Radar apparatus and vehicle

Abstract

To provide a radar apparatus capable of improving calculation accuracy for a position of a target, and a vehicle.SOLUTION: The radar system comprises: a radar module including a transmission antenna for transmitting a transmission signal; and a re-radiation part including a re-radiation element for re-radiating the transmission signal.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Further research is being conducted into improving vertical and horizontal resolution in order to realize imaging functions (image acquisition) in radar equipment. It is generally known that narrowing the beam improves object separation performance and that narrowing the beam can achieve high resolution, and that increasing the antenna aperture is sufficient to narrow the beam. Known methods for increasing the antenna aperture include increasing the number of antennas and placing antennas at a greater distance without increasing the number of antennas.

[0003] When increasing the number of antennas, the board size increases accordingly, and the number of ICs that control the antennas also increases, which creates issues with module size and heat generation.

[0004] Placing the antennas farther apart increases the size of the circuit board, and because the distance between the antennas is no longer half the wavelength (λ / 2), there is the issue of degradation of detection performance due to the occurrence of grating lobes (side lobes).

[0005] For example, Patent Document 1 proposes controlling the radiation directivity of a radar device by narrowing the beam using a lens formed from a metamaterial and controlling the radiation directivity direction. Also, Non-Patent Document 1 proposes a method of controlling radiation directivity with suppressed side lobes by forming a metalens by controlling the transmission amplitude and transmission phase of a sheet using metamaterial technology. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 2010-526318 [Patent Document 2] Japanese Patent Publication No. 2023-011202 [Patent Document 3] Japanese Patent Publication No. 2020-153872 [Patent Document 4] Japanese Patent Publication No. 2020-060483 [Patent Document 5] Japanese Patent Publication No. 2020-060485 [Non-patent literature]

[0007] [Non-Patent Document 1] “Transmissive Metasurface With Independent Amplitude / Phase Control and Its Application to Low-Side-Lobe Metalens Antenna” [Non-patent document 2] ”Design of a novel polarization converter based on artificial materials with metallic meta-atoms” Summary of the Invention [Problem to be solved by the invention]

[0008] However, the existing technologies of Patent Document 1 and Non-Patent Document 1 are beam control technologies that utilize the lens effect using metamaterial technology, and are not technologies for physically increasing the number of antennas in a MIMO radar.

[0009] The present disclosure contributes to providing a radar device and a vehicle that can achieve higher resolution by physically increasing the number of antennas in a MIMO radar and improve the accuracy of detecting the position of a target. [Means for solving the problem]

[0010] A radar device according to one aspect of the present disclosure includes a radar module having a transmitting antenna that transmits a transmission signal, and a re-radiating unit having a re-radiating element that re-radiates the transmission signal.

[0011] A vehicle according to one aspect of the present disclosure is equipped with a radar device including a radar module having a transmitting antenna for transmitting a transmission signal, and a re-radiating unit having a re-radiating element for re-radiating the transmission signal. [Effects of the Invention]

[0012] According to an embodiment of the present disclosure, the accuracy of detecting the position of a target can be improved by increasing the resolution. [Brief explanation of the drawings]

[0013] [Figure 1] Diagram explaining the concept of radar equipment [Figure 2] Overall configuration diagram [Figure 3] FIG. 1 is a diagram illustrating the concept of a radar device according to a first embodiment. [Figure 4] FIG. 10 is a diagram illustrating the concept of a radar device according to a second embodiment. [Figure 5A] Diagram showing the radiation direction when the signal radiation direction is not controlled [Figure 5B] A diagram showing the radiation direction when the signal radiation direction is controlled [Figure 6] FIG. 20 is a diagram illustrating the concept of a radar device according to a sixth embodiment. [Figure 7] FIG. 20 is a diagram illustrating the concept of a radar device according to a modification of the sixth embodiment. [Figure 8A] FIG. 13 is a diagram illustrating the concept of a radar device according to a seventh embodiment. [Figure 8B] FIG. 13 is a diagram illustrating the concept of a radar device according to a seventh embodiment. [Figure 9A] FIG. 20 is a diagram illustrating the concept of a radar device according to a first modification of the seventh embodiment. [Figure 9B] FIG. 20 is a diagram illustrating the concept of a radar device according to a first modification of the seventh embodiment. [Figure 10A]FIG. 20 is a diagram illustrating the concept of a radar device according to a second modification of the seventh embodiment. [Figure 10B] FIG. 20 is a diagram illustrating the concept of a radar device according to a second modification of the seventh embodiment. [Figure 11A] FIG. 20 is a diagram illustrating the concept of a radar device according to a third modification of the seventh embodiment. [Figure 11B] FIG. 20 is a diagram illustrating the concept of a radar device according to a third modification of the seventh embodiment. [Figure 12] FIG. 20 is a diagram illustrating the concept of a radar device according to an eighth embodiment. [Figure 13] FIG. 1 is a diagram illustrating the time when a transmitting antenna element and a re-radiating element radiate a signal. [Figure 14] FIG. 13 is a diagram showing the configuration of a radar receiving unit according to the eighth embodiment. [Figure 15] Diagram explaining the outline of separation of the beat frequency analysis section [Figure 16] FIG. 20 is a diagram illustrating the concept of a radar device according to a first modification of the eighth embodiment. [Figure 17] FIG. 1 is a diagram illustrating the time when a transmitting antenna element and a re-radiating element radiate a signal. [Figure 18] FIG. 20 is a diagram illustrating the concept of a radar device according to a second modification of the eighth embodiment. [Figure 19] FIG. 20 is a diagram illustrating the concept of a radar device according to a ninth embodiment. [Figure 20A] Diagram showing vertical polarization [Figure 20B] Diagram showing horizontal polarization [Figure 20C] Diagram showing right-hand circular polarization [Figure 20D] Diagram showing left-handed circular polarization [Figure 21] FIG. 22 is a diagram illustrating an outline of a radar device according to a tenth embodiment mounted on a vehicle. [Figure 22] A diagram showing an example of the configuration of a thin radar device [Figure 23] A diagram showing an example of the configuration of a thin radar device DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings as appropriate.

[0015] The radar module 110 shown in FIG. 1 has N transmitting antenna elements 113-1 to 113-N arranged on the zy plane, and the re-radiating unit 120 has M re-radiating elements 120-1 to 120-M arranged on the zy plane for each of the transmitting antenna elements 113-1 to 113-N. Radio waves (transmitted signals) radiated from each of the transmitting antenna elements 113-1 to 113-N are re-radiated by each of the re-radiating elements 120-1 to 120-M. For example, when radio waves radiated in the x-axis direction from each of the transmitting antenna elements 113-1 to 113-N of the radar module 110 are re-radiated by the re-radiating unit 120, at least one of the phase, delay time, and polarization is converted by the re-radiating elements #1 and #M. The radar module 110 can receive radio waves re-radiated in the x-axis direction by each re-radiating element and waves reflected by the target 130 from the radio waves radiated by the transmitting antenna elements. Furthermore, when a transparent film is used for the re-radiation unit 120, radio waves that pass through the transparent film without passing through the M re-radiation elements 120-1 to 120-M of the re-radiation unit 120 are reflected by the target 130 and received by the radar module 110. Since the radio waves re-radiated and transmitted by the re-radiation unit 120 differ in at least one of phase, delay time, and polarization, the radar module 110 can separate the received reflected waves into the reflected waves of the radio waves re-radiated and transmitted by each re-radiation element. When N transmitting antenna elements 113-1 to 113-N of the radar module 110 and M re-radiation elements 120-1 to 120-M of the re-radiation unit 120 are used, radio waves can be separated into N×(M+1) different types, taking into account transmission through the transparent film. For example, by using the re-radiation unit 120, it is possible to obtain the same effect as increasing the number of transmitting antennas in a MIMO (Multi Input Multi Output) radar by (M+1) times, and increase the number of virtual receiving antennas in the MIMO radar, without making any changes to the radar module 110. This makes it possible to expand the aperture length of the virtual receiving antenna in the MIMO radar, and improve angle measurement performance (angle measurement estimation accuracy and angle resolution for multiple targets).

[0016] The re-radiation unit 120 re-radiates the radio waves emitted from the radar module 110, but does not re-radiate the reflected signals received by the radar module 110. For example, the re-radiation unit 120 is not involved in (is transparent to) the reception of reflected signals by the radar module 110. The re-radiation elements 120-1 to 120-M are installed in locations where they re-radiate the radio waves emitted from the radar module 110, but do not re-radiate the reflected signals received by the radar module 110.

[0017] 2 includes a radar transmission signal generation unit 111, a radio transmission unit 112, a transmission antenna 113, a control unit 114, a receiving antenna 115, a radio reception unit 116, and a signal processing unit 117. The radar transmission signal generation unit 111, the radio transmission unit 112, and the transmission antenna 113 constitute a radar transmission unit 118, and the receiving antenna 115, the radio reception unit 116, and the signal processing unit 117 constitute a radar reception unit 119. The control unit 114 may be included in the radar transmission unit 118 or may be included in the radar reception unit 119.

[0018] A radar transmission signal is code-division multiplexed (CDM) or time-division multiplexed (TDM) and transmitted from the radar module 110. The transmission signal transmitted from the radar module 110 is re-radiated by the re-radiation unit 120, reflected by the target 130, and received by the radar module 110. Patent Document 2 describes a configuration in which a signal is code-multiplexed and transmitted from a transmitting antenna, and Patent Document 3 describes a configuration in which a signal is time-division multiplexed and transmitted from a transmitting antenna. Since the configuration in which a signal is code-multiplexed and transmitted from a transmitting antenna and the configuration in which a signal is time-division multiplexed and transmitted from a transmitting antenna are well-known technologies, the following describes an outline of the configurations of the radar transmission signal generation unit 111, the radio transmission unit 112, the transmitting antenna 113, the control unit 114, the receiving antenna 115, the radio reception unit 116, and the signal processing unit 117.

[0019] The radar transmission signal generation unit 111 generates a transmission signal. The radar transmission signal generation unit 111 includes, for example, a modulation signal generation unit and a VCO (Voltage Controlled Oscillator). The modulation signal generation unit generates a sawtooth modulation signal (for example, a modulation signal for VCO control) for each radar transmission period Tr. The VCO generates a frequency modulation signal (hereinafter, for example, referred to as a frequency chirp signal or chirp signal) based on the modulation signal output from the modulation signal generation unit, and outputs the frequency modulation signal to the radio transmission unit 112. The radar transmission signal generation unit 111 may generate a transmission signal for each radar transmission period Tr using a code with a different code sequence.

[0020] The radio transmission unit 112 performs control to code-multiplex or time-division-multiplex the transmission signal.

[0021] Transmitting antenna 113 has N transmitting antenna elements 113-1 to 113-N. Transmitting antenna 113 radiates into space the signal received from radio transmitting unit 112. The configurations of transmitting antenna elements 113-1 to 113-N may be the same, or transmitting antenna elements with different configurations may be included.

[0022] The control unit 114 controls the radio transmission unit 112 , the signal processing unit 117 , and the re-radiation unit 120 .

[0023] Receiving antenna 115 has L receiving antenna elements 115-1 to 115-L located at a location separate from transmitting antenna elements 113-1 to 113-N. Receiving antenna 115 receives a reflected signal reflected from a target. The reflected signal received by each receiving antenna element is output to wireless receiving unit 116.

[0024] Radio receiving unit 116 includes, for example, an amplifier and a detector. Radio receiving unit 116 demodulates the reflected signal received by receiving antenna 115. Radio receiving unit 116 outputs the demodulated reflected signal to signal processing unit 117.

[0025] The signal processing unit 117 has an AD conversion unit, an output switching unit, a Doppler analysis unit, etc. The signal processing unit 117 performs positioning of the target 130 based on the signal input from the wireless receiving unit 116, and outputs the result. The re-radiating section 120 has a plurality of re-radiating elements 120-1 to 120-M. Each re-radiating element has the same configuration, and the radio waves re-radiated by each re-radiating element differ in at least one of phase, delay time, and polarization.

[0026] <First Embodiment> The radar module 110 shown in FIG. 3 has N transmitting antenna elements. The re-radiating unit 120 is located physically separated from the radar module 110 and has M re-radiating elements. The transmission signal radiated from each transmitting antenna element is re-radiated by each re-radiating element of the re-radiating unit 120, or passes through the re-radiating unit 120 without being re-radiated, and reaches the target 130. For example, the transmission signals radiated from each transmitting antenna element reach the target 130 as M+1 different transmission signals. For example, with the radar module 110 having N transmitting antenna elements and the re-radiating unit 120 having M re-radiating elements, N×(M+1) different transmission signals reach the target 130. Therefore, it can be said that a MIMO radar is configured with N×(M+1) transmitting antennas. Here, N and M are both integers equal to or greater than 1.

[0027] By making at least a part of the re-radiating section 120 out of a material with high radio wave permeability, such as a transparent film, the transmission signals radiated from the transmitting antenna elements 113-1 to 113-N can reach the target 130 as they are.

[0028] The re-radiating unit 120 may be attached to a radome that protects the radar module 110 (or the transmitting antenna 113). For example, the re-radiating unit 120 may be attached to the inside (antenna unit side) of the radome. With this configuration, the radome can protect not only the radar module 110 (or the transmitting antenna 113) but also the re-radiating unit 120 (this can be similarly applied to the following embodiments, and similar effects can be obtained). For example, if at least a part of the re-radiating unit 120 is made of a material with high radio wave transparency, such as a transparent film, the transparent film may be attached to the inside of the radome (the surface facing the antenna unit).

[0029] <Embodiment 2> The radar module 110 shown in FIG. 4 has N transmitting antenna elements. The re-radiating unit 120 is located physically separated from the radar module 110 and has M re-radiating elements. The transmission signal radiated from each transmitting antenna element is re-radiated by each re-radiating element of the re-radiating unit 120 and reaches the target 130. For example, the transmission signal radiated from each transmitting antenna element reaches the target 130 as M different transmission signals. For example, the radar module 110 has N transmitting antenna elements and the re-radiating unit 120 has M re-radiating elements, and N×M different transmission signals reach the target 130. Therefore, it can be said that a MIMO radar is configured with N×M transmitting antennas. Here, N is an integer equal to or greater than 1, and M is an integer equal to or greater than 2.

[0030] In the above-described second embodiment, it can be understood that the first embodiment corresponds to a case where one of the re-radiating elements is a transparent re-radiating element, for example, a re-radiating element that is not involved in re-radiation. Therefore, in the following description and claims, the re-radiating element includes a transparent re-radiating element. A transparent re-radiating element is a re-radiating element that is not involved in re-radiation and that transmits radio waves radiated from the transmitting antenna as they are, and also includes a state in which no re-radiating element exists and radio waves are transmitted.

[0031] On the other hand, according to the second embodiment, the number of transmitting antennas of the MIMO radar can be increased even if re-radiating elements are arranged on a member (for example, a substrate) made of a material that blocks (does not transmit) radio waves. For example, even if the substrate is made of a material that blocks radio waves, the re-radiating elements only need to receive the transmission signals radiated from the transmitting antenna elements on one surface of the substrate and re-radiate them from the other surface of the substrate.

[0032] <Third Embodiment> A metamaterial structure can be used as the re-radiating element in the first and second embodiments. By using a re-radiating element with a metamaterial structure, it is possible to control the phase and ON / OFF of the re-radiating element, or perform polarization conversion. For example, Non-Patent Document 1 proposes a phase control method using metamaterials, and Non-Patent Document 2 proposes a polarization conversion technology using metamaterials.

[0033] <Fourth Embodiment> In the first and third embodiments, the re-radiating elements may be configured on a transparent film. By configuring the re-radiating elements on a transparent film, the transparent film on which the re-radiating elements are configured can be attached to the windshield, so that the re-radiating elements can be arranged without impairing the appearance.

[0034] <Fifth Embodiment> FIG. 5A shows the radiation direction when the re-radiating elements do not control the direction in which the signal is radiated, and FIG. 5B shows the radiation direction when the re-radiating elements control the direction in which the signal is radiated.

[0035] When the radiation direction of the re-radiating element is not controlled, the re-radiating element may re-radiate with a directivity that maximizes the radiation direction in the direction received from the transmitting antenna element, as shown in FIG. 5A. For example, in FIG. 5A, the directivity of the re-radiating element 120-1 (#1) is tilted in the positive direction of the z-axis, and the directivity of the re-radiating element 120-M (#M) is tilted in the negative direction of the z-axis. In this case, the maximum radiation direction of re-radiation varies depending on the position of the re-radiating element. Therefore, depending on the position of the target 130, the radio waves re-radiated from the re-radiating element may not reach the target 130 easily, which may degrade the performance of the MIMO radar and make it difficult to detect the target 130. In FIG. 5B, the tilt of the directivity of the re-radiating element 120-1 (#1) and the directivity of the re-radiating element 120-M (#M) in the z-axis direction is controlled, allowing each re-radiating element 120 to re-radiate along the x-axis.

[0036] In the first to fourth embodiments, when the re-radiating element controls the direction in which the signal is radiated, the re-radiating element may radiate radio waves with the same directivity, that is, the maximum radiation direction of the directivity radiated by the transmitting antenna element. By controlling the directivity using a metamaterial structure as the re-radiating element, the re-radiating element can re-radiate with the same directivity, that is, the maximum radiation direction of the directivity radiated by the transmitting antenna element. Furthermore, by using a metamaterial structure for the re-radiating element, the directivity of the re-radiating element can also be adjusted individually. Because the maximum radiation direction of the directivity radiated by the transmitting antenna element and each re-radiating element is the same (for example, the same directivity), the radio waves re-radiated from all the re-radiating elements can be reflected by the target 130 and received by the radar module 110. As a result, the aperture length of the virtual receiving antenna of the MIMO radar is increased, thereby improving the angle measurement performance and enabling reliable detection of the target 130. In the above description, the case where the maximum radiation direction of the directivity emitted by the transmitting antenna element and each re-radiating element is the same has been described. However, this is not limited to this. For example, by configuring each re-radiating element with an element having a metamaterial structure, the maximum radiation direction of the directivity emitted by each re-radiating element can be controlled to be a different radiation direction, thereby widening the viewing angle of the radar.

[0037] <Sixth Embodiment> FIG. 6 illustrates a radar device in which a control unit 114 is added to the radar module 110 described in the first to fifth embodiments and controls the phase shifters included in the re-radiating elements 120-1 to 120-M. The control unit 114 illustrated in FIG. 6 controls the phase of the signals re-radiated by each re-radiating element to orthogonalize the phases of the signals re-radiated by the re-radiating elements. The re-radiating elements include, for example, a phase shifter. The control unit 114 controls the phase shifter to impart a desired phase rotation to each re-radiating element. The control unit 114 controls the phase to achieve a desired phase on the surface of the re-radiating element. The control unit 114 controls the phase of the signals re-radiated by each re-radiating element, taking into account the phase difference caused by the difference in distance between the transmitting antenna element and each re-radiating element. By controlling the phases of the signals radiated by each re-radiating element to be orthogonal, it is possible to separate the signals radiated by each re-radiating element from the reflected signals reflected by the target 130.

[0038] By configuring each re-radiating element as an element having a metamaterial structure, the phase can be controlled by the control unit 114. Various structures have been proposed for phase control using metamaterials, and for example, a proposal such as that in Non-Patent Document 1 has been made.

[0039] The radar module 110 can use either code multiplexing or time division multiplexing, and the radar module 110 can also obtain similar effects by using Doppler multiplexing.

[0040] (Variation) 7, when multiple radar modules 110-1 and 110-2 are used, an integrated control unit 140 is provided, and the integrated control unit 140 controls the control unit 114 of each radar module 110. The radar module 110-1 has a transmitting antenna element 113-1 and corresponding re-radiating elements 120-1-1 to 120-1-M. The radar module may have multiple transmitting antenna elements. The radar modules 110-1 and 110-2 may have the same configuration, or the number of transmitting antenna elements or the number of receiving antenna elements included in each radar module may differ, or the number of re-radiating elements included in the re-radiating units 120-1 and 120-2 may differ. The integrated control unit 140 performs phase control of the transmitting antenna elements 113-1-1 and 113-2-1 and the re-radiating elements 120-1-1 to 120-1-M and 120-2-1 to 120-2-M of the radar modules 110-1 and 110-2. The radar device is provided with a number of re-radiating units 120 corresponding to the number of radar modules 110. In FIG. 7, one re-radiating unit 120 is provided corresponding to one radar module 110, but one re-radiating unit 120 may be provided corresponding to multiple radar modules 110. Furthermore, the control unit 114 of one radar module 110 (for example, the control unit 114 of the radar module 110-1) may function as the integrated control unit 140.

[0041] <Seventh Embodiment> As shown in FIGS. 8A and 8B, the re-radiating element 120-1 may be a reconfigurable intelligent surface (RIS) configured by periodically arranging a plurality of elements 121. In the configuration shown in FIG. 8A, a transmission signal radiated from the transmitting antenna element 113-1 is re-radiated by the re-radiating element 120-1, and a transmission signal radiated from the transmitting antenna element 113-2 is re-radiated by the re-radiating element 120-2. In FIG. 8B, each of the re-radiating elements 120-1 and 120-2 is configured by, for example, nine elements arranged in a 3×3 matrix. The control unit 114 turns on different elements depending on the time. For example, at time T=1, the control unit 114 turns on the elements in the left and middle columns and turns off the elements in the right column. For example, at time T=2, the control unit 114 turns on the elements in the middle and right columns and turns off the elements in the left column. The control unit 114 alternately repeats the RIS pattern (state of each element) at time T=1 and the RIS pattern at time T=2. Each re-radiating unit achieves a specific directivity with six elements that are turned on. The re-radiating elements are configured with multiple such elements and can form a directional beam, which has the effect of increasing the directional gain within a specified angle range and has the effect of expanding the target detection distance range of the radar device.

[0042] When the elements that are turned ON among the multiple elements change, the phase center of the RIS pattern composed of the ON elements changes. Changing the phase center in time division means changing the position of each re-radiating element in time division, which has the same effect as switching the transmitting antenna in time division, and can be said to increase the number of transmitting antennas in a MIMO radar. Hereinafter, re-radiating elements obtained by partially operating multiple elements with overlap in time division are also called virtual re-radiating elements. The VE corresponding to each re-radiating element that switches in time division is composed of each RIS pattern. In Figure 8, the VE corresponding to the re-radiating element at time T=1 is VE#1, and the VE corresponding to the re-radiating element at time T=2 is VE#2. The phase center positions of VE#1 and VE#2 are different.

[0043] The arrangement of elements and the elements that are turned ON are not limited to the example in Fig. 8. The control unit 114 may turn ON any element in any arrangement of elements as long as the phase center changes in time division. The elements that are turned ON may overlap in each RIS pattern.

[0044] The directional beams generated by the virtual re-radiating elements VE#1 and VE#2 when switched in time division may be directional beams with the same directivity in time division, or may be directional beams with different directivities. Alternatively, beam control that adaptively changes the directional beam may be used.

[0045] (Variation 1) In the first modification shown in Figures 9A and 9B, multiple transmitting antenna elements radiate code-multiplexed transmission signals, while re-radiating elements switch RIS patterns in a time-division manner. For example, the same RIS pattern is used for the code length of the code when multiplexing transmission is performed by multiple transmitting antenna elements. The multiple transmitting antenna elements may radiate transmission signals that are Doppler-division multiplexed (DDM) instead of code-multiplexed.

[0046] 9A radiates code-multiplexed transmit signals using a code with a code length of 2. For example, the code used by the transmit antenna element Tx1 is [1,1], and the transmit antenna element Tx1 repeatedly transmits a reference chirp signal (e.g., transmits 1,1,1,1 from time 1 to time 4). On the other hand, the code used by the transmit antenna element Tx2 is [1,-1], and the transmit antenna element Tx2 alternately transmits a chirp signal with the same phase (corresponding to code element 1) and a chirp signal with a phase difference of π (corresponding to code element -1) with respect to the reference chirp signal (e.g., transmits 1,-1,1,-1 from time 1 to time 4).

[0047] Therefore, at times T=1 and 3, the transmitting antenna element Tx1 transmits a chirp signal with phase 0 (reference phase), and the transmitting antenna element Tx2 transmits a chirp signal with phase 0 (reference phase), and at times T=2 and 4, the transmitting antenna element Tx1 transmits a chirp signal with phase 0 (reference phase), and the transmitting antenna element Tx2 transmits a chirp signal with phase π (phase difference π from the reference phase).

[0048] 9B, for example, at times T=1 and T=2, the control unit 114 turns on the elements in the left and middle columns and turns off the elements in the right column. For example, at times T=3 and T=4, the control unit 114 turns on the elements in the middle and right columns and turns off the elements in the left column. The control unit 114 alternately repeats the state at times T=1 and T=2 and the state at times T=3 and T=4. The control unit 114 performs multiple virtual antennas by switching the RIS pattern at a period (for example, two periods in FIG. 9A) according to the code length of the code used in the transmitting antenna element. In FIG. 9B, VE#1 is used at times T=1 and T=2, and VE#2 is used at times T=3 and T=4, and the positions of the phase centers of VE#1 and VE#2 are different.

[0049] According to this embodiment, by using a common re-radiating element for code-multiplexed (or Doppler-multiplexed) transmitting antenna elements, an effect similar to that of increasing the number of transmitting antennas in a MIMO radar can be obtained, so that the number of virtual receiving antennas in the MIMO radar can be increased and the aperture length can be enlarged while reducing the number of re-radiating elements, thereby improving the angle measurement performance (angle measurement estimation accuracy and angular resolution for multiple targets). Furthermore, the effect of reducing the number of re-radiating elements makes it possible to reduce the installation area of ​​the re-radiating elements, which also has the effect of miniaturizing the radar device.

[0050] Furthermore, this embodiment can increase the number of virtual receiving antennas in the MIMO radar in proportion to the number of code-multiplexed transmitting antenna elements and the number of RIS patterns of time-division multiplexed re-radiating elements.

[0051] The directional beams generated by the virtual re-radiating elements VE#1 and VE#2 when switched in time division may be directional beams with the same directivity in time division, or may be directional beams with different directivities. Alternatively, beam control that adaptively changes the directional beam may be used.

[0052] (Variation 2) In Modification 1, code multiplexing is performed by the transmitting antenna element, but in Modification 2 shown in Figures 10A and 10B, code multiplexing is performed by the re-radiating element. In Modification 2, the re-radiating element imparts a phase for code multiplexing along with a phase for beamforming of the re-radiating element, and further switches the RIS pattern in a time-division manner. In Modification 2, the transmitting antenna element does not multiplex signals. Note that instead of code multiplexing, the re-radiating element may impart a phase rotation for Doppler multiplexing to perform Doppler multiplexing, and similar effects can be obtained.

[0053] The transmission signal (e.g., a chirp signal) radiated from the transmitting antenna element 113-1 is re-radiated from the re-radiating elements 120-1 and 120-2. For example, the code used in the transmitting antenna element Tx1 is the code [1,1], and the transmitting antenna element Tx1 repeatedly transmits, for example, a reference chirp signal. For example, the transmission signal radiated from the transmitting antenna element 113-1 is not given a phase rotation for each transmission period of the chirp signal (e.g., at times T=1 and 2).

[0054] First, the assignment of beamforming phases to the reradiating elements will be described. The two reradiating elements 120-1 and 120-2 are configured, for example, by 15 elements arranged in a 3x5 matrix. The RIS pattern of each reradiating element changes in a time-division manner at a period of each time T under the control of the control unit 114. For example, the control unit 114 turns off the elements in the rightmost column at times T=1 and T=2, and configures the remaining four columns of elements into virtual reradiating elements VE#1 and VE#2 in the two left columns and two right columns, respectively. The virtual reradiating elements VE#1 in the two left columns are virtual reradiating elements corresponding to the reradiating element 120-1, and the virtual reradiating elements VE#2 in the two right columns are virtual reradiating elements corresponding to the reradiating element 120-2. The control unit 114 turns off the elements in the leftmost column at times T=3 and T=4, and configures the remaining four columns of elements into virtual reradiating elements VE#3 and VE#4 in the two left columns and two right columns, respectively. The virtual re-radiating elements VE#3 in the two left columns are virtual re-radiating elements corresponding to the re-radiating element 120-1, and the virtual re-radiating elements VE#4 in the two right columns are virtual re-radiating elements corresponding to the re-radiating element 120-2. The positions of the phase centers of VE#1 to VE#4 are all different.

[0055] Furthermore, the virtual re-radiating element VE#1 (or VE#2) by each RIS pattern of the re-radiating elements at times T=1 and 2 is configured, for example, by six elements arranged in a 3×2 array, and beam-forming phases Φ1 to Φ6 (or Φ7 to Φ12) using these multiple elements are applied to form a beam in a predetermined direction. The beams formed by each virtual re-radiating element VE#1, VE#2 may form directional beams that are almost the same, or may form directional beams with different main beam directions. Similarly, the virtual re-radiating element VE#3 (or VE#4) by each RIS pattern of the re-radiating elements at times T=3 and 4 is similarly configured, for example, by six elements arranged in a 3×2 array, and beam-forming phases Φ1 to Φ6 (or Φ7 to Φ12) using these multiple elements are applied to form a beam in a predetermined direction. Furthermore, the virtual re-radiating elements VE#1, VE#2, VE#3, VE#4 may form directional beams that are almost the same, or may form directional beams with different main beam directions. By using multiple such elements to form such a directional beam, the directional gain can be increased, thereby increasing the SNR (signal-to-noise ratio) of the received signal of the reflected wave from the target in the direction of the directional beam.

[0056] Next, we will explain the addition of phases for code multiplexing, which is performed together with the addition of beamforming phases to the re-radiating elements of the re-radiating elements. For example, the virtual re-radiating element VE#1 (or VE#2) by the RIS pattern of the re-radiating elements at times T=1 and T=2 can be re-radiated as a code-multiplexed (or Doppler-multiplexed) signal by further adding phase rotation with a different code in addition to the beamforming phases Φ1 to Φ6 (or Φ7 to Φ12) using multiple elements.

[0057] For example, the code used by virtual re-radiating element VE#1 composed of elements in the two leftmost columns is code [1,1] at times T=1 and T=2. In this case, when phase rotation is superimposed on the beamforming phase using multiple elements, phase rotation is applied to each of the six elements, [Φ1,Φ1] to [Φ6,Φ6]. As a result, the virtual re-radiating element generates a beam in a predetermined directional beam pattern from the transmit signal (e.g., chirp signal) incident on the virtual re-radiating element from transmitting antenna element 113-1, with a phase of 0 (no phase rotation applied or a predetermined phase rotation serving as a reference phase applied), and re-radiates the beam.

[0058] Furthermore, the code used in the virtual re-radiating element VE#2 configured in the two right-hand columns is the code [1, -1] at times T=1 and T=2. In this case, when phase rotation is superimposed on the beamforming phase using multiple elements, phase rotation is applied to each of the six elements, from [Φ7, -Φ7] to [Φ12, -Φ12]. As a result, the virtual re-radiating element generates a beam in a predetermined directional beam pattern using a transmission signal (for example, a chirp signal) from transmitting antenna element 113-1 incident on the virtual re-radiating element, with a phase of 0 (no phase rotation applied, or a predetermined phase rotation serving as a reference phase) and a phase of π (a phase rotation with a phase difference of π from the phase at "phase 0"), and re-radiates the beam.

[0059] Similarly, the virtual re-radiating element VE#3 (or VE#4) using each RIS pattern of the re-radiating element at times T=3 and 4 can be re-radiated as a code-multiplexed (or Doppler-multiplexed) signal by adding phase rotation with a different code to the beamforming phases Φ1 to Φ6 (or Φ7 to Φ12) using multiple elements.

[0060] The control unit 114 alternately repeats the states at times T=1 and 2 and the states at times T=3 and 4. Such code-multiplexed and time-multiplexed signals are orthogonal to each other, and the reflected waves from the target can be received separately by the radar receiving unit. Therefore, the re-radiating elements form beams using each RIS pattern of the virtual re-radiating elements, and then code-multiplex and re-radiate the beams (in the case of FIG. 10B, the re-radiated signals are two RIS patterns, and the code multiplexing number is 2). In addition, the RIS patterns are time-multiplexed in a period corresponding to the code length (in the case of FIG. 10A, two transmission periods). (In the case of FIG. 10B, two RIS patterns are switched every two transmission periods by time division, so the time multiplexing number is 2). By combining code multiplexing and time multiplexing, the control unit's control operation on the re-radiating elements achieves the same effect as increasing the number of transmitting antennas in the radar by (code multiplexing number × time multiplexing number), thereby increasing the number of virtual receiving antennas in the MIMO radar. This allows the aperture length of the virtual receiving antenna in the MIMO radar to be expanded, improving angle measurement performance (angle measurement estimation accuracy and angular resolution for multiple targets).

[0061] As shown in Figures 8 and 9, if nine elements are associated with each re-radiating element, the two re-radiating elements 120-1 and 120-2 are configured with 18 elements. However, by using 15 elements and combining code multiplexing and time multiplexing to configure the two re-radiating elements 120-1 and 120-2, the number of elements can be reduced. A plurality of elements may be associated with three or more re-radiating elements. For example, 3 x (2K + 1) elements may be associated with K re-radiating elements. In the seventh embodiment and the first modification of the seventh embodiment, each re-radiating element performs the same operation, so that N elements can be configured for a plurality of re-radiating elements.

[0062] The directional beams generated by the virtual re-radiating elements VE#1 to VE#4 when switched in time division may be directional beams with the same directivity in time division, or may be directional beams with different directivities. Alternatively, beam control for adaptively varying the directional beam may be used.

[0063] (Variation 3) In Modification 2, an example was shown in which the number of transmitting antennas is one and the transmitting antenna element does not perform multiplexing transmission. However, Modification 3 shown in Figures 11A and 11B adds re-radiation by a re-radiating element to transmit signals that are code-multiplexed by multiple transmitting antenna elements. In Modification 3, the re-radiating element imparts a phase for code multiplexing as well as a phase for beamforming of the re-radiating element to the code-multiplexed transmit signals from the multiple transmitting antenna elements, and switches the RIS pattern in a time-division manner. Note that, instead of code multiplexing, the re-radiating element may impart phase rotation for Doppler multiplexing to perform Doppler multiplexing, and similar effects can be obtained. Also, instead of code multiplexing, the transmitting antenna element may impart phase rotation for Doppler multiplexing to perform Doppler multiplexing, and similar effects can be obtained.

[0064] Multiple transmitting antenna elements radiate code-multiplexed signals. For example, the code used by transmitting antenna element Tx1 is [1,1,1,1], and transmitting antenna element Tx1 repeatedly transmits a reference chirp signal. On the other hand, the code used by transmitting antenna element Tx2 is [1,1,-1,-1], and transmitting antenna element Tx2 repeatedly transmits chirp signals with phases 0, 0, π, and π, in that order. Here, a phase 0 chirp signal (corresponding to code element 1) has the same phase as the reference chirp signal, and a phase π chirp signal (corresponding to code element -1) has a phase difference of π from the reference chirp signal.

[0065] For example, at times T=1 and 2, the transmitting antenna element Tx1 transmits a chirp signal with a phase of 0, and the transmitting antenna element Tx2 transmits a chirp signal with a phase of 0, and at times T=3 and 4, the transmitting antenna element Tx1 transmits a chirp signal with a phase of 0, and the transmitting antenna element Tx2 transmits a chirp signal with a phase of π. Therefore, the signals are code-multiplexed (code multiplex number 2) using orthogonal codes with a code length of 4 from the two transmitting antenna elements Tx1 and Tx2 and transmitted.

[0066] The transmit signals (for example, chirp signals) radiated from the transmit antenna elements 113-1 and 113-2 are re-radiated by the re-radiating elements 120-1 and 120-2.

[0067] The two re-radiating elements 120-1 and 120-2 are each composed of, for example, 15 elements arranged in a 3x5 matrix. The RIS pattern of each re-radiating element is time-shared. For example, the control unit 114 turns off the rightmost element at T=1 to 4, and configures the remaining four rows of elements by using the two rows on the left and the two rows on the right as virtual re-radiating elements VE#1 and VE#2, respectively. The control unit 114 turns off the leftmost element at T=5 to 8, and configures the remaining four rows of elements by using the two rows on the left and the two rows on the right as virtual re-radiating elements VE#3 and VE#4, respectively. The phase center positions of VE#1 to VE#4 are all different.

[0068] Furthermore, the virtual re-radiating element VE#1 (or VE#2) according to each RIS pattern of the re-radiating element at times T=1 to T=4 is configured, for example, by six elements arranged in a 3×2 matrix, and beam-forming phases Φ1 to Φ6 (or Φ7 to Φ12) using these multiple elements are applied to form a beam in a predetermined direction. The beams formed by each virtual re-radiating element VE#1, VE#2 may form directional beams that are almost the same, or may form directional beams with different main beam directions. Similarly, the virtual re-radiating element VE#3 (or VE#4) according to each RIS pattern of the re-radiating element at times T=5 to T=8 is similarly configured, for example, by six elements arranged in a 3×2 matrix, and beam-forming phases Φ1 to Φ6 (or Φ7 to Φ12) using these multiple elements are applied to form a beam in a predetermined direction. Furthermore, the virtual re-radiating elements VE#1, VE#2, VE#3, VE#4 may form directional beams that are almost the same, or may form directional beams with different main beam directions. By using multiple such elements to form such a directional beam, the directional gain can be increased, thereby increasing the SNR (signal-to-noise ratio) of the received signal of the reflected wave from the target in the direction of the directional beam.

[0069] Furthermore, the virtual re-radiating element VE#1 (or VE#2) based on the RIS pattern of the re-radiating element at times T=1 and 2 (or times T=3 and 4) can be re-radiated as a code-multiplexed (or Doppler-multiplexed) signal by further adding phase rotation with a different code in addition to the beamforming phases Φ1 to Φ6 (or Φ7 to Φ12) using multiple elements.

[0070] For example, the code used by virtual re-radiating element VE#1 composed of elements on the two left columns is the code [1,1] at times T=1 and 2 (or times T=3 and 4). In this case, when phase rotation is superimposed on the beamforming phase using multiple elements, phase rotation is applied to each of the six elements, [Φ1,Φ1] to [Φ6,Φ6]. As a result, the virtual re-radiating element generates a beam in a predetermined directional beam pattern for the transmit signals (e.g., chirp signals) incident on the virtual re-radiating element from transmitting antenna elements 113-1 and 113-2, with a phase of 0 (no phase rotation applied or a predetermined phase rotation serving as a reference phase applied), and re-radiates the beam.

[0071] Furthermore, the code used by virtual re-radiating element VE#2, which is composed of elements in the two right-hand columns, is the code [1, -1] at times T=1 and 2 (or times T=3 and 4). In this case, when phase rotation is superimposed on the beamforming phase using multiple elements, phase rotation is applied to each of the six elements, from [Φ7, -Φ7] to [Φ12, -Φ12]. As a result, the virtual re-radiating element generates a beam of transmission signals (e.g., chirp signals) from transmitting antenna elements 113-1 and 113-2 incident on the virtual re-radiating element, with a predetermined directional beam pattern, using either phase 0 (no phase rotation applied, or a predetermined phase rotation serving as a reference phase) or phase π (a phase rotation with a phase difference of π from the phase at "phase 0"), and re-radiates the beam.

[0072] Similarly, the virtual re-radiating element VE#3 (or VE#4) using each RIS pattern of the re-radiating element at times T=5 and 6 (or times T=7 and 8) can be re-radiated as a code-multiplexed (or Doppler-multiplexed) signal by adding phase rotation with a different code to the beamforming phases Φ1 to Φ6 (or Φ7 to Φ12) using multiple elements.

[0073] The control unit 114 alternately repeats the states of time T=1 to 4 and time T=5 to 8. Such code-multiplexed signals for the transmitting antenna elements and code-multiplexed and time-multiplexed signals for the virtual re-radiating elements are orthogonal to each other, and the reflected waves from the target can be received separately by the radar receiving unit.

[0074] Therefore, the re-radiating elements form beams using each RIS pattern of the virtual re-radiating elements, and then code-multiplex the beams before re-radiating them (in the case of FIG. 11B, the re-radiated signals are two RIS patterns, and the code-multiplexing number of the virtual re-radiating elements is two). The RIS patterns are also time-multiplexed at a period (four transmission periods in the case of FIG. 11A) according to the code length of the code-multiplexing for the multiple transmitting antenna elements (in the case of FIG. 11B, two RIS patterns are switched in a time-multiplexing manner every four transmission periods, so the time-multiplexing number is two). The control operation of the control unit, which combines code-multiplexing of the transmitting antenna elements with code-multiplexing and time-multiplexing of the re-radiating elements, achieves the same effect as increasing the number of transmitting antennas in the radar by (transmitting antenna multiplexing number × code-multiplexing number of the re-radiating elements × time-multiplexing number), thereby enabling the number of virtual receiving antennas in the MIMO radar to be increased. This allows the aperture length of the virtual receiving antennas in the MIMO radar to be expanded, thereby improving angle measurement performance (angle measurement estimation accuracy and angular resolution for multiple targets).

[0075] The directional beams generated by the virtual re-radiating elements VE#1 to VE#4 when switched in time division may be directional beams with the same directivity in time division, or may be directional beams with different directivities. Alternatively, beam control for adaptively varying the directional beam may be used.

[0076] For example, a transmitting antenna element radiates a code-multiplexed transmission signal. A re-radiating element code-multiplexes and re-radiates the signal, and further switches the RIS pattern in a time-division manner at a period corresponding to the code length of the code-multiplexing. Note that multiple elements may be associated with three or more re-radiating elements.

[0077] In the seventh embodiment, the positioning performance of the radar device for targets, particularly the angle measurement performance (angle measurement estimation accuracy and angular resolution for multiple targets), can be improved by combining multiple multiplexing methods and increasing the number of virtual antennas. However, since multiple chirp signals are transmitted, the Doppler detection range may be reduced. If the Doppler detection range of the expected target is wide, the effect of reducing the Doppler detection range can be suppressed by shortening the chirp signal transmission period. The control unit 114 can select which method to use from the seventh embodiment and the first to third modifications of the seventh embodiment depending on the angle measurement performance and the Doppler detection performance. Furthermore, the control unit 114 may switch between the methods of the seventh embodiment and the first to third modifications of the seventh embodiment depending on, for example, the vehicle speed. While FIGS. 10B and 11B show multiple re-radiating elements arranged in the column direction, multiple re-radiating elements may be associated with the row direction, or with both the row and column directions. For example, a RIS pattern may be used in which four re-radiating elements are associated with elements arranged in a 7×5 array, and the phase center of the re-radiating elements is shifted in the column direction. Furthermore, the number of elements constituting one re-radiating element does not have to be 3×2.

[0078] <Embodiment 8> In the first to seventh embodiments, the re-radiating elements re-radiate with different time delays. The eighth embodiment shown in Fig. 12 separates the signals transmitted by each re-radiating element by using different time delays.

[0079] In FIG. 13, the transmitting antenna element is r Every transmission time T c Transmit a chirp signal.

[0080] The chirp signal radiated by the transmitting antenna element is transmitted at different times T i (In the following description, T i is T i+1 The delay time T i is the transmission time T of the chirp signal radiated by the transmitting antenna element. c The difference in delay time between each re-radiating element is ΔT = T i+1 -T i is greater than the TOF (Time of Flight) for detecting a target within the radar device's maximum detection range R, for example, 2R / c (c is the speed of light). For example, ΔT > 2R / c. If the re-radiating element is made of a transparent film or the like, the signal transmitted from the transmitting antenna will pass through it, so in this case the delay time T0 will be T0 = 0 (the timing at which the chirp signal starts to be transmitted), and T1 is set to be greater than the TOF of the maximum detection range.

[0081] In the eighth embodiment, the distance between the transmitting antenna element and each re-radiating element may be varied so that the chirp signals radiated by each re-radiating element are transmitted with different delay time differences. By varying the distance between the transmitting antenna element and each re-radiating element, a time difference is provided in the chirp signals radiated by the re-radiating unit, and control of the re-radiating elements from the control unit 114 can be omitted.

[0082] The radar receiving unit 119 shown in Fig. 14 can be combined with the multiplexing method using code multiplexing (or Doppler multiplexing) and time division multiplexing described in the seventh embodiment. The radar receiving unit 119 includes receiving antenna elements 115-1 to 115-Na, antenna system processing units 1401-1 to 1401-Na, a CFAR (Constant False Alarm Rate) unit 1408, and a direction estimating unit 1409. The antenna system processing units 1401-1 to 1401-Na correspond to the receiving antenna elements 115-1 to 115-Na. The antenna system processing units 1401-1 to 1401-Na have the same configuration. The antenna system processing unit 1401-1 includes a radio receiving unit 116 and a signal processing unit 117. The radio receiving unit 116 includes a mixer unit 1402 and an LPF (Low Pass Filter) 1403. The signal processing unit 117 has an AD conversion unit 1404, a beat frequency analysis unit 1405, a distance separation unit 1406, and Doppler analysis units 1407-1 to 1407-Loc.

[0083] The mixer unit 1402 receives the output of the receiving antenna element 115-1 and the VCO output, and outputs the detected (mixed) output to the LPF 1403.

[0084] The LPF 1403 extracts a beat signal included in the baseband of the signal input from the mixer unit 1402 and outputs it to the AD conversion unit 1404 .

[0085] The AD conversion unit 1404 samples and quantizes the signal input from the LPF 1403 to convert it into a digital signal, and outputs it to the beat frequency analysis unit 1405 .

[0086] The beat frequency analysis unit 1405 performs frequency analysis of the beat signal output from the AD conversion unit 1404 for each transmission period. The output of the beat frequency analysis unit 1405 separates the reflected signals received from each re-radiating element into each distance block RB. When re-radiating the signal, the difference in delay time for each re-radiating element is set larger than the TOF for detecting a target in the maximum detection range R, so the signal reflected by the target can be separated and received as a block for each radiating element. Here, the distance ΔR of the distance block RB (the distance detected by the radar) is the distance that can be detected based on the time difference in the delay time for each re-radiating element. For example, ΔR(T i+1 ,T i )=(T i+1 -T i )×c / 2>R. The time T0 delayed by the transparent re-radiating element (#0) is T0=0. FIG. 15 is a diagram illustrating the received signals from the transmitting (Tx) antenna and re-radiating elements #1 to #M, and an overview of their separation, at the output of the beat frequency analysis unit 1405. The beat frequency analysis unit 1405 outputs the received signals from the re-radiating elements #1 to #M separated into M distance blocks RB (if a received signal from the transmitting antenna is included, it is separated into M+1 distance blocks RB. FIG. 15 shows the received signal from the transmitting antenna included).

[0087] The distance separation unit 1406 outputs, for each reflected signal separated for each distance block RB received from the beat frequency analysis unit 1405, to Doppler analysis units 1407-1 to 1407-Loc as a distance based on the starting point of each distance block RB. The number of Doppler analysis units Loc is M×N, where M is the number of re-radiating elements and N is the number of transmitting antenna elements (if transmitting antenna elements are included, Loc=(M+1)×N)). For example, for a transmission signal radiated from transmitting antenna #1, RB#0 is output to Doppler analysis unit 1407-1, and RB#1 is output to Doppler analysis unit 1407-2.

[0088] Each of the Doppler analysis units 1407-1 to 1407-Loc performs Doppler analysis on the reflected signal of the distance block RB input from the distance separation unit 1406.

[0089] The CFAR unit 1408 performs adaptive threshold determination using the outputs of the Loc Doppler analyzers 1407-1 to 1407-Loc, and extracts the distance index and Doppler frequency index that give the peak signal.

[0090] The direction estimation unit 1409 performs a direction estimation process for the target using outputs from Loc Doppler analysis units 1407-1 to 1407-Loc at the distance index and Doppler frequency index that give the peak signal extracted by the CFAR unit 1408, and outputs angle measurement information such as the azimuth or elevation angle of the target as a positioning result, together with the distance information and Doppler information at the distance index and Doppler frequency index.

[0091] (Variation 1) 16, a first modification of the eighth embodiment turns on / off a switch included in a re-radiating element. For example, each re-radiating element re-radiates a transmission signal radiated from a transmitting antenna element while the switch is turned on, and does not re-radiate the transmission signal while the switch is turned off.

[0092] 17, the switches of the re-radiating elements are controlled by the control unit 114 and turned on in order. M It later turns ON and re-radiates the transmission signal radiated from the transmitting antenna element.

[0093] (Variation 2) In the second modification of the eighth embodiment shown in Fig. 18, the beam of the transmission signal radiated by the transmitting antenna element is narrowed and radiated to the re-radiating elements in sequence. The timing at which the transmitting antenna element radiates the transmission signal to each re-radiating element is controlled, thereby controlling the radiation timing of each re-radiating element. The re-radiating elements control the directivity (beam) during re-radiation. The directivity of the signals radiated by all the re-radiating elements is the same.

[0094] <Ninth Embodiment> In the radar device according to the ninth embodiment shown in FIG. 19, in the first to eighth embodiments, each re-radiating element converts the polarized wave to be radiated into an orthogonal polarized wave (for example, vertical / horizontal polarized wave, right-handed / left-handed circularly polarized wave). The polarization conversion unit may convert the polarization in a fixed manner, or may switch the polarized wave to be radiated under the control of the control unit 114. For example, the re-radiating element 120-1 converts the polarized wave (for example, vertical polarized wave) of the transmission signal into an orthogonal polarized wave (for example, horizontal polarized wave) and re-radiates the converted signal, while the re-radiating element 120-2 (including a transparent re-radiating element) re-radiates the transmission signal without converting the polarization. For example, the re-radiating element 120-1 converts the transmission signal into a right-handed circularly polarized wave and re-radiates it, while the re-radiating element 120-2 converts the received transmission signal into a left-handed circularly polarized wave and re-radiates it.

[0095] 20A shows vertically polarized waves, FIG. 20B shows horizontally polarized waves, FIG. 20C shows right-handed circularly polarized waves, and FIG. 20D shows left-handed circularly polarized waves.

[0096] <Tenth Embodiment> In the tenth embodiment, a vehicle equipped with the radar module 110 and the re-radiation unit 120 in the first to ninth embodiments will be described with reference to FIG.

[0097] The radar module 110 is installed in the front of the roof inside the vehicle. The radar module 110 may be a thin radar device equipped with a thin end-fire antenna, for example, as shown in Figs. 22 and 23 (for example, Patent Documents 4 and 5).

[0098] The thin radar device has a circuit board 2201, a signal processing IC 2202, a connector 2203, and transmitting / receiving antennas 113 and 115 arranged inside a main body made up of a housing 2207 and a dielectric lens 2204 arranged in a window 2205 of the housing 2207. The window 2205 is an area of ​​the housing 2207 that is permeable to radio waves.

[0099] A signal processing IC 2202 mounted on a circuit board 2201 processes a transmission signal 2206 transmitted from the transmission / reception antennas 113 and 115, each of which is composed of a plurality of antenna elements, and a reception signal received by the transmission / reception antenna, and communicates with an external device such as a vehicle ECU via a connector 2203. The transmission / reception antennas 113 and 115 are disposed at a position that is the focal point of a dielectric lens 2204. The dielectric lens 2204 narrows the radio wave beam of the transmission signal 2206 and converts it into a plane wave, radiates the plane wave toward a forward region (x2 axis direction) outside the device, and focuses a received reflected signal onto the transmission / reception antennas 113 and 115. The signal processing IC 2202 may be composed of a millimeter wave band IC 2202-1 and a baseband band IC 2202-2.

[0100] The re-radiation unit 120 is configured, for example, on a transparent film on the z1y1 plane. By configuring the re-radiation unit 120 as a re-radiation unit in which re-radiation elements are arranged on a transparent film, the re-radiation elements can be arranged anywhere on the windshield. Note that, as shown in FIG. 21, the x1 axis on which the re-radiation unit 120 is arranged and the x2 axis on which the radar module 110 is arranged do not have to be parallel.

[0101] The re-radiating elements on the transparent film are controlled by a control unit 114 in the radar module 110. The control unit 114 and the re-radiating elements can communicate with each other using transparent electrodes on the transparent film.

[0102] Even when a radar module with low resolution in the longitudinal direction (vertical direction, z2 axis direction) is used, the resolution in the longitudinal direction can be improved by combining it with a re-radiating element.

[0103] In the above-described embodiments, the notation "...device" used for each component may be replaced with other notations such as "...circuitry," "...assembly," "...device," "...unit," or "...module."

[0104] The present disclosure can be realized by software, hardware, or software linked to hardware. Each functional block used in the description of the above embodiments may be partially or entirely realized as an LSI, which is an integrated circuit, and each process described in the above embodiments may be partially or entirely controlled by a single LSI or a combination of LSIs. The LSI may be composed of individual chips, or may be composed of a single chip that includes some or all of the functional blocks. The LSI may have data input and output. Depending on the degree of integration, the LSI may be called an IC, system LSI, super LSI, or ultra LSI.

[0105] The integrated circuit method is not limited to LSI, but may be realized by a dedicated circuit, a general-purpose processor, or a dedicated processor. Also, a field programmable gate array (FPGA) that can be programmed after LSI manufacturing, or a reconfigurable processor that can reconfigure the connections and settings of circuit cells within the LSI, may be used. The present disclosure may be realized as digital processing or analog processing.

[0106] Furthermore, if an integrated circuit technology that can replace LSI emerges due to advances in semiconductor technology or other derivative technologies, it is natural that such technology can be used to integrate functional blocks. The application of biotechnology, etc. is also a possibility.

[0107] (1) A radar device according to one aspect of the present disclosure includes a radar module having a transmitting antenna for transmitting a transmission signal, and a re-radiating unit having a re-radiating element for re-radiating the transmission signal. (2) In a radar device according to an aspect of the present disclosure, in the radar device of (1), the re-radiating unit has at least two of the re-radiating elements. (3) In a radar device according to one aspect of the present disclosure, in the radar device of (2), one of the re-radiating elements is a transparent re-radiating element. (4) In a radar device according to one aspect of the present disclosure, in the radar device of (1), the re-radiating element is configured with an element having a metamaterial structure. (5) A radar device according to one aspect of the present disclosure is the radar device according to (1), wherein the re-radiating element is disposed on a transparent film. (6) In a radar device according to one aspect of the present disclosure, in the radar device of (4), the element having the metamaterial structure controls the directivity of the re-radiated signal. (7) In a radar device according to an aspect of the present disclosure, in the radar device of (2), the signals re-radiated by the re-radiating elements are orthogonal to each other. (8) In a radar device according to one aspect of the present disclosure, in the radar device of (7), the re-radiating element delays the re-radiated signal. (9) A radar device according to an aspect of the present disclosure is the radar device of (8), further comprising a control unit that controls the re-radiating element to delay the signal. (10) A radar device according to one aspect of the present disclosure is the radar device of (9), further comprising a plurality of the radar modules and a plurality of the re-radiation units, and the control unit controls the plurality of the radar modules and the plurality of the re-radiation units. (11) A radar device according to one aspect of the present disclosure is a radar device according to (1), wherein the re-radiating unit has a re-radiating element composed of elements having a plurality of metamaterial structures, and further includes a control unit that controls the ON and OFF of the plurality of elements in a time-division manner. (12) In a radar device according to an aspect of the present disclosure, in the radar device of (4), the re-radiating unit has a re-radiating element configured with elements having a plurality of metamaterial structures, The re-radiating element, which is made up of elements having the plurality of metamaterial structures, forms and outputs a predetermined beam. (13) In one aspect of the present disclosure, the radar device is the radar device of (11), wherein the transmitting antenna has a plurality of transmitting antenna elements, and the plurality of transmitting antenna elements transmit code-multiplexed or Doppler-multiplexed transmission signals. (14) In one aspect of the present disclosure, the radar device is the radar device of (11) or (12), wherein the transmitting antenna has a plurality of transmitting antenna elements, and the element having the metamaterial structure code-multiplexes or Doppler-multiplexes the re-radiated signal. (15) In one aspect of the present disclosure, the radar device is the radar device of (11) or (12), wherein the transmitting antenna has a plurality of transmitting antenna elements, the plurality of transmitting antenna elements transmit Doppler-multiplexed transmission signals, and the element having the metamaterial structure code-multiplexes the re-radiated signals. (16) In one aspect of the present disclosure, the radar device is the radar device of (14) or (15), wherein the re-radiating unit has at least two re-radiating elements each composed of a plurality of elements having the metamaterial structure. (17) In one aspect of the present disclosure, the radar device is the radar device of (8), wherein the transmission signal is a chirp signal and the delay is a delay based on the maximum detection range of the radar device. (18) A radar device according to one aspect of the present disclosure is the radar device of (17), wherein the re-radiating unit has a plurality of re-radiating elements, the transmission signal is a chirp signal, and the time difference for delaying the signal between the two re-radiating elements is greater than twice the value obtained by dividing the maximum detection range of the radar device by the speed of light. (19) In one aspect of the present disclosure, the radar device is the radar device of (18), wherein the radar module separates the reflected signal, which is the transmitted signal reflected by the target, into reflected signals, which are signals re-radiated by each re-radiating element and reflected by the target, based on the delay. (20) In one aspect of the present disclosure, the radar device is the radar device of (9), wherein the re-radiating unit has a switch corresponding to the re-radiating element, and the control unit controls the switch to delay the signal. (21) In one aspect of the present disclosure, a radar device is the radar device of (7), wherein the re-radiating unit has a plurality of re-radiating elements, and the transmitting antenna changes its directivity and sequentially radiates a transmission signal to the plurality of re-radiating elements. (22) In a radar device according to one aspect of the present disclosure, in the radar device of (2), the plurality of re-radiating elements re-radiate the transmission signals with polarizations orthogonal to each other. (23) A vehicle according to one aspect of the present disclosure is equipped with the radar device of (1). (24) In one aspect of the present disclosure, the vehicle of (23) is such that the radar module is installed on the roof of the vehicle and the re-radiation unit is installed on the windshield of the vehicle. [Industrial Applicability]

[0108] The present disclosure is useful for radar devices and vehicles. [Explanation of symbols]

[0109] 110 Radar Module 111 Radar transmission signal generator 112 Radio transmitter 113 Transmitting Antenna 113-1~113-N Transmitting antenna elements 114 Control Unit 115 Receiving Antenna 116 Radio receiving unit 117 Signal Processing Unit 118 Radar transmitter 119 Radar receiver 120 Re-radiating section 120-1~120-M Re-radiating element 130 targets 140 Integrated Control Unit 1401 Antenna system processing unit 1402 Mixer section 1403 LPF 1404 AD conversion unit 1405 Beat Frequency Analysis Unit 1406 Distance separation section 1407 Doppler analysis unit 1408 CFAR Department 1409 Direction estimation part 2201 Circuit Board 2202 Signal Processing IC 2202-1 Millimeter-wave band IC 2202-2 Baseband IC 2203 Connector 2204 Dielectric Lens 2205 Window 2206 Transmitted Signal 2207 Case

Claims

1. a radar module having a transmitting antenna for transmitting a transmission signal; a re-radiating unit having a re-radiating element that re-radiates the transmission signal; A radar device comprising:

2. The re-radiating unit has at least two of the re-radiating elements. The radar device according to claim 1 .

3. one of the re-radiating elements is a transparent re-radiating element; The radar device according to claim 2 .

4. The re-radiating element is composed of an element having a metamaterial structure. The radar device according to claim 1 .

5. the re-radiating element is disposed on a transparent film; The radar device according to claim 1 .

6. The element having the metamaterial structure controls the directionality of the re-radiated signal. The radar device according to claim 4.

7. The re-radiating elements are configured such that the signals re-radiated by each re-radiating element are orthogonal. The radar device according to claim 2 .

8. the re-radiating element delays the re-radiated signal; The radar device according to claim 7.

9. Further, a control unit is provided that controls the re-radiating element to delay the signal. The radar device according to claim 8.

10. a plurality of the radar modules and a plurality of the re-radiation units; the control unit controls the plurality of radar modules and the plurality of re-radiation units. The radar device according to claim 9, comprising:

11. the re-radiating unit has a re-radiating element configured with a plurality of elements having a metamaterial structure, Further provided is a control unit that controls the ON and OFF of a plurality of elements having the metamaterial structure in a time division manner. The radar device according to claim 4.

12. the re-radiating unit has a re-radiating element configured with a plurality of elements having a metamaterial structure, The radar device according to claim 4, wherein the re-radiating element, which is made up of a plurality of elements having a metamaterial structure, forms and outputs a predetermined beam.

13. the transmitting antenna has a plurality of transmitting antenna elements; The plurality of transmitting antenna elements transmit code-multiplexed or Doppler-multiplexed transmission signals. The radar device according to claim 11 or 12.

14. the transmitting antenna has a plurality of transmitting antenna elements; The element having the metamaterial structure code-multiplexes or Doppler-multiplexes the re-radiated signal. The radar device according to claim 11 or 12.

15. the transmitting antenna has a plurality of transmitting antenna elements; the plurality of transmitting antenna elements transmit code-multiplexed or Doppler-multiplexed transmission signals; The element having the metamaterial structure code-multiplexes or Doppler-multiplexes the re-radiated signal. The radar device according to claim 11 or 12.

16. The re-radiating unit has at least two re-radiating elements each composed of a plurality of elements having the metamaterial structure. The radar device according to claim 14 or 15.

17. the transmission signal is a chirp signal, The delay is based on the maximum detection range of the radar device. The radar device according to claim 8.

18. the re-radiating section has a plurality of re-radiating elements, the transmission signal is a chirp signal, a time difference between the two re-radiating elements for delaying the signals is greater than twice the maximum detection range of the radar device divided by the speed of light; The radar device according to claim 17.

19. The radar module separates the reflected signals of the transmitted signals reflected by the target into reflected signals of the signals re-radiated by each re-radiating element reflected by the target based on the delay. The radar device according to claim 18.

20. the re-radiating unit has a switch corresponding to the re-radiating element, The control unit controls the switch to delay the signal. The radar device according to claim 9.

21. the re-radiating section has a plurality of re-radiating elements, The transmitting antenna changes its directivity and sequentially radiates a transmission signal to the plurality of re-radiating elements. The radar device according to claim 7.

22. The plurality of re-radiating elements re-radiate the transmission signal with mutually orthogonal polarizations. The radar device according to claim 2 .

23. A vehicle equipped with the radar device according to claim 1.

24. The radar module is mounted on the roof of a vehicle; The re-radiation unit is installed on the windshield of the vehicle.

24. The vehicle of claim 23.

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