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 the 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 between the two antennas based on the received receiving waves; an extractor that extracts, from the intensity difference table, the plurality of directions of arrival of the receiving waves corresponding to the intensity difference detected by the detector according to the combination of the two antennas; and a comparator that compares the directions of arrival of the receiving waves corresponding to the plurality of intensity differences 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 obtaining 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 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 them.

[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 direction of arrival of the received wave in a plane (two-dimensional) including the one direction. Therefore, in order to detect the three-dimensional direction of arrival of the received wave, it is necessary to arrange the antennas in one direction and also 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 the 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 direction of arrival 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 direction of arrival 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 the intensity difference between two of the antennas based on the received wave received by the plurality of antennas; an extractor that extracts a plurality of arrival directions of the received wave corresponding to the intensity difference detected by the detector from the intensity difference table stored in the storage unit, according to the combination of the two antennas; and a comparator that compares the arrival directions of the received wave corresponding to the plurality of intensity differences obtained from the extractor and obtains, as a detection result, the arrival direction of the received wave that matches.

[0009] The method for acquiring the intensity difference table of the present disclosure is a method for acquiring an intensity difference table used in the above direction detection device. The method includes the steps of: 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 acquiring 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: receiving the received wave by a plurality of antennas; detecting, by the detector, an intensity difference between two of the antennas based on the received wave received by the plurality of antennas; extracting, by the extractor, a plurality of arrival directions of the received wave corresponding to the intensity difference detected by the detector from the intensity difference table stored in the storage unit according to combinations of the two antennas; and comparing, by the comparator, the arrival directions of the received wave corresponding to the plurality of obtained intensity differences, 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: receiving the received wave by a plurality of antennas; detecting, by the detector, an intensity difference between two of the antennas based on the received wave received by the plurality of antennas; extracting, by the extractor, a plurality of arrival directions of the received wave corresponding to the intensity difference detected by the detector from the intensity difference table stored in the storage unit according to combinations of the two antennas; and comparing, by the comparator, the arrival directions of the received wave corresponding to the plurality of obtained intensity differences, and 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 antennas in the radome, it is possible to preferably detect the arrival direction of a received wave in a dimension that could not be obtained conventionally while removing ambiguity.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Mode for Carrying Out 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. Also, the components 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 components described below can be combined as appropriate, and when there are a plurality of embodiments, it is also possible to combine each embodiment.

[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, the 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 an intensity difference table. FIG. 6 is a graph showing an example of the intensity difference table. FIG. 7 is a graph showing an example of the intensity difference table. FIG. 8 is a graph when the arrival directions of the received waves are superimposed. FIG. 9 is a schematic configuration diagram of a device used for the method of obtaining the intensity difference table.

[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 linearly in a plurality along the AZ direction (the x direction in FIG. 1) and one is provided in the EL direction (the z direction in FIGS. 1 to 3), which is a one-dimensional arrangement. In Embodiment 1, although it is a one-dimensional arrangement to suppress the height in the EL direction, the arrangement is not particularly limited. The plurality of antennas 5 are provided with at least three or more so that there are two or more combination patterns of two antennas. The plurality of antennas 5 are arranged at a predetermined interval in the AZ direction. In Embodiment 1, the intervals between the antennas 5 are unequal intervals, but they may be equal intervals.

[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 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 (the 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 (the 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 depending on the arrival direction of the received wave may be imparted 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, an extractor 12, and a comparator 13.

[0021] Detector 10 is connected to a plurality of antennas 5 and detects the intensity difference, frequency, and polarization of the received wave received by the plurality of antennas 5. Note that information regarding polarization may be obtained from the intensity ratio of two orthogonal linear antennas or from measurements obtained by rotating one linear antenna. In this case, a dedicated antenna for detecting polarization may be provided separately. Detector 10 detects the intensity difference between two antennas 5 as the intensity difference. Here, in Embodiment 1, three antennas, namely, "Antenna 1", "Antenna 2", and "Antenna 3", are applied as the plurality of antennas 5. In this case, in Embodiment 1, detector 10 detects the intensity difference between "Antenna 1" and "Antenna 2" and the intensity difference between "Antenna 1" and "Antenna 3" as the intensity difference between two antennas 5. Note that detector 10 may detect the intensity difference between "Antenna 2" and "Antenna 3", and may detect at least two or more intensity differences according to the combination pattern of two antennas among the plurality of antennas 5. Hereinafter, in the direction detection device 1 and the direction detection method of Embodiment 1, the description will be made based on the combinations of "Antenna 1" and "Antenna 2" and "Antenna 1" and "Antenna 3", but the present invention is not particularly limited to this combination, and it may be applied as a direction detection device 1 and a direction detection method using three or more intensity differences. Further, although detector 10 detects the intensity difference, frequency, and polarization, it is sufficient to detect at least the intensity difference, and the frequency and polarization may be detected as necessary.

[0022] The memory unit 11 stores the intensity difference table T shown in FIG. 5. The intensity difference table T 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 represents the AZ angle and the vertical axis represents the EL angle. Also, the intensity difference table T is composed of a plurality of cells associated with the AZ angle and the EL angle. Each cell has an associated intensity difference. Therefore, the AZ angle and the EL angle are associated with the cell with which the intensity difference is associated. Also, the intensity difference table T is prepared for at least each frequency or polarization, and if necessary, an intensity difference table T corresponding to the frequency, an intensity difference table T corresponding to the polarization, or an intensity difference table T corresponding to the frequency and the polarization may be prepared. In other words, if the intensity difference table T is not necessary, the intensity difference table T corresponding to the frequency and the intensity difference table T corresponding to the polarization do not have to be prepared. Furthermore, the intensity difference table T is prepared for each combination of two antennas. That is, in Embodiment 1, as the intensity difference table T, an intensity difference table T for "antenna 1" and "antenna 2" and an intensity difference table T for "antenna 1" and "antenna 3" are prepared. Also, although not shown, the memory 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 T includes not only the intensity difference table T shown in FIG. 5 but also a mathematical formulation based on the intensity difference table T shown in FIG. 5.

[0023] Based on the frequency, polarization, and intensity difference of the received wave detected by the detector 10, the extractor 12 extracts the arrival direction of the received wave corresponding to the intensity difference from the intensity difference table T. Specifically, in Embodiment 1, the extractor 12 obtains, if necessary, an intensity difference table T corresponding to the frequency, an intensity difference table T corresponding to the polarization, or an intensity difference table T corresponding to the frequency and the polarization based on the frequency and polarization of the received wave detected by the detector 10. After that, the extractor 12 extracts the cell of the intensity difference table T corresponding to the intensity difference detected by the detector 10. Also, the extractor 12 extracts the cell of the intensity difference table T in each of the combinations of "antenna 1" and "antenna 2" and "antenna 1" and "antenna 3".

[0024] The comparator 13 obtains, as a detection result, the arrival direction of the received wave in which a plurality of candidate arrival directions extracted by the extractor 12 match. Here, with reference to FIGS. 6 to 8, the processing by the comparator 13 will be specifically described. FIGS. 6 and 7 are diagrams when cells having the same intensity difference are extracted from the intensity difference table T as shown in FIG. 5. In FIG. 6, it is a diagram when cells with the intensity difference between "antenna 1" and "antenna 2" being a predetermined intensity difference ΔE 12 are extracted. In FIG. 7, it is a diagram when cells with the intensity difference between "antenna 1" and "antenna 3" being a predetermined intensity difference ΔE 13 are extracted.

[0025] When the comparator 13 obtains the intensity difference ΔE 12 between "antenna 1" and "antenna 2" extracted by the extractor 12, as shown in FIG. 6, it obtains the cells corresponding to the intensity difference ΔE 12 . Also, when the comparator 13 obtains the intensity difference ΔE 13 between "antenna 1" and "antenna 3" extracted by the extractor 12, as shown in FIG. 7, it obtains the cells corresponding to the intensity difference ΔE 13 . Then, as shown in FIG. 8, the comparator 13 obtains the cells where the cells corresponding to the intensity difference ΔE 12 between "antenna 1" and "antenna 2" and the cells corresponding to the intensity difference ΔE 13 between "antenna 1" and "antenna 3" match. Then, the comparator 13 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 is the azimuth that causes the intensity difference ΔE 12 between "antenna 1" and "antenna 2" and at the same time causes the intensity difference ΔE 13 between "antenna 1" and "antenna 3". Since it matches the observation result, it can be inferred that it is the arrival direction of the received wave.

[0026] (Method for obtaining intensity difference table) Next, with reference to FIG. 9, a method for obtaining the intensity difference table T used in the direction detection device 1 will be described. To obtain the intensity difference table T, 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.

[0027] The transmitter 22 transmits a radio wave having a predetermined polarization toward the receiver 23. The receiver 23 has equivalent performance simulating the plurality of antennas 5 and the radome 6 of the direction detection device 1, and acquires the received radio wave as a received wave. The operation unit 24 moves the receiver 23 so that the position of the transmitter 22 as seen 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 wave received by the receiver 23, and acquires the AZ angle and EL angle at the time of acquisition.

[0028] In the method for obtaining the intensity difference table T, the receiver 23 including the plurality of antennas 5 executes a step of operating the operation unit 24 so that the arrival direction becomes a predetermined AZ angle and EL angle. After that, in the acquisition method, a step of generating a radio wave having a predetermined frequency from the transmitter 22 serving as a radio wave source is executed. Then, in the acquisition method, a step of receiving, by the receiver 23, the radio wave having a predetermined frequency as a received wave is executed. In the acquisition method, when the receiver 23 receives the received wave, the measuring device 25 measures the intensity difference of the received wave 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 obtaining the intensity difference table T for each frequency and polarization of the received wave is executed. Note that in the above method for obtaining the intensity difference table T, the intensity difference table T is obtained for each frequency and polarization of the received wave, but the intensity difference table T may be obtained only for each frequency or only for each polarization.

[0029] Note that for each of the frequencies or polarization states of the received waves, a plurality of intensity difference tables T prepared may be subjected to an interpolation process in which the intensity differences between the frequencies or polarization states are interpolated. Further, although each cell in the intensity difference table T is associated with an arrival direction composed of an AZ angle and an EL angle, an interpolation process in which the AZ angle and the EL angle between the cells are interpolated may be executed.

[0030] (Direction Detection Method) Next, with reference to FIG. 4, a direction detection method for detecting the arrival direction of received waves by the direction detection device 1 will be described.

[0031] In the direction detection method, first, step S1 of receiving received waves by a plurality of antennas 5 is executed. After this, in the direction detection method, in the detector 10, step S2 of detecting the intensity difference and the frequency or polarization state between two antennas 5 based on the received waves received by the plurality of antennas 5 is executed. Note that in step S2, the frequency and the polarization state may not be detected. Subsequently, in the direction detection method, in the extractor 12, step S3 of acquiring, from the storage unit 11, the intensity difference table T corresponding to the detected frequency or polarization state is executed based on the detected frequency or polarization state. Then, in the direction detection method, in the extractor 12, step S4 of extracting a plurality of cells corresponding to the arrival direction of the received waves, that is, the AZ angle and the EL angle, corresponding to the intensity difference detected by the detector 10 from the acquired intensity difference table T according to the combination of two antennas 5 is executed. In the direction detection method, after the execution of step S4, in the comparator 13, step S5 of comparing the acquired plurality of cells of the AZ angle and the EL angle and acquiring the AZ angle and the EL angle of the matching cells as the detection result is executed. Note that in the direction detection method of Embodiment 1, the corresponding intensity difference table T is used based on the frequency or polarization state, but the corresponding intensity difference table T may be used based on the frequency and the polarization state.

[0032] [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. FIG. 10 is an explanatory diagram of an example related to the direction detection device and the direction detection method according to Embodiment 2. FIG. 11 is an explanatory diagram of an example related to the direction detection device and the direction detection method according to Embodiment 2.

[0033] In the direction detection method of Embodiment 1, in the extractor 12, cells corresponding to the intensity difference detected by the detector 10 were extracted according to the combination of the two antennas 5. In this case, in the comparator 13, as shown on the left side of FIG. 10, there may be a plurality of matching cells. Also, in the comparator 13, as shown on the left side of FIG. 11, the number of matching cells may be zero.

[0034] Therefore, in the direction detection method of Embodiment 2, the extractor 12 extracts the arrival direction of the received wave corresponding to the intensity difference width obtained by adding adjustment widths (α, β) to the intensity difference ΔE detected by the detector 10. Specifically, when the extractor 12 acquires the intensity difference ΔE from the detector 10, it generates "ΔE - α < ΔE < ΔE + β" as the intensity difference width, and acquires cells corresponding to the generated intensity difference width. Here, the extractor 12 reduces the number of cells to be acquired by reducing the adjustment widths (α, β), and increases the number of cells to be acquired by increasing the adjustment widths (α, β). Note that the adjustment widths (α, β) may be the same value among all the antennas 5, or may be different values among the antennas 5.

[0035] Specifically, as shown on the left side of FIG. 10, as a result of the comparator 13 obtaining and comparing the cells corresponding to the intensity difference widths between "antenna 1" and "antenna 2" and the cells corresponding to the intensity difference widths between "antenna 1" and "antenna 3", when a plurality of cells are found to correspond, the extractor 12 narrows the intensity difference width. As a result, the cells corresponding to the intensity difference width between "antenna 1" and "antenna 2" and the cells corresponding to the intensity difference width between "antenna 1" and "antenna 3" are reduced. Then, the comparator 13 obtains and compares again the cells corresponding to the intensity difference width between "antenna 1" and "antenna 2" and the cells corresponding to the intensity difference width between "antenna 1" and "antenna 3", so that, as shown on the right side of FIG. 10, matching cells can be found.

[0036] Also, as shown on the left side of FIG. 11, as a result of the comparator 13 obtaining and comparing the cells corresponding to the intensity difference widths between "antenna 1" and "antenna 2" and the cells corresponding to the intensity difference widths between "antenna 1" and "antenna 3", when there are no matching cells, that is, when the cells do not match, the extractor 12 widens the intensity difference width. As a result, the cells corresponding to the intensity difference width between "antenna 1" and "antenna 2" and the cells corresponding to the intensity difference width between "antenna 1" and "antenna 3" increase. Then, the comparator 13 obtains and compares again the cells corresponding to the intensity difference width between "antenna 1" and "antenna 2" and the cells corresponding to the intensity difference width between "antenna 1" and "antenna 3", so that, as shown on the right side of FIG. 11, matching cells can be found.

[0037] [Embodiment 3] Next, referring to FIG. 12, Embodiment 3 will be described. In Embodiment 3, in order to avoid redundant descriptions, parts different from Embodiments 1 and 2 will be described, and parts having the same configuration as those in Embodiments 1 and 2 will be denoted by the same reference numerals and described. FIG. 12 is a cross-sectional view showing an example of the shape of the radome of the direction detection device according to Embodiment 3.

[0038] In the direction detection method of Embodiment 1, in the extractor 12, cells corresponding to the intensity differences detected by the detector 10 were extracted according to the combination of the two antennas 5. In this case, in the comparator 13, there are a plurality of matching cells, and it may not be possible to narrow them 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.

[0039] Therefore, in Embodiment 3, as shown in FIG. 12, the radome 6 of the direction detection device 1 has a configuration in which a material for changing the electrical characteristics is added. As the material for changing the electrical characteristics, for example, a good conductor such as a dielectric or a metal can be used. Hereinafter, a configuration in which a dielectric 31 is added 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. 12 may be arranged. In the radome 6a of FIG. 12, a 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. 12, the dielectric 31b has a block shape protruding from the inside of the radome 6a. In the radome 6c of FIG. 12, a dielectric 31c is provided following the inside of the radome 6c. 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. 12, a separate dielectric 32 is attached to the inside of the radome 6a. In the radome 6e of FIG. 12, a cap-shaped dielectric 33 covering the antenna 5 is attached.

[0040] Although not shown, 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 airframe outside the radome 6 may be used as a material for changing the electrical characteristics. That is, the airframe 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.

[0041] [Embodiment 4] Next, Embodiment 4 will be described. In Embodiment 4, to avoid redundant descriptions, the parts different from Embodiments 1 to 3 will be described, and for the parts having the same configuration as those in Embodiments 1 to 3, the same reference numerals will be used for description.

[0042] In Embodiment 1, the radome 6 of the direction detection device functioned as the intensity difference imparting unit. However, in Embodiment 4, 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.

[0043] [Embodiment 5] Next, with reference to FIGS. 13 and 14, Embodiment 5 will be described. In Embodiment 5, to avoid redundant descriptions, the parts different from Embodiments 1 to 4 will be described, and for the parts having the same configuration as those in Embodiments 1 to 4, the same reference numerals will be used for description. FIGS. 13 and 14 are schematic configuration diagrams showing examples of the arrangement of a plurality of antennas of the direction detection device according to Embodiment 4.

[0044] In Embodiment 1, the three antennas 5 are arranged side by side in the AZ direction. However, as shown in FIG. 13, they may be arranged with different heights in the EL direction. That is, the three antennas 5 may be arranged at three points. This is because in the direction detection method using the intensity difference table T, ambiguity is resolved by applying different intensity differences depending on the arrival direction of the received wave by the intensity difference applying unit, so there are no restrictions on the arrangement of the antennas 5. Also, as shown in FIG. 14, four antennas 5 may be arranged as a plurality of antennas 5. In this case, the distances between the antennas 5 may be unequal or equal. When arranging four antennas 5, three of them may be used as regular antennas 5 and one may be used as a spare antenna 5. By increasing the number of antennas 5, when it is difficult to narrow down the matching cells in the comparator 13, the number of combinations of antennas 5 can be increased, or the number of combinations using the spare antenna 5 can be increased.

[0045] Note that 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 T in which the intensity differences in each cell were obtained. However, the configuration is not particularly limited to this. For example, while deforming the radome 6 under load, the intensity differences in each cell may be obtained to generate the intensity difference table T, and using the generated intensity difference table T, the arrival direction of the received wave may be detected in consideration of the load deformation of the radome 6.

[0046] As described above, the direction detection device 1, the method for obtaining the intensity difference table T, the direction detection method, and the direction detection program described in the embodiments are understood as follows, for example.

[0047] The direction detection device 1 according to the first aspect is a direction detection device 1 that detects the arrival direction of a received wave, and includes a plurality of antennas 5 that receive the received wave, and a plurality of antennas 5 that receive the received wave. An intensity difference imparting unit (radome 6, dielectric 31, good conductor, antenna element having a spatially non-uniform gain) that imparts an intensity difference different depending on the arrival direction of the received wave to the received intensity of the received wave, and among the plurality of antennas 5, a storage unit 11 that stores an intensity difference table T associating the intensity difference between two of the antennas 5 with the arrival direction of the received wave for each combination of the two antennas 5, a detector 10 that detects the intensity difference between two of the antennas 5 based on the received wave received by the plurality of antennas 5, and from the intensity difference table T stored in the storage unit 11, an extractor 12 that extracts a plurality of arrival directions of the received wave corresponding to the intensity difference detected by the detector 10 according to the combination of the two antennas 5, and a comparator 13 that compares the arrival directions of the received wave corresponding to the plurality of intensity differences acquired from the extractor 12 and acquires the matching arrival direction of the received wave as a detection result.

[0048] 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 intensity difference table T, ambiguity can be removed and the three-dimensional arrival direction of the received wave can be suitably obtained.

[0049] As a second aspect, the intensity difference table T 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 12 is based on the frequency or polarization detected by the detector 10. The intensity difference table T corresponding to the frequency or polarization is acquired, and the arrival direction of the received wave corresponding to the intensity difference detected by the detector 10 is extracted from the acquired intensity difference table T.

[0050] According to this configuration, since the intensity difference table T can be obtained for each frequency or each polarization, an appropriate intensity difference corresponding to the frequency and polarization can be obtained, and the arrival direction of the received wave with high accuracy corresponding to the intensity difference can be extracted.

[0051] 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 a non-uniform structure in three-dimensional space.

[0052] According to this configuration, by making the shape of the radome 6 a non-uniform shape or a non-uniform structure in three-dimensional space, different intensity differences can be imparted depending on the arrival direction of the received wave.

[0053] 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.

[0054] According to this configuration, by providing a material that changes electrical characteristics in the radome 6, different intensity differences can be easily imparted depending on the arrival direction of the received wave.

[0055] 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.

[0056] According to this configuration, by making the gain of the element 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 element of the antenna 5 different for each element, different intensity differences can be easily imparted depending on the arrival direction of the received wave.

[0057] As a sixth aspect, the extractor 12 extracts the arrival direction of the received wave corresponding to the intensity difference width obtained by adding an 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 13 widens the adjustment width, while when there are a plurality of candidates for the arrival direction of the received wave that match, the comparator 13 narrows the adjustment width.

[0058] According to this configuration, by adjusting the adjustment width, it is possible to appropriately find the arrival direction of the received wave that matches.

[0059] 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 T has a plurality of cells associated with the AZ angle and the EL angle, and the intensity differences are respectively set in the plurality of cells, and the intensity differences between the cells are interpolated.

[0060] According to this configuration, since the intensity differences between the cells can be appropriately interpolated, the intensity differences can be accurately obtained, and the arrival direction of the received wave corresponding to the intensity differences can be appropriately obtained.

[0061] As an eighth aspect, when the intensity difference table T is prepared for each frequency or polarization of the received wave, the intensity difference table T has the intensity differences between the frequencies or the intensity differences between the polarizations interpolated.

[0062] According to this configuration, since the intensity differences between the frequencies and the intensity differences between the polarizations can be appropriately interpolated, the intensity differences between the frequencies and the intensity differences between the polarizations can be accurately obtained, and the arrival direction of the received wave corresponding to the intensity differences can be appropriately obtained.

[0063] The method for obtaining the intensity difference table T according to the ninth aspect is a method for obtaining the intensity difference table T used in the above-described direction detection device 1, 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 T that associates the intensity difference between two of the antennas 5 with the arrival direction of the received wave based on the intensity difference obtained by receiving the received wave.

[0064] According to this configuration, it is possible to obtain an intensity difference table T that appropriately associates the intensity difference with the arrival direction of the received wave.

[0065] The direction detection method according to the tenth aspect is a direction detection method for detecting the arrival direction of a received wave by the above-described direction detection device 1, and includes steps of receiving the received wave by a plurality of antennas 5 (step S1), detecting, by the detector 10, the intensity difference between two of the antennas 5 based on the received wave received by the plurality of antennas 5 (step S2), extracting, by the extractor 12, a plurality of arrival directions of the received wave corresponding to the intensity difference detected by the detector 10 from the intensity difference table T stored in the storage unit 11 according to combinations of two of the antennas 5 (steps S3 and S4), and comparing, by the comparator 13, the arrival directions of the received wave corresponding to the plurality of obtained intensity differences and obtaining, as a detection result, the arrival direction of the received wave that matches (step S5).

[0066] 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 intensity difference table T, ambiguity can be removed and the three-dimensional arrival direction of the received wave can be suitably obtained.

[0067] The direction detection program according to the 11th aspect is a direction detection program for detecting the arrival direction of a received wave, which is executed by the above-described direction detection device 1. The program includes steps S1 to S5 as follows: Step S1: A plurality of antennas 5 receive the received wave; Step S2: In the detector 10, based on the received waves received by the plurality of antennas 5, the intensity difference between two of the antennas 5 is detected; Step S3 and S4: In the extractor 12, according to the combination of two of the antennas 5, a plurality of arrival directions of the received wave corresponding to the intensity difference detected by the detector 10 are extracted from the intensity difference table T stored in the storage unit 11; Step S5: In the comparator 13, the arrival directions of the received waves corresponding to the plurality of acquired intensity differences are compared, and the matching arrival direction of the received wave is obtained as the detection result.

[0068] 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 intensity difference table T, ambiguity can be removed, and the three-dimensional arrival direction of the received wave can be suitably obtained.

Explanation of Signs

[0069] 1 Direction detection device 5 Antenna 6 Radome 10 Detector 11 Storage unit 12 Extractor 13 Comparator 21 Acquisition device 22 Transmitter 23 Receiver 24 Operation unit 25 Measuring device 31a~31c, 32, 33 Dielectric T Intensity difference table

Claims

1. In a direction detecting 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 with the arrival direction of the received wave; a detector that detects the intensity difference between two of the plurality of antennas based on the received wave received by the plurality of antennas; an extractor that extracts a plurality of arrival directions of the received wave corresponding to the intensity difference detected by the detector from the intensity difference table stored in the storage unit, according to the combination of the two antennas; a comparator that compares the arrival directions of the received wave corresponding to the plurality of intensity differences acquired from the extractor and acquires, as a detection result, the arrival direction of the received wave that matches; and the extractor extracts the arrival direction of the received wave corresponding to an intensity difference width obtained by imparting an adjustment width to the intensity difference detected by the detector, wherein when candidates for the arrival direction of the received wave corresponding to the plurality of intensity difference widths extracted according to the combination do not match, the comparator widens the adjustment width, and when there are a plurality of candidates for the arrival direction of the received wave that match, the comparator narrows the adjustment width. A direction detecting 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 detecting 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 detecting device according to claim 1 or 2.

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

5. The direction detection device according to any one of claims 1 to 4, wherein the intensity difference imparting unit has the antenna in which the gain of the 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 is The direction detection device according to any one of claims 1 to 5, having a plurality of cells associated with the AZ angle and the EL angle, and the intensity difference being set in each of the plurality of cells, and the intensity difference between the cells being interpolated.

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

8. A method for acquiring an intensity difference table for acquiring an intensity difference table used in the direction detection device according to any one of claims 1 to 7, Setting the received wave generated from the radio wave source to a predetermined arrival direction for a plurality of antennas; Generating the received wave from the radio wave source; Receiving the received wave by the plurality of antennas; Obtaining an intensity difference table associating the intensity difference between two of the antennas and the arrival direction of the received wave based on the intensity difference obtained by receiving the received wave. A method for acquiring an intensity difference table that executes the steps.

9. 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 7, Receiving the received wave by a plurality of antennas; Detecting, by the detector, an intensity difference between two of the antennas based on the received wave received by the plurality of antennas; In the extractor, extracting a plurality of arrival directions of the received wave corresponding to the intensity difference detected by the detector from the intensity difference table stored in the storage unit according to a combination of two of the antennas; In the comparator, comparing the arrival directions of the received wave corresponding to the plurality of acquired intensity differences, 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 intensity difference width obtained by adding an 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 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 adjustment width is widened, while when there are a plurality of candidates for the arrival direction of the received wave that match, the adjustment width is narrowed. A direction detection method.

10. 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 7, receiving the received wave by a plurality of antennas; in the detector, detecting the intensity difference between two of the antennas based on the received wave received by the plurality of antennas; in the extractor, extracting a plurality of arrival directions of the received wave corresponding to the intensity difference detected by the detector from the intensity difference table stored in the storage unit according to the combination of two of the antennas; in the comparator, comparing the arrival directions of the received wave corresponding to the plurality of obtained intensity differences, 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 intensity difference width obtained by adding an 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 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 adjustment width is widened, while when there are a plurality of candidates for the arrival direction of the received wave that match, the adjustment width is narrowed. A direction detection program for causing the above to be executed.

Images