Radio antennas, wireless communication systems

Abstract

To provide a wireless antenna that can most strongly radiate electromagnetic waves in a direction closer to the normal direction of a dielectric waveguide.SOLUTION: A wireless antenna 100 capable of transmitting and receiving signals in the millimeter wave or quasi-millimeter wave bands includes a cable-like waveguide 110 formed of a dielectric material and a lump body 120 formed of a dielectric material. The dielectric constant of the waveguide 110 is greater than the dielectric constant of the surroundings of the waveguide 110 excluding the lump body 120. The lump body 120 is located on or near the waveguide 110. The lump body 120 has a periodic structure in which the dielectric constant varies periodically in the longitudinal direction of the waveguide 110.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a radio antenna including a dielectric waveguide and a radio communication system using this radio antenna, and more particularly to an antenna technology that can radiate electromagnetic waves most strongly in a direction closest to the normal direction of the dielectric waveguide. [Background technology]

[0002] Fifth-generation mobile communication systems (so-called 5G) and sixth-generation mobile communication systems (so-called 6G) ​​require high data rates of 10 Gb / s or more. As one method for achieving such high-speed wireless communication, the application of millimeter wave bands (frequency bands of 30 GHz to 300 GHz) or sub-terahertz bands (frequency bands of 100 GHz or more) to wireless communication is being considered.

[0003] Electromagnetic waves with such high frequencies are characterized by significant attenuation as they propagate through space. It is known that the loss of TEM mode electromagnetic waves propagating through free space (known as free space propagation loss) is proportional to the square of the frequency. Furthermore, electromagnetic waves with such high frequencies are characterized by large diffraction losses due to obstructions (in other words, the electromagnetic waves tend to propagate in a straight line). For this reason, there is a demand for technology to reduce blind zones (i.e., areas where electromagnetic waves cannot reach).

[0004] Patent Document 1 discloses a wireless antenna that includes a dielectric waveguide, which is a wired transmission medium, and a dielectric attachment (referred to as a "mass" in Patent Document 1) that can be installed anywhere on the dielectric waveguide, as a technology for reducing blind zones. According to the wireless antenna of Patent Document 1, a dielectric waveguide is installed from a wireless base station. By installing a dielectric attachment at a portion of the dielectric waveguide located near an area that would be a blind zone if the wireless antenna were not used, the dielectric attachment radiates electromagnetic waves, thereby reducing blind zones. The wireless antenna of Patent Document 1 does not require active components such as repeaters, and the dielectric attachment (i.e., the electromagnetic wave radiation source) can be formed anywhere on the dielectric waveguide, thereby achieving coverage tailored to the situation with low power consumption. For example, in high-frequency communications, efficient coverage can be achieved in factories or rooms where people or equipment are present as shields. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2021-114766 Summary of the Invention [Problem to be solved by the invention]

[0006] Fig. 1 of Patent Document 1 shows that electromagnetic waves are radiated from the dielectric attachment in the normal direction of the dielectric waveguide. However, in reality, this is not the case. This will be explained.

[0007] 1 and 2 are diagrams for explaining, using ray approximation, the behavior of electromagnetic waves propagating through a dielectric waveguide 110 equipped with a prior art dielectric attachment 920. The angle between the radiation direction of the electromagnetic wave radiated from the dielectric attachment 920 and the normal direction of the dielectric waveguide 110 (hereinafter referred to as the radiation angle) is θ radThe electromagnetic wave propagates through the dielectric waveguide 110 while repeatedly undergoing total reflection near the boundary between the dielectric waveguide 110 and air. Typically, the relative permittivity of the dielectric material used in the dielectric waveguide 110 is 4 or less, so the angle (i.e., critical angle) formed between the electromagnetic wave approximated by a ray and the longitudinal direction of the dielectric waveguide 110 during total reflection is approximately 40° or less. Therefore, whether the permittivity of the dielectric attachment 920 is higher (see FIG. 1) or lower (see FIG. 2) than that of the dielectric waveguide 110, the radiation angle θ of the electromagnetic wave radiated from the dielectric attachment 920 is rad becomes a fairly large value (see the trajectory of the electromagnetic wave approximated by a ray in Figures 1 and 2). For simplicity, the cross-sectional shape of the dielectric attachment 920 is rectangular in Figures 1 and 2, but the same argument applies even if the cross-sectional shape of the dielectric attachment 920 is, for example, triangular or semicircular.

[0008] Typically, the radiation angle θ rad is more preferable as it is closer to 0°, and less practical as it is closer to 90°. This is because the dielectric waveguide 110 propagates electromagnetic waves in its longitudinal direction. In other words, there is little point in radiating electromagnetic waves in a direction close to the propagation direction of the dielectric waveguide 110.

[0009] An object of the present invention is to provide a radio antenna that can radiate electromagnetic waves most strongly in a direction closest to the normal direction of a dielectric waveguide, and a radio communication system using this radio antenna. [Means for solving the problem]

[0010] The technical matters described herein are not intended to explicitly or implicitly limit the invention described in the claims, nor to express the possibility of accepting such limitations by anyone other than those who benefit from the present invention (e.g., the applicant and the right holder), but are described simply to facilitate understanding of the gist of the present invention. The outline of the present invention from other perspectives can be understood, for example, from the claims at the time of filing of this patent application. The radio antenna of the present invention has a dielectric waveguide and a mass. The dielectric waveguide has a dielectric constant greater than the dielectric constant of the surrounding area excluding the mass. The mass is located on or near the dielectric waveguide. The mass is a portion that radiates and absorbs electromagnetic waves. Electromagnetic waves are transmitted and received between the mass and a communication terminal. The dielectric waveguide may have a branched structure. The dielectric waveguide may be connected to a medium capable of propagating electromagnetic waves. The mass has a diffraction grating structure. [Effects of the Invention]

[0011] According to the present invention, since the mass having the diffraction grating structure is located on or near the dielectric waveguide, the electromagnetic wave can be radiated most strongly in a direction closest to the normal direction of the dielectric waveguide. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram for explaining the behavior of electromagnetic waves propagating in a dielectric waveguide having a dielectric attachment according to the prior art, using a ray approximation. [Figure 2] 1 is a diagram for explaining the behavior of electromagnetic waves propagating in a dielectric waveguide having a dielectric attachment according to the prior art, using a ray approximation. [Figure 3] 1 shows an example of the configuration of a wireless communication system according to an embodiment. [Figure 4] Cross-sectional view of a dielectric waveguide. [Figure 5] 1A and 1B are diagrams for explaining a mass, (a) a cross-sectional view of the mass, (b) a perspective view of the mass, and (c) a cross-sectional view of another example of the mass. [Figure 6] FIG. 2 is a cross-sectional view of the wireless antenna according to the first embodiment. [Figure 7] FIG. 1 is a diagram for explaining radiation of electromagnetic waves. [Figure 8] 1 is a diagram for explaining differences in wave numbers in electromagnetic wave interference. [Figure 9] 1A, 1B, and 1C show examples of a wireless antenna in which a mass is located near a waveguide. (a) First Example, (b) Second Example, and (c) Third Example. [Figure 10] An example of a radio antenna with a branched configuration. [Figure 11] Structures in which a waveguide is connected to a medium. (a) Example 1. (b) Example 2. (c) Example 3. [Figure 12] Configuration of the wireless antenna used in the electromagnetic field simulation. (a) Cross-sectional view. (b) Plan view. [Figure 13] The relationship between radiation angle and period. [Figure 14] Electromagnetic field simulation results. (a) Radiation angle is 7 degrees. (b) Radiation angle is 45 degrees. [Figure 15] 10A and 10B are a side view and a plan view, respectively, of a wireless antenna according to a first example of the second embodiment. [Figure 16] 10A and 10B are a side view and a plan view, respectively, of a wireless antenna according to a second example of the second embodiment. [Figure 17] 10A and 10B are a side view and a plan view, respectively, of a wireless antenna according to a third embodiment. [Figure 18] 10A is a bottom view of a rail portion of a radio antenna according to a fourth embodiment of the present invention; FIG. 10B is a side view of the radio antenna; and FIG. [Figure 19] 10A and 10B are a side view and a plan view, respectively, of an example of an installation example of a rail portion in a wireless antenna according to a fourth embodiment. [Figure 20] 10A and 10B are a side view and a plan view, respectively, of an example of an installation example of a rail portion in a wireless antenna according to a fourth embodiment. [Figure 21] 10A is a side view of another example of the configuration of the wireless antenna according to the fourth embodiment, FIG. 10B is a plan view of the first periodic structure, and FIG. 10C is a plan view of the second periodic structure. [Figure 22] Other embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0013] An embodiment of the present invention will be described with reference to the drawings.

[0014] First Embodiment The wireless communication system 1 of the embodiment shown in FIG. 3 includes the wireless antenna 100 of the embodiment, the communication terminal 200, and the signal generation device 800. As shown in FIG. 3, the wireless antenna 100 has a configuration including a waveguide 110 and one or more lumps 120. The waveguide 110 is a physical object formed of a dielectric, and as shown in FIG. 3, has an external shape in which the length is significantly larger than the width (or the square root of the cross-sectional area), such as a cable for example. The waveguide 110 may have a linear shape, or may have a shape that meanders slightly as shown in FIG. 3, in other words, a shape having a bend that does not adversely affect the low-loss propagation of the waveguide 110 described later, or may have a branching structure. The branching structure of the waveguide 110 will be described later. In the local region of the waveguide 110 where the lump 120 is located, the waveguide 110 preferably has a linear shape. Each lump 120 may be formed of the same dielectric as the waveguide 110 or may be formed of a dielectric different from the waveguide 110. Each lump 120 is located on the waveguide 110. In this case, the lump 120 protrudes like a protrusion from the waveguide 110. Alternatively, each lump 120 is located in the vicinity of the waveguide 110 away from the waveguide 110. Alternatively, among the T (where T is a predetermined integer of 2 or more) lumps 120, t (where t is a predetermined integer satisfying 1≦t<T) lumps 120 are located on the waveguide 110, and the remaining T−t lumps 120 are located in the vicinity of the waveguide 110 away from the waveguide 110. In this embodiment, one end of the waveguide 110 is connected to a signal generation device 800 that generates a signal having a frequency of millimeter wave (30 GHz to 300 GHz) or quasi-millimeter wave (although there is no clear definition, approximately 20 GHz to 30 GHz). There is no limitation to the type of this signal, and it may be an analog signal, a digital signal, a discrete-time signal, or a continuous-time signal. In the example shown in FIG. 3, the other end of the waveguide 110 is not connected to anything and is open, but may be short-circuited, may be connected to an antenna (for example, a linear antenna, an aperture antenna, etc.), or may be terminated.

[0015] As shown in FIG. 4, which is a cross-sectional view perpendicular to the longitudinal direction of the waveguide 110 at an arbitrary position in the longitudinal direction, the waveguide 110 has a cross-section with both a constant shape and a constant size. In this example, the cross-sectional shape of the waveguide 110 is rectangular. Therefore, the waveguide 110 has two long side surfaces 111 that face each other in a first direction orthogonal to the longitudinal direction of the waveguide 110, and two short side surfaces 113 that face each other in a second direction orthogonal to both the longitudinal direction and the first direction of the waveguide 110. The long side surfaces 111 are side surfaces whose width (i.e., the length in the direction orthogonal to the longitudinal direction of the waveguide 110) is equal to the length of the long side of the rectangular cross-section, and the short side surfaces 113 are side surfaces whose width is equal to the length of the short side of the rectangular cross-section. In this way, the waveguide 110 has a uniform structure, i.e., the cross-sectional shape and size at an arbitrary position are both constant, and the material is constant at an arbitrary position. In FIG. 4, the cross-sectional shape of the waveguide 110 is rectangular, but is not limited to this structure and may be, for example, square or circular.

[0016] The dielectric constant of the waveguide 110 is greater than the dielectric constant of the surroundings of the waveguide 110 excluding the mass 120. In the example shown in Figures 3 and 4, the surroundings of the waveguide 110 are air, and the dielectric constant of air is approximately 1, so the dielectric constant of the waveguide 110 is greater than 1. For this reason, in the absence of the mass 120, the electromagnetic field of the signal from the signal generating device 800 input to the one end of the waveguide 110 is concentrated in the waveguide 110, which has a large dielectric constant, and is transmitted with low loss towards the other end of the waveguide 110, reaching the other end of the waveguide 110.

[0017] Each mass 120 located on or near the waveguide 110 can function as a radiator that radiates electromagnetic waves (radio waves in terms of frequency band). The power lost in each mass 120 due to the radiation of electromagnetic waves depends primarily on the shape (described below), size, and dielectric constant of the mass 120. From the perspective of radiating electromagnetic waves with higher power, for example, the dielectric constant of the mass 120 is preferably the same as or greater than the dielectric constant of the waveguide 110. The dielectric constant of the mass 120 is uniform, i.e., the dielectric constants at any two different points on the mass 120 are equal to each other. More preferably, from the perspective of loss, materials with small dielectric loss tangents in the frequency band of the electromagnetic waves used are selected as the dielectrics of the waveguide 110 and the mass 120. Generally, the higher the dielectric constant, the larger the dielectric loss tangent. Therefore, the dielectric constants of the dielectrics of the waveguide 110 and the mass 120 are determined taking into account the amount of radiation and loss. Thus, when mass 120 is present, the signal from signal generating device 800 is radiated into space as electromagnetic waves from mass 120. Note that "radiation" means that the power of the signal that reaches mass 120 that is lost due to electromagnetic wave radiation exceeds the transmission loss that would actually occur if mass 120 were not present. The power lost due to electromagnetic wave radiation at mass 120 is usually a portion of the power of the signal that reaches mass 120, and the signal with the remaining power passes through the portion of waveguide 110 where mass 120 is located. The signal that passes through mass 120 propagates with low loss through waveguide 110 toward the adjacent mass 120, or toward the other end of waveguide 110 if there is no adjacent mass 120. The electromagnetic waves radiated from mass 120 are received by a wireless antenna (not shown) of communication terminal 200, such as a mobile phone.

[0018] As shown in FIG. 5( a), at least one mass 120 included in the wireless antenna 100 includes a base 120v and a periodic structure 120p standing on the base 120v. The base 120v and the periodic structure 120p may be integrally formed or may be separate tangible objects. In the former case, the mass 120 having the periodic structure 120p is fabricated, for example, by cutting a dielectric or by injection molding a molten dielectric. In the latter case, multiple dielectrics constituting the periodic structure 120p are attached to the base 120v by mechanical construction (see the fourth embodiment) or by using an adhesive or pressure-sensitive adhesive. The dielectric constant of the adhesive or pressure-sensitive adhesive is preferably approximately the same as that of the base 120v. The periodic structure 120p is a so-called diffraction grating structure, and the dielectric constant of the periodic structure 120p varies periodically in the longitudinal direction of the waveguide 110.

[0019] From another perspective, referring to Figure 5(b), in a three-dimensional Cartesian coordinate system, when the two-dimensional extent of base 120v is represented by x-coordinates and y-coordinates and the height of periodic structure 120p at position (x, y) is represented by z-coordinates, the height z of periodic structure 120p is expressed as z = f(x, y) using function f (more precisely, function f corresponding to a closed region on the xy plane). In other words, the occupied interval of the periodic structure 120p in the z-axis direction at position (x, y) is (0, f(x, y)]. However, the function f is a bounded function and a periodic function, and satisfies f(x, y0) = f(x + A, y0) when the variable y is fixed to any value y0 included in the closed region, and satisfies f(x0, y) = C(x0, y) when the variable x is fixed to any value x0 included in the closed region. A is the period, and C(x0, y) is a constant corresponding to the value x0 (i.e., a constant function related to y). The closed region is preferably rectangular. The maximum value of the function f is set to H, and the minimum value of the function f is set to 0. Examples of the function f are not particularly limited, but include a function representing a sine wave, a function representing a rectangular wave (the example shown in Figure 5), a function representing a trapezoidal wave, a function representing a triangular wave, a function representing a sawtooth wave, and a function representing a stepped sawtooth wave.

[0020] The maximum value of the variable x included in the above closed region is x maxis set as the minimum value of the variable x included in the above closed region, and x min is set as, (x max - x min ) / A is 2 or more, preferably 3 or more. When the variable y is fixed to an arbitrary value y0 included in the above closed region, in the closed interval [x min , x max , the interval p H of the variable x that satisfies f(x, y0) = H (however, theoretically includes a degenerate interval consisting of a single point, but in reality is a proper and bounded interval) and the interval of the variable x that satisfies f(x, y0) < H (however, theoretically includes a degenerate interval consisting of a single point, but in reality is a proper interval) appear periodically and alternately. p H / A is set to an appropriate value for the periodic structure 120p to function as a diffraction grating according to the frequency of the electromagnetic wave propagating in the waveguide 110, the interference of the electromagnetic wave in a desired direction described later, etc., but usually is 0.8 or less.

[0021] When the block 120 is located on or near the waveguide 110, the bottom surface of the base 120v (the bottom surface is the surface without the periodic structure 120p in the z - axis direction) contacts the waveguide 110, or faces the waveguide 110 without the periodic structure 120p being located between the base 120v and the waveguide 110. In the local region where the block 120 is located on or near the waveguide 110, the x - axis direction is parallel to the longitudinal direction of the waveguide 110. Hereinafter, the y - axis direction is referred to as "the width direction of the waveguide 110", and the z - axis direction is referred to as "the normal direction of the waveguide 110". According to such a periodic structure 120p, in the longitudinal direction of the waveguide 110, two values with different dielectric constants (that is, the dielectric constant of the dielectric and the dielectric constant of air) appear periodically and alternately.

[0022] As shown in FIG. 5(c), a periodic structure 120p in which a portion corresponding to air (however, a portion not exceeding the height H) in the periodic structure 120p shown in FIG. 5(a) is replaced with a dielectric 120s other than air is also allowed. According to the above example, the height z e of the dielectric 120s at the position (x, y) is ze =Hf(x,y), and the occupied area of ​​the dielectric 120s in the z-axis direction at the position (x,y) is (f(x,y),H). The dielectric constant of the dielectric 120s is different from the dielectric constant of the mass 120.

[0023] The width of the periodic structure 120p (i.e., the length of the periodic structure 120p in the width direction of the waveguide 110) may be the same as the width of the waveguide 110 (i.e., the length of the waveguide 110 in the width direction of the waveguide 110), may be greater than the width of the waveguide 110, or may be smaller than the width of the waveguide 110. By making the width of the periodic structure 120p greater than the width of the waveguide 110, the electromagnetic wave radiated from the periodic structure 120p can be made closer to a plane wave. By making the width of the periodic structure 120p smaller than the width of the waveguide 110, the electromagnetic wave radiated from the periodic structure 120p can be made closer to a spherical wave. In the case of a spherical wave, the antenna gain when the mass 120 is considered as an antenna is reduced, and the isotropy of the radiated electromagnetic wave can be made higher compared to a plane wave. In other words, a wider coverage can be achieved.

[0024] 6 is a cross-sectional view of a wireless antenna 100 including a mass 120 having a periodic structure 120p when the periodic function is a function representing a square wave, and the mass 120 and the waveguide 110, taken along the longitudinal direction of the waveguide 110. In the example shown in FIG. 6, from a first perspective, the periodic structure 120p is a line-and-space structure in which a plurality of linearly extending grooves 120a are arranged at equal intervals and parallel to one another. From a second perspective, the periodic structure 120p is a line-and-space structure in which a plurality of linearly extending relatively high portions 120b and a plurality of linearly extending relatively low portions 120c are arranged alternately at equal intervals and parallel to one another. From a third perspective, the periodic structure 120p is a line-and-space structure in which a plurality of linearly extending rail portions 120d stand at equal intervals and parallel to one another on a base portion 120v. The extension direction of each groove 120a, each portion 120b, 120c, or each rail portion 120d is perpendicular to the longitudinal direction of the waveguide 110. The depth of the grooves 120a or the height of the rail portions 120d are equal to each other. In the example shown in Figures 5 and 6, the shape of the base 120v is a rectangular flat plate.

[0025] Electromagnetic waves are difficult to radiate from the grooves 120a because they cancel each other out and are attenuated in each groove 120a of the periodic structure 120p, but they are radiated well from the portions between the grooves 120a (i.e., the relatively high portions 120b). By appropriately setting the period A of the periodic structure 120p (i.e., the sum of the length of one line and the length of one space in the longitudinal direction of the waveguide 110), it is possible to cause the electromagnetic waves to interfere with each other in a specific direction. Therefore, it is possible to radiate the electromagnetic waves most strongly in that specific direction (including the normal direction of the waveguide 110). The principle behind this is explained below.

[0026] 7 shows a schematic diagram of the wavefront of an electromagnetic wave radiated from a mass 120 having a periodic structure 120p, as understood from the Huygens-Fresnel principle, and the radiation direction in which the electromagnetic wave is most strongly radiated from the mass 120. The angle θ formed between the radiation direction in which the electromagnetic wave propagating through the waveguide 110 is most strongly radiated from the mass 120 and the normal direction of the waveguide 110 at the position of the mass 120 is referred to as the radiation angle θ hereinafter. In order for electromagnetic waves radiated from adjacent track portions 120d to constructively interfere with each other at the radiation angle θ, the difference between the wave number per period A of the electromagnetic wave propagating through the dielectric and the wave number per length in the radiation direction corresponding to the period A of the electromagnetic wave propagating through free space (i.e., A sin θ) must be an integer. 8, in order for the electromagnetic waves radiated from the adjacent rail portions 120d to reinforce each other at the radiation angle θ, the formula (1) must be satisfied. g is the wavelength of the electromagnetic wave of the propagation mode propagating through the boundary region between the waveguide 110 and the mass 120, and N eq is the equivalent refractive index, and λ0 is the wavelength of the electromagnetic wave in free space. From the definition of the equivalent refractive index, equation (2) holds.

number

[0027] When m=1, equation (3) holds. This represents the condition in which electromagnetic waves constructively interact in the direction farthest from the waveguide 110, that is, in the direction closest to the normal direction of the waveguide 110. N eq takes a value ranging from 1, which is the refractive index of air, to approximately 2, which is the refractive index of the waveguide 110 or the mass 120. sinθ takes a value of 1 or less. By appropriately selecting the period A, it is possible to obtain θ that satisfies equation (3). Therefore, it is possible to radiate the electromagnetic wave most strongly in a direction closest to the normal direction of the waveguide 110. This will be explained later as an example of the first embodiment.

number

[0028] When the total number T of the blocks 120 is 2 or more, the shape commonly held by a part of the T blocks 120 (i.e., p blocks, where p satisfies 1 ≦ p < T) may be the same as or different from the shape commonly held by another part of the T blocks 120 (i.e., q blocks, where q satisfies 1 ≦ q < T - p) or all of them (i.e., q blocks, where q satisfies q = T - p). Alternatively, when T ≧ 2, any two different blocks 120 among the T blocks 120 may have different shapes. For example, when T = 2, one block 120 may have the above-described periodic structure 120p, while the other block 120 may not have the above-described periodic structure 120p.

[0029] Furthermore, when the total number T of the blocks 120 is 2 or more, the size commonly held by a part of the T blocks 120 (i.e., p blocks, where p satisfies 1 ≦ p < T) may be the same as or different from the size commonly held by another part of the T blocks 120 (i.e., q blocks, where q satisfies 1 ≦ q < T - p) or all of them (i.e., q blocks, where q satisfies q = T - p). Alternatively, when T ≧ 2, any two different blocks 120 among the T blocks 120 may have different sizes. For example, when T = 2, one block 120 may have the periodic structure 120p with period A, while the other block 120 may have the periodic structure 120p with period B (where A ≠ B).

[0030] The positions of the masses 120 on the waveguide 110 in the longitudinal direction are preferably positions excluding both ends of the waveguide 110, and more preferably positions where mismatching is unlikely to occur and propagation mode conversion is unlikely to occur. When the total number T of masses 120 is 2 or more, the distances measured from one end of the waveguide 110 along the longitudinal direction of any two different masses 120 among the T masses 120 may be different from each other. Alternatively, for example, the distances measured from one end of the waveguide 110 along the longitudinal direction of two or more different masses 120 may be equal to each other. In the latter case, these two or more masses 120 are located at different positions on the circumference of the waveguide 110. Furthermore, in this latter case, taking into consideration the propagation mode of the electromagnetic wave propagating through the waveguide 110, the two masses 120 are preferably located at positions 180 degrees apart from each other on the circumference of the waveguide 110.

[0031] In examples where masses 120 are located on waveguide 110, each mass 120 may be formed integrally with waveguide 110 or may be formed separately from waveguide 110. In the latter case, each mass 120 is attached to waveguide 110, but may or may not be removable thereafter. Even if each mass 120 is removable from waveguide 110, it is desirable that each mass 120 not move on waveguide 110 once attached. Each mass 120 remains in intimate contact with waveguide 110. For this reason, when attaching the mass 120 to the waveguide 110, the base 120v of the mass 120 has a contact surface with a surface shape that is the same as the local surface shape of the portion of the waveguide 110 to which the mass 120 is attached; for example, if the waveguide 110 is an elongated rectangular parallelepiped, the contact surface of the mass 120 is composed of at least one flat surface, and if the waveguide 110 is an elongated cylinder, the contact surface of the mass 120 is a part of the cylindrical surface. When an adhesive or pressure-sensitive adhesive is used to attach the mass 120 to the waveguide 110, it is desirable that the dielectric constant of the adhesive or pressure-sensitive adhesive be approximately the same as the dielectric constant of the waveguide 110 or the dielectric constant of the mass 120.

[0032] In an example where the mass 120 is located near the waveguide 110 and away from the waveguide 110, the upper limit of the distance between the mass 120 and the waveguide 110 is determined by the dielectric constant of the mass 120, the dielectric constant of the waveguide 110, the dielectric constant of the medium between the mass 120 and the waveguide 110 (examples of the medium include air or foamed plastic), the strength of the signal propagating through the waveguide 110, the cross-sectional shape of the waveguide 110, and the cross-sectional size of the waveguide 110. Note that the "distance between the mass 120 and the waveguide 110" here refers to the shortest distance between any point on the mass 120 and any point on the waveguide 110. If the distance between the mass 120 and the waveguide 110 is equal to or less than the upper limit, the mass 120 functions as a radiating portion or a receiving portion, as described above. In other words, the "proximity of the waveguide" where the mass is located is the range in which the mass 120 can function as a radiator or a receiver.

[0033] The positional relationship between the mass 120 and the waveguide 110 may be permanent or temporary. In the case of a permanent relationship, for example, as shown in FIG. 9( a), the mass 120 is fixed to a mounting part 310 that is fixed to the waveguide 110. The material of the mounting part 310 may be a dielectric or a metal. However, it is desirable to avoid the presence of an electrical conductor between the mass 120 and the waveguide 110 (for example, if the mounting part 310 is made of a metal, a part or all of the mounting part 310). The mounting part 310 serves as a holder that holds the mass 120 and as a spacer that maintains a constant distance between the mass 120 and the waveguide 110.

[0034] In the case of a temporary relationship, for example, as shown in FIG. 9( b), the mass 120 is fixed to a cylindrical slider 320, and the slider 320 is attached to the waveguide 110. The slider 320 can move along the waveguide 110. The material of the slider 320 may be a dielectric or a metal. However, even in this example, it is desirable to avoid the presence of an electrical conductor between the mass 120 and the waveguide 110 (for example, if the material of the slider 320 is metal, it may be a part or the whole of the slider 320). The slider 320 serves as a holder that holds the mass 120 and as a spacer that keeps the distance between the mass 120 and the waveguide 110 constant.

[0035] Another example of a temporary relationship is when the mass 120 is attached to a movable object (e.g., footwear, an anklet, or a transport robot) and the waveguide 110 is entirely or partially embedded in a structure such as a floor or a passageway. FIG. 9( c) shows an example in which the movable object is a transport robot 330. In this case, when the movable object moving on the structure approaches the waveguide 110—that is, when the mass 120 attached to the movable object enters a range where its distance from the waveguide 110 is equal to or less than the upper limit—the mass 120 functions as a radiator or receiver. If the movable object has a receiver or transmitter (the movable object may have electronic components such as an amplifier, as necessary), communication is realized between the signal generator 800 (which may be a receiver or a transmitter / receiver, as will be described later) and the receiver or transmitter of the movable object. In the example where the mass 120 is attached to a movable object, electromagnetic radiation occurs only when the movable object approaches the waveguide 110, thereby improving the efficiency of energy utilization.

[0036] A cover (not shown) made of a dielectric material may be disposed around the waveguide 110 having one or more lumps 120. The cover is in close contact with the waveguide 110 and the lumps 120 on the waveguide 110. This example is not limiting, and the cover may cover the waveguide 110 excluding the lumps 120, or excluding the lumps 120 and the portion of the waveguide 110 where the lumps 120 are located. The dielectric constants of the waveguide 110 and the lumps 120 are greater than the dielectric constant of the cover. Therefore, in the absence of the lumps 120, the electromagnetic field of the signal from the signal generating device 800 input to the one end of the waveguide 110 is concentrated in the waveguide 110, which has a large dielectric constant, and then propagates with low loss toward the other end of the waveguide 110, reaching the other end of the waveguide 110.

[0037] The waveguide 110 may have a configuration as a single product, or may have a configuration in which, for example, multiple waveguides (hereinafter referred to as sub-waveguides) having the same structure are connected in a row. In the latter case, the sub-waveguides can be connected to each other by fusion splicing or by using a connector, as in the case of optical fibers. Alternatively, the sub-waveguides may be connected to each other by welding or melting. The dielectric constant of one of two adjacent sub-waveguides connected to each other may be different from the dielectric constant of the other sub-waveguide.

[0038] The waveguide 110 may have a branching structure. There are no limitations on the branching shape or the number of branches. FIG. 10 shows an example of a T-shaped waveguide 110 with two branches. The waveguide 110 with a branching structure may have a configuration as a single product, or may have a configuration in which, for example, multiple sub-waveguides with the same structure are connected. In the latter case, a connection using, for example, a branching waveguide 350 can be used to connect the sub-waveguides.

[0039] In the above-described embodiment, one end of the waveguide 110 is physically connected to the signal generating device 800, but this configuration is not limiting. For example, as shown in FIG. 11 , one end of the waveguide 110 may be connected to a portion of a medium capable of propagating electromagnetic waves, and the other portion of the medium may be connected to the signal generating device 800. Examples of the medium include a line made of a material different from that of the waveguide 110 (e.g., a coaxial line or a waveguide having a dielectric constant different from that of the waveguide 110), air, or optical fiber. As can be understood from the case where the medium is air, the term "connection" does not necessarily mean only a physical connection, but also a physical aspect in which electromagnetic waves can propagate. When the medium is a line 110a, the line 110a and the waveguide 110 are connected to each other using, for example, a connector 360, as shown in FIG. 11(a). 11(b), for example, an antenna device 370a attached to the signal generating device 800 and an antenna device 370b attached to one end of the waveguide 110 realize propagation of electromagnetic waves between the signal generating device 800 and the waveguide 110. The antenna device 370b attached to one end of the waveguide 110 may include, for example, a repeater that amplifies the captured electromagnetic waves. However, if the antenna device 370a attached to the signal generating device 800 and one end of the waveguide 110 are well aligned, the one end of the waveguide 110 may directly receive a signal from the signal generating device 800.

[0040] When the medium is an optical fiber 112, for example, as shown in FIG. 11(c), one end of the waveguide 110 is connected to a first opto-electrical converter 380a, the first opto-electrical converter 380a is connected to one end of the optical fiber 112, and the other end of the optical fiber 112 is connected to a second opto-electrical converter 380b included in the signal generating device 800. The second opto-electrical converter 380b is, for example, a laser diode, and converts the electrical signal generated by the signal generating device 800 into an optical signal. The optical signal propagates through the optical fiber 112. The first opto-electrical converter 380a is, for example, a photodiode, and converts the optical signal from the optical fiber 112 into an electrical signal. Therefore, propagation of an electromagnetic wave (in this example, light) is realized between the signal generating device 800 and the waveguide 110.

[0041] For example, if a long waveguide 110 is used from the signal generating device 800 to the location where the mass 120 is to be installed, in a situation where the location where the mass 120 is to be installed is limited to a location far away from the signal generating device 800, the transmission loss of the waveguide 110 cannot be ignored. Since the transmission loss of the optical fiber 112 is usually smaller than the transmission loss of the waveguide 110, the configuration shown in Fig. 11(c) is useful for long-distance, low-loss transmission of signals.

[0042] The waveguide 110 typically has characteristics equivalent to a wide-band filter and can transmit a wideband signal. Therefore, as shown in FIG. 3, if the signal input from the signal generating device 800 to the waveguide 110 is a multiband signal having Q bands (where Q is a predetermined integer satisfying Q≧2), each of the masses 120 will emit Q electromagnetic waves in the corresponding bands. Furthermore, the optical fiber 112 is typically capable of transmitting wideband signals. Therefore, according to the configuration shown in FIG. 11(c), the multiband signal generated by the signal generating device 800 propagates through the optical fiber 112 as an optical signal by photoelectric conversion, then propagates through the waveguide 110 again as an electrical signal by photoelectric conversion, and is emitted from each of the masses 120 as Q electromagnetic waves in the corresponding bands.

[0043] In the case of multi-band signals, the propagation characteristics of the electromagnetic waves radiated into space from the mass 120 differ for each band, and therefore the optimal position of the mass 120 for radiation differs for each band. For example, high-frequency electromagnetic waves are more affected by electromagnetic wave obstructions. Therefore, if high-frequency electromagnetic waves are radiated from the same position as the optimal position for radiating low-frequency electromagnetic waves, the presence of electromagnetic obstructions will increase the number of blind spots. However, by using the wireless antenna 100 and locating the mass 120 at a position on the waveguide 110 that avoids electromagnetic obstructions (i.e., the optimal position for radiating high-frequency electromagnetic waves), separate from the mass 120 located at the optimal position for radiating low-frequency electromagnetic waves, and preferably by further locating the mass 120 with an appropriate shape (e.g., the periodic structure 120p described above) or by arranging multiple masses 120 in an appropriate direction, the radiation direction of the high-frequency electromagnetic waves can be optimized, thereby reducing the number of blind spots caused by electromagnetic obstructions.

[0044] When the waveguide 110 has two or more masses 120, the total number T of masses 120 is determined according to the desired power loss due to electromagnetic wave radiation. The power of the signal from the signal generating device 800 input to the one end of the waveguide 110 needs to be the total power obtained by adding the sum of the power lost due to electromagnetic wave radiation between each mass 120 and the other end of the waveguide 110 to the transmission loss that actually occurs in the portion of the waveguide 110 that functions as a waveguide.

[0045] Alternatively, when the power of the signal input from the signal generating device 800 to the one end of the waveguide 110 (hereinafter referred to as input power) is predetermined, the power obtained by subtracting the transmission loss actually occurring in the portion of the waveguide 110 that functions as a waveguide from the input power is distributed to the power lost by radiation of electromagnetic waves between each mass 120 and the other end of the waveguide 110, and the degree of radiation in each mass 120 is determined according to the distributed power. For example, equal radiation loss may be desired in each mass 120. In this case, assuming that there are T masses 120 and the masses 120 closest to the signal generating device 800 are called the first, second, ..., tth, ..., Tth mass 120, the degree of radiation of the tth mass 120 may be adjusted so that the proportion of power represented by 1 / (T-t+1) of the power of the signal reaching the location where the tth mass 120 (t∈{1, ..., T}) is located is lost by radiation. In this case, in the Tth mass 120, almost all of the power of the signal that reaches it is lost through radiation, so there is almost no radiation of electromagnetic waves at the other end of the waveguide 110. For example, when T=5, the first, second, third, and fourth masses 120 radiate -7 dB (one-fifth), -6 dB (one-fourth), -4.8 dB (one-third), and -3 dB (one-half) of the signal that reaches them, respectively, and the fifth mass 120 radiates as much of the power of the signal that reaches it as electromagnetic waves as possible.

[0046] In the above example, the ratio of the power of the signal reaching the t-th mass 120 to the radiation loss increases as t increases, so the shape and size of the mass 120 are selected so that the radiation power at the t-th mass 120 increases as t increases.

[0047] In the wireless antenna 100, unless the close contact state of the t-th (t∈S, S is a predetermined subset of the set {1, ..., T} excluding the empty set) mass 120 is maintained permanently, the close contact state of the t-th mass 120 that causes a portion of the waveguide 110 to function as an electromagnetic wave radiation portion can be released at any time. In other words, the close contact state of the t-th mass 120 continues to be maintained while a portion of the waveguide 110 needs to function as an electromagnetic wave radiation portion. However, when this need is no longer present, the close contact state of the t-th mass 120 at the portion that functions as a radiation portion is released. The portion whose close contact state is released loses its function as an electromagnetic wave radiation portion and functions as a waveguide. Therefore, the position of the electromagnetic wave radiation portion, i.e., the position where the mass 120 is attached to the waveguide 110, can be easily changed depending on changes in the service area.

[0048] The above-described wireless antenna 100 can be used not only as a transmitting antenna but also as a receiving antenna. In this case, for example, a receiving device is connected to the one end of the waveguide 110 instead of the signal generating device 800. For example, electromagnetic waves emitted from a mobile phone are absorbed in the receiving section (i.e., the mass 120) and transmitted to the receiving device by the waveguide 110. The 3 dB loss occurs when the electromagnetic waves absorbed in the receiving section are distributed toward the one end and the other end of the waveguide 110. A transmitting / receiving device having both transmitting and receiving functions may be connected to the one end of the waveguide 110 instead of the signal generating device 800. In addition, (1) a configuration can be adopted in which a receiving device is connected to the other end of the waveguide 110, to which the signal generating device 800 is connected, (2) a configuration can be adopted in which a transmitting / receiving device is connected to the other end of the waveguide 110, (3) a configuration can be adopted in which a receiving device is connected to each of the one end and the other end of the wireless antenna 100, or (4) a configuration can be adopted in which a transmitting / receiving device is connected to each of the one end and the other end of the wireless antenna 100. In particular, with the configurations (2), (3), and (4), a combining device (not shown) combines electromagnetic waves received by the receiving functions of devices connected to both ends of the waveguide 110, thereby eliminating the 3 dB loss described above.

[0049] <Example of the first embodiment> A wireless antenna 100 in the 28 GHz band, which is an example of the first embodiment, will be described together with the results of electromagnetic field analysis. 28 GHz is a frequency used to realize wireless communication of about 10 Gbps in fifth-generation mobile communication systems.

[0050] FIG. 12 shows a wireless antenna 100 according to an embodiment. The wireless antenna 100 shown in FIG. 12 has two masses 120. The waveguide 110 has the shape of an elongated rectangular parallelepiped. The size and shape of the periodic structure 120p of one mass 120 are the same as the size and shape of the periodic structure 120p of the other mass 120. One mass 120 is fixed to one long side surface 111, and the other mass 120 is fixed to the other long side surface 111. The distance from one end of the waveguide 110 to one mass 120 is the same as the distance from one end of the waveguide 110 to the other mass 120. The dimensions of the waveguide 110 and the masses 120 are as shown in FIG. 12. In the electromagnetic field analysis, for simplicity, the relative dielectric constants of the waveguide 110 and the mass 120 are set to the same value (specifically, 2.1), the total number of rail portions 120d is set to 5, and the duty ratio of the line and space is set to 0.5. In the electromagnetic field analysis, the period A of the periodic structure 120p is a design parameter.

[0051] The width of the periodic structure 120p (20 mm) is larger than the width of the waveguide 110 (7 mm) to make the electromagnetic waves emitted from the periodic structure 120p as close to a plane wave as possible. Because the periodic structure 120p acts as a macroscopic scatterer for the electromagnetic waves propagating through the waveguide 110, the smaller the size of the periodic structure 120p, the closer the electromagnetic waves emitted from the scatterer become to spherical waves emitted from a single point. In the case of spherical waves, the amount of electromagnetic waves (referred to here as unwanted radiation waves for convenience) radiated in a direction perpendicular to the plane of the paper in FIG. 12 (i.e., a direction perpendicular to the longitudinal direction and normal direction of the waveguide 110) increases. This effect is particularly pronounced when the size of the scatterer is smaller than the wavelength. Because the influence of unwanted radiation waves is not taken into account in the derivation of Equation (1), a large amount of unwanted radiation waves results in a large error in the radiation direction from Equation (3). To minimize this error, it is desirable to make the width of the periodic structure 120p as wide as possible. In the example that was the subject of the electromagnetic field analysis, the width of the periodic structure 120p was set to a value (20 mm) that was approximately twice the wavelength of the electromagnetic wave.

[0052] Under the above conditions, the effective refractive index N of the mode propagating through the waveguide 110 is eq is calculated as 1.365 by electromagnetic field analysis. eq Substituting these values, the relationship between the radiation angle θ and the period A is as shown in FIG. 13. From FIG. 13, the period A required to obtain a desired radiation angle θ can be derived. For example, if it is desired to radiate electromagnetic waves in the direction of θ = 0° (i.e., the normal direction of the waveguide 110), the period A is 8 mm. FIG. 14(a) shows the results of electromagnetic field analysis of the propagation of electromagnetic waves when the period A is 8 mm. The radiation angle θ is 7°, which is close to the target value of 0°. Furthermore, when the period A is 16 mm, the radiation angle θ is 45° as shown in FIG. 14(b), which matches the radiation angle θ calculated from FIG. 13. The difference between the radiation angle θ calculated from FIG. 13 and the radiation angle θ obtained by electromagnetic field analysis is due to the fact that the width of the periodic structure 120p, which should ideally extend infinitely in the direction perpendicular to the longitudinal direction and normal direction of the waveguide 110, is actually finite (20 mm).

[0053] The results of the electromagnetic field analysis show that the first embodiment can radiate electromagnetic waves most strongly in a direction closest to the normal direction of the waveguide 110. It also shows that the radiation angle θ can be changed by changing the period A of the periodic structure 120p. Changing the parameters of the waveguide 110 and the periodic structure 120p (including the number of grooves 120a) does not change the radiation principle, and therefore similar results are obtained for the radiation angle θ. These parameters primarily affect the emissivity (the ratio of the power of the electromagnetic waves propagating through the waveguide 110 before being radiated from the mass 120 to the power of the electromagnetic waves radiated from the mass 120). Therefore, the parameters can be determined taking this into consideration as a design requirement. In this example, the masses 120 are arranged above and below the waveguide 110, so that electromagnetic waves are radiated in both the vertical and horizontal directions of the waveguide 110. To radiate electromagnetic waves in one direction, simply attach the mass 120 to one side of the waveguide 110.

[0054] Second Embodiment According to the structure described in the first embodiment, the equivalent refractive index and characteristic impedance of the mode of the electromagnetic wave propagating through the waveguide 110 change at the boundary between the mass 120 and the waveguide 110, resulting in the generation of reflected and radiated waves. In particular, because the phase of the radiated wave differs from the phase of the electromagnetic wave intentionally emitted by the periodic structure 120p, the radiated wave may interfere with the desired electromagnetic wave generated by constructive interference in the radiation direction obtained by Equation (3), potentially resulting in unintended disturbances in the radiation angle of the electromagnetic wave. Therefore, it is necessary to minimize the changes in the equivalent refractive index and characteristic impedance at the boundary between the mass 120 and the waveguide 110. As a second embodiment, a structure for minimizing the changes in the equivalent refractive index and characteristic impedance will be described. Only the differences between the first and second embodiments will be described. For other technical details, please refer to the description of the first embodiment.

[0055] In the second embodiment, both ends of the mass 120 in the longitudinal direction of the waveguide 110 each have a tapered structure that tapers in the longitudinal direction of the waveguide 110. For example, as shown in FIG. 15 , both ends of the waveguide 110 in the longitudinal direction of the base 120v extend in the longitudinal direction of the waveguide 110 while decreasing the length in the y-axis direction (i.e., width) without changing the length in the z-axis direction (i.e., height). Alternatively, as shown in FIG. 16 , both ends of the waveguide 110 in the longitudinal direction of the base 120v extend in the longitudinal direction of the waveguide 110 while decreasing the length in the z-axis direction (i.e., height) without changing the length in the y-axis direction (i.e., width). Although not shown, both ends of the waveguide 110 in the longitudinal direction of the base 120v may extend in the longitudinal direction of the waveguide 110 while decreasing the length in the y-axis direction (i.e., width) and while decreasing the length in the z-axis direction (i.e., height). The length L of the tapered structure is appropriately set by electromagnetic field analysis as a value that can sufficiently reduce reflection and unwanted radiation. Although a linear taper is illustrated in Figures 15 and 16, a taper with any curve, such as a parabolic or exponential curve, may also be used. The tapered structure gradually changes the equivalent refractive index and characteristic impedance of the mode of the electromagnetic wave propagating through the waveguide 110, thereby reducing the aforementioned reflection and unwanted radiation.

[0056] Third Embodiment As the third embodiment, a mechanism that can dynamically change the radiation direction will be described. Only the differences between the first embodiment and the third embodiment will be described. For other technical matters, please refer to the description of the first embodiment.

[0057] In the third embodiment, the wireless antenna 100 includes a temperature control device 400 that can change the temperature of the mass 120. A plate 150 (e.g., a metal plate) with low thermal resistance is attached to the side of the mass 120 (in this example, the side of the base 120v). One end of the plate 150 is connected to one end of the conductive path 160, and the other end of the conductive path 160 is connected to the temperature control device 400. The temperature control device 400 can adjust the temperature applied to the plate 150, thereby changing the temperature of the mass 120. In general, the dielectric constant (or refractive index) of a dielectric material is temperature-dependent. Changing the temperature of the mass 120 changes the equivalent refractive index of the mode of the electromagnetic wave propagating through the waveguide 110 and the mass 120. According to equation (3), a change in the equivalent refractive index changes the radiation angle. The radiation angle can be dynamically changed according to this relationship.

[0058] When the temperature control device 400 is, for example, a power supply, the conductive path 160 is a conductive wire, and the plate 150 generates heat according to the principle of resistance heating. The temperature of the plate 150 can be changed by changing the value of the current. When the temperature control device 400 is, for example, a heat exchanger or a chiller, the conductive path 160 is a flow path through which a medium heated or cooled by heat exchange flows, and the plate 150 is heated or cooled by heat transfer between the medium and the plate 150. The temperature of the plate 150 can be changed by controlling the temperature of the heat exchanger or chiller.

[0059] <Modification 1 of the Third Embodiment> Generally, as the dielectric constant increases, the dielectric loss tangent increases. Therefore, if electromagnetic waves are radiated from the mass 120 over a long period of time, thermal energy is generated in the mass 120 due to dielectric loss. This thermal energy increases the temperature of the mass 120, which may cause the radiation direction to deviate from the intended direction. Changes in the ambient temperature or direct sunlight may also change the temperature of the mass 120, causing the radiation direction to deviate from the intended direction. Therefore, the temperature control device 400 may be used to control the temperature of the mass 120 to be kept constant.

[0060] <Modification 2 of the Third Embodiment> The temperature control device 400 and the conductive path 160 described in the third embodiment are not required. In this second modification, although not shown, a metal heat sink with low thermal resistance is attached to the mass 120 (in this example, to the side of the base 120v). The heat sink is useful for suppressing the temperature rise of the mass 120. The periodic structure 120p shown in FIG. 5(a) itself has a heat radiation function, but attaching a metal heat sink with low thermal resistance to the mass 120 enables more efficient heat radiation. Furthermore, since the periodic structure 120p shown in FIG. 5(c) does not provide sufficient heat radiation, attaching a metal heat sink with low thermal resistance to the mass 120 enables efficient heat radiation. Furthermore, since the metal heat sink also functions as an electromagnetic shield, the radiation of electromagnetic waves in undesired radiation directions can be suppressed by optimizing the shape of the heat sink and the attachment position of the heat sink to the mass 120.

[0061] <Fourth embodiment> As the fourth embodiment, a mechanism that can dynamically change the radiation direction will be described. Only the differences between the first embodiment and the fourth embodiment will be described. For other technical matters, please refer to the description of the first embodiment.

[0062] As shown in Figures 18, 19, and 20, the mass 120 includes a base 120v and multiple rail sections 120d, each of which is a tangible object independent of the base 120v. The multiple rail sections 120d have the same size and shape. Each rail section 120d is attached to the base 120v by a mechanical structure. The base 120v has multiple fasteners on its upper surface. In this example, each fastener is a pair of cylindrical protrusions 120k fixed to the upper surface of the base 120v. The pair of cylindrical protrusions 120k is located at both ends in the width direction of the base 120v, and the multiple fasteners are aligned in a row at equal intervals along the longitudinal direction of the waveguide 110. Each rail section 120d has a hole 120h at each end of its lower surface, into which the cylindrical protrusion 120k can be inserted. The rail portion 120d can be attached to any fixture by inserting the cylindrical protrusion 120k into the hole 120h. In this example, the distance between adjacent rail portions 120d in the longitudinal direction of the waveguide 110 is approximately zero. The multiple rail portions 120d are attached to the base portion 120v at equal intervals, thereby forming a periodic structure 120p. The configuration of the fourth embodiment can realize various periodic structures 120p. For example, as shown in FIG. 19, one rail portion 120d can be attached to every other base portion 120v, or as shown in FIG. 20, two rail portions 120d can be attached to every third base portion 120v. Since each rail portion 120d can be removed from the base portion 120v, the periodic structure 120p can be easily reconfigured according to the desired radiation direction. The rail portion 120d is not limited to a rectangular parallelepiped, and may be, for example, a columnar body having a triangular or trapezoidal cross section as long as its cross-sectional shape satisfies the function described in the first embodiment. Furthermore, according to the configuration of the fourth embodiment, the distance between adjacent rail portions 120d in the longitudinal direction of the waveguide 110 is approximately zero, so that by attaching all of the rail portions 120d to the base portion 120v, it is also possible to realize a mass 120 that does not have a periodic structure 120p.

[0063] In the examples shown in Figures 18, 19, and 20, all of the track sections 120d are tangible objects independent of the base section 120v, but this is not limited to such an example. Some of the multiple track sections 120d may be fixed to the base section 120v, and the remaining track sections 120d may be tangible objects independent of the base section 120v. In the example shown in Figure 21, multiple first track sections 120d1 are fixed to the base section 120v at equal intervals, and multiple second track sections 120d2 are tangible objects independent of the base section 120v. The multiple second track sections 120d2 are held at equal intervals by a holder 170. The multiple first track sections 120d1 constitute a first periodic structure 120p1. The second rail portions 120d2 are inserted into the first periodic structure 120p1 by a sliding mechanism (not shown), and as a result, the first rail portions 120d1 and the second rail portions 120d2 are alternately arranged in a row at equal intervals to form the second periodic structure 120p2. In this way, by inserting or removing the second rail portions 120d2, it is possible to switch from the first periodic structure 120p1 to the second periodic structure 120p2, or from the second periodic structure 120p2 to the first periodic structure 120p1.

[0064] <Other embodiments> Another embodiment related to the present invention will be described with reference to FIG. 22. As shown in FIG. 22, a plurality of lumps 120 having the same size and shape may be arranged in the waveguide 110 at a period A that satisfies formula (1). Here, A = B + C holds, where B is the distance between adjacent lumps 120 and C is the length of each lumps 120 in the longitudinal direction of the waveguide 110. The width of each lumps 120 may be the same as the width of the waveguide 110, or may be greater than or smaller than the width of the waveguide 110. Each lumps 120 is not limited to a rectangular parallelepiped, and as long as its cross-sectional shape satisfies the function described in the first embodiment, each lumps 120 may be a columnar shape, for example, with a triangular or trapezoidal cross section.

[0065] <Addendum 1> The technical features disclosed in the various embodiments and their modifications described above are not necessarily mutually exclusive, and technical features of one embodiment or its modifications may be applied to technical features of another embodiment or its modifications, provided that there is no contradiction from a technical viewpoint.

[0066] The claims as of the filing of this application do not necessarily exhaustively claim all inventions disclosed in this specification. In this regard, this should not be understood or construed as meaning that the applicant has pre-filing waived any right to a patent for any invention not claimed at the time of filing this application. To the extent permitted by the laws, regulations, or treaties of any country or region where this application is filed, the applicant reserves the right to a patent for any invention not claimed in this application, the right to file a divisional application for such invention, the right to claim such invention by amendment, and any other rights, unless the applicant expressly and conclusively expresses a contrary intention.

[0067] An example of a summary of the present invention based on another aspect is as follows.

[0068] The first invention is a wireless antenna capable of transmitting and receiving millimeter wave or quasi-millimeter wave band signals, and includes a cable-shaped waveguide formed of a dielectric material and a mass formed of a dielectric material. The dielectric constant of the waveguide is greater than the dielectric constant of the surrounding area of ​​the waveguide excluding the mass. The mass is located on or near the waveguide. The mass has a periodic structure in which the dielectric constant changes periodically in the longitudinal direction of the waveguide.

[0069] The second invention is a method of the first invention, in which the period of the periodic structure is A, the angle between the radiation direction in which the electromagnetic wave propagating through the waveguide is most strongly radiated from the mass and the normal direction of the waveguide at the position of the mass is θ, and the wavelength of the electromagnetic wave propagating through the waveguide is λ. g The wavelength in free space of the electromagnetic wave radiated from the mass is λ0, and the following equation is established:

number

[0070] The third invention is characterized in that, in the first or second invention, the length of the mass in the width direction, which is perpendicular to the longitudinal direction of the waveguide and perpendicular to the normal direction of the waveguide, does not match the width of the waveguide.

[0071] The fourth invention is characterized in that, in any of the first to third inventions, each of the ends of the mass in the longitudinal direction of the waveguide has a tapered structure that tapers in the longitudinal direction of the waveguide.

[0072] A fifth invention is characterized in that, in any one of the first to fourth inventions, the optical fiber further includes a periodic structure changing device that can mechanically change the period of the periodic structure.

[0073] A sixth invention is characterized in that, in any one of the first to fifth inventions, it further includes a temperature control device that can change the temperature of the mass.

[0074] The seventh invention is a wireless antenna capable of transmitting and receiving signals in the millimeter wave band or quasi-millimeter wave band, comprising a cable-shaped waveguide formed of a dielectric and an antenna function section. The antenna function section comprises a plurality of masses each formed of a dielectric. The dielectric constant of the waveguide is greater than the dielectric constant of the surroundings of the waveguide excluding the antenna function section. The antenna function section is located on the waveguide or in the vicinity of the waveguide. The plurality of masses are arranged at equal intervals in the longitudinal direction of the waveguide. Let B be the interval between adjacent masses among the plurality of masses, and C be the length of each of the plurality of masses in the longitudinal direction of the waveguide, and let A=B+C be the angle θ between the radiation direction in which the electromagnetic waves propagating through the waveguide are most strongly radiated from the antenna function section and the normal direction of the waveguide at the position of the antenna function section, and let λ be the wavelength of the electromagnetic waves propagating through the waveguide. g and the wavelength in free space of the electromagnetic wave radiated from the antenna function section is λ0, the following equation holds:

number

[0075] An eighth invention is a wireless communication system including a wireless antenna and a communication terminal, wherein the wireless antenna includes a cable-shaped waveguide formed of a dielectric and a mass formed of a dielectric. The dielectric constant of the waveguide is higher than the dielectric constant of the surroundings of the waveguide excluding the mass. The mass is located on or near the waveguide. The mass has a periodic structure in which the dielectric constant changes periodically in the longitudinal direction of the waveguide. The communication terminal receives electromagnetic waves radiated from the mass with its antenna, and the mass receives electromagnetic waves from the communication terminal antenna. In the eighth invention, the wireless antenna may be any of the first to seventh inventions.

[0076] <Addendum 2> While the present invention has been described with reference to exemplary embodiments, those skilled in the art will recognize that various changes can be made and equivalents can be substituted for elements thereof without departing from the scope of the invention. Furthermore, many modifications can be made to adapt a particular system, device, or component thereof to the teachings of the present invention without departing from the essential scope of the invention. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed for carrying out this invention, but rather that the invention will include all embodiments falling within the scope of the appended claims.

[0077] Furthermore, the use of terms such as "first" and "second," if any, does not denote any order or importance, and terms such as "first" and "second" are used to distinguish between elements. The terms used herein are for the purpose of describing embodiments and are not intended to limit the present invention in any way. The term "comprises" and its conjugations, when used in this specification and / or the appended claims, reveal the presence of the stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof. The term "and / or" includes any and all combinations of one or more of the associated listed elements, if any. In the claims and the specification, unless otherwise specified, the use of words such as "connected," "coupled," "joined," "connected," or synonyms thereof, and all forms thereof, does not necessarily negate the presence of one or more intermediate elements between two elements that are, for example, "connected" or "coupled" to each other or "coupled" to each other. In the claims and the specification, the term "optional," if any, should be understood as a term that represents the same meaning as the universal symbol ∀, unless otherwise specified. For example, the phrase "for any X" has the same meaning as "for all X" or "for each X."

[0078] Unless otherwise specified, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Furthermore, terms such as those defined in commonly used dictionaries should be interpreted to have a meaning consistent with their meaning in the context of the relevant art and this disclosure, and should not be interpreted ideally or excessively formally unless explicitly defined.

[0079] It will be understood that in describing the present invention, many techniques and steps are disclosed. Each of these has distinct advantages, and each can be used in combination with one or more, or in some cases all, of the other disclosed techniques. Therefore, to avoid cluttering, this specification will refrain from describing every possible combination of individual techniques or steps. Nevertheless, the specification and claims should be read with the understanding that such combinations are fully within the scope of the present invention and claims.

[0080] The corresponding structures, materials, acts, and equivalents of all functional elements combined with means or steps in the following claims are intended to include the structures, materials, or acts, if any, that perform the function in combination with other elements.

[0081] Although the present invention has been described above with reference to exemplary embodiments, it is not limited to these embodiments. Various modifications and variations are possible without departing from the spirit of the present invention. The selected and described embodiments are intended to illustrate the principles of the present invention and its practical application. The present invention may be used in various embodiments with various modifications and variations, which are determined according to the expected use. All such modifications and variations are intended to be included within the scope of the present invention, as defined by the appended claims, and are intended to be accorded the same protection when interpreted in accordance with the breadth that is fairly, legally, and equitably to be given. [Explanation of symbols]

[0082] 1. Wireless communication systems 100 Radio Antenna 110 Waveguide 111 Long side 112 Optical Fiber 113 Short side 120 Mass 150 plates 160 Conduction Path 170 Holder 200 Communication terminal 310 Mounting parts 320 Slider 330 Transport Robot 350 Branching Waveguide 360 Connector 400 Temperature Control Device 800 signal generator 920 Dielectric Attachment 110a track 120a groove 120b Relatively high area 120c Relatively low part 120d rail section 120d1 First rail section 120d2 Second rail section 120h hole 120k cylindrical convex part 120p periodic structure 120p1 1st periodic structure 120p2 2nd periodic structure 120s Dielectric 120v base 370a Antenna equipment 370b Antenna equipment 380a Photoelectric converter 380b Photoelectric converter

Claims

1. A wireless antenna capable of transmitting and receiving signals in the millimeter wave band or quasi-millimeter wave band, a cable-shaped waveguide formed of a dielectric; A mass formed of dielectric material Including, the dielectric constant of the waveguide is greater than the dielectric constant of the surroundings of the waveguide excluding the mass; the mass is located on or near the waveguide; the mass has a periodic structure in which the dielectric constant changes periodically in the longitudinal direction of the waveguide, The period of the periodic structure is A, θ is an angle formed between the radiation direction in which the electromagnetic wave propagating through the waveguide is most strongly radiated from the mass and the normal direction of the waveguide at the position of the mass; The wavelength of the electromagnetic wave propagating through the waveguide is λ g year, The wavelength in free space of the electromagnetic wave radiated from the mass is λ 0 As, [Equation 5] holds true A radio antenna characterized by:

2. A wireless antenna capable of transmitting and receiving signals in the millimeter wave band or quasi-millimeter wave band, a cable-shaped waveguide formed of a dielectric; A mass formed of dielectric material Including, the dielectric constant of the waveguide is greater than the dielectric constant of the surroundings of the waveguide excluding the mass; the mass is located on or near the waveguide; the mass has a periodic structure in which the dielectric constant changes periodically in the longitudinal direction of the waveguide, The length of the mass in a width direction perpendicular to the longitudinal direction of the waveguide and perpendicular to the normal direction of the waveguide does not match the width of the waveguide. A radio antenna characterized by:

3. A wireless antenna capable of transmitting and receiving signals in the millimeter wave band or quasi-millimeter wave band, a cable-shaped waveguide formed of a dielectric; A mass formed of dielectric material Including, the dielectric constant of the waveguide is greater than the dielectric constant of the surroundings of the waveguide excluding the mass; the mass is located on or near the waveguide; the mass has a periodic structure in which the dielectric constant changes periodically in the longitudinal direction of the waveguide, Both ends of the mass in the longitudinal direction of the waveguide have a tapered structure that tapers in the longitudinal direction of the waveguide. A radio antenna characterized by:

4. A wireless antenna capable of transmitting and receiving signals in the millimeter wave band or quasi-millimeter wave band, a cable-shaped waveguide formed of a dielectric; A mass formed of dielectric material Including, the dielectric constant of the waveguide is greater than the dielectric constant of the surroundings of the waveguide excluding the mass; the mass is located on or near the waveguide; the mass has a periodic structure in which the dielectric constant changes periodically in the longitudinal direction of the waveguide, Furthermore, a periodic structure changing device that mechanically changes the period of the periodic structure is included. A radio antenna characterized by:

5. A wireless antenna capable of transmitting and receiving signals in the millimeter wave band or quasi-millimeter wave band, a cable-shaped waveguide formed of a dielectric; A mass formed of dielectric material Including, the dielectric constant of the waveguide is greater than the dielectric constant of the surroundings of the waveguide excluding the mass; the mass is located on or near the waveguide; the mass has a periodic structure in which the dielectric constant changes periodically in the longitudinal direction of the waveguide, Further, a temperature control device for changing the temperature of the mass is included. A radio antenna characterized by:

6. A wireless communication system including a wireless antenna and a communication terminal, The wireless antenna includes a cable-like waveguide formed of a dielectric and a mass formed of a dielectric, the dielectric constant of the waveguide is greater than the dielectric constant of the surroundings of the waveguide excluding the mass; the mass is located on or near the waveguide; the mass has a periodic structure in which the dielectric constant changes periodically in the longitudinal direction of the waveguide, The period of the periodic structure is A, θ is an angle formed between the radiation direction in which the electromagnetic wave propagating through the waveguide is most strongly radiated from the mass and the normal direction of the waveguide at the position of the mass; The wavelength of the electromagnetic wave propagating through the waveguide is λ g , Let the wavelength in free space of the electromagnetic wave radiated from the mass be λ 0 , [Equation 6] is established, the communication terminal receives the electromagnetic waves radiated from the mass with an antenna of the communication terminal; The mass receives electromagnetic waves from the antenna of the communication terminal. A wireless communication system comprising:

Images