JP2003142934A - Horizontally polarized nondirectional antenna system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a horizontally polarized nondirectional antenna system of simple structure which has as a small diameter and can be made small-sized. SOLUTION: A 2nd antenna 3 and a 3rd antenna 5 are arranged above a 1st antenna 1 almost at an interval λ. The antennas 1, 3, and 5 each have a couple of semicircular antenna elements having length λ/6 arranged opposite to each other and feeding is carried out from a feed point 2 of antenna elements 1a and 1b constituting the 1st antenna 1. The 3rd antenna 5 is equipped with arms 6a and 6b of length λ/8 atop of antenna elements 5a and 5b. The 1st antenna 1 and 2nd and 3rd antennas 3 and 5 are connected together by feed lines 4 and 7 respectively and a current which is in phase with the 1st antenna 1 is made to flow to the 2nd antenna 3 and 3rd antenna 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless LAN, for example.
The present invention relates to a horizontally polarized omnidirectional antenna device used in a base station or the like.

[0002]

2. Description of the Related Art Conventionally, a wireless LAN base station is required to have an omnidirectional antenna characteristic in order to communicate with a terminal. For this reason, for example, vertically polarized omnidirectional collinear antennas are often used in outdoor base stations of wireless LANs.

[0003]

As described above, conventionally, a vertically polarized omnidirectional collinear antenna is generally used as a wireless LAN antenna, but recently, a horizontally polarized omnidirectional antenna has been used. Utilization is also considered. However, the horizontally polarized omnidirectional antenna generally has a larger diameter than the vertically polarized omnidirectional antenna, which is disadvantageous in terms of weight, wind pressure load, and the like. For this reason, conventionally, a horizontally polarized omnidirectional antenna is not often used.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a horizontal polarization omnidirectional antenna device having a simple structure, a small diameter, and a small size.

[0005]

A horizontally polarized omnidirectional antenna device according to the present invention comprises a first pair of mountain-shaped antenna elements facing each other having a length of approximately λ / 6.
And an antenna of about λ / 4 above the first antenna.
A second antenna composed of a pair of chevron-shaped antenna elements having a length of approximately λ / 6 and arranged at intervals of
A pair of chevron-shaped antenna elements having a length of approximately λ / 6 arranged at an interval of approximately λ / 4 above the second antenna and a length of approximately λ / 8 provided at the tip thereof. A third antenna including an arm having a height, power feeding means for feeding power to an end of the antenna element so that currents of opposite phases flow through the respective antenna elements forming the first antenna, and the first antenna A feed line connecting between the first antenna and the second antenna and between the second antenna and the third antenna so that a current having the same phase as the current flows through the second antenna and the third antenna. And is provided.

With the above-mentioned structure, it is possible to reduce the diameter and size with a simple structure, and to make the directivity in the horizontal plane omnidirectional with a deviation of 1 dB or less. In addition, the directivity within the horizontal plane can be adjusted by finely adjusting the length and interval of the arms provided on the antenna element that constitutes the third antenna.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a basic configuration of a horizontally polarized omnidirectional antenna device according to an embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a first antenna, which is a pair of antenna elements 1a and 1b each having a mountain shape and having a length of approximately λ (wavelength) / 6. Power is supplied from a power supply point 2 provided at the tip of 1b.

Then, the second antenna 3 is arranged above the first antenna 1 with a spacing of approximately λ / 4.
In this second antenna 3, a pair of mountain-shaped antenna elements 3a and 3b having a length of approximately λ / 6 are arranged to face each other. In addition, the first antenna 1 is so arranged that the current i having the same phase as that of the first antenna 1 flows through the second antenna 3.
And the ends of the second antenna 3 are connected by a power feeding line 4.

Further, the third antenna 5 is arranged above the second antenna 3 with a spacing of approximately λ / 4. This third antenna 5 is similar to the second antenna 3 in that it has a pair of mountain-shaped antenna elements 5 each having a length of approximately λ / 6.
a and 5b are arranged facing each other, and approximately λ /
8 arms 6a and 6b are provided in parallel toward the second antenna 3 side. Further, the second antenna 3 and the end portions of the third antenna 5 are connected by the power supply line 7 so that the current i having the same phase as that of the second antenna 3 flows to the third antenna 5.

In the above structure, by finely adjusting the lengths of the arms 6a and 6b of the third antenna 5 and the spacing Δg, the directivity in the horizontal plane of horizontal polarization is adjusted to be non-directional. . Since the currents flowing through the arms 6a and 6b have opposite phases, no radio wave is emitted.

On the other hand, in the first antenna 1, currents of opposite phases flow through the antenna elements 1a and 1b, but since the flowing directions are the same, radio waves are emitted. In addition, the second antenna 3 and the third antenna 5 have a current flowing in the same phase as the first antenna 1, so that radio waves are efficiently radiated.

Next, a specific configuration example of the horizontal polarization omnidirectional antenna device will be described with reference to FIGS. 2 to 6. FIG. 2A is a front perspective view of the horizontal polarization omnidirectional antenna device according to the embodiment of the present invention, and FIG. 2B is a rear perspective view thereof. 3 is a perspective view showing a specific example of the antenna element alone, FIG. 4 (a) is a front view showing a feeding circuit portion, FIG. 4 (b) is a rear view thereof, and FIG. 4 (c).
Is a front view of a split balun portion provided on the feeding end side, FIG. 5 is a side view showing the overall configuration, and FIG. 6 is a sectional view showing a state in which an antenna is mounted on a radome.

In FIG. 2, reference numeral 11 is a dielectric substrate, for example, a copper foil substrate having a relative permittivity of 2.2 and a thickness of about 0.8 mm. Then, as shown in FIG. 2A, one of the first, second, and third antennas 1a, 3a, and 5a of the first, second, and third antennas 1a, 3a, and 5a is approximately λ / 4 on the front side of the substrate 11. Install at intervals.

Also, on the back surface of the substrate 11, as shown in FIG. 2B, the other antenna elements 1b, 3b, 5b of the first, second, and third antennas 1, 3, 5 are provided on the front side. The antenna elements 1a, 3a, and 5a are mounted at positions facing each other.
Each element of the antennas 1, 3, and 5 is formed by using a conductor such as copper or brass, and forming a shape called a Bruce antenna (mean side of λ / 4 on one side) into a mountain shape. That is, each antenna element is formed into a mountain shape by bending a rectangular conductor plate at the center, for example, as shown in FIG. 3, to facilitate processing. Further, the arms 6 a and 6 b of the third antenna 5 are provided on the substrate 11. The arms 6a and 6b are formed by microstrip lines having a length of λ / 8.

As shown in FIGS. 2A and 4A, the microstrip line 1 is provided on the front side of the substrate 11.
The feed line constituted by 2a is provided, and the split balun 13 is provided at the base. This split balun 1
3 has a ground portion 15 and a line 16 made of copper foil formed on the upper surface of the dielectric substrate 14 as shown in FIG.
In this case, the ground portion 15 is formed on the lower half of the substrate 14, and the line 16 is formed upward from the upper center of the ground portion 15. Further, the upper end of the line 16 is extended to the upper end surface of the substrate 14 to form a short line 16a, and the short line 16a is connected to the microstrip line 12a. The microstrip line 12a is provided from the base of the substrate 11 toward the first antenna 1, and is connected to the short line 16a of the split balun 13 on the way. Further, the substrate 14 is provided with a notch 17 in the lower center thereof so that the lower end of the microstrip line 12a is exposed so that it can be connected to an external circuit (a connector 19 described later).

On the other hand, the base portion on the back surface side of the substrate 11 is shown in FIG.
(B), as shown in FIG. 4 (b), the ground portion 18 is provided,
From this ground portion 18 to the microstrip line 12b
To the feeding points of the antenna elements 1a and 1b of the first antenna.

Further, the antenna element 1 of the first antenna 1
a, 1b and the antenna elements 3a, 3b of the second antenna 3
, And the antenna elements 3a, 3 of the second antenna 3
b and the antenna elements 5a and 5b of the third antenna 5 are each a feed line (microstrip line).
It is connected by 4 and 7.

Then, as shown in FIGS. 4A, 4B and 5, a connector 19 for external connection is provided on the base of the substrate 11.
Mounted, and the microstrip line 12a formed on the upper surface of the substrate 11 and the ground portion 1 formed on the back surface of the substrate 11.
8 and the ground portion 15 of the split balun 13.

Further, a radome 20 as shown in FIG. 6 is provided on the outer side of the antenna to protect it, if necessary.

As shown in the above-mentioned embodiment, the first, second, and third sides of the substrate 11 having the feed line formed are sandwiched in the center.
Attach the antenna elements 1, 3 and 5 of
By forming the antenna element in a plate shape, the radiation resistance and the band can be improved.

In the above-mentioned horizontally polarized omnidirectional antenna device, the center frequency is 5250 MHz, and the antenna elements of the first, second, and third antennas 1, 3, and 5 have a total length of 25.5 m.
When m (0.446λ) and full width 6 mm (0.105λ) are set, the return loss (Return) shown in FIG. 7 is set.
Loss characteristics, the horizontal in-plane directivity shown in FIG. 8, and the vertical in-plane directivity shown in FIG. 9 were obtained. In the above antenna device, the radome 20 has an outer diameter of 12 mm and a thickness of 0.5 m.
Using FRP of m, the total length of the whole antenna device is 130
mm.

The return loss characteristic shown in FIG. 7 is 5.1.
At -90 to 5.305 GHz, -9.5 dB (VS
It can be set to WR≈2.0) or less. The operating gain at this time was about 2 dBi.

In the horizontal plane directivity shown in FIG. 8, a non-directional characteristic was obtained with a deviation of 1 dB or less. The vertical plane directivity shown in FIG. 9 has an 8-shaped characteristic having a high gain in the horizontal direction. By constructing the antenna element having a simple shape on one substrate 11 as described above, the antenna element and the feeding circuit can be integrated to reduce the weight and size, and the horizontal polarization with a small diameter and high gain can be achieved. An omnidirectional antenna device could be realized.

In the above embodiment, the case where the antenna has a one-stage configuration has been described, but the gain can be improved by further providing a multi-stage configuration. For example, when the antenna has a two-stage configuration, an operating gain of about 5 dBi,
In the case of the 4-stage configuration, an operating gain of about 7 dBi could be obtained.

FIG. 10 shows an example of a horizontally polarized omnidirectional antenna device having a four-stage configuration. Board 1
1 sets the length according to the multi-stage configuration, and the first stage to the fourth stage
The antennas 21 to 24 of the step are attached with a predetermined space. The first to fourth stage antennas 21 to 24 have the same configuration as the above-described one-stage configuration antenna, and thus detailed description thereof will be omitted.

On the front surface side of the substrate 11, a power supply line formed by a microstrip line 12a is provided in advance.
The microstrip line 12a is provided from the base of the substrate 11 toward the first-stage antenna 21, and is connected to the short line 16a at the tip of the split balun midway. That is, the split balun 13 is provided on the base portion on the front side of the substrate 11 as in the case of the one-stage configuration, and the short line 16a at the tip of the split balun and the microstrip line 12a are connected.

The above microstrip line 1
2a is extended to the antenna 22 of the second stage, and a branching portion 25 is provided in this extended portion to provide a vertical direction (antenna 21 of the first stage).
And toward the third stage antenna 23).

The microstrip line 12a branched downward at the branching portion 25 extends to the first-stage antenna 21, where it is branched vertically at the branching portion 26 to form the first-stage antenna 21 and the second-stage antenna 21. Power is supplied to the stage antenna 22.

The microstrip line 12a branched upward by the branching section 25 extends to the antenna 23 of the third stage, where it is branched vertically by the branching section 27 to form the antenna 23 of the third stage. The fourth stage antenna 24 is fed.

Also on the back side of the substrate 11, power is similarly supplied to the first to fourth stage antennas 21 to 24. The above-mentioned power feeding means can feed power to the first to fourth stage antennas 21 to 24 under the same conditions.

The horizontal polarization omnidirectional antenna device having the above-mentioned four-stage structure has the return loss characteristics shown in FIG. 11, the horizontal in-plane directivity shown in FIG. 12, and the vertical in-plane directivity shown in FIG.

In the return loss characteristic shown in FIG.
At -250 to 5.350 GHz, -9.5 dB (V
It was possible to set SWR≈2.0) or less. The operating gain at this time was about 7 dBi.

With the directivity in the horizontal plane shown in FIG. 12, omnidirectional characteristics were obtained with a deviation of 1 dB or less, as in the case of the one-stage antenna device. Further, in the vertical in-plane directivity shown in FIG. 13, a sharper figure-eight characteristic than the one-stage antenna device was obtained due to the improvement of the operation gain. By configuring the antenna in multiple stages as described above, the operating gain can be improved according to the number of stages.

In the above embodiment, the case where the antenna element is formed in a mountain shape has been described. However, in the other embodiment, the antenna element may be formed in a semicircular shape or a polygon approximate to a semicircular shape, for example, a trapezoidal shape. The same characteristics as can be obtained.

[0036]

As described above in detail, according to the present invention, the structure is simple, the diameter is small, the size can be reduced, and the directivity in the horizontal plane is omnidirectional with a deviation of 1 dB or less. It is possible to provide a high-gain horizontally polarized omnidirectional antenna device. In addition, the directivity within the horizontal plane can be adjusted by finely adjusting the length and interval of the arms provided on the antenna element that constitutes the third antenna.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of a horizontal polarization omnidirectional antenna device according to an embodiment of the present invention.

FIG. 2A is a front perspective view showing a specific configuration example of the horizontal polarization omnidirectional antenna device in the same embodiment;
(B) is a perspective view of the same back side.

FIG. 3 is a perspective view showing a specific example of a single antenna element in the same embodiment.

4A is a front view showing a power feeding circuit portion in the same embodiment, FIG. 4B is a rear view of the same, and FIG. 4C is a front view of a split balun.

FIG. 5 is a side view of the horizontally polarized omnidirectional antenna device according to the same embodiment.

FIG. 6 is a cross-sectional view of the horizontally polarized omnidirectional antenna device according to the same embodiment.

FIG. 7 is a diagram showing a return loss characteristic of the horizontally polarized omnidirectional antenna device according to the same embodiment.

FIG. 8 is a view showing the directivity in the horizontal plane of the horizontally polarized omnidirectional antenna device in the same embodiment.

FIG. 9 is a diagram showing vertical in-plane directivity of the horizontally polarized omnidirectional antenna device in the same embodiment.

FIG. 10 is a front view of a horizontally polarized omnidirectional antenna device according to the present invention having a four-stage configuration.

FIG. 11 is a diagram showing a return loss characteristic of the horizontally polarized omnidirectional antenna device according to the same embodiment.

FIG. 12 is a diagram showing directivity in a horizontal plane of a horizontally polarized omnidirectional antenna device having a four-stage configuration.

FIG. 13 is a diagram showing vertical in-plane directivity of a horizontally polarized omnidirectional antenna device having a four-stage configuration.

[Explanation of symbols]

1 ... First antenna 1a, 1b ... Antenna element 2 ... feeding point 3 ... second antenna 3a, 3b ... Antenna element 4 ... feeder line 5 ... third antenna 5a, 5b ... Antenna element 6a, 6b ... Arm 7 ... feeder line 11 ... Substrate 12a, 12b ... Microstrip line 13 ... Split balun 14 ... Split balun substrate 15 ... Ground part 16 ... Railroad 16a ... short line 17 ... Notch 18 ... Earth part 19 ... Connector 20 ... radome 21 ... First-stage antenna 22 ... Second stage antenna 23 ... Third stage antenna 24 ... Fourth stage antenna 25, 26, 27 ... Bifurcation

Claims (7)

[Claims] 1. A first antenna in which a pair of chevron-shaped antenna elements are arranged to face each other, and a pair of chevron-shaped antenna elements which are arranged at a predetermined interval above the first antenna. And a third antenna including a pair of mountain-shaped antenna elements arranged at a predetermined interval above the second antenna, and each of the first antennas. Power feeding means for feeding power to the end portion of the antenna element so that current of opposite phase flows through the antenna element, and first so that current of the same phase as the first antenna flows through the second antenna and the third antenna. Antenna and second
And a feed line that connects the second antenna and the third antenna to each other, and a horizontally polarized omnidirectional antenna device. 2. A first antenna in which a pair of mountain-shaped antenna elements are arranged to face each other, and a pair of mountain-shaped antenna elements which are arranged above the first antenna with a predetermined interval. A second antenna comprising: a pair of mountain-shaped antenna elements arranged at a predetermined interval above the second antenna; and a third antenna comprising an arm provided at the tip of the pair of antenna elements, Power feeding means for feeding power to the ends of the antenna elements so that currents of opposite phases flow through the respective antenna elements forming the first antenna; and currents of the same phase as the first antenna are supplied to the second antenna and the third antenna. The first antenna and the second antenna
A horizontal polarization omnidirectional antenna device comprising: a feed line that connects the antenna and the second antenna and a third antenna. 3. A first antenna in which a pair of mountain-shaped antenna elements each having a length of approximately λ / 6 are arranged to face each other, and an interval of approximately λ / 4 is maintained above the first antenna. A second antenna composed of a pair of mountain-shaped antenna elements each having a length of approximately λ / 6, and a second antenna that is disposed above the second antenna with a spacing of approximately λ / 4. A third antenna including a pair of mountain-shaped antenna elements having a length of λ / 6 and an arm having a length of approximately λ / 8 provided at the tip thereof, and each of the first antennas. Power feeding means for feeding power to the end portion of the antenna element so that current of opposite phase flows through the antenna element, and first so that current of the same phase as the first antenna flows through the second antenna and the third antenna. Antenna and second
A horizontal polarization omnidirectional antenna device comprising: a feed line that connects the antenna and the second antenna and a third antenna. 4. The horizontal polarization omnidirectional antenna device according to claim 3, wherein each antenna element forming the first, second and third antennas is formed in a substantially semicircular shape or a substantially trapezoidal shape. Horizontal polarization omnidirectional antenna device. 5. The horizontal polarization omnidirectional antenna device according to claim 3, wherein one of the antenna elements forming the first, second and third antennas is provided on one surface of the dielectric substrate,
A horizontally polarized omnidirectional antenna device, wherein the other of the antenna elements is provided on the other surface of the dielectric substrate. 6. A horizontal polarization omnidirectional antenna device, wherein a radome is provided outside the horizontal polarization omnidirectional antenna device according to claim 2. 7. A horizontal polarization omnidirectional antenna device comprising a plurality of horizontal polarization omnidirectional antenna devices according to claim 2, 3, 4, or 5.