JP2015136045A - Array antenna device and array antenna signal processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an array antenna device in which both load reduction of signal processing, and estimation of arrival direction or polarization are satisfied.SOLUTION: An array antenna device includes: a plurality of vector antennas; an output signal selecting section; and a signal processing section. The plurality of vector antennas are arranged in an array. Each vector antenna is constituted by selecting M (where, M is an integer of 3-6) antennas from three electric field receiving antennas spatially crossing each other at a predetermined angle, and three magnetic field receiving antennas spatially crossing each other at a predetermined angle. The output signal selecting section selects the output signals of (M-1) or less, where the correlation coefficients are a preset threshold or less, from the output signal of each vector antenna. The signal processing section performs array signal processing by using the output signals of (M-1) or less.

Description

  Embodiments described herein relate generally to an array antenna device and an array antenna signal processing method.

  The array antenna apparatus can be configured by arranging, for example, a plurality of vector antennas that combine an electric field receiving antenna and a magnetic field receiving antenna in an array.

  When estimating the arrival direction of an incoming wave, the direction of polarization, and the like, calculation using all the received signals from the antennas constituting the vector antenna increases the signal processing load. On the other hand, if the received signals of all the antennas are averaged to reduce the number of received signals, the polarization information is lost, making it difficult to estimate the polarization.

JP 2006-507752 gazette

  Embodiments of the present invention provide an array antenna apparatus and an array antenna signal processing method that can achieve both signal processing load reduction and estimation of the direction of incoming waves and the direction of polarization.

  The array antenna apparatus of the embodiment includes a plurality of vector antennas, an output signal selection unit, and a signal processing unit. The plurality of vector antennas are arranged in an array. Each vector antenna is composed of three electric field receiving antennas that intersect each other at a predetermined angle in space and three magnetic field receiving antennas that intersect each other at a predetermined angle in space (where M is an integer of 3 or more and 6 or less). It is configured by selecting more than one antenna. The output signal selection unit selects (M−1) or less output signals whose correlation coefficients are equal to or less than a preset threshold value from the output signals of the respective vector antennas. The signal processing unit performs array signal processing using the (M−1) or less output signals.

It is a block diagram of the array antenna apparatus concerning 1st Embodiment. 2A is a schematic perspective view of the vector antenna, FIG. 2B is its coordinate system, FIGS. 2C to 2E are schematic perspective views of the electric field receiving antenna, and FIGS. 2F to 2H. FIG. 2 is a schematic perspective view of a magnetic field receiving antenna. It is a flowchart showing the output signal selection part effect | action of the array antenna apparatus concerning 1st Embodiment. 4A to 4F are explanatory diagrams of reception patterns of Eθ polarized waves with respect to angles φ and θ. FIGS. 5A to 5F are explanatory diagrams of reception patterns of Eφ polarized waves with respect to angles φ and θ. It is a block diagram of the array antenna apparatus concerning a comparative example. FIGS. 7A to 7D are schematic perspective views of a vector antenna used in the array antenna apparatus according to the second embodiment. FIGS. 8A to 8D are schematic perspective views of a vector antenna used in the array antenna apparatus according to the third embodiment. It is a flowchart showing the effect | action of the output signal selection part of the array antenna apparatus concerning 6th Embodiment. It is a flowchart showing the effect | action of the output signal selection part of the array antenna apparatus concerning 7th Embodiment. It is a flowchart showing the effect | action of the output signal selection part of the array antenna apparatus concerning 8th Embodiment. It is a flowchart in the case of setting a noise power and a noise power threshold value beforehand corresponding to time and a frequency.

Each embodiment will be described below with reference to the drawings.
Note that the drawings are schematic or conceptual, and the size ratio between the parts is not necessarily the same as the actual one. Further, even when the same part is represented, the dimensions and ratios may be represented differently depending on the drawings.
Note that, in the present specification and each drawing, the same elements as those described above with reference to the previous drawings are denoted by the same reference numerals, and detailed description thereof is omitted as appropriate.

(First embodiment)
FIG. 1 is a configuration diagram of an array antenna apparatus according to the first embodiment.
The array antenna apparatus includes N vector antennas A _j (j = 1,..., N (positive integer)), an output signal selection unit 104, and a signal processing unit 105.

2A is a schematic perspective view of the vector antenna 301, FIG. 2B is its coordinate system, FIGS. 2C to 2E are schematic perspective views of the electric field receiving antenna, and FIGS. ) Is a schematic perspective view of a magnetic field receiving antenna.
Each vector antenna A _j (j = 1 to N) includes three spatially orthogonal electric field receiving antennas 302, 303, and 304 and three spatially orthogonal magnetic field receiving antennas 305, 306, and 307. It shall consist of elements. In the present specification, “perpendicular” means that the crossing angle is not less than 80 degrees and not more than 100 degrees.

  The electric field receiving antennas 302 to 304 are, for example, dipole antennas having a half wavelength, and the electric field receiving antenna 302 extending along the x axis and the electric field receiving antenna 303 extending along the y axis. And an electric field receiving antenna 304 extending along the z-axis. The shape is not limited to a dipole. For example, if the meander line shape or the helical shape is used, the antenna length can be shortened. Alternatively, in order to avoid contact of the three antennas, it is possible to deform such as partially bending the shape. The electric field receiving antenna may use an electric dipole. Further, the electric field receiving antennas 302, 303, and 304 may deviate from orthogonality, and the extending directions of the dipole antennas may intersect each other at a predetermined angle.

  The magnetic field receiving antennas 305 to 307 include a magnetic field receiving antenna 305 disposed in the xz plane, an electric field receiving antenna 306 disposed in the yz plane, and an electric field receiving antenna 307 disposed in the xy plane. 2 (f) to 2 (h) show a square loop antenna, a circular loop antenna or a multi-turn loop antenna may be used. The magnetic field receiving antennas 305 to 307 may use magnetic dipoles. Further, the magnetic field receiving antennas 305, 306, and 307 may deviate from orthogonality, and planes including loops may intersect each other at a predetermined angle.

  Moreover, magnetism can be received by the electric field receiving antennas 302 to 304. In this case, it is preferable to increase the reception sensitivity of the electric field as the ratio of the electric field to the magnetic field. Conversely, the magnetic field receiving antenna can receive the electric field. In this case, it is preferable to increase the reception sensitivity of the magnetic field as the ratio of the electric field to the magnetic field.

  Next, a method for discriminating which of the electric field reception sensitivity and the magnetic field reception sensitivity is higher will be described. In this case, the antenna may be considered as a transmission antenna, which will be described in other words as an electric field antenna and a magnetic field antenna. In an antenna including an electric field antenna and a magnetic field antenna, the ratio of the electric field amplitude to the magnetic field amplitude (electric field ÷ magnetic field) is 120π in a plane wave region far from the antenna. However, in the vicinity region where the distance from the antenna is short, the ratio of the electric field amplitude to the magnetic field amplitude is not 120π.

  In the case of an electric field receiving antenna, the ratio between the electric field amplitude and the magnetic field amplitude is larger than 120π. In the case of a magnetic field receiving antenna, the ratio between the electric field amplitude and the magnetic field amplitude is smaller than 120π. In this way, the electric field receiving antenna and the magnetic field receiving antenna can be distinguished from the ratio between the electric field amplitude and the magnetic field amplitude.

As shown in FIG. 1, the array antenna apparatus includes N (N ≧ 2) vector antennas _Aj . The number N can be selected according to the purpose of the array antenna apparatus. For example, if the number N is increased, the accuracy of array signal processing can be increased. On the other hand, when the number N is reduced, cost reduction and installation space reduction are facilitated.

  Further, the arrangement can be set to an arbitrary shape including a linear shape, a circular shape, a lattice shape, or the like in accordance with the arrival direction of the incoming wave. Moreover, a mutual space | interval may be arbitrary. For example, a technique may be used in which the interval is set to ½ or less of the wavelength of the incoming wave and the generation of virtual images is suppressed.

The output signal selection unit 104 selects only a predetermined number of output signals having a small correlation coefficient from the six output signals from the respective vector antennas A _j (j = 1 to N), and sends them to the signal processing unit 105. Output toward.

The signal processing unit 105 performs an operation using the selected output signal among the output signals from the vector antenna A _j (j = 1 to N), and estimates the arrival direction of the incoming wave, the polarization direction, and the like. . When the signal processing unit 105 includes an amplifier, a filter, an analog-digital converter, and the like (not shown), the high-frequency output signal from the vector antenna A _j (j = 1 to N) is digitized and digital signal processing is performed. Can do.

FIG. 3 is a flowchart showing the operation of the output signal selection unit of the array antenna apparatus according to the first embodiment.
In this figure, the case where the output signal selection unit 104 selects three output signals will be described. First, a combination for selecting three output signals from the six output signals of each vector antenna A _j (j = 1 to N) is set. The number of combinations is ₆ C ₃ = 20 (S100).

  Within each combination, there are three combinations for selecting two output signals from the three output signals. All correlation coefficients between the three are calculated (S102). The calculation formula of the correlation coefficient will be described in detail later.

  The maximum value among the three correlation coefficients calculated within each combination is set as the representative correlation coefficient (S104).

A combination with the smallest representative correlation coefficient is selected, and three output signals included in the selected combination are selected (S106). This selection is performed for all N vector antennas A _j (j = 1 to N).

In the first embodiment, the correlation coefficient can be calculated by the following method, for example. The output signals of the electric field receiving antennas 302 to 304 are represented by E1 (t), E2 (t), and E3 (t) as a function of time t. In addition, the output signal of the magnetic field antenna is represented by H1 (t), H2 (t), and H3 (t) as a function of time t. When the output signal is an analog signal, the correlation coefficient ρ _EiHj (i = 1, 2, 3, j = 1, 2, 3) can be expressed by Expression (1). These output signals correspond to the high frequency power received by the respective antennas, and can be represented by analog signals or digital signals.

The denominator in the absolute value symbol is for normalizing the maximum value of the correlation coefficient ρ _EiHj to 1.

When the output signal is a digital signal, the correlation coefficient ρ _EiHj (i = 1, 2, 3, j = 1, 2, 3) is obtained using T pieces of data sampled between times t1 and t2. And can be represented by the formula (2).

The denominator in the absolute value symbol is for normalizing the maximum value of the correlation coefficient ρ _EiHj to 1. Expressions (1) and (2) are expected value calculations by time average calculation.
Further, the correlation coefficient can also be calculated between the electric field antennas as expressed in Equation (3).

  If the output signals Eh (t) and Ek (t) of the electric field antenna in Expression (3) are replaced with the output signals Hh (t) and Hk (t) of the magnetic field antenna, the correlation coefficient between the magnetic field antennas can be calculated ( However, h = 1, 2, 3, k = 1, 2, 3).

  Further, when the output signal is a digital signal, the correlation coefficient can be expressed by Expression (4) between the electric field antennas. Similarly, the correlation coefficient between magnetic field antennas can be calculated.

  Next, it will be described that the signal processing load reduction and the polarization estimation can be both achieved by the first embodiment. (Table 1) represents an example of a function representing reception patterns of polarization Eθ and polarization Eφ from six antennas. The characteristics of the three electric field receiving antennas 302 to 304 are the same, and the arrangement directions are different. The characteristics of the three magnetic field receiving antennas 305 to 307 are the same, and the arrangement directions are different. ω represents the ratio of reception sensitivity between the electric field receiving antenna and the magnetic field receiving antenna.

  The ratio ω between the reception sensitivity of the electric field antenna and the reception sensitivity of the magnetic field antenna is 1. As shown in FIG. 2B, the range of the angle θ is 0 to 90 degrees, and the range of the angle φ is 0 to 360 degrees.

  4A to 4F are response diagrams of reception patterns of the polarization Eθ with respect to the angles φ and θ. Table 2 represents the absolute value of the correlation value between the two output signals with respect to the polarization Eθ.

  In the reception pattern of the output signal E1 of the electric field receiving antenna 302 shown in FIG. 4A, there is a null having no reception sensitivity at an angle of 90 degrees and an angle of 270 degrees.

  Also, the reception pattern of the output signal H1 of the magnetic field receiving antenna 305 shown in FIG. 4D has nulls at an angle of 90 degrees and an angle of 270 degrees. While the reception pattern of the output signal H1 does not change with respect to the angle θ, the reception pattern of the output signal E1 has a difference so as to become smaller near the angle of 90 degrees, but the output signal E1, the output signal H1, Has a high positive correlation (high correlation coefficient). In Table 2, the description “less than 1” indicates that the correlation coefficient is large. Thus, when the positive correlation is high, the correlation between the output signals received by the two antennas is also high. In other words, the correlation between the information included in the output signal E1 of the electric field receiving antenna 302 and the information included in the output signal H1 of the magnetic field receiving antenna 305 is high.

  When array signal processing is performed, all output signals with high correlation, such as the output signal E1 and the output signal H1, can be handled. However, from the viewpoint of the amount of information, the amount of information can be maintained by using one of the two output signals having a high correlation.

  Similarly, the reception pattern of the output signal E2 shown in FIG. 4B has nulls at angles 0, 180, and 360 degrees. As shown in FIG. 4E, the reception pattern of the output signal H2 also has nulls at angles of 0, 180, and 360 degrees. As described above, since the output signal E2 and the output signal H2 have opposite signs of the reception pattern response, the negative correlation is high, that is, one of the two output signals having a high negative correlation. If one is used, the amount of information can be maintained. In other combinations, the correlation coefficient is small. In Table 2, “0” indicates that the correlation coefficient is small.

  Further, since the reception pattern of the output signal H3 is not received, the output signal E3 is selected. Therefore, for the polarization Eθ, array signal processing may be performed using one of the output signals E1 and H1, one of the output signals E2 and H2, and the output signal E3.

  5A to 5F are response diagrams of reception patterns of the polarization Eφ with respect to the angles φ and θ. Table 3 shows the correlation of the output signal with respect to the polarization Eφ.

  In this figure, the ratio ω between the reception sensitivity of the electric field antenna and the reception sensitivity of the magnetic field antenna is 1. In the reception pattern of the output signal E1 of the electric field receiving antenna 1 shown in FIG. 5A, nulls having no reception sensitivity exist at angles of 0, 180, and 360 degrees.

  Also, the reception pattern of the output signal H1 shown in FIG. 5D has nulls at angles of 0, 180, and 360 degrees. That is, the output signals E1 and H1 have a high positive correlation. Thus, when the positive correlation is high, the correlation between the output signals received by the two antennas is also high. When performing array signal processing, all output signals with high correlation, such as the output signals E1 and H1, can be handled. However, from the viewpoint of the amount of information, the required amount of information can be maintained if one of the two output signals having high correlation is used.

  Similarly, the output signal E2 reception pattern shown in FIG. 5B has nulls at angles of 90 and 270 degrees. Further, as shown in FIG. 5E, the reception pattern of the output signal H2 also has nulls at angles of 90 and 270 degrees. Thus, the output signals E2 and H2 are opposite in sign of the reception pattern, and therefore have a high negative correlation (a large correlation coefficient).

  Note that the correlation is low in combinations other than the above. Further, since the reception pattern of the output signal E3 is not received, the output signal H3 is selected. Therefore, for the polarization Eφ, array signal processing may be performed using any one of the output signals E1 and H1, any one of the output signals E2 and H2, and the output signal H3.

  As described with reference to FIGS. 4 and 5, the correlation coefficient between the output signals can be estimated from the reception pattern. For this reason, if the reception pattern is known in advance, the correlation coefficient need not be calculated for two output signals that are not selected simultaneously.

  The incoming wave is generally obliquely polarized or elliptically polarized, and includes a polarization Eθ component and a polarization Eφ component. The reception pattern in this case is calculated by combining the reception pattern response shown in FIG. 4 and the reception pattern response shown in FIG. 5 according to the polarization state of the incoming wave.

  For example, consider a case where the polarization Eθ and the polarization Eφ are oblique 45-degree polarized waves having the same amplitude and the same phase. At this time, the response value is the value obtained by adding the response value of the polarization Eθ and the response value of the polarization Eφ and dividing by two. For example, for the electric field receiving antenna, since the response value of the polarization Eφ is zero, (−sin θ) / 2 is obtained. For the magnetic field receiving antenna, since the response of the polarization Eθ is zero, (sin θ) / 2 is obtained. However, ω = 1. The correlation coefficient between the reception pattern of the output signal E3 and the reception pattern of the output signal H3 is minus 1, and the absolute value of the correlation coefficient is large. For this reason, an output signal corresponding to one of the antennas may be used. In the oblique polarization, the remaining four antennas have a large correlation coefficient between the electric field receiving antenna 302 and the magnetic field receiving antenna 305, and a large correlation coefficient between the electric field receiving antenna 303 and the magnetic field receiving antenna 306.

In the first embodiment, the correlation coefficient ρ _EiHj between the output signals is calculated, and the amount of information included in the three output signals of the combination having the smallest correlation coefficient ρ _EiHj is stored in the three selected antennas. Will be included. The information amount of the three antennas is equivalent to the information amount of the six antennas. For this reason, in the array signal processing, polarization estimation and arrival direction estimation are possible, and estimation accuracy is maintained. Compared to performing array signal processing using six output signals from six antennas, the load of signal processing is reduced in the first embodiment using three output signals.

Note that the response of the reception pattern of the vector antenna A _j (j = 1 to N) may not be known. For example, if the installation environment changes due to the mutual coupling between antennas or the influence of a fixing device that fixes the antenna, the reception pattern becomes unknown. If the reception pattern can be measured after the array antenna device is installed, the measurement result can be used. However, when the wavelength is as long as several tens of meters to several kilometers, measurement becomes difficult. In this case, since an accurate reception pattern cannot be obtained, the output signal can be selected with high accuracy by directly calculating the correlation coefficient between the output signals.

FIG. 6 is a configuration diagram of an array antenna apparatus according to a comparative example.
The array antenna apparatus of the comparative example includes N vector antennas B _j (j = 1 to N) and an array signal processing unit 204, but does not include an output signal selection unit. Output signals from a plurality of antennas constituting each vector antenna B _j (j = 1 to N)) are directly input to the array signal processing unit 204 and subjected to signal processing. For this reason, the load of signal processing is not reduced.

(Second Embodiment)
FIGS. 7A to 7D are schematic perspective views of a vector antenna used in the array antenna apparatus according to the second embodiment. 7A is a schematic perspective view of a vector antenna 311 including three electric field receiving antennas, and FIGS. 7B to 7D are schematic perspective views of electric field receiving antennas 312, 313, and 314 constituting the vector antenna.

  4 and 5, the correlation between the reception pattern E1 of the electric field reception antenna and the reception pattern H1 of the magnetic field reception antenna is high. Further, the correlation between the reception pattern E2 of the electric field reception antenna and the reception pattern H2 of the magnetic field reception antenna is also high when an arbitrary polarization is assumed. For this reason, even if only the output signals from the electric field receiving antennas 312, 313, and 314 are selected, the necessary amount of information is maintained.

  Polarization estimation requires at least two output signals from two orthogonal receive antennas. There are three combinations for selecting two output signals from the three output signals. For these three combinations, a correlation coefficient between output signals may be calculated, and an output signal corresponding to the combination having the smallest correlation coefficient may be selected. Alternatively, a threshold value may be provided for the correlation coefficient in advance, and an output signal that is equal to or less than the threshold value may be selected. When the correlation coefficients are calculated in order, if a threshold is provided, it is not necessary to calculate all the correlation coefficients, and the calculation time can be shortened.

  According to the second embodiment, the number of data of the output signal is reduced. It is possible to simplify the configuration of the array antenna device, reduce the weight, reduce the cost, and reduce the calculation load of the array signal processing. Also, assuming a specific incoming wave, polarization output can be estimated because two orthogonal antenna output signals are used. In addition, when the frequency is in the GHz band, the vector antenna can be reduced in size by using only the electric field receiving antenna.

(Third embodiment)
FIGS. 8A to 8D are schematic perspective views of a vector antenna used in the array antenna apparatus according to the third embodiment. 8A is a schematic perspective view of a vector antenna 315 including three magnetic field receiving antennas, and FIGS. 8B to 8D are schematic perspective views of magnetic field receiving antennas constituting the vector antenna.

  As described in FIGS. 4 and 5, the correlation between the electric field receiving antenna and the magnetic field receiving antenna is high. For this reason, even if only the output signals from the magnetic field receiving antennas 316, 317, 318 are selected, the necessary amount of information is maintained. Polarization estimation requires at least two output signals from two orthogonal receive antennas. There are three combinations for selecting two output signals from three output signals.

  For these three combinations, a correlation coefficient between output signals may be calculated, and an output signal corresponding to the combination having the smallest correlation coefficient may be selected. Alternatively, a threshold value may be provided for the correlation coefficient in advance, and an output signal that is equal to or less than the threshold value may be selected. When the correlation coefficients are calculated in order, if a threshold is provided, it is not necessary to calculate all the correlation coefficients, and the calculation time can be shortened.

  In a frequency range of kHz to MHz, a loop antenna that is a magnetic field antenna may be used as used in leakage electromagnetic field strength measurement and the like. In this case, the magnetic field amplitude is larger than the electric field amplitude in the vicinity region where the distance from the antenna is short. For this reason, even if dielectrics such as trees and animals are nearby. There is an advantage that the characteristics hardly change.

  According to the third embodiment, it is possible to simplify the configuration of the array antenna device, reduce the weight, reduce the cost, and reduce the load of the array signal processing. In addition, when the wave source of noise generated from an electronic device or the like is an electric field antenna, the external noise has electric field properties. In particular, this phenomenon becomes stronger when the distance between the noise wave source and the antenna is short. When the reception antenna is a magnetic field antenna, the sensitivity to external noise having electric field characteristics can be reduced, and the influence of external noise can be reduced. Thus, either a magnetic field receiving antenna or an electric field receiving antenna can be selected depending on the use conditions.

(Fourth embodiment)
The array antenna apparatus according to the fourth embodiment includes a vector antenna Aj (j configured by selecting three antenna elements from three spatially orthogonal electric field receiving antennas and three spatially orthogonal magnetic field receiving antennas. = 1 to N). In each vector antenna, two output signals whose correlation coefficients are equal to or less than a preset threshold value are selected from the three output signals, and array signal processing is performed using the two selected output signals.

  In the fourth embodiment, the combination of the electric field receiving antenna and the magnetic field receiving antenna may be changed for each vector antenna. In this case, it becomes easier to select the receiving antenna in accordance with the installation space of the vector antenna that is restricted by the installation environment. When the angle range of the arrival direction is limited, it may be better to configure the vector antenna by combining the electric field receiving antenna and the magnetic field receiving antenna. According to the fourth embodiment, depending on the direction of arrival, the reception sensitivity can be increased by selecting both the electric field receiving antenna and the magnetic field receiving antenna.

(Fifth embodiment)
The array antenna apparatus according to the fifth embodiment is a vector antenna A _j configured by selecting four or more antennas from three spatially orthogonal electric field receiving antennas and three spatially orthogonal magnetic field receiving antennas. N (j is an integer greater than or equal to 2) (j = 1 to N). In each vector antenna A _j (j = 1 to N), three output signals whose correlation coefficient values are below a preset threshold value are selected from four or more output signals, and the two selected outputs Array signal processing is performed using the signal.

  The number of output signals of the array antenna apparatus according to the fifth embodiment is larger than the number of output signals (three) of the array antenna apparatus according to the fourth embodiment. Since the correlation coefficient between the selected output signals is small, the amount of information included in the output signal can be increased. As a result, the estimation accuracy of the direction of the incoming wave, the polarization, etc. can be improved.

(Sixth embodiment)
FIG. 9 is a flowchart showing the operation of the output signal selection unit of the array antenna apparatus according to the sixth embodiment.
In the sixth embodiment, the output signal selection unit 104 narrows down the output signal by calculating the reception pattern correlation coefficient ρ _PTN . In addition, although demonstrated as what selects three output signals from six output signals, this invention is not limited to this.

First, a reception pattern correlation coefficient ρ _PTN between antennas is calculated (S200). The reception pattern correlation coefficient ρ _PTN between the antennas can be expressed by, for example, Expression (5).

In equation (5), A _θ1 (Ω) represents the first antenna reception pattern of the polarization Eθ. A _θ2 represents the second antenna reception pattern of the polarization Eθ. A _φ1 represents the first antenna reception pattern of the polarization Eφ. A _φ2 represents the second antenna reception pattern of the polarization Eφ. The maximum value of the reception pattern correlation coefficient ρ _PTN represented in Expression (5) is 1 and the minimum value is 0. A _θ1 , A _θ2 , A _φ1 and A _φ2 are functions of the angles θ and φ.

Next, a threshold for the reception pattern correlation coefficient ρ _PTN is set (S202). The threshold value can be determined experimentally. For example, the relationship between the pattern correlation coefficient ρ _PTN and the arrival direction estimation accuracy is obtained in advance, and the threshold value can be determined from the pattern correlation coefficient ρ _{PTN in a} range that satisfies the required arrival direction estimation accuracy.

In this manner, a combination for selecting three output signals from the six output signals is determined under a condition that does not include an output signal whose reception pattern correlation coefficient ρ _PTN is equal to or greater than the threshold (S204). By step S204, the number of combinations in the subsequent steps can be reduced. For example, in the case of the reception pattern of FIG. 6 or FIG. 7, two ways of selecting one of the output signals E1 and H1, two ways of selecting one of the output signals E2 and H2, and two output signals E3 and H3. Since there are two ways to select one of these, a total of eight ways can be reduced. Since there are 20 ( ₆ C ₃ ) combinations for selecting three of the six output signals, a significant reduction is possible.

Next, a correlation coefficient ρ _EiHj (i = 1, 2, 3, j = 1, 2, 3) between output signals in each combination is calculated (S206). Next, the maximum value of the correlation coefficient ρ _EiHj in each combination is set as the representative correlation coefficient of each combination (S208). Next, three output signals included in the combination having the smallest representative correlation coefficient are selected (S210).

  According to the sixth embodiment, reception sensitivity depending on the arrival direction can be increased. In addition, the processing time can be shortened and the cost can be reduced.

(Seventh embodiment)
FIG. 10 is a flowchart showing the operation of the output signal selection unit of the array antenna apparatus according to the seventh embodiment.
In the seventh embodiment, the output signal selection unit 104 selects and narrows down the output signals by calculating the output power. In addition, although demonstrated as what selects three output signals from six output signals, this invention is not limited to this.

  First, the output power of the antenna element is calculated (S300). Next, a threshold for output power is set (S302). Note that the output power threshold value can be determined by performing preliminary measurement in advance depending on the conditions to be applied.

Next, the combination which selects three output signals from six output signals is set on the conditions which do not contain the antenna output signal from which output power becomes below a threshold value (S304). Next, a correlation coefficient ρ _EiHj between the output signals in each combination is calculated (S306).

Next, the maximum value of the correlation coefficient ρ _EiHj of each combination is set as the representative correlation coefficient of each combination (S308). Next, three output signals included in the combination with the smallest representative correlation coefficient are selected (S310).

  Since the electric field reception antenna and the magnetic field reception antenna are not omnidirectional, an angle range with low reception sensitivity is generated. Assuming that the incoming wave is in the direction of low reception sensitivity, the incoming wave power included in the output signal is reduced. In this case, the power of the output signal itself is also small.

The output signal always includes noise. For this reason, the information on the incoming wave included in the output signal may be buried in noise. Between the output signal from the antenna with low reception sensitivity and the output signal from the antenna element with high reception sensitivity, the correlation of noise is low, and the correlation function ρ _EiHj may be small regardless of the information of the incoming wave. is there. For this reason, when an output signal is selected only by the correlation coefficient ρ _EiHj of the output signal, there is a possibility that an antenna with low reception sensitivity is always selected.

  In the present embodiment, it is possible to select only an output signal that is equal to or higher than a preset output power threshold value, and to perform array signal processing with an output signal from an antenna with high reception sensitivity except for an antenna with low reception sensitivity with respect to an incoming wave. it can. For this reason, compared with the noise power included in the output signal, the ratio of the incoming wave power included in the output signal is improved, and the estimation accuracy of the array signal processing is improved.

(Eighth embodiment)
FIG. 11 is a flowchart showing the operation of the output signal selection unit of the array antenna apparatus according to the eighth embodiment.
In the eighth embodiment, the output signal selection unit 104 selects an output signal by calculating noise power. In addition, although demonstrated as what selects three output signals from six output signals, this invention is not limited to this.

  First, the noise power of each antenna is calculated (S400). Next, a threshold for noise power is set (S402).

Next, a combination for selecting three output signals from the six output signals is set under a condition that does not include an output signal whose noise power is equal to or greater than the threshold (S404). Next, a correlation coefficient ρ _EiHj between the output signals in each combination is calculated (S406).

Next, the maximum value of the correlation coefficient ρ _EiHj in each combination is set as the representative correlation coefficient of each combination (S408). Next, three output signals included in the combination having the smallest representative correlation coefficient are selected (S410).

  The noise included in the output power includes both thermal noise generated inside the array antenna device and external noise arriving at the antenna. External noise includes urban noise, which is unnecessary radiation from electronic equipment, and aerial noise using lightning as a wave source. These may not be negligible for the reception of weak incoming waves, even if they do not affect the communication of the form phone. Although the degree of influence varies depending on the installation location of the array antenna device and the observation frequency, it may not be ignored. When the external noise is strong, by removing the output signal with large noise power, the ratio of the incoming wave power contained in the output signal is improved compared to the noise power contained in the output signal, and the estimation accuracy of the array signal processing is improved. Is done.

  Note that noise power can be estimated in a state where an incoming wave is received. For example, the frequency spectrum of the output signal is calculated, and the noise power is estimated from this spectrum. When the frequency bandwidth of the incoming wave is limited such that the incoming wave is an unmodulated wave or an amplitude-modulated wave, the noise level can be estimated from the intensity of the frequency other than this frequency band.

FIG. 12 is a flowchart when the noise power and the noise power threshold are set in advance corresponding to time and frequency.
First, the noise power of each antenna element is set in advance corresponding to time and frequency (S500). Next, the noise power of each antenna element is set corresponding to the observation time and the observation frequency (S502).

  Next, a threshold for noise power is set in correspondence with the observation time and the observation frequency (S504). Next, a combination for selecting three output signals from the output signals is set to six under the condition that the antenna output signal whose noise power is equal to or greater than the threshold is not included (S506).

A correlation coefficient ρ _EiHj between the output signals in each combination is calculated (S508). Next, the maximum value of the correlation coefficient ρ _EiHj in each combination is set as the representative correlation coefficient of each combination (S510). Next, three output signals included in the combination having the smallest representative correlation coefficient are selected (S512).

  By limiting the selection of the output signal in this way, it is possible to select without using an output signal with a large noise power. As a result, the ratio of the incoming wave power included in the output signal is improved compared to the noise power included in the output signal, and the estimation accuracy of the array signal processing is improved. In addition, noise power may be difficult to estimate when the modulation scheme of the incoming wave is unknown, but it is possible to set the noise power and the noise power threshold even in this case.

  According to the first to eighth embodiments, an array antenna apparatus and an array antenna signal processing method capable of achieving both a reduction in signal processing load and estimation of an arrival direction and a polarization direction are provided. Furthermore, this embodiment facilitates antenna calibration, speeding up of the estimation algorithm, improvement of reception sensitivity, reduction of noise reception, miniaturization, weight reduction, and cost reduction of the antenna device. Furthermore, the present embodiment can also be applied to an array antenna apparatus that transmits information based on the estimated information. Communication performance can be further improved by selecting a transmission beam pattern and a transmission antenna in accordance with the direction of incoming waves and the direction of polarization. Such an array antenna device can be widely applied to radar devices and the like.

  Note that the present invention is not limited to the above-described embodiment, and can be embodied by modifying constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

  As mentioned above, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and the equivalents thereof. Further, the above-described embodiments can be implemented in combination with each other.

104 Output signal selection unit, 105 Signal processing unit, ₃₀₂ , ₃₀₃ , 304 Electric field reception antenna, 305, 306, 307 Magnetic field reception antenna, Aj (j = 1,..., N) Vector antenna, ρ _EiHi (output signal) Correlation coefficient, E1 (t), E2 (t), E3 (t) Electric field receiving antenna output signal, H1 (t), H2 (t), H3 (t) Magnetic field receiving antenna output signal, Eθ polarization, Eφ polarization Wave, ρ _PTN pattern correlation coefficient

Claims (15)

A plurality of vector antennas arranged in an array, each vector antenna comprising three electric field receiving antennas spatially intersecting each other at a predetermined angle and three magnetic field receiving antennas spatially intersecting each other at a predetermined angle A plurality of vector antennas configured by selecting M antennas (where M is an integer of 3 or more and 6 or less);
An output signal selection unit that selects (M−1) or less output signals whose correlation coefficient is equal to or less than a preset threshold value from the output signals of the respective vector antennas;
A signal processing unit that performs array signal processing using the (M-1) or less output signals;
Array antenna device equipped with A plurality of vector antennas arranged in an array, each vector antenna having three electric field receiving antennas spatially intersecting each other at a predetermined angle and three magnetic field receiving antennas spatially intersecting each other at a predetermined angle Including multiple vector antennas,
An output signal selection unit for selecting three output signals whose correlation is equal to or less than a preset threshold value from the output signals of the respective vector antennas;
A signal processing unit for performing an array processing signal using the three output signals;
Array antenna device equipped with A plurality of vector antennas arranged in an array, each vector antenna having three electric field receiving antennas spatially intersecting each other at a predetermined angle and three magnetic field receiving antennas spatially intersecting each other at a predetermined angle Including multiple vector antennas,
All combinations for selecting three output signals from the six output signals of the respective vector antennas are set, and a correlation coefficient between two output signals selected from the three output signals in all the combinations , And the maximum value of the calculated three correlation coefficients is set as the representative correlation coefficient of each combination, and the output for selecting the three output signals included in the combination having the minimum representative correlation coefficient is selected. A signal selector;
A signal processing unit that performs array signal processing using the three output signals included in the combination with which the representative correlation coefficient is minimized;
Array antenna device equipped with A plurality of vector antennas arranged in an array, each vector antenna being spatially intersecting with each other at a predetermined angle, or three magnetic field receiving antennas spatially intersecting with each other at a predetermined angle Including a plurality of vector antennas,
Three combinations in which two output signals are selected from the three output signals of each vector antenna are set, and the correlation coefficient between the two output signals in each combination is equal to or less than a preset threshold value. An output signal selector for selecting a combination;
A signal processing unit that performs array signal processing using two output signals included in the combination selected in each of the vector antennas;
Array antenna device equipped with   The array antenna apparatus according to claim 1, wherein the predetermined angle is approximately 90 degrees.   A pattern correlation coefficient is calculated in advance from a reception pattern between two output signals of the six output signals of the respective vector antennas, and becomes a pattern correlation coefficient equal to or greater than a preset pattern correlation coefficient threshold value. 2. The array antenna apparatus according to claim 1, wherein both of the two output signals are not selected simultaneously.   A pattern correlation coefficient is calculated in advance from a reception pattern between two output signals of the six output signals of the respective vector antennas, and becomes a pattern correlation coefficient equal to or greater than a preset pattern correlation coefficient threshold value. The array antenna apparatus according to claim 3, wherein a combination is not used.   The array antenna apparatus according to claim 1, wherein the output signal selection unit does not select an output signal having power equal to or less than a preset threshold value.   The array antenna apparatus according to claim 1, wherein the output signal selection unit does not select an output signal having noise power equal to or higher than a preset threshold value.   The array antenna apparatus according to claim 3, wherein the output signal selection unit does not select a combination including an output signal having noise power equal to or higher than a preset threshold value.   The array antenna apparatus according to claim 9 or 10, wherein the noise power is set in advance corresponding to time and frequency, and the noise power of the antenna element is set according to observation time and observation frequency.   The array antenna apparatus according to claim 9 or 10, wherein the threshold value of the noise power is set in advance corresponding to time and frequency, and the noise power threshold value of the antenna element is set according to an observation time and an observation frequency. An array antenna in which a plurality of vector antennas are arranged, each configured by selecting M antennas (M is an integer of 3 or more and 6 or less) from three electric field receiving antennas and three magnetic field receiving antennas. A signal processing method comprising:
A threshold value of a correlation coefficient of two output signals out of six output signals of each vector antenna is set in advance,
From the output signals of the respective vector antennas, select (M−1) or less output signals that are less than or equal to the threshold,
An array antenna signal processing method for performing array signal processing using the (M-1) or less output signals. An array antenna signal processing method in an antenna in which a plurality of vector antennas are arranged, each including three electric field receiving antennas and three magnetic field receiving antennas,
Set all combinations to select three output signals from each vector antenna,
In all the combinations, three correlation coefficients between two of the three output signals are calculated, and the calculated maximum value of the three correlation coefficients is used as the representative correlation coefficient of each combination. ,
Select three output signals included in the combination that minimizes the representative correlation coefficient,
An array antenna signal processing method for performing array signal processing using the three output signals included in the combination with which the representative correlation coefficient is minimized. An array antenna signal processing method in an antenna in which a plurality of vector antennas are arranged, each including three electric field receiving antennas or three magnetic field receiving antennas,
Set three combinations in which two output signals are selected from the three output signals of each vector antenna,
Pre-set a correlation coefficient threshold between the two output signals in each combination;
Select a combination in which the correlation coefficient in each combination is less than or equal to the threshold,
An array antenna signal processing method for performing array signal processing using two output signals included in the combination.

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