Antenna device and antenna unit

Abstract

To provide an antenna device which operates with high gain in a plurality of frequency bands and also has high gain in a horizontal direction.SOLUTION: An antenna device 100 includes: a plurality of multi-resonance antenna bodies 40; a first antenna 10 for operating as a zeroth-order resonance antenna in a first frequency band; and a second antenna 20 for operating in a second frequency band different from the first frequency band.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The disclosure herein relates to an antenna device and an antenna unit. [Background technology]

[0002] Patent Document 1 discloses an antenna device that increases the directional gain of a first antenna in a predetermined direction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2023-521949 Summary of the Invention [Problem to be solved by the invention]

[0004] The antenna device disclosed in Patent Document 1 is not configured to be operable in multiple frequency bands.

[0005] One disclosed object is to provide an antenna device that operates with high gain in multiple frequency bands and has high gain in the horizontal direction. [Means for solving the problem]

[0006] The antenna device disclosed herein comprises: The antenna includes a plurality of multi-resonance antenna bodies (40) each having a first antenna (10) that operates as a zero-order resonant antenna in a first frequency band and a second antenna (20) that operates in a second frequency band different from the first frequency band.

[0007] The multi-resonance antenna of the present disclosure has a first antenna that operates in a first frequency band and a second antenna that operates in a second frequency band, and therefore operates in multiple frequency bands. In addition, the first antenna operates as a zero-order resonance antenna and is omnidirectional in the horizontal direction. By combining multiple multi-resonance antennas with such a configuration and performing phase control, an antenna device can be realized that operates with high gain in multiple frequency bands and has high gain in the horizontal direction in the first frequency band.

[0008] The antenna unit disclosed herein comprises: The antenna device (100) includes a plurality of multi-resonance antenna elements (40), each of which has a first antenna (10) that operates as a zero-order resonant antenna in a first frequency band and a second antenna (20) that operates in a second frequency band different from the first frequency band, and a phase control device (80) that performs phase control on signals transmitted and received by the plurality of multi-resonance antenna elements.

[0009] The multi-resonance antenna has a first antenna that operates in a first frequency band and a second antenna that operates in a second frequency band, and therefore operates in multiple frequency bands. In addition, the first antenna operates as a zero-order resonance antenna and is omnidirectional in the horizontal direction. By combining multiple multi-resonance antennas with this configuration and performing phase control on the signals transmitted and received by the multiple multi-resonance antennas, it is possible to operate with high gain in multiple frequency bands and obtain high gain in the horizontal direction in the first frequency band.

[0010] Note that the symbols in parentheses in the claims indicate a correspondence with the specific means described in the embodiments described below as one aspect, and do not limit the technical scope of the present disclosure. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a diagram illustrating a configuration of an antenna unit. [Figure 2] FIG. 2 is an external perspective view of the antenna device. [Figure 3] FIG. 2 is a top view of the antenna device. [Figure 4] FIG. 2 is a top view of the multi-resonance antenna alone. [Figure 5] FIG. 2 is a side view of the multi-resonance antenna alone. [Figure 6] FIG. 2 is a front view of the multi-resonance antenna alone. [Figure 7] FIG. 2 is a top view of the antenna device, in which the third antenna is omitted. [Figure 8] FIG. 2 is a side view of the antenna device. [Figure 9] 1A and 1B are diagrams illustrating the basic configuration of a metamaterial antenna. [Figure 10] FIG. 2 is a diagram illustrating the directivity of an antenna device. [Figure 11] FIG. 2 is a diagram illustrating the directivity of an antenna device. [Figure 12] FIG. 10 is a diagram illustrating the gain of the antenna device. [Figure 13] FIG. 10 is a diagram illustrating a modified example of the antenna device. [Figure 14] FIG. 10 is a diagram illustrating a modified example of the antenna device. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The present disclosure is not limited to the following embodiments, and various modifications described below are also included within the technical scope of the present disclosure. Furthermore, various modifications other than those described below can be implemented without departing from the gist of the present disclosure. Various supplements and modifications can be implemented in appropriate combinations as long as no technical contradictions arise. Components having the same function are given the same reference numerals, and their description may be omitted. Furthermore, when only a portion of a configuration is mentioned, the description given elsewhere can be applied to the other portions.

[0013] The antenna unit 1000 of the present disclosure shown in FIG. 1 is attached to a mobile object such as a vehicle and used. The antenna unit 1000 is connected to a communication ECU (Electronic Control Unit) mounted on the vehicle and used. The communication ECU 60 uses signals received by the antenna unit 1000 and inputs transmission signals to the antenna unit 1000. The antenna unit 1000 and the communication ECU 60 are connected by a coaxial cable, a feeder line, or the like. The antenna unit 1000 and the communication ECU may be connected by one or more AV lines. The antenna unit 1000 includes a transmission / reception unit 800 and an antenna device 100.

[0014] The transmitting / receiving unit 800 is a circuit module for performing signal processing on transmission signals and reception signals. The transmitting / receiving unit 800 includes a connector to which a cable is connected, an IC chip (Integrated Circuit), a memory, and the like. The transmitting / receiving unit 800 performs, for example, modulation, demodulation, frequency conversion, amplification, and the like. The transmitting / receiving unit 800 includes a phase control device 80. The phase control device 80 performs phase control on signals transmitted and received by the antenna device 100. The phase control device 80 includes a plurality of phase shifters 81 and a combiner 85.

[0015] 1 does not show modulation / demodulation circuits of the transmission / reception unit 800. An example of performing phase control on signals received by a plurality of multi-resonance antennas 40 will be described. As shown in FIG. 1, a plurality of phase shifters 81 are connected to the plurality of multi-resonance antennas 40 included in the antenna device 100, respectively. The plurality of phase shifters 81 adjust the phase amounts of radio waves received by the multi-resonance antennas 40. The phase amounts of the plurality of phase shifters 81 may be set by the communication ECU 60.

[0016] The combiner 85 combines the output signals of the phase shifters 81. The combiner 85 demodulates the combined signal and sends it to the communication ECU 60. The phase control device 80 controls the phase of each multi-resonant antenna body 40, thereby controlling the beam to be directed in a desired azimuth range.

[0017] Antenna device 100 is attached to the roof of a vehicle, the upper edge of the windshield, the dashboard, a pillar, a door panel, a bumper, etc. Antenna device 100 is configured to operate in three frequency bands, namely, a first frequency band, a second frequency band, and a third frequency band, which are spaced apart by 500 MHz or more.

[0018] The first frequency band, the second frequency band, and the third frequency band are all frequency bands used by Wi-Fi (registered trademark). The antenna device 100 is configured to support the 2.4 GHz band, the 5 GHz band, and the 920 MHz band of Wi-Fi.

[0019] The wavelength of the first frequency band is the wavelength of any frequency in the first frequency band. The wavelength of the second frequency band is the wavelength of any frequency in the second frequency band. The wavelength of the third frequency band is the wavelength of any frequency in the third frequency band. The wavelength in the description of the dimensions of the members constituting the antenna device 100 is the electrical length. The electrical length here is the effective length taking into consideration the wavelength shortening effect due to the fringing electric field or the dielectric.

[0020] The antenna device 100 may be used for only either transmission or reception. Because radio wave transmission and reception are reciprocal, a configuration capable of transmitting radio waves of a certain frequency is also a configuration capable of receiving radio waves of that frequency. In the following description, "transmission and reception" refers to at least one of transmission and reception.

[0021] The first frequency band includes 2.4 GHz. The first frequency band is configured to support the 2.4 GHz band from 2400 MHz to 2497 MHz. The first frequency band is a lower frequency band than the second frequency band.

[0022] The second frequency band includes 5 GHz. The second frequency band is configured to support the 5 GHz band from 5150 MHz to 5730 MHz. The second frequency band is a different frequency band from the first frequency band. The second frequency band has a larger bandwidth than the first frequency band. Specifically, the second frequency band has a bandwidth of 500 MHz or more.

[0023] The third frequency band is configured to support the 920 MHz band for Wi-Fi. In other words, the third frequency band refers to the 920 MHz band from 915 MHz to 928 MHz. In other words, the third frequency band includes 920 MHz. The third frequency band has a smaller bandwidth than the first and second frequency bands. The third frequency band is a lower frequency band than the first and second frequency bands.

[0024] The uses or specific values of the first, second, and third frequency bands may be changed as appropriate depending on the use. For example, the first, second, and third frequency bands may be frequency bands including 6 GHz. The first, second, and third frequency bands may be configured to support the 6 GHz band from 5925 MHz to 6425 MHz. The first, second, and third frequency bands may be frequency bands used for different types of communication. The first, second, and third frequency bands may correspond to frequency bands used by UWB (Ultra Wide Band), Bluetooth (registered trademark), GNSS (Global Navigation Satellite System), etc.

[0025] <Specific Configuration of Antenna Device 100> 2 or 3, antenna device 100 includes a plurality of multi-resonance antennas 40, a third antenna 30, and a ground plate 51. The plurality of multi-resonance antennas 40 are arranged at predetermined intervals on the upper surface of ground plate 51. Third antenna 30 is arranged at a predetermined interval from the plurality of multi-resonance antennas 40 on the upper surface of ground plate 51.

[0026] The ground plane 51 is a plate-shaped conductive member made of a conductor such as copper. Here, the plate-shaped member also includes a thin film such as a metal foil. The ground plane 51 is formed on the surface of a printed wiring board (not shown) that is formed in a flat shape by sandwiching a dielectric between metal conductive plates. The ground plane 51 may also be realized by using a conductor layer disposed inside a multilayer board that includes multiple conductor layers and insulating layers. The ground plane 51 is electrically connected to a grounding cable via, for example, a power supply circuit, and provides a ground potential (in other words, earth potential) for the antenna device 100.

[0027] The ground plate 51 has an upper surface and a lower surface. The lower surface is the surface opposite to the upper surface. The direction perpendicular to the ground plate 51 is the up-down direction for the antenna device 100. The up-down direction is the direction from the lower surface to the upper surface.

[0028] The ground plate 51 is formed in a square shape. The configuration of the antenna device 100 will be described below by introducing the concept of a right-handed three-dimensional coordinate system having an X-axis, a Y-axis, and a Z-axis that are orthogonal to each other. The X-axis shown in Figures 2, 3, 7, etc. is defined along one side of the ground plate 51. The Y-axis is defined along another side of the ground plate 51 that is orthogonal to the X-axis. The Z-axis is defined so as to be perpendicular to an imaginary plane that includes the X-axis and the Y-axis. The up-down direction of the antenna device 100 is defined along the Z-axis.

[0029] 2, ground plate 51 is large enough to contain multi-resonance antenna 40 and third antenna 30 when viewed from above. The length of one side of ground plate 51 is set to, for example, 90 mm or 100 mm. The length of one side of ground plate 51 may be designed based on the size of multi-resonance antenna 40 or third antenna 30.

[0030] The dimensions of the main plate 51 can be changed as appropriate. The shape of the main plate 51 as viewed from above can also be changed as appropriate. The main plate 51 may be circular or rectangular. The main plate 51 may be any other polygonal shape, such as a hexagon or octagon. The main plate 51 may be a line-symmetric shape, such as a square or a regular hexagon, or a shape with rotational symmetry, such as a parallelogram. The term "rectangular" includes rectangles and squares. The term "circular" can include not only perfect circles but also ellipses. The main plate 51 may be a non-line-symmetric shape, or may be any shape that does not have symmetry.

[0031] <Multiple-resonance antenna 40> 4, 5, and 6 are diagrams illustrating a portion of ground plate 51. The configuration of multi-resonance antenna 40 will be described by introducing the concept of a right-handed three-dimensional coordinate system having an X1 axis and a Y1 axis that are orthogonal to each other. The X1 axis and Y1 axis are different from the X axis and Y axis described above. The Z1 axis is the same as the Z axis described above. The X1 axis shown in FIGS. 4, 5, and 6 is defined along one side of multi-resonance antenna 40. The Y1 axis is defined along another side of multi-resonance antenna 40 that is orthogonal to the X1 axis. Multi-resonance antenna 40 includes first antenna 10, second antenna 20, and connecting conductor 13.

[0032] The first antenna 10 operates as a zero-order resonant antenna in the first frequency band. The first antenna 10 is a conductive structure for transmitting and receiving radio waves in the first frequency band. The first antenna 10 is adjacent to the second antenna 20 in the X1 positive direction. The first antenna 10 includes a first opposing portion 11, a short-circuit portion 14, and fixed conductors 15 and 16. The first opposing portion 11 is electrically connected to the ground plate 51 by the short-circuit portion 14 provided in the center. This structure corresponds to a mushroom structure, which is a basic structure of metamaterials. The first antenna 10 operates as a metamaterial antenna in cooperation with the ground plate 51 in the first frequency band. The first antenna 10 can also be called a resonant structure.

[0033] The first opposing portion 11 is a plate-shaped conductive member made of a conductive material such as copper. The first opposing portion 11 is disposed to face the ground plate 51 at a first distance D1. The first distance D1 is the distance between the first opposing portion 11 and the ground plate 51. The first distance D1 is set to 5 mm, for example. The first distance D1 may also be set to 3 mm, 4 mm, 6 mm, or the like. By being disposed to face the ground plate 51, the first opposing portion 11 forms a capacitance according to the area of the first opposing portion 11 and the distance between the first opposing portion 11 and the ground plate 51.

[0034] The first opposing portion 11 has a capacitance that resonates in parallel with the inductance of the short-circuit portion 14 in the second frequency band. The area of the first opposing portion 11 is designed to provide a desired capacitance. The desired capacitance is a capacitance that operates in the first frequency band in cooperation with the inductance of the short-circuit portion 14. If the operating frequency is f, the inductance of the short-circuit portion 14 is Ls, and the capacitance formed between the first opposing portion 11 and the ground plane 51 is C, then the relationship f≒1 / {2π√(Ls·C)} holds. The operating frequency f may be the center frequency of the first frequency band. A person skilled in the art would be able to determine an appropriate area of the first opposing portion 11 based on this relationship.

[0035] The first opposing portion 11 is formed in a rectangular shape. The length L1x of the first opposing portion 11 in the X1 direction is set to 14 mm, 18 mm, 22 mm, etc. The length L1y of the first opposing portion 11 in the Y1 direction is set to 15 mm, 19 mm, 23 mm, etc. The length of one side of the first opposing portion 11 can be changed as appropriate. The larger the first opposing portion 11, the larger the capacitance formed and the lower the operating frequency of the first antenna 10. The dimensions of the first opposing portion 11 are determined taking into account the value of the first frequency or the wavelength shortening effect of surrounding members, etc.

[0036] The first opposing portion 11 may have a line-symmetric shape such as a square or a regular hexagon, or may have a rotationally symmetric shape such as a parallelogram. The first opposing portion 11 is disposed at the same height (plane) as the second opposing portion 21 of the second antenna 20, which will be described later, with respect to the ground plane 51. The first opposing portion 11 is supported by the short-circuit portion 14.

[0037] The short-circuiting portion 14 is a conductive member that electrically connects the ground plate 51 and the first opposing portion 11. The short-circuiting portion 14 may be a conductive pin or a processed sheet metal member. The inductance of the short-circuiting portion 14 can be adjusted by adjusting the diameter or length of the short-circuiting portion 14. The length of the short-circuiting portion 14 is a first distance D1. The short-circuiting portion 14 is a polygonal prism having a cross section that is rectangular or hexagonal, for example. One end of the short-circuiting portion 14 is electrically connected to the ground plate 51, and the other end is electrically connected to the first opposing portion 11.

[0038] The short-circuit portion 14 is provided at the center of the opposing plate, which is the center of the first opposing portion 11. If the first opposing portion 11 is square or rectangular, the center of the first opposing portion 11 corresponds to the intersection of the diagonals. If the first opposing portion 11 is triangular, the inner center can be used as the center. The position where the short-circuit portion 14 is formed does not need to strictly coincide with the center of the opposing plate. The short-circuit portion 14 may be shifted by several mm from the center of the opposing plate.

[0039] The fixed conductors 15 and 16 are conductors that fix the first opposing portion 11. Providing the fixed conductors 15 and 16 can stabilize the structure of the first antenna 10. The fixed conductors 15 and 16 also function as elements for impedance matching. The fixed conductors 15 and 16 function as impedance elements that increase the inductance component.

[0040] One end of the fixed conductors 15 and 16 is connected to a corner of the first opposing portion 11. The fixed conductor 15 extends in the Z1 negative direction from a corner of the first opposing portion 11 facing in the Y1 positive direction and the X1 positive direction. The fixed conductor 16 extends in the Z1 negative direction from a corner of the first opposing portion 11 facing in the Y1 negative direction and the X1 positive direction. The fixed conductors 15 and 16 are fixed to the printed wiring board so as not to come into contact with the ground plate 51.

[0041] The facing distance D2 is the distance between the first facing portion 11 and the second facing portion 21. The facing distance D2 may be set to any value. For example, the facing distance D2 is set to 5.0 mm. The facing distance D2 may also be set to 3.0 mm, 7.0 mm, or the like.

[0042] The second antenna 20 is a monopole antenna. A monopole antenna is an antenna having a radiating element of 1 / 4 wavelength on a ground plane. The second antenna 20 operates as a zero-order resonant antenna in the second frequency band. The second antenna 20 is a conductive member for transmitting and receiving radio waves in the second frequency band. The second antenna 20 is configured as a three-dimensional plate-like monopole antenna having a length of 1 / 4 of the wavelength of the second frequency band. The second antenna 20 includes a second opposing portion 21, a fixed conductor 26, and an extension portion 22.

[0043] The second opposing portion 21 is a plate-like conductive member made of a conductor such as copper. The second opposing portion 21 is rectangular with its longitudinal direction in the Y1 direction. The second opposing portion 21 has a plurality of sides. The second opposing portion 21 has a power supply side edge 21s. Of the multiple sides of the second opposing portion 21, the power supply side edge 21s is the side closest to a power supply point 23, which will be described later. The power supply side edge 21s is connected to the extension portion 22.

[0044] The second opposing portion 21 is disposed to face the base plate 51 at a predetermined first distance D1. The distance between the second opposing portion 21 and the base plate 51 is set to be equal to the distance between the first opposing portion 11 and the base plate 51. The second opposing portion 21 is supported by the extension portion 22.

[0045] The fixed conductor 26 is a conductive member provided for matching frequency characteristics. The upper end of the fixed conductor 26 is connected to the second opposing portion 21. The fixed conductor 26 extends in the Z1 negative direction from a corner of the second opposing portion 21 that is in the Y1 positive direction and the X1 positive direction, and is grounded to the ground plate 51.

[0046] The fixed conductor 26 is configured to be narrower than the width in the X1 direction of the second opposing portion 21. The second antenna 20 functions as an inverted-F antenna by connecting the fixed conductors 26. An inverted-F antenna is an antenna that is made smaller and has a lower profile by bending a monopole antenna parallel to the ground plate 51.

[0047] The extension portion 22 is a conductive member that extends from the power supply side edge 21s of the second opposing portion 21 toward the ground plate 51. The extension portion 22 is plate-shaped. The height of the extension portion 22 when the ground plate 51 is used as the reference is approximately equal to the first distance D1. The extension portion 22 is oriented perpendicular to the ground plate 51. The upper end of the extension portion 22 is connected to the power supply side edge 21s of the second opposing portion 21. The extension portion 22 and the second opposing portion 21 may be perpendicular. A power supply point 23 is formed at the lower end of the extension portion 22.

[0048] The feed point 23 is a portion where the phase control device 80 and the second antenna 20 are electrically connected via a feed line. The feed point 23 is a portion where the phase shifter 81 and the second antenna 20 are electrically connected via a feed line. The feed point 23 is a connection point between the second antenna 20 and the feed line. The feed line is a microstrip line or a wiring pattern that electrically connects the phase control device 80 and the second antenna 20.

[0049] The extension portion 22 has an upper portion 221 and leg portions 222. The upper portion 221 is pentagonal in shape, with a rectangle connected to the top of a downward-facing isosceles triangle. The upper portion 221 is located above the leg portions 222, and the upper end of the upper portion 221 has a width equal to the length of the second opposing portion 21 in the Y1 direction, with the width narrowing toward the bottom of the upper portion 221. The leg portions 222 are rectangular in shape. The leg portions 222 are located below the upper portion 221, and are narrower in width than the upper portion 221. The width and height of the leg portions 222 may be set to any value, such as 2 mm or 3 mm.

[0050] The leg portion 222 is configured to suppress electromagnetic field coupling between the extension portion 22 and the ground plate 51. If the leg portion 222 were not provided, the extension portion 22 and the ground plate 51 would be closer to each other in larger areas, making it difficult for the antenna to function as a monopole antenna. The width and height of the leg portion 222 are designed so that the current supplied from the feed point 23 flows toward the second opposing portion 21. The length of the upper portion 221 in the height direction is adjusted so that the distance between the second opposing portion 21 and the ground plate 51 is a first distance D1.

[0051] The upper portion 221 and the second opposing portion 21 are plate-like members that are continuous with the leg portions 222. Here, plate-like means that it is not linear and has a width that is sufficiently larger than the leg portions 222, and refers to a shape that is, for example, three or five times or more wider than the leg portions 222. Specifically, a shape with a width of 5 mm or more or 10 mm or more corresponds to a plate-like member when viewed from the leg portions 222.

[0052] Leg 222 is electrically connected to the feed line at its lower end. Leg 222 forms feed point 23. Leg 222 has feed side surface 222a, which is the surface that forms feed point 23. Leg 222 has a plate shape and therefore has multiple plate surfaces, which correspond to feed side surface 222a.

[0053] The connecting conductor 13 connects and integrates the first antenna 10 and the second antenna 20. The connecting conductor 13 is disposed between the first opposing portion 11 of the first antenna 10 and the second opposing portion 21 of the second antenna 20, and electrically connects the first antenna 10 and the second antenna 20. The connecting conductor 13 is disposed between the first opposing portion 11 and the second opposing portion 21. The connecting conductor 13 is configured to be narrower in width in the X1 direction than the first opposing portion 11 and the second opposing portion 21.

[0054] <Arrangement of the multi-resonant antenna 40> As shown in FIG. 7 , the multiple multi-resonance antennas 40 include a plurality of antenna pairs 41. A pair of antenna pairs 41 refers to two of the multi-resonance antennas 40 that are arranged facing each other. The multi-resonance antennas 40 that form a pair of antenna pairs 41 are arranged so that their orientations are opposite to each other. The orientation of the multi-resonance antenna 40 refers to, for example, the direction in which any side or any face of the multi-resonance antenna 40 faces. The orientation of the multi-resonance antenna 40 refers to, for example, the direction in which the feed side surface 222a faces. As shown in FIG. 3 , the feed side edges 21s of the multi-resonance antennas 40 that form a pair of antenna pairs 41 are arranged so that they face in opposite directions.

[0055] As shown in Figures 3 and 7, the pair of antennas 41 are arranged so that their feed points 23 face each other, with the third antenna 30 (particularly the feed extension 33 described below) interposed therebetween. The pair of antennas 41 are arranged so that their feed side surfaces 222a, which form the feed points 23, face each other. The pair of antennas 41 have their extension portions 22 facing each other. The pair of antennas 41 have their feed side edges 21s facing each other. The pair of antennas 41 have their upper portions 221 facing each other. The pair of antennas 41 have their leg portions 222 facing each other. These arrangements can narrow the distance between the feed points 23 of the pair of antennas.

[0056] The pair of antennas 41 are arranged to face each other with an antenna distance D3 therebetween. The antenna distance D3 is the distance between the pair of antennas 41. The antenna distance D3 is the distance between the extension portions 22 of the pair of antennas 41. The reference point for measuring the antenna distance D3 may be any point. The antenna distance D3 may be the distance between the feed points 23 of the pair of antennas 41, or the distance between the feed sides 21s of the pair of antennas 41. The antenna distance D3 is set to be equal to or less than ¼ of the wavelength of the first frequency band. Specifically, the antenna distance D3 is set to be equal to or greater than 20 mm and equal to or less than 32 mm.

[0057] Antenna center 51c is the center point of antenna pair 41 and is located on the upper surface of ground plate 51. As shown in FIG. 7, antenna centers 51c, which are the centers of multiple antenna pairs 41, are aligned. Multi-resonance antennas 40 forming multiple antenna pairs 41 are arranged at equal intervals in circumferential direction Ci on the upper surface of ground plate 51, with antenna center 51c as the reference. Circumferential direction Ci is a clockwise direction on the upper surface of ground plate 51, with antenna center 51c as the reference. As shown in FIG. 7, when there are four multi-resonance antennas 40, adjacent multi-resonance antennas 40 are arranged at 90-degree intervals in circumferential direction Ci.

[0058] <Third antenna 30> As shown in Fig. 8, the antenna device 100 includes a third antenna 30 that operates in a third frequency band. The third antenna 30 is an inverted-F antenna. The third antenna 30 includes a main body 31, a short-circuiting extension 32, and a power supply extension 33. The main body 31 is a conductive plate. The main body 31 includes a first extension 31a, a bent portion 31b, and a second extension 31c.

[0059] The first extending portion 31a extends in the Y direction and is disposed so as to face the base plate 51. The length of the first extending portion 31a is set to 52 mm. The bent portion 31b bends from an end portion of the first extending portion 31a and extends in the negative Z direction. The length of the bent portion 31b is set to 10 mm. The second extending portion 31c bends from a lower end portion in the Z direction of the bent portion 31b and extends in the Y direction. The length of the second extending portion 31c is set to 22 mm. The second extending portion 31c is disposed so as to face the base plate 51 at a first distance D1.

[0060] In this way, since the main body 31 is bent into a U-shape, it is possible to shorten the length in the Y direction of the third antenna 30. The length in the Y direction of the first extension 31a is set so as not to protrude from the base plate 51.

[0061] The short-circuiting extension 32 is a conductive plate. One end of the short-circuiting extension 32 is connected to the first extension 31a, and the other end is electrically connected to the ground plate 51. The power supply extension 33 is a conductive plate. One end of the power supply extension 33 is connected to the first extension 31a, and the other end is electrically connected to a power supply line provided in the transceiver unit 800.

[0062] The short-circuiting extension 32 and the power supply extension 33 are formed by bending a strip-shaped / linear conductor that extends continuously from the first extension 31a. In other words, the main body 31, the short-circuiting extension 32, and the power supply extension 33 are produced by bending members cut out from a single metal plate.

[0063] The short-circuiting extension 32 and the power supply extension 33 are disposed in positions where the third antenna 30 operates as an inverted-F antenna. The short-circuiting extension 32 and the power supply extension 33 can be adjusted as appropriate in consideration of impedance matching, etc. The length of each part of the third antenna 30 is set so that the path length of the resonant current is an integral multiple of ¼ of the wavelength of the third frequency band.

[0064] As shown in Fig. 3, third antenna 30 is disposed between multiple multi-resonance antennas 40. The direction in which a set of multi-resonance antennas forming antenna pair 41 are arranged is defined as antenna arrangement direction W. Third antenna 30 is disposed to avoid outer region Eo that is outside antenna pair 41 in antenna arrangement direction W. The outside of antenna pair 41 refers to the region that is outside multi-resonance antennas 40 that form antenna pair 41 in antenna arrangement direction W, with antenna center 51c as the reference.

[0065] The short-circuiting extension 32 and the power supply extension 33 are arranged around the center of the ground plate 51. Here, the area around the center of the ground plate 51 refers to, for example, a range of 5 mm from the center of the ground plate 51. The power supply extension 33 is arranged around the antenna center 51c. The area around the antenna center 51c refers to, for example, a range of 5 mm from the antenna center 51c.

[0066] The short-circuiting extension 32 and the power supply extension 33 are arranged in an inner region Ei inside the antenna pair 41. The inside of the antenna pair 41 is the space sandwiched between the multi-resonant antenna bodies 40 that form the antenna pair 41. The inner region Ei includes the antenna center 51c. In top view, a portion of the main body 31 of the third antenna body 30 is arranged in the inner region Ei.

[0067] <Basic structure and operation of metamaterial antenna 200> Before describing the operation of antenna device 100, the basic configuration and operating principle of metamaterial antenna 200 will be described with reference to Fig. 9. Metamaterial antenna 200 includes a ground plane 51x, a facing portion 11x, and a short-circuit portion 14x.

[0068] The feed point 13x of the metamaterial antenna 200 is positioned at a position where impedance matching can be achieved in the facing portion 11x. Here, impedance matching refers to making the impedance value of the signal sending side and the impedance value of the signal receiving side approximately the same. If the impedances are not matched, a decrease in gain due to reflections and the like may occur, which may ultimately reduce the practicality of the antenna.

[0069] Metamaterial antenna 200 is an antenna that utilizes zero-order resonance, a phenomenon in which a metamaterial resonates at a frequency where the phase constant β is zero, among the dispersion characteristics of the metamaterial. Metamaterial antenna 200 is characterized by operating by LC parallel resonance between the capacitance formed between ground plate 51x and opposing portion 11x and the inductance of short-circuit portion 14x. The resonant frequency corresponds to the operating frequency of the antenna.

[0070] In metamaterial antenna 200, when power at the operating frequency is supplied from feed point 13x to facing portion 11x, parallel resonance occurs due to energy exchange between the inductor and capacitor, generating an electric field between ground plate 51x and facing portion 11x that is perpendicular to ground plate 51x. That is, an electric field is generated in the Z2 direction. This perpendicular electric field propagates from short-circuit portion 14x toward the edge of facing portion 11x. This perpendicular electric field becomes vertically polarized at the edge of facing portion 11x and is radiated into space. Note that, in this disclosure, vertical polarization refers to radio waves whose electric field vibration direction is perpendicular to ground plate 51x and facing portion 11x. Vertical polarization can also be called ground-vertically polarized wave or simply vertical polarization.

[0071] The propagation direction of the vertical electric field generated by the above-described LC parallel resonance (in other words, zero-order resonance) is symmetrical about the short-circuit portion 14x, and therefore has approximately the same gain in all directions in the antenna horizontal plane. In other words, one metamaterial antenna 200 has directivity in all directions (360°) from the center of the facing portion 11x toward its edge. In this disclosure, the antenna horizontal plane refers to a plane parallel to the ground plate 51x and the facing portion 11x. In this disclosure, the direction from the center of the facing portion 11x toward its edge is also referred to as the antenna horizontal direction. The antenna horizontal direction corresponds to the lateral direction (in other words, the side) of the antenna device 100.

[0072] Furthermore, the operation of the antenna when it transmits (radiates) radio waves and the operation when it receives radio waves are reversible. Although the above explanation has been given using the example of radiating radio waves, the above configuration allows the antenna to receive vertically polarized waves arriving from the horizontal direction.

[0073] The above-described ground plate 51x, opposing portion 11x, and short-circuit portion 14x correspond, in this order, to the ground plate 51, first opposing portion 11, and short-circuiting extension 32 of the multi-resonance antenna body 40. The feeding point 13x corresponds to the portion where the connecting conductor 13 and the first opposing portion 11 are connected. The explanation of the operation of the above-described basic configuration may be used as an explanation of the first antenna 10.

[0074] In addition to metamaterial antenna 200, there is also a patch antenna, which uses a metal plate facing a ground plane. A patch antenna utilizes a resonance phenomenon that occurs when the path length of a current is λ / 2, and its operating principle is different from that of metamaterial antenna 200. Furthermore, while a patch antenna requires the radiating element to have a dimension that is λ / 2, metamaterial antenna 200 does not require the facing portion 11x to have a length of λ / 2. Furthermore, metamaterial antennas are also different from patch antennas in terms of directivity. That is, patch antennas and planar inverted-F antennas form beams perpendicular to the ground plane (i.e., upward), whereas metamaterial antennas generally form beams horizontally rather than upward. Furthermore, patch antennas do not require a short-circuiting element, whereas metamaterial antennas require a short-circuiting element. Thus, metamaterial antenna 200 is different from patch antennas in terms of its operating principle, directivity, configuration, and so on.

[0075] <Operation of the Antenna Device 100> The operation of the antenna device 100 will now be described. Figures 10 and 11 show the gain when directivity control is performed in the first frequency band in the antenna unit 1000. That is, the phase control device 80 controls the phase of each multi-resonant antenna element 40 of the antenna device 100, and controls the directivity to a predetermined direction. The phase control is performed using a beam former method or the like.

[0076] The dotted lines in Figures 10 and 11 show the gain when the directivity is controlled to be directed at a predetermined angle. The solid lines show the results of taking the maximum gain in each direction when the directivity is directed around the entire circumference of the antenna device 100. As shown in Figures 10 and 11, it can be seen that high gain can be obtained around the entire circumference of the antenna device 100. It can also be seen that nearly omnidirectional gain can be obtained in the horizontal direction.

[0077] In the antenna unit 1000, even when directivity control is performed in the second frequency band, it is expected that gain close to omnidirectional in the horizontal direction can be obtained, as in FIGS.

[0078] Fig. 12 is a graph of the gain when the antenna spacing D3 of the antenna pair 41 is changed and the antenna is operated in the first frequency band. As shown in Fig. 11, it can be seen that the gain peaks at 1 / 4 wavelength of the first frequency band.

[0079] <Summary of the embodiment> The gain obtained when performing phase control on multiple multi-resonant antennas 40 depends on the antenna spacing D3. The gain is maximized when the antenna spacing is ¼ of the wavelength. In the present disclosure, a pair of antennas are arranged facing each other with an antenna spacing of ¼ or less of the wavelength of the first frequency band. This allows for high gain in the first frequency band.

[0080] In an antenna, the closer to feed point 23, the smaller the electric field radiation. In the present disclosure, multi-resonant antennas 40 forming antenna pair 41 are arranged so that feed sides 222a forming the feed point face each other. This results in the arrangement of multi-resonant antennas 40 forming antenna pair 41 such that portions of multi-resonant antennas 40 with small electric field radiation face each other. This makes it possible to suppress the influence of one of the two multi-resonant antennas forming antenna pair 41 on the other.

[0081] In the present disclosure, the centers of the multiple antenna pairs 41 are aligned. The multiple resonant antennas 40 forming the multiple antenna pairs 41 are arranged at equal intervals in the circumferential direction Ci with respect to the antenna center 51c. With this arrangement of the multiple resonant antennas 40, when phase control is performed on the multiple resonant antennas 40, it is possible to obtain directivity that is close to a circular shape (in other words, omnidirectional) in the horizontal direction at the first frequency.

[0082] A monopole antenna is omnidirectional in the horizontal direction, so by using antenna device 100 of the present disclosure to perform phase control on multiple multi-resonant antenna elements 40, it is possible to obtain high gain in the horizontal direction even in the second frequency band.

[0083] The antenna device 100 of the present disclosure further includes a third antenna 30 that operates in a third frequency band that is lower than the first and second frequency bands, thereby enabling the antenna device 100 to operate in the third frequency band as well.

[0084] In the present disclosure, the third antenna 30 is arranged to avoid the outer region Eo in the antenna arrangement direction W. Consider a case where the third antenna 30 is arranged outside the antenna pair 41 in the antenna arrangement direction W. Here, consider a case where phase control is performed on multiple multi-resonance antennas 40 to direct directivity in the antenna arrangement direction W. In this case, the third antenna 30 exists in the direction of directivity, and there is a possibility that the third antenna 30 will get in the way. Therefore, in the present disclosure, the third antenna 30 is arranged to avoid the outer region Eo in the antenna arrangement direction W. As a result, the third antenna 30 is not arranged outside the antenna pair 41 in the antenna arrangement direction W. This makes it possible to suppress the effect of the third antenna 30 on the gain of the multi-resonance antenna 40 in the antenna arrangement direction W.

[0085] The third antenna 30 is an inverted-F antenna. Since an inverted-F antenna has a low profile, the antenna device 100 can be made smaller.

[0086] As described above, the gain of antenna device 100 is maximized when antenna spacing D3 is ¼ of the wavelength. In the present disclosure, antenna spacing D3 is set to 20 mm or more and 32 mm or less so that it is ¼ of the wavelength of the first frequency band or less. As a result, when the first frequency band of antenna device 100 of the present disclosure is used at 2.4 GHz, the difference in gain of antenna device 100 can be kept within 1 dB compared to the gain when antenna spacing D3 is ¼ of the wavelength of the first frequency.

[0087] In the present disclosure, the first frequency band includes 2.4 GHz and the second frequency band includes 5 GHz, which allows the antenna device 100 to be used in the Wi-Fi frequency bands (2.4 GHz, 5 GHz).

[0088] <Modification> In the above-described embodiment, the antenna device 100 is configured to include the third antenna 30, but this is not necessarily limited to this. For example, as shown in Fig. 13, the antenna device 100 may be configured without including the third antenna 30.

[0089] In the above-described embodiment, the antenna device 100 is configured to include four multi-resonance antenna elements 40, but this is not necessarily limited to this. The antenna device 100 may include any number of multi-resonance antenna elements 40. For example, as shown in FIG. 13 , the antenna device 100 may be configured to include six multi-resonance antenna elements 40.

[0090] In the above-described embodiment, the antenna device 100 has two antenna pairs 41, but this is not necessarily limited to this. The number of antenna pairs 41 included in the antenna device 100 may be any number. For example, as shown in FIG. 13 , the antenna device 100 may have three antenna pairs 41.

[0091] In the above embodiment, the antenna spacing D3 is equal to or less than ¼ of the wavelength of the first frequency band, but this is not necessarily limited to this. For example, the antenna spacing D3 may be equal to or greater than ¼ of the wavelength of the first frequency band.

[0092] In the above embodiment, the multi-resonant antennas 40 forming the antenna pair 41 are configured so that the feed sides 222a face each other, but this is not necessarily limited to this. For example, the multi-resonant antennas 40 forming the antenna pair 41 may be configured so that the feed sides 222a do not face each other.

[0093] In the above embodiment, the multi-resonance antenna 40 forming the plurality of antenna pairs 41 is arranged at equal intervals in the circumferential direction Ci with respect to the antenna center 51c, but this is not necessarily limited to this. For example, the multi-resonance antenna 40 forming the plurality of antenna pairs 41 may be arranged not at equal intervals in the circumferential direction Ci with respect to the antenna center 51c.

[0094] In the above embodiment, the antenna centers 51c of the plurality of antenna pairs 41 are aligned, but this is not necessarily limited to this. For example, the centers of the plurality of antenna pairs 41 may not be aligned.

[0095] In the above embodiment, the second antenna 20 is a monopole antenna, but this is not necessarily limited to this. For example, the second antenna 20 may be an antenna other than a monopole antenna.

[0096] In the above embodiment, the third antenna 30 is configured to operate in a third frequency band that is lower than the first and second frequency bands, but this is not necessarily limited to this. For example, the third antenna 30 may be configured to operate in a third frequency band that is higher than the first and second frequency bands.

[0097] In the above embodiment, the third antenna 30 is arranged to avoid the outer area Eo that is outside the antenna pair 41 in the antenna arrangement direction W, but this is not necessarily limited to this. For example, the third antenna 30 may be arranged in the outer area Eo that is outside the antenna pair 41 in the antenna arrangement direction W.

[0098] In the above embodiment, the third antenna 30 is configured as an inverted-F antenna, but this is not necessarily limited to this. For example, the third antenna 30 may be configured as a loop antenna. A loop antenna is an antenna in which the conductor portion serving as the antenna element is formed into a ring-shaped (loop) coil.

[0099] In the above-described embodiment, the antenna spacing D3 is set to 20 mm or more and 32 mm or less, but this is not necessarily limited to this. For example, the antenna spacing D3 may be set to 20 mm or less or 32 mm or more.

[0100] In the above-described embodiment, the first antenna 10 is configured to include the fixed conductors 16 and 17, but this is not necessarily limited to this. For example, the first antenna 10 may be configured without the fixed conductors 16 and 17.

[0101] In the above-described embodiment, the first antenna 10 is configured to include the connecting conductor 13, but this is not necessarily limited to this. For example, the first antenna 10 may be configured without the connecting conductor 13. In this case, the facing distance D2 is set so that the first antenna 10 operates using power supplied from the second antenna 20 in the first frequency band.

[0102] In the above-described embodiment, the short-circuiting extension 32 and the power supply extension 33 are arranged in the inner area Ei inside the antenna pair 41, but this is not necessarily limited to this. For example, the antenna device 100 may be configured as shown in Fig. 14. The first extension 31a, the bent portion 31b, and the second extension 31c may be arranged in the inner area Ei inside the antenna pair 41.

[0103] In the above-described embodiment, the multi-resonance antenna 40 includes the first antenna 10 that operates as a zero-order resonant antenna in a first frequency band (e.g., 2.4 GHz band) and the second antenna 20 that operates as a monopole antenna in a second frequency band (e.g., 5 GHz band), but this is not necessarily limited to this. For example, the multi-resonance antenna 40 may further include a fourth antenna that operates as a zero-order resonant antenna in a frequency band different from the first and second frequency bands. The fourth antenna may operate as a zero-order resonant antenna in a frequency band including 6 GHz, for example. The frequency band including 6 GHz is configured to support the 6 GHz band from 5925 MHz to 6425 MHz. [Explanation of symbols]

[0104] 100 Antenna device, 80 Phase control device, 10 First antenna, 20 Second antenna, 222a Feeding side, 23 Feeding point, 30 Third antenna body, 40 Multi-resonant antenna body, 41 Antenna pair, 51c Antenna center, Ci Circumferential direction, D3 Antenna spacing, Eo Outer region, W Antenna arrangement direction.

Claims

1. An antenna device comprising a plurality of multi-resonant antenna bodies (40) each having a first antenna (10) that operates as a zero-order resonant antenna in a first frequency band and a second antenna (20) that operates in a second frequency band different from the first frequency band.

2. The plurality of multi-resonance antennas include a pair of antennas (41) facing each other with an antenna interval (D3) therebetween, The antenna device according to claim 1 , wherein the antenna spacing is equal to or less than ¼ of a wavelength of the first frequency band.

3. The multi-resonant antenna has a feed point (23), 3. The antenna device according to claim 2, wherein the multi-resonant antenna elements forming the antenna pair are arranged such that the feed sides (222a) forming the feed points face each other.

4. the plurality of multi-resonant antenna elements include a plurality of the antenna pairs; The antenna centers (51c) of the plurality of antenna pairs coincide with each other, 3. The antenna device according to claim 2, wherein the multi-resonant antenna elements forming the plurality of antenna pairs are arranged at equal intervals in a circumferential direction (Ci) with the antenna center as a reference.

5. The antenna device according to claim 1 , wherein the second antenna is a monopole antenna.

6. 2. The antenna device of claim 1, further comprising a third antenna element (30) operating in a third frequency band lower than the first and second frequency bands.

7. The plurality of multi-resonance antennas include a pair of antennas (41) facing each other with an antenna interval (D3) therebetween, a third antenna (30) that operates in a third frequency band that is lower than the first frequency band and the second frequency band; 2. The antenna device according to claim 1, wherein the direction in which a set of the multi-resonant antenna bodies forming the antenna pair are arranged is defined as an antenna arrangement direction (W), and the third antenna body is arranged to avoid an outer region (Eo) that is outside the antenna pair in the antenna arrangement direction.

8. 8. The antenna device according to claim 6, wherein the third antenna is an inverted-F antenna.

9. The plurality of multi-resonance antennas include a pair of antennas (41) facing each other with an antenna interval (D3) therebetween, 2. The antenna device according to claim 1, wherein the antenna spacing is equal to or greater than 20 mm and equal to or less than 32 mm.

10. the first frequency band includes 2.4 GHz; The antenna device according to claim 1 , wherein the second frequency band includes 5 GHz.

11. an antenna device (100) including a plurality of multi-resonant antenna bodies (40) each having a first antenna (10) operating as a zero-order resonant antenna in a first frequency band and a second antenna (20) operating in a second frequency band different from the first frequency band; and a phase control device (80) that performs phase control on signals transmitted and received by the plurality of multi-resonance antenna elements.

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