JP2012129599A - Antenna device - Google Patents

Abstract

The present invention provides an antenna device that can change directivity in a one-dimensional direction and can be miniaturized.
An antenna device according to the present invention includes a substrate, a plurality of power feeding elements disposed on the substrate, and both ends of the plurality of power feeding elements, which are spaced apart from the power feeding elements. It is characterized by comprising a plurality of parasitic elements having a shape intersecting a rectangular shape, and a plurality of stubs respectively connected to the plurality of parasitic elements.
[Selection] Figure 1

Description

  The present invention relates to an antenna device using a microstrip antenna.

  2. Description of the Related Art Conventionally, a MIMO (Multiple Input Multiple Output) function and a directivity variable function are required for an antenna device used in a mobile communication base station in order to increase communication capacity. Generally, the directivity of an antenna device is changed by arranging a plurality of antennas, but the circuit configuration of the antenna is complicated.

  Furthermore, there is a demand for downsizing of mobile communication base stations, and downsizing of antenna devices is also desired. As an antenna device having this downsizing and variable directivity function, for example, there is a microstrip antenna presented in Patent Documents 1 and 2. In the microstrip antennas described in Patent Documents 1 and 2, a rectangular parasitic element (non-excited element) is arranged at both ends of a rectangular feeding element, and a switch connected to the parasitic element is controlled to supply the element. It is intended to change the directivity by making it possible to connect and open.

Saitama University Faculty of Engineering Osamu Haneishi, Hidekazu Suga, “Beam Shaping of Microstrip Antenna with Variable Stub-Loaded Non-Excited Element”, IEICE Transactions, April 17, 1986, AP86-1 JP 2007-37077 A

  However, the antenna device presented in Patent Document 1 has a limited directivity variable direction. In addition, as presented in Patent Document 2, in the case of an antenna device in which a plurality of feeding elements and parasitic elements are arranged, the directivity variable direction can be switched between up, down, left, and right. In order not to be affected by mutual interference, it is necessary to arrange them at a predetermined distance, which is undesirable from the viewpoint of miniaturization.

  In view of the above problems, an object of the present invention is to provide an antenna device that can be miniaturized and can change the directivity for realizing MIMO and beamforming.

  An antenna device according to an embodiment of the present invention is disposed on a substrate, a plurality of power feeding elements disposed on the substrate, and both ends of the plurality of power feeding elements, separated from the power feeding elements, A plurality of parasitic elements having a shape obtained by intersecting two rectangular shapes, and a plurality of stubs respectively connected to the plurality of parasitic elements. According to the antenna device according to an embodiment of the present invention, the directivity can be varied in a one-dimensional direction, and downsizing can be realized.

  In addition, an antenna device according to an embodiment of the present invention includes a rectangular substrate and a plurality of substantially cross-shaped elements that are arranged at four corners of the substrate and have overlapping portions at portions where two rectangular shapes intersect. A plurality of parasitic elements, a plurality of feeder elements disposed between the plurality of parasitic elements, respectively, and a plurality of stubs respectively connected to the plurality of parasitic elements. It is characterized by providing. According to the antenna device according to an embodiment of the present invention, the directivity can be varied in a one-dimensional direction, and downsizing can be realized.

  Furthermore, the antenna device according to an embodiment of the present invention includes a rectangular substrate, a plurality of feeding elements respectively disposed on the sides on the substrate, and the plurality of feeding elements so as to sandwich the plurality of feeding elements. A plurality of polygonal parasitic elements disposed at both ends of the feeding element by a predetermined distance from the feeding element, and a plurality of stubs respectively connected to the plurality of parasitic elements. It is characterized by that. According to the antenna device according to an embodiment of the present invention, the directivity can be varied in a one-dimensional direction, and downsizing can be realized.

  ADVANTAGE OF THE INVENTION According to this invention, directivity can be changed to a one-dimensional direction, and the antenna apparatus which implement | achieves size reduction can be provided.

It is a perspective view which shows the structure of the antenna apparatus which concerns on the 1st Embodiment of this invention. It is a figure for demonstrating the structure of the antenna apparatus which concerns on the 1st Embodiment of this invention, (a) is a top view which shows the structure of the microstrip antenna shown in FIG. 1, (b) is It is a top view which shows the structure of the parasitic element board | substrate shown in FIG. It is a figure for demonstrating schematic structure of the conventional antenna apparatus, (a) is a perspective view which shows schematic structure of the conventional antenna apparatus, (b) is Y of the antenna apparatus shown to (a). It is a figure which shows the radiation characteristic of -Z direction. It is a figure which shows the electric current distribution of the antenna apparatus shown in FIG. It is a figure for demonstrating schematic structure of the antenna apparatus which concerns on the comparative example 1 with respect to this invention, (a) is a perspective view which shows schematic structure of the antenna apparatus which concerns on the comparative example 1, (b) is ( It is a figure which shows the radiation characteristic of the YZ direction of the antenna apparatus shown to a). It is a figure which shows the electric current distribution of the antenna apparatus shown in FIG. It is a figure for demonstrating schematic structure of the antenna device which concerns on the comparative example 2 with respect to this invention, (a) is a perspective view which shows schematic structure of the antenna device which concerns on the comparative example 2, (b) is ( It is a figure which shows the radiation characteristic of the YZ direction of the antenna apparatus shown to a). It is a figure which shows the electric current distribution of the antenna apparatus shown in FIG. It is a perspective view which shows schematic structure of the antenna apparatus which concerns on the comparative example 3 with respect to this invention. It is a figure which shows the electric current distribution of the antenna apparatus shown in FIG. It is a figure for demonstrating schematic structure of the antenna apparatus which concerns on the comparative example 4 with respect to this invention, (a) is a perspective view which shows schematic structure of the antenna apparatus which concerns on the comparative example 4, (b) is ( It is a figure which shows the radiation characteristic of the YZ direction of the antenna apparatus shown to a). It is a figure which shows the electric current distribution in a part of antenna apparatus shown in FIG. It is a perspective view showing a schematic structure of a microstrip antenna of an antenna device concerning a 1st embodiment of the present invention. It is a figure for demonstrating the radiation pattern of the antenna apparatus which concerns on the 1st Embodiment of this invention, (a) is a case where directivity is changed in the direction of -90 degree-0 degree of a YZ direction. It is a figure which shows a radiation pattern in three dimensions, (b) is a figure which shows the radiation characteristic of the YZ direction in the radiation pattern shown to (a), (c) is 0 degree of a YZ direction. (D) is a figure which shows the radiation characteristic of the YZ direction in the radiation pattern shown to (c), and (e) is a figure which shows the radiation pattern at the time of changing directivity to the direction of (e). ) Is a diagram showing the radiation pattern in a three-dimensional manner when the directivity is varied in the direction of 0 ° to 90 ° in the YZ direction, and (f) is the Y− in the radiation pattern shown in (e). It is a figure which shows the radiation characteristic of a Z direction. It is a figure for demonstrating the radiation pattern of the antenna apparatus which concerns on the 1st Embodiment of this invention, (a) is a figure which shows the radiation characteristic of the XZ direction in the radiation pattern shown to Fig.14 (a). (B) is a figure which shows the radiation characteristic of the XY direction in the radiation pattern shown to Fig.14 (a), (c) is X-- in the radiation pattern shown in FIG.14 (b). It is a figure which shows the radiation characteristic of a Z direction, (d) is a figure which shows the radiation characteristic of the XY direction in the radiation pattern shown in FIG.14 (b), (e) is a figure which shows FIG.14 (c). It is a figure which shows the radiation characteristic of the XZ direction in the radiation pattern shown to (f), (f) is a figure which shows the radiation characteristic of the XY direction in the radiation pattern shown in FIG.14 (c). It is a figure which shows the electric current distribution in a part of antenna apparatus which concerns on the 1st Embodiment of this invention.

  Hereinafter, an antenna device according to the present invention will be described with reference to the drawings. However, the antenna device of the present invention can be implemented in many different modes and should not be construed as being limited to the description of the embodiments described below.

(First embodiment)
Hereinafter, an antenna device according to a first embodiment of the present invention will be described in detail with reference to the drawings.

<Configuration>
FIG. 1 is a perspective view showing a configuration of an antenna apparatus 1000 according to the first embodiment of the present invention. In FIG. 1, an antenna device 1000 includes a ground conductor 120, a first substrate 110 disposed on the ground conductor 120, a plurality of feeding elements 101a to 101d and a plurality of parasitic elements disposed on the first substrate 110. A microstrip antenna 100 comprising 102a-102d. The antenna device 1000 includes a parasitic element substrate 200 including a plurality of parasitic elements 201 a to 201 d disposed on the second substrate 210 and spaced apart from the microstrip antenna 100 on the microstrip antenna 100. But you can.

  The microstrip antenna 100 and the parasitic element substrate 200 shown in FIG. 1 will be described in more detail with reference to FIG. FIG. 2 is a view for explaining the configuration of the antenna device 1000 according to the first embodiment of the present invention, and FIG. 2A is a top view showing the configuration of the microstrip antenna 100 shown in FIG. (B) is a top view which shows the structure of the parasitic element board | substrate 200 shown in FIG.

  As shown in FIG. 2A, the microstrip antenna 100 is configured such that rectangular power supply elements 101 a to 101 d and polygonal parasitic elements 102 a to 102 d are arranged on a first substrate 110. is there. The first substrate 110 is a dielectric, and a ground conductor 120 having the same size as that of the first substrate 110 may be disposed under the first substrate 110 as illustrated in FIG. The size of the first substrate 110 may be, for example, a square shape with one side of about 14 cm to 17 cm, and the thickness may be a thin plate shape with a thickness of 0.2 mm to 1.0 mm. In addition, the dimension of the 1st board | substrate 110 and the ground conductor 120 is an example, and may be changed according to the dimension requested | required with respect to the antenna apparatus 1000. FIG. The feed elements 101a to 101d and the passive elements 102a to 102d are thin metal, and may be formed by patterning a metal thin film on the first substrate 110, respectively. In addition, a plurality of thin metal plates may be stacked on the first substrate 110, respectively.

  As illustrated in FIG. 2A, the power feeding elements 101a to 101d may have a rectangular shape in which the lengths a1 and b1 of two different sides satisfy a1> b1. The power feeding elements 101a to 101d are arranged on the side of the first substrate 110 at a distance c1 from the edge of the first substrate 110, and the length of the side facing the edge of the first substrate 110 is b1. Placed in. At this time, as shown in the drawing, the power feeding elements 101a to 101d may be arranged symmetrically on two axes k1 and k2 that are orthogonal to each other through the center of one side of the first substrate 110. Here, as an example, each dimension may be a1 = 53 mm, b1 = 30 mm, and c1 = 15 mm, but is not limited thereto.

  In addition, feed points 111a to 111d are arranged at positions that define the detection direction in the feed elements 101a to 101d, respectively. The microstrip antenna 100 is fed with power to the ground conductor 120 disposed under the microstrip antenna 100 via the feeding points 111a to 111d. The feeding points 111a to 111d may be arranged at positions close to the edge side of the first substrate 110 from the center of the rectangular feeding elements 101a to 101d as shown in the figure, but are not limited to the illustrated positions and are not limited to the specifications. It can be changed accordingly.

  As shown in FIG. 2A, the parasitic elements 102a to 102d may have a polygonal shape formed by intersecting two rectangular shapes having the same shape at right angles. For example, the shape which is the same shape as the power feeding elements 101a to 101d and the two sides a1 and b1 are formed by orthogonally intersecting two rectangular shapes with a1> b1. In addition, the parasitic elements 102a to 102d may have a substantially cross shape in which the centers of the two rectangular shapes are shifted and intersected without overlapping each other. At this time, the parasitic elements 102a to 102d are respectively the first The substrate 110 may be arranged in an axially symmetric shape with the diagonal line as an axis. Further, the parasitic elements 102a to 102d may be arranged in an axially symmetric shape with respect to two orthogonal axes k1 and k2 on the first substrate 110. As shown in FIG. 2A, the parasitic elements 102a to 102d include the length a2 of the sides of the parasitic elements 102a to 102d facing the center O of the first substrate 110, and the first substrate 110. The shape may be such that two rectangular shapes intersect each other so that the length a3 of the sides of the parasitic elements 102a to 102d facing the corners is a2 <a3. As an example, the dimensions of the parasitic elements 102a to 102d may be a2 = 14.7 mm and a3 = 8.8 mm, but are not limited thereto.

  Two connection points 112a to 112h are arranged in each of the parasitic elements 102a to 102d. As shown in the figure, the connection points 112a to 112h may be arranged on intersections where the two rectangular shapes of the parasitic elements 102a to 102d cross, but are not limited to the illustrated positions, and are appropriately determined according to specifications. Can be changed. As shown in FIG. 13, stubs 122a to 122p are connected to the connection points 112a to 112h via switches 123a to 123h. The stubs 122a to 122p are two open stubs having different lengths, and one of the long and short open stubs may be selected by switching the switches 123a to 123h. The size and configuration of the stubs 122a to 122p can be changed as appropriate according to the configuration of the antenna device.

  The parasitic elements 102a to 102d are disposed at both ends of the feeder elements 101a to 101d. As illustrated in FIG. 2A, the parasitic elements 102 a to 102 d are separated from the edge of the first substrate 110 by a distance c1 at the four corners of the rectangular first substrate 110. May be arranged such that the length of the opposite side is b1. Further, the parasitic elements 102a to 102d are only a predetermined distance from the feeding elements 101a to 101d so that the distances from the connection points 112a to 112h to the feeding points 111a to 111d of the feeding elements 101a to 101d are the element spacing d1. Spaced apart. In the present embodiment, the element interval d1 is d1 = 40.8 mm.

  On the microstrip antenna 100 having such a configuration, the parasitic element substrate 200 is disposed via a spacer (not shown) or the like. As illustrated in FIG. 2B, the parasitic element substrate 200 is obtained by disposing parasitic elements 201 a to 201 d on the second substrate 210. The parasitic elements 201a to 201d may be formed in the same shape using the same material as the power feeding elements 101a to 101d. Even if the lengths a1 and b1 of two different sides are a1> b1. Good. At this time, as shown in FIG. 1, the parasitic elements 201a to 201d on the second substrate 210 are arranged so as to be separated from the power feeding elements 101a to 101d on the first substrate 110 by a predetermined distance and overlap at the same position. May be.

  Next, in order to explain the operation and radiation characteristics of the antenna device 1000 according to the first embodiment of the present invention including the above-described microstrip antenna 100, hereinafter, antenna devices according to Conventional Example 1 and Comparative Examples 1 to 4 will be described. 400 to 800 will be described. The antenna devices 400 to 800 are manufactured using the same materials and manufacturing methods as those of the antenna device 1000 according to the first embodiment of the present invention. Omitted.

(Conventional example 1)
With reference to FIG. 3 and FIG. 4, the configuration of the antenna device 400 and the radiation characteristic of the beam according to Conventional Example 1 will be described. FIG. 3 is a diagram for explaining a schematic configuration of a conventional antenna device 400, (a) is a perspective view showing a schematic configuration of the conventional antenna device 400, and (b) is a diagram illustrating (a). It is a figure which shows the radiation characteristic of the YZ direction of the antenna apparatus 400 shown. FIG. 4 is a diagram showing a current distribution of the antenna device 400 shown in FIG.

  As illustrated in FIG. 3A, the antenna device 400 according to the conventional example 1 is separated from the feeding element 401 and the feeding point 411 of the feeding element 401 by the element interval d4 on the substrate 410. Parasitic elements 402a and 402b having connection points 412a and 412b arranged at both ends are arranged. At this time, each of the power supply element 401 and the parasitic elements 402a and 402b has a square shape with a side length a4 of a4 = 50.5 mm. The element spacing d4 at this time is d4 = 58 mm, and the length of the entire antenna element including the feeding element 401 and the parasitic elements 402a and 402b is 1.44λ. In the following, λ is the wavelength of the resonance frequency of the feed element.

  According to the antenna device 400, as shown in FIG. 3B, it has radiation characteristics in the YZ direction. The current distribution of the antenna device 400 at this time is as shown in FIG. FIG. 4 shows a current distribution when the length of the stub 422a connected to the connection point 412a of the parasitic element 402a is long and the length of the stub 422b connected to the connection point 412b of the parasitic element 402b is short. Yes.

  In FIG. 4, ranges 403a and 403b surrounded by dotted lines indicate portions that cause coupling between the feeding element 401 and the parasitic elements 402a and 402b, respectively. Referring to the ranges 403a and 403b shown in FIG. 4, it can be seen that the parasitic element 402a and the parasitic element 402b have different couplings. Therefore, the conventional antenna device 400 adjusts the coupling by adjusting the coupling generated in the parasitic element 402a by the stub 422a connected to the parasitic element 402a.

  As described above, in the antenna device 400 according to the related art example 1, the size of the antenna element is as large as 1.44λ. Therefore, in order to reduce the size of the antenna device, an experiment was performed by changing the shape of the antenna element as in Comparative Examples 1 to 4 described below.

(Comparative Example 1)
With reference to FIG.5 and FIG.6, the structure of the antenna apparatus 500 which concerns on the comparative example 1 with respect to this invention, and the radiation characteristic of a beam are demonstrated. FIG. 5 is a diagram for explaining a schematic configuration of the antenna device 500 according to the comparative example 1. FIG. 5A is a perspective view illustrating a schematic configuration of the antenna device 500 according to the comparative example 1. FIG. These are figures which show the radiation characteristic of the YZ direction of the antenna apparatus 500 shown to (a). FIG. 6 is a diagram showing a current distribution of the antenna device 500 shown in FIG.

  As illustrated in FIG. 5A, the antenna device 500 according to the comparative example 1 is separated from the feeding element 501 and the feeding point 511 of the feeding element 501 by the element interval d5 on the substrate 510. Parasitic elements 502a and 502b having connection points 512a and 512b arranged at both ends are arranged. At this time, the feeding element 501 and the parasitic elements 502a and 502b have rectangular shapes in which the lengths a5 and b5 of two different sides are a5 = 20 mm and b5 = 51 mm, respectively. The element interval d5 at this time is d5 = 58 mm, and the length of the entire antenna element including the feeding element 501 and the parasitic elements 502a and 502b is 0.9λ. Therefore, the antenna device 500 according to Comparative Example 1 can be reduced in size as compared with the antenna device 400 according to Conventional Example 1 shown in FIG.

  According to the antenna device 500, as shown in FIG. 5B, it has radiation characteristics in the YZ direction. Note that the current distribution of the antenna device 500 at this time is as shown in FIG. FIG. 6 shows a current distribution when the length of the stub 522a connected to the connection point 512a of the parasitic element 502a is long and the length of the stub 522b connected to the connection point 512b of the parasitic element 502b is short. Yes.

  In FIG. 6, ranges 503 a and 503 b surrounded by dotted lines indicate portions where coupling is generated between the feeding element 501 and the parasitic elements 502 a and 502 b, respectively. When the parasitic element 502a and the parasitic element 502b in the ranges 503a and 503b shown in FIG. 6 are compared, it can be seen that the coupling amount is small and the directivity variable amount is small.

  As described above, the antenna device 500 according to the comparative example 1 can be downsized to 0.9λ as compared with the antenna device 400 according to the conventional example 1, but the amount of directivity is small. there were. For this reason, in order to realize both downsizing of the antenna device and increasing the variable amount of directivity, an experiment was performed by changing the shape of the antenna element as Comparative Example 2 described below.

(Comparative Example 2)
With reference to FIG.7 and FIG.8, the structure of the antenna apparatus 600 which concerns on the comparative example 2, and the radiation characteristic of a beam are demonstrated. FIG. 7 is a diagram for explaining a schematic configuration of the antenna device 600 according to the comparative example 2. FIG. 7A is a perspective view illustrating a schematic configuration of the antenna device 600 according to the comparative example 2. FIG. These are figures which show the radiation characteristic of the YZ direction of the antenna apparatus 600 shown to (a). FIG. 8 is a diagram showing a current distribution of the antenna device 600 shown in FIG.

  As illustrated in FIG. 7A, the antenna device 600 according to the comparative example 2 is separated from the feeding element 601 and the feeding point 611 of the feeding element 601 by the element interval d6 on the substrate 610. Parasitic elements 602a and 602b having connection points 612a and 612b arranged at both ends are arranged. At this time, the feed element 601 has a rectangular shape having the same size as that of the feed element 501 of the antenna device 500 according to the comparative example 1 illustrated in FIG. In addition, the parasitic elements 602a and 602b extend from the rectangular shape having the same size as the parasitic elements 502a and 502b according to the comparative example 1 toward the feeding element 601 by a length a6, and have different two side lengths a6. , B6 have a combined shape of rectangles where a6 = 20 mm and b5 = 51 mm. The element spacing d6 at this time is d6 = 58 mm, and the length of the entire antenna element including the feeding element 501 and the parasitic elements 502a and 502b is 0.9λ. Therefore, the antenna device 600 according to the comparative example 2 can be downsized as compared with the antenna device 400 according to the conventional example 1, similarly to the antenna device 500 according to the comparative example 1.

  The antenna device 600 has radiation characteristics in the YZ direction as illustrated in FIG. Note that the current distribution of the antenna device 600 at this time is as shown in FIG. FIG. 8 shows a case where the length of the stub 622a connected to the connection point 612a of the parasitic element 602a is long and the length of the stub 622b connected to the connection point 612b of the parasitic element 602b is short.

  In FIG. 8, ranges 603a and 603b surrounded by dotted lines indicate portions where coupling is generated between the feeding element 601 and the parasitic elements 602a and 602b, respectively. In the ranges 603a and 603b shown in FIG. 8, it can be seen that the amount of current flowing through the parasitic elements 602a and 602b is increased as compared with the conventional example 1 and the comparative example 1. For this reason, the antenna device 600 can increase the variable amount of directivity by the connected stubs 622a and 622b as compared with the antenna device 500.

  As described above, the antenna device 600 according to the comparative example 2 can be reduced to 0.9λ as compared with the antenna device 400 according to the conventional example 1, but the directionality variable direction is limited. Met. Therefore, in order to realize both downsizing of the antenna device and increasing the variable amount of directivity, an experiment was performed by changing the shape of the antenna element as Comparative Example 3 described below.

(Comparative Example 3)
With reference to FIG.9 and FIG.10, the structure of the antenna apparatus 700 which concerns on the comparative example 3, and the radiation characteristic of a beam are demonstrated. FIG. 9 is a diagram for explaining a schematic configuration of an antenna device 700 according to Comparative Example 3. 10 is a diagram showing a current distribution of the antenna device 700 shown in FIG.

  As illustrated in FIG. 9, the antenna device 700 according to the comparative example 3 is separated from the feeding element 701 and the feeding point 711 of the feeding element 701 by an element interval d7 on the substrate 710 at both ends of the feeding element 701. Parasitic elements 702a and 702b having connection points 712a and 712b to be disposed are disposed. At this time, the feed element 701 has a rectangular shape having the same size as that of the feed element 501 of the antenna device 500 according to the comparative example 1 illustrated in FIG. Further, the parasitic elements 702a and 702b extend from the rectangular shape having the same size as the parasitic elements 502a and 502b of the antenna device 500 according to the comparative example 1 toward the feeding element 701 by a length a7, respectively. The lengths a7 and b7 of the rectangular shape with a7 = 30 mm and b7 = 10 mm, and further extending from the rectangular shape by a length a8 toward the power feeding element 701, respectively, have two different side lengths a8 and b8. The shape is a combination of a rectangular shape with a8 = 7 mm and b8 = 30 mm. The element interval d7 at this time is d7 = 58 mm, and the length of the entire antenna element including the feeding element 701 and the parasitic elements 702a and 702b is 0.9λ. Therefore, the antenna device 700 according to the comparative example 3 can be downsized as compared with the antenna device 400 according to the conventional example 1, similarly to the antenna devices 500 and 600 according to the comparative examples 1 and 2.

  FIG. 10 shows a current distribution of the antenna device 700. FIG. 10 shows a case where the length of the stub 722a connected to the connection point 712a of the parasitic element 702a is long and the length of the stub 722b connected to the connection point 712b of the parasitic element 702b is short.

  In FIG. 10, ranges 703a and 703b surrounded by dotted lines indicate portions that cause coupling between the feeding element 701 and the parasitic elements 702a and 702b. It can be seen that the amount of current flowing through the parasitic elements 702a and 702b in the ranges 703a and 703b shown in FIG. 10 increases as compared with the comparative example 1, but decreases as compared with the comparative example 2. Therefore, it can be seen that the antenna device 700 according to the comparative example 3 is configured to reduce the amount of coupling that contributes to changing the directivity as compared with the antenna device 600 according to the comparative example 2.

  As described above, the antenna device 700 according to the comparative example 3 can extend the part of the shape of the parasitic elements 702a and 702b to be close to the feeder element 701 and increase the coupling amount to change the directivity. The antenna device 700 can be reduced in size. Further, as Comparative Example 4 described below, an experiment for MIMO was performed to increase the communication amount.

(Comparative Example 4)
With reference to FIG.11 and FIG.12, the structure of the antenna apparatus 800 which concerns on the comparative example 4, and the radiation characteristic of a beam are demonstrated. FIG. 11 is a diagram for explaining a schematic configuration of an antenna apparatus 800 according to Comparative Example 4, and (a) is a perspective view illustrating a schematic configuration of the antenna apparatus 800 according to Comparative Example 4, and (b). These are the figures which show the radiation characteristic of the YZ direction of the antenna apparatus 800 shown to (a). FIG. 12 is a diagram showing a current distribution in a part of the antenna device 800 shown in FIG.

  As illustrated in FIG. 11A, the antenna device 800 according to the comparative example 4 includes, on the substrate 810, element spacing from four feeding elements 801a to 801d and feeding points 811a to 811d of the feeding elements 801a to 801d, respectively. Four parasitic elements 802a to 802d having connection points 812a to 812h arranged at both ends of the power feeding elements 801a to 801d separated by d8 are arranged. At this time, each of the power feeding elements 801a to 801d and the parasitic elements 802a to 802d has a square shape with one side a1 like the power feeding element 401 and the parasitic elements 402a and 402b according to Conventional Example 1. Note that the antenna device 800 uses the feeding element 801a and the parasitic elements 802a and 802b arranged at both ends of the feeding element 801a as one antenna, and the antenna is centered on the Z axis passing through the center O of the substrate 810. The antenna is rotated by four degrees and four antennas are arranged on the substrate 810. By rotating the antenna by 90 degrees, the polarizations of the antennas of the feed elements 801a and 801c and the feed elements 801b and 801d are orthogonal to each other. The parasitic elements 802a to 802d exclude overlapping portions. The parasitic elements of the feeding element 801a are parasitic elements 802a and 802b, the parasitic elements of the feeding element 801b are parasitic elements 802b and 802c, and the parasitic elements of the feeding element 801c are parasitic elements 802c and 802d. The parasitic elements of the feeding element 801d are the parasitic elements 802d and 802a. The element interval d8 at this time is d8 = 58 mm, which is 0.5λ.

  FIG. 12 shows an antenna current distribution in a part of the antenna device 800. In FIG. 12, the stubs 822a and 822b connected to the connection points 812a and 812b of the parasitic element 802a and the stub 822d connected to the connection point 812d of the parasitic element 802b are long and the connection of the parasitic element 802b is shown. The case where the length of the stub 822c connected to the point 812c is short is shown.

  In FIG. 12, ranges 803a and 803b surrounded by dotted lines indicate portions that cause coupling between the feeding element 801a and the parasitic elements 802a and 802b. Compared with the antenna device 400 according to the conventional example 1, the amount of coupling is small. This is because the parasitic elements 802a and 802b are also used, and current is not generated orthogonal to the parasitic elements 802a and 802b.

  As described above, the antenna device 800 according to the comparative example 4 is configured by compactly arranging four antennas so that the antenna device 400 according to the conventional example 1 can support MIMO. There is almost nothing.

  As described above, none of the antenna devices 400 to 800 according to the conventional example 1 and the comparative examples 1 to 4 can be downsized and obtain a desired directivity variable amount. Therefore, the antenna device 500 according to Comparative Example 1 is configured so as to have the configuration of the antenna device 600 according to Comparative Example 2 that results in an increase in the amount of coupling between the feed element 601 and the parasitic elements 602a and 602b. As an antenna, the antenna apparatus 1000 according to the first embodiment of the present invention is obtained by arranging the antennas based on the configuration of the antenna apparatus 800.

(First embodiment)
Hereinafter, the configuration and operation of the antenna device 1000 according to the first embodiment of the present invention will be described in more detail with reference to FIGS. 13 to 16.

  FIG. 13 is a perspective view showing a schematic configuration of the microstrip antenna 100 included in the antenna device 1000 according to the first embodiment of the present invention. The microstrip antenna 100 shown in FIG. 13 has the same configuration as the microstrip antenna 100 shown in FIG. The microstrip antenna 100 is based on the configuration of the antenna device 500 according to the comparative example 1, and the configuration in which the parasitic elements 102a to 102d are combined in a convex shape with respect to the feeding elements 101a to 101d, and the comparative example. 4 including a configuration in which a plurality of parasitic elements 102a to 102d are arranged at both ends of a plurality of feeding elements 101a to 101d so as to sandwich the plurality of feeding elements 101a to 101d, respectively, based on the configuration of the antenna device 800 according to FIG. It was.

  As illustrated in FIG. 13, stubs 122a to 122p are connected to connection points 112a to 112h of parasitic elements 102a to 102d via switches 123a to 123h, respectively. As described above, the lengths of the two open stubs of the stubs 122a to 122p are changed by switching the switches 123a to 123h connected thereto. FIG. 13 shows a schematic configuration of the stubs 122a to 122p and the switches 123a to 123h. The stubs 122a to 122p and the switches 123a to 123h are assumed to have the same size and configuration.

  Note that the microstrip antenna 100 has a feeding element 101a and parasitic elements 102a and 102b arranged at both ends of the feeding element 101a as one antenna, with the Z axis passing through the center O of the first substrate 110 as the center. Although it has a shape in which the antenna is rotated by 90 degrees and is not shown, the parasitic elements 102a to 102d may have an overlapping portion at a portion where two rectangular shapes intersect. Further, as shown in the figure, the parasitic elements 102a to 102d do not have an overlapping portion, and may have a single substantially cross shape. At this time, the element interval d1 of the microstrip antenna 100 is d1 = 40.8 mm, which is 0.35λ. Therefore, the microstrip antenna 100 can be reduced in size as compared with the antenna devices 400 to 800 according to Conventional Example 1 and Comparative Examples 1 to 4.

  Furthermore, with reference to FIGS. 14-16, the radiation characteristic of the antenna apparatus 1000 which concerns on the 1st Embodiment of this invention is demonstrated.

  FIG. 14 is a diagram for explaining a radiation pattern of the antenna device 1000 according to the first embodiment of the present invention. FIG. 14A shows directivity in a direction from −90 ° to 0 ° in the YZ direction. 3 is a diagram showing a radiation pattern in a three-dimensional manner when V is varied, (b) is a diagram showing radiation characteristics in the YZ direction in the radiation pattern shown in (a), and (c) is a diagram showing Y- It is a figure which shows the radiation pattern at the time of changing directivity to 0 degree direction of Z direction in three dimensions, (d) is a figure which shows the radiation characteristic of the YZ direction in the radiation pattern shown to (c). (E) is a three-dimensional diagram showing a radiation pattern when the directivity is varied in the direction of 0 ° to 90 ° in the YZ direction, and (f) is shown in (e). It is a figure which shows the radiation characteristic of the YZ direction in a radiation pattern. FIG. 15 is a diagram for explaining a radiation pattern of the antenna device 1000 according to the first embodiment of the present invention. FIG. 15A is a diagram in the XZ direction in the radiation pattern shown in FIG. It is a figure which shows a radiation characteristic, (b) is a figure which shows the radiation characteristic of the XY direction in the radiation pattern shown to Fig.14 (a), (c) was shown in FIG.14 (b). It is a figure which shows the radiation characteristic of the XZ direction in a radiation pattern, (d) is a figure which shows the radiation characteristic of the XY direction in the radiation pattern shown in FIG.14 (b), (e) is It is a figure which shows the radiation characteristic of the XZ direction in the radiation pattern shown in FIG.14 (c), (f) is a figure which shows the radiation characteristic of the XY direction in the radiation pattern shown in FIG.14 (c). It is. FIG. 16 is a diagram showing a current distribution in a part of the antenna device 1000 according to the first embodiment of the present invention.

  FIG. 14 shows the directivity of the four antennas constituting the microstrip antenna 100 by controlling the stubs 122c to 122f connected to the antenna composed of the feeding element 101a and the parasitic elements 102a and 102b shown in FIG. The radiation pattern in the case of changing the characteristics is shown. Hereinafter, the switching operation of the stubs 122a to 122p for changing the directivity of the microslip antenna 100 will be described with reference to FIG.

<Operation>
First, the power feeding element 101a will be described. In the case where the directivity is varied in the direction of −90 ° to 0 ° in the YZ direction shown in FIGS. 14A and 14B, the feeding element 101a and the parasitic element 102a shown in FIGS. , 102b. In FIG. 16, the switch 123b connected to the connection point 112b (see FIG. 13) of the parasitic element 102b is connected to the long open stub 122c, and the switch 123c connected to the connection point 112c (see FIG. 13) of the parasitic element 102d is connected. The state switched to the state connected to the short open stub 122f is shown. The state of other switches is not questioned.

  In FIG. 16, ranges 103a and 103b surrounded by dotted lines indicate portions that cause coupling between the feeding element 101a and the parasitic elements 102a and 102b. When the parasitic element 102a and the parasitic element 102b in the ranges 103a and 103b shown in FIG. 16 are compared, the switch 123c connected to the connection point 112c of the parasitic element 102b is connected to the short open stub 122f. By switching, it can be seen that the amount of current flowing through the parasitic element 102b increases more than the amount of current flowing through the parasitic element 102a. As a result, a difference occurs in the coupling amount generated between the feeding element 101a and the parasitic elements 102a and 102b, so that the directivity can be varied in the direction of −90 ° to 0 ° in the YZ direction. It becomes like this.

  As shown in FIGS. 14E and 14F, when the directivity of the microstrip antenna 100 is varied in the direction of 0 ° to 90 ° in the YZ direction, the parasitic element 102a is connected. The switch 123b connected to the point 112b is switched to a state connected to the short open stub 122d, and the switch 123c connected to the connection point 112c of the parasitic element 102b is switched to a state connected to the long open stub 122e. Thereby, the amount of current flowing through the parasitic element 102a can be made larger than the amount of current flowing through the parasitic element 102b. Therefore, since it is possible to cause a difference in the coupling amount generated between the feed element 101a and the parasitic elements 102a and 102b, according to the microstrip antenna 100, the difference between 0 ° and 90 ° in the YZ direction can be obtained. Directivity can be varied in the direction.

  In order to obtain directivity having a peak at the center as shown in FIGS. 14C and 14D, both open stubs may be connected to the longer side.

  Thus, according to the microstrip antenna 100, among the four antennas, the stubs 122c to 122f are controlled for each of the antennas including the feeding element 101a and the parasitic elements 102a and 102b, thereby reducing the 0 in the YZ direction. The directivity can be varied in the direction of ° to 90 ° or in the direction of -90 ° to 0 °. The same applies to the antenna including the feeding element 101c and the parasitic elements 102c and 102d.

  Directivity can be varied in the XZ direction for the antenna composed of the feed element 101b and the parasitic elements 102b and 102c and the antenna composed of the feed element 101d and the parasitic elements 102d and 102a.

  As described above, according to the antenna apparatus 1000 according to the first embodiment of the present invention, the size of the antenna including the parasitic elements 102a and 102b that can change the directivity can be reduced to 1.13λ. . Therefore, the mobile communication base station on which the antenna device 1000 is mounted can be downsized.

DESCRIPTION OF SYMBOLS 1000 ... Antenna apparatus, 100 ... Microstrip antenna, 110 ... 1st board | substrate, 101a-101d ... Feeding element, 102a-102d ... Parasitic element, 120 ... Ground conductor, 122a-122p ... Stub, 123a-123h ... Switch

Claims (10)

A substrate,
A plurality of power feeding elements disposed on the substrate;
A plurality of parasitic elements having a shape in which two rectangular shapes are crossed at both ends of the plurality of feeding elements, respectively, spaced from the feeding element,
A plurality of stubs respectively connected to the plurality of parasitic elements;
An antenna device comprising: The plurality of stubs are connected to a plurality of switches, respectively.
The antenna device according to claim 1, wherein the directivity of the antenna device is varied by switching the plurality of switches. The plurality of feeding elements are rectangular,
The antenna device according to claim 1, wherein each of the plurality of parasitic elements has a shape in which two rectangular shapes having the same shape as the feeding element intersect each other at a right angle.   4. The antenna device according to claim 1, wherein the plurality of feeding elements and parasitic elements are each configured by patterning a metal thin film on the substrate. 5.   4. The antenna device according to claim 1, wherein each of the plurality of feeding elements and the parasitic elements is configured by laminating a plurality of thin metal plates on the substrate. 5. A rectangular substrate;
A plurality of parasitic elements having a substantially cross shape that are arranged at the four corners of the substrate and have overlapping portions at portions where two rectangular shapes intersect,
Between the plurality of parasitic elements, a plurality of feeding elements arranged separately from the parasitic elements, and
A plurality of stubs respectively connected to the plurality of parasitic elements;
An antenna device comprising: A rectangular substrate;
A plurality of power feeding elements respectively disposed on the sides on the substrate;
A plurality of non-feeding elements in a polygonal shape that are arranged at a predetermined distance from both ends of the plurality of feeding elements so as to sandwich the plurality of feeding elements, and
A plurality of stubs respectively connected to the plurality of parasitic elements;
An antenna device comprising:   The antenna device according to claim 7, wherein each of the plurality of parasitic elements has a polygonal shape in which two rectangular shapes intersect each other at a right angle.   The antenna device according to any one of claims 6 to 8, wherein the plurality of feeding elements and the parasitic elements are arranged on the axes orthogonal to each other on the substrate. The plurality of stubs are connected to a plurality of switches, respectively.
The directivity of the antenna device is varied by switching the plurality of switches to vary the amount of coupling generated between the plurality of feeding elements and the plurality of parasitic elements. The antenna apparatus as described in any one of Claims 6 thru | or 9.