JPS6112104A - Multi-stage crossing type high gain antenna - Google Patents

Abstract

PURPOSE:To improve the directivity characterisric and the earthquake resistance and wind resistance by arranging plural number of unit antennas comprising a central feeding multi-stage crossing type vertical antenna around a vertical supporting pole. CONSTITUTION:Upper and lower supports 21, 22 are fixed near both ends of the vertical supporting pole 1. The unit antennas 61-64 are supported around the supporting pole 1 in parallel to the upper/lower supports 21, 22. The unit antannas 61-64 consist of the central feeding multi-stage crossing type vertical antenna. For example, plural number of coaxial dipole antenna elements are connected in cascade and they are energized from the central part. Through the forming above, the excellent desired directivity characterisric is obtained and the earthquake resistance and wind resistance are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multistage intersecting high gain antenna.

Vertically polarized antennas used in base stations such as automobile radio telephones are omnidirectional in the horizontal plane, have horizontal directionality over a wide band in the vertical plane, and have high gain, earthquake resistance, and An antenna that satisfies these requirements to a certain extent is required to have excellent wind speed resistance, but conventional antennas have been constructed by installing multiple coaxial dipole antenna elements vertically and connecting each antenna element in parallel. has been put into practical use.

This conventional antenna has a large number of mechanical fixing points to keep each antenna element in a vertical state and is supported by a vertical support, and a large number of electrical connection points to feed power to each antenna element. , it takes a relatively large amount of time and effort to manufacture, and if the connection at the electrical connection point for power supply is unstable, micro discharges will occur in this part, causing continuous white noise in the transmitting and receiving frequency band. In addition to generating noise, a non-linear component is generated in this portion, which may cause a cross-modulation wave to be generated, albeit a small one, and to cause cross-modulation interference in the transmitting and receiving frequency band.

The present invention is non-directional in the horizontal plane, has horizontal directionality over a wide range in the vertical plane, has excellent earthquake resistance and wind speed resistance, and facilitates the connection of electrical and mechanical connection parts. The object of the present invention is to realize a vertically polarized skin antenna for high power, which can be operated reliably and is free from the risk of noise disturbances and cross-modulation disturbances caused by instability of connection parts.

FIG. 1 is a side view showing one embodiment of the present invention, and FIG. 2 is a side view showing an embodiment of the present invention.
In both figures, reference numeral 1 denotes a vertical support made of, for example, a steel pipe or a steel rod. Although not shown in Figure 1,
The base of the column 1 is fixed to a suitable support, such as the top of a support tower. Reference numeral 21 denotes an upper support body, which includes a ring-shaped base 3 that fits onto the upper part of the vertical support 1 and is fixed by screwing or welding, and support arms 4I that protrude from the outer peripheral surface of the base 3 at equal intervals in the circumferential direction. or hemp, and ring-shaped parts 51 to 54 attached to the outer ends of each of the supporting arms 41 to 4. 2- is a lower support, which has the same structure as the upper support 21, and is linked so that the protruding direction of the four support arms matches the protrusion direction of the support arms 4-4f1 on the upper support 2I. The shaped base is fitted and fixed to the lower part of the vertical support 1. 6I to 6φ each consist of a same-shaped protrusion. To attach the unit antenna 61 to the upper and lower supports 2 and 2, for example, after inserting the top of the unit antenna 6t into the ring-shaped portion 5I at the outer end of the support arm 41 of the upper support 2I, The lower part of the unit antenna 6I is placed in the support arm 4F of the upper support 21 in the support arm 2- of the lower support 2-.
By inserting the stopper 71 into the ring-shaped part at the outer end of the support arm corresponding to the ring-shaped part, the stopper 71 is crimped to the periphery of this ring-shaped part, and the unit antenna 6r can be inserted through the upper and lower supports 21 and 22 without falling. It is supported parallel to the vertical support 1. The same applies to the case where other unit antennas 6 or 4 are supported. Incidentally, the mechanical support strength may be increased by fixing the unit antenna and the ring-shaped portion at the outer end of the support arm by appropriate means. 8I to 84 are each unit antenna feed 1it,
9 is a four-branch terminal, and IQ is a common feed line.

Although FIG. 2 shows an example in which the vertical support 1 is formed of a hollow tube with a circular cross-sectional shape, as shown in FIG. Alternatively, as shown in FIG. 4, the vertical support 1 may be formed of a rectangular-like hollow tube with an inwardly concave arc-shaped side wall. It may also be formed using the body.

Although Figures 1 and 2 show an example in which four unit antennas are provided, it is possible to use three or five or more unit antennas, or to increase the distance between the vertical support and the unit antenna.
If the cross-sectional shape of
It is desirable that the cross-section and surface shape of the pillar be formed into a polygon according to the number of unit antennas.

As mentioned above, the configuration of each unit antenna is the same. Next, the specific configuration of the unit antenna will be explained.

FIG. 5 is a diagram showing an example of the configuration of a unit antenna.
1 to II+o are metal cylindrical bodies, each axial length of which is formed to be slightly shorter than the datum of the transmitting/receiving wavelength or A, and each axial direction is maintained perpendicularly. Reference numeral 12 denotes a coaxial transmission line having an outer conductor made of a rigid body, and is made of, for example, a coaxial tube or a 7 millimeter cable. Hereinafter, a case in which a coaxial tube is used will be explained. The coaxial tube 12 is made of metal cylinder II + %
Commonly inserted into 113% lb, 11ri and I+,
These metal cylinders and the coaxial tube are filled with an appropriate dielectric material (for example, polyethylene), or an appropriate insulating spacer is interposed between the metal cylinder and the outer conductor portion of the coaxial tube within these metal cylinders. This forms a coaxial dipole antenna element, and the metal cylinders 111 to 119 are mechanically supported by the coaxial tube 12 at appropriate intervals in the vertical direction. 13 is a metal support rod, which is a metal cylindrical body 11a.

I 1m % + 14 % l It and + 111
1, and fill the space between these metal cylinders and the metal support rod with an appropriate dielectric, or interpose an appropriate insulating spacer, etc. to connect the metal cylinders and the metal support rods in these metal cylinders. A coaxial dipole antenna element is formed by the metal support rod 13, and the metal cylinders 11° to Il+o are mechanically supported at appropriate intervals in the vertical direction, and the lower end of the metal support rod 13 is connected to the metal cylinder. It is fixed to the body 111, and the metal cylindrical body 11Jslli
, 117 and the eye 9 are connected to the metal cylindrical body 11. , +14, eyes 6.
Metal support rod 1 exposed between each of 118 and ll+o
It is fixed to the part 3 and the metal cylindrical body 111.11g
5 Ila, 118 and ILo in a metal cylinder 111%l
b, 11! , 11 and 11 and to the outer conductor of the coaxial tube 12 exposed above 119. to lI+o are vertically intersected by a coaxial tube 12 and a metal support rod +3, and are integrally supported.

14I and +4J are short circuit plates; 14. is the metal cylinder I1
1 to short-circuit between the metal cylindrical body If and the outer conductor of the coaxial tube 12 to prevent the signal from leaking downward to the metal cylindrical body II+.
The metal cylindrical body I is internally installed at a location approximately % of the axial length of +o.
I+o and the metal support rod 13 are short-circuited, and the metal cylindrical body 111
o Prevents the signal from leaking upward. Reference numeral 15 denotes a power feeding point, which is formed by connecting the internal conductor of the coaxial tube 12 to the upper end of the metal cylinder 1. This feeding point 15
The internal conductor of the coaxial pipe +2 above can be removed completely, or the internal conductor of the coaxial pipe 12 can be connected to the inside and outside of the coaxial pipe 12 at a point separated upward by the length of the feeding point 15 (where the inner conductor is the wavelength within the pipe) or an odd number multiple of the length. Short-circuit between the conductors or from the feed point 15■
Or, by cutting the internal conductor of the coaxial pipe 12 to open it at a point separated upward by an integral multiple of the length, the inside of the coaxial pipe 12 above the power feeding point 15 is kept electrically disconnected. It is. Reference numeral 16 denotes a Schwartz tube, which is made of a metal sleeve having the axial length of a roof tile, and short-circuits between its lower edge and the outer conductor of the coaxial tube 12 to prevent unnecessary current from flowing through the outer conductor.

FIG. 6 shows the metal cylinder 111 to ILo and the coaxial tube 12.
and a metal support rod 13, in which the metal cylinder 111 is connected to the internal conductor of the metal cylinder 11-, and the internal conductor of the metal cylinder 11+ is connected to the metal cylinder 11. -, the outer conductor and the inner conductor forming the coaxial dipole antenna element are alternately crossed and connected in cascade, and a part of the coaxial tube 12 is also used as a feed line, and its feed point 15 is Since it is selected as the midpoint of 10 coaxial dipole antenna elements,
The equal circuit is illustrated by FIG.

In FIG. 7, U; to If;o are coaxial dipole antenna elements, 12' is a feeder line, 14'1 and 14
``a'' is a short circuit point, 15 is a feeding point, and 17 is a signal source.

In this unit antenna, the same number of antenna elements provided above and below the feed point 15 are electrically connected in parallel to the feed point 15, so that the lower antenna element is 11 mm, 11'4, 11' 3, II- and 111 directions, and at the same time the upper antenna element is excited in the 111.1 direction.
1, it will be excited sequentially in the directions of Il'gxll'I and ll'Io, and if the frequency of the excitation power is the design frequency, for example 820 MHz, the directivity in the vertical plane will be as shown in Figure 8. produces a beam in the horizontal direction.

At a frequency other than the design frequency, for example 790 MHz, the directivity in the vertical plane due to the antenna elements 11'6 to lI'+o above the feed point 15 is smaller than that in the horizontal direction, as shown by the dashed line in FIG. The beam is produced in an upward angular direction, and the directivity in the vertical plane of the antenna elements 11 to 11 at the bottom of the feed point 15 is as follows.
As shown by the broken line in the figure, a beam is generated in a downward angular direction from the horizontal direction, but the directivity due to the antenna element group at the top of the feed point 15 and the direction due to the antenna element control at the bottom of the feed point 15 are generated. 1 student is synthesized,
As shown by the solid line in FIG. 9, a beam is generated in the horizontal direction within the vertical plane. At a frequency higher than the transmitter frequency, for example 840 MHz, the directivity in the vertical plane by the antenna element group at the top of the feeding point 15 is such that the beam is directed downward in the angular direction from the horizontal direction, as shown by the dashed line in FIG. The directivity in the vertical plane by the antenna element group at the bottom of the feeding point 15 produces a beam in an angular direction upward from the horizontal direction, as shown by the broken line in FIG. The directivities of the antenna element groups above and below 15 are combined to produce a beam in the horizontal direction within the vertical plane, as shown by the solid line in FIG.

In other words, this unit antenna has good directivity frequency characteristics in the vertical plane over a wide band, and even when the number of antenna elements is increased or decreased according to the required gain, the feeding point 1
By selecting the same number of antenna elements above and below Q5, the directivities of the antenna element groups above and below the feeding point 15 are combined to produce a beam in the horizontal direction within the vertical plane. Note that the directivity in the horizontal plane exhibits non-directional characteristics.

In addition, in this unit antenna, there is only one connection point for feeding power, the feeding point 15 (115r'), and the internal conductors of the metal cylinders 111 to 1110 are connected to a common coaxial tube 12.
and a common metal support rod 13, and since the number of component parts is small, manufacturing is easy and costs can be reduced.

It should be noted that between each outer conductor and inner conductor of antenna elements 111 to 11a in this unit antenna (for example, when filled with a dielectric material such as polyethylene, the high frequency voltage (or current) propagating inside the antenna element) A phase difference occurs between the antenna element and the high-frequency voltage (or current) propagating outside, but the phase difference can be reduced by making the axial length of the antenna element almost match the length described below.
By adjusting the angle, it is possible to provide even better directivity characteristics at the design frequency.

Generally, when a dielectric material with a high permittivity is filled between the inner and outer conductors of a coaxial pipe, there is a relationship between the wavelength input in the pipe and the free space wavelength, so the signal propagating between the outside and the inside of the coaxial pipe is In order to create a phase difference of 96, (tiles) between the
It is necessary to choose the axial length of the coaxial tube.

For example, polyethylene between the inner and outer conductors of a coaxial pipe? When filled, the dielectric constant is approximately 2.3, so (3)
The formula is:

Even in the coaxial dipole antenna element constituting the unit antenna in the antenna of the present invention, it is necessary to shorten the actual axial length from the theoretical value due to the corner effect.
According to the results of experiments conducted by the present inventors on the prototype, the axial length of the antenna element was set at no.
・・・・・・ Selected as (4), 3
In particular, we were able to obtain a unit antenna that was omnidirectional in the Q horizontal plane, produced a sharp beam in the horizontal direction in the vertical plane, and had a high gain.

The above explanation is based on the case where the same number of coaxial dipole antenna elements are provided above and below the feeding point. However, when there are many antenna elements, it is necessary to It can have sex.

Although not shown in FIG. 5, the metal cylinders 111 to Il+ constitute the coaxial dipole antenna element.

A bottomed cylindrical antenna cover 7 or 74 made of fiber-reinforced plastic (F, R, P, etc.) is attached to the outside of the super top 16, and the upper and lower parts are supported as explained with reference to FIG. Support bars are provided on the bodies 21 and 2, and the metal cylindrical body 11+v is supported on the upper support body 21 while maintaining insulation between it and the vertical support 1, and the super top 16 or the metal cylindrical body 1! [ may be supported by the lower support 2°. Further, the lower end of the coaxial tube 12 in FIG. 5 is connected to any one of the power supply lines 8I to 84 shown in FIG. 1.

The vertical plane of the antenna of the present invention is constructed by arranging a plurality of unit antennas around a vertical support, that is, a plurality of unit antennas each consisting of a centrally fed multi-stage intersecting vertical antenna as explained with reference to FIGS. 5 to 10, as described above. Directional characteristics within,
In other words, to explain the overall pattern of directivity in the vertical plane at a sufficiently far distance, on the same horizontal plane perpendicular to the central axis of the vertical support, on the same circumference centered on the central axis of the vertical support, in the circumferential direction. Comprehensive pattern D (θ, Φ ) is given by the following equation.

...(5) However, N: On the same horizontal plane perpendicular to the central axis of the vertical support, at multiple locations equally spaced in the circumferential direction on the same circumference centered on the central axis of the vertical support. Total number of antenna elements (one each) θ: Angle of inclination or elevation with respect to the horizontal plane Φ: Azimuth angle in the horizontal plane a: Radius of the vertical support b: Center distance between the vertical support and the antenna element 2π to 2□ Person entry: Free space wavelength position internal angle εA: When m=O, ε knee 1 Field=1, 2, 3.・・・・・・Noto@Suzuku=2H'm(x
) = Jm(x) -jYm(x) : m-order \Nkel function of the second kind J (x) : m-order Betz function Y, (x) : m-order Neumann function j : imaginary unit in the horizontal plane The total pattern of directional characteristics is (5)
In the formula e = Q, ie cose=l +! : Required by doing.

As mentioned above, at each location where one coaxial Quiball antenna element is provided around the vertical support,
The total no.＼turn Dt(+3+Φ
) is obtained by multiplying D(θ, Φ) in equation (5) by the array factor, and is given by the following equation.

......(6) However, M: Number of antenna elements (number of stages) in the AAA antenna d2jtL Among the antenna elements in the antenna,
The center spacing between adjacent antenna elements in Figures 11 to 13 is based on a design frequency of 800MHz,
This shows the overall pattern of directivity in the horizontal plane based on theoretical calculations when the radius of the vertical strut is 25 wavelengths and the number of unit antennas is four. In this case, FIG. 12 shows the case where the center spacing is 0.45 wavelengths, and FIG. 13 shows the case where the center spacing is 0.5 wavelengths.

When examining directivity characteristics, if the change in electric field strength is within ±3 clB, it is assumed that the electric field strength is the same, so each pattern in Figures 11 to 13 can be regarded as non-directional. .

In addition, by forming the cross-sectional shape of the vertical support into a rectangular shape with a recess as shown in the fourth figure, and by utilizing the reflection of the electromagnetic waves on the surface, omnidirectionality in the horizontal plane can be made even more perfect. It can be done.

FIG. 14 shows six unit antennas, and FIG. 15 shows eight unit antennas arranged at equal intervals in the circumferential direction, and the center distance between the vertical support and the unit antennas is set to 0.
5 wavelengths, and the radius of the vertical support and the design frequency are the 11th wavelength.
This is the overall pattern of the directivity characteristics at one point in the horizontal plane when the pattern is similar to that shown in Figures 1 to 13. As is clear from both figures, as the number of unit antennas increases, it approaches complete omnidirectionality. .

Instead of arranging the unit antennas at equal intervals in the circumferential direction, by arranging the unit antennas in a concentrated manner in any direction from the vertical support, directivity can be provided in any direction.

In the antenna of the present invention, the outer conductor of the metal cylindrical body I11 or the 1iOb coaxial tube 12 constituting the first antenna,
The fixed part between the metal support rods 13 etc. and the connection part of the power feeding part can be firmly connected by soldering or the like, and the connection between each unit antenna and the vertical support can be made via a solid material. Therefore, there is no risk of noise interference or cross-modulation interference, and since each unit antenna is supported by a support made of steel pipes, etc., the reliability of the electrical connection and mechanically fixed parts of the unit antenna is improved. In combination, it has excellent earthquake resistance and wind speed resistance, has good directivity characteristics, and can increase transmission and reception power by a multiple of the number of unit antennas, making it suitable as an antenna for base stations such as automobile radio telephones.

[Brief explanation of drawings]

FIG. 1 is a side view showing one embodiment of the present invention, and FIG. 2 is a side view showing an embodiment of the present invention.
The plan view, FIGS. 3 and 4 are cross-sectional views showing other examples of the main structure, FIG. 5 is a view showing an example of the structure of the unit antenna which is the main part of the present invention, and FIG. , a diagram showing its electrical connection, FIG. 7 is its equivalent circuit diagram, and FIGS. 8 to 10.
The figures are diagrams explaining the directional characteristics, Figures 11 to 1.
Figure 5 is a diagram explaining the directional characteristics of the antenna of the present invention.
: Vertical support, 21 and 2a double support, 3: Ring-shaped base, 41 to 4 umbrellas: Support arm, 51 to 54: Ring-shaped part, 6/or 41: Unit antenna, 7+ to 74: Stopper, 8 No to 81: Power feed line, 9: 4 branch terminal, 10: Common power feed line, 11I to lI+o: Metal cylinder, 12: Coaxial transmission line, 13: Metal support rod, 14
+ and 142: Short circuit board, 15: Feeding point, 16: Chevel top, ! 7: signal source, 11'1 to II'+o: antenna element, 12': feed line, 14'1 and +4'J:
It is a short circuit point.

Claims (6)

[Claims] (1) A multi-stage cross-type high-gain antenna characterized in that a plurality of unit antennas each consisting of a center-fed multi-stage cross-type vertical antenna are arranged around a vertical column. (2) A multi-stage cross-type high gain antenna according to claim 1, wherein the unit antennas are provided at points equally spaced in the circumferential direction on a circumference centered on a vertical support. (3) The multi-stage cross-type high gain antenna according to claim 1, wherein the unit antennas are centrally provided in any direction from the vertical support. (4) A unit antenna is constructed by arranging a plurality of coaxial dipole antenna elements vertically and connecting the outer conductor of one antenna element of the adjacent coaxial dipole antenna elements to the inner conductor of the other antenna element. , the plurality of coaxial dipole antenna elements are connected in cascade such that the inner conductor of the one antenna element is connected to the outer conductor of the other antenna element, and the plurality of coaxial dipole antenna elements are connected approximately at the center of the plurality of coaxial dipole antenna elements. A multi-stage cross-type high gain antenna according to any one of claims 1 to 3, configured to feed power to a cascade connection line. (5) Each inner conductor of every other coaxial dipole antenna element is formed with a common coaxial transmission line, and the inside of this coaxial transmission line in the upper part from the feeding point is kept electrically disconnected, and the feeding point is 5. The multi-stage cross-type high gain antenna according to claim 4, wherein a portion below the point is also used as a feed line, and said every other coaxial dipole antenna element is supported by said coaxial transmission line. (6) Each internal conductor of every other coaxial dipole antenna element is formed with a common coaxial transmission line, and the inside of the coaxial transmission line above the feeding point is kept electrically disconnected, and the feeding point is The portion below the point is also used as a feed line, and the coaxial transmission line supports every other coaxial dipole antenna element, and each of the coaxial dipole antenna elements other than the every other coaxial dipole antenna element 4. The multi-stage intersecting antenna element according to claim 4, wherein the internal conductor is formed of a common metal rod, and the metal rod supports coaxial dipole antenna elements other than every other coaxial dipole antenna element. gain antenna.