JP2009130451A - Antenna system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a base station antenna device capable of achieving a wide half width of not less than 100° in a horizontal plane by improving F/B ratio of radiation pattern characteristics. <P>SOLUTION: The antenna device 100 is provided with: a first reflection plate 10 having a side surface portion of 0.1-0.25 λ height formed on both ends in a longitudinal direction, and having 0.5-1.5 λ width; a second reflection plate 20 having a side surface portion of 0.25-0.5 λ height formed on both ends in a longitudinal direction, and having 1-2 λ width; an antenna 301 disposed on the center axis of the first reflection plate 10 in the longitudinal direction so as to be spaced at 0.2-0.3 λ from the first reflection plate 10; and a parasitic element 40 disposed on the center axis of the first reflection plate 10 in the longitudinal direction so as to be spaced at 0.5-1 λ from the first reflection plate 10. The directivity and radiation pattern of the antenna are controlled with the first reflection plate 10, the second reflection plate 20 and the parasitic element 40, and the excellent F/B ratio and the wide half width can be achieved. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an antenna device for a wireless device, and more particularly to a base station antenna device in a mobile communication system.

  Since a base station antenna of a mobile communication system requires a directional radiation pattern, in general, dipole antennas and patch antennas are arranged on a metal ground plane as an array antenna, and the ground plane is used as a reflector. It has been practiced to provide directivity or to attach directivity by attaching a rod-like or plate-like reflector near the collinear array antenna in which half-wave dipole antennas are stacked in multiple stages.

  In addition, if radio waves other than its own sector are received by a terminal in a certain sector zone, noise or disconnection during communication may occur due to radio wave interference, or call quality may be degraded such as unsatisfactory handover. The directional base station antenna is required to improve the F / B (Front to Back) ratio and suppress the radiation pattern to the direction other than the own sector as low as possible. Also, in order to cover a wide range of the sector area, it is desirable to make the half width of the radiation pattern of the base station antenna as wide as possible.

In view of such a situation, for example, an antenna device that realizes an improvement in the F / B ratio as described in Patent Documents 1 and 2, and a half-value width adjustment as described in Patent Documents 3 and 4 are realized. Antenna devices have been developed.
JP 2002-141742 A JP 2003-264426 A JP 2003-32031 A JP 2007-19615 A

  Patent Document 1 describes a reflector-equipped dipole antenna device that can adjust the half-value width of directivity in a horizontal plane without replacing an existing antenna. Patent Document 2 describes a half-wave dipole antenna that is small and has a large FB ratio. However, when these techniques are used to improve the F / B ratio, there is a problem that the ground plane of the antenna becomes large and a large number of parts are required, which increases the design difficulty.

Patent Document 3 describes a dipole antenna device in which the gain of the back surface is suppressed, and Patent Document 4 describes a dipole antenna that is optimal for a horizontally polarized element of a polarization sharing antenna in which a large number of elements are arranged. Although the half width is adjusted, if these techniques are used to widen the half width, there is a problem that the F / B ratio deteriorates due to a trade-off relationship.
Therefore, the present invention can realize both an improvement in the F / B ratio and a wide radiation pattern half width, and can change the radiation pattern half width in a state where the F / B ratio is improved. The purpose is to provide.

  In order to achieve this object, the antenna device provided by the present invention has side portions with heights of 0.1 to 0.25λ formed at both ends in the longitudinal direction, and has a width of 0.5 to 1.5λ. A rectangular first reflector having a height of 0.25 to 0.5λ formed at both ends in the longitudinal direction, a square second reflector having a width of 1 to 2λ, and a first And an antenna element disposed on the central axis in the longitudinal direction of the reflector at a distance of 0.2 to 0.3λ from the first reflector, and the first reflector has a side surface portion of the second reflector and the first element. The first reflector is disposed on the second reflector such that a gap of 0.25 to 0.5λ is provided between the side and the side of the reflector.

The antenna device may further include a radome that covers the first reflector, the second reflector, and the antenna element.
The antenna device may further include a parasitic element disposed on the central axis in the longitudinal direction of the first reflecting plate and spaced from the first reflecting plate by 0.5 to 1λ.
The parasitic element may have a circular rod shape with a diameter of 0.05λ or less or a flat plate shape with a width of 0.05λ or less.
Further, the second reflecting plate and the parasitic element may be formed integrally with the radome.

According to the antenna device of the present invention, it is possible to improve the F / B ratio of the radiation pattern characteristics and realize a wide half-value width of 100 ° or more in the horizontal plane. In addition, the full width at half maximum in the horizontal plane can be freely varied within a range of 60 ° to 140 °, and the same effect can be obtained regardless of the type of antenna used, such as a dipole antenna, a cross dipole antenna, or a patch antenna. Is possible.
Furthermore, the antenna device of the present invention has a higher degree of design freedom than a conventional similar antenna device, and can easily tune electrical characteristics according to the application.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1A is a schematic diagram of an antenna device according to a first embodiment of the present invention. As shown in the figure, the antenna device 100 includes a first reflecting plate 10 and a second reflecting plate 20 made of metal, a dipole antenna 301, and a parasitic element 40. Both sides of the first reflector 10 and the second reflector 20 are bent to form side portions.

  Here, the dimensions of each part of the antenna device 100 are the electrical length of the operating frequency, the width W1 of the first reflector 10 is 0.5 to 1.5λ, the width W2 of the second reflector 20 is 1 to 2λ, The height H1 of the side surface of the first reflector 10 is 0.1 to 0.25λ, the height H2 of the side surface of the second reflector 20 is 0.25 to 0.5λ, and the first reflector 10 and the second reflection. The distance D between the side surfaces of the plate 20 is 0.25 to 0.5λ, the distance L1 between the first reflector 10 and the dipole antenna 301 is 0.2 to 0.3λ, and the first reflector 10 The distance L2 between the side surface portion and the side surface portion of the parasitic element 40 is 0.5 to 1λ on both side surfaces, and the diameter φ of the circular rod-shaped parasitic element 40 is 0.05λ or less. The parasitic element 40 may have a flat plate shape with a width of 0.05λ or less.

The dipole antenna 301 and the parasitic element 40 are disposed on the central axis of the first reflecting plate 10 while being separated from the first reflecting plate 10 by distances L1 and L2, respectively. Although the dipole antenna 301 is used here, the shape of the antenna to be used is not limited to this. This point will be described later.
A power supply circuit (not shown) is provided on the back side of the first reflecting plate 10, and power is supplied to the antenna via a connector or the like.

  FIG. 1B is a perspective view of the antenna device 100. A dipole antenna array is constituted by a plurality of dipole antennas 30 on the central axis of the first reflector 10. A parasitic element 40 is disposed on the central axis of the first reflector 10 and above the dipole antenna array. If the dipole antenna 30 is a printed circuit board type, it is easy to handle and the antenna device 100 can be easily assembled. However, the method of forming the dipole antenna 301 is not limited to this.

  In the antenna device 100 having such a configuration, the first reflector 10 is used to provide directivity to the horizontal omnidirectional dipole antenna 301. The second reflector 20 is for improving the F / B ratio by controlling the radiation pattern behind the antenna. Furthermore, since the 1st reflective plate 10 and the 2nd reflective plate 20 have a side part, the wraparound of a radiation pattern is suppressed and optimal control is implement | achieved. The parasitic element 40 is arranged to finely adjust the radiation pattern in front of the antenna and plays a role similar to a reflector.

  By making an arbitrary setting within the above-described range of the dimensions of each part, the antenna device 100 can improve the F / B ratio and adjust the radiation pattern. For example, solid lines in FIG. 3 indicate that the dimensions of each part of the antenna apparatus 100 shown in FIG. 1 are W1: 1.5λ, W2: 2λ, H1: 0.25λ, H2: 0.25λ, D: 0. This is a radiation pattern characteristic in a horizontal plane when designed as 25λ, L2: 0.75λ, and φ: 0.015λ. At this time, as shown in the drawing, it is possible to obtain a radiation pattern characteristic having a half-value width of about 120 ° in a horizontal plane.

  On the other hand, the broken line in FIG. 3 shows the radiation pattern characteristics of a general dipole array antenna device. The antenna device 104 is schematically shown in FIGS. 2 (a) and 2 (b). The antenna device 104 is configured by installing a dipole antenna 301 at the center on a flat ground plane. The width of the ground plane is 1.5λ, and the distance between the ground plane and the dipole antenna is 0.25λ.

When the antenna device 100 and the antenna device 104 are compared, the radiation pattern of the main lobe is hardly changed, and any antenna device can obtain a radiation pattern characteristic having a half width of about 120 ° in the horizontal plane. On the other hand, it can be seen that the F / B ratio is improved in the antenna device 100 compared to the antenna device 104.
As described above, according to the antenna device of the present invention, when a wide half width of 100 ° or more is required, a favorable F / B ratio can be obtained as compared with a general dipole array antenna.

  FIG. 4 shows the radiation pattern characteristics in the horizontal plane obtained by designing by changing the electrical length dimension of each part within the range shown in FIG. As shown in the figure, it is possible to freely design the antenna device 100 in which the full width at half maximum in the horizontal plane is about 60 ° to 140 ° by appropriately changing the dimensions of each part. In recent years, base station antennas are assumed to be used in various situations, and variations of antennas having different half widths are required. According to the antenna device 100 of the present invention, it is possible to design an antenna with a good F / B ratio by selecting the half width of the radiation pattern in response to such a current situation.

  Next, a second embodiment of the present invention will be described. FIG. 5 shows an antenna device having the same configuration as that of the antenna device 100 shown in FIG. 1, and uses a cross dipole antenna 302 instead of the dipole antenna 301. In the antenna device 101, a cross dipole array antenna for ± 45 ° polarization is formed on the first reflector 10 by a plurality of cross dipole antennas 302. The electrical length dimension range of each part is the same as that of the antenna device 100.

  According to the antenna device 101, electrical characteristics substantially equivalent to the electrical characteristics of the antenna device 100 shown in FIG. 3 can be obtained. Although the plane of polarization is different from that of the dipole array antenna used in the antenna device 100, the radiation pattern is determined according to the structure of the reflector.

  Subsequently, a third embodiment of the present invention using a patch antenna will be described. 6A and 6B show an antenna device having the same configuration as that of the antenna device 100 described above, using a patch antenna 303 instead of the dipole antenna 301. FIG. In this antenna device 102, a patch antenna array is formed on the first reflector 10 by a plurality of patch antennas 303. As in the third embodiment, the electrical length dimension range of each part is the same as that of the antenna device 100.

  The radiation pattern characteristics in the horizontal plane of the antenna device 102 are shown in FIG. As shown in the figure, when the patch antenna 303 is used, the half-value width characteristic tuning range is narrower than that of the antenna device 100 or the like, but the half-value width in the horizontal plane is approximately 60 ° to 100 °, which is sufficient. The antenna device 102 can have a wide half-value width.

  Thus, in the antenna device of the present invention, the shape of the antenna to be used is not limited to a dipole antenna, and various antennas such as a cross dipole antenna and a patch antenna can be used. In addition, when any antenna is used, the same effect as when using a dipole antenna can be obtained.

By the way, the antenna devices 100 to 102 described as the first to third embodiments are actually used with a radome. Therefore, FIG. 8 is a schematic view showing an actual usage form of the antenna device of the present invention, that is, a form at the time of commercialization.
The antenna device 103 includes a radome 50 that covers the first reflecting plate 10, the second reflecting plate 20, the antenna 30, and the parasitic element 40. As the antenna 30, for example, a dipole antenna, a cross dipole antenna, a patch antenna, or the like can be used as described above.

Here, the parasitic element 40 and the second reflecting plate 20 may be formed by metallization coating directly on the top and bottom surfaces of the radome 50 by spray gun painting or the like. Alternatively, the radome 50 may be formed by attaching or assembling a metal rod or metal plate. Alternatively, it may be formed by assembling a resin having a pattern wiring by a MID (Molded Interconnect Device) technique.
Further, depending on the shape of the radome 50, the parasitic element 40 is not disposed, and an antenna device in which the first reflecting plate 10, the second reflecting plate 20, and the antenna 30 are covered with the radome 50 is configured. It is also possible to obtain

  Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments and can be implemented in various ways.

(A) is the schematic of the 1st Example of the antenna apparatus of this invention, (b) is a perspective view. (A) is the schematic of a general dipole array antenna apparatus, (b) is a perspective view. The figure which shows the directional half value width in a horizontal surface in the antenna apparatus by the 1st Example of this invention, and a general dipole antenna apparatus. The figure which shows the directivity half value width in a horizontal surface in the 1st Example of the antenna apparatus of this invention. The perspective view of the 2nd Example of the antenna device of this invention. (A) is the schematic of the 3rd Example of the antenna apparatus of this invention, (b) is a perspective view. The figure which shows the directivity half value width in a horizontal surface in the 3rd Example of the antenna apparatus of this invention. Schematic of the usage pattern of the antenna device of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Antenna apparatus 10 1st reflecting plate 20 2nd reflecting plate 301 Antenna element 40 Parasitic element

Claims (6)

A rectangular first reflector having side portions of height 0.1 to 0.25λ formed at both ends in the longitudinal direction and having a width of 0.5 to 1.5λ;
A rectangular second reflecting plate having side portions of height 0.25 to 0.5λ formed at both ends in the longitudinal direction and having a width of 1 to 2λ;
An antenna element disposed on the central axis in the longitudinal direction of the first reflector and spaced from the first reflector by 0.2 to 0.3λ;
With
The first reflector is disposed on the second reflector such that a gap of 0.25 to 0.5λ is provided between the side surface of the second reflector and the side surface of the first reflector. An antenna device characterized by being placed on top of each other. The antenna device according to claim 1,
An antenna device, further comprising a radome that covers the first reflector, the second reflector, and the antenna element. The antenna device according to claim 1 or 2,
An antenna device, further comprising a parasitic element disposed on a central axis in a longitudinal direction of the first reflecting plate and spaced apart from the first reflecting plate by 0.5 to 1λ. The antenna device according to claim 3, wherein
The parasitic element is a circular rod having a diameter of 0.05λ or less. The antenna device according to claim 3, wherein
The parasitic element has a flat plate shape with a width of 0.05λ or less. The antenna device according to any one of claims 3 to 5,
The antenna device, wherein the second reflector and the parasitic element are formed integrally with the radome.

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