Direction detection device, method for acquiring intensity difference table, direction detection method, and direction detection program

Abstract

To appropriately find the directions of arrival of receiving waves while removing ambiguity even if there is a restriction on installation of antennas in a radome.SOLUTION: A direction finding device comprises: a plurality of antennas; an intensity difference application unit that applies, to reception intensities of receiving waves received by the plurality of antennas, different intensity differences according to the directions of arrival of the receiving waves; a storage unit that stores, for every combination of two antennas, an intensity difference table in which the intensity difference between the two antennas and the directions of arrival of the receiving waves are associated with each other; a detector that detects the intensity difference and phase difference between the two antennas based on the received receiving waves; an extractor that extracts, from the intensity difference table, the directions of arrival of the receiving waves corresponding to the intensity difference; a derivation unit that derives the directions of arrival of the receiving waves corresponding to the phase difference; and a comparator that compares the directions of arrival of the receiving waves corresponding to the intensity difference and the directions of arrival of the receiving waves corresponding to the phase difference with each other to acquire the directions of arrival of the receiving waves matching each other as a finding result.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to a direction detection device for detecting the arrival direction of a received wave, a method for acquiring an intensity difference table, a direction detection method, and a direction detection program.

Background Art

[0002] Conventionally, as a direction detection device, an angle measurement processing device for calculating the arrival direction of a signal such as a received wave is known (see, for example, Patent Document 1). The angle measurement processing device includes a plurality of antenna elements and a radome covering the plurality of antenna elements. The angle measurement processing device calculates the arrival direction of the arrival signal based on the arrival signals received by the plurality of antenna elements.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When detecting the arrival direction of a received wave using the phase difference between a plurality of antennas, ambiguity may occur. Ambiguity means that, depending on the relationship between the distance between the antennas and the wavelength of the received wave, even if the phase differences obtained between the antennas are the same, a plurality of candidates for the arrival direction of the received wave are calculated. The ambiguity that occurs varies depending on the distance between the antennas. Therefore, in order to resolve the ambiguity, it is common to use a plurality of antennas with unequal distances between the antennas.

[0005] Also, when a plurality of antennas are arranged in one direction (for example, the azimuth direction (also referred to as the AZ direction)), the plurality of antennas can detect the arrival direction of the received wave in a plane (two-dimensional) including the one direction. Therefore, in order to detect the arrival direction of the three-dimensional received wave, it is necessary to arrange the antennas in one direction and also arrange them in another direction intersecting the one direction (for example, the elevation angle direction (also referred to as the EL direction)), that is, to arrange them two-dimensionally.

[0006] However, antennas installed in the internal space of a radome may be difficult to arrange two-dimensionally due to the spatial constraints of the radome. Due to the spatial constraints of the radome, when a plurality of antennas are arranged only in the one-dimensional direction, the arrival direction of the received wave in the plane including the one direction can be calculated from the phase difference between the plurality of antennas. However, for the other direction intersecting the one direction, since there are no plurality of antennas, there is a problem that calculation using the phase difference cannot be performed.

[0007] Therefore, an object of the present disclosure is to provide a direction detection device, a method for acquiring an intensity difference table, a direction detection method, and a direction detection program that can suitably detect the arrival direction of a received wave while removing ambiguity even when there are restrictions on the installation of antennas in a radome.

Means for Solving the Problems

[0008] The direction detection device of the present disclosure is a direction detection device that detects the arrival direction of a received wave. The direction detection device includes: a plurality of antennas that receive the received wave; an intensity difference imparting unit that imparts an intensity difference that varies depending on the arrival direction of the received wave to the reception intensity of the received wave received by the plurality of antennas; a storage unit that stores, for each combination of two of the plurality of antennas, an intensity difference table that associates the intensity difference between the two antennas with the arrival direction of the received wave; a detector that detects, based on the received wave received by the plurality of antennas, the intensity difference between two of the antennas and the phase difference between the two antennas; an extractor that extracts, from the intensity difference table stored in the storage unit, the arrival direction of the received wave corresponding to the intensity difference detected by the detector, according to the combination of the two antennas; a derivation unit that derives the arrival direction of the received wave corresponding to the phase difference detected by the detector; and a comparator that compares the arrival direction of the received wave corresponding to the intensity difference obtained from the extractor with the arrival direction of the received wave corresponding to the phase difference obtained from the derivation unit, and obtains, as a detection result, the matching arrival direction of the received wave.

[0009] The method for obtaining the intensity difference table of the present disclosure is a method for obtaining an intensity difference table used in the above direction detection device. The method includes: setting, for a plurality of antennas, the received wave generated from a radio wave source to have a predetermined arrival direction; generating the received wave from the radio wave source; receiving the received wave by the plurality of antennas; and obtaining an intensity difference table that associates the intensity difference between two of the antennas with the arrival direction of the received wave, based on the intensity difference obtained by receiving the received wave.

[0010] The direction detection method of the present disclosure is a direction detection method for detecting the arrival direction of a received wave by the above-described direction detection device, including steps of: receiving the received wave by a plurality of antennas; detecting, by the detector, an intensity difference and a phase difference between two of the antennas based on the received wave received by the plurality of antennas; extracting, by the extractor, from the intensity difference table stored in the storage unit, the arrival direction of the received wave corresponding to the intensity difference detected by the detector according to a combination of two of the antennas; deriving the arrival direction of the received wave corresponding to the phase difference detected by the detector; and comparing, by the comparator, the arrival direction of the received wave corresponding to the intensity difference obtained from the extractor with the arrival direction of the received wave corresponding to the phase difference obtained from the derivation unit, and obtaining, as a detection result, the arrival direction of the received wave that matches.

[0011] The direction detection program of the present disclosure is a direction detection program for detecting the arrival direction of a received wave, which is executed by the above-described direction detection device, including steps of: receiving the received wave by a plurality of antennas; detecting, by the detector, an intensity difference and a phase difference between two of the antennas based on the received wave received by the plurality of antennas; extracting, by the extractor, from the intensity difference table stored in the storage unit, the arrival direction of the received wave corresponding to the intensity difference detected by the detector according to a combination of two of the antennas; deriving the arrival direction of the received wave corresponding to the phase difference detected by the detector; and comparing, by the comparator, the arrival direction of the received wave corresponding to the intensity difference obtained from the extractor with the arrival direction of the received wave corresponding to the phase difference obtained from the derivation unit, and causing to execute the step of obtaining, as a detection result, the arrival direction of the received wave that matches.

Advantages of the Invention

[0012] According to the present disclosure, even if there are restrictions on the installation of the antenna within the radome, it is possible to suitably detect the direction of arrival of received waves in dimensions that could not be obtained conventionally while removing ambiguity.

Brief Description of the Drawings

[0013]

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DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments according to the present disclosure will be described in detail with reference to the drawings. Note that the present invention is not limited by this embodiment. In addition, the constituent elements in the following embodiments include those that can be replaced by those skilled in the art and are easy to replace, or those that are substantially the same. Furthermore, the constituent elements described below can be combined as appropriate, and when there are a plurality of embodiments, the respective embodiments can also be combined.

[0015] [Embodiment 1] The direction detection device 1 and the direction detection method according to Embodiment 1 are a device and a method for detecting the arrival direction of a received wave. The received wave is a radio wave, for example, a beam of a detection radar. The direction detection device 1 is provided, for example, in a transportation machine such as an aircraft, a vehicle, or a ship. The arrival direction of the received wave is determined by the angle (AZ angle) in the azimuth direction (hereinafter referred to as the AZ (Azimuth) direction) and the angle (EL angle) in the elevation direction (hereinafter referred to as the EL (Elevation) direction).

[0016] FIG. 1 is a schematic configuration diagram showing a part of the direction detection device according to Embodiment 1. FIG. 2 is a cross-sectional view taken along line A-A of FIG. 1. FIG. 3 is a cross-sectional view taken along line B-B of FIG. 1. FIG. 4 is an explanatory diagram regarding the direction detection device and the direction detection method according to Embodiment 1. FIG. 5 is a diagram of the intensity difference table. FIG. 6 is a graph showing an example of the arrival direction based on the phase difference. FIG. 7 is a graph showing an example of extraction from the intensity difference table. FIG. 8 is a graph when candidates for the arrival direction of the received wave are superimposed.

[0017] (Direction Detection Device) As shown in FIGS. 1 to 3, the direction detection device 1 includes a plurality of antennas 5 and a radome 6. The plurality of antennas 5 are arranged in a straight line along the AZ direction (x direction in FIG. 1), and one antenna is provided in the EL direction (z direction in FIGS. 1 to 3), resulting in a one-dimensional arrangement. In Embodiment 1, although a one-dimensional arrangement is adopted to suppress the height in the EL direction, the arrangement is not particularly limited. The plurality of antennas 5 only need to be two or more. In Embodiment 1, two antennas 5 are used for explanation. The plurality of antennas 5 are arranged at a predetermined interval in the AZ direction.

[0018] The radome 6 is provided, for example, on the wing of an aircraft. The radome 6 functions as an intensity difference imparting unit that imparts different intensity differences to the intensity difference of the signal intensity between the antennas 5 depending on the arrival direction of the received wave. Note that the wing length direction of the aircraft wing is the AZ direction. Specifically, the radome 6 has a non-uniform shape in a three-dimensional space including the AZ direction and the EL direction. As shown in FIG. 2, the cross-sectional shape of the radome 6 cut at the position on the wing root side (left side in FIG. 1) in the AZ direction has a wide internal space in the EL direction. On the other hand, as shown in FIG. 3, the cross-sectional shape of the radome 6 cut at the position on the wing tip side (right side in FIG. 1) has a narrow internal space in the EL direction. Also, in the cross-sections shown in FIGS. 2 and 3, the thickness of the radome 6 is not constant and varies depending on the EL direction.

[0019] Note that the radome 6 has a laminated structure, and different intensity differences may be imparted depending on the arrival direction of the received wave by varying the shape, varying the laminated structure, or varying both the shape and the laminated structure.

[0020] Also, as shown in FIG. 4, the direction detection device 1 includes a detector 10, a storage unit 11, a calculation unit 12, an extractor 13, and a comparator 14.

[0021] The detector 10 is connected to two antennas 5 and has a detection unit 10a for detecting a phase difference and a detection unit 10b for detecting an intensity difference. The detection unit 10a detects the phase difference and frequency of the received waves received by the two antennas 5. Also, the detection unit 10a calculates the wavelength from the detected frequency. The detection unit 10b detects the intensity difference, frequency, and polarization of the signal intensities of the received waves received by the two antennas 5. Note that information regarding polarization may be obtained from the intensity ratio of two orthogonal linear antennas or from measurements with a single linear antenna rotated. In this case, a dedicated antenna for detecting polarization may be provided separately. Here, in Embodiment 1, "Antenna 1" and "Antenna 2" are applied as the two antennas 5. That is, in Embodiment 1, the detection unit 10b detects the intensity difference between "Antenna 1" and "Antenna 2" as the intensity difference between the two antennas 5. Note that the detection unit 10b detects the intensity difference, frequency, and polarization, but at least the intensity difference may be detected, and the frequency and polarization may be detected as necessary.

[0022] The storage unit 11 stores the distance d between the two antennas 5 and the intensity difference table T1 shown in FIG. 5. Note that the distance d between the antennas 5 and the intensity difference table T1 may be stored in a separate storage unit 11 or an integrated storage unit 11 as shown in FIG. 4, and is not particularly limited. The distance d between the antennas 5 is the distance between "Antenna 1" and "Antenna 2" and is a fixed value defined at the time of installation.

[0023] The intensity difference table T1 is data that associates the intensity difference between two antennas 5 with the arrival direction of the received wave. In FIG. 5, the horizontal axis is the AZ angle and the vertical axis is the EL angle. Also, the intensity difference table T1 is composed of a plurality of cells associated with the AZ angle and the EL angle. Each cell has an intensity difference associated with it. For this reason, the AZ angle and the EL angle are associated with the cell with the intensity difference associated. Also, the intensity difference table T1 is prepared at least for each frequency or polarization, and an intensity difference table T1 corresponding to the frequency, an intensity difference table T1 corresponding to the polarization, or an intensity difference table T1 corresponding to the frequency and the polarization may be prepared. In Embodiment 1, an intensity difference table T1 of "antenna 1" and "antenna 2" is prepared as the intensity difference table T1. Also, although illustration is omitted, the storage unit 11 stores a program for detecting the arrival direction of the received wave using the direction detection device 1. Note that the intensity difference table T1 includes, in addition to the intensity difference table T1 shown in FIG. 5, those obtained by formulating based on the intensity difference table T1 shown in FIG. 5.

[0024] The calculation unit 12 calculates the arrival direction of the received wave from a predetermined calculation formula based on the phase difference Δθ and wavelength λ of the received wave detected by the detection unit 10a of the detector 10 and the distance d between the antennas 5 acquired from the storage unit 11. Here, the predetermined calculation formula is a generally known phase difference direction finding method, and uses "θ = sin -1 (Δθ·λ / 2πd)", etc.

[0025] The extractor 13 extracts the arrival direction of the received wave corresponding to the intensity difference from the intensity difference table T1 of "antenna 1" and "antenna 2" based on the frequency, polarization, and intensity difference of the received wave detected by the detection unit 10b of the detector 10. Specifically, in Embodiment 1, the extractor 13 acquires an intensity difference table T1 corresponding to the frequency, an intensity difference table T1 corresponding to the polarization, or an intensity difference table T1 corresponding to the frequency and the polarization based on the frequency and polarization of the received wave detected by the detection unit 10b as needed. After that, the extractor 13 extracts the cell of the intensity difference table T1 corresponding to the intensity difference detected by the detection unit 10b.

[0026] The comparator 14 obtains, as a detection result, the arrival direction of the received wave in which the arrival direction calculated in the arithmetic unit 12 matches the plurality of arrival direction candidates extracted by the extractor 13. Here, with reference to FIGS. 6 to 8, the processing by the comparator 14 will be specifically described. FIG. 6 is a diagram of a graph showing the change in the arrival direction at a predetermined phase difference calculated using a predetermined calculation formula. In FIG. 6, the arrival direction at the phase difference Δθ between "antenna 1" and "antenna 2" is shown as an example. On the other hand, FIG. 7 is a diagram when cells having the same intensity difference are extracted from the intensity difference table T1 as shown in FIG. 5. In FIG. 7, it is a diagram when cells of the intensity difference ΔE between "antenna 1" and "antenna 2" are extracted.

[0027] As shown in FIG. 6, the comparator 14 obtains the arrival direction based on the phase difference Δθ between "antenna 1" and "antenna 2" acquired by the arithmetic unit 12. Also, as shown in FIG. 7, the comparator 14 obtains cells that are candidates for the arrival direction based on the intensity difference ΔE between "antenna 1" and "antenna 2". Then, as shown in FIG. 8, the comparator 14 overlaps the arrival direction based on the phase difference Δθ between "antenna 1" and "antenna 2" and the cells corresponding to the arrival direction based on the intensity difference ΔE between "antenna 1" and "antenna 2", and obtains the matching cells. Then, the comparator 14 obtains the AZ angle and the EL angle corresponding to the obtained cells as the detection result. That is, the azimuth indicated by the combination of the AZ angle and the EL angle shown by the matching cells causes a phase difference Δθ between "antenna 1" and "antenna 2" and also causes an intensity difference ΔE between "antenna 1" and "antenna 2". Since it matches the observation result, it can be inferred that it is the arrival direction of the received wave.

[0028] (Intensity Difference Table Acquisition Method) Next, with reference to FIG. 9, a method for acquiring the intensity difference table T1 used in the direction detection device 1 will be described. For the acquisition of the intensity difference table T1, the acquisition device 21 shown in FIG. 9 is used. The acquisition device 21 includes a transmitter 22, a receiver 23, an operation unit 24, and a measuring device 25.

[0029] The transmitter 22 transmits radio waves with a predetermined polarization toward the receiver 23. The receiver 23 is configured to simulate the plurality of antennas 5 and radomes 6 of the direction detection device 1, and acquires the received radio waves as received waves. The operation unit 24 moves the receiver 23 so that the position of the transmitter 22 as viewed from the receiver 23 becomes a predetermined AZ angle and EL angle. The measuring device 25 sets the transmission frequency of the transmitter 22, acquires the intensity difference of the received waves received by the receiver 23, and acquires the AZ angle and EL angle at the time of acquisition.

[0030] In the method for acquiring the intensity difference table T1, the operation unit 24 is operated so that the receiver 23 including the two antennas 5 has an arrival direction that becomes a predetermined AZ angle and EL angle. After that, in the acquisition method, a step of generating radio waves with a predetermined frequency from the transmitter 22 serving as a radio wave source is executed. Then, in the acquisition method, a step of receiving the radio waves with a predetermined frequency as received waves by the receiver 23 is executed. In the acquisition method, when the receiver 23 receives the received waves, the measuring device 25 measures the intensity difference of the received waves received. Then, in the acquisition method, a step of associating the measured intensity difference between the two antennas 5 with the AZ angle and EL angle at the time of acquisition, and acquiring the intensity difference table T1 for each frequency and polarization of the received waves is executed. Note that in the above method for acquiring the intensity difference table T1, the intensity difference table T1 is acquired for each frequency and polarization of the received waves, but the intensity difference table T1 may be acquired only for each frequency or only for each polarization.

[0031] Note that for the plurality of intensity difference tables T1 prepared for each frequency or polarization of the received waves, an interpolation process may be executed in which the intensity difference between frequencies or polarizations is interpolated. Further, each cell in the intensity difference table T1 is associated with an arrival direction composed of an AZ angle and an EL angle, but an interpolation process may be executed in which the AZ angle and EL angle between cells are interpolated.

[0032] (Direction Detection Method) Next, with reference to FIG. 4, a direction detection method for detecting the arrival direction of a received wave by the direction detection device 1 will be described.

[0033] In the direction detection method, first, step S1 of receiving a received wave by two antennas 5 is executed. After this, in the direction detection method, in the detector 10, step S2 of detecting the phase difference and intensity difference between the two antennas 5 based on the received waves received by the two antennas 5 is executed. In step S2, in the detection unit 10a, the phase difference and frequency between the two antennas 5 are detected, and in the detection unit 10b, the intensity difference between the two antennas 5 and, if necessary, the frequency or polarization are detected. Subsequently, in the direction detection method, based on the detected phase difference and wavelength and the distance d between the antennas 5 acquired from the storage unit 11, step S3 of calculating the arrival direction of the received wave corresponding to the phase difference from a predetermined calculation formula is executed. Next, in the direction detection method, in the extractor 13, step S4 of acquiring the intensity difference table T1 corresponding to the frequency or polarization from the storage unit 11 based on the detected frequency or polarization is executed. Then, in the direction detection method, in the extractor 13, step S5 of extracting the arrival direction of the received wave corresponding to the intensity difference detected by the detector 10, that is, the cell corresponding to the AZ angle and EL angle, from the acquired intensity difference table T1 is executed. In the direction detection method, after the execution of step S5, in the comparator 14, step S6 of comparing the arrival direction of the received wave corresponding to the phase difference calculated in step S3 with the acquired cells of the AZ angle and EL angle and acquiring the AZ angle and EL angle of the matching cell as the detection result is executed. Note that in the direction detection method of Embodiment 1, a cell is acquired from the corresponding intensity difference table T1 based on the frequency or polarization, but a cell may also be acquired from the corresponding intensity difference table T1 based on the frequency and polarization.

[0034] [Embodiment 2] Next, referring to FIGS. 10 and 11, Embodiment 2 will be described. In Embodiment 2, in order to avoid duplicate descriptions, differences from Embodiment 1 will be described, and parts having the same configuration as in Embodiment 1 will be described with the same reference numerals. FIGS. 10 and 11 are explanatory diagrams of an example related to the direction detection device and the direction detection method according to Embodiment 2.

[0035] In the direction detection method of Embodiment 1, in the extractor 13, the cells corresponding to the intensity difference detected by the detection unit 10b of the detector 10 were extracted. In this case, in the comparator 14, as shown on the left side of FIG. 10, there may be a plurality of matching cells. Also, in the comparator 14, as shown on the left side of FIG. 11, the number of matching cells may be zero.

[0036] Therefore, in the direction detection method of Embodiment 2, the extractor 13 extracts the arrival direction of the received wave corresponding to the intensity difference width obtained by adding the first adjustment widths (α, β) to the intensity difference ΔE detected by the detector 10. Specifically, when the extractor 13 acquires the intensity difference ΔE from the detector 10, it generates "ΔE - α < ΔE < ΔE + β" as the intensity difference width, and acquires the cells corresponding to the generated intensity difference width. Here, the extractor 13 reduces the number of cells to be acquired by reducing the first adjustment widths (α, β), while increases the number of cells to be acquired by increasing the first adjustment widths (α, β).

[0037] Specifically, as shown on the left side of FIG. 10, as a result of the comparator 14 comparing the arrival direction of the received wave corresponding to the phase difference with the cells corresponding to the intensity difference width between "antenna 1" and "antenna 2", when a plurality of cells are applicable, the extractor 13 narrows the intensity difference width. Thereby, the number of cells corresponding to the intensity difference width between "antenna 1" and "antenna 2" decreases. Then, the comparator 14 compares again the arrival direction of the received wave corresponding to the phase difference with the cells corresponding to the intensity difference width between "antenna 1" and "antenna 2", so that, as shown on the right side of FIG. 10, the matching cells can be found.

[0038] Also, as shown on the left side of FIG. 11, when the comparator 14 compares the arrival direction of the received wave corresponding to the phase difference with the cell corresponding to the intensity difference width between "antenna 1" and "antenna 2" and there is no matching cell, that is, when the cells do not match, the extractor 13 widens the intensity difference width. As a result, the number of cells corresponding to the intensity difference width between "antenna 1" and "antenna 2" increases. Then, the comparator 14 compares again the arrival direction of the received wave corresponding to the phase difference with the cell corresponding to the intensity difference width between "antenna 1" and "antenna 2", and as shown on the right side of FIG. 11, a matching cell can be found.

[0039] [Embodiment 3] Next, referring to FIGS. 12 to 15, Embodiment 3 will be described. In Embodiment 3, in order to avoid duplicate descriptions, the parts different from Embodiments 1 and 2 will be described, and the parts having the same configuration as those in Embodiments 1 and 2 will be described with the same reference numerals. FIG. 12 is an explanatory diagram regarding the direction detection device and the direction detection method according to Embodiment 3. FIG. 13 is a graph showing an example of the phase difference table. FIG. 14 is a graph showing an example of the intensity difference table. FIG. 15 is a graph when the arrival directions of the received waves are superimposed.

[0040] In the direction detection methods of Embodiments 1 and 2, the arrival direction of the received wave corresponding to the phase difference was derived by calculation using a predetermined calculation formula. In Embodiment 3, the arrival direction of the received wave corresponding to the phase difference is derived using the phase difference table T2.

[0041] (Direction Detection Device) The direction detection device 40 according to Embodiment 3 includes a plurality of antennas 5 and a radome 6. Since the plurality of antennas 5 are the same as those in Embodiments 1 and 2, the description thereof will be omitted. The radome 6 functions as a phase difference imparting unit that imparts different phase differences depending on the arrival direction of the received wave. The radome 6 imparts different phase differences depending on the arrival direction of the received wave by varying the shape, varying the laminated structure, or varying both the shape and the laminated structure.

[0042] Further, as shown in FIG. 12, the direction detection device 40 includes a detector 10, a storage unit 11, an extractor 13, and a comparator 14.

[0043] The detector 10 is connected to two antennas 5 and has a detection unit 10a for detecting a phase difference and a detection unit 10b for detecting an intensity difference. The detection unit 10a detects the phase difference of the received waves received by the two antennas 5, and also detects the frequency and polarization as necessary. That is, in the third embodiment, the detection unit 10a detects the phase difference between "antenna 1" and "antenna 2" as the phase difference between the two antennas 5. Note that the detection unit 10b is the same as in the first and second embodiments.

[0044] The storage unit 11 stores a phase difference table T2 instead of the distance d between the two antennas 5. The phase difference table T2 is substantially the same as the intensity difference table T1 shown in FIG. 5. That is, the phase difference table T2 is data that associates the phase difference between the two antennas 5 with the arrival direction of the received wave. The phase difference table T2 may be prepared for each frequency or for each polarization, similar to the intensity difference table T1. The method for obtaining the phase difference table T2 is executed using the above-described acquisition device 21. The phase difference table T2 can be obtained by obtaining the phase difference instead of the intensity difference obtained in the method for obtaining the intensity difference table T1. In the method for obtaining the phase difference table T2 as well, the phase difference table T2 may be obtained for each frequency and for each polarization of the received wave, or the phase difference table T2 for only each frequency or only each polarization may be obtained.

[0045] Furthermore, interpolation processing for interpolating the intensity difference between frequencies or polarizations may be performed on the plurality of phase difference tables T2 prepared for each frequency or polarization of the received wave. Further, each cell in the phase difference table T2 is associated with the arrival direction consisting of the AZ angle and the EL angle, but interpolation processing for interpolating the AZ angle and the EL angle between cells may be performed.

[0046] The extractor 13 has an extraction unit 13a that uses the phase difference table T2 and an extraction unit 13b that uses the intensity difference table T1. The extraction unit 13b is the same as the extractor 13 in Embodiments 1 and 2. The extraction unit 13a extracts the arrival direction of the received wave corresponding to the phase difference from the phase difference table T2 of "Antenna 1" and "Antenna 2" based on the frequency, polarization, and phase difference of the received wave detected by the detection unit 10a of the detector 10. Specifically, in Embodiment 3, the extraction unit 13a acquires the phase difference table T2 corresponding to the frequency based on the frequency of the received wave detected by the detection unit 10a. After that, the extractor 13 extracts the cell of the phase difference table T2 corresponding to the phase difference detected by the detection unit 10b.

[0047] The comparator 14 obtains, as a detection result, the arrival direction of the received wave in which the candidates of the plurality of arrival directions extracted by the extraction unit 13a of the extractor 13 match the candidates of the plurality of arrival directions extracted by the extraction unit 13b of the extractor 13. Here, with reference to FIGS. 13 to 15, the process by the comparator 14 will be specifically described. FIG. 13 is a diagram when cells having the same phase difference value are extracted from the phase difference table T2. In FIG. 13, it is a diagram when cells of the phase difference Δθ between "Antenna 1" and "Antenna 2" are extracted. FIG. 14 is a diagram when cells having the same intensity difference value are extracted from the intensity difference table T1 as shown in FIG. 5. In FIG. 14, it is a diagram when cells of the intensity difference ΔE between "Antenna 1" and "Antenna 2" are extracted.

[0048] As shown in FIG. 13, the comparator 14 acquires cells that are candidates for the direction of arrival based on the phase difference Δθ between "Antenna 1" and "Antenna 2". Also, as shown in FIG. 14, the comparator 14 acquires cells that are candidates for the direction of arrival based on the intensity difference ΔE between "Antenna 1" and "Antenna 2". Then, as shown in FIG. 15, the comparator 14 overlaps the cell corresponding to the direction of arrival based on the phase difference Δθ between "Antenna 1" and "Antenna 2" and the cell corresponding to the direction of arrival based on the intensity difference ΔE between "Antenna 1" and "Antenna 2", and acquires the matching cells. Then, the comparator 14 acquires the AZ angle and the EL angle corresponding to the acquired cells as detection results. That is, the azimuth indicated by the combination of the AZ angle and the EL angle indicated by the matching cells causes a phase difference Δθ between "Antenna 1" and "Antenna 2" and also causes an intensity difference ΔE between "Antenna 1" and "Antenna 2", and since it matches the observation result, it can be inferred that it is the direction of arrival of the received wave.

[0049] (Direction Detection Method) Next, with reference to FIG. 12, a direction detection method for detecting the direction of arrival of a received wave by the direction detection device 40 will be described.

[0050] In the direction detection method, first, step S11 of receiving a received wave by two antennas 5 is executed. After that, in the direction detection method, in the detector 10, step S12 of detecting a phase difference and an intensity difference between the two antennas 5 based on the received waves received by the two antennas 5 is executed. In step S12, in the detection unit 10a, a phase difference between the two antennas 5 and a frequency or polarization as necessary are detected, and in the detection unit 10b, an intensity difference between the two antennas 5 and a frequency or polarization as necessary are detected. Subsequently, in the direction detection method, in the extractor 13, step S13 of acquiring, from the storage unit 11, an intensity difference table T1 and a phase difference table T2 corresponding to the frequency or polarization based on the detected frequency or polarization is executed. Then, in the direction detection method, in the extraction unit 13a of the extractor 13, step S14 of extracting a cell corresponding to the arrival direction of the received wave corresponding to the phase difference detected by the detector 10, that is, a cell corresponding to the AZ angle and the EL angle, from the acquired phase difference table T2 is executed. Also, in the direction detection method, in the extraction unit 13b of the extractor 13, step S15 of extracting a cell corresponding to the arrival direction of the received wave corresponding to the intensity difference detected by the detector 10, that is, a cell corresponding to the AZ angle and the EL angle, from the acquired intensity difference table T1 is executed. In the direction detection method, after the execution of step S15, in the comparator 14, step S16 of comparing the arrival direction of the received wave corresponding to the phase difference calculated in step S3 with the acquired cells of the AZ angle and the EL angle and acquiring the AZ angle and the EL angle of the matching cell as the detection result is executed. Note that in the direction detection method of Embodiment 1, cells are acquired from the intensity difference table T1 and the phase difference table T2 based on the frequency or polarization, but cells may be acquired from the intensity difference table T1 and the phase difference table T2 based on the frequency and polarization.

[0051] [Embodiment 4] Next, referring to FIGS. 16 and 17, Embodiment 4 will be described. In Embodiment 4, to avoid redundant descriptions, only the parts different from Embodiments 1 to 3 will be described, and the parts having the same configuration as those in Embodiments 1 to 3 will be denoted by the same reference numerals and described. FIGS. 16 and 17 are explanatory diagrams of an example related to the direction detection device and the direction detection method according to Embodiment 4.

[0052] In the direction detection method of Embodiment 3, in the extraction unit 13a of the extractor 13, the cells corresponding to the phase difference detected by the detection unit 10a of the detector 10 were extracted, and in the extraction unit 13b of the extractor 13, the cells corresponding to the intensity difference detected by the detection unit 10b of the detector 10 were extracted. In this case, in the comparator 14, as shown on the left side of FIG. 16, there may be a plurality of matching cells. Also, in the comparator 14, as shown on the left side of FIG. 17, the number of matching cells may be zero.

[0053] Therefore, in the direction detection method of Embodiment 4, the extraction unit 13a of the extractor 13 extracts the arrival direction of the received wave corresponding to the phase difference width obtained by adding the second adjustment width (α, β) to the phase difference Δθ detected by the detection unit 10a. Specifically, when the extraction unit 13a acquires the phase difference Δθ from the detection unit 10a, it generates "Δθ - α < Δθ < Δθ + β" as the phase difference width and acquires the cells corresponding to the generated phase difference width. Here, the extraction unit 13a reduces the number of cells to be acquired by reducing the second adjustment width (α, β), while increasing the number of cells to be acquired by increasing the second adjustment width (α, β).

[0054] Also, in the direction detection method, the extraction unit 13b of the extractor 13 extracts the arrival direction of the received wave corresponding to the intensity difference width obtained by adding the adjustment width (α, β) to the intensity difference ΔE detected by the detection unit 10b. Specifically, when the extraction unit 13b acquires the intensity difference ΔE from the detection unit 10b, it generates "ΔE - α < ΔE < ΔE + β" as the intensity difference width and acquires the cells corresponding to the generated intensity difference width. Here, the extraction unit 13b reduces the number of cells to be acquired by reducing the first adjustment width (α, β), while increasing the number of cells to be acquired by increasing the first adjustment width (α, β).

[0055] Specifically, as shown on the left side of FIG. 16, when the comparator 14 compares the cells corresponding to the phase difference width between "Antenna 1" and "Antenna 2" with the cells corresponding to the intensity difference width between "Antenna 1" and "Antenna 2", if a plurality of cells are found to correspond, the extractor 13 narrows at least one of the phase difference width and the intensity difference width. As a result, the cells corresponding to the phase difference width between "Antenna 1" and "Antenna 2" and the cells corresponding to the intensity difference width between "Antenna 1" and "Antenna 2" are reduced. Then, the comparator 14 compares again the cells corresponding to the phase difference width between "Antenna 1" and "Antenna 2" with the cells corresponding to the intensity difference width between "Antenna 1" and "Antenna 2", and as shown on the right side of FIG. 16, the matching cells can be found.

[0056] Also, as shown on the left side of FIG. 17, when the comparator 14 compares the cells corresponding to the phase difference width between "Antenna 1" and "Antenna 2" with the cells corresponding to the intensity difference width between "Antenna 1" and "Antenna 2", and if there are no matching cells, that is, if the cells do not match, the extractor 13 widens the phase difference width and the intensity difference width. As a result, the cells corresponding to the phase difference width between "Antenna 1" and "Antenna 2" and the cells corresponding to the intensity difference width between "Antenna 1" and "Antenna 2" increase. Then, the comparator 14 compares again the cells corresponding to the phase difference width between "Antenna 1" and "Antenna 2" with the cells corresponding to the intensity difference width between "Antenna 1" and "Antenna 2", and as shown on the right side of FIG. 17, the matching cells can be found.

[0057] [Embodiment 5] Next, referring to FIG. 18, Embodiment 5 will be described. In Embodiment 5, in order to avoid redundant descriptions, only the parts different from Embodiments 1 to 4 will be described, and the parts having the same configuration as those in Embodiments 1 to 4 will be described with the same reference numerals. FIG. 18 is a cross-sectional view showing an example of the shape of the radome of the direction detection device according to Embodiment 5.

[0058] In the direction detection methods of Embodiments 1 to 4, in the extractor 13, the cells corresponding to the intensity differences detected by the detector 10 were extracted from the intensity difference table T1. In this case, in the comparator 14, there may be a plurality of matching cells, and it may not be possible to narrow down even by adjusting the intensity difference width. This is because in the radome 6, there are parts where different intensity differences are not imparted depending on the arrival direction of the received wave, or parts where the imparting is insufficient, etc.

[0059] Therefore, in Embodiment 5, as shown in FIG. 18, the configuration of the direction detection device 1 is such that a material for changing the electrical characteristics is added to the radome 6. As the material for changing the electrical characteristics, for example, a good conductor such as a dielectric or a metal can be used. Hereinafter, the configuration with the addition of the dielectric 31 will be described. The dielectric 31 may impart different intensity differences depending on the arrival direction of the received wave. For example, the dielectrics 31a to 31c, 32, and 33 in FIG. 18 may be arranged. In the radome 6a of FIG. 18, the dielectric 31a is provided following the inside of the radome 6a, and the inner surface of the dielectric 31a is a curved surface. In the radome 6b of FIG. 18, the dielectric 31b is in the shape of a block protruding from the inside of the radome 6a. In the radome 6c of FIG. 18, the dielectric 31c is provided following the inside of the radome 6c, and the inner surface of the dielectric 31c facing the antenna 5 is a plane, and the surfaces continuous on both sides in the EL direction of this plane are also planes. In the radome 6d of FIG. 18, a separate dielectric 32 is attached inside the radome 6a. In the radome 6e of FIG. 18, a cap-shaped dielectric 33 covering the antenna 5 is attached.

[0060] Although not shown in the figure, a material for changing the electrical characteristics such as the dielectric 31 may be arranged outside the radome 6. For example, when the direction detection device 1 is mounted on an aircraft, the fuselage outside the radome 6 may be used as the material for changing the electrical characteristics. That is, the fuselage outside the radome 6 may function as an intensity difference imparting unit that imparts different intensity differences depending on the arrival direction of the received wave.

[0061] Moreover, Embodiment 5 may be applied when imparting the phase difference described in Embodiment 3. That is, by adding a material for changing the electrical characteristics to the radome 6, a phase difference different depending on the arrival direction of the received wave may be imparted.

[0062] [Embodiment 6] Next, referring to FIG. 19, Embodiment 6 will be described. In Embodiment 6, in order to avoid duplicate descriptions, parts different from Embodiments 1 to 5 will be described, and parts having the same configuration as those in Embodiments 1 to 5 will be denoted by the same reference numerals and described. FIG. 19 is a schematic configuration diagram showing an example of the arrangement of a plurality of antennas of the direction detection device according to Embodiment 6.

[0063] In Embodiments 1 to 5, two antennas 5 are arranged side by side, but as shown in FIG. 19, three or more may be arranged side by side in the AZ direction. When using three or more antennas 5, since the number of combinations of two antennas 5 can be increased, the candidates for the arrival direction of the received wave corresponding to the intensity difference can be increased, and the accuracy of narrowing down the candidates can be improved. Further, when using three or more antennas 5, the candidates for the arrival direction of the received wave corresponding to the phase difference in Embodiments 3 and 4 can also be increased by increasing the number of combinations of two antennas 5.

[0064] In Embodiment 6, when using three or more antennas 5, when calculating the arrival direction of the received wave corresponding to the phase difference using a predetermined calculation formula, they are arranged in a row in the AZ direction so as to have unequal intervals. On the other hand, in Embodiment 6, when using three or more antennas 5, when calculating the arrival direction of the received wave corresponding to the phase difference using the phase difference table T2, there is no restriction on the arrangement of the antennas 5.

[0065] Also, in Embodiments 1 to 5, while changing the AZ angle and the EL angle, the arrival direction of the received wave was detected using the intensity difference table T1 in which the intensity differences in each cell were obtained. However, the configuration is not particularly limited to this. For example, while load-deforming the radome 6, the intensity differences in each cell may be obtained to generate the intensity difference table T1, and the arrival direction of the received wave may be detected in consideration of the load deformation of the radome 6 using the generated intensity difference table T1.

[0066] Also, in Embodiments 1 to 5, the radome 6 of the direction detection devices 1 and 40 functioned as the intensity difference imparting unit. However, by making the gain of the elements of the antenna 5 a non-uniform gain in space, the antenna 5 itself may function as the intensity difference imparting unit. That is, by making the gain of the elements of the antenna 5 different for each element, different intensity differences can be obtained depending on the arrival direction of the received wave.

[0067] As described above, the direction detection devices 1 and 40, the method for obtaining the intensity difference table T1, the direction detection method, and the direction detection program described in the embodiments are understood as follows, for example.

[0068] The direction detection devices 1 and 40 according to the first aspect are direction detection devices 1 and 40 for detecting the arrival direction of a received wave, and include a plurality of antennas 5 for receiving the received wave, and an intensity difference imparting unit (radome 6, dielectric 31, good conductor, antenna element having a non-uniform gain in space) that imparts an intensity difference different depending on the arrival direction of the received wave to the reception intensity of the received wave received by the plurality of antennas 5, a storage unit 11 that stores, for each combination of two of the plurality of antennas 5, an intensity difference table T1 associating the intensity difference between the two antennas 5 and the arrival direction of the received wave, a detector 10 that detects, based on the received wave received by the plurality of antennas 5, the intensity difference between the two antennas 5 and the phase difference between the two antennas 5, an extractor 13 that extracts, according to the combination of the two antennas 5, the arrival direction of the received wave corresponding to the intensity difference detected by the detector 10 from the intensity difference table T1 stored in the storage unit, a derivation unit (arithmetic unit 12) that derives the arrival direction of the received wave corresponding to the phase difference detected by the detector 10, and a comparator 14 that compares the arrival direction of the received wave corresponding to the intensity difference acquired from the extractor 13 with the arrival direction of the received wave corresponding to the phase difference acquired from the derivation unit and acquires, as a detection result, the matching arrival direction of the received wave.

[0069] According to this configuration, even when arranging a plurality of antennas 5 due to physical constraints in the internal space of the radome 6, by using the phase difference and the intensity difference, which are different physical quantities, ambiguity can be removed and the three-dimensional arrival direction of the received wave can be suitably acquired. At this time, since at least two antennas 5 may be used, the device configuration can be simplified.

[0070] As a second aspect, the intensity difference table T1 is stored for each frequency or polarization of the received wave. The detector 10 detects the frequency or polarization of the received wave, and the extractor 13 acquires the intensity difference table T1 corresponding to the frequency or polarization based on the frequency or polarization detected by the detector 10, and extracts the arrival direction of the received wave corresponding to the intensity difference detected by the detector 10 from the acquired intensity difference table T1.

[0071] According to this configuration, since the intensity difference table T1 can be acquired for each frequency or polarization, an appropriate intensity difference corresponding to the frequency and polarization can be acquired, and the arrival direction of the received wave with high accuracy corresponding to the intensity difference can be extracted.

[0072] As a third aspect, the intensity difference imparting unit has a radome 6 that houses the plurality of antennas 5, and the radome 6 has a non-uniform shape or non-uniform structure in three-dimensional space.

[0073] According to this configuration, by making the shape of the radome 6 a non-uniform shape or non-uniform structure in three-dimensional space, intensity differences different depending on the arrival direction of the received wave can be imparted.

[0074] As a fourth aspect, the intensity difference imparting unit is provided in the radome 6 that houses the plurality of antennas 5 and has a material (dielectric 31, good conductor) that changes electrical characteristics.

[0075] According to this configuration, by providing a material that changes electrical characteristics in the radome 6, intensity differences different depending on the arrival direction of the received wave can be easily imparted.

[0076] As a fifth aspect, the intensity difference imparting unit is the antenna 5 in which the gain of the element of the antenna 5 is a non-uniform gain in space.

[0077] According to this configuration, by making the gain of the elements of the antenna 5 a non-uniform gain in space, the antenna 5 itself can be easily made to function as an intensity difference imparting unit. That is, by making the gain of the elements of the antenna 5 different for each element, it is possible to easily obtain different intensity differences depending on the arrival direction of the received wave.

[0078] As a sixth aspect, the extractor 13 extracts the arrival direction of the received wave corresponding to an intensity difference width obtained by imparting a first adjustment width to the intensity difference detected by the detector 10. When candidates for the arrival direction of the received wave corresponding to a plurality of the intensity difference widths extracted according to the combination do not match, the comparator 14 widens the first adjustment width, while when there are a plurality of candidates for the arrival direction of the received wave that match, the comparator 14 narrows the first adjustment width.

[0079] According to this configuration, by adjusting the first adjustment width, it is possible to appropriately find the arrival direction of the received wave that matches.

[0080] As a seventh aspect, the arrival direction of the received wave is defined by an AZ angle that is an angle in the azimuth direction and an EL angle that is an angle in the elevation direction orthogonal to the azimuth direction. The intensity difference table T1 has a plurality of cells associated with the AZ angle and the EL angle, and the intensity difference is set in each of the plurality of cells, and the intensity difference between the cells is interpolated.

[0081] According to this configuration, since the intensity difference between the cells can be appropriately interpolated, the intensity difference can be accurately obtained, and the arrival direction of the received wave corresponding to the intensity difference can be appropriately obtained.

[0082] As an eighth aspect, when the intensity difference table T1 is prepared for each frequency or polarization of the received wave, the intensity difference between the frequencies or the intensity difference between the polarizations in the intensity difference table T1 is interpolated.

[0083] According to this configuration, since the intensity difference between frequencies and the intensity difference between polarization states can be appropriately interpolated, the intensity difference between frequencies and the intensity difference between polarization states can be accurately obtained, and the arrival direction of the received wave corresponding to the intensity difference can be appropriately obtained.

[0084] As a ninth aspect, the deriving unit is an arithmetic unit 12 that calculates the arrival direction of the received wave from a predetermined calculation formula based on the phase difference, the frequency of the received wave, and the distance between two of the antennas 5.

[0085] According to this configuration, the arrival direction of the received wave can be easily derived by performing an operation using a predetermined calculation formula.

[0086] As a tenth aspect, the storage unit 11 further stores, for each combination of two of the plurality of antennas 5, a phase difference table T2 that associates the phase difference between two of the antennas 5 with the arrival direction of the received wave. The deriving unit is an extractor 13 that extracts, from the phase difference table T2 stored in the storage unit 11, the arrival direction of the received wave corresponding to the phase difference detected by the detector 10 according to the combination of two of the antennas 5.

[0087] According to this configuration, by using the phase difference table T2, candidates for the arrival direction of the received wave can be easily extracted.

[0088] As an eleventh aspect, the phase difference table T2 is stored for each frequency or polarization state of the received wave. The detector 10 detects the frequency or polarization state of the received wave. The extractor 13 obtains the phase difference table T2 corresponding to the frequency or polarization state based on the frequency or polarization state detected by the detector 10, and extracts the arrival direction of the received wave corresponding to the phase difference detected by the detector 10 from the obtained phase difference table T2.

[0089] According to this configuration, since the phase difference table T2 can be obtained for each frequency or each polarization, an appropriate phase difference corresponding to the frequency and polarization can be obtained, and the arrival direction of the received wave with good accuracy corresponding to the phase difference can be extracted.

[0090] As a twelfth aspect, the extractor 13 extracts the arrival direction of the received wave corresponding to a phase difference width obtained by adding a second adjustment width to the phase difference detected by the detector 10, and the comparator 14 determines that the arrival direction candidate of the received wave corresponding to the phase difference width and the arrival direction candidate of the received wave corresponding to the intensity difference do not match. In this case, while widening the second adjustment width, when there are a plurality of matching arrival direction candidates of the received wave, the second adjustment width is narrowed.

[0091] According to this configuration, by adjusting the second adjustment width, the arrival direction of the received wave that matches can be appropriately found.

[0092] As a thirteenth aspect, the arrival direction of the received wave is defined by an AZ angle that is an angle in the azimuth direction and an EL angle that is an angle in the elevation direction orthogonal to the azimuth direction. The phase difference table T2 has a plurality of cells associated with the AZ angle and the EL angle, and the phase difference is set in each of the plurality of cells, and the phase difference between the cells is interpolated.

[0093] According to this configuration, since the phase difference between cells can be appropriately interpolated, the phase difference between frequencies can be accurately obtained, and the arrival direction of the received wave corresponding to the phase difference can be appropriately obtained.

[0094] As a fourteenth aspect, when the phase difference table T2 is prepared for each frequency or each polarization of the received wave, the phase difference table T2 interpolates the phase difference between the frequencies or the phase difference between the polarizations.

[0095] According to this configuration, since the phase difference between frequencies and the phase difference between polarization planes can be appropriately interpolated, the phase difference between frequencies and the phase difference between polarization planes can be accurately obtained, and the arrival direction of the received wave corresponding to the phase difference can be appropriately obtained.

[0096] The method for obtaining the intensity difference table T1 according to the 15th aspect is a method for obtaining the intensity difference table T1 used in the above-described direction detection devices 1 and 40, and includes steps of setting, for a plurality of antennas 5, the received wave generated from a radio wave source (transmitter 22) to have a predetermined arrival direction, generating the received wave from the radio wave source, receiving the received wave by the plurality of antennas 5, and obtaining an intensity difference table T1 in which the intensity difference between two of the antennas 5 and the arrival direction of the received wave are associated with each other based on the intensity difference obtained by receiving the received wave.

[0097] According to this configuration, an intensity difference table T1 in which the intensity difference and the arrival direction of the received wave are appropriately associated with each other can be obtained.

[0098] The direction detection method according to the 16th aspect is a direction detection method for detecting the arrival direction of a received wave by the above-described direction detection devices 1 and 40, including steps S1 and S11 of receiving the received wave by a plurality of antennas 5, steps S2 and S12 of detecting, by the detector 10, an intensity difference and a phase difference between two of the antennas 5 based on the received wave received by the plurality of antennas 5, steps S5 and S15 of extracting, by the extractor 13, from the intensity difference table T1 stored in the storage unit 11, the arrival direction of the received wave corresponding to the intensity difference detected by the detector 10 according to the combination of two of the antennas 5, steps S3 and S13 of deriving the arrival direction of the received wave corresponding to the phase difference detected by the detector 10, and steps S6 and S16 of comparing, by the comparator 14, the arrival direction of the received wave corresponding to the intensity difference obtained from the extractor 13 with the arrival direction of the received wave corresponding to the phase difference obtained from the derivation unit, and obtaining, as a detection result, the matching arrival direction of the received wave.

[0099] According to this configuration, even when arranging a plurality of antennas 5 due to physical constraints in the internal space of the radome 6, by using the phase difference and the intensity difference which are different physical quantities, ambiguity can be removed and the three-dimensional arrival direction of the received wave can be suitably obtained. At this time, since at least two antennas 5 may be used, simplification of the device configuration can be achieved.

[0100] The direction detection program according to the 17th aspect is a direction detection program for detecting the arrival direction of a received wave, which is executed by the above-described direction detection devices 1 and 40. The program includes steps S1 and S11 of receiving the received wave by a plurality of antennas 5, steps S2 and S12 of detecting, by the detector 10, an intensity difference and a phase difference between two of the antennas 5 based on the received wave received by the plurality of antennas 5, steps S5 and S15 of extracting, by the extractor 13, from the intensity difference table T1 stored in the storage unit 11, the arrival direction of the received wave corresponding to the intensity difference detected by the detector 10 according to the combination of two of the antennas 5, steps S3 and S13 of deriving the arrival direction of the received wave corresponding to the phase difference detected by the detector 10, and steps S6 and S16 of comparing, by the comparator 14, the arrival direction of the received wave corresponding to the intensity difference obtained from the extractor 13 with the arrival direction of the received wave corresponding to the phase difference obtained from the derivation unit, and obtaining, as a detection result, the matching arrival direction of the received wave.

[0101] According to this configuration, even when arranging a plurality of antennas 5 due to physical constraints in the internal space of the radome 6, by using the phase difference and the intensity difference, which are different physical quantities, ambiguity can be removed, and the three-dimensional arrival direction of the received wave can be suitably obtained. At this time, since at least two antennas 5 may be used, the device configuration can be simplified.

Explanation of Reference Numerals

[0102] 1, 40 Direction detection device 5 Antenna 6 Radome 10 Detector 11 Storage unit 12 Arithmetic unit 13 Extractor 14 Comparator 21 Acquisition device 22 Transmitter 23 Receiver 24 Operation unit 25 Measuring instrument Dielectrics 31a to 31c, 32, 33 Intensity difference table T1 Phase difference table T2

Claims

1. In a direction detection device for detecting the arrival direction of a received wave, a plurality of antennas for receiving the received wave; an intensity difference imparting unit that imparts an intensity difference different depending on the arrival direction of the received wave to the reception intensity of the received wave received by the plurality of antennas; a storage unit that stores, for each combination of two of the plurality of antennas, an intensity difference table associating the intensity difference between the two antennas and the arrival direction of the received wave; a detector that detects, based on the received wave received by the plurality of antennas, the intensity difference between two of the antennas and the phase difference between two of the antennas; an extractor that extracts, according to the combination of two of the antennas, the arrival direction of the received wave corresponding to the intensity difference detected by the detector from the intensity difference table stored in the storage unit; a derivation unit that derives the arrival direction of the received wave corresponding to the phase difference detected by the detector; a comparator that compares the arrival direction of the received wave corresponding to the intensity difference acquired from the extractor with the arrival direction of the received wave corresponding to the phase difference acquired from the derivation unit, and acquires, as a detection result, the matching arrival direction of the received wave; and the extractor extracts the arrival direction of the received wave corresponding to an intensity difference width obtained by imparting a first adjustment width to the intensity difference detected by the detector, wherein when the candidate for the arrival direction of the received wave corresponding to the intensity difference width and the candidate for the arrival direction of the received wave corresponding to the phase difference do not match, the comparator widens the first adjustment width, and when there are a plurality of candidates for the matching arrival direction of the received wave, the comparator narrows the first adjustment width. A direction detection device.

2. The intensity difference table is stored for each frequency or polarization of the received wave, the detector detects the frequency or polarization of the received wave, and the extractor acquires the intensity difference table corresponding to the frequency or polarization based on the frequency or polarization detected by the detector, and extracts the arrival direction of the received wave corresponding to the intensity difference detected by the detector from the acquired intensity difference table. The direction detection device according to claim 1.

3. The intensity difference imparting unit has a radome that houses the plurality of antennas, and the radome has a non-uniform shape or non-uniform structure in three-dimensional space. The direction detection device according to claim 1 or 2.

4. The intensity difference imparting unit is provided in a radome that houses a plurality of the antennas, and the direction detection device according to any one of claims 1 to 3, which has a material that changes electrical characteristics.

5. The intensity difference imparting unit is the direction detection device according to any one of claims 1 to 4, which has an antenna in which the gain of an element of the antenna is a non-uniform gain in space.

6. The arrival direction of the received wave is defined by an AZ angle that is an angle in the azimuth direction and an EL angle that is an angle in the elevation angle direction orthogonal to the azimuth direction. The intensity difference table has a plurality of cells associated with the AZ angle and the EL angle, and the intensity difference is set in each of the plurality of cells, and the intensity difference between the cells is interpolated. The direction detection device according to any one of claims 1 to 5.

7. When the intensity difference table is prepared for each frequency or polarization of the received wave, the intensity difference table is the direction detection device according to any one of claims 1 to 6, in which the intensity difference between the frequencies or the intensity difference between the polarizations is interpolated.

8. The derivation unit is an arithmetic unit that calculates the arrival direction of the received wave from a predetermined calculation formula based on the phase difference, the frequency of the received wave, and the distance between two of the antennas. The direction detection device according to any one of claims 1 to 7.

9. The storage unit further stores, for each combination of two of the plurality of antennas, a phase difference table that associates the phase difference between two of the antennas with the arrival direction of the received wave. The derivation unit is an extraction unit that extracts, according to the combination of two of the antennas, the arrival direction of the received wave corresponding to the phase difference detected by the detector from the phase difference table stored in the storage unit. The direction detection device according to any one of claims 1 to 7.

10. The phase difference table is stored for each frequency or polarization of the received wave. The detector detects the frequency or polarization of the received wave. The extraction unit acquires the phase difference table corresponding to the frequency or polarization based on the frequency or polarization detected by the detector, and extracts the arrival direction of the received wave corresponding to the phase difference detected by the detector from the acquired phase difference table. The direction detection device according to claim 9.

11. The extractor extracts the arrival direction of the received wave corresponding to the phase difference width obtained by adding a second adjustment width to the phase difference detected by the detector. When the candidate for the arrival direction of the received wave corresponding to the phase difference width and the candidate for the arrival direction of the received wave corresponding to the intensity difference do not match, the comparator widens the second adjustment width, while when there are a plurality of candidates for the arrival direction of the received wave that match, the comparator narrows the second adjustment width. The direction detection device according to claim 9 or 10.

12. The arrival direction of the received wave is defined by an AZ angle that is an angle in the azimuth direction and an EL angle that is an angle in the elevation direction orthogonal to the azimuth direction. The phase difference table has a plurality of cells associated with the AZ angle and the EL angle, and the phase difference is set in each of the plurality of cells, and the phase difference between the cells is interpolated. The direction detection device according to any one of claims 9 to 11.

13. When the phase difference table is prepared for each frequency or polarization of the received wave, the phase difference table has the phase difference between the frequencies or the phase difference between the polarizations interpolated. The direction detection device according to any one of claims 9 to 12.

14. In a direction detection device for detecting the arrival direction of a received wave, a plurality of antennas for receiving the received wave, an intensity difference imparting unit that imparts an intensity difference that varies depending on the arrival direction of the received wave to the received intensity of the received wave received by the plurality of antennas, a storage unit that stores, for each combination of two of the plurality of antennas, an intensity difference table associating the intensity difference between the two antennas with the arrival direction of the received wave, a detector that detects, based on the received wave received by the plurality of antennas, the intensity difference between the two antennas and the phase difference between the two antennas, respectively, an extractor that extracts, according to the combination of the two antennas, the arrival direction of the received wave corresponding to the intensity difference detected by the detector from the intensity difference table stored in the storage unit, a derivation unit that derives the arrival direction of the received wave corresponding to the phase difference detected by the detector. A comparator that compares the arrival direction of the received wave corresponding to the intensity difference obtained from the extractor with the arrival direction of the received wave corresponding to the phase difference obtained from the derivation unit, and acquires the matching arrival direction of the received wave as a detection result; The extractor extracts the arrival direction of the received wave corresponding to the phase difference width obtained by adding a second adjustment width to the phase difference detected by the detector; When the candidate for the arrival direction of the received wave corresponding to the phase difference width does not match the candidate for the arrival direction of the received wave corresponding to the intensity difference, the comparator widens the second adjustment width, while when there are a plurality of candidates for the matching arrival direction of the received wave, the comparator narrows the second adjustment width. A direction detection device. [

15. ] A method for obtaining an intensity difference table for obtaining an intensity difference table used in the direction detection device according to any one of Claims 1 to 14, setting, for a plurality of antennas, the received wave generated from the radio wave source so as to have a predetermined arrival direction; generating the received wave from the radio wave source; receiving the received wave by a plurality of the antennas; obtaining an intensity difference table associating the intensity difference between two of the antennas with the arrival direction of the received wave based on the intensity difference obtained by receiving the received wave. A method for obtaining an intensity difference table. [

16. ] A direction detection method for detecting the arrival direction of a received wave by the direction detection device according to any one of Claims 1 to 14, receiving the received wave by a plurality of antennas; detecting, by the detector, the intensity difference and the phase difference between two of the antennas based on the received wave received by the plurality of antennas; extracting, by the extractor, from the intensity difference table stored in the storage unit, the arrival direction of the received wave corresponding to the intensity difference detected by the detector according to the combination of the two antennas; deriving the arrival direction of the received wave corresponding to the phase difference detected by the detector; executing, in the comparator, comparing the arrival direction of the received wave corresponding to the intensity difference obtained from the extractor with the arrival direction of the received wave corresponding to the phase difference obtained from the derivation unit, and obtaining the matching arrival direction of the received wave as a detection result; In the extracting step, in the extractor, the arrival direction of the received wave corresponding to the intensity difference width obtained by adding a first adjustment width to the intensity difference detected by the detector is extracted. In the step of obtaining the detection result, in the comparator, when the candidate of the arrival direction of the received wave corresponding to the intensity difference width and the candidate of the arrival direction of the received wave corresponding to the phase difference do not match, the first adjustment width is widened, while when there are a plurality of candidates of the arrival direction of the received wave that match, the first adjustment width is narrowed. Direction detection method.

17. A direction detection method for detecting the arrival direction of a received wave by the direction detection device according to any one of Claims 1 to 14, Receiving the received wave by a plurality of antennas; In the detector, detecting the intensity difference and the phase difference between two of the antennas based on the received wave received by the plurality of antennas; In the extractor, extracting, according to the combination of two of the antennas, the arrival direction of the received wave corresponding to the intensity difference detected by the detector from the intensity difference table stored in the storage unit; Deriving the arrival direction of the received wave corresponding to the phase difference detected by the detector; In the comparator, comparing the arrival direction of the received wave corresponding to the intensity difference obtained from the extractor with the arrival direction of the received wave corresponding to the phase difference obtained from the derivation unit, and obtaining, as a detection result, the arrival direction of the received wave that matches. In the extracting step, in the extractor, the arrival direction of the received wave corresponding to the phase difference width obtained by adding a second adjustment width to the phase difference detected by the detector is extracted. In the step of obtaining the detection result, in the comparator, when the candidate of the arrival direction of the received wave corresponding to the phase difference width and the candidate of the arrival direction of the received wave corresponding to the intensity difference do not match, the second adjustment width is widened, while when there are a plurality of candidates of the arrival direction of the received wave that match, the second adjustment width is narrowed. Direction detection method.

18. A direction detection program for detecting the arrival direction of a received wave, which is executed by the direction detection device according to any one of Claims 1 to 14, Receiving the received wave by a plurality of antennas; In the detector, based on the received waves received by the plurality of antennas, detecting the intensity difference and the phase difference between two of the antennas; In the extractor, extracting, according to combinations of two of the antennas, the arrival direction of the received wave corresponding to the intensity difference detected by the detector from the intensity difference table stored in the storage unit; deriving the arrival direction of the received wave corresponding to the phase difference detected by the detector; In the comparator, comparing the arrival direction of the received wave corresponding to the intensity difference obtained from the extractor with the arrival direction of the received wave corresponding to the phase difference obtained from the derivation unit, and obtaining, as a detection result, the arrival direction of the received wave that matches; In the extracting step, in the extractor, extracting the arrival direction of the received wave corresponding to an intensity difference width obtained by adding a first adjustment width to the intensity difference detected by the detector; In the step of obtaining the detection result, in the comparator, when the candidate for the arrival direction of the received wave corresponding to the intensity difference width and the candidate for the arrival direction of the received wave corresponding to the phase difference do not match, widening the first adjustment width, and when there are a plurality of candidates for the arrival direction of the received wave that match, narrowing the first adjustment width, a direction detection program for execution. **Claim 19** A direction detection program for detecting the arrival direction of a received wave, which is executed by the direction detection device according to any one of Claims 1 to 14, receiving the received wave by a plurality of antennas; In the detector, based on the received waves received by the plurality of antennas, detecting the intensity difference and the phase difference between two of the antennas; In the extractor, extracting, according to combinations of two of the antennas, the arrival direction of the received wave corresponding to the intensity difference detected by the detector from the intensity difference table stored in the storage unit; deriving the arrival direction of the received wave corresponding to the phase difference detected by the detector; In the comparator, comparing the arrival direction of the received wave corresponding to the intensity difference obtained from the extractor with the arrival direction of the received wave corresponding to the phase difference obtained from the derivation unit, and obtaining, as a detection result, the arrival direction of the received wave that matches; In the step of extraction, in the extractor, the arrival direction of the received wave corresponding to the phase difference width obtained by adding a second adjustment width to the phase difference detected by the detector is extracted. In the step of obtaining the detection result, in the comparator, when the candidate for the arrival direction of the received wave corresponding to the phase difference width and the candidate for the arrival direction of the received wave corresponding to the intensity difference do not match, while widening the second adjustment width, when there are a plurality of candidates for the arrival direction of the received wave that match, a direction detection program that causes the second adjustment width to be narrowed.

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