JPH07105660B2 - Received power density equalizer - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a received power density equalizing device, and more particularly to a LAN (Local Area Ne).
(work: a network system such as a computer in a building or the like) relates to a reception power density equalizing device suitable for radio wave radiation from an antenna in a network.

[0002]

2. Description of the Related Art Heretofore, it has been general to use an antenna having a narrow directional characteristic of radio waves for radio wave radiation in a LAN or the like.

[0003]

However, in a LAN or the like, for example, when the antenna of the master station is installed on the ceiling of the room or on the wall surface of the room, the received power density is strong immediately below or in front of the antenna. On the other hand, the electric field strength weakens as the position deviates from the front position. This is because, as shown in FIG. 10 (A), the radiation pattern itself of the normal single antenna 10, which is a radio wave source, has the strongest front position and increases the angle from the front position. This is because it has a pattern characteristic such that the radiated power itself decreases. Another cause is that when the reception position deviates from the front position of the single antenna and the angle from the central axis increases, the distance to the reception point also increases, and a propagation loss due to the distance is added. In order to solve the above-mentioned problems, as shown in FIG. 10 (B), not only the front position but also the angle from the front is increased so that a stronger received power density can be obtained in a wider range. A single antenna 11 having a radiation pattern is also known. However, even if such an antenna is used, it is not possible to solve the above distance attenuation, so that the reception power densities at the respective reception points having different linear distances from the antenna 11 are not necessarily the same. The present invention has been made to solve the above problems, and can emit radio waves so that the reception power density of the radio waves becomes uniform on the reception surfaces at the same distance from the antenna surface in the radio wave direction. The purpose is to provide a device.

[0004]

In order to solve the above-mentioned problems, the present invention provides an incident surface which is made of a dielectric material and on which an electric wave transmitted from an antenna surface of an antenna is incident as an incident electric wave. A received power density homogenizing device having an emission surface for emitting an incident radio wave as an outgoing radio wave, wherein either one of the incidence surface or the emission surface is on a radio wave direction axis which is a central axis in the direction of the radio wave. On the other hand, the other surface of the incident surface or the emission surface, which is not a flat surface, is formed in a plane shape that is perpendicular to the incident surface. the distance to the point where the incident is x to the output of the received power density homogenizing device
Let y be the distance from the projection surface to the receiving point where the emitted radio wave is received, be the permittivity be ε, be the incident angle of the radio wave to the curved surface be θ, and be the transmission power density of the incident radio wave. pt,
The received power density of the emitted radio wave at the receiving point is pr
Then, the following formula

[Equation 2] Is formed so as to satisfy the above condition, and is configured to equalize the received power density on the receiving surface at the same distance from the antenna surface in the direction of the radio wave. Further, in the above received power density homogenizing apparatus, the incident surface and the exit surface are curved surfaces, and a passage path through which the incident radio wave incident on the incident surface at a distance x from the radio wave direction axis passes through the dielectric body. The curvatures of the incident surface and the emission surface are set so that the length becomes equal to the path length of the incident radio wave incident on the position equal to the position of the distance x in the dielectric in the above-mentioned received power density homogenizing device. It may be configured as follows.

[0005]

According to the present invention having the above-mentioned structure, one of the surfaces of the dielectric is formed in a plane perpendicular to the radio wave direction axis, and the other surface is formed by the following formula.

[Equation 3] Since it is formed into a curved surface that satisfies the above conditions, when the radio wave is incident on the surface of the dielectric and then re-emitted, it is refracted in the traveling direction of the radio wave and the diffusion of the radio wave that passes through the dielectric allows Radio waves from the radiator can be diffused toward the reception point, and the emitted radio waves are emitted from the emission surface so that the reception power density is uniform on the reception surface where the distance from the antenna surface to the direction of the radio waves is equal. Can be made.
Further, in the above-mentioned received power density homogenizing device, both the entrance surface and the exit surface are formed into curved surfaces, and the path length of the incident radio wave incident on the entrance surface at the distance x from the radio wave direction axis passes through the dielectric. However, if the curvatures of the incident surface and the emission surface are set so as to be equal to the path length of the incident radio wave incident on the position equal to the position of the distance x in the above-mentioned received power density homogenizer, Using a dielectric, emit radio waves from the emission surface so that the reception power density becomes uniform on the reception surface where the distance from the radio wave radiator such as an antenna in the direction of the radio waves is the same as in the above case. You can

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of the first embodiment of the present invention. As shown in FIG. 1, this received power density homogenizing apparatus 1
Is configured by arranging the dielectric into a substantially concave lens shape having a flat surface S1 and a curved surface S2 perpendicular to the radio wave direction axis A-A, and is arranged between the antenna 4 and the receiving surface Q-Q. Further, the received power density homogenizing device 1 is formed in the shape of a rotary body having a radio wave direction axis A-A as a rotation axis. Here, the antenna 4 is an antenna that transmits electric power forming a parallel plane wave, and is, for example, an antenna configured by arranging a plurality of single antennas in an array.

In this case, the receiving surface Q-Q is the radio wave direction axis A-
It is configured as a plane perpendicular to A, and the vertical distances (distances in the direction of radio waves ) from the lower surface (antenna surface) of the antenna 4 at each point on the receiving surface Q-Q are all equal r. Here, there is a relation of r = y + z .

An incident radio wave from the antenna 4 is incident on the plane S1 of the receiving power density equalizing device 1 at the transmission power density pt and is emitted from the curved surface S2. Therefore, the flat surface S1 is the incident surface and the curved surface S2 is the exit surface.

Next, a more detailed structure of the curved surface S2 which is the emission surface of the reception power density uniformizing apparatus 1 of this embodiment and the operation of the reception power density uniforming apparatus 1 of this embodiment will be described with reference to FIG.
9 to FIG. 9 will be described in detail.

FIG. 6 is a diagram showing the power value at each reception point of the radio wave radiated from the center point 0 of the antenna. The power value at the transmission point is P _t , and the distance from the transmission point to the reception point is r
Then, the power value P _r at the receiving point is calculated by the following equation.

[Equation 4] Can be expressed as Here, k is a proportional constant. Therefore, from the above equation (1), the power value P _{r at the} receiving point
Is proportional to the power value P _t at the transmission point and inversely proportional to the square of the distance r from the transmission point to the reception point.

FIG. 7 shows the relationship between the incident angle θ1 and the refraction angle θ2 when a radio wave enters from the space M1 having a dielectric constant of 1 to the dielectric M2 having a dielectric constant of ε. Between the angle θ1 and the refraction angle θ2, the following equation

[Equation 5] There is a relationship represented by. In the above formula (2), ε represents the dielectric constant. In air, the value of ε is about 1.0 (farad / m).

FIG. 8 is a diagram for explaining the principle of this embodiment. First, the plane wave power of the transmission power density pt from the antenna 4 is the plane S1 which is the incident surface of the reception power density uniformizing device 1.
Incident on. In this case, the value P _t of the power of the entire ring having the minute width dx at the position of the radius x from the radio wave direction axis A-A is
Can be represented by the formula _{P t = pt · 2π · x} · dx ........................ below (3).

On the other hand, the value P _r of the received power, which is a projected image on the receiving surface Q separated by the distance y from the emission surface S2 of the receiving power density homogenizing apparatus 1, is given by the following equation, where pr is the receiving power density. P _r = pr · 2π {x + y · tan (θo−θ)} dx can be expressed by (4).

Since the plane S1 which is the incident surface is perpendicular to the traveling direction of the passing radio wave, refraction of the radio wave does not occur, but the curved surface S2 which is the emitting surface is not perpendicular to the traveling direction of the passing radio wave. Therefore, refraction as shown in FIG. 8 occurs. Here, the angle θ is the angle of incidence on the curved surface S2. Therefore, in the above equation (4), the angle θ
o is the following equation using the angle θ from the above equation (2).

[Equation 6] Can be expressed as

Further, since the values of the transmission power P _t and the reception power P _r must be equal, there is a relation expressed by the following equation P _t = P _r .

Therefore, by substituting the above equations (3) and (4) for rearranging, the following equation is obtained.

[Equation 7] The relationship shown in can be derived.

In the usual case, the distance y from the emission surface S2 of the reception power density uniformizing device 1 to the reception surface Q is extremely large compared to the distance x from the radio wave direction axis AA of the reception power density uniformizing device 1. Is very large. Therefore, 1 is a range that can be ignored with respect to y / x. Therefore, by ignoring 1 and substituting the above equation (5) into equation (7), the following equation is obtained.

[Equation 8] Can be expressed as The shape of the emission surface S2 of the reception power density uniformizing device 1 at the position of the distance x from the radio wave direction axis A-A can be determined from the equation (8).

That is, since the reception power density pr is made constant when the transmission power density pt is constant, if pt / pr is made constant in the above equation (8),
The shape of the emission surface S2 can be determined.

The following table shows the trial calculation results obtained by substituting specific numerical values into the above equation (8).

[Table 1] Shown in. Numerical parameters other than θ and x are pt
/ Pr = 100, y = 2000 mm, ε = 4.0 farad / m.

In order to obtain the concrete shape of the curved surface S2 from the numerical values in Table 1, it is necessary to perform integration on x, and FIG. 9 schematically shows the shape of the curved surface S2. As can be seen from FIG. 9, this curved surface S2 is similar to the curved surface of a concave lens, but is an aspherical curved surface different from a normal spherical concave lens and has no focus unlike a normal spherical concave lens, The radius of curvature of the curved surface increases as the distance x from the radio wave direction axis A-A increases.
Further, if the distance y from the emission surface S2 of the reception power density uniformizing device 1 to the reception surface Q changes, the shape of the reception power density uniforming device also changes.

Next, a second embodiment of the present invention will be described. As shown in FIG. 2, this received power density equalizing device 2
Is configured as a concave lens of a rotating body having a flat surface S3 and a curved surface S4 perpendicular to the radio wave axis AA, and
It is arranged between the antenna 5 and the receiving position Q-Q. Here, the antenna 5 is an antenna that transmits electric power that is not a parallel plane wave, and is, for example, a normal single antenna having a radiation pattern as shown in FIG.

In the above case, the transmission power density pt
Varies depending on the distance x from the radio wave direction axis A-A. In this case, in order to obtain the shape of the outgoing-side curved surface S4 of the reception power density uniformization device 2, the reception power density pt (x) of the radio wave incident on the reception power density uniformization device 1 is known, and then the reception power density is obtained. The shape of the emission surface S3 may be determined by the above equation (8) with pr kept constant and the incident angle of the radio wave on the curved surface being θ.

Further, the above-mentioned received power density uniformizing device 1,
With No. 2, even if the entrance surface and the exit surface are reversed, the same effect as described above can be obtained. Specifically, this is the case as in the third embodiment shown in FIG. 3 and the fourth embodiment shown in FIG. In this case, the shape of the curved surface may be determined by the above equation (8) with the incident angle of the radio wave on the curved surface being θ.

Further, FIG. 4 shows an example in which a horn antenna 6 is provided as a radiator for transmitting a non-parallel plane wave.

In the above-mentioned embodiment, the receiving power density homogenizing device is one in which one of the incident surface and the emitting surface of the radio wave is a flat surface. As long as the path length of the radio wave passing therethrough is the same as that in the above-described embodiment, the received power density equalizing device having another shape may be used. For example, there is a case where both the entrance surface and the exit surface are curved surfaces as in the received power density homogenizing device 3 of the fifth embodiment shown in FIG. In this case, the radio wave direction axis A
The curvatures of the entrance surface and the exit surface are set such that the transmission path length TX of the radio wave incident on the position of the distance x from −A in the dielectric body becomes equal to that of the reception power density uniformizing device 1 in FIG. 1, for example. . Also in this case, similarly to each of the above-described embodiments, the shape of the curved surface may be determined by the above equation (8) with the incident angle of the radio wave on the curved surface being θ.

Further, in addition to the above example, the concept of a Fresnel lens used as a method for reducing the lens thickness in an optical lens is applied to the present invention to form a dielectric in a Fresnel lens shape. It is also effective to use and belongs to the technical scope of the present invention.

Further, FIGS. 10A and 10B showing a conventional example.
It is also possible to use the single antennas 10 and 11 having the radiation pattern characteristics of. In that case, the above distance x
The radiation pattern of the antenna itself may be variably controlled according to the value of y or y. Alternatively, the radiation pattern can be approximately variably controlled by adjusting the distance between the primary radiator of the antenna and the received power density equalizing device, utilizing the distance attenuation of the transmission power.

The present invention is not limited to the above embodiment. The above-mentioned embodiment is an exemplification, has substantially the same configuration as the technical idea described in the scope of the claims of the present invention, and has any similar effect to the present invention. It is included in the technical scope of the invention.

[0029]

As described above, according to the present invention,
One of the dielectrics is formed on a plane perpendicular to the radio wave direction axis, and the other surface is

[Equation 9] Since it is formed into a curved surface that satisfies the above conditions, when the radio wave is incident on the surface of the dielectric and then re-emitted, it is refracted in the traveling direction of the radio wave and the diffusion of the radio wave that passes through the dielectric allows Radio waves from the radiator can be diffused toward the reception point, and the emitted radio waves are emitted from the emission surface so that the reception power density is uniform on the reception surface where the distance from the antenna surface to the direction of the radio waves is equal. Can be made.
Further, in the above-mentioned received power density homogenizing device, both the entrance surface and the exit surface are formed into curved surfaces, and the path length of the incident radio wave incident on the entrance surface at the distance x from the radio wave direction axis passes through the dielectric. However, if the curvatures of the incident surface and the emission surface are set so as to be equal to the path length of the incident radio wave incident on the position equal to the position of the distance x in the above-mentioned received power density homogenizer, Using a dielectric, emit radio waves from the emission surface so that the reception power density becomes uniform on the reception surface where the distance from the radio wave radiator such as an antenna in the direction of the radio waves is the same as in the above case. You can

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a configuration of a received power density equalizing apparatus that is a first embodiment of the present invention.

FIG. 2 is a conceptual diagram showing a configuration of a received power density equalizing device that is a second embodiment of the present invention.

FIG. 3 is a conceptual diagram showing the configuration of a received power density equalizing device that is a third embodiment of the present invention.

FIG. 4 is a conceptual diagram showing the configuration of a received power density equalizing apparatus that is a fourth embodiment of the present invention.

FIG. 5 is a conceptual diagram showing the configuration of a received power density equalizing apparatus that is a fifth embodiment of the present invention.

FIG. 6 is a diagram illustrating power at a reception point of radio waves radiated from an antenna.

FIG. 7 is a diagram illustrating refraction of radio waves at a boundary surface of a dielectric.

FIG. 8 is a conceptual diagram illustrating the principle of the received power density equalizing device shown in FIG.

9 is a diagram showing an example of a curved surface shape of the reception power density uniformizing device shown in FIG.

FIG. 10 is a diagram showing electric field strength in a conventional antenna.

[Explanation of symbols]

 1,2,3 Received power density equalizer 4,5 Antenna 6 Horn antenna 10,11 Antenna

Claims (2)

[Claims] 1. A uniform received power density having an incident surface made of a dielectric material, on which an electric wave transmitted from an antenna surface of an antenna enters as an incident electric wave, and an emitting surface for emitting the incident electric wave as an outgoing electric wave. In either of the incident surface and the emission surface, one of the incident surface and the emission surface is formed in a plane shape perpendicular to the radio wave direction axis which is the central axis of the radio wave direction, and the incident surface or the emission surface. The other surface of the surfaces, which is not a flat surface, is formed into a curved surface, and the curved surface has a distance x from the radio wave direction axis to a point where the incident radio wave is incident on the incident surface, and the reception power density is uniform.
From the exit surface of the apparatus the outgoing distance radio to the receiving point, which is received and y, the dielectric constant and epsilon, to the curved surface
When the incident angle of the radio wave is θ, the transmission power density of the incident radio wave is pt, and the reception power density of the outgoing radio wave at the reception point is pr, the following equation is obtained: The received power density equalizing device is formed to have a curved surface satisfying the condition (1), and uniformizes the received power density on the receiving surface at the same distance from the antenna surface in the direction of the radio wave. 2. The entrance path and the exit surface are curved surfaces, and a passing path length through which the incident radio wave incident on the entrance surface at a distance x from the radio wave direction axis passes through the dielectric body, In the received power density equalizing device, the distance x
The received power density homogenization of claim 1, wherein the dielectric of the incident surface so as to be equal to the passing path length and the exit surface curvature, characterized in that the set of the incident radio wave incident on the same position the position of the apparatus.