Antenna device and antenna

Abstract

To provide an antenna device that can function a spatial diversity even in an environment in which a channel correlation has spatial periodicity and is repeatedly high and low.SOLUTION: An antenna device 100 includes an antenna part 110 in which a plurality of antenna elements 111 including at least a first antenna element, a second antenna element, a third antenna element, and a fourth antenna element is disposed on an antenna substrate 112, a selection part 130, and a control part 120. In a relation among a first line in a first direction connecting a position of the first antenna element and a position of the second antenna element, a second line passing a position of the third antenna element in the first direction, and a third line passing the fourth antenna element in the first direction, the antenna element 111 is disposed on the antenna substrate 112 so that the longer one of a first distance between the first line and the second line and a second distance between the second line and the third line does not become an integral multiple of the shorter one.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to an antenna device and an antenna. [Background technology]

[0002] In wireless communication, when there are multiple transmission paths between communication devices, the channel correlation between multiple receiving antennas periodically goes up and down in response to the planar positional changes of the antenna elements. In such a communication environment, a fading phenomenon occurs in which the reception level frequently drops, and the transmission characteristics of wireless communication may be deteriorated. As one of the techniques for compensating for the deterioration of the transmission characteristics, a diversity technique has been proposed that obtains multiple reception waves with low correlation with each other, and combines or selects these reception waves to reduce the drop in the reception level.

[0003] Patent Document 1 discloses a diversity antenna device in which three omnidirectional antenna elements are arranged in an equilateral triangle at half-wavelength intervals. The diversity antenna device disclosed in Patent Document 1 splits the excitation signal from each antenna element into two, and combines the signals between the antenna elements in opposite phases using a combiner. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2000-278193 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the diversity antenna device disclosed in Patent Document 1, in an environment exhibiting spatially periodic channel correlation characteristics, channel correlation may become high for all antennas, and the effect of spatial diversity may not be achieved.

[0006] The present invention has been made in consideration of the problems inherent in the conventional techniques, and an object of the present invention is to provide an antenna device capable of achieving spatial diversity even in an environment in which channel correlation has spatial periodicity and repeatedly goes high and low. [Means for solving the problem]

[0007] An antenna device according to an embodiment of the present invention comprises an antenna section in which a plurality of antenna elements including at least a first antenna element, a second antenna element, a third antenna element, and a fourth antenna element are arranged on an antenna substrate, a selection section that selects the antenna elements provided in the antenna section, and a control section that controls the selection section, and in which the antenna elements are arranged on the antenna substrate such that, in a relationship between a first straight line in a first direction connecting the position of the first antenna element and the position of the second antenna element, a second straight line passing through the position of the third antenna element in the first direction, and a third straight line passing through the fourth antenna element in the first direction, the first distance between the first straight line and the second straight line and the second distance between the second straight line and the third straight line, the longer of the first distance and the second distance is not an integer multiple of the shorter distance.

[0008] An antenna according to another aspect of the present invention is an antenna in which a plurality of antenna elements including at least a first antenna element, a second antenna element, a third antenna element, and a fourth antenna element are arranged on an antenna substrate, and the antenna elements are arranged on the antenna substrate such that, in a relationship between a first straight line in a first direction connecting the position of the first antenna element and the position of the second antenna element, a second straight line passing through the position of the third antenna element in the first direction, and a third straight line passing through the fourth antenna element in the first direction, the first distance between the first straight line and the second straight line and the second distance between the second straight line and the third straight line, the longer of the first distance and the second distance is not an integer multiple of the shorter distance. Effect of the Invention

[0009] According to the present invention, it is possible to provide an antenna device capable of achieving spatial diversity even in an environment in which channel correlation has spatial periodicity and repeatedly goes high and low. [Brief description of the drawings]

[0010] [Figure 1] 1 is a diagram illustrating an example of a communication system in which an antenna device according to an embodiment of the present invention is used. [Diagram 2] 1A and 1B are diagrams for explaining the correlation between the position of an antenna element and a frequency response. [Diagram 3] 3 is a diagram for explaining the tendency of frequency response in the communication path shown in FIG. 1 and FIG. 2. FIG. [Figure 4A] 11 is a diagram showing another example of a communication system in which the antenna device according to the present embodiment is used. [Figure 4B] 1A and 1B are diagrams for explaining the correlation between the position of an antenna element and a frequency response. [Diagram 5] 1 is a schematic diagram showing a basic configuration of an antenna device according to an embodiment of the present invention. [Figure 6A] 3 is a schematic diagram for explaining the positional relationship of antenna elements in the antenna section in the present embodiment. FIG. [Figure 6B] 6B is a diagram for explaining channel correlation in the case where the antenna elements have the positional relationship shown in FIG. 6A. FIG. [Figure 7A] 11 is a diagram showing an example in which the period of channel correlation in this embodiment is equal to distance D2. FIG. [Figure 7B] 11 is a diagram showing an example in which the period of channel correlation in this embodiment is equal to distance D1. FIG. [Figure 8A] 10A and 10B are diagrams for explaining regions with high channel correlation in the present embodiment. [Figure 8B] 10A and 10B are diagrams for explaining regions with high channel correlation in the present embodiment. [Figure 8C] 10A and 10B are diagrams for explaining regions with high channel correlation in the present embodiment. [Figure 8D]10A and 10B are diagrams for explaining regions with high channel correlation in the present embodiment. [Figure 9] 10A and 10B are diagrams illustrating another example for explaining the positional relationship of antenna elements in the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The antenna device 100 according to this embodiment will be described in detail below with reference to the drawings. Note that the dimensional ratios in the drawings are exaggerated for the sake of explanation and may differ from the actual ratios. In addition, in the following description of the drawings, the same or similar parts are denoted by the same or similar reference symbols.

[0012] (Relationship between antenna position and correlation value) FIG. 1 shows an example of a communication system 10 in which an antenna device 100 according to this embodiment is used. In the example shown in FIG. 1, a transmitting antenna device 100a and a receiving antenna device 100b are mounted on a vehicle of the communication system 10 as the antenna device 100. The transmitting antenna device 100a is, for example, a switch or a sensor attached to the roof of the vehicle. The receiving antenna device 100b is, for example, an ECU (Electronic Control Unit) attached to the vehicle. In the example shown in FIG. 1, for example, information related to a switch or a sensor on the roof acquired by the transmitting antenna device 100a is transmitted to an ECU including the receiving antenna device 100b. Hereinafter, when it is not necessary to distinguish between the transmitting antenna device 100a and the receiving antenna device 100b, they will be simply referred to as "antenna device 100".

[0013] FIG. 2 shows correlation values ​​of frequency responses of communication paths measured while moving the position of the antenna at the position of the transmitting side antenna device 100a in FIG.

[0014] In the example shown in Fig. 2, the correlation value increases as the shading in the grayscale area increases. In Fig. 2, the frequency response is measured from 60 GHz to 62.56 GHz with a resolution of 10 MHz. Fig. 2 also shows the correlation value with the frequency response measured at the center of the measurement range by moving the transmitting antenna device 100a in a range of 30 mm in the left-right direction X and 30 mm in the front-back direction Y at the TX position of the vehicle in Fig. 1 in 1 mm increments.

[0015] In Figure 2, there are periodic band-shaped areas with high correlation values ​​from the rear left to the front right (from the bottom left to the top right on the paper of Figure 2). The wavelength of 60 GHz radio waves is approximately 5 mm, but because the areas with high correlation values ​​are band-shaped, the correlation value cannot be lowered even if the antenna is moved several wavelengths in the longitudinal direction of the band. In other words, no diversity effect can be obtained even if multiple antennas are placed on a line in the longitudinal direction of this band.

[0016] In addition, in the example shown in Fig. 2, the correlation value periodically becomes high, so even if the antennas are arranged in the short direction of the band, a diversity effect is not necessarily obtained. For example, points P1 and P2 shown in Fig. 2 are both in areas with high correlation values, and the relationship between the positions of points P1 and P2 makes it impossible to obtain a diversity effect.

[0017] Fig. 3 is a graph showing the relationship between frequency and power indicating the value of frequency response at points P1, P2, and P3 shown in Fig. 2. Specifically, Fig. 3 shows the frequency response of the communication channel at points P1, P2, and P3 at positions (0,15), (-2,4), and (-12,15) in the (X,Y) coordinates of Fig. 2.

[0018] As shown in FIG. 3, the frequency response trends of points P1 and P2 are similar, and sufficient diversity effect cannot be obtained even if antennas are placed at these two points. On the other hand, the frequency response trends of points P1 and P3 are different, and diversity effect can be expected if antennas are placed at these two points. For example, in the rectangular area shown by the dashed line between the frequencies of 60.5 GHZ to 61.0 GHz and between 62.0 GHz and 62.5 GHz in FIG. 3, the power drop is -55 dBm at points P1 and P2, which have high channel correlation. On the other hand, at point P3, which has low channel correlation with point P1, power of -50 dBm or more is obtained. That is, by using the antenna at the position of point P3, which has low channel correlation with point P1, in the antennas in FIG. 1 and FIG. 2, the signal power can be increased by 5 dBm or more, and communication quality can be improved.

[0019] The tendency of spatial distribution of correlation values ​​depends on the arrangement of antennas of the transmitter and receiver. Figures 4A and 4B show correlation values ​​of frequency responses when the transmitting antenna device 100a is arranged at a position different from that of Figures 1 and 2. In the example shown in Figure 4A, the transmitting antenna device 100a is, for example, a door switch or a sensor. Similarly to the example shown in Figure 1, the receiving antenna device 100b shown in Figure 4A is an ECU (Electronic Control Unit) installed in a vehicle. In the example shown in Figure 4A, for example, information related to a door switch or a sensor acquired by the transmitting antenna device 100a is transmitted to an ECU equipped with the receiving antenna device 100b.

[0020] In the graph showing the correlation values ​​of the frequency response in FIG. 4B, from left to right, regions with high correlation values ​​appear in a shorter period than in FIG. 2. In other words, in order to reduce the channel correlation between antennas, it is necessary to use antennas arranged differently from those in FIG. 1 and FIG. 2. However, the spatial distribution of the correlation values ​​is an interference pattern caused by the direct wave and the reflected, diffracted, and / or scattered waves strengthening or weakening each other, like the height pattern seen in the two-wave model of direct waves and ground reflection. The period of the interference pattern varies in the range of about 1 / 2 wavelength to several times the wavelength depending on the positional relationship between the transmitter / receiver and the object that causes reflection, diffraction, and / or scattering. If the object that causes reflection, diffraction, and / or scattering is displaced, the spatial distribution of the correlation values ​​also changes, and as a result, there is a possibility that all antennas will be located in a region with high correlation values. Objects that cause reflection, diffraction, and / or scattering can be not only fixed structures such as walls and the ground, but also displaceable objects such as openable and closable doors, sliding seats, and human bodies. Therefore, even if the position of the transmitter / receiver is fixed, the optimal antenna arrangement cannot be determined.

[0021] In addition, the probability that an antenna with low channel correlation exists can be increased by arranging a large number of antennas. However, when a large number of antennas are arranged regularly at regular intervals in a square or parallelogram lattice, even if the number of antenna elements is increased, all antennas may be located in an area with high channel correlation. In other words, when the number of antennas to be arranged is increased in order to ensure that an antenna with low channel correlation exists, it is not possible to ensure that an antenna with low channel correlation exists, and furthermore, this leads to an increase in the circuit size, power consumption, and / or cost of the antenna device.

[0022] As described above, in an environment where channel correlation periodically goes high and low with respect to changes in planar position, the conventional regular antenna arrangement may not provide a spatial diversity effect.

[0023] In this embodiment, the above problem is solved by arranging the antennas so that at least one antenna can obtain a different frequency response even when the channel correlation periodically changes. Specifically, for the positions of the four antenna elements 111, a straight line L1 is defined that connects the positions of two antenna elements 111a and 111b. In addition, two straight lines L2 and L3 are defined that are parallel to the straight line L1 and pass through the other two antenna elements 111c and 111d, respectively. The antenna elements 111 are arranged so that the longer distance D1 between the straight line L1 and the straight line L2 and the shorter distance D3 between the straight line L2 and the straight line L3 are not multiples of the shorter distance.

[0024] (Configuration example of antenna device 100) Fig. 5 is a schematic diagram showing a basic configuration of an antenna device 100 according to this embodiment. As shown in Fig. 5, the antenna device 100 according to this embodiment includes an antenna section 110, a control section 120, and a selection section 130. The antenna device 100 may also include a switching section 140. Details of the antenna section 110 will be described later.

[0025] The control unit 120 controls the selection unit 130. The control unit 120 may also control the switching unit 140. Specifically, the control unit 120 is connected to an external wireless IC (not shown), and controls the selection unit 130 and / or the switching unit 140 based on a control signal from the outside. The control unit 120 also outputs the control result, etc. to the outside.

[0026] Furthermore, the control unit 120 may be configured as, for example, a general-purpose microcomputer. In this case, a computer program for causing the microcomputer to function as the antenna device 100 may be installed in the microcomputer. By executing the computer program, the microcomputer functions as a plurality of information processing circuits provided in the antenna device 100. Furthermore, the control unit 120 may realize the plurality of information processing circuits provided in the antenna device 100 by software, or it is also possible to prepare dedicated hardware to configure the information processing circuits. Furthermore, the plurality of information processing circuits may be configured by individual hardware.

[0027] The selection unit 130 selects the antenna element 111 provided in the antenna unit 110. Specifically, the selection unit 130 selects the antenna element 111 with a low correlation value in response to control from the control unit 120, thereby realizing a diversity effect. That is, the above-mentioned control unit 120 controls the selection unit 130 to select at least one antenna element 111 located at a position where the channel correlation is low among the antenna elements 111. The control unit 120 may also detect the level of channel correlation based on the signal level from the antenna element 111, and control the selection unit 130 to select at least one antenna element 111 located at a position where the channel correlation is low based on the detection result. The control unit 120 may also control the selection unit 130 to select at least one antenna element 111 located at a position where the channel correlation is low based on a control signal input from the outside.

[0028] Furthermore, when the antenna device 100 is the transmitting antenna device 100a, the selection unit 130 may have a function of distributing signals to the selected antenna elements 111. Furthermore, when the antenna device 100 is the receiving antenna device 100b, the selection unit 130 may have a function of combining signals from the selected antenna elements 111.

[0029] The switching unit 140 switches between transmitting and receiving a signal via the antenna unit 110. Specifically, the switching unit 140 switches, in response to control from the control unit 120, between configuring the antenna device 100 as a transmitting-side antenna device 100a and configuring the antenna device 100b as a receiving-side antenna device.

[0030] As shown in FIG. 5, the antenna unit 110 in this embodiment is a planar patch antenna in which a plurality of antenna elements 111 (antenna elements 111a, 111b, 111c, and 111d, see FIG. 6A) are arranged on an antenna substrate 112. Hereinafter, when there is no need to distinguish between the antenna elements 111a, 111b, 111c, and 111d, they will be simply referred to as "antenna element 111." The antenna element 111a corresponds to the first antenna element. The antenna element 111b corresponds to the second antenna element. The antenna element 111c corresponds to the third antenna element. Furthermore, the antenna element 111d corresponds to the fourth antenna element.

[0031] Fig. 6A is a diagram showing the positional relationship of antenna elements 111 in antenna unit 110. As shown in Fig. 6A, antenna elements 111a and 111b are arranged on a straight line L1. This straight line L1 corresponds to a first straight line.

[0032] Moreover, the antenna element 111c is disposed on a straight line L2 parallel to the straight line L1. Furthermore, the antenna element 111d is disposed on a straight line L3 parallel to the straight line L1. That is, the straight lines L1, L2, and L3 are in a parallel positional relationship. The straight line L2 corresponds to the second straight line. Moreover, the straight line L3 corresponds to the third straight line.

[0033] The distance between the straight lines L1 and L2 is defined as D1, and the distance between the straight lines L2 and L3 is defined as D2. The distance D1 corresponds to the first distance. The distance D2 corresponds to the second distance.

[0034] 6A, the direction connecting the position of antenna element 111a and the position of antenna element 111b corresponds to the X-axis direction. In this embodiment, the X-axis direction corresponds to the first direction.

[0035] Here, a case where the longer distance is an integer multiple of the shorter distance in the relationship between distances D1 and D2 will be shown with reference to FIG. 6B. FIG. 6B shows an example where the longer distance D1 is twice the shorter distance D2. Also, in FIG. 6B, the locations shown with diagonal lines parallel to the lines L1 to L3 indicate locations with high channel correlation. That is, in the example shown in FIG. 6B, all of the antenna elements 111 are located on the diagonal lines with high channel correlation. Therefore, the diversity effect is not achieved with the antenna elements 111 in the positional relationship shown in FIG. 6B.

[0036] Next, an example will be described in which, in the relationship between distance D1 and distance D2 in this embodiment, the longer distance is not an integer multiple of the shorter distance.

[0037] 7A and 7B show an example in which the longer distance D1 is 2.5 times the shorter distance D2. That is, in the relationship between the distances D1 and D2, the longer distance is not an integer multiple of the shorter distance in FIG. 7A and 7B.

[0038] In the example shown in Fig. 7A, the straight lines L2 and L3 passing through the antenna elements 111c and 111d are shown as diagonal patterns with high channel correlation. In this case, it can be seen that the straight line L1 passing through the antenna elements 111a and 111b is located (in the middle) between the diagonal patterns with high channel correlation. That is, in the example shown in Fig. 7A, the antenna elements 111a and 111b can be arranged in an area where the channel correlation is likely to be the lowest, and further reduction in channel correlation can be expected.

[0039] In addition, in the example shown in Fig. 7B, the straight line L1 passing through the antenna elements 111a and 111b and the straight line L2 passing through the antenna element 111c are shown with a diagonal line pattern with high channel correlation. In this case, it can be seen that the straight line L3 passing through the antenna element 111d is located between the diagonal line patterns with high channel correlation. That is, in the example shown in Fig. 7B, the antenna element 111d can be arranged in an area where the channel correlation is likely to be low, and a reduction in channel correlation can be expected.

[0040] In addition, when the coordinates of the antenna element 111a, the antenna element 111b, the antenna element 111c, and the antenna element 111d are (X1, Y1), (X2, Y2), (X3, Y3), and (X4, Y4), respectively, the coordinate values ​​may be given as follows. For example, the coordinates may be (X1, Y1) = (0, 0), (X2, Y2) = (r, 0), (X3, Y3) = (1.4r, r), and (X4, Y4) = (0, 1.4r), respectively. Here, r is a scale factor, and is a constant that is 1 / 2 to several times the wavelength of the target frequency. Even when the antenna element 111 is in such a positional relationship, the relationship of distance D1 = 2.5 × distance D2 is established.

[0041] 8A to 8D are diagrams showing the relationship with regions of high channel correlation in coordinates using the above-mentioned scale factor r. That is, the coordinates of each of the antenna elements 111a to 111d in Fig. 8A to 8D are (X1, Y1) = (0, 0), (X2, Y2) = (r, 0), (X3, Y3) = (1.4r, r), and (X4, Y4) = (0, 1.4r). Also, on the drawings of Fig. 8A to 8D, each of the antenna elements 111a to 111d is represented by antenna V1 to antenna V4.

[0042] In the example shown in FIGS. 8A to 8D, the straight line connecting antennas V1 and V4 extends in the Y-axis direction. The Y-axis direction corresponds to the second direction. The straight line connecting antennas V1 and V4 corresponds to the fourth line. Straight lines parallel to the fourth line and passing through antennas V2 and V3 correspond to the fifth line and the sixth line, respectively. The distance between the fourth line and the fifth line corresponds to the third distance. The distance between the fifth line and the sixth line corresponds to the fourth distance.

[0043] That is, in the example shown in FIGS. 8A to 8D, the antenna element 111 is disposed on the antenna substrate 112 such that the distance D1 is not an integer multiple of the distance D2, and the third distance is not an integer multiple of the fourth distance.

[0044] Fig. 8A shows an example in which the region with high channel correlation extends in the X-axis direction and exists periodically in the Y-axis direction. In the example of Fig. 8A, three antenna elements 111, namely, antenna V1, antenna V2, and antenna V3, are located in the region with high channel correlation. On the other hand, antenna V4 is not located in the region with high channel correlation, and this antenna V4 can reduce the channel correlation.

[0045] Also, Fig. 8B shows an example in which the region with high channel correlation extends in the Y-axis direction and exists periodically in the X-axis direction. In the example of Fig. 8B, three antenna elements 111, namely, antenna V1, antenna V2, and antenna V4, are located in the region with high channel correlation. On the other hand, antenna V3 is not located in the region with high channel correlation, and this antenna V3 can reduce the channel correlation.

[0046] Also, Fig. 8C shows an example in which the regions of high channel correlation extend in the X-axis direction and exist periodically in the Y-axis direction, and the intervals between the regions of high channel correlation are narrower than those shown in the example of Fig. 8A. In the example of Fig. 8C, two antenna elements 111 of antennas V3 and V4 are located in the regions of high channel correlation. On the other hand, antennas V1 and V2 are not located in the regions of high channel correlation, and the channel correlation can be reduced by these antennas V1 and V2.

[0047] Furthermore, Fig. 8D shows an example in which the regions of high channel correlation extend in the Y-axis direction and exist periodically in the X-axis direction, and the intervals between the regions of high channel correlation are narrower than those shown in the example of Fig. 8B. In the example of Fig. 8D, two antenna elements 111, antenna V2 and antenna V3, are located in the regions of high channel correlation. On the other hand, antennas V1 and V4 are not located in the regions of high channel correlation, and the antennas V1 and V4 can reduce the channel correlation.

[0048] In the example shown in Fig. 8A to Fig. 8D, the positional relationship of antennas V1 to V4 is (X1, Y1) = (0, 0), (X2, Y2) = (r, 0), (X3, Y3) = (1.4r, r), and (X4, Y4) = (0, 1.4r). However, this configuration does not limit the embodiment. For example, the positional relationship of antennas V1 to V4 may be set to be optimal depending on the size of the area of ​​antenna unit 110.

[0049] For example, when it is desired to reduce the area of ​​the antenna unit 110, the positional relationship of antennas V1 to V4 may be (X1, Y1) = (0, 0), (X2, Y2) = (r, 0), (X3, Y3) = (1.3r, r), and (X4, Y4) = (0, 1.3r). Even in this case, a relationship can be realized between distances D1 and D2 in which the longer distance is not an integer multiple of the shorter distance.

[0050] Furthermore, when it is expected that channel correlation will decrease by separating the antenna elements 111, the positional relationships may be (X1, Y1) = (0, 0), (X2, Y2) = (r, 0), (X3, Y3) = (1.6r, r), and (X4, Y4) = (0, 1.6r). Even in this case, a relationship can be realized between the distances D1 and D2 in which the longer distance is not an integer multiple of the shorter distance.

[0051] As described above, the antenna device 100 in this embodiment includes an antenna section 110 in which a plurality of antenna elements 111 including at least a first antenna element, a second antenna element, a third antenna element, and a fourth antenna element are arranged on an antenna substrate 112. The antenna device 100 also includes a selection section 130 that selects the antenna element 111 provided in the antenna section 110, and a control section 120 that controls the selection section 130. A first straight line in a first direction that connects the position of the first antenna element and the position of the second antenna element is determined. A second straight line that passes through the position of the third antenna element in the first direction is determined. Furthermore, a third straight line that passes through the fourth antenna element in the first direction is determined. The antenna element 111 is arranged on the antenna substrate 112 such that the longer of the first distance and the second distance is not an integer multiple of the shorter distance with respect to the first distance between the first straight line and the second straight line and the second distance between the second straight line and the third straight line.

[0052] As a result, the antenna device 100 in this embodiment can realize the antenna section 110 including the antenna element 111 with low channel correlation. Therefore, the antenna device 100 can achieve spatial diversity even in an environment where the channel correlation has spatial periodicity and repeats highs and lows.

[0053] In addition, in the antenna device 100, a fourth line in the second direction is defined that connects the position of the first antenna element and the position of the fourth antenna element. A fifth line is defined in the second direction that passes through the position of the second antenna element. Furthermore, a sixth line is defined in the second direction that passes through the third antenna element. The antenna element 111 is disposed on the antenna substrate 112 such that the longer of the third distance and the fourth distance is not an integer multiple of the shorter of the third distance and the fourth distance, with respect to a third distance between the fourth line and the fifth line and a fourth distance between the fifth line and the sixth line.

[0054] As a result, the antenna device 100 in this embodiment can realize the antenna section 110 including the antenna element 111 with low channel correlation even in the second direction different from the first direction. Therefore, the antenna device 100 can make the spatial diversity function more appropriately even in an environment where the channel correlation has spatial periodicity and repeats highs and lows.

[0055] Furthermore, the control unit 120 controls the selection unit 130 to select at least one antenna element 111 located at a position where channel correlation is low from among the antenna elements 111. This makes it possible to include antenna elements 111 with low channel correlation in the antenna elements 111 selected by the selection unit 130, thereby enabling spatial diversity to function.

[0056] Furthermore, the antenna device 100 further includes a switching unit 140 that switches between transmitting and receiving a signal via the antenna unit 110. This allows the antenna device 100 to function as a transmitting-side antenna device 100a or a receiving-side antenna device 100b depending on the installation location and usage environment, allowing for more flexible application in the communication system 10 to which the antenna device 100 is applied. Also, it allows the antenna device 100 to be installed on both the transmitting side and the receiving side, allowing spatial diversity to function more appropriately.

[0057] Furthermore, since the antenna device 100 in this embodiment can utilize spatial diversity without relying on directional diversity, it is possible to obtain the diversity effect even in millimeter wave radio, in which the number of propagation paths of radio waves between transmitters and receivers is reduced due to high directivity and large distance attenuation.

[0058] In the above embodiment, an example has been shown in which the antenna unit 110 is configured with four antenna elements 111. As described above, in this embodiment, highly accurate directivity control using a large-scale antenna is not required, and even a small-scale device can achieve the effect of spatial diversity.

[0059] (Other embodiments) Although the embodiments have been described in detail with reference to the drawings, the present embodiments are not limited to the contents described in the above embodiments. The components described above include those that a person skilled in the art can easily imagine and those that are substantially the same. Furthermore, the configurations described above can be appropriately combined. Various omissions, substitutions, or modifications of the configurations can be made without departing from the spirit of the embodiments.

[0060] In the above embodiment, an example in which the antenna elements 111 are arranged at the vertices of a rectangle has been shown, but the embodiment is not limited to this configuration. For example, the antenna elements 111 may be arranged at the vertices of a triangle and at the orthocenter. That is, it is sufficient that the distance between a line connecting two antenna elements and a line parallel to the line passing through the other two antenna elements is not an integer multiple. FIG. 9 shows an example in which antenna elements are arranged at the vertices of an arbitrary triangle and at the orthocenter of the triangle. For example, in the example shown in FIG. 9, the positions of the four antenna elements are as follows. The coordinates of V1 are (X1, Y1) = (0, 5r). The coordinates of V2 are (X2, Y2) = (-15r / √7, 0). The coordinates of V3 are (X3, Y3) = (√7r, 0). Furthermore, the coordinates of V4 are (X4, Y4) = (0, 3r). This makes it possible to reduce channel correlation by the same principle as in the above embodiment. The arrangement of antenna elements 111 is not limited to the arrangement of antenna elements 111 at the vertices and orthocenter of a triangle. For example, the positions of antenna elements 111 may be arranged at the vertices and centroid, incenter, circumcenter, or eccenter of a triangle. Even in this case, the diversity effect can be obtained by not having an integer multiple relationship between the distance between a line connecting two antenna elements and a line parallel to the line connecting two antenna elements and passing through the other two antenna elements.

[0061] Also, an antenna device may be realized by partially applying the antenna section 110 according to the above-mentioned embodiment. For example, an array antenna section arranged in a lattice pattern may be used in combination with the above-mentioned antenna section 110. In this way, for example, an appropriate communication path can be realized by configuring the antenna section 110 to exhibit a diversity function for the array antenna section.

[0062] In the above embodiment, the antenna device 100 is applied to a vehicle, but this configuration does not limit the embodiment. For example, the antenna device 100 is effective in an environment where there are a small number of main radio wave propagation paths between wireless communication devices and the channel correlation periodically repeats highs and lows with respect to a planar position return, and can be applied anywhere. Specifically, the antenna device 100 can be applied indoors, inside the housing of industrial equipment, and in outdoor environments where line-of-sight waves and reflected waves are the main propagation paths.

[0063] In the above-described embodiment, the antenna unit 110 is a planar patch antenna, but the embodiment is not limited to this. For example, the same effect can be obtained by applying the configuration of the above-described embodiment to a general antenna such as a dipole antenna, a slot antenna, or a horn antenna.

[0064] Furthermore, the antenna device 100 in the above embodiment is effective in any environment in which the channel correlation between two antennas periodically goes high and low with respect to a change in position on a plane. Therefore, since there is no restriction on the relative positional relationship between the transmitter and receiver, the antenna device 100 can be applied to antennas mounted on sensors arranged three-dimensionally.

[0065] In the above embodiment, the selection unit 130 selects the antenna element 111 with a low correlation value in response to the control from the control unit 120 to realize a diversity effect. The configuration of the selection unit 130 does not limit the configuration of this embodiment. For example, the selection unit 130 may be configured to select all of the above antenna elements 111. In this case, at least one antenna element 111 with low channel correlation is included, and a diversity effect can be realized. Furthermore, when all antenna elements 111 are selected, the selection unit 130 may adjust the phases of all received waves and / or transmitted waves so that they are in phase, and combine them. In this case, the antenna device 100 can increase the signal-to-noise ratio (hereinafter referred to as S / N ratio) of the received waves and / or transmitted waves without canceling each other, and can realize a diversity effect. Furthermore, the selection unit 130 may adjust the phases of the received waves and / or transmitted waves so that they are in phase, and then multiply each received wave and / or transmitted wave by its envelope to maximize the S / N ratio of the combined wave. In this case, the signal-to-noise ratio can be maximized for each of the above-mentioned methods for the selection unit 130, making it possible to obtain a more appropriate diversity effect.

[0066] The features of the antenna device 100 and the antenna of this embodiment will be described below.

[0067] The antenna device 100 according to the first aspect includes an antenna section 110 in which a plurality of antenna elements including at least a first antenna element, a second antenna element, a third antenna element, and a fourth antenna element are arranged on an antenna substrate. The antenna device 100 also includes a selection section 130 that selects an antenna element 111 included in the antenna section 110, and a control section 120 that controls the selection section 130. The antenna device 100 defines a first straight line in a first direction that connects the position of the first antenna element and the position of the second antenna element. The antenna device 100 also defines a second straight line that passes through the position of the third antenna element in the first direction. The antenna device 100 also defines a third straight line that passes through the fourth antenna element in the first direction. In the antenna device 100, the antenna element 111 is arranged on the antenna substrate 112 such that the longer of the first distance between the first straight line and the second straight line and the second distance between the second straight line and the third straight line is not an integer multiple of the shorter distance.

[0068] According to the above configuration, the antenna device 100 in this embodiment can realize the antenna section 110 including the antenna element 111 with low channel correlation. Therefore, the antenna device 100 can achieve spatial diversity even in an environment where the channel correlation has spatial periodicity and repeats highs and lows.

[0069] In the antenna device 100 according to the second aspect, a fourth straight line in the second direction is defined that connects the position of the first antenna element and the position of the fourth antenna element. In addition, in the antenna device 100, a fifth straight line is defined that passes through the position of the second antenna element in the second direction. In addition, in the antenna device 100, a sixth straight line is defined that passes through the third antenna element in the second direction. In the antenna device 100, the antenna element 111 is disposed on the antenna substrate 112 such that the longer of the third distance and the fourth distance is not an integer multiple of the shorter of the third distance and the fourth distance between the fifth and sixth straight lines.

[0070] According to the above configuration, the antenna device 100 in this embodiment can realize the antenna section 110 including the antenna element 111 with low channel correlation even in the second direction different from the first direction. Therefore, the antenna device 100 can make the spatial diversity function more appropriately even in an environment where the channel correlation has spatial periodicity and repeats high and low correlations.

[0071] The control unit 120 of the antenna device 100 according to the third embodiment may control the selection unit 130 to select, from among the antenna elements 111, at least one antenna element 111 that is located at a position where the channel correlation is low.

[0072] According to the above configuration, the antenna device 100 can include antenna elements 111 with low channel correlation in the antenna elements 111 selected by the selection unit 130, and can achieve spatial diversity.

[0073] The antenna device 100 according to the fourth embodiment may further include a switching section 140 that switches between transmitting and receiving a signal via the antenna section 110.

[0074] According to the above configuration, the antenna device 100 can function as the transmitting side antenna device 100a or the receiving side antenna device 100b depending on the installation location and the usage environment, and more flexible application is possible in the communication system 10 including the antenna device 100. Also, it becomes possible to install the antenna device 100 on both the transmitting side and the receiving side, and it becomes possible to make the spatial diversity function more appropriately.

[0075] The antenna device 100 according to the fifth embodiment may further include an array antenna section in which antenna elements 111 are arranged in a lattice pattern.

[0076] According to the above configuration, the antenna device 100 can realize an appropriate communication path by configuring the antenna section 110 to exhibit a diversity function with respect to the array antenna section.

[0077] The antenna according to the sixth aspect is an antenna in which a plurality of antenna elements 111 including at least a first antenna element, a second antenna element, a third antenna element, and a fourth antenna element are arranged on an antenna substrate 112. In addition, the antenna has a first straight line in a first direction connecting the position of the first antenna element and the position of the second antenna element. In addition, the antenna has a second straight line in the first direction passing through the position of the third antenna element. In addition, the antenna has a third straight line in the first direction passing through the fourth antenna element. In the antenna, the antenna elements 111 are arranged on the antenna substrate 112 such that the longer of the first distance and the second distance is not an integer multiple of the shorter distance with respect to a first distance between the first straight line and the second straight line and a second distance between the second straight line and the third straight line.

[0078] According to the above configuration, the antenna in this embodiment can realize an antenna including antenna elements 111 with low channel correlation. Therefore, the antenna can achieve spatial diversity even in an environment where channel correlation has spatial periodicity and repeats highs and lows. [Explanation of symbols]

[0079] 10. Communication Systems 100 Antenna device 110 Antenna section 111, 111a, 111b, 111c, 111d antenna elements 112 Antenna board 120 Control section 130 Selection section 140 Switching section

Claims

1. an antenna section including a plurality of antenna elements, including at least a first antenna element, a second antenna element, a third antenna element, and a fourth antenna element, disposed on an antenna substrate; A selection unit that selects the antenna element provided in the antenna unit; A control unit that controls the selection unit, An antenna device in which, in a relationship between a first line in a first direction connecting the position of the first antenna element and the position of the second antenna element, a second line passing through the position of the third antenna element in the first direction, and a third line passing through the fourth antenna element in the first direction, the antenna elements are arranged on the antenna substrate such that, with respect to a first distance between the first line and the second line and a second distance between the second line and the third line, the longer of the first distance and the second distance is not an integer multiple of the shorter distance.

2. 2. The antenna device according to claim 1, wherein, in a relationship between a fourth line in a second direction connecting the position of the first antenna element and the position of the fourth antenna element, a fifth line passing through the position of the second antenna element in the second direction, and a sixth line passing through the third antenna element in the second direction, the antenna elements are arranged on the antenna substrate such that, with respect to a third distance between the fourth line and the fifth line and a fourth distance between the fifth line and the sixth line, the longer of the third distance and the fourth distance is not an integer multiple of the shorter distance.

3. The antenna device according to claim 1 , wherein the control unit controls the selection unit to select at least one of the antenna elements that is located at a position where channel correlation is low, from among the antenna elements.

4. The antenna device according to claim 1 , further comprising a switching unit that switches between transmitting and receiving a signal via the antenna unit.

5. 4. The antenna device according to claim 1, further comprising an array antenna section in which the antenna elements are arranged in a lattice pattern.

6. An antenna having a plurality of antenna elements, including at least a first antenna element, a second antenna element, a third antenna element, and a fourth antenna element, disposed on an antenna substrate, An antenna in which, in a relationship between a first line in a first direction connecting the position of the first antenna element and the position of the second antenna element, a second line passing through the position of the third antenna element in the first direction, and a third line passing through the position of the fourth antenna element in the first direction, the antenna elements are arranged on the antenna substrate such that, with respect to a first distance between the first line and the second line and a second distance between the second line and the third line, the longer of the first distance and the second distance is not an integer multiple of the shorter distance.

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