JP2020056780A - Radar device - Google Patents

Abstract

To provide an improved radar device capable of expanding an opening length per one antenna element and an opening length of a virtual reception array antenna.SOLUTION: A radar device includes a transmitting array antenna 108 and a receiving array antenna 202 one of which includes a first antenna element group in which a phase center of m antenna elements are arranged being equally spaced in a first axis direction with a first spacing D(m is an integer greater than or equal to 1), and the other of the transmitting array antenna and the receiving array antenna includes a second antenna element group in which a phase center of (n+1) antenna elements are arranged in the first axis direction with a second spacing D(n) (n is an integer greater than or equal to 1). A first interval Dsatisfies a desired relational expression (Equation (1)), and a second interval D(n) satisfies a specific relational expression.SELECTED DRAWING: Figure 9

Description

  The present disclosure relates to a radar device.

  In recent years, a radar device using a radar transmission signal having a short wavelength including a microwave or a millimeter wave capable of obtaining high resolution has been studied. Further, in order to improve outdoor safety, there is a demand for the development of a radar device (wide-angle radar device) that detects an object (target) including a pedestrian in a wide-angle range in addition to a vehicle.

  In addition, as a radar device, a configuration in which a plurality of antenna elements (array antennas) are provided in a transmission branch in addition to a reception branch and beam scanning is performed by signal processing using a transmission and reception array antenna (MIMO (Multiple Input Multiple Output) radar). (Sometimes called).

  In the MIMO radar, by arranging the antenna elements in the transmitting and receiving array antennas, a virtual receiving array antenna (hereinafter referred to as a virtual receiving array or a virtual receiving array) which is at most equal to the product of the number of transmitting antenna elements and the number of receiving antenna elements. Array antenna). This has the effect of increasing the effective aperture length of the array antenna with a small number of elements.

US Patent No. 9869762

  One embodiment of the present disclosure contributes to providing an improved radar device that can increase the aperture length per antenna element and the aperture length of a virtual reception array antenna.

ここで、ｄ_Ｈは第１の基本間隔を示し、ｎ_ｔは１以上の整数、
前記第２の間隔D_r(n)は、式（１ｂ）を満たし、

ここで、Ｎ_ａは、1≦n＜N_a-1を満たす整数であり、
ｎ_ｒは、式（１ｃ）を満たす、

構成を採る。 A radar device according to an aspect of the present disclosure includes a radar transmission circuit that transmits a radar signal from a transmission array antenna, and a radar reception circuit that receives a reflected wave signal of the radar signal reflected from a target from a reception array antenna, comprising, the one is the transmission array antenna and the reception array antenna, a first antenna element phase center of the m antenna elements are arranged at equal intervals in the first interval D _t along the first axis direction And the other of the transmitting array antenna and the receiving array antenna has a phase center of (n + 1) antenna elements at a second interval along the first axial direction. Including a second antenna element group arranged by D _r (n) (n is an integer of 1 or more), the first interval D _t satisfies the formula (1a),

Here, d _H indicates a first basic interval, _nt is an integer of 1 or more,
The second interval D _r (n) satisfies equation (1b),

Here, N _a is an integer satisfying 1 ≦ n <N _a -1,
n _r satisfies equation (1c);

Take the configuration.

  Note that these comprehensive or specific aspects may be realized by a system, a method, an integrated circuit, a computer program, or a recording medium, and any of the system, the device, the method, the integrated circuit, the computer program, and the recording medium It may be realized by any combination.

  According to an aspect of the present disclosure, it is possible to provide an improved radar device that can increase an aperture length per antenna element and an aperture length of a virtual reception array antenna.

  Further advantages and advantages of one aspect of the present disclosure will be apparent from the description and drawings. Such advantages and / or advantages are each provided by some embodiments and by the features described in the description and drawings, but not necessarily all to achieve one or more identical features. There is no.

FIG. 2 is a block diagram illustrating an example of a configuration of a radar device according to Embodiment 1. FIG. 3 is a block diagram illustrating an example of a configuration of a radar transmission unit according to Embodiment 1. FIG. 3 is a diagram illustrating an example of a radar transmission signal according to the first embodiment. 6 is a diagram showing an example of a time division switching operation of the transmitting antenna by the control unit according to Embodiment 1. FIG. FIG. 9 is a block diagram showing another example of the configuration of the radar transmission signal generation unit according to the first embodiment. FIG. 2 is a block diagram illustrating an example of a configuration of a radar receiving unit according to Embodiment 1. FIG. 4 is a diagram illustrating an example of a transmission timing of a radar transmission signal of the radar device according to Embodiment 1 and an example of a measurement range. FIG. 4 is a diagram showing a three-dimensional coordinate system used for describing the operation of the direction estimating unit according to the first embodiment. FIG. 4 is a diagram showing an example of an antenna arrangement according to the first embodiment. FIG. 3 is a diagram showing an example of a sub-array antenna configuration according to the first embodiment. FIG. 9 is a diagram illustrating an example of an antenna arrangement according to variation 1 of the first embodiment. FIG. 7 is a diagram showing an example of a directivity pattern by a one-dimensional beam by a virtual receiving array antenna according to variation 1 of the first embodiment. FIG. 7 is a diagram showing an example of a directivity pattern by a one-dimensional beam when a weight is applied to a virtual reception array antenna according to variation 1 of the first embodiment. FIG. 7 is a diagram illustrating an example of an antenna arrangement according to a first comparative example of the first embodiment; FIG. 7 is a diagram showing a comparison between an example of a directivity pattern by a one-dimensional beam by a virtual reception array antenna according to Variation 1 of Embodiment 1 and an example of a directivity pattern by a one-dimensional beam by a virtual reception array antenna according to Comparative Example 1; An example of a directivity pattern by a one-dimensional beam when a weight is applied to the virtual reception array antenna according to Variation 1 of Embodiment 1 and an example of a directivity pattern by a one-dimensional beam by the virtual reception array antenna according to Comparative Example 1 Diagram showing comparison of FIG. 7 is a diagram illustrating an example of an antenna arrangement according to variation 2 of the first embodiment. FIG. 9 is a diagram illustrating an example of an antenna arrangement according to variation 3 of the first embodiment. FIG. 10 is a diagram illustrating an example of an antenna arrangement according to variation 4 of the first embodiment. FIG. 9 is a diagram illustrating an example of an antenna arrangement according to variation 5 of the first embodiment. FIG. 10 is a diagram showing an example of a directivity pattern by a one-dimensional beam by a virtual receiving array antenna according to Variation 5 of Embodiment 1; FIG. 9 is a diagram illustrating an example of an antenna arrangement according to the second embodiment. FIG. 10 is a diagram showing an example of the size of each antenna element according to the second embodiment. FIG. 10 is a diagram showing an example of a cross-sectional view along a first axial direction of a directivity pattern of a two-dimensional beam by a virtual receiving array antenna according to a second embodiment. FIG. 10 is a diagram showing an example of a cross-sectional view along a second axial direction, showing a directivity pattern of a two-dimensional beam by the virtual receiving array antenna according to the second embodiment. FIG. 14 is a diagram illustrating an example of an antenna arrangement according to a second comparative example of the second embodiment. FIG. 7 is a diagram illustrating an example of a directivity pattern of a two-dimensional beam by the virtual reception array antenna according to the second embodiment, which is an example of a cross-sectional view along the first axis direction and a directivity pattern of the two-dimensional beam by the virtual reception array antenna according to the second comparative example. FIG. 7 is a diagram showing a comparison with an example of a cross-sectional view along the first axial direction FIG. 9 is a diagram illustrating an example of a directivity pattern of a two-dimensional beam by the virtual reception array antenna according to the second embodiment, which is an example of a cross-sectional view along the second axial direction, and a directivity pattern of the two-dimensional beam by the virtual reception array antenna according to the second comparative example. FIG. 7 shows a comparison with an example of a cross-sectional view along the second axial direction. FIG. 14 is a diagram showing an example of the arrangement of a transmission array antenna and a reception array antenna according to variation 1 of the second embodiment. The figure which shows an example of arrangement | positioning of the virtual receiving array antenna which concerns on the variation 1 of Embodiment 2. FIG. 10 is a diagram showing an example of the size of an antenna element according to variation 1 of the second embodiment. FIG. 10 is a diagram showing an example of a cross-sectional view along a first axis direction of a directivity pattern of a two-dimensional beam by a virtual reception array antenna according to variation 1 of the second embodiment. FIG. 10 is a diagram showing an example of a cross-sectional view along a second axis direction, showing a directivity pattern of a two-dimensional beam by a virtual reception array antenna according to variation 1 of the second embodiment. FIG. 11 is a diagram showing an example of the arrangement of a transmission array antenna and a reception array antenna according to Variation 2 of Embodiment 2. The figure which shows an example of arrangement | positioning of the virtual receiving array antenna which concerns on the variation 2 of Embodiment 2. FIG. 10 is a diagram showing an example of the size of an antenna element according to variation 2 of the second embodiment. FIG. 14 is a diagram showing an example in which the size of the antenna element according to Variation 2 of Embodiment 2 is different for each antenna element. FIG. 10 is a diagram showing an example of a cross-sectional view along a first axis direction of a directivity pattern of a two-dimensional beam by a virtual reception array antenna according to Variation 2 of Embodiment 2. FIG. 10 is a diagram illustrating an example of a cross-sectional view along a second axis direction, showing a directivity pattern of a two-dimensional beam by a virtual reception array antenna according to Variation 2 of Embodiment 2. FIG. 10 is a diagram showing an example of the arrangement of a transmission array antenna and a reception array antenna according to variation 3 of the second embodiment. The figure which shows an example of arrangement | positioning of the virtual receiving array antenna which concerns on the variation 3 of Embodiment 2. FIG. 14 is a diagram showing an example of the size of an antenna element according to variation 3 of the second embodiment. The figure which shows an example when the size of the antenna element which concerns on the variation 3 of Embodiment 2 differs for every antenna element. FIG. 14 is a diagram illustrating an example of a cross-sectional view along a first axis direction of a directivity pattern of a two-dimensional beam by a virtual reception array antenna according to Variation 3 of Embodiment 2. FIG. 14 is a diagram illustrating an example of a cross-sectional view along a second axial direction, showing a directivity pattern of a two-dimensional beam by a virtual receiving array antenna according to Variation 3 of Embodiment 2. FIG. 17 is a diagram showing an example of the arrangement of the transmitting and receiving array antennas and the arrangement of the virtual receiving array antenna according to the third embodiment. FIG. 14 is a diagram showing another example of the arrangement of the transmission / reception array antenna according to the third embodiment. FIG. 21 is a diagram showing another example of the arrangement of the virtual reception array antenna according to the third embodiment. FIG. 14 is a diagram showing another example of the arrangement of the transmission / reception array antenna according to the third embodiment. FIG. 21 is a diagram showing another example of the arrangement of the virtual reception array antenna according to the third embodiment. FIG. 14 is a diagram showing another example of the arrangement of the transmission / reception array antenna according to the third embodiment. FIG. 21 is a diagram showing another example of the arrangement of the virtual reception array antenna according to the third embodiment. FIG. 9 is a block diagram illustrating an example of a configuration of a radar device according to Embodiment 4. Block diagram showing an example of the configuration of a radar device according to Embodiment 5. FIG. 14 is a diagram showing an example of a chirp pulse used by the radar device according to the fifth embodiment.

  For example, a pulse radar device that repeatedly transmits a pulse wave is known as a radar device. A received signal of a wide-angle pulse radar for detecting a vehicle / pedestrian in a wide-angle range is obtained by mixing a plurality of reflected waves from a target located at a short distance (eg, a vehicle) and a target located at a long distance (eg, a pedestrian). Signal. For this reason, (1) the radar transmitting unit is required to have a configuration for transmitting a pulse wave or a pulse-modulated wave having an autocorrelation characteristic (hereinafter, referred to as a low range sidelobe characteristic) serving as a low range sidelobe, and (2). The radar receiver is required to have a configuration having a wide reception dynamic range.

  The configuration of the wide-angle radar device includes the following two configurations.

  The first configuration is that a pulse wave or a modulated wave is mechanically or electronically scanned using a directional beam having a narrow angle (a beam width of several degrees) to transmit a radar wave, and a narrow angle directional beam is transmitted. This is a configuration for receiving a reflected wave using a neutral beam. In this configuration, the number of scans increases in order to obtain high resolution, so that the followability for a target moving at high speed is deteriorated.

  The second configuration is that, in the reception branch, a reflected wave is received by an array antenna composed of a plurality of antennas (a plurality of antenna elements), and the arrival of the reflected wave is performed by a signal processing algorithm based on a reception phase difference with respect to an antenna element interval. The configuration uses a method of estimating an angle (Direction of Arrival (DOA) estimation). In this configuration, even if the scanning interval of the transmission beam in the transmission branch is thinned, the angle of arrival can be estimated in the reception branch, so that the scanning time can be shortened and the tracking can be performed as compared with the first configuration. The performance is improved. For example, the direction-of-arrival estimation method includes Fourier transform based on matrix operation, Capon method and LP (Linear Prediction) method based on inverse matrix operation, or MUSIC (Multiple Signal Classification) based on eigenvalue operation and ESPRIT (Estimation of Signal Parameters). via Rotational Invariance Techniques).

  Also, in addition to the reception branch, the MIMO radar that performs beam scanning using a plurality of antenna elements in the transmission branch also transmits a signal multiplexed using time division, frequency division or code division from a plurality of transmission antenna elements, and A signal reflected by an object is received by a plurality of receiving antenna elements, and a multiplexed transmission signal is separated and received from each of the received signals.

  Further, in the MIMO radar, by devising the arrangement of the antenna elements in the transmission / reception array antenna, a virtual reception array antenna (virtual reception array or virtual reception array) which is at most equal to the product of the number of transmission antenna elements and the number of reception antenna elements. Receiving array antenna). As a result, a propagation path response represented by the product of the number of transmitting antenna elements and the number of receiving antenna elements can be obtained. By appropriately arranging the transmitting and receiving antenna element intervals, the effective aperture of the array antenna can be reduced with a small number of elements. The length can be virtually enlarged to improve the angular resolution.

  Here, as the antenna element configuration in the MIMO radar, there are a configuration using one antenna element (hereinafter, referred to as a single antenna) and a configuration in which a plurality of antenna elements are formed into a sub-array (hereinafter, referred to as a sub-array or a sub-array antenna configuration). Are roughly divided into

  When a single antenna is used, the characteristics have a wider directivity than when a subarray is used, but the antenna gain is relatively low. Therefore, in order to improve the reception SNR (Signal to Noise Ratio) of the reflected wave signal, in the reception signal processing, for example, more addition processing is performed, or an antenna is configured using a plurality of single antennas. become.

  On the other hand, when a sub-array is used, a single sub-array includes a plurality of antenna elements as compared with a case where a single antenna is used. Antenna gain can be improved. Specifically, the physical size of the sub-array is equal to or larger than the wavelength at the radio frequency (carrier frequency) of the transmission signal.

  The MIMO radar can be applied not only to one-dimensional scanning in the vertical or horizontal direction but also to two-dimensional beam scanning in the vertical and horizontal directions (for example, see Patent Document 1).

  As a MIMO radar that performs beam scanning in two dimensions, for example, there is a long-distance MIMO radar used for in-vehicle applications. In a long-distance MIMO radar, a high resolution in the horizontal direction equivalent to that of a MIMO radar that performs one-dimensional beam scanning in the horizontal direction is required, and a capability of estimating an angle in the vertical direction is also required.

  For example, when there is a restriction on the number of transmitting and receiving antennas for a MIMO radar (for example, about 4 transmitting antenna elements and / or about 4 receiving antenna elements) due to a request for cost reduction or the like, more antenna elements are used. Therefore, it is difficult to improve the reception SNR of the reflected wave signal. Furthermore, the MIMO radar that performs two-dimensional beam scanning has a restriction on the aperture length of the virtual receiving array antenna by the MIMO radar as compared with the MIMO radar that performs one-dimensional beam scanning, and the horizontal resolution is reduced.

  In order to improve the capability of estimating the angle in the vertical direction, for example, by using a sub-array antenna configuration in which each of the antenna elements constituting the array antenna (hereinafter, referred to as an array element) further includes a plurality of antenna elements. The directional gain of the array antenna may be improved. However, when the antenna elements of both the transmitting antenna element and the receiving antenna element are arranged at equal intervals in the horizontal and vertical directions at about a half wavelength, the spacing between adjacent antenna elements is also about a half wavelength. Therefore, it is difficult to make the size of the antenna element larger than about half a wavelength, and it is difficult to make the antenna element into a sub-array due to physical restrictions due to physical interference with an adjacent antenna element.

  On the other hand, it is also possible to arrange antennas at irregular intervals in order to make the antenna elements into a sub-array, and to increase the interval between adjacent antennas by one or more wavelengths (see Patent Document 1). However, if the interval between adjacent antennas is extended by one wavelength or more, the interval between the virtual receiving array antennas is extended to one wavelength or more, and grating lobes or side lobe components are generated in the angular direction, and the probability of erroneous detection by the radar device increases. I do.

  In order to realize a MIMO radar with few erroneous detections, a configuration of a virtual receiving array antenna in which the side lobe of a beam to be formed is low is required. In order to reduce the side lobes, it is desirable to arrange the antenna elements in the virtual receiving array antenna at equal intervals in the horizontal and vertical directions at about half a wavelength. Therefore, there has been proposed a configuration in which the antenna elements are arranged at regular intervals of one or more wavelengths, and the virtual receiving array antennas are arranged at half-wavelength intervals (see Patent Document 1). However, since the virtual receiving array antennas are arranged at half-wavelength intervals, the aperture length of the virtual receiving array antenna is limited by the restriction on the number of antennas. Also, as the antenna element interval is increased, a grating lobe is generated near the main lobe, and the probability of erroneous detection increases.

<First Embodiment>
According to an aspect of the present disclosure, a radar device that can suppress the generation of unnecessary grating lobes while increasing the aperture length of a virtual reception array antenna is provided. Further, there is provided a radar apparatus capable of improving the directivity gain of an antenna element by using a sub-array antenna configuration for the antenna element.

  Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the embodiments, the same components are denoted by the same reference numerals, and the description thereof will not be repeated.

  The embodiments described below are examples, and the present disclosure is not limited to the following embodiments.

[Configuration of the radar device 10]
FIG. 1 is a block diagram illustrating an example of a configuration of a radar device 10 according to the present embodiment. The radar device 10 includes a radar transmission unit (also referred to as a transmission branch or a radar transmission circuit) 100, a radar reception unit (also referred to as a reception branch or a radar reception circuit) 200, a reference signal generation unit (reference signal generation circuit) 300, A control unit (control circuit) 400.

  The radar device 10 is, for example, a MIMO radar using a time division multiplex method. That is, in the radar transmitting unit 100 of the radar device 10, a plurality of transmission antennas are switched in a time division manner, and different time division multiplexed radar transmission signals are transmitted. Further, in the radar receiving section 200 of the radar device 10, the reception processing is performed by separating each time-division multiplexed transmission signal. However, the configuration of the radar device 10 is not limited to this. For example, in the radar transmitting unit 100 of the radar device 10, different transmission signals subjected to frequency division multiplexing are transmitted from a plurality of transmission antennas, and the radar receiving unit 100 separates the frequency division multiplexed transmission signals to perform reception processing. May be performed. Similarly, for example, in the radar transmitting unit 100 of the radar device 10, different transmission signals multiplexed by code division are transmitted from a plurality of transmission antennas, and the radar reception unit 100 separates each transmission signal multiplexed by code division. In such a case, the receiving process may be performed. Hereinafter, the radar device 10 using the time division multiplexing method will be described as an example.

The radar transmitter 100 generates a high-frequency (radio frequency) radar signal (radar transmission signal) based on the reference signal received from the reference signal generator 300. Then, radar transmitting section 100 switches the plurality of transmitting antenna elements # 1 to _#Nt in a time-division manner and transmits a radar transmission signal.

Radar receiver 200, a reflected wave signal is reflected radar transmission signal in the target (not shown), it receives using a plurality of receive antenna elements # 1~ # N _a. The radar receiving unit 200 performs a process synchronized with the radar transmitting unit 100 by performing the following processing operation using the reference signal received from the reference signal generating unit 300. The radar receiver 200 performs signal processing on the reflected wave signal received by each of the receiving antenna elements 202, and performs at least detection of the presence or absence of a target or estimation of the direction. The target is an object to be detected by the radar device 10, and includes, for example, a vehicle (including two, three, and four wheels) or a person.

  The reference signal generator 300 is connected to each of the radar transmitter 100 and the radar receiver 200. The reference signal generating unit 300 supplies the reference signal to the radar transmitting unit 100 and the radar receiving unit 200, and synchronizes the processes of the radar transmitting unit 100 and the radar receiving unit 200.

The control unit 400 sets a pulse code generated by the radar transmission unit 100, a phase set in the variable beam control by the radar transmission unit 100, and a level at which the radar transmission unit 100 amplifies a signal for each radar transmission cycle _Tr. I do. Then, the control unit 400 transmits a control signal (code control signal) indicating a pulse code, a control signal (phase control signal) indicating a phase, and a control signal (transmission control signal) indicating an amplification level of a transmission signal. , To the radar transmitter 100. In addition, control section 400 outputs to radar receiving section 200 an output switching signal instructing switching timing of transmission sub-arrays # 1 to #N (output switching of radar transmission signals) in radar transmitting section 100.

[Configuration of Radar Transmitter 100]
FIG. 2 is a block diagram illustrating an example of a configuration of radar transmitting section 100 according to the present embodiment. The radar transmission unit 100 includes a radar transmission signal generation unit (radar transmission signal generation circuit) 101, a transmission frequency conversion unit (transmission frequency conversion circuit) 105, a power divider (power distribution circuit) 106, and a transmission amplification unit (transmission). Amplifying circuit) 107 and a transmission array antenna 108.

  In the following, the configuration of the radar transmitting unit 100 using the coded pulse radar is shown as an example, but is not limited thereto. For example, radar transmission using frequency modulation of an FM-CW (Frequency Modulated Continuous Wave) radar. The same can be applied to signals.

The radar transmission signal generator 101 generates a timing clock (clock signal) obtained by multiplying the reference signal received from the reference signal generator 300 by a predetermined number, and generates a radar transmission signal based on the generated timing clock. Then, the radar transmission signal generation unit 101 repeatedly outputs the radar transmission signal at the radar transmission period _Tr based on the code control signal for each predetermined radar transmission period _Tr from the control unit 400.

Radar transmission _{signal, y (k t, M)} = I (k T, M) + jQ (k t, M) is represented by. Here, j represents an imaginary unit, k represents a discrete time, and M represents an ordinal of a radar transmission cycle. Further, I (k _T , M) and Q (k _T , M) are in-phase components (In-Phase components) of the radar transmission signal (k _T , M) at the discrete time k _T in the M-th radar transmission cycle. , And a quadrature component.

  The radar transmission signal generation unit 101 includes a code generation unit (code generation circuit) 102, a modulation unit (modulation circuit) 103, and an LPF (Low Pass Filter) 104.

The code generation unit 102 generates a code a _n (M) (n = 1,..., L) of a code sequence having a code length L in the M-th radar transmission cycle based on a code control signal for each radar transmission cycle _Tr. (Pulse code). As the code a _n (M) generated by the code generation unit 102, a pulse code that provides a low range sidelobe characteristic is used. Examples of the code sequence include a Barer code, an M-sequence code, and a Gold code. The code a _n (M) generated by the code generation unit 102 may be the same code or a code including a different code.

Modulator 103, a pulse modulation to the code a _n (M) output from the code generation unit 102 (amplitude modulation, ASK (Amplitude Shift Keying), or pulse shift keying) or phase modulation (PSK: Phase Shift Keying) And outputs the modulated signal to the LPF 104.

  LPF 104 outputs, to the transmission frequency conversion section 105, a signal component having a frequency equal to or less than a predetermined limit band among the modulation signals output from the modulation section 103, as a baseband radar transmission signal.

  The transmission frequency conversion unit 105 frequency-converts a baseband radar transmission signal output from the LPF 104 into a radar transmission signal in a predetermined carrier frequency (RF: Radio Frequency) band.

Power divider 106, a radar transmission signal of a radio frequency band output from the transmission frequency converter 105 partitioned the N _t, and outputs to the transmission amplification section 107.

Transmission amplification section 107 _{(107-1~107-N t)} based on the transmission control signal of the radar transmission every period T _r which is instructed by the control unit 400 amplifies the radar transmission signal outputted to a predetermined level Output or turn off the transmission output.

Transmission array antenna 108 has _{N t} transmit antennas elements _{# 1~ # N t (108-1~108-} N t). Each transmit antenna elements # 1~ # _{N t} are each connected to a separate transmit amplifier section 107-1 to _{107-N t,} radar transmission output from a separate transmit amplifier section 107-1 to _{107-N t} Send a signal.

FIG. 3 is a diagram illustrating an example of a radar transmission signal according to the first embodiment. In each radar transmission period _Tr , a pulse code sequence is transmitted during a code transmission section _Tw , and the remaining section ( _Tr - _Tw ) is a non-signal section. The inner code transmission period T _w includes code length L pulse code sequence. One code includes L sub-pulses. Further, per sub-pulses, by pulse modulation using N _o samples is performed, within each code transmission period T _w, include _{N r (= N o × L} ) samples. Further, a non-signal section (T _r −T _w ) in the radar transmission cycle _Tr includes Nu samples.

Figure 4 shows an example of division switching operation time of each transmit antenna elements # 1~ # N _t by the control unit 400. 4, the control unit 400, for each radar transmission cycle T _r, in order from the transmit antenna elements # 1 to transmit antenna element #N _t, the control signal (sign control signal for an instruction to switch the output from each transmit antenna elements , Transmission control signal) to the radar transmitting unit 100. Control section 400 sets the transmission output period of each transmission sub-array to (T _r × N _b ), and the transmission output period (T _r × N _p ) of all transmission sub-arrays = (T _r × N _b × N _t ). Is repeated _Nc times. Further, a radar receiving unit 200 described later performs a positioning process based on a switching operation of the control unit 400.

For example, when transmitting a radar transmission signal from transmission antenna element # 1, control section 400 causes transmission amplification section 107-1 connected to transmission antenna element # 1 to amplify the input signal to a predetermined level. outputs a transmission control signal for instructing, to the transmission antenna element # is not connected to a transmit amplifier section 107-2~107-N _t, and outputs a transmission control signal that instructs to turn off the transmission output .

  Similarly, when transmitting a radar transmission signal from transmission antenna element # 2, control section 400 causes transmission amplification section 107-2 connected to transmission antenna element # 2 to amplify the input signal to a predetermined level. , And outputs a transmission control signal instructing the transmission amplifier 107 not connected to the transmission antenna element # 2 to turn off the transmission output.

Thereafter, the control unit 400 performs the order similar control to the transmission antenna elements # 3~ # _{N t.} The output switching operation of the radar transmission signal by the control unit 400 has been described above.

[Other Configurations of Radar Transmitter 100]
FIG. 5 is a block diagram showing another example of the configuration of the radar transmission signal generation unit 101 according to Embodiment 1. The radar transmission section 100 may include a radar transmission signal generation section 101a shown in FIG. 5 instead of the radar transmission signal generation section 101. The radar transmission signal generation unit 101a does not include the code generation unit 102, the modulation unit 103, and the LPF 104 illustrated in FIG. 2, but instead includes the code storage unit (code storage circuit) 111 and the DA conversion unit (DA) illustrated in FIG. (Conversion circuit) 112.

  The code storage unit 111 stores in advance the code sequence generated by the code generation unit 102 shown in FIG. 2, and sequentially reads out the stored code sequence cyclically.

  The DA converter 112 converts a code sequence (digital signal) output from the code storage 111 into an analog baseband signal.

[Configuration of Radar Receiver 200]
FIG. 6 is a block diagram showing an example of the configuration of the radar receiving section 200 according to the present embodiment. Radar receiver 200 includes a receiving array antenna 202, _{N a} number of antenna elements system processor (antenna element line processing circuit) 201 and (201-1 to _{201-N a),} the direction estimating section (direction estimation circuit) 214 And

Receiving array antenna 202 has a _{N a} number of receiving antenna elements _{# 1~ # N a (202-1~202-} N a). N _a number of receiving antenna elements 202-1 through 202-N _a receives the reflected wave signal is a radar transmission signal reflected by the reflective object including the measurement target (object), a reflected wave signal received, respectively, and outputs as a received signal to a corresponding antenna element system processor 201-1 to _{201-N a.}

Each antenna element system processor 201 (201-1 to _{201-N a)} includes a reception radio section (reception radio circuit) 203, and a signal processing unit (signal processing circuit) 207. The reception radio unit 203 and the signal processing unit 207 generate a timing clock (reference clock signal) obtained by multiplying the reference signal received from the reference signal generation unit 300 by a predetermined number, and operate based on the generated timing clock to perform radar transmission. Synchronization with the unit 100 is ensured.

The reception radio unit 203 includes an amplifier (amplification circuit) 204, a frequency converter (frequency conversion circuit) 205, and a quadrature detector (quadrature detection circuit) 206. Specifically, in z-th reception radio section 203, amplifier 204 amplifies a reception signal received from z-th reception antenna element #z to a predetermined level. Here, z = 1,..., _Nr . Next, the frequency converter 205 converts the frequency of the received signal in the high-frequency band to the baseband. Next, the quadrature detector 206 converts the received signal in the baseband into a received signal in the baseband including the I signal and the Q signal.

Each signal processing unit 207 includes a first AD conversion unit (AD conversion circuit) 208, a second AD conversion unit (AD conversion circuit) 209, a correlation operation unit (correlation operation circuit) 210, and an addition unit (addition circuit). ) it has a 211, an output switching section (output switching circuit) 212, and the _{N t} Doppler analysis unit (Doppler analysis circuit) _{213-1～213-N t,} a.

  The first AD converter 208 receives an I signal from the quadrature detector 206. The first AD converter 208 converts the I signal into digital data by sampling the baseband signal including the I signal in discrete time.

  The second AD converter 209 inputs the Q signal from the quadrature detector 206. The second AD converter 209 converts the Q signal into digital data by sampling the baseband signal including the Q signal in discrete time.

Here, in the sampling of the first AD converter 208 and the second AD converter 209, Ns discrete samples are performed per time T _p (= T _w / L) of one sub-pulse in the radar transmission signal. . That is, the number of oversamples per sub-pulse is Ns.

FIG. 7 shows an example of a transmission timing of a radar transmission signal of the radar apparatus 10 according to Embodiment 1, and an example of a measurement range. In the following description, the I-th signal I _z (k, M) and the Q signal Q _z (k, M) are used to output the M-th signal as the output of the first AD converter 208 and the second AD converter 209. The received signal of the baseband at the discrete time k of the radar transmission cycle T _r [M] is represented as a complex signal x _z (k, M) = I _z (k, M) + jQ _z (k, M). In the following, the discrete time k is based on the timing at which the radar transmission cycle (T _r ) starts (k = 1), and the signal processing unit 207 uses the sampling points before the end of the radar transmission cycle _Tr. do periodically measured until a _{k = (N r + N u} ) N s / N o. In other words, k = 1, ..., a _{(N r + N u) N} s / N o. Here, j is an imaginary unit.

In the z-th signal processing unit 207, the correlation operation unit 210 performs the discrete sample value x _z (k, M) received from the first AD conversion unit 208 and the second AD conversion unit 209 for each radar transmission cycle _Tr. a), pulse code a _n of the code length L to be transmitted in a radar transmitter 100 (M) (except, z = 1, ..., n a, n = 1, ..., performs correlation calculation between L). For example, the correlation operation unit 210 performs a sliding correlation operation between the discrete sample value x _z (k, M) and the pulse code a _n (M). For example, the correlation operation value AC _z (k, M) of the sliding correlation operation at the discrete time k in the M-th radar transmission cycle T _r [M] is calculated based on Expression (1).

式（１）において、アスタリスク（*）は複素共役演算子を表す。

In equation (1), an asterisk (*) represents a complex conjugate operator.

Correlation calculation unit 210, for example, according to equation (1), k = 1, ..., performs correlation calculation for a period of _{(N r + N u) N} s / N o.

The correlation operation unit 210 is not limited to the case where the correlation operation is performed on k = 1,..., (N _r + N _u ) N _s / N _o , and the existence of the target to be measured by the radar device 10 The measurement range (that is, the range of k) may be limited according to the range. By limiting, the amount of calculation processing in the correlation calculation unit 210 is reduced. For example, correlation calculation section _{210, k = N s (L +} 1), ..., may be limited measurement range to _{(N r + N u) N} s / N o -N s L. In this case, as shown in FIG. 7, the radar device 10 does not perform the measurement in the time interval corresponding to a code transmission period T _w.

  With the above-described configuration, even when the radar transmission signal goes directly to the radar receiving unit 200, the processing by the correlation calculation unit 210 is not performed during the period when the radar transmission signal goes around (at least a period of less than τ1). Therefore, the radar apparatus 10 can perform measurement without the influence of the wraparound. When the measurement range (the range of k) is limited, the processing of the addition unit 211, the output switching unit 212, the Doppler analysis unit 213, and the direction estimation unit 214 described below is similarly performed on the measurement range (k). ) May be applied. As a result, the amount of processing in each component can be reduced, and the power consumption in the radar receiver 200 can be reduced.

In the z-th signal processing unit 207, addition unit 211, based on the output switching signal outputted from the control unit 400, a radar transmission cycle which is continuously transmitted from the N _D th transmit antenna element #N _D units period (T _r × N _b) a plurality of times N _b of T _r, using the correlation operation value AC _z (k, M) received from the correlation calculation unit 210 for each discrete time k, adds (coherent integration) Perform processing. _{Here, N D = 1, ...,} N t, z = 1, ..., a N _a.

The addition (coherent integration) processing over the period (T _r × N _b ) is represented by the following equation (2).

ここで、CI_z ^(ND)(k,m)は相関演算値の加算値（以下、相関加算値と呼ぶ）を表し、mは加算部２１１における加算回数の序数を示す１以上の整数である。また、z=1,…, N_aである。

Here, CI _z ^(ND) (k, m) represents an addition value of the correlation operation value (hereinafter, referred to as a correlation addition value), and m is an integer of 1 or more indicating an ordinal number of the number of additions in the addition unit 211. . In addition, z = 1, ..., a N _a.

Note that, in order to obtain an ideal addition gain, it is a condition that the phase components of the correlation operation value are aligned within a certain range in the addition section of the correlation operation value. That is, the number of additions is preferably set based on the assumed maximum moving speed of the target to be measured. This is because the larger the assumed maximum moving speed of the target is, the larger the fluctuation amount of the Doppler frequency included in the reflected wave from the target is, and the shorter the time period having a high correlation is, so that N _p (= N × N _b ) is This is because the value becomes small, and the gain improving effect by the addition in the adding unit 211 becomes small.

In the z-th signal processing unit 207, output switching unit 212, based on the output switching signal outputted from the control unit 400, the radar transmission cycle T _r which is continuously transmitted from the transmitting antenna elements of the N _D period a plurality of times N _b a (T _r × N _b) by adding to the unit, the addition result of each discrete time ^{_{k CI z (ND) (k}} , m) and the Doppler analysis unit 213-N _D of the N _D Selectively switch and output. _{Here, N D = 1, ...,} N t, z = 1, ..., a N _a.

Each of the signal processing unit 207 includes a transmission antenna element #. 1 to # _{N t} as many _{N t} pieces of the Doppler analysis unit _{213-1~213-N t.} The Doppler analyzer 213 (213-1 to 213 -N _t ) outputs CI _z ^(ND) (k, N _C (w−1)), which are N _c outputs of the adder 211 obtained for each discrete time k. +1) to CI _z ^(ND) (k, N _C × w) as one unit, and performs coherent integration by aligning the timing of the discrete time k. For example, the Doppler analysis unit 213, as shown in the following equation (3), the phase variations corresponding to 2N _f-number different Doppler frequency _{f s ΔΦ Φ (f s)} = 2πf s (T r × N b) ΔΦ Is corrected, coherent integration is performed.

ここで、FT_CI_z ^(ND)(k,f_s,w)は、第z番目の信号処理部２０７における第N_D番目のドップラ解析部２１３−Ｎ_Ｄにおける第w番目の出力であり、加算部２１１の第N_D番目の出力に対する、離散時間kでのドップラ周波数f_sΔΦのコヒーレント積分結果を示す。ただし、N_D=1,…,N_tであり、f_s=−N_f+1,…,0,N_fであり、k=1,…,(N_r+Nu)Ns/N_oであり、wは自然数であり、ΔΦは位相回転単位であり、jは虚数単位であり、z=1,…,N_aである。

^{_{Here, FT_CI z (ND) (k}} , f s, w) is the first w-th output in the N _D th Doppler analysis unit 213-N _D in the z-th signal processing unit 207, an adder for the first N _D th output of 211, shows the coherent integration results of the Doppler frequency f _s .DELTA..PHI at discrete time k. However, N _D = 1, ..., a _{N t, f s = -N f} + 1, ..., 0, is the _{N f, k = 1, ...} , be an _{(N r + Nu) Ns /} N o , w is a natural number, .DELTA..PHI is a phase rotating unit, j is an imaginary unit, z = 1, ..., a N _a.

Accordingly, each signal processing unit 207 generates FT_CI _z ^(ND) (k, −N _f +1, w),..., FT_CI which is a coherent integration result corresponding to 2N _f Doppler frequency components for each discrete time k. ^{_{z (ND) (k, N}} f -1, w) obtaining, in a plurality of times N _b × every period of _{N c (T r × N b} × N c) of the radar transmission circumferential period T _r.

If a ΔΦ = 1 / N _c, the processing of the Doppler analysis unit 213 described above, the sampling interval _{T m = (T r × N} p), a discrete output of the adder 211 at the sampling frequency f _m = 1 / T _m This is equivalent to Fourier transform (DFT) processing.

Further, by setting N _f to a power of two, the Doppler analysis unit 213 can apply fast Fourier transform (FFT) processing, and can reduce the amount of calculation processing. Note that when N _f > N _c , in a region where q> N _c , CI _z ^(ND) (k, N _c (w−1) +1) = 0 is performed to perform a zero padding process. 213 can similarly apply FFT processing and reduce the amount of arithmetic processing.

Further, the Doppler analyzer 213 may perform a process of sequentially calculating the product-sum operation shown in the above equation (3) instead of the FFT process. That is, the Doppler analysis unit 213 outputs N _c outputs CI _z ^(ND) (k, N _c (w−1) + q + 1) of the addition unit 211 obtained at each discrete time k. , F _s = −N _f +1,..., 0, N _f −, and the coefficients exp [−j2πfs _{s Tr} N _b qΔΦ] may be generated, and the product-sum operation may be sequentially performed. Here, q = 0,..., N _c −1.

Note that the following description, the same processing at each of the first antenna element from the signal processing unit 207 of the system processor 201-1 of the _{N a-th} antenna system processing unit _{201-N a} signal processing unit 207 subjecting the w-th output FT_CI _z ⁽¹⁾ obtained in _{(k, f s, w)} , ..., FT_CI z (Na) (k, f s, w) to the following equation (4) (or formula (5)) is denoted as a virtual reception array correlation vector _{h (k, f s, w} ) as.

Virtual reception array correlation vector _{h (k, f s, w} ) is the product of the number N _a number N _t and the receiving antenna elements #. 1 to # N _a transmit antenna elements #. 1 to # N _t N _t × N Contains _a number of elements. Virtual reception array correlation vector _{h (k, f s, w} ) will be described later, explanation of processing for direction estimation based on the phase difference between the receiving antenna elements # 1~ # N _a the reflection wave signal from the target Used for Here, z = 1, ..., a _{N a, N D = 1,} ..., a N _t.

Further, in the above equation (4) and (5), the phase rotation for each Doppler frequency (f _s .DELTA..PHI) due to the transmission time difference between the transmission sub-array is corrected. That is, the first transmission sub-arrays of (N _D = 1) as a reference, the received signal FT_CI _z ^(Na) of the Doppler frequency (f _s ΔΦ) component from transmission subarray of the _{N D (k, f s,} w) to _{against, exp [-j2πf s ΔΦ (N} D -1) T r N b] is multiplied.

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

Direction estimation unit 214, w th output from the 1st antenna element system processor signal processing unit 207 of 201-1 to the _{N a} th antenna element system processor _{201-N a} signal processing unit 207 virtual reception array correlation vector h of the Doppler analysis unit 213 (k, f _s, w) with respect to, as represented by the following formula (6), the phase shift between the transmission array antenna 108 and between the receiving array antennas 202 by multiplying the deviation and the array correction value h _cal for correcting the amplitude deviation _[b], the virtual reception array correlation vector h _{_After_cal} corrected for inter-antenna deviation (k, f _s, w) is calculated. Note that b = 1,..., (N _t × N _a ).

Virtual reception array correlation corrected for inter-antenna deviation vector _{h _after_cal (k, f s,} w) is a column vector of N _a × N _r number of elements. In the following, the virtual reception array correlation vector _{h _after_cal (k, f s,} w) of each element of _{h 1 (k, f s,} w), ..., denoted _{h Na × Nr (k, f} s, w) and Thus, the direction estimation process will be described.

Then, the direction estimating unit 214, the virtual reception array correlation vector _{h _after_cal (k, f s,} w) using the estimated direction of arrival of the reflected wave signal based on a phase difference between the reflected wave signals between the receiving array antennas 202 Perform processing.

The direction estimating unit 214 calculates a spatial profile by changing the azimuth direction θ in the direction estimation evaluation function value P _H (θ, k, f _s , w) within a predetermined angle range, and calculates the maximum peak of the calculated spatial profile. A predetermined number is extracted in descending order, and the azimuth direction of the local maximum peak is used as the estimated value of the arrival direction.

Note that there are various evaluation function values P _H (θ, k, f _s , w) depending on the arrival direction estimation algorithm. For example, an estimation method using a known array antenna may be used.

  For example, the beamformer method can be represented by the following equations (7) and (8).

Here, the superscript H is a Hermitian transpose operator. A _H (θ _u ) indicates a direction vector of the virtual receiving array antenna with respect to the arriving wave in the azimuth direction θ _u.In addition, θ _u changes the azimuth range in which the arrival direction is estimated at a predetermined azimuth interval β _1. It is a thing. For example, θ _u is set as follows.

ここでfloor(x)は、実数xを超えない最大の整数値を返す関数である。

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

  Instead of the beamformer method, a method such as Capon or MUSIC can be similarly applied.

  FIG. 8 shows a three-dimensional coordinate system used for explaining the operation of the direction estimating unit 214 according to the first embodiment. A case in which the processing of the direction estimation unit 214 is adapted to the three-dimensional coordinate system shown in FIG. 8 to perform the estimation processing in the two-dimensional direction will be described below.

8, the position vector of the target (target) P _T those relative to the origin O is defined as r _PT. Further, in FIG. 8, the projection points obtained by projecting the position vector r _PT of the target P _T to the XZ plane and P _T '. In this case, the azimuth θ is defined as an angle between the straight line OP _T ′ and the Z axis (θ> 0 when the X coordinate of the target _PT is positive). The elevation angle φ is defined as an angle of a line connecting the target P _T , the origin O, and the projection point P _T ′ in a plane including the target P _T , the origin O, and the projection point P _T ′ (object If the Y coordinate of the target _PT is positive, φ> 0). In the following, a case will be described as an example where transmission array antenna 108 and reception array antenna 202 are arranged in the XY plane.

The position vector of the n _va th antenna element in the virtual receiving array antenna with reference to the origin O is denoted as Sn _va . Here, n _va = 1,..., N _t × N _a .

The position vector S ₁ of the first (n _va = 1) antenna element in the virtual receiving array antenna is determined based on the positional relationship between the physical position of the first receiving antenna element Rx # 1 and the origin O. Is done. Position vector S ₂ of the other antenna elements in the virtual reception array _antenna, ..., Sn _va is based on the position vector S ₁ of the first antenna element, the transmission present in the XY plane array antenna 108 and the receiving array antenna The determination is made in a state where the relative arrangement of the virtual receiving array antenna determined from the element spacing of 202 is maintained. Note that the origin O may be made to coincide with the physical position of the first receiving antenna element Rx # 1.

When the radar receiving unit 200 receives the reflected wave from the target _PT existing in the far field, the second antenna element based on the reception signal at the first antenna element of the virtual reception array antenna The phase difference d (r _PT , 2,1) of the received signal is expressed by the following equation (9). Here, <x, y> is an inner product operator of the vector x and the vector y.

  The position vector of the second antenna element based on the position vector of the first antenna element of the virtual receiving array antenna is represented by the following equation (10) as an inter-element vector D (2,1). .

Similarly, when the radar receiver 200 receives a reflected wave from the target _PT existing in the far field, based on the reception signal at the n _va ^(r) th antenna element of the virtual reception array antenna, The phase difference d (r _PT , n _va ^(t) , n _va ^(r) ) of the received signal at the n _va ^(t) -th antenna element is expressed by the following equation (11). ^{_{Here, n va (r) = 1}} , ..., N t × N a, n va (t) = 1, ..., a N _t × N _a.

The position vector of the _nva ^(t) th antenna element based on the position vector of the _nva ^(r) th antenna element of the virtual receiving array antenna is referred to as an inter-element vector D ( _nva ^(t) , n _va ^(r) ) in the following equation (12).

As shown in the above equations (11) and (12), the _nva ^(t) th antenna element based on the reception signal at the _nva ^(r) th antenna element of the virtual receiving array antenna in the phase difference d of the received signal ^{_{(r PT, n va (t}} ), n va (r)) is a unit vector indicating the direction of the target object P _T present in the far field _{(r PT / | r PT |} ) And the inter-element vector D (n _va ^(t) , n _va ^(r) ).

When the virtual receiving array antenna exists on the same plane, the inter-element vector D (n _va ^(t) , n _va ^(r) ) exists on the same plane. The direction estimation unit 214 configures a virtual plane array antenna using all or a part of such inter-element vectors and assuming that an antenna element is virtually present at the position indicated by the inter-element vector, Is performed. That is, the direction estimating unit 214 performs the arrival direction estimating process using a plurality of virtual antennas interpolated by the interpolation process on the antenna elements forming the virtual receiving array antenna.

  When virtual antenna elements overlap, the direction estimation unit 214 may fixedly select one of the overlapping antenna elements in advance. Alternatively, the direction estimating unit 214 may perform the averaging process using the reception signals of all the overlapping virtual antenna elements.

Hereinafter, using N _q pieces of elements between vector group, in case where the virtual plane arranged array antennas, the direction estimation processing in two dimensions using the beam former method will be described.

Here, it represents the first n _q-th inter-element vector D that constitute the virtual plane disposed array antenna ^{_{(n va (nq) (t}} ), n va (nq) (r)). Here, n _q = 1,..., N _q .

The direction estimating unit 214 _calculates h ₁ (k, f _s , w),..., H _{Na × N} (k, f _s , w) which are each element of the virtual reception array correlation vector _{h_after_cal} (k, f _s , w). ) Is used to generate a virtual plane arrangement array antenna element correlation vector h _VA (k, f _s , w) shown in the following equation (13).

The virtual plane arrangement array direction vector a _VA (θ _u , φ _v ) is shown in the following equation (14).

If the virtual reception array antenna is present in the XY plane, the target P _T unit vector indicating the direction of _{(r PT / | r PT |} ) and, in the following the relationship between the azimuth angle θ and elevation φ Equation (15) Shown in

The direction estimating unit 214 calculates the unit vector (r _PT / | r _PT | for each of the angular directions θ _u and φ _v for calculating the two-dimensional spatial profiles in the vertical direction and the horizontal direction by using the above equation (15). ) Is calculated.

Further, the direction estimating unit 214 uses the virtual plane arrangement array antenna element correlation vector h _VA (k, f _s , w) and the virtual plane arrangement array direction vector a _VA (θ _u , φ _v ) to calculate the horizontal direction. And two-dimensional direction estimation processing in the vertical direction.

For example, in the direction estimation process in the two-dimensional using a beamformer method, a virtual plane disposed array antenna correlation vector _{h VA (k, f s,} w) and the virtual plane arranged array direction vector _{a VA (θ u, φ v} ) a The two-dimensional spatial profile in the vertical direction and the horizontal direction is calculated using the direction estimation evaluation function in two dimensions expressed by the following equation (16), and the azimuth that becomes the maximum value or the maximum value of the two-dimensional spatial profile is calculated. And the elevation direction are used as estimated values of the arrival direction.

The direction estimating section 214, other than the beam former method, using a virtual plane disposed array antenna correlation vector _{h VA (k, f s,} w) and the virtual plane arranged array direction vector _{a VA (θ u, φ v} ) Then, a high-resolution direction-of-arrival estimation algorithm such as the Capon method or the MUSIC method may be applied. Thereby, although the amount of calculation increases, the angular resolution can be increased.

  Note that the above-described discrete time k may be converted into distance information and output. When converting the discrete time k into distance information R (k), the following equation (17) may be used.

ここで、T_wは符号送信区間を表し、Lはパルス符号長を表し、C₀は光速度を表す。

Here, T _w denotes the code transmission section, L is representative of a pulse code length, C ₀ denotes the speed of light.

The Doppler frequency information may be converted into a relative velocity component and output. When converting the Doppler frequency f _s ΔΦ into the relative velocity component v _d (f _s ), the conversion can be performed using the following equation (18).

ここで、λは送信周波数変換部１０５から出力されるRF信号のキャリア周波数の波長である。

Here, λ is the wavelength of the carrier frequency of the RF signal output from the transmission frequency converter 105.

  The result obtained from direction estimating section 214 is output to a vehicle control section (not shown) mounted on the vehicle. The vehicle control unit controls the vehicle using the direction estimation result.

[Antenna Arrangement in Radar Apparatus 10]
The arrangement of the transmission array antenna 108 and the reception array antenna 202 in the radar apparatus 10 having the above configuration will be described.

FIG. 9 is a diagram illustrating an example of an antenna arrangement according to the first embodiment. The total number N _t of transmitting antenna elements that constitute the transmission array antenna 108 is 3 or more, the total number N _a of the receiving antenna elements constituting the receiving array antenna 202 is 4 or more. Both transmitting array antenna 108 and receiving array antenna 202 are arranged along the first axis direction. In FIG. 9, for example, the first axis direction and the second axis direction are a horizontal direction and a vertical direction, respectively.

Here, the basic interval in the first axis direction is d _H (about half a wavelength). As shown in FIG. 9, N _t transmit antennas elements Tx # 1~Tx # N _t are arranged at equal intervals in the first interval D _t along the first axis. D _t is a positive integer multiple of the basic spacing d _H. That is, D _t = n _t × d _H is represented by a certain positive integer n _t . Incidentally, N _t transmit antennas elements Tx # 1~Tx # N _t transmit antenna element group, referred to as a transmission antenna group.

Further, as shown in FIG. 9, N _a number of receiving antenna elements Rx # 1~Rx # N _a, respectively, spacing D _r (1) of the adjacent receiving antenna element ~D _r (N _a -1 ) Are arranged at irregular intervals. The interval D _r (n) (1 ≦ n ≦ N _a −1) represents the interval between the receiving antenna element Rx # n + 1 and the receiving antenna element Rx # n + 1 on the right side, and D _r (n) = (n _{r (n) × n t +1} ) is represented as d _H. Here, n _r = [n _r (1), n _r (2),..., N _r (N _a -1)] is one or two values located at the center, and 0 on both sides thereof. Alternatively, it is a number sequence in which a sequence of values increased by one is arranged symmetrically. When N _a = 4, for example, n _r = [2,1,2]. When N _a = 5, for example, n _r = [2,1,1,2]. If N _a = 6, for example, n _r = [2,1,1,1,2], n _r = [2,2,1,2,2], or n _r = [3,2,1, 2,3]. For _a positive integer n that satisfies 1 ≦ n <N _a −1, n _r (n) = n _r (N _a −n) holds, and for D _r (n), similarly, D _r (n) = D _r (N _a -n) holds. That is, the arrangement of the receiving array antenna 202 in FIG. 9 is such that the center portion has a narrow interval and the end portions have a wide interval. Incidentally, N _a number of receiving antenna elements Rx # 1~Rx # N _a receiving antenna element group, or, referred to as a reception antenna group.

  The reception array antenna 108 and the reception array antenna 202 can extend the aperture length (not shown) of the antenna element in the first axis direction and the second axis direction with the point shown in FIG. 9 as a phase center. Thereby, the beam width in the horizontal and vertical directions can be reduced, and a high antenna gain can be obtained. A sub-array antenna configuration may be used for each antenna element, and an array weight may be applied to the sub-array antenna element to suppress side lobes.

  FIG. 10 is a diagram illustrating an example of a sub-array antenna configuration according to Embodiment 1. The first axis direction and the second axis direction shown in FIG. 10 are, for example, the horizontal direction and the vertical direction, respectively.

  As shown in FIG. 10, various sub-array antenna configurations can be used for the antenna elements by setting the interval between the sub-array antenna elements to about half a wavelength. For example, when (a) a sub-array antenna configuration of one element in the first axial direction and four elements in the second axial direction is used, (b) a sub-array antenna configuration of one element in the first axial direction and ten elements in the second axial direction is used. (C) When a sub-array antenna configuration of two elements in the first axial direction and four elements in the second axial direction is used, (d) a sub-array antenna configuration of two elements in the first axial direction and ten elements in the second axial direction is used. And so on. Furthermore, the configuration of the sub-array antenna is not limited to the configuration shown in FIG. The antenna gain can be improved by increasing the aperture length.

For the case where the number of elements in the radar device 10 is the N _t transmit array antenna 108 and the number of elements N _a number of receiving array antenna 202 is disposed along the first axis, showing a plurality of examples are given below.

<Variation 1 of Embodiment 1>
In variation 1 of the present embodiment, an antenna arrangement in the case where the number of transmitting antenna elements is four and the number of receiving antenna elements is four, and a direction-of-arrival estimation method using the same will be described.

FIG. 11 is a diagram illustrating an example of an antenna arrangement according to variation 1 of the first embodiment. The first axis direction and the second axis direction shown in FIG. 11 are, for example, the horizontal direction and the vertical direction, respectively. Incidentally, the interval delimited by the dashed vertical line in a first axial direction, represents a fundamental spacing d _H of the first axial direction. In the following figures as well, the basic interval d _{H in} the first axis direction may be represented by a similar broken line. The arrangement of the transmission array antenna 108a and the arrangement of the reception array antenna 202a constitute the arrangement of the virtual reception array antenna VAA1.

11, the total number N _t of transmitting antenna elements that constitute the transmission array antenna 108a is four, four transmission antenna elements, respectively, represented by Tx # 1 to TX # 4. Transmit antenna elements Tx # 1 to TX # 4 are arranged at equal intervals in a first axial direction D _t = 2 × d _H. Here, the basic interval d _H in the first axial direction is, for example, d _H = 0.5λ. The total number N _a of the receiving antenna elements Rx constituting the reception array antenna 202a is four, four receive antenna elements, respectively, represented by Rx # 1~Rx # 4. Receive antenna elements Rx # 1~Rx # 4 are arranged at intervals of _{D r = [5,3,5] × d} H in the first axial direction. In the example shown in FIG. 11, n _r = [2,1,2].

  By using the sub-array antenna configuration shown in FIG. 10 for the antenna elements of the transmission array antenna 108a and the reception array antenna 202a shown in FIG. 11, a wide aperture length of the virtual reception array antenna VAA1 is secured, and the beam width is reduced. High antenna gain by the sub-array antenna can be obtained.

Here, the aperture length of the transmission array antenna 108a is, 2 × d _H below the first axis direction, may be formed of any length in the second axis direction. The aperture length of the receiving array antenna 202a is the first axis direction 3 × d _H below, may be constituted of any length in the second axis direction. Furthermore, a sub-array antenna configuration may be used for each antenna element, and an array weight may be applied to the sub-array antenna element to suppress side lobes.

  For example, when the field of view (FOV) required for the radar device 10 is wide in the horizontal direction and narrow in the vertical direction, the beam patterns of the antenna elements of the transmission array antenna 108a and the reception array antenna 202a are also horizontal. It is desirable that the angle be wide in the direction and narrow in the vertical direction. Therefore, it is conceivable that each antenna element uses, for example, a sub-array antenna configuration arranged in the vertical direction shown in FIG. 10B.

  For example, a FOV having a narrow angle in the horizontal direction is required for the radar device 10 used for long-distance detection on an expressway or the like. In this case, it is conceivable that each antenna element of the transmission array antenna 108a and the reception array antenna 202a adopts a configuration in which sub-array antenna elements are arranged in a horizontal direction, for example, as shown in (c) or (d) in FIG. Can be

  Similarly, it is desirable that each antenna element of the transmission array antenna 108a and the reception array antenna 202a use a sub-array antenna configuration that forms a beam pattern suitable for the viewing angle of the radar device.

  FIG. 12A shows an example of a directivity pattern by a one-dimensional beam by virtual reception array antenna VAA1 according to Variation 1 of Embodiment 1. The directivity pattern shown in FIG. 12A is formed in the first axis direction by the beamformer method using the virtual receiving array antenna VAA1 shown in FIG. The directivity pattern shown in FIG. 12A is a case where the arriving wave to the receiving array antenna 202a arrives from 0 degree (zenith) in the first axial direction.

  FIG. 12B shows an example of a directivity pattern by a one-dimensional beam when a weight is applied to virtual reception array antenna VAA1 according to variation 1 of the first embodiment. The radar device 10 may apply a weight to the signal received by the virtual receiving array antenna VAA1 to form a beam. For example, when the virtual reception array weights shown in FIG. 12B are applied to the received signals of VA # 1 to VA # 16, the main lobe width becomes large, but the side lobe level is lowered as shown in the beam pattern shown in FIG. 12B. Beam can be formed.

<Comparative Example 1>
Regarding Variation 1 of Embodiment 1, Comparative Example 1 will be considered.

FIG. 13 shows an example of an antenna arrangement according to Comparative Example 1 of the first embodiment. In Comparative Example 1 shown in FIG. 13, four transmit antenna elements Tx # 1 to TX # 4 of transmission array antenna 108b is disposed at equal intervals d _H. Also, four receive antenna elements Rx # 1~Rx # 4 of receiving array antenna 202b are equally spaced apart at intervals of 4 × d _H.

As shown in FIG. 13, a virtual reception array antenna VAA2 including transmission antenna elements Tx # 1 to Tx # 4 and reception antenna elements Rx # 1 to Rx # 4 has 16 virtual antennas, d _H Are arranged at equal intervals. Aperture length of the first axial direction of the virtual reception array antenna VAA2 of Comparative Example 1 is a 15 × d _H, a first axial aperture length 19 × d virtual reception array antenna VAA1 variations 1 of the first embodiment _Less than _H. Thus, in Comparative Example 1, it is difficult to increase the opening length of the virtual receiving array antenna VAA2 in the first axial direction, as compared with Variation 1 of Embodiment 1.

  FIG. 14A shows an example of a directivity pattern by a one-dimensional beam by virtual reception array antenna VAA1 according to Variation 1 of Embodiment 1 and an example of a directivity pattern by one-dimensional beam by virtual reception array antenna VAA2 according to Comparative Example 1. The following shows a comparison. Variation 1 and Comparative Example 1 both use the same number of transmitting antenna elements and receiving antenna elements.

  In the directivity pattern of Variation 1, a beam of the main lobe having a smaller width than that of Comparative Example 1 is formed. That is, the virtual receiving array antenna VAA1 according to Variation 1 has a virtual receiving array configuration with higher resolution than the virtual receiving array antenna VAA2 according to Comparative Example 1.

  As shown in FIG. 14A, the side lobe on the wide angle side in the directivity pattern of variation 1 is higher than the side lobe of comparative example 1. However, for example, when the horizontal viewing angle is narrowed, the wide-angle side is located outside the viewing angle, so the influence of the side lobe height is small and may be ignored.

  FIG. 14B shows an example of a directivity pattern by a one-dimensional beam when a weight is applied to virtual reception array antenna VAA1 according to Variation 1 of Embodiment 1 and a one-dimensional beam by virtual reception array antenna VAA2 according to Comparative Example 1. 7 shows a comparison with an example of a directivity pattern.

  As shown in FIG. 14B, in variation 1 of the first embodiment, by applying weight to virtual reception array antenna VAA1, a main lobe width and a side lobe level equivalent to comparative example 1 can be secured. Further, as compared with Comparative Example 1, in Variation 1 of Embodiment 1, the distance between the antenna elements of transmission array antenna 108a and reception array antenna 202a is wider.

  Therefore, in variation 1 of the first embodiment, higher antenna gain can be obtained by configuring transmission array antenna 108a and reception array antenna 202a by extending the aperture length of each antenna element in the horizontal direction. That is, in variation 1 of the first embodiment, a directivity pattern equivalent to that of comparative example 1 can be obtained while increasing the antenna gain.

<Variation 2 of Embodiment 1>
The antenna arrangement of the variation 2 of the present embodiment is similar to the antenna arrangement of the variation 1 of the embodiment. The antenna arrangement when the total number of antenna elements of the transmission array antenna 108c is three and the total number of antenna elements of the reception array antenna 202c is five will be described.

  FIG. 15 shows an example of an antenna arrangement according to variation 2 of the first embodiment. The first axis direction and the second axis direction shown in FIG. 15 are, for example, the horizontal direction and the vertical direction, respectively. The arrangement of the transmission array antenna 108c and the reception array antenna 202c constitutes the arrangement of the virtual reception array antenna VAA3.

15, the total number N _t of transmitting antenna elements is three, respectively, represented by Tx # 1 to TX # 3. Transmit antenna elements Tx # 1~Tx # 3 are equally spaced apart about the first axis direction at intervals D _t = 2 × d _H. Here, the basic interval d _H in the first axial direction is, for example, d _H = 0.5λ. The total number N _a of the receiving antenna elements is five, respectively, represented by Rx # 1~Rx # 5. Receive antenna elements Rx # 1~Rx # 5 is arranged in the first axial direction at an interval of _{D r = [5,3,3,5] × d} H. This corresponds to the case where n _r = [2,1,1,2].

  Also in Variation 2 of Embodiment 1, similarly to Variation 1, the aperture lengths of the antenna elements of the transmission array antenna 108c and the reception array antenna 202c are set in the first axial direction and the third axis with the point shown in FIG. It can be extended in two axial directions. Thus, a high antenna gain can be obtained while narrowing the beam width in the horizontal direction and the vertical direction. A sub-array antenna configuration may be used for each antenna element, and an array weight may be applied to the sub-array antenna element to suppress side lobes.

<Variation 3 of Embodiment 1>
The antenna arrangement of variation 3 of the present embodiment is similar to the antenna arrangement of variation 1 of the present embodiment. The antenna arrangement when the total number of antenna elements of the transmission array antenna 108d is three and the total number of antenna elements of the reception array antenna 202d is four will be described.

  FIG. 16 shows an example of an antenna arrangement according to variation 3 of the first embodiment. The first axis direction and the second axis direction shown in FIG. 16 are, for example, the horizontal direction and the vertical direction, respectively. The arrangement of the transmission array antenna 108d and the reception array antenna 202d constitutes the arrangement of the virtual reception array antenna VAA4.

16, the total number N _t of transmitting antenna elements is three, respectively, represented by Tx # 1 to TX # 3. Transmit antenna elements Tx # 1~Tx # 3 are equally spaced apart about the first axis direction at intervals D _t = 2 × d _H. Here, the basic interval d _H in the first axial direction is, for example, d _H = 0.5λ. The total number N _a of the receiving antenna elements is four, respectively, represented by Rx # 1~Rx # 4. Receive antenna elements Rx # 1~Rx # 4 is disposed in a first axial direction at an interval of _{D r = [5,3,5] × d} H. This corresponds to the case where n _r = [2,1,2].

  Also in Variation 3 of Embodiment 1, similarly to Variation 1, the aperture lengths of the antenna elements of the transmission array antenna 108d and the reception array antenna 202d are set in the first axial direction and in the first axial direction with the point shown in FIG. It can be extended in two axial directions. Thereby, the beam width in the horizontal and vertical directions can be reduced, and a high antenna gain can be obtained. A sub-array antenna configuration may be used for each antenna element, and an array weight may be applied to the sub-array antenna element to suppress side lobes.

<Variation 4 of Embodiment 1>
The antenna arrangement of variation 4 of the present embodiment is similar to the antenna arrangement of variation 3 of the present embodiment. A description will be given of an antenna arrangement in the case where the intervals between antenna elements are different between the transmission array antenna 108e and the reception array antenna 202e.

  FIG. 17 shows an example of an antenna arrangement according to variation 4 of the first embodiment. The first axis direction and the second axis direction shown in FIG. 17 are, for example, the horizontal direction and the vertical direction, respectively. The arrangement of the transmission array antenna 108e and the reception array antenna 202e constitutes the arrangement of the virtual reception array antenna VAA5.

17, the total number N _t of transmitting antenna elements is three, respectively, represented by Tx # 1 to TX # 3. Transmit antenna elements Tx # 1~Tx # 3 are equally spaced apart about the first axis direction at intervals D _t = d _H. Here, the basic interval d _H in the first axial direction is, for example, d _H = 0.5λ. The total number N _a of the receiving antenna elements is four, respectively, represented by Rx # 1~Rx # 4. Receive antenna elements Rx # 1~Rx # 4 is disposed in a first axial direction at an interval of _{D r = [3,2,3] × d} H. This corresponds to the case where n _r = [2,1,2].

  Also in Variation 4 of Embodiment 1, similarly to Variation 3, the aperture lengths of the antenna elements of the transmission array antenna 108e and the reception array antenna 202e are set in the first axial direction and the third axis with the point shown in FIG. It can be extended in two axial directions. As a result, a high antenna gain can be obtained while narrowing the beam width in the horizontal and vertical directions. A sub-array antenna configuration may be used for each antenna element, and an array weight may be applied to the sub-array antenna element to suppress side lobes.

  As shown in FIG. 17, in the virtual receiving array antenna VAA5, a virtual antenna formed by a transmitting antenna element Tx # 3 and a receiving antenna element Rx # 2 and a transmitting antenna element Tx # 1 and the virtual antenna configured by the receiving antenna element Rx # 3 are configured to overlap. Therefore, at the position of virtual antenna VA # 6, there are two received signals. The radar apparatus 10 may use one of the two received signals in the DOA estimation, use an average value thereof, or use the sum thereof. Note that there is no phase difference due to the angle of arrival between the two overlapping signals because the positions of the virtual receiving antennas overlap.

  Therefore, when the radar device 10 is a time-division multiplexed MIMO radar, the radar device 10 may perform Doppler analysis using two received signals received by overlapping virtual antennas. By reducing the transmission cycle of the signal analyzed by the Doppler analyzer 213 shown in FIG. 6, the maximum speed at which the Doppler analyzer 213 can analyze can be increased.

<Variation 5 of Embodiment 1>
The antenna arrangement of variation 5 of the present embodiment is similar to the antenna arrangement of variation 3 of the present embodiment. The antenna arrangement in the case where the intervals between antenna elements are different between the transmission array antenna 108f and the reception array antenna 202f will be described.

  FIG. 18 shows an example of an antenna arrangement according to variation 5 of the first embodiment. The first axis direction and the second axis direction shown in FIG. 18 are, for example, the horizontal direction and the vertical direction, respectively. The arrangement of the transmission array antenna 108f and the reception array antenna 202f constitutes the arrangement of the virtual reception array antenna VAA6.

18, the total number N _t of transmitting antenna elements is three, respectively, represented by Tx # 1 to TX # 3. Transmit antenna elements Tx # 1~Tx # 3 are equally spaced apart about the first axis direction at intervals D _t = 3 × d _H. Here, the basic interval d _H in the first axial direction is, for example, d _H = 0.5λ. The total number N _a of the receiving antenna elements is four, respectively, represented by Rx # 1~Rx # 4. Receive antenna elements Rx # 1~Rx # 4 is disposed in a first axial direction at an interval of _{D r = [7,4,7] × d} H. This corresponds to the case where n _r = [2,1,2].

  Also in Variation 5 of Embodiment 1, similarly to Variation 3, the aperture lengths of the antenna elements of the transmission array antenna 108f and the reception array antenna 202f are set in the first axial direction and in the first axial direction with the point shown in FIG. It can be extended in two axial directions. Thus, a high antenna gain can be obtained while narrowing the beam width in the horizontal direction and the vertical direction. A sub-array antenna configuration may be used for each antenna element, and an array weight may be applied to the sub-array antenna element to suppress side lobes.

  FIG. 19 shows an example of a directivity pattern by a one-dimensional beam by the virtual receiving array antenna VAA6 according to Variation 5 of the first embodiment. The directivity pattern shown in FIG. 19 is a directivity pattern formed in the first axis direction when the incoming wave to the receiving antenna arrives from the first axis direction at 0 degree (zenith).

  Variation 5 of Embodiment 1 is suitable for a case where the horizontal viewing angle (FOV) is narrow. Variation 5 of Embodiment 1 can be used, for example, in a long-distance radar having a horizontal viewing angle of about 30 degrees. By using the sub-array antenna configuration for each antenna element of the transmission array antenna 108f and the reception array antenna 202f, the directivity in the horizontal and vertical directions can be reduced.

  As shown in FIG. 19, in variation 5 of the first embodiment, side lobes of about -3.4 dB occur as compared with the main lobe. However, by using a sub-array antenna configuration for each antenna element and narrowing the directivity in the first axis direction, the influence of side lobes can be reduced. Further, a direction-of-arrival estimation method that is less affected by side lobes, such as a maximum likelihood estimation method, may be used.

  As described above, Variation 1, Variation 2, Variation 3, Variation 4, and Variation 5 have been described as examples of the antenna arrangement according to Embodiment 1.

Thus, in the first embodiment, the radar device 10 includes a radar transmitter 100 which are multiplexed and transmitted radar transmission signals from a plurality of transmit antenna elements # 1~ # N _t of the transmission array antenna 108, the radar transmission signal There comprises a reflected wave signal reflected at the target, the radar receiver 200 that receives using a plurality of receive antenna elements # 1~ # N _a transmission array antenna 202, a. Further, in this embodiment, arranging the transmitting antenna element # 1~ # N _t and receive antenna elements # 1~ # N _a, as described above.

  According to the first embodiment, the aperture lengths of the antenna elements of the transmission array antenna 108 and the reception array antenna 202 can be expanded by, for example, sub-arrays, thereby improving the antenna gain and improving the reception SNR of the reflected wave signal. it can. Further, according to the first embodiment, the occurrence of unnecessary grating lobes is suppressed, and the risk of erroneous detection by the MIMO radar can be reduced. Further, according to the first embodiment, a MIMO radar having a narrow main lobe width in a beam pattern formed by a virtual receiving array antenna can be configured.

  Note that a dummy antenna element may be provided for the transmitting antenna and the receiving antenna. Here, the dummy antenna element is an antenna that has a configuration physically similar to other antenna elements and is not used for transmitting and receiving radar signals. For example, a dummy antenna element may be provided between antenna elements or in a region outside the antenna element. The provision of the dummy antenna element has an effect of equalizing the influence of electrical characteristics such as radiation, impedance matching, and isolation of the antenna.

(Embodiment 2-2 dimensional arrangement)
The radar apparatus according to the present embodiment has the same basic configuration as radar apparatus 10 according to the first embodiment, and thus will be described with reference to FIG.

  In the present embodiment, by using a sub-array antenna configuration for each antenna element, the directivity gain of the antenna element is increased, the aperture length of the virtual receiving array antenna is increased in the two-dimensional direction, and the generation of unnecessary grating lobes is suppressed. To reduce the risk of erroneous detection and achieve a desired directivity pattern.

[Antenna Arrangement in Radar Apparatus 10]
In the second embodiment, the antenna arrangement in the two-dimensional direction, including the antenna arrangement of the transmission array antenna 108 and the reception array antenna 202 in the first embodiment, and the arrival direction estimation method using the antenna arrangement explain. By arranging the antenna elements in the two-dimensional direction, it is possible to estimate the two-dimensional direction of arrival.

FIG. 20 is a diagram illustrating an example of an antenna arrangement according to the second embodiment. The first axis direction and the second axis direction shown in FIG. 20 are, for example, the horizontal direction and the vertical direction, respectively. Incidentally, the interval delimited by the dashed vertical line in a first axial direction, represents a fundamental spacing d _H of the first axial direction. Further, the interval delimited by vertical dashed lines in a second axial direction, represents a fundamental spacing d _V in the second axial direction. In the following drawings, similar basic lines may sometimes indicate the basic intervals in the first axis direction and the second axis direction. In Figure 20, the total number N _t of transmitting antenna elements that constitute the transmission array antenna 108g is six. The total number N _a of the receiving antenna elements constituting the receiving array antenna 202g is eight, eight receiving antenna elements, respectively, represented by Rx # 1~Rx # 8. The total number of virtual antennas of the virtual receiving array antenna VAA7 composed of the transmitting antenna elements Tx # 1 to Tx # 6 and the receiving antenna elements Rx # 1 to Rx # 8 is 48, and VA # 1 to VA # 48, respectively. Is shown. Here, the first axis direction is orthogonal to the second axis direction. The basic interval d _{H in} the first axis direction is, for example, d _H = 0.5λ. The basic interval d _V in the second axis direction is, for example, d _V = 0.68λ.

20, the arrangement of transmitting antenna elements Tx # 1 to # 3 and receiving antenna elements Rx # 1 to # 4 is the same as that of variation 3 of the first embodiment. That is, the transmission antenna elements Tx # 1~Tx # 3 are equally spaced apart about the first axis direction at intervals D _t = d _H. The receiving antenna element Rx # 1~Rx # 4 is disposed in a first axial direction at an interval of _{D r = [3,2,3] × d} H. This corresponds to the case where n _r = [2,1,2]. Further, transmission antenna elements Tx # 4 to Tx # 6 are arranged similarly to transmission antenna elements Tx # 1 to Tx # 3. Further, reception antenna elements Rx # 5 to Rx # 8 are arranged in the same manner as reception antenna elements Rx # 1 to Rx # 4.

The arrangement of the transmitting antenna elements Tx # 4 to Tx # 6 and the receiving antenna elements Rx # 5 to Tx # 8 are respectively corresponding to the transmitting antenna elements Tx # 1 to Tx # 3 and the receiving antenna elements Rx # 1 to Rx # 4. Thus, they may be arranged shifted in the first axis direction and the second axis direction. For example, as shown in FIG. 20, the transmitting antenna elements Tx # 4~Tx # 6, respectively, transmit antenna element Tx # against 1 to TX # 3, distance d _H in a first axial direction, the second axially are staggered spacing d _V. The receiving antenna element Rx # 5~Rx # 8, respectively, relative to the receiving antenna elements Rx # 1~Rx # 4, distance d _H in a first axial direction, staggered spacing 2d _V in a second axial direction Placed.

  Each antenna element of the transmitting array antenna 108g and the receiving array antenna 202g is physically located at a position adjacent to the transmitting antenna elements Tx # 1 to Tx # 6 and the receiving antenna elements Rx # 1 to Rx # 8. The opening length may be enlarged to such an extent as not to interfere. The antenna gain can be improved by increasing the aperture length.

  Also in Embodiment 2, similarly to Embodiment 1, each antenna element of transmitting array antenna 108g and receiving array antenna 202g may be configured using a sub-array antenna configuration.

  FIG. 21 shows an example of the size of the antenna element according to the second embodiment. For example, as shown in FIG. 21, each antenna element may have a sub-array antenna configuration including four elements in the second axis direction. When the field of view (FOV) of the radar device 10 is wide in the horizontal direction and narrow in the vertical direction, the beam patterns of the antenna elements of the transmission array antenna 108g and the reception array antenna 202g are similarly wide and vertical in the horizontal direction. It is desirable that the direction be a narrow angle. Therefore, as shown in FIG. 10B, a sub-array antenna configuration in which sub-array antenna elements are arranged in the vertical direction is conceivable. As described above, it is desirable to use a sub-array antenna configuration that forms a beam pattern suitable for the viewing angle of the radar device 10 for each antenna element of the transmission array antenna 108g and the reception array antenna 202g.

  A sub-array antenna configuration may be used for each antenna element, and an array weight may be applied to the sub-array antenna element to suppress side lobes.

  FIG. 22A is an example of a directional pattern of a two-dimensional beam (main beam: horizontal 0 °, vertical 0 ° direction) by virtual receiving array antenna VAA7 according to Embodiment 2, and is an example of a cross-sectional view along the first axis direction. Is shown.

  FIG. 22B is an example of a directional pattern of a two-dimensional beam (main beam: horizontal 0 °, vertical 0 ° direction) by virtual reception array antenna VAA7 according to Embodiment 2, and is an example of a cross-sectional view along the second axis direction. Is shown.

  The characteristics of these directivity patterns will be described later with reference to FIGS. 24A and 24B.

  In the case of a time division multiplexed MIMO radar, all the antenna elements of the transmission array antenna 108g need not be multiplexed. For example, multiplexing may be performed on three transmission antenna elements Tx # 1 to Tx # 3 shown in FIG. As a result, the number of virtual reception arrays decreases, the angle estimation performance in the first axis direction (horizontal direction) can be maintained, and the number of multiplexed antennas can be reduced.

  In the case of a time-division multiplexed MIMO radar, the transmission cycle can be shortened with a decrease in the number of multiplexed antennas. Therefore, the maximum Doppler speed that can be analyzed by the Doppler analysis unit 213 can be increased. Therefore, compared to a configuration in which all antenna elements are multiplexed and signals are transmitted independently from the transmission antenna elements, a configuration suitable for high-speed object detection can be achieved.

Also, a beam may be formed using a plurality of antenna elements of the transmission array antenna 108g as one antenna element. For example, power is supplied to the transmission antenna elements Tx # 1 and Tx # 4 by controlling the phase, and the transmission antenna elements are used as one transmission antenna element. Similarly, the transmitting antenna elements Tx # 2 and Tx # 5 and the transmitting antenna elements Tx # 3 and Tx # 6 are controlled in phase and fed, and used as one transmitting antenna element. Thus, the phase center of which is arranged on the first axis at intervals of 2 × d _H, it can be treated as the sum of three transmit antenna elements.

  By forming a transmission beam by using a plurality of transmission antenna elements as one antenna element, the viewing angle in the first axis direction (horizontal direction) is reduced as compared with a case where signals are transmitted independently from each transmission antenna element. Although narrower, the gain in the front direction is improved. Further, as in the case where all the antenna elements are not multiplexed, the number of multiplexed transmission antenna elements is three. For example, in the case of a time-division multiplexed MIMO radar, the transmission cycle can be shortened by the small number of multiplexes, and the maximum Doppler speed that can be analyzed by the Doppler analysis unit 213 can be increased. Therefore, in the above-described example, the detection distance of the radar device 10 can be increased, and the performance of detecting the high-speed moving object by the radar device 10 can be improved, as compared with a configuration in which signals are transmitted independently from the transmission antenna elements. be able to.

<Comparative Example 2>
FIG. 23 is a diagram illustrating an example of an antenna arrangement according to a comparative example 2 of the second embodiment.

In Comparative Example 2, the transmitting antenna elements Tx # 1 to TX # 6 constituting the transmission array antenna 108h is the distance d _H in a first axial direction, at an interval of d _V in a second axial direction, arranged at regular intervals Is done. The receiving antenna element Rx # 1~Rx # 8 constituting the reception array antenna 202h at intervals of 3 × d _H in a first axial direction, at an interval of 2 × d _V in a second axial direction, at equal intervals Be placed. The total number of virtual antennas of the virtual receiving array antenna VAA8 constituted by the transmitting antenna elements Tx # 1 to Tx # 6 and the receiving antenna elements Rx # 1 to Rx # 8 is 48, and VA # 1 to VA # 48, respectively. Is shown. In virtual reception array antenna VAA8, 48 pieces of virtual antennas VA # 1~VA # 48 at intervals of d _H in a first axial direction, at an interval of d _V in a second axial direction, are arranged at regular intervals.

In Comparative Example 2, the transmitting antenna elements Tx # 1 to TX # 6, respectively, so as not to physically interfere with the adjacent antenna, the first axis direction and a second axial, respectively, d _H below and d _V It is required to have the following opening length. Therefore, transmission antenna elements Tx # 1 to Tx # 6 cannot all use the sub-array antenna configuration as shown in FIG. 21 and must be configured with a single antenna element. That is, in the second embodiment, a sub-array antenna configuration is used for one transmitting antenna element, but in Comparative Example 2, it is difficult to use a sub-array antenna configuration for one transmitting antenna element.

In Comparative Example 2, the receiving antenna elements Rx # 1~Rx # 8, respectively, in a first axial direction and second axial direction, respectively, consists of 3 × d _H below and 2 × d _V following aperture length In this case, it is possible to prevent physical interference with an adjacent antenna. Therefore, a sub-array antenna configuration may be used for each of reception antenna elements Rx # 1 to Rx # 8, and side lobes may be suppressed by applying an array weight to the sub-array antenna elements. However, in Comparative Example 2, the range in which the aperture length of the receiving antenna elements Rx # 1 to Rx # 8 in the second axial direction can be widened is smaller than in Embodiment 2.

  FIG. 24A is an example of a directional pattern of a two-dimensional beam (main beam: horizontal 0 °, vertical 0 ° direction) by virtual reception array antenna VAA7 according to Embodiment 2, and is an example of a cross-sectional view along the first axis direction. 7 shows a comparison with an example of a cross-sectional view along a first axis direction, which is a directivity pattern of a two-dimensional beam by a virtual reception array antenna VAA8 according to Comparative Example 2. FIG. 24B is an example of a cross-sectional view along the second axial direction, showing a directivity pattern of a two-dimensional beam (main beam: horizontal 0 °, vertical 0 ° direction) by virtual reception array antenna VAA7 according to Embodiment 2. 7 shows a comparison with an example of a cross-sectional view along the second axis direction, showing a directivity pattern of a two-dimensional beam by the virtual reception array antenna VAA8 according to Comparative Example 2.

  In the second embodiment, the same number of transmitting antenna elements and receiving antenna elements as in Comparative Example 2 are used. However, as shown in FIG. 24A, a beam having a narrower main lobe width can be formed by the configuration of Embodiment 2 as compared with the configuration of Comparative Example 2. Therefore, with the antenna arrangement of the second embodiment, a virtual reception array configuration having a higher resolution in the first axial direction (horizontal direction) than that of the second comparative example can be obtained.

  Further, as shown in FIG. 24B, the beam shape of the second embodiment is substantially the same as the beam shape of Comparative Example 2. However, in the second embodiment, compared to Comparative Example 2, the horizontal spacing between the phase centers of the transmitting antenna element and the receiving antenna element in the horizontal direction is larger, so that one antenna element of the transmitting array antenna 108h and the receiving array antenna 202h is used. The opening length can be configured to be wider in the horizontal direction. Therefore, with the antenna arrangement of the second embodiment, it is possible to obtain a directivity pattern having the same performance in the second axis direction (vertical direction) while increasing the antenna gain as compared with the comparative example 2.

<Variation 1 of Embodiment 2>
In variation 1 of the second embodiment, the antenna arrangement including the transmission array antenna 108 and the reception array antenna 202 of the first embodiment, the antenna arrangement arranged in a two-dimensional direction, and the arrival direction using the antenna arrangement The estimation method will be described. Also in the variation 1 of the second embodiment, as in the second embodiment, by arranging the antenna elements in the two-dimensional direction, it is possible to estimate the two-dimensional direction of arrival.

  FIG. 25A shows an example of an arrangement of a transmission array antenna 108i and a reception array antenna 202i according to Variation 1 of Embodiment 2.

In FIG. 25A, the total number Nt of the transmission antenna elements constituting the transmission array antenna 108i is six, and the six transmission antenna elements are indicated by Tx # 1 to Tx # 6, respectively. The total number N _a of the receiving antenna elements constituting the receiving array antenna 202i is eight, eight receiving antenna elements, respectively, represented by Rx # 1~Rx # 8. Here, the first axis direction is orthogonal to the second axis direction. The basic interval d _{H in} the first axis direction is, for example, d _H = 0.5λ. The basic interval d _V in the second axis direction is, for example, d _V = 0.68λ.

As shown in FIG. 25A, the arrangement of transmission antenna elements Tx # 1 to Tx # 6 is the same as the arrangement of transmission antenna elements Tx # 1 to Tx # 6 of the second embodiment. That is, the transmission antenna elements Tx # 1~Tx # 3 are equally spaced apart about the first axis direction at intervals D _t = d _H. Further, the transmitting antenna elements Tx # 4~Tx # 6, respectively, to the transmission antenna elements Tx # 1 to TX # 3, distance d _H in a first axial direction, staggered spacing d _V in a second axial direction Therefore, they are arranged in the same manner as the transmission antenna elements Tx # 1 to Tx # 3.

The arrangement of receiving antenna elements Rx # 3 to Rx # 6 is the same as the arrangement of receiving antenna elements Rx # 1 to Rx # 4 of Variation 3 of the first embodiment. That is, the reception antenna elements Rx # 3~Rx # 6 is disposed in a first axial direction at an interval of _{D r = [5,3,5] × d} H. This corresponds to the case where n _r = [2,1,2].

The receiving antenna element Rx # 1, Rx # 2 and Rx # 7, Rx # 8, respectively, receive antenna element Rx # 4, Rx # 5 the same interval, i.e., first at intervals of 3 × d _H It is arranged in the axial direction. Further, the arrangement of the receiving antenna elements Rx # 1, Rx # 2 and Rx # 7, Rx # 8 is shifted in the first axis direction and the second axis direction with respect to the receiving antenna elements Rx # 4, Rx # 5. It may be arranged. For example, as shown in FIG. 25A, the receiving antenna elements Rx # 1, Rx # 2, to the receiving antenna elements Rx # 4, Rx # 5, the first axial spacing d _H, the second axis direction -2d _V are offset from each other. On the other hand, the receiving antenna elements Rx # 7, Rx # 8, to the receiving antenna elements Rx # 4, Rx # 5, distance -d _H in a first axial direction, staggered spacing 2d _V in a second axial direction Be placed.

  The antenna elements of the transmission array antenna 108i and the reception array antenna 202i are adjacent to each other with the positions of the transmission antenna elements Tx # 1 to Tx # 6 and the reception antenna elements Rx # 1 to Rx # 8 shown in FIG. The aperture length may be increased to such an extent that it does not physically interfere with the antenna. The antenna gain can be improved by increasing the aperture length.

  FIG. 25B shows an example of the arrangement of the virtual reception array antenna VAA9 according to Variation 1 of Embodiment 2. The virtual reception array antenna VAA9 shown in FIG. 25B is a virtual reception array antenna based on the transmission array antenna 108i and the reception array antenna 202i shown in FIG. 25A. The total number of virtual antennas of the virtual reception array antenna VAA9 configured by the transmission antenna elements Tx # 1 to Tx # 6 of the transmission array antenna 108i and the reception antenna elements Rx # 1 to Rx # 8 of the reception array antenna 202i is 48, The 48 virtual antennas are indicated by VA # 1 to VA # 48, respectively.

  FIG. 26 shows an example of the size of the antenna element according to Variation 1 of the second embodiment. For example, as shown in FIG. 26, a sub-array antenna configuration including four elements in the second axis direction may be used for each antenna element. When the field of view (FOV) of the radar device 10 is wide in the horizontal direction and narrow in the vertical direction, the beam patterns of the antenna elements of the transmission array antenna 108i and the reception array antenna 202i are similarly wide and vertical in the horizontal direction. It is desirable that the direction be a narrow angle. Therefore, as shown in FIG. 10B, a sub-array antenna configuration in which the antenna elements are arranged in the vertical direction is conceivable. As described above, it is desirable to use a sub-array antenna configuration that forms a beam pattern suitable for the viewing angle of the radar device 10 for each antenna element of the transmission array antenna 108i and the reception array antenna 202i.

  A sub-array antenna configuration may be used for each antenna element, and an array weight may be applied to the sub-array antenna element to suppress side lobes.

  FIG. 27A is a directional pattern of a two-dimensional beam (main beam: horizontal 0 °, vertical 0 ° direction) by virtual reception array antenna VAA9 according to variation 1 of Embodiment 2 shown in FIG. 1 shows an example of a cross-sectional view along the line. FIG. 27B is a directional pattern of a two-dimensional beam (main beam: horizontal 0 °, vertical 0 ° direction) by virtual reception array antenna VAA9 according to Variation 1 of Embodiment 2, and is a cross section along the second axial direction. FIG.

  As shown in FIG. 27A, the directivity pattern of Variation 1 of Embodiment 2 has a wider main lobe width in the first axial direction (horizontal direction) than that of Embodiment 2 shown in FIG. 22A. Therefore, the performance of the angle estimation in the horizontal direction is better in the second embodiment than in the variation 1 of the second embodiment. On the other hand, as shown in FIG. 27B, the directivity pattern of Variation 1 of Embodiment 2 has a main lobe width in the second axial direction (vertical direction) different from that of Embodiment 2 shown in FIG. 22B. wide. Therefore, the performance of the angle estimation in the vertical direction is better in the variation 1 of the second embodiment than in the second embodiment.

  In the case of a time-division multiplexed MIMO radar, all the antenna elements of transmission array antenna 108 do not need to be multiplexed, as in the second embodiment. For example, three transmission antenna elements Tx # 1 to Tx # 3 shown in FIG. 25A may be multiplexed. Further, similarly to Embodiment 2, a beam may be formed using a plurality of antenna elements of transmission array antenna 108 as one antenna element.

For example, power is supplied to the transmitting antenna elements Tx # 1 and Tx # 4 by controlling the phase, and the transmitting antenna elements are used as one transmitting antenna. Similarly, the transmitting antenna elements Tx # 2 and Tx # 5 and the transmitting antenna elements Tx # 3 and Tx # 6 are controlled in phase and fed, and used as one transmitting antenna. Thus, the phase center of which is arranged on the first axis at intervals of 2 × d _H, it can be treated as a transmission antenna consisting of a total of three. With these configurations, the same effects as those of the second embodiment can be obtained in the variation 1 of the second embodiment.

<Variation 2 of Embodiment 2>
In the variation 2 of the second embodiment, the antenna arrangement including the transmission array antenna 108 and the reception array antenna 202 of the first embodiment, the antenna arrangement arranged in a two-dimensional direction, and the arrival direction using the antenna arrangement The estimation method will be described. Also in the variation 2 of the second embodiment, as in the second embodiment, by arranging the antenna elements in the two-dimensional direction, the two-dimensional direction of arrival can be estimated. Variation 2 of Embodiment 2 has the same number of antenna elements and a different antenna arrangement than Embodiment 2 and Variation 1 of Embodiment 2.

  As described above, since the variation 2 of the second embodiment has an antenna configuration that partially includes the antenna configuration of the variation 1 of the second embodiment, the same effect as that of the variation 1 of the second embodiment is obtained. Is obtained. Further, in the variation 2 of the second embodiment, the effect of improving the resolution can be obtained.

  FIG. 28A shows an example of the arrangement of transmission array antenna 108j and reception array antenna 202j according to Variation 2 of Embodiment 2.

In Figure 28A, the total number N _t of transmitting antenna elements that constitute the transmission array antenna 108j is six, six transmit antenna elements, respectively, represented by Tx # 1 to TX # 6. The total number N _a of the receiving antenna elements constituting the receiving array antenna 202j is eight, eight receiving antenna elements, respectively, represented by Rx # 1~Rx # 8. Here, the first axis direction is orthogonal to the second axis direction. The basic interval d _{H in} the first axis direction is, for example, d _H = 0.5λ. The basic interval d _V in the second axis direction is, for example, d _V = 0.68λ.

As shown in FIG. 28A, the arrangement of transmission antenna elements Tx # 1 to Tx # 3 and the arrangement of transmission antenna elements Tx # 4 to Tx # 6 are respectively the same as those of variation 3 of the first embodiment. This is the same arrangement as the arrangement of Tx # 1 to Tx # 3. That is, the transmitting antenna element Tx # 1 to TX # 3, the transmitting antenna element Tx # 1 to TX # 3, respectively, are arranged at equal intervals in a first axial direction at an interval of D _t = 2 × d _H . Further, the transmitting antenna elements Tx # 4~Tx # 6, respectively, to the transmission antenna elements Tx # 1 to TX # 3, distance d _H in a first axial direction, staggered spacing d _V in a second axial direction Placed.

As shown in FIG. 28A, the arrangement of receiving antenna elements Rx # 4 to Rx # 7 is the same as the arrangement of receiving antenna elements Rx # 1 to Rx # 4 of Variation 3 of the first embodiment. is there. That is, the reception antenna elements Rx # 4~Rx # 7 is arranged in the first axial direction at an interval of _{D r = [5,3,5] × d} H. This corresponds to the case where n _r = [2,1,2]. Further, the receiving antenna elements Rx # 1 to Rx # 3 and Rx # 8 are arranged at intervals of d _V on the second axis coordinates different from the second axis coordinates where the receiving antenna elements Rx # 4 to Rx # 7 are arranged. Is done. The receiving antenna elements Rx # 1 and Rx # 8 are arranged on the same first axis coordinate, and Rx # 2, Rx # 3, Rx # 5, Rx # 1 and Rx # 8 have different first axis coordinates, respectively. above, it is arranged at intervals of d _H.

  The antenna elements of the transmission array antenna 108j and the reception array antenna 202j are adjacent antennas with the positions of the transmission antenna elements Tx # 1 to Tx # 6 and the reception antenna elements Rx # 1 to Rx # 8 shown in FIG. The opening length may be increased to such an extent that physical interference does not occur. The antenna gain can be improved by increasing the aperture length. Furthermore, a sub-array antenna configuration may be used for each antenna element, and an array weight may be applied to the sub-array antenna element to suppress side lobes.

  FIG. 28B shows an example of the arrangement of the virtual receiving array antenna VAA10 according to Variation 2 of Embodiment 2. The virtual receiving array antenna VAA10 shown in FIG. 28B is a virtual receiving array antenna based on the transmitting array antenna 108j and the receiving array antenna 202j shown in FIG. 28A. The total number of virtual antennas of the virtual reception array antenna VAA10 configured by the transmission antenna elements Tx # 1 to Tx # 6 of the transmission array antenna 108j and the reception antenna elements Rx # 1 to Rx # 8 of the reception array antenna 202j is 48, The 48 virtual antennas are indicated by VA # 1 to VA # 48, respectively.

  FIG. 29A shows an example of the size of the antenna element according to Variation 2 of Embodiment 2. FIG. 29B illustrates an example in which the size of the antenna element according to Variation 2 of Embodiment 2 is different for each antenna element.

  For example, as shown in FIG. 29A, a sub-array antenna configuration including four elements in the second axis direction may be used for each antenna element. When the field of view (FOV) of the radar device 10 is wide in the horizontal direction and narrow in the vertical direction, the beam patterns of the antenna elements of the transmission array antenna 108j and the reception array antenna 202j are similarly wide and vertical in the horizontal direction. It is desirable that the direction be a narrow angle. Therefore, as shown in FIG. 10B, a sub-array antenna configuration in which the antenna elements are arranged in the vertical direction is conceivable. As described above, it is desirable that each antenna element of the transmission array antenna 108j and the reception array antenna 202j has a sub-array antenna configuration that forms a beam pattern suitable for the viewing angle of the radar device 10.

  In FIG. 29A, all the antenna elements use the same sub-array antenna configuration. Further, the configuration may be changed for each antenna element within a range that does not interfere with an adjacent antenna. For example, as shown in FIG. 29B, the transmission antenna elements Tx # 1 to Tx # 6 may be configured by a sub-array of two elements in the first axis direction and four elements in the second axis direction, and the reception antenna element Rx # Each of # 4, # 6, and # 7 may be configured with a sub-array of three elements in the first axis direction and eight elements in the second axis direction. Comparing the configuration shown in FIG. 29A with the configuration shown in FIG. 29B, in the configuration shown in FIG. 29A, since the beam pattern of each antenna element is wide, a wide viewing angle (FOV) can be secured, In the configuration shown in FIG. 29B, the antenna gain in the front direction is improved, and the SNR is improved.

  FIG. 30A is a directivity pattern of a two-dimensional beam (main beam: horizontal 0 °, vertical 0 ° direction) by virtual reception array antenna VAA10 according to Variation 2 of Embodiment 2 shown in FIG. 1 shows an example of a cross-sectional view along the line. FIG. 30B is a directional pattern of a two-dimensional beam (main beam: horizontal 0 °, vertical 0 ° direction) by virtual reception array antenna VAA10 according to Variation 2 of Embodiment 2, and is a cross section along the second axis direction. FIG.

  The directivity pattern shown in FIG. 30A has the same main lobe width in the first axial direction (horizontal direction) as compared to Variation 1 of Embodiment 2 shown in FIG. 27A. Further, the directivity pattern shown in FIG. 30B has a narrower main lobe width in the second axis direction (vertical direction) than the variation 1 of the second embodiment shown in FIG. 27B. Therefore, when the configuration of the variation 2 of the second embodiment is used, the performance of the vertical angle estimation of the radar device 10 can be improved as compared with the configuration of the variation 1 of the first embodiment.

  By combining the configuration according to Variation 2 of Embodiment 2 with a method of independently estimating the directions of arrival in the first axis direction and the second axis direction, a higher side lobe level as compared with Variation 1 of Embodiment 2 is achieved. The probability of erroneous detection that can be caused can be reduced, and the accuracy of arrival direction estimation can be improved. For example, the virtual receiving array antenna VAA10 shown in FIG. 28B accurately estimates the direction of arrival in the first axis direction and the second axis direction, and uses a two-dimensional beam for an angle exceeding a certain threshold. Estimate the direction of arrival. As a result, the probability of erroneous detection by the radar device 10 can be reduced, and the accuracy of arrival direction estimation can be improved. Further, the amount of calculation for arrival direction estimation can be reduced.

  In the case of a time-division multiplexed MIMO radar, all element antennas of the transmission array antenna 108j do not have to be multiplexed, similarly to the first variation of the second embodiment. For example, three transmission antenna elements Tx # 4 to Tx # 6 shown in FIG. 28A may be multiplexed. Further, as in Embodiment 2, a beam may be formed using a plurality of antenna elements of transmission array antenna 108j as one antenna element. With these configurations, the same effects as in the second embodiment can be obtained in the variation 2 of the second embodiment.

<Variation 3 of Embodiment 2>
Variation 3 of the second embodiment includes the antenna arrangement of the transmission array antenna 108 and the reception array antenna 202 of the first embodiment, the antenna arrangement arranged in a two-dimensional direction, and the arrival direction using the antenna arrangement. The estimation method will be described. Also in the variation 3 of the second embodiment, as in the second embodiment, by arranging the antenna elements in the two-dimensional direction, it is possible to estimate the two-dimensional direction of arrival.

  The antenna arrangement of Variation 3 of the present embodiment is an antenna arrangement in which the antenna arrangement of Variation 2 of Embodiment 2 is partially changed. In addition to the effect of Variation 2 of Embodiment 2, the effect of improving the maximum Doppler speed that can be analyzed by Doppler analyzer 213 in the case of time-division MIMO is obtained.

  FIG. 31A shows an example of the arrangement of transmission array antenna 108k and reception array antenna 202k according to variation 3 of the second embodiment.

In Figure 31A, the total number N _t of transmitting antenna elements that constitute the transmission array antenna 108k is six, six transmit antenna elements, respectively, represented by Tx # 1 to TX # 6. The total number N _a of the receiving antenna elements constituting the receiving array antenna 202k is eight, eight receiving antenna elements, respectively, represented by Rx # 1~Rx # 8. Here, the first axis direction is orthogonal to the second axis direction. The basic interval d _{H in} the first axis direction is, for example, d _H = 0.5λ. The basic interval d _V in the second axis direction is, for example, d _V = 0.68λ.

The antenna arrangement shown in FIG. 31A is the same as the antenna arrangement of variation 2 of the second embodiment shown in FIG. 28A except for the arrangement of transmitting antenna element Tx # 3. In other words, in the third variation of the second embodiment, the transmission antenna element Tx # 3 of the transmission antenna elements Tx # 1 to Tx # 6 is shifted in the first axial direction and the second axial direction based on the variation 2 of the second embodiment. biaxially, anomalously each d _H, are staggered by d _V.

  Here, each of the antenna elements of the transmission array antenna 108k and the reception array antenna 202k has a beam width narrowed by expanding the aperture length as shown in FIG. 10 around the position of the antenna element shown in FIG. 31A as a phase center. , A high antenna gain can be obtained. The aperture length of each antenna element may be increased by increasing the size of each antenna element so as not to physically interfere with an adjacent antenna. Furthermore, a sub-array antenna configuration may be used for each antenna element, and an array weight may be applied to the sub-array antenna element to suppress side lobes.

  FIG. 31B shows an example of an arrangement of a virtual receiving array antenna according to variation 3 of the second embodiment. The virtual receiving array antenna VAA11 shown in FIG. 31B is a virtual receiving array antenna based on the transmitting array antenna 108k and the receiving array antenna 202k shown in FIG. 31A. The total number of virtual antennas of the virtual receiving array antenna VAA11 configured by the transmitting antenna elements Tx # 1 to Tx # 6 of the transmitting array antenna 108k and the receiving antenna elements Rx # 1 to Rx # 8 of the receiving array antenna 202k is 47, The 47 virtual antennas are indicated by VA # 1 to VA # 47, respectively.

  As shown in FIG. 31B, in the virtual receiving array antenna VA # 6, at the position of the virtual antenna VA # 6, a virtual antenna constituted by the transmitting antenna element Tx # 3 and the receiving antenna element Rx # 2, and the transmitting antenna The element Tx # 2 and the virtual antenna configured by the receiving antenna element Rx # 3 are configured to overlap. Therefore, at the position of virtual antenna VA # 6, there are two received signals. The radar apparatus 10 may use one of the two received signals in the DOA estimation, use an average value thereof, or use the sum thereof. Note that there is no phase difference due to the angle of arrival between the two overlapping signals because the positions of the virtual receiving antennas overlap.

  As shown in Variation 4 of Embodiment 1, the maximum speed at which Doppler analysis section 213 can analyze can be increased by using the signals of these overlapping virtual reception array antennas.

  FIG. 32A shows an example of the size of the antenna element according to Variation 3 of Embodiment 2. FIG. 32B illustrates an example in which the size of the antenna element according to Variation 3 of Embodiment 2 is different for each antenna element.

  For example, as shown in FIG. 32A, a sub-array antenna configuration including four elements in the second axis direction may be used for each antenna element. When the field of view (FOV) of the radar device 10 is wide in the horizontal direction and narrow in the vertical direction, the beam patterns of the antenna elements of the transmission array antenna 108k and the reception array antenna 202k are similarly wide-angle and vertical in the horizontal direction. It is desirable that the direction be a narrow angle. Therefore, as shown in FIG. 10B, a sub-array antenna configuration in which the antenna elements are arranged in the vertical direction is conceivable. As described above, it is desirable to use a sub-array antenna configuration that forms a beam pattern suitable for the viewing angle of the radar device 10 for each antenna element of the transmission array antenna 108 and the reception array antenna 202.

  In FIG. 32A, the same sub-array antenna configuration is used for all antenna elements. However, the configuration may be changed for each antenna element within a range that does not interfere with an adjacent antenna. For example, as shown in FIG. 32B, the transmission antenna elements Tx # 1 to Tx # 6 may be configured by a sub-array of two elements in the first axis direction and four elements in the second axis direction, and the reception antenna element Rx # Each of # 4, # 6, and # 7 may be configured with a sub-array of three elements in the first axis direction and eight elements in the second axis direction. Comparing the configuration shown in FIG. 32A with the configuration shown in FIG. 32B, in the configuration shown in FIG. 32A, since the beam pattern of each antenna element is wide, a wide viewing angle (FOV) can be secured. In the configuration shown in FIG. 32B, the antenna gain in the front direction is improved, and the SNR is improved.

  FIG. 33A shows a directivity pattern of a two-dimensional beam (main beam: horizontal 0 °, vertical 0 ° direction) by virtual reception array antenna VAA11 according to variation 3 of Embodiment 2 shown in FIG. 1 shows an example of a cross-sectional view along the line. FIG. 33B shows a directivity pattern of a two-dimensional beam (main beam: horizontal 0 °, vertical 0 ° direction) by virtual reception array antenna VAA11 according to variation 3 of Embodiment 2 shown in FIG. 1 shows an example of a cross-sectional view along the line.

  As shown in FIGS. 33A and 33B, the directivity pattern of variation 3 of the second embodiment is similar to the variation 2 and directivity pattern of the second embodiment shown in FIGS. 30A and 30B, respectively. The directivity pattern of Variation 3 of Embodiment 2 has a main lobe width smaller than the directivity pattern of Variation 2 of Embodiment 2 by about 0.5 degrees in the first axis direction and in the second axis direction. It is about 0.4 degrees larger. In addition, the directivity pattern of Variation 3 of Embodiment 2 has a maximum sidelobe level lower by about 1.3 dB than the directivity pattern of Variation 2 of Embodiment 2. Therefore, using the configuration of Variation 3 of Embodiment 2 can reduce the probability of erroneous detection as compared to Variation 2 of Embodiment 2.

  As described above in the description of the variation 2 of the second embodiment, by combining the configuration according to the variation 3 of the second embodiment with the method of independently performing the arrival direction estimation in the first axis direction and the second axis direction, The probability of erroneous detection can be reduced, and the accuracy of arrival direction estimation can be improved. For example, by using the virtual receiving array antenna VAA11 shown in FIG. 31B, the direction of arrival is precisely estimated in the first axis direction and the second axis direction, and a more accurate arrival direction using a two-dimensional beam for an angle exceeding a certain threshold value. Make an estimate. As a result, the probability of erroneous detection by the radar device 10 can be reduced, and the accuracy of arrival direction estimation can be improved. In addition, the amount of calculation required for DOA estimation can be reduced.

  In the case of a time-division multiplexed MIMO radar, all the antenna elements of the transmission array antenna 108k do not need to be multiplexed, similarly to Variation 1 and Variation 2 of the second embodiment. For example, three transmission antenna elements Tx # 4 to Tx # 6 shown in FIG. 31A may be multiplexed. Further, similarly to Embodiment 2, a beam may be formed using a plurality of antenna elements of transmission array antenna 108k as one antenna element. With these configurations, the same effects as in the second embodiment can be obtained in the variation 3 of the second embodiment.

  As shown in FIG. 31B, in the virtual receiving array antenna VAA11, at the position of the virtual antenna VA # 6, the virtual antenna formed by the transmitting antenna element Tx # 3 and the receiving antenna element Rx # 2, and the transmitting antenna element Tx # 2 and a virtual antenna configured by the receiving antenna element Rx # 3 are configured to overlap. Therefore, at the position of virtual antenna VA # 6, there are two received signals. The radar apparatus 10 may use one of the two received signals in the DOA estimation, use an average value thereof, or use the sum thereof. Note that there is no phase difference due to the angle of arrival between the two overlapping signals because the positions of the virtual receiving antennas overlap.

  In the case of a time division multiplexed MIMO radar, Doppler analysis may be performed using these two overlapping signals. By reducing the transmission cycle of the signal analyzed by the Doppler analyzer 213, the maximum speed that can be analyzed by the Doppler analyzer 213 shown in FIG. 6 can be increased.

  As described above, as an example of the antenna arrangement according to Embodiment 2, in addition to Embodiment 2, Variation 1, Variation 2, and Variation 3 have been described.

Thus, in the second embodiment, the radar device 10 includes a plurality of transmit antenna elements Tx # 1~Tx # N _t radar transmitter 100 which are multiplexed and transmitted radar signal transmitted from the transmitting array antenna 108, radar the reflected wave signal reflected in the transmission signal is the target comprises a, a radar receiver 200 that receives using a plurality of receive antenna elements Rx # 1~Rx # N _a transmission array antenna 202. Further, in the second embodiment, the transmitting antenna element Tx # 1~Tx # N _t and receive antenna elements Rx # 1~Rx # N _a containing structure of transmission array antenna and the reception array antenna of the first embodiment 2 Place in the dimension direction.

  This makes it possible to increase the size of each antenna element and improve the antenna gain of the transmission array antenna 108 and the reception array antenna 202 by, for example, forming a sub-array.

  According to the second embodiment, the effect of the first embodiment is exerted, and a MIMO radar capable of two-dimensional direction-of-arrival estimation can be configured.

  In addition, a dummy antenna element may be provided in the radar device 10 in addition to the transmission antenna and the reception antenna. Here, the dummy antenna element is an antenna whose constituent antenna element has a configuration physically similar to other antenna elements and is not used for transmission and reception of radar signals by the radar device 10. For example, a dummy antenna element may be provided between antenna elements or in a region outside the antenna element. The provision of the dummy antenna element has an effect of equalizing the influence of electrical characteristics such as radiation, impedance matching, and isolation of the antenna.

<Embodiment 3>
The radar device according to the third embodiment has the same basic configuration as the radar device 10 according to the first embodiment, and thus will be described with reference to FIG.

  In the third embodiment, by using a sub-array antenna configuration for each antenna element, the directivity gain of the antenna element is increased, the aperture length of the virtual receiving array antenna is increased in the two-dimensional direction, and the generation of unnecessary grating lobes is suppressed. Accordingly, the radar device 10 that can reduce the risk of erroneous detection and realize a desired directivity pattern is provided.

[Antenna Arrangement in Radar Apparatus 10]
In Embodiment 3, transmission array antennas 108 according to Embodiments 1 and 2 are referred to as one “transmission antenna group”, and reception array antenna 202 according to Embodiments 1 and 2 is referred to as one. One “receiving antenna group”. In the following description, the transmission array antenna and the reception array antenna may be collectively described as a “transmission / reception array antenna”.

  In the third embodiment, as in the other embodiments, each antenna is enlarged to a size that does not physically interfere, the antenna gain is improved, and a large number of transmission antenna groups or reception antenna groups are used. The aperture length of the virtual receiving array antenna can be enlarged, and the resolution can be improved.

  FIG. 34 is a diagram showing an example of the arrangement of the transmitting and receiving array antennas and the arrangement of the virtual receiving array antenna according to the third embodiment. FIG. 34 shows an example in which the transmission array antenna 108a in FIG. 11 is used as one transmission antenna group, and the transmission array antenna 108L in which two groups are arranged in the first axis direction is used as the extended virtual reception array antenna VAA12. obtain.

The aperture length of the transmission antenna group is D _T1 in the first axis direction, the aperture length of the reception antenna group is D _{R1 in} the first axis direction, and the interval between the transmission antenna groups is D _R1 + d on the first axis. _H. As a result, as shown in FIG. 34, the virtual receiving array antenna VAA12 has a configuration in which two virtual receiving array antenna groups each including the virtual receiving array antenna VAA1 shown in FIG. is there.

  FIG. 35A is a diagram showing another example of the arrangement of the transmission / reception array antenna according to the third embodiment. FIG. 35B is a diagram showing another example of the arrangement of the virtual receiving array antenna according to the third embodiment. As an example of the two-dimensional arrangement, FIGS. 35A and 35B show an example in which a plurality of transmission antenna groups and a plurality of reception antenna groups are arranged based on the configuration of the antenna arrangement shown in FIG. In FIG. 35A, four transmission antenna groups are arranged in two rows in the first axis direction and two rows in the second axis direction, and four reception antenna groups are arranged in two rows in the first axis direction and two rows in the second axis direction. Be placed. Considering the opening length of each antenna group in the first axis direction, the opening length in the second axis direction, and the interval between the antenna groups, the transmission array antenna 108m and the reception array antenna 202m are used, so that the virtual reception array antenna of FIG. VAA13 can be obtained.

Here, the aperture length of the transmitting antenna group is D _T1 in the first axis direction and D _{T2 in} the second axis direction, and the aperture length of the receiving antenna group is D _R1 in the first axis direction and D _T1 in the second axis direction. _R2 , the interval between the transmitting antenna groups is D _R1 + d _H on the first axis, 2 × _DR 2 in the second axis direction, and the interval between the receiving antenna groups is D _T1 + D _{R1 in} the first axis direction. -d _H, and 2 × _{D R2} in the second axial direction. As a result, as shown in FIG. 35B, the virtual receiving array antenna VAA13 includes four virtual receiving array antenna groups each including the virtual receiving array antenna VAA7 shown in FIG. This is a configuration in which four rows are arranged in the axial direction.

  FIG. 36A is a diagram showing another example of the arrangement of the transmission / reception array antenna according to the third embodiment. FIG. 36B is a diagram showing another example of the arrangement of the virtual reception array antenna according to the third embodiment. FIG. 36A, which is another example of the two-dimensional arrangement, shows a case where the transmission array antenna 108i is one transmission antenna group and the reception array antenna 202i is one reception antenna in the antenna arrangement of variation 1 of the second embodiment shown in FIG. 25A. An example in which a plurality of transmission antenna groups and a plurality of reception antenna groups are arranged as a group will be described. The transmission array antenna 108n has a configuration in which a total of four sets of transmission antenna groups are arranged in two rows in the first axis direction and two rows in the second axis direction. The reception array antenna 202n has one set of reception antenna groups. Configuration.

Here, aperture length of the receiving antenna groups, and _{D R1} in a first axial direction, and _{D R2} in the second axial direction transmission antenna group, the distance _D R1 + _{d H} to the first axis, the second axis _Are arranged at intervals of DR2. Thus, virtual reception array antenna VAA14 shown in FIG. 36B has a configuration in which four virtual reception array antenna groups each including virtual reception array antenna VAA9 shown in FIG. 25B as one group are arranged.

  FIG. 37A is a diagram showing another example of the arrangement of the transmission / reception array antenna according to the third embodiment. FIG. 37B is a diagram showing another example of the arrangement of the virtual receiving array antenna according to the third embodiment. FIG. 37A, which is another example of the two-dimensional arrangement, shows that, in the antenna arrangement of variation 1 shown in FIG. 25A, the transmission array antenna 108i is one transmission antenna group, and the reception array antenna 202i is one reception antenna group. An example in which a transmitting antenna group and two receiving antenna groups are arranged is shown. In the transmission array antenna 108p, a total of four sets of transmission antenna groups are arranged in two rows in the first axis direction and two rows in the second axis direction. In the receiving array antenna 202p, two sets of receiving antenna groups are arranged.

Here, the aperture length of each reception antenna group, D _R1 in a first axial _direction, and D _R2 in the second axial direction, the distance D _{R1 +} d _H each transmit antenna group to the first axis, the second axis _Are arranged at intervals of 2 × _DR2 . The second reception antenna group is arranged to 6d _H offset in a first axial direction, are arranged at intervals D _R2 in the second axial direction. Therefore, a receiving antenna element Rx # 3 of the first receiving antenna group, and the second reception antenna group of receive antenna elements Rx # 3, disposed 6d _H offset in a first axial direction, the first The receiving antenna elements Rx # 7 and Rx # 8 of the receiving antenna group and the receiving antenna elements Rx # 1 and Rx # 2 of the second receiving antenna group are arranged at the same position on the second axis. As a result, the virtual receiving array antenna VAA15 has the configuration shown in FIG. 37B. The virtual reception array antenna VAA15 has a configuration in which eight virtual reception array antenna groups each including the virtual reception array antenna VAA9 illustrated in FIG. 25B as one group are arranged.

  Here, a case has been described where a plurality of transmission antenna groups and a plurality of reception antenna groups are provided based on the arrangement of the array antennas described in Embodiment 1 and Embodiment 2. However, the present invention is not limited to this, and the present invention is not limited thereto. Similar effects can be obtained when a plurality of transmitting antenna groups or receiving antenna groups are provided based on an array antenna arrangement other than the antenna arrangement. Further, the interval between the transmitting antenna group and the receiving antenna group is not limited to the above-described example.

<Embodiment 4>
FIG. 38 is a block diagram showing an example of a configuration of a radar device 10a according to the fourth embodiment. The configuration of the radar device 10 according to the present disclosure is not limited to the configuration illustrated in FIG. For example, the configuration of the radar device 10a shown in FIG. 38 may be used. 38, the same components as those in FIGS. 1 and 2 are denoted by the same reference numerals, and description thereof will be omitted. In FIG. 38, the configuration of the radar receiving unit 200 is the same as that of FIG. 6, and thus the detailed configuration is omitted.

In the radar apparatus 10 shown in FIG. 1, for example, in the radar transmitting section 100 of FIG. 2, the control section 400 adjusts the output levels of the plurality of transmission amplifying sections 107 by the transmission control signal, thereby transmitting the radar transmission signal. The output transmission amplifier 107 is selectively switched. The radar transmission signal generation unit 101 repeatedly outputs a radar transmission signal in the radar transmission cycle _Tr based on the code control signal from the control unit 400 for each predetermined radar transmission cycle _Tr . On the other hand, in the radar apparatus 10a shown in FIG. 38, in the radar transmission section 100a, the output (radar transmission signal) from the radar transmission signal generation section 101 is subjected to transmission radio processing by the transmission radio section 107a, and switching control is performed. In accordance with the switching control signal from unit 410, transmission switching unit 109 selectively switches the output of transmission radio unit 107a to any one of transmission antennas 108. Note that, unlike the control unit 400 in FIG. 2, the radar transmission signal generation unit 101 does not receive a switching control signal from the switching control unit 410.

  With the configuration of the radar device 10a shown in FIG. 38, the same effect as in the other embodiments can be obtained.

<Embodiment 5>
In each of the first to third embodiments, a case has been described in which the radar transmitting unit 100 or 100a uses a pulse compression radar that transmits a pulse train by performing phase modulation or amplitude modulation, but the modulation method is not limited to this. For example, the present disclosure is also applicable to a radar system using a frequency-modulated pulse wave such as a chirp pulse.

  FIG. 39 is a block diagram illustrating an example of a configuration of a radar device 10b according to the fifth embodiment. FIG. 40 is a diagram showing an example of a chirp pulse used by the radar device 10b according to the fifth embodiment. FIG. 39 shows an example of a configuration diagram of a radar device 10b when a radar system using chirp pulses (for example, fast chirp modulation) is applied. 39, the same components as those in FIGS. 1, 2, 6, and 38 are denoted by the same reference numerals, and description thereof will be omitted.

  First, transmission processing in the radar transmission unit 100b will be described. In the radar transmission unit 100b, the radar transmission signal generation unit 401 has a modulation signal generation unit 402 and a VCO (Voltage Controlled Oscillator) 403.

The modulation signal generator 402 periodically generates a sawtooth-shaped modulation signal, for example, as shown in FIG. Here, _{let the} radar transmission period be _Tr .

VCO 403 outputs a frequency modulation signal (in other words, a frequency chirp signal) to transmission radio section 107a based on the radar transmission signal output from modulation signal generation section 402. The frequency modulation signal is amplified in transmission radio section 107a, and radiated into space from transmission antenna 108 switched in transmission switching section 109 in accordance with the switching control signal output from switching control section 410. For example, in each of the transmit antennas 108 of the N _t from the first transmitting antenna 108, the radar transmission signal is transmitted at a transmission interval of _{N p (= N t × T} r) cycle.

Directional coupling unit 404 takes out a part of the signal of the frequency-modulated signal, and outputs the respective reception radio section 501 of the antenna element system processor 201-1～N _a radar receiver 200b (mixer 502).

Next, a reception process in the radar receiver 200b will be described. In each antenna element system processor 201-1～N _a radar receiving section 200b, a mixer unit 502 included in the reception radio section 501, on the received reflected wave signal, a frequency modulated signal (direction a transmission signal The signal input from the sexual coupling unit 404) is mixed, and the mixed signal passes through the LPF 503 included in the reception radio unit 501. Thereby, a beat signal having a beat frequency corresponding to the delay time of the reflected wave signal is extracted as an output of the LPF 503. For example, as shown in FIG. 40, the difference frequency between the frequency of the transmission signal (transmission frequency modulation wave) and the frequency of the reception signal (reception frequency modulation wave) is obtained as the beat frequency.

  The signal output from LPF 503 is converted into discrete sample data by A / D conversion section 208b of signal processing section 207b.

An R-FFT (Range-Fast Fourier Transform) unit 504 performs an FFT process on N _data discrete sample data obtained in a predetermined time range (range gate) for each transmission cycle _Tr . Thus, the signal processing unit 207b outputs a frequency spectrum in which a peak appears at a beat frequency corresponding to the delay time of the reflected wave signal (radar reflected wave). Thereby, the distance to the target can be calculated. In the FFT processing, the R-FFT unit 504 may multiply, for example, a window function coefficient such as a Han window or a Hamming window. By using the window function coefficient, it is possible to suppress a side lobe occurring around a peak appearing in the beat frequency in the frequency spectrum.

Here, the beat frequency spectrum response output from the R-FFT unit 504 of the z-th signal processing unit 207b and obtained by transmitting the M-th chirp pulse is represented by AC_RFT _z (f _b , M). Here, f _b is an index number (bin number) of the FFT, and f _b = 0,..., N _data / 2. As the frequency index f _b is small, the delay time of the reflected wave signal is small (in other words, the short distance between the target) shows the beat frequency.

The output switching unit 212 in the z-th signal processing unit 207b is, for example, based on the switching control signal input from the switching control unit 410, for each radar transmission cycle _Tr , similarly to the radar device 10a illustrated in FIG. The output of the R-FFT unit 504 is selectively switched to one of the N _t Doppler analyzers 213 and output.

Hereinafter, as an example, the switching control signal in the M-th radar transmission cycle _Tr [M] is represented by information of N _t bits [bit ₁ (M), bit ₂ (M), ..., bit _Nt (M)]. . For example, in the switching control signal of the M-th radar transmission cycle T _r [M], at the N _D-th bit bit _ND (M) (where either N _D = 1 to N _t) is '1' some cases, the output switching unit 212 selects the first N _D th Doppler analysis unit 213 (other words when ON). On the other hand, in the switching control signal of the M-th radar transmission cycle T _r [M], if the N _D-th bit bit _ND (M) is "0", the output switching unit 212, the N _D th The Doppler analyzer 213 is not selected (in other words, OFF). Output switching section 212 outputs a signal input from R-FFT section 504 to selected Doppler analysis section 213.

As described above, the selection of each Doppler analyzer 213 is sequentially turned ON at N _p (= N _t × T _r ) cycles. The switching control signal repeats the above content _Nc times.

Note that the transmission start time of the transmission signal in each transmission radio section 107a does not have to be synchronized with the cycle _Tr . For example, in each transmission radio section 107a, a transmission delay delta ₁ which different transmission start time, delta _2, ..., provided delta _Nt, may start the transmission of the radar transmission signal.

The z-th (z = 1,..., N _a ) -th signal processing unit 207b includes N _t Doppler analysis units 213.

  The Doppler analysis unit 213 performs Doppler analysis on the output from the output switching unit 212 for each beat frequency index fb.

For example, when _Nc is a power of 2, fast Fourier transform (FFT) processing can be applied in Doppler analysis.

The w-th output in the N _D th Doppler analysis unit 213 of the z-th signal processing unit 207b, as shown in equation (19), the Doppler frequency response of the Doppler frequency index f _u in the beat frequency index f _b FT_CI _z ^(ND) (f _b , f _u , w). It is to be N _D = 1 to N _t, a ND = 1 to N _t, w is an integer of 1 or more. Further, j is an imaginary unit, and z = 1 to N _a.

  The processing of the direction estimating unit 214 after the signal processing unit 207b is, for example, an operation in which the discrete time k described in the first embodiment is replaced with the beat frequency index fb, and thus detailed description is omitted.

  With the above configuration and operation, the same effects as those of the first to third embodiments can also be obtained in the fifth embodiment.

The above-mentioned beat frequency index fb may be converted into distance information and output. Expression (20) may be used to convert the beat frequency index fb into distance information R (f _b ). Here, B _w represents the frequency modulation band width of the frequency chirp signals generated by frequency modulation, C ₀ denotes the speed of light.

  The embodiment according to the example of the present disclosure has been described above. In addition, you may implement combining the said embodiment and the operation | movement concerning each variation suitably.

Further, in the above embodiment, the case where the basic intervals d _H = 0.5λ and d _V = 0.5λ has been described as an example, but the present invention is not limited to these values. For example, base distance d _H and d _V is 0.5 wavelength or more and may be the following values one wavelength. Further, in the above embodiment, the notation “antenna group” may be replaced with another notation such as “antenna element group”.

  In the radar devices 10, 10a, and 10b (see, for example, FIGS. 1, 38, and 39), the radar transmitting unit 100 and the radar receiving unit 200 may be individually arranged at physically separated locations. . In the radar receiving unit 200 (see, for example, FIGS. 1, 38, and 39), the direction estimating unit 214 and other components may be individually arranged at physically separated locations.

  Although not shown, the radar devices 10, 10a, and 10b include, for example, a CPU (Central Processing Unit), a recording medium such as a ROM (Read Only Memory) storing a control program, and a working memory such as a RAM (Random Access Memory). Having. In this case, the function of each unit described above is realized by the CPU executing the control program. However, the hardware configuration of the radar devices 10, 10a, 10b is not limited to such an example. For example, each functional unit of the radar devices 10, 10a, and 10b may be realized as an integrated circuit (IC). Each functional unit may be individually formed into one chip, or may be formed into one chip so as to include a part or the whole thereof. Although not shown, the radar devices 10, 10a, and 10b can be mounted on moving objects such as vehicles (automobiles, motorcycles, bicycles, construction vehicles, forklifts), trains, and ships. , A roadside device (Road Side Unit).

  Although various embodiments have been described with reference to the drawings, it is needless to say that the present disclosure is not limited to such examples. It is clear that those skilled in the art can conceive various changes or modifications within the scope of the claims, and these naturally belong to the technical scope of the present disclosure. I understand. Further, each component in the above embodiment may be arbitrarily combined without departing from the spirit of the disclosure.

  In each of the above embodiments, the present disclosure has been described with respect to an example in which the present disclosure is configured using hardware, but the present disclosure can also be realized by software in cooperation with hardware.

  In the above description, the notation “...” Used for each component is “... Circuit”, “... Device”, “... Unit”, or “. It may be replaced with another notation such as "module".

  Each functional block used in the description of each of the above embodiments is typically realized as an LSI which is an integrated circuit. The integrated circuit may control each functional block used in the description of the above embodiment, and may have an input and an output. These may be individually integrated into one chip, or may be integrated into one chip so as to include some or all of them. Here, the LSI is used, but it may be called an IC, a system LSI, a super LSI, or an ultra LSI depending on the degree of integration.

  Further, the method of circuit integration is not limited to LSI, and may be realized using a dedicated circuit or a general-purpose processor. After the LSI is manufactured, a programmable FPGA (Field Programmable Gate Array) or a reconfigurable processor that can reconfigure the connection or setting of circuit cells inside the LSI may be used.

  Furthermore, if an integrated circuit technology that replaces the LSI appears due to the advancement of the semiconductor technology or another technology derived therefrom, the functional blocks may be integrated using the technology. For example, the application of biotechnology is possible.

ここで、ｄ_Ｈは第１の基本間隔を示し、ｎ_ｔは１以上の整数、
前記第２の間隔D_r(n)は、式（１ｂ）を満たし、

ここで、Ｎ_ａは、1≦n＜Ｎ_ａ-1を満たす整数であり、
n_rは、式（１ｃ）を満たす。

The radar device of the present disclosure includes a radar transmission circuit that transmits a radar signal from a transmission array antenna, and a radar reception circuit that receives a reflected wave signal from the reception array antenna, the radar signal being reflected at a target, one transmission array antenna and the reception array antenna includes a first antenna element group phase center of the m antenna elements are arranged at equal intervals in the first interval D _t along the first axis direction ( m is an integer of 1 or more), the other of the transmission array antenna and the receiving array antenna, (n + 1) pieces of phase center of the antenna element is along said first axial second distance D _r (n ) a second group of antenna elements which are arranged in (n is an integer of 1 or more), the first distance D _t satisfies the formula (1a),

Here, d _H indicates a first basic interval, _nt is an integer of 1 or more,
The second interval D _r (n) satisfies equation (1b),

Here, _{N a} is an integer satisfying 1 ≦ n _{<N a} -1,
n _r satisfies equation (1c).

  In the radar device according to an embodiment of the present disclosure, the first basic interval is equal to or greater than 0.5 wavelength and equal to or less than 0.8 wavelength.

  In the radar device according to the present disclosure, at least one of the transmission array antenna and the reception array antenna includes a plurality of sub-array elements.

  In the radar device according to the present disclosure, one of the transmission array antenna and the reception array antenna duplicates the first antenna element group at a third interval along a second axis direction orthogonal to the first axis direction. A third antenna element group disposed, wherein the third interval is an integral multiple of a second basic interval, and the second basic interval is 0.5 wavelength or more and 0.8 wavelength or less. The other of the transmitting array antenna and the receiving array antenna includes a fourth antenna element group in which the second antenna element group is duplicately arranged at a fourth interval along the second axis direction, The fourth interval is an integral multiple of the second basic interval.

In the radar device according to an embodiment of the present disclosure, one of the transmission array antenna and the reception array antenna connects the first antenna element group and the third antenna element group at a fifth interval along the first axis direction. When the fifth antenna element group includes a fifth antenna element group that is duplicated and arranged, and the opening length of the first antenna element group is D _T1 and the opening length of the second antenna element group is D _R1 , the fifth interval is , A value obtained by adding a basic interval d _H to the aperture length D _R1 of the second antenna element group, and the other of the transmitting array antenna and the receiving array antenna has a sixth interval along the first axial direction. The sixth antenna element group includes the sixth antenna element group in which the second antenna element group and the fourth antenna element group are duplicated and arranged, and the sixth interval is the opening length D _{T1 of} the first antenna element group. And the first Is a value obtained by subtracting the base distance d _H from the sum of the aperture length D _R1 of the antenna element group.

  A moving object according to the present disclosure includes the radar device according to the present disclosure.

  A stationary object according to the present disclosure includes the radar device according to the present disclosure.

  The present disclosure is suitable as a radar device that detects a wide angle range.

10, 10a, 10b Radar devices 100, 100a, 100b Radar transmitters 101, 101a, 401 Radar transmission signal generator 102 Code generator 103 Modulator 104 LPF
105 Transmission frequency conversion unit 106 Power divider 107 Transmission amplification unit 107a Transmission radio unit 108 Transmission array antenna 109 Transmission switching unit 111 Code storage unit 112 DA conversion unit 200 Radar reception unit 201 Antenna element system processing unit 202 Reception array antenna 203 Reception radio Unit 204 amplifier 205 frequency converter 206 quadrature detector 207 signal processing unit 208, 209 AD conversion unit 210 correlation operation unit 211 addition unit 212 output switching unit 213 Doppler analysis unit 214 direction estimation unit 300 reference signal generation unit 400 control unit 402 modulation Signal generator 403 VCO
404 Directional coupling unit 410 Switching control unit 501 Wireless reception unit 502 Mixer unit 503 LPF
504 R-FFT section

Claims (7)

A radar transmission circuit for transmitting a radar signal from a transmission array antenna,
A radar receiving circuit that receives a reflected wave signal from the receiving array antenna, wherein the radar signal is reflected by a target;
With
Wherein one of the transmission array antenna and the reception array antenna includes a first antenna element group phase center of the m antenna elements are arranged at equal intervals in the first interval D _t along the first axis direction (M is an integer of 1 or more),
The other of the transmitting array antenna and the receiving array antenna is a second array in which phase centers of (n + 1) antenna elements are arranged at a second interval _Dr (n) along the first axis direction. Including an antenna element group (n is an integer of 1 or more),
The first distance _{D t} satisfies the formula (1),

Here, d _H indicates a first basic interval, _nt is an integer of 1 or more,
The second interval D _r (n) satisfies equation (2),

Here, N _a is an integer satisfying 1 ≦ n <N _a -1,
n _r satisfies equation (3),

Radar equipment. The first basic interval is 0.5 wavelength or more and 0.8 wavelength or less,
The radar device according to claim 1. At least one of the transmission array antenna and the reception array antenna includes a plurality of sub-array elements,
The radar device according to claim 1. One of the transmitting array antenna and the receiving array antenna is a third antenna in which the first antenna element group is duplicately arranged at a third interval along a second axis direction orthogonal to the first axis direction. Including element group,
The third interval is an integral multiple of the second basic interval,
The second basic interval is not less than 0.5 wavelength and not more than 0.8 wavelength,
The other of the transmission array antenna and the reception array antenna includes a fourth antenna element group in which the second antenna element group is duplicately arranged at a fourth interval along the second axis direction,
The fourth interval is an integer multiple of the second basic interval.
The radar device according to claim 1. One of the transmission array antenna and the reception array antenna has a fifth interval along the first axis direction, and the first antenna element group and the third antenna element group are duplicately arranged. Including an antenna element group,
When the opening length of the first antenna element group is D _T1 and the opening length of the second antenna element group is D _R1 ,
The fifth interval is the second value obtained by adding the base distance d _H in aperture length D _R1 of the antenna element group,
The other of the transmission array antenna and the reception array antenna has the sixth antenna element group and the fourth antenna element group duplicately arranged at a sixth interval along the first axis direction. Including an antenna element group,
The distance between the sixth is the first value obtained by subtracting the base distance d _H from the sum of the aperture length D _R1 of the first group of antenna elements and aperture length D _T1 of the antenna element group,
The radar device according to claim 4.   A moving object equipped with the radar device according to claim 1.   A stationary object equipped with the radar device according to claim 1.

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