Antenna, wireless communication device, and structure

Abstract

This antenna comprises: a first conductor that extends across a first surface; a second conductor that extends across the first surface and serves as a potential reference of the first conductor, the second conductor being separated from the first conductor in a first direction and electrically connected to the first conductor; a housing that houses the first conductor and the second conductor, and has a surface facing the second conductor and being a conductive body having electrical conductivity; and an attachment part that is provided between the second conductor and the conductive body inside the housing, and fixes the second conductor to the conductive body while electrically insulating the second conductor and the conductive body. The attachment part is smaller than the second conductor and is not in contact with an end portion of the second conductor in a plan view.

Description

Antennas, wireless communication devices and structures

[0001] The present disclosure relates to antennas, wireless communication devices and structures.

[0002] In recent years, an antenna that is capable of good communication even when placed on a metal plate has become known (see, for example, Patent Document 1).

[0003] International Publication No. 2018 / 174026

[0004] The antenna of the present disclosure comprises a first conductor extending on a first surface, a second conductor positioned away from the first conductor in a first direction, electrically connected to the first conductor, and extending on the first surface as a potential reference for the first conductor, a housing that houses the first conductor and the second conductor and whose surface facing the second conductor is an electrically conductive conductor, and a mounting portion provided inside the housing between the second conductor and the conductor, electrically insulating the second conductor from the conductor and fixing the second conductor to the conductor, wherein the mounting portion is smaller than the second conductor in a planar view and does not contact an end of the second conductor.

[0005] A wireless communication device according to the present disclosure includes the antenna according to the present disclosure and a communication unit that performs wireless communication with an external device via the antenna.

[0006] The structure of the present disclosure comprises the wireless communication device of the present disclosure.

[0007] FIG. 1 is an external view of the top surface of an antenna according to an embodiment. FIG. 2 is an external view of the bottom surface of the antenna according to an embodiment. FIG. 3 is a diagram for explaining a first installation method of the antenna according to an embodiment. FIG. 4 is a diagram for explaining a second installation method of the antenna according to an embodiment. FIG. 5 is a cross-sectional view of the antenna according to an embodiment. FIG. 6 is an exploded view of the antenna according to an embodiment. FIG. 7 is a diagram showing an example configuration of a second substrate and a second conductor according to an embodiment. FIG. 8 is a diagram for explaining communication characteristics of an antenna according to a comparative example. FIG. 9 is a diagram for explaining a first example configuration of a mounting portion according to an embodiment. FIG. 10 is a diagram for explaining the relationship between the size of the mounting portion according to an embodiment and the radiation efficiency of the antenna. FIG. 11 is a diagram for explaining a second example configuration of a mounting portion according to an embodiment. FIG. 12 is a diagram for explaining the relationship between the size of the mounting portion according to an embodiment and the radiation efficiency of the antenna. FIG. 13 is a diagram for explaining a third example configuration of a mounting portion according to an embodiment. FIG. 14 is a diagram for explaining the relationship between the size of the mounting portion according to an embodiment and the radiation efficiency of the antenna. FIG. 15 is a diagram for explaining a first example installation position of a mounting portion according to an embodiment. FIG. 16 is a diagram for explaining the radiation efficiency of the antenna in a first example of an installation position of the attachment unit according to the embodiment. FIG. 17 is a diagram for explaining the relationship between the installation position of the attachment unit according to the embodiment and the radiation efficiency of the antenna. FIG. 18 is a diagram for explaining a second example of an installation position of the attachment unit according to the embodiment. FIG. 19 is a diagram for explaining the radiation efficiency of the antenna in the second example of an installation position of the attachment unit according to the embodiment. FIG. 20 is a diagram for explaining the relationship between the installation position of the attachment unit according to the embodiment and the radiation efficiency of the antenna. FIG. 21 is a diagram for explaining a third example of an installation position of the attachment unit according to the embodiment. FIG. 22 is a diagram for explaining the radiation efficiency of the antenna in the third example of an installation position of the attachment unit according to the embodiment. FIG. 23 is a block diagram showing an example configuration of a wireless communication device according to the embodiment.

[0008] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Note that the present invention is not limited to this embodiment, and in the following embodiments, the same components are designated by the same reference numerals, and redundant explanations will be omitted.

[0009] In the following description, an XYZ Cartesian coordinate system is set, and the positional relationship of each part will be described with reference to this XYZ Cartesian coordinate system. The direction parallel to the X axis in a horizontal plane is defined as the X-axis direction, the direction parallel to the Y axis in the horizontal plane perpendicular to the X axis is defined as the Y-axis direction, and the direction parallel to the Z axis perpendicular to the horizontal plane is defined as the Z-axis direction. Furthermore, the plane including the X axis and Y axis will be referred to as the XY plane as appropriate, the plane including the X axis and Z axis will be referred to as the XZ plane as appropriate, and the plane including the Y axis and Z axis will be referred to as the YZ plane as appropriate. The XY plane is parallel to the horizontal plane. The XY plane, XZ plane, and YZ plane are perpendicular to each other.

[0010] [Embodiment] [Antenna] The appearance of an antenna according to an embodiment will be described with reference to Fig. 1 and Fig. 2. Fig. 1 is an appearance view of the top surface of the antenna according to the embodiment. Fig. 2 is an appearance view of the bottom surface of the antenna according to the embodiment.

[0011] As shown in Fig. 1, the top and sides of the antenna 1 are covered with a resin housing 11. As shown in Fig. 2, the bottom of the antenna 1 is formed of a metal conductor 12. That is, the antenna 1 has a structure covered with a case including the resin housing 11 and the conductor 12. The antenna 1 has a cable 20 for connecting to a communication device (not shown). The antenna 1 has a thin structure with a length of about 112 mm in the long side direction, a length of about 64 mm in the short side direction, and a height of about 13 mm.

[0012] An installation method of an antenna according to an embodiment will be described with reference to Fig. 3 and Fig. 4. Fig. 3 is a diagram for explaining a first installation method of an antenna according to an embodiment. Fig. 4 is a diagram for explaining a second installation method of an antenna according to an embodiment.

[0013] 3, the antenna 1 is installed on the top surface of a metal box 2, for example. The antenna 1 may also be installed on the side surface of the box 2, for example. The antenna 1 is fastened to the box 2 with screws, for example.

[0014] As shown in Figure 4, the antenna 1 may be housed, for example, inside a box 2. For example, a housing section 4 may be formed on the side of the box 2, the antenna 1 may be housed in the housing section 4, and the housing section 4 may be covered with a resin plate 3. The resin plate 3 may be either light-transmitting or non-light-transmitting. Specifically, the resin plate 3 may be made of a material that is capable of transmitting electromagnetic waves. The resin plate 3 may be made of, for example, acrylic resin, polycarbonate resin, or the like. In this embodiment, the antenna 1 has a thin structure, so the depth of the housing section 4 may be approximately 15 mm.

[0015] [Configuration of Antenna] A configuration example of the antenna according to the embodiment will be described with reference to Fig. 5 and Fig. 6. Fig. 5 is a cross-sectional view of the antenna according to the embodiment. Fig. 6 is an exploded view of the antenna according to the embodiment.

[0016] As shown in Figures 5 and 6, the antenna 1 has a housing 11, a conductor 12, a first substrate 13, a second substrate 14, a first conductor 15, a second conductor 16, and an attachment portion 17.

[0017] The antenna 1 is configured to be capable of radiating circularly polarized waves. The antenna 1 is configured to exhibit an artificial magnetic conductor character (ARTC) for electromagnetic waves of a predetermined frequency incident on the XY plane of the antenna 1 from the positive side of the Z axis. In this disclosure, the artificial magnetic conductor character refers to the character of a surface where the phase difference between the incident wave and the reflected wave is 0 degrees. On a surface having the artificial magnetic conductor character, the phase difference between the incident wave and the reflected wave is -90 degrees to +90 degrees in the operating frequency band.

[0018] The housing 11 covers the top and side surfaces of the first substrate 13, the second substrate 14, the first conductor 15, the second conductor 16, and the mounting portion 17. The housing 11 has a plurality of support portions 11a. The support portions 11a maintain the length of the antenna 1 in the height direction and improve the strength of the antenna 1.

[0019] The conductor 12 is located on the bottom surface of the antenna 1. The conductor 12 has electrical conductivity. The conductor 12 is formed of, for example, a metal material. The housing 11 and the conductor 12 accommodate the first substrate 13, the second substrate 14, the first conductor 15, the second conductor 16, and the mounting portion 17.

[0020] The first substrate 13 extends in the XY plane. The XY plane is also referred to as the first surface. The first substrate 13 is, for example, a dielectric substrate. The first substrate 13 is formed, for example, in a rectangular shape, but is not limited to this. The first substrate 13 may be a one-layer substrate (single-sided substrate) or a two-layer substrate (double-sided substrate).

[0021] The second substrate 14 extends in the XY plane. The second substrate 14 is located away from the first substrate 13 in the Z-axis direction. The Z-axis direction is also referred to as the first direction. The second substrate 14 is, for example, a dielectric substrate. The second substrate 14 is formed, for example, in a rectangular shape, but is not limited to this. The second substrate 14 may be a one-layer substrate (single-sided substrate) or a two-layer substrate (double-sided substrate).

[0022] The first conductor 15 is provided on the first substrate 13. The first conductor 15 is made of, for example, a metal material. The first conductor 15 extends in the XY plane. The first conductor 15 is formed, for example, in a rectangular shape, but is not limited to this. The first conductor 15 is formed to function as a resonator.

[0023] The second conductor 16 is provided on the second substrate 14. The second conductor 16 is formed of, for example, a metal material. The second conductor 16 extends in the XY plane. The second conductor 16 is formed, for example, in a rectangular shape, but is not limited to this. The second conductor 16 is formed to function as a ground. The second substrate 14 and the second conductor 16 may be formed from a single metal plate.

[0024] The first conductor 15 and the second conductor 16 are electromagnetically connected by a plurality of connection parts 30. One end of each connection part 30 is electromagnetically connected to the first conductor 15, and the other end is electromagnetically connected to the second conductor 16. The connection part 30 is, for example, a conductor formed in a columnar shape, but is not limited to this.

[0025] 7 is a diagram showing an example of the configuration of the second substrate and the second conductor according to the embodiment. As shown in FIG. 7, the second substrate 14 and the second conductor 16 have a plurality of through holes 40. Conductors are formed on the inner walls of the through holes 40. In the example shown in FIG. 7, the second substrate 14 is, for example, a two-layer substrate, and the second conductors 16 are formed on both sides of the second substrate 14. The second conductors 16 formed on both sides are electromagnetically connected via the through holes. Here, the distance D between adjacent through holes 40 along the X-axis direction is set to λ 1 / λ 2 / λ 3 / λ 4 / λ 5 / λ 6 / λ 7 / λ 8 / λ 9 / λ 10 / λ 11 / λ 12 / λ 13 / λ 14 / λ 15 / λ 16 / λ 25 / λ 26 / λ 27 / λ 28 / λ 29 / λ 30 / λ 31 / λ 32 / λ 33 / λ 34 / λ 35 / λ 36 / λ 37 / λ 38 / λ 39 / λ 40 / λ 41 / λ 42 / λ 43 / λ 44 / λ 45 / λ 46 / λ 47 / λ 48 / λ 49 / λ 50 / λ 51 / λ 52 / λ 53 / λ 54 / λ 55 / λ 56 / λ 57 / λ 58 / λ 59 ... Ｍａｘ Then, λ Ｍａｘ It is preferable that the ratio is 1 / 4 or less.

[0026] The mounting portion 17 is provided between the conductor 12 and the second conductor 16. The mounting portion 17 is formed, for example, from a resin material. The mounting portion 17 electrically insulates the conductor 12 from the second conductor 16. The mounting portion 17 is, for example, a rectangular resin sheet, but is not limited thereto. The mounting portion 17 is attached to the conductor 12 and the second conductor 16 with, for example, an insulating adhesive or insulating double-sided tape. That is, the mounting portion 17 fixes the conductor 12 to the second conductor 16. The mounting portion 17 may also be provided between the housing 11 and the first conductor 15. The mounting portion 17 may also be provided both between the housing 11 and the first conductor 15 and between the conductor 12 and the second conductor 16.

[0027] Here, if the mounting portion 17 is made of a conductive material, the antenna 1 has good high-frequency characteristics but has problems with stability of characteristics, reliability, and cost. Therefore, in this embodiment, the mounting portion 17 is made of a resin material, which has fewer problems with stability of characteristics, reliability, and cost, but in this case, the communication characteristics of the antenna 1 may deteriorate.

[0028] FIG. 8 is a diagram illustrating the communication characteristics of an antenna according to a comparative example. FIG. 8 shows simulation results assuming that antenna 1 communicates in two bands, the 900 MHz (megahertz) band and the 2 GHz band. In FIG. 8, the horizontal axis represents frequency (GHz (gigahertz)) and the vertical axis represents radiation efficiency (dB (decibels)). Waveform 101 represents the radiation characteristics of antenna 1 when mounting portion 17 is formed of a conductive material. Waveform 102 represents the radiation characteristics of antenna 1 when mounting portion 17 is formed of a resin material and the size of mounting portion 17 is the same as that of second conductor 16. Comparing waveforms 101 and 102, when mounting portion 17 is formed of a resin material, the radiation characteristics of antenna 1 deteriorate in the low-frequency band of 900 MHz and the high-frequency band of 2 GHz. Antenna 1 exhibits particularly large degradation in the radiation characteristics in the high-frequency band.

[0029] Therefore, in the present disclosure, the antenna 1 is configured such that the attachment portion 17 is formed from a resin material and the communication characteristics are improved.

[0030] [Configuration of Mounting Portion] The mounting portion 17 is formed to be smaller than the second conductor 16 in order to improve the communication characteristics of the antenna 1. In order to improve the communication characteristics of the antenna 1, the mounting portion 17 is provided so that at least a portion of its end does not come into contact with an end of the second conductor 16 when viewed in a plan view on the XY plane.

[0031] (First Configuration Example) A first configuration example of the mounting portion according to the embodiment will be described with reference to Fig. 9. Fig. 9 is a diagram for explaining the first configuration example of the mounting portion according to the embodiment.

[0032] As shown in FIG. 9 , the mounting portion 17A is smaller than the second conductor 16 in plan view in the XY plane. The second conductor 16 has, for example, a long side 16a that is 80 mm long and a short side 16b that is 50 mm long. The mounting portion 17A has a long side 17Aa that is 60 mm long and a short side 17Ab that is 50 mm long. That is, the long side 17Aa of the mounting portion 17A is shorter than the long side 16a of the second conductor 16, and the short side 17Ab is the same length as the short side 16b of the second conductor 16. The short side 17Ab of the mounting portion 17A does not contact the short side 16b of the second conductor 16 in plan view in the XY plane.

[0033] FIG. 10 is a diagram illustrating the relationship between the size of the mounting portion according to the embodiment and the radiation efficiency of the antenna. In FIG. 10, the horizontal axis represents the length of the long side of the mounting portion 17A relative to the wavelength, and the vertical axis represents the radiation efficiency [dB]. The radiation efficiency shown in FIG. 10 represents the worst value of the radiation efficiency in the band from 1.71 [GHz] to 2.17 [GHz]. 0 / 4 on the horizontal axis represents the result of a simulation in which the mounting portion 17A is absent and there is air (relative dielectric constant 1.0) between the conductor 12 and the second conductor 16. The length of the long side of the mounting portion 17A is expressed as a multiple of the wavelength of the radio wave. As shown in FIG. 10, the radiation efficiency of the antenna 1 significantly decreases when the length of the long side 17Aa of the mounting portion 17A exceeds λ, where λ is the intra-dielectric wavelength of the radio wave within the mounting portion 17A. The radiation efficiency of the antenna 1 improves when the length of the long side 17Aa of the mounting portion 17A is λ or less. That is, in this embodiment, the communication characteristics of the antenna 1 can be improved by setting the length of the long side 17Aa of the attachment portion 17A to λ or less.

[0034] (Second Configuration Example) A second configuration example of the mounting portion according to the embodiment will be described with reference to FIG. 11. FIG. 11 is a diagram for explaining the second configuration example of the mounting portion according to the embodiment.

[0035] 11 , the mounting portion 17B is smaller than the second conductor 16 in plan view in the XY plane. The mounting portion 17B has a long side 17Ba that is 80 mm long and a short side 17Bb that is 30 mm long. That is, the length of the long side 17Ba of the mounting portion 17B is the same as the long side 16a of the second conductor 16, and the length of the short side 17Bb is shorter than the short side 16b of the second conductor 16. The long side 17Ba of the mounting portion 17B does not contact the long side 16a of the second conductor 16 in plan view in the XY plane.

[0036] FIG. 12 is a diagram illustrating the relationship between the size of the mounting portion according to the embodiment and the radiation efficiency of the antenna. In FIG. 12, the horizontal axis represents the length of the short side of the mounting portion 17B relative to the wavelength, and the vertical axis represents the radiation efficiency [dB]. The radiation efficiency shown in FIG. 12 represents the worst value of the radiation efficiency in the band from 1.71 GHz to 2.17 GHz. The length of the short side of the mounting portion 17B is expressed as a multiple of the wavelength of the radio wave. As shown in FIG. 12, the radiation efficiency of the antenna 1 significantly decreases when the length of the short side 17Bb of the mounting portion 17B exceeds λ / 2. The radiation efficiency of the antenna 1 improves when the length of the short side 17Bb of the mounting portion 17B is λ / 2 or less. That is, in this embodiment, the communication characteristics of the antenna 1 can be improved by setting the length of the short side 17Bb of the mounting portion 17B to λ / 2 or less.

[0037] (Third Configuration Example) A third configuration example of the mounting portion according to the embodiment will be described with reference to FIG. 13. FIG. 13 is a diagram for explaining the third configuration example of the mounting portion according to the embodiment.

[0038] 13 , the mounting portion 17C is smaller than the second conductor 16 in plan view in the XY plane. The mounting portion 17C has a long side 17Ca that is 60 mm long and a short side 17Cb that is 30 mm long. That is, the long side 17Ca of the mounting portion 17C is shorter than the long side 16a of the second conductor 16, and the short side 17Cb of the mounting portion 17C is shorter than the short side 16b of the second conductor 16. In plan view in the XY plane, the long side 17Ca and the short side 17Cb of the mounting portion 17C do not contact the long side 16a and the short side 16b of the second conductor 16, respectively.

[0039] FIG. 14 is a diagram illustrating the relationship between the size of the mounting portion according to the embodiment and the radiation efficiency of the antenna. In FIG. 14, the horizontal axis represents frequency (GHz) and the vertical axis represents radiation efficiency (dB). Waveform 111 represents the radiation efficiency of a comparative example antenna 1 in which the mounting portion 17 and the second conductor 16 are the same size. Waveform 112 represents the radiation efficiency of the antenna 1 when the mounting portion 17 is the mounting portion 17A shown in FIG. 9 . Waveform 113 represents the radiation efficiency of the antenna 1 when the mounting portion 17 is the mounting portion 17C shown in FIG. 13 . Waveform 114 represents the radiation efficiency of the antenna 1 when the mounting portion 17 is the mounting portion 17B shown in FIG. 11 . As shown by waveforms 112 to 114, by using mounting portion 17A, 17B, or 17C as the mounting portion, the antenna 1 can suppress degradation of communication characteristics in the 2 GHz band. Note that, from the standpoint of bonding strength with the conductor 12, it is preferable to use mounting portion 17A.

[0040] [Position of Mounting Portion] Next, a description will be given of the position in the XY plane of the mounting portion 17. For example, depending on the positional relationship between the mounting portion 17C and the second conductor 16 in plan view in the XY plane shown in Fig. 13, it may not be possible to sufficiently improve communication characteristics.

[0041] 15 is a diagram illustrating a first example of the installation position of the mounting portion according to the embodiment. As shown in FIG. 15 , consider an example in which the long side 17Ca of the mounting portion 17C is positioned close to the long side 16a of the second conductor 16 in plan view on the XY plane. In this case, the distance between the long side 16a of the second conductor 16 and the long side 17Ca of the mounting portion 17C in plan view on the XY plane is defined as L1.

[0042] FIG. 16 is a diagram illustrating the radiation efficiency of the antenna in a first example of the installation position of the mounting portion according to the embodiment. In FIG. 16, the horizontal axis represents frequency [GHz], and the vertical axis represents radiation efficiency [dB]. Waveform 121 represents the radiation efficiency of the antenna 1 when the mounting portion 17C is disposed as shown in FIG. 13 . Waveform 122 represents the radiation efficiency when L1 = 0 [mm] in the example of the mounting portion 17C shown in FIG. 15 . Comparing waveforms 121 and 122, when viewed in the XY plane, the radiation characteristics of the antenna 1 deteriorate when the distance between the long side 17Ca of the mounting portion 17C and the long side 16a of the second conductor 16 is 0 [mm].

[0043] FIG. 17 is a diagram illustrating the relationship between the installation position of the mounting portion according to the embodiment and the radiation efficiency of the antenna. In FIG. 17 , the horizontal axis represents the distance between the long side 17Ca of the mounting portion 17C and the long side 16a of the second conductor 16 in planar view in the XY plane, and the vertical axis represents the radiation efficiency [dB]. The radiation efficiency shown in FIG. 17 represents the worst value of the radiation efficiency in the band from 1.71 [GHz] to 2.17 [GHz]. In FIG. 17 , the distance between the long side 17Ca of the mounting portion 17C and the long side 16a of the second conductor 16 in planar view in the XY plane is expressed as a multiple of a reference distance. The reference distance is the distance in the Z-axis direction between the conductor 12 and the second conductor 16. As shown in FIG. 17 , the radiation efficiency of the antenna 1 significantly decreases when the distance between the long side 17Ca of the mounting portion 17C and the long side 16a of the second conductor 16 in planar view in the XY plane is less than twice the reference distance. The radiation efficiency of the antenna 1 is improved when the distance between the long side 17Ca of the mounting portion 17C and the long side 16a of the second conductor 16 in plan view on the XY plane is at least twice the reference distance. That is, in this embodiment, the communication characteristics of the antenna 1 can be improved by making the distance between the long side 17Ca of the mounting portion 17C and the long side 16a of the second conductor 16 in plan view on the XY plane at least twice the reference distance.

[0044] (Second Example) Figure 18 is a diagram for explaining a second example of the installation position of the mounting portion according to the embodiment. As shown in Figure 18, consider an example in which the short side 17Cb of the mounting portion 17C is positioned close to the short side 16b of the second conductor 16 in planar view on the XY plane. In this case, the distance between the short side 16b of the second conductor 16 and the short side 17Cb of the mounting portion 17C in planar view on the XY plane is defined as L2.

[0045] FIG. 19 is a diagram illustrating the radiation efficiency of the antenna in a second example of the installation position of the mounting portion according to the embodiment. In FIG. 19, the horizontal axis represents frequency [GHz], and the vertical axis represents radiation efficiency [dB]. Waveform 131 represents the radiation efficiency of the antenna 1 when the mounting portion 17C is disposed as shown in FIG. 13 . Waveform 132 represents the radiation efficiency when L2 = 0 [mm] in the example of the mounting portion 17C shown in FIG. 18 . Comparing waveforms 131 and 132, when viewed in the XY plane, the radiation characteristics of the antenna 1 deteriorate when the distance between the short side 17Cb of the mounting portion 17C and the short side 16b of the second conductor 16 is 0 [mm].

[0046] FIG. 20 is a diagram illustrating the relationship between the installation position of the mounting portion according to the embodiment and the radiation efficiency of the antenna. In FIG. 20, the horizontal axis represents the distance between the short side 17Cb of the mounting portion 17C and the short side 16b of the second conductor 16 in planar view in the XY plane, and the vertical axis represents the radiation efficiency [dB]. The radiation efficiency shown in FIG. 20 represents the worst value of the radiation efficiency in the band from 1.71 [GHz] to 2.17 [GHz]. In FIG. 20, the distance between the short side 17Cb of the mounting portion 17C and the short side 16b of the second conductor 16 in planar view in the XY plane is shown as a multiple of a reference distance. The reference distance is the distance in the Z-axis direction between the conductor 12 and the second conductor 16. As shown in FIG. 20, the radiation efficiency of the antenna 1 decreases when the distance between the short side 17Cb of the mounting portion 17C and the short side 16b of the second conductor 16 in planar view in the XY plane is less than twice the reference distance. The radiation efficiency of the antenna 1 is improved when the distance between the short side 17Cb of the mounting portion 17C and the short side 16b of the second conductor 16 in plan view on the XY plane is at least twice the reference distance. That is, in this embodiment, the communication characteristics of the antenna 1 can be improved by making the distance between the short side 17Cb of the mounting portion 17C and the short side 16b of the second conductor 16 in plan view on the XY plane at least twice the reference distance.

[0047] (Third Example) FIG. 21 is a diagram illustrating a third example of the installation position of the mounting portion according to the embodiment. As shown in FIG. 21 , the antenna 1 may have mounting portions 17D-1, 17D-2, 17D-3, and 17D-4. The mounting portions 17D-1 to 17D-4 are formed in a rectangular shape. The mounting portions 17D-1 to 17D-4 are each formed in the same shape. The mounting portions 17D-1 to 17D-4 are arranged symmetrically with respect to the second conductor 16 in a planar view of the XY plane. The mounting portions 17D-1 to 17D-4 may also be arranged asymmetrically with respect to the second conductor 16 in a planar view of the XY plane. When it is not necessary to distinguish between the mounting portions 17D-1 to 17D-4, they will be collectively referred to as the mounting portions 17D.

[0048] The mounting portion 17D has a long side 17Da that is 30 mm long and a short side 17Db that is 15 mm long. In planar view in the XY plane, the distance between the long side 16a of the second conductor 16 and the long side 17Da of the mounting portion 17D is defined as L3. In planar view in the XY plane, the distance between the short side 16b of the second conductor 16 and the short side 17Db of the mounting portion 17D is defined as L4.

[0049] FIG. 22 is a diagram illustrating the radiation efficiency of the antenna in a third example of the installation position of the mounting portion according to the embodiment. In FIG. 22, the horizontal axis represents frequency [GHz], and the vertical axis represents radiation efficiency [dB]. Waveform 141 shows the radiation efficiency of the antenna 1 when L3 = 0 [mm] and L4 = 0 [mm] in the example of the mounting portion 17D shown in FIG. 21 . Waveform 142 shows the radiation efficiency of the antenna 1 when L3 = 3 [mm] and L4 = 3 [mm] in the example of the mounting portion 17D shown in FIG. 21 . As shown by waveforms 141 and 142, the radiation characteristics of the antenna 1 are substantially the same regardless of L3 and L4. However, by positioning the mounting portion 17D at L3 = 3 [mm] and L4 = 3 [mm], the characteristics can be improved in the low frequency band.

[0050] [Wireless Communication Device] A wireless communication device according to the embodiment will be described with reference to Fig. 23. Fig. 23 is a block diagram showing an example of the configuration of the wireless communication device according to the embodiment.

[0051] 23, the wireless communication device 200 includes an antenna 1, a memory 210, a controller 220, a sensor 230, and a battery 240. The memory 210, the controller 220, the sensor 230, and the battery 240 are also called a communication unit.

[0052] Memory 210 includes, for example, a semiconductor memory. Memory 210 may be configured to function as a work memory for controller 220. Memory 210 may be included in controller 220. Memory 210 may store a program describing the processing content that realizes each function of wireless communication device 200, information used by wireless communication device 200, and the like.

[0053] The controller 220 includes, for example, a processor. The controller 220 may include one or more processors. The processor may include a general-purpose processor that loads a specific program to execute a specific function, and a dedicated processor specialized for a specific process. The dedicated processor may include an application-specific IC. An application-specific IC is also called an ASIC (Application Specific Integrated Circuit). The processor may include a programmable logic device. A programmable logic device is also called a PLD (Programmable Logic Device). A PLD may include an FPGA (Field-Programmable Gate Array). The controller 220 may be either a SoC (System-on-a-Chip) or a SiP (System in a Package) in which one or more processors work together. The controller 220 may store various information or programs for operating each component of the wireless communication device 200 in the memory 210.

[0054] The controller 220 may be configured to generate a transmission signal to be transmitted from the wireless communication device 200. The controller 220 may be configured to acquire measurement data from a sensor, for example. The controller 220 may be configured to generate a transmission signal in response to the measurement data. The controller 220 may be configured to transmit a baseband signal to the antenna 1.

[0055] The sensor 230 includes various sensors. The sensor 230 may include, for example, a speed sensor, a vibration sensor, an acceleration sensor, a gyro sensor, a rotation angle sensor, an angular velocity sensor, a geomagnetic sensor, a magnet sensor, a temperature sensor, a humidity sensor, an air pressure sensor, a light sensor, an illuminance sensor, a UV sensor, a gas sensor, a gas concentration sensor, an atmosphere sensor, a level sensor, an odor sensor, a pressure sensor, an air pressure sensor, a contact sensor, a wind sensor, an infrared sensor, a human presence sensor, a displacement sensor, an image sensor, a weight sensor, a smoke sensor, a liquid leakage sensor, a vital sign sensor, a battery remaining amount sensor, and an ultrasonic sensor. The sensor 230 may also include a GNSS (Global Navigation Satellite System) sensor that acquires current location information of the wireless communication device 200.

[0056] Battery 240 may be configured to provide power to wireless communication device 200. Battery 240 may be configured to provide power to at least one of memory 210, controller 220, and sensor 230. Battery 240 includes at least one of a primary battery and a secondary battery.

[0057] [Other Embodiments] The antenna 1 and the wireless communication device 200 according to the embodiments may be installed in various structures. In this case, the conductor 12 of the antenna 1 may be installed on a metal member. The structure may be, for example, a delivery box that stores packages delivered to users by a delivery company or the like. In this case, for example, the antenna 1 or the wireless communication device 200 transmits and receives various information related to the packages stored in the delivery box to and from a server device or the like. The structure may be, for example, a container or a pallet for transporting various packages.

[0058] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the contents of these embodiments. Furthermore, the above-described components include those that can be easily imagined by a person skilled in the art, those that are substantially the same, and those that are within the so-called equivalent range. Furthermore, the above-described components can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the spirit of the above-described embodiments.

[0059] REFERENCE SIGNS LIST 1 Antenna 2 Box 3 Resin plate 4 Storage section 11 Housing 11a Support section 12 Conductor 13 First board 14 Second board 15 First conductor 16 Second conductor 17, 17A, 17B, 17C Mounting section 20 Cable 30 Connection section 40 Through hole 200 Wireless communication device 210 Memory 220 Controller 230 Sensor 240 Battery

Claims

1. An antenna comprising: a first conductor extending over a first surface; a second conductor located away from the first conductor in a first direction, electrically connected to the first conductor, and extending over the first surface serving as a potential reference for the first conductor; a housing that houses the first conductor and the second conductor and has a surface facing the second conductor that is an electrically conductive conductor; and a mounting portion provided inside the housing between the second conductor and the conductor, electrically insulating the second conductor from the conductor and fixing the second conductor to the conductor, wherein the mounting portion is smaller than the second conductor in a plan view and does not contact an end of the second conductor.

2. The antenna as described in claim 1, wherein the mounting portion is formed in a rectangular shape extending over the first surface, the length of the long side of the mounting portion is less than λ, where λ is the dielectric wavelength of the radio waves to be transmitted and received within the mounting portion, and the short side of the mounting portion does not contact an end of the second conductor.

3. The antenna according to claim 2, wherein the length of the short side of the mounting portion is λ / 2 or less, and the long side of the mounting portion does not contact the end of the second conductor.

4. The antenna according to claim 3, wherein the mounting portion is divided into a plurality of portions, and each of the long and short sides of the divided mounting portions does not contact an end of the second conductor.

5. The antenna as described in claim 3, wherein the distance between the long side of the mounting portion and the end of the second conductor, and the distance between the short side of the mounting portion and the end of the second conductor are each at least twice the distance between the second conductor and the conductor.

6. The antenna as described in claim 1, wherein the mounting portion is formed in a rectangular shape extending over the first surface, the length of the short side of the mounting portion is not more than λ / 2, where λ is the dielectric wavelength of the radio waves to be transmitted and received within the mounting portion, and the long side of the mounting portion does not contact an end of the second conductor.

7. The second conductor is a substrate electrically connected to the ground by a plurality of through holes, and the spacing between the plurality of through holes is set to λ 1 , which is the wavelength of the maximum frequency of the radio waves to be transmitted and received. Ｍａｘ Then, λ Ｍａｘ 3. The antenna according to claim 1, wherein the .lambda. / 4 or less.

8. The antenna according to claim 1 or 2, wherein the second conductor is a metal plate.

9. The antenna according to claim 1 or 2, wherein the mounting portion is a resin sheet.

10. A wireless communication device comprising: the antenna according to claim 1; and a communication unit for wirelessly communicating with an external device via the antenna.

11. A structure comprising the wireless communication device of claim 10.

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