JP2008060764A - Horizontal polarization omnidirectional antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antenna excellent in omnidirectionality on a horizontal plane and having a firm structure against flexure or vibration. <P>SOLUTION: A horizontal plane omnidirectional antenna includes: coaxial lines having a prescribed length composed of at least central conductors and external conductors concentrically arranged with the axis of the central conductors; element support members which have ground lines to be connected to the external conductors at one end side of the coaxial lines and power feeding lines to be connected to the central conductors of the coaxial lines, and arrayed by connection in an axial direction along a plane substantially in parallel with the axial line of the coaxial lines; and folded dipoles 100 which are connected between the power feeding lines and the ground lines formed in the element support members, and which are formed in a circular or polygonal shape along a plane substantially vertical with respect to the axial line of the coaxial lines. The plurality of horizontal plane omnidirectional antennas are serially connected in a vertical direction, which includes: the coaxial lines; the element support members; and the folded dipoles 100. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a horizontally polarized omnidirectional antenna mainly used in a base station of a mobile communication system, and more particularly to the configuration of the horizontally polarized omnidirectional antenna.

A conventional horizontally polarized omnidirectional antenna includes an antenna substrate formed with a pair of feed lines parallel to the front and back of the end along the long side of a rectangular plate supported in the vertical direction, and the pair of feed lines. A horizontally polarized non-polarization antenna having a plurality of connected dipole antennas formed in a ring shape and a balanced / unbalanced conversion unit formed on the base of the antenna substrate for performing series feeding on the pair of feeding lines. Directional antennas have been proposed.
(For example, see Patent Document 1)

JP 2005-167705 A

However, according to the conventional horizontally polarized omnidirectional antenna, the transmission line between the antennas is realized by a pair of feed lines formed on a printed circuit board. To reduce the transmission loss of this feed line, There is a problem that it is necessary to use an expensive printed circuit board with a small transmission loss, which increases the cost. In addition, depending on the required performance, it is necessary to support multiple dipole antennas on the printed circuit board, so the printed circuit board becomes very long, and it is hard and has a sufficient thickness to maintain the strength of the printed circuit board. A certain substrate was required, and the cost of the material was unavoidable in this respect.
In addition, since the elements constituting the antenna are composed of dipole antennas, it is necessary to equip the base of the antenna with a balanced / unbalanced conversion unit that performs series feeding on the pair of feeding lines. There is also a problem that the printed circuit board becomes larger.
On the other hand, since the antenna configured in this manner is elongated in the vertical direction, the radome covering the elements constituting the antenna bends or vibrates due to the influence of wind or the like. As a result, the stress is applied to the printed circuit board constituting the antenna. However, as shown in the prior art invention, the length of the short side of the printed circuit board is formed to be equal to or smaller than the outer diameter of the ring-shaped dipole antenna, and the dimension in the long side direction is short. Considering an extremely long state as compared with the side, it can be considered that the radome is bent by a wind or resonates and vibrates, for example, so that the printed circuit board is largely bent or vibration is applied. Therefore, in order to stabilize the electrical characteristics of the antenna and to obtain reliability in terms of strength, vibration of the printed circuit board can be reduced by providing a holding means for holding the printed circuit board around the printed circuit board. Although it could be suppressed, it could not cope with the stress caused by bending of the entire radome. Therefore, in this application, it was made to solve these problems.
The purpose is to provide a high-performance horizontally polarized omnidirectional antenna with a simple configuration.
Another object is to provide a horizontally polarized omnidirectional antenna with a slim outer diameter.
Another object of the present invention is to provide a horizontally polarized omnidirectional antenna excellent in reliability with respect to bending and vibration caused by wind.
Another object is to provide a low-cost horizontally polarized omnidirectional antenna.
Another object is to provide a horizontally polarized omnidirectional antenna that can easily optimize the tilt angle.

In order to solve the above problems, the invention of claim 1 is a horizontal plane omnidirectional antenna,
A coaxial line of a predetermined length comprising at least a central conductor and an outer conductor disposed concentrically with the central axis of the central conductor;
A ground line connected to the outer conductor on one end side of the coaxial line and a feed line connected to the central conductor of the coaxial line are arranged and connected in an axial direction along a plane substantially parallel to the axis of the coaxial line An element support member;
A folded dipole connected between the feeder line formed on the element support member and the ground line, and formed in a circular or polygonal shape along a plane substantially perpendicular to the axis of the coaxial line. Configured.

According to a second aspect of the present invention, in the horizontal plane omnidirectional antenna according to the first aspect, a plurality of horizontal plane omnidirectional antennas comprising the coaxial line, the element support member, and the folded dipole are connected in series in the vertical direction. Configured.
.

According to a third aspect of the present invention, in the horizontal omnidirectional antenna according to any one of the first or second aspects, the folded dipole has an antenna length of 0.4 to 0.6 wavelength of the operating frequency. Configured to have.

According to a fourth aspect of the present invention, the outer dimension of the element support member in a direction substantially orthogonal to the axis of the coaxial line is slightly larger than the outer dimension of the folded dipole. The horizontal plane omnidirectional antenna as described in any one of Claims.

A fifth aspect of the present invention is the horizontal plane omnidirectional antenna according to any one of the first to fourth aspects, wherein the length of the coaxial line and the length of the feeder line formed on the element support member are as follows. Thus, the tilt angle of radiation with respect to a plane substantially perpendicular to the axial direction of the feeder line is optimized and set.

According to a sixth aspect of the present invention, in the horizontal plane omnidirectional antenna according to any one of the first to fifth aspects, the coaxial line is constituted by a coaxial cable.

According to the first aspect of the present invention, not only can an antenna with an excellent electrical characteristic be provided by having a simple structure and reducing the loss of the feed line, but also a main feature of feeding a folded dipole in series. Since the feed line is composed of a coaxial line, not only the outer diameter of the entire antenna can be made slim, but also the mechanical strength of the antenna can be made extremely strong.

According to the invention of claim 2, a plurality of horizontal plane omnidirectional antennas comprising a coaxial line, an element support member and a folded dipole may be connected in series in the vertical direction according to the required electrical characteristics. Even if the antenna configuration is small, it can be a highly versatile horizontal polarization omnidirectional antenna.

According to the third aspect of the present invention, when a radio wave having a high frequency is used, for example, for an antenna for a PHS base station, the folded dipole can be reduced in size, and as a result, the antenna can be made slim. Therefore, it is possible to provide an antenna having ease of installation on the roof of a building or the upper part of a utility pole.

According to the invention of claim 4, if the inner diameter of the radome is formed to be slightly larger than the width dimension of the element support member, both side sides of the element support member serve as guides when the assembled antenna is housed in the radome. Thus, the folded dipole can be prevented from coming into contact with the inner wall of the radome and deformed, and the spacer can be operated as a spacer that maintains an appropriate distance between the radome and the folded dipole against the bending and vibration of the radome. .

According to a fifth aspect of the present invention, in addition to the effect of the horizontal omnidirectional antenna according to any one of the first to fourth aspects, for example, the feed line formed on the element support member is configured to have a path length. By configuring it so that it consists of a plurality of different lines and selectively selecting the path of the feed line as necessary, the tilt angle of radiation with respect to a plane substantially perpendicular to the axial direction of the feed line can be arbitrarily set It is possible to provide a highly advantageous antenna that can be set to be optimized for the angle.

According to the invention of claim 6, since the coaxial line can be realized by a generally available coaxial cable, an antenna with high productivity efficiency can be provided. In addition, the main feeder line is composed of a coaxial cable, and the element support member composed of, for example, a printed circuit board is formed to be as small as possible. Even so, the flexibility of the coaxial cable constituting the antenna can absorb the stress, and an extremely reliable antenna with respect to mechanical strength can be provided.

Hereinafter, an example of an embodiment embodying the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic drawing of a horizontally polarized omnidirectional antenna according to the present invention, where (a) is a front view, (b) is a rear view, and (c) is a top view. FIG. 2 is an enlarged perspective view of a main part of the horizontally polarized omnidirectional antenna according to the present invention. FIG. 3 is a schematic diagram showing the overall configuration of a horizontally polarized omnidirectional antenna according to the present invention. In the following specific examples, when the direction is indicated, the axial direction of the coaxial line is the vertical direction. In the following embodiments, the antenna according to the present invention is an example corresponding to a PHS base station antenna, but is not limited to the PHS.

In the figure, reference numeral 1 denotes a horizontally polarized omnidirectional antenna according to the present invention, which is connected to a coaxial cable 5 as a coaxial line formed in a predetermined length and an external conductor 7 on one end side of the coaxial cable 5. An element support member 30 provided with a feed line 31 connected to the ground conductor 35 and the central conductor 9 of the coaxial cable 5 and arranged and connected in the axial direction along a plane substantially parallel to the axis of the coaxial cable 5; A folded dipole 100 connected between the feeder line 31 and the ground line 35 formed on the support member 30 and formed in a substantially circular shape along a plane substantially perpendicular to the axis of the coaxial cable 5 is formed. The horizontal polarization omnidirectional antenna 1 is configured by using an element portion as a basic configuration and arranging a plurality of the element portions in series as necessary.

The coaxial cable 5 used in the embodiment of the present invention is obtained by cutting a commercially available 8D-2V having a characteristic impedance of 50Ω into a predetermined length, and both ends thereof are subjected to predetermined processing. It has been given. In the embodiment of the present invention, the size of the coaxial cable 5 is 0.4 to 0.6 wavelengths of the operating frequency in consideration of the waveform shortening rate and the like.

At one end of the coaxial cable 5 formed in this way, element support members 30 are arrayed and connected in the axial direction along a plane substantially parallel to the axis of the coaxial cable 5. In the embodiment of the present invention, the element support member 30 is composed of a printed circuit board 2 made of a glass composite material (CEM-3, relative dielectric constant = 4, 2) having a thickness of 1.6 mm. This printed circuit board 2 is a double-sided board provided with a conductive material on both sides, and is connected to the front and back surfaces by through holes provided at necessary places.
Here, the element support member 30 will be described in more detail. As well shown in FIGS. 1 and 2, on the surface side of the printed circuit board 2, in addition to the feeder line 31 connected to the central conductor 9 of the coaxial cable 5 formed from the lower side to the upper side of the printed circuit board 2. A front side fixing land 32a, which is a land for fixing a folded dipole 100 described later to the printed circuit board, is formed. Further, in addition to the ground line 35 connected to the outer conductor 7 of the coaxial cable 5 formed on the back surface side of the printed circuit board 2 from the lower side to the upper side of the printed circuit board 2, the printed circuit board 2 is located at a position facing the front side fixing land 32a. A back side fastening land 32b is formed. In the embodiment of the present invention, the ground line 35 is a ground conductor of the printed circuit board 2 and is connected to the surface side ground conductor by a through hole. The front side fastening land 32a and the back side fastening land 32b are also electrically connected through a through hole.

The feed line 31 is connected to a connection land 31a for connecting the tip of the central conductor 9 of the coaxial cable 5, a support land 31b for fixing a feed point of a folded dipole 100, which will be described later, and the printed circuit board 2 further above. A transmission path having a predetermined line length connecting the connection land 31c connecting the tip of the center conductor 9 of the coaxial cable 5 to be connected, and this line length depends on the tilt angle of the antenna together with the line length of the coaxial cable. Have been optimized. As described above, the printed circuit board 2 is subjected to predetermined processing to form the element support member 30.
The above explanation is for the element support member 30 (shown by 30B in the figure) interposed between the coaxial cables 5, and the element support member 30 located at the uppermost stage (shown by 30A in the figure). ) Need only have a feed line in which the length of the feed line 31 is sufficient to attach the folded dipole 100, and is located above the folded dipole such as the connection land 31 as shown in the front view of FIG. There is no need for a track. In the following description, what is described as the element support member 30 is an explanation of the element support member 30B interposed between the coaxial cables 5 shown in the drawings unless otherwise specified.

Next, the folded dipole 100 will be described. The folded dipole 100 according to the embodiment of the present invention includes a first element member 10 formed in a substantially semicircular shape, and a second element formed in a substantially semicircular shape so as to face the first element member 10. The element member 20 is configured to form a substantially circular folded dipole 100 when the element support member 30 is attached to the front side and the back side. Each element member is formed by bending an elastic conductive material with a die or the like into a curved shape. In the embodiment of the present invention, the element member is made of a copper alloy for springs having a plate thickness of 0.5 mm.

The first element member 10 includes a substantially semicircular lower element 11, an upper element 13 having a substantially radius arranged substantially in parallel with the lower element 11, and one end of the lower element 11 and the upper element 13. The folding | returning part 17 which connects is integrally comprised. In addition, a support base portion 15 formed integrally by folding the distal end portion 12 of the lower element 11 inward is integrally provided at the other distal end portion 12 of the lower element 11. The support base 15 is formed with a fixing claw 15 a for positioning the first element member 10 protruding toward the element support member 30. Further, a connecting piece 16 is provided at the tip 14 of the other end of the upper element 13 so that the tip 14 of the upper element 13 is folded inward.
The second element member 20 has a similar configuration, and is a substantially semicircular lower element 21 so as to face the first element member 10, and a substantially semicircular shape arranged substantially parallel to the lower element 21. The upper element 23, and the folded portion 27 that connects one end of the lower element 21 and the upper element 23 are integrally formed. In addition, a support base portion 25 is integrally provided at the other end portion 22 of the lower element 21 so that the distal end portion 22 of the lower element 21 is folded inside. The support base 25 is formed with a fixing claw 25 a for positioning the second element member 20 protruding toward the element support member 30. The axis of the fixing claw 25a and the axis of the fixing claw 15a formed on the first element member 10 are mutually connected when the first element member 10 and the second element member are attached to the element support member 30. It is formed in a staggered position so as not to polymerize. Further, a connecting piece 26 is provided at the tip 24 of the other end of the upper element 23 so that the tip 24 of the upper element 23 is folded inward.

Here, a procedure for attaching the first and second element members to the element support member 30 will be described. First, the fixing claw 15a formed in the support base 15 of the first element member 10 is inserted into the positioning hole 2a formed in the element support member 30, and the support base 15 is brought into contact with the support land 31b. If the support land 31b and the support base 15 are fixed by a known method such as soldering, the first element member 10 is attached along a plane substantially perpendicular to the axial direction of the coaxial line. When this fixing is completed, the connection piece 16 formed by folding the tip 14 on the other end side of the upper element 13 is disposed to face the front side fastening land 32a. With the method, the attachment of the first element member 10 is completed by fixing the connecting piece 16 to the front side fixing land 32a.
Next, the second element member 20 is attached. Since the positioning hole 2b for positioning the second element member 20 is formed in the element support member 30, the fixing claw 25a formed in the second element member 20 is inserted into the positioning hole 2b. The support base 25 is brought into contact with a ground line 35 formed on the back surface of the element support member 30. Then, the support base 25 is fixed to the ground line 35 by a known method such as soldering. Further, since the connection piece 26 formed by folding the tip 24 on the other end side of the upper element 23 is disposed so as to face the back-side fastening land 32b, the connection piece 26 is connected by a known method such as soldering. The attachment of the second element member 20 is completed by adhering to the back side fastening land 32b.

The first and second element members attached in this way are the support base portion 15, the lower element 11, the folded portion 17, the upper element 13, the connection piece 16, and the element support member 30 of the first element member 10. A substantially circular element composed of a connection piece 26 of the second element member 20, an upper element 23, a folded portion 27, a lower element 21, and a support base 25 via fastening lands 32 a and 32 b formed on A folded dipole 100 is arranged between the feeder line 31 formed on the support member 30 and the ground line 35 so as to be arranged and connected along a plane substantially orthogonal to the axis of the coaxial cable.
In the embodiment of the present invention, the folded dipole 100 is configured to have a substantially circular shape. However, it is sufficient that desired characteristics can be obtained even if it is formed in a polygonal shape such as a square shape. It is not limited to examples.

When the folded dipole 100 is attached to the element support member 30, the coaxial cable 5 as the coaxial line and the element support member 30 are attached.
Notches 4 are formed below and above the printed circuit board 2. The size of the notch 4 is such that when the outer conductor 7 of the coaxial cable is applied to the notch 4 from the surface side of the printed circuit board 2, the central conductor 9 of the coaxial cable 5 is connected to the connection land 31a (or the connection land 31a). A width slightly smaller than the outer diameter of the outer conductor 7 is formed so as to be just in contact with the land 31c) (see the top view in FIG. 1C). The processing of the front end portion of the coaxial cable 5 brings the outer conductor 7 portion of the coaxial cable 5 into contact with the cutout portion 4, and the front end portions of the outer conductor 7 and the inner insulator 8 of the coaxial cable 5 are formed at the bottom portion of the cutout portion 4. What is necessary is just to process it to the dimension which the center conductor 9 just contacts the connection land 31a (or connection land 31c), and the external insulator 6 does not overlap with the printed circuit board 2 when it makes contact.
Then, if the coaxial cable 5 is applied to the notch 4, the well-known grounding conductor 36 having a sufficiently wide width provided on both sides of the notch 4 on the front side of the printed circuit board 2 is known. The element part, which is the basic structure of the antenna, is completed by firmly connecting with this technique.

FIG. 3 shows an overall configuration of the antenna 1 formed by connecting a plurality of element portions configured in this manner in series. By arranging the first and second element members 10 and 20 in a pair in the horizontal direction with respect to the element support member 30 disposed via the coaxial cable 5, a plurality of folded dipoles 100 are formed on the coaxial line. 5, and is fed in series by a feed line composed of the central conductor 9 and the feed line 31 and a feed line composed of the external conductor 7 and the ground line 35. A feed line having a connector 50 connected to the tip thereof is connected to the base side of the antenna.
In the embodiment of the present invention, the horizontal dimension of the element support member 30 is set to be slightly larger than the outer diameter of the folded dipole 100 formed in a substantially circular shape. Then, by forming the inner diameter of the radome (not shown) slightly larger than the horizontal dimension of the element support member 30, the sides on both sides of the element support member 30 are used when the assembled antenna is stored in the radome. To prevent the folded dipole 100 from coming into contact with the inner wall of the radome and deforming it, and to maintain an appropriate distance between the radome and the folded dipole 100 against the bending and vibration of the radome. It works as.

Here, the specific dimension which comprised this antenna as an antenna for PHS base stations whose center frequency is 1902.2 MHz (wavelength (lambda) = 157.7 mm) is shown.
The line length of the coaxial line 5 is 71 mm (0.45λ) using a coaxial cable 8D-2V (wavelength reduction rate = 66%).
The first and second element members 10 and 20 are folded so that the lower element, the upper element, and the folded portion are both 3 mm wide, and the distance between the lower blocking and the upper element is 3 mm. The folded dipole 100 is formed in a substantially circular shape having a diameter of approximately 25 mm (0.16λ) and a perimeter of 71.5 mm (0.45λ).
The distances between the folded dipoles 100 are attached to each other by 86 mm (0.54λ). Under these conditions, an antenna having a vertical plane tilt angle of −5 ° is configured.

The measured data of this antenna is shown in FIGS. 4 is a voltage standing wave ratio (hereinafter referred to as VSWR), FIG. 5 is a horizontal polarization vertical plane directivity, and FIG. 6 is a horizontal polarization horizontal plane directivity.
FIG. 4 shows measured values of VSWR over a 65 MHz range centered on this band so that the value of VSWR of 1884.5 to 1919.9 MHz, which is the frequency band of the PHS band, can be clearly understood. According to this result, VSWR = 1.27 at the lower limit frequency of 1884.5 MHz, VSWR = 1,11 at the center frequency of 1902,2 MHz, and VSWR = 1.12 at the upper limit frequency of 1919.9 MHz, which are the targets. A value having a sufficient margin with respect to VSWR = 1.5 is obtained.
According to the horizontal polarization vertical plane directivity data in FIG. 5, the tilt angle of the vertical plane of the antenna based on the above conditions is optimized to be just −5 ° in the downward direction of the antenna at a frequency of 1902.2 MHz. It is suitable for one of the antenna performances required as a PHS base station antenna.
According to the horizontal polarization horizontal plane directivity data in FIG. 6, the horizontal plane deviation of the antenna based on the above conditions is 1.3 dB with respect to the target within 1.5 dB at a frequency of 1902.2 MHz, which is a sufficient target. Is satisfied.

As described above, according to the horizontally polarized omnidirectional antenna of the present invention, an antenna having an excellent electrical characteristic can be provided because the structure is simple and the loss of the feed line can be reduced. In addition, since the main feed line that feeds the folded dipole 100 in series is a coaxial line, not only the outer diameter of the entire antenna can be made slim, but also the mechanical strength of the antenna can be made extremely strong. Further, if this antenna is used for a radio wave having a particularly high frequency, for example, an antenna for a PHS base station, the folded dipole 100 can be made small and the folded dipole 100 is formed in a substantially circular shape. As a result, the antenna can be slimmed down, and as a result, the antenna can be slimmed, and an antenna having ease of installation on the roof of a building or the upper part of a utility pole can be provided. In addition, since the folded dipole 100 is used, the feeder line can be drawn out without providing a balance-unbalance conversion, so that the antenna structure is simplified.

In addition, a highly productive antenna can be provided by using a commercially available coaxial cable as a coaxial line. Further, in this way, the main feeder line is constituted by a coaxial cable, and the element support member 30 that supports the folded dipole 100 is formed so as to be as small as possible. Therefore, the radome is bent entirely by wind or the like. Even if it vibrates or vibrates, the stress generated by them can be absorbed by the flexibility of the coaxial cable, and an extremely reliable antenna with respect to mechanical strength can be provided.

Then, if the inner diameter of the radome is formed slightly larger than the width dimension of the element support member 30, both sides of the element support member 30 serve as a guide when the assembled antenna is stored in the radome. The folded dipole 100 can be prevented from coming into contact with the inner wall of the radome and deformed, and can be operated as a spacer that keeps an appropriate distance between the radome and the folded dipole 100 against the bending and vibration of the radome.

In addition, for example, the feed line formed on the element support member 30 is configured to include a plurality of lines having different path lengths, and the path of the feed line is selectively selected as necessary. Thus, it is possible to provide an excellent antenna capable of optimizing and setting a radiation tilt angle with respect to a plane substantially orthogonal to the axial direction of the feed line.

The present invention is not limited to the above embodiment. For example, the folded dipole may be formed in a polygonal shape such as a quadrangle, and the arrangement interval and the number of arrangements may be adjusted to the required performance. May be changed as appropriate. In addition to the PHS base station antenna using the 1900 MHz band according to the embodiment, it may be configured to be provided for other frequency bands and uses, and so on, without departing from the spirit of the present invention. It is also possible to implement by appropriately changing the configuration.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic drawing of the horizontal polarization omnidirectional antenna concerning this invention, (a) is a front view, (b) is a rear view, (c) is a top view. It is the perspective view which expanded the principal part of the horizontal polarization omnidirectional antenna concerning this invention. It is the schematic which shows the whole structure of the horizontal polarization omnidirectional antenna concerning this invention. It is actual measurement data of the voltage standing wave ratio of the horizontal polarization omnidirectional antenna concerning the present invention. It is actual measurement data of the horizontal polarization vertical plane directivity of the horizontal polarization omnidirectional antenna concerning this invention. It is actual measurement data of the horizontal polarization horizontal plane directivity of the horizontal polarization omnidirectional antenna concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Horizontally polarized omnidirectional antenna, 2 ... Printed circuit board, 2a ... Positioning hole, 2b ... Positioning hole, 4 ... Notch part, 5 ... Coaxial cable, 6 ... External insulator, 7 ... External conductor, 8 ... Internal insulation Body: 9 ... Center conductor, 10 ... First element member, 11 ... Lower element, 12 ... Tip part, 13 ... Upper element, 14 ... Tip part, 15 ... Support base, 15a ... Fixing claw, 16 ... Connection piece , 17 ... folded portion, 20 ... second element member, 21 ... lower element, 22 ... tip part, 23 ... upper element, 24 ... tip part, 25 ... support base, 25a ... fixing claw, 26 ... connection piece, 27: Folded part, 30 ... Element support member, 31 ... Feed line, 32 ... Fastening land, 35 ... Ground line, 36 ... Ground conductor, 50 ... Connector, 100 ... Folded dipole.

Claims (6)

In horizontal plane omnidirectional antenna,
A coaxial line of a predetermined length comprising at least a central conductor and an outer conductor disposed concentrically with the central axis of the central conductor;
A ground line connected to the outer conductor on one end side of the coaxial line and a feed line of a predetermined length connected to the central conductor of the coaxial line, and an axial direction along a plane substantially parallel to the axis of the coaxial line Element support members arranged and connected to each other,
A folded dipole connected between the feeder line and the ground line formed on the element support member, and formed in a circular or polygonal shape along a plane substantially perpendicular to the axis of the coaxial line;
A horizontal plane omnidirectional antenna comprising:
The horizontal plane omnidirectional antenna according to claim 1, wherein a plurality of horizontal plane omnidirectional antennas including the coaxial line, the element support member, and the folded dipole are connected in series in a vertical direction.
The horizontal plane omnidirectional antenna according to any one of claims 1 and 2, wherein the folded dipole has an antenna length of 0.4 to 0.6 wavelengths of a used frequency.
4. The outer dimension of the element support member in a direction substantially orthogonal to the axis of the coaxial line is slightly larger than the outer dimension of the folded dipole. 5. Horizontal plane omnidirectional antenna.
The radiation tilt angle with respect to a plane substantially perpendicular to the axial direction of the feed line is optimized and set according to the length of the coaxial line and the length of the feed line formed on the element support member. The horizontal plane omnidirectional antenna as described in any one of Claims 1-4.
The horizontal plane omnidirectional antenna according to any one of claims 1 to 5, wherein the coaxial line includes a coaxial cable.

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