WO2020136791A1 - Electromagnetic wave filter and spatial magnetic field control system - Google Patents

Abstract

An electromagnetic wave filter (100) is provided on the radio wave emission direction of an access point (400) which has a general-purpose dipole antenna, and controls the distribution of an electric field. This electromagnetic wave filter (100) is formed of a conductor, has a plurality of bent surfaces (101) and slots that are formed so as to form openings in the bent surfaces (101), sets the electric field to be substantially constant inside a prescribed communication area (700), and sets the electric field to become drastically weak outside the communication area so as to form an uncommunicable area (701). Each of the bent surfaces (101) has a prescribed angle to the emission direction. Each of the slots forms an opening having a prescribed length in a direction orthogonal to the polarization direction of the antenna, and said length is about 1/2 of the wavelength of the radio wave.

Description

Electromagnetic wave filter and spatial electromagnetic field control system

The present invention relates to an electromagnetic wave filter for controlling electromagnetic waves and a space electromagnetic field control system.

By installing a wireless router and access point (AP), terminals etc. can communicate wirelessly. Sensors and terminals using the IoT (Intenet Of Things) technology may have different wireless communication systems co-located in the same area. For example, WiFi (registered trademark) having a communication frequency of 2.4 GHz band or 5 GHz band is used in factories, hospitals, restaurants, etc., and even in a mixed environment, it is easy to construct a wireless communication system for each communication system. , Security is required.

Since the dipole antenna mainly used for wireless routers and APs spreads out a circular electric wave toward the communication area, extra electric wave leaks out of the desired area, and the electric wave, wall, and metal surface of the adjacent AP Due to the interference with the reflected waves, null spots are generated in which the radio waves weaken.

As a conventional technology, there is an electromagnetic wave filter that controls the electromagnetic field in the space radiated from the antenna. For example, there is a vehicle-mounted radar technique in which a metal slit plate having a plurality of slits is arranged in the radiation direction of an antenna to reduce reflected waves of side lobes (for example, refer to Patent Document 1 below). In addition, there is a technique of varying the beam width by allowing the reflector having a slit to pass only the polarized waves orthogonal to the slit for the V and H polarized waves of the primary radiator (see, for example, Patent Document 2 below). In addition, there is a technique in which a plurality of small reflecting plates of a radiating element are arranged with a gap therebetween, and the small reflecting plates can be easily replaced and are equivalent to an antenna of a large reflecting plate (for example, refer to Patent Document 3 below). In addition, there is a technique in which a large number of millimeter-wave antenna aperture surfaces are arranged in a large array on a substrate to narrow the beam and form a constant electric field value (Fresnel zone) in a predetermined area such as a gate (for example, , Non-Patent Document 1 below).

JP, 2006-029834, A Japanese Patent Laid-Open No. 11-214920 JP-A-63-026006

However, with the above-mentioned conventional technology, it was not possible to confine radio waves to a specific communication area in wireless communication using a general-purpose wireless router or AP. As in Patent Documents 1 and 2, only arranging a metal plate (reflector) having a slit in front of the antenna cannot perform polarization control but radio wave area control. Further, in Patent Document 3 and Non-Patent Document 1, in addition to using an arrayed reflector, it is not possible to use radio waves radiated by a general-purpose wireless router or AP.

In one aspect, the present invention aims to be able to confine radio waves in a specific communication area.

In one proposal, the electromagnetic wave filter is an electromagnetic wave filter that is provided on the emitting direction of the radio waves of the antenna and controls the electric field distribution, and is made of a conductor, and has a plurality of bent curved surfaces and openings formed on the bent curved surfaces. It is required that the electric field has a slot and has a substantially constant electric field within a predetermined communication area, and the electric field is suddenly weakened outside the communication area.

According to one embodiment, it is possible to confine radio waves in a specific communication area.

FIG. 1 is a diagram showing an electromagnetic wave filter according to an embodiment. FIG. 2 is a diagram showing a case where the incident angle of the electromagnetic wave on the electromagnetic wave filter according to the embodiment is oblique. FIG. 3 is a diagram showing a case where the incident angle of the electromagnetic wave on the electromagnetic wave filter according to the embodiment is more oblique. FIG. 4A is a diagram showing a characteristic example of each condition of the electromagnetic wave filter according to the exemplary embodiment. (Part 1) FIG. 4B is a diagram showing a characteristic example of each condition of the electromagnetic wave filter according to the exemplary embodiment. (Part 2) FIG. 5A is a diagram showing a characteristic example of each condition of the electromagnetic wave filter according to the exemplary embodiment. (Part 3) FIG. 5B is a diagram showing a characteristic example of each condition of the electromagnetic wave filter according to the exemplary embodiment. (Part 4) FIG. 6A is a diagram showing a characteristic example of each condition of the electromagnetic wave filter according to the exemplary embodiment. (Part 5) FIG. 6B is a diagram showing a characteristic example of each condition of the electromagnetic wave filter according to the exemplary embodiment. (Part 6) FIG. 7 is an explanatory diagram of a communication area by the electromagnetic wave filter according to the embodiment. FIG. 8A is a diagram showing a configuration example of a spatial electromagnetic field control system including the electromagnetic wave filter according to the exemplary embodiment. (Part 1) FIG. 8B is a diagram showing a configuration example of a spatial electromagnetic field control system including the electromagnetic wave filter according to the exemplary embodiment. (Part 2) FIG. 9 is a diagram illustrating a hardware configuration example of a transmitter of the spatial electromagnetic field control system according to the exemplary embodiment. FIG. 10 is a diagram illustrating a hardware configuration example of a terminal of the spatial electromagnetic field control system according to the exemplary embodiment. FIG. 11 is a diagram showing a configuration example of the electromagnetic wave filter used for the simulation according to the embodiment. FIG. 12 is a diagram showing a simulation result of the electric field distribution of the electromagnetic wave filter according to the embodiment. FIG. 13 is a diagram showing various antenna characteristics when the electromagnetic wave filter according to the embodiment is used. (Part 1) FIG. 14 is a diagram showing various antenna characteristics when the electromagnetic wave filter according to the embodiment is used. (Part 2) FIG. 15A is a diagram showing various antenna characteristics when the electromagnetic wave filter according to the embodiment is used. (Part 3) FIG. 15B is a diagram showing various antenna characteristics when the electromagnetic wave filter according to the embodiment is used. (Part 4) FIG. 16 is a diagram in which the communication area of the spatial electromagnetic field control system according to the embodiment is scaled up. FIG. 17 is a diagram showing a plurality of communication areas of the space electromagnetic field control system according to the embodiment. FIG. 18 is a diagram showing a construction example of a plurality of communication areas of the spatial electromagnetic field control system according to the exemplary embodiment. FIG. 19 is a diagram illustrating a communication area using the electromagnetic wave filter according to the embodiment. FIG. 20 is a diagram showing an electric field distribution when the width of the electromagnetic wave filter according to the embodiment is changed. FIG. 21 is a diagram showing a state in which the height of the electromagnetic wave filter according to the embodiment is changed. FIG. 22 is a diagram showing an application example of the space electromagnetic field control system according to the embodiment.

(Embodiment)
Hereinafter, embodiments of the electromagnetic wave filter and the spatial electromagnetic field control system of the present invention will be described. The electromagnetic wave filter according to the embodiment is provided in the emission direction of an electric wave emitted from an antenna of a transmitter including a wireless communication router or an access point (AP), and traps the electric wave in a specific communication area. The electromagnetic wave filter traps the electric wave within the communication area by controlling the electromagnetic wave so that the electric wave strength (electric field) is almost constant in the communication area and the electric wave strength (electric field) is suddenly weakened outside the communication area.

In addition, the spatial electromagnetic field control system according to the embodiment includes the above-mentioned electromagnetic wave filter, a transmitter that transmits a radio wave, and a receiver that receives a radio wave transmitted by the transmitter when located within a specific communication area. Including and For example, the transmitter is the above-mentioned router or access point (AP), and the receiver is a terminal (smartphone, portable personal computer (PC), etc.) held by a user who can move to a specific communication area.

FIG. 1 is a diagram showing an electromagnetic wave filter according to an embodiment. FIG. 1A is a partial side sectional view, and FIG. 1B is a partial front view. As shown in FIG. 1A, the electromagnetic wave filter 100 is formed in a substantially wavy shape by bending a conductor such as a metal plate. The conductor is, for example, a metal plate made of copper, aluminum, iron or the like, or a metal layer made of copper or the like provided on one side or both sides of a high frequency substrate (for example, a dielectric base material (for example, 1 mm in thickness) such as glass epoxy). (For example, the thickness is 18 microns).

In the example of FIG. 1A, the angle θ is 30 degrees, and in this case, the bent folding surface 101 forms an inverted V-shape with two sides of the substantially triangular shape between the folding surface 101 and the adjacent folding curved surface 101. In the electromagnetic wave filter 100, the inverted V-shape is continuously formed in the X-axis direction to have a substantially wavy shape.

FIG. 1B shows a partial view of the bent curved surface 101. A slot 102 having a predetermined width W and a length L is formed in the folded curved surface 101 along a direction orthogonal to the electromagnetic wave incident direction. The width W of the slot 102 is about a minute width (for example, 2 mm) that allows radio waves to pass therethrough. The length L of the slot 102 has a relationship of L=λa/2 with respect to the wavelength λ of radio waves (electromagnetic waves), for example. A plurality of the slots 102 are formed at a predetermined interval in the depth direction Z of the curved surface 101 shown in FIG.

In the example of FIG. 1, the double slot in which the slot 102 is provided in each of the adjacent folding curved surfaces 101 has been described, but the present invention is not limited to this, and the slot 102 may be provided in only one of the adjacent folding curved surfaces 101 (single slot). ). For example, the double slot and the single slot can be appropriately selected according to the shape in a specific communication area and the intensity distribution of a radio wave desired in the communication area.

Further, in the above description, the electromagnetic wave filter 100 has been described as having the curved surface 101 having an inverted V shape, but as will be described later in detail, the electromagnetic wave filter 100 has an optimal angle θ and has an inverted V shape and a V shape. It has a corrugated shape that is arranged alternately.

A router or an AP is arranged on one incident surface 100a (front side of the lower part of the figure) of the electromagnetic wave filter 100, and a radio wave (electromagnetic wave) radiated from an antenna of a transmitter of the router or AP is incident on the incident surface 100a. ..

Next, an outline of transmission and reflection characteristics of electromagnetic waves incident on the electromagnetic wave filter 100 for each incident angle will be described with reference to FIGS. 1 to 3. FIG. 1 shows a case where the incident angle of the electromagnetic wave on the electromagnetic wave filter 100 is 0°, that is, the electromagnetic wave enters the electromagnetic wave filter 100 from the front direction.

When an electromagnetic wave is incident from the front direction of FIG. 1, the slot 102 is positioned at an angle of Lsinθ with respect to the wavelength λa/2 of the electromagnetic wave in the front direction with respect to the electromagnetic wave filter 100, and Lsinθ becomes small. .. Thereby, in the electromagnetic wave filter 100, when the electromagnetic wave is incident on the incident surface 100a from the front direction, the ratio of the electromagnetic wave to be reflected (ref.) is increased, and thus the ratio of transmitted (pass) is decreased to be input. Attenuates a lot of electromagnetic power.

For example, assume that at the incident angle of 0° (90° with respect to the X axis) shown in FIG. 1, the power Pin of the electromagnetic wave input to the incident surface 100a is Pin=100 (100%). In this case, the reflection power Pref. =100×0.8=80 (80%), and the transmission power Ppass=100×0.2=20 (20%).

FIG. 2 is a diagram showing a case where the incident angle of the electromagnetic wave on the electromagnetic wave filter according to the embodiment is oblique. In FIG. 2, the incident angle of the electromagnetic wave with respect to the X axis is θ (30°), that is, the length L of the slot 102 of the electromagnetic wave filter 100 is substantially the same as the wavelength λa/2 of the electromagnetic wave, and the electromagnetic wave is obliquely incident. Shows the case of incidence.

When the electromagnetic wave is incident from the oblique direction in FIG. 2, the L of the slot 102 is located at substantially the same size with respect to the electromagnetic wave filter 100 with respect to the wavelength λa/2 of the electromagnetic wave in the oblique direction. In this case, the ratio of reflecting (ref.) the electromagnetic wave becomes small, and thus the ratio of transmitting (pass) becomes large, and a large amount of the power of the inputted electromagnetic wave passes.

For example, in the case of the incident angle of 0° shown in FIG. 2, when the power Pin of the electromagnetic wave input to the incident surface 100a is 100, the reflected power Pref. =100×0.2=20, and the transmission power Ppass=100×0.8=80.

FIG. 3 is a diagram showing a case where the incident angle of the electromagnetic wave on the electromagnetic wave filter according to the embodiment is more oblique. In the example of FIG. 3, the incident angle θ of the electromagnetic wave with respect to the X axis is further inclined in the X axis direction than in FIG. 2 (about 15°). This shows the case where only a small amount of light is incident on.

As shown in FIG. 3, when the electromagnetic wave is incident from a more oblique direction, the electromagnetic wave filter 100 has a larger rate of reflecting (ref.) the electromagnetic wave that is obliquely incident to the incident surface 100a, and thus the electromagnetic wave is transmitted. The ratio of the input electromagnetic waves becomes small, and the power of the input electromagnetic wave is largely attenuated.

For example, in the case of an incident angle of 15° shown in FIG. 3, when the power Pin of the electromagnetic wave input to the incident surface 100a is 100, the reflected power Pref. =100×0.8=80, and the transmission power Ppass=100×0.2=20.

As shown in FIGS. 1 to 3, the electromagnetic wave filter 100 has a high reflection ratio with respect to the electromagnetic wave incident on the incident surface 100a from the front direction (90° with respect to the X axis). Further, the electromagnetic wave incident on the incident surface 100a at a predetermined angle (for example, θ=30° with respect to the X axis) has a high transmission rate. Furthermore, the ratio of reflection is high for electromagnetic waves incident from an angle (eg, θ=15° with respect to the X axis) that is oblique to the treatment angle.

FIG. 4 (FIG. 4A, FIG. 4B) to FIG. 6 (FIG. 6A, FIG. 6B) are diagrams showing characteristic examples according to conditions of the electromagnetic wave filter according to the embodiment. The electric field state of the radio wave transmitted through the electromagnetic wave filter when the angle of the electromagnetic wave filter is changed with respect to the antenna of the transmitter using the electromagnetic field simulator will be described.

First, the electric field (E) distribution when the incident angle of the electromagnetic wave with respect to the electromagnetic wave filter 100 (folded curved surface 101) provided with the single slot 102 is changed will be described with reference to FIG. 4 (FIGS. 4A and 4B).

As shown in FIG. 4A (a), the bent curved surface 101 is located on the Y-axis plane, and the antenna 400 of the transmitter is a dipole antenna having a length of 27 mm along the Z-axis direction, and It is located on the near side of the folding curved surface 101 in the figure (at a position of -30 mm). The bent curved surface 101 is a square of 120 mm in length and width on the Y-axis surface, and the slot 102 has an opening of 27 mm along a direction orthogonal to the direction of the antenna 400 (polarization direction). The center frequency f0 of the radio wave radiated from the antenna 400 of the transmitter was set to f0=5 GHz, and the power of the electromagnetic wave input to the incident surface 100a was set to Pin=1W.

FIG. 4A(b) is a table showing the electric field E when the angle θ is changed between the X- and Y-axes about the Z-axis of the electromagnetic wave filter (folded curved surface 101) for the fixed antenna 400. The electric field E is a value on the inner side (at a position of 110 mm) of the folding curved surface 101 in the Y-axis direction. The dotted line in the figure is the characteristic curve of the sin curve.

4B(a) to 4(d) show the radio wave distribution corresponding to FIG. 4A(b), and the electromagnetic wave filter 100 (folded curved surface 101) is placed between the X and Y axes about the Z axis with respect to the antenna 400. FIG. 6 is a diagram showing a state of a radio wave distribution when the angle θ is changed by. Each of these figures shows an electric field distribution in an area including the antenna 400 and the electromagnetic wave filter 100 and having an area of 200 mm in the X-axis direction and 160 mm in the Y-axis direction.

In FIG. 4B(a), the curved surface 101 is located on the Y axis (90° with respect to the X axis), and the electromagnetic wave filter 100 is arranged in the polarization direction of the antenna 400 having a length along the Z axis. The state where the (slot 102) is orthogonal (θ=90°) is shown. When a radio wave enters the slot 102 from directly in front (θ=90°), the electromagnetic wave filter 100 allows many radio waves to pass through the slot 102. It is shown that the transmission power Ppass is large in the range along the Y axis on the side that has passed through the electromagnetic wave filter 100 (the upper side in the figure). At this time, the electric field at the uppermost position Ya (Y=110 mm) in the chart is 67 V/m.

In FIG. 4B(b), the bent curved surface 101 is positioned at an angle of 60° with respect to the Y axis. In the electromagnetic wave filter 100, the range of the transmission power Ppass is shown on the upper left side after passing through the slot 102. At this time, the electric field at the top of the chart (position Ya) is 45 V/m.

In FIG. 4B(c), the bent curved surface 101 is positioned at an angle of 30° with respect to the Y axis. In the electromagnetic wave filter 100, the range of the transmission power Ppass is shown on the upper left side after passing through the slot 102, and it is shown that the transmission power is smaller than that in FIG. 4B(b). At this time, the electric field at the top of the chart (position Ya) is 10 V/m.

In FIG. 4B(d), the bent curved surface 101 is positioned at an angle of 15° with respect to the Y axis. In the electromagnetic wave filter 100, the range of the transmission power Ppass is shown on the left side after passing through the slot 102, and it is shown that the transmission power is smaller than that in FIG. 4B(c). At this time, the electric field at the top of the chart (position Ya) is 14 V/m.

In the case of the slot 102 of the electromagnetic wave filter 100 shown in FIG. 4A (a), as shown in FIGS. 4B (a) to (B), when the radio wave is incident from directly in front (θ=90°), the transmittance is large. On the other hand, when a radio wave is incident on the slot 102 at a certain angle, the transmittance becomes small.

Here, the electric field intensity E at the position Ya shown in FIG. 4A(b) is E=67 (V/m) when the angle θ with respect to the Y axis is 90°, and the sin curve is reduced as the tilt angle is reduced. E decreases along with. When the angle θ is 30°, the electric field strength E is the smallest (E=10 V/m), and when the angle θ is 15°, the electric field strength E increases again (E=14 V/m). According to the characteristics of FIG. 4A(b), when the angle (θ) at which the transmitted wave is the minimum and the reflected wave is the maximum is 30°, the optimum value is obtained in the case of multiple slots.

Next, referring to FIG. 5 (FIG. 5A, FIG. 5B) and FIG. 6 (FIG. 6A, FIG. 6B), the electric field when the incident angle of the electromagnetic wave with respect to the electromagnetic wave filter 100 (folded curved surface 101) provided with the double slot is changed. (E) The distribution will be described.

First, the electromagnetic wave filter 100 shown in FIG. 5A (a) has two bent curved surfaces 101 formed by bending a metal plate or the like, and the two bent curved surfaces 101 are convex in the incident direction of electromagnetic waves (Y axis front side). Slots 102 are formed on each of the bent curved surfaces 101 so as to project. The two folding curved surfaces 101 are inclined by 30° with respect to the Y axis, as in FIG. 1.

Note that the antenna 400 of the transmitter is a dipole antenna having a length of 27 mm along the Z-axis direction, as in FIG. 4A, and is on the front side of the folding curved surface 101 in the Y-axis direction (at a position of −30 mm). Is located in.

Also, each of the two bent curved surfaces 101 is a square having a length and width of 120 mm, and the slot 102 has an opening of 27 mm along a direction orthogonal to the direction of the antenna 400 (polarization direction). The center frequency f0 of the radio wave radiated from the antenna 400 of the transmitter was set to f0=5 GHz, and the power of the electromagnetic wave input to the incident surface 100a was set to Pin=1W.

FIG. 5A(b) is a chart showing the electric field E when the angle θ of the electromagnetic wave filter 100 is changed about the Z axis with respect to the fixed antenna 400 between the X and Y axes. This electric field E is a value on the back side (at a position of 110 mm) of the electromagnetic wave filter 100 in the Y-axis direction. The dotted line in the figure is the characteristic curve of the sin curve.

Further, FIGS. 5B(a) to 5(d) show a radio wave distribution corresponding to FIG. 5A(b), and the angle θ is changed with respect to the antenna 400 about the Z axis of the electromagnetic wave filter 100 between the X and Y axes. It is a figure which shows the state of a radio wave distribution at the time of making it.

In FIG. 5B(a), the electromagnetic wave filter 100 is located on the Y axis (90° with respect to the X axis), and the electromagnetic wave filter 100 is in the polarization direction of the antenna 400 having a length along the Z axis. The state where the (slot 102) is orthogonal (θ=90°) is shown. When a radio wave enters the slot 102 from directly in front (θ=90°), the electromagnetic wave filter 100 allows many radio waves to pass through the slot 102. It is shown that the transmission power Ppass is large in the range along the Y axis on the side that has passed through the electromagnetic wave filter 100 (the upper side in the figure).

FIGS. 5B(b) to 5(d) show a state in which the electromagnetic wave filter 100 is positioned at an angle of 60°, 30°, and 15° with respect to the Y axis. Even with these inclinations, the range of the transmission power Ppass is shown in the range along the Y-axis on the side where the electromagnetic wave filter 100 is transmitted through the slot 102 (the upper side in the drawing).

At this time, the electric field at the top of the chart (position Ya) is 70 V/m when θ is 90°, 60 V/m when θ is 60°, 35 V/m when θ is 30°, and 15° when θ is 30°. Sometimes it is 25 V/m. It is shown that the smaller θ is, the shorter the slot length seen from the antenna 400 (dipole antenna) becomes, and the smaller the generated electric field Ev becomes.

Next, the electric field (E) distribution when the incident angle of the electromagnetic wave with respect to the electromagnetic wave filter 100 (folded curved surface 101) provided with the double slot is changed will be described with reference to FIG. 6 (FIGS. 6A and 6B).

The electromagnetic wave filter 100 shown in FIG. 6A (a) has two bent curved surfaces 101 formed by bending a metal plate or the like, and the two bent curved surfaces 101 are provided in a concave shape that spreads in the electromagnetic wave incident direction (Y axis front side). A slot 102 is formed on each bent surface 101. The two folding curved surfaces 101 are inclined by 30° with respect to the Y axis, as in FIG. 1.

FIG. 6A(b) is a chart showing the electric field E when the angle θ of the electromagnetic wave filter 100 is changed about the Z axis between the X and Y axes with respect to the fixed antenna 400. This electric field E is a value on the back side (at a position of 110 mm) of the electromagnetic wave filter 100 in the Y-axis direction. The dotted line in the figure is the characteristic curve of the sin curve.

6B(a) to 6(d) show a radio wave distribution corresponding to FIG. 6A(b), in which the angle θ is changed with respect to the antenna 400 about the Z axis of the electromagnetic wave filter 100 between the X and Y axes. It is a figure which shows the state of a radio wave distribution at the time of making it.

In FIG. 6B(a), the electromagnetic wave filter 100 is located on the Y axis (90° with respect to the X axis), and the electromagnetic wave filter 100 is arranged in the polarization direction of the antenna 400 having a length along the Z axis. The state where the (slot 102) is orthogonal (θ=90°) is shown. When a radio wave enters the slot 102 from directly in front (θ=90°), the electromagnetic wave filter 100 allows many radio waves to pass through the slot 102. It is shown that the transmission power Ppass is large in the range along the Y axis on the side that has passed through the electromagnetic wave filter 100 (the upper side in the figure).

FIGS. 6B(b) to 6B(d) show a state in which the electromagnetic wave filter 100 is positioned at an angle of 60°, 30°, and 15° with respect to the Y axis. Even with these inclinations, the range of the transmission power Ppass is shown in the range along the Y-axis on the side where the electromagnetic wave filter 100 is transmitted through the slot 102 (the upper side in the drawing).

At this time, the electric field at the top of the chart (position Ya) is 65 V/m when θ is 90°, 62 V/m when θ is 60°, 40 V/m when θ is 30°, and 15° when θ is 30°. Sometimes it is 10 V/m. It is shown that the smaller θ is, the shorter the slot length seen from the antenna 400 (dipole antenna) is, and thus the smaller the electric field Ev is.

Here, FIG. 6A(b) shows the characteristics of the electric field distribution Evr and the characteristics of the electric field Ev of the above-mentioned convex electromagnetic wave filter 100 (FIG. 5A(b)). According to the characteristics shown in FIG. 6A(b), an optimum value is obtained in which the electric field distribution Evr and the electric field Ev are well balanced and have the same value in the vicinity of θ=30° with respect to the change of θ. That is, in the case of the double slot configuration, the electromagnetic wave filter 100 preferably has a shape obtained by combining the convex shape shown in FIG. 5 (FIG. 5A(a)) and the concave shape shown in FIG. 6 (FIG. 6A(a)). (Corresponding to Figure 1).

FIG. 7 is an explanatory diagram of a communication area by the electromagnetic wave filter according to the embodiment. The communication area of the electromagnetic wave filter 100 having a combination of the convex shape and the concave shape described above and the intensity (electric field) of the radio wave in each of the states A to C are shown. An AP antenna 400 is provided at a position apart from the electromagnetic wave filter 100 by a predetermined distance (upper part in the drawing). Numerical values in the figure are, for example, the strength of radio waves (for example, received power mw).

(1) The transmission and reflection states of radio waves in the electromagnetic wave filter 100 portion are
In the state A (θ=90°), assuming that the intensity of the received radio wave is 100, the reflection (Pref.) is 100×0.8=80 and the transmission (Ppass) is 100×0.2=20.
In the state B (θ=30°), the distance from the AP (antenna 400) is larger than that in the state A. Therefore, when the intensity of the received radio wave is small and becomes 70, the reflection (Pref.) is 70×0.2=14. , And the transmission (Ppass) is 70×0.8=56.
In the state C (θ=15°), the distance from the AP (antenna 400) is larger than that in the state B, so that when the intensity of the received radio wave is small and is 50, the reflection (Pref.) is ×0.8=40, The transmission (Ppass) is ×0.2=10.

(2) The strength of the radio wave in the communication area 700 (and incommunicable area 701) is
In the state A′ (θ=90°), the intensity becomes 10 due to the distance attenuation from the AP (electromagnetic wave filter 100).
In the state B′ (θ=30°), the intensity is 12 because the distance from the electromagnetic wave filter 100 is larger than that in the state A′.
In the state C′ (θ=15°), the intensity is 1 because the distance from the electromagnetic wave filter 100 is larger than that in the state B′.

As shown in FIG. 7, according to the electromagnetic wave filter 100 of the embodiment, the communication area 700 can receive a radio wave having a substantially constant intensity (10 to 12). In addition, in the incommunicable area 701, the strength is sharply reduced (intensity 1), and the communication is impossible. As described above, according to the electromagnetic wave filter 100 of the embodiment, when the user's terminal (MS) 710 is located in the communication area 700, it is possible to receive a radio wave with a constant radio wave intensity. Further, when the user's terminal (MS) 710 is located in the communication-disabled area 701, the strength of the received radio wave may be sharply weakened so that it cannot be received. That is, the electromagnetic wave filter 100 of the embodiment can radiate (transmit) the radio wave radiated from the general-purpose AP (antenna 400) so that the radio wave intensity becomes constant only within the predetermined communication area 700.

FIG. 8 (FIGS. 8A and 8B) is a diagram showing a configuration example of a space electromagnetic field control system including an electromagnetic wave filter according to the embodiment. FIG. 8A is an exploded perspective view of the space electromagnetic field control system 800, and FIG. 8B is a view showing a mounting state.

As shown in FIG. 8A, the spatial electromagnetic field control system 800 includes a transmitter (AP) 810, the electromagnetic wave filter 100 described above, and a cover 820. AP 810 radiates a λ/4 vertically polarized radio wave from antenna 400. As described above, the electromagnetic wave filter 100 is arranged at a predetermined distance from the AP 810 (antenna 400) and is housed in the cover 820. The cover 820 is formed in a box shape that covers the electromagnetic wave filter 100 and the AP 810 with a material that transmits radio waves, for example, ABS resin. In the embodiment, the AP 810 is described as a transmitter, but the AP 810 also transmits/receives data to/from a terminal described later and has a function of a receiver.

Then, as shown in FIG. 8B, with the electromagnetic wave filter 100 and the AP 810 housed in the cover 820, the cover 820 can be easily attached to a desired wall or ceiling 830 installation site via bolts 821.

This space electromagnetic field control system 800 can be configured by accommodating the general-purpose AP 810 and the electromagnetic wave filter 100 described above in the cover 820, and can be manufactured easily and at low cost. Then, by attaching the cover 820 to a desired installation location, the radio waves emitted by the AP 810 can be communicated only with the terminal (MS) 710 located within the predetermined communication area 700.

FIG. 9 is a diagram illustrating a hardware configuration example of a transmitter of the spatial electromagnetic field control system according to the exemplary embodiment. The transmitter (AP) 810 has a general-purpose hardware configuration, and includes a CPU 901, a RAM 902, an RF-front end 903, a signal processing unit 904, an operation unit interface (IF) 905, a LAN port 906, a power supply port 907, and an antenna 400. including.

The CPU 901 executes the control program stored in the ROM, the RAM 902, etc. to control the entire AP 810, and uses the RAM 902 as a work area at this time. The RF-front end 903 transmits/receives data via the antenna 400 under the control of the wireless transmission/reception of the signal processing unit 904. The operation unit interface (IF) 905 is an interface for performing operation settings by the user. Data to be transmitted/received is input/output via the LAN port 906. The AP 810 operates based on the power supplied from the power port 907.

FIG. 10 is a diagram showing a hardware configuration example of a terminal of the spatial electromagnetic field control system according to the exemplary embodiment. The terminal (MS) 710 includes a CPU 1001, a RAM 1002, an RF-front end 1003, a signal processing unit 1004, and an operation unit interface (IF) 1005. Further, it includes a sensor 1006, a speaker 1007, a microphone 1008, a camera 1009, a keyboard 1010, a display 1011, a power source 1012, and an antenna 1013. The terminal (MS) 710 has each general-purpose hardware configuration such as a smartphone.

The CPU 1001 executes a control program stored in the ROM, the RAM 1002, and the like to control the entire terminal (MS) 710, and uses the RAM 1002 as a work area at this time. The RF-front end 1003 transmits/receives data via the antenna 1013 under the control of wireless transmission/reception of the signal processing unit 1004. The operation unit interface (IF) 1005 is an interface for performing operation settings by the user.

Under the control of the CPU 1001, the terminal (MS) 710 transmits the data input from the sensor 1006, the microphone 1008, the camera 1009, and the keyboard 1010, and displays the received data on the display 1011. The terminal (MS) 710 operates based on a power source supplied from a power source 1012 such as a built-in battery. In the example of FIG. 10, a configuration example of a smartphone or the like has been described as the terminal 710, but the terminal 710 also includes a simple one including a sensor such as an IoT sensor, a CPU, a memory, an RFID, and the like.

(Simulation of electric field distribution in communication area by spatial electromagnetic field control system)
Next, the electric field distribution in the communication area by the spatial electromagnetic field control system will be described. The communication frequency f0 was 5 GHz (λ=60 mm), and the input power to the electromagnetic wave filter 100 was 1 W.

FIG. 11 is a diagram showing a configuration example of the electromagnetic wave filter used for the simulation according to the embodiment. The electromagnetic wave filter 100 has a height (Z axis) and a width (X axis) of 200 mm×390 mm, and a vertical length (Y axis) of 26 mm. The electromagnetic wave filter 100 has a double-slot structure, and each bent curved surface 101 is formed in a wave shape inclined by 30° with respect to the Y axis. The length of one folding curved surface 101 is 30 mm, and the slot 102 is formed in each folding curved surface 101 with an opening width of 27 mm×2 mm. A plurality of slots 102 are provided at intervals of 27 mm in the Z-axis direction.

FIG. 12 is a diagram showing a simulation result of an electric field distribution of the electromagnetic wave filter according to the embodiment. The vertical and horizontal directions show the electric field distribution on the XY plane in the space of 300 mm×600 mm, and it can be seen that the electric field distribution of the electromagnetic wave filter 100 is confined in a rectangular shape. That is, it has an electric field distribution that spreads in the X-axis direction, which is the width of the electromagnetic wave filter 100, and the electric field strength is similarly low at the boundary (three sides) of the space on the transmission side of the electromagnetic wave filter 100, resulting in a rectangular space. The electric field distribution adapted to was obtained.

13 to 15 (FIGS. 15A and 15B) are diagrams showing various antenna characteristics when the electromagnetic wave filter according to the embodiment is used. FIG. 13A is a polar coordinate diagram (Smith chart) of the complex reflection coefficient Γ showing the input impedance characteristic, and the characteristic line S shows that the matching with the antenna 400 is good. FIG. 13B shows the reflection characteristic (S11) of the input, where the horizontal axis is the frequency and the vertical axis is the reflection amount, and it is shown that the broadband frequency characteristic can be maintained. It is also shown that the resonance point f0 (5 GHz) is not displaced even in the configuration using the electromagnetic wave filter 100.

FIG. 14A shows the XY plane gain characteristic, and FIG. 14B shows the three-dimensional (3D) gain characteristic. It is shown that a favorable gain characteristic of −2 to 4.5 dBi can be obtained in the desired radiation direction (+Y axis direction).

15A and 15B are diagrams showing electric field values at a predetermined distance from the electromagnetic wave filter 100. As shown in FIG. 15A, the electric field value above a predetermined distance (Y=200 mm) from the electromagnetic wave filter 100 is shown in FIG. 15B. The horizontal axis of FIG. 15B is the distance 0 mm to 600 mm in the horizontal direction (X axis) of the space, and the vertical axis is the electric field strength at each distance. As shown in FIG. 15B, a substantially constant electric field strength is obtained in a predetermined range 1501 (400 mm) up to a distance of 100 to 500 mm. Further, it is shown that the electric field strength sharply decreases in a range (distance 0 mm to 100 mm and distance 500 mm to 600 mm) outside the predetermined range 1501 (400 mm).

FIG. 16 is a diagram in which the communication area of the space electromagnetic field control system according to the embodiment is scaled up. Here, in a simulation using an actual computer, it is not possible to calculate a space within a range of several meters due to memory constraints, and in the illustrated example, a scaled up communication area of a predetermined vertical and horizontal range (1500 mm×3000 mm) is used. Shows a construction example of.

The example in FIG. 16 shows a case where the analysis space (300 mm×600 mm) is scaled up by about 5 times. The distance between the antenna 400 of the AP 810 and the electromagnetic wave filter 100 was 30 mm, and the distance between the electromagnetic wave filter 100 and the communication area 700 was 1200 mm. With this scale-up, the range of the communication area 700 in which the electric field is constant can be 1000 mm in the X-axis direction. Note that the example in FIG. 16 is an example in which the communication frequency (f0) is 5 GHz, and therefore, for example, if f0 is 2.4 GHz, each numerical value in FIG. 16 is approximately doubled, and the range of the communication area 700 is the X axis. Approximately 2000 mm in the direction.

FIG. 17 is a diagram showing a plurality of communication areas of the spatial electromagnetic field control system according to the embodiment. FIG. 17 shows a state in which a plurality of scaled-up communication areas shown in FIG. 16 are arranged in the X-axis direction (f0=5 GHz). In this way, by providing a plurality of communication areas 700 (A, B, C,...) Adjacent to each other with a small gap, it becomes possible to perform communication only within each communication area 700. .. In the example of FIG. 17, the communication area 700(B) is not interfered with by the adjacent communication area 700(A) and the communication area 700(C).

FIG. 18 is a diagram showing a construction example of a plurality of communication areas of the spatial electromagnetic field control system according to the exemplary embodiment. FIG. 18A is a communication area using the electromagnetic wave filter 100 according to the embodiment. FIG. 18B shows a communication area using a conventional dipole antenna for comparison. All of these figures are simulation results of the electric field distribution, and the vertical and horizontal (X, Y) range is 5 m×20 m.

The upper half of FIG. 18A shows a state in which two APs 810 (antenna 400) are arranged adjacent to each other at a predetermined distance (10 m) corresponding to two communication areas. Here, the AP 810 (antenna 400) is arranged at different positions in the Y-axis direction, and the radiation directions are opposite to each other. 18A shows a state where only one AP 810 (antenna 400) is arranged in the lower half portion.

As shown in FIG. 18A, the adjacent communication area 700(A) and communication area 700(B) each have a range of 6 m in the X-axis direction, and both ends of the communication area 700 have a distance of 0. It has an incommunicable area 701 of 5 m each (total of 1 m). In this case, the AP 810 (antenna 400) can be narrowed down to 7 m in the X-axis direction, preventing interference between the adjacent communication areas 700 (A) and 700 (B) and only within the accident communication area 700. Communication is possible.

On the other hand, in the conventional dipole antenna (antenna 400) shown in FIG. 18(b), as shown in the lower half of the figure, the uncommunicable area 1801 is located at a long distance from both ends of the communication area 1800 in the X-axis direction. positioned. Here, as shown in FIG. 18A, it is assumed that the APs 810 (antennas 400) are arranged at intervals of 10 m as in the embodiment. In this case, the incommunicable area (guard area) 1801 of the communication area 1800(A) overlaps with the other communication area 1800(B). Similarly, the guard area 1801 of the communication area 1800(B) overlaps with the other communication area 1800(A).

Due to this, in the conventional technology, one communication area 1800(A) interferes with another adjacent communication area 1800(B), and communication within one communication area 1800 is impossible. In this case, it is necessary to take measures such as different encryption for each communication area 1800, and security must be ensured.

FIG. 19 is a diagram illustrating a communication area using the electromagnetic wave filter according to the embodiment. With reference to FIG. 19, a communication area using the electromagnetic wave filter 100 according to the embodiment and a communication area using an antenna of the related art will be compared. FIG. 19A is a diagram showing an electric field distribution using the electromagnetic wave filter 100 according to the embodiment. FIG. 19(b) is a diagram showing an electric field distribution by the conventional dipole antenna, and FIG. 19(c) is a diagram showing an electric field distribution by the conventional planar patch antenna.

As shown in FIG. 19A, the electric field distribution of the electromagnetic wave filter 100 according to the embodiment is enclosed in a rectangular shape. In this case, there is an electric field distribution that spreads in the X-axis direction, which is the width of the electromagnetic wave filter 100, and the electric field strength similarly decreases at the boundary (three sides) of the space on the transmission side of the electromagnetic wave filter 100, resulting in a rectangular shape. The electric field distribution adapted to the space is obtained.

On the other hand, in the electric field distribution of only the dipole antenna 400 shown in FIG. 19(b), the radio waves radiated from the antenna 400 are spread radially (substantially circular). The dipole antenna 400 alone has a predetermined electric field strength even at the ends (0 mm, 600 mm) on the X-axis, for example, and radio waves cannot be confined in a rectangular area. Similarly for the patch antenna 1901 shown in FIG. 19C, the radio waves radiated from the patch antenna 1901 are spread radially and the radio waves cannot be confined in the rectangular area.

As described above, by using the electromagnetic wave filter 100 according to the embodiment, the radio waves radiated from the antenna 400 can be confined in a rectangular area such as a room.

FIG. 20 is a diagram showing an electric field distribution when the size of the width of the electromagnetic wave filter according to the embodiment is changed. In the above description, the width (X axis) of the electromagnetic wave filter 100 is 390 mm, but in FIG. 20, the width of the electromagnetic wave filter 100 is 630 mm and the width of the space area is 700 mm. When the width of the electromagnetic wave filter 100 is increased, the electric field strength at both ends of the width (X axis) can be more rapidly reduced. Therefore, the larger the width of the electromagnetic wave filter 100, the more the radio waves can be confined in the rectangular communication area. Since the width (X axis) of the electromagnetic wave filter 100 corresponds to the width of the space electromagnetic field control system 800 (cover 820), it is desirable that the width is appropriate from the viewpoint of practicality.

FIG. 21 is a diagram showing a state in which the height of the electromagnetic wave filter according to the embodiment is changed. In the above description, the height (Z axis) of the electromagnetic wave filter 100 is set to 26 mm (see FIG. 11). 21A, the height (Z axis) of the electromagnetic wave filter 100 was 140 mm, and in FIG. 21B, the height (Z axis) of the electromagnetic wave filter 100 was 90 mm. The electric field distribution in this case was almost the same as the above-mentioned electric field distribution (see FIG. 19 and the like). As described above, the electric field distribution in the XY plane does not change regardless of the height (Z axis) of the electromagnetic wave filter 100.

FIG. 22 is a diagram showing an application example of the space electromagnetic field control system according to the embodiment. According to the space electromagnetic field control system 800 of the embodiment, the following 1. ~3. Applicable to
1. It is possible to construct a radio-wave closed space for each adjacent desired communication area.
2. It can prevent unwanted radiation outside the desired area and reduce the risk of interception in public places.
3. It is possible to provide a wireless environment in a space where electromagnetic waves are a concern.

Above 1. 22A, for example, as shown in FIG. 22A, a component equipped with an IoT sensor (corresponding to the terminal 710) conveyed on the lanes L1 to L3 for each of the manufacturing lines (lanes) L1 to L3 of the factory. And management of materials.

The above-mentioned space electromagnetic field control system 800 (the cover 820 housing the AP 810 and the electromagnetic wave filter 100) is arranged for each of the lanes L1 to L3. Thereby, independent communication areas 700 can be constructed in the lanes L1 to L3. For example, the IoT sensor (corresponding to the terminal 710) carried on the lane L1 can communicate with the AP 810 on the lane L1 when it is located in the communication area 700. At this time, the IoT sensor (corresponding to the terminal 710) is not located in the communication area 700 of the APs 810 of the other lanes L2 and L3, and does not communicate with the AP 810 of these other lanes L2 and L3. Radio waves in the communication area 700 of the lane L1 do not leak to the communication areas 700 of the other adjacent lanes L2 and L3, so that the communication data between the AP 810 and the IoT sensor (corresponding to the terminal 710) in the lane L1 is transmitted. Security can be secured. Furthermore, security measures such as special encryption can be eliminated.

Also, it is not limited to the application example to the lane, but it can be applied to provide information for each adjacent booth at an exhibition hall or an aquarium, and to ensure security at different departments (islands of desks) adjacent to each other in the same office. Also, it can be applied to secure security at different stores adjacent to each other in the same building, and to manage reading by only the person to be checked at an entrance gate where exhibitions and festivals are crowded.

↑ 2. Can be applied to, for example, a waiting room at a station or an airport, a seat of a train or an airplane, a seat of a restaurant or the like. For example, as shown in FIG. 22B, the space electromagnetic field control system 800 (the cover 820 that houses the AP 810 and the electromagnetic wave filter 100) is arranged on the ceiling or floor of each of the train sheets N1 to N3. .. As a result, the communication areas 700 that are independent of the sheets N1 to N3 can be constructed. Then, since the radio waves in the communication area 700 of the sheet N1 do not leak to the communication areas 700 of the other adjacent sheets N2 and N3, communication data between the AP 810 and the user terminal 710 (MS) on the sheet N1. The security of can be secured. Furthermore, security measures such as special encryption can be eliminated.

↑ above 3. Can be applied to, for example, a hospital or a server room. According to the embodiment, since the communication area 700 can be constructed only in a predetermined area, unnecessary electromagnetic waves are not given to the medical equipment in the hospital and the server. That is, according to the embodiment, it is possible to construct the communication area 700 in which radio waves are confined even in a hospital or a server room.

The electromagnetic wave filter of the above-described embodiment is provided on the direction of emission of radio waves from the antenna and controls the electric field distribution. This electromagnetic wave filter is made of a conductor, has a plurality of bent curved surfaces, and has slots formed on the bent curved surfaces to form a substantially constant electric field in a predetermined communication area. In addition, the electric field is sharply weakened outside the communication area. Thereby, the radio waves can be confined within the communication area.

By combining such an electromagnetic wave filter with a general-purpose wireless router or AP, it is possible to prevent leakage of radio waves outside the communication area with a simple configuration and improve security. For example, it becomes possible to arrange the communication areas so that terminals and sensors of different wireless communication systems do not interfere with each other. In this case, means such as encryption for each different wireless communication system can be eliminated.

Further, the bent surface has a predetermined angle with respect to the incident direction of the radio wave of the antenna, the slot is opened with a predetermined length in the direction orthogonal to the polarization direction of the antenna, and the length is equal to the wavelength of the radio wave. It may be about ½. The angle of the curved surface may be such that the transmitted wave is the smallest and the reflected wave is the largest when the slot is used alone. As a result, the slot located on the direction of emission of radio waves from the antenna has a low radio wave transmittance and a high radio wave reflectance. Further, the slot having the bent surface at the portion having the predetermined angle has a large transmittance and a small reflectance of the radio wave obliquely incident from the antenna. The radio wave incident further obliquely from the antenna has a low transmittance and a high reflectance. As a result, the radio wave emitted from the antenna at the fixed position is transmitted or reflected at different angles for each slot, and the intensity of the radio wave after passing through each slot can be controlled, and a communication area of a predetermined shape can be constructed. ..

For example, the electromagnetic wave filter may have a substantially wave-shaped shape in which a bent surface has a V-shape and an inverted V-shape having a predetermined angle with respect to the incident direction of radio waves, and are alternately arranged. For example, the angle of the curved surface is 30°. The angle of the curved surface of the electromagnetic wave filter may be a predetermined angle based on the electric field distribution and electric field strength in the communication area. Thereby, for example, a substantially rectangular communication area can be constructed.

Also, the width of the entire bent surface of the electromagnetic wave filter can be a predetermined width according to the size of the communication area. By enlarging the electromagnetic wave filter in the width direction, it becomes possible to suppress the electromagnetic waves from entering the communication area.

Further, the space electromagnetic field control system of the embodiment can be configured by the above electromagnetic wave filter, an access point equipped with an antenna, and a cover that houses the access point and the electromagnetic wave filter. The cover can be easily attached to a place where a predetermined communication area is constructed. Further, the movable terminal can communicate with the access point only when it is located in the communication area.

Also, by arranging a plurality of communication areas adjacent to each other with a predetermined interval, terminals located in the communication area can communicate only with access points in this communication area. Since each communication area does not interfere with an adjacent communication area, security can be maintained even if a different encryption means for each communication area is unnecessary.

Also, the plurality of communication areas may be arranged with an interval such that the incommunicable areas having a predetermined electric field located at both ends of the communication area do not overlap the incommunicable areas of other adjacent communication areas. This allows the communication areas to be as close to each other as possible. In other words, the distance between adjacent access points can be made as short as possible, and the communication areas can be divided and arranged even in a small space.

100 Electromagnetic wave filter 100a Incident surface 101 Folded curved surface 102 Slot 400, 1013 Antenna (dipole antenna)
700 Communication Area 701 Incommunicable Area 710 Terminal 800 Spatial Electromagnetic Field Control System 810 AP (Access Point)
820 Cover 830 Ceiling 901, 1001 CPU
902,1002 RAM
903, 1003 RF- front end 904, 1004 Signal processing unit 1800 Communication area 1801 Communication disabled area (guard area)

Claims (10)

1. An electromagnetic wave filter which is provided on the emitting direction of the radio waves of the antenna and controls the electric field distribution,
   It is made of a conductor and has a plurality of bent curved surfaces and a slot formed in the bent curved surfaces, and a substantially constant electric field is formed in a predetermined communication area, and the electric field is sharply weakened outside the communication area.
   An electromagnetic wave filter characterized by the above.
2. The bent surface forms a predetermined angle with respect to the emission direction,
   The electromagnetic wave according to claim 1, wherein the slot is opened with a predetermined length in a direction orthogonal to a polarization direction of the antenna, and the length is about ½ of a wavelength of a radio wave. filter.
3. The electromagnetic wave filter according to claim 2, wherein the angle of the curved surface is the angle at which the transmitted wave is the smallest and the reflected wave is the largest when the slot is used alone.
4. The electromagnetic wave filter according to claim 1, wherein the bent curved surface has a substantially wavy shape in which V-shaped and inverted V-shaped having a predetermined angle with respect to the emission direction are alternately arranged.
5. The electromagnetic wave filter according to claim 4, wherein the angle of the curved surface is a predetermined angle based on the electric field distribution and electric field strength in the communication area.
6. The electromagnetic wave filter according to claim 2, wherein the angle of the bent surface is 30°.
7. The electromagnetic wave filter according to any one of claims 1 to 6, wherein the entire width of the curved surface is a predetermined width according to the size of the communication area.
8. An access point with an antenna,
   An electromagnetic wave filter provided on the emitting direction of the radio wave of the antenna and controlling the electric field distribution,
   A cover that accommodates the access point and the electromagnetic wave filter and is attached to a portion that builds a predetermined communication area,
   A terminal that communicates with the access point when located in the communication area,
   The electromagnetic wave filter,
   It is made of a conductor and has a plurality of bent curved surfaces and a slot formed in the bent curved surfaces, and a substantially constant electric field is formed in a predetermined communication area, and the electric field is sharply weakened outside the communication area.
   A space electromagnetic field control system characterized by the above.
9. The space electromagnetic field control system according to claim 8, wherein a plurality of the communication areas are arranged adjacent to each other with a predetermined interval.
10. The plurality of communication areas are arranged such that communication-disabled areas having a predetermined electric field located at both ends of the communication area do not overlap communication-disabled areas of other adjacent communication areas. The space electromagnetic field control system according to claim 9.

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