JP4588750B2 - Frequency sharing array antenna - Google Patents

Description

  The present invention relates to a frequency sharing array antenna that can be suitably used as an antenna for a base station in a mobile communication system or the like.

In mobile communication, the area covered by one base station is divided into fan-shaped sectors to improve frequency use efficiency. In order to divide the area into a fan shape in this way, it is necessary to radiate radio waves only in a desired fan-shaped range using a directional antenna as a base station antenna.
When the required directivity in the horizontal plane is narrow (for example, 100 ° or less), the directional antenna used as the base station antenna has two or more antenna elements arranged in the horizontal direction as described in Patent Document 1. May be configured.
JP-A-6-69716

  However, the horizontal multi-element array antenna as described above needs to synthesize each antenna element using a two-distributor or the like. For this reason, when an array is formed in multiple stages in the vertical direction, the structure of the power feeding circuit becomes complicated, and the manufacturing cost increases due to the increase in the number of components and the number of assembly steps. In addition, when configuring a frequency sharing antenna, antenna elements that resonate with individual frequencies are arranged in an overlapping manner, so that electrical characteristics such as VSWR (standing wave ratio) and horizontal plane directivity are provided. Cause deterioration.

  In recent years, in order to reduce the burden on the base station due to the addition of a steel tower, it is also practiced to store an antenna shared by two or more frequencies in one antenna cover. However, this frequency sharing antenna has the disadvantages that the antenna elements that resonate with individual frequencies interact with each other electrically, so that it is difficult to form directivity in the horizontal plane and the structure is complicated.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a frequency sharing array antenna capable of obtaining good directivity in a horizontal plane while simplifying the structure and reducing the cost.

  In order to achieve the above object, the present invention provides a plurality of first antenna element units arranged in a staggered manner in the vertical direction across the vertical center axis, and the first antenna element units across the vertical center axis. A plurality of second antenna element units arranged in a staggered manner in a vertical direction in a form that does not overlap with the first antenna element unit, and the first antenna element unit includes a first antenna element that resonates at one or more frequencies. The second antenna element unit is configured by a second antenna element that resonates at one or a plurality of frequencies different from the frequency, and provides a frequency sharing array antenna.

In one embodiment, the first antenna element unit has one first antenna element, and the second antenna element unit has one second antenna element.
In another embodiment, the first antenna element unit has a subarray in which a plurality of the first antenna elements are arranged in the vertical direction, and the second antenna element unit has the second antenna element in the vertical direction. It has a plurality of subarrays.
In still another embodiment, the first antenna element unit has one first antenna element, and the second antenna element unit has a subarray in which a plurality of the second antenna elements are arranged in the vertical direction. Have.

As the first and second antenna elements, a vertically polarized antenna element or a horizontally polarized antenna element can be used. Further, a horizontally polarized antenna element may be used for one of the first and second antenna elements, and a vertically polarized antenna element may be used for the other.
Further, as the first and second antenna elements, a dual-polarized antenna element that is a combination of a horizontally polarized antenna element and a vertically polarized antenna element is used, or vertically polarized waves are used as the first antenna element. It is also possible to use a dual-polarized antenna element that uses an antenna element and combines a horizontally polarized antenna element and a vertically polarized antenna element as the second antenna element.

  For the first and second antenna elements, for example, dipole antenna elements or patch antenna elements can be used.

According to the present invention, the plurality of first antenna element units arranged in a staggered manner in the vertical direction across the vertical center axis, and the first antenna element unit not overlapped with the vertical center axis. A plurality of second antenna element units arranged in a staggered pattern in the vertical direction, and the first antenna element unit has a first antenna element that resonates at a single or a plurality of first frequencies, Since the second antenna element unit is configured to have a second antenna element that resonates at a single or a plurality of second frequencies, the number of antenna elements and power supply components such as a distributor can be reduced, Cost reduction.
In addition, since it is possible to prevent the first and second antenna elements from overlapping and to suppress electrical interference between them, it is possible to obtain good VSWR characteristics and horizontal plane directivity.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a conceptual diagram showing a first embodiment of a frequency sharing array antenna according to the present invention. The array antenna according to the present embodiment includes a plurality of antenna element units U1 arranged in a staggered manner in the vertical direction across the vertical center axis L, and the first antenna element unit U1 across the vertical center axis L. A plurality of antenna element units U2 arranged in a staggered pattern in the vertical direction in a non-overlapping form. In the present embodiment, the antenna element units U1 and U2 are opposed to each other with the vertical center axis L interposed therebetween.

The antenna element units U1 and U2 include single antenna elements 1 and 2, respectively. In this embodiment and each of the embodiments described later, dipole antenna elements are used as the antenna elements 1 and 2. The antenna elements 1 and 2 are configured to resonate at frequencies f1 and f2, respectively, and are arranged in such a manner that their element conductors face vertically, that is, function as vertical polarization antenna elements.
When the antenna according to the present embodiment is used as a base station antenna in a mobile communication system or the like, the frequencies f1 and f2 are set to, for example, 0.8 GHz (800 MHz) and 2 GHz, respectively.

  According to the frequency sharing array antenna according to the present embodiment, the antenna elements 1 and 2 are arranged in a staggered pattern in the vertical direction with the vertical center axis L interposed therebetween, so that the antenna elements are not arranged in a staggered pattern. Compared to an array antenna, that is, a conventional array antenna (not shown) in which the antenna elements 1 and 2 are opposed to each other across the vertical center axis L, the number of antenna elements related to each frequency is halved. can do.

In addition, in the antenna of the conventional configuration, power feeding means such as a distributor is used to connect the left and right antenna elements of each stage. However, in the antenna according to this embodiment, such power feeding means is unnecessary. Become. Therefore, according to the antenna according to the present embodiment, the configuration can be simplified, and the number of component parts and the number of assembly steps can be reduced, thereby significantly reducing the cost.
Furthermore, since the antenna according to the present embodiment can be arranged without overlapping the antenna element 1 for the frequency f1 and the antenna element 2 for the frequency f2, the mutual interference between them can be suppressed, and a good VSWR ( Standing wave ratio) characteristics and horizontal plane directivity can be realized.

FIG. 2 is a conceptual diagram showing a second embodiment of the frequency sharing array antenna according to the present invention. The array antenna according to the present embodiment is different from the antenna shown in FIG. 1 in that the antenna element unit U1 has two antenna elements 1 and the antenna element unit U2 has two antenna elements 2.
The two antenna elements 1 in the antenna element unit U1 are arranged at predetermined intervals in the vertical direction, thereby constituting a sub-array of the antenna elements 1. Similarly, the two antenna elements 2 in the antenna element unit U2 are arranged at predetermined intervals in the vertical direction, thereby forming a sub-array of the antenna elements 2. Note that the sub-array of the antenna element 1 and the sub-array of the antenna element 2 are opposed to each other with the vertical center axis L interposed therebetween.

  Also with the antenna according to the present embodiment, an effect equivalent to that of the antenna shown in FIG. 1 described above can be obtained. Note that the number of antenna elements 1 and 2 constituting the sub-array is not limited to 2, and can be set to an arbitrary number of 2 or more.

FIG. 3 conceptually shows a third embodiment of the frequency sharing array antenna according to the present invention. The array antenna according to the present embodiment differs from the antenna shown in FIG. 1 in that the antenna element unit U2 includes two antenna elements 2.
The two antenna elements 2 in the antenna element unit U2 are arranged at a predetermined interval in the vertical direction to constitute a subarray. The subarray faces the antenna element 1 with the vertical center axis L interposed therebetween.

  The antenna according to the present embodiment can also obtain an effect according to the effect of the antenna shown in FIG. Note that the number of antenna elements 2 arranged in the sub-array is not limited to two and can be set to any number of two or more. Further, instead of configuring a sub-array of the antenna elements 2, a sub-array of the antenna elements 1 can be configured.

FIG. 4 is a conceptual diagram showing a fourth embodiment of the frequency sharing array antenna according to the present invention. The array antenna according to this embodiment is different from the antenna shown in FIG. 1 in that the antenna element unit U1 has the dual-polarization antenna element 3 and the antenna element unit U2 has the dual-polarization antenna element 4.
The dual polarization antenna element 3 has a configuration (cross dipole configuration) in which a vertical polarization antenna element 1 and a horizontal polarization antenna element 1 ′ both resonating at a frequency f 1 are arranged, and the dual polarization antenna element 4. Has a configuration (cross dipole configuration) in which a vertically polarized antenna element 2 and a horizontally polarized antenna element 2 ′, both of which resonate at a frequency f2, are crossed.

  According to the array antenna according to the present embodiment, in addition to the effect of the array antenna shown in FIG. 1, the horizontal polarization and the vertical polarization at the frequency f1 are shared, and the horizontal polarization and the vertical polarization at the frequency f2 are shared. Can be shared.

  FIG. 5 is a conceptual diagram showing a fifth embodiment of the frequency sharing array antenna according to the present invention. The array antenna according to the present embodiment is different from that shown in FIG. 4 in that the antenna element unit U1 is provided with the two polarization-sharing antenna elements 3 and the antenna element unit U2 is provided with the two polarization-sharing antenna elements 4. Is different from the antenna shown in FIG.

The dual-polarized antenna elements 3 of the antenna element unit U1 are arranged in the vertical direction at a predetermined interval to form a sub-array of the dual-polarized antenna element 3, and similarly, the two polarized waves of the antenna element unit U2 are shared. The antenna elements 4 are arranged in a vertical direction at a predetermined interval to constitute a sub-array of the polarization sharing antenna element 4. The former sub-array 3 and the latter sub-array 4 are opposed to each other with the vertical center axis L interposed therebetween.
Also in the antenna according to the present embodiment, an effect equivalent to that of the antenna shown in FIG. 4 can be obtained. Note that the number of the polarization sharing antenna elements 3 and 4 constituting the subarray is not limited to 2, and can be set to any number of 2 or more.

FIG. 6 shows a sixth embodiment of the frequency sharing array antenna according to the present invention. The array antenna according to the present embodiment is different from the array antenna shown in FIG. 4 in that the antenna element unit U2 includes two polarization sharing antenna elements 4.
The two polarization sharing antenna elements 4 in the antenna element unit U2 are arranged at a predetermined interval in the vertical direction to constitute a subarray. The subarray faces the polarization sharing antenna element 3 of the antenna element unit U1 across the vertical center axis L.

  The antenna according to the present embodiment can also obtain an effect according to the antenna shown in FIG. Note that the number of the polarization sharing antenna elements 4 constituting the subarray is not limited to 2, and can be set to an arbitrary number of 2 or more. Further, instead of configuring a sub-array of the dual-polarized antenna element 4, a sub-array of the dual-polarized antenna element 3 can be configured.

  The antenna elements 1 and 2 shown in FIGS. 1 to 3 are configured to resonate at a single frequency f1 and f2, respectively. However, one or both of these antenna elements resonate at a plurality of frequencies. It is also possible to configure. Similarly, one or both of the antenna elements 1, 1 ′ and one or both of the antenna elements 2, 2 ′ shown in FIGS. 4 to 6 can be configured to resonate at a plurality of frequencies.

  FIG. 7 shows an example of a dipole antenna element that resonates at three frequencies. This antenna element 10 includes element conductors 12a, 13a and 14a made of a metal foil formed on one surface of a dielectric substrate 11, and an element conductor made of a metal foil formed on the other surface of the dielectric substrate 11. 12b, 13b and 14b. The lengths of the element conductors 12a and 12b are set so as to resonate at the frequency f1 ′, and extend coaxially in the left and right directions in the drawing, respectively.

The element conductors 13a and 13b are formed to have a length that resonates at the frequency f2 ′ by a notch 16 provided in the shape of a “U” in each of the element conductors 12a and 12b. The element conductors 14a and 14b Each of the element conductors 13a and 13b is formed to have a length that resonates at a frequency f3 ′ by a notch 17 provided in a “U” shape.
The element conductors 12a, 13a and 14a are connected to one feed line 15a via a common central feed point 18a, and the element conductors 12b, 13b and 14b are respectively fed via a common central feed point 18b. 15b. Reference numeral 19 denotes a grounding part connected to the feed line 15a.

In the antenna element 10 configured as described above, the element conductors 12a and 12b resonate at the frequency f1 ′, the element conductors 13a and 13b resonate at the frequency f2 ′, and the element conductors 14a and 14b resonate at the frequency f3 ′. If the antenna element 1 in the antenna shown in FIG. 1 is substituted, this antenna can be shared by the four frequencies f1 ′ to f3 ′ and f2.
Of course, the antenna elements that resonate at a plurality of frequencies as described above may be substituted for both of the antenna elements 1 and 2 shown in FIGS. 1 to 3, and the antenna elements 1 and 2 shown in FIGS. One or both of (1 ′, 2 ′) may be substituted.

  FIG. 8 is a conceptual diagram showing a seventh embodiment of the frequency sharing array antenna according to the present invention. In the array antenna according to this embodiment, the relative arrangement form of each antenna element unit U1 and each antenna element unit U2 is the same as that of the antenna of each embodiment.

  The antenna according to the present embodiment has one antenna element 1 for vertical polarization whose antenna element unit U1 resonates at 0.8 GHz (f1), and the antenna element unit U2 resonates at 2 GHz (f2). It has a subarray in which the polarization sharing antenna elements 4 are arranged in the vertical direction at a predetermined interval. The horizontally polarized antenna elements 1 ′ that resonate at 0.8 GHz (f1) are positioned above the antenna element units U1 and U2 at each stage. In this horizontally polarized antenna element 1 ′, the position of the central feed point is located on the vertical center axis L.

In the antenna according to this embodiment, when a horizontal plane beam width of 90 ° in the 0.8 GHz (f1) band is realized and a horizontal plane beam width of 90 ° in the 2 GHz (f2) band is realized, the vertical deviation of the 0.8 GHz band is realized. The horizontal arrangement interval D1 of the wave antenna element 1 and the horizontal arrangement interval D2 of the 2 GHz band vertical polarization antenna element 2 are respectively set as follows.
D1: (wavelength lambda _0.8 is corresponding to 0.8GHz) 0.22λ _0.8 on a wavelength basis of 0.8GHz band, 0.54λ ₂ (λ ₂ on a wavelength basis of the 2GHz band corresponding to 2GHz Wavelength)
D2: 0.47λ ₂ in terms of the wavelength converted in the 2 GHz band, and 0.2λ _{0.8 in} the wavelength converted value of the _0.8 GHz band

According to the array antenna according to the present embodiment, since the overlap between the 0.8 GHz band vertical polarization antenna element 1 and the 2 GHz band vertical polarization antenna element 2 is avoided, electrical interference between them is suppressed. . For this reason, good VSWR characteristics can be obtained, and good directivity in the horizontal plane as shown in FIGS. 9A and 9B and FIGS. 10A and 10B can be realized.
9A and 9B show the directivity in the horizontal plane of vertical polarization and horizontal polarization for 0.8 GHz, respectively, and FIGS. 10A and 10B show the directivity for 2 GHz. The horizontal plane directivity of vertical polarization and horizontal polarization is shown respectively.

FIG. 11 shows the configuration of an array antenna according to a comparative example according to the prior art.
The antenna according to this comparative example includes two 0.8 GHz band vertical polarization antenna elements 1, one 0.8 GHz band horizontal polarization antenna element 1, and four 2 GHz band polarization shared antenna elements 4. It is constituted by.
The two 0.8 GHz band vertically polarized antenna elements 1 are arranged to face each other with the vertical center axis L interposed therebetween so that the horizontal interval between them is D1. On the other hand, two of the four 2-GHz band dual-polarized antenna elements 4 are the upper-element conductors of the vertical-polarized antenna element 1 opposed to the vertical-polarized antenna elements 2 included therein. The remaining two polarization-sharing antenna elements 4 are arranged below each other so that the vertically polarized antenna elements 2 included therein are below the opposed vertically polarized antenna elements 1. The side element conductors are arranged to face each other with the distance D2.

In the array antenna according to this comparative example, since the horizontal interval between adjacent vertically polarized antenna elements 1 and 2 becomes small, the antenna elements 1 and 2 are electrically interfered with each other. It causes deterioration of directivity.
(A) and (b) of FIG. 12 show the directivity in the horizontal plane of vertical polarization and horizontal polarization at 0.8 GHz of the antenna according to this comparative example, respectively, and (a) and ( b) shows the directivity in the horizontal plane of vertically polarized waves and horizontally polarized waves at 2 GHz of the antenna.

As is clear from the comparison between FIGS. 9 and 10 and FIGS. 12 and 13, the antenna according to the present invention shown in FIG. 8 exhibits better directivity in the horizontal plane than the antenna according to the comparative example. ing.
Further, as apparent from the comparison between FIG. 8 and FIG. 11, according to the antenna according to the present invention, the number of antenna elements is reduced to ½ that of the antenna according to the comparative example. The system configuration can be simplified.
In the antenna shown in FIG. 8, a plurality of vertical antenna elements 1 at each stage are arranged in the vertical direction to form a subarray, and the number of arrayed polarization antenna elements 4 in the subarray at each stage is set to 2 or more. Is possible.

The present invention is not limited to the configuration of the above embodiment, and includes various modifications. In other words, in each of the embodiments described above, dipole antenna elements are used as the antenna elements 1 and 2, but other antenna elements such as patch antenna elements may be used instead.
In the embodiment shown in FIGS. 1 to 3, vertical polarization antenna elements are used as the antenna elements 1 and 2, but a horizontal polarization antenna element is used for one or both of these antenna elements 1 and 2. It is also possible to use it.
Furthermore, in each of the above embodiments, the left and right antenna element units U1 and U2 are arranged opposite to each other with the vertical center axis L interposed therebetween. However, the vertical direction of the units U1 and U2 is within a range in which distortion in the horizontal plane directivity does not occur. The relative position may be shifted.

It is a conceptual diagram which shows 1st Embodiment of the frequency sharing array antenna which concerns on this invention. It is a conceptual diagram which shows 2nd Embodiment of the frequency sharing array antenna which concerns on this invention. It is a conceptual diagram which shows 3rd Embodiment of the frequency sharing array antenna which concerns on this invention. It is a conceptual diagram which shows 4th Embodiment of the frequency sharing array antenna which concerns on this invention. It is a conceptual diagram which shows 5th Embodiment of the frequency sharing array antenna which concerns on this invention. It is a conceptual diagram which shows 6th Embodiment of the frequency sharing array antenna which concerns on this invention. It is a front view which shows an example of the dipole antenna element which resonates to three frequencies. It is a conceptual diagram which shows 7th Embodiment of the frequency sharing array antenna which concerns on this invention. (A) And (b) is a graph which respectively shows the directivity in the horizontal surface of the vertically polarized wave and horizontal polarized wave about 0.8 GHz in the antenna of FIG. (A) And (b) is a graph which respectively shows the directivity in the horizontal surface of the vertical polarization and horizontal polarization about 2 GHz in the antenna of FIG. It is a conceptual diagram which shows the structure of the frequency sharing array antenna which concerns on a comparative example. (A) And (b) is a graph which respectively shows the directivity in the horizontal plane of the vertically polarized wave and horizontal polarized wave about 0.8 GHz in the antenna of FIG. (A) And (b) is a graph which respectively shows the directivity in the horizontal surface of the vertical polarization and horizontal polarization about 2 GHz in the antenna of FIG.

Explanation of symbols

U1, U2 Antenna element unit L Vertical center axis 1,1 ', 2,2' Antenna element 3,4 Polarization antenna element

Claims (10)

A plurality of first antenna element units arranged in a staggered manner in the vertical direction across the vertical central axis;
A plurality of second antenna element units arranged in a staggered manner in the vertical direction in a form that does not overlap the first antenna element unit across the vertical central axis,
The first antenna element unit is constituted by a first antenna element that resonates at one or more frequencies,
The frequency sharing array antenna, wherein the second antenna element unit is configured by a second antenna element that resonates at one or a plurality of frequencies different from the frequency.   2. The first antenna element unit includes one first antenna element, and the second antenna element unit includes one second antenna element. 3. Frequency sharing array antenna.   The first antenna element unit has a subarray in which a plurality of the first antenna elements are arranged in a vertical direction, and the second antenna element unit is a subarray in which a plurality of the second antenna elements are arranged in a vertical direction. The frequency sharing array antenna according to claim 1, wherein   The first antenna element unit has one first antenna element, and the second antenna element unit has a subarray in which a plurality of the second antenna elements are arranged in a vertical direction. The frequency sharing array antenna according to claim 1.   The frequency sharing array antenna according to any one of claims 1 to 4, wherein the first and second antenna elements are vertically polarized antenna elements.   The frequency sharing array antenna according to any one of claims 1 to 4, wherein the first and second antenna elements are horizontally polarized antenna elements.   The frequency sharing array antenna according to any one of claims 1 to 4, wherein one of the first and second antenna elements is a horizontally polarized antenna element and the other is a vertically polarized antenna element. .   5. The frequency according to claim 1, wherein the first and second antenna elements are dual-polarized antenna elements in which a horizontally polarized antenna element and a vertically polarized antenna element are combined. Shared array antenna.   The first antenna element is a vertically polarized antenna element, and the second antenna element is a polarization sharing antenna element in which a horizontally polarized antenna element and a vertically polarized antenna element are combined. Item 5. The frequency sharing array antenna according to any one of Items 1 to 4.   10. The frequency sharing array antenna according to claim 1, wherein the first and second antenna elements are dipole antenna elements or patch antenna elements.

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