Wireless communication device and structure

Abstract

This wireless communication device comprises: an antenna; and a communication unit disposed in the antenna. The antenna is provided with: a first conductor; a second conductor connected to the first conductor; a third conductor that is connected to the first conductor and is placed side by side with the second conductor; a fourth conductor positioned between the second conductor and the third conductor so as to be separated from the second and third conductors; a first connection conductor having one end connected to the first conductor and having the other end connected to the second conductor; a second connection conductor having one end connected to the first conductor and having the other end connected to the third conductor; and a power feeding conductor having one end connected to a power feeding point and having the other end connected to one of the first, second, third, and fourth conductors that faces the power feeding point. The communication unit is disposed at a position in the antenna where the magnetic field intensity is relatively high.

Description

[Technical field]

[0001] The present disclosure relates to wireless communication devices and structures. [Background technology]

[0002] There are known techniques for miniaturizing communication devices. For example, Patent Document 1 describes a wireless communication device that is miniaturized by incorporating an antenna and a communication unit in a single housing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-83240 Summary of the Invention

[0004] A wireless communication device according to the present disclosure includes an antenna, and a communication unit disposed inside the antenna and configured to perform wireless communication with an external device via the antenna, the antenna including a first conductor extending in a first surface direction, a second conductor extending in the first surface direction facing a first end of the first conductor in the first direction and connected to the first conductor, a third conductor extending in the first surface direction aligned with the second conductor in the first direction facing a second end of the first conductor in the first direction and connected to the first conductor, and a second conductor extending in the first surface direction aligned with the second conductor in the first direction between the second conductor and the third conductor in the first direction. the communication unit is disposed at a position inside the antenna where the magnetic field strength is relatively strong, the communication unit being disposed at a position where the magnetic field strength is relatively strong inside the antenna.

[0005] A structure according to the present disclosure includes a wireless communication device according to the present disclosure. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a wireless communication device according to the first embodiment. [Diagram 2] FIG. 2 is a diagram showing a configuration example of the upper conductor of the antenna according to the first embodiment. [Diagram 3] FIG. 3 is a diagram showing a configuration example of the bottom conductor of the antenna according to the first embodiment. [Figure 4] FIG. 4 is a block diagram showing an example of the configuration of the communication unit according to the first embodiment. [Diagram 5] FIG. 5 is a diagram showing a current flow in the wireless communication device according to the first embodiment. [Figure 6] FIG. 6 is a diagram showing a current flow in the upper conductor of the antenna according to the first embodiment. [Figure 7] FIG. 7 is a diagram showing a current flow in the bottom conductor of the antenna according to the first embodiment. [Figure 8] FIG. 8 is a diagram for explaining the flow of a magnetic field inside the antenna according to the first embodiment. [Figure 9] FIG. 9 is a diagram showing a simulation result of the magnetic field strength inside the antenna according to the first embodiment. [Figure 10] FIG. 10 is a diagram for explaining a method of arranging communication units according to a first comparative example. [Figure 11] FIG. 11 is a diagram showing the flow of a magnetic field inside the antenna according to the first comparative example. [Figure 12] FIG. 12 is a diagram for explaining the radiation efficiency of the antenna according to the first comparative example. [Figure 13] FIG. 13 is a diagram for explaining a method of arranging communication units according to the second comparative example. [Figure 14] FIG. 14 is a diagram showing the flow of a magnetic field inside the antenna according to the second comparative example. [Figure 15]FIG. 15 is a diagram for explaining the radiation efficiency of the antenna according to the second comparative example. [Figure 16] FIG. 16 is a diagram for explaining a method of arranging the communication units according to the first embodiment. [Figure 17] FIG. 17 is a diagram showing the flow of a magnetic field inside the antenna according to the first embodiment. [Figure 18] FIG. 18 is a diagram for explaining the radiation efficiency of the antenna according to the first embodiment. [Figure 19] FIG. 19 is a diagram for explaining the radiation efficiency of the antenna according to the first embodiment. [Figure 20] FIG. 20 is a diagram for explaining the arrangement direction of the communication unit according to the first embodiment. [Figure 21] FIG. 21 is a diagram for explaining the arrangement direction of the communication unit and the radiation efficiency of the antenna according to the first embodiment. [Figure 22] FIG. 22 is a diagram illustrating an example of the configuration of a wireless communication device according to the second embodiment. [Figure 23] FIG. 23 is a diagram illustrating a configuration example of the upper conductor of the antenna according to the second embodiment. [Figure 24] FIG. 24 is a diagram for explaining the radiation efficiency of the antenna according to the second embodiment. In FIG. [Diagram 25] FIG. 25 is a diagram showing a method of arranging a communication unit on the bottom conductor of the antenna according to the second embodiment. [Figure 26] FIG. 26 is a diagram showing a configuration example of a bottom conductor according to a modified example of the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] 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 duplicated explanations will be omitted.

[0008] In the following description, an XYZ Cartesian coordinate system is set, and the positional relationship of each part is 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. A plane including the X-axis and Y-axis is appropriately referred to as the XY plane. A plane including the X-axis and Z-axis is appropriately referred to as the XZ plane. A plane including the Y-axis and Z-axis is appropriately referred to as the YZ plane. The XY plane is parallel to the horizontal plane. The XY plane, the XZ plane, and the YZ plane are perpendicular to each other.

[0009] [First embodiment] An example of the configuration of a wireless communication device according to the first embodiment will be described with reference to Fig. 1, Fig. 2, and Fig. 3. Fig. 1 is a diagram showing an example of the configuration of a wireless communication device according to the first embodiment. Fig. 2 is a diagram showing an example of the configuration of an upper conductor of an antenna according to the first embodiment. Fig. 3 is a diagram showing an example of the configuration of a lower conductor of an antenna according to the first embodiment. Fig. 1 shows a cross-sectional view taken along line II in Fig. 2.

[0010] As shown in FIGS. 1 to 3, the wireless communication device 1 includes an antenna 2 and a communication unit 3.

[0011] The antenna 2 includes a first conductor 10, a second conductor 12, a third conductor 14, a fourth conductor 16, a first connecting conductor 201, a first connecting conductor 202, a second connecting conductor 221, a second connecting conductor 222, a power supply conductor 24, and a housing 26. The first conductor 10, the second conductor 12, the third conductor 14, the fourth conductor 16, the first connecting conductor 201, the first connecting conductor 202, the second connecting conductor 221, the second connecting conductor 222, and the power supply conductor 24 are accommodated in the housing 26. The first connecting conductor 201 and the first connecting conductor 202 may be collectively referred to as the first connecting conductor 20. The second connecting conductor 221 and the second connecting conductor 222 may be collectively referred to as the second connecting conductor 22. The antenna 2 is mounted on the metal member 4, for example, on the first conductor 10 side. The antenna 2 does not necessarily have to be mounted on the metal member 4 on the side of the first conductor 10. The metal member 4 is a type of conductive article.

[0012] The antenna 2 is configured to be capable of radiating circularly polarized waves. The antenna 2 is configured to exhibit artificial magnetic conductor characters with respect to electromagnetic waves of a predetermined frequency incident on the XY plane of the antenna 2 from the positive side of the Z axis. In the present disclosure, the artificial magnetic conductor characters refer to the characteristics of a surface where the phase difference between an incident wave and a reflected wave is 0 degrees. On a surface having artificial magnetic wall characteristics, the phase difference between an incident wave and a reflected wave is -90 degrees to +90 degrees in a frequency band.

[0013] The first conductor 10 is a conductor extending in the XY plane. The XY plane is sometimes called the first surface. The X-axis direction is sometimes called the first direction, and the Y-axis direction is sometimes called the second direction. The first conductor 10 is sometimes called the bottom surface conductor of the antenna 2. The first conductor 10 is configured, for example, in a substantially rectangular shape, but is not limited thereto. In this embodiment, the first conductor 10 has a rectangular shape in which the length in the X-axis direction is longer than the length in the Y-axis direction. The width of the first conductor 10 in the X-axis direction is wider than the widths of the second conductor 12, the third conductor 14, and the fourth conductor 16.

[0014] The second conductor 12, the third conductor 14, and the fourth conductor 16 are located away from the first conductor 10 in the Z-axis direction. The second conductor 12, the third conductor 14, and the fourth conductor 16 face the first conductor 10. The second conductor 12, the third conductor 14, and the fourth conductor 16 are sometimes called the upper conductors of the antenna 2. The widths in the Y-axis direction of the first conductor 10, the second conductor 12, the third conductor 14, and the fourth conductor 16 may be the same. The widths in the X-axis direction of the second conductor 12 and the third conductor 14 may be the same. The width in the X-axis direction of the fourth conductor 16 is wider than the widths in the X-axis direction of the second conductor 12 and the third conductor 14.

[0015] The second conductor 12 faces a first end in the X-axis direction of the first conductor 10. The first end is an end on the negative side of the X-axis direction of the first conductor 10. The second conductor 12 is configured in, for example, a substantially rectangular shape, but is not limited to this.

[0016] The third conductor 14 faces a second end of the first conductor 10 in the X-axis direction. The second end is an end of the first conductor 10 on the positive side of the X-axis. The third conductor 14 is configured, for example, in a substantially rectangular shape, but is not limited thereto. The third conductor 14 is aligned with the second conductor 12 along the X-axis direction.

[0017] The fourth conductor 16 is located between the second conductor 12 and the third conductor 14. The fourth conductor 16 is aligned with the second conductor 12 and the third conductor 14 along the X-axis direction. The fourth conductor 16 is not in contact with the second conductor 12 and the third conductor 14. That is, a gap is formed between the second conductor 12 and the fourth conductor 16 and between the third conductor 14 and the fourth conductor 16. The fourth conductor 16 faces the first conductor 10 between the second conductor 12 and the third conductor 14. The fourth conductor 16 is configured to have, for example, a substantially rectangular shape, but is not limited thereto. A plurality of fourth conductors 16 may be located between the second conductor 12 and the third conductor 14. When a plurality of fourth conductors 16 are located, the respective fourth conductors 16 are not in contact with each other. When a plurality of fourth conductors 16 are located, a gap is formed between the respective fourth conductors 16, and the fourth conductors 16 are aligned along the X-axis direction. That is, at least one fourth conductor 16 may be located between the second conductor 12 and the third conductor 14.

[0018] The second conductor 12 and the fourth conductor 16 are capacitively connected via a gap. The third conductor 14 and the fourth conductor 16 are capacitively connected via a gap. When a plurality of fourth conductors 16 are positioned between the second conductor 12 and the third conductor 14, the respective fourth conductors 16 are capacitively connected to each other via a gap.

[0019] The first connecting conductor 201 and the first connecting conductor 202 are configured to connect the first conductor 10 and the second conductor 12. The first connecting conductor 201 and the first connecting conductor 202 are, for example, columnar bodies extending in the Z-axis direction. The first connecting conductor 201 and the first connecting conductor 202 are aligned along the Y-axis direction.

[0020] The second connecting conductor 221 and the second connecting conductor 222 are configured to connect the first conductor 10 and the third conductor 14. The second connecting conductor 221 and the second connecting conductor 222 are, for example, columnar bodies extending in the Z-axis direction. The second connecting conductor 221 and the second connecting conductor 222 are aligned along the Y-axis direction.

[0021] The power supply conductor 24 is configured such that one end is connected to the power supply point P1 and the other end is connected to the second conductor 12. In this embodiment, the power supply point P1 is provided in the first conductor 10 near the first connecting conductor 202. The power supply point P1 may be provided in the first conductor 10 near the first connecting conductor 201, the second connecting conductor 221, or the second connecting conductor 222. The power supply conductor 24 is, for example, a columnar body extending in the Z-axis direction. As shown in FIG. 3, a clearance C is provided between the power supply point P1 and the first conductor 10. That is, the power supply point P1 is provided in the first conductor 10 via a gap. Since the clearance C is provided between the power supply point P1 and the first conductor 10, the power supply conductor 24 and the first conductor 10 are not connected. The power supply conductor 24 may be configured such that one end is connected to the power supply point P1 and the other end is connected to the third conductor 14. The power supply conductor 24 may be configured such that one end is connected to the power supply point P1 and the other end is connected to the fourth conductor 16. That is, the power supply conductor 24 may be configured such that one end is connected to the power supply point P1 and the other end is connected to any one of the second conductor 12, the third conductor 14, and the fourth conductor 16 that faces the power supply point P1.

[0022] The communication unit 3 is disposed inside the antenna 2. The communication unit 3 is disposed on the first conductor 10. The communication unit 3 is mounted on, for example, a mounting portion (not shown) provided on the first conductor 10. The communication unit 3 may be attached to the first conductor 10 with, for example, double-sided tape or adhesive. The communication unit 3 has a structure shielded with a metal cap or the like. The communication unit 3 is formed, for example, in a rectangular parallelepiped shape. In the example shown in FIG. 3, the communication unit 3 has a length in the Y-axis direction shorter than its length in the X-axis direction. In this embodiment, the communication unit 3 is described as being formed in a rectangular parallelepiped shape, but the present disclosure is not limited thereto. The communication unit 3 may be formed in a cubic shape or a cylindrical shape. The communication unit 3 is connected to one end of a power feed line 5 such as a cable. The other end of the power feed line 5 is connected to a power feed point P1. That is, the communication unit 3 is connected to the power feed point P1 via the power feed line 5. For example, when transmitting radio waves, power (signal) is supplied from the communication unit 3 to the second conductor 12 via the feed point P1. For example, when receiving radio waves, power (signal) is supplied from the second conductor 12 to the communication unit 3 via the feed point P1. The communication unit 3 and the feed point P1 may be connected by a feed pattern extending from the feed point P1 to the communication unit 3.

[0023] An example of the configuration of a communication unit according to the first embodiment will be described with reference to Fig. 4. Fig. 4 is a block diagram showing an example of the configuration of a communication unit according to the first embodiment.

[0024] As shown in FIG. 4, the communication unit 3 includes a memory 30, a controller 32, a sensor 34, and a battery 36.

[0025] The memory 30 may include, for example, a semiconductor memory. The memory 30 may be configured to function as a work memory for the controller 32. The memory 30 may be included in the controller 32. The memory 30 stores a program describing the processing contents for realizing each function of the wireless communication device 1, information used by the wireless communication device 1, and the like.

[0026] The controller 32 may include, for example, a processor. The controller 32 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. The application-specific IC is also called an ASIC (Application Specific Integrated Circuit). The processor may include a programmable logic device. The programmable logic device is also called a PLD (Programmable Logic Device). The PLD may include an FPGA (Field-Programmable Gate Array). The controller 32 may be either a SoC (System-on-a-Chip) in which one or more processors work together, or a SiP (System in a Package). The controller 32 may store various information, programs for operating each component of the wireless communication device 1, and the like in the memory 30.

[0027] The controller 32 may be configured to generate a transmission signal to be transmitted from the wireless communication device 1. The controller 32 may be configured to acquire measurement data from the sensor 34, for example. The controller 32 may be configured to generate a transmission signal according to the measurement data. The controller 32 may be configured to transmit a baseband signal to the antenna 2.

[0028] The sensor 34 includes various sensors. The sensor 34 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 sensor, a displacement amount sensor, an image sensor, a weight sensor, a smoke sensor, a liquid leakage sensor, a vital sensor, a battery remaining amount sensor, and an ultrasonic sensor. The sensor 34 may include a GNSS (Global Navigation Satellite System) sensor that acquires current position information of the wireless communication device 1.

[0029] The battery 36 may be configured to supply power to the wireless communication device 1. The battery 36 may be configured to supply power to at least one of the memory 30, the controller 32, and the sensor 34. The battery 36 may include at least one of a primary battery and a secondary battery. A negative electrode of the battery 36 may be configured to be electrically connected to a ground terminal of a circuit board (not shown).

[0030] Next, a method for arranging the communication units according to the first embodiment will be described.

[0031] Fig. 5, Fig. 6, and Fig. 7 are diagrams for explaining the flow of current in the antenna 2 according to the first embodiment. Fig. 5 is a diagram showing the flow of current in the wireless communication device according to the first embodiment. Fig. 5 shows a cross section at the same position as line II shown in Fig. 2. Fig. 6 is a diagram showing the flow of current in the upper conductor of the antenna according to the first embodiment. Fig. 7 is a diagram showing the flow of current in the lower conductor of the antenna according to the first embodiment.

[0032] As shown in Figures 5 to 7, current I flows in a circular manner through the first conductor 10, the first connecting conductor 20, the second conductor 12, the fourth conductor 16, the third conductor 14, the second connecting conductor 22, and the first conductor 10 in that order.

[0033] 8 is a diagram for explaining the flow of a magnetic field inside the antenna 2 according to the first embodiment. FIG. 8 illustrates a schematic diagram of the flow of a magnetic field between the first conductor 10 and the second conductor 12, the third conductor 14, and the fourth conductor 16.

[0034] The magnetic field M1 is a magnetic field generated by a current flowing through the first connecting conductor 201. The magnetic field M2 is a magnetic field generated by a current flowing through the first connecting conductor 202. Since the currents flowing through the first connecting conductor 201 and the first connecting conductor 202 have the same direction, the magnetic fields M1 and M2 have the same direction. The magnetic fields M1 and M2 are counterclockwise circular magnetic fields surrounding the first connecting conductor 201 and the first connecting conductor 202, respectively, when viewed from above on the XY plane.

[0035] The magnetic field M3 is a magnetic field generated by a current flowing through the second connecting conductor 221. The magnetic field M4 is a magnetic field generated by a current flowing through the second connecting conductor 222. Since the currents flowing through the second connecting conductor 221 and the second connecting conductor 222 have the same direction, the magnetic fields M3 and M4 have the same direction. The magnetic fields M3 and M4 are clockwise circular magnetic fields surrounding the second connecting conductor 221 and the second connecting conductor 222, respectively, when viewed from above on the XY plane.

[0036] Since the directions of the currents flowing through the first connecting conductor 20 and the second connecting conductor 22 are opposite to each other, the directions of the magnetic fields M1 and M2 and the magnetic fields M3 and M4 are opposite to each other.

[0037] The magnetic field M5 is generated by the current flowing through the power supply conductor 24. When viewed from above on the XY plane, the magnetic field M5 is a counterclockwise circular magnetic field surrounding the power supply conductor 24. Since the direction of the current flowing through the power supply conductor 24 is the same as the direction of the current flowing through the first connecting conductor 20, the magnetic field M5 has the same direction as the magnetic fields M1 and M2.

[0038] The magnetic field M6 is a magnetic field near the center in the X-axis direction generated by the current flowing through the first conductor 10, the second conductor 12, the third conductor 14, and the fourth conductor 16. The magnetic field M6 is a magnetic field parallel to the Y-axis direction in a top view of the XY plane. In the example shown in FIG. 8, the magnetic field M6 is a magnetic field flowing from the -Y-axis direction to the +Y-axis direction. The direction of the current flowing through the first conductor 10 is opposite to that of the current flowing through the second conductor 12, the third conductor 14, and the fourth conductor 16. Therefore, the direction of the magnetic field generated by the current flowing through the first conductor 10 is opposite to that of the magnetic field generated by the current flowing through the second conductor 12, the third conductor 14, and the fourth conductor 16. The magnetic fields between the first conductor 10 and the second conductor 12, the third conductor 14, and the fourth conductor 16 are in the same direction, such as the direction of the magnetic field being the +Y-axis direction or the -Y-axis direction. The magnetic field M6 is the sum of a magnetic field generated by the current flowing through the first conductor 10, a magnetic field generated by the current flowing through the second conductor 12, the third conductor 14, and the fourth conductor 16, and a magnetic field generated by the current flowing through the first connecting conductor 20 and the second connecting conductor 22. The directions of the magnetic fields M1 to M4 between the first conductor 10 and the second conductor 12, the third conductor 14, and the fourth conductor 16 are respectively in the +Y-axis direction. In this embodiment, since the connecting conductors are spaced apart from one another, the influence of the magnetic fields M1 to M4 on the magnetic field M6 is relatively small.

[0039] The directions of the magnetic fields M1 and M2 are opposite between the first connecting conductor 201 and the first connecting conductor 202. Therefore, the magnetic fields M1 and M2 cancel each other out between the first connecting conductor 201 and the first connecting conductor 202, weakening the magnetic field.

[0040] The directions of the magnetic fields M3 and M4 are opposite between the second connecting conductor 221 and the second connecting conductor 222. Therefore, the magnetic fields M3 and M4 cancel each other out between the second connecting conductor 221 and the second connecting conductor 222, weakening the magnetic field.

[0041] FIG. 9 is a diagram showing a simulation result of the magnetic field strength inside the antenna 2 according to the first embodiment. In FIG. 9, the stronger the magnetic field strength is, the darker the color is, and the weaker the magnetic field strength is, the lighter the color is. As shown in FIG. 9, inside the antenna 2, the first connecting conductor 201, the first connecting conductor 202, the second connecting conductor 221, the second connecting conductor 222, and the area around the power supply conductor 24 are areas where the magnetic field strength is strongest, and inside the antenna 2, the area near the center in the longitudinal direction is an area where the magnetic field strength is relatively strong. Inside the antenna 2, the area between the first connecting conductor 201 and the first connecting conductor 202 and the area between the second connecting conductor 221 and the second connecting conductor 222 are areas where the magnetic field strength is weakest.

[0042] 8 and 9, the magnetic field flow and magnetic field strength vary depending on the location inside the antenna 2. In this embodiment, the location of the communication unit 3 is determined based on at least one of the magnetic field flow and magnetic field strength inside the antenna 2. In this embodiment, the communication unit 3 is placed at a position inside the antenna 2 where the magnetic field strength is relatively strong. Specifically, in this embodiment, the communication unit 3 is placed near the first connecting conductor 20 or the second connecting conductor 22 where the magnetic field strength is relatively strong.

[0043] [Communication unit arrangement method according to the comparative example] Before describing the method of arranging the communication unit 3 according to the first embodiment, a method of arranging the communication unit 3 according to a comparative example will be described.

[0044] (First Comparative Example) Fig. 10 is a diagram for explaining a method of arranging the communication unit 3 according to the first comparative example. Fig. 10 is a diagram of the first conductor 10 as viewed from above. As shown in Fig. 10, for example, the communication unit 3 is arranged between the second connecting conductor 221 and the second connecting conductor 222 in the first conductor 10. In the example shown in Fig. 10, the communication unit 3 is arranged between the second connecting conductor 221 and the second connecting conductor 222 in the first conductor 10 so that the longitudinal direction of the communication unit 3 and the longitudinal direction of the first conductor 10 are aligned.

[0045] 11 is a diagram showing the flow of a magnetic field inside the antenna 2 according to the first comparative example.

[0046] As shown in Fig. 11, the communication unit 3 is disposed between the second connecting conductor 221 and the second connecting conductor 222. A magnetic field M3 is generated around the second connecting conductor 221. A magnetic field M4 is disposed around the second connecting conductor 222. Since the communication unit 3 is disposed in an area where the magnetic field is weak, almost no magnetic field flows in the space between the third conductor 14 and the communication unit 3. In other words, when the communication unit 3 is disposed in an area where the magnetic field is weak because the directions of the magnetic fields M3 and M4 are opposite to each other, the magnetic fields do not weaken each other in that area, and the magnetic field becomes stronger than when the communication unit 3 is not disposed.

[0047] The radiation efficiency of the antenna according to the first comparative example will be described with reference to Fig. 12. Fig. 12 is a diagram for explaining the radiation efficiency of the antenna according to the first comparative example.

[0048] 12, the horizontal axis indicates frequency [MHz (megahertz)], and the vertical axis indicates total radiation efficiency [dB (decibels)]. Graph G1 shows the total radiation efficiency of the antenna 2 when the communication unit 3 is not arranged. Graph G2 shows the total radiation efficiency of the antenna 2 when the communication unit 3 is arranged on the first conductor 10 between the second connecting conductor 221 and the second connecting conductor 222.

[0049] In the example shown in FIG. 12, as shown in graph G1, the resonant frequency of the antenna 2 is about 900 MHz. As shown in graph G2, the resonant frequency of the antenna 2 when it is arranged between the second connecting conductor 221 and the second connecting conductor 222 is 800 MHz or less. When the communication unit 3 is arranged between the second connecting conductor 221 and the second connecting conductor 222 in the first conductor 10, the inductance component of the antenna 2 increases, and the resonant frequency shifts to the lower frequency side. That is, when the communication unit 3 is arranged between the second connecting conductor 221 and the second connecting conductor 222 in the first conductor 10, the radiation characteristics of the antenna 2 change from the case when the communication unit 3 is not arranged in the first conductor 10.

[0050] (Second Comparative Example) Fig. 13 is a diagram for explaining a method of arranging the communication unit 3 according to the second comparative example. Fig. 13 is a diagram of the first conductor 10 as viewed from above. As shown in Fig. 13, for example, the communication unit 3 is arranged in the center of the first conductor 10. In the example shown in Fig. 10, the communication unit 3 is arranged in the center of the first conductor 10 so that the longitudinal direction of the communication unit 3 and the longitudinal direction of the first conductor 10 are aligned.

[0051] 14 is a diagram showing the flow of a magnetic field inside the antenna 2 according to the second comparative example.

[0052] 14, the communication unit 3 is disposed in the center of the first conductor 10. A magnetic field M6 is generated in the center of the first conductor 10. A part of the magnetic field M6 is blocked by the communication unit 3, and the rest flows in the space between the third conductor 14 and the communication unit 3. In other words, by disposing the communication unit 3 in the center of the first conductor 10, the magnetic field in the center of the first conductor 10 is weaker than when the communication unit 3 is not disposed.

[0053] The radiation efficiency of the antenna according to the second comparative example will be described with reference to Fig. 15. Fig. 15 is a diagram for explaining the radiation efficiency of the antenna according to the second comparative example.

[0054] 15, the horizontal axis indicates frequency [MHz], and the vertical axis indicates total radiation efficiency [dB]. Graph G1 indicates the total radiation efficiency of the antenna 2 when the communication unit 3 is not disposed. Graph G3 indicates the total radiation efficiency of the antenna 2 when the communication unit 3 is disposed in the center of the first conductor 10 so that the longitudinal direction of the communication unit 3 and the longitudinal direction of the first conductor 10 are aligned.

[0055] In the example shown in FIG. 15, as shown in graph G1, the resonant frequency of the antenna 2 is about 900 MHz. As shown in graph G3, the resonant frequency of the antenna 2 when the communication unit 3 is arranged in the center of the first conductor 10 is 900 MHz or higher. When the communication unit 3 is arranged in the center of the first conductor 10, the inductance component of the antenna 2 is reduced, and the resonant frequency shifts to the high frequency side. In other words, when the communication unit 3 is arranged in the center of the first conductor 10, the radiation characteristics change from those of the antenna 2 when the communication unit 3 is not arranged on the first conductor 10.

[0056] [Communication unit arrangement method according to the first embodiment] Fig. 16 is a diagram for explaining a method of arranging the communication unit 3 according to the first embodiment. Fig. 16 is a diagram of the first conductor 10 as viewed from above. As shown in Fig. 16, for example, the communication unit 3 is arranged near the second connecting conductor 221 of the first conductor 10. In the example shown in Fig. 16, the communication unit 3 is arranged near the second connecting conductor 221 of the first conductor 10 so that the longitudinal direction of the communication unit 3 and the longitudinal direction of the first conductor 10 are aligned.

[0057] 17 is a diagram showing the flow of a magnetic field inside the antenna 2 according to the first embodiment. FIG 17 shows a cross-sectional view taken along line CC in FIG.

[0058] As shown in FIG. 17, the communication unit 3 is disposed near the second connecting conductor 221. A magnetic field M3 is generated around the second connecting conductor 221. Since the communication unit 3 is disposed near the second connecting conductor 221, the strength of the magnetic field M3 is strong around the communication unit 3. Therefore, the magnetic field M3 flows in the space between the communication unit 3 and the third conductor 14 without being blocked by the communication unit 3. As a result, the magnetic field M3 generated around the second connecting conductor 221 and the magnetic field M4 generated around the second connecting conductor 222 cancel each other out.

[0059] The radiation efficiency of the antenna according to the first embodiment will be described with reference to Fig. 18. Fig. 18 is a diagram for explaining the radiation efficiency of the antenna according to the first embodiment.

[0060] 18, the horizontal axis indicates frequency [MHz], and the vertical axis indicates total radiation efficiency [dB]. Graph G1 indicates the total radiation efficiency of the antenna 2 when the communication unit 3 is not disposed. Graph G4 indicates the total radiation efficiency of the antenna 2 when the communication unit 3 is disposed in the first conductor 10 near the second connecting conductor 221.

[0061] As shown in FIG. 18, the resonance frequency of the graph G1 and the resonance frequency of the graph G4 are both 900 MHz and are almost the same. The overall radiation efficiency at the resonance frequency of the graph G1 is about -2 dB, which is good. The overall radiation efficiency at the resonance frequency of the graph G4 is slightly lower than -2 dB, but is good. The graph G4 shows characteristics close to those of the graph G1 in the band from 750 MHz to 950 MHz. That is, it can be said that the radiation characteristics of the antenna 2 in which the communication unit 3 is arranged near the second connecting conductor 221 are comparable to the radiation characteristics of the antenna 2 in which the communication unit 3 is not arranged. That is, by arranging the communication unit 3 near the second connecting conductor 221 in the first conductor 10, the antenna 2 and the communication unit 3 can be integrated without changing the characteristics of the antenna 2. This allows the wireless communication device 1 to be made smaller in size.

[0062] The radiation efficiency of the antenna according to the first embodiment will be described with reference to Fig. 19. Fig. 19 is a diagram for explaining the radiation efficiency of the antenna according to the first embodiment.

[0063] In FIG. 19, the horizontal axis indicates frequency [MHz], and the vertical axis indicates total radiation efficiency [dB]. Graph G1 shows the radiation efficiency of the antenna 2 when the communication unit 3 is not arranged on the first conductor 10. Graph G4 shows the radiation efficiency of the antenna 2 when the communication unit 3 is arranged near the second connecting conductor 221 on the first conductor 10. Graph G5 shows the radiation efficiency of the antenna 2 when the communication unit 3 is arranged near the second connecting conductor 222 on the first conductor 10. Graph G6 shows the radiation efficiency of the antenna 2 when the communication unit 3 is arranged near the first connecting conductor 201 on the first conductor 10. In the example shown in FIG. 19, the communication unit 3 is arranged on the first conductor 10 so that the longitudinal direction of the communication unit 3 and the longitudinal direction of the first conductor 10 are aligned.

[0064] 19, the graph G4 and the graph G5 are almost the same. That is, in the first conductor 10, the radiation characteristics of the antenna 2 when the communication unit 3 is arranged near the second connecting conductor 221 are almost the same as those when the communication unit 3 is arranged near the second connecting conductor 222.

[0065] Graph G6 has a radiation characteristic of about -2 dB at the resonant frequency. Graph G6 has a radiation characteristic at the resonant frequency that is almost the same as that of graph G1. In the first conductor 10, the radiation characteristic of the antenna 2 at the resonant frequency when the communication unit 3 is arranged near the first connecting conductor 201 is almost the same as the radiation characteristic of the antenna 2 at the resonant frequency when the communication unit 3 is not arranged. That is, in the first conductor 10, it is preferable to arrange the communication unit 3 near the first connecting conductor 201 rather than near the second connecting conductor 221 and the second connecting conductor 222.

[0066] That is, as shown in Figure 19, in this embodiment, the communication unit 3 is arranged in the first conductor 10 near the first connecting conductor 201, the second connecting conductor 221, or the second connecting conductor 222, thereby making it possible to integrate the antenna 2 and the communication unit 3.

[0067] In this embodiment, as shown in Fig. 3 and other figures, since the power feed point P1 and the power feed conductor 24 are provided near the first connecting conductor 202, there is a possibility that the communication unit 3 cannot be provided near the first connecting conductor 202 due to space limitations. Therefore, the communication unit 3 is preferably provided near any of the first connecting conductor 201, the second connecting conductor 221, and the second connecting conductor 222 other than the first connecting conductor 202 provided near the power feed point P1 and the power feed conductor 24. However, if the space limitations are eliminated by, for example, miniaturizing the communication unit 3, the communication unit 3 may be provided near the first connecting conductor 202.

[0068] 3 and other figures, the communication unit 3 and the power feed point P1 are connected by a power feed line 5. From the viewpoint of routing the power feed line 5, it is preferable to place the communication unit 3 near the first connecting conductor 201 or the first connecting conductor 202 rather than near the second connecting conductor 221 or the second connecting conductor 222.

[0069] (Communication unit placement direction) Next, the orientation of the communication unit 3 will be described.

[0070] Fig. 20 is a diagram for explaining the arrangement direction of the communication unit 3 according to the first embodiment. In the example shown in Fig. 20, the communication unit 3 is arranged in the first conductor 10 near the second connection conductor 221 such that the longitudinal direction is aligned with the lateral direction of the first conductor 10.

[0071] The relationship between the arrangement direction of the communication unit according to the first embodiment and the radiation efficiency of the antenna will be described with reference to Fig. 21. Fig. 21 is a diagram for explaining the arrangement direction of the communication unit according to the first embodiment and the radiation efficiency of the antenna.

[0072] In Fig. 21, the horizontal axis indicates frequency [MHz], and the vertical axis indicates total radiation efficiency [dB]. Graph G1 indicates the radiation efficiency of the antenna 2 when the communication unit 3 is not arranged on the first conductor 10. Graph G4 indicates the total radiation efficiency of the antenna 2 when the communication unit 3 is arranged on the first conductor 10 near the second connecting conductor 221 with its longitudinal direction parallel to the longitudinal direction of the first conductor 10. Graph G7 indicates the total radiation efficiency of the antenna 2 when the communication unit 3 is arranged on the first conductor 10 near the second connecting conductor 221 with its longitudinal direction parallel to the transverse direction of the first conductor 10.

[0073] As shown in graph G7, in the first conductor 10, when the communication unit 3 is arranged in the vicinity of the second connecting conductor 221 with its longitudinal direction parallel to the short side direction of the first conductor 10, the resonant frequency of the antenna 2 is 900 MHz or less. When the communication unit 3 is arranged in the vicinity of the second connecting conductor 221 with its longitudinal direction parallel to the short side direction of the first conductor 10, the communication unit 3 may reach a region where the magnetic field between the second connecting conductor 221 and the second connecting conductor 222 is weakened. Therefore, the magnetic field does not weaken each other in the region between the second connecting conductor 221 and the second connecting conductor 222, so the magnetic field becomes stronger than when the communication unit 3 is not arranged. That is, in the first conductor 10, when the communication unit 3 is arranged between the second connecting conductor 221 and the second connecting conductor 222, the inductance component of the antenna 2 becomes large, so that the resonant frequency shifts to the low frequency side.

[0074] 21, the communication unit 3 is preferably arranged so as not to reach a region in the vicinity of the second connecting conductor 221 where the magnetic field between the second connecting conductor 221 and the second connecting conductor 222 is weak. In this embodiment, the communication unit 3 is preferably arranged so that its short side direction is parallel to the short side direction of the first conductor 10.

[0075] [Second embodiment] A configuration example of a wireless communication device according to the second embodiment will be described with reference to Fig. 22 and Fig. 23. Fig. 22 is a diagram showing a configuration example of a wireless communication device according to the second embodiment. Fig. 23 is a diagram showing a configuration example of an upper conductor of an antenna according to the second embodiment. Fig. 22 shows a cross-sectional view taken along II-II in Fig. 23. Note that the configuration of the lower conductor of the antenna according to the second embodiment is the same as the configuration of the first conductor 10 shown in Fig. 3, and therefore description thereof will be omitted.

[0076] As shown in FIGS. 22 and 23, a wireless communication device 1A includes an antenna 2A and a communication unit 3.

[0077] The antenna 2A includes a first conductor 10, a second conductor 12A, a third conductor 14A, a fourth conductor 16A, a first connecting conductor 201, a first connecting conductor 202, a second connecting conductor 221, a second connecting conductor 222, a power supply conductor 24, and a housing 26.

[0078] The second embodiment differs from the wireless communication device 1 shown in Fig. 1 in that the communication unit 3 is disposed on the second conductor 12A or the third conductor 14A among the upper surface conductors inside the antenna 2A. In the examples shown in Figs. 22 and 23, the communication unit 3 is disposed on the second conductor 12A. Specifically, the communication unit 3 is disposed on the second conductor 12A near the first connection conductor 201 with the longitudinal direction of the communication unit 3 parallel to the longitudinal direction of the antenna 2A. The communication unit 3 may be disposed on the third conductor 14A.

[0079] The second conductor 12A is longer in the X-axis direction than the second conductor 12 shown in Fig. 2. Specifically, the second conductor 12A is formed long in the X-axis direction to such an extent that the communication unit 3 can be disposed in the vicinity of the first conductor 10 with its longitudinal direction parallel to the longitudinal direction of the antenna 2A.

[0080] The third conductor 14A is longer in the X-axis direction than the third conductor 14 shown in Fig. 2. Specifically, the third conductor 14A is formed long in the X-axis direction to such an extent that the communication unit 3 can be disposed in the vicinity of the second conductor 12 with its longitudinal direction parallel to the longitudinal direction of the antenna 2A.

[0081] The length of the second conductors 12A in the X-axis direction is the same as the length of the third conductors 14A in the X-axis direction.

[0082] The fourth conductor 16A is formed so that its length in the X-axis direction is shorter than that of the fourth conductor 16 shown in Fig. 2 by the amount that the second conductor 12A and the third conductor 14A are formed so as to be longer than the second conductor 12 and the third conductor 14 shown in Fig. 2. In the example shown in Figs. 22 and 23, the length of the fourth conductor 16A in the X-axis direction is shorter than the lengths of the second conductor 12A and the third conductor 14A.

[0083] As shown in FIG. 23, in the second embodiment, the power feed point P1 is provided on the second conductor 12A. A clearance C is provided between the power feed point P1 and the second conductor 12A. One end of the power feed conductor 24 is connected to the power feed point P1, and the other end is connected to the first conductor 10. Since the clearance C is provided between the power feed point P1 and the second conductor 12A, the power feed conductor 24 is not connected to the second conductor 12A. The power feed point P1 may be provided on either the third conductor 14A or the fourth conductor 16A via a gap. That is, in the second embodiment, one end of the power feed conductor 24 may be connected to the power feed point P1 provided on either the second conductor 12A, the third conductor 14A, or the fourth conductor 16A via a gap, and the other end may be connected to the first conductor 10 facing the power feed point P1.

[0084] The radiation efficiency of the antenna according to the second embodiment will be described with reference to Fig. 24. Fig. 24 is a diagram for explaining the radiation efficiency of the antenna according to the second embodiment.

[0085] In FIG. 24, the horizontal axis indicates frequency [MHz], and the vertical axis indicates total radiation efficiency [dB]. Graph G10 indicates the total radiation efficiency of the antenna 2A when the communication unit 3 is not arranged. Graph G11 indicates the radiation efficiency of the antenna 2A when the communication unit 3 is arranged in the first conductor 10 near the first connecting conductor 201 with its longitudinal direction parallel to the longitudinal direction of the antenna 2A as shown in FIG. 25. In FIG. 25, the feed point P1 is provided in the first conductor 10 via a clearance C. In the example shown in FIG. 25, the feed point P1 is once connected to the feed point P1, and the other end is connected to the second conductor 12A facing the feed point P1. Graph G12 indicates the radiation efficiency of the antenna 2A when the communication unit 3 is arranged in the second conductor 12A near the first connecting conductor 201 with its longitudinal direction parallel to the longitudinal direction of the antenna 2A.

[0086] As shown in graph G10, the resonant frequency of the antenna 2A is about 850 MHz when the communication unit 3 is not disposed. The overall radiation efficiency at the resonant frequency of graph G10 is about -3 dB, which is favorable.

[0087] As shown in graph G11, the resonant frequency of the antenna 2A is about 850 MHz when the communication unit 3 is arranged in the first conductor 10 in the vicinity of the first connecting conductor 201 with its longitudinal direction parallel to that of the antenna 2A. The overall radiation efficiency at the resonant frequency of graph G11 is about -3 dB, which is favorable.

[0088] As shown in graph G12, in the second conductor 12A, when the communication unit 3 is disposed in the vicinity of the first connecting conductor 201 with its longitudinal direction parallel to that of the antenna 2A, the resonant frequency of the antenna 2A is about 850 MHz. The overall radiation efficiency at the resonant frequency of graph G12 is about -3 dB, which is favorable.

[0089] The resonance frequency and radiation characteristic at the resonance frequency of the graph G11 and the graph G12 are almost the same as the resonance frequency and radiation characteristic at the resonance frequency of the graph G10. Also, the resonance frequency of the graph G11 and the graph G12 are almost the same as the resonance frequency of the graph G10. The radiation characteristic of the graph G11 and the graph G12 are almost the same in the range of 700 MHz to 950 MHz. That is, the radiation characteristic in the range of 700 MHz to 950 MHz is almost the same when the communication unit 3 is disposed on the first conductor 10 and when the communication unit 3 is disposed on the second conductor 12A. That is, therefore, in the second embodiment, the communication unit 3 can be disposed on any one of the first conductor 10, the second conductor 12A, and the third conductor 14A.

[0090] In the second embodiment, the communication unit 3 may be disposed on the second conductor 12A or the third conductor 14A. From the viewpoint of routing the power feed line 5, it is preferable to dispose the communication unit 3 on either the second conductor 12A or the third conductor 14A, whichever is closer to the power feed point P1. In the example shown in Fig. 22 and Fig. 23, it is preferable to dispose the communication unit 3 on the second conductor 12A.

[0091] [Modification of the second embodiment] Next, a modification of the second embodiment of the present disclosure will be described.

[0092] In the second embodiment, the communication unit 3 is described as being mounted on the second conductor 12A or the third conductor 14A. In this case, the bottom conductor may be formed of a single metal plate or the like.

[0093] A configuration example of a bottom conductor according to a modification of the second embodiment will be described with reference to Fig. 26. Fig. 26 is a diagram showing a configuration example of a bottom conductor according to a modification of the second embodiment.

[0094] 26, the bottom conductor 40 includes a first conductor 10A, a first connecting conductor 20A1, a first connecting conductor 20A2, a second connecting conductor 22A1, a second connecting conductor 22A2, and a power supply conductor 24A. The bottom conductor 40 is a metal plate in which the first conductor 10A, the first connecting conductor 20A1, the first connecting conductor 20A2, the second connecting conductor 22A1, the second connecting conductor 22A2, and the power supply conductor 24 are integrally formed.

[0095] The first connecting conductor 20A1 and the first connecting conductor 20A2 are bent toward the X-axis direction so as to be parallel to the Z-axis direction, thereby forming a configuration in which the first conductor 10A is connected to a second conductor (not shown).

[0096] The second connecting conductor 22A1, the second connecting conductor 22A2, and the power supply conductor 24A are bent toward the -X-axis direction so as to be parallel to the Z-axis direction, thereby connecting the first conductor 10A and a fourth conductor (not shown).

[0097] As shown in Fig. 26, by integrating the first conductor 10A, the first connecting conductor 20A1, the first connecting conductor 20A2, the second connecting conductor 22A1, the second connecting conductor 22A2, and the power supply conductor 24A, it becomes easy to manufacture the antenna 2A shown in Fig. 22. This makes it possible to reduce the manufacturing cost of the antenna 2A.

[0098] [Other embodiments] The antenna 2 according to the first embodiment and the antenna 2A according to the second embodiment may be mounted on various structures. Examples of the structures include containers and pallets used for transporting various items. In this case, the antenna 2 or the antenna 2A transmits and receives various information related to the items stored in the container to and from a server device or the like. The structure may be, for example, a delivery box that stores parcels.

[0099] Although the embodiments of the present invention have been described above, the present invention is not limited to the contents of these embodiments. 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 appropriately combined. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the spirit of the above-described embodiments. [Explanation of symbols]

[0100] 1. Wireless communication devices 2 Antennas 3 Communication Unit 4 Metallic parts 5 Power line 10 First Conductor 12 Second Conductor 14 Third Conductor 16 4th Conductor 20 First connecting conductor 22 Second connecting conductor 24 Power Supply Conductor 26 Case 30 Memory 32 Controller 34 Sensors 36 Battery 40 Bottom conductor

Claims

1. The antenna, a communication unit disposed inside the antenna and configured to wirelessly communicate with an external device via the antenna; Including, The antenna is A first conductor extending in a first surface direction; a second conductor extending in the first plane direction and connected to a first end of the first conductor in a first direction; a third conductor that faces a second end of the first conductor in the first direction, is connected to the first conductor, and extends in the first plane direction aligned with the second conductor in the first direction; At least one fourth conductor extending in the first surface direction and positioned apart from the second conductor and the third conductor in the first direction; a first connection conductor having one end connected to the first conductor and the other end connected to the second conductor; a second connection conductor having one end connected to the first conductor and the other end connected to the third conductor; a power supply conductor having one end connected to a power supply point and the other end connected to one of the first conductor, the second conductor, the third conductor, and the fourth conductor that faces the power supply point; The communication unit is disposed at a position inside the antenna where the magnetic field strength is relatively strong. Wireless communication device.

2. 2. The wireless communication device according to claim 1, A wireless communication device, wherein the communication unit is arranged in the first conductor near the first connecting conductor or the second connecting conductor.

3. 3. The wireless communication device according to claim 2, A wireless communication device, wherein the communication unit is arranged in the first conductor near one of the first connecting conductor and the second connecting conductor that is farther from the power supply point.

4. 3. The wireless communication device according to claim 2, A wireless communication device, wherein the communication unit is arranged in the first conductor near one of the first connecting conductor and the second connecting conductor, which is closer to the power supply point.

5. 2. The wireless communication device according to claim 1, A wireless communication device, wherein the communication unit is arranged in the second conductor or the third conductor in the vicinity of the first connecting conductor or the second connecting conductor.

6. 6. The wireless communication device according to claim 5, A wireless communication device, wherein the communication unit is arranged in the second conductor or the third conductor near either the first connecting conductor or the second connecting conductor, whichever is closer to the power supply point.

7. 7. A wireless communication device according to claim 1, A wireless communication device, wherein the antenna has a length in a second direction perpendicular to the first direction in the first surface direction that is shorter than the length in the first direction.

8. 7. A wireless communication device according to claim 1, A wireless communication device, wherein the first conductor, the first connecting conductor, the second connecting conductor, and the power supply conductor are formed from a single metal member.

9. 7. A wireless communication device according to claim 1, A wireless communication device, wherein the antenna is mounted on a conductive article on the first conductor side.

10. A structure comprising a wireless communication device according to any one of claims 1 to 6.

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