JP2005062058A - Search radar system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a search radar system capable of performing observation with high target detection accuracy. <P>SOLUTION: Radar transmission signal is produced by a transmission circuit 5, a reflection signal from a target of radar transmission signal transmitted from an antenna part 9 arranging a plurality of antenna elements in an array, toward a space is received by every antenna element, and a plurality of corresponding digital element signals are derived. Then, a multi-reception beam consisting of a plurality of reception beams is formed against the derived plurality of corresponding digital element signals. The distance from the self device to the target is output by detecting the target from the output of the multi-reception beam. According to the distance to the target, the beam number effective for forming the multi-reception beam is output from the beam corresponding table. A reception beam corresponding to the beam number is controlled by a control circuit 25 so as to turn on the reception beam. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an improvement of a search radar apparatus suitable for obtaining target position information as three-dimensional information.

  As a search radar that obtains the target position as three-dimensional information, an antenna is constructed so that a large number of pencil beams are arranged adjacent to each other in the vertical plane (elevation plane), and the target radar is rotated in a horizontal plane. There is a multi-beam method for searching (see Non-Patent Document 1, for example).

  When the search radar antenna is configured with an array antenna and the target position is obtained as three-dimensional information, a cosecant beam shape that covers the space in the vertical plane (elevation plane) over a wide area is set during transmission. , And at the time of reception, a target is detected by forming a multi-reception beam in which a large number of pencil beams having substantially the same beam width are arranged adjacent to each other in a vertical plane by digital processing using DBF (Digital Beam Forming). The method is adopted.

  When three-dimensional information of a target is obtained by forming a multi-reception beam by an array antenna, as shown in FIG. 10, after detecting a target with many pencil beams adjacent to each other in a vertical plane, the target after the detection is detected. In order to increase the detection rate in tracking operation or the like, a multi-beam radar device that controls the number of beams or the beam interval of multi-received beams based on detected target distance data or the like has been proposed (for example, see Patent Document 1). .)

In any case, in a search radar equipped with an array antenna, a large number of pencil beams having substantially the same beam width are adjacently arranged in the vertical plane to form a multi-reception beam to obtain target three-dimensional information. It is configured as follows.
“Revised Radar Technology”, The Institute of Electronics, Information and Communication Engineers, October 1, 1996, p. 286 JP 2000-171551 A

  As described above, in a conventional search radar that forms a multi-receive beam in a vertical plane and searches for a target, each pencil beam constituting the multi-receive beam has substantially the same beam width and has a predetermined search coverage. Are arranged to cover.

  In the search radar device, the multi-reception beam at the time of the target search is required to search over a wide range without any leakage for the purpose of the search, so each adjacent pencil beam forming the multi-reception beam is in the short range. In, it is inevitable that there will be many overlapping areas.

  That is, as shown in FIG. 10A, the multi-reception beam at the time of the target search does not overlap the adjacent pencil beams so much in the long-distance search region. The detection is performed by a unit of pencil beams or a number of pencil beams close thereto, and is detected without a plurality of data processing.

  Further, in the region where the pencil beams adjacent to each other overlap each other, a useless reception beam is formed, and improvement has been demanded from the viewpoint of effective use of resources.

  On the other hand, as shown in FIG. 10B, for example, the target B existing at a short distance is received by being overlapped by a plurality of adjacent pencil beams.

  That is, the detection target is detected through a plurality of data processing, and it is not only difficult to accurately identify whether the detected target is a single target or a plurality of targets, but in some cases it has a spread angle. It was judged as if it were a clutter, and the deterioration of detection characteristics as a radar could not be denied.

  The present invention has been made in view of the above, and, as an object, a search radar apparatus that can eliminate unnecessary beam formation during search and can easily detect a target with few steps through a plurality of data processing. Is to provide.

  The search radar apparatus according to the present invention includes a transmission unit that generates a radar transmission signal, an antenna unit that is connected to the transmission unit and includes a plurality of antenna elements arranged in an array, and is transmitted from the antenna unit toward the space. Receiving means for receiving a reflected signal from the target of the radar transmission signal for each antenna element and deriving a plurality of corresponding digital element signals; and a plurality of corresponding digital element signals derived from the receiving means On the other hand, beam forming means for forming a multi-reception beam composed of a plurality of reception beams, and a target is detected from the output of the multi-reception beam formed by the beam forming means, and a distance from the own apparatus to the target is output. Outputs a beam number effective for forming a multi-reception beam according to the target detection means and the distance from the target detection means to the detected target. A beam correspondence table that, and summarized in that a control means for controlling the beam forming means so as to turn on the receive beams corresponding to the beam number output from the beam corresponding table.

  As described above, the search radar apparatus of the present invention forms a multi-reception beam having a different number of beams or beam intervals corresponding to the distance from the own apparatus, and performs multi-reception when searching for a coverage area at a long distance. In addition to preventing detection area leakage by increasing the number of beams, it is possible to reduce the number of multiple reception beams and avoid overlap between adjacent beams when searching for a coverage area at a short distance. .

  Therefore, since the number of beams or the beam interval can be changed according to the search distance at the time of target search, there is less leakage of the search space and there is less overlap between adjacent pencil beams. A search radar apparatus capable of searching can be provided.

  As described above, the search radar device of the present invention, when searching for a space and performing target detection, increases the number of multiple reception beams when searching for a coverage area at a long distance, and prevents detection omission. When searching for a coverage area at a short distance, it is possible to reduce the number of multi-received beams and avoid overlapping of the beams, so that the discriminating power of target detection can be improved and unnecessary beam formation can be performed. By doing so, an efficient search is possible.

  Hereinafter, an embodiment of a search radar according to the present invention will be described in detail with reference to FIGS.

  FIG. 1 shows a configuration of a search radar apparatus 1 according to an embodiment of the present invention. The search radar apparatus 1 includes a transmission / reception circuit 3, a beam forming circuit 21, a detection circuit 31, a correlation circuit 41, and the like. , A beam correspondence table 51, a tracking circuit 61, a target position accumulation circuit 63, and a display 71. 2 and 3 are diagrams showing a detailed configuration of the search radar apparatus 1. FIG.

As shown in FIG. 2, the transmission / reception circuit 3 includes a transmission circuit 5, a circulator 7, an array antenna unit 9 having m antenna elements 9-1 to 9-m, and each antenna element 9- of the array antenna unit 9. 1 to 9-m corresponding to the receiving circuits 11-1 to 11-m connected via the circulator 7, and analog / digital (A /) provided corresponding to the receiving circuits 11-1 to 11-m. D) It is composed of conversion circuits 13-1 to 13-m.

  The transmission circuit 5 generates a transmission R / F (Radio Frequency) signal at a predetermined transmission repetition period, and supplies it to the array antenna unit 9 via the circulator 7. Further, the transmission circuit 5 supplies a transmission timing signal of the transmission R / F signal to the variable beam forming circuits 21-1 to 21-n and the target detection circuit 31.

  The array antenna unit 9 having m antenna elements 9-1 to 9-m radiates a transmission R / F signal supplied via the circulator 7 to the space, receives a reflected echo from the space, and 7 to the receiving circuits 11-1 to 11-m.

  The reception circuits 11-1 to 11-m perform low-noise amplification and frequency conversion on the signals from the antenna elements 9-1 to 9-m obtained through the circulator 7, respectively, and then detect the received signals. Extract and obtain received data.

  Receiving data from the receiving circuits 11-1 to 11-m are converted into digital signals by the A / D converting circuits 13-1 to 13-m and supplied to the beam forming circuit 21.

  As shown in FIG. 2, the beam forming circuit 21 includes n beam forming circuits 23-1 to 23-n and a control circuit 62, and the n beam forming circuits 23-1 to 23-n include The n pencil beams are configured to form a multi-reception beam in which the pencil beams are sequentially arranged adjacent to each other.

  The control circuit 25 inputs the beam number from the correlation circuit 41 and selectively controls the ON / OFF switching of the operation of the beam forming circuit corresponding to the beam number designated by the correlation circuit 41. The n beam forming circuits 23-1 to 23-n are controlled by the control circuit 25 to form a multi-reception beam composed of a maximum of n pencil beams, and an OFF signal among the n pencil beams. Is stopped so that the formation of a multi-reception beam composed only of a pencil beam to which an ON signal is given can be switched and output.

  Therefore, the beam forming circuit 21 can switch and form multiple reception beams with different numbers of pencil beams or different intervals between the pencil beams in accordance with the distance from the apparatus according to the control output signal from the control circuit 25. .

  Therefore, the n beam forming circuits 21-1 to 21-n that have received the control output signal from the control circuit 25 perform beam forming calculations using the supplied m series of digital reception data. In the beam forming calculation, each of the beam forming circuits 23-1 to 23-n generates a reception signal for each beam, and also performs unnecessary wave suppression processing such as SLC processing and clutter removal processing. It is configured.

  The effective beam output among the n beam outputs 1 to n switched by the control output signal from the control circuit 25 is supplied to and stored in the corresponding beam storage circuits 33-1 to 33-n.

  As shown in FIG. 3, the detection circuit 31 includes beam storage circuits 33-1 to 33-n, a target detection circuit 35, a determination circuit 37, and an angle measurement processing circuit 39.

  The beam storage circuits 33-1 to 33-n store the supplied beam outputs 1 to n as data, and store the beam outputs 1 to n stored for the target detection circuit 35 and the angle measurement processing circuit 39. Supply.

  The target detection circuit 35 executes target detection processing based on the beam outputs 1 to n supplied from the beam storage circuits 33-1 to 33-n based on the transmission timing signal from the transmission circuit 5, and detects the target. The beam number and the distance data to the target are supplied to the determination circuit 37.

  Based on the beam number and distance data from the target detection circuit 35, the determination circuit 37 determines an angle measurement method capable of obtaining angle measurement data with the highest accuracy for the target, and sends it to the angle measurement processing circuit 39. At the same time, the beam number corresponding to the determined angle measurement method is selected from the n beams and notified to the angle measurement processing circuit 39. The angle measurement method includes, for example, a monopulse angle measurement method and an amplitude comparison angle measurement method.

  The angle measurement processing circuit 39 reads out the angle measurement method notified from the determination circuit 37 and the beam of the beam number to be measured by the angle measurement method from the beam storage circuits 33-1 to 33-n, and executes angle measurement processing. Then, angle data such as azimuth data, altitude data, and distance data is output. The angle measurement processing circuit 39 can employ a known circuit, and includes a switch for switching and selecting a beam and an angle measurement arithmetic circuit.

  The correlation circuit 41 extracts the highly correlated beam number stored in the beam correspondence table 51 based on the distance data from the angle measurement data from the angle measurement processing circuit 39, and is provided in the beam forming circuit 21. Output to the circuit 25. At the same time, the correlation circuit 41 combines the angle measurement data from the angle measurement processing circuit 39 into one detection information and outputs it to the tracking circuit 61.

  As shown in FIG. 4, the beam correspondence table 51 divides distance data into a long distance and a short distance, and stores beam numbers corresponding to the distance data. When the distance data D is 50 km or more as the reference distance data Dref, for example, it means a long distance, and beam numbers # 11, # 12, # 13, # 14, # 15, # 16, # 17, # 18, # 19, # 20, and # 21 are extracted and output to the correlation circuit 41. On the other hand, when the distance data D is less than 50 km as the reference distance data Dref, for example, it means a short distance, and the beam numbers # 11, # 13, # 15, # 17, # 19, # 21 are extracted and correlated. Output to the circuit 41. As a result, when the target is a long distance, all beam numbers # 11 to # 21 are output to the control circuit 25. On the other hand, when the target is a short distance, an even number among # 11 to # 21 is output. Only the odd-numbered beam numbers are thinned out and output to the control circuit 25.

  In the configuration of the beam correspondence table 51, at least two or more reference distance data Dref described above may be provided to store beam numbers corresponding to a long distance, a middle distance, and a short distance.

  Here, the operation of the correlation circuit 41 of the search radar apparatus 1 will be described in detail with reference to FIGS.

  Even a point target such as an aircraft generally spreads in a distance direction, an azimuth direction, and an elevation (altitude) direction, and a plurality of detections are performed. In the schematic diagram shown in FIG. 5, the reception level is indicated by the size of a black circle ●. Generally, the reception level tends to increase when the target aircraft is close to the true position. FIG. 5 is a schematic diagram for explanation, and the number of detections is exaggerated.

  For the azimuth data output from the angle measurement processing circuit 39, and angle measurement data such as altitude data and distance data, the correlation circuit 41 provides detection information of the target aircraft having a certain extent as shown in FIG. As shown in FIG. 6, it is regarded as a target of one aircraft and is collected into one detection information.

  As shown in FIG. 5, when a plurality of detections are detected from the angle measurement processing circuit 39 for one target, these pieces of information are output as they are to the display unit 71 (scope) or the senior organization of the search radar device 1. Then, although there is actually one aircraft, it is mistaken that there are a plurality of aircraft. Therefore, as described above, a single target is expected to be detected separately, and correlation processing is performed to combine detection information having a certain extent in space into one.

  In the multi-reception beam search radar apparatus 1, the detection information output from the angle measurement circuit 39 tends to increase as the target is larger, and the detection information tends to increase as the target is closer.

In addition, as the distance from the search radar device 1 increases, the beam overlap becomes smaller and sparser. On the other hand, as the distance from the search radar device 1 becomes shorter, the beam overlap becomes larger and denser.

Due to the nature of the search radar device 1 as described above, it is practically difficult to determine a uniform correlation parameter with respect to the target size (large / small) and the target distance (far / short). Therefore, the correlation circuit 41 eliminates the need for complicated parameter adjustment that depends on the beam density (the size of the overlap) only by selecting the beam.

  Here, the correlation parameter in the elevation direction will be mainly described.

  For example, even if "elevation angle width = 1 degree correlation gate", the number of beams included in the elevation angle width differs in terms of power between a long distance and a short distance. As shown in FIG. 7D, the beam line is, for example, a line having a detection probability of 50%, and is represented by the number of beams with an arrow at that time.

  Since the number of beams involved depends on the distance, the number of detections is naturally different. For this reason, it is impossible to apply these correlation parameters uniformly anywhere in the coverage area, even though the number of detections varies depending on the location.

  Therefore, in the present invention, in order to avoid the sparse / dense state of the received beam, the received beam to be used is thinned according to the distance from the search radar apparatus 1, and information corresponding to the thinned beam number is not used in the correlation processing. By doing so, a uniform correlation parameter can be used.

  Returning to FIG. 3, the tracking circuit 61 performs tracking processing on the detection information (target) output from the correlation circuit 41, and similarly stores information related to the target position in the target position storage circuit 63 as tracking information. The target position accumulation circuit 63 accumulates tracking information including the target position based on the tracking result by the tracking circuit 41. The display unit 71 displays target information output from the tracking circuit 41.

  The tracking circuit 61 periodically updates the position of the target specified by the detection information output from the correlation circuit 41 by the capture tracking process, so that the target to be noticed is relatively displaced with respect to the search radar device 1. The target and its surrounding area are always displayed.

  The operation of the search radar apparatus 1 according to this embodiment described above will be described with reference to FIGS.

  7A is a timing chart showing transmission and reception timings of the search radar apparatus 1, FIG. 7B is a diagram showing an elevation angle coverage of the search radar apparatus 1, and FIG. 7C is a cosecant beam formed at the time of transmission. (D) is the conceptual diagram which showed the multi-reception beam formed at the time of reception.

First, the transmission circuit 5 generates a transmission R / F signal at a predetermined transmission repetition period and supplies it to the array antenna unit 9 via the circulator 7. As shown in FIG. 7, the transmission R / F signal formed by the transmission circuit 5 is supplied to the array antenna unit 9 at the timing of the transmission pulse synchronized with the transmission repetition period. The array antenna unit 9 radiates transmission R / F signals to the space from the m antenna elements 9-1 to 9-m. The shape of the transmission beam at this time is a cosecant beam that can cover the spatial region in a wide range with a vertical plane, as shown in FIG. At the same time, the transmission circuit 5 supplies the transmission timing signal of the transmission R / F signal to the variable beam forming circuits 21-1 to 21-n and the target detection circuit 31. In the reception period shown in FIG. Reflected echoes from the space are received via the antenna elements 9-1 to 9-m and supplied to the receiving circuits 11-1 to 11-m via the circulator 7. In the receiving circuits 11-1 to 11-m, the signals from the antenna elements 9-1 to 9-m obtained through the circulator 7 are subjected to low noise amplification and frequency conversion, and then detected to detect the received signals. Extracted and output to the A / D conversion circuits 13-1 to 13-m. Receiving signals from the receiving circuits 11-1 to 11-m are converted into digital signals by the A / D conversion circuits 13-1 to 13-m and supplied to the beam forming circuit 21.

  Note that the control circuit 62 is reset when power is first applied to the search radar device 1. In the first transmission pulse operation, the beam number to be selected is not output from the correlation circuit 41. In this case, the control circuit 62 designates all the beam numbers # 1 to #n. And ON signals are output to the beam forming circuits 23-1 to 23-n corresponding to the designated beam numbers.

  Next, the beam forming circuits 21-1 to 21-n perform beam forming calculations using the supplied m systems of digital reception data, and generate reception signals for each beam unit. As a result, the beam forming circuits 23-1 to 23-n controlled by the control circuit 25 form a multi-reception beam adjacent to the pencil beam as shown in FIG.

  Next, the n beam outputs 1 to n switched by the control output signal from the control circuit 25 are supplied to and stored in the corresponding beam storage circuits 33-1 to 33-n.

  Next, the target detection circuit 35 executes target detection processing based on the beam outputs 1 to n supplied from the beam storage circuits 33-1 to 33-n based on the transmission timing signal from the transmission circuit 5, Is supplied to the determination circuit 37.

  Next, the determination circuit 37 determines an angle measurement method capable of obtaining angle measurement data with the highest accuracy for the target based on the beam number and distance data from the target detection circuit 35, and an angle measurement processing circuit. 39, and the beam number corresponding to the determined angle measurement method is selected from the n beams and notified to the angle measurement processing circuit 39.

  Next, the angle measurement processing circuit 39 reads the angle measurement method notified from the determination circuit 37 and the beam of the beam number to be measured by the angle measurement method from the beam storage circuits 33-1 to 33-n, and performs angle measurement processing. To output angle measurement data such as azimuth data, altitude data, and distance data to the correlation circuit 41.

  Next, the correlation circuit 41 extracts a beam number having a high correlation stored in the beam correspondence table 51 based on the distance data from the angle measurement data from the angle measurement processing circuit 39, and is provided in the beam forming circuit 21. Output to the control circuit 25. At the same time, the correlation circuit 41 combines the angle measurement data from the angle measurement processing circuit 39 into one detection information and outputs it to the tracking circuit 61.

  Next, the tracking circuit 61 performs a tracking process on the detection information (target) output from the correlation circuit 41 and accumulates information related to the target position in the target position storage circuit 63 as tracking information. The target position accumulation circuit 63 accumulates tracking information including the target position based on the tracking result by the tracking circuit 41. The display unit 71 displays target information output from the tracking circuit 41.

  In the tracking circuit 61, the target position designated by the detection information output from the correlation circuit 41 is periodically updated by the capture tracking process, so that the target to be noticed is displaced relative to the search radar apparatus 1. However, the target and its peripheral range can always be displayed on the display 71.

  Here, the correlation circuit 41 extracts a highly correlated beam number stored in the beam correspondence table 51 based on the distance data among the angle measurement data from the angle measurement processing circuit 39. As shown in FIG. 4, in the beam correspondence table 51, distance data is divided into a long distance and a short distance, and beam numbers corresponding to the distance data are stored. Therefore, when the distance data D is, for example, 50 km or more, This means a long distance, and beam numbers # 11, # 12, # 13, # 14, # 15, # 16, # 17, # 18, # 19, # 20, # 21 are extracted to the correlation circuit 41. Output. Further, the correlation circuit 41 outputs these beam numbers to the control circuit 25 provided in the beam forming circuit 21. Next, in the control circuit 25, these beam numbers from the correlation circuit 41 are input, and these beam numbers # 11, # 12, # 13, # 14, # 15, # 16, # specified by the correlation circuit 41 are input. ON control signals are output to the beam forming circuits 23-1 to 23-n corresponding to 17, # 18, # 19, # 20, and # 21.

  As a result, in the reception period, as shown in FIG. 8, the multi-reception beams adjacent to the pencil beam are formed by the beam forming circuits 23-1 to 23-n controlled by the control circuit 25.

  That is, when an attempt is made to search for a long-range coverage area that also reaches the maximum detection distance L in the search radar device 1, all of the switching control signals from the control circuit 25 are output as ON signals. The beam forming circuits 23-1 to 23-n are activated. As a result, as shown in FIG. 8, the output of n (11 in the figure) beam forming circuits 23-1 to 23-n having a large number does not leak to a long-distance search area. Search and target detection is performed.

  On the other hand, when the distance data D is less than 50 km, for example, it means a short distance, and beam numbers # 11, # 13, # 15, # 17, # 19, # 21 are extracted from the beam correspondence table 51. Output to the correlation circuit 41. As a result, when the target is a short distance, even numbers among # 11 to # 21 are thinned out, and only odd number beam numbers are output to the control circuit 25. Next, the control circuit 25 inputs these beam numbers from the correlation circuit 41 and corresponds to these beam numbers # 11, # 13, # 15, # 17, # 19, and # 21 designated by the correlation circuit 41. ON control signals are output to the beam forming circuits 23-1 to 23-n.

  As a result, only the odd-numbered (six in the figure) beam forming circuits 23-1, 23-3,... Shown in FIG. 9 are selected, and as shown in FIG. A thinned multi-reception beam is formed, and there is little overlap between adjacent beams, the elevation angle resolution is good, and the target detection is performed by an efficient search without waste.

  Note that, in the search at a short distance, even if the number of beams is decreased, the reflected reception power from the target is large, so the target detection rate does not decrease.

  In addition, when scanning a long-distance search range, when the beam interval is narrowed, the search range (elevation angle range) as a radar is narrowed, but on the contrary, the leakage area is reduced and the antenna gain at the time of beam formation is As it increases, the detection rate for small targets increases.

  As described above, in the present embodiment, the configuration is such that the number of beams or the beam interval can be switched in accordance with the distance in the search area regardless of whether the target exists in the search area. It is possible to provide a search radar apparatus that can perform an efficient search with less leakage and less overlap between adjacent pencil beams.

It is the block diagram which showed one Embodiment of the search radar apparatus by this invention. FIG. 2 is a diagram (part 1) illustrating a detailed configuration of the search radar apparatus illustrated in FIG. 1; FIG. 3 is a second diagram illustrating a detailed configuration of the search radar apparatus illustrated in FIG. 1. It is a block diagram of the beam corresponding | compatible table 51 used for this invention. It is a schematic diagram which shows the big reception level of a target aircraft. It is the figure which considered that the detection information of the target aircraft was considered as one target, and was collected into one. (A) is a timing chart showing transmission and reception timings of the search radar device 1, (b) is a diagram showing an elevation angle coverage of the search radar device 1, and (c) is a cosecant beam formed at the time of transmission. (D) is a conceptual diagram showing a multi-reception beam formed during reception. FIG. 4 is a pattern diagram of a multi-reception beam formed for searching a long-range area range. FIG. 6 is a pattern diagram of a multi-reception beam formed for searching a short range region. It is the pattern figure (a) and (b) of the multi reception beam shown in order to demonstrate operation | movement of the conventional search radar apparatus.

Explanation of symbols

3 Transmitting Circuit 7 Circulator 9 Array Antenna Units 11-1 to 11-m Receiving Circuits 13-1 to 13-m Analog / Digital (A / D) Conversion Circuit 21 Beam Forming Circuits 23-1 to 23-n Beam Forming Circuit 25 Control circuit 31 Detection circuit 33-1 to 33-n Beam storage circuit 35 Target detection circuit 37 Determination circuit 39 Measurement processing circuit 41 Correlation circuit 51 Beam correspondence table 61 Tracking circuit 71 Indicator

Claims (3)

A transmission means for generating a radar transmission signal;
An antenna unit connected to the transmission means and having a plurality of antenna elements arranged in an array; and
Receiving means for receiving a reflected signal from a target of the radar transmission signal transmitted from the antenna unit toward the space for each antenna element, and deriving a plurality of corresponding digital element signals;
Beam forming means for forming, for each of the plurality of corresponding digital element signals derived from the receiving means, a multi-receive beam comprising a plurality of receive beams;
Target detection means for detecting a target from the output of the multi-reception beam formed by the beam forming means and outputting a distance from the own apparatus to the target;
A beam correspondence table for outputting a beam number effective for forming a multi-reception beam according to the distance from the target detection means to the detected target;
A search radar apparatus comprising: control means for controlling beam forming means to turn on a reception beam corresponding to a beam number output from the beam correspondence table. The beam forming means includes
When searching for a closer area using the preset distance from the device as a reference value, the number of the beams is reduced or the beam interval is increased compared to searching for a farther area. The search radar apparatus according to claim 1. The beam correspondence table is:
The beam number is stored so as to reduce the number of the beams when searching for a closer region, when searching for a closer region, using the preset distance from the device as a reference value. The search radar device according to claim 1.

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