Radar device and vehicle

Abstract

The invention provides a radar device and a vehicle, which can improve the calculation precision of the position of a target object. A radar device according to one embodiment of the present disclosure is provided with: a radar module having a transmission antenna for transmitting a transmission signal; and a re-radiating unit having a re-radiating element that re-radiates the transmission signal.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a radar device and a vehicle. BACKGROUND

[0002] Further research is being conducted on longitudinal / lateral high resolution in order to achieve an imaging function (acquisition of an image) with a radar device. In general, it is known that resolution performance of an object can be improved by narrowing a beam to achieve high resolution, and in order to narrow the beam, it is sufficient to increase an antenna aperture. Here, as a method of increasing the antenna aperture, there are a method of increasing the number of antennas and a method of configuring by pulling apart the distance between antennas without increasing the number of antennas.

[0003] In the case of increasing the number of antennas, as the number of antennas increases, the substrate size becomes large, and the number of ICs that control the antennas also increases, so there are technical problems in terms of module size and heat dissipation.

[0004] In the case of configuring by pulling apart the distance between antennas, the substrate size becomes large. In addition, since the distance between antennas is not half a wavelength (λ / 2), there are technical problems in which detection performance is degraded due to the generation of a grating lobe (side lobe).

[0005] For example, in Patent Literature 1, with respect to radiation directivity of a radar device, a scheme is proposed in which a lens formed of a metamaterial is used to narrow a beam, and radiation directivity direction thereof is controlled. In addition, in Non-Patent Literature 1, a method is proposed in which a metasurface is formed by controlling the transmission amplitude and the transmission phase of a sheet using a metamaterial technology, and radiation directivity control in which a side lobe is suppressed is performed.

[0006] PRIOR ART DOCUMENTS

[0007] PATENT LITERATURE

[0008] Patent Literature 1: Japanese Patent Application Laid-Open No. 2010-526318

[0009] Patent Literature 2: Japanese Patent Application Laid-Open No. 2023-011202

[0010] Patent Literature 3: Japanese Patent Application Laid-Open No. 2020-153872

[0011] Patent Literature 4: Japanese Patent Application Laid-Open No. 2020-060483

[0012] Patent Literature 5: Japanese Patent Application Laid-Open No. 2020-060485

[0013] NON-PATENT LITERATURE

[0014] Non-Patent Literature 1: "Transmissive Metasurface With Independent Amplitude / Phase Control and Its Application to Low-Side-Lobe Metalens Antenna".

[0015] Non-Patent Literature 2: "Design of a novel polarization converter based on artificial materials with metallic meta-atoms". SUMMARY

[0016] However, the prior art of Patent Literature 1 and Non-Patent Literature 1 is a beam control technology that utilizes a lens effect using a metamaterial technology, and is not a technology for physically increasing the number of antennas as a MIMO radar.

[0017] The present disclosure relates to a MIMO radar that achieves high resolution by physically increasing the number of antennas, and contributes to providing a radar device and a vehicle that can improve the detection accuracy of the position of a target object.

[0018] A radar device of one embodiment of the present disclosure includes a radar module including a transmission antenna that transmits a transmission signal, and a re-radiation unit including a re-radiation element that re-radiates the transmission signal.

[0019] A vehicle of one embodiment of the present disclosure includes a radar device including a radar module including a transmission antenna that transmits a transmission signal, and a re-radiation unit including a re-radiation element that re-radiates the transmission signal.

[0020] According to one embodiment of the present disclosure, the detection accuracy of the position of a target object can be improved by high resolution. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a diagram illustrating a concept of a radar device.

[0022] Figure 2 is a block diagram.

[0023] Figure 3 is a diagram illustrating a concept of a radar device of Embodiment 1.

[0024] Figure 4 is a diagram illustrating a concept of a radar device of Embodiment 1.

[0025] Figure 5Ais a graph of the radiation direction in the case where the direction of the radiation signal is not controlled.

[0026] Figure 5B is a graph of the radiation direction in the case where the direction of the radiation signal is controlled.

[0027] Figure 6 is a graph explaining the concept of the radar apparatus of Embodiment 6.

[0028] Figure 7 is a graph explaining the concept of the radar apparatus of the modification of Embodiment 6.

[0029] Figure 8A is a graph explaining the concept of the radar apparatus of Embodiment 7.

[0030] Figure 8B is a graph explaining the concept of the radar apparatus of Embodiment 7.

[0031] Figure 9A is a graph explaining the concept of the radar apparatus of the modification 1 of Embodiment 7.

[0032] Figure 9B is a graph explaining the concept of the radar apparatus of the modification 1 of Embodiment 7.

[0033] Figure 10A is a graph explaining the concept of the radar apparatus of the modification 2 of Embodiment 7.

[0034] Figure 10B is a graph explaining the concept of the radar apparatus of the modification 2 of Embodiment 7.

[0035] Figure 11A is a graph explaining the concept of the radar apparatus of the modification 3 of Embodiment 7.

[0036] Figure 11B is a graph explaining the concept of the radar apparatus of the modification 3 of Embodiment 7.

[0037] Figure 12 is a graph explaining the concept of the radar apparatus of Embodiment 8.

[0038] Figure 13 is a graph explaining the time when the transmission antenna element and the re-radiation element radiate a signal.

[0039] Figure 14 is a graph explaining the structure of the radar receiving section 119 of Embodiment 8.

[0040] Figure 15 is a graph explaining the outline of the separation in the beat analysis section.

[0041] Figure 16FIG. 8 is a diagram illustrating a concept of a radar device according to a modification 1 of Embodiment 8.

[0042] Figure 17 FIG. 9 is a diagram illustrating a time when a transmission antenna element and a re-radiation element radiate a signal.

[0043] Figure 18 FIG. 10 is a diagram illustrating a concept of a radar device according to a modification 2 of Embodiment 8.

[0044] Figure 19 FIG. 11 is a diagram illustrating a concept of a radar device according to Embodiment 9.

[0045] Figure 20A FIG. 12 is a diagram illustrating vertical polarization.

[0046] Figure 20B FIG. 13 is a diagram illustrating horizontal polarization.

[0047] Figure 20C FIG. 14 is a diagram illustrating right-hand circular polarization.

[0048] Figure 20D FIG. 15 is a diagram illustrating left-hand circular polarization.

[0049] Figure 21 FIG. 16 is a diagram illustrating an outline in a case where the radar device according to Embodiment 10 is mounted on a vehicle.

[0050] Figure 22 FIG. 17 is a diagram illustrating a structure example of a thin radar device.

[0051] Figure 23 FIG. 18 is a diagram illustrating a structure example of a thin radar device.

[0052] BRIEF DESCRIPTION OF DRAWINGS

[0053] 110 radar module

[0054] 111 radar transmission signal generation section

[0055] 112 wireless transmission section

[0056] 113 transmission antenna

[0057] 113-1 to 113-N transmission antenna elements

[0058] 114 control section

[0059] 115 reception antenna

[0060] 116 wireless reception section

[0061] 117 signal processing section

[0062] 118 radar transmission section

[0063] 119 radar receiving section

[0064] 120 reradiation section

[0065] 120-1 to 120-M reradiation elements

[0066] 130 target

[0067] 140 integrated control section

[0068] 1401 antenna system processing section

[0069] 1402 mixer section

[0070] 1403 LPF

[0071] 1404 AD conversion section

[0072] 1405 beat analysis section

[0073] 1406 range separation section

[0074] 1407 Doppler analysis section

[0075] 1408 CFAR section

[0076] 1409 direction estimation section

[0077] 2201 circuit substrate

[0078] 2202 signal processing IC

[0079] 2202-1 IC for millimeter wave band

[0080] 2202-2 IC for baseband

[0081] 2203 connector

[0082] 2204 dielectric lens

[0083] 2205 window section

[0084] 2206 transmission signal

[0085] 2207 housing DETAILED DESCRIPTION

[0086] Hereinafter, embodiments of the present disclosure will be explained in detail with appropriate reference to the attached drawings.

[0087] Figure 1The illustrated radar module 110 has N transmission antenna elements 113-1 to 113-N arranged on the zy plane, and the reradiation section 120 has M reradiation elements 120-1 to 120-M arranged on the zy plane for each of the transmission antenna elements 113-1 to 113-N. The electric waves (transmission signals) radiated from each of the transmission antenna elements 113-1 to 113-N are reradiated by each of the reradiation elements 120-1 to 120-M. For example, the electric waves radiated in the x-axis direction from each of the transmission antenna elements 113-1 to 113-N of the radar module 110 are, when reradiated by the reradiation section 120, at least one of the phase, the delay time, and the polarization is converted by the reradiation elements #1, #M. The radar module 110 can receive the electric waves reradiated in the x-axis direction by each of the reradiation elements and the reflected waves of the electric waves radiated by the transmission antenna elements after being reflected by the target 130. In addition, when a transparent film is used as the reradiation section 120, the electric waves that have not passed through the M reradiation elements 120-1 to 120-M of the reradiation section 120 but have been transmitted through the transparent film are reflected by the target (object) 130 and received by the radar module 110. At least one of the phase, the delay time, and the polarization of each of the electric waves that have been reradiated or transmitted by the reradiation section 120 is different, and thus the radar module 110 can separate the received reflected waves into the reflected waves of the electric waves that have been reradiated or transmitted by each of the reradiation elements. When the N transmission antenna elements 113-1 to 113-N of the radar module 110 and the M reradiation elements 120-1 to 120-M of the reradiation section 120 are used, if the transmission of the transparent film is taken into account, it should be possible to separate into N x (M + 1) kinds of electric waves. For example, by using the reradiation section 120, it is possible to obtain the same effect as in the case where the number of transmission antennas in a MIMO (Multi Input Multi Output) radar is increased to (M + 1) times without changing the radar module 110, and it is possible to increase the virtual reception antenna number of the MIMO radar. Thus, it is possible to expand the aperture length of the virtual reception antenna of the MIMO radar, and it is possible to improve the angle measurement performance (angle measurement estimation accuracy or angle resolution for a plurality of objects).

[0088] The reradiation section 120 reradiates the electric waves radiated from the radar module 110, but does not reradiate the reflected signals received by the radar module 110. For example, for the reflected signals, the reradiation section 120 does not participate in the reception by the radar module 110 (i.e., is transparent). The reradiation elements 120-1 to 120-M are provided at positions at which the electric waves radiated from the radar module 110 are reradiated, but the reflected signals received by the radar module 110 are not reradiated.

[0089] Figure 2The illustrated radar module 110 has a radar transmission signal generation section 111, a wireless transmission section 112, a transmission antenna 113, a control section 114, a reception antenna 115, a wireless reception section 116, and a signal processing section 117. The radar transmission signal generation section 111, the wireless transmission section 112, and the transmission antenna 113 constitute a radar transmission section 118, and the reception antenna 115, the wireless reception section 116, and the signal processing section 117 constitute a radar reception section 119. The control section 114 can be included in the radar transmission section 118 or in the radar reception section 119.

[0090] The radar transmission signal is subjected to code multiplexing (CDM: Code Division Multiplexing) or time division multiplexing (TDM: Time Division Multiplexing) and transmitted from the radar module 110. The transmission signal transmitted from the radar module 110 is re-radiated by a re-radiation section 120 and reflected by a target 130, and received by the radar module 110. In Patent Literature 2, a structure in which a transmission signal is transmitted from a transmission antenna subjected to code multiplexing is described, and in Patent Literature 3, a structure in which a transmission signal is transmitted from a transmission antenna subjected to time division multiplexing is described. As described above, the structure in which a transmission signal is transmitted from a transmission antenna subjected to code multiplexing and the structure in which a transmission signal is transmitted from a transmission antenna subjected to time division multiplexing are known technologies, and therefore, in the following, the general structure of the radar transmission signal generation section 111, the wireless transmission section 112, the transmission antenna 113, the control section 114, the reception antenna 115, the wireless reception section 116, and the signal processing section 117 will be described.

[0091] The radar transmission signal generation section 111 generates a transmission signal. The radar transmission signal generation section 111 has, for example, a modulation signal generation section and a VCO (Voltage Controlled Oscillator). The modulation signal generation section generates a sawtooth-shaped modulation signal (for example, a modulation signal for VCO control) for each radar transmission period Tr. The VCO generates a frequency-modulated signal (hereinafter, for example, referred to as a frequency chirp signal or a chirp signal) based on the modulation signal output from the modulation signal generation section and outputs it to the wireless transmission section 112. The radar transmission signal generation section 111 can also generate a transmission signal using codes different in code sequence for each radar transmission period Tr.

[0092] The wireless transmission section 112 performs control for code multiplexing or time division multiplexing of the transmission signal.

[0093] The transmission antenna 113 has N transmission antenna elements 113-1 to 113-N. The transmission antenna 113 radiates a signal received from the wireless transmission section 112 to space. The structure of each of the transmission antenna elements 113-1 to 113-N can be the same or can include different structures.

[0094] The control section 114 controls the wireless transmission section 112, the signal processing section 117, and the re-radiation section 120.

[0095] The reception antenna 115 has L reception antenna elements 115-1 to 115-L at positions different from the transmission antenna elements 113-1 to 113-N. The reception antenna 115 receives a reflected signal reflected at a target. The reflected signal received in each reception antenna element is output to the wireless reception section 116.

[0096] The wireless reception section 116 has, for example, an amplifier, a detector. The wireless reception section 116 demodulates the reflected signal received by the reception antenna 115. The wireless reception section 116 outputs the demodulated reflected signal to the signal processing section 117.

[0097] The signal processing section 117 has an AD conversion section, an output switching section, a Doppler analysis section, and the like. The signal processing section 117 performs positioning of the target 130 based on the signal input from the wireless reception section 116, and outputs the result.

[0098] The re-radiation section 120 has a plurality of re-radiation elements 120-1 to 120-M. The structures of the re-radiation elements are the same, and at least one of the phase, the delay time, and the polarization of the electric wave re-radiated by each re-radiation element is different.

[0099] <Embodiment 1>

[0100] Figure 3 The radar module 110 illustrated has N transmission antenna elements. The re-radiation section 120 is located at a position physically spaced apart from the radar module 110, and has M re-radiation elements. The transmission signal radiated by each transmission antenna element is re-radiated by each re-radiation element of the re-radiation section 120, or is transmitted without being re-radiated by the re-radiation section 120, and reaches the target 130. For example, the transmission signal radiated from each transmission antenna element reaches the target 130 as M+1 kinds of transmission signals. For example, by the radar module 110 having N transmission antenna elements and the re-radiation section 120 having M re-radiation elements, N x (M+1) kinds of transmission signals reach the target 130. Therefore, it can be said that N x (M+1) transmission antennas are constituted as a MIMO radar. Here, N and M are each an integer of one or more.

[0101] As at least a part of the re-radiation section 120, a material such as a transparent film of a material having high electric wave transmittance is used, whereby the transmission signal radiated from each transmission antenna element 113-1 to 113-N can directly reach the target 130.

[0102] Further, the reradiation section 120 can be installed on a radar antenna cover that protects the radar module 110 (or the transmission antenna 113). For example, a structure in which the reradiation section 120 is installed on the inner side (antenna section side) of the radar antenna cover can be employed. By employing such a structure, not only the radar module 110 (or the transmission antenna 113) but also the reradiation section 120 can be protected by means of the radar antenna cover (the same effect can also be obtained in the following embodiments). For example, in a case where at least a part of the reradiation section 120 is composed of a material having high electric wave transmittance such as a transparent film, a structure in which the transparent film is attached on the inner side (on the surface opposite to the antenna section) of the radar antenna cover can be employed.

[0103] <Embodiment 2>

[0104] Figure 4 The illustrated radar module 110 has N transmission antenna elements. The reradiation section 120 is located at a position physically separated from the radar module 110 and has M reradiation elements. The transmission signals radiated from each transmission antenna element are radiated by each reradiation element of the reradiation section 120 to reach the target 130. For example, the transmission signals radiated from each transmission antenna element reach the target 130 as M kinds of transmission signals. For example, by the radar module 110 having N transmission antenna elements and the reradiation section 120 having M reradiation elements, N x M kinds of transmission signals reach the target 130. Therefore, it can be said that N x M transmission antennas are configured as a MIMO radar. Here, N is an integer of 1 or more, and M is an integer of 2 or more.

[0105] It can be understood that Embodiment 1 is a case where one of the reradiation elements is a transparent reradiation element (for example, a reradiation element that does not participate in any reradiation) in Embodiment 2 described above. Therefore, in the following description and the recitation of the scope of the right, the reradiation elements include the transparent reradiation element. The transparent reradiation element refers to a reradiation element that does not participate in reradiation and allows the electric wave radiated from the transmission antenna to be directly transmitted, including a state where the reradiation element does not exist and the electric wave is directly transmitted.

[0106] On the other hand, according to Embodiment 2, even if the reradiation elements are arranged on a member (for example, a substrate) composed of a material that blocks (does not transmit) electric waves, it is possible to increase the number of transmission antennas of the MIMO radar. For example, even if the substrate is composed of a material that blocks electric waves, as long as the reradiation elements receive the transmission signals radiated from the transmission antenna elements on the surface of one side of the substrate and radiate from the surface of the other side of the substrate.

[0107] <Embodiment 3>

[0108] On the other hand, as the re-radiation element in Embodiments 1 and 2, a metamaterial structure can be used. By employing a re-radiation element having a metamaterial structure, control of the phase, ON / OFF, or polarization conversion of the re-radiation element can be performed. For example, a phase control method using a metamaterial is proposed in Non-Patent Literature 1, and a polarization conversion technique using a metamaterial is proposed in Non-Patent Literature 2.

[0109] <Embodiment 4>

[0110] In Embodiments 1 and 3, the re-radiation element can also be formed on a transparent film. By forming the re-radiation element on a transparent film, the transparent film on which the re-radiation element is formed can be attached to a windshield, and thus the re-radiation element can be disposed without impairing the appearance.

[0111] <Embodiment 5>

[0112] Figure 5A a radiation direction in a case where the re-radiation element does not control the direction of a radiated signal, Figure 5B a radiation direction in a case where the re-radiation element controls the direction of a radiated signal.

[0113] In a case where the direction in which the re-radiation element radiates is not controlled, as shown in Figure 5A , there is a case where the re-radiation element radiates with directivity in which the direction from which the signal is received by the transmission antenna element is the maximum radiation direction. For example, in Figure 5A , the directivity of the re-radiation element 120-1 (#1) is tilted toward the positive direction of the z axis, and the directivity of the re-radiation element 120-M (#M) is tilted toward the negative direction of the z axis. In this case, since the maximum radiation direction of the re-radiation differs depending on the position of the re-radiation element, there is a case where the electric wave re-radiated from the re-radiation element is difficult to reach depending on the position of the target 130, and thus the performance of the MIMO radar is degraded, and it can be difficult to detect the target 130. In Figure 5B , by controlling the directivity of the re-radiation element 120-1 (#1) and the tilt of the directivity of the re-radiation element 120-M (#M) toward the z axis direction, each re-radiation element 120 can radiate along the x axis.

[0114] In Embodiments 1 to 4, in the case where the re-radiation elements control the direction of the radiated signal, it can be that the re-radiation elements radiate electric waves in the same direction as the maximum radiation direction of the directivity of the radiation of the transmission antenna element, that is, in the same directivity. By employing a metamaterial structure as the re-radiation elements to control the directivity, the re-radiation elements can radiate in the same direction as the maximum radiation direction of the directivity of the radiation of the transmission antenna element, that is, in the same directivity. Further, by employing a metamaterial structure as the re-radiation elements, it is also possible to individually adjust the directivity of the re-radiation elements. Since the maximum radiation directions of the directivity of the radiation of the transmission antenna element and each of the re-radiation elements are the same (for example, the directivities are the same), the electric waves radiated from all the re-radiation elements are reflected by the target 130 and received by the radar module 110, as a result, the aperture length of the virtual reception antenna of the MIMO radar is increased, so that the angle measurement performance can be improved, and the target 130 can be reliably detected. Further, in the above description, the case where the maximum radiation directions of the directivity of the radiation of the transmission antenna element and each of the re-radiation elements are the same is described, but it is not limited thereto, for example, by configuring each of the re-radiation elements with an element having a metamaterial structure, it is possible to control the maximum radiation direction of the directivity of the radiation of each of the re-radiation elements, so as to be different radiation directions, thereby expanding the field of view angle of the radar.

[0115] <Embodiment 6>

[0116] In Figure 6 , a radar device is shown in which the control section 114 is added to the radar module 110 described in Embodiments 1 to 5 to control the phase shifters included in the re-radiation elements 120-1 to 120-M. Figure 6 The control section 114 shown controls the phases of the re-radiation by each of the re-radiation elements so that the phases of the signals re-radiated by the re-radiation elements are orthogonal. The re-radiation elements include, for example, phase shifters. The control section 114 controls the phase shifters in such a manner as to impart a desired phase rotation to each of the re-radiation elements. The control section 114 controls in such a manner that the surface of the re-radiation element becomes a desired phase. The control section 114 controls the phases at which each of the re-radiation elements re-radiates in consideration of the phase difference due to the distance difference between the transmission antenna element and each of the re-radiation elements. By controlling in such a manner that the phases of the signals radiated by each of the re-radiation elements are orthogonal to each other, it is possible to separate the reflection signals of the signals radiated by each of the re-radiation elements reflected by the target 130.

[0117] By employing an element having a metamaterial structure as each of the re-radiation elements, the control section 114 can control the phase. Various structures have been proposed for phase control based on metamaterials, for example, a scheme like that of Non-Patent Literature 1 has been proposed.

[0118] The radar module 110 can use any of code multiplexing and time division multiplexing. In addition, the radar module 110 can also achieve the same effect using Doppler multiplexing.

[0119] (Modified example)

[0120] As shown in Figure 7 , in a case where a plurality of radar modules 110-1 and 110-2 are used, a comprehensive control section 140 is provided, which controls the control section 114 of each radar module 110. The radar module 110-1 has a transmission antenna element 113-1, and has corresponding re-radiation elements 120-1-1 to 120-1-M. The radar module can have a plurality of transmission antenna elements. It can be that the structures of the respective radar modules 110-1 and 110-2 are the same, or it can be that the respective radar modules have different numbers of transmission antenna elements or different numbers of reception antenna elements, or it can be that the re-radiation sections 120-1 and 120-2 contain different numbers of re-radiation elements. The comprehensive control section 140 performs phase control of each transmission antenna element 113-1-1 and 113-2-1, and each re-radiation element 120-1-1 to 120-1-M and 120-2-1 to 120-2-M of the respective radar modules 110-1 and 110-2. The radar device is provided with a number of re-radiation sections 120 corresponding to the number of the respective radar modules 110. In Figure 7 , one re-radiation section 120 is provided corresponding to one radar module 110, but it can also be that one re-radiation section 120 is provided corresponding to a plurality of radar modules 110. In addition, it can also be that the control section 114 of one radar module 110 (for example, the control section 114 of the radar module 110-1) functions as the comprehensive control section 140.

[0121] <Embodiment 7>

[0122] The re-radiation element 120-1 can be an RIS (Reconfigurable Intelligent Surface) configured by periodically arranging a plurality of elements 121 as shown in Figure 8A and Figure 8B . In the structure shown in Figure 8A , the transmission signal radiated from the transmission antenna element 113-1 is re-radiated by the re-radiation element 120-1, and the transmission signal radiated from the transmission antenna element 113-2 is re-radiated by the re-radiation element 120-2. In Figure 8BIn this case, each of the re-radiation elements 120-1, 120-2 is composed of, for example, 9 elements arranged in 3 x 3. The control section 114 causes different elements to be turned on depending on the time. For example, at time T = 1, the control section 114 sets the elements of the left and middle columns to be turned on and sets the elements of the right column to be turned off. For example, at time T = 2, the control section 114 sets the elements of the middle and right columns to be turned on and sets the elements of the left column to be turned off. The control section 114 causes the RIS pattern (state of each element) at time T = 1 and the RIS pattern at time T = 2 to appear alternately repeatedly. Each re-radiation section realizes a specific directivity by 6 elements in the turned-on state. The re-radiation elements are composed of a plurality of elements, and a directivity beam can be formed, so that an effect of increasing the directivity gain in a prescribed angular range can be obtained, and an effect of expanding the object detection range of the radar device can be obtained.

[0123] When the elements to be turned on among the plurality of elements change, the phase center of the RIS pattern composed of the turned-on elements changes. The phase center changes in a time-division manner, that is, the position of each re-radiation element changes in a time-division manner, so that it can be considered that the same effect as the operation of switching the transmission antenna in a time-division manner is obtained, and the number of transmission antennas of the MIMO radar is increased. Hereinafter, the re-radiation element obtained by causing a plurality of elements to operate in a time-division manner and in a manner that there is an overlap between each time will also be referred to as a virtual re-radiation element. The VE corresponding to each re-radiation element switched in a time-division manner is composed of each RIS pattern. In FIG. 8, the VE corresponding to the re-radiation element at time T = 1 is VE#1, and the VE corresponding to the re-radiation element at time T = 2 is VE#2. The positions of the phase centers of VE#1 and VE#2 are different.

[0124] The arrangement of the elements and the elements to be turned on are not limited to the example of FIG. 8. As long as the control section 114 causes the phase center to change in a time-division manner, it does not matter which arrangement of elements the control section 114 causes which elements to be turned on. The elements to be turned on can also have an overlap between each RIS pattern.

[0125] In addition, the directivity beam based on the virtual re-radiation elements VE#1, VE#2 when switched in a time-division manner can be a directivity beam having the same directivity in a time-division manner, or can be a directivity beam having different directivities in a time-division manner. Alternatively, beam control that changes the directivity beam in an adaptive manner can also be employed.

[0126] (Modified example 1)

[0127] In Figure 9A and Figure 9BIn the variation 1 shown, multiple transmit antenna elements radiate a code-multiplexed transmit signal, while the re-radiating elements switch the RIS pattern in a time-division manner. For example, the same RIS pattern is used for the duration of the code length when multiple transmit antenna elements transmit code-multiplexed signals. Multiple transmit antenna elements can also radiate a transmit signal that is not code-multiplexed but rather Doppler-multiplexed (DDM).

[0128] Figure 9A The multiple transmitting antenna elements 113-1 and 113-2 shown radiate, for example, a transmitted signal multiplexed with a code length of 2. For example, the code used in transmitting antenna element Tx1 is code [1, 1], and transmitting antenna element Tx1 repeatedly transmits a chirp signal as a reference (for example, transmitting 1, 1, 1, 1 from time 1 to 4). On the other hand, the code used in transmitting antenna element Tx2 is code [1, -1], and transmitting antenna element Tx2 alternately transmits a chirp signal with the same phase relative to the chirp signal as a reference (corresponding to code element 1) and a chirp signal with a phase difference of π (corresponding to code element -1) (for example, transmitting 1, -1, 1, -1 from time 1 to 4).

[0129] Therefore, at times T=1 and T=3, transmitting antenna element Tx1 transmits a chirped signal with phase 0 (reference phase), and transmitting antenna element Tx2 transmits a chirped signal with phase 0 (reference phase). At times T=2 and T=4, transmitting antenna element Tx1 transmits a chirped signal with phase 0 (reference phase), and transmitting antenna element Tx2 transmits a chirped signal with phase π (phase difference π relative to the reference phase).

[0130] In addition, such as Figure 9B As shown, for example, at times T=1 and T=2, control unit 114 sets the elements in the left and middle columns to be turned on, and sets the elements in the right column to be turned off. For example, at times T=3 and T=4, control unit 114 sets the elements in the middle and right columns to be turned on, and sets the elements in the left column to be turned off. Control unit 114 causes the states at times T=1 and T=2 and at times T=3 and T=4 to alternately repeat. Control unit 114 operates according to a period corresponding to the code length of the code used in the transmitting antenna element (for example, in...). Figure 9A The RIS pattern is switched over two cycles (in the middle), thereby implementing the function of multiplexing the virtual antenna. Figure 9B In the diagram, VE#1 is defined at times T=1 and T=2, and VE#2 is defined at times T=3 and T=4. The phase centers of VE#1 and VE#2 are located at different positions.

[0131] According to the present embodiment, for the transmission antenna elements that perform code multiplexing (or Doppler multiplexing), a common reradiation element can be used, the same effect as increasing the number of transmission antennas in a MIMO radar is obtained, and thus the number of reradiation elements can be reduced, the virtual number of reception antennas of the MIMO radar can be increased, and the aperture length can be expanded, and the angle measurement performance (angle estimation accuracy or angle resolution for multiple targets) can be improved. In addition, based on the effect of reducing the number of reradiation elements, the area for arranging the reradiation elements can be reduced, and the radar device can be miniaturized.

[0132] In addition, in the present embodiment, the virtual number of reception antennas of the MIMO radar can be increased in proportion to the number of transmission antenna elements that perform code multiplexing and the number of RIS patterns of the reradiation elements that perform time division multiplexing.

[0133] In addition, the directivity beams based on the virtual reradiation elements VE#1 and VE#2 at the time of time division switching can be directivity beams having the same directivity in a time division manner, or can be directivity beams having different directivity in a time division manner. Alternatively, beam control that changes the directivity beams in an adaptive manner can be employed.

[0134] (Variation 2)

[0135] In Variation 1, code multiplexing is performed by the transmission antenna elements, but in Variation 2 shown in FIGS. 12 and 13, code multiplexing is performed by the reradiation elements. Figure 10A and Figure 10B In Variation 2, the reradiation elements impart the beam forming phase of the reradiation elements and impart the phase for code multiplexing, and switch the RIS pattern in a time division manner. In Variation 2, the transmission antenna elements do not perform multiplexing of signals. In addition, instead of performing code multiplexing, the reradiation elements can impart phase rotation to perform Doppler multiplexing, and the same effect can be obtained.

[0136] The transmission signal (for example, a chirp signal) radiated from the transmission antenna element 113-1 is reradiated by the reradiation elements 120-1 and 120-2. For example, the code used in the transmission antenna element Tx1 is code [1, 1], and the transmission antenna element Tx1 repeatedly transmits a chirp signal as a reference. For example, the transmission signal radiated from the transmission antenna element 113-1 is not imparted with phase rotation for each transmission period (for example, times T = 1, T = 2) of the chirp signal.

[0137] First, the assignment of the phase for beamforming of the re-radiation elements will be described. The two re-radiation elements 120-1 and 120-2 are each composed of, for example, 15 elements arranged in 3 x 5. By control of the control section 114, the RIS pattern of each re-radiation element is changed in a time-division manner with a cycle of each time T. For example, at times T = 1, T = 2, the control section 114 sets the elements of the rightmost column to be off, and with respect to the remaining 4 columns of elements, virtual re-radiation elements VE#1 and VE#2 are formed from the left 2 columns and the right 2 columns, respectively. The virtual re-radiation element VE#1 of the left 2 columns is a virtual re-radiation element corresponding to the re-radiation element 120-1, and the virtual re-radiation element VE#2 of the right 2 columns is a virtual re-radiation element corresponding to the re-radiation element 120-2. At times T = 3, T = 4, the control section 114 sets the elements of the leftmost column to be off, and with respect to the remaining 4 columns of elements, virtual re-radiation elements VE#3 and VE#4 are formed from the left 2 columns and the right 2 columns, respectively. The virtual re-radiation element VE#3 of the left 2 columns is a virtual re-radiation element corresponding to the re-radiation element 120-1, and the virtual re-radiation element VE#4 of the right 2 columns is a virtual re-radiation element corresponding to the re-radiation element 120-2. The positions of the phase centers of VE#1 to VE#4 are different from each other.

[0138] In addition, the virtual re-radiation element VE#1 (or VE#2) based on each RIS pattern of the re-radiation elements at times T = 1, T = 2 is composed of, for example, 6 elements arranged in 3 x 2, and the phases Φ1 to Φ6 (or Φ7 to Φ12) of the plurality of elements are assigned to form a beam in a prescribed direction. With respect to the beams formed by the virtual re-radiation elements VE#1, VE#2, respectively, it is possible to form substantially the same directive beams, or it is possible to form directive beams having different main beam directions. In addition, the virtual re-radiation elements VE#3 (or VE#4) based on each RIS pattern of the re-radiation elements at times T = 3, T = 4 are likewise composed of, for example, 6 elements arranged in 3 x 2, and the phases Φ1 to Φ6 (or Φ7 to Φ12) of the plurality of elements are assigned to form a beam in a prescribed direction. In addition, the virtual re-radiation elements VE#1, VE#2, VE#3, VE#4 can form substantially the same directive beams, or can form directive beams having different main beam directions. By forming such directive beams using such a plurality of elements, it is possible to improve the directive gain, and thus it is possible to improve the received signal SNR (signal-to-noise power ratio) of the reflected wave from the target in the direction of the directive beam.

[0139] Next, the assignment of the phase for code multiplexing, which is performed at the same time as the assignment of the beamforming phase to the re-radiation element, will be described. For example, the virtual re-radiation element VE#1 (or VE#2) based on the RIS pattern of the re-radiation element at time T = 1, T = 2 further assigns a phase rotation based on a different code in addition to the beamforming phases Φ1 ~ Φ6 (or Φ7 ~ Φ12) of the plurality of elements, whereby it can be caused to re-radiate a signal subjected to code multiplexing (or Doppler multiplexing).

[0140] For example, the code used in the virtual re-radiation element VE#1 composed of 2 columns of elements on the left side is the code [1, 1] at time T = 1, T = 2. In this case, if a phase rotation is superimposed on the beamforming phase of the plurality of elements, the plurality of (6) elements respectively assign phase rotations of [Φ1, Φ1] ~ [Φ6, Φ6]. Thereby, with respect to a transmission signal (for example, a chirp signal) from the transmission antenna element 113-1 incident to the virtual re-radiation element, the virtual re-radiation element causes it to be a transmission signal (for example, a chirp signal) of phase 0 (no phase rotation is assigned, or a prescribed phase rotation as a reference phase is assigned), and produces a beam in a prescribed directivity beam pattern to re-radiate.

[0141] In addition, the code used in the virtual re-radiation element VE#2 composed of 2 columns on the right side is the code [1, -1] at time T = 1, T = 2. In this case, if a phase rotation is superimposed on the beamforming phase of the plurality of elements, the plurality of (6) elements respectively assign phase rotations of [Φ7, -Φ7] ~ [Φ12, -Φ12]. Thereby, with respect to each transmission signal (for example, a chirp signal) from the transmission antenna element 113-1 incident to the virtual re-radiation element, the virtual re-radiation element respectively causes it to be a transmission signal (for example, a chirp signal) of phase 0 (no phase rotation is assigned, or a prescribed phase rotation as a reference phase is assigned) and phase π (a phase rotation of which the phase difference from the phase at the time of "phase 0" is π is assigned), and produces a beam in a prescribed directivity beam pattern to re-radiate.

[0142] In addition, the virtual re-radiation element VE#3 (or VE#4) based on each RIS pattern of the re-radiation element at time T = 3, T = 4 also similarly further assigns a phase rotation based on a different code in addition to the beamforming phases Φ1 ~ Φ6 (or Φ7 ~ Φ12) of the plurality of elements, whereby it can be caused to re-radiate a signal subjected to code multiplexing (or Doppler multiplexing).

[0143] The control unit 114 alternately repeats the states at times T=1, T=2 and T=3, T=4. The resulting signals, multiplexed by both code and time, are orthogonal, allowing the reflected waves from the target to be separated and received at the radar receiver. Therefore, through the reradiating element, the signal is beamformed based on the RIS patterns of the virtual reradiating element and reradiated by code multiplexing (in... Figure 10B In the example, the re-radiated signal is for two RIS patterns, with a code multiplexing number of 2. Furthermore, the RIS pattern follows a period corresponding to the code length (in...). Figure 10A In the middle, there are 2 transmission cycles) subject to time division (in Figure 10B In this configuration, two RIS patterns are switched in a time-division manner every two transmission cycles, resulting in a time multiplexing number of 2. By combining such code multiplexing and time multiplexing in the control unit's control of the re-radiating element, the same effect as increasing the number of transmitting antennas in the radar to (code multiplexing number × time multiplexing number) times can be achieved, thus increasing the number of virtual receiving antennas in the MIMO radar. Consequently, the aperture length of the virtual receiving antennas in the MIMO radar can be increased, improving angle measurement performance (angle estimation accuracy or angular resolution for multiple targets).

[0144] If, as shown in Figures 8 and 9, nine elements are assigned to each re-radiating element, then two re-radiating elements 120-1 and 120-2 would consist of 18 elements. However, if 15 elements are used, with combination code multiplexing and time multiplexing used to construct two re-radiating elements 120-1 and 120-2, the number of elements can be reduced. Multiple elements can also be assigned to three or more re-radiating elements. For example, for K re-radiating elements, there could be 3 × (2K+1) elements. Similarly, in Embodiment 7 and its variation 1, since each re-radiating element performs the same operation, multiple re-radiating elements can be constructed using N elements.

[0145] Furthermore, when switching in a time-division manner, the directional beams based on virtual reradiating elements VE#1 to #4 can be divided into directional beams with the same directionality in a time-division manner, or they can be divided into directional beams with different directionalities in a time-division manner. Alternatively, beam control that adaptively changes the directional beams can also be used.

[0146] (Variation Example 3)

[0147] In Variation Example 2, an example is shown where the number of transmit antennas is one and the transmit antenna elements are not multiplexed for transmission. Figure 11A and Figure 11BThe modification example 3 is an example in which the following content is added to the modification example, that is, the content that the re-radiation elements re-radiate the transmission signals subjected to code multiplexing by the plurality of transmission antenna elements. In the modification example 3, for the transmission signals subjected to code multiplexing from the plurality of transmission antenna elements, the re-radiation elements impart the beam forming phase of the re-radiation elements and impart the phase for code multiplexing, and switch the RIS pattern in a time division manner. In addition, instead of code multiplexing, the re-radiation elements can impart phase rotation to become Doppler multiplexing to perform Doppler multiplexing, and the same effect can be obtained. Furthermore, instead of code multiplexing, the transmission antenna elements can impart phase rotation to become Doppler multiplexing to perform Doppler multiplexing, and the same effect can be obtained.

[0148] The plurality of transmission antenna elements radiate signals subjected to code multiplexing. For example, the code used in the transmission antenna element Tx1 is the code [1, 1, 1, 1], and the transmission antenna element Tx1 repeatedly transmits the chirp signal as a reference. On the other hand, the code used in the transmission antenna element Tx2 is the code [1, 1, -1, -1], and the transmission antenna element Tx2 repeatedly transmits the chirp signals of phases 0, 0, π, π in that order. Here, the signal of phase 0 is a chirp signal of the same phase with respect to the chirp signal as a reference (corresponding to the code element 1), and the signal of phase π is a chirp signal having a phase difference of π with respect to the chirp signal as a reference (corresponding to the code element -1).

[0149] For example, at times T = 1, T = 2, the transmission antenna element Tx1 transmits the chirp signal of phase 0, and the transmission antenna element Tx2 transmits the chirp signal of phase 0, and at times T = 3, T = 4, the transmission antenna element Tx1 transmits the chirp signal of phase 0, and the transmission antenna element Tx2 transmits the chirp signal of phase π. Thus, from the 2 transmission antenna elements Tx1 and Tx2, code multiplexing (code multiplexing number 2) is performed using an orthogonal code of code length 4.

[0150] The transmission signals (for example, chirp signals) radiated from the transmission antenna elements 113-1 and 113-2 are re-radiated by the re-radiation elements 120-1 and 120-2.

[0151] The 2 re-radiation elements 120-1, 120-2 are constituted by, for example, 15 elements arranged in 3 x 5. The RIS pattern of each re-radiation element is time-divided. For example, at T = 1 to 4, the control section 114 sets the elements of the rightmost column to be off, and with respect to the remaining 4 columns of elements, virtual re-radiation elements VE#1, VE#2 are constituted by the left 2 columns and the right 2 columns, respectively. At T = 5 to 8, the control section 114 sets the elements of the leftmost column to be off, and with respect to the remaining 4 columns of elements, virtual re-radiation elements VE#3, VE#4 are constituted by the left 2 columns and the right 2 columns, respectively. The positions of the phase centers of VE#1 to VE#4 are different from each other.

[0152] In addition, the virtual re-radiation element VE#1 (or VE#2) based on the RIS pattern of the re-radiation element at time T = 1 to 4 is constituted by, for example, 6 elements arranged in 3 x 2, and a beam forming phase Φ1 to Φ6 (or Φ7 to Φ12) of the plurality of elements is imparted to form a beam in a prescribed direction. With respect to the beams formed by the virtual re-radiation elements VE#1, VE#2, respectively, it can be a substantially same directive beam, or it can be a directive beam having a different main beam direction. In addition, the virtual re-radiation elements VE#3 (or VE#4) based on the RIS pattern of the re-radiation element at time T = 5 to 8 is also similarly constituted by, for example, 6 elements arranged in 3 x 2, and a beam forming phase Φ1 to Φ6 (or Φ7 to Φ12) of the plurality of elements is imparted to form a beam in a prescribed direction. In addition, the virtual re-radiation elements VE#1, VE#2, VE#3, VE#4 can form a substantially same directive beam, or can form a directive beam having a different main beam direction. By forming such a directive beam using such a plurality of elements, the directivity gain can be improved, and thus the received signal SNR (signal to noise power ratio) of the reflected wave from the target in the direction of the directive beam can be improved.

[0153] In addition, the virtual re-radiation element VE#1 (or VE#2) based on the RIS pattern of the re-radiation element at time T = 1, T = 2 (or time T = 3, T = 4) is further imparted with a phase rotation based on a different code in addition to the beam forming phase Φ1 to Φ6 (or Φ7 to Φ12) of the plurality of elements, and thus can be configured to re-radiate a signal subjected to code multiplexing (or Doppler multiplexing).

[0154] For example, the code used in the virtual re-radiation element VE#1 constituted by 2 columns of elements on the left side is the code [1, 1] at time T = 1, T = 2 (or time T = 3, T = 4). In this case, if a phase rotation is superimposed on the beam forming phase of the plurality of elements, the plurality (6) of elements impart a phase rotation of [Φ1, Φ1] to [Φ6, Φ6], respectively. Thus, with respect to the transmission signal (for example, a chirp signal) from the transmission antenna elements 113-1 and 113-2 incident on the virtual re-radiation element, the virtual re-radiation element re-radiates it as a transmission signal (for example, a chirp signal) having a phase of 0 (no phase rotation is imparted, or a prescribed phase rotation is imparted as a reference phase), and forms a beam in a prescribed directive beam pattern.

[0155] In addition, the code used in the virtual re-radiation element VE#2 composed of the elements of the right 2 columns is the code [1, -1] at the time T = 1, T = 2 (or the time T = 3, T = 4). In this case, if the phase rotation is overlapped on the beamforming phase using the plurality of elements, the plurality (6) of elements respectively impart the phase rotations of [Φ7, -Φ7] ~ [Φ12, -Φ12]. Thereby, with respect to each transmission signal (for example, a chirp signal) from the transmission antenna elements 113-1 and 113-2 incident to the virtual re-radiation element, the virtual re-radiation element sets it to the transmission signal (for example, a chirp signal) of the phase 0 (no phase rotation is imparted, or a prescribed phase rotation as a reference phase is imparted) and the phase π (a phase rotation of which the phase difference from the phase at the time of the phase 0 is π is imparted) respectively, and produces a beam in a prescribed directivity beam pattern to re-radiate.

[0156] In addition, the virtual re-radiation element VE#3 (or VE#4) of each RIS pattern of the re-radiation element based on the time T = 5, T = 6 (or the time T = 7, T = 8) also similarly, further imparts a phase rotation based on a different code in addition to the beamforming phases Φ1 ~ Φ6 (or Φ7 ~ Φ12) using the plurality of elements, whereby it can be set to a signal subjected to code multiplexing (or Doppler multiplexing) to re-radiate.

[0157] The control section 114 alternately repeats the state of the time T = 1 ~ 4 and the state of the time T = 5 ~ 8. The signal obtained in this way, which is subjected to code multiplexing with respect to the transmission antenna elements and code multiplexing and time multiplexing of the virtual re-radiation element, is a mutually orthogonal signal, and the reflected wave from the target can be received separately in the radar receiving section.

[0158] Therefore, by the re-radiation element, the signal is beamformed based on each RIS pattern of the virtual re-radiation element, and is re-radiated subjected to code multiplexing (in Figure 11B , the number of code multiplexing of the virtual re-radiation element is 2 for the re-radiation signal of 2 RIS patterns). In addition, the RIS pattern is subjected to time division (in Figure 11A , 4 transmission periods) with a period corresponding to the code length of the code multiplexing with respect to the plurality of transmission antenna elements (in Figure 11BIn this case, the two RIS patterns are switched in a time-division manner at every 4 transmission periods, and thus the number of time multiplexing is 2). By the control action of the control section that combines the code multiplexing of the transmission antenna elements and the code multiplexing and time multiplexing of the re-radiation elements, the same effect as the case where the number of transmission antennas in the radar is increased to (transmission antenna multiplexing number x code multiplexing number of re-radiation elements x time multiplexing number) times can be obtained, and the virtual reception antenna number of the MIMO radar can be increased. Thus, the aperture length of the virtual reception antenna of the MIMO radar can be expanded, and the angle measurement performance (angle measurement estimation accuracy or angle resolution for a plurality of targets) can be improved.

[0159] In addition, the directivity beam based on the virtual re-radiation elements VE#1 to VE#4 at the time of time-division switching can be directivity beams having the same directivity in a time-division manner, or can be directivity beams having different directivity in a time-division manner. Alternatively, the beam control can also be changed in an adaptive manner so as to change the directivity beam.

[0160] For example, the transmission antenna elements radiate the transmission signal subjected to code multiplexing. The re-radiation elements re-radiate the signal subjected to code multiplexing, and the RIS pattern is switched in a time-division manner at a period corresponding to the code length of the code multiplexing. In addition, a plurality of elements can be provided corresponding to three or more re-radiation elements.

[0161] In Embodiment 7, the number of virtual antennas is increased by combining the multiplexing methods, and thus the positioning performance of the radar device for a target, particularly the angle measurement performance (angle measurement estimation accuracy or angle resolution for a plurality of targets), can be improved, but the Doppler detection range can be reduced because a plurality of chirp signals are transmitted. In the case where the Doppler detection range of the target to be assumed is a wide range, the influence of the reduction in the Doppler detection range can be suppressed by shortening the transmission period of the chirp signal. The control section 114 can select which of Embodiment 7 and the modified examples 1 to 3 of Embodiment 7 is to be used in accordance with the angle measurement performance and the Doppler detection performance. In addition, the control section 114 can also switch the method of Embodiment 7 and the modified examples 1 to 3 of Embodiment 7, for example, in accordance with the vehicle speed. In the case where the vehicle speed is high, the angle measurement performance can be improved by using the method of Embodiment 7 or the modified examples 1 to 3 of Embodiment 7. Figure 10B 、 Figure 11B In Embodiment 7, a plurality of re-radiation elements are arranged in the column direction, but a plurality of re-radiation elements can not be arranged in the column direction, but can be arranged in the row direction or in both the row direction and the column direction. For example, an RIS pattern in which the elements arranged in 7 x 5 are made to correspond to four re-radiation elements and the phase center of the re-radiation elements is moved in the column direction can be used. In addition, the elements constituting one re-radiation element can not be 3 x 2.

[0162] <Embodiment 8>

[0163] Embodiment 8 is an embodiment in which the re-radiation elements re-radiate the delay produced at different times. In Figure 12 In Embodiment 8 shown in the drawing, the signals transmitted by the respective re-radiation elements are separated by different time delays.

[0164] In Figure 13 , the transmission antenna elements re-radiate the chirp signals transmitted by the transmission antenna elements at different times. r The transmission time T c of the chirp signals transmitted by the transmission antenna elements is varied.

[0165] In the respective re-radiation elements, the chirp signals radiated by the transmission antenna elements are re-radiated with delays of T i (T i is shorter than T i+1 ). The delay time T i in the respective re-radiation elements is shorter than the transmission time T c of the chirp signals radiated by the transmission antenna elements. In addition, the difference ΔT=T i+1 -T i is larger than the TOF (Time of Flight) of the radar device when detecting a target in the maximum detection range R (for example, 2R / c (c is the speed of light)). For example, ΔT>2R / c. In addition, in the case where the re-radiation elements are made of a transparent film or the like, the transmission signals from the transmission antenna are transmitted, so in this case, the delay time T0 is T0=0 (the transmission start timing of the chirp signal), and T1 is set to be larger than the TOF of the maximum detection range.

[0166] In addition, in Embodiment 8, the chirp signals radiated by the respective re-radiation elements can be transmitted with different delay time differences by making the distances between the transmission antenna elements and the respective re-radiation elements different. If the chirp signals radiated by the re-radiation section are provided with time differences by making the distances between the respective transmission antenna elements and the respective re-radiation elements different, the control of the re-radiation elements by the control section 114 can be omitted.

[0167] Figure 14The radar receiving section 119 described in the embodiment can be combined with the multiplexing method based on code multiplexing (or also Doppler multiplexing) and time division multiplexing described in Embodiment 7. The radar receiving section 119 has the receiving antenna elements 115-1 to 115-Na, the antenna system processing sections 1401-1 to 1401-Na, a CFAR (Constant False Alarm Rate) section 1408, and a direction estimation section 1409. The antenna system processing sections 1401-1 to 1401-Na correspond to the receiving antenna elements 115-1 to 115-Na. Each of the antenna system processing sections 1401-1 to 1401-Na has the same structure. The antenna system processing section 1401-1 has the wireless receiving section 116 and the signal processing section 117. The wireless receiving section 116 has a mixer section 1402 and an LPF (Low Pass Filter) 1403. The signal processing section 117 has an AD conversion section 1404, a beat analysis section 1405, a distance separation section 1406, and Doppler analysis sections 1407-1 to 1407-Loc.

[0168] The mixer section 1402 receives the outputs of the receiving antenna element 115-1 and the VCO, and outputs the mixed outputs to the LPF 1403.

[0169] The LPF 1403 extracts the beat signal included in the baseband frequency band of the signal input from the mixer section 1402, and outputs to the AD conversion section 1404.

[0170] The AD conversion section 1404 samples and quantizes the signal input from the LPF 1403, converts to a digital signal, and outputs to the beat analysis section 1405.

[0171] The beat analysis section 1405 performs frequency analysis on the beat signal as the output of the AD conversion section 1404 for each transmission cycle. In the output of the beat analysis section 1405, the reflected signals received from each of the re-radiation elements are separated for each distance block RB. Since the difference in the time delayed in each of the re-radiation elements is larger than the TOF when detecting the target in the maximum detection range R at the time of performing the re-radiation of the signal, the signal reflected at the target can be received as separated for each of the re-radiation elements. Here, the distance (distance detected in the radar) AR of the distance block RB is a distance that can be detected from the time difference in the delay time by each of the re-radiation elements. For example, AR (T i+1 , T i ) = (T i+1 -T i ) x c / 2 > R. The delay time TO by the transparent re-radiation element (#0) is TO = 0. Figure 15is a diagram illustrating an outline of the reception signals from the transmission (Tx) antenna and the re-radiation elements #1 to #M and their separation in the output of the beat analysis section 1405. The beat analysis section 1405 outputs the reception signals from the re-radiation elements #1 to #M in a state of being separated into M different distance blocks RB each (in the case of including the reception signal from the transmission antenna, into M+1 distance blocks RB. Figure 15

[0172] The distance separation section 1406 outputs each reflection signal separated by the distance block RB received from the beat analysis section 1405 to the Doppler analysis sections 1407-1 to 1407-Loc as a distance from the start point of each distance block RB. If the number of re-radiation elements is M and the number of transmission antenna elements is N, the number of Doppler analysis sections Loc is M x N (in the case of including the transmission antenna element, Loc = (M+1) x N). For example, for the transmission signal radiated from the transmission antenna #1, RB #0 is output to the Doppler analysis section 1407-1 and RB #1 is output to the Doppler analysis section 1407-2.

[0173] Each Doppler analysis section 1407-1 to 1407-Loc performs Doppler analysis on the reflection signal of the distance block RB input from the distance separation section 1406.

[0174] The CFAR section 1408 uses the outputs of the Loc Doppler analysis sections 1407-1 to 1407-Loc to perform threshold determination in an adaptive manner, and extracts the distance index and the Doppler frequency index that give a peak signal.

[0175] The direction estimation section 1409 uses the outputs from the Loc Doppler analysis sections 1407-1 to 1407-Loc corresponding to the distance index and the Doppler frequency index that give a peak signal extracted by the CFAR section 1408 to perform direction estimation processing of a target, and outputs the azimuth or elevation angle of the target as angle measurement information together with the distance information and the Doppler information of the distance index and the Doppler frequency index as a positioning result.

[0176] (Modified Example 1)

[0177] Figure 16 In Modified Example 1 of Embodiment 8 illustrated above, the on / off of the switch included in the re-radiation element is performed. For example, each re-radiation element re-radiates the transmission signal radiated from the transmission antenna element during the on period of the switch, and does not re-radiate during the off period of the switch.

[0178] As Figure 17 ​As shown, the switching of each re-radiation element is controlled by the control unit 114, and they are turned on sequentially. Each re-radiation element is activated at delays T1 to T2. M It then enters the conducting state, re-radiating the transmitted signal radiated from the transmitting antenna element.

[0179] (Variation Example 2)

[0180] Figure 18 In variation 2 of embodiment 8 shown, the beam of the transmitted signal radiated by the transmitting antenna element is narrowed and sequentially illuminated by the re-radiating elements. The transmitting antenna element controls the timing of the transmission of the transmitted signal to each re-radiating element. The re-radiating element controls its directivity (beam) during re-radiation. The signals radiated by all the re-radiating elements have the same directivity.

[0181] <Implementation Method 9>

[0182] Figure 19 The radar device of Embodiment 9 shown is based on Embodiments 1 to 8, in which each reradiating element converts the polarization of the radiation into mutually orthogonal polarizations (e.g., vertical / horizontal polarization, right-hand circular / left-hand circular polarization). The polarization conversion unit can convert the polarization in a fixed manner, or it can switch the polarization of the radiation according to the control from the control unit 114. For example, reradiating element 120-1 converts the polarization of the transmitted signal (e.g., vertical polarization) into an orthogonal polarization (e.g., horizontal polarization) and reradiates, while reradiating element 120-2 (which includes a transparent reradiating element) does not convert the polarization of the transmitted signal and reradiates. For example, reradiating element 120-1 converts the transmitted signal into right-hand circular polarization and reradiates, while reradiating element 120-2 converts the received transmitted signal into left-hand circular polarization and reradiates.

[0183] Figure 20A This is a diagram representing vertical polarization. Figure 20B It is a diagram representing horizontal polarization. Figure 20C This is a diagram representing right-handed circular polarization. Figure 20D It is a diagram representing left-handed circular polarization.

[0184] <Implementation Method 10>

[0185] Regarding implementation method 10, using Figure 21 This describes a vehicle equipped with the radar module 110 and the re-radiation unit 120 described in embodiments 1 to 9.

[0186] The radar module 110 is located inside the vehicle's roof at the front. For example, as... Figure 22 and Figure 23 As shown, radar module 110 can be a thin radar device with a thin end-fire array antenna (e.g., Patent Documents 4 and 5).

[0187] In the thin radar device, a circuit board 2201, a signal processing IC 2202, a connector 2203, and transceiving antennas 113, 115 are arranged in a main body constituted by a housing 2207 and a dielectric lens 2204 arranged at a window portion 2205 of the housing 2207. The window portion 2205 is a region of the housing 2207 through which an electric wave can be transmitted.

[0188] The signal processing IC 2202 arranged on the circuit board 2201 performs processing of a transmission signal 2206 transmitted from the transceiving antennas 113, 115 constituted by a plurality of antenna elements, and a reception signal received by the transceiving antennas, and communicates with an external device such as a vehicle ECU via the connector 2203. The transceiving antennas 113, 115 are arranged at a position that becomes a focal point of the dielectric lens 2204. The dielectric lens 2204 converts a beam of the electric wave of the transmission signal 2206 into a plane wave by reducing the beam, radiates the plane wave to a front region (x2 axis direction) outside the device, and condenses a received reflection signal to the transceiving antennas 113, 115. The signal processing IC 2202 can be constituted by a millimeter wave band IC 2202-1 and a baseband band IC 2202-2.

[0189] The re-radiation portion 120 is constituted, for example, on a transparent film along the z1y1 plane. By providing the re-radiation portion 120 as a re-radiation portion in which a re-radiation element is arranged on a transparent film, the re-radiation element can be arranged at an arbitrary position on the windshield. In addition, as shown in FIG. 12, the x1 axis on which the re-radiation portion 120 is arranged and the x2 axis on which the radar module 110 is arranged can not be parallel. Figure 21

[0190] The control of the re-radiation element on the transparent film is performed from the control portion 114 in the radar module 110. The control portion 114 and the re-radiation element can communicate using a transparent electrode or the like on the transparent film.

[0191] Even in the case of using a radar module in which the resolution in the vertical direction (z2 axis direction) is low, by being combined with the re-radiation element, it is possible to improve the resolution in the vertical direction.

[0192] In the above-described embodiments, the expression "device" used for each structural element can be replaced with other expressions such as "circuitry", "assembly", "equipment", "unit", or "module".

[0193] ​The present disclosure can be realized by software, hardware, or software in cooperation with hardware. Each functional block used in the description of the aforementioned embodiments can also be realized by an LSI that is an integrated circuit, or a portion thereof, each process described in the aforementioned embodiments can also be controlled by one LSI or a combination of LSIs, partially or entirely. The LSI can be constructed of a dedicated circuit for each function, or can be constructed of one chip that includes a part or all of the functional blocks. The LSI can include a data input and output coupled thereto. The LSI is sometimes referred to as "IC", "system LSI", "super LSI" or "ultra LSI" depending on a difference in the degree of integration. Moreover, the method of circuit integration is not limited to the LSI, and implementation by using dedicated circuitry or general purpose processors, or by using a newly developed integrated circuit that replaces the LSI, is also possible.

[0194] The method of circuit integration is not limited to LSIs, and implementation by using dedicated circuitry, or by using a general purpose processor that performs the functions by means of software is also possible. In the following description, the possibility of hardware implementation is not excluded even when the term "circuitry" is used.

[0195] Further, the method of circuit integration is not limited to LSIs, and implementation by using consumer electronic appliances, computer appliances, or detachable semiconductor chips are also possible. In the following description, the possibility of hardware implementation is not excluded even when the term "circuitry" is used.

[0196] (1) A radar device of one embodiment of the present disclosure includes a radar module including a transmission antenna that transmits a transmission signal, and a re-radiation unit including a re-radiation element that re-radiates the transmission signal.

[0197] (2) A radar device of one embodiment of the present disclosure includes the radar device of (1), in which the re-radiation unit includes at least two re-radiation elements.

[0198] (3) A radar device of one embodiment of the present disclosure includes the radar device of (2), in which at least one of the re-radiation elements is a transparent re-radiation element.

[0199] (4) A radar device of one embodiment of the present disclosure includes the radar device of (1), in which the re-radiation element includes a material having a metamaterial structure.

[0200] (5) A radar device of one embodiment of the present disclosure includes the radar device of (1), in which the re-radiation element is provided on a transparent film.

[0201] (6) The radar device of one embodiment of the present disclosure is the radar device of (4), in which the element having a metamaterial structure controls the directivity of the reemitted reemitted signal.

[0202] (7) The radar device of one embodiment of the present disclosure is the radar device of (2), in which the reemitting elements each reemit orthogonal reemitted signals.

[0203] (8) The radar device of one embodiment of the present disclosure is the radar device of (7), in which the reemitting elements delay the reemitted transmitted signals.

[0204] (9) The radar device of one embodiment of the present disclosure is the radar device of (8), further comprising a control portion that controls the reemitting elements to delay the transmitted signals.

[0205] (10) The radar device of one embodiment of the present disclosure is the radar device of (9), comprising a plurality of the radar modules and a plurality of the reemitting portions, and the control portion controls the plurality of the radar modules and the plurality of the reemitting portions.

[0206] (11) The radar device of one embodiment of the present disclosure is the radar device of (1), in which the reemitting portion includes reemitting elements each including a plurality of elements having a metamaterial structure, and the radar device further comprises a control portion that controls the on and off of the plurality of elements in a time-division manner.

[0207] (12) The radar device of one embodiment of the present disclosure is the radar device of (4), in which the reemitting portion includes reemitting elements each including a plurality of elements having a metamaterial structure, and the reemitting elements each including a plurality of elements having a metamaterial structure form a prescribed beam and output.

[0208] (13) The radar device of one embodiment of the present disclosure is the radar device of (11), in which the transmitting antenna includes a plurality of transmitting antenna elements, and the plurality of transmitting antenna elements transmit transmitted signals subjected to code multiplexing or Doppler multiplexing.

[0209] (14) The radar device of one embodiment of the present disclosure is the radar device of (11) or (12), in which the transmitting antenna includes a plurality of transmitting antenna elements, and the element having a metamaterial structure code-multiplexes or Doppler-multiplexes the reemitted reemitted signal.

[0210] (15) The radar device of one embodiment of the present disclosure is the radar device of (11) or (12), in which the transmission antenna has a plurality of transmission antenna elements, the plurality of transmission antenna elements transmit transmission signals subjected to Doppler multiplexing, and the elements each having a metamaterial structure code-multiplexes the re-radiated re-radiation signals.

[0211] (16) The radar device of one embodiment of the present disclosure is the radar device of (14) or (15), in which the re-radiation unit has at least two re-radiation elements each composed of a plurality of the elements each having a metamaterial structure.

[0212] (17) The radar device of one embodiment of the present disclosure is the radar device of (8), in which the transmission signal is a chirp signal and the delay is a delay based on a maximum detection range of the radar device.

[0213] (18) The radar device of one embodiment of the present disclosure is the radar device of (17), in which the re-radiation unit has a plurality of re-radiation elements, the transmission signal is a chirp signal, and a time difference between times at which the transmission signal is delayed by two of the re-radiation elements is greater than twice a value obtained by dividing the maximum detection range of the radar device by the speed of light.

[0214] (19) The radar device of one embodiment of the present disclosure is the radar device of (18), in which the radar module separates, based on the delay, a reflection signal reflected by a target from a re-radiation signal re-radiated by each of the re-radiation elements.

[0215] (20) The radar device of one embodiment of the present disclosure is the radar device of (9), in which the re-radiation unit has a switch corresponding to each of the re-radiation elements, and the control unit controls the switch to delay the transmission signal.

[0216] (21) The radar device of one embodiment of the present disclosure is the radar device of (7), in which the re-radiation unit has a plurality of re-radiation elements, and the transmission antenna changes directivity to sequentially radiate the transmission signal to the plurality of re-radiation elements.

[0217] (22) The radar device of one embodiment of the present disclosure is the radar device of (2), in which the plurality of re-radiation elements re-radiate the transmission signal using polarizations orthogonal to each other.

[0218] (23) A vehicle is mounted with the radar device of (1).

[0219] (24) The vehicle of one embodiment of the present disclosure is, in the vehicle of (23), the radar module is provided on a roof of the vehicle, and the reradiation portion is provided on a windshield of the vehicle.

[0220] While the various embodiments have been described above, it should be apparent that a large number of modifications can be made without departing from the spirit of the disclosure and the general scope of equivalents of the embodiments. It should also be appreciated that these modifications are within the scope of the disclosure.

[0221] The disclosure content of the specification, drawings, and abstract of the description included in Japanese Patent Application No. 2024-090848, filed on June 4, 2024, is incorporated herein by reference in its entirety.

[0222] Industrial applicability

[0223] The present disclosure is useful for a radar device and a vehicle.

Claims

1. A radar device, characterized by Possessing: a radar module having a transmission antenna that transmits a transmission signal; and a re-radiation section having at least one re-radiation element that re-radiates the transmission signal as a re-radiation signal.

2. The radar device according to claim 1, wherein at least one of the at least one re-radiation element is a transparent re-radiation element.

3. The radar device according to claim 1, wherein the re-radiation element is composed of an element having a metamaterial structure.

4. The radar device according to claim 1, wherein the re-radiation element is disposed on a transparent film.

5. The radar device according to claim 3, wherein the element having the metamaterial structure controls the directivity of the re-radiation signal.

6. The radar device according to claim 1, wherein the first re-radiation signal based on a first re-radiation element of the at least one re-radiation element is orthogonal to the second re-radiation signal based on a second re-radiation element of the at least one re-radiation element.

7. The radar device according to claim 1, further possessing a control section that controls the re-radiation signal to be delayed by the re-radiation element.

8. The radar device according to claim 7, wherein the radar module is a plurality of radar modules, the re-radiation section is a plurality of re-radiation sections, the control section controls the plurality of radar modules and the plurality of re-radiation sections.

9. The radar device according to claim 3, wherein the re-radiation section has a re-radiation element composed of a plurality of elements having a metamaterial structure, and the radar device further possesses a control section that controls the on and off of a plurality of the elements having a metamaterial structure in a time-division manner.

10. The radar device according to claim 3, wherein the re-radiation section has a re-radiation element composed of a plurality of elements having a metamaterial structure, and the re-radiation element composed of a plurality of elements having a metamaterial structure forms a prescribed beam and outputs.

11. The radar device according to claim 9 or 10, wherein the transmission antenna has a plurality of transmission antenna elements, a plurality of the transmission antenna elements transmit transmission signals subjected to code multiplexing or Doppler multiplexing.

12. The radar device according to claim 9 or 10, wherein the transmission antenna has a plurality of transmission antenna elements, the element having a metamaterial structure code-multiplexes or Doppler-multiplexes the re-radiation signal.

13. The radar device according to claim 7, wherein the transmission signal is a chirp signal, the delay is a delay based on a maximum detection range of the radar device.

14. The radar device according to claim 13, wherein the re-radiation section has a plurality of re-radiation elements, the transmission signal is a chirp signal, a time difference in time at which the re-radiation signal is delayed between two of the re-radiation elements is greater than 2 times a value obtained by dividing the maximum detection range of the radar device by the speed of light.

15. The radar device according to claim 14, wherein ​ The radar module separates the reflection signal of the transmission signal reflected by the target from the re-radiation signal of the re-radiation element based on the delay.

16. The radar apparatus according to claim 7, wherein The re-radiation section has a switch corresponding to the re-radiation element, The control section controls the switch to delay the re-radiation signal.

17. The radar apparatus according to claim 1, wherein The re-radiation section has a plurality of re-radiation elements, The transmission antenna changes the directivity to sequentially radiate the transmission signal to the plurality of re-radiation elements.

18. The radar apparatus according to claim 1, wherein The plurality of re-radiation elements re-radiate the transmission signal using polarizations orthogonal to each other.

19. A vehicle characterized by comprising The radar apparatus according to claim 1.

20. The vehicle according to claim 19, wherein The radar module is provided on a roof of the vehicle, The re-radiation section is provided on a windshield of the vehicle.

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