JP2018026667A - Dual frequency omnidirectional antenna and collinear array antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dual frequency omnidirectional antenna capable of sharing plural frequency band while preventing plural shared frequency bands from interfering with each other with a simple configuration.SOLUTION: A dual frequency omnidirectional antenna 10 has a folded dipole structure. The dual frequency omnidirectional antenna 10 which has a U-shaped continuous cross section in a longitudinal direction, which includes: a pair of outer resonance elements 31a and 31b which resonates at a high frequency band; and a pair of folded parts 39a and 39b each continue with the outer resonance elements 31a and 31b, which resonate at low frequency band. The dual frequency omnidirectional antenna also includes a pair of inner resonance element 33a and 33b which is disposed inside the outer resonance elements 31a and 31b along a longitudinal direction of the outer resonance elements 31a and 31b.SELECTED DRAWING: Figure 1D

Description

  The present invention relates to a dual-frequency omnidirectional antenna and a collinear array antenna used in, for example, a base station antenna apparatus in a mobile communication system or the like.

  Conventionally, for example, Patent Document 1 is disclosed as a dual-frequency omnidirectional antenna for a base station in a mobile communication system or the like. The dual-band omnidirectional antenna, which is a dual-frequency omnidirectional antenna disclosed in Patent Document 1, includes an antenna array that is vertically stacked in the following order, and is divided into a first frequency band and a second frequency band. A first dual-band dipole that resonates, a first single-band dipole that resonates only in the first frequency band, a second single-band dipole that resonates only in the first frequency band, and a resonance in the first and second frequency bands. And a second dual-band dipole.

US Pat. No. 7,755,559

  In recent mobile communication systems, it is required to make effective use of existing base stations, instead of simply adding new base stations, in response to new frequency band allocation. For this reason, one antenna with an existing base station is required to be shared by a plurality of frequency bands.

  In order to share a plurality of frequency bands, in the antenna, methods such as arrangement of a plurality of resonant elements and widening of the antenna are mainly used. However, the structure of the antenna itself is complicated, and problems such as a plurality of frequency bands interfering with each other between stages depending on the frequency band are likely to occur in a multistage (tandemly arranged) antenna.

  For this reason, in view of the above circumstances, the present invention can share a plurality of frequency bands with a simple configuration, and can suppress a plurality of shared frequency bands from interfering with each other. The purpose is to provide.

  In order to achieve the above object, one aspect of the dual-frequency omnidirectional antenna of the present invention is a dual-frequency omnidirectional antenna having a folded dipole structure, wherein a U-shaped cross section is in the longitudinal direction. A continuous outer resonance element that resonates in a high frequency band, and a folded portion that is continuous with the outer resonance element and resonates in a low frequency band, along the longitudinal direction of the outer resonance element. And an inner resonance element disposed inside the outer resonance element.

  In order to achieve the above object, a collinear array antenna of the present invention is characterized in that the dual-frequency omnidirectional antenna described above is multistaged using a distribution matching line.

  According to the present invention, it is possible to provide a dual-frequency omnidirectional antenna and a collinear array antenna that can share a plurality of frequency bands with a simple configuration and can suppress interference between the plurality of shared frequency bands. it can.

FIG. 1A is a perspective view of a dual-frequency omnidirectional antenna according to an embodiment of the present invention. 1B is a front view of the dual-frequency omnidirectional antenna shown in FIG. 1A. 1C is a vertical side view of the dual-frequency omnidirectional antenna shown in FIG. 1A, and is a diagram of the dual-frequency omnidirectional antenna shown in FIG. 1B as viewed from an arrow 1C. FIG. 1D is a diagram showing a positional relationship between the first outer resonance element and the first inner element of each of the upper resonance unit and the lower resonance unit based on the front view of the dual-frequency omnidirectional antenna shown in FIG. 1B. . FIG. 1E is a cross-sectional view of the dual-frequency omnidirectional antenna taken along line 1E shown in FIG. 1D. FIG. 1F is an example of a first inner resonance element. 2A is a perspective view of a collinear array antenna in which the dual-frequency omnidirectional antenna shown in FIG. 1A is arranged in two stages in a tandem arrangement. 2B is a front view of the collinear array antenna shown in FIG. 2A. 2C is a VSWR characteristic diagram of the collinear array antenna shown in FIG. 2A. FIG. 2D is a diagram illustrating a typical directivity of the first frequency band f1 between the vertical plane and the horizontal plane of the collinear array antenna illustrated in FIG. 2A. FIG. 2E is a diagram illustrating a typical directivity of the second frequency band f2 in the vertical plane and the horizontal plane of the collinear array antenna illustrated in FIG. 2A. FIG. 3 is a perspective view of a collinear array antenna in which the collinear array antenna shown in FIG. 2A is arranged in three stages in a tandem arrangement.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. For example, like the screw 41a and the like are omitted in FIG. 1A, some of the members are omitted in some drawings for clarity of illustration.
[One Embodiment]
A dual-frequency omnidirectional antenna 10 having a folded dipole structure as shown in FIG. 1A uses, for example, a first frequency band f1 and a second frequency band f2 that are shared in a base station apparatus. That is, the dual-frequency omnidirectional antenna 10 is an antenna shared by the two frequency bands f1 and f2. The second frequency band f2 is assumed to be higher than the first frequency band f1. For example, the relationship of “f2≈f1 × 2” is established between the first frequency band f1 and the second frequency band f2. A radio signal output from a coaxial terminal (not shown) is guided and radiated to the two-frequency omnidirectional antenna 10 through a power supply cable (not shown). The total length of the dual-frequency omnidirectional antenna 10 that is one element is preferably ≈0.5λ to ≈0.7λ in the second frequency band f2.

  In the base station apparatus, for example, as shown in FIGS. 2A and 2B, a collinear array antenna 20 in which two dual-frequency omnidirectional antennas 10 are arranged in tandem and arranged in two stages using a distribution matching line 79 is used. It is preferred that The total length of the collinear array antenna 20 having the two dual-frequency omnidirectional antennas 10 is preferably ≈0.5λ to ≈0.7λ in the first frequency band f1. In the collinear array antenna 20 shown in FIG. 2A, from the lower resonance unit 50 described later of the first dual-frequency omnidirectional antenna 10a to the upper resonance unit 30 described later of the second dual-frequency omnidirectional antenna 10b. The interstage 25 which is the length is preferably ≈0.8λ in the second frequency band f2. FIG. 2C shows a VSWR characteristic diagram of the collinear array antenna 20 shown in FIG. 2A. In the collinear array antenna 20 shown in FIG. 2A, a typical directivity of the first frequency band f1 in the vertical plane and the horizontal plane is shown in FIG. 2D, and a representative directivity of the second frequency band f2 in the vertical plane and the horizontal plane is shown. Is shown in FIG. 2E.

  In the base station apparatus, for example, as shown in FIG. 3, the collinear array antenna 20 in which the three collinear array antennas 20 shown in FIG. Good.

  In the collinear array antenna 20, as long as the dual-frequency omnidirectional antenna 10 is multistaged using the distribution matching line 79, the number of dual-frequency omnidirectional antennas 10 is not particularly limited. In the collinear array antenna 20, a parallel power feeding method is used in which power is fed in parallel to each of the dual-frequency omnidirectional antennas 10. In the base station apparatus, one dual-frequency omnidirectional antenna 10 may be used.

  Each of the dual-frequency omnidirectional antennas 10 has the same configuration with respect to each other, and will be described with reference to FIG.

  As shown in FIG. 1A, the dual-frequency omnidirectional antenna 10 includes a substantially cylindrical upper resonance unit 30, a substantially cylindrical lower resonance unit 50, an upper resonance unit 30, and a lower resonance unit 50. And a support portion 70 to support. The upper resonance unit 30 and the lower resonance unit 50 are arranged on the same straight line in the longitudinal direction of the dual-frequency omnidirectional antenna 10, and are arranged slightly apart from each other with a support base 75c to be described later interposed therebetween. The The upper resonance unit 30 and the lower resonance unit 50 function as a pair of resonance units constituting the dual-frequency omnidirectional antenna 10. The support portion 70 is surrounded by the upper resonance unit 30 and the lower resonance unit 50, in other words, penetrates the upper resonance unit 30 and the lower resonance unit 50 in the longitudinal direction of the dual-frequency omnidirectional antenna 10. ing.

  Since the upper resonance unit 30 and the lower resonance unit 50 have the same configuration, description will be made using the upper resonance unit 30 shown in FIGS. 1A to 1E. For example, as shown in FIG. 1B, the illustration of the screw 41a and the like is omitted, and in some drawings, the illustration of a part of the member is omitted for clarity of illustration.

  As shown in FIGS. 1A and 1B, the upper resonance unit 30 includes a pair of first and second outer resonance elements 31a and 31b. Each of the first and second outer resonance elements 31 a and 31 b is disposed along the longitudinal direction of the dual-frequency omnidirectional antenna 10. As shown in FIG. 1E, for example, the first and second outer resonance elements 31a and 31b are each formed by, for example, bending an elongated plate member into a U shape. In the cross section of the upper resonance unit 30 shown in FIG. 1E, both ends of the U-shape of the first outer resonance element 31a are disposed away from both ends of the U-shape of the second outer resonance element 31b. A gap is formed. The first and second outer resonance elements 31a and 31b are arranged so as to surround the support portion 70, and the upper resonance unit 30 has a substantially cylindrical cross section. As shown in FIGS. 1D and 1E, first and second inner resonance elements 33a and 33b, which will be described later, are arranged inside the first and second outer resonance elements 31a and 31b, respectively. Since the first outer resonance element 31a and the second outer resonance element 31b have the same configuration, the following description will be made using the first outer resonance element 31a. The first outer resonance element 31a continuously has a U-shaped cross section in the longitudinal direction of the dual-frequency omnidirectional antenna 10 (first outer resonance element 31a), and is fed by a power feeding unit 77 described later. Resonance occurs in the high second frequency band f2.

  The support unit 70 includes a rod-shaped member 73 disposed along the longitudinal direction of the dual-frequency omnidirectional antenna 10 (first outer resonance element 31 a), and first and second side plate portions 75 a and 75 b that support the rod-shaped member 73. And have. The rod-shaped member 73 is a metal material such as brass, aluminum, stainless steel, or copper, for example. The first and second side plate portions 75a and 75b are, for example, plastic.

  As shown in FIG. 1B, the power feeding unit 77 is disposed between the upper resonance unit 30 and the lower resonance unit 50 in the longitudinal direction of the dual-frequency omnidirectional antenna 10, and the upper resonance unit 30 and the lower resonance unit 50. The unit 50 is electrically connected to the first and second outer resonance elements 31 a and 31 b of each unit 50.

  As shown in FIG. 1A, FIG. 1B, and FIG. 1C, the first side plate portion 75a is disposed at the end of the upper resonance unit 30 on the opposite side to the power feeding portion 77, and the second side plate portion 75b is the power feeding portion 77. It is arranged at the end of the lower resonance unit 50 on the opposite side. The first and second side plate portions 75 a and 75 b are planes that are disposed orthogonal to the longitudinal direction of the dual-frequency omnidirectional antenna 10. The first and second side plate portions 75a and 75b have the same configuration.

  As shown in FIG. 1A, the first and second side plate portions 75a and 75b are arranged on the same straight line with respect to each other, and have a through-hole through which the rod-shaped member 73 penetrates in the central portion. The first and second side plate portions 75 a and 75 b support the rod-shaped member 73 by the rod-shaped member 73 passing through the through hole.

  As shown in FIGS. 1A, 1B, and 1C, the first side plate portion 75a includes the first and second outer resonance elements 31a of the upper resonance unit 30 at the end of the upper resonance unit 30 opposite to the power feeding portion 77. , 31b supports the ends of the first and second outer resonance elements 31a, 31b in a state where the ends of the first side plate 75a are in contact with the planar portion. The first side plate portion 75a is fixed to a first folded portion 39a of each of first and second inner resonance elements 33a and 33b described later in the upper resonance unit 30.

  As shown in FIGS. 1A, 1B, and 1C, the second side plate portion 75b has the first and second outer resonances of the lower resonance unit 50 at the end of the lower resonance unit 50 opposite to the power feeding portion 77. The ends of the first and second outer resonance elements 31a and 31b are supported in a state where the ends of the elements 31a and 31b are in contact with the planar portion of the second side plate portion 75b. The second side plate portion 75b is fixed to the first folded portion 39a of each of first and second inner resonance elements 33a and 33b described later in the lower resonance unit 50.

  The support unit 70 includes a support base 75 c that supports the rod-shaped member 73 around the power supply unit 77. The support base 75c includes the ends of the first and second outer resonance elements 31a and 31b of the upper resonance unit 30 disposed on the power feeding unit 77 side, and the lower resonance unit 50 disposed on the power feeding unit 77 side. The end portions of the first and second outer resonance elements 31a and 31b are supported. The support base 75c has substantially the same configuration as the first and second side plate portions 75a and 75b. The support base 75c is, for example, plastic.

  In the collinear array antenna 20 shown in FIGS. 2A and 2B, the rod-shaped member 73 is disposed over the entire length of the collinear array antenna 20, and the collinear array antenna 20 further includes a main body plate member 71. The main body plate member 71 extends from the end of the upper resonance unit 30 adjacent to the lower resonance unit 50 of the first dual-frequency omnidirectional antenna 10a to the upper resonance unit 30 of the second dual-frequency omnidirectional antenna 10b. Extends to the end of the lower resonance unit 50 adjacent to. The main body plate member 71 may extend over the entire length of the collinear array antenna 20. In the collinear array antenna 20, the connection between the two-frequency omnidirectional antennas 10 is not particularly limited.

  As shown in FIGS. 1D and 1E, the upper resonance unit 30 has a pair of first and second inner resonance elements 33a and 33b disposed between the first and second outer resonance elements 31a and 31b. The first inner resonance element 33 a is disposed between the first outer resonance element 31 a and the rod-shaped member 73, and the second inner resonance element 33 b is disposed between the second outer resonance element 31 b and the rod-shaped member 73. . Since the first and second inner resonance elements 33a and 33b have the same configuration, the first inner resonance element 33a will be described.

  The first inner resonance element 33a is continuous with the first outer resonance element 31a by a first folded portion 39a described later, and resonates at a lower first frequency band f1 by first and second folded portions 39a and 39b described later. The first inner resonance element 33a is covered with the first outer resonance element 31a, and is arranged inside each of the U-shaped first outer resonance elements 31a along the longitudinal direction of the first outer resonance element 31a. Such first inner resonance element 33a is formed, for example, by fixing a plurality of plate members to each other with screws 41a or the like. For example, the first plate member 35a functions as, for example, a U-shaped first and second folded portions 39a and 39b arranged continuously at both ends of the first straight portion 37a and the first straight portion 37a. The first and second folded portions 39a and 39b may be U-shaped, for example, and the degree of folding may be appropriately adjusted. That is, the first and second folded portions 39a and 39b may be curved surface portions. The second plate member 35b functions as the second linear portion 37b.

  The first inner resonance element 33a has a U-shape at the first folded portion 39a from the end of the first outer resonance element 31a away from the power feeding section 77 toward the end of the first outer resonance element 31a closer to the power feeding section 77. Wrapped into a mold. The first inner resonance element 33a is straight from the end portion side of the first outer resonance element 31a, which is away from the power feeding portion 77, in the first linear portion 37a, toward the end portion side of the first outer resonance element 31a, which is closer to the power feeding portion 77. It extends in a shape. In the second folded portion 39b, the first inner resonance element 33a is coupled from the end portion of the first outer resonance element 31a close to the power feeding portion 77 toward the end portion side of the first outer resonance element 31a far from the power feeding portion 77. It will be folded back into a letter shape. The first inner resonance element 33a extends again linearly toward the end of the first outer resonance element 31a away from the power feeding portion 77 in the second linear portion 37b.

  The first and second linear portions 37a and 37b are arranged in parallel to each other and to the first outer resonance element 31a. The first straight portion 37a is disposed away from the first outer resonance element 31a and is adjacent to the rod-shaped member 73 (main body plate member 71). The second straight portion 37b is disposed between the first straight portion 37a and the first outer resonance element 31a, and has a length that is substantially half of the first straight portion 37a. The first folded portion 39 a is disposed at the end portion of the first outer resonant element 31 a that is separated from the power feeding portion 77, and the second folded portion 39 b is disposed at the end portion of the first outer resonant element 31 a that is close to the power feeding portion 77. The first folded portion 39a faces the second folded portion 39b. As described above, the first inner resonance element 33 a is folded at both ends of the upper resonance unit 30.

  The first plate member 35a is fixed at the second folded portion 39b by the second plate member 35b and screws 41a. The first plate member 35a is fixed to the end portion of the first outer resonance element 31a away from the power feeding portion 77 by a screw 41b or the like in the first folded portion 39a. An end portion of the first outer resonance element 31a close to the power feeding portion 77 is fixed to the support base 75c with a screw 41c or the like.

  The first straight portion 37a and the second straight portion 37b are maintained at a distance from each other, for example, by a screw 43a. Accordingly, the first straight portion 37a and the second straight portion 37b are not in contact with each other. The same applies to the first outer resonance element 31a and the second linear portion 37b. Thus, the first outer resonance element 31a is not in contact with the first inner resonance element 33a, and the first and second plate members 35a, 35b of the first inner resonance element 33a are not in contact with each other.

  The first inner resonance element 33a may be formed by bending a single plate member a plurality of times. The first straight portion 37a may be fixed to the support base 75c with a screw (not shown). The method for fixing the first inner resonance element 33a is not particularly limited.

  The first outer resonance element 31a and the first inner resonance element 33a arranged in this way may be arranged in a spiral shape as one element. As shown in FIG. 1D, the spiral means the overall diameter of the first outer resonance element 31a and the first inner resonance element 33a when the first outer resonance element 31a and the first inner resonance element 33a are viewed from the front. It is shown that the first outer resonance element 31a and the first inner resonance element 33a are arranged in a spiral so that becomes gradually smaller.

  In the present embodiment, the first straight line portion 37a is interposed between the first straight line portion 37a continuous to the U-shaped first folded portion 39a fixed to the first outer resonance element 31a and the first outer resonance element 31a. It is only necessary that the second linear portion 37b that is continuous with the U-shaped second folded portion 39b that is continuous with the U-shaped second folded portion 39b is disposed. In the present embodiment, the first and second folded portions 39a and 39b are arranged at both ends, but there is no particular limitation as long as one or more folded portions are arranged.

  As shown in FIG. 1F, the first inner resonance element 33a itself may be arranged in a spiral shape. At this time, for example, in a state where the two straight portions 371a and 371b are continuous with each other by one folded portion 391a, the other one straight portion 371c may be disposed between the two straight portions 371a and 371b. .

  The first outer resonance element 31a and the first inner resonance element 33a are, for example, metal materials such as brass, aluminum, and stainless steel. The first outer resonance element 31 a is electrically connected to the power feeding unit 77 and is fed from the power feeding unit 77. The first outer resonance element 31a resonates at a high second frequency band f2. The first inner resonance element 33a is electrically connected to the first outer resonance element 31a at the first folded portion 39a, and is fed from the power feeding section 77 via the first outer resonance element 31a. Therefore, by passing through the first and second folded portions 39a and 39b, the element length is increased and the resonance frequency band is lowered. The first inner resonance element 33a resonates in the lower first frequency band f1 by the first and second folded portions 39a and 39b. The first outer resonance element 31a and the first inner resonance element 33a are arranged in a spiral shape as one element and are not in contact with each other, so that the first frequency band f1 and the second frequency band f2 that are shared are used. Is suppressed from interfering.

  In the present embodiment, the first inner resonance element 33a that resonates in the lower first frequency band f1 is disposed inside the outer resonance element that resonates in the higher second frequency band f2 by the first and second folded portions 39a and 39b. . Thereby, in this embodiment, the configuration of the dual-frequency omnidirectional antenna 10 can be simplified, the two frequency bands f1 and f2 can be shared, and the two shared frequency bands f1 and f2 are prevented from interfering with each other. it can. The first outer resonance element 31a and the first inner resonance element 33a are arranged in a spiral shape as one element and are not in contact with each other. In a state where the first straight portion 37a is arranged away from the first outer resonance element 31a, the second straight portion 37b is arranged between the first straight portion 37a and the first outer resonance element 31a. Therefore, it is possible to reliably suppress interference between the two shared frequency bands. In the collinear array antenna 20 as well, it is possible to suppress interference between the two shared frequency bands f1 and f2.

  The present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment.

  DESCRIPTION OF SYMBOLS 10 ... Dual frequency omnidirectional antenna, 20 ... Collinear array antenna, 30 ... Upper side resonance unit, 31a ... First outer resonance element, 31b ... Second outer resonance element, 33a ... First inner resonance element, 33b ... Second Inner resonance element, 37a ... first straight part, 37b ... second straight part, 39a ... first folded part, 39b ... second folded part, 50 ... lower resonant unit, 70 ... support part, 71 ... main body plate member, 73 ... Rod-shaped member, 77 ... Power feeding unit, 79 ... Distribution matching line.

Claims (3)

A dual-frequency omnidirectional antenna having a folded dipole structure,
An outer resonant element continuously having a U-shaped cross section in the longitudinal direction and resonating in a high frequency band;
An inner resonance element that is continuous with the outer resonance element and has a folded portion for resonating in a low frequency band, and is disposed inside the outer resonance element along the longitudinal direction of the outer resonance element;
A dual-frequency omnidirectional antenna characterized by comprising:   2. The dual-frequency omnidirectional antenna according to claim 1, wherein the outer resonance element and the inner resonance element are arranged in a spiral shape as one element.   A collinear array antenna, wherein the dual-frequency omnidirectional antenna according to claim 1 is multistaged using a distribution matching line.