JP5827470B2 - Sector antenna - Google Patents

Description

  The present invention relates to a sector antenna including a frequency sharing dipole element for transmitting and receiving horizontally polarized waves in a plurality of frequency bands.

  In recent years, mobile communication terminals such as mobile phones are rapidly spreading, and high-speed data communication is performed by sharing frequencies of, for example, 800 MHz band, 1.5 GHz band, and 2 GHz band.

  A sector antenna as shown in FIG. 7A is an antenna device that performs horizontal polarization transmission / reception with such a mobile communication terminal in a plurality of frequency bands (for example, 1.5 GHz band and 2 GHz band). The sector antenna is an antenna device for performing transmission / reception with respect to a sector sector having a predetermined angle with the antenna at the center (vertex) (see, for example, Patent Document 1).

  A sector antenna 70 having a conventional structure shown in FIG. 7A includes a frequency sharing dipole element 11 that transmits and receives 1.5 GHz and 2 GHz band horizontal polarization, and a first reflection disposed along the frequency sharing dipole element 11. The plate 12, the pair of second reflecting plates 13 c and 13 c disposed on the first reflecting plate 12 outside the both ends 14 and 14 of the frequency sharing dipole element 11, and the both ends of the first reflecting plate 12 The side reflector 15 is provided.

  Horizontally polarized light radiated from the sector antenna 70 is reflected by the first reflector 12 in the main radiation direction 16 (in the direction of the center of the sector) and has a beam width depending on the distance between the pair of second reflectors 13c and 13c. Is adjusted to be the same as the angle of the sector, and the side reflector 15 suppresses the wraparound of the horizontally polarized wave to the antenna back surface.

  The sector antenna 70 radiates horizontally polarized waves of 1.5 GHz band and 2 GHz band with radiation characteristics as shown in FIG.

  Combining a plurality of such sector antennas (for example, three in a 120-degree sector sector) covers a 360-degree omnidirectional communication area.

Japanese Patent Laid-Open No. 2007-60062

  By the way, for the convenience of area design, it may be required to make the beam widths approximately equal in a plurality of frequency bands, and to make the beam width wider in the higher frequency band.

  However, the conventional sector antenna structure has a problem that the beam width is generally narrow in the higher frequency band.

  The beam width of the horizontally polarized wave is adjusted by changing the interval between the second reflectors. However, in the conventional sector antenna, the beam width of the higher frequency band is the first even if the interval between the second reflectors is changed. Regardless of the interval between the two reflectors, it is always narrower than the lower frequency band.

  For example, in the sector antenna 70 having the conventional structure shown in FIG. 7, the normalized radiation gain (beam width) of the horizontal polarization in the 2 GHz band is narrower than the 1.5 GHz band. The same beam width cannot be obtained.

  For this reason, when the interval of the second reflector 13c is adjusted so that the beam width of the horizontally polarized wave in the 2 GHz band is the same as the angle of the sector, the beam width in the 1.5 GHz band becomes wider than the angle of the sector. When a plurality of sector antennas 70 are used in combination, the 1.5 GHz band interferes in the vicinity of the boundary between adjacent sector sectors.

  On the other hand, when the interval of the second reflector 13c is adjusted so that the beam width of the horizontally polarized wave in the 1.5 GHz band is the same as the angle of the sector, the beam width in the 2 GHz band becomes narrower than the angle of the sector. A dead zone of 2 GHz band is formed in the vicinity of the sector boundary.

  The present invention has been made to solve the above problems, and when transmitting and receiving horizontal polarization in a plurality of frequency bands, the beam widths of different frequency bands are made approximately equal, and in the higher frequency band, An object of the present invention is to provide a sector antenna capable of further widening the beam width.

In order to achieve the above object, the present invention provides a frequency sharing dipole element that transmits and receives horizontally polarized waves in a plurality of frequency bands, and is disposed along the frequency sharing dipole element and apart from the frequency sharing dipole element, A first reflector that reflects horizontally polarized waves from a frequency sharing dipole element; and a non-conducting state with the first reflector between the frequency sharing dipole element and the first reflector; and the frequency A pair of second reflectors disposed upright on both ends of the common dipole element, wherein the plurality of frequency bands are 1.5 GHz band and 2 GHz band, and the pair of second reflectors reflector state, and are not to adjust the beam width of the horizontal polarization of the plurality of frequency bands, the plurality of or equal approximate beamwidth of the horizontal polarization in the frequency band, or of the plurality of frequency bands A lower sector antenna to widen the beam width of the horizontal polarization than the frequency band of the plurality of frequency bands in the frequency band have ways.

  The pair of second reflectors may be disposed to be inclined outward so that a distance between the pair of second reflectors increases toward the frequency sharing dipole element.

The first reflector may be provided with side reflectors at both ends in the outer direction.
The side reflecting plate may be disposed outside the pair of second reflecting plates.

  It is good to have a plane symmetry shape with respect to the central plane perpendicular to the first reflector and the horizontal plane.

There are a plurality of the frequency sharing dipole elements, and the frequency sharing dipole elements are preferably arranged such that their longitudinal directions are respectively horizontal and parallel to the vertical direction.
The first reflector may be arranged so as to be parallel to each of the plurality of frequency sharing dipole elements.
Horizontally polarized beam widths are approximately equal in the plurality of frequency bands, or horizontally polarized beams in a higher frequency band of the plurality of frequency bands than in a lower frequency band of the plurality of frequency bands. Wide is good.

  According to the present invention, when horizontally polarized waves are transmitted and received in a plurality of frequency bands, the beam widths of different frequency bands can be made substantially equal, and the beam width can be made wider in the higher frequency band. A sector antenna can be provided.

(A) is a perspective view showing the structure of the sector antenna according to the first embodiment, (b) is a sectional view taken along the line AA of (a), and (c) is a horizontal deviation of the sector antenna. It is a figure showing the radiation characteristic of a wave by the normalized radiation gain. (A) is a schematic sectional drawing which shows the structure of the sector antenna which concerns on 2nd embodiment, (b) is a figure showing the radiation characteristic of the horizontal polarization of the sector antenna by the normalized radiation gain. (A) is a schematic sectional drawing of the sector antenna of an Example, (b) is the dimension drawing. It is a figure which shows the relationship between the space | interval of the 2nd reflector of the sector antenna of an Example, and beam width. (A) is a schematic sectional drawing of the sector antenna of a comparative example, (b) is the dimension drawing. It is a figure which shows the relationship between the space | interval of the 2nd reflector of the sector antenna of a comparative example, and beam width. (A) is a schematic sectional drawing which shows the structure of the sector antenna of the conventional structure, (b) is a figure showing the radiation characteristic of the horizontal polarization of the sector antenna by the normalized radiation gain.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  FIG. 1A is a perspective view showing a structure of a sector antenna according to the first embodiment, FIG. 1B is a sectional view taken along line AA in FIG. 1A, and FIG. It is a figure showing the radiation characteristic of horizontal polarization by standardized radiation gain. Here, the normalized radiation gain is standardized with the main radiation direction of the sector antenna being 0 degree and the radiation gain in the main radiation direction being 0 dB.

  As shown in FIG. 1A, a sector antenna 10 according to the present embodiment includes a plurality of frequency sharing dipole elements 11, a first reflector 12, and a pair of second reflectors 13n and 13n. Prepare mainly.

  The plurality of frequency sharing dipole elements 11 are arranged in parallel in the vertical direction (Z direction in FIG. 1A). Further, the frequency sharing dipole element 11 is arranged so that its longitudinal direction is the horizontal direction (X direction in FIG. 1A), and can transmit and receive horizontal polarization. In the present embodiment, the frequency sharing dipole element 11 is configured to transmit and receive horizontal polarization using both the 1.5 GHz band and the 2 GHz band.

  The first reflector 12 is disposed along the frequency sharing dipole element 11 and spaced from the frequency sharing dipole element 11, and is electrically connected to a ground (not shown). The first reflector 12 is for reflecting the horizontally polarized waves of a plurality of frequency bands radiated from the frequency sharing dipole element 11 in the main radiation direction 16. In the present embodiment, the first reflecting plate 12 is disposed so as to be parallel to the plurality of frequency sharing dipole elements 11.

  The pair of second reflecting plates 13n and 13n are disposed upright outside the both ends 14 and 14 of the frequency sharing dipole element 11 in a space between the frequency sharing dipole element 11 and the first reflecting plate 12. At the same time, it is disposed in a non-conductive state with respect to the first reflector 12 and the ground. The second reflector 13n is for individually adjusting the beam width of the horizontally polarized wave for each frequency band.

  Moreover, the 1st reflecting plate 12 is equipped with the side surface reflecting plates 15 and 15 in the both ends of an outer side direction (left-right direction in FIG.1 (b)). The side reflector 15 is for suppressing the sneaking of the horizontally polarized wave toward the back surface of the first reflector 12.

  In addition, the sector antenna 10 has a frequency sharing dipole element 11 and a first reflection so as to be symmetrical with respect to a central plane perpendicular to the first reflector 12 and a horizontal plane (XY plane in FIG. 1B). The shapes and arrangement positions of the plate 12, the second reflecting plate 13n, and the side reflecting plate 15 are determined. Thereby, the horizontally polarized beam in the sector can be made uniform.

  Note that the present invention does not particularly limit the means for disposing the second reflector 13n in a non-conductive state, and for example, a resin spacer 17 or the like can be used.

  As a result, the sector antenna 10 according to the present embodiment has a 2 GHz band without increasing the 1.5 GHz beam width (normalized radiation gain) as shown in FIG. The beam width can be expanded and the beam widths of both frequency bands can be made approximately equal.

  Regarding the action of the second reflector 13n, the inventors have increased the beam width because the intensity of the current distribution excited by the second reflector 13n by the horizontally polarized wave in the 2 GHz band is larger than the 1.5 GHz band. I guess.

  Next, a second embodiment of the present invention will be described.

  As shown in FIG. 2A, the sector antenna 20 according to the present embodiment has the same basic structure as that of the sector antenna 10 of the first embodiment, and also with respect to the first reflector 12 and the ground. In a non-conducting state, a pair of second reflecting plates 13t and 13t are provided in a space between the frequency sharing dipole element 11 and the first reflecting plate 12. The pair of second reflectors 13t and 13t stand outside the both ends 14 and 14 of the frequency sharing dipole element 11 and outward so that the distance between them increases toward the frequency sharing dipole element 11. Inclined.

  As a result, the sector antenna 20 according to the present embodiment has a 2 GHz band without increasing the beam width (normalized radiation gain) of the 1.5 GHz band as shown in FIG. The beam width can be made wider than the 1.5 GHz band.

  Here, Table 1 shows the 3 dB beam width (angle of normalized radiation gain-3 dB) of 1.5 GHz band and 2 GHz band horizontal polarization of the sector antennas 10 and 20 of the present invention and the sector antenna 70 of the conventional structure. .

  As shown in Table 1, the sector antenna 70 (conventional) having a conventional structure in which the second reflector 13c is disposed in a conductive state with respect to the first reflector 12 and the ground has a 3 dB beam width of 73 in the 1.5 GHz band. It can be seen that the 2 GHz band is 68 degrees, whereas the beam width is narrower in the higher frequency band.

  On the other hand, the sector antenna 10 (invention 1) in which the second reflector 13n is disposed in a non-conducting state with respect to the first reflector 12 and the ground has a 3 GHz beam width of 73 degrees in the 1.5 GHz band obtained by the conventional structure. It can be seen that the 3 dB beam width in the 2 GHz band is widened to 73 degrees, the same as in the 1.5 GHz band, without changing.

  In addition, the sector antenna 20 (invention 2) in which the second reflector 13t is disposed in a non-conductive state and inclined outward with respect to the first reflector 12 and the ground is 1.5 GHz band obtained by a conventional structure. It can be seen that the 3 dB beam width of the 2 GHz band is further expanded without changing the 3 dB beam width of 73 degrees to 76 degrees, which is larger than the 1.5 GHz band.

  In short, in the sector antenna of the present invention, the second reflecting plate 13n is disposed in a non-conductive state with respect to the first reflecting plate 12 and the ground without changing the beam width of the horizontally polarized wave in the low frequency band. It is possible to make the beam widths of both frequency bands substantially the same.

  Further, by disposing the second reflecting plate 13t in a non-conductive state with respect to the first reflecting plate 12 and the ground and tilting outward, without changing the beam width of the horizontally polarized wave in the low frequency band, It is possible to widen the beam width in the high frequency band than in the low frequency band.

  The present invention is not limited to the above-described embodiment, and can be applied to a sector antenna sharing another frequency band such as an 800 MHz band.

  Examples of the present invention will be described below.

[Example]
As shown in FIG. 3A, the first reflector 12 (width: 184 mm) is disposed 40 mm apart from the frequency sharing dipole element 11 sharing the horizontal polarization of 1.5 GHz band and 2 GHz band in parallel. In addition, a pair of second reflectors 13t (width: about 31.6 mm) is placed between the first reflector 12 and the frequency sharing dipole element 11 so that the distance from the first reflector 12 is 5 mm. The sector antenna 20 according to the second embodiment is configured in a conductive state. The first reflector 12 has side reflectors 15 having a height of 5 mm at both ends, and was electrically connected to the ground. The pair of second reflecting plates 13t and 13t are spaced apart by an inner width of 116 mm and are inclined at an angle of about 18.4 degrees so that the outer width is 136 mm. Here, the second reflecting plate 13t is fixed on the first reflecting plate 12 using a resin spacer so as to be in a non-conductive state with respect to the first reflecting plate 12 and the ground. The dimensions of the sector antenna 20 are shown in FIG.

  When the radiation characteristics of the sector antenna configured as described above were evaluated, the normalized radiation gain as shown in FIG. 2B was obtained, and the 3 dB beam width in the 1.5 GHz band was 73 degrees. Thus, the 3 GHz beam width in the 2 GHz band was 76 degrees, and the beam width in the high frequency band could be made wider than the beam width in the low frequency band.

  Furthermore, the radiation characteristics of the sector antenna are measured by changing the distance between the pair of second reflectors 13t arranged to be inclined outward, and the relationship between the distance between the second reflectors and the 3 dB beam width is evaluated. 4 shows.

  As shown in FIG. 4, the 3 dB beam width in the 2 GHz band is wider than the 1.5 GHz band regardless of the change in the outer width W of the second reflector, and the second band is inclined outward in the non-conductive state. It can be seen that the beam width can be widened in the higher frequency band by arranging the reflector.

  Further, when the outer width W of the second reflector is 126 mm, the 3 dB beam width in the 1.5 GHz band is 74 degrees, whereas the 3 dB beam width in the 2 GHz band is 82 degrees, which is larger. It can be seen that the beam width of the horizontally polarized wave can be individually adjusted for each frequency band by adjusting the arrangement of the second reflecting plate in the conductive state.

  Next, a comparative example will be described.

[Comparative example]
As shown in FIG. 5A, the first reflector 12 (width: 184 mm) is disposed 40 mm away from the frequency sharing dipole element 11 sharing the horizontal polarization of 1.5 GHz band and 2 GHz band in parallel. At the same time, a pair of second reflectors 13c (width: 25 mm) is disposed on the first reflector 12 in a conductive state with the first reflector 12 to form a sector antenna 70 having a conventional structure. The first reflector 12 has side reflectors 15 having a height of 5 mm at both ends, and was electrically connected to the ground. In addition, the pair of second reflecting plates 13c is arranged perpendicular to the first reflecting plate 12 with a spacing of 140 mm. Here, the second reflecting plate 13c is in a conductive state with respect to the first reflecting plate 12 and the ground. The dimensions of the sector antenna 70 are shown in FIG.

  When the radiation characteristics of the sector antenna configured as described above were evaluated, the normalized radiation gain as shown in FIG. 7B was obtained, and the 3 dB beam width in the 1.5 GHz band was 73 degrees. The 3 dB beam width in the 2 GHz band was 68 degrees.

  Further, FIG. 6 shows the results of measuring the radiation characteristics of the sector antenna with the interval between the pair of second reflectors 13c changed and evaluating the relationship between the interval between the second reflectors and the 3 dB beam width.

  As shown in FIG. 6, the 3 dB beam width in the 2 GHz band tends to be narrower than the 1.5 GHz band regardless of the change in the interval W between the second reflectors, and is in a conductive state with the first reflector. It can be seen that the arranged second reflector cannot have the same beam width in different frequency bands, and cannot widen the beam width in the higher frequency band.

  According to the embodiment and comparative example described above, the sector antenna of the present invention makes the second reflector non-conducting and adjusts the size and arrangement of the second reflector so that the beam width of the horizontally polarized wave is individually adjusted for each frequency band. I understand that I can do it.

10 sector antenna 11 frequency sharing dipole element 12 first reflector 13n second reflector 14 tip of frequency sharing dipole element

Claims (7)

Frequency sharing dipole element that transmits and receives horizontal polarization in multiple frequency bands,
A first reflector that is disposed along the frequency sharing dipole element and spaced apart from the frequency sharing dipole element, and that reflects a horizontally polarized wave from the frequency sharing dipole element;
A pair of the frequency sharing dipole element and the first reflecting plate disposed between the first reflecting plate and the first reflecting plate in a non-conducting state, and disposed upright on both ends of the frequency sharing dipole element. A second reflector;
With
The plurality of frequency bands are 1.5 GHz band and 2 GHz band,
Or second reflector of the pair state, and are not to adjust the beam width of the horizontal polarization of the plurality of frequency bands, equal approximate beamwidth of the horizontal polarization by the plurality of frequency bands, or the A sector antenna characterized in that a beam width of horizontally polarized waves is made wider in a higher frequency band of a plurality of frequency bands than in a lower frequency band of the plurality of frequency bands .   2. The sector antenna according to claim 1, wherein the pair of second reflectors are arranged to be inclined outward so that a distance between the pair of second reflectors increases toward the frequency sharing dipole element.   The sector antenna according to claim 1 or 2, wherein the first reflector includes side reflectors at both ends in the outer direction.   The sector antenna according to claim 3, wherein the side reflector is disposed outside the pair of second reflectors.   5. The sector antenna according to claim 1, wherein the sector antenna has a plane symmetrical shape with respect to a central plane perpendicular to the first reflecting plate and a horizontal plane.   The sector antenna according to any one of claims 1 to 5, wherein there are a plurality of the frequency sharing dipole elements, and each of the frequency sharing dipole elements is arranged so that its longitudinal direction is in the horizontal direction and parallel to each other in the vertical direction.   The sector antenna according to claim 6, wherein the first reflector is arranged in parallel with each of the plurality of frequency sharing dipole elements.

Images