radar device

Abstract

A radar device according to the present invention comprises: a radar transmitting unit for transmitting radar signals from a first transmitting antenna, a second transmitting antenna, and a third transmitting antenna at a predetermined transmission cycle; and a radar receiving unit for receiving, using a first receiving antenna, a second receiving antenna, a third receiving antenna, and a fourth receiving antenna, a plurality of reflected wave signals resulting from reflections of the radar signals transmitted from each of the first, second, and third transmitting antennas from a target, wherein the first transmitting antenna is separated from the second transmitting antenna in a first direction, the third transmitting antenna is separated from the first and second transmitting antennas in a second direction, the first, second, and third receiving antennas are separated from each other in the first direction, and the fourth receiving antenna is separated from the first, second, and third receiving antennas in the second direction.

Description

[0001] This application is a divisional application of the following patent application: Application number: 201610702468.4, Application date: August 22, 2016, Invention name: Radar device. Technical Field

[0002] The present invention relates to a radar device. Background Art

[0003] In recent years, research has been underway on radar devices that utilize short-wavelength radar transmission signals, including microwaves and millimeter waves, to achieve high resolution. Furthermore, to improve outdoor safety, there is a demand for radar devices (wide-angle radar devices) that can detect objects (targets) in addition to vehicles and pedestrians over a wide angle.

[0004] For example, a pulse radar device that repeatedly transmits pulse waves is known as a radar device. The received signal of a wide-angle pulse radar that detects vehicles and pedestrians in a wide-angle range is a mixture of multiple reflected waves from targets at close range (e.g., vehicles) and targets at far range (e.g., pedestrians). To achieve this, (1) the radar transmitting unit is required to have a structure that transmits pulse waves or pulse-modulated waves with low range sidelobe autocorrelation characteristics (hereinafter referred to as low range sidelobe characteristics), and (2) the radar receiving unit is required to have a structure with a wide reception dynamic range.

[0005] The following two structures can be cited as the structure of the wide-angle radar device.

[0006] The first is a configuration that uses a narrow-angle (beam width of several degrees) directional beam to transmit radar waves by mechanically or electronically scanning pulse waves or modulated waves, and then receives the reflected waves using the narrow-angle directional beam. This configuration requires numerous scans to achieve high resolution, which degrades tracking of relatively high-speed moving targets.

[0007] The second is a structure that uses an array antenna composed of multiple antennas (antenna elements) to receive reflected waves and estimates the angle of arrival of the reflected waves (Direction of Arrival (DOA) estimation) using a signal processing algorithm based on the reception phase difference relative to the antenna spacing. In this structure, even if the scanning interval of the transmission beam in the transmission branch is sparse, the arrival angle can be estimated in the reception branch, thereby shortening the scanning time and improving tracking performance compared to the first structure. For example, the Fourier transform based on matrix operations, the Capon method and LP (Linear Prediction) method based on inverse matrix operations, and MUSIC (Multiple Signal Classification) and ESPRIT (Estimation of Signal Parameters via Rotational Invariance Techniques) based on eigenvalue operations are listed.

[0008] In addition, as a radar device, a structure (sometimes also called MIMO radar) has been proposed that includes multiple antennas (array antennas) in the transmitting branch in addition to the receiving branch, and performs beam scanning by signal processing using the transmitting and receiving array antennas (for example, refer to non-patent document 1).

[0009] In MIMO radar, by considering the arrangement of antenna elements in a transmit / receive array antenna, a virtual receive array antenna (hereinafter referred to as a virtual receive array) can be constructed with a maximum value equal to the product of the number of transmit antenna elements and the number of receive antenna elements. This has the effect of increasing the effective aperture length of the array antenna with a small number of elements.

[0010] Furthermore, MIMO radar can also be applied when performing two-dimensional beam scanning in the vertical and horizontal directions in addition to one-dimensional scanning in the vertical or horizontal direction.

[0011] Prior art literature

[0012] Non-patent literature

[0013] Non-Patent Document 1: Jian Li, Stoica, Petre, "MIMO Radar with Colocated Antennas," Signal Processing Magazine, IEEE Vol. 24, Issue 5, pp. 106-114, 2007 Summary of the Invention

[0014] However, for MIMO radar, in order to achieve miniaturization and low cost, there is a limit on the number of antennas for transmitting and receiving branches (for example, about 4 antennas for transmitting and about 4 antennas for receiving). Therefore, the aperture length in the vertical and horizontal directions of the planar virtual receiving array formed by the MIMO radar is limited.

[0015] One aspect of the present invention provides a radar device capable of maximizing the aperture length in a virtual receiving array.

[0016] A radar device according to one embodiment of the present invention has a structure comprising: a radar transmitting unit that transmits radar signals from a first transmitting antenna, a second transmitting antenna, and a third transmitting antenna at a predetermined transmission period; and a radar receiving unit that receives, using a first receiving antenna, a second receiving antenna, a third receiving antenna, and a fourth receiving antenna, a plurality of reflected wave signals resulting from the radar signals transmitted from each of the first, second, and third transmitting antennas and reflected from a target, wherein the first transmitting antenna is separated from the second transmitting antenna in a first direction, the third transmitting antenna is separated from the first and second transmitting antennas in a second direction, the first, second, and third receiving antennas are separated from each other in the first direction, and the fourth receiving antenna is separated from the first, second, and third receiving antennas in the second direction. In the first direction, the first distance between the first transmitting antenna and the second transmitting antenna, the second distance between the first receiving antenna and the second receiving antenna, and the third distance between the second receiving antenna and the third receiving antenna are integer multiples of the first common distance, and the first distance, the second distance, and the third distance are different from each other. In the second direction, the fourth distance between the third transmitting antenna and the first transmitting antenna, and the fifth distance between the fourth receiving antenna and the first receiving antenna are integer multiples of the second common distance, the fourth distance and the fifth distance are different from each other, the first distance is smaller than the second distance and the fifth distance is smaller than the fourth distance, or the sum of the second distance and the third distance is smaller than the first distance, and the fourth distance is smaller than the fifth distance.

[0017] A radar apparatus according to one embodiment of the present invention has a configuration including: a radar transmitting unit that transmits radar signals from each of a plurality of transmitting antennas at a predetermined transmission cycle; and a radar receiving unit that receives a plurality of reflected wave signals resulting from the plurality of radar signals being reflected from a target using a plurality of receiving antennas, wherein the plurality of transmitting antennas include Nt1 transmitting antennas arranged in a first direction and Nt2 transmitting antennas arranged in a second direction orthogonal to the first direction, and the plurality of receiving antennas include Na1 receiving antennas arranged in the first direction and Na2 receiving antennas arranged in the second direction, wherein in the first direction, the element spacings between the Nt1 transmitting antennas and the element spacings between the Na1 receiving antennas are integer multiples of the first spacing and are all different values, and in the second direction, the element spacings between the Nt2 transmitting antennas and the element spacings between the Na2 receiving antennas are integer multiples of the second spacing and are all different values.

[0018] Furthermore, these general and specific aspects may be implemented by systems, methods, integrated circuits, computer programs, or recording media, or by any combination of systems, devices, methods, integrated circuits, computer programs, and recording media.

[0019] According to one aspect of the present invention, the aperture length in the virtual receiving array can be maximized.

[0020] Further advantages and effects of one embodiment of the present invention will be apparent from the description and drawings. These advantages and / or effects may be provided separately by several embodiments and features described in the description and drawings, and it is not necessary to provide all features in order to obtain one or more features. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1A A diagram showing an example of the arrangement of transmitting antennas.

[0022] Figure 1B A diagram showing an example of the arrangement of receiving antennas.

[0023] Figure 1C is a diagram showing an example of a configuration of a virtual receiving array.

[0024] Figure 2A : is a diagram showing a directivity pattern formed by a virtual receiving array (d=0.5λ).

[0025] Figure 2B : is a diagram showing a directivity pattern formed by a virtual receiving array (d=1.3λ).

[0026] Figure 3This is a block diagram showing the configuration of a radar device according to Embodiment 1 of the present invention.

[0027] Figure 4 This is a diagram showing an example of a radar transmission signal according to the first embodiment of the present invention.

[0028] Figure 5 This is a block diagram showing another configuration of the radar transmission signal generating unit according to the first embodiment of the present invention.

[0029] Figure 6 This is a diagram showing an example of the transmission timing (timing) and measurement range of the radar transmission signal according to the first embodiment of the present invention.

[0030] Figure 7A This is a diagram showing an example of arrangement of transmitting antennas and receiving antennas according to Embodiment 1 of the present invention.

[0031] Figure 7B This is a diagram showing an example of arrangement of a virtual receiving array according to the first embodiment of the present invention.

[0032] Figure 8 This is a diagram showing a directivity pattern formed by a virtual receiving array according to the first embodiment of the present invention.

[0033] Figure 9A This is a diagram showing an example of arrangement of transmitting antennas and receiving antennas according to Variation 1 of Embodiment 1 of the present invention.

[0034] Figure 9B This is a diagram showing an example of arrangement of a virtual receiving array according to Modification 1 of Embodiment 1 of the present invention.

[0035] Figure 10A This is a diagram showing an example of arrangement of transmitting antennas and receiving antennas according to Modification 2 of Embodiment 1 of the present invention.

[0036] Figure 10B This is a diagram showing an example of arrangement of a virtual receiving array according to Modification 2 of Embodiment 1 of the present invention.

[0037] Figure 11A This is a diagram showing an example of arrangement of transmitting antennas and receiving antennas according to Modification 3 of Embodiment 1 of the present invention.

[0038] Figure 11B This is a diagram showing an example of arrangement of a virtual receiving array according to Modification 3 of Embodiment 1 of the present invention.

[0039] Figure 12 This is a diagram showing an example of arrangement of transmitting antennas and receiving antennas using sub-array antenna elements according to Embodiment 2 of the present invention.

[0040] Figure 13AThis is a diagram showing an example of arrangement of transmitting antennas and receiving antennas according to Embodiment 2 of the present invention.

[0041] Figure 13B This is a diagram showing an example of arrangement of a virtual receiving array according to Embodiment 2 of the present invention.

[0042] Figure 14 This is a diagram showing a directivity pattern formed by a virtual receiving array according to the first embodiment of the present invention.

[0043] Figure 15A This is a diagram showing an example of arrangement of transmitting antennas and receiving antennas according to Modification 1 of Embodiment 2 of the present invention.

[0044] Figure 15B This is a diagram showing an example of arrangement of a virtual receiving array according to Modification 1 of Embodiment 2 of the present invention.

[0045] Figure 15C This is a diagram showing an example of arrangement of transmitting antennas and receiving antennas according to Modification 1 of Embodiment 2 of the present invention.

[0046] Figure 16 This is a diagram showing an example of arrangement of transmitting antennas and receiving antennas using sub-array antenna elements according to Modification 2 of Embodiment 2 of the present invention.

[0047] Figure 17A This is a diagram showing an example of arrangement of transmitting antennas and receiving antennas according to Modification 3 of Embodiment 2 of the present invention.

[0048] Figure 17B This is a diagram showing an example of arrangement of a virtual receiving array according to Modification 3 of Embodiment 2 of the present invention.

[0049] Figure 18 This is a diagram showing an example of arrangement of transmitting antennas and receiving antennas using sub-array antenna elements according to Modification 3 of Embodiment 2 of the present invention.

[0050] Figure 19 This is a diagram showing an example of arrangement of transmitting antennas and receiving antennas using sub-array antenna elements according to Modification 4 of Embodiment 2 of the present invention.

[0051] Figure 20A This is a diagram showing an example of arrangement of transmitting antennas and receiving antennas according to Modification 4 of Embodiment 2 of the present invention.

[0052] Figure 20B This is a diagram showing an example of arrangement of a virtual receiving array according to Modification 4 of Embodiment 2 of the present invention.

[0053] Figure 21A This is a diagram showing an example of arrangement of transmitting antennas and receiving antennas according to Modification 5 of Embodiment 2 of the present invention.

[0054] Figure 21B This is a diagram showing an example of arrangement of a virtual receiving array according to Modification 5 of Embodiment 2 of the present invention.

[0055] Figure 22A This is a diagram showing an example of arrangement of transmitting antennas and receiving antennas according to Modification 6 of Embodiment 2 of the present invention.

[0056] Figure 22B This is a diagram showing an example of arrangement of a virtual receiving array according to Modification 6 of Embodiment 2 of the present invention.

[0057] Figure 23A This is a diagram showing an example of the arrangement of transmission antennas according to the present invention.

[0058] Figure 23B This is a diagram showing an example of the arrangement of transmission antennas according to the present invention.

[0059] Figure 23C This is a diagram showing an example of the arrangement of transmission antennas according to the present invention.

[0060] Figure 23D This is a diagram showing an example of the arrangement of transmission antennas according to the present invention.

[0061] Figure 23E This is a diagram showing an example of the arrangement of transmission antennas according to the present invention.

[0062] Figure 23F This is a diagram showing an example of the arrangement of transmission antennas according to the present invention.

[0063] Figure 24A This is a diagram showing an example of the arrangement of receiving antennas according to the present invention.

[0064] Figure 24B This is a diagram showing an example of the arrangement of receiving antennas according to the present invention.

[0065] Figure 24C This is a diagram showing an example of the arrangement of receiving antennas according to the present invention.

[0066] Figure 24D This is a diagram showing an example of the arrangement of receiving antennas according to the present invention.

[0067] Figure 24E This is a diagram showing an example of the arrangement of receiving antennas according to the present invention.

[0068] Figure 24F This is a diagram showing an example of the arrangement of receiving antennas according to the present invention.

[0069] Figure 25 FIG. 1 is a diagram showing another configuration of the direction estimation unit.

[0070] Figure 26This is a diagram showing a three-dimensional coordinate system used in the description of the operation of the direction estimation unit.

[0071] Figure 27 Is to use Figure 9A Antenna configuration and Figure 9B The configuration of the virtual receiving array constitutes a diagram of the virtual plane configuration array antenna.

[0072] Figure 28A Is the vector D(n) between elements va (t) , 1) is a diagram of components virtually configured in the positions shown.

[0073] Figure 28B Is the vector D(n) between elements va (t) , 2) is a diagram of components virtually configured in the positions shown.

[0074] Figure 29A Is to use Figure 9B The virtual receiving array shown is a diagram showing the results of a computer simulation of the direction estimation process in 2D under condition A.

[0075] Figure 29B Is to use Figure 9B The virtual receiving array shown is a diagram showing the results of a computer simulation of the direction estimation process in two dimensions under condition B.

[0076] Figure 29C Is to use Figure 27 The diagram shows the results of a computer simulation of a two-dimensional direction estimation process under condition A using an array antenna arranged on a virtual plane.

[0077] Figure 29D Is to use Figure 27 The diagram shows the results of a computer simulation of an array antenna arranged on a virtual plane and a two-dimensional direction estimation process under condition B. DETAILED DESCRIPTION

[0078] [Process leading to completion of one embodiment of the present invention]

[0079] Figure 1A The antenna configuration of the transmit array antenna includes four transmit antennas (Tx#1 to Tx#4). Figure 1B The antenna configuration of a receiving array antenna including four receiving antennas (Rx#1 to Rx#4) is shown.

[0080] exist Figure 1A and Figure 1B In, d H The horizontal element spacing of the receiving antenna, d VIndicates the vertical element spacing of the receiving antenna. Figure 1A In the example, the element spacing of the transmitting antenna in the horizontal and vertical directions is assumed to be 2d. H , 2d V .

[0081] Figure 1C Indicates inclusion Figure 1A and Figure 1B The antenna configuration shown is a virtual receive array of transmit and receive array antennas.

[0082] like Figure 1C As shown, the virtual receiving array includes a 16-element virtual receiving array (VA#1 to VA#16) in which four antennas are arranged in a planar manner in the horizontal direction and four antennas are arranged in a planar manner in the vertical direction.

[0083] exist Figure 1C In the virtual receiving array, the horizontal and vertical element spacings are d H d V That is, the aperture length D of the virtual receiving array in the horizontal and vertical directions is H 、D V For 3D H , 3d V .

[0084] As an example, the element spacing d=d H =d V , aperture length D = D H =D V The virtual receiving array has equal amplitude weights, and the beam width (Fourier beam width) BW of Fourier beamforming is expressed as follows: Here, λ represents the wavelength of the carrier frequency of the wireless signal (RF signal) transmitted from the transmitting branch.

[0085] BW≒0.7λ / D[rad]

[0086] exist Figure 1C In the virtual receiving array (D=3d) shown, the Fourier beamwidth BW≒0.7λ / 3d[rad].

[0087] For example, when d=0.5λ, the Fourier beam width BW≒0.7 / 1.5[rad]≒30°, and when d=0.7λ, the Fourier beam width BW≒0.7 / 2.1[rad]≒19°.

[0088] By further increasing the element spacing d, the Fourier beam width BW can be further narrowed. However, as the element spacing d is increased, grating lobes are more likely to occur at angles closer to the main beam, increasing false detection.

[0089] For example, Figure 2A represents the directivity pattern when the element spacing d = 0.5λ, Figure 2B The directivity pattern when the element spacing d = 1.3λ is shown. Figure 2A and Figure 2B In the example, the main beam is formed in the 0° direction.

[0090] like Figure 2A As shown in Figure 1, when the element spacing d = 0.5λ, the Fourier beam width BW of the main beam is relatively wide, about 30°. Figure 2A In the range of ±90°, no grating lobes occur.

[0091] On the other hand, Figure 2B As shown, when the element spacing d=1.3λ, the Fourier beam width BW of the main beam is relatively narrow at about 10°, but grating lobes occur at angles of about ±50° from the main beam (0° direction).

[0092] For example, in Figure 2B When the detection angle of a wide-angle radar is widened to approximately ±25° or more, grating lobes occur within the detection angle range, increasing false detections.

[0093] Thus, there are limits on increasing the element spacing d to narrow the Fourier beamwidth BW. Alternatively, instead of increasing the element spacing d, the aperture length D could be increased by increasing the number of antenna elements. However, this also imposes limits on the aperture length D of the virtual receive array when considering cost savings.

[0094] To achieve an angular resolution of approximately 10° under these limitations, employing DOA estimation algorithms such as MUSIC and the Capon method increases the amount of computation required for eigenvalue decomposition and matrix inversion. Furthermore, even when employing a DOA estimation algorithm that achieves high resolution, achieving high angular resolution performance is difficult if the SNR (Signal to Noise Ratio) is not sufficiently high.

[0095] One aspect of the present invention maximizes the aperture length of a virtual receiving array in both the vertical and horizontal directions when using a MIMO radar to perform two-dimensional beam scanning. Using this virtual receiving array improves angular resolution with a reduced number of antenna elements, while also achieving a more compact and cost-effective radar device.

[0096] Hereinafter, an embodiment of one aspect of the present invention will be described in detail with reference to the accompanying drawings. In the embodiment, the same components are denoted by the same reference numerals, and their descriptions will be omitted to avoid duplication.

[0097] Furthermore, the following describes a configuration in which a radar device transmits code-division-multiplexed different transmission signals from multiple transmission antennas in a transmission branch, and separates each transmission signal in a reception branch for reception processing. However, the configuration of the radar device is not limited to this configuration; a configuration in which frequency-division-multiplexed different transmission signals are transmitted from multiple transmission antennas in a transmission branch, and separates each transmission signal in a reception branch for reception processing can also be employed. Similarly, a radar device configuration in which time-division-multiplexed transmission signals are transmitted from multiple transmission antennas in a transmission branch, and reception processing can be performed in a reception branch can also be employed.

[0098] [Implementation Method 1]

[0099] [Structure of radar device]

[0100] Figure 3 1 is a block diagram showing the configuration of the radar device 10 according to this embodiment.

[0101] The radar device 10 includes a radar transmitting unit (transmitting branch) 100 , a radar receiving unit (receiving branch) 200 , and a reference signal generating unit 300 .

[0102] Radar transmitting unit 100 generates a high-frequency (radio frequency) radar signal (radar transmission signal) based on the reference signal received from reference signal generating unit 300. Radar transmitting unit 100 then transmits the radar transmission signal at a predetermined transmission cycle using a transmission array antenna composed of multiple transmission antennas 106-1 to 106-Nt.

[0103] The radar receiving unit 200 uses a receiving array antenna comprising multiple receiving antennas 202-1 to 202-Na to receive radar transmission signals, i.e., reflected wave signals, that are reflected by targets (not shown). Using a reference signal received from the reference signal generating unit 300, the radar receiving unit 200 performs the following processing operations, synchronizing processing with the radar transmitting unit. Specifically, the radar receiving unit 200 processes the reflected wave signals received by each receiving antenna 202 to at least detect the presence of a target and estimate its direction. A target is an object detected by the radar device 10, and may include, for example, a vehicle (including four-wheeled and two-wheeled vehicles) or a person.

[0104] The reference signal generating unit 300 is connected to the radar transmitting unit 100 and the radar receiving unit 200. The reference signal generating unit 300 supplies a reference signal as a reference signal to the radar transmitting unit 100 and the radar receiving unit 200 to synchronize their processing.

[0105] [Structure of Radar Transmitting Unit 100]

[0106] The radar transmission unit 100 includes radar transmission signal generating units 101-1 to 101-Nt, wireless transmission units 105-1 to 105-Nt, and transmission antennas 106-1 to 106-Nt. Specifically, the radar transmission unit 100 includes Nt transmission antennas 106, each connected to its own radar transmission signal generating unit 101 and wireless transmission unit 105.

[0107] The radar transmission signal generating unit 101 generates a timing clock which is a predetermined multiple of the reference signal received from the reference signal generating unit 300, and generates a radar transmission signal based on the generated timing clock. Then, the radar transmission signal generating unit 101 repeatedly outputs the radar transmission signal at a predetermined radar transmission period (Tr). The radar transmission signal is transmitted at a predetermined frequency. z (k, M) = I z (k,M)+j Q z (k, M) represents the number corresponding to each transmitting antenna 106, z = 1, ..., Nt. In addition, j represents an imaginary unit, k represents a discrete time, and M represents the ordinal number of the radar transmission cycle.

[0108] Each radar transmission signal generating unit 101 includes a code generating unit 102, a modulating unit 103, and an LPF (Low Pass Filter) 104. The following describes the components of the radar transmission signal generating unit 101-z corresponding to the zth (z=1, ..., Nt) transmitting antenna 106.

[0109] Specifically, the code generation unit 102 generates a code a(z) of a code sequence with a code length L for each radar transmission period Tr. n (n=1, ..., L) (Pulse code) Code a(z) generated in each code generating unit 102-1 to 102-Nt n In (z=1, ..., Nt), codes that are weakly correlated or uncorrelated with each other are used. Examples of code sequences include Walsh-Hadamard codes, M-sequence codes, and Gold codes.

[0110] Modulation section 103 modulates code a(z) received from code generation section 102. n Pulse modulation (amplitude modulation, ASK (Amplitude Shift Keying), pulse shift keying) or phase modulation (Phase Shift Keying) is performed, and the modulated signal is output to the LPF 104 .

[0111] LPF 104 outputs signal components below a predetermined limit bandwidth among the modulated signal received from modulation section 103 to wireless transmission section 105 as a baseband radar transmission signal.

[0112] The zth (z=1,…,Nt) wireless transmitting unit 105 performs frequency conversion on the baseband radar transmission signal output from the zth radar transmission signal generating unit 101 to generate a radar transmission signal in the carrier frequency (Radio Frequency: RF) segment, which is amplified by the transmitting amplifier to the specified transmission power P [dB] and then output to the zth transmitting antenna 106.

[0113] The z-th (z=1, . . . , Nt) transmitting antenna 106 transmits the radar transmission signal output from the z-th wireless transmitting unit 105 into the air.

[0114] Figure 4 The radar transmission signal is transmitted from the Nt transmitting antennas 106 of the radar transmission unit 100. The code transmission interval Tw contains a pulse code sequence of code length L. The pulse code sequence is transmitted during the code transmission interval Tw in each radar transmission cycle Tr, and the remaining interval (Tr-Tw) is a signal-free interval. Each pulse code (a(z) n ) is pulse modulated using No samples, and each code transmission interval Tw contains a signal of Nr (=No×L) samples. That is, the sampling rate in modulation section 103 is (No×L) / Tw. Furthermore, the signal-free interval (Tr-Tw) contains Nu samples.

[0115] Furthermore, instead of the radar transmission signal generating unit 101, the radar transmission unit 100 may also include Figure 5 The radar transmission signal generating unit 101a is shown. The radar transmission signal generating unit 101a does not have Figure 3 The code generation unit 102, modulation unit 103 and LPF 104 shown in FIG are replaced by a code storage unit 111 and a DA conversion unit 112. The code storage unit 111 stores the code in advance in the code generation unit 102 ( Figure 3 ) and cyclically reads out the stored code sequence. The DA conversion unit 112 converts the code sequence (digital signal) output from the code storage unit 111 into an analog signal.

[0116] [Structure of Radar Receiving Unit 200]

[0117] exist Figure 3 In FIG, the radar receiving unit 200 includes Na receiving antennas 202 forming an array antenna. In addition, the radar receiving unit 200 includes Na antenna system processing units 201 - 1 to 201 -Na and a direction estimation unit 214 .

[0118] Each receiving antenna 202 receives a radar transmission signal reflected by a target (object), ie, a reflected wave signal, and outputs the received reflected wave signal as a received signal to the corresponding antenna system processing unit 201 .

[0119] Each antenna system processing unit 201 includes a wireless receiving unit 203 and a signal processing unit 207 .

[0120] Wireless receiving unit 203 includes amplifier 204, frequency converter 205, and quadrature detector 206. Wireless receiving unit 203 generates a timing clock that is a predetermined multiple of the reference signal received from reference signal generator 300 and operates based on the generated timing clock. Specifically, amplifier 204 amplifies the received signal received from receiving antenna 202 to a predetermined level, frequency converter 205 converts the high-frequency received signal to a baseband frequency, and quadrature detector 206 converts the baseband received signal into a baseband received signal containing an I signal and a Q signal.

[0121] The signal processing unit 207 includes AD conversion units 208 and 209 and separation units 210 - 1 to 210 -Nt.

[0122] The I signal is input from quadrature detector 206 to AD converter 208, and the Q signal is input from quadrature detector 206 to AD converter 209. AD converter 208 converts the baseband signal containing the I signal into digital data by sampling the signal in discrete time. AD converter 209 converts the baseband signal containing the Q signal into digital data by sampling the signal in discrete time.

[0123] Here, in the sampling of the AD converters 208 and 209, Ns discrete samples are performed per time Tp (=Tw / L) of one sub-pulse in the radar transmission signal. That is, the number of oversampling per one sub-pulse is Ns.

[0124] In the following description, the baseband received signal at discrete time k in the Mth radar transmission cycle Tr[M], which is the output of A / D converters 208 and 209, is represented as the complex signal x(k,M) = Ir(k,M) + j Qr(k,M). Hereinafter, the discrete time k is referenced to the start of the radar transmission cycle (Tr) (k = 1). Signal processing unit 207 operates periodically until sampling point k = (Nr + Nu)Ns / No, just before the end of the radar transmission cycle Tr. That is, k = 1, ..., (Nr + Nu)Ns / No. Here, j is an imaginary unit.

[0125] Signal processing section 207 includes Nt separation sections 210, which is equal to the number of systems corresponding to the number of transmitting antennas 106. Each separation section 210 includes a correlation operation section 211, an addition operation section 212, and a Doppler frequency analysis section 213. The following describes the configuration of the zth (z=1, ..., Nt) separation section 210.

[0126] The correlation operation unit 211 performs correlation operation on the discrete sample values x(k, M) including the discrete sample values Ir(k, M) and Qr(k, M) received from the AD conversion units 208 and 209 and the pulse code a(z) of the code length L transmitted from the radar transmission unit 100 for each radar transmission cycle Tr. n (where z=1, ..., Nt, n=1, ..., L). For example, the correlation operation unit 211 performs a correlation operation between the discrete sample value x(k, M) and the pulse code a(z) n For example, the correlation calculation value AC of the sliding correlation calculation at discrete time k in the Mth radar transmission cycle Tr[M] is (z) (k, M) is calculated based on the following formula.

[0127]

[0128] In the above formula, the asterisk (*) represents the complex conjugation operator.

[0129] For example, the correlation operation unit 211 performs the correlation operation according to the equation (1) over the entire period of k=1, ..., (Nr+Nu)Ns / No.

[0130] Furthermore, the correlation operation is not limited to the case where the correlation operation is performed for k = 1, ..., (Nr + Nu) Ns / No. The correlation operation unit 211 may also limit the measurement range (i.e., the range of k) according to the target existence range of the radar device 10. As a result, the amount of calculation processing of the correlation operation unit 211 can be reduced in the radar device 10. For example, the correlation operation unit 211 may limit the measurement range to k = Ns (L + 1), ..., (Nr + Nu) Ns / No - NsL. In this case, Figure 6 As shown, the radar device 10 does not perform measurement in a time interval corresponding to the code transmission interval Tw.

[0131] Thus, even if the radar transmission signal directly enters the radar receiving unit 200, the processing of the correlation calculation unit 211 is not performed during the period of the radar transmission signal entering the radar receiving unit 200 (at least during a period of less than τ1), so the radar device 10 can perform measurements without the influence of the entering signal. Furthermore, when the measurement range (range k) is limited, the processing of the addition unit 212, Doppler frequency analysis unit 213, and direction estimation unit 214 described below can also be similarly applied to the processing within the limited measurement range (range k). This reduces the amount of processing in each component and reduces the power consumption of the radar receiving unit 200.

[0132] The adding unit 212 uses the correlation calculation value AC received from the correlation calculation unit 211 for each discrete time k of the M-th radar transmission period Tr. (z) (k, M), the correlation calculation value AC is performed during the entire period (Tr×Np) of the radar transmission cycle Tr of the predetermined number of times (Np times). (z) Addition (coherent integration) of (k, M): The addition (coherent integration) processing of the number of additions Np in the entire period (Tr×Np) is expressed by the following equation.

[0133]

[0134] Among them, CI (z) (k, M) represents the added value of the correlation value (hereinafter referred to as the correlation added value), Np is an integer greater than or equal to 1, and m is an integer greater than or equal to 1 representing the ordinal number of additions when Np is the number of additions in adding section 212 as a unit. Furthermore, z = 1, ..., Nt.

[0135] The adding unit 212 performs Np additions on the output of the correlation calculating unit 211 obtained in units of the radar transmission period Tr. (z) (k, Np(m-1)+1)~AC (z) (k, Np×m) is used as a unit, and the correlation value CI is calculated for each discrete time k by aligning the timing of the discrete time k and performing the addition operation. (z) (k, M). Thus, by adding the correlation values Np times, adding unit 212 can improve the SNR of the reflected wave signal within the range where the reflected wave signal from the target has a high correlation. Consequently, radar receiving unit 200 can improve measurement performance related to estimating the target's arrival distance.

[0136] Furthermore, to achieve an ideal addition gain, the phase components of the correlation values must be aligned within a certain range within the addition interval (number of additions Np) of the correlation values. Specifically, number of additions Np is preferably set based on the assumed maximum 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. Consequently, the period of high correlation becomes shorter, so a smaller number of additions Np reduces the gain improvement effect of the addition in adding section 212.

[0137] The Doppler frequency analysis unit 213 converts the Nc outputs of the addition unit 212 obtained at each discrete time k, namely, CI (z) (k, Nc(w-1)+1)~CI (z) (k, Nc×w) is used as a unit, and coherent integration is performed at the timing of the discrete time k. For example, as shown in the following equation, Doppler frequency analysis section 213 corrects the phase variation corresponding to 2Nf different Doppler frequencies fsΔΦ by Φ(fs) = 2πfs(Tr×Np)ΔΦ, and then performs coherent integration.

[0138]

[0139] Among them, FT_CI (z) Nant (k, fs, w) is the w-th output from the Doppler frequency analysis unit 213 and represents the coherent integration result of the Doppler frequency fsΔΦ at discrete time k in the Nant 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 1, and ΔΦ is a phase rotation unit.

[0140] Thus, each antenna system processing unit 201 obtains the coherent integration result corresponding to 2Nf Doppler frequency components at each discrete time k, that is, FT_CI, for each of the multiple Np×Nc periods (Tr×Np×Nc) of the radar transmission cycle Tr. (z) Nant (k, -Nf+1, w), ..., FT_CI (z) Nant (k, Nf-1, w) Note that j is an imaginary unit, and z = 1, ..., Nt.

[0141] When ΔΦ=1 / Nc, the processing of the Doppler frequency analysis unit 213 is equivalent to performing discrete Fourier transform (DFT) processing on the output of the addition unit 212 at a sampling interval Tm=(Tr×Np) and a sampling frequency fm=1 / Tm.

[0142] Furthermore, by setting Nf to a power of 2, Fast Fourier Transform (FFT) processing can be applied in the Doppler frequency analysis unit 213, thereby reducing the amount of computational processing. (z) The zero padding process of (k, Nc(w-1)+q)=0 can be similarly applied to the FFT process, and the amount of calculation processing can be reduced.

[0143] Furthermore, the Doppler frequency analysis unit 213 may perform a process of successively calculating the product-sum operation shown in the above equation (3) instead of the FFT process. That is, the Doppler frequency analysis unit 213 may also calculate the Nc outputs of the addition unit 212 obtained at each discrete time k, i.e., CI (z) (k, Nc(w-1)+q+1), generating coefficients corresponding to fs=-Nf+1, ..., 0, ..., Nf-1 The product-sum operation is performed successively, where q = 0 to Nc - 1.

[0144] In the following description, the w-th output FT_CI obtained by performing the same processing in each of Na antenna system processing units 201 is referred to as FT_CI. (z) 1 (k, fs, w), FT_CI (z) 2 (k, fs, w), …, FT_CI (z) Na (k, fs, w) is expressed as a 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 transmit antennas Nt and the number of receive antennas Na. The virtual receive array correlation vector h(k, fs, w) is used in the later description of the process of estimating the direction of the reflected wave signal from the target based on the phase difference between receive antennas 202. Here, z = 1, ..., Nt, and b = 1, ..., Na.

[0145]

[0146]

[0147] The above describes the processing in each component of the signal processing unit 207.

[0148] The direction estimation unit 214 uses the array correction value h_cal to calculate the virtual reception 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] Calculate the virtual receiving array correlation vector h after correcting the phase deviation and amplitude deviation between the antenna system processing units 201 _after_cal (k, fs, w). Virtual receiving array correlation vector h _after_cal (k, fs, w) is expressed by the following formula: Furthermore, y = 1, ..., (Nt × Na).

[0149] h _after_cal (k,fs,w)=CA h(k,fs,w)

[0150]

[0151] The virtual receiving array correlation vector h after correcting the inter-antenna bias _after_cal (k, fs, w) is a column vector consisting of Na×Nr elements. In the following, the virtual receiving array correlation vector h _after_cal Each element of (k, fs, w) is represented by h1(k, fs, w), ..., h Na×Nr (k, fs, w), description of the direction estimation process.

[0152] [Antenna Configuration in Radar Device 10]

[0153] The arrangement of the Nt transmitting antennas 106 and the Na receiving antennas 202 in the radar apparatus 10 having the above configuration will be described.

[0154] The Nt transmitting antennas 106 and the Na receiving antennas 202 are arranged at unequal intervals in the horizontal direction and the vertical direction.

[0155] Specifically, N arranged in a straight line in the horizontal direction TH The element spacing of the transmitting antennas 106 (sometimes also expressed as Nt1) and the N elements arranged in a straight line in the horizontal direction RH The element spacings of the receiving antennas 202 (sometimes also expressed as Na1) are respectively predetermined values d H (corresponding to the first predetermined value), these element intervals all have different values.

[0156] Similarly, N arranged in a straight line in the vertical direction TV N TV The element spacing of the transmitting antennas 106 (sometimes also expressed as Nt2) and the N elements arranged in a straight line in the vertical direction RVThe element spacings of the receiving antennas 202 (sometimes expressed as Na2) are respectively predetermined values d V (corresponding to the second predetermined value), these element intervals all have different values.

[0157] Furthermore, in the arrangement of the transmitting antenna 106 and the receiving antenna 202 in this embodiment, it is assumed that the following constraints are satisfied.

[0158] Furthermore, let N be the number of antenna elements arranged on a straight line in the horizontal direction of the transmitting antenna 106. TH Root, set the element spacing to α1×d H ,α2×d H ,…,α NTH－1 ×d H In addition, the number of antenna elements arranged on a straight line in the horizontal direction of the receiving antenna 202 is N. RH Root, set the element spacing to β1×d H , β2×d H ,…,β NRH－1 ×d H .

[0159] Furthermore, the number of antenna elements arranged on a straight line in the vertical direction of the transmitting antenna 106 is N. TV Root, set the element spacing to γ1×d V ,γ2×d V ,…,γ NTV－1 ×d V In addition, the number of antenna elements arranged on a straight line in the vertical direction of the receiving antenna 202 is N. RV Root, set the element spacing to η1×d V ,η2×d V ,…,η NRV－1 ×d V .

[0160] <Condition A-1>

[0161] The sum of the element spacings of the receiving antennas 202 arranged in a straight line in the horizontal direction (the horizontal aperture length of the receiving antennas 202 ) is smaller than the minimum value of the element spacings of the transmitting antennas 106 arranged in a straight line in the horizontal direction.

[0162] min(α1,α2,…)>(β1+β2+…)

[0163] Alternatively, the sum of the element spacings of the transmitting antennas 106 arranged in a straight line in the horizontal direction (the horizontal aperture length of the transmitting antennas 106 ) is smaller than the minimum value of the element spacings of the receiving antennas 202 arranged in a straight line in the horizontal direction.

[0164] min(β1,β2,…)>(α1+α2+…)

[0165] That is, in the horizontal direction, the sum of the element spacings of one of the transmitting antenna 106 and the receiving antenna 202 is smaller than the minimum value of the element spacing of the other antenna.

[0166] By satisfying condition A-1, the virtual receiving array contains N TH ×N RH A horizontal linear array of roots. For example, N TH =N RH =3, the horizontal linear array is composed of elements arranged in the following positions.

[0167] {0, β1, β1+β2,

[0168] α1, α1+β1, α1+β1+β2,

[0169] α2, α2+β1, α2+β1+β2}×d H

[0170] <Condition A-2>

[0171] As a virtual receiving array of Nt×Na, N TH ×N RH The distance between any two elements in the horizontal linear array of the root is α nth , β nrh is configured so that d is increased each time H , up to 1×d H , 2×d H , 3×d H ~n×d H (n is an integer greater than or equal to 2). The above-mentioned predetermined number is the maximum natural number that can be taken by the following formula.

[0172]

[0173] <Condition B-1>

[0174] The sum of the element spacings of the receiving antennas 202 arranged in a straight line in the vertical direction (the vertical aperture length of the receiving antennas 202 ) is smaller than the minimum value of the element spacings of the transmitting antennas 106 arranged in a straight line in the vertical direction.

[0175] min(γ1, γ2,…)>(η1+η2+…)

[0176] Alternatively, the sum of the element spacings of the transmitting antennas 106 arranged on a straight line in the vertical direction (the vertical aperture length of the transmitting antennas 106 ) is smaller than the minimum value of the element spacings of the receiving antennas 202 arranged on a straight line in the vertical direction.

[0177] min(η1, η2,…)>(γ1+γ2+…)

[0178] That is, in the vertical direction, the sum of the element spacings of one of the transmitting antenna 106 and the receiving antenna 202 is smaller than the minimum value of the element spacing of the other antenna.

[0179] By satisfying condition B-1, the virtual receiving array contains N TV ×N RV A vertical linear array of roots. For example, N TV =N RV =3, the vertical linear array is composed of elements in the following arrangement positions.

[0180] {0, η1, η1+η2,

[0181] γ1, γ1+η1, γ1+η1+η2,

[0182] γ2, γ2+η1, γ2+η1+η2}×d V

[0183] <Condition B-2>

[0184] In the Nt×Na virtual receiving array, N TV ×N RV The distance between any two elements of the linear array in the vertical direction of the root is γ ntv ,η nrv is configured so that d is increased each time V , up to 1×d V , 2×d V , 3×d V ~n×d V (n is an integer greater than or equal to 2). The above-mentioned predetermined number is the maximum natural number that can be taken by the following formula.

[0185]

[0186] The conditions of A-1, A-2, B-1, and B-2 have been described above.

[0187] By satisfying the conditions A-1, A-2, B-1, and B-2, the virtual receiving array is an array configuration that minimizes the redundancy of the element spacing between any two array elements in the longest unequally spaced linear array in the horizontal direction and the longest unequally spaced linear array in the vertical direction (Minimum Redundancy Array. For example, refer to reference non-patent document 1). As a result, the radar device can improve the angular resolution by increasing the array aperture, and for each basic unit (for example, d H d V : about 0.5λ), spatial sampling based on array elements can be performed, so the grating lobes and side lobes can be suppressed.

[0188] (Refer to non-patent document 1) A. Moffet, "Minimum-redundancy linear arrays", Antennas and Propagation, IEEE Transactions on, vol. 16, No. 2, (1968), pp. 172-175.

[0189] then, Figure 7A : shows an example of the arrangement of the transmitting antenna 106 and the receiving antenna 202. Figure 7B Indicates passing Figure 7A The antenna configuration shown results in the configuration of the virtual receive array.

[0190] Here, it is assumed that the number of transmitting antennas 106 is Nt = 4 and the number of receiving antennas 202 is Na = 4. Furthermore, the four transmitting antennas 106 are denoted by Tx#1 to Tx#4, and the four receiving antennas 202 are denoted by Rx#1 to Rx#4.

[0191] exist Figure 7A In the figure, the transmitting antennas Tx#1 to Tx#4 are based on the upper end of the three antennas configured in the vertical direction, that is, the transmitting antenna Tx#1, and one more antenna is configured in the horizontal right direction (rotating the L shape by +90°). The receiving antennas Rx#1 to Rx#4 are based on the right end of the three antennas configured in the horizontal direction, that is, the receiving antenna Rx#3, and one more antenna is configured in the vertical upward direction (rotating the L shape by -90°).

[0192] In addition, Figure 7A 、 Figure 7B In, d H The basic unit of horizontal element spacing, d V The basic unit that represents the vertical spacing of elements. Figure 7A The horizontal element spacing of the transmitting antenna 106 is 7d.H , the vertical element spacing is d V and 2d V In addition, Figure 7A The horizontal element spacing of the receiving antenna 202 is 2d. H and d H , the vertical element spacing is 7d V .

[0193] exist Figure 7A In the horizontal direction, the sum of the element spacings of the receiving antenna 202 (3d H ) is smaller than the minimum value (7d) of the element spacing of the transmitting antenna 106 H ). In addition, Figure 7A In the vertical direction, the sum of the element spacings of the transmitting antenna 106 (3d H ) is smaller than the minimum value (7d) of the element spacing of the receiving antenna 202 H ).Right now, Figure 7A The antenna configuration satisfies the above conditions A-1 and B-1.

[0194] In addition, Figure 7A In the horizontal direction, N TH The transmitting antennas 106 and N RH The maximum value (7d) of the element spacing of the transmitting antenna 106 with the smaller number of antennas among the receiving antennas 202 H ) is greater than the maximum value (2d H ). Similarly, in Figure 7A In the vertical direction, N TV The transmitting antennas 106 and N RV The maximum value (7d) of the element spacing of the receiving antenna 202 with the smaller number of antennas among the receiving antennas 202 H ) is greater than the maximum value (2d H ).

[0195] Furthermore, it is preferred that N TH ×N TV The maximum number of Nt transmitting antennas 106 is configured so that N RH ×N RV To configure Na receiving antennas 202 for maximum. For example, Figure 7A In order to make (N TH ×N TV )=(2×3) to configure Nt(=4) transmitting antennas 106 so that (N RH ×N RV)=(3×2), Na (=4) receiving antennas 202 are arranged. In this way, the aperture area of the virtual receiving array composed of Nt transmitting antennas 106 and Na receiving antennas 202 can be maximized.

[0196] Through the above Figure 7A The antenna configuration shown is composed of Figure 7B The configuration of the virtual receiving array shown has the following characteristics.

[0197] (1) Horizontal direction

[0198] exist Figure 7A In the horizontal direction, the components are spaced 7d apart. H The two transmitting antennas Tx#1 and Tx#4 are configured and the horizontal direction is based on the element spacing of 2d H d H The horizontal position relationship between the three configured receiving antennas Rx#1, Rx#2, and Rx#3, Figure 7B The virtual receiving array shown contains elements spaced 2d apart in the horizontal direction. H d H 、4d H , 2d H d H The horizontal virtual linear array antenna HLA (with 6 elements arranged on a straight line) Figure 7B VA#1, VA#5, VA#9, VA#4, VA#8, VA#12) are surrounded by dotted lines.

[0199] Taking the horizontal position of VA#1 as a reference, the horizontal coordinates (x1, x2, x3, x4, x5, x6) of each of the six elements (VA#1, VA#5, VA#9, VA#4, VA#8, VA#12) constituting the horizontal virtual linear array antenna HLA are (x1, x2, x3, x4, x5, x6) = [0, 2d H , 3d H , 7d H , 9d H , 10d H ].

[0200] Here, the element spacing between any two different elements included in the horizontal virtual linear array antenna HLA is |x A –x B |(where A and B are integers from 1 to 6, A≠B) is {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}×d H That is, by using the 6-element horizontal virtual linear array antenna HLA, it is possible to virtually regard the basic unit d in the horizontal direction as HArrival direction estimation for an 11-element equally spaced linear array as the element spacing.

[0201] For example, by setting d H =0.5λ, the radar device 10 can estimate the direction of arrival while suppressing the occurrence of grating lobes over the entire wide range of ±90° in the horizontal direction. In addition, since the array aperture length is 10d H =5λ, and the beam width BW is approximately 8°, so the radar device 10 can achieve a high angular resolution of BW=10° or less.

[0202] Specifically, horizontal direction estimation processing in direction estimation section 214 is performed as follows.

[0203] First, in Figure 7B For example, the following combination of virtual receiving arrays in the horizontal direction is used to obtain {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}×d H The element spacing of 2 elements.

[0204] 1×d H Component spacing: VA#5, VA#9 combination

[0205] 2×d H Component spacing: VA#4, VA#8 combination

[0206] 3×d H Component spacing: Combination of VA#1, VA#9

[0207] 4×d H Component spacing: VA#9, VA#4 combination

[0208] 5×d H Component spacing: VA#5, VA#4 combination

[0209] 6×d H Component spacing: VA#9, VA#8 combination

[0210] 7×d H Component spacing: Combination of VA#1, VA#4

[0211] 8×d H Component spacing: VA#5, VA#12 combination

[0212] 9×d H Component spacing: Combination of VA#1, VA#8

[0213] 10×d H Component spacing: Combination of VA#1, VA#12

[0214] That is, N arranged on a straight line in the horizontal direction TH ×N RH The element spacing between any two virtual antenna elements (VA) of the root is d H Any two virtual antenna elements are separated by a distance d H The element spacing is an integer multiple of , and the element spacing includes all intervals from 1 times to the specified value times. That is, Figure 7A The antenna configuration satisfies the above-mentioned condition A-2.

[0215] Furthermore, when there are multiple combinations of elements with the same element interval, one of them may be selected, or an addition averaging process may be applied to multiple combinations (this example shows one selection).

[0216] The element number (VA#) of the virtual receiving array corresponds to the virtual receiving array correlation vector h after correcting the inter-antenna bias shown in equation (6): _after_cal The element number of the column vector of (k, fs, w). For example, VA#1 corresponds to h _after_cal The first element h1(k, fs, w) of the column vector element (k, fs, w) is the same for the other VA#2 to VA#16.

[0217] The azimuth estimation unit 214 generates a horizontal basic unit d based on the combination of the above-mentioned element spacing and the virtual receiving array elements. H The correlation vector h of the 11-element equally spaced linear array as the element spacing VAH (k, fs, w). Correlation vector h of an equally spaced linear array VAH (k, fs, w) is expressed as follows. VAH The number of elements in (k, fs, w) is represented by N VAH (exist Figure 7B Chinese N VAH =11).

[0218]

[0219] In the horizontal arrival direction estimation, the azimuth estimation unit 214 converts the direction estimation evaluation function value P H The azimuth direction θ in (θ, k, fs, w) is variable within a specified angle range to calculate the spatial distribution, and the maximum peak values of the calculated spatial distribution are extracted in a specified number in descending order, and the azimuth direction of the maximum peak is output as the estimated value of the arrival direction.

[0220] Furthermore, the evaluation function value P H(θ, k, fs, w) Various methods are available depending on the direction of arrival estimation algorithm. For example, the estimation method using an array antenna disclosed in Reference Non-Patent Document 2 can also be used. Furthermore, when multiple waves with high correlation arrive, various direction of arrival estimation algorithms can be applied after applying a spatial smoothing method to suppress the correlation. In this case, the same applies to the direction of arrival estimation process described below.

[0221] (Refer to Non-Patent Document 2) Direction-of-arrival estimation using signal subspace modeling Cadzow, JA; Aerospace and Electronic Systems, IEEE Transactions on Volume: 28, Issue: 1 Publication Year: 1992, Pages: 64-79

[0222] For example, the beamforming method can be expressed as follows: Furthermore, the so-called Capon and MUSIC methods are also applicable in the same manner.

[0223] P H (θ u ,k,fs,w)=|a H (θ u ) H h VAH (k,fs,w)| 2 (10)

[0224]

[0225] Here, the superscript H is the Hermitian transposition operator. In addition, a H (θ u ) represents the orientation direction θ u The direction vector of the virtual receiving array of the incoming wave.

[0226] In addition, the azimuth direction θ u It is the value of a vector that changes at a predetermined azimuth interval β1 within the azimuth range for the arrival direction estimation. u It is set as follows.

[0227] θ u =θmin+uβ1, u=0,…,NU

[0228] NU=floor[(θmax-θmin) / β1]+1

[0229] Here, floor(x) is a function that returns the maximum integer value that does not exceed the real number x.

[0230] Figure 8 It represents the direction estimation result (computer simulation result) obtained using the above structure. Figure 8 In the simulation, the beamforming method is used and the target direction is set to 0°. Figure 8 The direction estimation result shown is that the basic unit d in the horizontal direction is virtually regarded as H Results of direction of arrival estimation for an 11-element equally spaced linear array as element spacing.

[0231] like Figure 8 As shown, it can be seen that the beam width BW of the beam in the target direction of 0° is about 8°, a sidelobe level of 13 dB or less is obtained, and no grating lobe occurs.

[0232] (2) Vertical direction

[0233] exist Figure 7A In the vertical direction, according to the element spacing d V , 2d V The three transmitting antennas Tx#1, Tx#2, and Tx#3 are configured in the vertical direction according to the element spacing of 7d. V The vertical position relationship between the two configured receiving antennas Rx#3 and Rx#4, Figure 7B The virtual receiving array shown includes elements spaced 2d apart in the vertical direction. V d V 、4d V , 2d V d V A 6-element vertical virtual linear array antenna VLA (with Figure 7B VA#11, VA#10, VA#9, VA#15, VA#14, VA#13) are enclosed by dotted lines.

[0234] With the vertical position of VA#11 as a reference, the vertical coordinates (y1, y2, y3, y4, y5, y6) of the six elements (VA#11, VA#10, VA#9, VA#15, VA#14, VA#13) constituting the vertical virtual linear array antenna VLA are (y1, y2, y3, y4, y5, y6) = [0, 2d V , 3d V , 7d V , 9d V , 10d V ].

[0235] Here, the element spacing between any two different elements included in the vertical virtual linear array antenna VLA is |y A –y B |(where A and B are integers from 1 to 6, A≠B) is {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}×d V That is, the 6-element vertical virtual linear array antenna VLA can be virtually regarded as having an element spacing in the vertical direction as a basic unit d V The radar device 10 has an 11-element equally spaced linear array, and is capable of estimating the direction of arrival with high angular resolution.

[0236] For example, in d V =0.5λ, the radar device 10 can estimate the direction of arrival while suppressing the occurrence of grating lobes over the entire wide range of ±90° in the vertical direction. In addition, since the array aperture length is 10d V =5λ, the beam width BW is approximately 8°, and the radar device 10 can achieve a high angular resolution of BW=10° or less.

[0237] Specifically, vertical direction estimation processing in direction estimation section 214 is performed as follows.

[0238] First, for example, the following combinations of virtual receiving arrays in the vertical direction are used to obtain Figure 7B As the above {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}×d V The element spacing of 2 elements.

[0239] 1×d V The element spacing is obtained by combining VA#10 and VA#9.

[0240] 2×d V Component spacing: VA#11, VA#10 combination

[0241] 3×d V Component spacing: Combination of VA#11, VA#9

[0242] 4×d V Component spacing: VA#9, VA#15 combination

[0243] 5×d V Component spacing: VA#10, VA#15 combination

[0244] 6×d V Component spacing: VA#9, VA#14 combination

[0245] 7×d VComponent spacing: VA#10, VA#14 combination

[0246] 8×d V Component spacing: VA#10, VA#13 combination

[0247] 9×d V Component spacing: Combination of VA#11, VA#14

[0248] 10×d V Component spacing: Combination of VA#11, VA#13

[0249] That is, N arranged on a straight line in the vertical direction TV ×N RV The element spacing between any two virtual antenna elements (VA) of the root is d V Any two virtual antenna elements are separated by a distance d V The element spacing is an integer multiple of , and the element spacing includes all intervals from 1 times to the specified value times. That is, Figure 7A The antenna configuration satisfies the above-mentioned condition B-2.

[0250] Furthermore, when there are multiple combinations of elements with the same element interval, one of them may be selected, or an addition averaging process may be applied to multiple combinations (this example shows one selection).

[0251] The element number (VA#) of the virtual receiving array corresponds to the virtual receiving array correlation vector h after correcting the inter-antenna bias shown in equation (6): _after_cal The element number of the column vector of (k, fs, w). For example, VA#1 corresponds to h _after_cal The first element h1(k, fs, w) of the column vector element (k, fs, w) is the same for the other VA#2 to VA#16.

[0252] The azimuth estimation unit 214 generates a vertical basic unit d based on the combination of the above-mentioned element spacing and the virtual receiving array elements. V The correlation vector h of the 11-element equally spaced linear array as the element spacing VAV (k, fs, w). Correlation vector h of an equally spaced linear array VAV (k, fs, w) is expressed as follows. VAV The number of elements in (k, fs, w) is represented by N VAV (exist Figure 7B Chinese N VAV =11).

[0253]

[0254] In the vertical arrival direction estimation, the azimuth estimation unit 214 converts the direction estimation evaluation function value P V ( The elevation angle direction φ in k, fs, w) is variable within a specified angle range to calculate the spatial distribution, the maximum peak values of the calculated spatial distribution are extracted in descending order, and the elevation angle direction of the maximum peak is output as the estimated value of the arrival direction.

[0255] Furthermore, the evaluation function value P V (φ, k, fs, w) Various methods are available depending on the direction of arrival estimation algorithm. For example, the estimation method using an array antenna disclosed in Reference Non-Patent Document 2 can also be used. Furthermore, when multiple waves with high correlation arrive, various direction of arrival estimation algorithms can be applied after applying a spatial smoothing method to suppress the correlation. In this case, the same applies to the direction of arrival estimation process described below.

[0256] For example, the beamforming method can be expressed as follows: Furthermore, the so-called Capon and MUSIC methods are also applicable in the same manner.

[0257] P V (φ v ,k,fs,w)=|a V (φ v ) H h VAV (k,fs,w)| 2 (13)

[0258]

[0259] Here, the superscript H is the Hermitian transposition operator. In addition, a V (φ V ) represents the elevation angle φ V The direction vector of the virtual receiving array of the incoming wave.

[0260] In addition, φ V It is a value that changes at a predetermined azimuth interval β2 within the elevation angle range for estimating the direction of arrival. V u It is set as follows.

[0261] φ V =φmin+vβ2, v=0,…,NV

[0262] NV=floor[(φmax-φmin) / β2]+1

[0263] The above explains Figure 7B Features of the virtual receive array configuration are shown.

[0264] In this embodiment, it is assumed that the direction vectors of the virtual receiving arrays are calculated in advance based on virtual receiving array configurations VA#1, ..., VA#(Nt×Na) described later.

[0265] Furthermore, the time information k can also be converted into distance information and output. To convert the time information k into distance information R(k), the following formula can be used: Where Tw represents the code transmission interval, L represents the pulse code length, and C0 represents the speed of light.

[0266]

[0267] Furthermore, the Doppler frequency information (fsΔΦ) may be converted into a relative velocity component and outputted. The Doppler frequency fsΔΦ may be converted into a relative velocity component vd(fs) using the following equation.

[0268] Here, λ is the wavelength of the carrier frequency of the RF signal output from the wireless transmission unit 105 .

[0269]

[0270] As described above, in a relatively small number of antenna elements, 4 transmitting antennas and 4 receiving antennas, by using Figure 7A The array configuration shown is capable of Figure 7B The aperture area of the virtual receiving array shown is maximized in the horizontal and vertical directions.

[0271] That is, according to this embodiment, when performing two-dimensional beam scanning in the vertical and horizontal directions using a MIMO radar, the radar device 10 can maximize the aperture length of the virtual receiving array in the vertical and horizontal directions.

[0272] Furthermore, the element spacing (d H d V ) is set to, for example, 0.5λ. Radar device 10 can achieve a high resolution of approximately 8° with a Fourier beamwidth BW by using equal-amplitude weighting, i.e., Fourier beam scanning. Specifically, radar device 10 can achieve high resolution in both the horizontal and vertical directions with a low computational load, without employing a direction-of-arrival estimation algorithm capable of achieving high resolution.

[0273] As described above, in this embodiment, by using such a virtual receiving array, the angular resolution can be improved with a smaller number of antennas, and the radar device 10 can be miniaturized and cost-effective.

[0274] Furthermore, in Figure 7A In this example, the spacing between transmit antennas Tx#1-Tx#4 and receive antennas Rx#1-Rx#4 has no effect on the virtual receive array configuration. However, since the proximity of transmit antennas Tx#1-Tx#4 to receive antennas Rx#1-Rx#4 improves the coupling between the transmit and receive antennas, it is more appropriate to place transmit antennas Tx#1-Tx#4 and receive antennas Rx#1-Rx#4 as far apart as possible within the permitted antenna size. This applies to the other antenna configurations described below.

[0275] In addition, Figure 7A As an example, the antenna configuration is shown when the transmitting antenna is set to 4 elements and the receiving antenna is set to 4 elements. Figure 7A The same result can also be obtained when the transmitting antenna configuration is set as the receiving antenna configuration and the receiving antenna configuration is set as the transmitting antenna configuration. Figure 7B The virtual receiving array configuration shown has the same structure and achieves the same effect. This also applies to the other antenna configurations described later.

[0276] (Variation 1 of Implementation Method 1)

[0277] The antenna configuration when the transmitting antenna 106 is configured as 4 elements and the receiving antenna 202 is configured as 4 elements is not limited to Figure 7A The antenna configuration shown. For example, Figure 9A Another example of antenna configuration is shown in FIG. 1 , where the transmitting antenna 106 is configured as 4 elements and the receiving antenna 202 is configured as 4 elements. Figure 9B Indicates passing Figure 9A The antenna configuration shown results in the configuration of the virtual receive array.

[0278] exist Figure 9A In, with Figure 7A Similarly, the transmission antennas Tx#1 to Tx#4 are a pattern in which one more antenna is arranged horizontally to the right, with the transmission antenna Tx#1 being the top of the three antennas arranged vertically as the base point. Figure 9A In the diagram, receiving antennas Rx#1 to Rx#4 are arranged vertically with receiving antenna Rx#2 being the center of the three antennas arranged horizontally as the base point, and one more antenna is arranged vertically upward (rotated 180 degrees in a T shape).

[0279] and Figure 7B Similarly, by Figure 9A The antenna configuration shown is composed of Figure 9B The configuration of the virtual receiving array shown has the above-mentioned features (1) and (2). Figure 9A and Figure 9B , explain in detail.

[0280] (1) Horizontal direction

[0281] exist Figure 9A In the horizontal direction, the components are spaced 7d apart. H The two transmitting antennas Tx#1 and Tx#4 are configured and the horizontal direction is based on the element spacing of 2d H d H The horizontal position relationship between the three configured receiving antennas Rx#1, Rx#2, and Rx#3, Figure 9B The virtual receiving array shown includes elements spaced 2d apart in the horizontal direction. H d H 、4d H , 2d H d H The horizontal virtual linear array antenna HLA (with 6 elements arranged on a straight line) Figure 9B VA#1, VA#5, VA#9, VA#4, VA#8, VA#12) are surrounded by dotted lines.

[0282] Taking the horizontal position of VA#1 as a reference, the horizontal coordinates (x1, x2, x3, x4, x5, x6) of each of the six elements (VA#1, VA#5, VA#9, VA#4, VA#8, VA#12) constituting the horizontal virtual linear array antenna HLA are (x1, x2, x3, x4, x5, x6) = [0, 2d H , 3d H , 7d H , 9d H , 10d H ].

[0283] Here, the element spacing between any two different elements included in the horizontal virtual linear array antenna HLA is |x A -x B |(where A and B are integers from 1 to 6, A≠B) is {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}×d H That is, by using the 6-element horizontal virtual linear array antenna HLA, it can be virtually regarded as having a basic unit d in the horizontal direction. H As an equidistant linear array with 11 elements, the radar device 10 can estimate the direction of arrival with high angular resolution.

[0284] For example, in d H =0.5λ, the radar device 10 can estimate the direction of arrival while suppressing the occurrence of grating lobes over the entire wide range of ±90° in the horizontal direction. In addition, since the array aperture length is 10d H=5λ, the beam width BW is approximately 8°, and the radar device 10 can achieve a high angular resolution of BW=10° or less.

[0285] (2) Vertical direction

[0286] exist Figure 9A In the vertical direction, according to the element spacing d V , 2d V The three transmitting antennas Tx#1, Tx#2, and Tx#3 are configured in the vertical direction according to the element spacing of 7d. V The vertical position relationship between the two configured receiving antennas Rx#2 and Rx#4, Figure 9B The virtual receiving array shown contains elements spaced 2d apart in the vertical direction. V d V 、4d V , 2d V d V A 6-element vertical virtual linear array antenna VLA (with Figure 9B VA#7, VA#6, VA#5, VA#15, VA#14, VA#13) are enclosed by the dotted lines shown.

[0287] Taking the vertical position of VA#7 as a reference, the vertical coordinates (y1, y2, y3, y4, y5, y6) of each of the six elements (VA#7, VA#6, VA#5, VA#15, VA#14, VA#13) constituting the vertical virtual linear array antenna VLA are (y1, y2, y3, y4, y5, y6) = [0, 2d V , 3d V , 7d V , 9d V , 10d V ].

[0288] Here, the element spacing between any two different elements included in the vertical virtual linear array antenna VLA is |y A -y B |(where A and B are integers from 1 to 6, A≠B) is {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}×d V That is, by using a 6-element vertical virtual linear array antenna VLA, it is possible to virtually regard it as having a basic unit d in the vertical direction. V As an equidistant linear array with 11 elements, the radar device 10 can estimate the direction of arrival with high angular resolution.

[0289] For example, in d V=0.5λ, the radar device 10 can estimate the direction of arrival while suppressing the occurrence of grating lobes over the entire wide range of ±90° in the vertical direction. In addition, since the array aperture length is 10d V =5λ, the beam width BW is approximately 8°, and the radar device 10 can achieve a high angular resolution of BW=10° or less.

[0290] (Variation 2 of Implementation Method 1)

[0291] In the first embodiment, when a higher resolution of about 10° is not required as the angular resolution in either the horizontal or vertical direction, the radar device 10 may set the number of elements of the transmitting antenna 106 or the number of elements of the receiving antenna 202 to three.

[0292] As an example, the radar device 10 in which the number of elements of the transmitting antenna 106 is set to three and the number of elements of the receiving antenna 202 is set to four will be described below when a high resolution is not required as the angular resolution in the vertical direction.

[0293] Figure 10A : shows an example of the configuration of the transmitting antenna 106 and the receiving antenna 202. Figure 10B Indicates passing Figure 10A The antenna configuration shown results in the configuration of the virtual receive array.

[0294] exist Figure 10A In FIG, the three transmitting antennas 106 are represented by Tx#1 to Tx#3, and the four receiving antennas 202 are represented by Rx#1 to Rx#4. Figure 10A In the example, among the transmitting antennas Tx#1 to Tx#3, one antenna is further arranged in the horizontal right direction with a spacing narrower than the vertical element spacing, that is, transmitting antenna Tx#1, which is the upper end of the two antennas arranged in the vertical direction. (The L shape is rotated by +90°). Among the receiving antennas Rx#1 to Rx#4, one antenna is further arranged in the vertical upper direction with a spacing narrower than the horizontal element spacing, that is, receiving antenna Rx#3, which is the right end of the three antennas arranged in the horizontal direction. (The L shape is rotated by -90°).

[0295] Furthermore, in the arrangement of the transmitting antenna 106 and the receiving antenna 202 in this modification, it is assumed that the constraint conditions A-1, A-2, B-1, and B-2 described in the first embodiment are satisfied.

[0296] Depend on Figure 10A The antenna configuration shown is composed of Figure 10B The configuration of the virtual receiving array shown has the following characteristics.

[0297] (1) Horizontal direction

[0298] exist Figure 10A In the horizontal direction, the components are spaced 5d apart. H The two transmitting antennas Tx#1 and Tx#3 are configured and arranged in the horizontal direction according to the element spacing d H , 2d H The horizontal position relationship between the three configured receiving antennas Rx#1, Rx#2, and Rx#3, Figure 10B The virtual receiving array shown includes the horizontal direction according to the element spacing d H , 2d H , 2d H d H , 2d H The 6-element horizontal virtual linear array antenna HLA (with Figure 10B VA#1, VA#4, VA#7, VA#3, VA#6, VA#9) are surrounded by dotted lines.

[0299] With the horizontal position of VA#1 as a reference, the horizontal coordinates (x1, x2, x3, x4, x5, x6) of each of the six elements (VA#1, VA#4, VA#7, VA#3, VA#6, VA#9) constituting the horizontal virtual linear array antenna HLA are (x1, x2, x3, x4, x5, x6) = [0, d H , 3d H , 5d H , 6d H , 8d H ].

[0300] Here, the element spacing between any two different elements included in the horizontal virtual linear array antenna HLA is |x A -x B |(where A and B are integers from 1 to 6, A≠B) is {1, 2, 3, 4, 5, 6, 7, 8}×d H That is, by using the 6-element horizontal virtual linear array antenna HLA, it can be virtually regarded as having a basic unit d in the horizontal direction. H As a linear array with 9 elements of equal spacing, the radar device 10 can estimate the direction of arrival with high angular resolution.

[0301] For example, by setting d H =0.5λ, the radar device 10 can estimate the direction of arrival while suppressing the occurrence of grating lobes over the entire wide range of ±90° in the horizontal direction. In addition, since the array aperture length is 8d H=4λ, the beam width BW is approximately 10°, and the radar device 10 can achieve a high angular resolution of BW=10° or less.

[0302] (2) Vertical direction

[0303] exist Figure 10A In the vertical direction, according to the element spacing d V The two transmitting antennas Tx#1 and Tx#2 are configured in the vertical direction according to the element spacing of 3d V The vertical position relationship between the two configured receiving antennas Rx#3 and Rx#4, Figure 10B The virtual receiving array shown includes the vertical direction according to the element spacing d V , 2d V d V A 4-element vertical virtual linear array antenna VLA (with Figure 10B VA#8, VA#7, VA#11, VA#10) are enclosed by dotted lines.

[0304] Taking the vertical position of VA#8 as a reference, the vertical coordinates (y1, y2, y3, y4) of each of the four elements (VA#8, VA#7, VA#11, VA#10) constituting the vertical virtual linear array antenna VLA are (y1, y2, y3, y4) = [0, d V , 3d V , 4d V ].

[0305] Here, the element spacing between any two different elements included in the vertical virtual linear array antenna VLA is |y A -y B |(where A and B are integers from 1 to 4, A≠B) is {1, 2, 3, 4}×d V That is, by using a 4-element vertical virtual linear array antenna VLA, it can be virtually considered that the element spacing in the vertical direction is a basic unit d V With the 5-element equally spaced linear array, the radar device 10 can estimate the direction of arrival with high angular resolution.

[0306] For example, in d V =0.5λ, the radar device 10 can estimate the direction of arrival while suppressing the occurrence of grating lobes over the entire wide range of ±90° in the vertical direction. In addition, the radar device 10, since the array aperture length is 4d V =2λ, so the beam width BW is about 20°.

[0307] (Variation 3 of Implementation Method 1)

[0308] In Embodiment 1, in radar apparatus 10 using five or more elements as the number of elements of receiving antenna 202, the number of elements of transmitting antenna 106 may be set to three. Alternatively, in radar apparatus 10 using five or more elements as the number of elements of transmitting antenna 106, the number of elements of receiving antenna 202 may be set to three.

[0309] Hereinafter, as an example, a radar device 10 in which the number of elements of the transmitting antenna 106 is set to three and the number of elements of the receiving antenna 202 is set to five will be described.

[0310] Figure 11A : shows an example of the configuration of the transmitting antenna 106 and the receiving antenna 202. Figure 11B Indicates passing Figure 11A The antenna configuration shown results in the configuration of the virtual receive array.

[0311] exist Figure 11A In FIG, three transmitting antennas 106 are represented by Tx#1 to Tx#3, and five receiving antennas 202 are represented by Rx#1 to Rx#5. Figure 11A In the example, the transmitting antennas Tx#1 to Tx#3 are arranged with one more antenna in the horizontal right direction (rotated +90° in the L shape) with the transmitting antenna Tx#1 being the upper end of the two antennas arranged in the vertical direction as the base point. The receiving antennas Rx#1 to Rx#5 are arranged with one antenna in the vertical up and down direction (cross shape) with the receiving antenna Rx#3 being the center of the three antennas arranged in the horizontal direction as the base point. The arrangement of the receiving antennas Rx#1 to Rx#5 is not limited to a cross arrangement and can be an L-shaped arrangement or a T-shaped arrangement (for example, see the following). Figures 24A to 24F ).

[0312] Furthermore, the arrangement of transmitting antenna 106 and receiving antenna 202 in this modification satisfies the constraint conditions A-1, A-2, B-1, and B-2 described in the first embodiment.

[0313] Depend on Figure 11A The antenna configuration shown is composed of Figure 11B The configuration of the virtual receiving array shown has the following characteristics.

[0314] (1) Horizontal direction

[0315] exist Figure 11A In the horizontal direction, the components are spaced 7d apart. H The two transmitting antennas Tx#1 and Tx#3 are configured and the horizontal direction is based on the element spacing of 2d H d HThe horizontal position relationship between the three configured receiving antennas Rx#2, Rx#3, and Rx#4, Figure 11B The virtual receiving array shown includes horizontal elements spaced 2d apart. H d H 、4d H , 2d H d H The 6-element horizontal virtual linear array antenna HLA (with Figure 11B VA#4, VA#7, VA#10, VA#6, VA#9, VA#12) are surrounded by dotted lines.

[0316] Taking the horizontal position of VA#4 as a reference, the horizontal coordinates (x1, x2, x3, x4, x5, x6) of each of the six elements (VA#4, VA#7, VA#10, VA#6, VA#9, VA#12) constituting the horizontal virtual linear array antenna HLA are (x1, x2, x3, x4, x5, x6) = [0, 2d H , 3d H , 7d H , 9d H , 10d H ].

[0317] Here, the element spacing between any two different elements included in the horizontal virtual linear array antenna HLA is |x A -x B |(where A and B are integers from 1 to 6, A≠B) is {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}×d H That is, by using the 6-element horizontal virtual linear array antenna HLA, it can be virtually regarded as having the element spacing in the horizontal direction as the basic unit d H The radar device 10 has an 11-element equally spaced linear array, and is capable of estimating the direction of arrival with high angular resolution.

[0318] For example, in d H =0.5λ, the radar device 10 can estimate the direction of arrival while suppressing the occurrence of grating lobes over the entire wide range of ±90° in the horizontal direction. In addition, since the array aperture length is 10d H =5λ, the beam width BW is approximately 8°, and the radar device 10 can achieve a high angular resolution of BW=10° or less.

[0319] (2) Vertical direction

[0320] exist Figure 11A In the vertical direction, the element spacing is 7d VThe two transmitting antennas Tx#1 and Tx#2 are configured in the vertical direction according to the element spacing d V , 2d V The vertical position relationship between the three configured receiving antennas Rx#1, Rx#3, and Rx#5, Figure 11B The virtual receiving array shown includes the vertical direction according to the element spacing d V , 2d V 、4d V d V , 2d V A 6-element vertical virtual linear array antenna VLA (with Figure 11B VA#2, VA#8, VA#14, VA#1, VA#7, VA#13) are surrounded by dotted lines.

[0321] Taking the vertical position of VA#2 as a reference, the vertical coordinates (y1, y2, y3, y4, y5, y6) of each of the six elements (VA#2, VA#8, VA#14, VA#1, VA#7, VA#13) constituting the vertical virtual linear array antenna VLA are (y1, y2, y3, y4, y5, y6) = [0, d V , 3d V , 7d V , 8d V , 10d V ].

[0322] Here, the element spacing between any two different elements included in the vertical virtual linear array antenna VLA is |y A -y B |(where A and B are integers from 1 to 6, A≠B) is {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}×d V That is, by using a 6-element vertical virtual linear array antenna VLA, it can be virtually regarded as having a basic unit d of element spacing in the vertical direction. V The radar device 10 can estimate the direction of arrival with a high angular resolution by using an 11-element equally spaced linear array. V Component spacing outside.

[0323] For example, in d V =0.5λ, the radar device 10 can estimate the direction of arrival while suppressing the occurrence of grating lobes over the entire wide range of ±90° in the vertical direction. In addition, since the array aperture length is 10d V =5λ, so the beam width BW is about 8°, and the radar device 10 can achieve a high angular resolution of BW=10° or less.

[0324] [Implementation Method 2]

[0325] In order to improve the directional gain of the array antenna, a radar apparatus may employ a sub-array antenna in which each array element constituting the array antenna further includes a plurality of antenna elements (sub-arrayed antenna elements).

[0326] For example, Figure 12 It means that the radar detection range in the vertical direction can be narrowed in the radar device. The minimum element spacing in the vertical direction is 2d. V In the case of Figure 13A An example of an antenna element that uses sub-arrays. Figure 12 In the present invention, by stacking two array elements in the vertical direction and using sub-array sub-array elements, the vertical directivity can be narrowed, the radiation in unnecessary directions can be reduced, and the array element gain can be improved.

[0327] Array antenna elements are difficult to arrange at intervals narrower than the size of the array elements. For example, by stacking the array elements of a subarray antenna vertically, the size of the array elements increases to approximately one wavelength, placing limitations on the array antenna configuration for radar systems. Specifically, in a subarray antenna configuration, the minimum element spacing in the vertical direction of the array configuration must be at least a specified value.

[0328] In this way, when using a subarray antenna structure, since the size of the array elements increases, the spacing between the subarray antennas needs to be increased, and the radar device may generate grating lobes in the directivity pattern formed by the array antenna.

[0329] Therefore, in this embodiment, even when using a subarray antenna, it is described that arrival direction estimation can be performed while suppressing the occurrence of grating lobes over a wide range, thereby achieving an antenna configuration with high resolution in the vertical and horizontal directions.

[0330] The radar device of this embodiment has the same basic structure as the radar device 10 of the first embodiment, so the reference is made to Figure 3 Provide explanation.

[0331] In the following, as an example, a radar device 10 in which array elements are stacked in a vertical direction is described as sub-arrayed. However, the radar device 10 has the same features as the first embodiment, in which array elements in the horizontal direction are not sub-arrayed.

[0332] Similar to the first embodiment, Nt transmitting antennas 106 and Na receiving antennas 202 are arranged at unequal intervals in the horizontal direction and the vertical direction.

[0333] In addition, in the vertical direction (the direction of constituting the sub-array antenna), N TV The element spacing of the transmitting antenna 106 and N RV The difference in element spacing between the receiving antennas 202 at the root is the basic unit d of the element spacing in the vertical direction. V The transmitting antenna 106 and the receiving antenna 202 of this embodiment are configured by a combination of one or more. V It is set to be lower than 1λ (for example, 0.5λ). That is, the transmitting antenna 106 and the receiving antenna 202 are arranged so as to include at least one arrangement satisfying the following equation (hereinafter referred to as condition B-3).

[0334] <Condition B-3>

[0335]

[0336] Furthermore, the radar device 10 having the arrangement of the transmitting antenna 106 and the receiving antenna 202 of this embodiment satisfies A-1, A-2, and B-2 other than B-1 among the restriction conditions described in the first embodiment.

[0337] As an example, Figure 13A : shows an example of the configuration of the transmitting antenna 106 and the receiving antenna 202. Figure 13B Indicates passing Figure 13A The antenna configuration shown results in the configuration of the virtual receive array.

[0338] Here, it is assumed that the number of transmitting antennas 106 is Nt = 4 and the number of receiving antennas 202 is Na = 4. Furthermore, the four transmitting antennas 106 are denoted by Tx#1 to Tx#4, and the four receiving antennas 202 are denoted by Rx#1 to Rx#4.

[0339] exist Figure 13A In the figure, the transmitting antennas Tx#1 to Tx#4 are arranged in a pattern in which one antenna is further arranged in the horizontal right direction (the L shape is rotated +90°) with the transmitting antennas Tx#1, which is the upper end of the three antennas arranged in the vertical direction, as the base point. The receiving antennas Rx#1 to Rx#4 are arranged in a pattern in which one antenna is further arranged in the vertical upward direction (the T shape is rotated 180°) with the receiving antennas Rx#2, which is the center of the three antennas arranged in the horizontal direction, as the base point.

[0340] Depend on Figure 13A The antenna configuration shown is composed of Figure 13B The configuration of the virtual receiving array shown has the following characteristics.

[0341] (1) Horizontal direction

[0342] exist Figure 13A In the horizontal direction, the components are spaced 7d apart. H The two transmitting antennas Tx#1 and Tx#4 are configured and the horizontal direction is based on the element spacing of 2d H d H The horizontal position relationship between the three configured receiving antennas Rx#1, Rx#2, and Rx#3, Figure 13B The virtual receiving array shown includes horizontal elements spaced 2d apart. H d H 、4d H , 2d H d H The 6-element horizontal virtual linear array antenna HLA (with Figure 13B VA#1, VA#5, VA#9, VA#4, VA#8, VA#12) are surrounded by dotted lines.

[0343] Taking the horizontal position of VA#1 as a reference, the horizontal coordinates (x1, x2, x3, x4, x5, x6) of each of the six elements (VA#1, VA#5, VA#9, VA#4, VA#8, VA#12) constituting the horizontal virtual linear array antenna HLA are (x1, x2, x3, x4, x5, x6) = [0, 2d H , 3d H , 7d H , 9d H , 10d H ].

[0344] Here, the element spacing between any two different elements included in the horizontal virtual linear array antenna HLA is |x A -x B |(where A and B are integers from 1 to 6, A≠B) is {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}×d H That is, by using the 6-element horizontal virtual linear array antenna HLA, it can be virtually regarded as having a basic unit d in the horizontal direction. H As an equidistant linear array with 11 elements, the radar device 10 can estimate the direction of arrival with high angular resolution.

[0345] For example, in d H = 0.5λ, the radar device 10 can estimate the direction of arrival while suppressing the occurrence of grating lobes over the entire wide range of ±90° in the horizontal direction. H =5λ, the beam width BW is approximately 8°, and the radar device 10 can achieve a high angular resolution of BW=10° or less.

[0346] (2) Vertical direction

[0347] exist Figure 13A In the vertical direction, the element spacing is 2d V 、4d V Configure 3 transmitting antennas Tx#1, Tx#2, Tx#3 and vertically space 5d according to the element spacing V The vertical position relationship between the two configured receiving antennas Rx#2 and Rx#4, Figure 13B The virtual receiving array shown includes a vertical direction according to the element spacing 4d V d V d V , 3d V , 2d V A 6-element vertical virtual linear array antenna VLA (with Figure 13B VA#7, VA#6, VA#15, VA#5, VA#14, VA#13) are enclosed by the dotted lines shown.

[0348] Taking the vertical position of VA#7 as a reference, the vertical coordinates (y1, y2, y3, y4, y5, y6) of the six elements (VA#7, VA#6, VA#15, VA#5, VA#14, VA#13) constituting the vertical virtual linear array antenna VLA are (y1, y2, y3, y4, y5, y6) = [0, 4d V , 5d V , 6d V , 9d V , 11d V ].

[0349] Here, the element spacing between any two different elements included in the vertical virtual linear array antenna VLA is |y A -y B |(where A and B are integers from 1 to 6, A≠B) is {1, 2, 3, 4, 5, 6, 7, 9, 11}×d V That is, by using the 6-element vertical virtual linear array antenna VLA, {1, 2, 3, 4, 5, 6, 7}×d V The combination of element spacing can be virtually regarded as having an element spacing in the vertical direction of d V The radar device 10 has an 8-element equally spaced linear array, and is capable of estimating the direction of arrival with high angular resolution.

[0350] Furthermore, by using {1, 2, 3, 4, 5, 6, 7, 9, 11}×d VThe combination of element spacing is virtually regarded as having a basic unit d in the vertical direction. V 2 times the element spacing 2d V The radar device 10 can also estimate the direction of arrival even if the linear array has 10 elements. In this case, the radar device 10 is considered to have a linear array of 10 elements, and the basic unit d is used. V Compared with an 8-element equally spaced linear array with a smaller element spacing, the spatial side lobes increase slightly, but the aperture length is further expanded, so the angular resolution can be improved.

[0351] For example, in d V = 0.5λ, the radar device 10 can estimate the direction of arrival while suppressing the occurrence of grating lobes over the entire wide range of ±90° in the vertical direction. V When estimating the direction of arrival using an 8-element equally spaced linear array as the element spacing, the array aperture length is 7d. V =3.5λ, so in the radar device 10, the beam width BW is about 11°. In addition, it is assumed that there is a virtual element spacing of 2d. V In the case of a 10-element linear array for direction of arrival estimation, since the array aperture length is 11d V =5.5λ, the beam width BW is approximately 7°, and the radar device 10 can achieve a high angular resolution of BW=10° or less.

[0352] In this way, in d V =0.5λ, in Figure 13A (|(The vertical element spacing of Tx#2 and Tx#3 is 4d V )-(The vertical element spacing of Rx#2 and Rx#4 is 5d V )|=d V ≒0.5λ<1λ, the radar device 10 satisfies the condition B-3. Figure 13B In the vertical arrangement of the virtual receiving array, the element spacing of 1λ or less (≒0.5λ) contains one or more ( Figure 13B VA#6 and VA#15 element spacing, VA#15 and VA#5 element spacing). Even a subarray antenna structure can be virtually considered to have a basic unit d in the vertical direction. V As an equally spaced linear array of multiple elements, use Figure 13A The radar device 10 is capable of estimating the direction of arrival with high angular resolution.

[0353] Figure 14 Indicates the direction estimation result (computer simulation result) obtained using the above structure. Figure 14 In the simulation, the beamforming method is used and the target direction is set to 0°. Figure 14 The direction estimation result (8-element DOA) indicated by the solid line is virtually regarded as the basic unit d in the vertical direction. V The direction of arrival estimation result (10-element DOA) is obtained by using an 8-element equally spaced linear array as the element spacing. The direction estimation result (10-element DOA) indicated by the dotted line is assumed to include the basic unit d in the vertical direction. V Results of direction of arrival estimation using a 10-element linear array with twice the element spacing.

[0354] like Figure 14 As shown in FIG. 1 , it can be seen that in the radar device 10 which is virtually regarded as an 8-element equally spaced linear array, the beam width BW of the beam at 0° in the target direction is about 11°, and a sidelobe level of 13 dB or less is obtained. Figure 14 As shown in FIG. 1 , it can be seen that in the radar device 10 that is virtually considered as a linear array of 10 elements, the side lobes increase compared to the case (solid line) that is virtually considered as an equally spaced linear array of 8 elements, but the beam width BW of the beam at 0° in the target direction is narrowed. Figure 14 As shown, it can be seen that no grating lobe occurs in both parties.

[0355] As described above, according to this embodiment, when using a MIMO radar with a subarray antenna configuration to perform two-dimensional beam scanning in the vertical and horizontal directions, the aperture length of the virtual receiving array in the vertical and horizontal directions can be maximized in radar apparatus 10. Specifically, according to this embodiment, by using a virtual receiving array, angular resolution can be improved with a reduced number of antenna elements, enabling radar apparatus 10 to be miniaturized and cost-effective.

[0356] (Change 1 of Implementation Method 2)

[0357] As long as the vertical dimension of the array elements stacked and sub-arrayed in the vertical direction is less than 2d V , then the above Figure 13A The antenna configuration in the MIMO radar can be applied.

[0358] exist Figure 13A In the configuration, the minimum vertical spacing is the spacing between Tx#1 and Tx#2, which is 2d V On the other hand, in Figure 15A In the configuration, the minimum spacing between the components in the vertical direction is the spacing between Rx#2 and Rx#4, which is 3d V .therefore, Figure 15AThe configuration can be applied to antenna elements in a sub-array with a larger vertical size. By using antenna elements in a sub-array with a larger vertical size, the vertical gain can be increased and the vertical directivity can be reduced.

[0359] On the other hand, the vertical dimension of the array elements stacked and sub-arrayed in the vertical direction is greater than 2d V , for example, Figure 15C As shown, when three antenna elements are stacked in a vertical direction and antenna elements are used in a sub-array, the antenna configuration described below can be used. V The following are examples of applicable antenna configurations.

[0360] Figure 15A : shows an example of the configuration of the transmitting antenna 106 and the receiving antenna 202. Figure 15B Indicates passing Figure 15A The antenna configuration shown results in the configuration of the virtual receive array.

[0361] Here, it is assumed that the number of transmitting antennas 106 is Nt = 4 and the number of receiving antennas 202 is Na = 4. Furthermore, the four transmitting antennas 106 are denoted by Tx#1 to Tx#4, and the four receiving antennas 202 are denoted by Rx#1 to Rx#4.

[0362] exist Figure 15A In the figure, the transmitting antennas Tx#1 to Tx#4 are based on the upper end of the three antennas configured in the vertical direction, that is, the transmitting antenna Tx#1, and one more antenna is configured in the horizontal right direction (rotating the L shape by +90°). The receiving antennas Rx#1 to Rx#4 are based on the center of the three antennas configured in the horizontal direction, that is, the receiving antenna Rx#2, and one more antenna is configured in the vertical upper direction (rotating the T shape by 180°).

[0363] pass Figure 15A The antenna configuration shown is composed of Figure 15B The configuration of the virtual receiving array shown has the following characteristics.

[0364] (1) Horizontal direction

[0365] exist Figure 15A In the horizontal direction, the components are spaced 7d apart. H The two transmitting antennas Tx#1 and Tx#4 are configured and the horizontal direction is based on the element spacing of 2d H d H The horizontal position relationship between the three configured receiving antennas Rx#1, Rx#2, and Rx#3, Figure 15BThe virtual receiving array shown includes horizontal elements spaced 2d apart. H d H 、4d H , 2d H d H The 6-element horizontal virtual linear array antenna HLA (with Figure 15B VA#1, VA#5, VA#9, VA#4, VA#8, VA#12) are surrounded by dotted lines.

[0366] Taking the horizontal position of VA#1 as a reference, the horizontal coordinates (x1, x2, x3, x4, x5, x6) of each of the six elements (VA#1, VA#5, VA#9, VA#4, VA#8, VA#12) constituting the horizontal virtual linear array antenna HLA are (x1, x2, x3, x4, x5, x6) = [0, 2d H , 3d H , 7d H , 9d H , 10d H ].

[0367] Here, the element spacing between any two different elements included in the horizontal virtual linear array antenna HLA is |x A -x B |(where A and B are integers from 1 to 6, A≠B) is {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}×d H That is, by using the 6-element horizontal virtual linear array antenna HLA, it can be virtually regarded as having the element spacing in the horizontal direction as the basic unit d H With the 11-element equally spaced linear array, the radar device 10 is capable of estimating the direction of arrival with high angular resolution.

[0368] For example, in d H = 0.5λ, the radar device 10 can estimate the direction of arrival while suppressing the occurrence of grating lobes over the entire wide range of ±90° in the horizontal direction. H =5λ, the beam width BW is approximately 8°, and the radar device 10 can achieve a high angular resolution of BW=10° or less.

[0369] (2) Vertical direction

[0370] exist Figure 15A In the vertical direction, the element spacing is 4d V , 5d V The three transmitting antennas Tx#1, Tx#2, and Tx#3 are configured and spaced 3d apart in the vertical direction.V The vertical position relationship between the two configured receiving antennas Rx#2 and Rx#4, Figure 15B The virtual receiving array shown includes a vertical direction according to the element spacing 3d V , 2d V , 3d V , 1d V , 3d V Six vertical virtual linear array antennas VLA (with Figure 15B VA#7, VA#15, VA#6, VA#14, VA#5, VA#13) are surrounded by dotted lines.

[0371] Taking the vertical position of VA#7 as a reference, the vertical coordinates (y1, y2, y3, y4, y5, y6) of the six elements (VA#7, VA#15, VA#6, VA#14, VA#5, VA#13) constituting the vertical virtual linear array antenna VLA are (y1, y2, y3, y4, y5, y6) = [0, 3d V , 5d V , 8d V , 9d V , 12d V ].

[0372] Here, the element spacing between any two different elements included in the vertical virtual linear array antenna VLA is |y A -y B |(where A and B are integers from 1 to 6, A≠B) is {1, 2, 3, 4, 5, 6, 7, 8, 9, 12}×d V That is, by using the 6-element vertical virtual linear array antenna VLA, {1, 2, 3, 4, 5, 6, 7, 8, 9}×d V The combination of element spacing can be virtually regarded as having the element spacing in the vertical direction as the basic unit d V The radar device 10 has a 10-element equally spaced linear array, and is capable of estimating the direction of arrival with high angular resolution.

[0373] Furthermore, by using {1, 2, 3, 4, 5, 6, 7, 8, 9, 12}×d V The combination of element spacing is virtually regarded as having a basic unit d including the vertical direction V 3 times the element spacing 3d V The radar device 10 can also estimate the direction of arrival even if the linear array has 11 elements. In this case, the radar device 10 is considered to have a linear array of 10 elements, and the basic unit d is used. VCompared with a 10-element equally spaced linear array with a fixed element spacing, the spatial side lobes increase slightly, but the aperture length is further expanded, so the angular resolution can be improved.

[0374] For example, in d V = 0.5λ, the radar device 10 can estimate the direction of arrival while suppressing the occurrence of grating lobes over the entire wide range of ±90° in the vertical direction. V When estimating the direction of arrival, using a 10-element equally spaced linear array as the element spacing, the array aperture length is 9d. V =4.5λ, so the beam width BW is about 9°, and the radar device 10 can achieve a high angular resolution of BW=10° or less. V For an 11-element linear array, when estimating the direction of arrival, the array aperture length is 12d. V =6λ, the beam width BW is about 7°, and a high angular resolution of BW=10° or less can be achieved.

[0375] (Variation 2 of Implementation Method 2)

[0376] In the above embodiment, the case where the array elements are divided into sub-arrays in the vertical direction is described, but the array elements may also be divided into sub-arrays in the horizontal direction. Figure 16 The radar device 10 can narrow the radar detection range in the horizontal direction, and the minimum element spacing in the horizontal direction is 2d H In the case of Figure 17A An example of this. Figure 16 In the embodiment of the present invention, by stacking two array elements in the horizontal direction and forming a sub-array, the horizontal directivity can be narrowed, the radiation in unnecessary directions can be reduced, and the array element gain can be improved.

[0377] However, similar to the vertical direction described above, stacking the array elements of the subarray antenna in the horizontal direction increases the size of the array elements to approximately one wavelength, thus creating limitations on the array antenna's configuration. Specifically, in the subarray antenna configuration, radar apparatus 10 is limited to a minimum element spacing in the horizontal direction of the array configuration exceeding a predetermined value.

[0378] Therefore, in this modification, it is described that even when a subarray antenna is used in the horizontal direction, arrival direction estimation can be performed while suppressing the occurrence of grating lobes over an entire wide range, thereby achieving a high-resolution antenna configuration in the vertical / horizontal directions.

[0379] Similar to the first embodiment, Nt transmitting antennas 106 and Na receiving antennas 202 are arranged at unequal intervals in the horizontal direction and the vertical direction.

[0380] In addition, in the horizontal direction (the direction of the sub-array antenna), N TV The element spacing of the transmitting antenna 106 and N RV The difference in element spacing between the receiving antennas 202 is the basic unit d of the element spacing in the horizontal direction. H The transmitting antenna 106 and the receiving antenna 202 of this embodiment are configured by combining one or more of the above. H It is set to be lower than 1λ (for example, 0.5λ). That is, the transmitting antenna 106 and the receiving antenna 202 are arranged so as to include at least one arrangement satisfying the following equation (hereinafter referred to as condition A-3).

[0381] <Condition A-3>

[0382] |(horizontal element spacing of the transmitting antenna 106)-(horizontal element spacing of the receiving antenna 202)|=d H ≒0.5λ<1λ

[0383] Furthermore, in the arrangement of transmitting antenna 106 and receiving antenna 202 in this modification, it is assumed that the constraint conditions A-2, B-1, and B-2 other than A-1 among the constraint conditions described in the first embodiment are satisfied.

[0384] In this way, in the horizontal sub-array antenna structure, the aperture length of the virtual receiving array in the vertical and horizontal directions can also be maximized. By using the virtual receiving array, the angular resolution can be improved with a smaller number of antennas, and the radar device 10 can be miniaturized and low-cost.

[0385] (Variation 3 of Implementation Method 2)

[0386] In this modification, a case where array elements are divided into sub-arrays in both the vertical and horizontal directions will be described. Figure 18 It is able to narrow the radar detection range in both vertical and horizontal directions, and the minimum element spacing in the vertical / horizontal direction is 2d V , 2d H In the case of 2 elements × 2 elements, the sub-array antenna element is suitable for Figure 17A An example of this. Figure 18 In the present invention, by stacking array elements in the vertical and horizontal directions and forming sub-arrays, the directivity in the vertical and horizontal directions can be narrowed, the radiation in unnecessary directions can be reduced, and the gain of the array elements can be improved.

[0387] However, radar apparatus 10 stacks array elements in the vertical and horizontal directions, increasing the size of the array elements to more than one wavelength. This creates limitations on the array antenna configuration. Specifically, radar apparatus 10 is subject to the requirement that the minimum element spacing in the vertical and horizontal directions of the array configuration must be greater than a specified value.

[0388] Therefore, in this change, it is described that even when subarray antennas are used in both the vertical and horizontal directions, arrival direction estimation can be performed while suppressing the occurrence of grating lobes over an entire wide range, thereby achieving a high-resolution antenna configuration in the vertical / horizontal directions.

[0389] Similar to the first embodiment, Nt transmitting antennas 106 and Na receiving antennas 202 are arranged at unequal intervals in the horizontal direction and the vertical direction.

[0390] So that in the vertical direction, N TV The element spacing of the transmitting antenna 106 and N RV The difference in element spacing between the receiving antennas 202 at the root is the basic unit d of the element spacing in the vertical direction. V The transmitting antenna 106 and the receiving antenna 202 of this embodiment are configured by including at least one combination of . V It is set to be lower than 1λ (for example, 0.5λ). That is, the transmitting antenna 106 and the receiving antenna 202 are arranged so as to include at least one arrangement satisfying the following equation (Condition B-3) in the vertical direction.

[0391] <Condition B-3>

[0392] |(element spacing in the vertical direction of the transmitting antenna 106)-(element spacing in the vertical direction of the receiving antenna 202)|=d V ≒0.5λ<1λ

[0393] In addition, so that in the horizontal direction, N TV The element spacing of the transmitting antenna 106 and N RV The difference in element spacing between the receiving antennas 202 is the basic unit d of the element spacing in the horizontal direction. H The transmitting antenna 106 and the receiving antenna 202 of this embodiment are configured by including at least one combination of. In addition, the basic unit d of the element spacing in the horizontal direction is H It is set to be lower than 1λ (for example, 0.5λ). That is, the transmitting antenna 106 and the receiving antenna 202 are arranged so as to include at least one arrangement satisfying the following formula (Condition A-3) in the horizontal direction.

[0394] <Condition A-3>

[0395] |(horizontal element spacing of the transmitting antenna 106)-(horizontal element spacing of the receiving antenna 202)|=d H ≒0.5λ<1λ

[0396] Furthermore, in the arrangement of transmitting antenna 106 and receiving antenna 202 in this modification, it is assumed that the constraint conditions A-2 and B-2 in addition to A-1 and B-1 among the constraint conditions described in the first embodiment are satisfied.

[0397] As an example, Figure 17A : shows an example of the configuration of the transmitting antenna 106 and the receiving antenna 202. Figure 17B Indicates passing Figure 17A The antenna configuration shown results in the configuration of the virtual receive array.

[0398] Here, it is assumed that the number of transmitting antennas 106 is Nt = 4 and the number of receiving antennas 202 is Na = 4. Furthermore, the four transmitting antennas 106 are denoted by Tx#1 to Tx#4, and the four receiving antennas 202 are denoted by Rx#1 to Rx#4.

[0399] exist Figure 17A In the figure, the transmitting antennas Tx#1 to Tx#4 are based on the upper end of the three antennas configured in the vertical direction, that is, the transmitting antenna Tx#1, and one more antenna is configured in the horizontal right direction (rotate the L shape +90°). The receiving antennas Rx#1 to Rx#4 are based on the center of the three antennas configured in the horizontal direction, that is, the receiving antenna Rx#2, and one more antenna is configured in the vertical upward direction.

[0400] Figure 17B Indicated by Figure 17A The antenna configuration shown constitutes the configuration of a virtual receiving array. Figure 17B The configuration of the virtual receiving array shown has the following characteristics.

[0401] (1) Horizontal direction

[0402] exist Figure 17A In the horizontal direction, the components are spaced 5d apart. H The two transmitting antennas Tx#1 and Tx#4 are configured with an element spacing of 4d in the horizontal direction. H , 2d H The horizontal position relationship between the three configured receiving antennas Rx#1, Rx#2, and Rx#3, Figure 17B The virtual receiving array shown includes a horizontal direction according to the element spacing 4d H d H d H, 3d H , 2d H The 6-element horizontal virtual linear array antenna HLA (with Figure 17B VA#1, VA#5, VA#4, VA#9, VA#8, VA#12) are surrounded by dotted lines.

[0403] Taking the horizontal position of VA#1 as a reference, the horizontal coordinates (x1, x2, x3, x4, x5, x6) of each of the six elements (VA#1, VA#5, VA#4, VA#9, VA#8, VA#12) constituting the horizontal virtual linear array antenna HLA are (x1, x2, x3, x4, x5, x6) = [0, 4d H , 5d H , 6d H , 9d H , 11d H ].

[0404] Here, the element spacing between any two different elements included in the horizontal virtual linear array antenna HLA is |x A -x B |(where A and B are integers from 1 to 6, A≠B) is {1, 2, 3, 4, 5, 6, 7, 9, 11}×d H That is, by using the six-element horizontal virtual linear array antenna HLA, {1, 2, 3, 4, 5, 6, 7}×d H The combination of element spacing can be virtually regarded as having the element spacing in the horizontal direction as the basic unit d H The radar device 10 has an 8-element equally spaced linear array, and is capable of estimating the direction of arrival with high angular resolution.

[0405] Furthermore, by using {1, 2, 3, 4, 5, 6, 7, 9, 11}×d H The combination of element spacing is virtually regarded as having a basic unit d in the horizontal direction. H 2 times the element spacing 2d H The radar device 10 can also estimate the direction of arrival even if the linear array has 10 elements. In this case, the radar device 10 is considered to have a linear array of 10 elements, and the basic unit d is used. H Compared with an 8-element equally spaced linear array with a smaller element spacing, the spatial side lobes increase slightly, but the aperture length is further expanded, so the angular resolution can be improved.

[0406] For example, in d H= 0.5λ, the radar device 10 can estimate the direction of arrival while suppressing the occurrence of grating lobes over the entire wide range of ±90° in the horizontal direction. H When the arrival direction is estimated using an 8-element equally spaced linear array with an element spacing of 1, the array aperture length is 7d. H =3.5λ, so in the radar device 10, the beam width BW is about 11°. In addition, it is assumed that the element interval 2d is included in the virtual H In the case of a 10-element linear array and arrival direction estimation, since the array aperture length is 11d V =5.5λ, the beam width BW is approximately 7°, and the radar device 10 can achieve a high angular resolution of BW=10° or less.

[0407] In this way, in d H =0.5λ, in Figure 17A In the radar device 10, the horizontal element spacing 5d between Tx#1 and Tx#4 is satisfied. V )-(Horizontal element spacing between Rx#1 and Rx#2 is 4d V )|=d H ≒0.5λ<1λ condition A-3. Therefore, Figure 17B In the horizontal arrangement of the virtual receiving array, the element spacing of 1λ or less (≒0.5λ) contains one or more ( Figure 17B VA#5 and VA#4, and VA#9). Virtually consider the basic unit d in the horizontal direction as V As a linear array of multiple elements with a spacing of 1 / 4, Figure 17A The radar device 10 is capable of estimating the direction of arrival with high angular resolution.

[0408] (2) Vertical direction

[0409] exist Figure 17A In the vertical direction, the element spacing is 2d V 、4d V The three transmitting antennas Tx#1, Tx#2, and Tx#3 are configured and spaced 5d apart in the vertical direction. V The vertical position relationship between the two configured receiving antennas Rx#2 and Rx#4, Figure 17B The virtual receiving array shown includes a vertical direction according to the element spacing 4d V d V d V , 3d V , 2d VA 6-element vertical virtual linear array antenna VLA (with Figure 17B VA#7, VA#6, VA#15, VA#5, VA#14, VA#13) are enclosed by the dotted lines shown.

[0410] Taking the vertical position of VA#7 as a reference, the vertical coordinates (y1, y2, y3, y4, y5, y6) of the six elements (VA#7, VA#6, VA#15, VA#5, VA#14, VA#13) constituting the vertical virtual linear array antenna VLA are (y1, y2, y3, y4, y5, y6) = [0, 4d V , 5d V , 6d V , 9d V , 11d V ].

[0411] Here, the element spacing between any two different elements included in the vertical virtual linear array antenna VLA is |y A -y B |(where A and B are integers from 1 to 6, A≠B) is {1, 2, 3, 4, 5, 6, 7, 9, 11}×d V That is, by using the 6-element vertical virtual linear array antenna VLA, {1, 2, 3, 4, 5, 6, 7}×d V The combination of element spacing can be virtually regarded as having the element spacing in the vertical direction as the basic unit d V The radar device 10 has an 8-element equally spaced linear array, and is capable of estimating the direction of arrival with high angular resolution.

[0412] Furthermore, by using {1, 2, 3, 4, 5, 6, 7, 9, 11}×d V The combination of element spacing is virtually considered to contain the basic unit d in the vertical direction V 2 times the element spacing 2d V The radar device 10 can also estimate the direction of arrival even if the linear array has 10 elements. In this case, the radar device 10 is considered to have a linear array of 10 elements, and the basic unit d is used. V Compared with an 8-element equally spaced linear array with a smaller element spacing, the spatial side lobes increase slightly, but the aperture length is further expanded, which can improve the angular resolution.

[0413] For example, in d V = 0.5λ, the radar device 10 can estimate the direction of arrival while suppressing the occurrence of grating lobes over the entire wide range of ±90° in the vertical direction. VWhen the arrival direction is estimated using an 8-element equally spaced linear array with an element spacing of 1, the array aperture length is 7d. V =3.5λ, so in the radar device 10, the beam width BW is about 11°. In addition, it is assumed that the element interval 2d is included in the virtual V In the case of a 10-element linear array and arrival direction estimation, since the array aperture length is 11d V =5.5λ, so the beam width BW is about 7°, and the radar device can achieve a high angular resolution of BW=10° or less.

[0414] In this way, in d V =0.5λ, in Figure 17A In the radar device 10, the vertical element spacing of Tx#2 and Tx#3 is 4d. V )-(The vertical element spacing of Rx#2 and Rx#4 is 5d V )|=d V ≒0.5λ<1λ condition B-3. Therefore, Figure 17B In the vertical arrangement of the virtual receiving array, the element spacing of 1λ or less (≒0.5λ) contains one or more ( Figure 17B The element spacings of VA#6 and VA#15, and the element spacings of VA#15 and VA#5 shown in FIG. 1 can be virtually considered as having a basic unit d in the vertical direction. V As a linear array of multiple elements with element spacing, the Figure 17A The radar device 10 is capable of estimating the direction of arrival with high angular resolution.

[0415] Therefore, even if both the vertical and horizontal directions are sub-array antenna structures, the aperture length of the virtual receiving array in the vertical and horizontal directions can be maximized. By using a virtual receiving array, the radar device 10 can improve the angular resolution with a smaller number of antennas, thereby achieving miniaturization and low cost of the radar device 10.

[0416] (Variation 4 of Implementation Method 2)

[0417] As long as the vertical dimension of the array elements stacked and arranged in sub-arrays in the vertical and horizontal directions is less than 2d V , and the horizontal size is less than 2d H , the antenna configuration in the MIMO radar described in Change 3 can be applied.

[0418] On the other hand, the vertical / horizontal size of the array elements stacked and sub-arrayed in the vertical / horizontal direction is greater than 2d V , 2d H, for example, Figure 19 As shown, when using an antenna element in which three antenna elements are stacked and arranged in a sub-array in the vertical and horizontal directions, the radar device 10 can use the antenna arrangement described below. The following describes the case where the vertical size of the array element stacked and arranged in a sub-array in the vertical direction is less than 3d. V The horizontal size of the array elements stacked and sub-arrayed in the horizontal direction is less than 3d H , for examples of applicable antenna configurations.

[0419] Figure 20A : shows an example of the configuration of the transmitting antenna 106 and the receiving antenna 202. Figure 20B Indicates passing Figure 20A The antenna configuration shown results in the configuration of the virtual receive array.

[0420] Here, it is assumed that the number of transmitting antennas 106 is Nt = 4 and the number of receiving antennas 202 is Na = 4. Furthermore, the four transmitting antennas 106 are denoted by Tx#1 to Tx#4, and the four receiving antennas 202 are denoted by Rx#1 to Rx#4.

[0421] exist Figure 20A In the figure, transmitting antennas Tx#1 to Tx#4 are arranged in a pattern in which one antenna is further arranged in the horizontal right direction at a spacing narrower than the vertical element spacing, using transmitting antenna Tx#1, which is the upper end of the three antennas arranged in the vertical direction, as the base point (rotating the L shape by -180°). Receiving antennas Rx#1 to Rx#4 are arranged in a pattern in which one antenna is further arranged in the vertical upper direction at a spacing narrower than the horizontal element spacing, using receiving antenna Rx#3, which is the right end of the three antennas arranged in the horizontal direction, as the base point (rotating the L shape by -90°).

[0422] Depend on Figure 20A The antenna configuration shown is composed of Figure 20B The configuration of the virtual receiving array shown has the following characteristics.

[0423] (1) Horizontal direction

[0424] exist Figure 20A In the horizontal direction, the element spacing is 3d H The two transmitting antennas Tx#1 and Tx#4 are configured with an element spacing of 4d in the horizontal direction. H , 5d H The horizontal position relationship between the three configured receiving antennas Rx#1, Rx#2, and Rx#3 satisfies condition A-3. Figure 20B The virtual receiving array shown includes elements spaced 3d apart in the horizontal direction. H d H, 3d H , 2d H , 3d H The 6-element horizontal virtual linear array antenna HLA (with Figure 20B VA#1, VA#4, VA#5, VA#8, VA#9, VA#12) are surrounded by dotted lines.

[0425] Taking the horizontal position of VA#1 as a reference, the horizontal coordinates (x1, x2, x3, x4, x5, x6) of each of the six elements (VA#1, VA#4, VA#5, VA#8, VA#9, VA#12) constituting the horizontal virtual linear array antenna HLA are (x1, x2, x3, x4, x5, x6) = [0, 3d H , 4d H , 7d H , 9d H , 12d H ].

[0426] Here, the element spacing between any two different elements included in the horizontal virtual linear array antenna HLA is |x A -x B |(where A and B are integers from 1 to 6, A≠B) is {1, 2, 3, 4, 5, 6, 7, 8, 9, 12}×d H That is, by using the six-element horizontal virtual linear array antenna HLA, {1, 2, 3, 4, 5, 6, 7, 8, 9}×d H The combination of element spacing can be virtually regarded as having the element spacing in the horizontal direction as the basic unit d H With the 10-element equally spaced linear array, the radar device 10 is capable of estimating the direction of arrival with high angular resolution.

[0427] Furthermore, by using {1, 2, 3, 4, 5, 6, 7, 8, 9, 12}×d H The combination of element spacing is virtually regarded as having a basic unit d in the horizontal direction. H 3 times the element spacing 3d H The radar device 10 can also estimate the direction of arrival by using a linear array of 11 elements. In this case, the radar device 10 having a linear array of 11 elements is considered to be different from the basic unit d H Compared with a 10-element equally spaced linear array with a fixed element spacing, the spatial side lobes increase slightly, but the aperture length is further expanded, so the angular resolution can be improved.

[0428] For example, in d H= 0.5λ, the radar device 10 can estimate the direction of arrival while suppressing the occurrence of grating lobes over the entire wide range of ±90° in the horizontal direction. H When the arrival direction is estimated using a 10-element equally spaced linear array with an element spacing of 9d, the array aperture length is 9d. H =4.5λ, so the beam width BW is about 9°, and the radar device 10 can achieve a high angular resolution of BW=10° or less. H In the case of an 11-element linear array and arrival direction estimation, since the array aperture length is 12d V =6λ, the beam width BW is approximately 7°, and the radar device 10 can achieve a high angular resolution of BW=10° or less.

[0429] (2) Vertical direction

[0430] exist Figure 20A In the vertical direction, the element spacing is 4d V , 5d V The three transmitting antennas Tx#1, Tx#2, and Tx#3 are configured and spaced 3d apart in the vertical direction. V The vertical position relationship between the two configured receiving antennas Rx#3 and Rx#4 satisfies condition B-3. Figure 20B The virtual receiving array shown includes a vertical direction according to the element spacing 3d V , 2d V , 3d V d V , 3d V A 6-element vertical virtual linear array antenna VLA (with Figure 20B VA#11, VA#15, VA#10, VA#14, VA#9, VA#13) are surrounded by dotted lines.

[0431] Taking the vertical position of VA#11 as a reference, the vertical coordinates (y1, y2, y3, y4, y5, y6) of each of the six elements (VA#11, VA#15, VA#10, VA#14, VA#9, VA#13) constituting the vertical virtual linear array antenna VLA are (y1, y2, y3, y4, y5, y6) = [0, 3d V , 5d V , 8d V , 9d V , 12d V ].

[0432] Here, the element spacing between any two different elements included in the vertical virtual linear array antenna VLA is |y A -y B |(where A and B are integers from 1 to 6, A≠B) is {1, 2, 3, 4, 5, 6, 7, 8, 9, 12}×d V That is, by using the 6-element vertical virtual linear array antenna VLA, {1, 2, 3, 4, 5, 6, 7, 8, 9}×d V The combination of element spacing can be virtually regarded as having the element spacing in the vertical direction as the basic unit d V The radar device 10 has a 10-element equally spaced linear array, and is capable of estimating the direction of arrival with high angular resolution.

[0433] Furthermore, by using {1, 2, 3, 4, 5, 6, 7, 8, 9, 12}×d V The combination of element spacing is virtually considered to contain the basic unit d in the vertical direction V 3 times the element spacing 3d V The radar device 10 can also estimate the direction of arrival by using a linear array of 11 elements. In this case, the radar device 10 having a linear array of 11 elements is considered to be different from the basic unit d V Compared with a 10-element equally spaced linear array with a fixed element spacing, the spatial side lobes increase slightly, but the aperture length is further expanded, so the angular resolution can be improved.

[0434] For example, in d V = 0.5λ, the radar device 10 can estimate the direction of arrival while suppressing the occurrence of grating lobes over the entire wide range of ±90° in the vertical direction. V When the arrival direction is estimated using a 10-element equally spaced linear array with an element spacing of 9d, the array aperture length is 9d. V =4.5λ, so the beam width BW is about 9°, and the radar device 10 can achieve a high angular resolution of BW=10° or less. V In the case of an 11-element linear array and arrival direction estimation, since the array aperture length is 12d V =6λ, the beam width BW is approximately 7°, and the radar device 10 can achieve a high angular resolution of BW=10° or less.

[0435] (Variation 5 of Implementation Method 2)

[0436] In the second embodiment, when a high resolution of about 10° is not required as the angular resolution in either the horizontal or vertical direction, the number of elements of the transmitting antenna 106 or the number of elements of the receiving antenna 202 may be set to three.

[0437] In the following, as an example, a case where a high resolution is not required as the angular resolution in the vertical direction, the number of elements of the transmitting antenna 106 is set to 3 and the number of elements of the receiving antenna 202 is set to 4 is described.

[0438] Furthermore, a MIMO array configuration is used in which the array elements are stacked in the vertical and horizontal directions to have a size of one wavelength (1λ) or more in both the vertical and horizontal directions.

[0439] Figure 21A : shows an example of the configuration of the transmitting antenna 106 and the receiving antenna 202. Figure 21B Indicated by Figure 21A The antenna configuration shown results in the configuration of the virtual receive array.

[0440] exist Figure 21A In FIG, the three transmitting antennas 106 are represented by Tx#1 to Tx#3, and the four receiving antennas 202 are represented by Rx#1 to Rx#4. Figure 21A In the figure, transmitting antennas Tx#1 to Tx#3 are arranged in a pattern in which one antenna is further arranged in the horizontal right direction at a distance wider than the vertical element spacing, i.e., transmitting antenna Tx#1, which is the upper end of the two antennas arranged in the vertical direction, is used as the base point (rotating the L shape by +90°). Receiving antennas Rx#1 to Rx#4 are arranged in a pattern in which one antenna is further arranged in the vertical upward direction at a distance narrower than the horizontal element spacing, i.e., receiving antenna Rx#2, which is the center of the three antennas arranged in the horizontal direction, is used as the base point (rotating the T shape by 180°).

[0441] Furthermore, in the arrangement of transmitting antenna 106 and receiving antenna 202 in this modification, it is assumed that the constraint conditions A-2 and B-2 in addition to A-1 and B-1 among the constraint conditions described in the first embodiment are satisfied.

[0442] Depend on Figure 21A The antenna configuration shown is composed of Figure 21B The configuration of the virtual receiving array shown has the following characteristics.

[0443] (1) Horizontal direction

[0444] exist Figure 21A In the horizontal direction, the components are spaced 5d apart. H The two transmitting antennas Tx#1 and Tx#3 are configured with a 4d spacing between the elements in the horizontal direction.H , 2d H The horizontal position relationship between the three configured receiving antennas Rx#1, Rx#2, and Rx#3 satisfies condition A-3. Figure 21B The virtual receiving array shown includes a horizontal direction according to the element spacing 4d H d H d H , 3d H , 2d H The 6-element horizontal virtual linear array antenna HLA (with Figure 21B VA#1, VA#4, VA#3, VA#7, VA#6, VA#9) are surrounded by dotted lines.

[0445] With the horizontal position of VA#1 as a reference, the horizontal coordinates (x1, x2, x3, x4, x5, x6) of each of the six elements (VA#1, VA#4, VA#3, VA#7, VA#6, VA#9) constituting the horizontal virtual linear array antenna HLA are (x1, x2, x3, x4, x5, x6) = [0, 4d H , 5d H , 6d H , 9d H , 11d H ].

[0446] Here, the element spacing between any two different elements included in the horizontal virtual linear array antenna HLA is |x A -x B |(where A and B are integers from 1 to 6, A≠B) is {1, 2, 3, 4, 5, 6, 7, 9, 11}×d H That is, by using the six-element horizontal virtual linear array antenna HLA, {1, 2, 3, 4, 5, 6, 7}×d H The combination of element spacing can be virtually regarded as having the element spacing in the horizontal direction as the basic unit d H The radar device 10 has an 8-element equally spaced linear array, and is capable of estimating the direction of arrival with high angular resolution.

[0447] Furthermore, by using {1, 2, 3, 4, 5, 6, 7, 9, 11}×d H The combination of element spacing is virtually regarded as having a basic unit d in the horizontal direction. H 2 times the element spacing 2d H The radar device 10 can also estimate the direction of arrival even if the linear array has 10 elements. In this case, the radar device 10 is considered to have a linear array of 10 elements, and the basic unit d is used. HCompared with an 8-element equally spaced linear array with a smaller element spacing, the spatial side lobes increase slightly, but the aperture length is further expanded, so the angular resolution can be improved.

[0448] For example, in d H = 0.5λ, the radar device 10 can estimate the direction of arrival while suppressing the occurrence of grating lobes over the entire wide range of ±90° in the horizontal direction. H When the arrival direction is estimated using an 8-element equally spaced linear array with an element spacing of 1, the array aperture length is 7d. H =3.5λ, so in the radar device 10, the beam width BW is about 11°. In addition, it is assumed that there is a virtual element spacing of 2d. H In the case of a 10-element linear array and arrival direction estimation, since the array aperture length is 11d H =5.5λ, the beam width BW is about 7°, and a high angular resolution of BW=10° or less can be achieved.

[0449] (2) Vertical direction

[0450] exist Figure 21A In the vertical direction, the element spacing is 2d V The two transmitting antennas Tx#1 and Tx#2 are configured in the vertical direction according to the element spacing of 3d V The vertical position relationship between the two configured receiving antennas Rx#2 and Rx#4 satisfies condition B-3. Figure 21B The virtual receiving array shown includes a vertical direction according to the element spacing 2d V d V , 2d V A 4-element vertical virtual linear array antenna VLA (with Figure 21B VA#5, VA#4, VA#11, VA#10) are surrounded by dotted lines.

[0451] Taking the vertical position of VA#5 as a reference, the vertical coordinates (y1, y2, y3, y4) of each of the four elements (VA#5, VA#4, VA#11, VA#10) constituting the vertical virtual linear array antenna VLA are (y1, y2, y3, y4) = [0, 2d V , 3d V , 5d V ].

[0452] Here, the element spacing between any two different elements included in the vertical virtual linear array antenna VLA is |y A -y B|(where A and B are integers from 1 to 4, A≠B) is {1, 2, 3, 5}×d V That is, by using the vertical virtual linear array antenna VLA of 4 elements, {1, 2, 3}×d V The combination of element spacing can be virtually regarded as having the basic unit d in the vertical direction. V As a linear array of four elements with equal spacing between elements, the radar device 10 can estimate the direction of arrival with high angular resolution.

[0453] Furthermore, by using {1, 2, 3, 5}×d V The combination of element spacing is virtually regarded as having a basic unit d in the vertical direction. V 2 times the element spacing 2d V The radar device 10 can also estimate the direction of arrival even if the linear array has 5 elements. In this case, the radar device 10 is considered to have a linear array of 5 elements, and the basic unit d is used. V Compared with a 4-element equally spaced linear array with a smaller element spacing, the spatial side lobes increase slightly, but the aperture length is further expanded, so the angular resolution can be improved.

[0454] For example, in d V = 0.5λ, the radar device 10 can estimate the direction of arrival while suppressing the occurrence of grating lobes over the entire wide range of ±90° in the vertical direction. V In the case of a 5-element linear array and arrival direction estimation, since the array aperture length is 5d V =2.5λ, so in the radar device 10, the beam width BW is approximately 16°.

[0455] (Variation 6 of Implementation Method 2)

[0456] In Embodiment 2, in a radar device 10 that uses five or more elements as the number of elements of the receiving antenna 202, the number of elements of the transmitting antenna 106 may be set to three. Alternatively, in a radar device 10 that uses five or more elements as the number of elements of the transmitting antenna 106, the number of elements of the receiving antenna 202 may be set to three.

[0457] Hereinafter, as an example, a radar device 10 in which the number of elements of the transmitting antenna 106 is set to three and the number of elements of the receiving antenna 202 is set to five will be described.

[0458] Furthermore, the description will be made using a MIMO array configuration in which array elements are stacked in the vertical and horizontal directions, and the size of the array elements is approximately one wavelength (1λ) in both the vertical and horizontal directions.

[0459] Figure 22A : shows an example of the configuration of the transmitting antenna 106 and the receiving antenna 202. Figure 22B Indicates passing Figure 22A The antenna configuration shown results in the configuration of the virtual receive array.

[0460] exist Figure 22A In FIG, three transmitting antennas 106 are represented by Tx#1 to Tx#3, and five receiving antennas 202 are represented by Rx#1 to Rx#5. Figure 22A In the figure, the transmitting antennas Tx#1 to Tx#3 are arranged in a pattern where one antenna is further arranged in the horizontal right direction (rotated +90° in the L shape) with the transmitting antenna Tx#1 being the top of the three antennas arranged in the vertical direction as the base point. The receiving antennas Rx#1 to Rx#5 are arranged in a pattern where one antenna is further arranged in the vertical up and down direction (cross shape) with the receiving antenna Rx#3 being the center of the three antennas arranged in the horizontal direction as the base point. The arrangement of the receiving antennas Rx#1 to Rx#5 is not limited to a cross arrangement and can be an L-shaped arrangement or a T-shaped arrangement (for example, see the following). Figures 24A to 24F ).

[0461] Furthermore, it is assumed that the arrangement of transmitting antenna 106 and receiving antenna 202 in this modification satisfies the conditions A-2 and B-2 in addition to A-1 and B-1 among the constraint conditions described in the first embodiment.

[0462] Depend on Figure 22A The antenna configuration shown is composed of Figure 22B The configuration of the virtual receiving array shown has the following characteristics.

[0463] (1) Horizontal direction

[0464] exist Figure 22A In the horizontal direction, the components are spaced 5d apart. H The two transmitting antennas Tx#1 and Tx#3 are configured with a 4d spacing between the elements in the horizontal direction. H , 2d H The horizontal position relationship between the three configured receiving antennas Rx#2, Rx#3, and Rx#4 meets condition A-3. Figure 22B The virtual receiving array shown includes a horizontal direction according to the element spacing 4d H d H d H , 3d H , 2d H The 6-element horizontal virtual linear array antenna HLA (with Figure 22B VA#4, VA#7, VA#6, VA#10, VA#9, VA#12) are surrounded by dotted lines.

[0465] Taking the horizontal position of VA#4 as a reference, the horizontal coordinates (x1, x2, x3, x4, x5, x6) of each of the six elements (VA#4, VA#7, VA#6, VA#10, VA#9, VA#12) constituting the horizontal virtual linear array antenna HLA are (x1, x2, x3, x4, x5, x6) = [0, 4d H , 5d H , 6d H , 9d H , 11d H ].

[0466] Here, the element spacing between any two different elements included in the horizontal virtual linear array antenna HLA is |x A -x B |(where A and B are integers from 1 to 6, A≠B) is {1, 2, 3, 4, 5, 6, 7, 9, 11}×d H That is, the radar device 10 uses {1, 2, 3, 4, 5, 6, 7}×d among the six-element horizontal virtual linear array antenna HLA. H The combination of element spacing can be virtually regarded as having the basic unit d in the horizontal direction. H An 8-element equally spaced linear array with a high element spacing enables estimation of the direction of arrival with high angular resolution.

[0467] Furthermore, the radar device 10 uses {1, 2, 3, 4, 5, 6, 7, 9, 11}×d H The combination of element spacing is virtually regarded as having a basic unit d in the horizontal direction. H 2 times the element spacing 2d H In this case, the radar device 10 having a linear array of 10 elements can also be used to estimate the direction of arrival. H Compared with an 8-element equally spaced linear array with a smaller element spacing, the spatial side lobes increase slightly, but the aperture length is further expanded, so the angular resolution can be improved.

[0468] For example, in d H = 0.5λ, the radar device 10 can estimate the direction of arrival while suppressing the occurrence of grating lobes over the entire wide range of ±90° in the horizontal direction. H When the arrival direction is estimated using an 8-element equally spaced linear array with an element spacing of 1, the array aperture length is 7d. H=3.5λ, so the beam width BW is about 11°. In addition, the radar device 10 is virtually considered to include an element interval of 2d. H In the case of a 10-element linear array and arrival direction estimation, since the array aperture length is 11d V =5.5λ, the beam width BW is about 7°, and a high angular resolution of BW=10° or less can be achieved.

[0469] (2) Vertical direction

[0470] exist Figure 22A In the vertical direction, the components are spaced 5d apart. V The two transmitting antennas Tx#1 and Tx#2 are configured in the vertical direction according to the element spacing of 2d V 、4d V The vertical position relationship between the three configured receiving antennas Rx#1, Rx#3, and Rx#5 satisfies condition B-3. Figure 22B The virtual receiving array shown includes a vertical direction according to the element spacing 2d V , 3d V d V d V 、4d V A 6-element vertical virtual linear array antenna VLA (with Figure 22B VA#2, VA#8, VA#1, VA#14, VA#7, VA#13) are surrounded by dotted lines.

[0471] With the vertical position of VA#2 as a reference, the vertical coordinates (y1, y2, y3, y4, y5, y6) of each of the six elements (VA#2, VA#8, VA#1, VA#14, VA#7, VA#13) constituting the vertical virtual linear array antenna VLA are (y1, y2, y3, y4, y5, y6) = [0, 2d V , 5d V , 6d V , 7d V , 11d V ].

[0472] Here, the element spacing between any two different elements included in the vertical virtual linear array antenna VLA is |y A -y B |(where A and B are integers from 1 to 6, A≠B) is {1, 2, 3, 4, 5, 6, 7, 9, 11}×d V That is, the radar device 10 uses {1, 2, 3, 4, 5, 6, 7}×d among the 6-element vertical virtual linear array antenna VLA. VThe combination of element spacing can be virtually regarded as having the element spacing in the vertical direction as the basic unit d V The 8-element equally spaced linear array is capable of high angular resolution direction of arrival estimation.

[0473] Furthermore, the radar device 10 uses {1, 2, 3, 4, 5, 6, 7, 9, 11}×d V The combination of element spacing is virtually regarded as including the element spacing in the vertical direction as the basic unit d V and 2 times the basic unit d V The element spacing is 2d V In this case, the radar device 10 having a linear array of 10 elements can also be used to estimate the direction of arrival. V Compared with an 8-element equally spaced linear array with a smaller element spacing, the spatial side lobes increase slightly, but the aperture length is further expanded, so the main beam is sharp, which can improve the angular resolution.

[0474] For example, d V = 0.5λ, the radar device 10 can estimate the direction of arrival while suppressing the occurrence of grating lobes over the entire wide range of ±90° in the vertical direction. V When estimating the direction of arrival using an 8-element equally spaced linear array as the element spacing, the array aperture length is 7d. V =3.5λ, so the beam width BW is about 11°. In addition, it is assumed that the element spacing is 2d. V For a 10-element linear array, when estimating the direction of arrival, the array aperture length is 11d. V =5.5λ, the beam width BW is approximately 7°, and the radar device 10 can achieve a high angular resolution of BW=10° or less.

[0475] Hereinabove, an embodiment of one aspect of the present invention has been described.

[0476] Furthermore, the above-described embodiments and the operations of the various modifications may be appropriately combined for implementation.

[0477] [Other embodiments]

[0478] (1) The antenna arrangement of the radar device 10 in which the transmitting antenna 106 is configured as 4 elements and the receiving antenna 202 is configured as 4 elements is not limited to Figure 7A 、 Figure 9A 、 Figure 13A 、 Figures 15A to 20A Antenna configuration shown.

[0479] For example, a combination of the configurations of the transmit antenna 106 and the receive antenna 202 can be configured in an L-shape or a T-shape. This, similar to the above-described embodiment, maximizes the aperture area formed by the vertical and horizontal directions of the virtual receive array. Furthermore, the configurations of the transmit antenna 106 and the receive antenna 202 can also be configured as a configuration in which the L-shape or T-shape is reversed vertically or horizontally.

[0480] Figures 23A to 23F An example of antenna configuration that achieves an equivalent effect to a four-element transmitting antenna 106 having two elements in the horizontal direction and three elements in the vertical direction is shown. Figures 23A to 23F As shown, it can also be configured in an L-shaped manner ( Figure 23C ), the L-shaped configuration is reversed upside down ( Figure 23A ), rotate the L shape 180 degrees ( Figure 23D ), the configuration of the L-shaped inverted left and right ( Figure 23F ), the configuration of rotating the T-shape by +90° ( Figure 23E ), rotate the T-shape by -90° ( Figure 23B ).

[0481] In addition, the number of elements of the transmitting antenna 106 is not limited to 4 elements. Figures 23A to 23F In the transmitting antenna 106 shown, even if the element spacings α and β of the three elements arranged in a straight line in the vertical direction are swapped, the same effect can be obtained. That is, even if the element spacing αd between element #1 and element #2 is changed to V and the element spacing βd between element #2 and element #3 V The element spacing βd of element #1 and element #2 is swapped V and the element spacing αd between element #2 and element #3 V , the same effect can be achieved.

[0482] Figures 24A to 24F FIG. 2 shows an example of an antenna configuration that achieves an equivalent effect to a receiving antenna 202 having four elements, namely, three elements in the horizontal direction and two elements in the vertical direction. Figures 24A to 24F As shown, it can also be configured in an L-shaped manner ( Figure 24B ), the L-shaped configuration is reversed left and right ( Figure 24C ), the L-shaped configuration is reversed upside down ( Figure 24E ), the configuration of rotating the L shape by 180 degrees ( Figure 24F )、T-shaped configuration( Figure 24D ), the T-shaped configuration is reversed upside down ( Figure 24A ).

[0483] In addition, the number of elements of the receiving antenna 202 is not limited to 4 elements. Figures 24A to 24F In the receiving antenna 202 shown, even if the element spacings α and β of the three elements arranged in a straight line in the horizontal direction are swapped, the same effect can be obtained. That is, even if the element spacing αd between element #1 and element #2 is changed to H and the element spacing βd between element #2 and element #3 H The element spacing βd of element #1 and element #2 is swapped H and the element spacing αd between element #2 and element #3 H , the same effect can be achieved.

[0484] The configuration of the transmitting antenna 106 is set to Figures 23A to 23F One of the configurations, the configuration of the receiving antenna 202 is set to Figures 24A to 24F The radar device 10 of one of the configurations can obtain the same effect as the above embodiment in each. In addition, even if the configuration of the transmitting antenna 106 is set to Figures 24A to 24F The configuration of one of the receiving antennas 202 shown in FIG. Figures 23A to 23F The radar device 10 in which one of the transmitting antennas 106 is arranged as shown can also obtain the same effects as those of the above-described embodiment.

[0485] (2) In the above embodiment, a case of using a coded pulse radar has been described. However, the present invention is also applicable to a radar system using a frequency-modulated pulse wave, such as a chirp pulse radar.

[0486] (3) Figure 3 In the illustrated radar device 10 , the radar transmitting unit 100 and the radar receiving unit 200 may be individually arranged in physically separate locations.

[0487] (4) Although not shown, the radar device 10 includes, for example, a CPU (Central Processing Unit), a storage medium such as a ROM (Read Only Memory) storing a control program, and a working memory such as a RAM (Random Access Memory). In this case, the functions of each of the aforementioned units are implemented by the CPU executing the control program. However, the hardware structure of the radar device 10 is not limited to this example. For example, each functional unit of the radar device 10 may be implemented as an integrated circuit (IC). Each functional unit may be individually integrated into a single chip, or some or all of them may be integrated into a single chip.

[0488] (5) In the above embodiment, the azimuth estimation unit 214 forms a horizontal virtual linear array antenna HLA based on the horizontal element spacing between any two different elements and performs direction estimation processing as the horizontal direction estimation processing. Furthermore, the azimuth estimation unit 214 forms a vertical virtual linear array antenna VLA based on the vertical element spacing between any two different elements and performs direction estimation processing as the vertical direction estimation processing.

[0489] However, the direction estimation process is not limited to the above-mentioned one, and a virtual ground plane array antenna (hereinafter referred to as a virtual plane array antenna) may be configured based on the element spacing in the horizontal and vertical directions to perform two-dimensional direction estimation processing.

[0490] Figure 25 FIG. 1 is a diagram showing another configuration of the direction estimation unit.

[0491] Below, use Figure 25 The operation of the direction estimation unit 250 shown will be described.

[0492] As in the above embodiment, Figure 25 The direction estimation unit 250 shown takes the virtual receiving array correlation vector h(k, fs, w) obtained by processing in each of Na antenna system processing units 201 as input, and includes a direction vector storage unit 251, a correlation vector generation unit 252, and an evaluation function operation unit 253.

[0493] Figure 26 is a diagram showing a three-dimensional coordinate system used in the description of the operation of the direction estimation unit 250. Figure 26 In the example, the target P with the origin O as the reference T The position vector is defined as r PT .

[0494] When the target P T The position vector r PT The projection point onto the XZ plane is set to P T ', the azimuth angle θ is defined as the straight line OP T ' and the angle formed by the Z axis (target P T When the X coordinate is positive, θ>0). The elevation angle φ is defined as the angle between the target P and the target P. T , origin O, and projection point P T 'In the plane, connected to the target P T , origin O, and projection point P T 'The angle of the line (target P TWhen the Y coordinate is positive, φ>0). In the following, a case where the transmitting antenna 106 and the receiving antenna 202 are arranged in the XY plane is described as an example.

[0495] The nth in the virtual receiving array with the origin O as the reference va The position vector of the element is represented by Sn va Among them, n va =1,…,Nt×Na.

[0496] Here, the position vector S1 of the first element in the virtual receiving array is determined based on the positional relationship between the physical position of the first receiving antenna 202-1 and the origin O. With the position vector S1 of the first element in the virtual receiving array as a reference, the position vectors S2, ..., Sn of the other positions are determined while maintaining the relative arrangement of the virtual receiving array determined by the element spacing between the transmitting antenna 106 and the receiving antenna 202 existing in the XY plane. va Furthermore, the origin O may be made to coincide with the physical position of the first receiving antenna 202 - 1 .

[0497] The radar receiving unit 200 receives signals from a target P in the far field. T In the case of a reflected wave, the phase difference d(r) between the received signal in the first element of the virtual receiving array and the received signal in the second element is the same as that in the first element of the virtual receiving array. PT , 2, 1) is expressed as formula (15). Where,<x,y> Is the inner product operator of vector x and vector y.

[0498]

[0499] Furthermore, in equation (16), the position vector of the second element with respect to the position vector of the first element of the virtual receiving array is expressed as an inter-element vector D(2, 1).

[0500] D(2,1)=S2-S1(18)

[0501] Similarly, the radar receiving unit 200 receives signals from a target P existing in the far field. T In the case of reflected waves, the nth virtual receiving array va (r) The received signal reference in the element and the nth va (t) The phase difference d(r PT , N va (t) , n va (r) ) is expressed as formula (17). Where n va(r) =1,…,Nt×Na,n va (t) =1,…,Nt×Na.

[0502]

[0503] In addition, in formula (18), the nth va (r) The position vector of the component is the reference, nth va (t) The position vector of the element is expressed as the element-to-element vector D(n va (t) , n va (r) ).

[0504]

[0505] As shown in equations (17) and (18), the nth va (r) The received signal in the component is the reference, and the nth va (t) The phase difference d(r PT , N va (t) , n va (r) ) depends on the target P that exists in the far field T The direction of the unit vector (r PT / |r PT |), and the inter-element vector D(n va (t) , n va (r) ).

[0506] In addition, when the virtual receiving array exists in the same plane, the inter-element vector D(n va (t) , n va (r) Direction estimation section 250 uses all or part of these inter-element vectors, assuming that elements exist virtually at the positions indicated by the inter-element vectors, to construct a virtual plane array antenna and perform two-dimensional direction estimation processing.

[0507] Furthermore, when the arrangement of virtual elements is repeated, one of the elements may be fixedly selected in advance. Alternatively, the received signals in all or part of the repeated virtual elements may be used to perform an addition and averaging process.

[0508] Below, using Nq The following describes a two-dimensional direction estimation process using a beamforming method when a virtual plane array antenna is configured using a group of inter-element vectors.

[0509] Here, the nqth inter-element vector D(n va(nq) (t) , n va(nq) (r) ). Where nq=1,…,N q .

[0510] The correlation vector generating unit 252 uses the virtual receiving array correlation vector h _after_cal Each element of (k, fs, w) is h1(k, fs, w), ..., h Na×Nr (k, fs, w), generating the virtual plane configuration array antenna correlation vector h shown in equation (19) VA (k, fs, w).

[0511]

[0512] The direction vector storage unit 251 stores the virtual plane configuration array direction vector a represented by equation (20): VA (θu,φv).

[0513]

[0514] In the case where the virtual receiving array exists in the XY plane, the target P T The direction of the unit vector (r PT / |r PT The relationship between |) and the azimuth angle θ and the elevation angle φ is expressed as formula (21). Therefore, the evaluation function calculation unit 253 calculates r using formula (21) for each angle direction θu and φv of the two-dimensional spatial distribution in the vertical and horizontal directions. PT / |r PT |.

[0515]

[0516] The evaluation function calculation unit 253 performs two-dimensional direction estimation processing in the horizontal and vertical directions using the virtual plane configuration array antenna correlation vector and the virtual plane configuration array direction vector.

[0517] The direction estimation process in 2D using the beamforming method uses the virtual plane to configure the array antenna correlation vector h VA (k, fs, w) and virtual surface configuration array direction vector a VA(θu, φv) The two-dimensional direction estimation evaluation function represented by equation (22) is used to calculate the two-dimensional spatial distribution in the vertical and horizontal directions, and the azimuth and elevation directions that are the maximum or maximum values of the two-dimensional spatial distribution are set as the arrival direction estimation values.

[0518] P VA (θ u ,φ v ,k,fs,w)=|a VA (θ u ,φ v ) H h VA (k,fs,w)| 2 (twenty four)

[0519] In addition to the beamforming method, the radar receiving unit 200 uses a virtual plane to configure the array antenna correlation vector h VA (k, fs, w) and virtual surface configuration array direction vector a VA (θu, φv), a high-resolution arrival direction estimation algorithm such as the Capon method or the MUSIC method is applied, which increases the amount of calculation but can further improve the angular resolution.

[0520] Figure 27 Is to use Figure 9A Antenna configuration and Figure 9B The configuration of the virtual receiving array constitutes a diagram of the virtual surface configuration array antenna. Specifically, Figure 27 is based on Figure 9B The virtual receiving array of 16 (=Nt×Na) elements shown in FIG. 1 assumes that the vector D(n va (t) ,1)、D(n va (t) , 2),…,D(n va (t) , 16) represents a virtual plane array antenna with virtual elements in each position. va (t) =1, ..., 16 (=Nt×Na), so if the vector D(n va (t) ,1)、D(n va (t) , 2),…,D(n va (t) , 16) are not repeated, the virtual elements are 256 (= 16 × 16) elements, but Figure 27 In the example, due to the repeated position, it consists of 169 elements. Therefore, using N q= 169 inter-element vector groups constitute a virtual plane array antenna. H =0.6 wavelength, D V =0.68 wavelength.

[0521] here, Figure 28A Is the vector D(n) between elements va (t) , 1) is a diagram of components virtually arranged in the positions shown. In addition, Figure 28B Is the vector D(n) between elements va (t) , 2) is a diagram of components virtually arranged at the positions shown. Here, n va (t) =1, ..., 16 (=Nt×Na). That is, Figure 28A In the Figure 9B The elements are virtually arranged at the positions indicated by the inter-element vectors of elements VA#1, ..., and VA#16, with element VA#1 in FIG. Figure 28B In the Figure 9B The elements are virtually arranged at the positions indicated by the inter-element vectors of elements VA#1, ..., and VA#16, with element VA#2 in FIG.

[0522] In addition, with Figure 28A 、 Figure 28B Similarly, in the inter-element vector D(n va (t) ,3),…,D(n va (t) , 16) each position, the elements are virtually configured as a virtual surface configuration array antenna, Figure 27 In the figure, the vector D(n va (t) ,1)、D(n va (t) , 2),…,D(n va (t) , 16) in each position, all the components are virtually arranged. Here, the virtual components include repeated virtual components, but one of the components is pre-selected and processed.

[0523] By using Figure 27 The virtual plane array antenna shown can virtually increase the number of elements in the radar receiving unit 200, thereby achieving the effect of reducing the grating lobe and sidelobe levels in the two-dimensional spatial distribution calculated in the two-dimensional direction estimation process.

[0524] Figure 29A Is to use Figure 9BThe virtual receiving array shown is a diagram showing the results of a computer simulation of the direction estimation process in 2D under condition A. Figure 29B Is to use Figure 9B The virtual receiving array shown is a diagram showing the results of a computer simulation of the direction estimation process in two dimensions under condition B. Figure 29C Is to use Figure 27 The diagram shows the results of a computer simulation of a two-dimensional direction estimation process under condition A using an array antenna arranged on a virtual plane. Figure 29D Is to use Figure 27 The diagram shows the results of a computer simulation of an array antenna arranged on a virtual plane and a two-dimensional direction estimation process under condition B.

[0525] exist Figure 29A 、 Figure 29C In Condition A, the heat map shows the two-dimensional spatial distribution of beamforming when a target arrives from two different directions (θ, φ) at (15°, 5°) and (15°, -5°) with equal received power levels. The values on the right side of the heat map represent decibel values.

[0526] In addition, Figure 29B 、 Figure 29D In Condition B, the heat map shows the two-dimensional spatial distribution of beamforming when a target arrives from two different directions (θ, φ) = (-20°, 0°) and (-10°, 0°) with equal received power levels. The values on the right side of the heat map represent decibel values.

[0527] From the computer simulation results, compared with Figure 29A 、 Figure 29B , it can be seen that Figure 29C 、 Figure 29D The heatmap shows fewer regions, i.e. Figure 29C and Figure 29D In the present invention, by using a virtual surface to configure the array antenna, the number of elements can be virtually increased, thereby achieving the effect of reducing the grating lobe and side lobe levels in the two-dimensional spatial distribution calculated in the two-dimensional direction estimation process.

[0528] Furthermore, since direction estimation section 250 calculates a two-dimensional spatial distribution using a virtual plane array antenna, the amount of computation required is greater than that of direction estimation section 214. However, when beamforming is used, the amount of computation can be reduced by using two-dimensional FFT processing.

[0529] While various embodiments have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such examples. Those skilled in the art can readily envision various variations or modifications within the scope of the claims and recognize that these variations naturally fall within the technical scope of the present invention. Furthermore, the constituent elements of the above embodiments may be arbitrarily combined without departing from the spirit of the invention.

[0530] In the above-mentioned embodiments, the present invention has been described by way of examples in which the present invention is configured using hardware. However, the present invention can also be realized by software in cooperation with hardware.

[0531] In addition, the functional blocks used in the description of the above embodiments are generally implemented as integrated circuits, i.e., LSIs. The integrated circuit controls the functional blocks used in the description of the above embodiments and may also include input terminals and output terminals. These functional blocks may be integrated individually into a single chip, or may be partially or fully integrated into a single chip. Although referred to as LSI here, it may be referred to as IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.

[0532] Furthermore, circuit integration is not limited to LSIs; dedicated circuits or general-purpose processors can also be used. FPGAs (Field Programmable Gate Arrays) that can be programmed after LSI fabrication, or reconfigurable processors that can reconfigure the connections and settings of circuit cells within the LSI, can also be used.

[0533] Furthermore, if integrated circuit technology that can replace LSIs emerges with advances in semiconductor technology or other technologies derived from it, it would be possible to use this technology to integrate functional blocks. There is also the possibility of applying biotechnology, etc.

[0534] <Summary of the present invention>

[0535] A radar apparatus according to the present invention has a configuration including: a radar transmitting unit for transmitting radar signals from each of a plurality of transmitting antennas at a predetermined transmission cycle; and a radar receiving unit for receiving a plurality of reflected wave signals resulting from the plurality of radar signals being reflected from a target using a plurality of receiving antennas. The plurality of transmitting antennas include Nt1 transmitting antennas arranged in a first direction and Nt2 transmitting antennas arranged in a second direction orthogonal to the first direction. The plurality of receiving antennas include Na1 receiving antennas arranged in the first direction and Na2 receiving antennas arranged in the second direction. In the first direction, the element spacings between the Nt1 transmitting antennas and the element spacings between the Na1 receiving antennas are integer multiples of the first spacing and are all different values. In the second direction, the element spacings between the Nt2 transmitting antennas and the element spacings between the Na2 receiving antennas are integer multiples of the second spacing and are all different values.

[0536] In the radar device of the present invention, the sum of the antenna element spacings of the transmitting antenna in the first direction is smaller than the minimum value of the antenna element spacings of the receiving antenna in the first direction, or the sum of the antenna element spacings of the receiving antenna in the first direction is smaller than the minimum value of the antenna element spacings of the transmitting antenna in the first direction.

[0537] In the radar device of the present invention, in the first direction, among the Nt1 transmitting antennas and the Na1 receiving antennas, the maximum value of the element spacing of the antenna with a smaller number of antennas is greater than the maximum value of the element spacing of the antenna with a larger number of antennas, and in the second direction, among the Nt2 transmitting antennas and the Na2 receiving antennas, the maximum value of the element spacing of the antenna with a smaller number of antennas is greater than the maximum value of the element spacing of the antenna with a larger number of antennas.

[0538] In the radar device of the present invention, the radar receiving unit receives and processes the multiple reflected wave signals as signals received using a virtual receiving array composed of the multiple transmitting antennas and the multiple receiving antennas. In the virtual receiving array, the element spacings of any two virtual antenna elements among the Nt1×Na1 virtual antenna elements arranged in the first direction are each an integer multiple of 1 or more of the first spacing, and the element spacings of multiple of the any two virtual antenna elements include all spacings from 1 times to multiples of the first specified value.

[0539] In the radar device of the present invention, the radar receiving unit receives and processes the multiple reflected wave signals as signals received using a virtual receiving array composed of the multiple transmitting antennas and the multiple receiving antennas. In the virtual receiving array, the element spacings of any two virtual antenna elements among the Nt2×Na2 virtual antenna elements arranged in the second direction are each an integer multiple of 1 or more of the second spacing, and the element spacings of multiple of the any two virtual antenna elements include all spacings from 1 times to multiples of the second specified value.

[0540] In the radar device of the present invention, at least one of the multiple transmitting antennas and the multiple receiving antennas is composed of multiple subarray elements. When the size of each antenna in the first direction of the at least one antenna is greater than 1 wavelength, at least one combination is included in which the difference between the element spacing of the Nt1 transmitting antennas and the element spacing of the Na1 receiving antennas is less than 1 wavelength. When the size of each antenna in the second direction of the at least one antenna is greater than 1 wavelength, at least one combination is included in which the difference between the element spacing of the Nt2 transmitting antennas and the element spacing of the Na2 receiving antennas is less than 1 wavelength.

[0541] In the radar device of the present invention, the radar receiving unit performs reception processing on the multiple reflected wave signals as signals received by a virtual plane configuration array antenna virtually configured at positions represented by inter-element vectors in all elements of a virtual receiving array composed of the multiple transmitting antennas and the multiple receiving antennas. In the virtual receiving array, the element spacings of any two virtual antenna elements among the Nt1×Na1 virtual antenna elements configured in the first direction are each an integer multiple of 1 or more of the first spacing, and the element spacings of the multiple arbitrary two virtual antenna elements include all spacings from 1 times to multiples of the first specified value.

[0542] In the radar device of the present invention, the radar receiving unit performs reception processing on the multiple reflected wave signals as signals received by a virtual plane configuration array antenna virtually configured at positions represented by inter-element vectors in all elements of a virtual receiving array composed of the multiple transmitting antennas and the multiple receiving antennas. In the virtual receiving array, the element spacings of any two virtual antenna elements among the Nt2×Na2 virtual antenna elements configured in the second direction are each an integer multiple of 1 or more of the second spacing, and the element spacings of multiple of the any two virtual antenna elements include all spacings from 1 times to multiples of the second specified value.

[0543] In the radar apparatus of the present invention, the plurality of transmitting antennas are arranged so as to maximize Nt1×Nt2, and the plurality of receiving antennas are arranged so as to maximize Na1×Na2.

[0544] In the radar apparatus of the present invention, the plurality of transmitting antennas and the plurality of receiving antennas are arranged in an L-shape, a T-shape, or a cross-shape.

[0545] Industrial Applicability

[0546] The present invention is suitable as a radar device for detecting a wide-angle range.

[0547] Description of labels

[0548] 10 Radar device

[0549] 100 radar transmitting unit

[0550] 200 radar receiving unit

[0551] 300 reference signal generation unit

[0552] 101, 101a radar transmission signal generation unit

[0553] 102 code generation unit

[0554] 103 Modulation Unit

[0555] 104 LPF

[0556] 105 Wireless Transmitter Unit

[0557] 106 Transmitting Antennas

[0558] 111 code storage unit

[0559] 112 DA conversion unit

[0560] 201 Antenna System Processing Unit

[0561] 202 Receiving Antenna

[0562] 203 Wireless Receiver Unit

[0563] 204 amplifier

[0564] 205 inverter

[0565] 206 Quadrature Detector

[0566] 207 Signal Processing Unit

[0567] 208, 209 AD conversion unit

[0568] 210 Separation Unit

[0569] 211 Correlation Operation Unit

[0570] 212 Addition Unit

[0571] 213 Doppler frequency analysis unit

[0572] 214, 250 Direction Estimation Unit

[0573] 251 direction vector storage unit

[0574] 252 Correlation Vector Generation Unit

[0575] 253 Evaluation function calculation unit

Claims

1. A radar device comprising: a radar transmitting unit that transmits radar signals from the first transmitting antenna, the second transmitting antenna, and the third transmitting antenna at a predetermined transmission period; and The radar receiving unit receives, using the first receiving antenna, the second receiving antenna, the third receiving antenna, and the fourth receiving antenna, a plurality of reflected wave signals resulting from the radar signal transmitted from each of the first, second, and third transmitting antennas and reflected from a target. The first transmitting antenna is isolated from the second transmitting antenna in a first direction, and the third transmitting antenna is separated from the first and second transmitting antennas in a second direction. The first, second and third receiving antennas are separated in a first direction, and the fourth receiving antenna is separated from the first, second and third receiving antennas in a second direction. In the first direction, a first distance between the first transmitting antenna and the second transmitting antenna, a second distance between the first receiving antenna and the second receiving antenna, and a third distance between the second receiving antenna and the third receiving antenna are integer multiples of the first common distance. The first distance, the second distance, and the third distance are different from each other, In the second direction, a fourth distance between the third transmitting antenna and the first transmitting antenna, and a fifth distance between the fourth receiving antenna and the first receiving antenna are integer multiples of the second common distance, and the fourth distance and the fifth distance are different from each other. The first distance is smaller than the second distance and the fifth distance is smaller than the fourth distance, or the sum of the second distance and the third distance is smaller than the first distance and the fourth distance is smaller than the fifth distance.

2. The radar device according to claim 1, wherein In the first direction, among the first and second transmitting antennas and the first, second and third receiving antennas, The first distance, which is the maximum value of the element spacing of a transmitting antenna having a small number of antennas, is greater than the second distance, which is the maximum value of the element spacing of a receiving antenna having a large number of antennas.

3. The radar device according to claim 1, wherein The radar receiving unit performs reception processing on the plurality of reflected wave signals as signals received using a virtual receiving array composed of the first, second, and third transmitting antennas and the first, second, third, and fourth receiving antennas. In the virtual receiving array, the element spacings of any two virtual antenna elements among the virtual antenna elements composed of the first and second transmitting antennas and the first, second and third receiving antennas arranged in the first direction are integer multiples of 1 or more of the first common distance, and the element spacings of multiple of the arbitrary two virtual antenna elements include all intervals from 1 times to times the first specified value.

4. The radar device according to claim 1, wherein The radar receiving unit receives and processes the plurality of reflected wave signals as signals received by the first, second, and third transmitting antennas and a virtual receiving array composed of the first, second, third, and fourth receiving antennas. In the virtual receiving array, the element spacings of any two virtual antenna elements among the virtual antenna elements formed by the third transmitting antenna and the fourth receiving antenna configured in the second direction are each an integer multiple of 1 or greater of the second common distance, and the element spacings of multiple of the arbitrary two virtual antenna elements include all intervals from 1 times to multiples of the second specified value.

5. The radar apparatus according to claim 1, wherein Each of the first, second, and third transmitting antennas and at least one of the first, second, third, and fourth receiving antennas is formed of a subarray element. When the size of each antenna in the first direction of the at least one antenna is greater than or equal to one wavelength, at least one of the difference between the first distance and the second distance and the difference between the first distance and the third distance is less than one wavelength. When the size of each antenna in the second direction of the at least one antenna is large, equal to or larger than one wavelength, the difference between the fourth distance and the fifth distance is smaller than one wavelength.

6. The radar apparatus according to claim 1, wherein The radar receiving unit performs reception processing on the plurality of reflected wave signals as signals received using a virtual plane arrangement array antenna virtually arranged at positions indicated by inter-element vectors in all elements of a virtual receiving array composed of the first, second, and third transmitting antennas and the first, second, third, and fourth receiving antennas. In the virtual receiving array, the element spacings of any two virtual antenna elements among the virtual antenna elements composed of the first and second transmitting antennas and the first, second and third receiving antennas arranged in the first direction are each an integer multiple of 1 or greater of the first common distance, and the element spacings of multiple of the arbitrary two virtual antenna elements include all spacings from 1 times to multiples of the first specified value.

7. The radar apparatus according to claim 1, wherein: The radar receiving unit performs reception processing on the plurality of reflected wave signals as signals received using a virtual plane arrangement array antenna virtually arranged at positions indicated by inter-element vectors in all elements of a virtual receiving array composed of the first, second, and third transmitting antennas and the first, second, third, and fourth receiving antennas. In the virtual receiving array, the element spacings of any two virtual antenna elements among the virtual antenna elements composed of the third transmitting antenna and the fourth receiving antenna configured in the second direction are each an integer multiple of 1 or greater of the second common distance, and the element spacings of multiple of the arbitrary two virtual antenna elements are all intervals from 1 times to multiples of the second specified value.

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