JP6905191B2 - Lens and compound eye lens - Google Patents

Description

The present invention relates to lenses and compound eye lenses.

In the 5th generation mobile communication system (hereinafter referred to as "5G"), it is considered to develop a base station having a wide range of radio waves (hereinafter referred to as "macrocell base station"). Further, in 5G, it is being considered to deploy not only macrocell base stations but also base stations with a narrow range of radio waves (hereinafter referred to as "small cell base stations") in areas where people are crowded. .. Furthermore, in 5G, the load on small base stations is reduced by installing IoT (Internet of things) devices that have wireless communication functions and various measurement functions in the city and offloading the traffic of small base stations. Therefore, it is being considered to install a wireless LAN (Local Area Network) access point. Therefore, in 5G, it is necessary to install not only microcell base stations and small cell base stations but also a large number of IoT devices and wireless LAN access points. Hereinafter, when a device used for wireless communication such as an IoT device and a wireless LAN access point is not distinguished, it is referred to as a wireless device.

FIG. 19 is a diagram showing a usage example of a conventional small cell base station. When the small cell base station 801 is installed on the street where the buildings 800 are lined up as shown in FIG. 19 (for example, Chuo-dori in Ginza), the place where the small cell base station is installed is a relatively high place on the wall surface of the building 800 (for example,). For example, 20 [m]) from the ground can be considered. By installing the small cell base station 801 at a relatively high place on the wall surface of the building 800, it becomes possible to provide a wireless communication service to a user on the sidewalk. However, when a large number of small cell base stations 801 and wireless devices are installed on the wall surface of a building, the landscape of the street may be impaired. Therefore, paying attention to the fact that the signboard 802 is installed at a relatively high place in many buildings 800, the small cell base station 801 or the wireless device is located inside the signboard surface of the signboard 802 (hereinafter referred to as "inside the signboard"). It has been proposed to install. In this case, the signboard 802 becomes an obstacle that hinders the propagation of electromagnetic waves. Therefore, by installing the small cell base station 801 and the wireless device in the signboard, wireless communication on the street where the buildings are lined up becomes possible without spoiling the landscape. Further, when the small cell base station 801 or the wireless device is installed in the signboard, since the power supply cable has already been laid in many signboards 802, it is not necessary to newly lay the power supply cable. The data received by the small cell base station 801 is transmitted to the entrance base station 803, and is transmitted to the base station control device by microwave, light, or the like. Then, it is further transmitted to the aggregation station 804 of a telecommunications carrier or the like by an optical line or the like.

FIG. 20 is a diagram showing a usage example of a conventional small cell base station. As the place where the small cell base station is installed, in addition to the street where the buildings are lined up, for example, a concourse of a station, an underground shopping mall around the station, a department store, or the like can be considered. In such cases, it has been proposed to install wireless devices on ceilings, pillars, walls, and the like. However, even in this case, the landscape may be spoiled. Therefore, as shown in FIG. 20, paying attention to the fact that the lighting equipment 903 is already installed on the ceiling 900, the pillar 901, the wall 902, etc., the small cell base station and the wireless device 904 are installed inside the housing of the lighting equipment 903. It is proposed to do. In the lighting device 903, the glove is an obstacle to electromagnetic waves. Therefore, by installing the small base station and the wireless device 904 inside the lighting device 903, wireless communication at a station concourse or the like becomes possible without spoiling the landscape. Further, since the power supply line is already laid in the lighting equipment 903, it is not necessary to newly lay the power line. The data received by the wireless device 904 is transmitted to the network connection point 905, and is transmitted to the network 907 (such as the Internet / intranet) via the gateway device 906 via Ethernet (registered trademark), optical fiber, or the like. ..
When the wireless device 904 taken up in FIG. 20 is an IoT device, the area shown by hatching in FIG. 20 (corresponding to the “communicable range” in the small cell base station) is, for example, the IoT device (pyroelectric sensor / infrared ray). If it is a motion sensor (such as a sensor or a fish-eye type surveillance camera), it represents the range in which it is possible to detect a person who is indoors, indoors, in a facility, or moving. In addition, if the IoT device uses infrared rays to detect a hot spot from a distance, or if it is an illuminance sensor that catches the light of a flame with high sensitivity, it can detect the outbreak of a fire. It can also be called a range. Then, the wireless device 904 equipped with these wireless communication functions can be installed inside the lighting device 903.

In this way, according to the above study assuming 5G, it is expected that the chances of installing wireless devices inside signboards and lighting equipment will increase in the future.

Takahiro Tsuchiya, Kazuto Goto, Mizuki Suga, Toshisho Huang, Hideyuki Tsuboi, Satoshi Kurosaki, Atsushi Ota, Masataka Iizuka, "Experimental Evaluation of Radio Entrance Environment for Street Small Cell Base Stations by 75GHz Band Propagation Measurement" IEICE Technical Report RCS2017-74 (2017-06)

However, when the wireless device is installed in a structure such as a signboard or a lighting device, a part of the electromagnetic wave output by the wireless device is reflected by an obstacle. Therefore, there is a problem that the communicable distance of the wireless device is shortened because the intensity of the electromagnetic wave transmitted through the obstacle is reduced due to the generation of the reflected wave.

In view of the above circumstances, an object of the present invention is to provide a technique capable of suppressing a decrease in the communicable distance.

In one aspect of the present invention, _{a plurality of thin films having a refractive index of n c with} respect to an electromagnetic wave having a wavelength λ propagating in a medium having _{a refractive index of n 1} are arranged in layers, and a part or all of the plurality of thin films has a convex lens shape. The thin film having substantially the same shape, n _c = (n ₁ × n ₂ ) ^1/2 , and having the largest area among the plurality of thin films transmits the electromagnetic waves at a predetermined transmittance. the electromagnetic wave of the surface obstacle to have the contact with the surface on the side where incident, thickness in a direction perpendicular to the surface of the plurality of thin film is an odd multiple of _{λ / (4 × n c)} , the lens Is.

In one aspect of the present invention, _{a plurality of thin films having a refractive index of n 2 with} respect to an electromagnetic wave having a wavelength λ propagating in a medium having _{a refractive index of n 1} are arranged in layers, and a part or all of the plurality of thin films has a convex lens shape. The thin film having substantially the same shape and having the largest area among the plurality of thin films is on the surface of the obstacles that transmit the electromagnetic waves at a predetermined transmittance on the side on which the electromagnetic waves are incident. The lenticular member in contact and the _{surface of the obstacle having a refractive index of n 2} and having a refractive index of n ₂ are parallel to the surface in contact with the thin film having a refractive index of n ₂ . A thin film-like member in contact with a surface existing on the opposite side of the surface in contact with the thin film is provided, and the thickness of the lens-like member in a direction perpendicular to the surface on the side where the electromagnetic wave is incident and the electromagnetic wave of the obstacle are incident. The total thickness of the thickness in the direction perpendicular to the surface of the thin film member and the thickness of the thin film member in the direction perpendicular to the surface on which the electromagnetic wave is incident is an odd multiple of _{λ / (4 × n 2).} Is a lens.

One aspect of the present invention is the above-described lens, the distance d _in the first antenna for radiating said electromagnetic wave and said plurality of thin film having a substantially identical shape to the shape of the convex lens, the first When the opening length D of the antenna and d _in ≧ 2D2 / λ, the shape substantially the same as the shape of the convex lens determines the distance between the first antenna and the second antenna that receives the electromagnetic wave. If the d _all, that the sum _{d l} of the thickness of said plurality of thin film having a substantially identical shape to the shape of the convex _{lens, R = (n c -1)} d f, d f = d all - (d It is a shape in contact with a spherical surface having a radius of curvature R that satisfies _in + d _l).

One aspect of the present invention is the above-described lens, the distance d _in the first antenna for radiating said electromagnetic wave and said plurality of thin film having a substantially identical shape to the shape of the convex lens, the first When the length D of the opening of the antenna and d _in <2D ² / λ, the shape substantially the same as the shape of the convex lens becomes a spherical surface having a radius of curvature R satisfying _{R = (n c} -1) d _in. It is a contacting shape.

One aspect of the present invention is a compound eye lens including a plurality of the above lenses.

According to the present invention, it is possible to extend the communicable distance.

The figure which shows the specific example of the conventional wireless communication system 7. The figure which shows the specific sectional view of the transmission member 1 of 1st Embodiment. The figure which shows the concrete structure which saw the transmission member 1 of 1st Embodiment from the transmission antenna 701 side. The figure explaining the radius of curvature R1 in the case where the transmission member 1 of 1st Embodiment is far enough away from a transmitting antenna 701. The figure explaining the radius of curvature R2 in the case where the transmission member 1 of 1st Embodiment is in the vicinity of transmission antenna 701. The figure explaining the principle that the transmission member 1 of 1st Embodiment can suppress a reflected wave. The figure which shows the specific example in the case where the first thin film 11 which touches an obstacle 702 does not touch a circle of curvature radius R1. The figure which shows the specific sectional view of the transmission member 2 of the 2nd Embodiment. The figure which shows the use example of the transmission member 2 of the 2nd Embodiment in the wireless communication system 7 of FIG. FIG. 9 is a diagram of simulation results showing the relationship between the radius of curvature R2 of the transmitting member 2 and the distance dollar between the transmitting antenna 701 and the receiving antenna 703. The figure which shows the relationship between the horizontal distance din + dL2 between a transmitting antenna 701 and an obstacle 702, and the radius of curvature R2 of a transmission member 2. The figure which shows the specific example in the case where the 2nd thin film 12 which touches an obstacle 702 does not touch a circle of radius of curvature R2. The figure which shows the specific example of the structure which saw the transmission member 1 of the modification from the front. The figure which shows the specific arrangement of the transmission member 1 when a plurality of transmission members 1 are in contact with an obstacle 702. FIG. 3 is a diagram showing a specific arrangement of the transparent members 1 when a plurality of transparent members 1 of the modified example shown in FIG. 13 are arranged in the YZ plane. The figure which shows the path of the electromagnetic wave propagating the obstacle 702. The figure which shows the specific example when the transmission member 1 or 2 is used in the non-approximate establishment system. The figure which shows the path of the electromagnetic wave propagating the obstacle 702a. The figure which shows the use example of the conventional small cell base station. The figure which shows the use example of the conventional small cell base station.

(Summary)
FIG. 1 is a diagram showing a specific example of the conventional wireless communication system 7. The conventional wireless communication system 7 has a transmitting antenna 701, an obstacle 702, and a receiving antenna 703. In FIG. 1, the X-axis of the XYZ coordinate system, which is a Cartesian coordinate system, is an axis parallel to the horizontal direction, and the Y-axis is an axis parallel to the vertical direction.

The transmitting antenna 701 is provided in, for example, a small cell base station, an IoT device, a wireless LAN access point, or the like. The transmitting antenna 701 has an aperture diameter of D. The transmitting antenna 701 exists at a position where the coordinates of its own center point are h _{1 with a predetermined position as the coordinate origin.} In the following, the presence in such a position, at the position of the height h _1, and expressed. The coordinate origin may be, for example, the ground surface.

The obstacle 702 is a member that transmits an incident electromagnetic wave at a predetermined transmittance, and is, for example, a signboard surface or a glove of a lighting device. The thickness of the obstacle 702 (i.e., the width of the X-axis direction) is _{d b.} The refractive index of the obstacle 702 with respect to an electromagnetic wave having a wavelength λ is n ₂ .

The receiving antenna 703 is provided in, for example, an entrance base station or a network connection point. Receive antenna 703 to the transmitting antenna 701, exists at a distance _{d all} away in the X-axis direction. The receiving antenna 703 _{exists at a height h 2} which is _{separated from h 1 by H 1 in the} positive direction of the Y axis. The difference in the vertical distance between the receiving antenna 703 and the transmitting antenna 701 is sufficiently shorter than the difference in the horizontal distance between the receiving antenna 703 and the transmitting antenna 701. That, H1 satisfies the relation of H1 _{<< d all.}
The transmitting antenna 701, the obstacle 702, and the receiving antenna 703 are arranged in the order of the transmitting antenna 701, the obstacle 702, and the receiving antenna 703 in the X-axis direction.

A part of the electromagnetic wave radiated by the transmitting antenna 701 _{propagates in the outside air having a refractive index of n 1 in the direction of an angle θ a} with respect to the horizontal direction, and passes through the obstacle 702. Electromagnetic waves transmitted through the obstacle 702, propagates in the direction of the angle theta _a fresh air in the refractive index n ₁ with respect to the horizontal direction reaches the receiving antenna 703. Note that θ _a satisfies the relationship of tan (θ _a ) = H1 / d _all.

The difference H1 of the vertical distance between the receiving antenna 703 and transmitting antenna 701 is sufficiently shorter than the difference _{d all} the horizontal distance between the receiving antenna 703 and transmitting antenna 701, a H1 _{/ d all} ≒ 0. That, theta _a satisfy the relationship of θ _a ≒ 0. This means that the angle of incidence of the electromagnetic wave on the obstacle 702 is close to 0 deg, and that the refraction angle of the refraction of the electromagnetic wave by the obstacle 702 can be approximated to 0.

In a wireless communication system 7, the electromagnetic wave passing through the obstacle 702, distance traveled in the obstacle 702 is _{d b / cos (θ a)} . In the wireless communication system 7, the distance the electromagnetic wave travels in the obstacle 702 are substantially the same length in the d _b. For simplicity below, particularly unless otherwise specified, a theta _a ≒ 0, in a wireless communication system 7, the distance electromagnetic waves traveling in the obstacle 702 will be described as a d _b.

For example, a street lined with outdoor buildings is an example of a usage scene of the wireless communication system 7. In this case, the transmitting antenna 701 may be installed inside a signboard on the building wall, for example. In this case, for example, the height difference H1 between the transmitting antenna 701 and the receiving antenna 703 is 7 m, and the horizontal distance is d _all. May be 70 m. Further, for example, a station concourse is an example of a usage scene of the wireless communication system 7. The transmitting antenna 701 may be installed in a lighting device installed on an indoor wall or pillar. In this case, for example, the height difference H1 between the transmitting antenna 701 and the receiving antenna 703 (NW connection point or the like) may be 3 m, and the horizontal distance _dall may be 30 m. In these usage scenes, _{the relationship of 10 ≦ d all} / H1 and the relationship of θ _a <5.71 deg are satisfied. That is, in this case, 1 / cos (θ _a ) is about 1.005, which is substantially the same as 1.

The wireless communication system 7 is not limited to such a system, the transmitting antenna 701, the obstacle 702 and receiving antenna 703, transmits to meet theta _a ≒ 0 antenna 701, the obstacle 702 and the receiving antenna 703 Any wireless communication system may be used as long as it is a wireless communication system arranged in the order of.

In each of the embodiments described below, the communicable distance is shortened by arranging the transmission member configured to satisfy a predetermined condition on the obstacle 702 of the conventional wireless communication system shown in FIG. Suppress.

Hereinafter, the transparent member of the embodiment will be described with reference to the drawings.

(First Embodiment)
FIG. 2 is a diagram showing a specific cross-sectional view of the transmission member 1 of the first embodiment. The transmission member 1 is in contact with the surface on the transmitting antenna 701 side of the surfaces parallel to the YZ plane of the obstacle 702 in the wireless communication system 7 of FIG. The transmitting member 1 suppresses the reflection of the incident electromagnetic wave on the surface of the obstacle 702, and collects the incident electromagnetic wave on the receiving antenna 703. The XYZ coordinates in FIG. 2 are the same as the XYZ coordinates in FIG.

The transmission member 1 includes a first thin film 11-1 to 11. The first thin films 11-1 to 5 have a thickness of d _s1 , and as will be described later, the total thickness of the first thin films 11-1 to 5 laminated is d _L1 and the refractive index is n _c. It is a thin film of a dielectric of. The refractive index n _c is
n _c = (n ₁ x n ₂ ) ^1/2 ... (1)
Meet.
The total thickness d _L1 is
d _L1 = m × λ / ( 4 × n _c ) ・ ・ ・ (2)
Satisfy the relationship. In this equation (2), m is an odd number (m = 1, 3, 5, ...), And λ is the wavelength of the electromagnetic wave incident on the transmitting member 1 in vacuum. The first thin film 11-1～5 Although each have the same thickness _{d s1} and refractive index _{n c,} shape or size is different. The first thin film 11-5 is in contact with the obstacle 702. The surface of the first thin film 11-5 in contact with the obstacle 702 is a surface perpendicular to the X-axis positive direction (that is, the thickness direction).

FIG. 3 is a diagram showing a specific configuration of the transmission member 1 of the first embodiment as viewed from the transmission antenna 701 side. The first thin films 11-1 to 11-5 are circular in the YZ plane, and the first thin film 11-1, the first thin film 11-2, the first thin film 11-3, the first thin film 11-4, The radius is shorter in the order of the first thin film 11-5.

Returning to the description of FIG. The first thin films 11-1 to 5 are the first thin film 11-1, the first thin film 11-2, the first thin film 11-3, the first thin film 11-4, and the first thin film 11-5. It is layered in the order of. More specifically, the first thin films 11-1 to 11-5 are laminated so as to form substantially the same shape as the convex lens shape. Therefore, the transmission member 1 functions as a convex lens that collects the incident electromagnetic wave. _{The thickness d L1} of the transmissive member 1 in the X-axis direction is the thickness of the first thin films 11-1 to 11-5 stacked (laminated) as described above, and in the example of FIG. 2, d _L1 The relationship of = d _s1 × 5 is satisfied. Therefore, from the above equation (2), d _s1 = (m / 5) × λ / ( 4 × n _c ). Here, m is an odd number.

The radius of curvature of the convex lens-like shape formed by the first thin films 11-1 to 11-5 is length R1. That is, the size of the first thin films 11-1 to 5 is a size adjusted so as to be in contact with the boundary of a circle having a radius of curvature R1. The radius of curvature R1 is calculated by the same method as the method for calculating the length of the radius of curvature of a commercially available lens, based on the distance between the transmitting antenna 701, the obstacle 702, and the receiving antenna 703.

Hereinafter, a thin film having a refractive index satisfying the relation of the formula (1) and a thickness satisfying the relation of the formula (2) is referred to as a first thin film 11.
The transmissive member 1 does not necessarily have to include the five first thin films 11, and if m is an odd number and the total thickness of the plurality of laminated members is m / 4 times the wavelength in the substance, how many sheets are there. It may be.
Further, the transmission member 1 of the embodiment does not necessarily have to be composed of the first thin film 11 having the same thickness, but is composed of a plurality of thin films _{having a refractive index of (n 1} × n ₂ ) ^1/2. , The thickness of the transmissive member 1 (that is, the width in the X-axis direction, d _L1 in FIG. 2) is an odd multiple of 1/4 of the wavelength in the substance, and the shape of the transmissive member 1 is substantially the same as that of the convex lens. Any shape may be used as long as it has a shape.
Further, the transmission member 1 may be formed by laminating the first thin films 11 like a seal, or may be formed by laminating the first thin films 11 with each other with an adhesive.

FIG. 4 is a diagram illustrating a radius of curvature R1 when the transmission member 1 of the first embodiment is sufficiently far from the transmitting antenna 701.

In FIG. 4, the arrangement of the transmitting antenna 701, the obstacle 702, and the receiving antenna 703 is the same as that of the wireless communication system 7 of FIG.
Further, in FIG. 4, the transmission member 1 is sufficiently far from the transmitting antenna 701. Therefore, the electromagnetic wave radiated by the transmitting antenna 701 is approximately a plane wave on the incident surface of the transmitting member 1. For example, if the distance between the transmitting antenna 701 and the transmission member 1 and _{d in, d in satisfy} the relation of _{d in} ≧ 2D ² _λ.

In general, the length r ₀ the radius of curvature of the convex lens for converging the focus of the focal length f ₀ of the electromagnetic wave of a plane wave incident on itself, the refractive index of the outside air is 1, the refractive index of itself as n _0, r ₀ = (N _0-1 ) f ₀ relationship is satisfied.
On the other hand, the transmitting member 1 in FIG. 4 collects electromagnetic waves, which are plane waves radiated by the transmitting antenna 701 and incident on the transmitting member 1, to the receiving antenna 703.
Therefore, in FIG. 4, the radius of curvature R1 of the transmissive member 1 whose _{focal length is substantially the same as d f is}
R1 = (n _c -1) d _f ... (3)
It is expressed as. Note that d _f is the horizontal distance between the receiving antenna 703 and the surface of the obstacle 702 on the transmitting antenna 701 side. That, _{d f} is the sum of the _{d out} and _{d b} in FIG. That is, when transmitting member 1 in the situation shown in FIG. 4 is sufficient distant to the transmitting antenna 701, the above equation for the radius of curvature (3) _{R1 = (n c -1) (} d out + d b) It becomes. Note that d _out is the horizontal distance between the receiving antenna 703 and the surface of the obstacle 702 on the receiving antenna 703 side.

FIG. 5 is a diagram illustrating a radius of curvature R2 when the transmitting member 1 of the first embodiment is in the vicinity of the transmitting antenna 701.

In FIG. 5, the arrangement of the transmitting antenna 701, the obstacle 702, and the receiving antenna 703 is the same as that of the wireless communication system 7 of FIG. Further, in FIG. 5, the transmission member 1 is in the vicinity of the transmitting antenna 701. Therefore, the electromagnetic wave radiated by the transmitting antenna 701 is approximately a spherical wave on the incident surface of the transmitting member 1. _{For example, the distance d in} between the transmitting antenna 701 and the transmitting member 1 satisfies the relationship of di _in <2D ^{2 λ.}

In FIG. 5, the electromagnetic wave radiated from the point P on the transmitting antenna 701 passes through the transmitting member 1 to become a plane wave, propagates in the outside air, and reaches the receiving antenna 703.
Therefore, a focal length d _in, the curvature radius R1 of the transmitting member 1 in FIG. 4,
R1 = (n _c -1) d _in ... (4)
Satisfy the relationship.

In FIG. 5, the electromagnetic wave transmitted through the transmitting member 1 is not focused on one point on the receiving antenna 703. However, the electromagnetic wave transmitted through the transmitting member 1 is converted into a plane wave electromagnetic wave in which the diffused spherical wave electromagnetic wave is not diffused and received by the receiving antenna 703. Hereinafter, this case is also referred to as light collection.

FIG. 6 is a diagram for explaining the principle that the transmitting member 1 of the first embodiment can suppress the reflected wave.

In FIG. 6, the incident wave _Li 1 and the incident wave _Li 2 are electromagnetic waves that propagate in the outside air in the same phase and are incident on the transmitting member 1. The incident wave _Li 1 is reflected at the boundary between the transmitting member 1 and the obstacle _{702, propagates through the obstacle 702 as the reflected wave LR} 1, and is emitted to the outside air. The incident wave _Li 2 is reflected at the boundary between the outside air and the transmitting member 1, and propagates in the outside air as the _{reflected wave LR 2.} Hereinafter, when the incident wave _Li 1 and the reflected wave L _R 1 are not distinguished, they are referred to as an electromagnetic wave L1. Further, hereinafter, when the incident wave _Li 2 and the reflected wave _LR 2 are not distinguished, it is referred to as an electromagnetic wave L2.

Generally, electromagnetic waves are reflected at points where substances having different refractive indexes come into contact with each other. That is, a reflected wave is generated by an electromagnetic wave incident on a portion where substances having different refractive indexes are in contact with each other. However, when the phase difference of the reflected waves of the electromagnetic waves reflected at the plurality of locations is an odd multiple of 180 degrees, the reflected waves cancel each other out. Therefore, the generation of reflected waves is suppressed.

The transmission member 1 has a structure in which a plurality of thin films are laminated, and the total thickness of the laminated thin films has a wavelength in the substance (that is, λ / n _c ) of m / 4 (m: odd number). Therefore, the electromagnetic wave L1 incident on the transparent member 1, before it is emitted to the outside as a reflected wave L _{R 1,} is as long propagation distance to a half wavelength of the odd multiple compared with the electromagnetic wave L2. Therefore, the electromagnetic wave L1 has a phase that is substantially the same as that of the electromagnetic wave L2 by an odd multiple of 180 degrees due to propagation.

Further, the transmission member 1 includes a first thin film 11 having _{a refractive index of (n 1} × n ₂ ) ^1/2. _{The formula of n c} = (n ₁ × n ₂ ) ^1/2 satisfied by the refractive index of the first thin film 11 is a formula generally known as a formula for giving the refractive index of the antireflection film of the optical element. Since the refractive index of the transmitting member 1 _{satisfies the equation of n c} = (n ₁ × n ₂ ) ^1/2 , the phase shift when the electromagnetic wave L1 is incident on the obstacle 702 from the transmitting member 1 and reflected, and the electromagnetic wave It is substantially the same as the phase shift when L2 is incident on the transmitting member 1 from the outside air and reflected.

As described above, the transmissive member 1 has a refractive index of (n ₁ × n ₂ ) ^1/2 , is provided with a plurality of first thin films 11 laminated in layers, and m is an odd number, and the total thickness is a substance. since the inner wavelength is of m / 4, they cancel each other in the outside air and the reflected wave _{L R} 2 of the reflected wave _{L R} 1 and an electromagnetic wave L2 of the electromagnetic wave L1. Therefore, the transmitting member 1 suppresses the generation of reflected waves.

Further, in the transmission member 1 configured in this way _{, a plurality of first thin films 11 having a refractive index of (n 1} × n ₂ ) ^1/2 are laminated in layers, and m is an odd number, and the total thickness is set. Since the wavelength is m / 4 in the substance, the generation of the reflected wave of the electromagnetic wave incident on the obstacle 702 is suppressed, and the electromagnetic wave is focused on the receiving antenna 703 to extend the communicable distance of the transmitting antenna 701. Can be done. In particular, when a small wireless device such as an IoT device is used, the gain cannot be earned so much and the communication distance becomes short, but the communication possible distance can be extended by the transmission member 1 configured in this way.
Further, the transmission member 1 configured in this way can extend the communicable distance of the transmitting antenna 701 only by being installed on the surface of the obstacle 702. Therefore, for example, according to the transmission member 1 of the embodiment, the size of the device for extending the communicable distance is large as compared with the method of increasing the gain of the amplifier corresponding to the expansion of the antenna diameter to be used and the amplification of the weak signal. It is possible to extend the communicable distance while suppressing the increase in installation costs.

(Modification example)
FIG. 7 is a diagram showing a specific example in the case where the first thin film 11 in contact with the obstacle 702 does not contact the circle having the radius of curvature R1. The transmission member 1 of FIG. 7 includes a first thin film 11-6 in place of the first thin film 11-1 of the transmission member 1 of FIG. The refractive index and thickness of the first thin film 11-6 are the same as those of the first thin film 11. The first thin film 11-6 has the same area as or larger than that of the first thin film 11-4 (see FIGS. 13 and 14 described later). The first thin film 11-6 touches the obstacle 702 and does not touch the circle with radius of curvature R1. The first thin film 11-6 has an area equal to or larger than that of the first thin film 11-4, has the same refractive index and thickness as the first thin film 11, and has a radius of curvature R1. Any thin film that does not touch the circle may be used. For example, the first thin film 11-6 may have a shape that covers the entire surface of the obstacle 702 in contact with the first thin film 11-6. In this case, since it is not necessary to process the first thin film 11-6 into a shape tangent to the circle having a radius of curvature R1, the effect of facilitating the production of the transparent member 1 is obtained. Further, when the user attaches the transmission member 1 provided with the first thin film 11-6 to the obstacle 702, the transmission member 1 includes the first thin film 11-6, so that the user covers the obstacle 702. The transparent member 1 may be attached to the. Therefore, the transparent member 1 configured in this way has an effect of facilitating the user to attach the transparent member 1 to the obstacle 702. The area of the first thin film 11 is the area of the surface of the first thin film 11 parallel to the YZ plane.

(Second embodiment)
FIG. 8 is a diagram showing a specific cross-sectional view of the transmission member 2 of the second embodiment. The transmission member 2 is in contact with a surface parallel to the YZ plane of the obstacle 702 in the wireless communication system 7 of FIG. The transmitting member 2 suppresses the reflection of the incident electromagnetic wave on the incident surface, and collects the incident electromagnetic wave on the receiving antenna 703. The XYZ coordinates in FIG. 8 are the same as the XYZ coordinates in FIG. Hereinafter, the same components as those in FIGS. 2 to 5 are designated by the same reference numerals and the description thereof will be omitted.
Further, regarding the two reflected waves L1 and L2 described in FIG. 6, in FIG. 8, the reflected wave on the surface of the third thin film 13 (the former L1 was the first thin film 11-1). (Different from the point), it becomes a reflected wave (corresponding to the previous L2) on the surface of the second thin film 12-5.

The transmission member 2 includes a lens-shaped member 21 and a third thin film 13. The lenticular member 21 and the third thin film 13 have a refractive index n ₂ . The lens-shaped member 21 has a convex lens-like shape and is in contact with the surface of the obstacle 702 on the transmitting antenna 701 side. On the other hand, the third thin film 13 is in contact with the other surface of the obstacle 702 (that is, the surface on the receiving antenna 703 side). The thickness _{d L2} of the lens-shaped member 21 of the transmission member 2 and the thickness _{d s3} of the third thin film 13, the thickness of the obstacle 702 as _{d b, d L2 + d b} + d s3 = m × λ / ( It is a thickness that satisfies the relationship of 4 × n _2). The lens-shaped member 21 includes a second thin film 12-1 to 5. The second thin film 12-1～5 Although each have the same thickness _{d s2} and refractive index _{n 2,} the shape or size is different. The second thin films 12-1 to 5 are circular in the YZ plane, and the second thin film 12-1, the second thin film 12-2, the second thin film 12-3, the second thin film 12-4, The radius is shorter in the order of the second thin film 12-5. Like the first thin film 11, the second thin film 12 is laminated so as to form a shape substantially the same as the convex lens shape. Therefore, the shape of the lens-shaped member 21 is substantially the same as that of the convex lens. Further, the second thin films 12-1 to 5 are laminated so as to be in contact with a circle having a radius of curvature R2, similarly to the first thin films 11-1 to 11. The radius of curvature R2 is calculated by the same method as the radius of curvature R1.

Hereinafter, a refractive index of n _2, the thin film thickness of d _s2 of the second thin film 12.
The transmissive member 2 does not necessarily have to include five second thin films 12, and the total thickness of the third thin film 13 and the obstacle 702, where m is an odd number, is a substance. Any number of second thin films 12 may be provided as long as the internal wavelength is m / 4 times.
Further, the lens-shaped member 21 of the embodiment does not necessarily have to be composed of the second thin film 12 having the same thickness. The lens-shaped member 21 may be configured in any way as long as it is configured to satisfy the following three conditions. The first condition, the total thickness of the refractive index of itself as n _2, and its thickness, the thickness of the obstacle 702 having a refractive index n _2, the thickness of the third thin film 13 having a refractive index n ₂ Is a thickness that satisfies the relationship of an odd multiple of 1/4 of the wavelength in the substance. The second condition is that the convex lens has substantially the same shape. The third condition is that it is composed of a plurality of thin films having a refractive index of n _2.
Further, the transmission member 2 may be formed by laminating the second thin films 12 like a seal, or may be formed by laminating the second thin films 12 with each other with an adhesive.

The third thin film 13 suppresses the generation of reflected waves generated when an electromagnetic wave propagating through the obstacle 702 is incident on the outside air from the obstacle 702.
The third thin film 13 is a thin film having a refractive index of n ₂ , and is in contact with the surface of the obstacle 702 opposite to the surface with which the second thin film 12 is in contact. The surface of the third thin film 13 in contact with the obstacle 702 is a surface perpendicular to the thickness direction. The thickness _{d s3} of the third thin film _is a thickness that _{d L2 +} d b + d _s3 is an odd multiple of _{λ / (4 × n 2)} .
That is, the thickness d _s3 of the third thin film is
_{d L2 + d b + d s3} = λ / (4 × n 2) × m (m: an odd number) (5)
Satisfy the relationship. Note that d _L2 is the thickness of the second thin films 12-1 to 5 stacked and satisfies the relationship of _{d L2} = d _{s2 × 5.
Since the thickness d s3} of the third thin film is an odd multiple of λ / (4 × n ₂ ), the generation of reflected waves of electromagnetic waves incident on the outside air from the obstacle 702 is suppressed by the same physical phenomenon as in FIG. Will be done.
The third thin film 13 may cover the entire surface of the obstacle 702 in contact with the third thin film 13, or may cover a part of the surface.

Next, the relationship between the radius of curvature R2 of the transmission member 2 of the second embodiment and the horizontal arrangement of the transmitting antenna 701, the obstacle 702, and the receiving antenna 703 will be described with reference to FIGS. 9 to 11.

FIG. 9 is a diagram showing an example of using the transmission member 2 of the second embodiment in the wireless communication system 7 of FIG. 9, the distance between the transmitting member 2 and the transmitting antenna 701 as _{d in, d in} satisfy the relation of ^{_{(d in ≧ 2D 2 / λ}} . Therefore, an electromagnetic wave transmitting antenna 701 is radiated, the transmitting member 2 On the incident surface, it is approximately a plane wave. The transmitting member 2 collects the incident electromagnetic wave on the receiving antenna 703.

Therefore, the transmission member 2 in FIG. 9 has a radius of curvature R2, as in the description of FIG. 4 of the first embodiment.
R2 = (n _c -1) d _f ... (6)
Satisfy the relationship. D _f As described above, the horizontal distance between the transmitting antenna 701 side of the surface of the receiving antenna 703 and the obstacle 702. Therefore, in FIG. 9, d _f = d _all − (d _in + d _L2 ), and the equation (6) for obtaining the radius of curvature is R2 = (n _c -1) {d _all − (d _in + d _L2 ). }. Here, d _all is the horizontal distance between the transmitting antenna 701 and the receiving antenna 703.

10, in FIG. 9 is a simulation result graph illustrating a relationship between the distance _{d all} of the curvature radius R2 of the transmitting member 2 and the transmitting antenna 701 and receiving antenna 703. In the simulation of FIG. 10, d _all in FIG. 9 satisfies the relationship of 10 ≦ d _{all / H1. Further, in FIG. 9, the angle θ a} formed by the straight line connecting the center of the transmitting antenna 701 and the center of the receiving antenna 703 and the surface of the obstacle 702 satisfies the relationship of θ _{a <5.71 deg.}
In FIG. 9, in FIG. 9, n ₁ = 1.00, n ₂ = 1.50, n _c = 1.22, _{di in} = 5 cm, d _L1 = 15λ / (4 × n _c ) = 15 × 0. If it is 4 / (4 × 1.22) ≒ 1.23cm, frequency representing the relationship between the radius of curvature R2 and _{d all} of the transmitting member 2 to be focused on the receive antenna 703 electromagnetic waves of 75 GHz. Here, the _{radius of curvature R2 is obtained and shown when d in} + d _L2 ≈6.7 cm is a fixed value and d _all is a value within the range of 0 to 200 m. In addition, in FIG. 10, the total thickness d _{L2 of} the transmission member 2 formed by laminating the second thin film 12 is 45λ / (4 × n _c ) = 45 × 0.4 / (4 × 1.22) ≈ This is the result of the simulation with 3.7 cm. The graph of FIG. 10 shows _{that the larger the d all} , the larger the radius of curvature R2.

_{FIG. 11 is a diagram showing the relationship between the horizontal distance d in} + d _L2 between the transmitting antenna 701 and the obstacle 702 and the radius of curvature R2 of the transmitting member 2. In the simulation of FIG. 11, d _all in FIG. 9 satisfies the relationship of 10 ≦ d _{all / H1.}
The graph of FIG. 11 shows that when n ₁ = 1.00, n ₂ = 1.50, n _c = 1.22, and d _all = 200 m in FIG. 9, an electromagnetic wave having a frequency of 75 GHz is transmitted to the receiving antenna 703. representing the relationship between the radius of curvature R2 and _{d all} of the transmitting member 2 to be condensed. Here, _{a graph of the radius of curvature R2 is shown when d all} = 200 m is a fixed value and d _in + d _L2 is a value within the range of 0 to 40 cm. The radius of curvature R2 is a smaller value as _{d in} + d _{L2 is larger.}

Transmitting member 2 configured in this way, the refractive index is the same refractive index as the obstacle _702, the second thin film _{d L2 +} d b + d _s3 is satisfying an odd multiple of the λ / (4n ₂₎ 12- Since the thin films 13 1 to 5 and the third thin film 13 are provided, the intensity of the electromagnetic wave transmitted through the obstacle 702 and output to the outside air can be increased as compared with the case where the transmitting member 2 is not provided. Further, in the transmission member 2 configured in this way, a plurality of second thin films 12 are laminated in layers so as to form a convex lens-like shape, and m is an odd number and the total thickness is the wavelength in the substance. Since it is m / 4, electromagnetic waves can be focused on the receiving antenna 703. Further, since the transmission member 2 configured in this way has the same refractive index as the obstacle 702, it can be manufactured by the same material as the obstacle 702, and has an effect of facilitating the production of the transmission member.
(Modification example)

In the transmission member 2, not all the second thin films 12 need to be in contact with the circle having the radius of curvature R2. For example, the second thin film 12 in contact with the obstacle 702 covers the entire surface of one side of the obstacle 702. Therefore, it does not have to touch a circle having a radius of curvature R2.

FIG. 12 is a diagram showing a specific example in the case where the second thin film 12 in contact with the obstacle 702 does not contact the circle having the radius of curvature R2. The transmission member 2 of FIG. 12 includes a second thin film 12-6 in place of the second thin film 12-1 of the transmission member 2 of FIG. The refractive index and thickness of the second thin film 12-6 are the same as those of the second thin film 12. The second thin film 12-6 touches the obstacle 702 and does not touch the circle with radius of curvature R2. The second thin film 12-6 may have a shape that covers the entire surface of the obstacle 702 in contact with the transmission member 2. In this case, since it is not necessary to process the second thin film 12-6 into a shape tangent to the circle having a radius of curvature R2, the effect of facilitating the production of the transmission member 2 is obtained. Further, for the user, attaching the transmission member 2 provided with the second thin film 12-6 to the obstacle 702 is different from attaching the transmission member 2 provided with the second thin film 12-1 to the obstacle 702. The time and effort required to process the second thin film 12 into a shape tangent to a circle having a radius of curvature R2 before mounting is reduced. Therefore, the transparent member 1 configured in this way has an effect of facilitating the user to attach the transparent member 2.

The shape and area of the second thin film 12-6 has the same or larger area as that of the second thin film 12-4, and the shape and area covering a part or all of the surface of the obstacle 702. Any shape and area may be used as long as it is used.

Hereinafter, modifications common to the transmission member 1 of the first embodiment and the transmission member 2 of the second embodiment will be described with reference to FIGS. 13 to 15. However, for the sake of simplicity, the transmission member will be described as the transmission member 1. The numbers in parentheses in FIGS. 13 to 15 indicate that the members may be represented by the reference numerals. That is, for example, the reference numeral 1 (2) in FIG. 13 indicates that the transparent member 1 or 2 may be used.

FIG. 13 is a diagram showing a specific example of the configuration in which the transparent member 1 of the modified example is viewed from the front. In the first thin film 11 of the transmission member 1, not all the first thin films 11 are necessarily circular in the YZ plane, and as shown in this figure, the shape in the YZ plane is quadrangular, octagonal, or the like. It may be non-circular.
Further, as shown in FIG. 7, a part of the first thin film 11 of the transmission member 1 may be the first thin film 11 having an area covering the obstacle 702.

In the transmission member 1 of the modified example, only one transmission member 1 does not necessarily come into contact with the obstacle 702, and a plurality of transmission members 1 may come into contact with the obstacle 702.

FIG. 14 is a diagram showing a specific arrangement of the transparent members 1 when a plurality of transparent members 1 are in contact with the obstacle 702. Hereinafter, a member including a plurality of transparent members 1 of the embodiment is referred to as a first collective member 101. In the first assembly member 101, the transmission members 1 may be arranged so as to circumscribe each other. In this case, the in-plane density of the transparent member 1 in the first collective member 101 is increased. Therefore, the first collective member 101 has an effect of condensing electromagnetic waves more efficiently when the area of irradiation of the electromagnetic wave on the obstacle 702 is larger than the area of the transmitting member 1 as compared with the case where the transmitting member 1 is one. Play.

FIG. 15 is a diagram showing a specific arrangement of the transparent members 1 when a plurality of transparent members 1 of the modified example shown in FIG. 13 are arranged in the YZ plane. Hereinafter, a member including a plurality of transmission members 1 of a modified example will be referred to as a second collective member 102. In the second collective member 102, as shown in this figure, in the transmission member 1 of the modified example, thin films having a non-circular or circular shape in the YZ plane such as a quadrangle or an octagon are formed on the obstacle 702 with each other. A plurality of sheets may be arranged so as to be in contact with each other.

<When θ _a ≒ 0 cannot be regarded as>
_{Hereinafter, a} wireless communication system (hereinafter referred to as “non-approximate establishment system”) which is provided with the transmitting antenna 701, the obstacle 702, and the receiving antenna 703 in the same order as the wireless communication system 7 but cannot be regarded as θ a ≈ 0 will be described. .. In the non-approximation established system, each transmitting member 1 or 2 in the formula (3) to (6), replacing the _{d f} to _{d f / cos (θ a)} , a _{d b d b / cos (θ} a) The following equations (7) to (10) replaced with are satisfied.
R1 = (n _c -1) d _f / cos (θ _a ) ... (7)
R1 = (n _c -1) d _in / cos (θ _a ) ... (8)
_{(D L2 + d b + d} s3) / cos (θ a) = λ / (4 × n 2) × m ··· (9)
R2 = (n _c -1) d _f / cos (θ _a ) ... (10)

As an example of the usage scene of the non-approximate establishment system, for example, a transmitting antenna 701 is installed in a signboard on a building wall located 10 m from the ground, and the rooftop of a building facing the building across a 30 m wide road (ground). It is a wireless communication system in which the receiving antenna 703 is installed at 20 m). In this case, since the horizontal distance d _all between the two antennas is 30 m and the height difference H1 is 10 m, 10> d _all / H1 (= 3), and _{the relationship between 10 ≦ d all} / H1 and θ _a <5.71 deg. And are not satisfied. That is, θ _a ≈ 0 is not satisfied.

Hereinafter, the refraction of electromagnetic waves in the non-approximate establishment system will be described.

FIG. 16 is a diagram showing a path of an electromagnetic wave propagating through the obstacle 702. In FIG. 16, the obstacle 702 in FIG. 1 is enlarged and shown in order to make the path of the electromagnetic wave remarkable.
The electromagnetic wave radiated by the transmitting antenna 701 enters the obstacle 702. The electromagnetic wave incident on the obstacle 702 is refracted and propagates through the obstacle 702. At the boundary that propagates from the obstacle 702 to the outside air, it is incident on this boundary at an incident angle θ _b and propagates into the outside air in _{the direction of the exit angle θ a.}
Distance an electromagnetic wave passing through the obstacle 702 (hereinafter referred to as "propagation path length".) As a U, U _{is U = d b / cos (θ} b).

Considering Snell's law, n ₁ × sin (θ _b ) = n ₂ × sin (θ _a ).
θ _b = arcsin (n ₁ × sin (θ _a )) / n ₂ … (11)
Meet.
Therefore, propagation path length U is _{U = d b / cos {arcsin} (n 1 × sin (θ a)) / n 2} ... (12)
Is.

Equations (11) and (12) are used to specifically show the displacement of the location on the receiving antenna 703 on which the electromagnetic wave reaches due to the refraction of the electromagnetic wave by the obstacle 702, and the magnitude thereof. In Figure _{16, d all = 30m, H1} = 10m, consider the case of _{d b = 8mm, n 1 =} 1.00 and _n 2 = 1.50. First, since d _all = 30 m and H1 = 10 m, tan (θ _a ) = H1 / d _all = 10/30 ≈ 0.333. In this case, θ _a = 18.43 deg. Since sin (θ _a ) = 0.316, using equation (11),
θ _b = arcsin (n ₁ × sin (θ _a )) / n ₂
= Arcsin (1.00 x 0.316) /1.50
= 18.43 / 1.50
= 12.29deg
Is.
Therefore, tan (θ _b) = a _{0.218, d b {tan (θ} a) -tan (θ b)} is ≒ 8 × {0.333-0.218} = 0.92mm . Therefore, since H1 = 10 m, 0.92 mm / 10 m is a very small value of 0.0001 or less.
This indicates that even in a non-approximate system, there is an electromagnetic wave propagating in substantially the same path as the wireless communication system 7 depending on the conditions. Further, this indicates that the transmission member 1 or 2 satisfies the equations (3) to (10) depending on the conditions even in the non-approximate establishment system.

Propagation between the case where the refraction of the electromagnetic wave due to the obstacle 702 is not considered (that is, the case where the propagation path length is d ₂ / cos (θ _a )) and the case where the refraction is considered, although it cannot be regarded as θ _{a ≈ 0.} The difference in path length is as follows. Propagation path length that does not consider _{refraction, d b / cos (θ a} ) a = 8 / 0.989 = 8.09mm. On the other hand, the propagation path length when considering refractive _{is d b / cos (θ b)} = 8 / 0.949 = 8.19mm. These differences (hereinafter referred to as “formula-dependent path length differences”) are 0.24 mm. The formula-dependent path length difference is about 3% of the propagation path length when refraction is taken into consideration, and is a small value as compared with the propagation path length when refraction is taken into consideration. Further, the formula depends path length difference is a small value as compared to the thickness d _b of the obstacle. This means that the transmission member 1 or 2 satisfies a part or all of the equations (3) to (10) with good accuracy even in the non-approximate establishment system depending on the conditions. Good accuracy means that the transmission member 1 or 2 satisfying a part or all of the formulas (3) to (10) is the position where the transmission member 1 or 2 satisfying the formulas (11) and (12) collects light. It means that the light is focused on the same position and range as the range.

FIG. 17 is a diagram showing a specific example when the transmission member 1 or 2 is used in a non-approximate establishment system. The same reference numerals are given to those having the same functions as those in FIG. 1, and the description thereof will be omitted.
In FIG. 17, the X-axis of the XYZ coordinate system, which is a Cartesian coordinate system, is an axis parallel to the horizontal direction, and the Y-axis is an axis parallel to the vertical direction.

The transmitting antenna 701a is, for example, a small cell base station installed on an indoor ceiling, an IoT device, a wireless LAN access point, or the like. The transmitting antenna 701a has an aperture diameter of D. The transmitting antenna 701a exists at a _{height h 3} (that is, the Y coordinate is h _3). Being present at a height h ₃ means that the Y coordinate of its own center point is h _3. The transmitting antenna 701 is in the negative direction of the Y-axis and emits electromagnetic waves in the direction of _{an angle θ a with respect to the vertical direction.} The angle θ _a is an angle formed by a straight line connecting the centers of the transmitting antenna 701a and the receiving antenna 703a in the vertical direction.

The obstacle 702a is a member that transmits an incident electromagnetic wave with a predetermined transmittance, and is, for example, a ceiling, a signboard surface, or a glove of a lighting device. Obstacles 702a has a thickness (i.e., the width of the Y-axis direction) is _{d b.} The refractive index of the obstacle 702a with respect to an electromagnetic wave having a wavelength λ is n ₂ .

The receiving antenna 703a is, for example, an entrance base station or a network connection point installed on an indoor wall. Receive antenna 703a, to the transmitting antenna 701a, present at a distance _{d all} away in the X-axis direction. The receiving antenna 703a _{exists at a height h 5} which is _{separated from h 3} by H 2 in the negative direction of the Y axis. It should be noted that H2 does not satisfy the relationship of _{H2 << dall.} H2 is an example 5 _{m, d all} is, for example, 30 m. The height of the ceiling indoors in FIG. 17 is h4, and an obstacle 702a also exists at this height h4.
The transmitting antenna 701a, the obstacle 702a, and the receiving antenna 703a are arranged in the negative direction of the Y axis in the order of the transmitting antenna 701a, the obstacle 702a, and the receiving antenna 703a.

_{An electromagnetic wave radiated in a} direction of an angle θ a with respect to the vertical direction when the transmitting antenna 701 is in the negative direction of the Y axis passes through the obstacle 702 a. Electromagnetic waves passing through the obstacle 702a is the outside air in the refractive index n ₁ propagates in the direction of the angle theta _a to the vertical, and reaches the receiving antenna 703a. Angle theta _a, for example, H2 is a 5 _m, if _{d all} is 30m is 58.99Deg. Further, in this case, 1 / cos (θ _a ) is substantially the same as 1.941.

FIG. 18 is a diagram showing a path of an electromagnetic wave propagating through the obstacle 702a. In FIG. 18, the obstacle 702a in FIG. 17 is enlarged and shown in order to make the path of the electromagnetic wave remarkable.

The electromagnetic wave radiated by the transmitting antenna 701a is incident on the obstacle 702a. The electromagnetic wave incident on the obstacle 702a is refracted and propagates through the obstacle 702a. At the boundary where the obstacle 702a propagates to the outside air, the boundary is incident at an _{incident angle θ b} and propagates into the _{outside air in the direction of the exit angle θ a.} The emitted electromagnetic wave is incident on the receiving antenna 703a.

Similar to FIG. 16, the angle θ _b is
θ _b = arcsin (n ₁ × sin (θ _a )) / n ₂ ... (13)
Meet. Further, in the same manner as in FIG. 16, _{d b} is
d _b / cos θ _b = d _b / cos {arcsin (n ₁ × sin θ _a ) / n ₂ } ・ ・ ・ (14)
Meet.
Therefore, in FIGS. 17 and 18, transparent member 1 or 2 is substituted in equation (3), respectively to (6), the _{d f d f / cos {arcsin} (n 1 × sinθ a) / n 2}, the _{d b d b / cos {arcsin} (n 1 × sinθ a) / n 2} substituted expressions (7) satisfies to (10).

Equations (13) and (14) are used to specifically show the displacement of the location on the receiving antenna 703a to which the electromagnetic wave reaches due to the refraction of the electromagnetic wave by the obstacle 702a, and the magnitude thereof. In Figure _{18, d all = 30m, H2} = 5m, consider the case of _{d b = 8mm, n 1 =} 1.00 and _n 2 = 1.50. First, since d _all = 30 m and H2 = 5 m, tan (θ _a ) = H2 / d _all = 5/30 ≈0.166. In this case, θ _a = 9.46 deg. Since sin (θ _a ) = 0.164, using equation (13),
θ _b = arcsin (n ₁ × sin (θ _a )) / n ₂
= Arcsin (1.00 x 0.164) /1.50
= 9.46 / 1.50
= 6.31deg
Is.
Therefore, tan (θ _b) = a _{0.111, d b {tan (θ} a) -tan (θ b)} is ≒ 8 × {0.166-0.111} = 0.44mm . Therefore, this means that since H2 = 5 m, the deviation of the position where the electromagnetic wave is collected is very small compared to the height difference between the antennas.
This indicates that, as in FIG. 16, even in the non-approximate establishment system, there is an electromagnetic wave propagating in substantially the same route as the wireless communication system 7 depending on the conditions.

The transmissive member is an example of a lens. The outside air is an example of a medium. The third thin film 13 is an example of a thin film member. The first collecting member 101 and the second collecting member 102 are examples of compound eye lenses. The first thin film 11-1 in FIG. 2, the first thin film 11-6 in FIG. 7, and the second thin film 12-1 in FIG. 8 have the largest area among the plurality of thin films. This is an example of a thin film having. The transmitting antenna 701 is an example of the first antenna. The receiving antenna 703 is an example of the second antenna.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes designs and the like within a range that does not deviate from the gist of the present invention.

1 ... Transmission member of the first embodiment, 2 ... Transmission member of the second embodiment, 11 ... First thin film, 12 ... Second thin film, 13 ... Third thin film, 21 ... Lens-like member, 701 ... transmitting antenna, 702 ... obstacle, 703 ... receiving antenna, 101 ... first collective member, 102 ... second collective member

Claims (5)

_{A plurality of thin films having a refractive index of n c} for an electromagnetic wave having a wavelength λ propagating in a medium having a refractive index of n ₁ are arranged in layers, and a part or all of the plurality of thin films form substantially the same shape as a convex lens. and, most thin film having a large area, the refractive index with respect to the electromagnetic wave is a n _2, one of the surfaces of obstacles that transmits the electromagnetic wave at a predetermined transmittance with out prior Symbol plurality of thin film In contact with
n _c = (n ₁ × n ₂ ) ^1/2 , and the thickness of the plurality of thin films in the direction perpendicular to one surface is an odd multiple of λ / (4 × n _c).
lens. _{A plurality of thin films having a refractive index of n 2 with} respect to an electromagnetic wave having a wavelength λ propagating in a medium having a refractive index of n ₁ are arranged in layers, and a part or all of the plurality of thin films form substantially the same shape as a convex lens. and a thin film having the largest area among the plurality of the thin film, the refractive index with respect to the electromagnetic wave is a n _2, on one of the surfaces of obstacles that transmits the electromagnetic wave at a predetermined transmittance with With the lenticular member in contact,
A thin film having a refractive index of n ₂ with respect to the electromagnetic wave, parallel to the surface of the obstacle that is in contact with the lens-shaped member , and in contact with the surface that exists on the opposite side of the surface that the lens-shaped member is in contact with. Shape member and
With
The thickness of the lenticular member in the direction perpendicular to the one surface, the thickness of the obstacle in the direction perpendicular to the one surface, and the thickness of the thin film member in the direction perpendicular to the one surface. The total thickness is
It is an odd multiple of λ / (4 × n _2),
lens. Before SL and a plurality of thin films, the distance d _in the first antenna is arranged on the side of the one surface of the obstacle to emit the electromagnetic waves, the length of the opening of the first antenna and D When d _in ≧ 2D ² / λ, the shape substantially the same as the shape of the convex lens is arranged on the opposite side of the first antenna and the one surface of the obstacle to receive the electromagnetic wave. the distance between the second antenna and _{d all,} the sum of the previous SL thickness of the plurality of thin film when the d _{l which, R = (n c -1)} d f, d f = d all - (d It is a shape in contact with a spherical surface having a radius of curvature R that satisfies _in + d _l).
The lens according to claim 1. Before SL and a plurality of thin films, the distance d _in the first antenna is arranged on the side of the one surface of the obstacle to emit the electromagnetic waves, the length of the opening of the first antenna and D When d _in <2D ² / λ, the shape substantially the same as the shape of the convex lens is a shape in contact with a spherical surface having a radius of curvature R satisfying _{R = (n c} -1) d _in.
The lens according to claim 1. A plurality of lenses according to any one of claims 1 to 4 are provided.
Compound eye lens.

Images