JP2012191501A - Antenna device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To implement an omnidirectional dual-polarized antenna ensuring a high gain and a satisfactory antenna characteristic in a compact antenna size.SOLUTION: An antenna device includes: a plurality of first antennas for radiating a vertically polarized radio wave; a plurality of second antennas fed from a different feeder from and at the same feeding phase as the first antennas for radiating a horizontally polarized radio wave; and a support member supporting the first and second antennas. The second antennas are arranged alternately with the first antennas, and the second feeder for feeding the second antennas is arranged such that regions opposed to the first antennas are nearer to the first antennas than feeding points to the second antennas.

Description

  The present invention relates to an antenna device, and more particularly to a technique that is preferably applied to an omnidirectional dual-polarization antenna.

  As mobile radio communication is used rapidly, the communication capacity is increased and the communication speed is increased. For this reason, sufficient communication capacity and communication speed cannot be obtained in one frequency band, and the communication capacity and communication speed are secured by allocating the second and third frequency bands to each communication company. When a plurality of frequency bands are used for one mobile radio communication, it is preferable to configure the antennas separately for each frequency band, but it may be difficult to configure the antennas separately due to the location conditions of the base station. . Therefore, a multi-frequency shared antenna is required in such a case.

  There are two types of multi-frequency antennas, directional type and non-directional type, but base stations such as PHS often form a service area in a circular area without dividing it into a fan-shaped area. Therefore, in order to transmit radio waves uniformly around the base station, many non-directional types are adopted.

  In mobile radio communications, vertical polarized radio waves are often used in consideration of the influence of obstacles and communication distances. However, with the increase in user service usage due to the recent trend toward broadband, further communication quality has increased. In order to improve radio wave reception efficiency, it may be preferable to use a mixture of vertically polarized antennas and horizontally polarized antennas. Further, in order to enable each communication carrier to provide a high-quality communication service to users, it is also required that a high gain can be secured as an antenna used for mobile radio communication.

  In particular, as a method for ensuring a high gain with respect to vertical polarization, there is a method (multistage collinear) in which a plurality of elements are stacked in multiple stages in the vertical direction to constitute an antenna. Multi-stage collinear consists of λ (wavelength, the same applies below) / 2 elements made of coaxial lines, and the coaxial wire's inner and outer conductors are alternately connected every other λ / 2 (coaxial Crossed multi-stage collinear), λ / 2 electrical length coil or U-shaped stub connected in series with λ / 2 element (phase-inverted coil type multi-stage collinear), coaxial conductor outer conductor A cylindrical dipole antenna is attached to the periphery of the circumferential slot formed in (1), and the dipole antennas are stacked in multiple stages (coaxial dipole type multistage collinear).

  For example, Patent Document 1 discloses a dual-frequency dual-polarized antenna that has a simple structure and can reduce manufacturing costs. The dual-frequency dual-polarized antenna according to the cited document 1 includes a first printed board including a plurality of vertical polarization elements that function as antenna elements for vertical polarization, and a first feeding circuit connected to the elements. A second printed circuit board having a plurality of parallel polarization elements that function as antenna elements for horizontal polarization and a second feeder circuit connected to the elements, and parallel to the vertical polarization elements The polarization elements are arranged alternately in one direction.

International Publication No. 08/136455

  Since the antenna of Cited Document 1 has the antenna elements of each frequency and each polarization alternately arranged at a short distance, if the antenna is used for non-directional applications without the reflector, each antenna interferes. As a result, there is a problem that the main beam becomes left-right unbalanced, and the non-directionality is deteriorated due to the phase difference (distorted directivity).

  For the above problem, each polarization element is collectively multi-staged (for example, a horizontal polarization element is arranged in an overlapping manner to form a horizontal polarization multi-stage collinear, and above (or below), By arranging a multi-stage collinear for vertical polarization similarly configured), both omnidirectionality and high gain can be ensured. However, this increases the size of the antenna device (because a multi-stage collinear for vertical polarization is placed on top of a multi-stage collinear for horizontal polarization. This is contrary to the situation where a multi-polarization antenna and a multi-frequency antenna are required due to the location conditions of the base station. It is desirable that the multi-polarization antenna and the multi-frequency antenna be configured with the same size as the single-polarization antenna and the single-frequency antenna.

  Accordingly, an object of the present invention is to realize an omnidirectional dual-polarization antenna that can secure a high gain and obtain good antenna characteristics without increasing the antenna size.

  The antenna device of the present invention includes a plurality of first antennas that radiate vertically polarized radio waves, and a plurality of antenna apparatuses that are arranged and fed with the same feeding phase from a feeding line different from the first antenna, and that are horizontally polarized radio waves. And a support member that supports the first and second antennas. The second antennas are arranged alternately with the first antennas, and the second antennas The second feeding line to be fed is arranged so that the region facing the first antenna is closer to the first antenna side than the feeding point to the second antenna.

  Further, in the above antenna device, the region where the second feeding line faces the first antenna is located outside the first antenna and closer to the first antenna side than the feeding point to the second antenna. It may be arranged.

  Further, in the above antenna device, the support member is configured by a substrate disposed outside the first antenna, and the second feeder is configured by a linear pattern formed on the substrate. There may be.

  In the antenna device described above, a part of the region where the second feeder line faces the radio wave radiation position of the first antenna in the region facing the first antenna is higher than the other region in the region. It may be arranged so as to be located outside the one antenna.

  Further, in the above antenna device, the second antenna has a hollow shape through which the first feed line feeding the first antenna can pass and a part thereof is connected to the second feed line. A plurality of dipole antennas arranged in a direction perpendicular to the surface may be used.

  In the antenna device described above, the first antenna may be constituted by a plurality of dipole antennas arranged in multiple stages along the same central axis in a direction perpendicular to the installation surface.

  According to the present invention, it is possible to realize a non-directional type dual-polarized antenna that can secure a high gain and obtain good antenna characteristics without increasing the antenna size.

It is the side view which showed the structure of the antenna apparatus of 2 frequency 2 polarization shared type type | mold which concerns on embodiment of this invention. It is sectional drawing which showed the structure of the antenna apparatus (antenna for perpendicular polarization | polarized-light) of 2 frequency 2 polarization shared type which concerns on embodiment of this invention. It is the perspective view which showed the structure of the antenna apparatus (antenna for horizontal polarization | polarized-light) of the dual frequency 2 polarized-wave type | mold type which concerns on embodiment of this invention. It is a figure explaining the relationship of the distance between the antenna element for vertical polarization, and the feed line for horizontal polarization in embodiment of this invention. It is the figure which showed the antenna characteristic (omnidirectional degree in the horizontal surface of the antenna for vertical polarization) of the dual-frequency dual-polarization antenna device according to the embodiment of the present invention. It is the figure which showed the antenna characteristic (omnidirectional degree in the horizontal surface of the antenna for vertical polarization) of the dual-frequency dual-polarization antenna device according to the embodiment of the present invention.

  In the dual-polarized antenna, when the horizontally polarized antenna and the vertically polarized antenna are stacked in multiple stages, there is little interference between the same polarized antennas. Ideally). Such a simple layering provides good antenna characteristics, but at the expense of miniaturization of the device. Depending on the location conditions of the base station, there is a need to configure a multi-frequency shared antenna with the same size as a single-frequency antenna, or a dual-polarized shared antenna with the same size as a single polarized antenna. In some cases, the above simple overlap cannot be adopted.

  In order to construct a dual-polarized antenna having the same size as a single-polarized antenna, it is necessary to incorporate the other polarized antenna group into one polarized antenna group that is stacked in multiple stages. As one of the methods, it can be considered that the horizontally polarized antennas and the vertically polarized antennas are alternately stacked in multiple stages (so-called alternate stacking). However, as described in the above simple overlap, interference between antenna elements is larger in different polarization antennas than in the same polarization antenna.

  On the other hand, the present invention intends to suppress interference between each polarization antenna by devising the arrangement of each polarization antenna and the arrangement of the feed line of the horizontal polarization antenna. . For the former, one polarized wave is used so that the radio radiation position of the vertically polarized antenna is not covered by the horizontally polarized antenna, and the radio wave radiation position of the horizontally polarized antenna is not covered by the vertically polarized antenna. Another polarization antenna is arranged in the middle position between the antennas for use. By preventing the radio wave radiation position from being applied to the other polarized antenna, interference with both polarized waves can be suppressed. For the latter, the feed line of the horizontally polarized antenna is placed as close as possible to the vertically polarized antenna and is arranged along the direction of arrangement of the vertically polarized antenna. By bringing the feed line of the horizontally polarized antenna close to the vertically polarized antenna, deterioration of omnidirectionality on the horizontal plane of the vertically polarized antenna can be suppressed.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a side view showing the configuration of a dual-frequency dual-polarization antenna device according to an embodiment of the present invention. In the present embodiment, a coaxial dipole antenna is employed as the vertically polarized antenna, and a horizontal dipole antenna is employed as the horizontally polarized antenna. A coaxial dipole antenna is known as a general antenna technology, and a metal-made cylindrical dipole antenna is placed so as to be opposed to each other across an excitation slot provided in the circumferential direction of the outer conductor of the coaxial line. It is a thing. The horizontal dipole antenna in this embodiment is a so-called T-shaped dipole antenna that is curved in a circumferential shape (annular shape) (see FIG. 3).

  Further, the antenna device 1 of the present embodiment radiates radio waves in two frequency bands of 1.9 GHz band and 2.5 GHz band as a dual frequency shared type. The 1.9 GHz band radio wave is radiated from the horizontally polarized dipole antenna element 21, and the 2.5 GHz band radio wave is radiated from the vertically polarized dipole antenna element 11.

  First, the configuration of the vertically polarized antenna will be described. Also in this embodiment, like a general coaxial dipole antenna, the vertically polarized dipole antenna element 11 has an excitation slot (not shown) provided in the circumferential direction of the outer conductor 12c (FIG. 2) of the coaxial line 12. It is arranged so as to make a pair facing each other. In this embodiment, a joining flange 13 (FIG. 2) made of the same metal as the vertically polarized dipole antenna element 11 and a coupling member 14 (FIG. 2) made of a resin material such as Teflon (registered trademark) or polyacetal are provided. Using it, the arrangement as a coaxial dipole antenna is realized.

  The interval at which the excitation slots are provided is 0.7 times (0.7λ) the wavelength of the radiated radio wave, for example, when the coaxial line 12 uses an insulator such as polyethylene as a dielectric. The pair of vertically polarized dipole antenna elements 11 forming a pair is provided so as to have a length of a half wavelength (λ / 2) of a radio wave radiated in the axial direction of the coaxial dipole antenna. The excitation slot serves as an excitation wave source, and power is fed from the excitation slot to the vertically polarized dipole antenna element 11 to radiate λ radio waves.

  FIG. 2 is a cross-sectional view showing a configuration of a dual-frequency dual-polarization antenna device (vertical polarization antenna) according to an embodiment of the present invention. 2A is a sectional view of a plane perpendicular to the axial direction of the antenna (a plane cut along line AA ′ in FIG. 1), and FIG. 2B is a plane parallel to two coaxial feed lines. Sectional drawing (surface cut | disconnected by the BB 'line | wire in FIG. 1) is represented.

  A coaxial line 12 for feeding power to the vertically polarized dipole antenna element 11 is disposed so as to pass through a cylinder of the vertically polarized dipole antenna element 11 formed of a cylindrical conductive member. The coaxial line 12 is a general coaxial cable and includes an inner conductor 12a, a dielectric 12b, and an outer conductor 12c.

  The joining flange 13 is a conductive member having a fitting portion that fits into the cylindrical vertically polarized dipole antenna element 11 and a hole portion through which the coaxial line 12 passes, and the vertically polarized dipole antenna element 11 is connected to the joining flange 13. While fixing to a fixed position, the coaxial line 12 is supported. Further, the joining flange 13 has a depressed portion for receiving the fitting of the coupling member 14.

  The coupling member 14 is a non-conductive member having a fitting portion that fits into the depressed portion of the joint flange 13 and a hole portion through which the coaxial line 12 that feeds power to the vertically polarized dipole antenna element 11 passes. The vertically polarized dipole antenna element 11 is coupled and the coaxial line 12 is supported.

  The coaxial line 12 that passes through the holes of the joint flange 13 and the coupling member 14 has the outer conductor 12c cut off at least in the power feeding portion (XX ′) (the inner conductor 12a is in an exposed state) Gap power feeding is performed when a current flows through the conductor 12a. Further, the region where the inner conductor 12a is exposed can be a range from Y to Y 'at the maximum.

  The coaxial dipole antenna of the present embodiment is basically constructed by stacking a pair of vertically polarized dipole antenna elements 11 facing each other in multiple stages in the axial direction (so-called multistage collinear), but the bottom stage is not a pair. The joining flange 13 is fitted and arranged on the vertically polarized dipole antenna element 11 (the coupling member 14 is not fitted because of the super top described later). Then, in order to prevent leakage of high-frequency current to the lowermost vertically polarized dipole antenna element 11, the outer conductor 12c of the coaxial line 12 is exposed at a portion passing through the joint flange 13 fitted to the dipole antenna, The joining flange 13 and the outer conductor 12c are connected (super top). On the other hand, in the uppermost stage, the inner conductor 12a of the coaxial line 12 is connected to the joint flange 13 fitted to the upper vertically polarized dipole antenna element 11.

  Next, the configuration of the horizontally polarized antenna will be described. In the present embodiment, a feed line is connected to a horizontally polarized dipole antenna element in which an element of a T-shaped dipole antenna is curved in an annular shape (circumferential shape). What is characteristic here is that a line-shaped antenna pattern formed on a substrate is used as a feed line for a horizontally polarized antenna, and an antenna (coaxial dipole antenna (vertically polarized antenna) and horizontal dipole antenna ( This is a function of supporting a horizontally polarized antenna)).

  As a component of the antenna device, in addition to the antenna and the feed line, as a matter of course, a support member for supporting the antenna elements and feed lines stacked in multiple stages as described above is also necessary. On the other hand, considering the miniaturization of the apparatus, it is desirable to reduce the number of parts as much as possible. In view of this, in the present embodiment, the substrate is used as a support member, and a feed line for a horizontally polarized antenna is formed on the substrate, and the support member such as an antenna element is shared with the feed line to reduce the number of components. We are trying to reduce it.

  FIG. 3 is a perspective view showing a configuration of a dual-frequency dual-polarization type antenna device (horizontal polarization antenna) according to an embodiment of the present invention. The horizontally polarized dipole antenna element 21 has two substantially semicircular conductive members (T-shaped dipole antenna elements curved in a circumferential shape) attached to both sides of the substrate 31, and the mounting side. A circular shape (annular shape) having a predetermined gap on the opposite side is formed. Further, the horizontally polarized dipole antenna elements 21 are arranged alternately with the pair of vertically polarized dipole antenna elements 11, that is, at positions where the respective radio wave radiation positions alternate and do not overlap the other antenna.

  The parallel two wires 22 that feed power to the horizontally polarized dipole antenna element 21 are formed on the substrate 31 as a line-shaped antenna pattern by etching a metal-based conductive material (such as copper). The parallel two wires 22 are positioned within the circumference of the horizontally polarized dipole antenna element 21 and are formed so as to be close to the antenna element at least in a region facing the vertically polarized dipole antenna element 11. . The parallel two wires 22 are provided with a phase adjustment bypass 22 a in a region opposite to the radio wave radiation position (excitation slot position) of the vertically polarized dipole antenna element 11. The phase adjustment detour 22a has a role of adjusting the feeding phase of the horizontally polarized dipole antenna element 21 according to the detour distance. When it is desired to advance the power feeding phase of each element, if the detour is shortened, the phase difference increases, and if the detour is long, the phase difference decreases.

  It is also possible to adjust the feeding phase to the vertically polarized dipole antenna element 11. Since the feed line to the dipole antenna 11 is a coaxial line, the feed phase can be adjusted by using materials having different dielectric constants for the dielectric. For example, when the dielectric 12b of the coaxial line 12 is made of polyethylene, the wavelength shortening rate is about 66%. Therefore, the interval (element interval) between the excitation slots (radiation positions) corresponding to the 0 ° position of the feeding phase is as follows. 0.7λ. Here, the wavelength shortening rate is the rate at which the wavelength of the current flowing through the coaxial feeder (the wavelength of the radio wave to be radiated) is shortened. On the other hand, when the dielectric 12b is air, the wavelength shortening rate is about 100%, and therefore the interval (element interval) between the excitation slots (radiation positions) corresponding to the 0 ° position of the feeding phase is 1λ. .

  The substrate 31 has a function of supporting the vertical polarization dipole antenna element 11 and the horizontal polarization dipole antenna element 21 as described above, while holding the feeder by forming the parallel two wires 22 on the surface. ing. The substrate 31 has an antenna positioning groove 31a formed at the end facing the vertically polarized dipole antenna element 11, and a band positioning groove 31b formed at the end opposite to the facing side. The antenna positioning groove 31 is used for positioning when the vertically polarized dipole antenna element 11 is fixed to the substrate 31 in manufacturing the antenna device 1. An element fixing band 41 is used to fix the vertically polarized dipole antenna element 11 to the substrate 31. The band positioning groove 31 b is used for positioning the element fixing band 41.

  In the present embodiment, in addition to the element fixing band 41, the antenna support spacer 42 is further used to fix the coaxial dipole antennas arranged in multiple stages to the substrate 31. In FIG. 1, the element fixing band 41 is used for all the pair of vertically polarized dipole antenna elements 11, and every other antenna support spacer 42 is used. The antenna support spacer 42 reinforces the support of the vertically polarized dipole antenna element 11 by the substrate. The antenna supporting spacer 42 may be used for all the pair of vertically polarized dipole antenna elements 11 together with the element fixing band 41, or only the antenna supporting spacer 42 may be used without using the element fixing band 41. The element fixing band 41 and the antenna support spacer 42 can be appropriately selected in terms of material and quantity as long as the antenna characteristics are not affected.

  In FIG. 1, the same number of the vertically polarized dipole antenna elements 11 and the horizontally polarized dipole antenna elements 21 are arranged. Accordingly, the number of antennas can be changed as appropriate. In addition, in the uppermost stage and the lowermost stage, either the vertically polarized dipole antenna element 11 or the horizontally polarized dipole antenna element 21 may be arranged.

  The coaxial line 12 connected from the bottommost vertically polarized dipole antenna element 11 (in the direction opposite to the direction in which the dipole antenna group is arranged) and the parallel two wires 22 at the lowermost end of the substrate 31 are Are connected to the connection terminal 51a and the connection terminal 51b, respectively. Although not shown, a balun portion having a balanced / unbalanced conversion function is required on the lower side of the feed line 22 of the horizontally polarized dipole antenna 21. In this embodiment, a super-top is used. Yes. Moreover, you may comprise so that a matching circuit may be connected with connection terminal 51a, 51b suitably.

  Furthermore, in this embodiment, the filter unit for improving the two-wave isolation is not provided. However, the filter unit may be appropriately disposed as necessary to obtain a desired isolation. Good. If a filter unit is provided, the filter unit is provided on the downstream side of the balun, and if a matching circuit is provided, the filter unit is disposed and connected between the balun and the filter. Further, in the present embodiment, the connection terminal is provided for each coaxial line. However, the connection terminal may be configured to be one by using a synthesis circuit that synthesizes two coaxial lines. Even in this case, the filter portion can be appropriately arranged as necessary.

  FIG. 4 is a diagram for explaining the relationship between the distance between the vertically polarized antenna element and the horizontally polarized feed line in the present embodiment, and FIGS. 5 and 6 are dual frequency dual polarization shared types according to the present embodiment. It is the figure which showed the antenna characteristic (The omnidirectional degree in the horizontal surface of the antenna for vertically polarized waves) of the antenna apparatus.

  5 and 6 corresponds to d in FIG. 4, and the omnidirectionality (roundness) in FIGS. 5 and 6 is the xy plane (vertical) in FIG. It represents the electric field in the horizontal plane of the polarization antenna. The degree of omnidirectionality (roundness) is expressed in dB, and the smaller the value, the more directivity without distortion. As shown in FIG. 5, when the distance between the element and the feeder line is 8 mm, the omnidirectionality (roundness) is 2.1 dB, 10 mm is 2.57 dB, 20 mm is 3.85 dB, 30 mm. In this case, it is 4.27 dB. As can be seen from the graph, the smaller the distance between the element and the feeder line, the more directivity without distortion. Also in FIG. 6, it can be seen that the smaller the distance between the element and the feeder line, the more non-directional (the pattern is a perfect circle). As described above, it is possible to suppress deterioration of omnidirectionality in the horizontal plane of the vertically polarized antenna by bringing the feed line of the horizontally polarized antenna close to the vertically polarized antenna.

  The above-described embodiment is a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention to the above-described embodiment alone, but in a form in which various modifications are made without departing from the gist of the present invention. Implementation is possible.

  For example, the antenna device to which the present invention is applied is not a dual-frequency antenna (a dual-frequency dual-polarization antenna device) as in the above embodiment, but a single-frequency antenna device (a single-frequency dual-polarization antenna device). There may be. Even in this case, if the vertically polarized antenna elements and the horizontally polarized antenna elements are alternately arranged at the center position of each element as in the above embodiment, a phase shift occurs. It is possible to suppress the deterioration of the influence on directivity.

  Further, in the above embodiment, if the feed line of the horizontally polarized antenna is arranged within the circumference of the horizontally polarized dipole antenna element 21 and as close as possible to the vertically polarized dipole antenna element 11, It may be outside or inside the vertically polarized dipole antenna element 11. For example, the feed line of the horizontally polarized antenna is constituted by a coaxial line or the like and is passed through the inside of the vertically polarized dipole antenna element 11 from the intermediate position between the antenna elements (the radio wave radiation position of the horizontally polarized antenna). It may be configured to be connected to a direction perpendicular to the axial direction with a conducting wire or the like and to feed the horizontally polarized dipole antenna element 21 attached to the substrate 31.

DESCRIPTION OF SYMBOLS 1 Antenna apparatus 11 Vertically polarized dipole antenna element 12 Coaxial line 12a Inner conductor 12b Dielectric 12c Outer conductor 13 Joint flange 14 Connecting member 21 Horizontally polarized dipole antenna element 22 Parallel two wires 22a Phase adjustment bypass 31 Substrate 31a Antenna Positioning groove 31b Band positioning groove 41 Element fixing band 42 Antenna support spacer 51 Connection terminal

Claims (6)

A plurality of first antennas that radiate vertically polarized radio waves;
A plurality of second antennas that are fed at the same feeding phase from a feeding line different from the first antenna and radiate horizontally polarized radio waves;
A support member for supporting the first and second antennas;
Have
The second antennas are arranged alternately with the first antennas, and the second feed line feeding the second antenna has a region facing the first antenna to the second antenna. The antenna device is arranged so as to be closer to the first antenna side than the feeding point.   The second feeding line is arranged so that a region facing the first antenna is outside the first antenna and closer to the first antenna side than a feeding point to the second antenna. The antenna device according to claim 1, wherein:   The said support member is comprised by the board | substrate arrange | positioned on the outer side of the said 1st antenna, The said 2nd electric power feeding line is comprised by the linear pattern formed on the said board | substrate. Item 3. The antenna device according to Item 1 or 2.   The second feeder line has a part of the region facing the radio wave radiation position of the first antenna in the region facing the first antenna, the part of the first antenna being more than the other region in the region. The antenna device according to any one of claims 1 to 3, wherein the antenna device is disposed so as to be located outside.   The second antenna has a hollow shape through which the first feed line feeding the first antenna can pass, and a direction perpendicular to the installation surface is connected to the second feed line. 5. The antenna device according to claim 1, wherein the antenna device includes a plurality of dipole antennas.   The said 1st antenna is comprised with the dipole antenna arrange | positioned in multiple stages along the same central axis in the direction perpendicular | vertical to an installation surface, The any one of Claim 1 to 5 characterized by the above-mentioned. The antenna device described.

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