JP3691007B2 - Horizontally polarized omnidirectional antenna device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a horizontally polarized omnidirectional antenna device used in, for example, a mobile communication base station.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, mobile communication base stations such as mobile phones and PHS are required to have non-directional antenna characteristics in order to communicate with a mobile body. For this reason, for example, in a PHS mobile communication base station, a vertically polarized omnidirectional collinear antenna is currently widely used.
[0003]
[Problems to be solved by the invention]
As described above, conventionally, a vertically polarized omnidirectional collinear antenna is generally used as a mobile communication antenna, but recently a horizontally polarized omnidirectional antenna is also considered. However, a horizontally polarized omnidirectional antenna generally has a larger diameter than a vertically polarized omnidirectional antenna, which is disadvantageous in terms of weight and wind pressure load. For this reason, conventionally, a horizontally polarized omnidirectional antenna is not often used.
[0004]
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a horizontally polarized omnidirectional antenna device that has a simple structure, a small diameter, and can be miniaturized.
[0005]
[Means for Solving the Problems]
The horizontal polarization omnidirectional antenna device according to the present invention includes a first antenna in which a pair of substantially semicircular antenna elements having a length of approximately λ / 4 are disposed facing each other, and the first antenna. A pair of substantially semicircular antenna elements having a length of approximately λ / 4 and disposed at the top of the antenna, and having a length of approximately λ / 8 provided at the tip thereof. A pair of antenna elements each having a substantially semicircular shape having a length of approximately λ / 4 disposed at a distance of approximately λ / 4 at the first lower portion, and a tip thereof; Power is supplied to the center of the antenna element so that an antiphase current flows through the third antenna formed of an arm having a length of approximately λ / 8 and each antenna element constituting the first antenna. A current having the same phase as that of the feeding means and the first antenna A feed line connecting between the first antenna and the second antenna and between the first antenna and the third antenna so as to flow to the second antenna and the third antenna; Features.
[0006]
With the above-described configuration, the diameter can be reduced with a simple structure, and the directivity in the horizontal plane can be made non-directional with a deviation within 1 dB. Moreover, the directivity in the horizontal plane can be adjusted by finely adjusting the lengths and intervals of the arms provided in the antenna elements constituting the second antenna and the third antenna.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a basic configuration of a horizontally polarized omnidirectional antenna apparatus according to an embodiment of the present invention.
[0008]
In FIG. 1, reference numeral 1 denotes a first antenna, which is a pair of substantially semicircular antenna elements 1a, 1b having a length of approximately λ (wavelength) / 4, and is arranged facing each other. Power is fed from feeding points 2a and 2b provided in the central part of each. In this case, the feeding phase is set so that the current i flowing through the antenna elements 1a and 1b has an opposite phase.
[0009]
Then, the second antenna 3 is arranged on the upper portion of the first antenna 1 with an interval of approximately λ / 4. The second antenna 3 has a pair of substantially semicircular antenna elements 3a and 3b having a length of approximately λ / 4 arranged facing each other, and arms 4a and 4b of approximately λ / 8 are disposed at the tip thereof. It is provided in parallel toward the first antenna 1 side. In addition, the feed line 5 connects the ends of the first antenna 1 and the second antenna 3 so that a current i in phase with the first antenna 1 flows through the second antenna 3.
[0010]
A third antenna 6 is disposed below the first antenna 1 with an interval of approximately λ / 4. Similar to the second antenna 3, the third antenna 6 has a pair of substantially semicircular antenna elements 6a and 6b having a length of approximately λ / 4, facing each other. / 8 arms 7a and 7b are provided in parallel toward the first antenna 1 side. In addition, the feed line 8 connects the ends of the first antenna 1 and the third antenna 6 so that a current i in phase with the first antenna 1 flows through the third antenna 6.
[0011]
In the above configuration, the distance Δg between the arms 4 a and 4 b of the second antenna 3 and the length and distance Δg of the arms 7 a and 7 b of the third antenna 6 are finely adjusted, so that the horizontal plane of horizontally polarized waves can be obtained. Adjust the directivity to be omnidirectional. Since the currents flowing through the arms 4a and 4b and the arms 7a and 7b are in opposite phases, no radio waves are emitted.
[0012]
On the other hand, in the first antenna 1, currents in opposite phases flow through the antenna elements 1 a and 1 b, but radio waves are radiated because the flowing directions are the same. Further, since the current having the same phase as the first antenna 1 flows through the second antenna 3 and the third antenna 6, radio waves are efficiently radiated.
[0013]
Next, a specific configuration example of the horizontally polarized omnidirectional antenna device will be described with reference to FIGS. 2A is a perspective view of the front side of the horizontally polarized omnidirectional antenna device according to the embodiment of the present invention, and FIG. 2B is a perspective view of the back side. 3 is a perspective view showing a specific example of an antenna element alone, FIG. 4A is a front view showing a feeding circuit portion, FIG. 4B is a rear view thereof, and FIG. 5 is a side view showing the entire configuration. FIG. 6 is a cross-sectional view showing a state where the antenna is mounted on the radome.
[0014]
In FIG. 2, 11 is a dielectric substrate, for example, a copper foil substrate, for example, having a relative dielectric constant of 2.6 and a thickness of about 1.6 mm. Then, on the front side of the substrate 11, as shown in FIG. 2A, one of the antenna elements 1a, 3a, 6a of the first, second, and third antennas 1, 3, 6 is approximately λ / 4. Install at intervals of.
[0015]
Further, as shown in FIG. 2B, the other antenna elements 1b, 3b, and 6b of the first, second, and third antennas 1, 3, and 6 are placed on the back surface of the substrate 11 as described above. It is mounted at a position facing 1a, 3a, 6a. Each element of the antennas 1, 3, 6 uses a conductor such as copper or brass, and has a C-shaped configuration called a blues antenna (a meander line with one side of λ / 4). In this case, the antenna element is formed into a polygonal shape, for example, a trapezoidal shape for easy processing, and is formed into a plate shape for high efficiency. Furthermore, the arms 4 a and 4 b of the second antenna 3 and the arms 7 a and 7 b of the third antenna 6 are provided on the substrate 11. The arms 4a and 4b and the arms 7a and 7b are formed by a microstrip line having a length of λ / 8.
[0016]
FIG. 3 shows a specific configuration example of a single antenna element 1a, 3a. The antenna element 1a constituting the first antenna 1 is divided into two elements in order to feed power at the center.
[0017]
Further, as shown in FIG. 2A and FIG. 4A, a feed line constituted by a microstrip line 12 is provided on the front side of the substrate 11. The microstrip line 12 is provided from the base of the substrate 11 toward the third antenna 6, and is divided into two by the branching unit 13 in the middle.
[0018]
On the other hand, a taper balun 14 is provided at the base on the back side of the substrate 11 as shown in FIGS. 2 (b) and 4 (b), and the first antenna together with the microstrip lines 12 distributed by the branch part 13. It connects to the feeding point of 1 antenna element 1a, 1b. In this case, one end of the microstrip line 12 branched by the branching portion 13 and one end of the taper balun 14 are positioned on the opposite side of the substrate 11 through a through hole 15 provided in the substrate 11 to invert the phase. Thus, power is supplied to the antenna elements 1a and 1b.
[0019]
Further, between the antenna elements 1 a and 1 b of the first antenna 1 and the antenna elements 3 a and 3 b of the second antenna 3 and between the antenna elements 1 a and 1 b of the first antenna 1 and the antenna element of the third antenna 6. 6a and 6b are connected by feed lines (microstrip lines) 5 and 8, respectively.
[0020]
Then, as shown in FIGS. 4A, 4B and 5, an external connection connector 16 is attached to the base of the substrate 11 and connected to the microstrip line 12 and the taper balun 14.
Further, a radome 17 as shown in FIG. 6 is provided on the outside of the antenna for protection as required.
[0021]
As shown in the above-described embodiment, the antenna elements of the first, second, and third antennas 1, 3, and 6 are mounted on both sides of the substrate 11 on which the feed line is formed in the center. By forming in the shape, the radiation resistance and the band can be improved.
[0022]
In the horizontal polarization omnidirectional antenna device, the center frequency is 1907 MHz, the antenna elements of the first, second, and third antennas 1, 3, and 6 have a total length of 58 mm (0.369λ) and a total width of 24 mm (0.153λ). ), A return loss characteristic shown in FIG. 7, a horizontal plane directivity shown in FIG. 8, and a vertical plane directivity shown in FIG. 9 were obtained. In the antenna device, an FRP having an outer diameter of 29 mm and a thickness of 1 mm was used as the radome 17 and the entire length of the antenna device was 205 mm.
[0023]
In the return loss characteristic shown in FIG. 7, −14 dB (VSWR≈1.5) or less was obtained at 1.895 to 1.918 GHz. The operating gain at this time was about 2 dBi.
[0024]
In the horizontal plane directivity shown in FIG. 8, a non-directional characteristic was obtained with a deviation within 1 dB.
The vertical plane directivity shown in FIG. 9 has an 8-shaped characteristic having a high gain in the horizontal direction.
By constructing an antenna element having a simple shape on a single substrate 11 as described above, the antenna element and the feeding circuit can be integrated to reduce weight and size, and a horizontally polarized wave with a thin diameter and high gain. An omnidirectional antenna device could be realized.
[0025]
In the above-described embodiment, the case where the antenna is configured in a single stage has been described. However, the gain can be improved by configuring the antenna in multiple stages. For example, when a two-stage configuration is used, an operation gain of about 5 dBi can be obtained, and when a four-stage configuration is used, an operation gain of about 7 dBi can be obtained.
[0026]
FIG. 10 shows an example in which the horizontally polarized omnidirectional antenna apparatus has a four-stage configuration. The length of the substrate 11 is set in accordance with the multi-stage configuration, and the first to fourth stage antennas 21 to 24 are mounted at a predetermined interval. Since the first to fourth stage antennas 21 to 24 have the same configuration as the one-stage antenna described above, detailed description thereof is omitted.
[0027]
In addition, on the front side of the substrate 11, a feed line configured in advance with a microstrip line 12 is provided. The microstrip line 12 is provided from the base part of the substrate 11 toward the first stage antenna 21, and is divided into two by the branch part 13 in the middle. The two distributed feed lines are extended to the central portion of the substrate 11, that is, between the second-stage antenna 22 and the third-stage antenna 23, and a branching portion 25 is provided at the central portion to provide a vertical direction (second-stage). Branching in the direction of the second antenna 22 and the third stage antenna 23). Further, a through hole 26 is provided in the branch portion 25.
[0028]
On the other hand, a taper balun is provided at the base of the back surface side of the substrate 11 as in the case of the above-described one-stage configuration, and one end of this taper balun and one of the microstrip lines 12 are crossed by a through hole 26. Invert the phase.
[0029]
Then, the microstrip line 12 branched downward at the branching portion 25 extends to between the first stage antenna 21 and the second stage antenna 22, where it is branched vertically by the branching portion 27. Power is supplied to the first stage antenna 21 and the second stage antenna 22.
[0030]
Further, the microstrip line 12 branched upward in the branching section 25 extends between the third stage antenna 23 and the fourth stage antenna 24, and is branched in the vertical direction by the branching section 28. Power is supplied to the third stage antenna 23 and the fourth stage antenna 24.
[0031]
Similarly, power is supplied to the first to fourth stage antennas 21 to 24 on the back side of the substrate 11.
By the above power feeding means, power can be fed to the first to fourth stage antennas 21 to 24 under the same conditions.
[0032]
In the horizontal polarization omnidirectional antenna device having the four-stage configuration, the horizontal plane directivity shown in FIG. 11 and the vertical plane directivity shown in FIG. 12 were obtained.
[0033]
In the horizontal plane directivity shown in FIG. 11, the omnidirectional characteristic was obtained with a deviation within 1 dB, as in the case of the antenna device having a single stage configuration.
Further, in the vertical in-plane directivity shown in FIG. 12, sharper 8-shaped characteristics than the one-stage antenna device were obtained by improving the operation gain.
[0034]
In the above embodiment, the PHS antenna in the 1.9 GHz band has been described as an example. However, the present invention can also be implemented in a cellular phone base station, a higher-frequency wireless LAN device, or the like.
[0035]
【The invention's effect】
As described in detail above, according to the present invention, the gain is small, the diameter is small, the size can be reduced, and the directivity in the horizontal plane can be made omnidirectional with a deviation within 1 dB. The horizontally polarized omnidirectional antenna apparatus can be provided. Moreover, the directivity in the horizontal plane can be adjusted by finely adjusting the lengths and intervals of the arms provided in the antenna elements constituting the second antenna and the third antenna.
[Brief description of the drawings]
FIG. 1 is a basic configuration diagram of a horizontally polarized omnidirectional antenna device according to an embodiment of the present invention.
2A is a front perspective view showing a specific configuration example of a horizontally polarized omnidirectional antenna device according to the embodiment, and FIG. 2B is a rear perspective view of the same.
FIG. 3 is a perspective view showing a specific example of a single antenna element in the embodiment.
4A is a front view showing a power feeding circuit portion in the embodiment, and FIG. 4B is a rear view of the same.
FIG. 5 is a side view of the horizontally polarized omnidirectional antenna device according to the embodiment.
FIG. 6 is a cross-sectional view of a horizontally polarized omnidirectional antenna device according to the embodiment.
FIG. 7 is a view showing a return loss characteristic of the horizontally polarized omnidirectional antenna device according to the embodiment.
FIG. 8 is a view showing the horizontal directivity of the horizontally polarized omnidirectional antenna device according to the embodiment;
FIG. 9 is a view showing the vertical in-plane directivity of the horizontally polarized omnidirectional antenna device according to the embodiment;
FIG. 10 is a front view when the horizontally polarized omnidirectional antenna device according to the present invention has a four-stage configuration.
FIG. 11 is a diagram showing the directivity in the horizontal plane of a horizontally polarized omnidirectional antenna device having a four-stage configuration.
FIG. 12 is a view showing the vertical in-plane directivity of a horizontally polarized omnidirectional antenna apparatus having a four-stage configuration;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... 1st antenna 1a, 1b ... Antenna element 2a, 2b ... Feeding point 3 ... 2nd antenna 3a, 3b ... Antenna element 4a. 4b ... arm 5 ... feed line 6 ... third antenna 6a, 6b ... antenna elements 7a, 7b ... arm 8 ... feed line 11 ... substrate 12 ... microstrip line 13 ... branch part 14 ... taper balun 15 ... through hole 16 ... Connector 17 ... Radome 21 ... First stage antenna 22 ... Second stage antenna 23 ... Third stage antenna 24 ... Fourth stage antenna 25 ... Branch part 26 ... Through holes 27, 28 ... Branch part

Claims (7)

A first antenna in which a pair of substantially semicircular antenna elements are disposed facing each other;
A second antenna comprising a pair of substantially semicircular antenna elements disposed at a predetermined interval above the first antenna;
A third antenna comprising a pair of substantially semicircular antenna elements disposed at a predetermined interval in the first lower portion;
A power feeding means for feeding power to a central portion of the antenna element so that a current of opposite phase flows through each antenna element constituting the first antenna
Between the first antenna and the second antenna, and between the first antenna and the third antenna so that a current in phase with the first antenna flows through the second antenna and the third antenna. A horizontally polarized omnidirectional antenna device comprising: a feed line connecting the two. A first antenna in which a pair of substantially semicircular antenna elements are disposed facing each other;
A second antenna comprising a pair of substantially semicircular antenna elements arranged at a predetermined interval above the first antenna and an arm provided at the tip thereof, and a predetermined value at the first lower part. A third antenna composed of a pair of substantially semicircular antenna elements arranged at an interval of and an arm provided at the tip thereof;
A power feeding means for feeding power to a central portion of the antenna element so that a current of opposite phase flows through each antenna element constituting the first antenna
Between the first antenna and the second antenna, and between the first antenna and the third antenna so that a current in phase with the first antenna flows through the second antenna and the third antenna. A horizontally polarized omnidirectional antenna device comprising: a feed line connecting the two. A first antenna in which a pair of substantially semicircular antenna elements having a length of approximately λ / 4 are disposed facing each other;
A pair of substantially semicircular antenna elements having a length of approximately λ / 4 and disposed at the top of the first antenna with a spacing of approximately λ / 4, and a substantially λ / 8 provided at the tip thereof. A second antenna comprising an arm having a length of
A pair of substantially semicircular antenna elements having a length of approximately λ / 4 and disposed at a distance of approximately λ / 4 in the first lower portion, and a length of approximately λ / 8 provided at the tip thereof A third antenna comprising an arm having a thickness;
A power feeding means for feeding power to a central portion of the antenna element such that a current having an opposite phase flows to each antenna element constituting the first antenna;
Between the first antenna and the second antenna, and between the first antenna and the third antenna so that a current in phase with the first antenna flows through the second antenna and the third antenna. A horizontally polarized omnidirectional antenna device comprising: a feed line connecting the two. 4. The horizontally polarized omnidirectional antenna device according to claim 3, wherein each of the antenna elements constituting the first to third antennas is formed in a substantially trapezoidal shape. 4. The horizontally polarized omnidirectional antenna device according to claim 3, wherein one of the antenna elements constituting the first to third antennas is provided on one surface of a dielectric substrate, and the other of the antenna elements is connected to the dielectric. A horizontally polarized omnidirectional antenna device, characterized in that it is provided on the other surface of the body substrate. 6. A horizontal polarization omnidirectional antenna device comprising a radome provided outside the horizontal polarization omnidirectional antenna device according to claim 2, 3, 4 or 5. 6. A horizontally polarized omnidirectional antenna device according to claim 2, 3, 4 or 5, wherein the horizontally polarized omnidirectional antenna device is provided in multiple stages.

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