JPH08335825A - Antenna system - Google Patents

Abstract

PURPOSE: To eliminate a non-sense state generating by the null that is caused above an exciter without deteriorating the horizontal radiation characteristic by providing a conductor member having its height set against a metallic base plate within a specific ratio range of the working wavelength at a position that is distant away from the exciter in the specific ratio range on the surface where the exciter of the metallic base plate is placed. CONSTITUTION: A monopole antenna consists of a metallic base plate 2a and a rod-shaped exciter 1 which is placed on the plate 2a. Then at least one conductor member 3 having its height set against the plate 2a within 1/4 to 1/12 working wavelength is provided at a position that is distant away from the exciter 1 in 1/2 to 1/12 working wavelength on the surface of the plate 2a where the exciter 1 is placed. For instance, the plate 2a has a round shape and the exciter 1 is set at the center of the plate 2a together with plural members 3 provided on the circumference of the plate 2a. Then the lengths of the exciter 1 and every member 3 are set at about λ/4 and λ/5 respectively. Thus the radius of the plate 2a is set at about λ/2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna device for high-speed wireless data communication such as a wireless LAN, which eliminates a null point generated in the antenna directivity characteristic without changing the shape of the antenna directivity main lobe. By doing so, the present invention relates to an antenna device that can eliminate a dead area caused by a null.

[0002]

2. Description of the Related Art FIG. 15 is a view showing an example of a conventional monopole antenna with a metal ground plane, in which (a) is a perspective view,
(B) has shown sectional drawing.

In the figure, numeral 100 is an exciter,
Reference numeral 200 represents a metal base plate. FIG. 16 shows an example of radiation directivity in the vertical plane of such a conventional antenna. In this figure, the Z axis is the longitudinal direction of the exciter, and the X axis is the plane direction of the metal base plate.

This example shows the characteristics when the diameter of the metal base plate is assumed to be 2λ and the height of the exciter is assumed to be ¼ wavelength. The solid line shows the calculated value by the method of moments, and the symbol x shows the measured value.

In the figure, θ indicates spherical coordinates. θ =
In the range of the angle γ from −10 ° to θ = 10 °, the gain is −10 dBi or less, and the dead zone occurs in this direction.
Further, numeral 104 is a main lobe, 105 is a side lobe, and 106 is a back lobe.

FIG. 17 is a diagram showing an example of a conventional monopole antenna with a corner reflector, in which (a) is a perspective view and (b) is a top view. Number code 100, 2
00 is the same as in FIG. 15, and 300 is a corner reflector. Further, R is the length of the reflector, h is the height of the reflector, and α is the corner angle.

FIG. 18 is a diagram showing the radiation directivity in the vertical plane of this antenna, which is an example of calculation using the method of moments. In the figure, θ is spherical coordinates, the height of the exciter shown in FIG. 17 is 1/4 wavelength, the length R of the reflector is 1.5 wavelength, the angle α of the corner is 30 °, and the width of the metal base plate. ,
If the length of the metal ground plane is assumed to be infinity, θ
The vertical in-plane radiation directivity from = -90 ° to θ = 90 ° is shown.

The numeral 104 indicates the main lobe, 1
Reference numeral 05 is a side lobe and 106 is a back lobe. θ
The gain is 0 dBi at an angle η from = 0 ° to θ = 15 °
The following is obtained, and it can be seen that a dead zone occurs in this direction.

19A and 19B are views showing another example of the conventional antenna, in which FIG. 19A is a top view and FIG. 19B is a sectional view. This antenna is a switch-over type sector beam antenna configured by arranging twelve monopole antennas with corner reflectors shown in FIG. 17 all having a corner angle of 30 °.

In the figure, numeral 100 is an exciter,
200 is a metal ground plane, 300 is a corner reflector, 108
Is an antenna changeover switch, and 109 is radiation directivity.

The directivity of a monopole antenna with a corner reflector used as a sector beam antenna switched by an antenna changeover switch as shown in FIG.
In the range where θ is 0 ° or more and 90 ° or less, there is no dead zone, the gain is high, and the side lobe 105 and the back lobe 106 that appear in the range where θ is less than 0 ° are small. desired.

[0012]

FIG. 20 shows an example in which the monopole antenna with a metal ground plane shown in FIG. 15 is used as a base station antenna, and the sector beam antenna with a metal ground plane shown in FIG. 19 is used as a terminal antenna. Is schematically shown. In the figure, reference numeral 150 is a base station antenna using a monopole antenna with a metal ground plane, 151 to 1
Reference numerals 54 respectively indicate terminals using a switchover sector beam antenna.

The terminal 153 has a large transmitting antenna gain and a large receiving antenna gain. On the other hand, the terminal 154 has small transmission antenna gain and reception antenna gain for direct waves, and has large transmission antenna gain and reception antenna gain for interference waves. Therefore, the D / U ratio is greatly deteriorated.

As described above, in the conventional monopole antenna with a metal ground plane and the monopole antenna with a corner reflector, a null is generated just above the exciter, which deteriorates the D / U ratio and causes a dead zone. There was a problem that became. The present invention has been made to solve the above problems, and an object of the present invention is to realize an antenna device in which null does not occur directly above an exciter without impairing the shape of the main lobe.

[0015]

According to the invention, the above mentioned objects are achieved by means of the patent claims.

That is, according to the first aspect of the present invention, in a monopole antenna with a metal ground plane, which is composed of a metal ground plane and a rod-shaped exciter erected on the metal ground plane, a surface on which the metal ground plane exciter is present. Of the conductor on the metal ground plane at a distance of about 1/2 to 1/4 of the working wavelength from the exciter on the metal ground plane. It is an antenna device provided with one.

According to a second aspect of the present invention, in a monopole antenna with a metal base plate, which is composed of a metal base plate and a rod-shaped exciter erected on the metal base plate, the surface of the metal base plate on which the exciter is present. Around the circumference of the exciter on the metal ground plane, whose radius is approximately 1/2 to 1/4 of the working wavelength, the height from the metal ground plane is 1/4 to 1/12 of the working wavelength. The antenna device is provided with a conductor member.

According to a third aspect of the present invention, in a monopole antenna with a metal base plate composed of a metal base plate and a rod-shaped exciter standing on the metal base plate, the radius is approximately 1/2 to 1 of the usable wavelength. / 4 and the width is 1/4 to 1/1 of the used wavelength
2 is an antenna device in which a conductor ring-shaped member is attached to the side of the metal base plate on which the exciter is present so that the center of the ring member is substantially at the position of the exciter.

According to a fourth aspect of the present invention, in a monopole antenna with a corner reflector having a metal base plate, a rod-shaped exciter standing upright on the metal base plate, and a corner reflector, the metal base plate near an opening of the corner reflector. This is an antenna device in which at least one rod-shaped conductor member whose height from the metal ground plane is 1/4 to 1/12 of the used wavelength is attached.

According to a fifth aspect of the present invention, in a monopole antenna with a corner reflector having a metal base plate, a rod-shaped exciter standing upright on the metal base plate, and a corner reflector, the opening of the corner reflector is on the metal base plate. The antenna device has a length substantially equal to the length of the opening of the corner reflector, and a conductor member having a height from the metal ground plate of 1/4 to 1/12 of the used wavelength is attached.

According to a sixth aspect of the present invention, in a monopole antenna with a corner reflector having a metal base plate, a rod-shaped exciter erected on the metal base plate, and a corner reflector, both ends of the corner reflector opening are provided. On the metal ground plane on the connecting line, the height from the metal ground plane is 1/4 of the operating wavelength.
1/12 conductor members on both sides of the corner reflector centerline so that the gap between the members is 1/10 or more of the operating wavelength and about 1/3 or less of the length of the corner reflector opening. It is an antenna device arranged in.

According to a seventh aspect of the present invention, in the antenna device according to any one of the fourth to sixth aspects, the conductor member is provided at the most end of the metal base plate. The invention according to claim 8 is the antenna device according to any one of claims 1 to 6, wherein the surface of the conductor member facing the exciter forms an angle of about 135 ° with the metal base plate.
It is configured so that

According to a ninth aspect of the present invention, in the antenna device according to any one of the first to sixth aspects, the angle formed by the surface of the conductor member facing the exciter and the metal base plate is approximately:
It is configured to be 45 °.

According to a tenth aspect of the present invention, a plurality of the corner reflector antenna devices according to any one of the fourth to ninth aspects are provided on a metal base plate so that the opening of the corner reflector faces outward. The antenna device is arranged and equipped with a selection switch so that any one of the plurality of antenna devices is selected by the selection switch.

According to an eleventh aspect of the present invention, a plurality of corner reflector antenna devices are arranged on a metal base plate so that the opening portions of the corner reflectors face outward, and the corner reflector antenna devices are covered with a radome, so that the opening portions of the respective corner reflectors are covered. This is an antenna device in which a conductor plate or a conductor film having a height higher than that of a metal base plate is about 1/4 to 1/12 of a used wavelength is attached to an inner surface or an outer surface of a radome corresponding to at least a part.

[0026]

In the antenna device of the present invention, a small conductor member is provided on the metal ground plane near the exciter of the monopole antenna with metal ground plane. The electromagnetic wave radiated from the exciter in a substantially horizontal direction is reflected upward by the member of the conductor, so that the null point generated in the upward direction of the exciter disappears.

Further, since the height of the conductor member is sufficiently smaller than the wavelength used, the horizontal radiation is not extremely blocked. Therefore, it is possible to easily realize an antenna that does not cause a null directly above the exciter without impairing the characteristics of the main lobe.

Further, in a monopole antenna with a corner reflector in which a rod-shaped exciter and a corner reflector are provided on a metal ground plane, since a conductor member is arranged near the opening of the corner reflector, the excitation is performed similarly to the above. It is possible to eliminate the null point above the exciter by reflecting the horizontal electromagnetic wave from the exciter upward.

In this case as well, there is almost no effect on the radiation in the main lobe direction, but especially in the case where a conductor member having a shape cut near the center line of the corner is provided, there is no effect on the main lobe. It can be almost ignored.

The size of the conductor member, the distance from the exciter, the angle formed with the conductor ground plane, and the like differ depending on how the horizontal directional characteristics of the antenna and the intensity of electromagnetic waves at the top of the exciter are balanced. Therefore, it may be set appropriately so that a desired directional characteristic can be obtained within the range of values shown as the constituent requirements.

[0031]

1 is a diagram showing a first embodiment of the present invention and is a perspective view of an antenna device. In the figure, numeral 1 represents an exciter, 2a represents a metal base plate, and 3 represents a conductor member made of metal pins.

As shown in the figure, the metal base plate 2a of the present antenna has a circular shape, the exciter 1 is arranged in the center thereof, and a plurality of conductor members 3 are arranged on the circumference. There is. The length of the exciter 1 is about λ / 4, and the length of the member 3 of each conductor is about λ /.
It is set to 5. The radius of the metal base plate 2 is set to about λ / 2. Further, the conductor member 3 is set at about 120 ° with respect to the surface of the ground conductor 2a.

FIG. 2 is a diagram showing a second embodiment of the present invention and is a perspective view of an antenna device, in which numeral 1
Is an exciter, 2a is a metal base plate, and 4 is a tapered conductor member.

Also in the case of this embodiment, the metal base plate 2a is circular and the exciter 1 is arranged at the center thereof as in the previous embodiment. The conductor member 4 has a taper, and the angle formed by the conductor member 4 and the metal base plate is set to about 135 °.

FIG. 3 is a diagram showing a third embodiment of the present invention, in which (a) is a perspective view and (b) is a plan view.
Reference numeral 1 is an exciter, 2b is a metal base plate, 5 is a conductor member made of a metal pin, and 6 is a corner reflector.

4A and 4B are views showing a fourth embodiment of the present invention. FIG. 4A is a perspective view, FIG. 4B is a plan view, and reference numerals 1, 2b and 6 are shown in FIG. Similarly, 7 is a conductor member made of metal having an L-shaped cross section.

In this embodiment, the length (height) of the exciter 1 is λ / 4, the height h of the corner reflector 6 is λ / 3,
The length R of one side of the corner reflector 6 is λ / 2, the angle α of the corner reflector is 30 °, and the height of the conductor member 7 is λ /.
The radiation directivity in the vertical plane in the case of 5 is shown in FIG.

In the figure, numeral 8 indicates a main lobe, 9 and 10 indicate side lobes, and 11 indicates a back lobe. In the figure, the gain at θ = 0 ° is about −5 dBi, and it can be seen that the null as shown in FIG. 18 described above does not appear.

6A and 6B are views showing a fifth embodiment of the present invention. FIG. 6A is a perspective view and FIG. 6B is a plan view. Similarly, 12
Reference characters a and 12b represent conductor members.

The conductor member of this embodiment is a strip-shaped member made of a metal plate, and its width (height from the metal base plate) is approximately λ / 5, and it is divided into two parts 12a and 12b. And is disposed so as to avoid the center line of the corner reflector. The length of this opening (the part where the conductor member is cut off) is approximately 1/3 of the corner reflector opening.

The radiation directivity (analyzed by the method of moments) in the vertical plane (in the XZ plane) is shown when the dimensions of each part other than the conductor members of this embodiment are the same as those of the embodiment of FIG. 7
Shown in In the figure, numeral 13 is a main lobe,
Reference numeral 14 is a side lobe, and 15 is a back lobe.

FIGS. 8A and 8B are views showing a sixth embodiment of the present invention. FIG. 8A is a perspective view and FIG. 8B is a plan view. The reference numerals 1, 2b and 6 are shown in FIG. Similar to FIG. 6, reference numeral 15 represents a conductor member. In this embodiment, the conductor member 15 is the metal base plate 2 on the opening side of the reflector 6.
It is attached to the end of b.

FIG. 9 is a diagram showing a seventh embodiment of the present invention. The reference numerals 1, 2B and 6 are the same as those in FIGS. 4 and 8, and 15 is a conductor member. The conductor member of the present embodiment is a band-shaped member made of a metal plate, and its width (height from the metal base plate) is approximately λ / 5, and the end portion of the metal base plate 2b in the opening direction of the corner reflector. It is installed in.

The conductor member 16 is attached so as to be inclined to the outside of the metal base plate so as to form an angle of about 135 ° with the metal base plate. FIG. 10 shows the radiation directivity (analyzed using the method of moments) in the vertical plane (in the XZ plane) when the dimensions of each part other than the conductor members of this embodiment are the same as those of the embodiment of FIG.

In the figure, numeral 17 indicates a main lobe, 18 and 19 indicate side lobes, and 20 indicates a back lobe. As in the embodiment shown in FIG. 4, when the member of the conductor of the metal plate is not tilted, its radiation directivity characteristic is shown in FIG.
As shown in Fig. 1, the side lobe level is large and the difference from the main lobe is about 5 dBi, whereas in the present embodiment, the member of the conductor of the metal plate is inclined by 135 °.
As shown in 0, it is possible to reduce the side lobe.

FIG. 11 is a view showing an eighth embodiment of the present invention, in which the reference numerals 1, 2b and 6 are the same as those in FIGS. 4 and 9, and 21 is a conductor member made of a metal plate. (The width in the short side direction is about λ / 5). In this embodiment, the conductor member 21 is attached to the end of the metal base plate 2b on the opening side of the reflector 6 while being inclined inwardly at an angle of about 45 ° with the metal base plate 2b.

FIG. 1 shows the radiation directivity (analyzed by the method of moments) in the vertical plane (in the XZ plane) when the dimensions of each part other than the conductor members of this embodiment are the same as those in the embodiment of FIG.
It is shown in FIG.

In the figure, numeral 22 indicates a main lobe, 23 indicates a side lobe, and 24 indicates a back lobe. As can be seen from the figure, in the embodiment shown in FIG. 11, the radiation directivity pattern shape can be approximated to the ideal beam, that is, the cosecant square beam.

13A and 13B are views showing a ninth embodiment of the present invention, in which FIG. 13A is a plan view and FIG. 13B is a sectional view. The figure shows an example in which the antenna is divided into two parts, arranged in an array, and an antenna changeover switch is arranged in the central portion thereof.

In the figure, numeral 1 is an exciter, 2c.
Is a metal base plate, 25 is a conductor member, 26 is a corner reflector, and 27 is a changeover switch. This antenna device operates so as to obtain a desired beam by selecting and switching the exciter 1 of each sector with the changeover switch 27.

Also in this embodiment, the effect of the conductor member 25 does not cause a null point in the upper part of the antenna.
14A and 14B are views showing a tenth embodiment of the present invention, showing an antenna having a radome, wherein FIG. 14A is a perspective view with a part of the radome cut away, and FIG. 14B is a cross section of only the radome. The figure is shown.

In the figure, numeral 1 indicates an exciter and 2d.
Is a metal base plate, 28 is a radome, 29 is a corner reflector, 30 is a changeover switch, and 31 is a conductor member. In this embodiment, a metal plate or a metal vapor deposition film attached to a radome is used as the conductor member 31 for preventing a null point from being formed above the antenna. for that reason,
The conductor member can be easily arranged, and the metal base plate can be easily angled.

In the above embodiment, the shape of the conductor member is cylindrical, angled, strip-shaped, etc., but the present invention is not limited to this, and the shape of the conductor member is triangular or quadrilateral, or Anything such as a cone or a triangular pyramid can be used.

[0054]

As described above, according to the antenna device of the present invention, the null point above the exciter can be eliminated in the monopole antenna with the metal ground plane and the monopole antenna with the corner reflector with the metal ground plane. it can.

In a device such as a wireless LAN, when a device having a small vertical tilt angle of the antenna of several tens of degrees is grounded for communication between the ceiling and the desk, a device on the desk is placed directly below the device on the ceiling. Communication is possible even when placed. Therefore, the present invention has the advantages that the dead area can be reduced and that the space utilization rate can be improved by eliminating the restrictions on the installation location of the device.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a second embodiment of the present invention.

FIG. 3 is a diagram showing a third embodiment of the present invention.

FIG. 4 is a diagram showing a fourth embodiment of the present invention.

FIG. 5 is a diagram showing radiation directivity in a vertical plane of the fourth embodiment.

FIG. 6 is a diagram showing a fifth embodiment of the present invention.

FIG. 7 is a diagram showing radiation directivity in a vertical plane of the fifth embodiment.

FIG. 8 is a diagram showing a sixth embodiment of the present invention.

FIG. 9 is a diagram showing a seventh embodiment of the present invention.

FIG. 10 is a diagram showing radiation directivity in a vertical plane of the seventh embodiment.

FIG. 11 is a diagram showing an eighth embodiment of the present invention.

FIG. 12 is a diagram showing radiation directivity in a vertical plane of the eighth embodiment.

FIG. 13 is a diagram showing a ninth embodiment of the present invention.

FIG. 14 is a diagram showing a tenth embodiment of the present invention.

FIG. 15 is a diagram showing an example of a conventional monopole antenna with a metal ground plane.

FIG. 16 is a diagram showing an example of radiation directivity in a vertical plane of a conventional antenna.

FIG. 17 is a diagram showing an example of a conventional monopole antenna with a corner reflector.

FIG. 18 is a diagram showing an example of a vertical in-plane radiation directivity of a conventional corner reflector antenna.

FIG. 19 is a diagram showing another example of a conventional antenna.

FIG. 20 is a diagram schematically showing a relationship between a base station antenna and a terminal antenna.

[Explanation of symbols]

1 Exciter 2a, 2b, 2c, 2d Metal base plate 3, 4, 5, 7, 12a, 12b, 15, 16, 21,
25,31 Conductor member 6,26,29 Corner reflector 8,13,22 Main lobe 9,10,14,18,19,23 Side lobe 11,15,20,24 Back lobe 27,30 Changeover switch 28 Radome

Claims (11)

[Claims] 1. A monopole antenna with a metal ground plate, comprising a metal ground plate and a rod-shaped exciter provided upright on the metal ground plate, wherein the surface of the metal ground plate on which the exciter is present is on the metal ground plate. At a position approximately 1/2 to 1/4 of the wavelength used from the exciter,
An antenna device, wherein at least one conductor member having a height from a metal ground plane of 1/4 to 1/12 of a used wavelength is provided. 2. A monopole antenna with a metal ground plate, which comprises a metal ground plate and a rod-shaped exciter provided upright on the metal ground plate, wherein the surface of the metal ground plate on which the exciter is present is on the metal ground plate. The height from the metal base plate is 1/4 of the working wavelength on a circle with the exciter as the center and the radius of which is approximately 1/2 to 1/4 of the working wavelength.
An antenna device comprising a plurality of conductor members of 1/12. 3. A monopole antenna with a metal ground plane composed of a metal ground plane and a rod-shaped exciter provided upright on the metal ground plane, wherein the radius is approximately 1/2 to 1/4 of the usable wavelength, and the width is Is attached to the side of the metal base plate where the exciter is present so that the center of the ring-shaped member is 1/4 to 1/12 of the wavelength used. Antenna device. 4. A monopole antenna with a corner reflector having a metal base plate, a rod-shaped exciter provided upright on the metal base plate, and a corner reflector, wherein a metal base plate is provided on the metal base plate near an opening of the corner reflector. An antenna device comprising at least one rod-shaped conductor member having a height from 1/4 to 1/12 of a used wavelength. 5. A monopole antenna with a corner reflector having a metal base plate, a rod-shaped exciter standing upright on the metal base plate, and a corner reflector, wherein a length is provided on the metal base plate at the opening of the corner reflector. An antenna device, wherein a conductor member having a length substantially equal to the opening of the corner reflector and having a height from a metal ground plate of 1/4 to 1/12 of a used wavelength is attached. 6. A monopole antenna with a corner reflector having a metal base plate, a rod-shaped exciter erected on the metal base plate, and a corner reflector, wherein the metal base plate is on a line connecting both ends of the opening of the corner reflector. Above, the height from the metal ground plane is 1/4 to 1 / of the wavelength used.
The 12 conductor members are arranged on both sides of the center line of the corner reflector so that the gap between the members is 1/10 or more of the wavelength used and about 1/3 or less of the length of the opening of the corner reflector. An antenna device characterized by being installed. 7. The antenna device according to claim 4, wherein the conductor member is provided at the end of the metal base plate. 8. The antenna device according to claim 1, wherein the surface of the conductor member facing the exciter makes an angle of about 135 ° with the metal base plate. 9. The antenna device according to claim 1, wherein the surface of the conductor member facing the exciter forms an angle of about 45 ° with the metal base plate. 10. A plurality of corner reflector antenna devices according to any one of claims 4 to 9 are arranged on a metal base plate so that an opening of the corner reflector faces outward. An antenna device comprising a selection switch, wherein any one of the plurality of antenna devices is selected by the selection switch. 11. A plurality of corner reflector antenna devices are arranged on a metal base plate so that the opening portions of the corner reflectors face outward and are covered with a radome, and correspond to at least a part of the opening portions of each corner reflector. An antenna device characterized in that a conductor plate or a conductor film having a height higher than that of a metal base plate is about 1/4 to 1/12 of a used wavelength is attached to an inner surface or an outer surface of the radome.