JP5470155B2 - Antenna device - Google Patents

Description

  The present invention relates to an antenna device applicable to a base station for land mobile radio communication that covers the same radio zone with a radiation pattern having the same horizontal plane beam width in a plurality of frequency bands.

  6 and 7 are schematic diagrams illustrating a structure example of a conventional antenna device. 6A to 6C, 9 is a reflector made of metal, and 10 is a multi-frequency or broadband antenna that operates in a plurality of frequency bands. 7A to 7C, 11 is a reflector made of metal (corner reflector), and 12 is a multi-frequency or broadband antenna that operates in a plurality of frequency bands. The prior art described here is an example of a dipole antenna with a reflector (FIG. 6) and an antenna (FIG. 7) described in Non-Patent Document 1.

  The dimensions (W9 × L9, W11 × L11) of the reflectors 9 and 11 made of metal, the distances (D9 and D11) between the reflectors 9 and 11 and the antennas 10 and 12, and the apex angle (α9) of the corner reflector are As described in Non-Patent Document 1, it is determined by design conditions such as gain and beam width.

  FIG. 8 is a conceptual diagram showing radiation patterns in a horizontal plane in three different frequency bands of the antenna device according to the prior art. The radiation patterns in the horizontal plane in three different frequency bands F1, F2, F3 are shown. In a conventional dipole antenna with a reflector (FIG. 6) and a corner reflector antenna (FIG. 7), a reflector 9 made of metal is used so that a desired gain and beam width can be obtained in a single frequency band. In addition, the structural parameters of the corner reflector 11 are set.

Antenna Engineering Handbook (Second Edition), Chapter 4, pp. 145-146, Ohmsha, 2008

  As described above, in a conventional dipole antenna with a reflector and a corner reflector antenna, a metal reflector and a corner reflector can be obtained so that a desired gain and beam width can be obtained in a single frequency band. Since the structural parameters were set, when operating the excitation element in multiple frequency bands using a multi-frequency shared antenna that operates in multiple frequency bands or a broadband antenna, multiple gains and beam widths Cannot be made constant over the frequency band.

  Therefore, as a conventional base station antenna configuration for land mobile radio communication that covers the same radio zone with the same radiation pattern in the horizontal plane in a plurality of frequency bands, reflection is performed for each desired frequency band. A dipole antenna with a plate and a corner reflector antenna must be designed, and antennas corresponding to the number of frequency bands must be individually installed, resulting in a disadvantage that the efficiency of antenna installation space is deteriorated.

  The present invention has been made in view of such circumstances, and an object of the present invention is to design a single antenna without designing a reflector dipole antenna or a corner reflector antenna for each desired frequency band. An object of the present invention is to provide an antenna device that can share a plurality of frequencies in the device and can improve the space efficiency of antenna installation.

In order to solve the above-described problems, the present invention includes a plurality of dielectric plates made of a metamaterial and a multi-frequency shared or broadband antenna that operates in a plurality of frequency bands, and the plurality of dielectric plates. Are installed in a number corresponding to the number of the plurality of frequency bands so that band gaps are formed in the plurality of frequency bands, and each of the plurality of dielectric plates has a rectangular shape, and one side of the rectangular shape. And the different sides orthogonal to the one side and the respective lengths are the same in terms of wavelength at the center frequency of the reflected frequency band among the plurality of frequency bands, and the distance to the antenna is the plurality of frequency bands antenna, characterized in that at a position the same distance in terms of wavelength at the center frequency of the frequency band to be reflected, the plurality of dielectric plates are disposed parallel to each other among the It is the location.

The present invention also includes a plurality of dielectric plates made of a metamaterial and a multi-frequency shared or broadband antenna that operates in a plurality of frequency bands, and the plurality of dielectric plates are arranged in the plurality of frequency bands. The number of the plurality of frequency bands is set so that a band gap is formed at each of the plurality of frequency plates, and each of the plurality of dielectric plates has a rectangular flat plate along a bending axis parallel to one side of the flat plate. And having a V-shape bent in two at the same angle, and one side of the rectangular shape, a different side orthogonal to the one side, and the length of each of the plurality of frequency bands to be reflected. are identical in terms of wavelength at the center frequency of the band, the distance between the antenna, disposed at a position the same distance in your Keru wavelength converted to the center frequency of the frequency band to be reflected out of said plurality of frequency bands Is the bending axis of the plurality of dielectric plates, an antenna apparatus characterized by coplanar.

The present invention is characterized in that, in the above-mentioned invention, the largest dielectric plate among the plurality of dielectric plates is replaced by a reflector made of metal.
The present invention is characterized in that, in the above invention, the plurality of dielectric plates have a metamaterial structure in which dielectrics are arranged in a periodic structure.
According to the present invention, in the above invention, the plurality of dielectric plates have a metamaterial structure in which cylindrical dielectrics are arranged in a matrix in parallel with the central axis of each cylindrical shape. And

According to the present invention, in the above invention, the plurality of dielectric plates include different second planes in which prismatic dielectrics are arranged in parallel and at equal intervals in the first plane, and are parallel to the first plane. And having a metamaterial structure in which a lattice shape arranged at equal intervals perpendicular to the dielectric disposed in the first plane is repeated in a direction perpendicular to the first plane and the second plane. It is characterized by that.
According to the present invention, in the above invention, the plurality of dielectric plates have a metamaterial structure in which plate-like dielectrics are provided with columnar holes whose central axes are parallel to each other in a matrix shape. Features.
According to the present invention, in the above invention, the plurality of dielectric plates have a metamaterial structure in which a plurality of spherical dielectrics are arranged in a face-centered cubic lattice.

  According to the present invention, a plurality of frequencies can be shared by one antenna device without designing a dipole antenna with a reflector or a corner reflector antenna for each desired frequency band, and the space for antenna installation Efficiency can be improved.

It is a schematic diagram which shows the structure of the antenna device by 1st Embodiment of this invention. It is a schematic diagram which shows the structural example of the dielectric material board which consists of metamaterials of the antenna device by 1st Embodiment of this invention. It is a conceptual diagram which shows the transmission coefficient of the dielectric material board which consists of the 1st-3rd metamaterial of the antenna apparatus by 1st Embodiment of this invention. It is a conceptual diagram which shows the radiation pattern in the horizontal surface of the antenna apparatus by 1st Embodiment of this invention. It is a schematic diagram which shows the structure of the antenna device by 2nd Embodiment of this invention. It is a schematic diagram which shows the structural example of the antenna apparatus by a prior art. It is a schematic diagram which shows the structural example of the antenna apparatus by a prior art. It is a conceptual diagram which shows the radiation pattern in the horizontal surface of the antenna apparatus by a prior art.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

A. First Embodiment FIG. 1 is a schematic diagram showing a configuration of an antenna device according to a first embodiment of the present invention. In the following description, an XYZ orthogonal coordinate system is set as shown in the figure, and the positional relationship of each member will be described with reference to this XYZ orthogonal coordinate system. FIG. 1A is a diagram showing the shape of the antenna device of the present embodiment in plan view in the X-axis direction. FIG. 1B is a perspective view of the antenna device. FIG.1 (c) is a figure which shows the shape of planar view of the antenna apparatus in a Z-axis direction.
In FIG. 1, 1 is a dielectric plate made of a first metamaterial, 2 is a dielectric plate made of a second metamaterial, 3 is a dielectric plate made of a third metamaterial, and 4 is a plurality of frequency bands. A multi-frequency or broadband antenna that operates. In addition, the dielectric plates 1 to 3 are provided in parallel to a plane (YZ plane) perpendicular to the signal transmission / reception direction (X-axis direction). Here, as described in Non-Patent Document 1 (page 14), the metamaterial is a substance having an artificial periodic structure having a property that does not exist in nature, and has a dielectric constant ε and a magnetic permeability μ. Both have negative values and are also called negative refractive index substances.

  The dimensions (W1 to W3, L1 to L3) of the dielectric plates 1 to 3 made of the first to third metamaterials are set so as to be substantially the same in wavelength ratio at the center frequency of each frequency band. ing. That is, the dimensions (W1 to W3, L1 to L3) of the dielectric plates 1 to 3 made of the first to third metamaterials are the same in terms of wavelength at the center frequency of each frequency band.

  Further, the distances (D1 to D3) between the dielectric plates 1 to 3 made of the first to third metamaterials and the antenna 4 are substantially equal in wavelength ratio at the center frequency of each frequency band. Is set to That is, the dielectric plates 1 to 3 are arranged in the order of the dielectric plate 3, the dielectric plate 2, and the dielectric plate 1 in the order from the antenna 4 in the signal transmission direction (X-axis direction) (distance D3). <D2 <D1).

  In addition, the dimensions (W1 to W3, L1 to L3) of the dielectric plates 1 to 3 are increased in the order of decreasing reflection frequency. Here, the dimensions (W1 to W3, L1 to L3) of the dielectric plates 1 to 3 and the distances (D1 to D3) with respect to the antenna 4 are simulation results or measured values according to the center frequency of the signal to be transmitted and received It is determined based on.

  FIG. 2 is a schematic diagram illustrating a structure example of the dielectric plates 1 to 3 made of the first to third metamaterials. As shown in FIGS. 2A to 2D, the dielectric plates 1 to 3 made of the first to third metamaterials are arranged so that the dielectrics have a periodic structure. 2A to 2D, the XYZ orthogonal coordinate system shown is the same as the XYZ orthogonal coordinate system shown in FIG. 1, and the metamaterial shown in FIGS. 2A to 2D is the YZ plane. The structure of the parallel dielectric plates 1-3 is shown.

In FIG. 2A, cylindrical dielectrics are arranged at equal intervals in a matrix on the XY plane, and the central axes of the cylindrical shapes are perpendicular to the signal transmission direction (X-axis direction) and are mutually connected. The structure by the dielectric material arrange | positioned so that the center axis | shaft may become parallel may be shown.
FIG. 2B shows that prismatic dielectrics are arranged at equal intervals in parallel to the first axial direction (Z-axis direction) on a first plane parallel to the YZ plane. Thickness of lattice shapes arranged at equal intervals in parallel to the direction (Y-axis direction) perpendicular to the first axis direction on the second plane parallel to the YZ plane that differs in the thickness direction (X-axis direction) A structure periodically repeated in the direction is shown. Further, the prismatic dielectric disposed on the first plane and the prismatic dielectric disposed on the second plane are disposed in contact with each other.

FIG. 2C shows a plate-like dielectric having a cylindrical hole whose center axis is a direction perpendicular to the signal transmission direction (X-axis direction) and whose center axes are parallel to each other in the XY plane. A structure provided in a matrix at intervals is shown.
FIG. 2D shows a structure in which a plurality of spherical dielectrics form a face-centered cubic lattice structure to constitute a dielectric plate.
2A to 2C is determined according to the center frequency of the reflected frequency band. Further, the radius of the spherical shape of the dielectric in the structure of FIG. 2D is determined according to the center frequency of the frequency band to be reflected. Moreover, the dielectric material which has the dielectric constant (epsilon) defined according to the center frequency of the frequency band to reflect is selected as the dielectric material which comprises the dielectric plates 1-3.

  FIG. 3 is a conceptual diagram showing transmission coefficients of the dielectric plates 1 to 3 made of the first to third metamaterials of the antenna device according to the first embodiment. When evaluated at −10 dB, three band gaps (bands through which radio waves do not pass) are formed. The dielectric plate 1 made of the first metamaterial is designed to have a small transmission coefficient in the band of the center frequency F1.

  Therefore, in this band, electromagnetic waves can be reflected by the dielectric plate 1 and transmitted through the dielectric plate 1 at frequencies other than the band gap band. That is, the dielectric plate 1 operates equivalently to a metal reflector in the band gap band. Similarly, the second and third dielectric plates 2 and 3 form a band gap in the bands of the center frequencies F2 and F3, and operate equivalently to the metal reflector in each band.

  FIG. 4 is a conceptual diagram showing a radiation pattern in the horizontal plane of the antenna device according to the first embodiment. The dimensions of the dielectric plates 1 to 3 made of the first to third metamaterials, and the distance between the dielectric plates 1 to 3 and the antenna 4 are substantially the same in wavelength ratio at the center frequency of each band gap frequency band. Therefore, the same horizontal plane radiation pattern and beam width can be realized in the three frequency bands.

  In the first embodiment described above, an example in the case of having the same in-plane radiation pattern and beam width in three frequency bands, that is, a case of a three-frequency shared antenna device has been described. The same applies to the shared antenna element by adding a dielectric plate made of a metamaterial. The structure example of the dielectric plate made of the metamaterial is not limited to that shown in FIG. 2, and various structures and combinations thereof are conceivable.

  In the first embodiment, the case where a dielectric plate made of three metamaterials is used as an example in the case of a three-frequency shared antenna device is taken as an example, but the dielectric plate made of a metamaterial having the maximum dimension is used. Even if (the dielectric plate 1 in FIG. 1) is replaced with a normal metal reflector, the same horizontal plane radiation pattern and beam width may be obtained.

B. Second Embodiment Next, a second embodiment of the present invention will be described.
FIG. 5 is a schematic diagram showing the configuration of the antenna device according to the second embodiment. The antenna device according to the second embodiment is an application example to a corner reflector antenna. FIG. 5A is a diagram illustrating the shape of the antenna device of the present embodiment in plan view in the X-axis direction. FIG. 5B is a perspective view of the antenna device. FIG. 5C is a diagram illustrating the shape of the antenna device in plan view in the Z-axis direction.
In FIG. 5, 5 is a dielectric plate made of a first metamaterial, 6 is a dielectric plate made of a second metamaterial, 7 is a dielectric plate made of a third metamaterial, and 8 is a plurality of frequency bands. It is a multi-frequency shared antenna or a broadband antenna that operates.

  The dielectric plates 5 to 7 made of the first to third metamaterials are V-shaped by bending a rectangular flat plate into two along a bending axis (Z axis) parallel to one side of the rectangular shape. It has a shape. Further, the width and length (W5 to W7, L5 to L7) of each of the two surfaces formed by bending the dielectric plates 5 to 7 and the distance between the dielectric plates 5 to 7 and the antenna 8 (D5 to D5). D7) is set such that the distance is substantially the same in wavelength ratio at the center frequency of each frequency band. That is, the width and length (W5 to W7, L5 to L7) of each of the two surfaces formed by bending the dielectric plates 5 to 7 are the centers of the frequency bands reflected by the dielectric plates 5 to 7, respectively. It has the same dimension in terms of wavelength in frequency.

Further, the two surfaces formed by bending the dielectric plates 5 to 7 are bent so as to be symmetric with respect to the bending axis. Further, the apex angles (α5 to α7) of the corner reflector are set to be the same opening angle.
Here, the dimensions (W5 to W7, L5 to L7) of the dielectric plates 5 to 7, the vertex angle (α5 to α7) of the corner reflector, and the distance (D5 to D7) with the antenna 4 are signals to be transmitted and received. It is determined based on the result of the simulation or the actual measurement value according to the center frequency.

  Thus, even when applied to a corner reflector antenna, three band gaps (bands through which radio waves do not pass) can be obtained as in FIG. 3, and within each band, electromagnetic waves are transmitted through the dielectric plate 5. The electromagnetic waves can be transmitted through the dielectric plates 5 to 7 at a frequency other than the band gap band. Therefore, similarly to the radiation pattern shown in FIG. 4, the same horizontal plane radiation pattern and beam width can be realized in the three frequency bands.

  According to the antenna device of the first and second embodiments described above, a plurality of dielectric plates having a metamaterial structure can be used instead of the conventional dipole antenna with reflector and the metal reflector of the corner reflector antenna. By installing a considerable number of desired frequency bands so that a band gap (a band through which radio waves do not pass) is formed in the desired frequency band, a dielectric plate having a metamaterial structure is provided in each band. It is possible to operate equivalent to a metal reflector.

  As a result, the same horizontal plane radiation pattern and beam width can be realized in a plurality of frequency bands. Therefore, a dipole antenna with a reflector and a corner reflector antenna are designed for each desired frequency band. There is no need, and a single antenna device can share a plurality of frequencies, and the efficiency of antenna installation space can be improved.

1, 2, 3, 5, 6, 7 ... Dielectric plates 4, 8 ... Antenna

Claims (8)

A plurality of dielectric plates made of metamaterials;
Multi-frequency shared or broadband antenna that operates in multiple frequency bands
Comprising
The plurality of dielectric plates are installed in a number corresponding to the number of the plurality of frequency bands so that band gaps are formed in the plurality of frequency bands,
Each of the plurality of dielectric plates is
Has a rectangular shape,
The sides of the rectangular shape, the different sides orthogonal to the one side, and the respective lengths are the same in terms of wavelength at the center frequency of the frequency band to be reflected among the plurality of frequency bands,
The distance between the antenna, in a position the same distance in your Keru wavelength converted to the center frequency of the frequency band to be reflected out of said plurality of frequency bands, said plurality of dielectric plates are parallel to each other features and to Rua antenna device. A plurality of dielectric plates made of metamaterials;
Multi-frequency shared or broadband antenna that operates in multiple frequency bands
Comprising
The plurality of dielectric plates are installed in a number corresponding to the number of the plurality of frequency bands so that band gaps are formed in the plurality of frequency bands,
Each of the plurality of dielectric plates is
A rectangular planar plate has a V-shape bent in two at the same angle along a folding axis parallel to one side of the planar plate,
The sides of the rectangular shape, the different sides orthogonal to the one side, and the respective lengths are the same in terms of wavelength at the center frequency of the frequency band to be reflected among the plurality of frequency bands,
The distance between the antenna is placed at a position the same distance in your Keru wavelength converted to the center frequency of the frequency band to be reflected out of said plurality of frequency bands,
It said plurality of said bending axis of the dielectric plate, characterized and to luer antenna device that are coplanar. The antenna device according to claim 1 or claim 2, characterized in that the largest dielectric plate of the plurality of dielectric plates was replaced by a reflection plate made of a metal. The antenna device according to any one of claims 1 to 3 , wherein the plurality of dielectric plates have a metamaterial structure in which dielectrics are arranged to have a periodic structure. 5. The antenna according to claim 4 , wherein the plurality of dielectric plates have a metamaterial structure in which cylindrical dielectrics are arranged in a matrix in parallel with the central axis of each cylindrical shape. apparatus. In the plurality of dielectric plates, prismatic dielectrics are arranged in parallel and at equal intervals in the first plane, and are arranged in the first plane in different second planes parallel to the first plane. and a dielectric lattice shape equally spaced and orthogonal to claim 4, characterized in that it comprises a structure of metamaterial repeated in a direction perpendicular to the first plane and the second plane The antenna device described. Wherein the plurality of dielectric plates, according to claim 4, characterized in that it comprises a structure of metamaterial central axis of each other in a plate-shaped dielectric body is provided with parallel cylindrical pores in a matrix Antenna device. The antenna device according to claim 4 , wherein the plurality of dielectric plates have a metamaterial structure in which a plurality of spherical dielectrics are arranged in a face-centered cubic lattice.

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