered configuration, as well as an example of the arrangement of the virtual receiving array, are shown.

[0200] Also, Figure 27 shows N TxGroup =2, N TxGroup_ANT =4, N RxGroup =3, N RxGroup_ANT Let = 2, and the horizontal position of each receiving antenna included in the receiving antenna group be D H Examples of the arrangement of the transmitting antenna 106 and receiving antenna 202 in a staggered configuration, as well as an example of the arrangement of the virtual receiving array, are shown.

[0201] Also, Figure 28 shows N TxGroup =2, N TxGroup_ANT =4, N RxGroup =3, N RxGroup_ANT Let = 2, and the horizontal position of each transmitting antenna included in the transmitting antenna group be D H By shifting the position of each receiving antenna in the receiving antenna group, D is the horizontal position of each receiving antenna. H Figure 28 shows examples of the arrangement of the transmitting antenna 106 and receiving antenna 202 in the case of a staggered arrangement, and an example of the arrangement of the virtual receiving array. In Figure 28, each transmitting antenna in the second transmitting antenna group (e.g., Tx#1, Tx#3, Tx#5, Tx#7) is positioned to the left of each transmitting antenna in the first transmitting antenna group (e.g., Tx#2, Tx#4, Tx#6, Tx#8). HThey are positioned offset from each other. Also, in Figure 28, in the receiving array antenna, each receiving antenna in the second receiving antenna group (e.g., Rx#2, Rx#5) is positioned to the left of each receiving antenna in the first receiving antenna group (e.g., Rx#3, Rx#6). H They are positioned offset from each other. Also, in Figure 28, each receiving antenna in the third receiving antenna group (for example, Rx#1, Rx#4) is positioned to the left of each receiving antenna in the second receiving antenna group. H They are positioned with an offset.

[0202] Also, Figure 29 shows N TxGroup =2, N TxGroup_ANT =4, N RxGroup =3, N RxGroup_ANT Let = 2, and the horizontal position of each transmitting antenna included in the transmitting antenna group be D H By shifting the position of each receiving antenna in the receiving antenna group, D is the horizontal position of each receiving antenna. H Figure 29 shows examples of the arrangement of the transmitting antenna 106 and receiving antenna 202 in the case of a staggered arrangement, and an example of the arrangement of the virtual receiving array. In Figure 29, each transmitting antenna in the second transmitting antenna group (e.g., Tx#1, Tx#3, Tx#5, Tx#7) is positioned to the right of each transmitting antenna in the first transmitting antenna group (e.g., Tx#2, Tx#4, Tx#6, Tx#8). H They are positioned offset from each other. Also, in Figure 29, in the receiving array antenna, each receiving antenna in the second receiving antenna group (e.g., Rx#2, Rx#5) is positioned to the left of each receiving antenna in the first receiving antenna group (e.g., Rx#3, Rx#6). H They are positioned offset from each other. Also, in Figure 29, each receiving antenna in the third receiving antenna group (for example, Rx#1, Rx#4) is positioned to the left of each receiving antenna in the second receiving antenna group. H They are positioned with an offset.

[0203] For example, in each MIMO array configuration shown in Figures 26 to 29, D H and D VBy setting the value to approximately 0.5λ, the horizontal and vertical element sizes of the transmitting antenna 106 and the receiving antenna 202 can be designed to be 1λ or larger.

[0204] Furthermore, for example, in each virtual receiving array shown in Figures 26 to 29, each virtual array element is arranged in a different position without overlap, which allows for an expansion of the aperture length of the virtual receiving array and an improvement in angular resolution.

[0205] Furthermore, the horizontal position of each transmitting antenna between the first transmitting antenna group and the second transmitting antenna group in the transmitting array antenna is D. H When they are positioned offset, or when the horizontal position of each receiving antenna between the first receiving antenna group and the second receiving antenna group in a receiving array antenna is D H Even when they are offset, the virtual array elements located near the center of the virtual receiving array are D H , D V They can be placed close together at intervals. Also, D H , D V The number of virtual array elements densely arranged at intervals is, for example, N TxGroup_ANT and N RxGroup It increases depending on the situation.

[0206] For example, in a virtual receiving array, in the horizontal direction, (N TxGroup_ANT ×N RxGroup_ANT The virtual array element of )-2 is D H They are spaced apart, and in the vertical direction (N RxGroup ×N TxGroup The virtual array element of )-2 is D V They are arranged at intervals. D is located near the center of the virtual receiving array. H , D V The more densely spaced virtual array elements there are, the better the reduction effect on grating lobes and side lobes can be achieved.

[0207] Also, N TxGroup_ANT The larger N is, the greater the number of virtual array elements arranged horizontally, which in turn expands the aperture length of the horizontal virtual receiving array and improves the horizontal angular resolution. Similarly, N RxGroupThe larger the value, the greater the number of virtual array elements arranged vertically, which allows for an expansion of the aperture length of the vertical virtual receiving array and improves the vertical angular resolution.

[0208] Note that in Figures 28 and 29, the number of receiving antenna groups is N. RxGroup When the number of receiving antennas is 3 or greater, this indicates a case where the horizontal position of each receiving antenna in each receiving antenna group is shifted in a certain direction (right or left). However, the direction in which the horizontal position of the receiving antennas is shifted is not limited to this. For example, the number of receiving antenna groups N RxGroup If the value is 3 or more, the horizontal position of each receiving antenna included in each receiving antenna group may be shifted to the right or left, and the direction may be made variable for each receiving antenna group.

[0209] Figure 30 shows N TxGroup =2, N TxGroup_ANT =4, N RxGroup =3, N RxGroup_ANT Let = 2, and the horizontal position of each transmitting antenna included in the transmitting antenna group be D H By shifting the position of each receiving antenna in the receiving antenna group, D is the horizontal position of each receiving antenna. H Figure 30 shows examples of the arrangement of the transmitting antenna 106 and receiving antenna 202 in the case of a staggered arrangement, and an example of the arrangement of the virtual receiving array. In Figure 30, each transmitting antenna in the second transmitting antenna group (e.g., Tx#1, Tx#3, Tx#5, Tx#7) is positioned to the left for each transmitting antenna in the first transmitting antenna group (e.g., Tx#2, Tx#4, Tx#6, Tx#8). H They are positioned offset from each other. Also, in Figure 30, in the receiving array antenna, each receiving antenna in the second receiving antenna group (e.g., Rx#2, Rx#5) is positioned to the left of each receiving antenna in the first receiving antenna group (e.g., Rx#3, Rx#6). H They are positioned offset from each other. Also, in Figure 30, each receiving antenna in the third receiving antenna group (for example, Rx#1, Rx#4) is positioned to the right of each receiving antenna in the second receiving antenna group. H They are positioned with an offset.

[0210] Even with the antenna configuration in Figure 30, the virtual array element located near the center of the virtual receiving array is D H , D V They can be placed close together at intervals. Also, D H , D V The number of virtual array elements densely arranged at intervals is, for example, N TxGroup_ANT and N RxGroup It increases depending on (N). For example, in the horizontal direction, TxGroup_ANT ×N RxGroup_ANT The virtual array element of )-2 is D H They are spaced apart, and in the vertical direction (N RxGroup ×N TxGroup The virtual array element of )-2 is D V They are arranged at intervals. D is located near the center of the virtual receiving array. H , D V The more densely spaced virtual array elements there are, the better the reduction effect on grating lobes and side lobes can be.

[0211] (Combination of Variation 3 and Variation 2) Furthermore, variation 3 of basic configuration 1 may be combined with variation 2 of basic configuration 1.

[0212] For example, with respect to the arrangement of the transmitting array antennas according to Modification 2 of Basic Arrangement 1, the horizontal position of each transmitting antenna included in the transmitting antenna group is further defined as D between the transmitting antenna group. H A staggered arrangement is acceptable.

[0213] Similarly, for example, with respect to the receiving array antenna arrangement according to Modification 2 of Basic Arrangement 1, the horizontal position of each receiving antenna included in the receiving antenna group is further defined as D between the receiving antenna group. H A staggered arrangement is acceptable.

[0214] Note that the number of transmitting antenna groups is N. TxGroupIf the number is 3 or more, the horizontal position of each transmitting antenna included in each transmitting antenna group may be shifted in a fixed direction (right or left), or the horizontal position of each transmitting antenna included in each transmitting antenna group may be shifted to the right or left, and the direction may be varied for each transmitting antenna group.

[0215] Figures 31 and 32 show an example of antenna arrangement in a combination of Modification 3 and Modification 2.

[0216] Figure 31 shows N TxGroup =4, N TxGroup_ANT =4, N RxGroup =4, N RxGroup_ANT Set = 2, and the horizontal position of each antenna included in the transmitting antenna group and the receiving antenna group is D. H Figure 31 shows examples of the arrangement of the transmitting antenna 106 and receiving antenna 202 in the case of a staggered arrangement, and an example of the arrangement of the virtual receiving array. In equation (11), D TxGroupV =5D V This is the result.

[0217] In Figure 31, in the transmitting array antenna, each transmitting antenna in the second transmitting antenna group (e.g., Tx3, Tx7, Tx11, Tx15) is directed to the left of each transmitting antenna in the first transmitting antenna group (e.g., Tx4, Tx8, Tx12, Tx16). H They are positioned offset from each other. Also, in Figure 31, each transmitting antenna in the third transmitting antenna group (for example, Tx2, Tx#6, Tx#10, Tx#14) is positioned to the left of each other in relation to each transmitting antenna in the second transmitting antenna group. H They are positioned offset from each other. Also, in Figure 31, each transmitting antenna in the fourth transmitting antenna group (for example, Tx1, Tx#5, Tx#9, Tx#13) is positioned to the left of each other in relation to each transmitting antenna in the third transmitting antenna group. H They are positioned with an offset.

[0218] Furthermore, in Figure 31, in the receiving array antenna, each receiving antenna in the second receiving antenna group (e.g., Rx#3, Rx#7) is directed to the left of each receiving antenna in the first receiving antenna group (e.g., Rx#4, Rx#8). H They are positioned offset from each other. Also, in Figure 31, each receiving antenna in the third receiving antenna group (for example, Rx#2, Rx#6) is positioned to the left of each receiving antenna in the second receiving antenna group. H They are positioned offset from each other. Also, in Figure 31, each receiving antenna in the fourth receiving antenna group (for example, Rx#1, Rx#5) is positioned to the left of each receiving antenna in the third receiving antenna group. H They are positioned with an offset.

[0219] Next, Figure 32 shows N TxGroup =2, N TxGroup_ANT =4, N RxGroup =2, N RxGroup_ANT Let = 4, and set the horizontal position of each antenna included in the transmitting antenna group and the receiving antenna group to D H Figure 32 shows examples of the arrangement of the transmitting antenna 106 and receiving antenna 202 when they are shifted, and an example of the arrangement of the virtual receiving array. In equation (12), D RxGroupH =5D H This is the result.

[0220] In Figure 32, each transmitting antenna in the second transmitting antenna group (e.g., Tx#1, Tx#3, Tx#5, Tx#7) is directed to the left of each transmitting antenna in the first transmitting antenna group (e.g., Tx#2, Tx#4, Tx#6, Tx#8). H They are positioned offset from each other. Also, in Figure 32, in the receiving array antenna, each receiving antenna in the second receiving antenna group (e.g., Rx#1, Rx#3, Rx#5, Rx#7) is positioned to the left of each receiving antenna in the first receiving antenna group (e.g., Rx#2, Rx#4, Rx#6, Rx#8). H They are positioned with an offset.

[0221] For example, in each MIMO array configuration shown in Figures 31 and 32, D H and D V By setting this to approximately 0.5λ, the horizontal and vertical element sizes of the transmitting antenna 106 and the receiving antenna 202 can be made 1λ or larger.

[0222] Furthermore, in each virtual receiving array shown in Figures 31 and 32, for example, each virtual array element is arranged in a different position without overlapping, which allows for an expansion of the aperture length of the virtual receiving array and an improvement in angular resolution.

[0223] Furthermore, the virtual array element located near the center of the virtual receiving array shown in Figures 31 and 32 is D H , D V They can be placed close together at intervals. Also, D H , D V The number of virtual array elements densely arranged at intervals is, for example, N TxGroup , N TxGroup_ANT , N RxGroup and N RxGroup_ANT It increases depending on the situation.

[0224] For example, in the horizontal direction (N TxGroup_ANT ×N RxGroup_ANT The virtual array element of )-2 is D H They are spaced apart, and in the vertical direction, (N RxGroup ×N TxGroup The virtual array element of )-2 is D V They are arranged at intervals. D is located near the center of the virtual receiving array. H , D V The more densely spaced virtual array elements there are, the better the reduction effect on grating lobes and side lobes can be achieved.

[0225] Also, N TxGroup_ANT and N RxGroup_ANT The larger N is, the greater the number of virtual array elements arranged horizontally, which in turn expands the aperture length of the horizontal virtual receiving array and improves the horizontal angular resolution. Similarly, N TxGroup , N RxGroupThe larger the value, the greater the number of virtual array elements arranged vertically, which allows for an expansion of the aperture length of the vertical virtual receiving array and improves the vertical angular resolution.

[0226] Furthermore, Modification 3 of Basic Arrangement 1 is, for example, a combination of arrangement methods A and B in Modification 2 of Basic Arrangement 1 shown in Figure 20, in which the horizontal position of each antenna in the transmitting array antenna and receiving array antenna is set D between the transmitting antenna groups and between the receiving antenna groups. H A staggered arrangement is acceptable.

[0227] Figure 33 shows N TxGroup =4, N TxGroup_ANT =4, N RxGroup =4, N RxGroup_ANT Let = 4, and set the horizontal position of each antenna included in the transmitting antenna group and the receiving antenna group to D H Figure 33 shows examples of the arrangement of the transmitting antenna 106 and receiving antenna 202 in the case of a staggered arrangement, and an example of the arrangement of the virtual receiving array. In equation (11), D TxGroupV =5D V And so, D in equation (12) RxGroupH =5D H This is the result.

[0228] In Figure 33, in the transmitting array antenna, each transmitting antenna in the second transmitting antenna group (e.g., Tx3, Tx7, Tx11, Tx15) is directed to the left of each transmitting antenna in the first transmitting antenna group (e.g., Tx4, Tx8, Tx12, Tx16). H They are positioned offset from each other. Also, in Figure 33, each transmitting antenna in the third transmitting antenna group (e.g., Tx2, Tx#6, Tx#10, Tx#14) is positioned horizontally at the same position as each transmitting antenna in the second transmitting antenna group. Also, in Figure 33, each transmitting antenna in the fourth transmitting antenna group (e.g., Tx1, Tx#5, Tx#9, Tx#13) is positioned to the left of each transmitting antenna in the third transmitting antenna group. H They are positioned with an offset.

[0229] Furthermore, in Figure 33, in the receiving array antenna, each receiving antenna in the second receiving antenna group (e.g., Rx#3, Rx#7, Rx#11, Rx#15) is directed to the left of each receiving antenna in the first receiving antenna group (e.g., Rx#4, Rx#8, Rx#12, Rx#16). H They are positioned offset from each other. Also, in Figure 33, each receiving antenna in the third receiving antenna group (for example, Rx#2, Rx#6, Rx#10, Rx#14) is positioned to the right of each receiving antenna in the second receiving antenna group. H They are positioned offset from each other. Also, in Figure 33, each receiving antenna in the fourth receiving antenna group (for example, Rx#1, Rx#5, Rx#9, Rx#13) is positioned to the left of each other in relation to each receiving antenna in the third receiving antenna group. H They are positioned with an offset.

[0230] This provides the combined effect of the arrangement methods 1-2A and 1-2B in the modified version 2 of the basic arrangement 1, in addition to the effect obtained in modified version 3 of the basic arrangement 1.

[0231] <Basic layout 2> Figure 34 shows an example of the arrangement of the transmitting antenna 106 and receiving antenna 202 in the basic configuration 2, and an example of the arrangement of the virtual receiving array.

[0232] (1) Arrangement of transmitting and receiving antennas In Figure 34, the number of transmitting antennas 106 in the transmitting array antenna is set to Nt = 4 (Tx#1, Tx#2, Tx#3, and Tx#4), and the number of receiving antennas 202 in the receiving array antenna is set to Na = 4 (Rx#1, Rx#2, Rx#3, and Rx#4).

[0233] The transmitting array antenna shown in Figure 34 consists of a "first transmitting antenna group" (Tx#2, Tx#4 in Figure 34) and a "second transmitting antenna group" (Tx#1, Tx#3 in Figure 34). Each transmitting antenna group is positioned identically in the vertical direction, and the antenna spacing in the horizontal direction (lateral direction in Figure 34) is 3D.H It includes two transmitting antenna elements. Furthermore, the vertical distance (vertical direction in Figure 34) between the "first transmitting antenna group" and the "second transmitting antenna group" is, for example, 3D V This is the result.

[0234] Furthermore, the receiving array antenna shown in Figure 34 consists of a "first receiving antenna group" (Rx#2, Rx#4 in Figure 34) and a "second receiving antenna group" (Rx#1, Rx#3 in Figure 34). Each receiving antenna group is identical in position in the vertical direction, and the antenna spacing in the horizontal direction is 2D H It includes two receiving antenna elements. The vertical distance between the "first receiving antenna group" and the "second receiving antenna group" is, for example, 2D V This is the result.

[0235] Thus, in the transmitting and receiving antenna arrangement shown in Figure 34, the transmitting array antenna is composed of multiple transmitting antenna groups, and each of the multiple transmitting antenna groups is, for example, horizontally D H intervals that are integer multiples of (here, 3D H It includes multiple transmitting antennas arranged in a 3D configuration. Furthermore, the group of transmitting antennas is 3D in the vertical direction. V They are arranged at intervals of 3D. In other words, the vertical antenna spacing between transmitting antenna groups (3D in Figure 34) V ) and the horizontal antenna spacing within each transmitting antenna group (3D in Figure 34) H ) is identical to this.

[0236] Furthermore, in the transmitting and receiving antenna arrangement shown in Figure 34, the receiving array antenna is composed of multiple receiving antenna groups, and each of the multiple receiving antenna groups is, for example, D in the horizontal direction. H intervals that are integer multiples of (here, 2D H It includes multiple receiving antennas arranged at intervals of ). Furthermore, the multiple receiving antenna groups are arranged in 2D in the vertical direction. V They are arranged at intervals of 2D. In other words, the horizontal spacing between antennas within each receiving antenna group (2D in Figure 34). H ) and the vertical antenna spacing between receiving antenna groups (2D in Figure 34)H ) is identical to this.

[0237] Furthermore, Figure 34 shows the antenna spacing at the transmitting antenna 106 (in Figure 34, 3D H ) and the antenna spacing at the receiving antenna 202 (2D in Figure 34) H Unlike, for example, the difference is D H Furthermore, Figure 34 shows the 3D spacing at which multiple transmitting antenna groups are arranged. V (D V (Intervals that are integer multiples of the interval) and the spacing at which multiple receiving antenna groups are arranged 2D V (D V The difference between (an integer multiple of) is D V That is the case.

[0238] For example, let's assume that the horizontal direction (side direction) shown in Figure 34 corresponds to the X-axis, and the vertical direction (vertical direction) shown in Figure 34 corresponds to the Y-axis direction.

[0239] In the antenna configuration shown in Figure 34, the position coordinates of the transmitting antenna 106 that constitutes the transmitting array antenna are the position coordinates (X) of the transmitting antenna Tx#1. T_#1 ,Y T_#1 ) is used as the reference point for the position coordinates (X) of the transmitting antenna Tx#2. T_#2 ,Y T_#2 )=(X T_#1 ,Y T_#1 +3D V ), position coordinates (X) of transmitting antenna Tx#3 T_#3 ,Y T_#3 )=(X T_#1 +3D H ,Y T_#1 ), and the position coordinates (X) of the transmitting antenna Tx#4. T_#4 ,Y T_#4 )=(X T_#1 +3D H ,Y T_#1 +3D V ) is expressed as.

[0240] Similarly, the position coordinates of receiving antenna 202, which constitutes the receiving array antenna, are the position coordinates (X) of receiving antenna Rx#1. R_#1 ,Y R_#1) is used as the reference point for the position coordinates (X) of the receiving antenna Rx#2. R_#2 ,Y R_#2 )=(X R_#1 ,Y R_#1 +2D V ), position coordinates (X) of receiving antenna Rx#3 R_#3 ,Y R_#3 )=(X R_#1 +2D H ,Y R_#1 ), and the position coordinates (X) of the receiving antenna Rx#4. R_#4 ,Y R_#4 )=(X R_#1 +2D H ,Y R_#1 +2D V ) is expressed as.

[0241] (2) Arrangement of virtual receiver array The arrangement of the virtual receiving array (virtual antennas VA#1 to VA#16) formed by the transmitting and receiving antenna arrangement shown in Figure 34 above has the following characteristics.

[0242] For example, the arrangement of the transmitting array antenna and the receiving array antenna shown in Figure 34 gives the position coordinates (X) of the virtual receiving array VA#1~VA#16. V_#1 ,Y V_#1 )~(X V_#16 ,Y V_#16 The following applies to each of them. Note that here, VA#1 is represented as the position reference (0,0) of the virtual receive array. (0,0), (0, 3D V ), (3D H , 0), (3D H , 3D V ), (0, 2D V ), (0, 5D V ), (3D H , 2D V ), (3D H , 5D V ), (2D H ,0), (2D H , 3D V ), (5D H , 0), (5D H , 3D V), (2D H , 2D V ), (2D H , 5D V ), (5D H , 2D V ), (5D H , 5D V )

[0243] Thus, in the virtual receiver array arrangement shown in Figure 34, each virtual receiver array element is positioned at a different location without overlap. Therefore, the aperture length of the virtual receiver array can be expanded, the main lobe can be narrowed, and the angular resolution can be improved.

[0244] Furthermore, as shown in Figure 34, the virtual array elements VA#4, VA#7, VA#10, and VA#13 located near the center of the virtual receiving array are positioned horizontally in the D direction. H Spacing, vertically D V They are densely arranged at intervals. For example, in Figure 34, interval D H and interval D V When the value is set to approximately 0.5λ, the virtual array elements VA#4, VA#7, VA#10, and VA#13 are positioned horizontally in the D direction. H = 0.5λ intervals, vertically in the direction D V They are arranged at 0.5λ intervals. This reduces grating lobes, similar to basic arrangement 1 (see, for example, Figure 8).

[0245] Furthermore, for example, in the MIMO array configuration shown in Figure 34, the spacing D H and interval D V If the value is set to approximately 0.5λ, the horizontal and vertical element sizes of the transmitting antenna 106 and the receiving antenna 202 can be designed to be 1λ or larger.

[0246] This allows for, for example, the use of a subarray consisting of four elements, with two planar patch antennas arranged vertically and horizontally, as shown in Figure 9A (where the antenna width W is...). ANT < 2D H Antenna height H ANT <2D VThis can be applied to at least one antenna element of the transmitting array antenna and the receiving array antenna shown in Figure 34.

[0247] In Figure 34, the horizontal antenna spacing in the transmitting array antenna is 3D H The vertical antenna spacing is 3D V Therefore, the antenna spacing (3D) of the transmitting array antenna shown in Figure 34. H and 3D V ) is the antenna spacing (2D) of the receiving array antenna. H and 2D V It is wider than the horizontal antenna spacing (3D) of the transmitting array antenna shown in Figure 34. H ) is the horizontal antenna spacing of the transmitting array antenna in basic configuration 1 (for example, 2D in Figure 8). H It is wider than ).

[0248] Therefore, the transmitting array antenna shown in Figure 34 may have wider vertical and horizontal spacing than the 4-element subarray shown in Figure 9A, for example, an antenna using a 9-element subarray with 3 vertical and 3 horizontal planar patch antennas arranged as a subarray, as shown in Figure 35 (where the antenna width W is...). ANT < 3D H Antenna height H ANT <3D V ) can be applied.

[0249] The direction estimation unit 214 performs direction estimation processing in the horizontal and vertical directions using the received signals of the virtual receiving array obtained from the above-described transmitting and receiving antenna arrangement (see, for example, Figure 34). For example, the virtual receiving array of basic arrangement 2 shown in Figure 34 has a similar configuration to the virtual receiving array of basic arrangement 1 (see, for example, Figure 8), and therefore similar performance can be obtained.

[0250] As described above, by using the MIMO array configuration shown in Figure 34, even if the vertical or horizontal element size of the antennas used in the transmitting and receiving array antennas is about 1λ, the antenna spacing in the virtual receiving array can be arranged to include element spacings of about 0.5λ in the horizontal and vertical directions, thereby reducing grating lobes. Furthermore, as shown in Figure 34, for example, since each virtual array element of the virtual receiving array is arranged without overlap, the aperture length of the virtual receiving array can be expanded, improving the angular resolution.

[0251] Furthermore, the antenna elements used in the transmitting antenna 106 and the receiving antenna 202 can be sub-array antennas with element sizes of at least 1λ in the vertical and horizontal directions. This improves the directional gain of the antennas and enhances the detection performance (e.g., detection distance) of the radar device 10.

[0252] Furthermore, in basic configuration 2, the antenna spacing can be set wider on either the transmitting array antenna or the receiving array antenna (the transmitting array antenna in Figure 34) than on the other. This allows for the application of larger sub-arrays to one of the array antennas, thereby improving the antenna's directional gain.

[0253] <Modification 1 of Basic Arrangement 2> Basic configuration 2 (for example, Figure 34) describes the case where the number of transmitting antennas 106 is 4 elements (Nt=4) and the number of receiving antennas 202 is 4 elements (Na=4). However, the number of transmitting antennas Nt and the number of receiving antennas Na are not limited to these numbers.

[0254] In Modification 1 of Basic Configuration 2, the transmitting array antennas are arranged similarly to Basic Configuration 2 (e.g., Figure 34), for example, with a 3D vertical spacing. V It consists of a first transmitting antenna group and a second transmitting antenna group. Furthermore, as with basic configuration 2, each transmitting antenna group has the same position in the vertical direction, and the antenna spacing in the horizontal direction is 3D H It includes two transmitting antenna elements.

[0255] Furthermore, in Modification 1 of Basic Configuration 2, the receiving array antennas are arranged similarly to Basic Configuration 2, for example, with a vertical spacing of 2D V N RxGroup A group of receiving antennas (for example, from the 1st to the Nth) RxGroup It consists of a group of receiving antennas. Each receiving antenna group is located at the same position vertically, and the antenna spacing is 2D horizontally. H N RxGroup_ANT It includes a number of receiving antenna elements.

[0256] In Modification 1 of Basic Arrangement 2, N RxGroup and N RxGroup_ANT Depending on the value of , it becomes possible to increase the number of antennas in the MIMO array (for example, the number of receiving antennas Na).

[0257] Figure 36 shows N RxGroup =3, N RxGroup_ANT An example of the arrangement of the transmitting antenna 106 and receiving antenna 202, and an example of the arrangement of the virtual receiving array, are shown for the case where = 2.

[0258] Figure 37 shows N RxGroup =2, N RxGroup_ANT An example of the arrangement of the transmitting antenna 106 and receiving antenna 202, and an example of the arrangement of the virtual receiving array, are shown for the case where =3.

[0259] Figure 38 shows N RxGroup =3, N RxGroup_ANT An example of the arrangement of the transmitting antenna 106 and receiving antenna 202, and an example of the arrangement of the virtual receiving array, are shown for the case where = 4.

[0260] Note that in Figures 36, 37, and 38, N TxGroup = 2, N TxGroup_ANT = 2

[0261] In each MIMO array configuration shown in Figures 36, 37, and 38, for example, D H and D VBy setting the value to approximately 0.5λ, the horizontal and vertical element sizes of the transmitting antenna 106 and the receiving antenna 202 can be designed to be approximately 1λ or larger.

[0262] Furthermore, in the virtual receiving arrays shown in Figures 36, 37, and 38, for example, each virtual array element is arranged in a different position without overlap, which allows for an expansion of the aperture length of the virtual receiving array and an improvement in angular resolution.

[0263] Furthermore, the virtual array elements located near the center of each virtual receiving array shown in Figures 36, 37, and 38 are D H , D V They can be placed close together at intervals. Also, D H , D V The number of virtual array elements densely arranged at intervals is N RxGroup and N RxGroup_ANT It increases depending on the situation.

[0264] For example, in a virtual receiving array, in the horizontal direction, (N RxGroup_ANT ×N TxGroup_ANT The virtual array element of )-2 is D H They are spaced apart, and in the vertical direction (N RxGroup ×N TxGroup_ANT The virtual array element of )-2 is D V They are arranged at intervals. D is located near the center of the virtual receiving array. H , D V The more densely spaced virtual array elements there are, the better the reduction effect on grating lobes and side lobes can be achieved.

[0265] Also, N RxGroup_ANT The larger N is, the greater the number of virtual array elements arranged horizontally, which in turn expands the aperture length of the horizontal virtual receiving array and improves the horizontal angular resolution. Similarly, N RxGroup The larger the value, the greater the number of virtual array elements arranged vertically, which allows for an expansion of the aperture length of the vertical virtual receiving array and improves the vertical angular resolution.

[0266] <Modification 2 of Basic Arrangement 2> The following describes the antenna placement methods 2-2A and 2-2B in modified version 2 of the basic configuration 2.

[0267] (Placement method 2-2A) In Modification 1 of Basic Configuration 2, the number of receiving antenna groups included in the receiving array antenna is N. RxGroup We explained the case where the number of virtual array elements arranged vertically is increased by increasing N. RxGroup If ≥ 3 is satisfied, then the number of transmitting antenna groups N in the transmitting array antenna. TxGroup Increasing this value can also increase the number of virtual array elements arranged vertically in the virtual receiver array.

[0268] In this case, the vertical antenna spacing of the transmitting antenna group is set to a constant value (e.g., 3D V ) may be used, but the number of receiving antenna groups N RxGroup Depending on this, the virtual receiver array configuration may result in an arrangement where virtual array elements overlap.

[0269] Therefore, in order to ensure that the virtual receiver array arrangement does not contain any overlapping virtual array elements, for example, the following spacing D can be added to the even-numbered antenna spacings in the vertical direction of the transmitting antenna group. TxGroupV2 You may use this.

number

[0270] For example, N RxGroup If =3, D TxGroupV2 =3D V N RxGroup If =4, D TxGroupV2 =5D H This is the result.

[0271] For example, the number of transmitting antennas N TxGroup If =3, the spacing between the three transmitting antenna groups is {3D V , D TxGroupV2 Let's assume the number of transmitting antenna groups is N. TxGroupIf =4, the spacing between the four transmitting antenna groups is {3D V , D TxGroupV2 , 3D V Let's assume the number of transmitting antenna groups is N. RxGroup_ANT If = 5, the spacing between the 5 transmitting antenna groups is {3D V , D TxGroupV2 , 3D V , D TxGroupV2 Let's assume that.

[0272] Figure 39 shows N TxGroup =4, N TxGroup_ANT =2, N RxGroup =3, N RxGroup_ANT Figure 39 shows an example of the arrangement of the transmitting antenna 106 and the receiving antenna 202 when = 2, and an example of the arrangement of the virtual receiving array. TxGroupV2 =3D V This is the result.

[0273] Also, Figure 40 shows N TxGroup =4, N TxGroup_ANT =2, N RxGroup =4, N RxGroup_ANT The following shows an example of the arrangement of the transmitting antenna 106 and the receiving antenna 202, and an example of the arrangement of the virtual receiving array, when = 2. In Figure 40, D in equation (13) TxGroupV2 =5D V This is the result.

[0274] Note that there are unequal intervals (for example, D) near the center of the virtual receiving array. H and D V If arrangements with a larger spacing than D are allowed, TxGroupV2 This value may be greater than the value in equation (13).

[0275] <Placement method 2-2B> In variation 1 of notation arrangement 2, the number of receiving antennas N is the number of receiving antennas included in each receiving antenna group of the receiving array antenna. RxGroup_ANT We explained the case where the number of virtual array elements arranged horizontally is increased by increasing N. RxGroup_ANT If ≥ 3 is satisfied, then in a transmitting array antenna, the number of transmitting antennas included in the transmitting antenna group is N. TxGroup_ANTIncreasing this value can also increase the number of virtual array elements arranged horizontally in the virtual receiver array.

[0276] In this case, the horizontal spacing between the receiving antennas is set to a constant value (e.g., 3D H ) may be used, but the number of receiving antennas included in the receiving antenna group is N. RxGroup_ANT Depending on this, the virtual array configuration may result in an arrangement where virtual array elements overlap.

[0277] Therefore, in order to ensure that the virtual receiver array configuration does not include any overlapping virtual array elements, for example, the following spacing may be used for the even-numbered spacings in the horizontal direction of the transmitting antennas included in the transmitting antenna group.

number

[0278] For example, N RxGroup_ANT If =3, D TxAntH =3D H N RxGroup_ANT If =4, D TxAntH =5D H This is the result.

[0279] For example, the number of transmitting antennas in a transmitting antenna group N TxGroup_ANT If =3, the antenna spacing of the three transmitting antennas is {3D H , D TxAntH Let's assume}. Also, the number of transmitting antennas N TxGroup_ANT If =4, the antenna spacing of the 4 transmitting antennas is {3D H , D TxAntH , 3D H Let's assume the number of transmitting antennas is N. TxGroup_ANT If = 5, the antenna spacing of the 5 transmitting antennas is {3D H , D TxAntH , 3D H , D TxAntH Let's assume that.

[0280] Figure 41 shows N TxGroup =2, NTxGroup_ANT =4, N RxGroup =2, N RxGroup_ANT Figure 41 shows an example of the arrangement of the transmitting antenna 106 and receiving antenna 202, and an example of the arrangement of the virtual receiving array, when D = 3. TxAntH =3D H This is the result.

[0281] Figure 42 shows N TxGroup =2, N TxGroup_ANT =4, N RxGroup =2, N RxGroup_ANT Figure 41 shows an example of the arrangement of the transmitting antenna 106 and receiving antenna 202, and an example of the arrangement of the virtual receiving array, when D = 4. TxAntH =5D H This is the result.

[0282] Note that there are unequal intervals (for example, D) near the center of the virtual receiving array. H and D V If arrangements with a larger spacing than D are allowed, TxAntH This value may be greater than the value in equation (14).

[0283] The above describes the arrangement methods 2-2A and 2-2B in the modified version 2 of the basic arrangement 2.

[0284] For example, in the transmit / receive antenna configuration shown in Figures 39 to 42 (e.g., MIMO array configuration), D H and D V By setting the value to approximately 0.5λ, the horizontal and vertical element sizes of the transmitting antenna 106 and the receiving antenna 202 can be designed to be approximately 1λ or larger.

[0285] Furthermore, for example, in each virtual receiving array shown in Figures 39 to 42, each virtual array element is arranged in a different position without overlap, so the aperture length of the virtual receiving array can be expanded and the angular resolution can be improved.

[0286] Furthermore, for example, a virtual array element located near the center of the virtual receiving array shown in Figures 39 to 42 is D H , DV They can be placed close together at intervals. Also, D H , D V The number of virtual array elements densely arranged at intervals is N TxGroup , N TxGroup_ANT , N RxGroup and N RxGroup_ANT It increases depending on the situation.

[0287] For example, in a virtual receiving array, in the horizontal direction, (N RxGroup_ANT ×N TxGroup_ANT The virtual array element of )-2 is D H They are spaced apart, and in the vertical direction (N RxGroup ×N TxGroup The virtual array element of )-2 is D V They are arranged at intervals. D is located near the center of the virtual receiving array. H , D V The more densely spaced virtual array elements there are, the better the reduction effect on grating lobes and side lobes can be.

[0288] Also, N TxGroup_ANT , N RxGroup_ANT The larger N is, the greater the number of virtual array elements arranged horizontally, which in turn expands the aperture length of the horizontal virtual receiving array and improves the horizontal angular resolution. Similarly, N TxGroup , N RxGroup The larger the value, the greater the number of virtual array elements arranged vertically, which allows for an expansion of the aperture length of the vertical virtual receiving array and improves the vertical angular resolution.

[0289] Furthermore, in the modified example 2 of the basic arrangement 2, an arrangement combining arrangement methods 2-2A and 2-2B is also possible. Figure 43 shows N TxGroup =4, N TxGroup_ANT =4, N RxGroup =4, N RxGroup_ANT Figure 43 shows an example of the arrangement of the transmitting antenna 106 and receiving antenna 202 for equation (13) = 4, and an example of the arrangement of the virtual receiving array. TxGroupV2 =5D H And so, D in equation (14) TxAntH =5D HThis results in the combined effect of arrangement methods 2-2A and 2-2B.

[0290] <Modification 3 of Basic Arrangement 2> The following describes the antenna placement methods 2-3A, 2-3B, and 2-3C in modified example 3 of basic configuration 2.

[0291] (Placement method 2-3A) Basic configuration 2 described the case where the horizontal positions of the transmitting antennas included in each transmitting antenna group are the same in a transmitting array antenna. However, the case is not limited to this, and the horizontal positions of the transmitting antennas included in each transmitting antenna group may differ.

[0292] For example, in a transmitting array antenna, each transmitting antenna included in the first transmitting antenna group and the second transmitting antenna group, respectively, has a horizontal position D H They may be positioned with a slight offset (in other words, shifted).

[0293] D in the horizontal direction H The direction of the shift may be either to the right or to the left for each transmitting antenna in the second transmitting antenna group relative to each transmitting antenna in the first transmitting antenna group.

[0294] Figure 44 shows a transmitting array antenna where each transmitting antenna in the second transmitting antenna group (e.g., Tx#1, Tx#3) is positioned to the right relative to each transmitting antenna in the first transmitting antenna group (e.g., Tx#2, Tx#4). H Examples of the arrangement of the transmitting antenna 106 and receiving antenna 202 when they are shifted, and an example of the arrangement of the virtual receiving array are shown.

[0295] In Figure 44, the horizontal positions of Tx#1 and Tx#2 are D H They are different. Also, the horizontal positions of Tx#3 and Tx#4 are D H different.

[0296] (Placement method 2-3B) Basic configuration 2 described the case where the horizontal positions of the receiving antennas included in each receiving antenna group are the same in a receiving array antenna. However, the case is not limited to this, and the horizontal positions of the receiving antennas included in each receiving antenna group may differ between each receiving antenna group.

[0297] For example, in a receiving array antenna, each receiving antenna included in the first receiving antenna group and the second receiving antenna group, respectively, has a horizontal position D H They may be placed at an angle.

[0298] D in the horizontal direction H The direction of the shift may be either to the right or to the left for each receiving antenna in the second receiving antenna group relative to each receiving antenna in the first receiving antenna group.

[0299] Figure 45 shows a receiving array antenna in which each receiving antenna in the second receiving antenna group (e.g., Rx#1, Rx#3) is positioned to the left relative to each receiving antenna in the first receiving antenna group (e.g., Rx#2, Rx#4). H Examples of the arrangement of the transmitting antenna 106 and receiving antenna 202 when they are shifted, and an example of the arrangement of the virtual receiving array are shown.

[0300] In Figure 45, the horizontal positions of Rx#1 and Rx#2 are D H They are different. Also, the horizontal positions of Rx#3 and Rx#4 are D H different.

[0301] (Placement method 2-3C) Arrangement method 2-3C is a combination of arrangement methods 2-3A and 2-3B.

[0302] For example, in a transmitting array antenna, the transmitting antennas between the first transmitting antenna group and the second transmitting antenna group are positioned horizontally at D HThey are positioned offset from each other. Similarly, in a receiving array antenna, the receiving antennas between the first receiving antenna group and the second receiving antenna group are positioned horizontally at a distance D H They are positioned with an offset.

[0303] Note that D in the horizontal direction H The direction of the shift can be, for example, to the right or left of each transmitting antenna in the second transmitting antenna group relative to each transmitting antenna in the first transmitting antenna group. Also, the horizontal direction D H The direction of the shift may be, for example, to the right or left of each receiving antenna in the second receiving antenna group relative to each receiving antenna in the first receiving antenna group.

[0304] Figure 46 shows an example of the arrangement of the transmitting antenna 106 and receiving antenna 202 according to arrangement method 2-3C, and an example of the arrangement of the virtual receiving array. In Figure 46, in the transmitting array antenna, each transmitting antenna (e.g., Tx#1, Tx#3) included in the second transmitting antenna group is positioned to the right of each transmitting antenna (e.g., Tx#2, Tx#4) included in the first transmitting antenna group. H They are positioned with a staggered arrangement. Also, in Figure 46, in the receiving array antenna, each receiving antenna in the second receiving antenna group (e.g., Rx#1, Rx#3) is positioned to the right of each receiving antenna in the first receiving antenna group (e.g., Rx#2, Rx#4). H They are positioned with an offset.

[0305] Figure 47 shows an example of the arrangement of the transmitting antenna 106 and receiving antenna 202 according to arrangement method 2-3C, and an example of the arrangement of the virtual receiving array. In Figure 47, in the transmitting array antenna, each transmitting antenna (e.g., Tx#1, Tx#3) included in the second transmitting antenna group is positioned to the right of each transmitting antenna (e.g., Tx#2, Tx#4) included in the first transmitting antenna group. HThey are positioned offset from each other. Also, in Figure 47, in the receiving array antenna, each receiving antenna in the second receiving antenna group (e.g., Rx#1, Rx#3) is positioned to the left of each receiving antenna in the first receiving antenna group (e.g., Rx#2, Rx#4). H They are positioned with an offset.

[0306] For example, between the receiving antenna group and the transmitting antenna group, the horizontal direction is D H Compared to an arrangement where the shifting direction is different (for example, Figure 47), the receiving antenna group and the transmitting antenna group have a horizontal D H An arrangement where the shifting direction is the same (for example, Figure 46) is more preferable because the virtual receiver array elements are more densely arranged near the center of the virtual receiver array arrangement.

[0307] The above explains the arrangement methods 2-3A to 2-3C.

[0308] For example, in the transmit / receive antenna configuration shown in Figures 45 to 47 (e.g., MIMO array configuration), D H and D V By setting the value to approximately 0.5λ, the horizontal and vertical element sizes of the transmitting antenna 106 and the receiving antenna 202 can be designed to be approximately 1λ in size.

[0309] As a result, in Modification 3 of Basic Arrangement 1, for example, an antenna is used in which four elements are arranged in a subarray by arranging two planar patch antennas vertically and horizontally, as shown in Figure 9A (where the antenna width W ANT < 2D H Antenna height H ANT <2D V ) can be applied (not shown).

[0310] Furthermore, the transmitting array antennas shown in Figures 45 to 47 may include, for example, an antenna with a wider vertical and horizontal spacing than the 4-element subarray shown in Figure 9A, using a subarray of 9 elements, where 3 planar patch antennas are arranged vertically and 3 horizontally (where the antenna width W is...). ANT < 3D H Antenna height HANT <3D V ) can be applied.

[0311] Furthermore, in Modification 3 of Basic Arrangement 2, the horizontal positions of the transmitting antennas included in each transmitting antenna group or the receiving antennas included in each receiving antenna group are different from each other in at least one of the transmitting array antenna and receiving array antenna. Therefore, in Modification 3 of Basic Arrangement 2, the lateral W of the subarray is different. ANT The element size is D H If it is smaller than this, the vertical element size of the subarray can be any size. For example, in each transmitting array antenna in Figures 45 to 47, a subarray consisting of eight vertical and one horizontal planar patch antennas as shown in Figure 25A may be used.

[0312] (A combination of Variation 3 and Variation 1 or Variation 2) Furthermore, Modification 3 of Basic Configuration 2 may be combined with Modification 1 or Modification 2 of Basic Configuration 2.

[0313] For example, with respect to the arrangement of the transmitting array antenna according to Modification 1 or Modification 2 of the basic arrangement 2, the horizontal position of each transmitting antenna included in the transmitting antenna group is further defined as D between the transmitting antenna group. H A staggered arrangement is acceptable.

[0314] Similarly, for example, with respect to the receiving array antenna arrangement according to Modification 1 or Modification 2 of the basic arrangement 2, the horizontal position of each receiving antenna included in the receiving antenna group is further defined as D between the receiving antenna group. H A staggered arrangement is acceptable.

[0315] Figures 48, 49, 50A, 50B, 51A, and 51B show an example of antenna arrangement in combination with Modification 3 and Modification 2.

[0316] Figure 48 shows N TxGroup =4, N TxGroup_ANT =4, N RxGroup =4, N RxGroup_ANTLet = 4, and the horizontal position of each antenna included in the transmitting antenna group be D H Figure 48 shows examples of the arrangement of the transmitting antenna 106 and receiving antenna 202 in the case of a staggered arrangement, and an example of the arrangement of the virtual receiving array. In equation (13), D TxGroupV2 =5D H And so, D in equation (14) TxAntH =5D H This is the result.

[0317] Figure 49 shows N TxGroup =4, N TxGroup_ANT =4, N RxGroup =4, N RxGroup_ANT Let = 4, and the horizontal position of each antenna included in the receiving antenna group be D H Figure 49 shows examples of the arrangement of the transmitting antenna 106 and receiving antenna 202 in the case of a staggered arrangement, and an example of the arrangement of the virtual receiving array. In equation (13), D TxGroupV2 =5D H And so, D in equation (14) TxAntH =5D H This is the result.

[0318] In Figure 49, in the receiving array antenna, each receiving antenna in the second receiving antenna group (e.g., Rx3, Rx7, Rx11, Rx15) is directed to the left of each receiving antenna in the first receiving antenna group (e.g., Rx4, Rx8, Rx12, Rx16). H They are positioned offset from each other. Also, in Figure 49, each receiving antenna in the third receiving antenna group (for example, Rx2, Rx#6, Rx#10, Rx#14) is positioned to the right of each receiving antenna in the second receiving antenna group. H They are positioned offset from each other. Also, in Figure 49, each receiving antenna in the fourth receiving antenna group (for example, Rx1, Rx#5, Rx#9, Rx#13) is positioned to the left of each receiving antenna in the third receiving antenna group. H They are positioned with an offset.

[0319] Figure 50A shows N TxGroup =4, N TxGroup_ANT =4, N RxGroup=4, N RxGroup_ANT Let = 4, and set the horizontal position of each antenna included in the transmitting antenna group and the receiving antenna group to D H Figure 50A shows an example of the arrangement of the transmitting antenna 106 and receiving antenna 202 in the case of a staggered arrangement, and Figure 50B shows an example of the arrangement of the virtual receiving array. In Figure 50A, D of equation (13) TxGroupV2 =5D H And so, D in equation (14) TxAntH =5D H This is the result.

[0320] In Figure 50A, in the transmitting array antenna, each transmitting antenna in the second transmitting antenna group (e.g., Tx3, Tx7, Tx11, Tx15) is directed to the left of each transmitting antenna in the first transmitting antenna group (e.g., Tx4, Tx8, Tx12, Tx16). H They are positioned offset from each other. Also, in Figure 50A, each transmitting antenna in the third transmitting antenna group (for example, Tx2, Tx#6, Tx#10, Tx#14) is positioned to the left of each other in relation to each transmitting antenna in the second transmitting antenna group. H They are positioned offset from each other. Also, in Figure 50A, each transmitting antenna in the fourth transmitting antenna group (for example, Tx1, Tx#5, Tx#9, Tx#13) is positioned to the left of each other in relation to each transmitting antenna in the third transmitting antenna group. H They are positioned with an offset.

[0321] Furthermore, in Figure 50A, in the receiving array antenna, each receiving antenna in the second receiving antenna group (e.g., Rx#3, Rx#7, Rx#11, Rx#15) is directed to the right of each receiving antenna in the first receiving antenna group (e.g., Rx#4, Rx#8, Rx#12, Rx#16). H They are positioned offset from each other. Also, in Figure 50A, each receiving antenna in the third receiving antenna group (for example, Rx#2, Rx#6, Rx#10, Rx#14) is positioned to the right of each receiving antenna in the second receiving antenna group. HThey are positioned offset from each other. Also, in Figure 50A, each receiving antenna in the fourth receiving antenna group (for example, Rx#1, Rx#5, Rx#9, Rx#13) is positioned to the right of each receiving antenna in the third receiving antenna group. H They are positioned with an offset.

[0322] Figure 51A shows N TxGroup =4, N TxGroup_ANT =4, N RxGroup =4, N RxGroup_ANT Let = 4, and set the horizontal position of each antenna included in the transmitting antenna group and the receiving antenna group to D H Figure 50A shows an example of the arrangement of the transmitting antenna 106 and receiving antenna 202 in the case of a staggered arrangement, and Figure 51B shows an example of the arrangement of the virtual receiving array. In Figure 50A, D of equation (13) TxGroupV2 =5D H And so, D in equation (14) TxAntH =5D H This is the result.

[0323] In Figure 51A, in the transmitting array antenna, each transmitting antenna in the second transmitting antenna group (e.g., Tx3, Tx7, Tx11, Tx15) is directed to the left of each transmitting antenna in the first transmitting antenna group (e.g., Tx4, Tx8, Tx12, Tx16). H They are positioned offset from each other. Also, in Figure 51A, each transmitting antenna in the third transmitting antenna group (for example, Tx2, Tx#6, Tx#10, Tx#14) is positioned to the right of each other in the first transmitting antenna group. H They are positioned offset from each other. Also, in Figure 51A, each transmitting antenna in the fourth transmitting antenna group (for example, Tx1, Tx#5, Tx#9, Tx#13) is positioned to the left of each other in relation to each transmitting antenna in the third transmitting antenna group. H They are positioned with an offset.

[0324] Furthermore, in Figure 51A, in the receiving array antenna, each receiving antenna in the second receiving antenna group (e.g., Rx#3, Rx#7, Rx#11, Rx#15) is directed to the left of each receiving antenna in the first receiving antenna group (e.g., Rx#4, Rx#8, Rx#12, Rx#16). H They are positioned offset from each other. Also, in Figure 51A, each receiving antenna in the third receiving antenna group (for example, Rx#2, Rx#6, Rx#10, Rx#14) is positioned to the right of each receiving antenna in the second receiving antenna group. H They are positioned offset from each other. Also, in Figure 51A, each receiving antenna in the fourth receiving antenna group (for example, Rx#1, Rx#5, Rx#9, Rx#13) is positioned to the left of each other in relation to each receiving antenna in the third receiving antenna group. H They are positioned with an offset.

[0325] For example, in each MIMO array configuration shown in Figures 48, 49, 50A, and 51A, D H and D V By setting the value to approximately 0.5λ, the horizontal and vertical element sizes of the transmitting antenna 106 and the receiving antenna 202 can be designed to be 1λ or larger.

[0326] Furthermore, in the virtual receiving arrays shown in Figures 48, 49, 50B, and 51B, for example, each virtual array element is arranged in a different position without overlap, which allows for an expansion of the aperture length of the virtual receiving array and an improvement in angular resolution.

[0327] Note that the number of transmitting antenna groups is N. TxGroup If the number of receiving antennas is 3 or more, the horizontal position of each transmitting antenna in each transmitting antenna group may be shifted in a fixed direction (right or left), or the horizontal position of each transmitting antenna in each transmitting antenna group may not be shifted to the right or left, and the direction may be varied for each transmitting antenna group. Similarly, the number of receiving antenna groups N RxGroupWhen it is 3 or more, the horizontal positions of the respective receiving antennas included in each receiving antenna group may be shifted in a fixed direction (right or left direction) for arrangement, or the direction may be variably set for each receiving antenna group without shifting the horizontal positions of the respective receiving antennas included in each receiving antenna group to the right or left direction.

[0328] In any antenna arrangement, virtual array elements located near the center of the virtual receiving array are arranged densely at intervals of D H , D V . Also, the number of virtual array elements arranged densely at intervals of D H , D V increases depending on, for example, N TxGroup , N TxGroup_ANT , N RxGroup and N RxGroup_ANT .

[0329] [[ID=2,4]]For example, in the horizontal direction, (N TxGroup_ANT ×N RxGroup_ANT ) - 2 virtual array elements are arranged at intervals of D H , and in the vertical direction, (N RxGroup ×N TxGroup ) - 2 virtual array elements are arranged at intervals of D V . The closer the virtual array elements are arranged densely at intervals of D H , D V near the center of the virtual receiving array, the more the reduction effect of grating lobes and side lobes can be improved.

[0330] Also, the larger N TxGroup_ANT and N RxGroup_ANT are, the larger the number of virtual array elements arranged horizontally, so the aperture length of the virtual receiving array in the horizontal direction can be expanded and the angular resolution in the horizontal direction can be improved. Similarly, the larger N TxGroup , N RxGroup are, the larger the number of virtual array elements arranged vertically, so the aperture length of the virtual receiving array in the vertical direction can be expanded and the angular resolution in the vertical direction can be improved.

[0331] <Basic Arrangement 3> Figures 52A to D show examples of the arrangement of the transmitting antenna 106 and receiving antenna 202 in the basic configuration 3, and examples of the arrangement of the virtual receiving array.

[0332] (1) Arrangement of transmitting and receiving antennas In Figures 52A to D, the number of transmitting antennas 106 in the transmitting array antenna is set to Nt = 4 (Tx#1, Tx#2, Tx#3 and Tx#4), and the number of receiving antennas 202 in the receiving array antenna is set to Na = 4 (Rx#1, Rx#2, Rx#3 and Rx#4).

[0333] The transmitting array antenna shown in Figures 52A-D consists of a "first transmitting antenna group" (Tx#2, Tx#4 in Figures 52A-D) and a "second transmitting antenna group" (Tx#1, Tx#3 in Figures 52A-D). Each transmitting antenna group is positioned identically in the vertical direction, and the antenna spacing in the horizontal direction (lateral direction in Figures 52A-D) is 2D. H It includes two transmitting antenna elements. Also, the vertical distance (vertical direction in Figures 52A-D) between the "first transmitting antenna group" and the "second transmitting antenna group" is, for example, 2D V This is the result.

[0334] Furthermore, in Figures 52A to D, the horizontal position of each transmitting antenna included in the first transmitting antenna group and the second transmitting antenna group is D H They will be in different, offset positions. For example, the horizontal position of each transmitting antenna in the second transmitting antenna group will be +D to the horizontal position of the transmitting antennas in the first transmitting antenna group. H Shifted arrangement or -D H The arrangement is staggered.

[0335] Furthermore, the receiving array antenna shown in Figures 52A-D consists of a "first receiving antenna group" (Rx#1, Rx#2 in Figures 52A-D) and a "second receiving antenna group" (Rx#3, Rx#4 in Figures 52A-D). Each receiving antenna group is identical in position horizontally, and the antenna spacing in the vertical direction is 2D VIt includes two receiving antenna elements. Also, the horizontal distance between the "first receiving antenna group" and the "second receiving antenna group" is, for example, 2D H This is the result.

[0336] Furthermore, in Figures 52A to D, the vertical position of each receiving antenna included in the first receiving antenna group and the second receiving antenna group is D V They will be in different, offset positions. For example, the vertical position of each receiving antenna in the second receiving antenna group will be +D compared to the vertical position of the receiving antenna in the first receiving antenna group. V Shifted arrangement or -D V The arrangement is staggered.

[0337] For example, in the transmitting and receiving antenna arrangements shown in Figures 52A and 52C, the positions of each transmitting antenna included in the transmitting array antenna and the positions of each receiving antenna included in the receiving array antenna are related by a rotation of, for example, +90° or -90° in a two-dimensional plane composed of the horizontal and vertical directions.

[0338] Furthermore, in the transmitting and receiving antenna arrangements shown in Figures 52B and 52D, the respective positions of the transmitting antennas included in the transmitting array antenna and the respective positions of the receiving antennas included in the receiving array antenna are related by being rotated, for example, +90° or -90° and inverted in a two-dimensional plane composed of the horizontal and vertical directions.

[0339] Note that ΔH is the amount of horizontal displacement of the second transmitting antenna group relative to the first transmitting antenna group. Tx Two types of combinations (+D H ,-D H ), and the vertical displacement ΔV of the second receiving antenna group relative to the first receiving antenna group. Rx Two types of combinations (+D V ,-D V ) can be any combination. Here, for example, in Figures 52A to D, +D H The direction is to the right, -D HThe direction is left. Also, in Figures 52A to D, +D V The direction is upward, -D V The direction is downward.

[0340] For example, four types of combination configurations (ΔH Tx , ΔV Rx )=(+D H , +D V ), (+D H ,-D V ), (-D H , +D V ), (D H ,-D V Any combination of ) is acceptable. As an example, Figures 52A to D show (ΔH Tx , ΔV Rx )=(-D H ,-D V ), (-D H , +D V ), (+D H , +D V ), (+D H ,-D V The MIMO array configuration and virtual receive array configuration for the case shown are indicated below.

[0341] The virtual receiving array configurations obtained by the MIMO array configurations for each antenna group displacement shown in Figures 52A to D are rotationally symmetrical, and similar angular measurement performance characteristics are obtained.

[0342] For example, let's assume that the horizontal direction (side direction) shown in Figure 52A corresponds to the X-axis, and the vertical direction (vertical direction) shown in Figure 52A corresponds to the Y-axis direction.

[0343] For example, in the antenna configuration shown in Figure 52A, the position coordinates of the transmitting antenna 106 that constitutes the transmitting array antenna are the position coordinates (X) of the transmitting antenna Tx#1. T_#1 ,Y T_#1 ) is used as the reference point for the position coordinates (X) of the transmitting antenna Tx#2. T_#2 ,Y T_#2 )=(X T_#1 +D H ,Y T_#1 +2D V) Coordinates of the position of transmission antenna Tx#3 (X T_#3 , Y T_#3 ) = (X T_#1 + 2D H , Y T_#1 ) and the coordinates of the position of transmission antenna Tx#4 (X T_#4 , Y T_#4 ) = (X T_#1 + 3D H , Y T_#1 + 2D V ) are represented as follows.

[0344] Similarly, the coordinates of the position of reception antenna 202 that constitutes the reception array antenna are based on the coordinates of the position of reception antenna Rx#1 (X R_#1 , Y R_#1 ). The coordinates of the position of reception antenna Rx#2 (X R_#2 , Y R_#2 ) = (X R_#1 , Y R_#1 + 2D V ), the coordinates of the position of reception antenna Rx#3 (X R_#3 , Y R_#3 ) = (X R_#1 + 2D H , Y R_#1 - D V ), and the coordinates of the position of reception antenna Rx#4 (X R_#4 , Y R_#4 ) = (X R_#1 + 2D H , Y R_#1 + D V ) are represented as follows.

[0345] (2) Arrangement of virtual reception array The arrangement of the virtual reception array (virtual antennas VA#1 to VA#16) configured by the transmission and reception antenna arrangements shown in FIGS. 52A to D described above has the following characteristics.

[0346] For example, based on the arrangement of the transmission array antenna and the reception array antenna shown in FIG. 52A, the position coordinates (X V_#1 , Y V_#1 ) to (X V_#16 , Y V_#16The following applies to each of them. Note that here, VA#1 is represented as the position reference (0,0) of the virtual receive array. (0,0), (D H , 2D V ), (2D H , 0), (3D H , 2D V ), (0, 2D V ), (D H , 4D V ), (2D H , 2D V ), (3D H , 4 V ), (2D H , - D V ), (3D H , D V ), (4D H , - D V ), (5D H , D V ), (2D H , D V ), (3D H , 3D V ), (4D H , D V ), (5D H , 3D V )

[0347] Thus, in the virtual receiver array arrangement shown in Figures 52A to D, each virtual receiver array element is positioned at a different location without overlap. Therefore, the aperture length of the virtual receiver array can be expanded, the main lobe can be narrowed, and the angular resolution can be improved.

[0348] Furthermore, the virtual array elements VA#4, VA#7, VA#10, and VA#13, located near the center of the virtual receiving array shown in Figures 52A-D, are positioned horizontally in the D direction. H Spacing, vertically D V They are densely arranged at intervals. For example, in Figures 52A to D, the interval D H and interval D V If we set the value to approximately 0.5λ, the virtual array element located near the center of the virtual receiving array will have a horizontal dimension of D H= 0.5λ intervals, vertically in the direction D V They are arranged at 0.5λ intervals. This reduces grating lobes, similar to basic arrangement 1 (see, for example, Figure 8).

[0349] Furthermore, for example, in the MIMO array configuration shown in Figures 52A-D, the interval D H and interval D V If the value is set to approximately 0.5λ, the horizontal and vertical element sizes of the transmitting antenna 106 and the receiving antenna 202 can be designed to be 1λ or larger.

[0350] This allows for, for example, the use of a subarray consisting of four elements, with two planar patch antennas arranged vertically and horizontally, as shown in Figure 9A (where the antenna width W is...). ANT < 2D H Antenna height H ANT <2D V This can be applied to at least one antenna of the transmitting array antenna and receiving array antenna shown in Figures 52A to D.

[0351] Note that the number of transmitting antennas included in the first transmitting antenna group (hereinafter referred to as "N") TxHGroup1_ANT (represented as "N") and the number of transmitting antennas included in the second transmitting antenna group (hereinafter referred to as "N") TxHGroup2_ANT (represented as ") may have the same number or a difference of one antenna. For example, |N TxHGroup1_ANT -N TxHGroup2_ANT Let |= 0 or 1.

[0352] Similarly, the number of receiving antennas included in the first receiving antenna group (hereinafter referred to as "N") RxVGroup1_ANT (represented as "N") and the number of receiving antennas included in the second receiving antenna group (hereinafter referred to as "N") RxVGroup2_ANT (represented as ") may have the same number or a difference of one antenna. For example, |N RxVGroup1_ANT -N RxVGroup2_ANT Let |= 0 or 1.

[0353] Figures 53A-D show the number of transmitting antennas N included in the first transmitting antenna group. TxHGroup1_ANT and the number of transmitting antennas N included in the second group of transmitting antennasTxHGroup2_ANT There is a difference of one antenna between the two, and the number of receiving antennas included in the first receiving antenna group is N. RxVGroup1_ANT The number of receiving antennas N included in the second receiving antenna group. RxVGroup2_ANT This shows an example configuration that minimizes the number of MIMO array antennas when the number of and are equal.

[0354] As shown in Figures 53A to D, |N TxHGroup1_ANT -N TxHGroup2_ANT |=1 and |N RxVGroup1_ANT -N RxVGroup2_ANT The configuration that minimizes the number of MIMO array antennas when |=0 is one in which the number of transmitting antennas is 3 and the number of receiving antennas is 4(N RxVGroup1_ANT =N RxVGroup2_ANT The configuration is such that =2), and for example, there are four possible patterns as shown in Figures 53A to D.

[0355] Figure 53A shows N TxHGroup1_ANT =1(Tx#2), N TxHGroup2_ANT =2(Tx#1,Tx#3), (ΔH Tx , ΔV Rx )=(-D H ,-D V Examples of MIMO array configurations and virtual receiver array configurations for the case shown are provided.

[0356] Figure 53B shows N TxHGroup1_ANT =1(Tx#2), N TxHGroup2_ANT =2(Tx#1,Tx#3), (ΔH Tx , ΔV Rx )=(-D H , +D V Examples of MIMO array configurations and virtual receiver array configurations for the case shown are provided.

[0357] Figure 53C shows N TxHGroup1_ANT =2(Tx#2,Tx#3), N TxHGroup2_ANT =1(Tx#1), ​​(ΔH Tx , ΔV Rx )=(+D H ,-D V Examples of MIMO array configurations and virtual receiver array configurations for the case shown are provided.

[0358] Figure 53D shows NTxHGroup1_ANT =2(Tx#2,Tx#3), N TxHGroup2_ANT =1(Tx#1), ​​(ΔH Tx , ΔV Rx )=(+D H , +D V Examples of MIMO array configurations and virtual receiver array configurations for the case shown are provided.

[0359] Figures 54A-D show the number of transmitting antennas N included in the first transmitting antenna group. TxHGroup1_ANT and the number of transmitting antennas N included in the second group of transmitting antennas TxHGroup2_ANT The number of and are equal, and the number of receiving antennas included in the first receiving antenna group is N. RxVGroup1_ANT The number of receiving antennas N included in the second receiving antenna group. RxVGroup2_ANT This example shows the configuration that minimizes the number of MIMO array antennas when there is a difference equivalent to one antenna.

[0360] As shown in Figures 54A to D, |N TxHGroup1_ANT -N TxHGroup2_ANT |=0 and |N RxVGroup1_ANT -N RxVGroup2_ANT The configuration with the minimum number of MIMO array antennas when |=1 is one in which the number of transmitting antennas is 4(N TxVGroup1_ANT =N TxVGroup2_ANT =2), resulting in a configuration with 3 receiving antennas, and for example, there are 4 patterns as shown in Figures 54A to D.

[0361] Figure 54A shows N RxHGroup1_ANT =1(Rx#1), ​​N RxHGroup2_ANT =2(Rx#2,Rx#3), (ΔH Tx , ΔV Rx )=(-D H , +D V Examples of MIMO array configurations and virtual receiver array configurations for the case shown are provided.

[0362] Figure 54B shows N RxHGroup1_ANT =1(Rx#1), ​​N RxHGroup2_ANT =2(Rx#2,Rx#3), (ΔH Tx , ΔV Rx )=(+D H , +D VExamples of MIMO array configurations and virtual receiver array configurations for the case shown are provided.

[0363] Figure 54C shows N RxHGroup1_ANT =2(Rx#1,Rx#2), N RxHGroup2_ANT =1(Rx#3), (ΔH Tx , ΔV Rx )=(-D H ,-D V Examples of MIMO array configurations and virtual receiver array configurations for the case shown are provided.

[0364] Figure 54D shows N RxHGroup1_ANT =2(Rx#1,Rx#2), N RxHGroup2_ANT =1(Rx#3), (ΔH Tx , ΔV Rx )=(+D H ,-D V Examples of MIMO array configurations and virtual receiver array configurations for the case shown are provided.

[0365] Figures 55A-D show the number of transmitting antennas N included in the first transmitting antenna group. TxHGroup1_ANT and the number of transmitting antennas N included in the second group of transmitting antennas TxHGroup2_ANT There is a difference of one antenna between the two, and the number of receiving antennas included in the first receiving antenna group is N. RxVGroup1_ANT The number of receiving antennas N included in the second receiving antenna group. RxVGroup2_ANT This example shows the configuration that minimizes the number of MIMO array antennas when there is a difference equivalent to one antenna.

[0366] As shown in Figures 55A to D, |n TxHGroup1_ANT -N TxHGroup2_ANT |=1 and |N RxVGroup1_ANT -N RxVGroup2_ANT When |=1, the configuration that minimizes the number of MIMO array antennas is one in which the number of transmitting antennas is 3 and the number of receiving antennas is 3. For example, there are four patterns as shown in Figures 55A to D.

[0367] Figure 55A shows n TxVGroup1_ANT =1(Tx#2), N TxVGroup2_ANT =2(Tx#1,Tx#3), N RxHGroup1_ANT =2(Rx#1,Rx#2), NRxHGroup2_ANT =1(Rx#3), (ΔH Tx , ΔV Rx )=(-D H ,-D V Examples of MIMO array configurations and virtual receiver array configurations for the case shown are provided.

[0368] Figure 55B shows N TxVGroup1_ANT =1(Tx#2), N TxVGroup2_ANT =2(Tx#1,Tx#3), N RxHGroup1_ANT =1(Rx#1), ​​N RxHGroup2_ANT =2(Rx#2,Rx#3), (ΔH Tx , ΔV Rx )=(-D H , +D V Examples of MIMO array configurations and virtual receiver array configurations for the case shown are provided.

[0369] Figure 55C shows N TxVGroup1_ANT =2(Tx#2,Tx#3), N TxVGroup2_ANT =1(Tx#1), ​​N RxHGroup1_ANT =2(Rx#1,Rx#2), N RxHGroup2_ANT =1(Rx#3), (ΔH Tx , ΔV Rx )=(+D H ,-D V Examples of MIMO array configurations and virtual receiver array configurations for the case shown are provided.

[0370] Figure 55D shows N TxVGroup1_ANT =2(Tx#2,Tx#3), N TxVGroup2_ANT =1(Tx#1), ​​N RxHGroup1_ANT =1(Rx#1), ​​N RxHGroup2_ANT =2(Rx#2,Rx#3), (ΔH Tx , ΔV Rx )=(+D H , +D V Examples of MIMO array configurations and virtual receiver array configurations for the case shown are provided.

[0371] For example, in Figures 55A to D, the transmitting array antenna includes three transmitting antennas, and the receiving array antenna includes three receiving antennas.

[0372] Furthermore, two of the three transmitting antennas (for example, transmitting antennas included in one transmitting antenna group) are, for example, 2D horizontally. H (In other words, D H They are positioned at a distance of twice the distance between them. Also, the remaining of the three transmitting antennas is positioned, for example, horizontally, away from the two transmitting antennas mentioned above. H They are spaced apart (in other words, in an intermediate position) and are positioned vertically from the two transmitting antennas mentioned above in 2D. V Interval (in other words, D V They are placed at a distance of twice the normal distance.

[0373] Similarly, two of the three receiving antennas (for example, receiving antennas included in one receiving antenna group) are, for example, 2D in the vertical direction. V (In other words, D V They are positioned at a distance of twice the distance between them. Also, the remaining one of the three receiving antennas is positioned, for example, vertically, away from the two receiving antennas mentioned above. V They are spaced apart (in other words, positioned in the middle) and horizontally, 2D from the two receiving antennas mentioned above. H Interval (in other words, D H They are placed at a distance of twice the normal distance.

[0374] In other words, in Figures 55A to D, the positions of the three transmitting antennas and the positions of the three receiving antennas are rotationally symmetrical in a two-dimensional plane composed of the horizontal (e.g., X-axis) and vertical (e.g., Y-axis) directions. For example, in Figures 52A to D, the transmitting array antenna and the receiving array antenna are rotated by ±90 degrees.

[0375] Furthermore, the basic configuration 3 and the transmitting and receiving antenna configurations related to each modified version of the basic configuration 3 include at least an antenna configuration having the arrangement relationship of the three transmitting antennas or three receiving antennas described above.

[0376] As shown in Figures 52A-D, 53A-D, 54A-D, and 55A-D, each virtual array element of the virtual receiving array is arranged in a different position without overlap, thus expanding the aperture length of the virtual receiving array and improving the angular resolution.

[0377] Furthermore, the virtual array element located near the center of the virtual receiving array is D H , D V They are densely arranged at intervals. For example, in Figures 52A-D, 53A-D, 54A-D and 55A-D, the intervals are D H and interval D V If we set the value to approximately 0.5λ, the virtual array element located near the center of the virtual receiving array will have a horizontal dimension of D H = 0.5λ intervals, vertically in the direction D V They are spaced at 0.5λ intervals. This reduces grating groves.

[0378] Also, for example, in the MIMO array configuration of basic configuration 3, the interval D H and interval D V If the value is set to approximately 0.5λ, the horizontal and vertical element sizes of the transmitting antenna 106 and the receiving antenna 202 can be designed to be approximately 1λ or larger.

[0379] This allows for, for example, the use of a subarray consisting of four planar patch antennas arranged in a 2x2 grid, as shown in Figure 9A (where the antenna width W is...). ANT < 2D H Antenna height H ANT <2D V This can be applied to at least one antenna element of the transmitting array antenna and receiving array antenna shown in Figures 52A-D, 53A-D, 54A-D, and 55A-D.

[0380] Also, in the case of the transmitting antenna 106, the lateral direction W ANT The element size is D H If it is smaller than that, an antenna of any size can be used in the vertical direction.

[0381] For example, Figure 56A shows an example where a sub-array of planar patch antennas arranged in a vertical order of 8 elements and a horizontal order, as shown in Figure 25A, is applied to the antenna configuration shown in Figure 52A. Note that, as shown in Figure 56B, in addition to the transmitting array antenna shown in Figure 56A, a parasitic element (dummy element) may be placed. The parasitic element can equalize the effect of inter-antenna coupling by adjacent antennas across each antenna, thereby equalizing the directional characteristics of each transmitting antenna (Tx#1~#4).

[0382] Thus, by using a sub-array configuration antenna in the antenna arrangement related to basic arrangement 3, the directional gain of the antenna can be improved, and the detection performance (e.g., detection distance) of the radar device 10 can be improved.

[0383] The direction estimation unit 214 performs direction estimation processing in the horizontal and vertical directions using the received signals of the virtual receiving array obtained from the above-described transmitting and receiving antenna arrangement. Note that the processing of the virtual receiving array of basic arrangement 3 in the direction estimation unit 214 is the same as that of basic arrangement 1, so its explanation is omitted here.

[0384] Figure 57 shows, for example, a MIMO array configuration (D) with the number of transmitting antennas 106 Nt=4 and the number of receiving antennas 202 Na=4, as shown in Figure 52A. H =0.5λ, D V An example of the direction estimation result when using the beamformer method as the direction estimation algorithm of the direction estimation unit 214, with (=0.5λ) used, is shown. Specifically, in Figure 57, the horizontal and vertical antenna spacing of the transmitting antenna 106 is 1λ or more, and the horizontal and vertical antenna spacing of the receiving antenna 202 is also 1λ or more. Note that the directivity of each antenna is calculated as omnidirectional.

[0385] Figure 57 plots the output of the estimated direction of arrival evaluation function values ​​within a range of ±90 degrees horizontally and ±90 degrees vertically, when the target true value is set to 0 degrees horizontally and 0 degrees vertically.

[0386] In Figure 57, it can be seen that the grating lobe is reduced in directions other than horizontal 0 degrees and vertical 0 degrees of the target true value, compared to, for example, Figure 1A. For example, in Figure 57, the ratio (PSLR) of the peak power value of the highest side lobe excluding the main lobes in directions other than horizontal 0 degrees and vertical 0 degrees to the peak power value of the main lobe in the horizontal 0 degrees and vertical 0 degrees directions is approximately 0.3.

[0387] As described above, by using the MIMO array configuration related to basic configuration 3, even if the vertical or horizontal element size of the antennas used in the transmitting array antenna and the receiving array antenna is about 1λ, the antennas in the virtual receiving array can be arranged to include element spacings of about 0.5λ in the horizontal and vertical directions, thereby reducing grating lobes. Furthermore, for example, since each virtual array element in the virtual receiving array shown in Figure 52A is arranged without overlap, the aperture length of the virtual receiving array can be expanded, improving the angular resolution.

[0388] <Modification 1 of Basic Arrangement 3> In Basic Configuration 3, the number of transmitting antennas 106 and receiving antennas 202 were described for configurations of 4 transmitting elements (Nt=4) and 4 receiving elements (Na=4) (e.g., Figures 52A-D), 3 transmitting elements (Nt=3) and 4 receiving elements (Na=4) (e.g., Figures 53A-D), 4 transmitting elements (Nt=4) and 3 receiving elements (Na=3) (e.g., Figures 54A-D), and the minimum configuration of 3 transmitting elements (Nt=3) and 3 receiving elements (Na=3) (e.g., Figures 55A-D). However, the number of transmitting antennas Nt and the number of receiving antennas Na are not limited to these numbers.

[0389] Modification 1 of Basic Configuration 3 describes a configuration in which the number of antennas in the MIMO array is increased compared to Basic Configuration 3.

[0390] For example, in a transmitting array antenna, the number of transmitting antennas N included in the first group of transmitting antennas. TxHGroup1_ANT , and the number of antennas N included in the second transmitting antenna group. TxHGroup2_ANTThe number of antennas included in the first receiving antenna group N in the receiving array antenna may be increased. RxVGroup1_ANT , and the number of antennas N included in the second receiving vertical antenna group. RxVGroup2_ANT You may increase it.

[0391] Figure 58 shows N TxHGroup1_ANT =2(Tx#2,Tx#4), N TxHGroup2_ANT =2(Tx#1,Tx#3), N RxVGroup1_ANT =3(Rx#1,Rx#2,Rx#3), N RxVGroup2_ANT The MIMO array configuration example and virtual receiver array configuration example for the case of =3(Rx#4,Rx#5,Rx#6) are shown. Note that in Figure 58, (ΔH Tx , ΔV Rx )=(-D H ,-D V This shows the case of (ΔH Tx , ΔV Rx )=(-D H , +D V ), (+D H ,-D V )(+D H , +D V ) is also acceptable.

[0392] Figure 59 shows N TxHGroup1_ANT =2(Tx#2,Tx#4), N TxHGroup2_ANT =2(Tx#1,Tx#3), N RxVGroup1_ANT =3(Rx#1,Rx#2,Rx#3), N RxVGroup2_ANT The MIMO array configuration example and virtual receiver array configuration example for the case of =2(Rx#4,Rx#5) are shown. Note that in Figure 59, (ΔH Tx , ΔV Rx )=(-D H ,-D V This shows the case of (ΔH Tx , ΔV Rx )=(+D H ,-D V ) is also acceptable.

[0393] Figure 60 shows N TxHGroup1_ANT =4(Tx#2,Tx#4,Tx#6,Tx#8), N TxHGroup2_ANT =4(Tx#1,Tx#3,Tx#5,Tx#7), NRxVGroup1_ANT =3(Rx#1,Rx#2,Rx#3), N RxVGroup2_ANT The MIMO array configuration example and virtual receiver array configuration example for the case of =3(Rx#4,Rx#5,Rx#6) are shown. Note that in Figure 60, (ΔH Tx , ΔV Rx )=(-D H ,-D V This shows the case of (ΔH Tx , ΔV Rx )=(-D H , +D V ), (+D H ,-D V )(+D H , +D V ) is also acceptable.

[0394] Figure 61 shows N TxHGroup1_ANT =3(Tx#2,Tx#4,Tx#6), N TxHGroup2_ANT =4(Tx#1,Tx#3,Tx#5,Tx#7), N RxVGroup1_ANT =3(Rx#1,Rx#2,Rx#3), N RxVGroup2_ANT The MIMO array configuration example and virtual receiver array configuration example for the case of =3(Rx#4,Rx#5,Rx#6) are shown. Note that in Figure 61, (ΔH Tx , ΔV Rx )=(-D H ,-D V This shows the case of (ΔH Tx , ΔV Rx )=(-D H , +D V ) is also acceptable.

[0395] In each MIMO array configuration shown in Figures 58 to 61, for example, D H and D V By setting the value to approximately 0.5λ, the horizontal and vertical element sizes of the transmitting antenna 106 and the receiving antenna 202 can be designed to be approximately 1λ or larger.

[0396] Furthermore, for example, in each virtual receiving array shown in Figures 58 to 61, each virtual array element is arranged in a different position without overlap, so the aperture length of the virtual receiving array can be expanded and the angular resolution can be improved.

[0397] Furthermore, the virtual array elements located near the center of each virtual receiving array shown in Figures 58 to 61 are D H , D V They can be placed close together at intervals. Also, D H , D V The number of virtual array elements densely arranged at intervals is N TxHGroup1_ANT , N TxHGroup2_ANT , N RxVGroup1_ANT and N RxVGroup2_ANT It increases depending on the situation.

[0398] For example, in a virtual receiving array, in the horizontal direction, (N TxHGroup1_ANT +N TxHGroup2_ANT The virtual array element of ) is D H They are spaced apart, and in the vertical direction (N RxVGroup1_ANT +N RxVGroup2_ANT The virtual array element of ) is D V They are arranged at intervals. Also, in a virtual receiving array, (N in the horizontal direction) TxHGroup1_ANT +N TxHGroup2_ANT )-2 D H A virtual array element with spacing, and (N in the vertical direction) RxVGroup1_ANT +N RxVGroup2_ANT )-2 D V The virtual array elements are spaced apart and arranged in a rectangular pattern both vertically and horizontally.

[0399] Near the center of the virtual receiving array, D H , D V The more densely spaced virtual array elements there are, the better the reduction effect on grating lobes and side lobes can be achieved.

[0400] Also, N TxGroup1_ANT , N TxHGroup2_ANT The larger N is, the greater the number of virtual array elements arranged horizontally, which in turn expands the aperture length of the horizontal virtual receiving array and improves the horizontal angular resolution. Similarly, N RxVGroup1_ANT , N RxVGroup2_ANT The larger the value, the greater the number of virtual array elements arranged vertically, which allows for an expansion of the aperture length of the vertical virtual receiving array and improves the vertical angular resolution.

[0401] Figure 62 shows, for example, a MIMO array configuration (Nt=8) with a number of transmitting antennas 106 and a number of receiving antennas 202 Na=6, as shown in Figure 60. TxGroup1_ANT =4, N TxGroup2_ANT =4, N RxGroup1_ANT =3, N RxGroup2_ANT =3, D H =0.5λ, D V An example of the direction estimation result when using the beamformer method as the direction estimation algorithm for the direction estimation unit 214, with (=0.5λ) used, is shown. Note that the directivity of each antenna is calculated as omnidirectional.

[0402] Figure 62 plots the output of the estimated direction of arrival evaluation function values ​​within a range of ±90 degrees horizontally and ±90 degrees vertically, when the target true value is set to 0 degrees horizontally and 0 degrees vertically.

[0403] In Figure 62, it can be seen that the grating lobe is reduced in directions other than horizontal 0 degrees and vertical 0 degrees of the target true value. For example, in Figure 62, the ratio of the peak power value of the highest side lobe excluding the main lobe to the peak power value of the main lobe in the horizontal 0 degrees and vertical 0 degrees directions (PSLR) is approximately 0.13, which is, for example, compared to Figure 52A, N TxHGroup1_ANT , N TxHGroup2_ANT and N RxVGroup1_ANT , N RxVGroup2_ANT By increasing the value, an improvement in the reduction effect of the side lobes can be observed. Also, in Figure 62, the peak of the main lobe is sharper compared to Figure 57, and N TxHGroup1_ANT , N TxHGroup2_ANT and N RxVGroup1_ANT , N RxVGroup2_ANT The increase in [the specified value] indicates an improvement in angular resolution.

[0404] <Modification 2 of Basic Arrangement 3> The following describes the antenna placement methods 3-2A and 3-2B in modified example 2 of basic configuration 3.

[0405] (Placement method 3-2A) In Modification 1 of Basic Arrangement 3, the number of receiving antennas included in the receiving antenna group of the receiving array antenna is N. RxVGroup1_ANT , N RxVGroup2_ANT We have explained the case in which the number of virtual array elements arranged vertically is increased by increasing the value. However, this is not limited to this, and for example, in a transmitting array antenna, the number of transmitting antenna groups N TxGroup Increasing this value can also increase the number of virtual array elements arranged vertically in the virtual receiver array.

[0406] In this case, the vertical antenna spacing of the transmitting antenna group is set to a constant value (for example, 2D V ) is acceptable, but the number of receiving antennas included in the receiving antenna group is N. RxVGroup1_ANT , N RxVGroup2_ANT Depending on this, the virtual receiver array configuration may result in an arrangement where virtual array elements overlap.

[0407] Therefore, in order to ensure that the virtual receiver array arrangement does not contain any overlapping virtual array elements, for example, the following spacing D can be added to the even-numbered antenna spacings in the vertical direction of the transmitting antenna group. TxHGroupV You may use this.

number

[0408] For example, N RxVGroup1_ANT =N RxVGroup2_ANT If =2, D TxHGroupV =2D V N RxVGroup1_ANT =N RxVGroup2_ANT If =3, D TxHGroupV =4D V This is the result.

[0409] For example, the number of transmitting antennas N TxHGroup If =3, the spacing between the three transmitting antenna groups is {2D V , D TxHGroupV Let's assume the number of transmitting antenna groups is N. TxHGroup If =4, the spacing between the four transmitting antenna groups is {2D V , D TxHGroupV , 2DV Let} be the case. Similarly, N RxGroup_ANT If = 5, the spacing between the 5 transmitting antenna groups is {2D V , D TxHGroupV , 2D V , D TxHGroupV Let's assume that.

[0410] Figure 63 shows N RxVGroup =2, N TxHGroup =4, N TxHGroup1_ANT =2, N TxHGroup2_ANT =2, N TxHGroup3_ANT =2, N TxHGroup4_ANT =2, N RxVGroup1_ANT =2, N RxVGroup2_ANT Examples of MIMO array configurations and virtual receiver array configurations for the case where =2 are shown. TxHGroup3_ANT " represents the number of transmitting antennas included in the third transmitting antenna group, and "N TxHGroup4_ANT " represents the number of transmitting antennas included in the fourth transmitting antenna group. In Figure 63, D in equation (15) TxHGroupV =2D V This is the result.

[0411] In Figure 63, the difference ΔV between the second receiving antenna group (Rx#3, Rx#4) and the first receiving antenna group (Rx#1, Rx#2) is shown. Rx(2,1) ΔV Rx(2,1) =-D V This shows the case of ΔV Rx(2,1) =+D V That is also acceptable.

[0412] Furthermore, Figure 63 shows the amount of shift ΔH between the second transmitting antenna group (Tx#3, Tx#7) and the first transmitting antenna group (Tx#4, Tx#8). Tx(2,1) to -D H The difference ΔH between the third transmitting antenna group (Tx#2, Tx#6) and the second transmitting antenna group is... Tx(3,2) to +D H The difference ΔH between the fourth transmitting antenna group (Tx#1, Tx#5) and the third transmitting antenna group is... Tx(4,3) to -D H Let's assume that each displacement amount has two types (+D V ,-D VAny combination of ) is acceptable. Note that in Figure 63, +D V The direction is upward, -D V The direction is downwards, +D H The direction is to the right, -D H This is considered to be the left direction.

[0413] Also, Figure 64 shows N RxVGroup =2, N TxHGroup =4, N TxHGroup1_ANT =2, N TxHGroup2_ANT =2, N TxHGroup3_ANT =2, N TxHGroup4_ANT =2, N RxVGroup1_ANT =3, N RxVGroup2_ANT Examples of MIMO array configurations and virtual receiver array configurations for the case where =3 are shown. In Figure 64, D in equation (15) TxHGroupV =4D V This is the result.

[0414] In Figure 64, the amount of deviation ΔV between the second receiving antenna group (Rx#4, Rx#5, Rx#6) and the first receiving antenna group (Rx#1, Rx#2, Rx#3) is shown. Rx(2,1) ΔV Rx(2,1) =-D V This shows the case of ΔV Rx(2,1) =+D V That is also acceptable.

[0415] Furthermore, Figure 64 shows the amount of shift ΔH between the second transmitting antenna group (Tx#3, Tx#7) and the first transmitting antenna group (Tx#4, Tx#8). Tx(2,1) is, -D H The difference ΔH between the third transmitting antenna group (Tx#2, Tx#6) and the second transmitting antenna group is... Tx(3,2) is, +D H The difference ΔH between the fourth transmitting antenna group (Tx#1, Tx#5) and the third transmitting antenna group is... Tx(4,3) is, -D H Let's assume that each displacement amount has two types (+D V ,-D V Any combination of ) is acceptable. Note that in Figure 64, +D V The direction is upward, -D V The direction is downwards, +D HThe direction is to the right, -D H This is considered to be the left direction.

[0416] Note that there are unequal intervals (for example, D) near the center of the virtual receiving array. H and D V If arrangements with a larger spacing than D are allowed, TxHGroupV This value may be greater than the value in equation (15).

[0417] (Placement method 3-2B) In variation 1 of the basic configuration 3, the number of transmitting antennas included in each transmitting antenna group of the transmitting array antenna is N. TxHGroup1_ANT , N TxHGroup2_ANT The case where the number of virtual array elements arranged horizontally is increased by increasing the value was explained. However, this is not limited to this, and for example, in a receiving array antenna, the number of receiving antenna groups N RxVGroup Increasing this value can also increase the number of virtual array elements arranged horizontally in the virtual receiver array.

[0418] In this case, the horizontal spacing between the receiving antennas is set to a constant value (for example, 2D) H ) may be used, but the number of transmitting antennas included in the transmitting antenna group N TxHGroup1_ANT , N TxHGroup2_ANT Depending on this, the virtual receiver array configuration may result in an arrangement where virtual array elements overlap.

[0419] Therefore, in order to create a virtual receiver array arrangement that does not include any overlapping virtual array elements, for example, at even-numbered intervals in the horizontal spacing of the receiver antenna group, the following interval D can be added. RxVGroupH You may use this.

number

[0420] For example, N TxHGroup1_ANT =N TxHGroup2_ANT If =2, D RxVGroupH =2D H N TxHGroup1_ANT =N TxHGroup2_ANT If =3, DRxVGroupH =4D H This is the result.

[0421] For example, the number of receiving antennas N RxVGroup If =3, the horizontal spacing between the three receiving antenna groups is {2D H , D RxVGroupH Let's assume the number of receiving antenna groups is N. RxVGroup If =4, the horizontal spacing of the four receiving antenna groups is {2D H , D RxVGroupH , 2D H Let's assume the number of receiving antenna groups is N. RxVGroup If = 5, the horizontal spacing of the 5 receiving antenna groups is {2D H , D RxVGroupH , 2D H , D RxVGroupH Let's assume that.

[0422] Figure 65 shows N TxHGroup =2, N RxVGroup =4, N TxHGroup1_ANT =2, N TxHGroup2_ANT =2, N RxVGroup1_ANT =2, N RxVGroup2_ANT =2, N RxVGroup3_ANT =2, N RxVGroup4_ANT Examples of MIMO array configurations and virtual receiver array configurations for the case where =2 are shown. RxVGroup3_ANT " represents the number of receiving antennas included in the third receiving antenna group, and "N RxVGroup4_ANT " represents the number of receiving antennas included in the fourth receiving antenna group. In Figure 65, D in equation (16) RxVGroupH =2D H This is the result.

[0423] Figure 65 shows the displacement ΔH of the second transmitting antenna group (Tx#1, Tx#3) relative to the first transmitting antenna group (Tx#2, Tx#4). Tx(2,1) ΔH Tx(2,1) =-D H This shows the case of ΔH Tx(2,1) =+D H That is also acceptable.

[0424] Furthermore, Figure 65 shows the amount of shift ΔV between the second receiving antenna group (Rx#3, Rx#4) and the first receiving antenna group (Rx#1, Rx#2). Rx(2,1) to -D V The difference ΔV between the third receiving antenna group (Rx#5, Rx#6) and the second receiving antenna group is... Rx(3,2) to +D V The difference ΔV between the fourth receiving antenna group (Rx#7, Rx#8) and the third receiving antenna group is... Rx(4,3) to -D V Let's assume that each displacement amount has two types (+D V ,-D V Any combination of ) is acceptable. Note that in Figure 65, +D V The direction is upward, -D V The direction is downward.

[0425] Figure 66 shows N TxHGroup =2, N RxVGroup =4, N TxHGroup1_ANT =3, N TxHGroup2_ANT =3, N RxVGroup1_ANT =2, N RxVGroup2_ANT =2, N RxVGroup3_ANT =2, N RxVGroup4_ANT Examples of MIMO array configurations and virtual receiver array configurations for the case where =2 are shown. In Figure 66, D in equation (16) RxVGroupH =4D H This is the result.

[0426] Furthermore, the amount of deviation ΔH between the second transmitting antenna group (Tx#1, Tx#3, Tx#5) and the first transmitting antenna group (Tx#2, Tx#4, Tx#6) is... Tx(2,1) ΔH Tx(2,1) =-D H This shows the case of ΔH Tx(2,1) =+D H That is also acceptable.

[0427] Furthermore, Figure 66 shows the displacement ΔV of the second vertical receiving antenna group (Rx#3, Rx#4) relative to the first receiving antenna group (Rx#1, Rx#2). Rx(2,1) to -D V The difference ΔV between the third receiving antenna group (Rx#5, Rx#6) and the second receiving antenna group is... Rx(3,2)to +D V The difference ΔV between the fourth receiving antenna group (Rx#7, Rx#8) and the third receiving antenna group is... Rx(4,3) to -D V Let's assume that each displacement amount has two types (+D V ,-D V Any combination of ) is acceptable. Note that in Figure 66, +D V The direction is upward, -D V The direction is downwards, +D H The direction is to the right, -D H This is considered to be the left direction.

[0428] Also, there are unequal intervals (for example, D) near the center of the virtual receiving array. H and D V If arrangements with a larger spacing than D are allowed, RxVGroupH This value may be greater than the value in equation (16).

[0429] The above describes the arrangement methods 3-2A and 3-2B in the modified example 2 of the basic arrangement 3.

[0430] For example, in the transmit / receive antenna configuration shown in Figures 63 to 66 (e.g., MIMO array configuration), for example, D H and D V By setting the value to approximately 0.5λ, the horizontal and vertical element sizes of the transmitting antenna 106 and the receiving antenna 202 can be designed to be approximately 1λ or larger.

[0431] Furthermore, for example, in the virtual receiving array shown in Figures 63 to 66, each virtual array element is arranged in a different position without overlapping, which allows for an expansion of the aperture length of the virtual receiving array and an improvement in angular resolution.

[0432] Furthermore, for example, a virtual array element located near the center of the virtual receiving array shown in Figures 63 to 66 is D H , D V They can be placed close together at intervals. Also, D H , D V The number of virtual array elements densely arranged at intervals is equal to the number of transmitting antennas N.TxHGroup , and the number of transmitting antennas N included in each transmitting antenna group. TxHGroup(ntvg)_ANT (Here, ntvg=1,…, N TxHGroup (If so, the number of receiving antenna groups N RxVGroup , and the number of receiving antennas N included in each receiving antenna group. RxVGroup(nrhg)_ANT (Here, nrhg=1,…, N RxVGroup It increases depending on (that).

[0433] For example, in a virtual receiving array, the horizontal direction is 0.5 × (N TxHGroup1_ANT +N TxHGroup2_ANT ) × N RxVGroup The virtual array element is D H They are arranged in rows with intervals between them, and in the vertical direction, 0.5 × (N RxVGroup1_ANT +N RxVGroup2_ANT ) × N TxHGroup The virtual array element is D V They are arranged in rows at intervals. Also, in the horizontal direction, 0.5 × (N TxHGroup1_ANT +N TxHGroup2_ANT ) × N RxVGroup -2 D H A virtual array element with spacing, and 0.5 × (N) in the vertical direction. RxVGroup1_ANT +N RxVGroup2_ANT ) × N TxHGroup -2 D V The virtual array elements with spacing are arranged in a rectangular pattern both vertically and horizontally.

[0434] Near the center of the virtual receiving array, D H , D V The more densely spaced virtual array elements there are, the better the reduction effect on grating lobes and side lobes can be.

[0435] Furthermore, the number of transmitting antennas N included in each transmitting antenna group. TxHGroup(ntvg)_ANT , and the number of receiving antenna groups N RxVGroup The larger the value, the greater the number of virtual array elements arranged horizontally, which in turn expands the aperture length of the horizontal virtual receiving array and improves the horizontal angular resolution. Similarly, the number of receiving antennas N included in each receiving antenna group... RxVGroup(nrhg)_ANT , and the number of transmitting antenna groups N TxHGroupThe larger the value, the greater the number of virtual array elements arranged vertically, which allows for an expansion of the aperture length of the vertical virtual receiving array and improves the vertical angular resolution.

[0436] Furthermore, in variation 2 of basic arrangement 3, it is also possible to combine arrangement methods 3-2A and 3-2B.

[0437] Figure 67 shows N RxVGroup =N TxHGroup =4, N TxHGroup1_ANT =N TxHGroup2_ANT =N TxHGroup3_ANT =N TxHGroup4_ANT =2, N RxVGroup1_ANT =N RxVGroup2_ANT =N RxVGroup3_ANT =N RxVGroup4_ANT Examples of MIMO array configurations and virtual receiver array configurations for the case where =2 are shown. In Figure 67, D in equation (15) TxHGroupV =2D V And so, D in equation (16) RxVGroupH =2D H This is the result.

[0438] Furthermore, Figure 67 shows the amount of shift ΔH between the second transmitting antenna group (Tx#3, Tx#7) and the first transmitting antenna group (Tx#4, Tx#8). Tx(2,1) is, -D H The difference ΔH between the third transmitting antenna group (Tx#2, Tx#6) and the second transmitting antenna group is... Tx(3,2) is-D H The difference ΔH between the fourth transmitting antenna group (Tx#1, Tx#5) and the third transmitting antenna group is... Tx(4,3) is-D H Let's assume that each displacement amount has two types (+D V ,-D V Any combination of the above is acceptable.

[0439] Furthermore, Figure 67 shows the amount of shift ΔV between the second receiving antenna group (Rx#3, Rx#4) and the first receiving antenna group (Rx#1, Rx#2). Rx(2,1) is-D V The difference ΔV between the third receiving antenna group (Rx#5, Rx#6) and the second receiving antenna group is... Rx(3,2)is +D V The difference ΔV between the fourth receiving antenna group (Rx#7, Rx#8) and the third receiving antenna group is... Rx(4,3) is, -D V Let's assume that each displacement amount has two types (+D V ,-D V Any combination of the above is acceptable.

[0440] Also, in Figure 67, +D V The direction is upward, -D V The direction is downwards, +D H The direction is to the right, -D H The direction is left.

[0441] Also, Figure 68A shows N RxVGroup =N TxHGroup =4, N TxHGroup1_ANT =N TxHGroup2_ANT =N TxHGroup3_ANT =N TxHGroup4_ANT =4, N RxVGroup1_ANT =N RxVGroup2_ANT =N RxVGroup3_ANT =N RxVGroup4_ANT Figure 68A shows an example of a MIMO array configuration when =4, and Figure 68B shows an example of a virtual receiver array configuration. In Figure 68A, D in equation (15) TxHGroupV =6D V And so, D in equation (16) RxVGroupH =6D H This is the result.

[0442] Furthermore, Figure 68A shows the amount of deviation ΔH between the second transmitting antenna group (Tx#3, Tx#7, Tx#11, Tx#15) and the first transmitting antenna group (Tx#4, Tx#8, Tx#12, Tx#16). Tx(2,1) is-D H The difference ΔH between the third transmitting antenna group (Tx#2, Tx#6, Tx#10, Tx#14) and the second transmitting antenna group is... Tx(3,2) is, +D H The difference ΔH between the fourth transmitting antenna group (Tx#1, Tx#5, Tx#9, Tx#13) and the third transmitting antenna group is... Tx(4,3) is, -D H Let's assume that each displacement amount has two types (+D V ,-D VAny combination of the above is acceptable.

[0443] Furthermore, Figure 68A shows the amount of shift ΔV between the second receiving antenna group (Rx#5, Rx#6, Rx#7, Rx#8) and the first receiving antenna group (Rx#1, Rx#2, Rx#3, Rx#4). Rx(2,1) is-D V The difference ΔV between the third receiving antenna group (Rx#9, Rx#10, Rx#11, Rx#12) and the second receiving antenna group is... Rx(3,2) is +D V The difference ΔV between the fourth receiving antenna group (Rx#13, Rx#14, Rx#15, Rx#16) and the third receiving antenna group is... Rx(4,3) is-D V Let's assume that each displacement amount has two types (+D V ,-D V Any combination of the above is acceptable.

[0444] Furthermore, in Figures 68A and 68B, +D V The direction is upward, -D V The direction is downwards, +D H The direction is to the right, -D H The direction is left.

[0445] <Basic layout 4> Figure 69 shows an example of the arrangement of the transmitting antenna 106 and receiving antenna 202 in the basic configuration 4, and an example of the arrangement of the virtual receiving array.

[0446] (1) Arrangement of transmitting and receiving antennas In Figure 69, the number of transmitting antennas 106 in the transmitting array antenna is set to Nt = 4 (Tx#1, Tx#2, Tx#3, and Tx#4), and the number of receiving antennas 202 in the receiving array antenna is set to Na = 4 (Rx#1, Rx#2, Rx#3, and Rx#4).

[0447] The transmitting array antenna shown in Figure 69 consists of, for example, a "first transmitting antenna group" (Tx#2, Tx#4 in Figure 69) and a "second transmitting antenna group" (Tx#1, Tx#3 in Figure 69). Each transmitting antenna group has a horizontal spacing of 2D H The spacing is D in the vertical direction. V It includes two transmitting antenna elements. In each of the transmitting antenna groups shown in Figure 69, adjacent transmitting antennas are 2D horizontally. H The interval (in other words, D H They are placed at a distance of twice the distance between them, and vertically in the D direction. V They are arranged at intervals of 2D. In other words, in Figure 69, the transmitting antennas included in each transmitting antenna group are arranged horizontally in 2D. H , vertically D V The antennas are arranged in a straight line diagonally downward to the right (in other words, diagonally upward to the left) with this antenna spacing.

[0448] Furthermore, in Figure 69, the second transmitting antenna group is positioned horizontally to the left of the first transmitting antenna group, D H , downwards in the vertical direction 2D V They are positioned with a staggered arrangement. In other words, the adjacent transmitting antenna groups shown in Figure 69 are positioned horizontally in the D direction. H The intervals are 2D vertically. V (In other words, D V They are in a shifted relationship (by twice the interval).

[0449] Furthermore, the receiving array antenna shown in Figure 69 is composed of, for example, a "first receiving antenna group" (Rx#2, Rx#4 in Figure 69) and a "second receiving antenna group" (Rx#1, Rx#3 in Figure 69). Each receiving antenna group has a horizontal antenna spacing of 2D H And the antenna spacing is D in the vertical direction. V It includes two receiving antenna elements. In each receiving antenna group shown in Figure 69, adjacent receiving antennas are 2D in the horizontal direction. H The interval (in other words, D H They are placed at a distance of twice the distance between them, and vertically in the D direction.V They are arranged at intervals of 2D. In other words, in Figure 69, the receiving antennas included in each receiving antenna group are arranged horizontally in 2D. H , vertically D V The antennas are arranged in a straight line diagonally upward to the right (in other words, diagonally downward to the left) with this antenna spacing.

[0450] Furthermore, in Figure 69, relative to the first receiving antenna group, the second receiving antenna group is positioned to the right in the horizontal direction D H , downwards in the vertical direction 2D V They are positioned with a staggered arrangement. In other words, the adjacent receiving antenna groups shown in Figure 69 are positioned horizontally D H The intervals are 2D vertically. V (In other words, D V They are in a shifted relationship (by twice the interval).

[0451] Furthermore, as shown in Figure 69, for example, each of the transmitting antennas Tx#1 to Tx#4 is positioned at a different location in both the horizontal and vertical directions. Similarly, as shown in Figure 69, each of the receiving antennas Rx#1 to Rx#4 is positioned at a different location in both the horizontal and vertical directions.

[0452] Furthermore, in the transmitting and receiving antenna arrangement shown in Figure 69, the respective positions of the transmitting antennas and the respective positions of the receiving antennas are symmetrical with respect to a line parallel to, for example, a line parallel to the horizontal or vertical direction (in other words, they are inverted).

[0453] For example, let's assume that the horizontal direction (side direction) shown in Figure 69 corresponds to the X-axis, and the vertical direction (vertical direction) shown in Figure 69 corresponds to the Y-axis direction.

[0454] In the antenna configuration shown in Figure 69, the position coordinates of the transmitting antenna 106, which constitutes the transmitting array antenna, are the position coordinates (X) of the transmitting antenna Tx#1. T_#1 ,Y T_#1 ) is used as the reference point for the position coordinates (X) of the transmitting antenna Tx#2. T_#2 ,Y T_#2 )=(XT_#1 +D H ,Y T_#1 +2D V ), position coordinates (X) of transmitting antenna Tx#3 T_#3 ,Y T_#3 )=(X T_#1 +2D H ,Y T_#1 -D V ), and the position coordinates (X) of the transmitting antenna Tx#4. T_#4 ,Y T_#4 )=(X T_#1 +3D H ,Y T_#1 +D V ) is expressed as.

[0455] Similarly, the position coordinates of receiving antenna 202, which constitutes the receiving array antenna, are the position coordinates (X) of receiving antenna Rx#1. R_#1 ,Y R_#1 ) is used as the reference point for the position coordinates (X) of the receiving antenna Rx#2. R_#2 ,Y R_#2 )=(X R_#1 -D H ,Y R_#1 +2D V ), position coordinates (X) of receiving antenna Rx#3 R_#3 ,Y R_#3 )=(X R_#1 +2D H ,Y R_#1 +D V ), and the position coordinates (X) of the receiving antenna Rx#4. R_#4 ,Y R_#4 )=(X R_#1 +D H ,Y R_#1 +3D V ) is expressed as.

[0456] (2) Arrangement of virtual receiver array The arrangement of the virtual receiving array (virtual antennas VA#1 to VA#16) formed by the transmitting and receiving antenna arrangement shown in Figure 69 above has the following characteristics.

[0457] For example, the arrangement of the transmitting array antenna and the receiving array antenna shown in Figure 69 allows for the position coordinates (X) of the virtual receiving array VA#1~VA#16. V_#1,Y V_#1 )~(X V_#16 ,Y V_#16 The following applies to each of them. Note that here, VA#1 is represented as the position reference (0,0) of the virtual receive array. (0,0), (D H , 2D V ), (2D H , -D V ), (3D H , D V ), (-D H , 2D V ), (0, 4D V ), (D H , D V ), (2D H , 3D V ), (2D H , D V ), (3D H , 3D V ), (4D H , 0), (5D H , 2D V ), (D H , 3D V ), (2D H , 5D V ), (3D H , 2D V ), (4D H , 4D V )

[0458] Thus, in the virtual receiver array arrangement shown in Figure 69, each virtual receiver array element is positioned at a different location without overlap. Therefore, the aperture length of the virtual receiver array can be expanded, narrowing the main lobe and improving the angular resolution.

[0459] Furthermore, the virtual array elements VA#2, VA#7, VA#9, VA#4, VA#15, VA#10, VA#8, and VA#13 located near the center of the virtual receiving array shown in Figure 69 are positioned horizontally in the D direction. H Spacing, vertically D V They are densely arranged at intervals. For example, in Figure 69, interval D H and interval D VWhen the value is approximately 0.5λ, the virtual array elements VA#2, VA#7, VA#9, VA#4, VA#15, VA#10, VA#8 and VA#13 are positioned horizontally in the D direction. H = 0.5λ intervals, vertically in the direction D V They are arranged at 0.5λ intervals. This reduces grating lobes, similar to basic arrangement 1 (see, for example, Figure 8).

[0460] Furthermore, near the center of the virtual receiving array shown in Figure 69, the interval D H and interval D V An element is missing at a position corresponding to a coordinate surrounded by densely arranged virtual array elements (e.g., VA#2, VA#7, VA#9, VA#4, VA#15, VA#10, VA#8, and VA#13). However, the radar device 10 surrounds the missing area with spacing D H and interval D V By performing interpolation processing using the received signals of densely arranged virtual array elements, the received signals of the elements in the missing locations can be approximately received.

[0461] Also, for example, in the MIMO array configuration of basic configuration 4, the interval D H and interval D V If the value is set to approximately 0.5λ, the horizontal and vertical element sizes of the transmitting antenna 106 and the receiving antenna 202 can be designed to be approximately 1λ or larger.

[0462] This allows for, for example, the use of a subarray consisting of four planar patch antennas arranged in a 2x2 grid, as shown in Figure 9A (where the antenna width W is...). ANT < 2D H Antenna height H ANT <2D V This can be applied to at least one antenna element of the transmitting array antenna and receiving array antenna shown in Figure 69. For example, Figure 70A shows an example where a sub-array of two vertically and two horizontally arranged planar patch antennas, as shown in Figure 9A, is applied to the transmitting antenna configuration shown in Figure 69.

[0463] Furthermore, in the transmitting antenna 106 and the receiving antenna 202, the lateral direction W ANT The element size is D H If it is smaller than the specified size, an antenna of any size can be used in the vertical direction. For example, Figure 70B shows an example where a sub-array of the planar patch antenna shown in Figure 25A, with 8 elements arranged vertically and 1 element arranged horizontally, is applied to the antenna arrangement shown in Figure 69. In addition to the transmitting array antenna shown in Figure 70B, a parasitic element (dummy element) may be placed (not shown).

[0464] Thus, by using a sub-array configuration antenna in the antenna arrangement related to the basic arrangement 4, the directional gain of the antenna can be improved, and the detection performance (e.g., detection distance) of the radar device 10 can be improved.

[0465] The direction estimation unit 214 performs direction estimation processing in the horizontal and vertical directions using the received signals of the virtual receiving array obtained from the above-described transmitting and receiving antenna arrangement. Note that the processing of the virtual receiving array of basic arrangement 4 in the direction estimation unit 214 is the same as that of basic arrangement 1, so its explanation is omitted here.

[0466] Figure 71 shows, for example, a MIMO array configuration (D) with the number of transmitting antennas 106 Nt=4 and the number of receiving antennas 202 Na=4, as shown in Figure 69. H =0.5λ, D V An example of the direction estimation result when the beamformer method is used as the direction estimation algorithm for the direction estimation unit 214, using (=0.5λ), is shown. Specifically, in Figure 71, the horizontal and vertical antenna spacing of the transmitting antenna 106 is 1λ or more, and the horizontal and vertical antenna spacing of the receiving antenna 202 is also 1λ or more. Note that the directivity of each antenna is calculated as omnidirectional.

[0467] Figure 71 plots the output of the estimated direction of arrival evaluation function values ​​within a range of ±90 degrees horizontally and ±90 degrees vertically, when the target true value is set to 0 degrees horizontally and 0 degrees vertically.

[0468] In Figure 71, it can be seen that the grating lobe is reduced in directions other than horizontal 0 degrees and vertical 0 degrees of the target true value, compared to, for example, Figure 1A. For example, in Figure 71, the ratio (PSLR) of the peak power value of the highest side lobe excluding the main lobes in directions other than horizontal 0 degrees and vertical 0 degrees to the peak power value of the main lobe in the horizontal 0 degrees and vertical 0 degrees directions is approximately 0.35.

[0469] As described above, by using the MIMO array configuration related to basic configuration 4, even if the vertical or horizontal element size of the antennas used in the transmitting array antenna and the receiving array antenna is about 1λ, the antennas in the virtual receiving array can be arranged to include element spacings of about 0.5λ in the horizontal and vertical directions, thereby reducing grating lobes. Furthermore, for example, since each virtual array element in the virtual receiving array shown in Figure 69 is arranged without overlap, the aperture length of the virtual receiving array can be expanded, improving the angular resolution.

[0470] <Modification 1 of Basic Arrangement 4> Basic configuration 4 (for example, Figure 69) describes the case where the number of transmitting antennas 106 is 4 elements (Nt=4) and the number of receiving antennas 202 is 4 elements (Na=4). However, the number of transmitting antennas Nt and the number of receiving antennas Na are not limited to these numbers.

[0471] In Modification 1 of Basic Configuration 4, for example, a configuration in which the number of transmitting antennas Nt and the number of receiving antennas Na are increased, using the antenna configuration shown in Figure 69 as the basic configuration, will be described.

[0472] The following describes the antenna placement methods 4-1A, 4-1B, 4-1C, and 4-1D in Modification 1 of Basic Configuration 4.

[0473] (Placement method 4-1A) For example, a transmitting array antenna consists of a first transmitting antenna group and a second transmitting antenna group. Furthermore, each transmitting antenna group is 2D in the horizontal direction. H , vertically D VIt includes multiple transmitting antenna elements arranged linearly in a diagonal downward direction to the right with a certain antenna spacing.

[0474] Furthermore, relative to the first group of transmitting antennas, the second group of transmitting antennas is positioned to the left, D H , downwards in 2D V They are positioned with an offset.

[0475] Here, the number of transmitting antennas included in the first group of transmitting antennas is "N". TxLowerRightGr1_ANT For example, N TxLowerRightGr1_ANT The value is ≥2. Also, the number of transmitting antennas included in the second group of transmitting antennas is "N". TxLowerRightGr2_ANT For example, N TxLowerRightGr2_ANT It is ≥ 2.

[0476] Furthermore, the receiving array antenna is composed of a first receiving antenna group and a second receiving antenna group. In addition, each receiving antenna group is 2D in the horizontal direction. H , vertically D V It includes multiple receiving antenna elements arranged linearly in an upward-right direction at intervals of .

[0477] Furthermore, relative to the first receiving antenna group, the second receiving antenna group is positioned to the right, D H , downwards in 2D V They are positioned with an offset.

[0478] Here, the number of receiving antennas included in the first receiving antenna group is "N". RxUpperRightGr1_ANT For example, N RxUpperRightGr1_ANT The value is ≥2. Also, the number of receiving antennas included in the second receiving antenna group is "N". RxUpperRightGr2_ANT For example, N RxUpperRightGr2_ANT It is ≥ 2.

[0479] Figure 72 shows N TxLowerRightGr1_ANT =4(Tx#2,Tx#4,Tx#6,Tx#8), N TxLowerRightGr2_ANT =4(Tx#1,Tx#3,Tx#5,Tx#7), N RxUpperRightGr1_ANT =2(Rx#2,Rx#4), N RxUpperRightGr2_ANTExamples of MIMO array configurations and virtual receiver array configurations for the case where =2(Rx#1,Rx#3) are shown.

[0480] Also, Figure 73 shows N TxLowerRightGr1_ANT =2(Tx#2,Tx#4), N TxLowerRightGr2_ANT =2(Tx#1,Tx#3), N RxUpperRightGr1_ANT =3(Rx#2,Rx#4,Rx#6), N RxUpperRightGr2_ANT This shows an example of a MIMO array configuration and a virtual receiver array configuration for the case where Rx#1, Rx#3, Rx#5 = 3.

[0481] Also, Figure 74 shows N TxLowerRightGr1_ANT =4(Tx#2,Tx#4,Tx#6,Tx#8), N TxLowerRightGr2_ANT =4(Tx#1,Tx#3,Tx#5,Tx#7), N RxUpperRightGr1_ANT =3(Rx#2,Rx#4,Rx#6), N RxUpperRightGr2_ANT This shows an example of a MIMO array configuration and a virtual receiver array configuration for the case where Rx#1, Rx#3, Rx#5 = 3.

[0482] In each MIMO array configuration shown in Figures 72, 73, and 74, for example, D H and D V By setting the value to approximately 0.5λ, the horizontal and vertical element sizes of the transmitting antenna 106 and the receiving antenna 202 can be designed to be approximately 1λ or larger.

[0483] Furthermore, for example, in the virtual receiving arrays shown in Figures 72, 73, and 74, some elements of each virtual array are placed in overlapping positions, but the aperture length of the virtual receiving array can be expanded, thereby improving the angular resolution. Note that in Figures 72 and 73, there is no overlap of virtual array elements, while in Figure 74, virtual array elements overlap in two places.

[0484] Furthermore, the virtual array elements located near the center of each virtual receiving array shown in Figures 72, 73, and 74 are D H , D VThey can be densely arranged at intervals. However, as shown in Figures 72, 73, and 74, elements at positions corresponding to some coordinates are missing near the center of each virtual receiving array. However, the radar device 10 surrounds the area around the missing positions, D H , D V By performing interpolation processing using the received signals of virtual array elements that are densely arranged at intervals, the received signal of the missing element can be approximately received.

[0485] Furthermore, the number of virtual array elements densely arranged near the center of each virtual receiving array shown in Figures 72, 73, and 74 is N TxLowerRightGr1_ANT , N TxLowerRightGr2_ANT N RxUpperRightGr1_ANT , N RxUpperRightGr2_ANT It increases depending on the situation.

[0486] For example, in a virtual receiving array, in the horizontal direction, (N TxLowerRightGr1_ANT +N TxLowerRightGr2_ANT +N RxUpperRightGr1_ANT +N RxUpperRightGr2_ANT The virtual array element of )-5 is D H They are spaced apart, and in the vertical direction, they are 0.5 × (N TxLowerRightGr1_ANT +N TxLowerRightGr2_ANT +N RxUpperRightGr1_ANT +N RxUpperRightGr2_ANT The virtual array element of )-1 is D V They are arranged at intervals. In a virtual receiver array, D H , D V The more densely spaced virtual array elements there are, the better the reduction effect on grating lobes and side lobes can be achieved.

[0487] Also, N TxLowerRightGr1_ANT , N TxLowerRightGr2_ANT N RxUpperRightGr1_ANT , N RxUpperRightGr2_ANT The larger the value, the greater the number of virtual array elements arranged horizontally and vertically, which allows for an expansion of the aperture length of the virtual receiving array in the horizontal and vertical directions, thereby improving the angular resolution in the horizontal and vertical directions.

[0488] Figure 75 shows, for example, a MIMO array configuration (Nt=8) with a number of transmitting antennas 106 and a number of receiving antennas 202 Na=6, as shown in Figure 74.TxLowerRightGr1_ANT =N TxLowerRightGr2_ANT =4, N RxUpperRightGr1_ANT =N RxUpperRightGr2_ANT =3, D H =0.5λ, D V An example of the direction estimation result when using the beamformer method as the direction estimation algorithm for the direction estimation unit 214, with (=0.5λ) used, is shown. Note that the directivity of each antenna is calculated as omnidirectional.

[0489] Figure 75 plots the output of the estimated direction of arrival evaluation function values ​​within a range of ±90 degrees horizontally and ±90 degrees vertically, when the target true value is set to 0 degrees horizontally and 0 degrees vertically.

[0490] In Figure 75, it can be seen that the grating lobe is reduced in directions other than horizontal 0 degrees and vertical 0 degrees of the target true value, compared to, for example, Figure 1A. For example, in Figure 75, the ratio of the peak power value of the highest side lobe excluding the main lobe to the peak power value of the main lobe in the horizontal 0 degrees and vertical 0 degrees directions (PSLR) is approximately 0.28, for example, the configuration of basic arrangement 4 shown in Figure 69 (N TxLowerRightGr1_ANT =N TxLowerRightGr2_ANT =N RxUpperRightGr1_ANT =N RxUpperRightGr2_ANT Compared to the case where =2 (see, for example, Figure 71), N TxLowerRightGr1_ANT , N TxLowerRightGr2_ANT , N RxUpperRightGr1_ANT , N RxUpperRightGr2_ANT By increasing the value, an improvement in the reduction effect of the side lobes can be observed. Also, in Figure 75, compared to Figure 71, the peak of the main lobe is sharper, and N TxLowerRightGr1_ANT , N TxLowerRightGr2_ANT , N RxUpperRightGr1_ANT , N RxUpperRightGr2_ANT The increase in [the specified value] indicates an improvement in angular resolution.

[0491] Note N TxLowerRightGr1_ANT , N TxLowerRightGr2_ANT , N RxUpperRightGr1_ANT , N RxUpperRightGr2_ANTIncreasing this value allows for a wider aperture length in the horizontal virtual array than in the vertical, resulting in a MIMO array configuration that makes it easier to improve the horizontal angular resolution compared to the vertical angular resolution.

[0492] (Placement method 4-1B) Arrangement method 4-1B describes a case where the aperture length of the virtual receiving array is extended vertically rather than horizontally. This results in a MIMO array configuration that can improve the vertical angular resolution compared to the horizontal angular resolution.

[0493] For example, a transmitting array antenna consists of a first transmitting antenna group and a second transmitting antenna group. Furthermore, each transmitting antenna group is positioned horizontally in a D-axis direction. H , vertically 2D V It includes multiple transmitting antenna elements arranged linearly in an upward-right direction with an antenna spacing of .

[0494] Furthermore, relative to the first group of transmitting antennas, the second group of transmitting antennas is 2D to the right. H , downwards D V They are positioned with an offset.

[0495] Here, the number of transmitting antennas included in the first group of transmitting antennas is "N". TxUpperRightGr1_ANT For example, N TxUpperRightGr1_ANT The value is ≥2. Also, the number of transmitting antennas included in the second group of transmitting antennas is "N". TxUpperRightGr2_ANT For example, N TxUpperRightGr2_ANT It is ≥ 2.

[0496] Furthermore, the receiving array antenna is composed of a first receiving antenna group and a second receiving antenna group. In addition, each receiving antenna group is positioned horizontally in the D direction. H , vertically 2D V It includes multiple receiving antenna elements arranged linearly in a diagonal downward direction to the right with a certain antenna spacing.

[0497] Furthermore, relative to the first receiving antenna group, the second receiving antenna group is 2D to the left. H , downwards DV They are positioned with an offset.

[0498] Here, the number of receiving antennas included in the first receiving antenna group is "N". RxLowerRightGr1_ANT For example, N RxLowerRightGr1_ANT The value is ≥2. Also, the number of receiving antennas included in the second receiving antenna group is "N". RxLowerRightGr1_ANT For example, N RxLowerRightGr2_ANT It is ≥ 2.

[0499] Figure 76 shows N TxUpperRightGr1_ANT =4(Tx#2,Tx#4,Tx#6,Tx#8), N TxUpperRightGr2_ANT =4(Tx#1,Tx#3,Tx#5,Tx#7), N RxLowerRightGr1_ANT =2(Rx#4,Rx#3), N RxLowerRightGr2_ANT Examples of MIMO array configurations and virtual receiver array configurations for the case where =2(Rx#2,Rx#1) are shown.

[0500] Figure 77 shows N TxUpperRightGr1_ANT =2(Tx#2,Tx#4), N TxUpperRightGr2_ANT =2(Tx#1,Tx#3), N RxLowerRightGr1_ANT =3(Rx#2,Rx#4,Rx#6), N RxLowerRightGr2_ANT Examples of MIMO array configurations and virtual receiver array configurations for the case (Rx#1,Rx#3,Rx#5)=3 are shown.

[0501] Figure 78 shows N TxUpperRightGr1_ANT =4(Tx#2,Tx#4,Tx#6,Tx#8), N TxUpperRightGr2_ANT =4(Tx#1,Tx#3,Tx#5,Tx#7), N RxLowerRightGr1_ANT =3(Rx#2,Rx#4,Rx#6), N RxLowerRightGr2_ANT This shows an example of a MIMO array configuration and a virtual receiver array configuration for the case where Rx#1, Rx#3, Rx#5 = 3.

[0502] In the MIMO array configurations shown in Figures 76, 77, and 78, for example, D H and D V By setting the value to approximately 0.5λ, the horizontal and vertical element sizes of the transmitting antenna 106 and the receiving antenna 202 can be designed to be approximately 1λ or larger.

[0503] Furthermore, for example, in the virtual receiving arrays shown in Figures 76, 77, and 78, some elements of each virtual array are placed in overlapping positions, but the aperture length of the virtual receiving array can be expanded, thereby improving the angular resolution. Note that in Figures 76 and 77, there is no overlap of virtual array elements, while in Figure 78, virtual array elements overlap in two places.

[0504] Furthermore, the virtual array elements located near the center of each virtual receiving array shown in Figures 76, 77, and 78 are D H , D V They can be densely arranged at intervals. However, as shown in Figures 76, 77, and 78, elements at positions corresponding to some coordinates are missing near the center of each virtual receiving array. However, the radar device 10 surrounds the area around these missing positions, D H , D V By performing interpolation processing using the received signals of virtual array elements that are densely arranged at intervals, the received signal of the missing element can be approximately received.

[0505] Furthermore, the number of virtual array elements densely arranged near the center of each virtual receiving array shown in Figures 76, 77, and 78 is N TxUpperRightGr1_ANT , N TxUpperRightGr2_ANT N RxLowerRightGr1_ANT , N RxLowerRightGr2_ANT It increases depending on the situation.

[0506] For example, in a virtual receiving array, the horizontal direction is 0.5 × (N TxUpperRightGr1_ANT +N TxUpperRightGr2_ANT +N RxLowerRightGr1_ANT +N RxLowerRightGr2_ANT The virtual array element of )-1 is D H They are spaced apart, and in the vertical direction (N TxUpperRightGr1_ANT +N TxUpperRightGr2_ANT +N RxLowerRightGr1_ANT +N RxLowerRightGr2_ANT The virtual array element of )-5 is D V They are arranged at intervals. In a virtual receiver array, D H , D VThe more densely spaced virtual array elements there are, the better the reduction effect on grating lobes and side lobes can be achieved.

[0507] Also, N TxUpperRightGr1_ANT , N TxUpperRightGr2_ANT N RxLowerRightGr1_ANT , N RxLowerRightGr2_ANT The larger the value, the greater the number of virtual array elements arranged horizontally and vertically, which allows for an expansion of the aperture length of the virtual receiving array in the horizontal and vertical directions, thereby improving the angular resolution in the horizontal and vertical directions.

[0508] Figure 79 shows, for example, a MIMO array configuration (Nt=8) with a number of transmitting antennas 106 and a number of receiving antennas 202 Na=6, as shown in Figure 78. TxUpperRightGr1_ANT =N TxUpperRightGr2_ANT =4, N RxLowerRightGr1_ANT =N RxLowerRightGr2_ANT =3, D H =0.5λ, D V An example of the direction estimation result when using the beamformer method as the direction estimation algorithm for the direction estimation unit 214, with (=0.5λ) used, is shown. Note that the directivity of each antenna is calculated as omnidirectional.

[0509] Figure 79 plots the output of the estimated direction of arrival evaluation function values ​​within a range of ±90 degrees horizontally and ±90 degrees vertically, when the target true value is set to 0 degrees horizontally and 0 degrees vertically.

[0510] In Figure 79, it can be seen that the grating lobe is reduced in directions other than horizontal 0 degrees and vertical 0 degrees of the target true value, compared to, for example, Figure 1A. For example, in Figure 79, the ratio of the peak power value of the highest side lobe excluding the main lobe to the peak power value of the main lobe in the horizontal 0 degrees and vertical 0 degrees directions (PSLR) is approximately 0.28, for example, the configuration of basic arrangement 4 shown in Figure 69 (N TxUpperRightGr1_ANT =N TxUpperRightGr2_ANT =N RxLowerRightGr1_ANT =N RxLowerRightGr2_ANT In the case of = (see, for example, Figure 71), N TxUpperRightGr1_ANT , N TxUpperRightGr2_ANT , N RxLowerRightGr1_ANT, N RxLowerRightGr2_ANT By increasing the value, an improvement in the reduction effect of the side lobes can be observed. Also, in Figure 79, compared to Figure 71, the peak of the main lobe is sharper, and N TxUpperRightGr1_ANT , N TxUpperRightGr2_ANT , N RxLowerRightGr1_ANT , N RxLowerRightGr2_ANT The increase in [the specified value] indicates an improvement in angular resolution.

[0511] Note N TxUpperRightGr1_ANT , N TxUpperRightGr2_ANT N RxLowerRightGr1_ANT , N RxLowerRightGr2_ANT Increasing this value allows for a greater extension of the aperture length of the virtual array in the vertical direction compared to the horizontal direction, resulting in a MIMO array configuration that makes it easier to improve the vertical angular resolution compared to the horizontal angular resolution.

[0512] (Placement method 4-1C) Arrangement method 4-1C is a combination of arrangement methods 4-1A and 4-1B.

[0513] For example, a transmitting array antenna consists of a first transmitting antenna group and a second transmitting antenna group. Furthermore, each transmitting antenna group is 2D in the horizontal direction. H , vertically D V It includes multiple transmitting antenna elements arranged linearly in a diagonal downward direction to the right with a certain antenna spacing.

[0514] Furthermore, relative to the first group of transmitting antennas, the second group of transmitting antennas is positioned to the left, D H , downwards in 2D V They are positioned with an offset.

[0515] Here, the number of transmitting antennas included in the first group of transmitting antennas is "N". TxLowerRightGr1_ANT For example, N TxLowerRightGr1_ANT The value is ≥2. Also, the number of transmitting antennas included in the second group of transmitting antennas is "N". TxLowerRightGr2_ANT For example, N TxLowerRightGr2_ANT It is ≥ 2.

[0516] Furthermore, for example, a receiving array antenna is composed of a first receiving antenna group and a second receiving antenna group. Also, each receiving antenna group is positioned horizontally in D H , vertically 2D V It includes multiple receiving antenna elements arranged linearly in a diagonal downward direction to the right with a certain antenna spacing.

[0517] Furthermore, relative to the first receiving antenna group, the second receiving antenna group is 2D to the left. H , downwards D V They are positioned with an offset.

[0518] Here, the number of receiving antennas included in the first receiving antenna group is "N". RxLowerRightGr1_ANT For example, N RxLowerRightGr1_ANT The value is ≥2. Also, the number of receiving antennas included in the second receiving antenna group is "N". RxLowerRightGr2_ANT For example, N RxLowerRightGr2_ANT It is ≥ 2.

[0519] Figure 80 shows N TxLowerRightGr1_ANT =4(Tx#2,Tx#4,Tx#6,Tx#8), N TxLowerRightGr2_ANT =4(Tx#1,Tx#3,Tx#5,Tx#7), N RxLowerRightGr1_ANT =4(Rx#2,Rx#4,Rx#6,Rx#8), N RxLowerRightGr2_ANT Examples of MIMO array configurations and virtual receiver array configurations for the case of =4(Rx#1,Rx#3,Rx#5,Rx#7) are shown.

[0520] In the MIMO array configuration shown in Figure 80, for example, D H and D V By setting the value to approximately 0.5λ, the horizontal and vertical element sizes of the transmitting antenna 106 and the receiving antenna 202 can be designed to be approximately 1λ or larger.

[0521] Furthermore, in the virtual receiving array shown in Figure 80, some elements of each virtual array are positioned in overlapping locations, but the aperture length of the virtual receiving array can be expanded, thereby improving the angular resolution. Note that in Figure 80, the virtual array elements overlap at one location.

[0522] Furthermore, the virtual array element located near the center of the virtual receiving array shown in Figure 80 is D H , D V They can be densely arranged at intervals. However, as shown in Figure 80, elements at positions corresponding to some coordinates are missing near the center of each virtual receiving array. However, the radar device 10 surrounds the area around these missing positions, D H , D V By performing interpolation processing using the received signals of virtual array elements that are densely arranged at intervals, the received signal of the missing element can be approximately received.

[0523] Furthermore, the number of virtual array elements densely arranged near the center of each virtual receiving array shown in Figure 80 is N TxLowerRightGr1_ANT , N TxLowerRightGr2_ANT N RxLowerRightGr1_ANT , N RxLowerRightGr2_ANT It increases depending on the situation.

[0524] For example, in a virtual receiving array, the horizontal direction is 0.5 × (N TxLowerRightGr1_ANT +N TxLowerRightGr2_ANT +N RxLowerRightGr1_ANT +N RxLowerRightGr2_ANT A virtual array element of )+1 is D H They are spaced apart, and in the vertical direction, they are 0.5 × (N TxLowerRightGr1_ANT +N TxLowerRightGr2_ANT +N RxLowerRightGr1_ANT +N RxLowerRightGr2_ANT A virtual array element of )+1 is D V They are arranged at intervals. In a virtual receiver array, D H , D V The more densely spaced virtual array elements there are, the better the reduction effect on grating lobes and side lobes can be achieved.

[0525] Also, N TxLowerRightGr1_ANT , N TxLowerRightGr2_ANT N RxLowerRightGr1_ANT , N RxLowerRightGr2_ANT The larger the value, the greater the number of virtual array elements arranged horizontally and vertically, which allows for an expansion of the aperture length of the virtual receiving array in the horizontal and vertical directions, thereby improving the angular resolution in the horizontal and vertical directions.

[0526] (Placement method 4-1D) Arrangement method 4-1D is a combination of arrangement methods 4-1A and 4-1B.

[0527] For example, a transmitting array antenna consists of a first transmitting antenna group and a second transmitting antenna group. Furthermore, each transmitting antenna group is 2D in the horizontal direction. H , vertically D V It includes multiple transmitting antenna elements arranged linearly in an upward-right direction with an antenna spacing of .

[0528] Furthermore, relative to the first group of transmitting antennas, the second group of transmitting antennas is 2D to the right. H , downwards D V They are positioned with an offset.

[0529] Here, the number of transmitting antennas included in the first group of transmitting antennas is "N". TxUpperRightGr1_ANT For example, N TxUpperRightGr1_ANT The value is ≥2. Also, the number of transmitting antennas included in the second group of transmitting antennas is "N". TxUpperRightGr2_ANT For example, N TxUpperRightGr2_ANT It is ≥ 2.

[0530] Furthermore, for example, a receiving array antenna is composed of a first receiving antenna group and a second receiving antenna group. Also, each receiving antenna group is 2D in the horizontal direction. H , vertically D V It includes multiple receiving antenna elements arranged linearly in an upward-right direction with an antenna spacing of .

[0531] Furthermore, relative to the first receiving antenna group, the second receiving antenna group is positioned to the right, D H , downwards in 2D V They are positioned with an offset.

[0532] Here, the number of receiving antennas included in the first receiving antenna group is "N". RxUpperRightGr1_ANT For example, N RxUpperRightGr1_ANT The value is ≥2. Also, the number of receiving antennas included in the second receiving antenna group is "N". RxUpperRightGr2_ANT For example, NRxUpperRightGr2_ANT It is ≥ 2.

[0533] Figure 81 shows N TxUpperRightGr1_ANT =4(Tx#2,Tx#4,Tx#6,Tx#8), N TxUpperRightGr2_ANT =4(Tx#1,Tx#3,Tx#5,Tx#7), N RxUpperRightGr1_ANT =4(Rx#2,Rx#4,Rx#6,Rx#8), N RxLUpperRightGr2_ANT Examples of MIMO array configurations and virtual receiver array configurations for the case of =4(Rx#1,Rx#3,Rx#5,Rx#7) are shown.

[0534] In the MIMO array configuration shown in Figure 81, for example, D H and D V By setting the value to approximately 0.5λ, the horizontal and vertical element sizes of the transmitting antenna 106 and the receiving antenna 202 can be designed to be approximately 1λ or larger.

[0535] Furthermore, in the virtual receiving array shown in Figure 81, some elements of each virtual array are positioned in overlapping locations, but the aperture length of the virtual receiving array can be expanded, thereby improving the angular resolution. Note that in Figure 81, the virtual array elements overlap at one location.

[0536] Furthermore, the virtual array element located near the center of the virtual receiving array shown in Figure 81 is D H , D V They can be densely arranged at intervals. However, as shown in Figure 81, near the center of each virtual receiving array, elements at positions corresponding to some coordinates are missing. However, the radar device 10 surrounds the area around these missing positions, D H , D V By performing interpolation processing using the received signals of virtual array elements that are densely arranged at intervals, the received signal of the missing element can be approximately received.

[0537] Furthermore, the number of virtual array elements densely arranged near the center of each virtual receiving array shown in Figure 81 is N TxUpperRightGr1_ANT , N TxLUpperRightGr2_ANT N RxUpperRightGr1_ANT , N RxUpperRightGr2_ANT It increases depending on the situation.

[0538] For example, in a virtual receiving array, the horizontal direction is 0.5 × (N TxUpperRightGr1_ANT +N TxUpperRightGr2_ANT +N RxUpperRightGr1_ANT +N RxUpperRightGr2_ANT A virtual array element of )+1 is D H They are spaced apart, and in the vertical direction, they are 0.5 × (N TxUpperRightGr1_ANT +N TxUpperRightGr2_ANT +N RxUpperRightGr1_ANT +N RxUpperRightGr2_ANT The virtual array element of ) is D V They are arranged at intervals. In a virtual receiver array, D H , D V The more densely spaced virtual array elements there are, the better the reduction effect on grating lobes and side lobes can be achieved.

[0539] Also, N TxUpperRightGr1_ANT , N TxUpperRightGr2_ANT N RxUpperRightGr1_ANT , N RxUpperRightGr2_ANT The larger the value, the greater the number of virtual array elements arranged horizontally and vertically, which allows for an expansion of the aperture length of the virtual receiving array in the horizontal and vertical directions, thereby improving the angular resolution in the horizontal and vertical directions.

[0540] The antenna placement methods 4-1A, 4-1B, 4-1C, and 4-1D in Modification 1 of Basic Arrangement 4 have been described above.

[0541] In addition, arrangement methods 4-1A, 4-1B, 4-1C, and 4-1D describe the case where the transmitting array antenna is composed of a first transmitting antenna group and a second transmitting antenna group. However, the number of transmitting antenna groups included in the transmitting array antenna is N. TxGroup The configuration may be 3 or more. In this case, the transmitting antenna group of the (ntx-1)th ntx is arranged according to one of the arrangement rules 4-1A, 4-1B, 4-1C, and 4-1D relative to the transmitting antenna group of the (ntx-1). Here, ntx = 1, ..., N TxGroup That is the case.

[0542] Similarly, arrangement methods 4-1A, 4-1B, 4-1C, and 4-1D were described in which the receiving array antenna consists of a first receiving antenna group and a second receiving antenna group. However, the number of receiving antenna groups N RxGroup The configuration may have three or more elements. In this case, the receiving antenna group of the nrx is arranged relative to the receiving antenna group of the (nrx-1) according to one of the arrangement rules 4-1A, 4-1B, 4-1C, and 4-1D. Here, nrx = 1, ..., N RxGroup That is the case.

[0543] Figure 82 shows, as an example, the number of transmitting antenna groups N in arrangement method 4-1B. TxGroup = 3, Number of receiving antenna groups N RxGroup Let =3, N TxUpperRightGr1_ANT =3(Tx#3,Tx#6,Tx#9), N TxUpperRightGr2_ANT =3(Tx#2,Tx#5,Tx#8), N TxUpperRightGr3_ANT =3(Tx#1,Tx#4,Tx#7), N RxLowerRightGr1_ANT =3(Rx#7,Rx#8,Rx#9), N RxLowerRightGr2_ANT =3(Rx#4,Rx#5,Rx#6), N RxLowerRightGr3_ANT This shows an example of a MIMO array configuration and a virtual receiver array configuration for the case where Rx#1, Rx#2, Rx#3 = 3.

[0544] For example, in the MIMO array configuration shown in Figure 82, D H and D V By setting the value to approximately 0.5λ, the horizontal and vertical element sizes of the transmitting antenna 106 and the receiving antenna 202 can be designed to be approximately 1λ or larger.

[0545] Furthermore, in the virtual receiving array shown in Figure 82, some elements of each virtual array are positioned in overlapping locations, but the aperture length of the virtual receiving array can be expanded, thereby improving the angular resolution. Note that in Figure 82, the virtual array elements overlap in eight locations.

[0546] Furthermore, the virtual array element located near the center of the virtual receiving array shown in Figure 82 is D H , D VThey can be densely arranged at intervals. However, as shown in Figure 82, near the center of the virtual receiving array, elements at positions corresponding to some coordinates are missing. However, the radar device 10 surrounds the area around these missing positions, D H , D V By performing interpolation processing using the received signals of virtual array elements that are densely arranged at intervals, the received signal of the missing element can be approximately received.

[0547] Furthermore, the number of virtual array elements densely arranged near the center of each virtual receiving array shown in Figure 82 is N TxGroup , N RxGroup It increases depending on the situation.

[0548] <Modification 2 of Basic Arrangement 4> In Modification 2 of Basic Configuration 4, the arrangement of the 4-element transmitting array antenna and the arrangement of the 4-element receiving array antenna shown in Basic Configuration 4 are each considered as "basic sets," and a MIMO array configuration in which the placement positions of multiple basic sets are offset is described.

[0549] In the configuration shown below, the offset of the basic set of transmitting array antennas to their horizontal and vertical positions, or the offset of the basic set of receiving array antennas to their horizontal and vertical positions, is such that there are no overlapping elements in the virtual receiving array configuration, and more virtual array elements are located near the center of the virtual receiving array. V or D H The elements may be set to be densely spaced. However, this is not the only way to achieve this; for example, if the number of arrangements with unequal spacing in the virtual receiver array arrangement is increased, or if the number of arrangements where virtual array elements overlap in the virtual receiver array arrangement is increased, this can also be achieved by adjusting the offset of the arrangement positions.

[0550] Figure 83 shows the number of basic sets of transmitting array antennas, N. TxBaseSet Let = 2, and the number of basic sets of receiving array antennas be N. RxBaseSetThe following shows an example of MIMO array configuration when = 1, and an example of a virtual receive array configuration. In Figure 83, the horizontal offset of the second basic set (e.g., Tx#5, Tx#6, Tx#7, and Tx#8) relative to the first basic set (e.g., Tx#1, Tx#2, Tx#3, and Tx#4) is D. Hoffset_TxBaseSet2 =5D H And the offset D of the position in the vertical direction Voffset_TxBaseSet2 Let = 0. As shown in Figure 83, by arranging the two basic sets of transmitting array antennas with a horizontal offset, D is set horizontally. H The number of virtual array elements arranged closely together can be increased, improving the horizontal angular resolution.

[0551] Figure 84 shows the number of basic sets of transmitting array antennas, N. TxBaseSet Let = 2, and the number of basic sets of receiving array antennas be N. RxBaseSet The following shows an example of MIMO array configuration and a virtual receive array configuration when = 1. In Figure 84, the horizontal offset of the second basic set (Tx#5, Tx#6, Tx#7, Tx#8) relative to the first basic set (e.g., Tx#1, Tx#2, Tx#3, and Tx#4) is D. Hoffset_TxBaseSet2 Set = 0, and the offset D of the vertical placement position. Voffset_TxBaseSet2 =5D V As shown in Figure 84, by arranging the two basic sets of transmitting array antennas with a vertical offset, the vertical direction D V The number of virtual array elements arranged closely together can be increased, improving the horizontal angular resolution.

[0552] Figure 85 shows the number of basic sets of transmitting array antennas, N. TxBaseSet Let = 1, and the number of basic sets of receiving array antennas be N. RxBaseSetThe following shows an example of MIMO array configuration when = 2, and an example of a virtual receiver array configuration. In Figure 85, the horizontal offset of the second basic set (Rx#5, Rx#6, Rx#7, Rx#8) relative to the first basic set (e.g., Rx#1, Rx#2, Rx#3, and Rx#4) is D. Hoffset_RxBaseSet2 =5D H And the offset D of the position in the vertical direction Voffset_RxBaseSet2 Let = 0. As shown in Figure 85, by arranging the two basic sets of receiving array antennas with a horizontal offset, D is set horizontally. H The number of virtual array elements arranged closely together can be increased, improving the horizontal angular resolution.

[0553] Figure 86 shows the number of basic sets of transmitting array antennas, N. TxBaseSet Let = 1, and the number of basic sets of receiving array antennas be N. RxBaseSet The following shows an example of MIMO array configuration and a virtual receiver array configuration when = 2. In Figure 86, the horizontal offset of the second basic set (Rx#5, Rx#6, Rx#7, Rx#8) relative to the first basic set (e.g., Rx#1, Rx#2, Rx#3, and Rx#4) is D. Hoffset_RxBaseSet2 Set = 0, and the offset D of the vertical placement position. Voffset_RxBaseSet2 =5D V As shown in Figure 86, by arranging the two basic sets of receiving array antennas with a vertical offset, the vertical direction D V The number of virtual array elements arranged closely together can be increased, improving the vertical angular resolution.

[0554] Figure 87 shows the number of basic sets of transmitting array antennas, N. TxBaseSet Let = 2, and the number of basic sets of receiving array antennas be N. RxBaseSetThe following shows an example of a MIMO array configuration and a virtual receiver array configuration when = 2. In Figure 87, the horizontal offset of the second basic set (Tx#5, Tx#6, Tx#7, Tx#8) relative to the first basic set of transmitting array antennas (e.g., Tx#1, Tx#2, Tx#3, and Tx#4) is D. Hoffset_TxBaseSet2 =8D H And the offset D of the position in the vertical direction Voffset_TxBaseSet2 Let = 0. Also, in Figure 87, the horizontal offset of the second basic set (Rx#5, Rx#6, Rx#7, Rx#8) relative to the first basic set (e.g., Rx#1, Rx#2, Rx#3, and Rx#4) of the receiving array antenna is D. Hoffset_RxBaseSet2 =5D H And the offset D of the position in the vertical direction Voffset_RxBaseSet2 Let = 0. As shown in Figure 87, by arranging the two basic sets of transmitting array antennas with a horizontal offset, and arranging the two basic sets of receiving array antennas with a horizontal offset, D is set horizontally. H The number of virtual array elements densely arranged at intervals can be further increased, for example, compared to Figure 83 or Figure 85, thereby further improving the horizontal angular resolution.

[0555] Figure 88A shows that the number of basic sets of transmitting array antennas is N. TxBaseSet Let = 4, and the number of basic sets of receiving array antennas be N. RxBaseSet Figure 88B shows an example of a MIMO array configuration when =4, and Figure 88B shows an example of a virtual receiver array configuration.

[0556] In Figure 88A, the horizontal offset of the second basic set (Tx#5, Tx#6, Tx#7, Tx#8) relative to the first basic set (e.g., Tx#1, Tx#2, Tx#3, and Tx#4) of the transmitting array antenna is D. Hoffset_TxBaseSet2 =8D H And the offset D of the position in the vertical direction Voffset_TxBaseSet2 Set = 0, and the horizontal offset of the third basic set (Tx#9, Tx#10, Tx#11, Tx#12) is D.Hoffset_TxBaseSet3 Set = 0, and the offset D of the vertical placement position. Voffset_TxBaseSet3 =5D V Let D be the horizontal offset of the fourth basic set (Tx#13, Tx#14, Tx#15, Tx#16). Hoffset_TxBaseSet4 =8D H And the offset D of the position in the vertical direction Voffset_TxBaseSet4 =5D V Let's assume that.

[0557] Furthermore, in Figure 88A, the horizontal offset of the second basic set (Rx#5, Rx#6, Rx#7, Rx#8) relative to the first basic set (e.g., Rx#1, Rx#2, Rx#3, and Rx#4) of the receiving array antenna is D. Hoffset_RxBaseSet2 =5D H And the offset D of the position in the vertical direction Voffset_RxBaseSet2 Set = 0, and set the horizontal offset of the third base set (Rx#9, Rx#10, Rx#11, Rx#12) to D. Hoffset_RxBaseSet3 Set = 0, and the offset D of the vertical placement position. Voffset_RxBaseSet3 =8D V Let D be the horizontal offset of the fourth basic set (Rx#13, Rx#14, Rx#15, Rx#16). Hoffset_RxBaseSet4 =5D H And the offset D of the position in the vertical direction Voffset_RxBaseSet4 =8D V Let's assume that.

[0558] As shown in Figures 88A and 88B, by arranging the basic set of the transmitting array antennas with a horizontal offset, and arranging the basic set of the receiving array antennas with a horizontal offset, the horizontal direction D H The number of virtual array elements densely arranged at intervals can be further increased, for example, compared to Figure 83 or Figure 85, thereby further improving the horizontal angular resolution. (Note that in Figure 88, the virtual array elements overlap at 8 locations.)

[0559] Similarly, as shown in Figures 88A and 88B, by arranging the basic set of transmitting array antennas with a vertical offset, and arranging the basic set of receiving array antennas with a vertical offset, D is generated vertically. V The number of virtual array elements densely arranged at intervals can be further increased, for example, compared to Figure 84 or Figure 86, thereby further improving the vertical angular resolution.

[0560] In Modification 2, the case where the antenna configuration of Basic Configuration 4 is used as the basic set was explained, but the basic set is not limited to the antenna configuration of Basic Configuration 4; for example, the antenna configuration of Modification 1 of Basic Configuration 4 may also be used.

[0561] Also, the number of basic sets included in the transmitting array antenna and the receiving array antenna (N TxBaseSet , N RxBaseSet The value is not limited to the above example and may be any other value.

[0562] <Basic layout 5> Figure 89 shows an example of the arrangement of the transmitting antenna 106 and receiving antenna 202 in the basic configuration 5, and an example of the arrangement of the virtual receiving array.

[0563] (1) Arrangement of transmitting and receiving antennas In Figure 89, the number of transmitting antennas 106 in the transmitting array antenna is set to Nt = 4 (Tx#1, Tx#2, Tx#3 and Tx#4), and the number of receiving antennas 202 in the receiving array antenna is set to Na = 4 (Rx#1, Rx#2, Rx#3 and Rx#4).

[0564] The transmitting array antenna shown in Figure 89 consists of, for example, a "first transmitting antenna group" (Tx#2, Tx#4 in Figure 89) and a "second transmitting antenna group" (Tx#1, Tx#3 in Figure 89). Each transmitting antenna group has an antenna spacing of D in the horizontal direction. H And the antenna spacing is D in the vertical direction. V It includes two transmitting antenna elements. In each of the transmitting antenna groups shown in Figure 89, adjacent transmitting antennas are in the horizontal direction DH They are spaced apart and arranged vertically in a D direction. V They are arranged at intervals of D. In other words, in Figure 89, the transmitting antennas included in each transmitting antenna group are arranged horizontally in the D direction. H , vertically D V The antennas are arranged in a straight line diagonally downward to the right (in other words, diagonally upward to the left) with this antenna spacing.

[0565] Furthermore, in Figure 89, the second transmitting antenna group is positioned 2D to the left in the horizontal direction relative to the first transmitting antenna group. H , downward in the vertical direction D V They are positioned with a staggered arrangement. In other words, the adjacent transmitting antenna groups shown in Figure 89 are positioned 2D horizontally. H The interval (in other words, D H (At intervals twice the number of), and vertically D V They are in a shifted relationship.

[0566] Furthermore, in Figure 89, the second transmitting antenna group is positioned horizontally to the left of the first transmitting antenna group, D H , downwards in the vertical direction 2D V They are positioned with an offset.

[0567] Furthermore, the receiving array antenna shown in Figure 89 is composed of, for example, a "first receiving antenna group" (Rx#2, Rx#4 in Figure 89) and a "second receiving antenna group" (Rx#1, Rx#3 in Figure 89). Each receiving antenna group has an antenna spacing of D in the horizontal direction. H And the antenna spacing is D in the vertical direction. V It includes two receiving antenna elements. In each receiving antenna group shown in Figure 89, adjacent receiving antennas are in the horizontal direction D H They are spaced apart and arranged vertically in a D direction. V They are arranged at intervals of D. In other words, in Figure 89, the transmitting antennas included in each receiving antenna group are arranged horizontally D H , vertically D V The antennas are arranged in a straight line diagonally upward to the right (in other words, diagonally downward to the left) with this antenna spacing.

[0568] Furthermore, in Figure 89, the second receiving antenna group is positioned 2D to the right in the horizontal direction relative to the first receiving antenna group. H , downward in the vertical direction D V They are positioned with a staggered arrangement. In other words, the adjacent receiving antenna groups shown in Figure 89 are positioned 2D horizontally. H The interval (in other words, D H (At intervals twice the number of), and vertically D V They are in a shifted relationship.

[0569] Furthermore, as shown in Figure 89, for example, each of the transmitting antennas Tx#1 to Tx#4 is positioned at a different location in the horizontal direction. Similarly, as shown in Figure 89, each of the receiving antennas Rx#1 to Rx#4 is positioned at a different location in the horizontal direction.

[0570] Furthermore, in the transmitting and receiving antenna arrangement shown in Figure 89, the respective positions of the transmitting antennas and the respective positions of the receiving antennas are symmetrical with respect to a line parallel to, for example, a horizontal or vertical line (in other words, they are inverted).

[0571] For example, let's assume that the horizontal direction (side direction) shown in Figure 89 corresponds to the X-axis, and the vertical direction (vertical direction) shown in Figure 89 corresponds to the Y-axis direction.

[0572] For example, in the antenna configuration shown in Figure 89, the position coordinates of the transmitting antenna 106 that constitutes the transmitting array antenna are the position coordinates (X) of the transmitting antenna Tx#1. T_#1 ,Y T_#1 ) is used as the reference point for the position coordinates (X) of the transmitting antenna Tx#2. T_#2 ,Y T_#2 )=(X T_#1 +2D H ,Y T_#1 +D V ), position coordinates (X) of transmitting antenna Tx#3 T_#3 ,Y T_#3 )=(X T_#1 +D H ,Y T_#1 -D V), and the position coordinates (X) of the transmitting antenna Tx#4. T_#4 ,Y T_#4 )=(X T_#1 +3D H ,Y T_#1 ) is expressed as.

[0573] Similarly, the position coordinates of receiving antenna 202, which constitutes the receiving array antenna, are the position coordinates (X) of receiving antenna Rx#1. R_#1 ,Y R_#1 ) is used as the reference point for the position coordinates (X) of the receiving antenna Rx#2. R_#2 ,Y R_#2 )=(X R_#1 -2D H ,Y R_#1 +D V ), position coordinates (X) of receiving antenna Rx#3 R_#3 ,Y R_#3 )=(X R_#1 +D H ,Y R_#1 +D V ), and the position coordinates (X) of the receiving antenna Rx#4. R_#4 ,Y R_#4 )=(X R_#1 -D H ,Y R_#1 +2D V ) is expressed as.

[0574] (2) Arrangement of virtual receiver array The arrangement of the virtual receiving array (virtual antennas VA#1 to VA#16) formed by the transmitting and receiving antenna arrangement shown in Figure 89 above has the following characteristics.

[0575] For example, the arrangement of the transmitting array antenna and the receiving array antenna shown in Figure 89 allows for the position coordinates (X) of the virtual receiving array VA#1~VA#16. V_#1 ,Y V_#1 )~(X V_#16 ,Y V_#16 The following applies to each of them. Note that here, VA#1 is represented as the position reference (0,0) of the virtual receive array. (0,0), (2D H , D V ), (D H , -DV ), (3D H , 0), (-2D H , D V ), (0, 2D V ), (-D H , 0), (D H , D V ), (D H , D V ), (3D H , 2D V ), (2D H , 0), (4D H , D V ), (-D H , 2D V ), (D H , 3D V ), (0, D V ), (2D H , 2D V ),

[0576] Thus, in the virtual receiver array arrangement shown in Figure 89, each virtual receiver array element is positioned at a different location without overlap, except for some virtual array elements (e.g., VA#8, #9). Therefore, the aperture length of the virtual receiver array can be expanded, the main lobe can be narrowed, and the angular resolution can be improved.

[0577] Furthermore, the virtual array elements VA#4, #11, #2, #16, #10, #7, #1, #15, #6, #13, VA#8, and #9, located near the center of the virtual receiving array shown in Figure 89, are in the horizontal direction D H Spacing, vertically D V They are densely arranged at intervals. For example, in Figure 89, interval D H and interval D V When the value is approximately 0.5λ, the virtual array elements VA#4, #11, #2, #16, #10, #7, #1, #15, #6, #13, VA#8, #9 are located in the horizontal direction D H = 0.5λ intervals, vertically in the direction D V They are arranged at 0.5λ intervals. This reduces grating lobes, similar to basic arrangement 1 (see, for example, Figure 8).

[0578] Furthermore, near the center of the virtual receiving array shown in Figure 89, the interval D H and interval D V An element is missing at a position corresponding to a coordinate surrounded by densely arranged virtual array elements. However, the radar device 10 surrounds the missing area, for example, with spacing D H and interval D V By performing interpolation processing using the received signals of densely arranged virtual array elements, the received signals of the elements in the missing locations can be approximately received.

[0579] Furthermore, for example, in the MIMO array configuration shown in Figure 89, the spacing D H and interval D V If the value is set to approximately 0.5λ, the horizontal and vertical element sizes of the transmitting antenna 106 and the receiving antenna 202 can be designed to be 1λ or larger.

[0580] This results in the lateral W direction of the transmitting antenna 106 and the receiving antenna 202. ANT The element size is D H If it is smaller than the specified size, an antenna of any size can be used in the vertical direction. For example, an antenna using eight elements arranged in a subarray, such as the one shown in Figure 25A, with eight planar patch antennas arranged vertically and one horizontally, can be applied to at least one of the antennas in the transmitting array antenna and receiving array antenna shown in Figure 89.

[0581] Note that the number of transmitting antennas included in the first transmitting antenna group (hereinafter referred to as "N") TxGroup1_ANT (represented as "N") and the number of transmitting antennas included in the second group of transmitting antennas (hereinafter referred to as "N") TxGroup2_ANT (represented as ") may have the same number or a difference of one antenna. For example, |N TxGroup1_ANT -N TxGroup2_ANT Let |= 0 or 1.

[0582] Similarly, the number of receiving antennas included in the first receiving antenna group (hereinafter referred to as "N") RxGroup1_ANT (represented as "N") and the number of receiving antennas included in the second receiving antenna group (hereinafter referred to as "N") RxGroup2_ANT(represented as ") may have the same number or a difference of one antenna. For example, |N RxGroup1_ANT -N RxGroup2_ANT Let |= 0 or 1.

[0583] Figures 90A and 90B show the number of transmitting antennas N included in the first transmitting antenna group. TxGroup1_ANT and the number of transmitting antennas N included in the second group of transmitting antennas TxGroup2_ANT There is a difference of one antenna between the two, and the number of receiving antennas included in the first receiving antenna group is N. RxGroup1_ANT The number of receiving antennas N included in the second receiving antenna group. RxGroup2_ANT Examples of MIMO array configurations and virtual receiver array configurations when the number of and are equal are shown.

[0584] As shown in Figures 90A and 90B, |N TxGroup1_ANT -N TxGroup2_ANT |=1 and |N RxGroup1_ANT -N RxGroup2_ANT When |=0, the MIMO array configuration has 3 transmitting antennas and 4 receiving antennas (N RxGroup1_ANT =N RxGroup2_ANT The configuration is such that =2), and for example, there are two possible patterns.

[0585] Figure 90A shows N TxGroup1_ANT =1(Tx#2), N TxGroup2_ANT Figure 90B shows an example of a MIMO array configuration for the case where =2(Tx#1, Tx#3), and N TxGroup1_ANT =2(Tx#2, Tx#3), N TxGroup2_ANT This is an example of a MIMO array configuration when =1 (Tx#1).

[0586] Next, Figures 91A and 91B show the number of transmitting antennas N included in the first transmitting antenna group. TxGroup1_ANT and the number of transmitting antennas N included in the second group of transmitting antennas TxGroup2_ANT The number of and are equal, and the number of receiving antennas included in the first receiving antenna group is N. RxGroup1_ANT The number of receiving antennas N included in the second receiving antenna group. RxGroup2_ANT This shows an example of a MIMO array configuration when there is a difference equivalent to one antenna, and an example of a virtual receiver array configuration.

[0587] As shown in Figures 91A and 91B, |N TxGroup1_ANT -N TxGroup2_ANT |=0 and |N RxGroup1_ANT -N RxGroup2_ANT When |=1, the MIMO array configuration is such that the number of transmitting antennas is 4(N TxGroup1_ANT =N TxGroup2_ANT =2), resulting in a configuration with 3 receiving antennas, and there are, for example, two possible patterns.

[0588] Figure 91A shows N RxGroup1_ANT =1(Rx#3), N RxGroup2_ANT Figure 91B shows an example of a MIMO array configuration for the case where =2(Rx#1,Rx#2), and N RxGroup1_ANT =2(Rx#2, Rx#3), N RxGroup2_ANT This is an example of a MIMO array configuration when =1 (Rx#1).

[0589] Next, Figures 92A to D show the number of transmitting antennas N included in the first transmitting antenna group. TxGroup1_ANT and the number of transmitting antennas N included in the second group of transmitting antennas TxHGroup2_ANT There is a difference of one antenna between the two, and the number of receiving antennas included in the first receiving antenna group is N. RxGroup1_ANT The number of receiving antennas N included in the second receiving antenna group. RxGroup2_ANT This shows an example of a MIMO array configuration when there is a difference equivalent to one antenna, and an example of a virtual receiver array configuration.

[0590] As shown in Figures 92A to D, |N TxGroup1_ANT -N TxGroup2_ANT |=1 and |N RxGroup1_ANT -N RxGroup2_ANT When |=1, the MIMO array configuration has 3 transmitting antennas and 3 receiving antennas, and there are four possible patterns, for example, as shown in Figures 92A to D.

[0591] Figure 92A shows N TxVGroup1_ANT =1(Tx#2), N TxVGroup2_ANT =2(Tx#1,Tx#3), N RxHGroup1_ANT =1(Rx#3), N RxHGroup2_ANTThis is an example of a MIMO array configuration when =2(Rx#1,Rx#2).

[0592] Figure 92B shows N TxVGroup1_ANT =1(Tx#2), N TxVGroup2_ANT =2(Tx#1,Tx#3), N RxHGroup1_ANT =2(Rx#2,Rx#3), N RxHGroup2_ANT This is an example of a MIMO array configuration when =1 (Rx#1).

[0593] Figure 92C shows N TxVGroup1_ANT =2(Tx#2,Tx#3), N TxVGroup2_ANT =1(Tx#1), ​​N RxHGroup1_ANT =1(Rx#3), N RxHGroup2_ANT This is an example of a MIMO array configuration for the case where =2(Rx#1,Rx#2).

[0594] Figure 92D shows N TxVGroup1_ANT =2(Tx#2,Tx#3), N TxVGroup2_ANT =1(Tx#1), ​​N RxHGroup1_ANT =2(Rx#2,Rx#3), N RxHGroup2_ANT This is an example of a MIMO array configuration when =1 (Rx#1).

[0595] In the virtual receiving arrays shown in Figures 90A, 90B, 91A, 91B, and 92A-D, each virtual array element is arranged in a different position without overlap, thus expanding the aperture length of the virtual receiving array and improving the angular resolution.

[0596] Furthermore, the virtual array element located near the center of the virtual receiving array is D H , D V They are densely arranged at intervals. For example, in Figures 90A, 90B, 91A, 91B and 92A-D, the interval D H and interval D V If we set the value to approximately 0.5λ, the virtual array element located near the center of the virtual receiving array will have a horizontal dimension of D H = 0.5λ intervals, vertically in the direction D V They are spaced at 0.5λ intervals. This reduces grating groves.

[0597] Also, for example, in the MIMO array configuration of basic configuration 5, the interval D H and interval D V If the value is set to approximately 0.5λ, the horizontal and vertical element sizes of the transmitting antenna 106 and the receiving antenna 202 can be designed to be approximately 1λ or larger.

[0598] This allows for, for example, the lateral W of the transmitting antenna 106 and the receiving antenna 202. ANT The element size is D H Any size antenna can be used in the vertical direction as long as it is smaller than the specified size. For example, Figure 93A shows an example where a sub-array of planar patch antennas arranged in a vertical order of 8 elements and a horizontal order, as shown in Figure 25A, is applied to the antenna arrangement shown in Figure 89. In addition, as shown in Figure 93B, a parasitic element (dummy element) may be placed in addition to the transmitting array antenna shown in Figure 93A. The parasitic element can equalize the effect of inter-antenna coupling by adjacent antennas across each antenna, and thus equalize the directional characteristics of each transmitting antenna (Tx#1~#4).

[0599] Thus, by using a sub-array configuration antenna in the antenna arrangement related to the basic arrangement 5, the directional gain of the antenna can be improved, and the detection performance (e.g., detection distance) of the radar device 10 can be improved.

[0600] The direction estimation unit 214 performs direction estimation processing in the horizontal and vertical directions using the received signals of the virtual receiving array obtained from the above-described transmitting and receiving antenna arrangement. Note that the processing of the virtual receiving array of the basic arrangement 5 in the direction estimation unit 214 is the same as that of the basic arrangement 1, so its explanation is omitted here.

[0601] Figure 94 shows, for example, a MIMO array configuration (D) with the number of transmitting antennas 106 Nt=4 and the number of receiving antennas 202 Na=4, as shown in Figure 89. H =0.5λ, D VAn example of the direction estimation result when the beamformer method is used as the direction estimation algorithm for the direction estimation unit 214, using (=0.5λ), is shown. Specifically, in Figure 94, the horizontal and vertical antenna spacing of the transmitting antenna 106 is 1λ or more, and the horizontal and vertical antenna spacing of the receiving antenna 202 is also 1λ or more. Note that the directivity of each antenna is calculated as omnidirectional.

[0602] Figure 94 plots the output of the estimated direction of arrival evaluation function values ​​within a range of ±90 degrees horizontally and ±90 degrees vertically, when the target true value is set to 0 degrees horizontally and 0 degrees vertically.

[0603] In Figure 94, it can be seen that the grating lobe is reduced in directions other than horizontal 0 degrees and vertical 0 degrees of the target true value, compared to, for example, Figure 1A. For example, in Figure 94, the ratio (PSLR) of the peak power value of the highest side lobe excluding the main lobes in directions other than horizontal 0 degrees and vertical 0 degrees to the peak power value of the main lobe in the horizontal 0 degrees and vertical 0 degrees directions is approximately 0.35.

[0604] As described above, by using the MIMO array configuration related to basic configuration 5, even if the vertical or horizontal element size of the antennas used in the transmitting array antenna and the receiving array antenna is about 1λ, the antennas in the virtual receiving array can be arranged to include element spacings of about 0.5λ in the horizontal and vertical directions, thereby reducing grating lobes. Furthermore, for example, since each virtual array element in the virtual receiving array shown in Figure 52A is arranged without overlap, the aperture length of the virtual receiving array can be expanded, improving the angular resolution.

[0605] <Modification 1 of Basic Arrangement 5> Modification 1 of Basic Configuration 5 describes a MIMO array configuration in which the arrangement of the transmitting array antenna and the receiving array antenna shown in Basic Configuration 5 are each considered as "basic sets," and the placement positions of multiple basic sets are offset.

[0606] The following describes the arrangement methods 5-1A, 5-1B, and 5-1C related to Modification 1 of Basic Arrangement 5.

[0607] (Placement method 5-1A) In arrangement method 5-1A, the arrangement of the 4-element transmitting array antenna and the arrangement of the 4-element receiving array antenna shown in basic arrangement 5 are each considered "basic sets," and a MIMO array arrangement with an offset configuration of multiple basic sets is described.

[0608] In the configuration shown below, the offset of the basic set of transmitting array antennas to their horizontal and vertical positions, or the offset of the basic set of receiving array antennas to their horizontal and vertical positions, is such that there are no overlapping elements in the virtual receiving array configuration, and more virtual array elements are located near the center of the virtual receiving array. V or D H The elements may be set to be densely spaced. However, this is not the only way to achieve this; for example, if the number of arrangements with unequal spacing in the virtual receiver array arrangement is increased, or if the number of arrangements where virtual array elements overlap in the virtual receiver array arrangement is increased, this can also be achieved by adjusting the offset of the arrangement positions.

[0609] Figure 95 shows the number of basic sets of transmitting array antennas, N. TxBaseSet Let = 2, and the number of basic sets of receiving array antennas be N. RxBaseSet The following shows examples of MIMO array configurations and virtual receiver array configurations when = 1. In Figure 95, the offset D of the horizontal placement position of the second basic set (Tx#5, Tx#6, Tx#7, and Tx#8) relative to the first basic set (Tx#1, Tx#2, Tx#3, and Tx#4) is shown. Hoffset_TxBaseSet2 =5D H And the offset D of the position in the vertical direction Voffset_TxBaseSet2 Let = 0. As shown in Figure 95, by arranging the two basic sets of transmitting array antennas with a horizontal offset, D is set horizontally. HThe number of virtual array elements that are densely arranged at intervals can be increased, improving the horizontal angular resolution. In the case of Figure 95, virtual array elements are arranged in overlapping positions in two locations.

[0610] Figure 96 shows the number of basic sets of transmitting array antennas, N. TxBaseSet Let = 2, and the number of basic sets of receiving array antennas be N. RxBaseSet The following shows examples of MIMO array configurations and virtual receiver array configurations when = 1. In Figure 96, the offset D of the horizontal placement position of the second basic set (Tx#5, Tx#6, Tx#7, and Tx#8) relative to the first basic set (Tx#1, Tx#2, Tx#3, and Tx#4) is shown. Hoffset_TxBaseSet2 Set = 0, and the offset D of the vertical placement position. Voffset_TxBaseSet2 =3D V As shown in Figure 96, by arranging the two basic sets of transmitting array antennas with a vertical offset, the vertical direction D V The number of virtual array elements densely arranged at intervals can be increased, improving the horizontal angular resolution. In the case of Figure 96, virtual array elements are arranged in overlapping positions in two locations.

[0611] Figure 97 shows the number of basic sets of transmitting array antennas, N. TxBaseSet Let = 1, and the number of basic sets of receiving array antennas be N. RxBaseSet The following shows examples of MIMO array configurations and virtual receiver array configurations when =2. In Figure 97, the offset D of the horizontal placement position of the second basic set (Rx#5, Rx#6, Rx#7, Rx#8) relative to the first basic set (e.g., Rx#1, Rx#2, Rx#3, and Rx#4) is shown. Hoffset_RxBaseSet2 =5D H And the offset D of the position in the vertical direction Voffset_RxBaseSet2 Let = 0. As shown in Figure 97, by arranging the two basic sets of receiving array antennas with a horizontal offset, D is set horizontally. H The number of virtual array elements, which are densely arranged at intervals, can be increased, thereby improving the angular resolution in the horizontal direction. In the case of Figure 97, the virtual array elements are arranged in overlapping positions in two locations.

[0612] Figure 98 shows the number of basic sets of transmitting array antennas, N. TxBaseSet Let = 1, and the number of basic sets of receiving array antennas be N. RxBaseSet The following shows an example of MIMO array configuration when =2, and an example of a virtual receiver array configuration. In Figure 98, the offset D of the horizontal placement position of the second basic set (Rx#5, Rx#6, Rx#7, and Rx#8) relative to the first basic set (e.g., Rx#1, Rx#2, Rx#3, and Rx#4) is shown. Hoffset_RxBaseSet2 Set = 0, and the offset D of the vertical placement position. Voffset_RxBaseSet2 =3D V As shown in Figure 98, by arranging the two basic sets of receiving array antennas with a vertical offset, the vertical direction D V The number of virtual array elements densely arranged at intervals can be increased, improving the vertical angular resolution. In the case of Figure 98, virtual array elements are arranged in overlapping positions in two locations.

[0613] Figure 99 shows that the number of basic sets of transmitting array antennas is N. TxBaseSet Let = 2, and the number of basic sets of receiving array antennas be N. RxBaseSet The following shows an example of a MIMO array configuration when =2, and an example of a virtual receiver array configuration. In Figure 99, the offset D of the horizontal position of the second basic set (Tx#5, Tx#6, Tx#7, and Tx#8) relative to the first basic set (e.g., Tx#1, Tx#2, Tx#3, and Tx#4) of the transmitting array antenna is shown. Hoffset_TxBaseSet2 =10D H And the offset D of the position in the vertical direction Voffset_TxBaseSet2 Let = 0. Also, in Figure 99, offset D is the horizontal positional offset of the second basic set (Rx#5, Rx#6, Rx#7, and Rx#8) relative to the first basic set (e.g., Rx#1, Rx#2, Rx#3, and Rx#4) of the receiving array antenna. Hoffset_RxBaseSet2 =5D H And the offset D of the position in the vertical direction Voffset_RxBaseSet2Let = 0. As shown in Figure 99, by arranging the two basic sets of transmitting array antennas with a horizontal offset, and arranging the two basic sets of receiving array antennas with a horizontal offset, D is generated horizontally. H The number of virtual array elements densely arranged at intervals can be further increased, for example, compared to Figure 95 or Figure 97, thereby further improving the horizontal angular resolution. In the case of Figure 99, virtual array elements are overlapping at four locations.

[0614] Figure 100A shows that the number of basic sets of transmitting array antennas is N. TxBaseSet Let = 2, and the number of basic sets of receiving array antennas be N. RxBaseSet Figure 100B shows an example of a MIMO array configuration when =4, and an example of a virtual receiver array configuration.

[0615] In Figure 100A, the horizontal offset D of the second basic set (Tx#5, Tx#6, Tx#7, and Tx#8) relative to the first basic set (e.g., Tx#1, Tx#2, Tx#3, and Tx#4) of the transmitting array antenna is shown. Hoffset_TxBaseSet2 =5D H And the offset D of the position in the vertical direction Voffset_TxBaseSet2 Let = 00.

[0616] Furthermore, in Figure 100A, the horizontal offset D of the second basic set (Rx#5, Rx#6, Rx#7, and Rx#8) relative to the first basic set (e.g., Rx#1, Rx#2, Rx#3, and Rx#4) of the receiving array antenna is shown. Hoffset_RxBaseSet2 =5D H And the offset D of the position in the vertical direction Voffset_RxBaseSet2 =-3D V The offset D of the horizontal placement position of the third basic set (Rx#9, Rx#10, Rx#11 and Rx#12) is... Hoffset_RxBaseSet3 =-5D H And the offset D of the position in the vertical direction Voffset_RxBaseSet3 =-3D VThe offset D of the horizontal placement position of the fourth basic set (Rx#13, Rx#14, Rx#15 and Rx#16) is... Hoffset_RxBaseSet4 Set = 0, and the offset D of the vertical placement position. Voffset_RxBaseSet4 =-6D V Let's assume that.

[0617] As shown in Figures 100A and 100B, by arranging the basic set of the transmitting array antennas in a horizontally offset position and the basic set of the receiving array antennas in a horizontally offset position, D H The number of virtual array elements densely arranged at intervals can be further increased, for example, compared to Figure 95 or Figure 97, thereby further improving the horizontal angular resolution.

[0618] Similarly, as shown in Figures 100A and 100B, by arranging the basic set of receiving array antennas in a vertically offset position, D in the vertical direction V The number of virtual array elements densely arranged at intervals can be increased, improving the vertical angular resolution. In the case of Figure 100B, virtual array elements are overlapped at eight locations.

[0619] <Placement method 5-1B> In arrangement method 5-1B, the arrangement of a 4-element transmitting array antenna and a 3-element receiving array antenna, or the arrangement of a 3-element transmitting array antenna and a 4-element receiving array antenna, as shown in basic arrangement 5, are each considered "basic sets," and MIMO array arrangements with offset placement positions for multiple basic sets are described.

[0620] In the following, we will explain the case where the antenna configuration shown in Figure 90A is used in the "basic set" as an example. However, the antenna configuration is not limited to the example shown in Figure 90A; other antenna configurations (for example, Figure 90B, Figure 91A, or Figure 91B) may also be used.

[0621] Furthermore, in the configuration shown below, the offset of the basic set of transmitting array antennas to their horizontal and vertical positions, or the offset of the basic set of receiving array antennas to their horizontal and vertical positions, is such that there are no overlapping elements in the virtual receiving array configuration, and more virtual array elements are located near the center of the virtual receiving array. V or D H The elements may be set to be densely spaced. However, this is not the only way to achieve this; for example, if the number of arrangements with unequal spacing in the virtual receiver array arrangement is increased, or if the number of arrangements where virtual array elements overlap in the virtual receiver array arrangement is increased, this can also be achieved by adjusting the offset of the arrangement positions.

[0622] Figure 101 shows the number of basic sets of transmitting array antennas, N. TxBaseSet Let = 2, and the number of basic sets of receiving array antennas be N. RxBaseSet The following shows examples of MIMO array configurations and virtual receiver array configurations when = 1. In Figure 101, the offset D of the horizontal placement position of the second basic set (Tx#4, Tx#5, and Tx#6) relative to the first basic set (Tx#1, Tx#2, and Tx#3) is shown. Hoffset_TxBaseSet2 =4D H And the offset D of the position in the vertical direction Voffset_TxBaseSet2 =D V As shown in Figure 101, by arranging the two basic sets of transmitting array antennas in a horizontally offset manner, the horizontal direction D H The number of virtual array elements arranged closely together can be increased, improving the horizontal angular resolution.

[0623] Figure 102 shows the number of basic sets of transmitting array antennas, N. TxBaseSet Let = 2, and the number of basic sets of receiving array antennas be N. RxBaseSet The following shows an example of MIMO array configuration when = 1, and an example of a virtual receive array configuration. In Figure 102, the horizontal offset of the second basic set (Tx#4, Tx#5, and Tx#6) relative to the first basic set (Tx#1, Tx#2, and Tx#3) is D.Hoffset_TxBaseSet2 Set = 0, and the offset D of the vertical placement position. Voffset_TxBaseSet2 =3D V As shown in Figure 102, by arranging the two basic sets of transmitting array antennas with a vertical offset, the vertical direction D V The number of virtual array elements arranged closely together can be increased, improving the vertical angular resolution.

[0624] Figure 103 shows the number of basic sets of transmitting array antennas, N. TxBaseSet Let = 1, and the number of basic sets of receiving array antennas be N. RxBaseSet The following shows an example of MIMO array configuration and a virtual receiver array configuration when = 2. In Figure 103, the horizontal offset of the second basic set (Rx#5, Rx#6, Rx#7, and Rx#8) relative to the first basic set (e.g., Rx#1, Rx#2, Rx#3, and Rx#4) is D. Hoffset_RxBaseSet2 =4D H And the offset D of the position in the vertical direction Voffset_RxBaseSet2 =D V As shown in Figure 103, by arranging the two basic sets of receiving array antennas in a horizontally offset position, the horizontal direction D H The number of virtual array elements arranged closely together can be increased, improving the horizontal angular resolution.

[0625] Figure 104 shows the number of basic sets of transmitting array antennas, N. TxBaseSet Let = 1, and the number of basic sets of receiving array antennas be N. RxBaseSet The following shows an example of MIMO array configuration when =2, and an example of a virtual receive array configuration. In Figure 104, the offset D of the horizontal placement position of the second basic set (Rx#5, Rx#6, Rx#7, and Rx#8) relative to the first basic set (e.g., Rx#1, Rx#2, Rx#3, and Rx#4) is shown. Hoffset_RxBaseSet2 Set = 0, and the vertical position offset D Voffset_RxBaseSet2 =3D VAs shown in Figure 104, by arranging the two basic sets of receiving array antennas with a vertical offset, the vertical direction D V The number of virtual array elements arranged closely together can be increased, improving the vertical angular resolution.

[0626] Figure 105 shows the number of basic sets of transmitting array antennas, N. TxBaseSet Let = 2, and the number of basic sets of receiving array antennas be N. RxBaseSet The following shows an example of a MIMO array configuration and a virtual receiver array configuration when = 2. In Figure 105, the horizontal offset of the second basic set (Tx#4, Tx#5, and Tx#6) relative to the first basic set (Tx#1, Tx#2, and Tx#3) of the transmitting array antennas is D. Hoffset_TxBaseSet2 =4D H And the offset D of the position in the vertical direction Voffset_TxBaseSet2 =-2D V In addition, in Figure 105, the horizontal offset D of the second basic set (Rx#5, Rx#6, Rx#7, and Rx#8) relative to the first basic set (e.g., Rx#1, Rx#2, Rx#3, and Rx#4) of the receiving array antenna is shown. Hoffset_RxBaseSet2 =4D H And the offset D of the position in the vertical direction Voffset_RxBaseSet2 =D V As shown in Figure 105, by arranging the two basic sets of transmitting array antennas with a horizontal offset, and arranging the two basic sets of receiving array antennas with a horizontal offset, the horizontal direction D H The number of virtual array elements densely arranged at intervals can be further increased, for example, compared to Figure 101 or Figure 103, thereby further improving the horizontal angular resolution.

[0627] Figure 106A shows the number of basic sets of transmitting array antennas as N. TxBaseSet Let = 2, and the number of basic sets of receiving array antennas be N. RxBaseSet Figure 106B shows an example of a MIMO array configuration when =4, and an example of a virtual receiver array configuration.

[0628] In Figure 106A, the horizontal offset of the second basic set (Tx#4, Tx#5, and Tx#6) relative to the first basic set (Tx#1, Tx#2, and Tx#3) of the transmitting array antenna is D. Hoffset_TxBaseSet2 =4D H And the offset D of the position in the vertical direction Voffset_TxBaseSet2 =D V Let's assume that.

[0629] Furthermore, in Figure 106A, the horizontal offset D of the second basic set (Tx#5, Tx#6, Tx#7, and Tx#8) relative to the first basic set (e.g., Rx#1, Rx#2, Rx#3, and Rx#4) of the receiving array antenna is shown. Hoffset_RxBaseSet2 =4D H And the offset D of the position in the vertical direction Voffset_RxBaseSet2 =-2D V The horizontal offset of the placement position of the third basic set (Tx#9, Tx#10, Tx#11 and Tx#12) is D Hoffset_RxBaseSet3 =-6D H And the offset D of the position in the vertical direction Voffset_RxBaseSet3 =-3D V The horizontal offset of the placement position of the fourth basic set (Tx#13, Tx#14, Tx#15 and Tx#16) is D Hoffset_RxBaseSet4 =-2D H And the offset D of the position in the vertical direction Voffset_RxBaseSet4 =-5D V Let's assume that.

[0630] As shown in Figures 106A and 106B, by arranging the basic set of the transmitting array antennas in a horizontally offset position, and arranging the basic set of the receiving array antennas in a horizontally offset position, D H The number of virtual array elements densely arranged at intervals can be further increased, for example, compared to Figure 101 or Figure 103, thereby further improving the horizontal angular resolution.

[0631] Similarly, as shown in Figures 106A and 106B, by arranging the basic set of receiving array antennas in a vertically offset position, D in the vertical direction V The number of virtual array elements arranged closely together can be increased, improving the vertical angular resolution.

[0632] <Placement method 5-1C> In arrangement method 5-1C, the arrangement of the 3-element transmitting array antenna and the arrangement of the 3-element receiving array antenna shown in basic arrangement 5 are considered "basic sets," and MIMO array arrangements with offset placement positions of multiple basic sets are described.

[0633] In the following section, we will explain the case where the antenna configuration shown in Figure 92B is used as the "basic set" as an example. However, the antenna configuration is not limited to the example shown in Figure 92B; other antenna configurations (for example, Figures 92A, 92C, or 92D) may also be used.

[0634] Furthermore, in th...

Claims

1. A radar transmission circuit that transmits radar signals using a transmitting array antenna, A radar receiving circuit that receives reflected wave signals, which are radar signals reflected from a target object, using a receiving array antenna, It is equipped with, One of the transmitting array antenna and the receiving array antenna is composed of a plurality of first antennas. Two of the plurality of first antennas are arranged at a first spacing in the first direction and at the same position in a second direction perpendicular to the first direction. Unlike the two antennas among the plurality of first antennas, the other two antennas among the plurality of first antennas are positioned at a first spacing in the first direction and shifted by a third spacing in the first direction and a second spacing in the second direction from the two antennas among the plurality of first antennas. The other of the transmitting array antenna and the receiving array antenna is composed of at least two or more second antenna groups. The at least two second antenna groups are arranged at a fourth interval apart from each other in the first direction and at a position shifted by a fifth interval in the second direction. Radar device.

2. The plurality of first antennas are composed of at least two or more groups of first antennas. Of the plurality of first antennas, the two antennas are included in one of the at least two groups of first antennas. Of the plurality of first antennas, the other two antennas are included in one of the other antenna groups of the at least two groups of first antennas. The radar device according to claim 1.

3. The positions of the plurality of first antennas in the first direction are different from each other. The radar device according to claim 1.

4. The first interval in the first direction is one times the interval of the fourth interval in the first direction. The radar device according to claim 1.

5. The group of at least two second antennas is composed of a plurality of second antennas, Each of the plurality of second antennas in the second antenna group has the same position in the first direction. The radar device according to claim 1.

6. All of the plurality of second antennas are positioned differently from each other in the second direction. The radar device according to claim 5.

7. The first interval in the first direction is twice the interval of the third interval in the first direction. The radar device according to claim 1.

8. The second interval in the second direction is twice the interval of the fifth interval in the second direction. The radar device according to claim 2.

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