JPH10135732A - Slave unit antenna for indoor radio lan - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep almost even signal intensity higher than a a fixed level for a master unit antenna by preparing a plane antenna and to secure an asymmetrical angle distribution of radiation intensity of the beams radiated through the antenna surface against the direction vertical to the antenna surface. SOLUTION: A slave unit antenna 1 has a planar shape, and the angle distribution of radiation intensity measured in the vertical direction of a plane is asymmetrical to the direction 5 vertical to the antenna surface. The antenna 1 is composed of a patch antenna consisting of 64 (8 rows × 8 columns) radiation conductors. The decree of asymmetry of the radiation intensity of the antenna 1 is decided by the cell size of a master unit antenna 3. If the cell size is small, the degree of asymmetry of the radiation intensity is decreased. Thus, it's possible to increase the range of radiation while securing the satisfactory radiation intensity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless LAN used for wireless communication between computers in a room such as an office.
More particularly, the present invention relates to a wireless LAN slave unit antenna suitable for high-quality and high-speed communication.

[0002]

2. Description of the Related Art An antenna of a wireless LAN used for wireless communication between computers in a room such as an office is disclosed in Japanese Patent Application Laid-Open No. 5-304526, entitled "Network device in premises". FIG. 14 shows the angular distribution of the radiation intensity of the antenna for the slave unit of the indoor wireless LAN according to the related art. The handset antenna 8 is designed to have the strongest radiation intensity in the direction 5 perpendicular to the antenna surface, and the angular distribution of the radiation intensity of the beam is substantially symmetric with respect to the direction 5 perpendicular to the antenna surface. I have. A plurality of such slave unit antennas 8 are provided for one master unit antenna, and as shown in FIG. 15, a certain distance diagonally below the master unit antenna 3 installed on the ceiling 4. It was usual to be installed and used separately.

[0003]

[0004] For the purpose of performing broadband communication by increasing the speed of wireless transmission, 2.4 is conventionally used.
An indoor wireless LAN is configured using a quasi-millimeter wave or a millimeter wave, which is a higher frequency, instead of a microwave of about GHz. A quasi-millimeter wave or a millimeter wave has a strong linearity and cannot be expected to propagate by radio wave diffraction as compared with a microwave.

For this reason, as shown in FIG. 15, when a signal in a quasi-millimeter wave or millimeter wave band is radiated from a slave unit antenna 8 having a radiation characteristic as shown in FIG. In the base unit antenna 3, the radiation intensity distribution is asymmetric with respect to the direction 5 perpendicular to the antenna surface. In particular, the radiation intensity of the beam farther from the handset antenna 8 is such that the spread of radio waves is large, so that the signal incident on the base unit antenna 3 provided on the ceiling 4 is weak, and as a result, the bit due to the decrease in the received power is reduced. There is a problem such as an increase in an error rate, and a problem that communication quality is significantly deteriorated.

[0005] Conventional methods for solving this problem include:
There are two methods, one is to increase the transmission power and the other is to reduce the radius of the cell.The former requires an increase in the power consumption of the device and the necessity of using a component capable of handling a higher power in the transmission amplifier. There is a problem that becomes more expensive. In the latter case, it is necessary to divide the office having the same area into more cells, so that the number of base unit antennas increases and the system configuration becomes complicated.

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide an antenna for a wireless LAN slave unit suitable for high-quality and high-speed communication.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an antenna for a slave unit of an indoor wireless LAN, which has a planar antenna surface and an angular distribution of radiation intensity of a beam radiated from the antenna surface. This can be achieved by a handset antenna having an antenna that is asymmetric with respect to a direction perpendicular to the plane.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments. FIG. 1 is a diagram showing an angular distribution of radiation intensity of an antenna 1 for a slave unit of an indoor wireless LAN according to the first embodiment of the present invention. The slave unit antenna 1 is attached to a movable shaft 2. The slave unit antenna 1 has a planar shape,
The angular distribution of the radiation intensity measured from the direction perpendicular to the plane of the slave unit antenna 1 is asymmetric with respect to the direction 5 perpendicular to the antenna surface as shown in FIG. 1 (hereinafter, the direction perpendicular to the antenna surface). For "wide angle side" and "narrow angle side"). If the cell of the indoor wireless LAN is within a circle having a radius of about 16 m around the base unit antenna 3, the angular distribution of the radiation intensity on the wide angle side is about 5 degrees in a -3 dB width, and the radiation intensity on the narrow angle side is Is preferably about 2 degrees.

FIG. 2 is a top view of the slave unit antenna. The slave unit antenna 1 is configured using a patch antenna 21 including a total of 64 radiation conductors 18 arranged in 8 rows and 8 columns. A specific configuration in the case of supporting a frequency of 40 GHz will be described. The patch antenna 21 has a three-layer structure, and is formed by laminating a ground layer and a dielectric layer from below, and laminating a conductor layer composed of the radiation conductor 18 and the wiring 20 on the top. In this embodiment, copper is used for the conductor layer and the ground layer, and a dielectric having a relative permittivity of 2.33 is used for the dielectric layer. The radiation conductor 18 has a square shape with one side of about 2.46 mm.

In the slave unit antenna 1 according to the present embodiment, the distance between the radiation conductors is set to about 0.6 so that the wavelength is about 0.9 wavelength (λ).
In order to make the angular distribution of the radiation intensity asymmetrical, and to supply a total of 32 radiation conductors existing in the first, second, seventh and eighth rows to other radiation conductors,
By changing the length of 0, power is supplied out of phase.

The spacing between the radiating conductors can be determined so that the coupling between the radiating conductors is made sufficiently small to radiate efficiently. If the distance between the radiation conductors is too large, the size of the antenna is unnecessarily increased. Generally, desirable characteristics can be obtained at 0.5 wavelength or more. Further, by changing the phase of the power supply, the electromagnetic waves from the radiation conductors interfere with each other, and a strengthening direction and a weakening direction are generated. Specifically, of the radiating conductors of eight rows in total, power is supplied to the center four columns at a fixed phase, and the first and second columns are advanced by 30 degrees with respect to the center four columns. By feeding eight rows with a phase delayed by 30 degrees, the angular distribution of the radiation intensity can be made asymmetric. The size of the phase to be shifted is
Desired characteristics can be given in the range of 5 degrees to 90 degrees.

The power supply to the patch antenna is performed by connecting to the wiring using the connector 14.

Thus, an antenna having the angular distribution of the radiation intensity shown in FIG. 3 can be realized. Although the angle is shown on the horizontal axis, the direction perpendicular to the antenna surface (the direction shown as 5 in FIG. 1) is shown as an angle of 0 degree.

The operating range and structure of the movable shaft 2 of the slave unit antenna 1 will be described with reference to FIGS. FIG. 4 shows an operating range of the movable shaft 2 of the slave unit antenna 1. The movable shaft 2 can freely move in a space 15 above a mounting surface 19 of the movable shaft 2 of a sphere whose length corresponds to a radius. FIG. 4 shows an example in which the mobile unit antenna 1 is oriented in several directions by the movable shaft 2 (4).
Example) is also shown. In this manner, the mobile unit antenna 1 can be freely oriented by the movable shaft 2, so that even when the installation location of the mobile unit antenna changes, the antenna surface can be appropriately directed to the main unit antenna. .

FIG. 5 shows the structure of the movable shaft 2. The movable shaft 17 is made of a non-metallic material having a bellows shape. Further, the movable shaft 17 has a structure in which a wiring 16 for feeding power to the slave unit antenna 1 through the connector 14 is passed through the inside thereof. It is needless to say that the wiring 16 and the movable shaft 17 may be provided separately, and the structure of the movable shaft is not limited to the bellows shape.

FIG. 6 shows the configuration of an indoor wireless LAN when the slave unit antenna 1 is used. The base unit antenna 3 is installed on a ceiling 4 having a height of 2.8 m from the floor 12, and the slave unit antenna 1 is installed on a desk 6 having a height of about 80 cm from the floor 12. The cell radius of the base unit antenna 3 is 16 m. Here, the handset antenna 1 has a narrow angle side (a side where the angular distribution of the radiation intensity is about 2 degrees) when the antenna surface is radiated toward the ceiling immediately above the cell boundary and the base unit antenna 3 side. And radiate radio waves with the antenna surface directed toward the base unit antenna 3. in this case,
The distribution of the radiation intensity of the radio wave from the slave unit antenna 1 at the location of the master unit antenna 3 becomes substantially symmetrical, and the radio wave of almost uniform intensity can be transmitted to the master unit antenna 3.

In this way, even when the slave unit antenna 1 is installed at the boundary between cells, sufficient radiation intensity can be obtained, so that the bit error rate can be reduced and the deterioration of communication quality can be improved as compared with the prior art. As a result, high-quality, high-speed communication can be stably realized over the entire area in the cell.

The above description has been made with reference to an example in which communication is performed using an electromagnetic wave in the millimeter wave band whose frequency is 40 GHz.
The same effect can be obtained by using a quasi-millimeter wave of z or more or a millimeter wave such as 60 GHz.

The degree to which the radiation intensity of the handset antenna is made asymmetric can be determined according to the size of the cell of the base station antenna 3. If the cell is small, by reducing the degree to which the radiation intensity is asymmetric, while ensuring sufficient radiation intensity,
The radiation range can be extended. FIG. 7 is a diagram showing the angular distribution of the radiation intensity of the handset antenna 7 in which the degree of asymmetry has been reduced. The slave unit antenna having such an angular distribution is suitable for an indoor wireless LAN in which the cell radius of the master unit antenna 3 is about 8 m. The angular distribution of the radiation intensity measured from the vertical direction of the antenna surface is about -3 dB width and about 3 on the narrow angle side.
The difference from the slave unit antenna 1 in FIG. 1 is that the degree and the wide angle side are set to about 5 degrees.

FIG. 8 shows the configuration of an indoor wireless LAN when the slave unit antenna 7 is used. The base unit antenna 3 is installed on a ceiling 4 having a height of 2.8 m from the floor 12, and the slave unit antenna 7 is installed on a desk 6 having a height of about 80 cm from the floor 12. Here, the slave unit antenna 7 has a narrow angle side (a side where the angular distribution of the radiation intensity is about 3 degrees) when the antenna surface is radiated toward the ceiling immediately above the cell boundary at the cell boundary, and the base unit antenna 3 side. And radiate radio waves with the antenna surface directed toward the base unit antenna 3. As a result, FIG.
As shown in the figure, the distribution of the radiation intensity of the radio wave from the slave unit antenna 7 at the location of the master unit antenna 3 is substantially symmetrical, that is, the radio wave of almost uniform intensity is transmitted to the master unit antenna 3. Can be.

In the above embodiment, the case where the radius of the cell is 16 m and 8 m has been described, but the radius of the cell is not limited to the numerical value. FIG. 9 shows the handset antenna 11.
When the height from the base unit antenna 3 to the base unit antenna 3 is 2 m, the radiation intensity of the base unit antenna 3 formed by the base unit antenna 11 installed at a distance L (m) from the base unit antenna 3 is determined. It is explanatory drawing of a distribution.

The slave unit antenna 11 is a slave unit antenna according to the present invention whose radiation intensity distribution is asymmetric with respect to a direction perpendicular to the antenna surface. The angle distribution on the wide angle side is 5 degrees, and the angle distribution on the narrow angle side is 1, 2, 3, and 5 degrees, respectively. When the antenna surface is radiated toward the ceiling directly above, the slave unit antenna 11 is installed such that the narrow angle side is on the master unit antenna 3 side, and the antenna surface is radiated toward the master unit antenna 3. . At this time, the radiation distribution changes depending on the angular distribution of the radiation intensity and the distance L as shown in FIG.

FIG. 10 shows the distance L dependence of the radiation distribution created on the base unit antenna 3 when the slave unit antenna 11 has the angular distribution of the radiation intensity shown in FIG.
As can be seen from FIG. 10, in order to obtain a radiation distribution on the antenna surface for the base unit that is substantially the same as the radiation distribution when the radiation intensity on the wide angle side is 5 degrees, the angle of the radiation intensity on the narrow angle side is required The distribution must be narrower than 5 degrees. Specifically, it can be said that it is desirable to set the angular distribution of the radiation intensity to about 3 degrees when the distance L is in the range of about 10 m, and 3 degrees or less when the distance L is 10 m or more.

In FIG. 11, the angle distribution of the radiation intensity on the wide angle side is 10 degrees, the angle distribution of the radiation intensity on the narrow angle side is 2, and
The case where it is set to 4, 6, and 10 degrees is shown. Similarly,
FIG. 12 shows that the angle distribution of the radiation intensity on the wide angle side is 15 degrees,
The angular distribution of the radiation intensity on the narrow angle side is 3, 6, 9 and 15
The case of degrees is shown. From these figures, it can be seen that the spread of the radiation intensity of the slave unit antenna depends on the radius of the indoor wireless LAN cell and the angular distribution of the radiation intensity of the slave unit antenna. When the radius of the cell is small, for example, about 5 m, the angular distribution of the radiation intensity on the wide angle side of the slave unit antenna is set to 15 degrees and the narrow angle side is set to 6 degrees, or
By setting the wide-angle side to 10 degrees and the narrow-angle side to 6 degrees, uniform radiation intensity can be obtained at the location of the base unit antenna 3. In general, it can be seen that the ratio of the angular distribution of the radiation intensity on the narrow angle side to the wide angle side should be about 3/5 or less. However, when there is too much difference in the angular distribution of the radiation intensity or when the angular distribution has an extremely small value, it becomes difficult to design the antenna. Therefore, the ratio of the angular distribution is set to 3/5 to 1/5. It is desirable to be about.

In the above description, the height from the slave unit antenna 11 to the master unit antenna 3 is 2 m, but the height is 2 m.
It is not limited to m. The angular distribution of the radiation intensity of the handset antenna can be determined according to the required cell radius, the height of the ceiling of the office, and the like.

FIG. 13 is a diagram showing another indoor wireless LAN system using the slave unit antenna of the present invention. FIG.
In, the base unit antenna 3 is installed not on the ceiling 4 but on a base 10 having a height of about 80 cm from a floor 12. The transmission / reception between the slave unit antenna 1 and the master unit antenna 3 is performed by using reflection at the ceiling 4. In general, the characteristics of the electromagnetic wave reflected by the ceiling 4 differ depending on the frequency of the electromagnetic wave, but in the quasi-millimeter wave or the millimeter wave, like the reflection of light,
Most of the energy propagates back toward the floor 12 by regular reflection where the angle of incidence and the angle of reflection are equal. Therefore, even if the base unit antenna 3 is provided on the floor 12 side of the indoor wireless LAN toward the ceiling 4, communication can be performed between the base unit antenna 3 and the slave unit antenna 1. In this indoor wireless LAN system, since the electromagnetic wave propagates by regular reflection, the height H obtained by adding the height from the slave unit antenna 1 to the ceiling 4 and the height from the ceiling 4 to the master unit antenna 3 is added. It is possible to determine the characteristic of the angular distribution of the radiation intensity of the slave unit antenna 1 on the assumption that the master unit antenna 13 is installed in the base unit. In this system, the base unit antenna 3 is installed on the floor
Since the construction for mounting the base unit antenna 3 is not required, and the power supply wiring therefor is not necessary, there is an effect that high-speed and high-quality communication can be performed simply and inexpensively.

In the above embodiment, the patch antenna is used as the slave unit antenna. However, in order to realize an antenna having a planar shape and an angular distribution of the radiation intensity of the beam that is asymmetric with respect to a direction perpendicular to the antenna surface, it is necessary to configure an array antenna, but the type is limited to a patch antenna Not something. For example, a slot antenna may be used. The antenna may have a triplate structure other than the microstrip structure. The present invention can be realized as long as the antenna can realize the angular distribution of the radiation intensity according to the use condition.

[0028]

According to the present invention, by making the characteristics of the slave unit antenna asymmetrical, the signal strength to the master unit antenna can be maintained at a certain level or more even from a location near the cell boundary.
In addition, since the mobility of the slave unit antenna can be ensured by providing a substantially uniform and further providing a movable shaft, there is an effect that a wireless LAN terminal or system suitable for high-speed and high-quality communication can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing an angular distribution of radiation intensity of a slave unit antenna.

FIG. 2 is a top view of the slave unit antenna.

FIG. 3 is a diagram showing an angular distribution of radiation intensity of the slave unit antenna.

FIG. 4 is a diagram showing an operation range of a movable shaft of the slave unit antenna.

FIG. 5 is a view showing a structure of a movable shaft of the slave unit antenna.

FIG. 6 is a configuration diagram of an indoor wireless LAN.

FIG. 7 is a diagram schematically showing an angular distribution of radiation intensity of the slave unit antenna.

FIG. 8 is another configuration diagram of the indoor wireless LAN.

FIG. 9 is an explanatory diagram of a radiation intensity distribution created by the slave unit antenna on the master unit antenna.

FIG. 10 is a diagram showing the distance dependence of the radiation intensity distribution created by the slave unit antenna on the master unit antenna.

FIG. 11 is a diagram showing the distance dependence of the radiation intensity distribution created by the slave unit antenna on the master unit antenna.

FIG. 12 is a diagram showing the distance dependence of the radiation intensity distribution created by the slave unit antenna on the master unit antenna.

FIG. 13 is another configuration diagram of the indoor wireless LAN.

FIG. 14 is a diagram showing the angular distribution of the radiation intensity of the conventional handset antenna.

FIG. 15 is a distribution of radiation intensity created by a slave antenna according to the prior art on a master antenna.

[Explanation of symbols]

1, 7, 11: slave unit antenna, 2, 17: movable shaft,
3, 13: master unit antenna, 4: ceiling, 5: direction perpendicular to the antenna surface, 6: desk, 8: conventional handset antenna, 10: stand, 12: floor, 14: connector, 15: Space, 16: wiring, 18: radiation conductor, 19: installation surface, 2
0: power supply wiring, 21: patch antenna.

Claims (3)

[Claims] 1. An antenna for a slave unit of an indoor wireless LAN, wherein the antenna has a planar antenna surface, and an angular distribution of a radiation intensity of a beam radiated from the antenna surface is in a direction perpendicular to the antenna surface. An indoor wireless LAN slave unit antenna having an asymmetric antenna. 2. The indoor wireless LAN slave unit antenna according to claim 1, further comprising a movable shaft for adjusting a positional relationship with a master unit antenna to be communicated. Antenna for handset. 3. An antenna for a slave unit of an indoor wireless LAN according to claim 1, wherein a plurality of radiation conductors for radiating quasi-millimeter wave or millimeter wave band electromagnetic waves are arranged in an array on said antenna surface. The degree to which the angular distribution of the radiation intensity of the beam radiated from the antenna surface is asymmetric is in the range of one-fifth to three-fifth of the angular distribution of the radiation intensity on the narrow-angle side. Indoor wireless LAN, characterized by being set to
Antenna for handset.