JP2018204974A - Radar device - Google Patents

Abstract

A radar device capable of widening a detection area while suppressing erroneous detection due to the influence of a grating lobe. An element antenna 1-1 to 1-4 constituting an array antenna and a transceiver 4-1 capable of transmitting and receiving signals at a plurality of frequencies via the element antennas 1-1 to 1-4. 4-2, and a signal processor 6 that determines whether the target has been detected by the main lobe or the grating lobe based on signals received at a plurality of frequencies. [Selection] Figure 1

Description

  The present invention relates to a radar apparatus that detects a target by transmitting and receiving radio waves using a plurality of antennas.

  When the phased array method is applied to the radar apparatus as an electronic scanning antenna, the radiation beam can be scanned by setting the phase of each element antenna constituting the array antenna. In the array antenna, an unnecessary beam called a grating lobe is generated. The angle at which the grating lobe is generated depends on the element antenna interval. In a radar device using an electronic scanning antenna, when a grating lobe is generated, it is difficult to discriminate whether the target, that is, the target was detected with the main lobe corresponding to the set beam direction or with the grating lobe. . For this reason, there is a possibility that a false detection may occur such that the target originally detected by the grating lobe is processed as being detected by the main lobe.

  As a method for preventing the grating lobe, there is a method of determining the element antenna interval to an appropriate value so that the grating lobe does not occur in the electronic scanning range in the design of the array antenna.

  However, the element antenna interval may not be set to the appropriate value described above due to conditions other than the grating lobe. As a technique capable of suppressing the influence of the grating lobe even when the element antenna interval is limited, there is a technique described in Patent Document 1. In the technique described in Patent Document 1, the transmission pattern is formed so that the power is reduced at the angle at which the grating lobe is generated, using the fact that the azimuth resolution of the radar apparatus is determined by the transmission / reception product of the reception pattern and the transmission pattern. Therefore, the influence of the grating lobe is suppressed.

Japanese Patent Laid-Open No. 11-23310

  However, according to the technique described in Patent Document 1, the transmission / reception product, that is, the antenna gain, decreases in a wide-angle region where a grating lobe occurs. For this reason, there has been a problem in that there is a restriction in widening the detection area.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a radar apparatus capable of widening a detection region while suppressing erroneous detection due to the influence of a grating lobe.

  In order to solve the above-described problems and achieve the object, a radar apparatus according to the present invention includes an array antenna and a transceiver capable of transmitting and receiving signals via the array antenna at a plurality of frequencies. . The radar apparatus includes a signal processor that determines whether a target has been detected by a main lobe or a grating lobe based on signals received at a plurality of frequencies.

  According to the present invention, the detection area can be widened while suppressing erroneous detection due to the influence of the grating lobe.

1 is a diagram illustrating a configuration example of a radar apparatus according to a first embodiment. Schematic diagram illustrating an example of arrayed element antennas according to the first embodiment FIG. 5 is a diagram illustrating a configuration example of a control circuit when the processing circuit of the first embodiment is a control circuit. The figure which shows the calculation result of Formula (1) in the case of N = 11 The figure which shows an example of the difference in the position of the grating lobe by the difference in the excitation frequency The figure which shows an example of the difference in the position of the grating lobe by the difference in the excitation frequency at the time of shifting a directivity direction 6 is a flowchart illustrating an example of a processing procedure in the radar apparatus according to the first embodiment. The figure which shows the structural example of the radar apparatus concerning Embodiment 2.

  Hereinafter, a radar apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a configuration example of a radar apparatus according to a first embodiment of the present invention. As shown in FIG. 1, the radar apparatus 10 according to the present embodiment includes element antennas 1-1 to 1-4, RF (Radio Frequency) modules 2-1 to 2-4, and power feeding circuits 3-1 and 3-2. , Transceivers 4-1, 4-2, DBFP (Digital Beam Forming Processor) 5, and signal processor 6. Hereinafter, when the element antennas 1-1 to 1-4 are shown without being individually distinguished, they are described as the element antenna 1, and when the RF modules 2-1 to 2-4 are shown without being individually distinguished, the RF module 2 is described. It describes. Also, when the power feeding circuits 3-1 and 3-2 are shown without being individually distinguished, they are described as a power feeding circuit 3, and when the transceivers 4-1 and 4-2 are shown without being individually distinguished, the transceiver 4 is shown. It describes.

  The element antennas 1-1 to 1-4, the RF modules 2-1 to 2-4, and the power feeding circuits 3-1 and 3-2 according to the present embodiment are array antennas that can form a beam by digital forming based on the subarray method. Configure. Digital forming is a technique for realizing phase synthesis by sampling a received signal received by an element antenna and performing phase processing on a digital memory without using a phase shifter in an array antenna. Digital forming includes a full array system in which a receiver is provided for each antenna, and a subarray system in which a plurality of element antennas are grouped and a receiver is provided for each group. In the sub-array method described in this embodiment, it is not necessary to arrange a receiver for each antenna, and hardware cost and hardware size can be suppressed.

  FIG. 1 shows an example in which the number of element antennas 1 constituting each group is two. In the example shown in FIG. 1, for example, the element antenna 1-1 and the element antenna 1-2 belong to the same group, and are connected to the same transceiver 4-1 via the same power supply circuit 3-1. In FIG. 1, four sets of element antennas 1 and RF modules 2 are shown, and an example in which two sets are grouped into one group is shown. However, the number of sets of element antennas 1 and RF modules 2 is as follows. Without being limited to this example, the number of sets of element antennas 1 and RF modules 2 is N (N is an integer of 2 or more). In FIG. 1, two sets of the power feeding circuit 3 and the transmitter / receiver 4 are illustrated, but the power feeding circuit 3 and the transmitter / receiver 4 are provided according to the above-described N and the number of element antennas constituting one group. FIG. 1 shows an example in which the number of element antennas 1 constituting each group is 2, but the number of element antennas 1 constituting each group is not limited to the example shown in FIG.

  The element antennas 1 can transmit and receive radio waves and are arranged at equal intervals. FIG. 2 is a schematic diagram illustrating an example of the arrayed element antennas 1. In the example illustrated in FIG. 2, the element antennas 1-1 to 1-10 are illustrated with N = 10, and the distance between the element antennas 1 is d.

  The RF module 2 is an analog circuit including an amplifier, a frequency converter, and the like. The RF module 2 performs processing such as amplification and frequency conversion on the transmission signal input from the power feeding circuit 3 and transmits the processed transmission signal from the element antenna 1. Further, the RF module 2 performs processing such as amplification and frequency conversion on the reception signal received by the element antenna 1 and inputs the processed reception signal to the power feeding circuit 3. The RF module 2 may include a phase shifter, and electronic scanning may be performed using the phase shifter to control the directivity direction. In this case, if the transmission phase by the direction cosine is similarly set for the received signal, a multi-beam can be formed by superimposing the digital beam tilt setting value of the DBF processing of the received signal.

  The power feeding circuit 3 distributes the transmission signal input from the transmitter / receiver 4 into two and outputs them to the two RF modules 2, respectively. The power feeding circuit 3 inputs reception signals input from the two RF modules 2 to the transceiver 4.

  The transceiver 4 generates a transmission signal and inputs the generated transmission signal to the power feeding circuit 3. The transceiver 4 samples the received signal input as an analog signal from the power feeding circuit 3 and converts it into a digital signal, and inputs the converted received signal to the DBFP 5. The transceiver 4 can transmit and receive signals at a plurality of frequencies via the above-described array antenna.

  The DBFP 5 is dedicated hardware that executes the DBF. That is, the DBFP 5 adjusts the phase and amplitude of the reception signal input from the transceiver 4 and inputs the adjusted reception signal to the signal processor 6. A reception beam is formed by adjusting the phase and amplitude of the reception signal. The specific method of DBF in this embodiment is not particularly limited, and a method used in general DBF can be used.

  The signal processor 6 uses the reception signal input from the DBFP 5 to perform a detection process for detecting the arrival direction of the reception signal, that is, the target direction. In the present embodiment, the signal processor 6 performs detection processing using the received signals respectively received at two frequencies, and estimates the target orientation based on the detection processing results corresponding to the two frequencies. . Specifically, the signal processor 6 determines whether the target has been detected by the main lobe or the grating lobe based on signals received at a plurality of frequencies. Note that any method may be used as the detection processing method for recognizing the direction of the target, and a method used in general detection processing may be used.

  The signal processor 6 is realized by a processing circuit. The processing circuit may be dedicated hardware or a control circuit including a processor. When the processing circuit is dedicated hardware, the processing circuit includes a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), Or a combination of these.

  FIG. 3 is a diagram illustrating a configuration example of a control circuit when the processing circuit is a control circuit. The control circuit 503 illustrated in FIG. 3 includes a processor 501 and a memory 502. The processor 501 is a CPU (Central Processing Unit), a microprocessor, or the like. The memory 502 corresponds to, for example, a nonvolatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), and a flash memory.

  When the signal processor 6 is realized by the control circuit 503, a program for realizing the function of the signal processor 6 is stored in the memory 502, and the program is executed by the processor 501, thereby the signal processor 6. The function is realized. The memory 502 is also used as a storage area when a program is executed by the processor 501. Further, the signal processor 6 may be realized by a processing circuit, a part of which is dedicated hardware, and the remaining part may be realized by the control circuit 503.

  Next, the operation of the present embodiment will be described. The radar apparatus 10 according to the present embodiment performs transmission / reception at two frequencies, performs detection processing using received signals respectively received at two frequencies, and based on detection processing results corresponding to the two frequencies, Estimate the orientation of the target. This suppresses erroneous detection due to the influence of the grating lobe. In order to explain this principle, first, a general theory of the position where a grating lobe is generated will be shown.

The grating lobe is generated by the periodicity of the array factor. The array factor is an index representing the directivity determined by the arrangement of the element antennas. The array factor is expressed by the following equation (1). U in the equation (1) is a function of θ and is represented by the equation (2). θ is an angle indicating the direction viewed from the array antenna, θ ₀ is the main lobe directing direction, N is the number of element antennas, λ is the wavelength of the signal to be transmitted and received, and d is the distance between the element antennas.

FIG. 4 is a diagram illustrating a calculation result of the expression (1) in the case of N = 11. A (u) shown in FIG. 4 represents the directivity characteristics of a one-dimensional array antenna in which the element antennas are arranged at equal intervals in the u coordinate. The visible region 11 indicates a visible region of the array antenna when the element antenna interval is d ₁ (= λ) and θ ₀ = 0, that is, a region of −π / 2 ≦ θ ≦ π / 2. The visible region 11 is −2π ≦ u ≦ 2π from the equation (2). The visible region 12 indicates the visible region of the array antenna when the element antenna interval is d ₁ (= λ) and θ ₀ = π. Since the visible region 12 is shifted by π from the case where the directing direction is θ ₀ = 0, the visible region 12 becomes −3π ≦ u ≦ π according to the equation (2), and the negative region u is smaller than the visible region 11. The direction is shifted by π. When the distance between the element antennas is d ₁ (= λ) and θ ₀ = 0, the visible region 11 includes part of the grating lobe 32 in addition to the main lobe 31, but at the end of the visible region 11. Since only some of them appear, the impact is small. On the other hand, the visible region 12 includes a grating lobe 32. In this case, it is difficult to determine whether the target is detected by the main lobe 31 or the grating lobe 32.

The visible region 13 indicates the visible region of the array antenna when the element antenna interval is d ₂ (= 2λ) and θ ₀ = 0. The visible region 13 is −4π ≦ u ≦ 4π from the equation (2). Also in this case, a plurality of grating lobes 32 are included, and the possibility of erroneous detection by the grating lobes 32 is further increased compared to when the element interval is d ₁ (= λ).

  As shown in FIG. 4, it is well known that the visible region changes depending on the distance d between the element antennas. That is, whether the grating lobe 32 exists in the visible region depends on the distance d between the element antennas. The phase difference between adjacent element antennas is as shown in the following formula (3) from the formula (1).

  Expression (3) means that a grating lobe is generated in the direction of θ when the phase difference between adjacent element antennas is 2nπ (n is an integer of 1 or more). When Expression (3) is transformed, the following Expression (4) is obtained.

  Equation (4) indicates the generation angle of the grating lobe. From the equation (4), it can be seen that the sine of the angle θ indicating the generation position of the grating lobe, that is, sin (θ) is proportional to the wavelength λ and inversely proportional to the distance d between the element antennas.

  From the above, in order to prevent the grating lobe from entering the visible medical treatment, a method of setting the element antenna interval d to the wavelength λ or less is conceivable. However, there may be a case where the element antenna interval d cannot be set to the wavelength λ or less due to a configuration problem. For example, when sub-array type digital beam forming is performed, the element antenna intervals are increased because the element antennas are grouped. For example, when the distance between the actual element antennas is d, and the two element antennas are grouped, the distance between the element antennas corresponds to 2d. For this reason, from FIG. 4 and Formula (4), compared with the case where the space | interval of an element antenna is d, the number of the grating lobes which enter a visible range increases. When a grating lobe is generated in a radar apparatus using an electronic scanning antenna, it is difficult to discriminate whether the main lobe is detected or the grating lobe is detected. For this reason, when a grating lobe occurs, the possibility of erroneous detection increases, and the azimuth resolution deteriorates. Further, even if the signal processing shifts from detection to tracking, accurate azimuth specification information cannot be obtained.

  As a method of suppressing the generation of grating lobes, a method of arranging element antennas at unequal intervals is also conceivable. However, when element antennas are arranged at unequal intervals, the number of element antennas at the same antenna length is smaller than that at equal intervals. Therefore, there is a problem that the effective radiated power is reduced.

  Here, focusing attention again on the equations (1), (2), and (4), the generation position of the grating lobe depends not only on the element antenna interval but also on the wavelength. In this embodiment, using this property, transmission / reception is performed at two or more frequencies, and the detection result at each frequency is compared, so that the main lobe is detected or the grating lobe is detected. It prevents false detections due to the fact that it cannot be determined.

  From Equations (1), (2), and (4), when the excitation frequency of the element antenna, that is, the excitation frequency of the signal transmitted or received by the element antenna is changed, only the position of the grating lobe has an action. For example, in the case of a one-dimensional array antenna, if the frequency is 9 GHz and the distance d between the element antennas is λ, that is, one wavelength, the grating lobe is generated at an azimuth angle of ± 90 degrees with respect to the main lobe. If the frequency is changed from 9 GHz to 10 GHz while leaving the element antenna interval as it is, the grating lobe moves about 25.8 degrees toward the main lobe side.

  FIG. 5 is a diagram illustrating an example of a difference in grating lobe position due to a difference in excitation frequency. In FIG. 5, the antenna factors are shown with respect to the azimuth angle θ when the element antenna intervals are the same and the excitation frequencies are three types of 9 GHz, 9.5 GHz, and 10 GHz. The position of the main lobe 24 matches in the cases of 9 GHz, 9.5 GHz, and 10 GHz, but the generation position of the grating lobe varies depending on the excitation frequency. The grating lobe 21 is a grating lobe when the excitation frequency is 9 GHz, the grating lobe 22 is a grating lobe when the excitation frequency is 9.5 GHz, and the grating lobe 23 is a grating lobe when the excitation frequency is 10 GHz. It is.

  FIG. 6 is a diagram illustrating an example of a difference in grating lobe position due to a difference in excitation frequency when the directivity direction is shifted. FIG. 6 shows the antenna factor when the pointing direction in the azimuth direction is shifted by +10 degrees, that is, when scanning is performed so as to shift the position of the main lobe. In the example shown in FIG. 6, as in FIG. 5, the antenna factor is shown with respect to the azimuth angle θ when the distance between the element antennas is the same and the excitation frequencies are three types of 9 GHz, 9.5 GHz, and 10 GHz. ing. Also in this case, the position of the main lobe 28 is the same in the cases of 9 GHz, 9.5 GHz, and 10 GHz, but the generation position of the grating lobe differs depending on the excitation frequency. The grating lobe 25 is a grating lobe when the excitation frequency is 9 GHz, and is maximum at an azimuth angle of −55.3 degrees. The grating lobe 26 is a grating lobe when the excitation frequency is 9.5 GHz, and is maximum at an azimuth angle of −51.1 degrees. The grating lobe 27 is a grating lobe when the excitation frequency is 10 GHz, and is maximum at an azimuth angle of −47.7 degrees.

  Thus, the generation position of the main lobe does not change with the excitation frequency, and the generation position of the grating lobe changes with the excitation frequency. In this embodiment, by using this property and performing transmission and reception at a plurality of excitation frequencies, the detection of the target by the main lobe and the detection of the target by the grating lobe are discriminated.

  Next, the operation of the present embodiment will be described. FIG. 7 is a flowchart showing an example of a processing procedure in the radar apparatus 10 of the present embodiment. FIG. 7 shows an example in which the radar apparatus 10 performs transmission / reception using two frequencies. As shown in FIG. 7, the radar apparatus 10 performs transmission / reception at the first frequency (step S1).

  Specifically, in step S1, for example, the following operation is performed. The signal processor 6 or a control circuit (not shown) instructs the transceiver 4 to perform transmission at the first frequency. The transceiver 4 generates a transmission signal corresponding to the first frequency, and transmits the transmission signal via the array antenna, that is, via the feeder circuit 3, the RF module 2, and the element antenna 1. Note that the frequency of the transmission signal generated by the transceiver 4 is a frequency that becomes the first frequency after the frequency conversion when the RF module 2 performs the frequency conversion, and the RF module 2 performs the frequency conversion. If not, it is the first frequency. Next, the signal processor 6 or a control circuit (not shown) instructs the transceiver 4 to perform reception at the first frequency. At this time, the signal processor 6 or a control circuit (not shown) also instructs the DBFP 5 in the direction of direction, that is, the direction of the center of the main lobe. Thus, when the target reflects the transmission signal transmitted from the radar apparatus 10, the reflected signal is received by the transceiver 4 via the element antenna 1, the RF module 2, and the power feeding circuit 3. The transceiver 4 converts the received signal into a digital signal and inputs it to the DBFP 5. The DBFP 5 performs digital beam forming on the input signal and inputs the processed signal to the signal processor 6.

  Next, the radar apparatus 10 performs transmission / reception at the second frequency (step S2). The operation of the radar device 10 in step S2 is the same as that in step S1 except that the frequency is changed from the first frequency to the second frequency.

  Next, the radar apparatus 10 performs target detection processing for each of the first frequency and the second frequency (step S3). Specifically, the signal processor 6 performs target detection processing for each of the first frequency and the second frequency. FIG. 7 shows an example in which step S3 is performed after step S2, but the target detection process at the first frequency may be performed between step S1 and step S2.

  Next, the signal processor 6 of the radar apparatus 10 determines whether or not the target has been detected at both the first frequency and the second frequency (step S4), and when the target has been detected at both (step S4 Yes). ), It is determined that the target has been detected by the main lobe, the direction of the target is determined (step S5), and the process is terminated. That is, the signal processor 6 determines the direction of the target on the assumption that the target exists in the set directivity direction.

  When the target is detected at either the first frequency or the second frequency (No in step S4), it is determined that the target has been detected by the grating lobe, and the direction of the target is determined by correction (step S4). S6) The process is terminated. The correction at this time means correcting the difference in position between the main lobe and the grating lobe from the directivity direction. For example, assume that the first frequency is 9 GHz and the second frequency is 9.5 GHz. At this time, it is assumed that the target exists in the vicinity of an azimuth angle of −71 degrees. In this case, as illustrated in FIG. 5, the grating lobe 22 exists in the vicinity of the azimuth angle of −71 degrees at the second frequency of 9.5 GHz, so that the target can be detected, but the first frequency is It cannot be detected at 9 GHz. Therefore, the signal processor 6 determines that the target is detected not by the main lobe but by the grating lobe, and when the target is present in the corrected direction, that is, the second frequency grating lobe, instead of the main lobe directing method. judge. On the other hand, when the target is present at around 0 degrees, the target is detected at both the first frequency and the second frequency, and therefore the signal processor 6 determines that the target is present in the pointing direction.

  If the target is not detected at either the first frequency or the second frequency in step S3, the signal processor 6 determines that the target has not been detected in either the main lobe or the grating lobe and performs processing. Exit. In the example described above, the plurality of frequencies that can be transmitted / received by the transceiver 4 includes the first frequency and the second frequency, and the transceiver 4 transmits / receives at the second frequency after transmitting / receiving at the first frequency. Although the example which performs is demonstrated, the specific process sequence is not limited to the example mentioned above.

  The shift amount of the grating lobe depends on the difference in the set frequency. For this reason, the frequency difference may be determined according to the beam width requirement of the radar apparatus system. For example, assuming that the first frequency is 9 GHz, the element antenna interval is 1 wavelength (33 mm), and the second frequency is 9.5 GHz, the second frequency has a grating lobe as compared with the first frequency. The generation position is shifted about 18.7 degrees inward, that is, toward the main lobe. Although the interval between the main lobe and the grating lobe varies depending on the frequency, there is no problem in the function as the radar apparatus 10 because it does not affect the directing direction of the main lobe.

  As described above, the radar apparatus 10 estimates the presence direction of the target using the results of transmission / reception at a plurality of frequencies. For this reason, unlike the technique described in Patent Document 1, it is not necessary to suppress power in the region where the grating lobe exists. Thereby, in the present embodiment, it is possible to widen the detection region while suppressing erroneous detection due to the influence of the grating lobe.

  In the above description, an example has been described in which transmission / reception is performed at two frequencies and whether the detection is performed with the main lobe or the grating lobe using the signals received at the respective frequencies. Transmission / reception may be performed at a frequency, and it may be determined whether detection is performed using a main lobe or a grating lobe using signals received at each frequency. For example, the radar apparatus 10 performs transmission / reception at three frequencies from the first frequency to the third frequency, and when the target is detected at all of these frequencies, it is determined that the target has been detected in the main lobe. If the target is detected at one of the three frequencies and not detected at the other frequency, it may be determined that the detection is performed by the grating lobe.

  In the above description, the configuration and operation example of performing sub-array type digital beam forming have been described. However, the operation of the present embodiment can also be applied to the case of performing full array type digital beam forming. Further, not only a one-dimensional array antenna but also a planar array antenna can obtain the same effect as this embodiment by applying the operation of this embodiment.

Embodiment 2. FIG.
FIG. 8 is a diagram illustrating a configuration example of the radar apparatus according to the second embodiment of the present invention. As shown in FIG. 8, the radar apparatus 10a of this embodiment includes element antennas 1-1 to 1-4, RF modules 2-1 to 2-4, transceivers 4a-1 to 4a-4, a DBFP 5a, and signals. A processing machine 6 is provided. Hereinafter, when the transceivers 4a-1 to 4a-4 are shown without being individually distinguished, they are referred to as a transceiver 4a. Constituent elements having the same functions as those in the first embodiment are denoted by the same reference numerals and redundant description is omitted. Hereinafter, differences from the first embodiment will be described.

  The element antennas 1-1 to 1-4 and the RF modules 2-1 to 2-4 of the present embodiment are array antennas that can form a beam by digital forming using a full array method.

  The transceiver 4a of the present embodiment can transmit and receive a broadband signal. That is, the transmitter / receiver 4a generates a broadband signal such as a chirp signal or a broadband spike pulse and inputs it to the RF module 2, converts the received signal received from the RF module 2 into a digital signal, and inputs the digital signal to the DBFP 5a. The transceiver 4a can transmit and receive a wideband signal of, for example, a 500 MHz band. The wideband signal includes signals of a plurality of frequencies that can be transmitted by the transceiver 4a.

  The radar apparatus 10a is an apparatus that performs full array type digital beam forming. Therefore, the DBFP 5a performs full array type digital beam forming. The signal processor 6a extracts signals corresponding to a plurality of frequencies from the wideband received signal input from the DBFP 5a, and detects the target using the signals of the plurality of frequencies in the same manner as in the first embodiment. Then, as in the first embodiment, it is determined whether the target is detected by the main lobe or the grating lobe depending on whether the target is detected at a plurality of frequencies. The operations of the present embodiment other than those described above are the same as those of the first embodiment.

  Although FIG. 8 shows a radar apparatus that performs digital beam forming using the full array method, the operation of this embodiment can also be applied to a radar apparatus that performs digital beam forming using the sub-array method.

  As described above, in the present embodiment, the radar apparatus 10a that transmits and receives a wideband signal is configured to estimate the target direction in the same manner as in the first embodiment based on signals of a plurality of frequencies among the wideband signals. did. For this reason, it is possible to achieve the same effect as that of the first embodiment by using a broadband signal transmitted and received at a time.

  The configuration described in the above embodiment shows an example of the contents of the present invention, and can be combined with another known technique, and can be combined with other configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

  1-1 to 1-10 element antenna, 2-1 to 2-4 RF module, 3-1, 3-2 feeding circuit, 4-1, 4-2, 4a-1 to 4a-4 transceiver, 5, 5a DBFP, 6, 6a Signal processor, 10, 10a Radar device.

Claims (6)

An array antenna,
A transceiver capable of transmitting and receiving signals at a plurality of frequencies via the array antenna;
A signal processor for determining whether the target is detected in the main lobe or the grating lobe based on the signals received at the plurality of frequencies;
A radar apparatus comprising: The plurality of frequencies includes a first frequency and a second frequency;
The radar apparatus according to claim 1, wherein the transceiver performs transmission and reception at a second frequency after performing transmission and reception at a first frequency.   The radar apparatus according to claim 1, wherein the transceiver transmits and receives a wideband signal including signals of the plurality of frequencies.   The radar apparatus according to any one of claims 1 to 3, wherein digital beam forming is performed by a subarray method.   4. The radar apparatus according to claim 1, wherein digital beam forming is performed by a full array method.   The radar apparatus according to claim 1, wherein the element antennas constituting the array antenna are equally spaced.

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