JP7558105B2 - Radio antennas, wireless communication systems - Google Patents

Description

The present invention relates to a wireless antenna and a wireless communication system using this wireless antenna.

Currently, mobile wireless communication services using electromagnetic waves, such as mobile phones, are widely used. Using such wireless communication services, services that require high communication speeds and large communication capacity, such as video distribution, are provided to users. For this reason, efforts are being made to increase the speed and capacity of wireless communication services in order to cope with the dramatic increase in data traffic. In wireless communication, generally, the wider the frequency bandwidth used, the faster the communication speed and the larger the communication capacity. Therefore, operators who provide wireless communication services wish to secure channels with as wide a frequency bandwidth as possible. However, there are restrictions on the use of frequencies used in wireless communication, and it is generally difficult to secure wideband channels near the frequency bands used in mobile communication.

Therefore, in order to obtain a channel with a wide bandwidth, application to mobile communications in the high-frequency range called millimeter waves (30 GHz to 300 GHz) and quasi-millimeter waves (there is no clear definition, but it is approximately 20 GHz to 30 GHz) is being considered (Non-Patent Document 1).

"Docomo 5G White Paper: Requirements and Technical Concepts for 5G Wireless Access after 2020," NTT Docomo, Inc., September 2014

As is well known, in such high frequency ranges, compared to the frequency range of several GHz or less used in mobile wireless communications, the loss of coaxial cables, which have been widely used as transmission cables up to now, is high, making it difficult to use a coaxial cable to connect a device that generates a transmission signal and an antenna installed at a distance. Therefore, it becomes necessary to place the device that generates the transmission signal as close to the antenna as possible, or to manufacture the device that generates the transmission signal and the antenna as a single unit.

There is also another problem with using high frequency ranges. According to the Friis propagation law (1), the received power P of an electromagnetic wave at a receiving antenna installed at a point a distance D away from the transmitting antenna is inversely proportional to the square of the frequency f. c is the speed of light, G _S is the transmitting antenna gain, G _R is the receiving antenna gain, and P _S is the transmitting power.

For this reason, when using high frequency bands, the service area covered by one transmitting antenna is narrower than when using frequencies below a few GHz, and in order to cover a service area of the same size as a conventional service area, the antenna gain must be increased, resulting in the need for multiple antennas. When multiple antennas are provided, for example, a method can be considered in which a signal from one transmitting device is distributed and transmitted to multiple antennas located at distant locations, but as mentioned above, when using coaxial cables, the loss is large and efficiency is poor. When a device for generating a transmission signal is placed near each antenna, or when the antennas and the device for generating a transmission signal are manufactured as a single unit, the cost increases by the number of devices for generating a transmission signal.

The present invention aims to provide a wireless antenna that can form a service area easily and at low cost, and a wireless communication system that uses this wireless antenna.

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 those who are not beneficiaries of 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, a mass made of a dielectric material is located on or near the dielectric waveguide, and an electric conductor located near the mass is located on the dielectric waveguide. The dielectric waveguide has a dielectric constant greater than the dielectric constant of the surroundings excluding the electric conductor. The mass is a portion that radiates and absorbs electromagnetic waves. Transmission and reception of electromagnetic waves is realized 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.

According to the present invention, the electromagnetic wave radiating or absorbing portion is realized on the dielectric waveguide or in a mass adjacent to the dielectric waveguide, so that a service area can be formed easily and at low cost.

An example of a wireless antenna configuration. An example of a wireless antenna configuration. An example of a wireless antenna configuration. An example of a wireless antenna configuration. 1A to 1F are cross-sectional views of a dielectric waveguide. (a) First example. (b) Second example. (c) Third example. (d) Fourth example. (e) Fifth example. (f) Sixth example. FIG. 13 shows the transmission loss and return loss of a waveguide without a mass. FIG. 1 shows the transmission loss of a waveguide with a mass and the return loss. FIG. 13 is a diagram showing a radiation pattern at a site where a mass is present. FIG. 2 is a diagram for explaining the definitions of the azimuth angle φ and the polar angle θ. 1A is a cross-sectional view of a dielectric waveguide in the vicinity of a mass, (a) a first example, (b) a second example, and (c) a third example. An example of a dielectric waveguide with a branching structure. A structure in which a dielectric waveguide is connected to a medium. (a) First example. (b) Second example.

An embodiment of the present invention will be described with reference to the drawings. The wireless communication system 1 of the embodiment includes a wireless antenna 100 of the embodiment, a communication terminal 200, and a signal generating device 800. As shown in Figs. 1 to 4, the wireless antenna 100 has a configuration including a long and thin cable-like waveguide 110 formed of a dielectric, one or more lumps 110c formed of a dielectric, and one or more electrical conductors 114. The waveguide 110 may extend linearly as shown in Figs. 2 to 4, or may extend slightly meanderingly as shown in Fig. 1, in other words, with a bend that does not adversely affect the low-loss propagation of the waveguide 110 described later, or may have a branched structure. The branched structure of the waveguide 110 will be described later. Each mass 110c will be described in detail later, but it may be the same dielectric as the waveguide 110, or may be a different dielectric from the waveguide 110. Each mass 110c is located on the waveguide 110. In this case, the mass 110c protrudes from the waveguide 110 like a protrusion. Alternatively, each mass 110c is located in the vicinity of the waveguide 110 away from the waveguide 110. Alternatively, n masses 110c (where n is a predetermined integer satisfying 1≦n<N) out of N masses 110c (where N is a predetermined integer satisfying 1≦n<N) are located on the waveguide 110, and the remaining N−n masses 110c are located in the vicinity of the waveguide 110 away from the waveguide 110. Each electrical conductor 114 is, for example, a thin plate-like metal (for example, malleable copper, aluminum, etc.). The electrical conductor 114 is located on the waveguide 110, as will be described in detail later. However, the position of the mass 110c and the position of the electrical conductor 114 do not overlap. In this embodiment, one end of the waveguide 110 is connected to a signal generator 800 that generates a signal having a frequency of millimeter waves (30 GHz to 300 GHz) or quasi-millimeter waves (approximately 20 GHz to 30 GHz, although there is no clear definition). There is no limitation on the type of signal, and it may be an analog signal, a digital signal, a discrete time signal, or a continuous time signal. The other end of the waveguide 110 is open and not connected to anything in the examples shown in Figures 1 to 4, but it may be short-circuited, connected to an antenna (e.g., a linear antenna, an aperture antenna, etc.), or may be terminated.

The waveguide 110 has a cross section with a constant shape and size, as shown in FIG. 5(a), which is a cross section perpendicular to the longitudinal direction at any position in the longitudinal direction of the waveguide 110 (excluding the portion where the mass 110c exists). In this example, the cross section of the waveguide 110 is rectangular. Therefore, the elongated rectangular parallelepiped waveguide 110 has two long side surfaces 111 that face each other in a direction perpendicular to the longitudinal direction of the waveguide 110, and two short side surfaces 113 that face each other in a direction perpendicular to the longitudinal direction of the waveguide 110. The long side surfaces 111 are sides whose width (i.e., the length in the direction perpendicular 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 111 are sides 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 except for the area where the mass 110c is present, that is, the cross-sectional shape and size are both constant at any position (except for the area where the mass 110c is present), and the material is constant at any position (except for the area where the mass 110c is present). Note that in FIG. 5(a), the cross-sectional shape of the waveguide 110 is rectangular, but it is not limited to this structure and may be, for example, a square or semicircle.

The dielectric constant of the waveguide 110 is greater than the dielectric constant of the surroundings of the waveguide 110 (excluding the electrical conductor 114). In the example shown in FIG. 5(a), 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 110c, 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 toward the other end of the waveguide 110, reaching the other end of the waveguide 110.

The shape of each lump 110c is not limited, and may be, for example, a polygonal prism, a cylinder, a sphere, or a part of any of these. When the total number of lumps 110c is two or more, the shape shared by some of these lumps 110c may be the same as or different from the shape shared by some or all of the other lumps 110c. Alternatively, any two different lumps 110c among these lumps 110c may have different shapes. Furthermore, when the number of lumps 110c is two or more, the size shared by some of these lumps 110c may be the same as or different from the size shared by some or all of the other lumps 110c. Alternatively, any two different lumps 110c among these lumps 110c may have different sizes.

The shape of each electrical conductor 114 is not limited, and may be, for example, an ellipse, a circle, a rectangle, or a square. However, it is preferable that the width of each electrical conductor 114 (i.e., the length in a direction perpendicular to the longitudinal direction of the waveguide 110) is greater than the width of the waveguide 110 (i.e., the length in a direction perpendicular to the longitudinal direction of the waveguide 110). The total number of electrical conductors 114 is usually one, but when the total number of electrical conductors 114 is two or more, the shape that some of these electrical conductors 114 have in common may be the same as or different from the shape that other parts or all of these electrical conductors 114 have in common. Alternatively, when the total number of electrical conductors 114 is two or more, any two different electrical conductors 114 among these electrical conductors 114 may have different shapes. Furthermore, when the number of electrical conductors 114 is two or more, the size that some of these electrical conductors 114 share in common may be the same as or different from the size that some or all of the other electrical conductors 114 share in common. Alternatively, any two different electrical conductors 114 among these electrical conductors 114 may have different sizes.

The position of the mass 110c on the waveguide 110 in the longitudinal direction is preferably a position excluding both ends of the waveguide 110, and more preferably a position where mismatching is unlikely to occur and conversion of the propagation mode is unlikely to occur. When the total number of masses 110c is two or more, the distances measured from one end of the waveguide 110 along its longitudinal direction of any two different masses 110c among these masses 110c may be different from each other, or, for example, the distances measured from one end of the waveguide 110 along its longitudinal direction of two or more different masses 110c may be equal to each other. In the latter case, these two or more masses 110c are located at different positions on the circumference of the waveguide 110. In the former case, the position of the mass 110c on the waveguide 110 in the circumferential direction is a part of a closed curve in the circumferential direction of the waveguide 110 (strictly speaking, a simple closed curve, that is, the edge of a cross section perpendicular to the longitudinal direction of the waveguide 110), and in the latter case, the positions of two or more masses 110c on the closed curve do not overlap with each other.

The position of the electrical conductor 114 on the waveguide 110 in the longitudinal direction is in the vicinity of at least one mass 110c corresponding to the electrical conductor 114 (see FIG. 1). This "vicinity" is understood as follows. The position of the electrical conductor 114 on the waveguide 110 in the circumferential direction is a part of the closed curve on which the mass 110c corresponding to the electrical conductor 114 is located. However, it is preferable that the positions of the electrical conductor 114 and the mass 110c do not overlap with each other on the closed curve, and that the electrical conductor 114 is as far away from the mass 110c as possible on the closed curve. For example, when the shape of the waveguide 110 is an elongated rectangular parallelepiped as described above and the mass 110c is located on one of the pair of long side surfaces 111, it is preferable that the electrical conductor 114 is located on the other of the pair of long side surfaces 111 (examples of Figures 5(b), (e), and (f) described later), and when the shape of the waveguide 110 is an elongated semicylindrical body, it is preferable that the mass 110c is located in the center of the curved surface and the electrical conductor 114 is located on the flat surface (example of Figure 5(c) described later). Also, when the mass 110c is viewed from the front in a direction perpendicular to the longitudinal direction of the waveguide 110, the electrical conductor 114 and the mass 110c are in an overlapping positional relationship.

The length of each electrical conductor 114 (i.e., the length in the longitudinal direction of the waveguide 110) is preferably greater than the length of the mass 110c (i.e., the length in the longitudinal direction of the waveguide 110) when the total number of masses 110c corresponding to the electrical conductor 114 is 1, and is preferably greater than the distance between the two masses 110c that are furthest from each other along the waveguide 110 among the two or more masses 110c when the total number of masses 110c corresponding to the electrical conductor 114 is two or more. For example, if the total number of electrical conductors 114 is 1 and the total number of masses 110c is N (N≧2), then N masses 110c correspond to one electrical conductor 114, and since one electrical conductor 114 is located in the vicinity of N masses 110c, one electrical conductor 114 is located on the waveguide 110 straddling two masses 110c that are furthest from each other along the waveguide 110 among the N masses 110c (see FIG. 2). Also, for example, when the total number of electrical conductors 114 is M (M≧2) and the total number of lumps 110c is N (N≧2), typically M=N is preferred, and one electrical conductor 114 is located near one corresponding lump 110c (see FIG. 1), but when M<N, there will be one or more electrical conductors 114 that span two or more lumps 110c (see FIG. 3), and when M>N, there will be one or more electrical conductors 114 that do not have a corresponding lump 110c (see FIG. 4).

Regarding the former, Fig. 5(b), which is a cross-sectional view perpendicular to the longitudinal direction of the rectangular parallelepiped waveguide 110, shows an example in which one triangular prism mass 110c exists on one of the two opposing long side surfaces 111, the width of the mass 110c, i.e., the height of the triangular prism, is equal to the length of the long side of the cross section, and one electrical conductor 114 exists on the other side. Fig. 5(c), which is a cross-sectional view perpendicular to the longitudinal direction of the semicylindrical waveguide 110, shows an example in which one approximately spherical mass 110c exists in the center of the semicylindrical side surface of the waveguide 110, and one electrical conductor 114 exists on the flat side surface of the waveguide 110. FIG. 5(e) shows a cross-sectional view along the longitudinal direction of the rectangular parallelepiped waveguide 110 when the mass 110c is a triangular prism, and FIG. 5(f) shows a cross-sectional view along the longitudinal direction of the rectangular parallelepiped waveguide 110 when the mass 110c is a semi-cylinder. In FIG. 5(e) and FIG. 5(f), one electrical conductor 114 is attached to the waveguide 110 over almost the entire length of the waveguide 110.

In the example where the mass 110c is located on the waveguide 110, each mass 110c may be formed integrally with the waveguide 110 or may be formed separately from the waveguide 110. In the latter case, each mass 110c is attached to the waveguide 110, but may not be removable thereafter, or may be removable from the waveguide 110. Even if each mass 110c is removable from the waveguide 110, it is desirable that each mass 110c does not move on the waveguide 110 once it is attached to the waveguide 110. Each mass 110c is in close contact with the waveguide 110. For this reason, when the mass 110c is attached to the waveguide 110, the mass 110c has a contact surface having the same surface shape as the local surface shape of the portion of the waveguide 110 to which the mass 110c is attached. For example, if the waveguide 110 is an elongated rectangular parallelepiped, the contact surface of the mass 110c is composed of at least one plane (see FIG. 5(b)), and if the waveguide 110 is an elongated cylinder, the contact surface of the mass 110c is a part of the cylindrical surface (see FIG. 5(c)). When an adhesive or pressure-sensitive adhesive is used to adhere the mass 110c 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 approximately the same as the dielectric constant of the mass 110c.

In an example where the mass 110c is located near the waveguide 110 away from the waveguide 110, the upper limit of the distance between the mass 110c and the waveguide 110 is determined by the dielectric constant of the mass 110c, the dielectric constant of the waveguide 110, the dielectric constant of the medium between the mass 110c and the waveguide 110 (air or foamed plastic can be exemplified as the medium), the strength of the signal propagating through the waveguide 110, the cross-sectional shape of the waveguide 110, the cross-sectional size of the waveguide 110, etc. However, here, the "distance between the mass 110c and the waveguide 110" refers to the shortest distance between any point on the mass 110c and any point on the waveguide 110. If the distance between the mass 110c and the waveguide 110 is equal to or less than the upper limit, the mass 110c functions as a radiating part or a receiving part, which will be described later. In other words, the "proximity of the waveguide" where the mass is located is the range in which mass 110c can function as a radiator or receiver, as described below.

The positional relationship between the mass 110c and the waveguide 110 may be a permanent relationship or a temporary relationship. In the case of a permanent relationship, for example, as shown in FIG. 10(a), the mass 110c is fixed to a mounting part 310 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 110c and the waveguide 110 (for example, a part or the whole of the mounting part 310 when the material of the mounting part 310 is metal). The mounting part 310 plays the role of a holder that holds the mass 110c and the role of a spacer that keeps the distance between the mass 110c and the waveguide 110 constant.

In the case of a temporary relationship, for example, as shown in FIG. 10(b), the mass 110c 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 (for example, a part or the whole of the slider 320 when the material of the slider 320 is a metal) between the mass 110c and the waveguide 110. The slider 320 plays the role of a holder that holds the mass 110c and the role of a spacer that keeps the distance between the mass 110c and the waveguide 110 constant.

As another example of a temporary relationship, the mass 110c is attached to a movable object (e.g., footwear, an anklet, or other object worn on the human body, or a transport robot), and the waveguide 110 is entirely or partially embedded in a structure such as a floor or a passageway. FIG. 10(c) shows an example in which the movable object is a transport robot 330. In this case, when a movable object moving on a structure approaches the waveguide 110, that is, when the mass 110c attached to the movable object enters a range where the distance from the waveguide 110 is equal to or less than the upper limit, the mass 110c functions as a radiator or receiver, which will be described later. When 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 generating device 800 (which may be a receiver or a transmitter/receiver, but is not limited to the signal generating device 800, as will be described later) and the receiver or transmitter of the movable object. In an example where mass 110c is attached to a movable object, electromagnetic radiation occurs only when the movable object approaches waveguide 110, improving the efficiency of energy utilization.

Each electrical conductor 114 may be either indestructible or removable from the waveguide 110. Even if a certain mass 110c is removable from the waveguide 110, one or more electrical conductors 114 corresponding to the removable mass 110c may be either indestructible or removable from the waveguide 110. Once each electrical conductor 114 is attached to the waveguide 110, it is desired that each electrical conductor 114 does not move on the waveguide 110. Each electrical conductor 114 is in close contact with the waveguide 110. Therefore, when attaching the electrical conductor 114 to the waveguide 110, the electrical conductor 114 has a contact surface having the same surface shape as the local surface shape of the portion of the waveguide 110 to which the electrical conductor 114 is attached. For example, if the waveguide 110 is an elongated rectangular parallelepiped, the contact surface of the electrical conductor 114 is composed of at least one flat surface (see FIG. 5(b)). A well-known adhesive or pressure sensitive adhesive can be used to attach the electrical conductor 114 to the waveguide 110.

Not limited to the examples shown in Figures 5(a) to (c), a covering portion 110b formed of a dielectric may be arranged on the outer periphery of a waveguide 110 having one or more lumps 110c (see Figure 5(d) which is a cross-sectional view perpendicular to the longitudinal direction of the waveguide 110). In Figure 5(d), the electrical conductor 114 is not covered with the covering portion 110b, but of course, a configuration in which the electrical conductor 114 is covered with the covering portion 110b is also allowed. The covering portion 110b is in close contact with the waveguide 110 and the lumps 110c on the waveguide 110. Not limited to the example shown in Figure 5(d), the covering portion 110b may cover the waveguide 110 except for the lumps 110c, or except for the part of the waveguide 110 where the lumps 110c are located and the lumps 110c. The dielectric constant of the waveguide 110 and the dielectric constant of the lumps 110c are greater than the dielectric constant of the covering portion 110b. Therefore, if the mass 110c is not present, 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 toward the other end of the waveguide 110, reaching the other end of the waveguide 110.

Each mass 110c can function as a radiation section that radiates electromagnetic waves (radio waves in terms of band). The power lost by the radiation of electromagnetic waves in the mass 110c mainly depends on the shape, size, number and dielectric constant of the mass 110c. From the viewpoint of radiating electromagnetic waves with stronger power, for example, it is preferable that the dielectric constant of the mass 110c is the same as or larger than that of the waveguide 110. More preferably, from the viewpoint of loss, a material with a small dielectric tangent in the frequency band of the electromagnetic waves used is selected as the dielectric of each of the waveguide 110 and the mass 110c. In general, the higher the dielectric constant, the larger the dielectric tangent, so the dielectric constant that each of the dielectrics of the waveguide 110 and the mass 110c should have is determined taking into account the amount of radiation and the amount of loss. In this way, when the mass 110c exists, the signal from the signal generating device 800 is radiated as electromagnetic waves by this mass 110c. Here, "radiation" means that the power of the signal that reaches the mass 110c that is lost due to electromagnetic radiation exceeds the transmission loss that would actually occur if the mass 110c did not exist. The power lost by electromagnetic radiation at the mass 110c is usually only a portion of the power of the signal that reaches the mass 110c, and the signal with the remaining power passes through the part of the waveguide 110 where the mass 110c is located. The signal that passes through the mass 110c travels through the waveguide 110 toward the adjacent mass 110c, or toward the other end of the waveguide 110 if there is no adjacent mass 110c, with low loss. The electromagnetic waves radiated by the mass 110c are received by a wireless antenna (not shown) of a communication terminal 200 such as a mobile phone.

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, with reference to 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.

The waveguide 110 may have a branched structure. There are no limitations on the branch shape or number of branches. FIG. 11 shows an example of a T-shaped waveguide 110 with two branches. The waveguide 110 with a branched structure may have a configuration as a single product (in other words, an integrally molded structure), 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 branched waveguide 350 can be adopted as a connection between the sub-waveguides.

In the above embodiment, one end of the waveguide 110 is physically connected to the signal generating device 800, but this configuration is not limited to this. For example, as shown in FIG. 12, one end of the waveguide 110 may be connected to a part of a medium capable of propagating electromagnetic waves, and the other part 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 (for example, a coaxial line, or a waveguide having a dielectric constant different from that of the waveguide 110), or air. 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 means a physical aspect in which electromagnetic waves can propagate. When the medium is the line 110a, the line 110a and the waveguide 110 are connected to each other using, for example, a connector 360, as shown in FIG. 12(a). When the medium is air, as shown in FIG. 12B, 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 the 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 alignment between the antenna device 370a attached to the signal generating device 800 and one end of the waveguide 110 is good, the one end of the waveguide 110 may directly receive a signal from the signal generating device 800.

When the shape of the waveguide 110 is an elongated rectangular parallelepiped as described above, it is preferable that the width of the short side surface 113 (i.e., the length in the direction perpendicular to the longitudinal direction of the waveguide 110) is approximately half the width of the short side surface 113 of the waveguide 110 that passes signals of the same frequency band in the absence of the electrical conductor 114.

Figure 6 shows the transmission loss (S parameter: S21) and reflection loss (S parameter: S11) at around 28 GHz for a waveguide 110 (dielectric constant: 2, short side: 4 mm, long side: 12 mm, length: 50 mm) surrounded by air (dielectric constant: 1). However, this waveguide 110 does not have a mass 110c. From the transmission loss in Figure 6, it can be seen that when no mass 110c is present in the waveguide 110, the signal passes with low loss. Also, from the reflection loss in Figure 6, it can be seen that impedance matching with the load is achieved.

Figure 7 shows the transmission loss (S parameter: S21) and reflection loss (S parameter: S11) of a waveguide 110 (dielectric constant: 2, short side: 4 mm, long side: 12 mm, length: 50 mm) surrounded by air (dielectric constant: 1) at around 28 GHz. However, this waveguide 110 has one mass 110c (dielectric constant: 2) on the long side 111 of the waveguide 110 at a position 30 mm from one end of the waveguide 110. The shape of the mass 110c is a triangular prism, the length of the base is 5 mm, and the length of the triangular prism (i.e., the height of the triangular prism) is 12 mm, the same as the long side of the waveguide 110. From the transmission characteristics in Figure 7, it can be seen that when the mass 110c exists in the waveguide 110, electromagnetic waves are radiated from the mass 110c. Also, from the reflection loss in Figure 7, it can be seen that impedance matching with the load is achieved. Therefore, most of the loss caused by attaching mass 110c to waveguide 110 is due to the radiation of electromagnetic waves outside waveguide 110.

Figure 8 shows the radiation pattern of a waveguide 110 (dielectric constant: 2, short side: 4 mm, long side: 12 mm, length: 50 mm) surrounded by air (dielectric constant: 1) at a location where a mass 110c exists. However, this waveguide 110 has one mass 110c (dielectric constant: 1.5) on each of the long side surfaces 111 of the waveguide 110 at a position 15 mm from one end of the waveguide 110. The shape of the mass 110c is a triangular prism, with the length of the base being 5 mm, and the length of the triangular prism (i.e. the height of the triangular prism) being 12 mm, the same as the long side of the waveguide 110. The radiation pattern is shown by the azimuth angle φ and polar angle θ defined in Figure 9. Waveguide 110 is arranged so that the width direction of its short side surface coincides with the x direction, the width direction of its long side surface coincides with the y direction, and its height direction (i.e., the longitudinal direction of waveguide 110) coincides with the z direction. Figure 8 shows the gain (dBi) in the range of φ=0 degrees and -180≦θ≦180 degrees. From Figure 8, it can be seen that there is a strong region with a gain of 0 dBi or more in the front direction (φ=0 degrees, θ=±30 degrees) of long side surface 111 of waveguide 110, that is, in the direction in which mass 110c protrudes, and electromagnetic waves are radiated.

When the waveguide 110 has two or more masses 110c, the total number of masses 110c is determined according to the desired power lost due to electromagnetic radiation. The power of the signal from the signal generating device 800 input to the one end of the waveguide 110 must be the sum of the power lost due to electromagnetic radiation at each mass 110c and the other end of the waveguide 110, plus the transmission loss that actually occurs in the part of the waveguide 110 that functions as a waveguide.

Alternatively, when the power of the signal from the signal generating device 800 input to the one end of the waveguide 110 (hereinafter referred to as the input power) is determined in advance, the power obtained by subtracting the transmission loss actually occurring in the part of the waveguide 110 that functions as a waveguide from the input power is distributed to the power lost by electromagnetic radiation between each mass 110c and the other end of the waveguide 110, and the degree of radiation in each mass 110c is determined according to the distributed power. For example, there are cases where equal radiation loss is desired in each mass 110c. In this case, assuming that there are N masses 110c, and the masses are called the first, second, ..., i-th, ..., N-th masses 110c from the side closest to the signal generating device 800, the degree of radiation of the i-th mass 110c may be adjusted so that the proportion of the power represented by formula (2) of the power of the signal reaching the part where the i-th mass 110c is located is lost by radiation. In this case, in the Nth mass 110c, almost all of the power of the signal that reaches it is lost by radiation, so there is almost no radiation of electromagnetic waves at the other end of the waveguide 110. For example, when N=5, the first, second, third, and fourth masses 110c radiate -7 dB (one fifth), -6 dB (one quarter), -4.8 dB (one third), and -3 dB (one half) of the signal that reaches them, respectively, as electromagnetic waves, and the fifth mass 110c radiates as much of the power of the signal that reaches it as electromagnetic waves as possible.

According to equation (2), the ratio of the power of the signal reaching the i-th mass 110c to the radiation loss increases as i increases, so the shape and size of mass 110c are selected so that the radiation power at the i-th mass 110c increases as i increases.

In the wireless antenna 100 of the embodiment, the adhered state of the mass 110c that causes part of the waveguide 110 to function as an electromagnetic wave radiator can be released at any time unless the adhered state of the mass 110c is maintained in a permanent manner. In other words, the adhered state of the mass 110c continues to be maintained during the period when it is necessary to cause part of the waveguide 110 to function as an electromagnetic wave radiator, but when this need is no longer necessary, the adhered state of the mass 110c at the part that functions as a radiator is released. The part where the adhered state is released loses its function as an electromagnetic wave radiator and functions as a waveguide. Therefore, the position of the electromagnetic wave radiator, i.e., the position where the mass 110c is attached to the waveguide 110, can be easily changed in response to changes in the service area.

The above-mentioned 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 by the receiving section (the mass 110c when the wireless antenna 100 is used as a transmitting antenna) and transmitted to the receiving device by the waveguide 110. The 3 dB loss occurs when the electromagnetic waves absorbed by the receiving section are distributed toward the one end and the other end of the waveguide 110. A transmitting/receiving device having both a transmitting function and a receiving function may be connected to the one end of the waveguide 110 instead of the signal generating device 800. In addition, (1) a configuration 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 in which a receiving device is connected to the other end of the waveguide 110 to which a transmitting/receiving device is connected, (3) a configuration 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 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, according to the configurations (2), (3), and (4), the above-mentioned 3 dB loss can be eliminated by a combining device (not shown) combining the electromagnetic waves received by the receiving functions of the devices connected to both ends of the waveguide 110.

The technical features disclosed in the various embodiments described above are not necessarily mutually exclusive. Technical features of one embodiment may be applied to technical features of other embodiments, provided there is no contradiction from a technical point of view.

<Addendum>
In the specification and claims, the term "connected" and all variations thereof mean a direct or indirect connection between two or more elements, and may include the presence of one or more intermediate elements between two elements that are "connected" to each other.

In the specification and claims, the term "comprises" and its conjugations are used as non-exclusive expressions. For example, the sentence "X includes A and B" does not deny that X includes components other than A and B (e.g., C where C ≠ A and C ≠ B). Also, when a sentence in the specification and claims contains a phrase in which the term "comprises" or its conjugations are combined with a negation, the sentence only refers to the object of the term "comprises" or its conjugations. Thus, for example, the sentence "X does not include A and B" acknowledges the possibility that X may include components other than A and B. Furthermore, the term "or" used in the specification or claims is not intended to be an exclusive or.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments. Various modifications and variations are permitted within the scope 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 can 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 afforded.

Claims (10)

A wireless antenna capable of transmitting and receiving millimeter wave or quasi-millimeter wave signals,
The waveguide includes a cable-like waveguide formed of a dielectric material, a mass formed of a dielectric material, and an electrical conductor;
the mass is located proximate the waveguide;
the electrical conductor is located on the waveguide in the vicinity of the mass,
A radio antenna in which the dielectric constant of the waveguide is greater than the dielectric constant of the surroundings of the waveguide excluding the electrical conductor. 2. The radio antenna according to claim 1,
A radio antenna, characterized in that the vicinity of the waveguide is within a range in which the mass can radiate electromagnetic waves or absorb electromagnetic waves. 2. The radio antenna according to claim 1 ,
The above-mentioned waveguide has a branched structure.
A radio antenna comprising : 4. The radio antenna according to claim 3,
The radio antenna is characterized in that the waveguide having the branch structure has an integrally molded structure or a configuration in which a plurality of sub-waveguides having the same structure are connected. 2. The radio antenna according to claim 1 ,
The waveguide is connected to a medium capable of propagating electromagnetic waves.
A radio antenna comprising : 6. The radio antenna according to claim 5,
A radio antenna, wherein the medium is a line made of a material different from that of the waveguide, or air. A radio antenna according to any one of claims 3 to 6,
A radio antenna, characterized in that the vicinity of the waveguide is within a range in which the mass can radiate electromagnetic waves or absorb electromagnetic waves. A wireless communication system including a wireless antenna and a communication terminal,
The wireless antenna includes a cable-shaped waveguide formed of a dielectric, a mass formed of a dielectric, and an electrical conductor;
the mass is located proximate the waveguide;
the electrical conductor is located on the waveguide in the vicinity of the mass,
the dielectric constant of the waveguide is greater than the dielectric constant of the surroundings of the waveguide excluding the electrical conductor;
the communication terminal receives the electromagnetic waves radiated from the mass with an antenna of the communication terminal;
A wireless communication system characterized in that the mass receives electromagnetic waves from an antenna of the communication terminal. 9. The wireless communication system according to claim 8 ,
The above-mentioned waveguide has a branched structure.
1. A wireless communication system comprising: 9. The wireless communication system according to claim 8 ,
The waveguide is connected to a medium capable of propagating electromagnetic waves.
1. A wireless communication system comprising:

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