JP2002299950A - Cylindrical slot antenna and polarization diversity antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily manufacture a cylindrical slot antenna even though the diameter of a feeding slot is made to be short. SOLUTION: A feeding slot 11 is formed on the circumferential side surface of a conductive cylindrical part 10 so as to extend almost along the center axis of the conductive cylindrical part 10, and a parasitic slot 12 is formed so as to face the feeding slot 11. Polarization crossing almost orthogonally with the extension direction of the feeding slot 11 can be radiated by feeding the feeding slot 11 by a coaxial cable 2. In such a case, the slot length L1 of the feeding slot 11 can be shortened by the action of the parasitic slot 12, and the slot width W1 of the feeding slot 11 can also be made large.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylindrical slot antenna having a diameter sufficiently smaller than a wavelength of a used frequency, and a polarization diversity antenna using the cylindrical slot antenna.

[0002]

2. Description of the Related Art In mobile communication, fading may occur when a moving body moves. In particular,
When traveling in an urban area, fading frequently occurs due to reflected waves having different paths due to buildings or the like in a forest. Since the quality of communication deteriorates when fading occurs, a diversity system is employed as one of the measures against fading. As the diversity system, a space diversity system and a polarization diversity system are known. The space diversity system is a system in which a plurality of antennas are spatially separated from each other, and a reception signal from an antenna having the highest reception power is selected and received. In addition, the polarization diversity system is a system in which an antenna receiving horizontal polarization and an antenna receiving vertical polarization are provided, and a reception signal from an antenna having higher reception power is selected and received. It is.

[0003]

Here, an antenna for a base station in mobile communication is provided at the top of a telephone pole or on the roof of a building, and it is difficult to secure a sufficient space for installing the antenna. ing. However, in the space diversity system, a required diversity effect cannot be obtained unless the antennas are arranged sufficiently apart. For this reason, in the spatial diversity system, there is a problem that the diversity antenna becomes large and it becomes difficult to use it as an antenna for a base station. In addition, in the polarization diversity system, a horizontal polarization antenna and a vertical polarization antenna are required. As a horizontally polarized antenna, a turn-style antenna, a square loop antenna, a super-turn style antenna, and the like are known, and all antennas have a size of λ / 2 or more when one side is λ. And the height of the antenna becomes high. For this reason, there is a problem that the diversity antenna becomes large even in the polarization diversity system, and it becomes difficult to use it as an antenna for a base station.

[0004] As a horizontally polarized antenna which is extended in the vertical direction and can be miniaturized, a cylindrical slot antenna having a slot formed along a central axis on a cylindrical body is known (ECJORDAN, WEMILLER "SLOTTED-CY
LIDER ANTENNA '' ELECTONICSFebruary, 1947 PP.90-93
reference). This cylindrical slot antenna is an antenna for horizontal polarization consisting only of a cylindrical body having a slot extending in the vertical direction. However, as the diameter of the cylindrical body is reduced, the FIG. As shown in 5,
As the slot width becomes narrower, the slot length tends to become longer. As the diameter becomes smaller, a higher dimensional accuracy of the slot is required. For example, if the diameter of the cylindrical body is about 0.10λ (λ is the wavelength of the used frequency),
The slot width is about 0.0062λ and the slot length is about 1.0λ. Here, assuming that the used frequency is 1900 MHz used in the PHS, the slot width is 0.0
062λ = 0.97 mm and the slot length 1.0λ = 157 mm. By the way, a collinear array antenna is generally used as an antenna for a base station. However, when a collinear array antenna is used, it is considered that the element spacing is preferably 1.0λ or less due to problems such as maximum gain and sublobes. ing.
However, since the slot length is about 1.0λ, it has been difficult to realize a desirable form of collinear array with this cylindrical slot antenna. Here, in order to shorten the slot length, the width of the slot must be further reduced, and a problem arises in that machining with higher precision is required.

Further, in order to solve the application to a collinear array and high-precision machining, it has been proposed to form a radiation slot on a dielectric substrate and mount the dielectric substrate in a cylindrical body ( 1997 IEICE Communications Society Conference, Atsuya Ando, 3 authors, "B-1-41 A Study on Horizontally Polarized Omnidirectional Diversity Antenna" P.4
1). However, there is a problem in that a dielectric substrate that can be mounted in a cylindrical body must be created, and the created dielectric substrate must be mounted in the cylindrical body, resulting in a complicated structure and an increase in the number of components. Was.

SUMMARY OF THE INVENTION Accordingly, the present invention provides a cylindrical slot antenna having a simple configuration capable of solving the application to the collinear array and high-precision machining even if the diameter is sufficiently smaller than the wavelength of the operating frequency. It is an object.

[0007]

In order to achieve the above object, a cylindrical slot antenna according to the present invention comprises a conductive cylindrical body and the cylindrical body extending substantially along a central axis of the cylindrical body. A feeding slot formed in an elongated shape on the peripheral side surface, and extending substantially along the central axis of the cylindrical body,
And a non-feeding slot formed on the peripheral side surface of the cylindrical body so as to face the feeding slot. In the cylindrical slot antenna of the present invention, the feed slot and the non-feed slot may be formed in multiple stages on a peripheral side surface of the cylindrical body.

Further, a polarization diversity antenna according to the present invention, which can achieve the above-mentioned object, has a conductive cylinder that is erected substantially vertically, and extends substantially along the central axis of the cylinder. A power supply slot elongated on the peripheral side surface of the cylindrical body, and a power supply slot extending substantially along the central axis of the cylindrical body and elongated on the peripheral side surface of the cylindrical body so as to face the power supply slot. A horizontal polarization antenna having a feeding slot and a vertical polarization antenna having a vertical polarization element arranged substantially coaxially with the cylindrical body and extending substantially vertically are provided.

According to the present invention, since the non-feeding slot is provided so as to face the feeding slot formed on the peripheral side surface of the cylindrical body, the slot width can be reduced even if the diameter of the cylindrical body is reduced. It can be wide and short. Thus, even if the diameter of the cylindrical slot antenna is reduced, high mechanical accuracy is not required. Further, since the feeding slot and the non-feeding slot are merely formed in the cylindrical body, the configuration can be simplified.
Also, the length of the parasitic element may be longer than the length of the feeding element depending on the specification, but the length can be shorter than one wavelength of the operating frequency. Can also be adapted to collinear arrays. Furthermore, since the diameter of the cylindrical body in the cylindrical slot antenna can be reduced, a compact and small horizontal polarization antenna can be obtained by vertically disposing the cylindrical slot antenna. In this case, even if the diameter of the cylindrical body is as small as, for example, 0.08 wavelength at the operating frequency, the cylindrical slot antenna can be applied to the collinear array and has a simple configuration that does not require high-precision machining. become.

Further, by arranging the cylindrical slot antenna vertically, it is possible to obtain a horizontally polarized antenna composed of a cylindrical body having a small diameter, and a coaxially vertically polarized antenna above or below the cylindrical slot antenna. Can be arranged. When the polarization diversity antenna is configured in this manner, a compact and small polarization diversity antenna can be obtained. Therefore, when the antenna is used as a polarization diversity antenna for a base station, a small installation area is required when the antenna is installed on a telephone pole or a building rooftop.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 2 show examples of the configuration of a cylindrical slot antenna according to an embodiment of the present invention. 1 is a perspective view of the cylindrical slot antenna of the present invention, and FIG. 2 is a developed view showing the cylindrical slot antenna of the present invention. In the cylindrical slot antenna 1 according to the present invention shown in FIG. 1, an elongated feeding slot 11 is formed on a peripheral side surface of a conductive cylindrical portion 10 made of a metal pipe having a diameter φ along a central axis of the conductive cylindrical portion 10. I have. Substantially right behind the power supply slot 11, an elongated non-power supply slot 12 is formed to face the power supply slot 11. The feeding slot 11 and the non-feeding slot 12 are elongated so as to extend along the center axis direction of the conductive cylindrical portion 10. Further, the conductive cylindrical portion 10 can be constituted by a copper pipe, a brass pipe, a stainless steel pipe, or the like.

The power supply slot 11 has a length L3 from one end.
Are supplied from the coaxial cable 2 to the power supply point 11a.
In this case, the outer conductor of the coaxial cable 2 is connected to one edge of the power supply slot 11 at the position of the length L3 from one end,
The core wire 2a of the coaxial cable 2 has a length L3 from the opposite end.
Is connected to the other edge at the position. In this way, the point where the core wire 2a is connected is the feed point 11a, and the portion where the jacket conductor is connected is the outer conductor connection portion 11b. In this case, by setting the feeding point 11a near the center of the feeding slot 11, the feeding point impedance increases, and by setting the feeding point 11a near the end of the feeding slot 11, the feeding point impedance can be reduced. That is, by changing the length L3 at which the feeding point 11a is provided, the feeding point impedance can be adjusted to match the characteristic impedance of the coaxial cable 2. In this way, by feeding power to the feeding point 11a by the coaxial cable 2, the electromagnetic wave of the polarization orthogonal to the extending direction of the feeding slot 11 is transmitted to the cylindrical slot antenna 1.
It will be radiated from. Here, by arranging the cylindrical slot antenna 1 vertically upright, horizontal polarized waves are radiated from the cylindrical slot antenna 1.

In the thus configured cylindrical slot antenna 1 according to the present invention, the cylindrical slot antenna 1
When the wavelength of the used frequency is represented by λ, the conductive cylindrical portion 1
In the case where the diameter φ of 0 is, for example, about 0.1λ, according to experiments, the slot length L1 of the feeding slot 11 is set to about 0.342.
λ, the slot width W1 of the feeding slot 11 is set to about 0.022.
If 2λ is set, the slot length L2 of the parasitic slot 12 is about 0.823λ, and the slot width W2 of the parasitic slot 12 is about 0.0063λ, good antenna characteristics can be obtained as described later. Specifically, assuming that the operating frequency of the cylindrical slot antenna 1 is, for example, 1900 MHz used in PHS, the diameter φ of the conductive cylindrical portion 10 is
Is about 16.0 mm (about 0.1λ), the slot length L1 of the feeding slot 11 is about 54.0 mm (about 0.342λ),
The slot width W1 of the feeding slot 11 is about 3.5 mm (about 0.0222λ), and the slot length L of the feeding slot 12 is
2 is about 130.0 mm (about 0.823λ), and the slot width W2 of the parasitic slot 12 is about 1.0 mm (about 0.0023λ).
63λ), which indicates that a small-sized cylindrical slot antenna 1 having a simple configuration can be realized. In this case, the slot width of the feed slot 11 can be widened and shortened even though the diameter of the cylindrical slot antenna 1 is reduced to about 0.1λ. This eliminates the need for high mechanical accuracy. Further, since the length of the non-feeding slot 12 longer than the feeding slot 11 is also set to 1λ or less, it can be applied to a collinear array.

In such a cylindrical slot antenna 1 according to the present invention, the cylindrical slot antenna 1 when the conductive cylindrical portion 10 is developed on a plane in order to understand its configuration.
2 is shown in FIG. In the developed cylindrical slot antenna 1 according to the present invention shown in FIG. 2, an elongated feeding slot 11 and an elongated parasitic feeding slot 12 are arranged along a major axis of a conductive cylindrical portion 10 which is shown as an expanded flat plate. They are formed almost in parallel. The space between the power feeding slot 11 and the non-power feeding slot 12 is set to be a space facing the peripheral side surface when the conductive cylindrical portion 10 has a cylindrical shape. The diameter φ of the conductive cylindrical portion 10, the slot length L1 and the slot width W1 of the feeding slot 11, and the slot length L2 and the slot width W2 of the parasitic slot 12 are used frequency and its bandwidth of the cylindrical slot antenna 1, and It is determined by experiment according to the required directivity.

Next, the diameter φ of the conductive cylindrical portion 10, the slot length L1 and the slot width W1 of the feeding slot 11, and
Slot length L2 and slot width W of parasitic slot 12
2. Some examples of the frequency characteristics of the cylindrical slot antenna 1 with respect to the length L3 indicating the feeding point 11a and the directional characteristics in the horizontal plane when the cylindrical slot antenna 1 is vertically arranged will be described below. In the cylindrical slot antenna 1 according to the present invention shown in FIG. 1, the diameter φ of the conductive cylindrical portion 10 is about 16.0 mm (about 0.1λ), and the slot length L1 of the feeding slot 11 is about 54.0 mm (about 0.342).
λ), the slot width W1 of the feeding slot 11 is set to about 3.5 m.
m (about 0.0222λ), the slot length L2 of the parasitic slot 12 is about 130.0 mm (about 0.823λ), the slot width W2 of the parasitic slot 12 is about 1.0 mm (about 0.0063λ), and the feeding point FIG. 3 shows the frequency characteristics of the impedance, FIG. 4 shows the frequency characteristics of the VSWR, and FIG. 5 shows the directivity characteristics in the horizontal plane when the length L3 indicating 11a is set to about 5.0 mm (0.0316λ). The frequency used is
Assuming that the cylindrical slot antenna 1 is used in the PHS, the frequency band includes the PHS frequency band of 1895 MHz to 1918 MHz.

Referring to the frequency characteristics of the impedance shown in FIG. 3 and the frequency characteristics of the VSWR shown in FIG.
In the HS frequency band, the feed point impedance is 5
The value is close to 0Ω, and it can be seen that it is almost matched to 50Ω which is the characteristic impedance of the coaxial cable 2. Therefore, the VSWR in the PHS frequency band
As shown in FIG. 4, a good value of 1.5 or less was obtained. The directional characteristics in the horizontal plane shown in FIG.
Hz, 1906.5 MHz, and 1920 MHz in the horizontal plane. In this case, 1893M
The maximum gain in Hz is 4.62 dBi, the average gain is 2.54 dBi, the maximum gain in 1906.5 MHz is 4.75 dBi, the average gain is 2.71 dBi, and the maximum gain in 1920 MHz is 4.16 dB.
At i, the average gain is 2.16 dBi. Thus, P
In the HS frequency band, the directivity having substantially the same shape can be obtained, and a high antenna gain can be obtained. Furthermore, although the shape of the directional characteristic in the horizontal plane drops by 5 to 6 db in the 100 ° and 280 ° directions,
Almost omnidirectional directional characteristics are obtained.

Next, the diameter φ of the conductive cylindrical portion 10 in the cylindrical slot antenna 1 according to the present invention shown in FIG.
2.5 mm (about 0.079λ), slot length L1 of feeding slot 11 is about 62.0 mm (about 0.393λ), slot width W1 of feeding slot 11 is about 3.5 mm (about 0.0222λ), no power feeding Slot length L of slot 12
2 is about 130.0 mm (about 0.823λ), and the slot width W2 of the parasitic slot 12 is about 1.0 mm (about 0.0023λ).
63λ), and the length L3 indicating the feeding point 11a is set to about 1.5 mm.
FIG. 6 shows the frequency characteristics of the impedance, FIG. 7 shows the frequency characteristics of the VSWR, and FIG. 8 shows the directional characteristics in the horizontal plane when (0.0095λ). The frequency used is 1895 assuming that the cylindrical slot antenna 1 is used in the PHS.
The frequency band includes the PHS frequency band of 1 MHz to 1918 MHz.

Referring to the frequency characteristics of the impedance shown in FIG. 6 and the frequency characteristics of the VSWR shown in FIG.
In the HS frequency band, the feed point impedance is 5
It can be seen that the value is within a range near 0Ω, and is almost matched to 50Ω which is the characteristic impedance of the coaxial cable 2. In the PHS frequency band, VSWR
As shown in FIG. 7, the value is about 2.0 in the high frequency region, but a good value of 1.5 or less is obtained in most frequency bands. The directional characteristics in the horizontal plane shown in FIG. 8 are 1893 MHz, 1906.5 MHz, 1920M
The directional characteristics in the horizontal plane at Hz are shown, and PHS
In the frequency band of, almost the same shape of directivity is obtained. Further, the antenna gain is slightly lowered, but a reasonable antenna gain can be obtained. further,
The shape of the directional characteristics in the horizontal plane is reduced by about 9 db in the directions of 80 ° and 260 °, and a gourd-type directional characteristic is obtained.

Next, the diameter φ of the conductive cylindrical portion 10 in the cylindrical slot antenna 1 according to the present invention shown in FIG.
0.0 mm (about 0.127λ), the slot length L1 of the feeding slot 11 is about 80.0 mm (about 0.506λ), the slot width W1 of the feeding slot 11 is about 4.5 mm (about 0.029λ), no power feeding Slot length L2 of slot 12
Is about 75.0 mm (about 0.475λ), and the slot width W2 of the parasitic slot 12 is about 1.0 mm (about 0.0063
λ), the length L3 indicating the feeding point 11a is about 10.0 mm
FIG. 9 shows the frequency characteristics of the impedance, FIG. 10 shows the frequency characteristics of the VSWR, and FIG. 11 shows the directional characteristics in the horizontal plane when (0.0633λ). The frequency used is 18 assuming that the cylindrical slot antenna 1 is used in the PHS.
The frequency band includes a PHS frequency band of 95 MHz to 1918 MHz.

Referring to the frequency characteristics of the impedance shown in FIG. 9 and the frequency characteristics of the VSWR shown in FIG.
In the PHS frequency band, the feed point impedance is in the range of about 50Ω, and it is understood that the impedance is almost matched to the characteristic impedance of the coaxial cable 2 of 50Ω. In the PHS frequency band, VSW
As shown in FIG. 10, R is about 1.9 in the high frequency region, but a good value of 1.5 or less is obtained in most frequency bands. The directional characteristics in the horizontal plane shown in FIG. 11 are 1893 MHz, 1906.5 MHz, and 192 MHz.
The directional characteristics in the horizontal plane at 0 MHz are shown. In this case, the maximum gain at 1893 MHz is 5.47 d.
The average gain at Bi was 2.37 dBi and 1906.5.
The maximum gain in MHz is 5.69 dBi and the average gain is 2.63 dBi, and the maximum gain in 1920 MHz is 5.15 dBi and the average gain is 2.07 dBi. As described above, in the PHS frequency band, the directivity having substantially the same shape can be obtained, and a high antenna gain can be obtained. Further, the shape of the directional characteristics in the horizontal plane is almost not radiated in the directions of 100 ° and 280 °, and thus, a figure-shaped directional characteristic is obtained.

Next, the diameter φ of the conductive cylindrical portion 10 in the cylindrical slot antenna 1 according to the present invention shown in FIG.
0.0 mm (about 0.127λ), the slot length L1 of the feeding slot 11 is about 57.0 mm (about 0.361λ), the slot width W1 of the feeding slot 11 is about 4.5 mm (about 0.029λ), and no power is fed. Slot length L2 of slot 12
Is about 117.0 mm (about 0.741λ), and the slot width W2 of the parasitic slot 12 is about 1.0 mm (about 0.006λ).
3λ), the length L3 indicating the feeding point 11a is set to about 17.0 mm.
(0.1076λ), FIG. 12 shows the frequency characteristics of the impedance, and FIG. 13 shows the frequency characteristics of the VSWR.
FIG. 14 shows the directional characteristics in the horizontal plane. The frequency used is 1 assuming that the cylindrical slot antenna 1 is used in the PHS.
The frequency band includes the PHS frequency band of 895 MHz to 1918 MHz.

Referring to the frequency characteristics of the impedance shown in FIG. 12 and the frequency characteristics of the VSWR shown in FIG.
In the PHS frequency band, the feed point impedance has a value near 50Ω, which indicates that the impedance is almost matched to the characteristic impedance of the coaxial cable 2 of 50Ω. For this reason, in the PHS frequency band, the VSW
As shown in FIG. 13, a very good value of R is 1.3 or less. The directional characteristics in the horizontal plane shown in FIG. 14 are 1893 MHz, 1906.5 MHz, and 1920 MHz.
The horizontal directional characteristics at Hz are shown. In this case, the maximum gain at 1893 MHz is 4.34 dBi
And the average gain is 2.59 dBi, 1906.5 MH
The maximum gain at z is 4.61 dBi and the average gain is 2.
The maximum gain at 1920 MHz is 4.20 dBi and the average gain is 2.50 dBi. As described above, in the PHS frequency band, the directivity having substantially the same shape can be obtained, and a high antenna gain can be obtained. Further, the shape of the directional characteristics in the horizontal plane is almost omnidirectional directional characteristics in which a maximum of 4 db drops in the 80 ° and 270 ° directions.

Referring to the antenna characteristics of the cylindrical slot antenna 1 according to the present invention described above, the conductive cylindrical portion 10
Even when the diameter of the power supply slot 11 is as thin as about 16.0 mm (0.101λ), the slot width of the power supply slot 11 can be made as wide as about 3.5 mm, and the slot length can be made as about 54.0 mm. Will not require a mechanical system. In addition, the feeding slot 11 and the non-feeding slot 12
Is simply formed on the conductive cylindrical portion 10, so that the configuration can be simplified. In addition, the passive slot 12
Is longer than the slot length of the feeding slot 11 and is about 130.0 mm, but can be shorter than one wavelength of the operating frequency.
Can be adapted to a collinear array even if the diameter of is reduced. This reason is considered as follows. In the cylindrical slot antenna 1, a current flows on the conductive cylindrical portion 10 in a circular manner from the edge of the feeding slot 11 where the feeding point 11a is provided to the edge where the outer conductor connecting portion 11b is provided. I have. Here, when the diameter of the conductive cylindrical portion 10 is reduced, the conductive cylindrical portion 10
It is considered that a path passing through the back side of the antenna becomes shorter, and current flows through this short path without drawing a circle, whereby the original operation of the cylindrical slot antenna is stopped. Therefore, it is considered that when the parasitic slot 12 is formed to cut off the path passing through the back side of the conductive cylindrical portion 10, the antenna operates as a cylindrical slot antenna. For this reason, by forming the parasitic slot 12 even when the diameter of the conductive cylindrical portion 10 is reduced, the cylindrical slot antenna 1 having the required antenna characteristics can be obtained.

In the cylindrical slot antenna 1 according to the present invention, the diameter φ of the conductive cylindrical portion 10, the slot length L1 and the slot width W1 of the feeding slot 11, and the slot length L2 and the slot width W2 of the parasitic slot 12 are determined. hand,
As shown in the frequency characteristics of the VSWR, the frequency characteristics from the narrow band to the wide band, and as shown in the directional characteristics in the horizontal plane, almost omnidirectional to 8
Can be obtained up to the directional characteristic in the horizontal plane. Further, by changing the length L3 indicating the feeding point 11a, the impedance of the cylindrical slot antenna 1 can be matched to the coaxial cable 2 to be fed.

Next, FIG. 15 shows a configuration of a modification of the embodiment of the cylindrical slot antenna of the present invention. FIG.
The cylindrical slot antenna 5 according to the present invention shown in FIG. 1 is configured by stacking slot antennas in multiple stages. The cylindrical slot antenna 5 includes an upper slot antenna formed of a feed slot 21 and a parasitic slot 22 formed on the peripheral side surface of the conductive cylindrical portion 20, and a lower slot antenna formed of a feed slot 25 and a parasitic slot 26. I have. The power supply slot 21 and the power supply slot 25 are formed at substantially the same position on the peripheral side surface of the conductive cylindrical portion 20, and the non-power supply slot 22 and the non-power supply slot 26 are also substantially at the same position on the peripheral side surface of the conductive cylindrical portion 20. Is formed.
And a power supply slot 21 and a power supply slot 25;
The parasitic slot 22 and the parasitic slot 26 are formed at positions on the peripheral side surface of the conductive cylindrical portion 20 facing each other.

The lower slot antenna has a coaxial cable 7 at a feed point 25a formed at one edge of the feed slot 25.
And the outer conductor of the coaxial cable 7 is connected to the outer conductor connecting portion 25b formed on the other edge. The core wire 6a and the outer conductor of the coaxial cable 6 are also connected to the feeding point 25a and the outer conductor connecting portion 25b.
The core wire 6a of the coaxial cable 6 is connected to a power supply point 21a formed on one edge of the power supply slot 21, and the outer conductor of the coaxial cable 6 is connected to an outer conductor connecting portion 21b formed on the other edge. Power is being supplied. The coaxial cable 6 has nλ (n is 1, 2, 3,...) So that the upper slot antenna and the lower slot antenna are fed in phase.
・) Length. Further, the coaxial cables 6 and 7 may be housed in the conductive cylindrical portion 20 as semi-rigid cables. In addition, cylindrical slot antenna 5
In the above, the slot length and slot width of the feeding slot 21 and the feeding slot 25 have the same dimensions, and the slot length and slot width of the parasitic slot 22 and the parasitic slot 26 have the same dimensions. The upper slot antenna and the lower slot antenna can be arranged at an interval within one wavelength of the operating frequency.

Next, FIG. 16 shows the configuration of an embodiment of the polarization diversity antenna of the present invention. The polarization diversity antenna 50 shown in FIG. 16 is arranged vertically, and is configured by providing a vertical polarization dipole antenna on a horizontal polarization cylindrical slot antenna 70.
The configuration of the horizontally polarized cylindrical slot antenna 70 is the same as that of the cylindrical slot antenna 1 shown in FIG. 1, and the feed slot 72 is formed on the peripheral side surface of the conductive cylindrical portion 71. Then, the core wire 74a of the coaxial cable 74 is
2a, and the outer conductor of the coaxial cable 74 is connected to the outer conductor connecting portion 72b.
Power is supplied to the cylindrical slot antenna 70 for horizontal polarization. The non-feed slot 73 is connected to the feed slot 7.
2 are formed on the circumferential side surface of the conductive cylindrical portion 71 facing the second cylindrical portion.

On the other hand, the vertically polarized dipole antenna 60
Is composed of a vertically arranged dipole element 61a and a dipole element 61b, and a central wire 62a of the coaxial cable 62 is provided at the center of the vertically polarized dipole antenna 60.
Are connected to the feeding point 60a of the dipole element 61a, and the outer conductor of the coaxial cable 62 is connected to the outer conductor connecting portion 60b of the dipole element 61b. However, since the power is supplied from the unbalanced coaxial cable 62 to the balanced vertically polarized dipole antenna 60, power is supplied with a balun interposed therebetween.

The cylindrical slot antenna 70 for horizontal polarization configured as described above can receive a horizontal polarization component, and the dipole antenna 60 for vertical polarization can receive a vertical polarization component. Therefore, the horizontal polarization cylindrical slot antenna 70 and the vertical polarization dipole antenna 6
By selecting and receiving the received signal having the higher level of the received signal received as 0, it is possible to use the polarization diversity receiving method. The polarization diversity antenna 50 used in this polarization diversity system is configured such that a cylindrical slot antenna 70 for horizontal polarization and a dipole antenna 60 for vertical polarization are arranged coaxially in the vertical direction, and have the same diameter. Can be made small, so that a compact and small polarization diversity antenna can be obtained. In the cylindrical slot antenna according to the present invention described above and the polarization diversity antenna to which the cylindrical slot antenna according to the present invention is applied,
The coaxial cable may be a coaxial cable having a diameter sufficiently smaller than the diameter of the conductive cylindrical portion such as a semi-rigid cable, and the coaxial cable may be housed in the conductive cylindrical portion.

[0030]

As described above, according to the present invention, since the non-feeding slot is provided so as to face the feeding slot formed on the peripheral side surface of the cylindrical body, the slot can be formed even if the diameter of the cylindrical body is reduced. The width can be made wider and shorter. Thus, even if the diameter of the cylindrical slot antenna is reduced, high mechanical accuracy is not required.
Further, since the feeding slot and the non-feeding slot are merely formed in the cylindrical body, the configuration can be simplified. Also, the length of the parasitic element may be longer than the length of the feeding element depending on the specification, but the length can be shorter than one wavelength of the operating frequency. Can also be adapted to collinear arrays. Furthermore, since the diameter of the cylindrical body in the cylindrical slot antenna can be reduced, a compact and small horizontal polarization antenna can be obtained by vertically disposing the cylindrical slot antenna. In this case, even if the diameter of the cylindrical body is as small as, for example, 0.08 wavelength at the operating frequency, the cylindrical slot antenna can be applied to the collinear array and has a simple configuration that does not require high-precision machining. become.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration according to an embodiment of a cylindrical slot antenna of the present invention.

FIG. 2 is a development view showing a configuration of a cylindrical slot antenna according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating frequency characteristics of impedance when the cylindrical slot antenna according to the embodiment of the present invention has a first dimension.

FIG. 4 is a diagram illustrating a frequency characteristic of a VSWR when the cylindrical slot antenna according to the embodiment of the present invention has a first dimension.

FIG. 5 is a diagram showing directional characteristics in a horizontal plane when the cylindrical slot antenna according to the embodiment of the present invention has a first dimension.

FIG. 6 is a diagram illustrating frequency characteristics of impedance when the cylindrical slot antenna according to the embodiment of the present invention has a second dimension.

FIG. 7 is a diagram showing a frequency characteristic of the VSWR when the cylindrical slot antenna according to the embodiment of the present invention has a second dimension.

FIG. 8 is a diagram showing directional characteristics in a horizontal plane when the cylindrical slot antenna according to the embodiment of the present invention has a second dimension.

FIG. 9 is a diagram illustrating frequency characteristics of impedance when the cylindrical slot antenna according to the embodiment of the present invention has a third dimension.

FIG. 10 is a diagram illustrating a frequency characteristic of VSWR when the cylindrical slot antenna according to the embodiment of the present invention has a third dimension.

FIG. 11 is a diagram showing directional characteristics in a horizontal plane when the cylindrical slot antenna according to the embodiment of the present invention has a third dimension.

FIG. 12 is a diagram illustrating frequency characteristics of impedance when the cylindrical slot antenna according to the embodiment of the present invention has a fourth dimension.

FIG. 13 is a diagram showing a frequency characteristic of VSWR when the cylindrical slot antenna according to the embodiment of the present invention has a fourth dimension.

FIG. 14 is a diagram showing directional characteristics in a horizontal plane when the cylindrical slot antenna according to the embodiment of the present invention has a fourth dimension.

FIG. 15 is a perspective view showing a configuration of a modified example according to the embodiment of the cylindrical slot antenna of the present invention.

FIG. 16 is a perspective view showing a configuration of a polarization diversity antenna according to an embodiment of the present invention.

[Explanation of symbols]

1 cylindrical slot antenna, 2 coaxial cable, 2a
Core wire, 5 cylindrical slot antenna, 6 coaxial cable,
6a core wire, 7 coaxial cable, 7a core wire, 10 conductive cylindrical portion, 11 feeding slot, 11a feeding point, 11
b outer conductor connection part, 12 no-feed slot, 20 conductive cylindrical part, 21 feeding slot, 21a feeding point, 21b
Outer conductor connection part, 22 No-power feeding slot, 25 feeding slot, 25a Feeding point, 25b Outer conductor connection part, 26
Parasitic slot, 50 polarization diversity antenna,
60 dipole antenna for vertical polarization, 60a feed point, 60b outer conductor connection part, 61a dipole element,
61b dipole element, 62 coaxial cable, 62a
Core wire, 70 cylindrical slot antenna for horizontal polarization, 71 conductive cylindrical portion, 72 feed slot, 72a feed point, 72
b Outer conductor connection, 73 parasitic slot, 74 coaxial cable, 74a core wire

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 5J021 AA02 AA07 AA11 AA13 AB05 FA32 HA05 HA06 HA10 JA05 JA07 5J045 AA12 AB05 AB06 CA02 CA03 DA04 HA06 JA03 NA01

Claims (3)

[Claims] 1. A conductive cylinder, a power supply slot elongated on a peripheral side surface of the cylinder so as to extend substantially along a central axis of the cylinder, and a power supply slot formed on a central axis of the cylinder. And a non-feeding slot extending substantially along the peripheral surface of the cylindrical body so as to face the feeding slot. 2. The cylindrical slot antenna according to claim 1, wherein said feeding slot and said non-feeding slot are formed in multiple stages on a peripheral side surface of said cylindrical body. 3. An electrically conductive cylindrical body which is erected substantially vertically, a feeding slot which is elongated on a peripheral side surface of the cylindrical body so as to extend substantially along a central axis of the cylindrical body, and A horizontally polarized antenna extending substantially along the central axis of the cylindrical body and having a parasitic slot formed on the peripheral side surface of the cylindrical body so as to be opposed to the feed slot; A polarization diversity antenna, comprising: a vertically polarized antenna that is coaxially arranged and includes a vertically polarized element that extends substantially vertically.