JP7249546B2 - radar equipment - Google Patents

Description

The present disclosure relates to radar equipment.

2. Description of the Related Art In recent years, studies have been made on radar devices using short-wavelength radar transmission signals including microwaves or millimeter waves that can provide high resolution. Further, in order to improve outdoor safety, there is a demand for the development of a radar device (wide-angle radar device) that detects objects (targets) including pedestrians in a wide-angle range in addition to vehicles.

In addition, as a radar device, in addition to the reception branch, the transmission branch is also equipped with a plurality of antennas (array antennas), and a configuration that performs beam scanning by signal processing using the transmission and reception array antennas (MIMO (Multiple Input Multiple Output) radar) ) has been proposed (see, for example, Non-Patent Document 1).

In MIMO radar, a virtual receiving array antenna (hereinafter referred to as a virtual receiving array) equal to the product of the number of transmitting antenna elements and the number of receiving antenna elements is created by devising the placement of antenna elements in the transmitting and receiving array antennas. Configurable. This has the effect of increasing the effective aperture length of the array antenna with a small number of elements.

In addition to one-dimensional scanning in the vertical or horizontal direction, MIMO radar can also be applied when three-dimensional positioning is performed by beam scanning in two dimensions in the vertical and horizontal directions (for example, Patent Document 1, Non See Patent Document 1).

Japanese Patent Publication No. 2017-534881

P. P. Vaidyanathan, P. Pal, Chun-Yang Chen, "MIMO radar with broadband waveforms: Smearing filter banks and 2D virtual arrays," IEEE Asilomar Conference on Signals, Systems and Computers, pp.188 -192, 2008. Direction-of-arrival estimation using signal subspace modeling, Cadzow.J.A., Aerospace and Electronic Systems, IEEE Transactions on Volume: 28 , Issue: 1 Publication Year: 1992, Page(s): 64-79

One aspect of the present disclosure contributes to providing a radar device capable of three-dimensional positioning, which suppresses sidelobes and secures high resolution along the horizontal direction.

A radar apparatus according to an aspect of the present disclosure includes a radar transmission unit that transmits a radar signal from a transmission array antenna, and a radar reception unit that receives a reflected wave signal of the radar signal reflected by a target from a reception array antenna. one of the transmitting array antenna and the receiving array antenna includes a plurality of first antennas having phase centers arranged along a first axis direction, the plurality of first antennas having phase centers antennas arranged at a first integer multiple of the first spacing; and antennas having phase centers arranged at a second integer multiple of the first spacing, wherein the second integer multiple is the Different from the first integer multiple, the other of the transmitting array antenna and the receiving array antenna has a phase center arranged in a second axis direction different from the first axis direction at an integer multiple of a second interval. and a plurality of third antennas whose phase centers are arranged in the second axis direction at an integral multiple of the third spacing, wherein the second axis of the plurality of third antennas The synthetic aperture length in the direction of the plurality of second antennas is wider than the synthetic aperture length in the second axis direction of the plurality of second antennas, and the plurality of second antennas has a phase center in the first axis direction and the plurality of the Arranged at intervals equal to the synthetic aperture length of the phase center of the first antenna, the radar transmission unit is capable of switching between transmission by the plurality of second antennas and transmission by the plurality of third antennas take.

These generic or specific aspects may be realized by systems, methods, integrated circuits, computer programs, or recording media, and any of the systems, devices, methods, integrated circuits, computer programs and recording media may be implemented in any combination.

According to one aspect of the present disclosure, one aspect of the present disclosure contributes to providing a radar device capable of three-dimensional positioning that suppresses side lobes and secures high resolution along the horizontal direction.

Further advantages and advantages of one aspect of the present disclosure will be apparent from the specification and drawings. Such advantages and/or advantages are provided by the several embodiments and features described in the specification and drawings, respectively, but not necessarily all to obtain one or more of the same features. No need.

1 is a block diagram showing an example of a configuration of a radar device according to Embodiment 1; FIG. 1 is a block diagram showing an example of a configuration of a radar transmission unit according to Embodiment 1; FIG. A diagram showing an example of a radar transmission signal according to Embodiment 1 A diagram showing an example of a time-division switching operation of transmission antennas by the control unit according to Embodiment 1 4 is a block diagram showing an example of another configuration of the radar transmission signal generator according to Embodiment 1. FIG. 1 is a block diagram showing an example of the configuration of a radar receiver according to Embodiment 1; FIG. A diagram showing an example of the transmission timing of the radar transmission signal and the measurement range of the radar device according to the first embodiment. FIG. 4 is a diagram showing a three-dimensional coordinate system used for explaining the operation of the direction estimation unit according to Embodiment 1; FIG. 10 is a diagram showing arrangement example 1 of receiving antennas of the receiving array antenna according to Embodiment 1 FIG. 10 is a diagram showing arrangement example 1 of receiving antennas of the receiving array antenna according to Embodiment 1 FIG. 11 shows arrangement example 1 of the transmitting antennas of the transmitting array antenna according to Embodiment 1 A diagram showing the arrangement of virtual reception arrays according to Arrangement Example 1 FIG. 4 is a diagram showing the arrangement of receiving antennas of a receiving array antenna according to Comparative Example 1; FIG. 4 is a diagram showing the arrangement of transmitting antennas of a transmitting array antenna according to Comparative Example 1; FIG. 10 is a diagram showing the arrangement of virtual reception arrays according to Comparative Example 1; Cross-sectional view along the first axis direction at 0 degrees in the second axis direction of the two-dimensional beams according to Arrangement Example 1 and Comparative Example 1 FIG. 11 is a diagram showing the arrangement of virtual reception arrays according to Comparative Example 2; FIG. 10 is a diagram showing arrangement example 2 of receiving antennas of the receiving array antenna according to arrangement example 2 of Embodiment 1; A diagram showing the arrangement of virtual reception arrays according to arrangement example 2 Cross-sectional view along the first axis direction at 0 degrees in the second axis direction of the two-dimensional beams according to Arrangement Example 1 and Arrangement Example 2 FIG. 13 shows arrangement example 3 of the transmitting antennas of the transmitting array antenna according to Embodiment 2 FIG. 11 is a diagram showing the arrangement of virtual reception arrays according to arrangement example 3; FIG. 11 is a diagram showing an arrangement of virtual reception arrays according to Comparative Example 3; Cross-sectional view along the first axis direction at 0 degrees in the second axis direction of the two-dimensional beams according to Arrangement Example 3 and Comparative Example 3 FIG. 4 shows arrangement example 4 of the transmitting antennas of the transmitting array antenna according to Embodiment 2 Block diagram showing an example of the configuration of a radar receiver according to Embodiment 3 FIG. 4 shows arrangement example 4 of the transmitting antennas of the transmitting array antenna according to Embodiment 3 An example of arrangement of antenna elements of a transmission array antenna according to Arrangement Example 4 A diagram showing an example of time-division switching control of the first antenna group and the second antenna group according to Embodiment 3

For example, as a radar device, a pulse radar device that repeatedly transmits pulse waves is known. The signal received by the wide-angle pulse radar that detects vehicles/pedestrians in a wide-angle range is a mixture of multiple reflected waves from a target (e.g. vehicle) at a short distance and a target (e.g. pedestrian) at a long distance. signal. For this reason, (1) in the radar transmission unit, a configuration for transmitting a pulse wave or a pulse-modulated wave having autocorrelation characteristics (hereinafter referred to as low-range sidelobe characteristics) with low range sidelobes has been studied, and (2) In the radar receiver, a configuration having a wide reception dynamic range is being studied.

As the configuration of the wide-angle radar device, there are the following two configurations.

The first configuration uses a directional beam with a narrow angle (a beam width of about several degrees) to scan a pulsed wave or modulated wave mechanically or electronically to transmit a radar wave, thereby achieving a narrow-angle directional beam. In this configuration, a reflected wave is received using a polar beam. In this configuration, the number of scans is increased to obtain high resolution, so the followability to a target moving at high speed is degraded.

In the second configuration, in the receiving branch, an array antenna consisting of multiple antennas (multiple antenna elements) receives the reflected waves, and the arrival of the reflected waves is detected by a signal processing algorithm based on the reception phase difference with respect to the antenna element spacing. This configuration uses a method of estimating angles (Direction of Arrival (DOA) estimation). In this configuration, even if the scanning interval of the transmission beam in the transmission branch is thinned out, the arrival angle can be estimated in the reception branch, so the scanning time can be shortened, and the tracking can be performed as compared with the first configuration. improve sexuality. For example, direction-of-arrival estimation methods include Fourier transform based on matrix operation, Capon method and LP (Linear Prediction) method based on inverse matrix operation, or MUSIC (Multiple Signal Classification) and ESPRIT (Estimation of Signal Parameters) based on eigenvalue operation. via Rotational Invariance Techniques).

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

Furthermore, in MIMO radar, by devising the layout of the antenna elements in the transmission and reception array antennas, it is possible to configure a virtual reception array antenna (virtual reception array) equal to the product of the number of transmission antenna elements and the number of reception antenna elements at maximum. . As a result, it is possible to obtain the channel response indicated by the product of the number of transmitting antenna elements and the number of receiving antenna elements. The angle resolution can be improved by virtually enlarging the length.

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

When a single antenna is used, compared with the case of using a sub-array, the antenna has a wider directivity, 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 subarray is used, compared to the case of using a single antenna, one subarray includes a plurality of antenna elements, so the physical size of the antenna becomes larger, and the main beam direction becomes larger. Antenna gain can be increased. Specifically, the physical size of the subarray is equal to or larger than the wavelength of the radio frequency (carrier frequency) of the transmission signal.

In addition to vertical or horizontal one-dimensional scanning, the MIMO radar can also be applied to vertical and horizontal two-dimensional beam scanning (see, for example, Patent Document 1, Non-Patent Document 1). For example, in a MIMO radar capable of two-dimensional beam scanning for long distances used in in-vehicle applications, in addition to high horizontal resolution equivalent to that of a MIMO radar that performs one-dimensional beam scanning in the horizontal direction, vertical angle estimation ability is required.

However, the number of antenna elements in the transmission/reception branch may be restricted in order to reduce the size and cost of the MIMO radar. For example, if there is a constraint of about four transmitting antenna elements/about four receiving antenna elements, the aperture lengths in the vertical and horizontal directions are restricted in the planar virtual reception array by the MIMO radar. Aperture length limitations reduce horizontal and horizontal resolution.

For example, in a long-distance MIMO radar capable of two-dimensional beam scanning for in-vehicle applications, in addition to high horizontal resolution equivalent to that of a MIMO radar that performs one-dimensional beam scanning in the horizontal direction, vertical Angle estimation ability is required. However, if there are restrictions on the number of antenna elements, the aperture length is restricted compared to MIMO radars that perform one-dimensional beam scanning. Due to aperture length limitations, horizontal resolution is lower than that of MIMO radars that perform one-dimensional beam scanning.

Moreover, in order to realize a MIMO radar with a reduced probability of false detection, it is desirable that the virtual receiving array has a configuration in which the side lobes of the beams formed are low.

(Embodiment 1)
One aspect of the present disclosure configures a MIMO radar capable of three-dimensional positioning that suppresses deterioration of horizontal angle separation performance compared to a MIMO radar that performs one-dimensional beam scanning and has added vertical angle estimation capability. be able to.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In addition, in the embodiments, the same constituent elements are denoted by the same reference numerals, and redundant description thereof will be omitted.

Before explaining the arrangement of a plurality of transmitting antennas (transmitting sub-arrays) and a plurality of receiving antennas (receiving sub-arrays), the configuration of the radar apparatus will be described. Specifically, in the transmission branch of the radar device, multiple transmission antennas are switched in a time division manner to transmit different time division multiplexed radar transmission signals, and in the reception branch, each transmission signal is separated and reception processing is performed. The configuration of the MIMO radar to be used will be described.

Note that the configuration of the radar device is not limited to transmitting different time-division multiplexed radar transmission signals. For example, radar transmissions may be frequency division multiplexed or code division multiplexed instead of time division multiplexed. That is, the transmission branch may transmit different frequency-division-multiplexed radar transmission signals from a plurality of transmission antennas, and the reception branch may separate each transmission signal for reception processing. Similarly, the configuration of the radar apparatus may be such that a transmission branch transmits a code-division-multiplexed radar transmission signal from a plurality of transmission antennas, and a reception branch performs reception processing.

In addition, the embodiment described below is an example, and the present disclosure is not limited to the following embodiment.

[Configuration of radar device 10]
FIG. 1 is a block diagram showing an example configuration of a radar device 10 according to the present disclosure.

The radar apparatus 10 includes a radar transmission section (also referred to as transmission branch or radar transmission circuit) 100, a radar reception section (also referred to as reception branch or radar reception circuit) 200, a reference signal generation section (reference signal generation circuit) 300, and a control unit (control circuit) 400 .

The radar transmission unit 100 generates a high-frequency (radio frequency) radar signal (radar transmission signal) based on the reference signal received from the reference signal generation unit 300 . Radar transmission section 100 then switches the plurality of transmission antenna elements #1 to #Nt in a time division manner to transmit radar transmission signals.

The radar receiver 200 receives a reflected wave signal, which is a radar transmission signal reflected by a target (not shown), using a plurality of receiving antenna elements #1 to #Na. The radar receiver 200 performs processing in synchronization with the radar transmitter 100 by performing the following processing operations using the reference signal received from the reference signal generator 300 . The radar receiver 200 performs signal processing on reflected wave signals received by the receiving antenna elements #1 to #Na, and at least detects the presence or absence of a target or estimates its direction. A target is an object to be detected by the radar device 10, and includes, for example, a vehicle (including two-wheeled, three-wheeled, and four-wheeled vehicles) 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 generation section 300 supplies the reference signal to the radar transmission section 100 and the radar reception section 200 to synchronize the processing of the radar transmission section 100 and the radar reception section 200 .

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

[Configuration of radar transmission unit 100]
FIG. 2 is a block diagram showing an example of the configuration of the radar transmission section 100 according to the present disclosure.

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 amplifier circuit) 107 and a transmission array antenna 108 .

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

The radar transmission signal generator 101 generates a timing clock (clock signal) 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 generating section 101 repeatedly outputs the radar transmission signal at the radar transmission period Tr based on the code control signal from the control section 100 for each predetermined radar transmission period Tr.

A radar transmission signal is represented by y(k _t ,M)=I(k _T ,M)+jQ(k _t ,M). where j represents the imaginary unit, k represents discrete time, and M represents the ordinal number of the radar transmission period. Also, 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 discrete time k _T in the M-th radar transmission cycle. , and quadrature components, respectively.

Radar transmission signal generation section 101 includes code generation section (code generation circuit) 102 , modulation section (modulation circuit) 103 , and LPF (Low Pass Filter) 104 .

Based on the code control signal for each radar transmission cycle Tr, the code generation unit 102 generates a code a _n (M) (n=1, . . . , L) ( pulse code). For the code a _n (M) generated in the code generating section 102, a pulse code that provides low-range sidelobe characteristics is used. Examples of code sequences include Barer codes, M-sequence codes, and Gold codes. Note that the codes a _n (M) generated by the code generation unit 102 may be the same code or codes containing different codes.

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

LPF 104 outputs signal components below a predetermined band limit in the modulated signal output from modulation section 103 to transmission frequency conversion section 105 as a baseband radar transmission signal.

The transmission frequency converter 105 frequency-converts the 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 divides the radio frequency band radar transmission signal output from transmission frequency conversion section 105 into Nt pieces and outputs the divided signals to respective transmission amplification sections 107 .

The transmission amplifying section 107 (107-1 to 107-Nt) amplifies the output radar transmission signal to a predetermined level based on the transmission control signal for each radar transmission period Tr instructed by the control section 400, and outputs the signal. or turn off the transmission output.

The transmit array antenna 108 has Nt transmit antenna elements #1 to #Nt (108-1 to 108-Nt). Each transmission antenna element #1 to #Nt is connected to individual transmission amplifiers 107-1 to 107-Nt, and transmits radar transmission signals output from individual transmission amplifiers 107-1 to 107-Nt. do.

FIG. 3 is a diagram illustrating an example of a radar transmission signal according to the present disclosure;

In each radar transmission period Tr, a pulse code sequence is transmitted during the code transmission section Tw, and the remaining section (Tr-Tw) is a no-signal section. A code length L pulse code sequence is included in the code transmission section Tw. One code includes L sub-pulses. In addition, Nr (=No×L) samples are included in each code transmission interval Tw by performing pulse modulation using No samples per sub-pulse. Nu samples are included in a no-signal period (Tr-Tw) in the radar transmission period Tr.

FIG. 4 shows an example of time-division switching operation of each of the transmitting antenna elements #1 to #Nt by the control section 400 according to the present disclosure.

In FIG. 4, the control unit 400 controls a control signal (code control signal, transmission control signal) to the radar transmission unit 100 . Further, the control unit 400 sets the transmission output period of each transmission sub-array to (Tr×Nb), and performs the switching operation of the transmission output period of all the transmission sub-arrays (Tr×Np)=(Tr×Nb×Nt) Nc times. Repeat control. Further, the radar receiving unit 200, which will be described later, performs positioning processing based on the switching operation of the control unit 400. FIG.

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. It outputs a transmission control signal instructing to turn off the transmission output to the transmission amplifier sections 107-2 to 107-Nt not connected to the transmission antenna element #1.

Similarly, when transmitting a radar transmission signal from transmission antenna element #2, control section 400 instructs 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, control section 400 sequentially performs similar control on transmitting antenna elements #3 to #Nt. The output switching operation of the radar transmission signal by the control unit 400 has been described above.

[Other Configurations of Radar Transmission Unit 100]
FIG. 5 is a block diagram showing an example of another configuration of the radar transmission signal generator 101a according to the present disclosure.

The radar transmitter 100 may include a radar transmission signal generator 101a shown in FIG. 5 instead of the radar transmission signal generator 101. FIG. Radar transmission signal generation section 101a does not have code generation section 102, modulation section 103 and LPF 104 shown in FIG. conversion circuit) 112.

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

The DA conversion unit 112 converts the code sequence (digital signal) output from the code storage unit 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 receiver 200 according to Embodiments 1 and 2. As shown in FIG.

The radar receiving unit 200 has a receiving array antenna 202, Na antenna system processing units (antenna system processing circuits) 201 (201-1 to 201-Na), and a direction estimation unit (direction estimation circuit) 214. .

The receiving array antenna 202 has Na receiving antenna elements #1 to #Na (202-1 to 202-Na). The Na receiving antenna elements 202-1 to 202-Na receive reflected wave signals, which are radar transmission signals reflected by reflecting objects including measurement targets (objects), and respectively correspond to the received reflected wave signals. It is output as a received signal to the antenna system processing units 201-1 to 201-Na.

Each antenna system processing section 201 (201-1 to 201-Na) has a reception radio section (reception radio circuit) 203 and a signal processing section (signal processing circuit) 207. FIG. 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 section 203 has an amplifier section (amplifier circuit) 204 , a frequency converter (frequency converter circuit) 205 , and a quadrature detector (quadrature detector circuit) 206 . Specifically, in the z-th receiving radio section 203, the amplifier 204 amplifies the received signal received from the z-th receiving antenna element #z to a predetermined level. where z=1,...,Nr. Next, the frequency converter 205 frequency-converts the received signal in the high frequency band to the baseband band. The quadrature detector 206 then converts the baseband received signal into a baseband received signal 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 calculation unit (correlation calculation circuit) 210, and an addition unit (addition circuit ) 211, an output switching unit (output switching circuit) 212, and Nt Doppler analysis units (Doppler analysis circuits) 213-1 to 213-Nt.

First AD converter 208 receives the I signal from quadrature detector 206 . The first AD converter 208 converts the I signal into digital data by sampling the baseband signal including the I signal at discrete times.

Second AD converter 209 receives the Q signal from quadrature detector 206 . The second AD converter 209 converts the Q signal into digital data by sampling the baseband signal including the Q signal at discrete times.

Here, in the sampling of the first AD converter 208 and the second AD converter 209, Ns discrete samples are performed per time Tp (=Tw/L) of one subpulse in the radar transmission signal. That is, the number of oversamples per subpulse is Ns.

FIG. 7 shows an example of the transmission timing of the radar transmission signal and the measurement range of the radar device 10 according to the present disclosure.

In the following description, using the I signal I _z (k, M) and the Q signal Q _z (k, M), the M-th A baseband received signal at a discrete time k of a radar transmission period Tr[M] is expressed as a complex number signal x _z (k, M)=I _z (k, M)+jQ _z (k, M). In the following description, the discrete time k is based on the start timing of the radar transmission cycle (Tr) (k=1), and the signal processing unit 207 uses k =(N _r +N _u )N _s /N _o are measured periodically. That is, k=1,...,(N _r +N _u )N _s /N _o . where j is the imaginary unit.

式（１）において、アスタリスク（*）は複素共役演算子を表す。 In the z-th signal processing unit 207, the correlation calculation unit 210 receives discrete sample values x _z (k,M) from the first AD conversion unit 208 and the second AD conversion unit 209 for each radar transmission period Tr. and a pulse code a _n (M) of code length L (where z=1, . . . , Na, n=1, . For example, the correlation calculator 210 performs a sliding correlation calculation between the discrete sample value x _z (k,M) and the pulse code a _n (M). For example, the correlation calculation value AC _z (k,M) of the sliding correlation calculation at the discrete time k in the Mth radar transmission cycle Tr[M] is calculated based on Equation (1).

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

_{Correlation calculation} section 210 performs correlation _calculation over a period of k=1, _.

Note that the correlation calculation unit 210 is not limited to performing the correlation calculation for k=1, . . . , (N _r +N _u )N _s /N _o . Depending on the range, the measurement range (ie the range of k) may be limited. By limiting, the amount of calculation processing in the correlation calculator 210 is reduced. For example, correlation calculator 210 may limit the measurement range to k=N _s (L+1), . . . , (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 measurement during the time interval corresponding to the code transmission interval Tw.

With the above-described configuration, even when the radar transmission signal directly reaches the radar receiving section 200, the processing by the correlation calculation section 210 is not performed during the period (at least the period less than τ1) during which the radar transmission signal enters. Therefore, the radar device 10 can perform measurements while excluding the effects of wraparound. Further, when limiting the measurement range (k range) may be applied. Thereby, 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, the adding unit 211, based on the output switching signal output from the control unit 400, calculates the radar transmission cycle continuously transmitted from the ND- _th transmitting antenna element _#ND . Addition (coherent integration) processing is performed using the correlation calculation value AC _z (k,M) received from the correlation calculation unit 210 every discrete time k in units of Nb times of Tr (Tr×Nb). where N _D =1,...,Nt and z=1,...,Na.

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,…,Naである。 Addition (coherent integration) processing over a period (Tr×Nb) is represented by the following equation (2).

Here, CI _z ^(ND) (k, m) represents the added value of the correlation calculation value (hereinafter referred to as the correlation added value), and m is an integer of 1 or more indicating the ordinal number of additions in the adder 211. . Also, z=1,...,Na.

In order to obtain an ideal addition gain, it is preferable that the phase components of the correlation calculation values are uniform within a certain range in the addition period of the correlation calculation values. In other words, the number of additions is preferably set based on the assumed maximum moving speed of the target to be measured. This is because the higher the assumed maximum moving speed of the target, the larger the amount of variation in the Doppler frequency contained in the reflected wave from the target, and the shorter the time period with high correlation, so Np (= N × Nb) is a small value. This is because the effect of improving the gain by the addition in the adder 211 becomes small.

In the z-th signal processing unit 207, the output switching unit ₂₁₂ converts CI _z ^(ND) (k,m) into -N _D is selected for output. Here, CI _z ^(ND) (k, m) is obtained by adding a plurality of Nb periods (Tr×Nb) of the radar transmission period Tr continuously transmitted from the _ND transmission antenna element, It is an addition result for each discrete time k, and N _D =1,...,Nt, z=1,...,Na.

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,…,Ntであり、f_s=－Nf+1,…,0,Nfであり、k=1,…,(Nr+Nu)Ns/No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,…,Naである。 Each signal processing section 207 has Nt Doppler analysis sections 213-1 to 213-Nt, the same number as the transmission antenna elements #1 to #Nt. The Doppler analysis unit 213 (213-1 to 213-Nt) outputs CI _z ^(ND) ₍ k, N _C (w−1)+ 1) ∼ CI _z ^(ND) (k, N _C ×w) is used as one unit, and coherent integration is performed with discrete time k timing aligned. For example, the Doppler analysis unit 213 calculates phase variations Φ(f _s )=2πf _s (T _r ×N _b ) ΔΦ corresponding to 2Nf different Doppler frequencies f _s ΔΦ as shown in the following equation (3): After correction, coherent integration is performed.

Here, FT_CI _z ^(ND) (k, f _s , w) is the w-th output of the ND _- th Doppler analysis unit 213- _ND in the z-th signal processing unit 207, and the addition unit 21 shows coherent integration results of Doppler frequency f _s ΔΦ at discrete time k for the N _D -th output of 211 . where N _D =1,…,Nt, f _s =−Nf+1,…,0,Nf, k=1,…,(Nr+Nu)Ns/No, and w is a natural number. , where ΔΦ is the phase rotation unit, j is the imaginary unit, and z=1,...,Na.

, FT_CI _z ^(ND) (k, -Nf ₊ 1, w), ^{. ND)} (k, Nf−1, w) is obtained for each Nb×Nc period (Tr×Nb×Nc) of the radar transmission period Tr.

When ΔΦ=1/N _c , the above-described processing of the Doppler analysis unit 213 performs discrete Fourier processing on the output of the addition unit 211 at the sampling interval T _m =(Tr×N _p ) and the sampling frequency f _m =1/T _m . It is equivalent to transform (DFT) processing.

Also, by setting Nf to a power of 2, the Doppler analysis unit 213 can apply Fast Fourier Transform (FFT) processing, and can reduce the amount of arithmetic processing. In addition, when _Nf > ^Nc , the Doppler analysis unit 213 similarly performs FFT processing can be applied to , and the amount of arithmetic processing can be reduced.

Further, in the Doppler analysis unit 213, instead of the FFT processing, a processing of sequentially calculating the sum of products shown in the above equation (3) may be performed. ^That _is , the Doppler analysis unit 213 calculates f Coefficients exp[-j2πf _s T _r N _b qΔΦ] corresponding to _s =−Nf+1, . where q=0,...,N _c -1.

In the following description, similar processing is performed in each of the signal processing unit 207 of the first antenna system processing unit 201-1 to the signal processing unit 207 of the Na-th antenna system processing unit 201-Na. The w-th output FT_CI _z ⁽¹⁾ (k, f _s , w), …, FT_CI _z ^(Na) (k, f _s , w) is expressed by the following equation (4) (or equation (5) ) as a virtual received array correlation vector h(k,f _s ,w).

The virtual receive array correlation vector h(k, f _s , w) has Nt×Na elements, which is the product of the number Nt of transmit antenna elements #1 to #Nt and the number Na of receive antenna elements #1 to #Na. including. The virtual receiving array correlation vector h(k, f _s , w) is used in the explanation of the process of estimating the direction based on the phase difference between the receiving antenna elements #1 to #Na for the reflected wave signal from the target, which will be described later. use. where z=1,...,Na and N _D =1,...,Nt.

Moreover, in the above equations (4) and (5), the phase rotation for each Doppler frequency (f _s ΔΦ) caused by the transmission time difference from each transmission sub-array is corrected. That is, with the first transmission sub-array (N _D =1) as a reference, the received signal FT_CI _z ^(Na) (k, f _s , w) of the Doppler frequency (f _s ΔΦ) component from the N _D -th transmission sub-array is It is multiplied by exp[-j2πf _s ΔΦ(N _D -1)T _r N _b ].

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

The direction estimation unit 214 uses the w-th Doppler analysis unit 213 output from the signal processing unit 207 of the first antenna system processing unit 201-1 to the signal processing unit 207 of the Na-th antenna system processing unit 201-Na. A virtual reception array correlation vector _{h_after_cal} (k, _fs , w) is calculated for the virtual reception array correlation vector h(k, _fs , w). Here, the virtual reception array correlation vector h _{_after_cal} (k, f _s , w) is expressed by the following equation (6) with respect to the virtual reception array correlation vector h(k, f _s , w) It is a virtual reception array correlation vector obtained by correcting the inter-antenna deviation by multiplying the array correction value h _{cal[b] for} correcting the phase shift deviation and amplitude deviation between the transmission array antennas 108 and between the reception array antennas 202 . Note that b=1,...,(Nt×Na).

The virtual reception array correlation vector _{h_after_cal} (k,f _s ,w) corrected for the inter-antenna deviation is a column vector consisting of Na×Nr elements. Below, each element of the virtual received array correlation vector _{h_after_cal} (k, _fs ,w) is denoted by _h1 (k,fs,w),...,hNa _×Nr (k,fs,w), It is used for explaining the direction estimation processing.

Next, direction estimating section 214 uses virtual reception array correlation vector h _{_after_cal} (k, f _s , w) to calculate reflected wave Performs signal arrival direction estimation 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, fs, w) within a predetermined angle range, and increases the maximum peak of the calculated spatial profile. A predetermined number of samples are sequentially extracted, and the azimuth direction of the maximum peak is used as an estimated value of the direction of arrival.

Note that the evaluation function value P _H (θ, k, fs, w) has various values depending on the direction-of-arrival estimation algorithm. For example, an estimation method using an array antenna disclosed in Non-Patent Document 2 may be used.

For example, the beamformer method can be expressed as in Equations (7) and (8) below.

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。 where the superscript H is the Hermitian transpose operator. Also, a _H (θ _u ) indicates the direction vector of the virtual receiving array for the incoming wave in the azimuth direction θ _u . Also, θ _u is obtained by changing the azimuth range for estimating the direction of arrival at a predetermined azimuth interval β ₁ . For example, θ _u is set as follows.

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

It should be noted that methods such as Capon and MUSIC can also be applied in place of the beamformer method.

FIG. 8 shows a three-dimensional coordinate system used for explaining the operation of the direction estimator 214 according to the present disclosure.

A case in which estimation processing is performed in two-dimensional directions by applying the processing of the direction estimation unit 214 to the three-dimensional coordinate system shown in FIG. 8 will be described below.

In FIG. 8, the position vector of the target _PT with respect to the origin O is defined as _rPT . In FIG. 8, the projection point obtained by projecting the position vector r _PT of the target _PT onto the XZ plane is _PT '. In this case, the azimuth angle θ is defined as the angle between the straight line OP _T ′ and the Z axis (θ>0 if the X coordinate of the target P _T is positive). Also, the elevation angle φ is defined as the angle of a line connecting the target P _T , the origin O and the projected point P _T ' in the plane containing the target P _T , the origin O and the projected point P _T ' (object φ>0 if the Y coordinate of the target P _T is positive). In the following description, an example of arranging the transmitting array antenna 108 and the receiving array antenna 202 in the XY plane will be described.

The position vector of the n _va -th antenna element in the virtual reception array with reference to the origin O is denoted by Sn _va . where n _va =1,..., Nt×Na.

The position vector _S1 of the first (n _va =1) antenna element in the virtual reception array is determined based on the positional relationship between the physical position of the first reception antenna element Rx#1 and the origin O. be. _Position vectors S ₂ , _. is determined while maintaining the relative arrangement of the virtual receiving array determined from the element spacing of . Note that the origin O may coincide with the physical position of the first receiving antenna element Rx#1.

When the radar receiver 200 receives a reflected wave from a target _PT existing in the far field, the received signal at the second antenna element is based on the received signal at the first antenna element of the virtual reception array. The phase difference d(r _PT ,2,1) of the received signal is given by Equation (9) below. where <x,y> is the inner product operator of vector x and vector y.

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

Similarly, when the radar receiving unit 200 receives a reflected wave from a target _PT existing in the far field, the received signal at the n _va ^(r) th antenna element of the virtual reception array is used as a reference, and the 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 given by Equation (11) _below . where n _va ^(r) = 1,..., Nt x Na and n _va ^(t) = 1,..., Nt x Na.

Note that the position vector of the n _va ^(t) -th antenna element based on the position vector of the n _va (r ⁾ -th antenna element of the virtual reception array is the inter-element vector D(n _va ^(t) , n _va ^(r) ) in the following equation (12).

As shown in the above equations (11) and (12), at the n _va ^(t) -th antenna element with reference to the received signal at the n _va ^(r) -th antenna element of the virtual reception array The phase difference d(r _PT , n _va ^(t) , n _va ^(r) ) of the received signal is a unit vector (r _PT /|r _PT |) indicating the direction of the target P _T existing in the far field and It depends on the inter-element vector D(n _va ^(t) , n _va ^(r) ).

Also, when the virtual receiving array exists on the same plane, the inter-element vector D(n _va ^(t) , n _va ^(r) ) exists on the same plane. The direction estimating unit 214 uses all or part of such inter-element vectors to configure a virtual plane array antenna assuming that antenna elements are virtually present at the positions indicated by the inter-element vectors. Perform direction estimation processing in . That is, direction estimating section 214 performs direction-of-arrival estimation processing using a plurality of virtual antennas interpolated by interpolation processing for the antenna elements forming the virtual reception array.

In addition, when the virtual antenna elements overlap, the direction estimation unit 214 may preliminarily select one antenna element among the overlapping antenna elements. Alternatively, the direction estimator 214 may perform averaging processing using received signals from all overlapping virtual antenna elements.

Two-dimensional direction estimation processing using the beamformer method when a virtual plane array antenna is configured using N _q inter-element vector groups will be described below.

Here, the nq-th inter-element vector constituting the virtual plane array antenna is expressed as D(n _va(nq) ^(t) , n _va(nq) ^(r) ). where nq=1,..., _Nq .

The direction estimation unit 214 uses h ₁ (k, fs, w), ..., h _{Na × N} (k, fs, w), which are the elements of the virtual received array correlation vector _{h_after_cal} (k, fs, w). Then, the virtual plane array antenna correlation vector h _VA (k, fs, w) shown in the following equation (13) is generated.

The virtual surface arrangement array direction vector a _VA (θu, φv) is given by the following equation (14).

When the virtual receiving array exists in the XY plane, the relationship between the unit vector (r _PT /|r _PT |) indicating the direction of the target P _T and the azimuth angle θ and elevation angle φ is given by the following equation (15). show.

The direction estimating unit 214 uses the above equation (15) to determine the unit vector (r _PT /|r _PT |) for each of the angular directions θu and φv for calculating the vertical and horizontal two-dimensional spatial profiles. calculate.

Further, the direction estimation unit 214 uses the virtual plane array antenna correlation vector h _VA (k, fs, w) and the virtual plane array antenna direction vector a _VA (θu, φv) to determine horizontal and vertical directions. Perform two-dimensional direction estimation processing.

For example, in two-dimensional direction estimation processing using the beamformer method, using the virtual plane array antenna correlation vector h _VA (k, fs, w) and the virtual plane array antenna direction vector a _VA (θu, φv), Calculate the two-dimensional spatial profile in the vertical and horizontal directions using the two-dimensional direction estimation evaluation function shown in the following equation (16), and the azimuth and elevation directions that give the maximum value or local maximum value of the two-dimensional spatial profile be the direction-of-arrival estimate.

Note that the direction estimator 214 uses the virtual plane array antenna correlation vector h _VA (k, fs, w) and the virtual plane array antenna direction vector a _VA (θu, φv) other than the beamformer method to obtain the Capon A high-resolution direction-of-arrival estimation algorithm such as the MUSIC method or the MUSIC method may be applied. As a result, although the amount of calculation increases, the angular resolution can be improved.

ここで、Tw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。 Also, the time information k described above may be converted into distance information and output. When converting time information k into distance information R(k), the following equation (17) may be used.

Here, Tw represents the code transmission period, L represents the pulse code length, and _C0 represents the speed of light.

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。 Also, 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 following equation (18) can be used.

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

[Antenna Element Arrangement in Radar Device 10 According to Embodiment 1]
The arrangement of the Nt transmitting antenna elements Tx#1 to #Nt of the transmitting array antenna 108 and the Na receiving antenna elements Rx#1 to #Na of the receiving array antenna 202 of the radar apparatus 10 having the above configuration will be described below. explain.

<Arrangement example 1>
FIG. 9 shows arrangement example 1 of receiving antenna elements Rx#1 to Rx#Na of receiving array antenna 202 according to the first embodiment.

As shown in FIG. 9, Na receive antenna elements Rx#1 to Rx#Na of receive array antenna 202 are arranged along the first axis. The Na receiving antenna elements Rx#1 to Rx#Na are arranged at basically equal intervals at a first interval _dH , and some are arranged at a third interval du different from the first interval _dH . be. In other words, of #Na-1 intervals, which are intervals between adjacent receiving antennas of Na receiving antenna elements Rx#1 to Rx#Na, part of them are third intervals different from the first interval. equal to the interval du and otherwise equal to the first interval _dH .

10A shows arrangement example 1 of receive antenna elements Rx#1 to Rx#8 of receive array antenna 202 according to Embodiment 1. FIG.

In one example shown in FIG. 10A, receive array antenna 202 comprises eight receive antenna elements Rx#1-Rx#8. Of the eight receiving antenna elements Rx#1 to Rx#8, the receiving antenna elements Rx#1 to Rx#7 are arranged at equal intervals along the first axis at a first interval _dH . Here, for example, the first spacing d _H is equal to 0.5 wavelengths. The remaining receive antenna element Rx#8 is spaced a third distance 2×d _H from receive antenna element Rx#7. That is, some of the receiving antenna elements Rx#1 to Rx#8 are arranged at unequal intervals. The synthetic aperture length dRx of the phase centers of receive antenna elements Rx#1-Rx#8 is equal to 8×d _H , the width along the first axis of receive antenna elements Rx#1-Rx#8.

FIG. 10B shows arrangement example 1 of transmitting antenna elements Tx#1 to Tx#2 of transmitting array antenna 108 according to Embodiment 1. In FIG.

In one example shown in FIG. 10B, the transmit array antenna 108 comprises two transmit antenna elements Tx#1 and Tx#2. The two receiving antenna elements Tx#1 and Tx#2 are arranged at an interval of 8×d _H in the direction of the first axis and at an interval of d _V in the direction of the second axis orthogonal to the direction of the first axis.

In one example, the first interval _dH and the second interval _dV may each be 0.3 wavelength or more and 2 wavelengths or less, or about half a wavelength, based on the wavelength used in the radar transmission signal. good. For example, the first spacing d _H and the second spacing d _V are equal to 0.5 wavelengths.

The first axis and the second axis may lie on the XY plane shown in FIG. 8, or may be arranged orthogonal to each other. For example, the first axis direction is horizontal and the second axis direction is vertical. In the following description, for the sake of simplicity, it is assumed that the direction of the first axis coincides with the horizontal direction and the direction of the second axis coincides with the vertical direction.

When the transmit array antenna 108 shown in FIG. 10B is used in long-distance observation applications, for example, for observations ahead of vehicles on highways, the field of view (FOV) can be narrowed horizontally and vertically. good. For example, the FOV is approximately 30 degrees horizontally and 10 degrees vertically.

Each of the receiving antenna elements of the receiving array antenna 202 widens the aperture length in the second axis direction to narrow the beam width in the vertical direction with the point (shaded white circle) shown in FIG. 10A as the phase center, thereby achieving a high antenna gain. Obtainable. Further, each of the transmitting antenna elements of the transmitting array antenna 108 has the point (white circle) shown in FIG. The beam width of the antenna can be narrowed down to obtain a high antenna gain. Each antenna element may be configured using a subarray antenna, and an array weight may be applied to the subarray antenna to suppress side lobes.

Dummy antenna elements may be installed for the reception antenna elements Rx#1 to Rx#8 arranged at uneven intervals shown in FIG. 10A. Here, the dummy antenna element is an antenna element that has the same physical configuration as other antenna elements and is not used for transmitting and receiving radar signals. For example, a dummy antenna element is installed in an unevenly spaced area such as between the receiving antenna element Rx#7 and the receiving antenna element Rx#8, the left side area of the receiving antenna element Rx#1, or the right side area of the receiving antenna element Rx#8. You may By installing the dummy antenna element, for example, the effect of uniforming the effects of electrical characteristics such as antenna radiation, impedance matching, and isolation can be obtained.

FIG. 10C shows an arrangement of virtual receive arrays according to Arrangement Example 1. FIG.

As shown in FIG. 10C, a pair of virtual antenna elements VA#8 and VA#9 are arranged adjacent to each other with a spacing of _dV in the second axis direction. Also, as shown in FIG. 10C, the aperture length along the first axis of the virtual receive array is equal to 16×d _H .

A two-dimensional beam is constructed by a two-dimensional virtual receive array extending along a first axis and a second axis. The arrangement of the receiving antenna elements Rx#1 to Rx#8 and the transmitting antenna elements Tx#1 and Tx#2 according to Embodiment 1 is an antenna arrangement having high resolution in the horizontal direction and angle estimation capability in the vertical direction. A certain point will be explained below by comparison with Comparative Example 1 and Comparative Example 2.

<Comparative Example 1>
FIG. 11A shows the arrangement of the receiving antenna elements Rx#1 to Rx#8 of the receiving array antenna according to Comparative Example 1. FIG.

For comparison, the number of receive antenna elements Rx#1 to Rx#8 shown in FIG. 11A is equal to the number of receive antenna elements Rx#1 to Rx#8 shown in FIG. 10A. Further, as shown in FIG. 11A, the receiving antenna elements Rx#1 to Rx#8 are arranged at equal intervals in the first axis direction at the first intervals d _H .

11B shows the arrangement of the transmitting antenna elements Tx#1 and Tx#2 of the transmitting array antenna according to Comparative Example 1. FIG.

For comparison, the number of transmit antenna elements Tx#1 and Tx#2 shown in FIG. 11B is equal to the number of transmit antenna elements Tx#1 and Tx#2 shown in FIG. 11A. In addition, the receiving antenna elements Tx#1 and Tx#2 are spaced apart by 7×d _H in the direction of the first axis so that at least a pair of virtual receiving arrays are aligned in the direction of the second axis. They are arranged at intervals of _dV in two axial directions.

FIG. 11C shows the arrangement of virtual reception arrays according to Comparative Example 1. FIG.

As shown in FIG. 11C, in the virtual receiving array, VA#8 and VA#9 are arranged adjacent to each other with an interval of _dV in the second axis direction, as in the present embodiment shown in FIG. 10C. However, the aperture length of the virtual reception array in the first axial direction is 14×d _H , which is smaller than the aperture length of the virtual reception array in the first axial direction of 16×d _H according to the first embodiment.

12 is a cross-sectional view along the first axis direction at 0 degrees in the second axis direction of the two-dimensional beams according to Arrangement Example 1 and Comparative Example 1. FIG.

As shown in FIG. 12, the beam width of 6.2 degrees corresponding to -3 dB according to the first embodiment is smaller than the beam width of 7.0 degrees according to the first comparative example. That is, according to the antenna arrangement according to the first embodiment, higher resolution along the horizontal direction than the antenna arrangement according to the comparative example 1 can be obtained. When the horizontal viewing angle is narrowed, the level of side lobes on the wide-angle side does not substantially affect the probability of erroneous detection.

<Comparative Example 2>
FIG. 13 shows the arrangement of virtual reception arrays according to Comparative Example 2. In FIG.

For comparison, the number of receiving antenna elements according to Comparative Example 2 is equal to the number of receiving antenna elements Rx#1 to Rx#8 shown in FIG. 10A. Furthermore, the number of transmitting antenna elements according to Comparative Example 2 is equal to the number of transmitting antenna elements Tx#1 and Tx#2 shown in FIG. 11A.

To maximize the aperture length along the first axis in the virtual receive array, the eight receive antenna elements are evenly spaced along the first axis as shown in FIG. 11A. Furthermore, two transmitting antenna elements are arranged at an interval of 8×d _H in the first axis direction as shown in FIG. 10B. In this case, the arrangement of the virtual receiving arrays is the arrangement shown in FIG.

Under the situation of using a virtual receive array with the arrangement shown in FIG. 13, the presence of multiple targets at the same distance and same velocity will, for example, lead to errors in estimating the vertical component of the direction of arrival. On the other hand, in the virtual reception array according to Embodiment 1, since a pair of virtual reception arrays are also arranged in the second axis direction, even if a plurality of targets exist at the same distance and at the same speed, vertical Errors in estimating direction components are reduced, and detection accuracy is improved.

If the spacing along the first axis direction between the transmitting antenna elements Tx#1 and Tx#2 of the transmitting array antenna 108 is equal to the synthetic aperture length dR of the receiving array antenna 202, then at least one pair of virtual receiving arrays are arranged in the second axis direction. It is preferable because the aperture length in the first axis direction of the virtual receiving array can be maximized while arranging the virtual receiving arrays in parallel. For example, the synthetic aperture length dR of the receiving array antenna 202 shown in FIG. 10A and the interval between the transmitting antenna elements Tx#1 and Tx#2 of the transmitting array antenna 108 shown in FIG. 10B are both 8× _dH . equal. However, the interval between the transmitting antenna elements _Tx #1 and Tx#2 of the transmitting array antenna 108 is not limited to this. It can be double. By narrowing the distance between the transmitting antenna elements Tx#1 and Tx#2 in the direction of the first axis, the number of combinations of virtual receiving arrays arranged in the direction of the second axis increases, and the accuracy in the vertical direction is improved.

In arrangement example 1 shown in FIG. 10A, the third spacing du between receive antenna elements Rx#7 and Rx#8 is equal to 2* _dH . However, the size of the third interval du is not limited to this. For example, increasing the third spacing du and increasing the aperture length of the virtual receive array can narrow the main lobe of the formed beam and improve the resolution. Further, for example, the side lobe level can be reduced by reducing the third spacing du and reducing the aperture length of the virtual receiving array.

<Arrangement example 2>
In arrangement example 1 shown in FIG. 10A, the receiving array antenna 202 is arranged such that the spacing between the receiving antenna elements Rx#7 and Rx#8 is different from the spacing between the receiving antenna elements Rx#1 to Rx#7. The ends are unevenly spaced. However, the antenna arrangement according to Embodiment 1 is not limited to arrangement example 1. FIG.

14A shows arrangement example 2 of receive antenna elements Rx#1 to Rx#8 of receive array antenna 202 according to arrangement example 2 of Embodiment 1. FIG.

In arrangement example 2 shown in FIG. 14A, the spacing between the receiving antenna elements Rx#5 and Rx#6 is the spacing between the receiving antenna elements Rx#1 to Rx#5 and the spacing between the receiving antenna elements Rx#6 to Rx#8. The inner sides of the receiving array antennas 202 are arranged at unequal intervals so that they are different from the intervals.

FIG. 14B shows an arrangement of virtual receive arrays according to Arrangement Example 2. FIG.

As shown in FIG. 14B, a pair of virtual antennas VA#8 and VA#9 are arranged adjacent to each other with a spacing of _dV in the second axis direction. Also, as shown in FIG. 14B, the aperture length along the first axis of the virtual receive array is equal to 16×d _H .

FIG. 15 is a cross-sectional view of the two-dimensional beams according to Arrangement Example 1 and Arrangement Example 2 along the first axis direction at 0 degrees in the second axis direction.

As shown in FIG. 15, it can be seen that the sidelobe level changes by changing the reception antenna elements arranged at irregular intervals in the reception array antenna 202 . On the other hand, even if the receiving antenna elements arranged at unequal intervals in the receiving array antenna 202 are changed, the aperture length of the virtual receiving array is equal to 16×d _H and the main lobe width hardly changes.

The arrangement of the transmitting array antenna 108 and the receiving array antenna 202 is not limited to the arrangement described above. For example, even if the positions of the transmitting array antenna 108 and the receiving array antenna 202 are exchanged, the same virtual reception array as before the exchange is obtained, and the same characteristics as before the exchange are obtained. Also, the arrangement of the transmitting array antenna 108 and the receiving array antenna 202 may be horizontally reversed and/or vertically reversed.

In Embodiment 1 of the present disclosure, radar apparatus 10 receives radar transmission section 100 that transmits a radar signal from transmission array antenna 108 and a reflected wave signal of the radar signal reflected by a target from reception array antenna 202. and a radar receiver 200 . Further, transmit antenna elements Tx#1 to Tx#Nt of transmit array antenna 108 and receive antenna elements Rx#1 to Rx#Na of receive array antenna 202 are shown in FIG. 9, FIG. 10A, FIG. 10B, or FIG. 14A. take placement.

According to Embodiment 1 of the present disclosure, it is possible to suppress degradation in horizontal resolution and configure a virtual reception array having vertical angle estimation capability, and perform horizontal and vertical angle estimation with high accuracy. It is possible to configure a radar device capable of performing three-dimensional positioning. Furthermore, according to the first embodiment of the present disclosure, a three-dimensional radar device in which angle estimation capability in the second axis direction is added without deteriorating angle separation performance in the horizontal direction compared to a MIMO radar device that performs one-dimensional beam scanning A positioning-capable MIMO radar device can be configured.

(Embodiment 2)
Embodiment 2 in which the arrangement of transmitting antenna elements Tx#1 to Tx#Nt of transmitting array antenna 108 is different from the antenna arrangement in Embodiment 1 will be described below. Note that the configuration of radar apparatus 10 according to Embodiment 2 is the same as that of radar apparatus 10 according to Embodiment 1 shown in FIG. The configuration is substantially the same as that of the radar device 10, and the description of the configuration of the radar device 10 is omitted.

[Antenna Arrangement in Radar Device 10]
<Arrangement example 3>
FIG. 16A shows arrangement example 3 of transmitting antenna elements Tx#1 to Tx#Nt of transmitting array antenna 108 according to Embodiment 2. FIG.

In FIG. 16A, the total number Nt of transmit antenna elements #1 to #Nt is equal to four. The transmitting antenna elements #1 to #4 are arranged with a second spacing _dV in the second axis direction and alternately with a first spacing _dH in the first axis direction. For example, the first spacing d _H and the second spacing d _V are equal to 0.5 wavelengths and 0.6 wavelengths respectively.

Each of the antenna elements of the transmission array antenna 108 has the point (white circle) shown in FIG. 16A as the phase center, and has a configuration in which the aperture length is widened to the extent that the antennas do not interfere with each other in the second axis direction, and the beam width in the vertical direction is narrowed. take. When the transmit array antenna 108 is used in close-range and wide-angle viewing applications, the field of view (FOV) may be widened horizontally and vertically. For example, the FOV is approximately 80 degrees horizontally and 30 degrees vertically.

The arrangement of a plurality of receive antenna elements #1 to #Na of receive array antenna 202 according to arrangement example 3 of Embodiment 2 is similar to the arrangement shown in FIG. 10A. Each of the antenna elements of the receiving array antenna 202 is an antenna whose phase center is the point shown in FIG. 10A, whose aperture length is widened in the direction of the second axis, and whose beam width in the vertical direction is about 30 degrees, which is the viewing angle. element.

The plurality of transmitting antenna elements #1 to #Nt and the plurality of receiving antenna elements #1 to #Na may be antennas having a wide beam width in the horizontal direction so as to enable wide-angle observation. Each antenna element may be configured using a subarray antenna, or an array weight may be applied to the subarray antenna to suppress side lobes.

Dummy antenna elements may be installed for the receiving antenna elements Rx#1 to #8 arranged at irregular intervals shown in FIG. 10A. For example, a dummy antenna element is installed in an unevenly spaced area such as between the receiving antenna element Rx#7 and the receiving antenna element Rx#8, the left side area of the receiving antenna element Rx#1, or the right side area of the receiving antenna element Rx#8. You may By installing a dummy antenna element, it is possible to obtain the effect of equalizing the effects of electrical characteristics such as antenna radiation, impedance matching, and isolation.

FIG. 16B shows the placement of the virtual receive array according to placement example 3. FIG.

The arrangement of the receiving antenna elements Rx#1 to Rx#8 and the transmitting antenna elements Tx#1 to Tx#4 according to Embodiment 2 is an antenna arrangement having high resolution in the horizontal and vertical directions. A comparison with Comparative Example 3 in which the elements are arranged at regular intervals will be described below.

<Comparative Example 3>
For comparison, the number Na of the receiving antenna elements Rx#1 to Rx#Na in Comparative Example 3 is equal to the number 8 of the receiving antenna elements Rx#1 to Rx#8 shown in FIG. 10A. Also, the number of elements Nx of the transmission antenna elements Tx#1 to Tx#Nx in Comparative Example 3 is equal to the number of elements 4 of the transmission antenna elements Tx#1 to Tx#4 shown in FIG. 16A.

In Comparative Example 3, the receiving antenna elements Rx#1 to Rx#8 are arranged at equal intervals as shown in FIG. 11A. Also, the transmitting antenna elements Tx#1 to Tx#4 are arranged in the same manner as shown in FIG. 16A.

FIG. 17 shows an arrangement of virtual reception arrays according to Comparative Example 3. In FIG.

As shown in FIG. 17, the aperture length in the first axis direction of the virtual receiving array according to Comparative Example 3 is equal to 8×d _H . This aperture length is smaller than 9×d _H which is the aperture length in the first axis direction of the virtual receiving array according to the second embodiment shown in FIG. 16B.

18 is a cross-sectional view along the first axis direction at 0 degrees in the second axis direction of the two-dimensional beams according to Arrangement Example 3 and Comparative Example 3. FIG.

As shown in FIG. 18, the beam according to the second embodiment has lower adjacent side lobes than the beam according to the third comparative example. That is, the antenna arrangement according to the second embodiment reduces the probability of false detection as compared with the antenna arrangement according to the third comparative example. Also, the beam width according to the second embodiment is smaller than the beam width according to the third comparative example. That is, the antenna arrangement according to the second embodiment provides higher resolution than the antenna arrangement according to the third comparative example.

Also in Embodiment 2, as in Embodiment 1, the third spacing du of the spacing between the receiving antenna elements Rx#7 and Rx#8 is 2×d _H be equivalent to. However, the size of the third interval du is not limited to this. For example, by increasing the third spacing du and increasing the aperture length of the virtual receive array, the main lobe of the formed beam can be narrowed to improve resolution. Also, for example, the sidelobe level can be reduced by reducing the third spacing du and reducing the aperture length of the virtual receive array.

Also in the second embodiment, as in the first embodiment, the side lobe level changes by changing the receiving antennas arranged at irregular intervals in the receiving array antenna 202 . On the other hand, even if the receiving antenna elements arranged at irregular intervals in the receiving array antenna 202 are changed, the aperture length of the virtual receiving array does not change, and the main lobe width hardly changes.

<Arrangement example 4>
FIG. 19 is a diagram showing arrangement example 4 of transmitting antenna elements Tx#1 to Tx#4 of transmitting array antenna 108 according to Embodiment 2. In FIG.

In Embodiment 2, the transmitting antenna elements Tx#2 and Tx#4 are not shifted in the first axial direction, as in Arrangement Example 4 shown in FIG. Even if they are arranged at regular intervals of _dV , the same effect as in Arrangement Example 3 shown in FIG. 16A can be obtained.

Also in Embodiment 2, as in Embodiment 1, the arrangement of transmitting array antenna 108 and receiving array antenna 202 is not limited to the arrangement described above. For example, even if the positions of the transmission array antenna 108 and the reception array antenna 202 are exchanged, the same virtual reception array as before the exchange can be obtained, and the same characteristics can be obtained. Also, the arrangement of the transmitting array antenna 108 and the receiving array antenna 202 may be horizontally reversed and/or vertically reversed.

In Embodiment 2 of the present disclosure, radar apparatus 10 receives radar transmission section 100 that transmits a radar signal from transmission array antenna 108 and a reflected wave signal of the radar signal reflected by a target from reception array antenna 202. and a radar receiver 200 . Furthermore, transmitting antenna elements Tx#1 to Tx#Nt of transmitting array antenna 108 and receiving antenna elements Rx#1 to Rx#Na of receiving array antenna 202 adopt the arrangement shown in FIG. 16 or FIG. 19, for example.

According to Embodiment 2 of the present disclosure, it is possible to suppress the horizontal sidelobes of the beams formed by the virtual receiving array, and in addition, it is possible to improve the horizontal resolution, and the probability of false detection is It is possible to configure a MIMO radar capable of three-dimensional positioning with a reduced

(Embodiment 3)
A third embodiment in which transmission antenna elements Tx#1 to Tx#Nt of transmission array antenna 108 are switched and used will be described below.

FIG. 20 is a block diagram showing an example of the configuration of a radar receiver (radar receiver circuit) 200a according to the third embodiment.

A direction estimating unit (direction estimating circuit) 214a of the radar receiving unit 200a has the function of the direction estimating unit 214 according to the first and second embodiments. Further, the direction estimator 214a receives a control signal from the controller 400 and switches the operation mode of the radar device 10 based on the control signal. Operation modes will be described later with reference to FIG.

Components other than the direction estimating unit 214a of the radar receiving unit 200a are the same as those of the radar receiving unit 200 according to Embodiments 1 and 2, and description thereof will be omitted.

[Antenna Arrangement in Radar Device 10]
Hereinafter, for simplicity, the number Nt of the transmitting antenna elements #Tx1 to #Nt of the transmitting array antenna 108 is equal to 6, and the number Na of the receiving antenna elements Rx#1 to #Na of the receiving array antenna 202 is set to 8. Embodiment 3 will be described by taking the case of equality as an example. However, the number of elements is not limited to these numbers.

In the third embodiment, the receiving antenna elements Rx#1 to Rx#8 of the receiving array antenna 202 are arranged at equal intervals and partially at irregular intervals, as in the first and second embodiments. For example, the arrangement of receive array antenna 202 is similar to the arrangement shown in FIG. 10A.

FIG. 21 shows arrangement example 4 of transmitting antenna elements Tx#1 to Tx#6 of transmitting array antenna 108 according to the third embodiment.

The transmitting antenna elements Tx#1 to Tx#6 include a first transmitting antenna group G1 and a second transmitting antenna group G2.

The first transmitting antenna group G1 includes transmitting antenna elements Tx#1 and Tx#2, and its antenna arrangement is transmitting antenna elements Tx#1 and Tx according to arrangement example 1 of Embodiment 1 shown in FIG. 10B. Same as #2 arrangement. The first transmitting antenna group G1 is used, for example, for long-distance narrow-angle observation applications.

The second transmitting antenna group G2 includes transmitting antenna elements Tx#3 to Tx#6, and the antenna arrangement thereof is transmitting antenna elements Tx#1 to Tx according to arrangement example 3 of Embodiment 2 shown in FIG. 16A. It is the same as the arrangement of #Nt. The second transmitting antenna group G2 is used, for example, for short-range wide-angle observation. Depending on the observation application, the used transmit antenna group is switched between the first transmit antenna group G1 or the second transmit antenna group G2.

The first group of transmitting antennas G1 or the second group of transmitting antennas G2 independently form a virtual receiving array. The first transmitting antenna group G1 and the receiving array antenna 202 shown in FIG. 10A constitute the virtual receiving array shown in FIG. 10C. The second transmitting antenna group G2 and the receiving array antenna 202 shown in FIG. 10A constitute the virtual receiving array shown in FIG. 16B.

The first transmitting antenna group G1 and the second transmitting antenna group G2 shown in FIG. 21 may have a common basic spacing in the first axis direction, or may have different basic spacings in the second axis direction. good too. For example, even if the basic spacing _dH1 in the first axial direction of the first transmitting antenna group G1 and the basic spacing _dH2 in the first axial direction of the second transmitting antenna group G2 are both 0.5 wavelengths. good. Also, for example, the basic spacing _dV1 in the second axial direction of the first transmitting antenna group G1 may be equal to 0.5 wavelength, and the basic spacing _dV2 in the second axial direction of the second transmitting antenna group G2 may be equal to 0.6 wavelengths.

As described above, the first transmitting antenna group G1 and the second transmitting antenna group G2 independently configure a virtual receiving array. Therefore, as long as there is no physical interference, the antenna elements of the first transmitting antenna group G1 and the second transmitting antenna group G2 may be freely arranged including their sizes.

FIG. 22 shows an example of arrangement of each antenna element of transmission array antenna 108 according to arrangement example 4 of the third embodiment.

As shown in FIG. 22, by arranging the transmitting antenna elements of the second antenna group G2 between the transmitting antenna elements Tx#1 and Tx#2 of the first antenna group G1, the entire transmitting array antenna 108 can reduce the installation area.

The configuration of each antenna element of the first transmitting antenna group G1 and the second transmitting antenna group G2 may adopt a configuration suitable for the viewing angle (FOV). For example, the first transmitting antenna group G1 narrows the beam width along both the horizontal and vertical directions, as shown in FIG. Spread in both directions of two axes. Also, for example, in order to obtain a relatively wide-angle beam radiation pattern along the vertical direction, the second transmitting antenna group G2 is arranged so that the antenna elements do not interfere with each other, as shown in FIG. Widen the aperture length of the element. Each antenna element may be configured using a subarray antenna, and an array weight may be applied to the subarray antenna to suppress side lobes.

Also in Embodiment 3, as in Embodiment 1, dummy antenna elements may be installed for receiving antenna elements Rx#1 to Rx#8 arranged at uneven intervals shown in FIG. 10A. . For example, a dummy antenna element is provided in an unevenly spaced area such as between the receiving antenna element Rx#7 and the receiving antenna element Rx#8, in the area on the left side of the receiving antenna element Rx#1, or in the area on the right side of the receiving antenna element Rx#8. may be installed. By installing the dummy antenna element, for example, the effect of uniforming the influence of electrical characteristics such as antenna radiation, impedance matching, or isolation can be obtained.

FIG. 23 shows an example of time-division switching control of the first antenna group G1 and the second antenna group G2 according to the third embodiment.

When the radar apparatus 10 is a time division multiplexing MIMO radar, the radar transmission section 100 temporally switches the combination of antennas used for time division multiplexing transmission based on the control signal from the control section 400 . As shown in FIG. 23, in the long-range mode, which is an operation mode for performing long-range narrow-angle observation, the radar transmitter 100 sets the transmission antenna elements Tx#1 and Tx#2 of the first transmission antenna group G1 to Used for time division multiplex transmission. Further, in the short-range mode, which is an operation mode in which short-range and wide-angle observation is performed, the radar transmission unit 100 uses the transmission antenna elements Tx#3 to Tx#6 of the second transmission antenna group G2 for time-division multiplex transmission. .

In addition, in the case of an operation mode that uses both the long-distance mode and the short-distance mode, the radar transmission unit 100 temporally shifts the first transmission antenna group G1 and the second transmission antenna group G2 used for time-division multiplex transmission to switch. For example, the radar transmission section 100 switches and uses all transmission antennas Tx#1 to Tx#6 in a time division manner. For example, as shown in FIG. 23, in time intervals dur1, dur2, dur7, and dur8, transmit antenna elements Tx#1 and Tx#2 of the first antenna group G1 are used for time division multiplexing transmission. Also, in the time intervals dur3 to dur6, dur9, and dur10, the transmission antennas Tx#3 to Tx#6 of the second antenna group G2 are used for time division multiplex transmission. Note that the order of using the transmitting antenna elements Tx#1 to Tx#6 is not limited to the order shown in FIG.

In Embodiment 3, the radar receiving section of FIG. 20 may be used, and the direction estimating section 214a selects the operation mode of the radar device 10 based on the control signal indicating the operation mode input from the control section 400. You can switch. Further, in Embodiment 3, the radar transmission unit in FIG. 2 may be used, and the radar signal generation unit 101 may switch the operation mode of the radar device 10 based on the control signal input from the control unit 400. .

In one example, the radar transmission signal generator 100 may transmit radar signals with different signal characteristics such as transmission cycle or transmission bandwidth depending on the operation mode based on instruction information from the control unit 400 . For example, when operating in short-range mode, the radar device 10 may transmit radar signals over a relatively wide band to obtain higher range resolution. On the other hand, when operating in the long-range mode, radar signals may be transmitted at relatively fast intervals in order to observe faster moving objects.

Further, when the radar device 10 is a MIMO radar multiplexed by code division or frequency division, the radar transmission unit 100 supplies power to the first transmission antenna group G1 and the second transmission antenna group G2 according to the operation mode. can be switched. By switching the feed, the group of transmitting antennas to be used is selected and the operation mode can be switched.

In Embodiment 3 of the present disclosure, radar apparatus 10 receives radar transmission section 100 that transmits a radar signal from transmission array antenna 108 and a reflected wave signal of the radar signal reflected by a target from reception array antenna 202. and a radar receiver 200 . Furthermore, the radar device 10 switches the virtual reception array to be used, for example, between the virtual reception arrays configured in the first and second embodiments according to the operation mode.

According to Embodiment 3 of the present disclosure, it is possible to configure a MIMO radar capable of three-dimensional positioning that obtains the effects obtained in Embodiments 1 and 2 in operation modes corresponding to each.

Various embodiments have been described above with reference to the drawings, but it goes without saying that the present disclosure is not limited to such examples. It is obvious that a person skilled in the art can conceive of various modifications or modifications within the scope described in the claims, and these also belong to the technical scope of the present disclosure. Understood. Also, the components in the above embodiments may be combined arbitrarily without departing from the gist of the disclosure.

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

Each functional block used in the description of each of the above embodiments is typically implemented as an LSI, which is an integrated circuit. The integrated circuit may control each functional block used in the description of the above embodiments and may have inputs and outputs. These may be made into one chip individually, or may be made into one chip so as to include part or all of them. Although LSI is used here, it may also be called IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.

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

Furthermore, if an integration technology that replaces the LSI appears due to advances in semiconductor technology or another derived technology, the technology may naturally be used to integrate the functional blocks. For example, the application of biotechnology is a possibility.

[Summary of Examples]
A radar apparatus according to the present disclosure includes a radar transmission unit that transmits a radar signal from a transmission array antenna, and a radar reception unit that receives a reflected wave signal of the radar signal reflected by a target from a reception array antenna, One of the transmitting array antenna and the receiving array antenna includes a plurality of first antennas with phase centers arranged along a first axis direction, and the other of the transmitting array antenna and the receiving array antenna has a phase center a plurality of second antennas arranged at a second spacing in a second axial direction different from the first axial direction, the plurality of first antennas having phase centers arranged at a first spacing; three or more antennas; and two or more antennas arranged at a third spacing different from the first spacing, wherein the plurality of second antennas have phase centers along the first axis. in the direction, spaced equal to the synthetic aperture length of the phase centers of the plurality of first antennas.

In the radar device of the present disclosure, the spacing between the phase centers of adjacent antennas of the plurality of first antennas is equal to the first spacing except for at least one spacing, and the at least one spacing is equal to the third is equal to the interval of

In the radar device of the present disclosure, the third interval is equal to an integral multiple of the first interval.

In the radar device of the present disclosure, the third interval is equal to twice the first interval.

In the radar device of the present disclosure, the at least one interval is one interval.

In the radar apparatus of the present disclosure, the plurality of second antennas are arranged with phase centers in the first axis direction at intervals equal to the synthetic aperture length of the phase centers of the plurality of first antennas.

In the radar device of the present disclosure, the number of elements of the second antenna is equal to two.

In the radar device of the present disclosure, the length of the range in which the phase centers are arranged in the first axis direction of the plurality of second antennas is equal to or less than the synthetic aperture length of the phase centers of the plurality of first antennas. , are arranged in the direction of the second axis at an interval that is an integral multiple of the second interval.

In the radar device of the present disclosure, the plurality of second antennas have phase centers arranged at the second intervals in the second axis direction.

In the radar device of the present disclosure, the plurality of second antennas includes a first antenna group and a second antenna group that have different virtual receiving arrays, and the first antenna group and the plurality of first antenna groups Transmission/reception with antennas and transmission/reception with the second antenna group and the plurality of first antennas can be switched.

INDUSTRIAL APPLICABILITY The present disclosure is suitable for radar devices that detect a wide angle range.

REFERENCE SIGNS LIST 10 radar device 100 radar transmitter 101, 101a radar transmission signal generator 102 code generator 103 modulator 104 LPF
105 transmission frequency conversion unit 106 power divider 107 transmission amplification unit 108 transmission array antenna 108-1, ..., 108-Nt transmission antenna element 111 code storage unit 112 DA conversion unit 200 radar reception unit 201-1, ..., 201-Na Antenna System Processing Unit 202 Receiving Array Antenna 202-1, . Conversion unit 210 Correlation calculation unit 211 Addition unit 212 Output switching unit 213-1, ..., 213-Nt Doppler analysis unit 214 Direction estimation unit 300 Reference signal generation unit 400 Control unit

Claims (7)

a radar transmitter that transmits a radar signal from a transmission array antenna;
a radar receiver that receives a reflected wave signal of the radar signal reflected by a target from a receiving array antenna;
and
one of the transmitting array antenna and the receiving array antenna includes a plurality of first antennas with phase centers arranged along a first axis direction;
The plurality of first antennas include antennas whose phase centers are arranged at a first interval , and antennas whose phase centers are arranged at a fifth interval different from the first interval ,
The other of the transmitting array antenna and the receiving array antenna includes a plurality of second antennas whose phase centers are arranged at second intervals in a second axis direction different from the first axis direction, and a plurality of third antennas arranged at a third interval in the second axial direction;
the synthetic aperture lengths of the plurality of third antennas in the second axial direction are wider than the synthetic aperture lengths of the plurality of second antennas in the second axial direction;
wherein the phase centers of the plurality of second antennas are arranged in the first axis direction at intervals equal to the synthetic aperture length of the phase centers of the plurality of first antennas;
The radar transmission unit is capable of switching between transmission by the plurality of second antennas and transmission by the plurality of third antennas,
radar equipment. The plurality of first antennas include three or more antennas whose phase centers are arranged at the first interval , and two or more antennas whose phase centers are arranged at the fifth interval. is
The radar device according to claim 1. The plurality of third antennas further includes one or more antennas whose phase centers are arranged at fourth intervals in the first axis direction,
The radar device according to claim 1 or 2. said fifth interval is equal to twice said first interval ;
The radar device according to any one of claims 1 to 3. the plurality of first antennas includes three antennas with the phase centers arranged at the first spacing ;
The radar device according to any one of claims 1 to 4. the number of elements of the plurality of second antennas is equal to two;
The radar device according to any one of claims 1 to 5. In the plurality of second antennas, the length of the range in which the phase centers are arranged in the first axis direction is equal to or less than the synthetic aperture length of the phase centers of the plurality of first antennas, and arranged at the second spacing ;
Radar device according to any one of claims 1 to 6.

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