JP3353218B2 - Antenna device - Google Patents

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, and more particularly to a directivity having a tilt beam on a vertical plane and a fan beam on a horizontal plane, and having a high gain. The present invention relates to an antenna device for a small-sized wireless LAN terminal which can suppress a multiplex wave by suppressing the height of the antenna, realizing it with a small and light antenna, and realizing it regardless of the shape of the antenna device.

[0002]

2. Description of the Related Art An antenna for a base station device used for a private wireless LAN or the like is installed on an indoor ceiling or the like, and an antenna for a terminal device is installed on a desk or a personal computer or workstation on a desk. .

[0003] The transmission speed is 10 Mb such as a wireless LAN.
In high-speed wireless communication such as exceeding ps, an antenna having a high directivity and a high gain is required. On the other hand, it is desirable that the terminal device be capable of directing the beam in all directions of 360 ° in the horizontal plane so that the base station can receive radio waves in any direction.

As an antenna for realizing this, an antenna in which a ground plane of a conductor as shown in FIG. 7 is divided into a plurality of sectors and a three-dimensional corner reflector antenna having a sector beam for each sector is installed.

FIG. 7A is a schematic view, and FIG. 7B is a top view (X
(Y plane) and (c) are side views (XZ plane). In FIG. 7, 1 is a radiation element, 2 is a reflector, 3 is a conductor ground plane, 4 is an antenna changeover switch, and 5 is a height h of a corner reflector.
r and 6 are the length lr of the reflection plate, 8 is the diameter 2s of the space for accommodating the 4 antenna changeover switches, X, Y and Z are orthogonal coordinates, and θ and φ are spherical coordinates. FIG. 7 shows an example in which the number of sectors is 12, and the antenna device in each sector has three ground planes and two radiating elements on both sides.
Operates as a three-dimensional corner reflector antenna. This antenna performs an operation of searching for the direction of arrival of a radio wave at the reception level when performing communication first, and switching to the antenna of the sector used by the antenna changeover switch. In such an antenna, the radiation directivity in the vertical plane is such that the gain is high when the value of θ is in the range of 0 ° or more and 90 ° or less, and the radiation in the other range becomes close to null. As for, it is required that the side lobe and the back lobe be small and the beam width be a value obtained by dividing 360 ° by the number of sectors.

FIG. 8 shows an antenna device in which a part of the conventional 12-sector three-dimensional corner reflector shown in FIG. 8, 1 is a radiating element, 2 is a reflector, 3 is a ground plane of a conductor, 5 is a height hr of the reflector, 6 is a length lr of the reflector, 7 is a corner angle α, 9
Denotes a value s which is a half of 2s shown in FIG. 7, 14 denotes an interval dr between the reflector and the radiating element behind the radiating element, X, Y, and Z denote orthogonal coordinates, and θ and φ denote spherical coordinates.

Here, the length lr of the reflector 6 is 2λ (λ is the wavelength of the reference frequency f ₀ ), the corner angle α of 7 is 30 °, 9
FIG. 9 shows the radiation directivity when s is 2λ and the height hr of the reflector is 0.6λ. At this time, the radiation directivity in the horizontal plane is 3 dB beam width 42 ° as shown in FIG.
9 and the radiation directivity in the vertical plane is shown in FIG.
As shown in (b), the tilt angle is 26 ° and the beam width is 3 dB.
2 °. It is assumed that 12 antennas are used side by side in the circumferential direction. At this time, since the 3 dB beam width of the radiation directivity in the desired horizontal plane is 30 °, the beam width is 12 ° wider than the desired value. I have.

In order to change the beam width of the antenna device, it is necessary to increase the height hr of the reflector and the corner length lr. However, if s is reduced, space for installing an antenna changeover switch, a power supply line, and a connector cannot be obtained, and there is no other way but to increase lr or hr without changing s. As a result, the physical size of the antenna is reduced. There was a drawback that cannot be reduced.

On the other hand, a conventional antenna using metal plate fins or fins is a multi-mode conical horn (Ohm, Antenna Engineering Handbook, p. 165). However, this antenna has a different structure from the case where metal plate fins are installed on the three-dimensional corner reflector, and the purpose is to increase the beam width in the horizontal plane to share polarization. This is different from the purpose of reducing the size of the antenna and increasing the gain. Although there is an example of using a dielectric as a method of controlling an electromagnetic field (Ohm: Antenna Engineering Handbook p. 165), a special bonding method is used to bond a dielectric such as Teflon to a metal such as copper. However, there is a drawback that it is difficult to manufacture an antenna at low cost.

FIG. 11 shows an example in which a conventional sectorized three-dimensional corner reflector antenna device is installed on a rectangular ground plate. In FIG. 11, 1 is a radiation element, 2 is a reflector, 4 is an antenna changeover switch, and 15 is a rectangular ground plane. As shown in the figure, each sector is given a number in a counterclockwise direction, with the sector on the short side of the main plate as 1. The antenna device having such a structure is usually affected by a metallic ground plate and a housing as shown in FIG. FIG. 12 shows characteristics of the conventional antenna device shown in FIG. FIG.
Is a graph based on measurement data showing a 3 dB beam width of radiation directivity in a conical surface for each sector. Here, the height hr of the reflector is 1.2 wavelength, and the length lr of the reflector is 3.1.
The wavelength and the radius s of the antenna changeover switch are 1.5 wavelengths. Here, the size of the rectangular base plate is 10 wavelengths on the short side and 12 wavelengths on the long side. Sectors 11 and 3 with long edges of the base plate have a 3 dB beam width of 34 ° in the conical plane.
However, the beam widths of the sectors 12, 1 and 2 having a short base plate edge are changed from 37 ° to 38 °, and there is a difference of 4 °. As described above, the conventional sectorized three-dimensional corner reflector antenna device has a disadvantage that the antenna characteristics cannot be made the same in all sectors because of the influence of the metal ground plate and the housing.

[0011]

As described above, the only way to obtain a high gain by using the conventional three-dimensional corner reflector antenna is to increase the height of the reflector and the length of the reflector to increase the aperture area. However, this has the disadvantage that the antenna cannot be made smaller. Further, as described above, the conventional sectorized three-dimensional corner reflector antenna apparatus has a disadvantage that the antenna characteristics cannot be made the same in all sectors because of being affected by the metal ground plate and the housing.

The present invention has been made to solve the above-mentioned problems by an inexpensive method without increasing the number of manufacturing steps as much as possible. Related to the reduction of

[0013]

The features of the present invention for solving the above-mentioned problems include: a ground plane having at least a surface of a conductor; and at least one radiating element formed on the ground plane.
In the three-dimensional corner reflector antenna device in which three surfaces on both sides and a rear side of the radiating element are formed by conductive reflecting plates, at least one of the above-mentioned reflecting plates is provided on one of the reflecting plates on both sides of the radiating element. Is located on the antenna device to which the conductor fin is attached.

Preferably, the above-mentioned fins are arranged in parallel with each other, and the fins arranged in parallel are arranged so as to be parallel to the above-mentioned ground plane and at right angles to the respective reflection plates beside the radiating element. I do.

Preferably, the fins are metal plates, and the fins are arranged in parallel with each other, and the fins arranged in parallel with each other are perpendicular to the ground plate and to each of the reflectors beside the radiating element. Arrange them at right angles.

[0016] Preferably, a plurality of antennas are radially arranged in a circular shape, and two adjacent antenna devices have a single reflector common to the two antenna devices, and a switch for selecting one of the antenna devices is provided. The switch is located at the center of the radially arranged antenna device.

Preferably, when the distance from each radiating element of the plurality of antenna devices to the end of the base plate differs depending on the antenna device, the number of fins is increased when the distance is short according to the distance. , The number of metal fins is reduced.

Preferably, when the distance from each radiating element of the plurality of antenna devices to the end of the ground plate differs depending on the antenna device, at least one of the width and the length of the fin when the distance is short according to the distance. And the width and length of the fins are made smaller as the distance becomes longer.

Preferably, the ground plate, the reflector and the fin are integrally formed of the same metal.

According to the present invention, because of the above-described structure, the electric field that stands vertically from the ground plane of the conductor is reflected and diffracted by the fin formed by the metal plate attached to the metal reflection plate. For this reason, the fin of the metal plate has a function of controlling the electromagnetic field distribution on the three-dimensional corner reflector. The electromagnetic field changes depending on the number and arrangement of the fins.

[0021]

FIG. 1 shows a first embodiment of a three-dimensional corner reflector antenna device with metal fins (that is, fins) according to the present invention. 1A is a schematic view, FIG. 1B is a top view (XY plane), and FIG. 1C is a side view (XZ plane). FIG. 1 shows an example in which two metal fins (fins) are used for one reflector. In FIG. 1, 1 is a radiating element, 2 is a reflecting plate, 3 is a ground plane of a conductor, and 5 is a reflecting plate. The plate height hr, 6 is the length lr of the reflection plate, 7 is the corner angle α, 9 is a value s which is half of 2s shown in FIG. 7, 10 is a metal fin, 11 is a metal fin. ) Width t, 12 is the length r of the metal fin, 14 is the distance dr between the reflector and the radiating element behind the radiating element, X, Y, and Z are orthogonal coordinates, and θ and φ are spherical coordinates. . Fins 10 are sometimes referred to herein as fins. The antenna device operates as a three-dimensional corner reflector antenna by three ground plates and two reflectors on both sides of the excitation element, and ten metal fins function to change the distribution of the electric field. FIG. 2 shows the radiation directivity of an antenna device when a metal fin is used for an antenna device having the same dimensions as that of FIG. 8 shown by a conventional three-dimensional corner reflector. Here, the length lr of the reflector 6 is 2λ (λ is the wavelength of the reference frequency f ₀ ), the corner angle α of 7 is 30 °, the s of 9 is 2λ, and the height hr of the reflector 5 is 0. 6 λ, 10 metal fins are provided for each reflector, 11 metal fins have a width t of 0.2 λ, 12 metal fins have a length r of 1 λ, and a space between the reflector and the radiating element behind the radiating element of 14. dr is set to 0.4λ. At this time, the radiation directivity in the horizontal plane is as shown in FIG.
As shown in FIG. 9B, the beam becomes a sector beam having a 3 dB beam width of 36 °, which is 3 times smaller than the case where there is no metal fin shown in FIG.
It can be seen that the dB beam width is reduced by 6 °. On the other hand, the radiation directivity in the vertical plane has a tilt angle of 26 ° and a 3 dB beam width of 34 ° as shown in FIG. In other words, the three-dimensional corner reflector antenna with metal fins of the present invention has a beam width of only the radiation directivity in the horizontal plane without substantially changing the shape and tilt angle of the radiation directivity in the vertical plane due to the effect of electromagnetic field distribution control by the metal fins. It can be seen that can be sharpened.

FIG. 3 shows a second embodiment of the present invention, in which the number of metal fins per reflector is five. In FIG. 3, 1 is a radiation element, 2 is a reflector, 3 is a ground plane of a conductor, 5 is a height hr of the reflector, and 6 is a length l of the reflector.
r and 7 are corner angles α, 9 is a half value 2s of 2s shown in FIG. 7 s, 10 is a metal fin, 11 is a width t of a metal fin, 12 is a length r of a metal fin, and 14 is a position behind a radiating element. The distances dr, X, Y, and Z between the reflector and the radiating element indicate orthogonal coordinates, and θ and φ indicate spherical coordinates.

Here, the length lr of the reflector is 2λ (λ is the wavelength of the reference frequency f ₀ ), the corner angle α is 30 °, the width of the reflector behind the radiating element is 1λ, and the height of the reflector is 0. 0.6λ, and the distance between the reflector and the radiating element is 0.4λ. FIG. 9 shows a conventional three-dimensional corner reflector, and the antenna device of the present invention has two metal fins. As shown in FIG. Here, the length lr of the reflecting plate of 6
(Λ is the wavelength of the reference frequency f ₀ ), and the corner angle α of 7
Is 30 °, 9 s is 2λ, and height of the reflector 5 hr is 0.
6λ, 10 metal fins for each reflector, 5 pieces, 11
The width t of the metal fin is 0.2λ, and the length r of the 12 metal fins is
Is 1λ, the spacing dr between the reflector behind the radiating element and the radiating element is 0.4λ. At this time, the radiation directivity in the horizontal plane is 3 dB beam width 32 ° as shown in FIG.
The vertical direction radiation pattern is shown in FIG.
As shown in (b), the tilt angle is 26 ° and the beam width is 3 dB.
6 °. In other words, the antenna device of the present invention using five metal fins can make the 3 dB beam width of the radiation directivity in the horizontal plane approximately equal to the desired 30 °, and almost change the shape and tilt angle of the radiation directivity in the vertical plane. There is no.

FIG. 5 shows a third embodiment of the antenna of the present invention in which the antenna of the present invention is arranged in the circumferential direction. In FIG. 5, reference numeral 1 denotes a radiating element, 2 denotes a reflector, 3 denotes a ground plane of a conductor, 4 denotes an antenna changeover switch, 8 denotes a diameter 2s of a space for accommodating the switch of 4, and 10 denotes a metal fin. This antenna can reduce the horizontal beam width by controlling the electromagnetic field radiated from the radiating element 1 with ten metal fins without changing the height and the ground plane diameter at all from the conventional antenna of FIG. Further, in this antenna, since the reflectors 2, the ground plate 3, and the metal fins 10 are all conductors, if the antenna device is manufactured using the same metal by a casting method or a shaving method, soldering can be performed. It is possible to reduce the labor and mass-production at low cost.

FIG. 6 shows a change in gain due to the installation of the metal fins of the present antenna. In FIG. 6, the horizontal axis represents the number of metal fins, and the vertical axis represents gain. Here, the antenna structures are the same as those in FIGS. 8, 1, and 3, respectively. In a conventional antenna device without metal fins, the gain was about 11.5 dBi, whereas when the number of fins was five, the gain became 13 dBi or more and the gain was 1.5 dB due to the effect of the metal fins.
The above can be confirmed.

FIG. 10 is a view showing a fourth embodiment of the antenna device according to the present invention. In FIG. 10, 1 is a radiating element, 2
Is a reflector plate, 4 is an antenna changeover switch, 15 is a rectangular ground plate, 16 is a 5-layer metal fin, 17 is a 2-layer metal fin, and 18 is a metal fin perpendicular to both the ground plate and the reflector. Each sector is given a number in the counterclockwise direction, with the sector having a short side of the base plate as 1 as shown in FIG. In this antenna device, the antenna has the same characteristics for each sector by changing the structure of the metal fins according to the distance from the radiating element to the edge of the ground plane. That is, by providing five stages of metal fins in the sectors 1 and 7 where the edge of the ground plate is the shortest, sharp directivity can be obtained even if the reflector or the ground plate is short. Next, the number of metal fins in two sectors, sector 2, sector 6, sector 8, and sector 12, which are slightly longer than the ground plate, are set. Furthermore, the metal fins are not provided in the sectors 4 and 10 in which the distance to the ground plane is long. Sectors 3, 5, 9, 1 where the distance to the ground plane is the longest
As for 1, the directivity of the vertical plane is too sharp. For this reason, a metal fin 18 perpendicular to both the base plate and the reflector is installed near the edge of the base plate, and by utilizing the reflection and scattering of radio waves, this is controlled to be the same as other sectors. I have.

As described above, the means for changing the structure of the metal fins in accordance with the length to the edge of the base plate can use not only the number of metal fins but also the length and width of the metal fins. It goes without saying that even if the shape of the base plate or the ratio of the length and width of the rectangle changes, similar effects can be obtained by using metal fins according to the change.

The antenna device according to the present invention has a three-dimensional corner reflector having a corner length, a corner height, an antenna switch storage space of 2 s, a ground plate size, a metal fin width t, and a length r.
Needless to say, it is effective even if changes.

It goes without saying that the antenna device of the present invention is effective even if the arrangement of the metal fins is changed.

[0030]

As described above, the antenna of the present structure has a sharper directivity in the horizontal plane than the conventional three-dimensional corner reflector of the same size by using the control of the electromagnetic field distribution by the metal fin, and has a higher directivity. It is possible to gain. In addition, as a method of manufacturing the antenna having the present structure, it is conceivable to mass-produce the metal fin reflectors and ground plates for all sectors by using a mold. For this reason, compared with the case where the dielectric is attached to the three-dimensional corner reflector by a special bonding method,
The process for adjusting the antenna is reduced, and the antenna can be manufactured at low cost. Further, according to the antenna device of the present invention, the number of metal fins, the length, and the width of each metal fin for each sector are appropriately determined, thereby realizing an antenna device in which variations between sectors are eliminated.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing the radiation directivity of the first embodiment of the antenna device of the present invention.

FIG. 3 is a diagram showing a second embodiment of the antenna device of the present invention.

FIG. 4 is a diagram showing the radiation directivity of a second embodiment of the antenna device of the present invention.

FIG. 5 is a diagram showing a third embodiment of the antenna device of the present invention.

FIG. 6 is a diagram showing the effect of the antenna device of the present invention.

FIG. 7 is a diagram showing a conventional antenna device.

FIG. 8 is a diagram showing a conventional antenna device.

FIG. 9 is a diagram showing radiation directivity of a conventional antenna device.

FIG. 10 is a diagram showing a fourth embodiment of the antenna device of the present invention.

FIG. 11 is a diagram showing an example of a conventional antenna device.

FIG. 12 is a diagram illustrating antenna characteristics of a conventional antenna device.

[Explanation of symbols]

 X, Y, Z Cartesian coordinates θ, φ Spherical coordinates 1 Radiating element 2 Reflector 3 Ground plane 4 Antenna switch 5 Reflector height hr 6 Reflector length lr 7 Corner angle α 8 Switch storage space diameter 2s 9 Switch storage space radius s 10 Metal fin 11 Metal fin width t 12 Metal fin length r 13 Tilt angle β 14 Spacing between radiating element and reflector dr 15 Rectangular ground plane 16 Five-layer metal fin 17 Two-layer metal fin Metal fins 18 Metal fins perpendicular to both the base plate and the reflector

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01Q 21/20

Claims (7)

(57) [Claims] At least one surface is constituted by a ground plane of a conductor, at least one radiating element formed on the ground plane, and three surfaces on both sides and a rear side of the radiating element are formed by a reflector of a conductor. In a three-dimensional corner reflector antenna device, at least one of the above-mentioned reflectors, on both sides of a radiation element, is provided with a conductor fin. 2. The antenna device according to claim 1, wherein:
The above-mentioned fins are arranged in parallel with each other, and the fins arranged in parallel are arranged so as to be parallel to the ground plate and at right angles to each of the reflectors beside the radiating element. Antenna device. 3. The antenna device according to claim 1, wherein:
The above-mentioned fins are arranged in parallel with each other with a metal plate, and the fins arranged in parallel are arranged so as to be perpendicular to the above-mentioned base plate and perpendicular to each of the reflectors beside the radiating element. An antenna device characterized in that: 4. The antenna device according to claim 1, wherein a plurality of antenna devices according to claim 1 are radially arranged in a circle, and two adjacent antenna devices have a single reflector common to the two antenna devices. An antenna device characterized in that a changeover switch for selecting one of the above is disposed at the center of the radially arranged antenna device. 5. The antenna device according to claim 4, wherein a distance from each radiating element of the plurality of antenna devices to an end of the base plate differs depending on the antenna device.
An antenna device according to the distance, wherein the number of fins is increased when the distance is short, and the number of metal fins is decreased as the distance increases. 6. The antenna device according to claim 4, wherein a distance from each of the radiating elements of the plurality of antenna devices to an end of the ground plane differs depending on the antenna device. An antenna device characterized in that at least one of the width and the length of a fin is increased when the distance is short, and the width and the length of the fin are reduced as the distance increases, according to the distance. 7. The antenna device according to claim 1, wherein the ground plate, the reflection plate, and the fin are integrally formed of the same metal.