JP2016140046A - Dual-polarized antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid a performance deterioration of a vertically polarized antenna.SOLUTION: A dual-polarized antenna includes: a conductor plate 1; four vertically polarized antennas 2 disposed on the conductor plate 1 in a manner to form a 90-degree rotation symmetry; a feedline 3 having a transmission line 31 disposed on a rotation symmetry axis O, and a transmission line 32 connected in a bent shape to the transmission line 31; four horizontally polarized antennas 4 connected to the transmission line 32 of the feedline 3 and disposed in parallel to the conductor plate 1 in a manner to form a 90-degree rotation symmetry with respect to the rotation symmetry axis O; and a feeder circuit which supplies each vertically polarized antenna 2 with power whose phase is shifted by 90 degrees between the adjacent vertically polarized antennas 2, and shifted by 180 degrees between the opposite vertically polarized antennas 2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a horizontal plane omnidirectional polarization-sharing antenna suitable for a small radio base station installed indoors, in an underground shopping center or the like where radio waves from a radio base station installed outdoors do not reach.

  Since the mobile phone communicates via a radio base station installed outdoors, the communication is interrupted in an indoor area, underground mall, or the like where radio waves from the radio base station do not reach. For this reason, small wireless base stations that can be installed indoors are arranged at appropriate locations to complement the communication area.

With the recent diversification of communication services and the increase in users and communication volume, the demands for antennas of radio base stations are increasing.
For example, the frequency band used in a mobile phone includes a 700 MHz band, a 900 MHz band, a 1.5 GHz band, and a 1.7 GHz band defined by LTE (Long Term Evolution) in addition to the conventional 800 MHz band and 2 GHz band. An antenna corresponding to such multi-frequency is required.

  Further, when covering an elongated area such as a tunnel, bidirectional directivity is required on the horizontal plane, but in order to cover a wide area such as an underground shopping street, omnidirectionality is required on the horizontal plane.

  Furthermore, in order to cope with an increase in communication traffic, it is necessary to multiplex communication using MIMO (Multi Input Multi Output) technology. Since indoor radio base stations are required to be miniaturized, a polarization MIMO system using a vertically polarized antenna and a horizontally polarized antenna is often used.

  In response to such a demand, n monopolar antennas for vertical polarization (hereinafter referred to as vertical polarization antennas) and dipole antennas for horizontal polarization (hereinafter referred to as horizontal polarization antennas) are arranged rotationally symmetrically, An antenna in which these are in-phase excited is known (see, for example, Patent Document 1). With this configuration, a non-directional radiation pattern can be obtained in a horizontal plane.

International Publication No. 2014/034490

  As described above, since the indoor radio base station is required to be downsized, a sufficient interval between the vertically polarized antenna and the horizontally polarized antenna cannot be secured. Therefore, it is common to arrange a vertically polarized antenna on a substrate serving as a ground conductor, and to arrange a horizontally polarized antenna above the vertically polarized antenna.

  However, since the circuit unit that controls the wireless function such as the transceiver is disposed on the substrate, it is necessary to provide a feed structure perpendicular to the substrate between the horizontally polarized antenna and the substrate. This vertical feeding structure has a problem that it has a great influence on a vertically polarized antenna. The antenna disclosed in Patent Document 1 does not show a feed structure for a horizontally polarized antenna, but it is considered that the same problem occurs in practical use.

  The present invention has been made to solve the above-described problems, and avoids deterioration of the performance of the vertically polarized antenna in the dual polarization antenna in which the horizontally polarized antenna is disposed above the vertically polarized antenna. An object of the present invention is to provide a dual-polarized antenna that can be used.

  The dual-polarized antenna according to the present invention includes a conductor plate, four monopole antennas arranged so as to be 90-degree rotationally symmetric on the conductor plate, and a first axis arranged on the rotational symmetry axis of the monopole antenna. A transmission line having a second transmission line bent and connected to the first transmission line and a second transmission line connected to the second transmission line, and parallel to the conductor plate and rotated. Four dipole antennas arranged so as to be 90-degree rotationally symmetric with respect to the axis of symmetry, and each monopole antenna being 90 degrees out of phase with the adjacent monopole antenna, and facing monopoles And a power feeding circuit that supplies power with a phase difference of 180 degrees with respect to the antenna.

  According to the present invention, since it is configured as described above, it is possible to avoid the deterioration of the performance of the vertical polarization antenna in the dual polarization antenna in which the horizontal polarization antenna is disposed above the vertical polarization antenna.

It is a top view which shows the structure of the polarization sharing antenna which concerns on Embodiment 1 of this invention. FIG. 2 is a cross-sectional view taken along line A-A ′ of FIG. 1. It is a figure which shows arrangement | positioning of the vertically polarized antenna in Embodiment 1 of this invention. It is a figure which shows the calculation result of the synthetic | combination pattern at the time of exciting the vertically polarized antenna in Embodiment 1 of this invention with the same amplitude and the same phase. It is a figure which shows the calculation result of the synthetic | combination pattern at the time of exciting the vertically polarized antenna in Embodiment 1 of this invention with the same amplitude and 90 degree phase difference. It is a top view which shows the structure of the polarization sharing antenna which concerns on Embodiment 2 of this invention. FIG. 7 is a sectional view taken along line B-B ′ of FIG. 6. It is a top view which shows the structure of the polarization sharing antenna which concerns on Embodiment 3 of this invention. FIG. 9 is a sectional view taken along line C-C ′ of FIG. 8. It is a top view which shows the structure of the polarization sharing antenna which concerns on Embodiment 4 of this invention. It is D-D 'sectional drawing of FIG. It is a figure which shows another structure of the vertically polarized antenna in Embodiment 4 of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Embodiment 1 FIG.
1 is a top view showing a configuration of a dual-polarized antenna according to Embodiment 1 of the present invention, and FIG. 2 is a cross-sectional view taken along line AA ′ of FIG. In FIG. 2, the feed line 3-4 and the horizontally polarized antenna 4 are not shown.
As shown in FIGS. 1 and 2, the polarization-sharing antenna has a conductor plate 1 that is a flat conductor having a finite size. In the figure, the conductor plate 1 has a square shape. However, the shape is not limited to this, and the shape can be freely selected, for example, a circle or a rectangle according to the outer shape of the dual-polarized antenna and the set location. . Moreover, in the following description, the case where the conductor plate 1 is arrange | positioned in parallel with the ground is assumed, and the surface containing the conductor plate 1 is defined as a horizontal surface. Further, the case where the electric field vibrates perpendicularly to the conductor plate 1 is defined as vertical polarization, and the case where the electric field vibrates parallel to the conductor plate 1 is defined as horizontal polarization.

On this conductor plate 1, four vertically polarized antennas 2 (2-1 to 2-4), which are four monopole antennas, are provided perpendicular to the conductor plate 1 (including a substantially vertical meaning). It has been. The length of the vertically polarized antenna 2 is set to be about 1/4 of the wavelength with respect to the frequency used in the dual polarization antenna. Each vertically polarized antenna 2 is arranged so as to be 90 degrees rotationally symmetric with respect to an axis (rotation symmetry axis O) that passes through a certain point on the conductor plate 1 and is perpendicular to the conductor plate 1. . Further, the contact end of each vertically polarized antenna 2 with the conductor plate 1 is connected to a first power feeding circuit (not shown) formed on the conductor plate 1.
This power feeding circuit has a power that is 90 degrees out of phase with the adjacent vertically polarized antenna 2 and 180 degrees out of phase with the opposite vertically polarized antenna 2 with respect to each vertically polarized antenna 2. Supply. Note that the amplitude of the power supplied to each vertically polarized antenna 2 is the same.

  1 and 2 show the case where the vertically polarized antenna 2 is a cylindrical conductor whose contact end with the conductor plate 1 is conical. However, the present invention is not limited to this. For example, the vertically polarized antenna 2 may be patterned on the dielectric substrate by etching or the like, and the dielectric substrate may be vertically set on the conductor plate 1.

  On the conductor plate 1, four feed lines 3 (3-1 to 3-4) for supplying power to a horizontally polarized antenna 4 described later are provided. As shown in FIG. 2, the feed line 3 is a transmission line that is bent in an L shape, and a transmission line (first transmission line) 31 disposed on the rotationally symmetric axis O of the vertical polarization antenna 2. And a transmission line (second transmission line) 32 that is bent and connected to the transmission line 31. The contact end of each transmission line 31 with the conductor plate 1 is connected to a second power feeding circuit (not shown) formed on the conductor plate 1. In FIGS. 1 and 2, the positions of the transmission lines 31 are shown apart from the rotational symmetry axis O for easier viewing of the drawings, but the positions of the transmission lines 31 should be closer to the axis of the rotational symmetry axis O. Good. As the feed line 3, a line having a predetermined characteristic impedance such as a coaxial line, a strip line, a microstrip line, or the like can be used.

Further, at the front end of the transmission line 32 of each feed line 3, horizontal polarization antennas 4 (4-1 to 4-1), which are four dipole antennas arranged parallel to the conductor plate 1 (including substantially parallel meaning). 4-1) are connected to each other. The horizontal polarization antenna 4 is disposed above the vertical polarization antenna 2. In the horizontally polarized antenna 4, the end of the transmission line 32 of the feed line 3 is connected to the center position in the line direction. The horizontal polarization antenna 4 is set so that the length of one side from the center position in the line direction is about ¼ of the wavelength with respect to the frequency used in the polarization sharing antenna. Each horizontally polarized antenna 4 is arranged so as to be 90 degrees rotationally symmetric with respect to the rotational symmetry axis O of the vertically polarized antenna 2.
Each horizontal polarization antenna 4 is supplied with electric power having the same amplitude and the same phase from the second feeding circuit via the feeding line 3.

  1 and 2 show the case where the horizontally polarized antenna 4 is a planar conductor. However, the present invention is not limited to this. For example, the horizontal polarization antenna 4 may be patterned on a dielectric substrate by etching or the like.

Next, the operation of the dual-polarized antenna according to Embodiment 1 will be described.
When element antennas are arranged with a predetermined interval, an array antenna is formed that can form various radiation patterns by changing the excitation amplitude and the excitation phase. In the first embodiment, with respect to vertical polarization, a four-element circular array antenna having four vertical polarization antennas 2 as element antennas is configured. Similarly, with respect to horizontal polarization, a four-element circular array antenna having four horizontal polarization antennas 4 as element antennas is configured.

In addition, the dipole antenna has an 8-shaped directivity in a plane including the dipole antenna.
In the first embodiment, four horizontally polarized antennas 4 which are dipole antennas are arranged 90 degrees rotationally symmetric and excited with the same amplitude and the same phase. Therefore, a non-directional radiation pattern can be obtained in the horizontal plane.

  On the other hand, the four vertically polarized antennas 2 that are monopole antennas have non-directional radiation patterns in a horizontal plane. Here, in the conventional antenna, as described above, the vertically polarized antenna has an impedance frequency characteristic in particular due to the influence of the vertical feed structure of the horizontally polarized antenna (corresponding to the transmission line 31 of the feed line 3 of the present invention). The desired operation cannot be obtained. On the other hand, in the first embodiment, the above problems can be solved by exciting each vertically polarized antenna 2 with the same amplitude and a phase difference of 90 degrees. The principle will be described in detail below.

  When the four vertically polarized antennas 2 are excited with the same amplitude and a phase difference of 90 degrees, for example, the excitation phase difference between the vertically polarized antenna 2-1 and the vertically polarized antenna 2-3 shown in FIG. Thus, the relationship is reversed. Accordingly, the phases of the electric fields radiated from the two antennas 2-1 and 2-3 are opposite to each other, so that the electric fields cancel each other on the rotational symmetry axis O having the same distance from both the antennas 2-1 and 2-3. Similarly, the same is true between the vertically polarized antenna 2-2 and the vertically polarized antenna 2-4. That is, the electric field on the rotationally symmetric axis O of the vertically polarized antenna 2 arranged in 90-degree rotational symmetry is 0, and even if a conductor is arranged at this position, the operation of the antenna 2 is not affected. Utilizing this property, the transmission line 31 of the feed line 3 is arranged on the rotational symmetry axis O where the electric field becomes zero. Thereby, it is possible to prevent the transmission line 31 of the feed line 3 from affecting the operation of the vertically polarized antenna 2.

When excitation is performed with a phase difference of 90 degrees, it is convenient for the S parameter of the vertically polarized antenna 2. For convenience of explanation, the port corresponding to the feed point of the vertical polarization antenna 2-1 is the first port, the port corresponding to the feed point of the vertical polarization antenna 2-2 is the second port, and the vertical polarization antenna 2-3. The port corresponding to the feeding point is the third port, the port corresponding to the feeding point of the vertically polarized antenna 2-4 is the fourth port, and the S parameters of the four ports are defined. Since the S parameters of the four ports are equal because of rotational symmetry, here, only the S parameter S ₁ for the first port is shown as the following equation (1).
S ₁ = S ₁₁ −S ₁₃ (1)
Here, S ₁₁ is a reflection coefficient of the vertically polarized antenna 2-1, and S ₁₃ is a mutual coupling between the vertically polarized antennas 2-1 and 2-3.

  That is, the S parameter is determined only by the mutual coupling between the vertical polarization antennas 2 facing the reflection coefficient thereof, and the influence of the adjacent vertical polarization antennas 2 is cancelled. This is advantageous for designing over a wide frequency range such as multi-frequency and broadband.

ここで、Ｅ_０は各垂直偏波アンテナ２の電界振幅であり、ξ_１〜ξ_４は各ポートの励振位相であり、φは水平面内における方位角であり、λは波長である。 Next, the influence of the dual-polarized antenna according to Embodiment 1 on the radiation pattern will be described.
As shown in FIG. 3, the horizontal plane is the xy plane, and the rotationally symmetric axis O of the vertically polarized antenna 2 is the origin. Further, the distance from each rotationally symmetric axis O to each vertically polarized antenna 2 is d. At this time, the combined pattern E (φ) of the four elements in the horizontal plane can be expressed as the following formula (2).

Here, E ₀ is the electric field amplitude of each vertically polarized antenna 2, ξ _{1 to} ξ ₄ are the excitation phases of each port, φ is the azimuth angle in the horizontal plane, and λ is the wavelength.

FIGS. 4 and 5 show the calculation results of the combined pattern when the distance d = 0.1λ, 0.2λ, 0.3λ, and 0.5λ using the formula (2). 4 shows a case where the ports of each vertically polarized antenna 2 are excited with the same amplitude and the same phase, and FIG. 5 shows a case where the ports of each vertically polarized antenna 2 are excited with the same amplitude and a phase difference of 90 degrees. Here, in order to compare the radiation patterns, each peak value is normalized and graphed.
As shown in FIGS. 4 and 5, when the distance d is 0.2λ or less, the gain deviation in the horizontal plane is smaller when excitation is performed with the same amplitude and phase. However, when comparing the distance d with a deviation of 3 dB, which is a general omnidirectional index, it can be seen that in both cases, d = about 0.3λ. That is, it can be said that the gain deviation characteristics in the horizontal plane are the same even when excited with a phase difference of 90 degrees.

As described above, according to the first embodiment, the four vertically polarized antennas 2 are excited with the same amplitude and a phase difference of 90 degrees, and the electric field on the rotational symmetry axis O is set to 0. Since the transmission line 31 of the feed line 3 of the horizontal polarization antenna 4 is arranged on the O, in the dual-polarized antenna in which the horizontal polarization antenna 4 is arranged above the vertical polarization antenna 2, the vertical polarization Even if the antenna 2 and the vertical feed structure (transmission line 31 of the feed line 3) of the horizontally polarized antenna 4 are close to each other, deterioration of the performance of the vertically polarized antenna 2 can be avoided.
Furthermore, since the S parameter of each vertical polarization antenna 2 is determined only by the mutual coupling between the vertical polarization antennas 2 facing the reflection coefficient of the vertical polarization antenna 2, it is easy to design over a wide frequency range.

Embodiment 2. FIG.
6 is a top view showing a configuration of a dual-polarized antenna according to Embodiment 2 of the present invention, and FIG. 7 is a cross-sectional view taken along line BB ′ of FIG. In FIG. 7, the illustration of the horizontally polarized antenna 4 is omitted. The dual-polarized antenna according to Embodiment 2 shown in FIGS. 6 and 7 is obtained by replacing the feed line 3 of the dual-polarized antenna according to Embodiment 1 shown in FIGS. 1 and 2 with a feed line 3b. Other configurations are the same, and only the different parts will be described with the same reference numerals.

  The feed line 3b has the same function as the feed line 3 of the first embodiment. As shown in FIGS. 6 and 7, the feed line 3 b includes one transmission line 33 and four transmission lines 34 (34-1 to 34-4).

The transmission line (first transmission line) 33 corresponds to the transmission line 31 of each feed line 3 in the first embodiment, and is disposed on the axis of the rotationally symmetric axis O of the conductor plate 1. A contact end of the transmission line 33 with the conductor plate 1 is connected to a second feeding circuit (not shown) formed on the conductor plate 1.
The transmission line (second transmission line) 34 corresponds to the transmission line 32 of the feed line 3 in Embodiment 1, and is provided for each horizontal polarization antenna 4, and one end is connected to the transmission line 33. The other end is connected to the corresponding horizontally polarized antenna 4.

The transmission line 33 is composed of, for example, a coaxial line, and the transmission line 34 is composed of, for example, a microstrip line. In this case, as shown in FIG. 7, the inner conductor 331 of the transmission line 33 and the signal lines 341 (341-1 to 341-4) of the transmission line 34 are electrically connected, and the outer conductor 332 of the transmission line 33 The ground 342 (342-1 to 342-4) of the transmission line 34 is electrically connected.
Although the transmission line 34 can be made of sheet metal or the like, it is better to form a pattern on the dielectric substrate 5 using etching or the like as shown in FIGS.
In this case, one side of the horizontally polarized antenna 4 is formed on one surface of the dielectric substrate 5 with respect to the connection position with the feed line 3b, and the other side is formed on the other surface of the dielectric substrate 5. Can be formed. Thereby, the horizontally polarized antenna 4 and the transmission line 34 can be integrally formed on the dielectric substrate 5.

As in the first embodiment, the horizontally polarized antenna 4 is excited with the same amplitude and the same phase. At this time, the transmission line 31 of each feed line 3 in the first embodiment is used as one transmission line 33 of the feed line 3b in the second embodiment, and the transmission line 32 of each feed line 3 in the first embodiment is used in the embodiment. There is no difference in the operation principle of the four transmission lines 34 of the feeder line 3b in FIG.
6 and 7, since the transmission line 33 of the feed line 3b can be arranged on the axis of the rotational symmetry axis O, the influence on the vertically polarized antenna 2 is further reduced. be able to.

  Further, since the horizontally polarized antenna 4 is a dipole antenna, a balun (balanced / unbalanced conversion line) is required when power is supplied through an unbalanced transmission line. Therefore, as shown in FIG. 6, the ground 342 of the transmission line 34 is tapered to operate as a balun. As a result, it is possible to suppress performance degradation when power is supplied through an unbalanced transmission line.

  As described above, according to the second embodiment, the feed line 3b in which the transmission lines 31 of the feed lines 3 in the first embodiment are combined into one transmission line 33 is used. Since the vertical feed structure (transmission line 33 of the feed line 3b) can be arranged on the axis of the rotationally symmetric axis O, it is possible to obtain a polarization sharing antenna that further reduces the influence on the vertical polarization antenna 2.

  Further, since the transmission line 34 can be operated as a balun, a dual-polarized antenna that does not deteriorate the performance of the dipole antenna (horizontal polarization antenna 4) that is a balanced antenna can be obtained.

Embodiment 3 FIG.
8 is a top view showing the configuration of the dual-polarized antenna according to Embodiment 3 of the present invention, and FIG. 9 is a cross-sectional view taken along the line CC ′ of FIG. In FIG. 9, the illustration of the horizontally polarized antenna 4 is omitted. The dual-polarized antenna according to the third embodiment shown in FIGS. 8 and 9 is the same as the dual-polarized antenna according to the second embodiment shown in FIGS. ˜6-4) and a non-excitation element (second conductor) 7 (7-1 to 7-4). Other configurations are the same, and only the different parts are described with the same reference numerals.

  The non-excitation element 6 is disposed around each vertically polarized antenna 2 and causes multiple resonance with the corresponding vertically polarized antenna 2. The non-excitation element 6 is arranged perpendicular to the conductor plate 1 (including a substantially vertical meaning). The length of the non-excitation element 6 is set to be about ¼ of the wavelength for the frequency used in the dual-polarized antenna and different from the frequency handled by the vertical polarization antenna 2. The contact end of each non-excitation element 6 with the conductor plate 1 is electrically connected to the conductor plate 1. The distance between the non-excitation element 6 and the corresponding vertically polarized antenna 2 is set so that the non-excited element 6 and the vertically polarized antenna 2 are electrically coupled. Further, for symmetry, the non-excitation element 6 is desirably arranged so as to be 90-degree rotationally symmetric with respect to the rotational symmetry axis O of the vertically polarized antenna 2.

  The non-excitation element 7 is arranged around each horizontal polarization antenna 4 and causes multiple resonance with the corresponding horizontal polarization antenna 4. The non-excitation element 7 is arranged in parallel (including the meaning of substantially parallel) to the horizontally polarized antenna 4. Further, the center position of the non-excitation element 7 in the line direction and the center position of the corresponding horizontally polarized antenna 4 in the line direction are matched. The non-excitation element 7 has a length on one side from the center position in the line direction that is a frequency used in the dual-polarized antenna and is about ¼ of the wavelength for a frequency different from the frequency handled by the horizontal polarization antenna 4. It is set to become. The distance between the non-excitation element 7 and the horizontal polarization antenna 4 is set so that the non-excitation element 7 and the horizontal polarization antenna 4 are electrically coupled. Further, for symmetry, the non-excitation element 7 is desirably arranged so as to be 90 degrees rotationally symmetric with respect to the rotational symmetry axis O of the vertically polarized antenna 2.

  In general, by appropriately designing the shape of the non-excitation element and the distance between the antenna and the non-excitation element, a double resonance characteristic can be obtained by electromagnetic coupling between the antenna and the non-excitation element. In the non-excitation elements 6 and 7 shown in FIGS. 8 and 9, the length is set shorter than the length of the vertical polarization antenna 2 and the horizontal polarization antenna 4. In this case, a two-resonance characteristic is obtained in which the non-excitation elements 6 and 7 resonate at a frequency f2 higher than the resonance frequency f1 of the vertical polarization antenna 2 and the horizontal polarization antenna 4.

  The number of the non-excitation elements 6 and 7 provided in the vertical polarization antenna 2 and the horizontal polarization antenna 4 is not limited to the above, and a plurality of non-excitation elements 6 and 7 having different lengths may be provided. At this time, if the number of the non-excitation elements 6 and 7 having different lengths is N, (N + 1) multiple resonance characteristics are obtained.

  8 and 9, the non-excitation element 7 is disposed above the horizontally polarized antenna 4. However, the present invention is not limited to this, and any position that electromagnetically couples to the horizontally polarized antenna 4 may be used. The horizontally polarized antenna 4 may be disposed below or on the same plane.

  In the above description, the case where the non-excitation element 6 is provided around the vertical polarization antenna 2 and the non-excitation element 7 is provided around the horizontal polarization antenna 4 has been described. However, the present invention is not limited to this, and the non-excitation element 6 may be provided only around the vertical polarization antenna 2, or the non-excitation element 7 may be provided only around the horizontal polarization antenna 4.

  As described above, according to the third embodiment, the non-excitation element 6 that generates the double resonance with the vertical polarization antenna 2 is provided, and the non-excitation element that generates the double resonance with the horizontal polarization antenna 4. 7 is provided, and in addition to the effects of the second embodiment, double resonance characteristics can be obtained, so that a polarization sharing antenna that operates in a plurality of frequency bands can be obtained.

Embodiment 4 FIG.
10 is a top view showing a configuration of a dual-polarized antenna according to Embodiment 4 of the present invention, and FIG. 11 is a cross-sectional view taken along the line DD ′ of FIG. The dual-polarized antenna according to the fourth embodiment shown in FIGS. 10 and 11 includes a vertically polarized antenna 2 and a horizontally polarized antenna 4 of the dual-polarized antenna according to the second embodiment shown in FIGS. The vertical polarization antenna 2b (2b-1 to 2b-4) and the horizontal polarization antenna 4b (4b-1 to 4b-4) are replaced. Other configurations are the same, and only the different parts are described with the same reference numerals.

The vertically polarized antenna 2b is a plate-shaped monopole antenna having a predetermined width, and is disposed vertically (including a substantially vertical meaning) on the conductor plate 1. The vertically polarized antenna 2b is patterned on the dielectric substrate 8 (8-1 to 8-4) by etching or the like. In addition, as shown in FIG. 11, the vertically polarized antenna 2b includes a plurality of conductors 21 (21-1 to 21-4) and 22 (22-1 to 22-4) branched and provided with grooves. have. The length of each of the branched conductors 21 and 22 is set to be about ¼ of the wavelength for different frequencies used in the dual-polarized antenna. Each vertically polarized antenna 2b is arranged so as to be 90 degrees rotationally symmetric with respect to an axis (rotation symmetry axis O) that passes through a certain point on the conductor plate 1 and is perpendicular to the conductor plate 1. . The contact end of the vertically polarized antenna 2b with the conductor plate 1 is connected to a first power feeding circuit (not shown) formed on the conductor plate 1, respectively.
In this first feeding circuit, each vertical polarization antenna 2b is 90 degrees out of phase with the adjacent vertical polarization antenna 2b and 180 degrees between the opposite vertical polarization antennas 2b. Supply offset power. In addition, the amplitude of the electric power supplied to each vertically polarized antenna 2b is the same.

FIG. 11 shows the case where the contact end of the vertically polarized antenna 2b with the conductor plate 1 is formed in a tapered shape. However, the present invention is not limited to this. For example, as shown in FIG. 12, the contact end may be rectangular.
Further, the width of the branching conductors 21 and 22 is not limited to the width shown in FIG. 11, and may be narrowed as shown in FIG. 12, for example.

The horizontally polarized antenna 4b is a dipole antenna, and is arranged in parallel (including the meaning of substantially parallel) to the conductor plate 1. In the horizontally polarized antenna 4b, the tip of the transmission line 34 of the corresponding feed line 3b is connected to the center position in the line direction. As shown in FIG. 10, the horizontal polarization antenna 4b has a plurality of conductors 41 (41-1 to 41-4) and 42 (42-1 to 42-4) branched and provided with grooves. doing. The horizontally polarized antenna 4b is configured to be line symmetrical. Each of the branched conductors 41 and 42 is set such that the length on one side from the center position in the line direction is about ¼ of the wavelength for different frequencies used in the polarization sharing antenna. Further, each horizontal polarization antenna 4 b is arranged so as to be 90 degrees rotationally symmetric with respect to the rotational symmetry axis O of the vertical polarization antenna 2.
The horizontally polarized antenna 4 b is formed on the upper surface of the dielectric substrate 5 from the center position in the line direction and is connected to the signal line 341 of the transmission line 34. Further, the other side from the center position in the line direction of the horizontally polarized antenna 4 b is formed on the lower surface of the dielectric substrate 5 and connected to the ground 342 of the transmission line 34.
Each horizontal polarization antenna 4b is supplied with electric power having the same amplitude and the same phase from the second feeding circuit via the feeding line 3b.

  In general, in a linear antenna such as a monopole antenna and a dipole antenna, multiple resonance characteristics can be obtained by branching a conductor. 10 and 11, the vertically polarized antenna 2b has conductors 21 and 22 branched into two, and the length of one conductor 21 is set to about ¼ of the wavelength with respect to the frequency f1, while the other The length of the conductor 22 is shorter than one of the conductors 21, and is set to a length of ¼ of the wavelength with respect to the frequency f2. In this case, a two-resonance characteristic having a relationship of f2> f1 is obtained. The same applies to the horizontally polarized antenna 4b shown in FIGS.

  In the above description, the vertical polarization antenna 2b and the horizontal polarization antenna 4b have two branches. However, the present invention is not limited to this, and the number of branches may be two or more. At this time, if the number of branches is M, M multiple resonance characteristics are obtained.

  In the above description, the vertical polarization antenna 2b is branched and the horizontal polarization antenna 4b is branched. However, the present invention is not limited to this, and only the vertically polarized antenna 2b may be branched, or only the horizontally polarized antenna 4b may be branched.

  As described above, according to the fourth embodiment, the vertically polarized antenna 2b is composed of the multiple branched conductors 21 and 22 that generate multiple resonances, and the horizontally polarized antenna 4b is divided into multiple branches that generate multiple resonances. Since the conductors 41 and 42 are used, in addition to the effects of the second embodiment, the excited antennas 2b and 4b themselves can have multiple resonance characteristics, so that a polarization sharing antenna corresponding to a plurality of frequencies is obtained. be able to.

  It is also possible to combine the configuration of the third embodiment and the configuration of the fourth embodiment. Thereby, the corresponding frequency can be further increased.

  In the present invention, within the scope of the invention, any combination of the embodiments, or any modification of any component in each embodiment, or omission of any component in each embodiment is possible. .

  DESCRIPTION OF SYMBOLS 1 Conductor plate, 2, 2b Vertically polarized antenna, 3, 3b Feeding line, 4, 4b Horizontally polarized antenna, 5, 8 Dielectric substrate, 6 Non-excitation element (first conductor), 7 Non-excitation element (first 2 conductor), 21, 22, 41, 42 conductor, 31, 33 transmission line (first transmission line), 32, 34 transmission line (second transmission line), 331 inner conductor, 332 outer conductor, 341 signal Line, 342 Ground.

Claims (7)

A conductor plate;
Four monopole antennas arranged to be 90-degree rotationally symmetric on the conductor plate;
A first transmission line disposed on the rotational symmetry axis of the monopole antenna, and a feed line having a second transmission line bent and connected to the first transmission line;
Four dipole antennas connected to the second transmission line of the feeder line and arranged so as to be 90 degrees rotationally symmetric with respect to the rotational symmetry axis and parallel to the conductor plate;
A power feeding circuit that supplies power with a phase shift of 90 degrees between the adjacent monopole antennas and a phase shift of 180 degrees between the monopole antennas facing each of the monopole antennas; Antenna device provided. The antenna device according to claim 1, wherein the feed line is provided for each of the dipole antennas. The first transmission line is one transmission line disposed on the axis of the rotational symmetry axis,
The antenna device according to claim 1, wherein the second transmission line is four transmission lines provided for each of the dipole antennas. The antenna device according to claim 3, further comprising: a first conductor that is provided for each dipole antenna and causes multiple resonance with the corresponding dipole antenna. 5. The antenna device according to claim 3, further comprising a second conductor that is provided for each monopole antenna and causes multiple resonance with the corresponding monopole antenna. The antenna device according to any one of claims 3 to 5, wherein the dipole antenna includes a plurality of branched conductors that generate multiple resonances. The antenna device according to any one of claims 3 to 6, wherein the monopole antenna includes a plurality of branched conductors that generate multiple resonances.

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