Radio communication device and communication circuit board

Abstract

This radio communication device comprises: a plurality of array antennas each having an antenna board and a plurality of radiating elements mounted on an antenna surface of the antenna board; and a communication circuit board which includes a circuit board body including a first surface, and a planar conductor provided on a surface of the circuit board body opposite to the first surface, the communication circuit board performing radio communication using the plurality of array antennas. Each of the plurality of array antennas is provided on the first surface such that a plane including the antenna surface does not intersect the conductor, the antenna surface has an inclination angle with respect to the first surface, and a surface of the antenna board opposite to the antenna surface is closer to the first surface than is the antenna surface.

Description

Wireless communication device and communication circuit board

[0001] This disclosure relates to a wireless communication device and a communication circuit board. This disclosure claims priority to Japanese Application No. 2023-104323, filed on June 26, 2023, and incorporates by reference all of the contents of said Japanese application.

[0002] In fifth-generation mobile communication systems (hereinafter also referred to as 5G), wireless communication is performed using millimeter waves or quasi-millimeter waves, resulting in large propagation losses. Therefore, wireless communication devices such as base stations and terminals that make up the system perform beamforming. To perform beamforming, the wireless communication devices are equipped with array antennas that include multiple radiating elements. By using beamforming, base stations and mobile terminals can improve gain by directing the beam (antenna orientation) in a specific direction (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2020-136807

[0004] The wireless communication device includes an antenna substrate, a plurality of array antennas each having a plurality of radiating elements mounted on an antenna surface of the antenna substrate, and a communication circuit board including a circuit board main body having a first surface and a flat conductor provided on a surface of the circuit board main body opposite to the first surface, the communication circuit board performing wireless communication using the plurality of array antennas. Each of the plurality of array antennas is provided on the first surface so that a plane including the antenna surface does not intersect with the conductor, the antenna surface has an inclination angle with respect to the first surface, and the surface of the antenna substrate opposite to the antenna surface is closer to the first surface than the antenna surface.

[0005] FIG. 1A is a perspective view showing an example of a wireless communication device according to the first embodiment. FIG. 1B is a perspective view showing an example of a wireless communication device according to a modified example of the first embodiment. FIG. 2 is a front view and a side view of a communication circuit board. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. FIG. 4 is an enlarged view of a tip of a support column. FIG. 5 is a front view of a communication circuit board according to a second embodiment. FIG. 6 is a cross-sectional view of a communication circuit board according to a third embodiment. FIG. 7A is a diagram showing an example of results obtained by simulation of a beam pattern of a model of a wireless communication device having two array antennas. FIG. 7B is a diagram showing the spherical coverage of FIG. 7A. FIG. 8A is a diagram showing an example of results obtained by simulation of a beam pattern of a model of a wireless communication device having four array antennas. FIG. 8B is a diagram showing the spherical coverage of FIG. 8A. FIG. 9A is a graph showing test results using a model of the wireless communication device according to the first embodiment. FIG. 9B is a graph showing test results using a model of the wireless communication device according to the second embodiment.

[0006] [Problem to be Solved by the Present Disclosure] The specifications of the 3GPP (Third Generation Partnership Project) (registered trademark), a project related to the standardization of mobile communication systems, stipulate the transmission and reception performance of 5G wireless communication devices. The specifications require that the wireless communication device satisfy spherical coverage requirements, such as obtaining predetermined transmission and reception characteristics in 50% or more of the spherical coverage of the wireless communication device, in order to guarantee a constant communication quality regardless of the orientation of the wireless communication device.

[0007] The range that can be covered by a beam from an array antenna is limited. Therefore, in order to satisfy the spherical coverage requirements required by 3GPP, a wireless communication device is provided with multiple array antennas. When a wireless communication device has multiple array antennas, the area that each array antenna should cover in the spherical coverage becomes smaller, making it relatively easy to satisfy the requirements required by 3GPP.

[0008] When a wireless communication device has multiple array antennas, it is necessary to secure an installation area for the array antennas on the circuit board of the wireless communication device, and this increases the manufacturing cost and power consumption of the wireless communication device. Reducing the number of array antennas not only fails to meet the requirements for spherical coverage, but also may impair the required transmission and reception performance.

[0009] Effect of the Present Disclosure According to the present disclosure, it is possible to reduce the number of array antennas while maintaining the required transmission and reception performance.

[0010] First, the contents of the embodiment will be listed and explained.

[0011] (1) A wireless communication device according to an embodiment of the present disclosure includes an antenna substrate, a plurality of array antennas each having a plurality of radiating elements mounted on an antenna surface of the antenna substrate, and a communication circuit board including a circuit board main body including a first surface and a flat conductor provided on a surface of the circuit board main body opposite to the first surface, the communication circuit board performing wireless communication using the plurality of array antennas. Each of the plurality of array antennas is provided on the first surface so that a plane including the antenna surface does not intersect with the conductor, the antenna surface is inclined relative to the first surface, and the surface of the antenna substrate opposite to the antenna surface is closer to the first surface than the antenna surface.

[0012] According to the above configuration, since the plane including the antenna surface does not intersect with the conductor, radio waves radiated from the multiple radiating elements of the array antenna are prevented from being blocked by the conductor, and a wider range in which the required gain can be obtained by a single array antenna can be ensured. Therefore, when multiple array antennas are appropriately arranged so as to ensure the gain required by the spherical coverage requirements and the gain in the required area, the number of array antennas can be reduced. In other words, the required gain can be ensured with a smaller number of array antennas. According to this embodiment, the number of array antennas can be reduced while maintaining the required transmission and reception performance.

[0013] (2) In the wireless communication device of (1), the normals of the antenna planes may be in different directions. In this case, the directions of the antenna planes of the array antennas can be distributed in multiple directions, allowing for more appropriate placement of the array antennas.

[0014] (3) In the wireless communication device of (1) or (2) above, the tilt angle may be 40 degrees or more and 60 degrees or less. If the tilt angle is less than 40 degrees, the orientation of the antenna plane will deviate significantly from a direction parallel to the first surface, which may reduce the gain in the direction parallel to the first surface. Also, if the tilt angle is greater than 60 degrees, the orientation of the antenna plane will deviate significantly from a direction normal to the first surface, which may reduce the gain in the direction normal to the first surface. By setting the tilt angle to 40 degrees or more and 60 degrees or less, the orientation of the array antenna can be appropriately set.

[0015] (4) In the wireless communication device according to any one of (1) to (3), the tilt angles of the array antennas may be equal. In this case, the orientation of the array antennas can be set uniformly in each direction.

[0016] (5) In the wireless communication device according to any one of (1) to (4), the device may further include a plurality of support columns protruding from the first surface and supporting the plurality of array antennas on the first surface, each of the plurality of support columns being provided on a surface opposite the antenna surface and having an inclined surface for supporting the array antenna. In this case, the plurality of array antennas can be properly supported on the first surface.

[0017] (6) The wireless communication device of (5) may further include a metal plate provided on the conductor and including the plurality of support posts, the plurality of support posts penetrating the circuit board body. In this case, the metal plate is provided in contact with the communication circuit board, thereby functioning as a heat sink for dissipating heat generated in the communication circuit board. Furthermore, since the support posts are connected to the metal plate, heat generated in the array antenna is also transferred to the metal plate, allowing the heat to be dissipated by the metal plate. This makes it possible to suppress temperature rise in the array antenna.

[0018] (7) In the wireless communication device of (6), the metal plate may have heat dissipation fins. In this case, heat propagating to the metal plate can be efficiently dissipated.

[0019] (8) Another embodiment of the present disclosure is a communication circuit board. The communication circuit board includes an antenna board, a plurality of array antennas each having a plurality of radiating elements mounted on an antenna surface of the antenna board, and a circuit board main body including a board surface and a flat conductor provided on an opposite surface to the board surface, and configured to perform wireless communication using the plurality of array antennas. Each of the plurality of array antennas is provided on the board surface so that a plane including the antenna surface does not intersect with the conductor, the antenna surface is inclined relative to the board surface of the circuit board main body, and the opposite surface of the antenna board to the antenna surface is closer to the board surface than the antenna surface.

[0020] [Details of the Embodiments] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that at least a portion of each embodiment described below may be combined in any manner. [First Embodiment] Refer to FIG. 1A. In FIG. 1A, a wireless communication device 1 is a wireless device installed, for example, in a factory or an office. The wireless communication device 1 has a function of performing wireless communication compliant with 5G with surrounding terminal devices. The wireless communication device 1 is used as a wireless slave station (RU: Radio Unit) in 5G.

[0021] In the following description, a three-dimensional Cartesian coordinate system may be used in each figure. Also, as shown in FIG. 1A , one direction of the X axis is the X1 direction, and the opposite direction of the X1 direction is the X2 direction. One direction of the Y axis is the Y1 direction, and the opposite direction of the Y1 direction is the Y2 direction. One direction of the Z axis is the Z1 direction, and the opposite direction of the Z1 direction is the Z2 direction. In this embodiment, as shown in FIG. 1A , the X axis is an axis extending from front to back of the wireless communication device 1. The Y axis is an axis extending from left to right of the wireless communication device 1. The Z axis is an axis extending from top to bottom of the wireless communication device 1. The X1 direction is a direction pointing forward. The X2 direction is a direction pointing backward. The Y1 direction is a direction pointing right. The Y2 direction is a direction pointing left. The Z1 direction is a direction pointing upward. The Z2 direction is a direction pointing downward.

[0022] The wireless communication device 1 includes a plurality of array antennas 2, a communication circuit board 4, a plurality of support posts 6, and a housing 8. The housing 8 is a box formed of resin or the like, and houses the plurality of array antennas 2 and the communication circuit board 4. The communication circuit board 4 is a rectangular board having a long side parallel to the Y axis and a short side parallel to the Z axis.

[0023] Please refer to Figure 2. The diagram on the left side of Figure 2 is a front view of the communication circuit board 4 when viewed in the X1 direction. The diagram on the right side of Figure 2 is a side view of the communication circuit board 4 when viewed in the Y1 direction. A communication processing circuit (not shown) is mounted on the communication circuit board 4. The communication processing circuit includes a baseband circuit that performs baseband processing, a transmission / reception circuit that performs signal modulation / demodulation, etc. The communication circuit board 4 also has the function of controlling beams formed by the multiple array antennas 2. The communication circuit board 4 also has the function of performing wireless communication using the multiple array antennas 2.

[0024] As shown in FIGS. 1A and 2, the first surface 4a of the communication circuit board 4 is a surface perpendicular to the X1 direction. The second surface 4b of the communication circuit board 4 is a surface facing the X2 direction. The first surface 4a and the second surface 4b are surfaces parallel to the YZ plane. The wireless communication device 1 is installed, for example, on a wall surface inside a building. In this case, the communication circuit board 4 is positioned so that the second surface 4b faces the wall surface. Therefore, the first surface 4a faces the opposite side of the wall surface.

[0025] A plurality of array antennas 2 (two array antennas 2 in the illustrated example) are provided on the first surface 4a. The two array antennas 2 are provided near the upper long side of the first surface 4a. One of the two array antennas 2 is provided near the right short side of the first surface 4a. The other of the two array antennas 2 is provided near the left short side of the first surface 4a.

[0026] Each of the two array antennas 2 has an antenna substrate 10 and a plurality of radiating elements 12. The plurality of array antennas 2 and the communication circuit board 4 are connected to each other by coaxial cables or the like. Signals transmitted and received by the plurality of array antennas 2 are exchanged with the communication circuit board 4 via the coaxial cables.

[0027] The antenna substrate 10 is a rectangular plate. The antenna substrate 10 has an antenna surface 10a. A plurality of radiating elements 12 are mounted on the antenna surface 10a. Of the plurality of radiating elements 12 (eight in the illustrated example), four are arranged along the long side of the antenna surface 10a, and two are arranged along the short side.

[0028] The array antenna 2 has an amplifier circuit and a phase shifter (neither of which are shown) corresponding to each of the eight radiating elements 12. The amplifier circuit and the phase shifter are mounted on the antenna board 10. The amplifier circuit amplifies the signals transmitted and received by the radiating elements 12. The phase shifter adjusts the phase of the signals transmitted and received by the radiating elements 12. The phases of the signals transmitted and received by the eight radiating elements 12 are each adjusted independently by the phase shifter. This enables the array antenna 2 to perform beamforming. The array antenna 2 can adjust the beam direction within a predetermined range around the antenna surface 10a. The beam direction of the array antenna 2 is controlled by the communication circuit board 4.

[0029] The plurality of support pillars 6 support the plurality of array antennas 2 on the first surface 4a. The plurality of support pillars 6 (two support pillars 6 in the illustrated example) support the array antenna 2 so that the antenna surface 10a is inclined with respect to the first surface 4a.

[0030] Referring to FIG. 3 , the communication circuit board 4 includes a circuit board main body 14 and a ground conductor plate 16. The circuit board main body 14 is formed of polyimide resin, epoxy resin, PPE resin, fluororesin, or the like. The above-mentioned communication processing circuit and the like are mounted on the third surface 14a of the circuit board main body 14. The ground conductor plate 16 is mounted on the fourth surface 14b of the circuit board main body 14. The ground conductor plate 16 is a conductor pattern made of copper or the like. The ground conductor plate 16 is disposed parallel to the first surface 4a. The ground conductor plate 16 is connected to a ground line (not shown) and is grounded. Note that while the communication circuit board 4 is shown as a single-layer board here, the communication circuit board 4 may also be a multi-layer board.

[0031] The antenna surface 10a of the array antenna 2 is inclined with respect to the first surface 4a. The long side of the antenna surface 10a is inclined with respect to the first surface 4a. The angle θ of inclination between the first surface 4a and the antenna surface 10a (hereinafter also referred to as the inclination angle) is greater than 0 degrees and less than 90 degrees. In other words, by setting the inclination angle in this manner, the antenna surface 10a can be reliably inclined with respect to the first surface 4a. In this embodiment, the inclination angle is set to 45 degrees.

[0032] The plane P1 is a plane that includes the antenna plane 10a. Like the first plane 4a, the plane P1 is a plane that is orthogonal to the XY plane. Therefore, in Figure 3, the plane P1 is shown by a dashed line. The plane P1 does not intersect with the first plane 4a. Therefore, the plane P1 does not intersect with the ground conductor plate 16 either.

[0033] If the plane P1 intersects with the ground conductor plate 16, an edge of the ground conductor plate 16 may protrude from the plane P1. This edge may block radio waves radiated from the antenna surface 10a (radiating element 12). In contrast, in this embodiment, the plane P1 including the antenna surface 10a does not intersect with the ground conductor plate 16, so the edge of the ground conductor plate 16 does not protrude from the plane P1. This prevents radio waves radiated from the multiple radiating elements 12 of the array antenna 2 from being blocked by the ground conductor plate 16, ensuring a wider range in which the required gain can be obtained by a single array antenna 2. Therefore, when multiple array antennas are appropriately arranged to ensure the gain required by the spherical coverage requirements and the gain in the required area, the number of array antennas can be reduced. In other words, the required gain can be ensured with a smaller number of array antennas 2.

[0034] In the wireless communication device 1 installed on a wall surface such that the communication circuit board 4 faces the wall surface, as in this embodiment, gain is required at least in the front direction of the first surface 4a (the normal direction of the first surface 4a: the X1 direction). To provide gain in the required direction, a larger number of array antennas can be arranged. If gain in the front direction is required, an array antenna facing the front direction can be added. However, in this embodiment, by appropriately arranging two array antennas 2, it is possible to provide a predetermined gain in an area of ​​50% or more of the spherical coverage while also obtaining the required gain in the front direction, which is the required area. As such, according to this embodiment, the number of array antennas 2 can be reduced while maintaining the required transmission and reception performance.

[0035] The imaginary vertical lines L11 and L12, indicated by dashed lines in Figures 2 and 3, extend in different directions. The imaginary vertical line L11 is a vertical line extending from the center of the antenna surface 10a of the right-side array antenna 2. The imaginary vertical line L11 is also a normal to the antenna surface 10a arranged on the right. The imaginary vertical line L12 is a vertical line extending from the center of the antenna surface 10a of the left-side array antenna 2. The imaginary vertical line L12 is also a normal to the antenna surface 10a arranged on the left. As shown in Figure 2, the imaginary vertical lines L11 and L12 extend in different directions in a plan view of the first surface 4a. More specifically, the imaginary vertical lines L11 and L12 extend in opposite directions along the Y-axis in a plan view of the first surface 4a. This allows the orientation of the antenna surfaces 10a of the multiple array antennas 2 to be dispersed in more directions, allowing the array antennas 2 to be more appropriately arranged.

[0036] The tilt angle may be 40 degrees or more and 60 degrees or less. If the tilt angle is less than 40 degrees, the orientation of the array antenna 2 will deviate significantly from the Y1 and Y2 directions parallel to the first surface 4a, which may result in a decrease in gain in the Y1 and Y2 directions. If the tilt angle is greater than 60 degrees, the orientation of the array antenna 2 will deviate significantly from the normal direction of the first surface 4a, which may result in a decrease in gain in the normal direction of the first surface 4a. By setting the tilt angle to 40 degrees or more and 60 degrees or less, the orientation of the array antenna 2 can be appropriately set. The tilt angle may be in the range of 40 degrees or more and 50 degrees or less.

[0037] In this embodiment, the tilt angle of the right array antenna 2 is equal to the tilt angle of the left array antenna 2. Therefore, the orientations of the array antennas 2 can be set uniformly.

[0038] As shown in FIG. 3 , the two support posts 6 are fixed to the communication circuit board 4 by being inserted into the through passages 17. The through passages 17 are holes that penetrate the communication circuit board 4 and the ground conductor plate 16 along the X-axis. The through passages 17 penetrate between the first surface 4a and the second surface 4b. Note that the through passages 17 may be configured as notches that are recessed into the side surface of the communication circuit board 4 from the first surface 4a to the second surface 4b. The tip portions 6a of the support posts 6 protrude from the first surface 4a. The bottom end surfaces 6b of the support posts 6 are flush with the outer surface 16a of the ground conductor plate 16. The array antenna 2 is fixed to the tip portions 6a of the support posts 6.

[0039] Please refer to Figure 4. As shown in Figure 4, the support 6 is a quadrangular prism-shaped member. The support 6 is formed of, for example, resin or metal. The tip portion 6a has a tip surface 18 and an inclined surface 20. The tip surface 18 is a surface parallel to the first surface 4a. The inclined surface 20 is inclined so as to approach the first surface 4a as it progresses in the Y2 direction from the edge 18a of the tip surface 18. The angle of inclination between the first surface 4a and the inclined surface 20 is equal to the angle of inclination between the first surface 4a and the antenna surface 10a. The array antenna 2 is held by the inclined surface 20.

[0040] The inclined surface 20 and the back surface 10b of the antenna substrate 10 face each other. The back surface 10b is the surface behind the antenna surface 10a and is parallel to the antenna surface 10a. The antenna substrate 10 is fixed to the tip 6a of the support 6 with the back surface 10b and the inclined surface 20 facing each other. Therefore, the inclination angle is determined by the angle of inclination between the inclined surface 20 and the first surface 4a. The antenna substrate 10 may be fixed to the support 6 by a fixing member. In this case, the fixing member fixes the antenna substrate 10 and the support 6 with the back surface 10b and the inclined surface 20 abutting each other. The antenna substrate 10 may be fixed to the support 6 by an adhesive layer interposed between the back surface 10b and the inclined surface 20. In this case, the adhesive layer may have high thermal conductivity. The inclined surface 20 holds the array antenna 2 so that the plane P1 does not intersect with the ground conductor plate 16. In this embodiment, by providing the support 6 having the inclined surface 20, the array antenna 2 can be properly supported on the first surface 4a.

[0041] 1B , the wireless communication device 1 includes an antenna-equipped communication circuit board 3. The antenna-equipped communication circuit board 3 includes a plurality of array antennas 2, a communication circuit board 4, and a plurality of support posts 6.

[0042] [Second Embodiment] Please refer to Figure 5. This embodiment differs from the first embodiment in that it has four array antennas 2. The four array antennas 2 are provided on the first surface 4a. The four array antennas 2 are provided near each side of the first surface 4a. The four array antennas 2 are provided near the center of each side.

[0043] In this embodiment, too, the four array antennas 2 are each arranged on the first surface 4a so that the plane P1 including the antenna surface 10a does not intersect with the ground conductor plate 16 and the antenna surface 10a is inclined with respect to the first surface 4a.

[0044] The imaginary vertical lines L13, L14, L15, and L16 extend in different directions from one another. The imaginary vertical line L13 is a vertical line extending from the center of the antenna surface 10a of the right-side array antenna 2. The imaginary vertical line L13 is also a normal to the antenna surface 10a arranged on the right. The imaginary vertical line L14 is a vertical line extending from the center of the antenna surface 10a of the upper array antenna 2. The imaginary vertical line L14 is also a normal to the antenna surface 10a arranged on the upper side. The imaginary vertical line L15 is a vertical line extending from the center of the antenna surface 10a of the left-side array antenna 2. The imaginary vertical line L15 is also a normal to the antenna surface 10a arranged on the left side. The imaginary vertical line L16 is a vertical line extending from the center of the antenna surface 10a of the lower array antenna 2. The imaginary vertical line L16 is also a normal to the antenna surface 10a arranged on the lower side.

[0045] In this case, the directions in which the antenna surfaces 10a of the multiple array antennas 2 face can be dispersed in multiple directions, allowing the array antennas 2 to be arranged more appropriately.

[0046] Third Embodiment Referring to Fig. 6, this embodiment differs from the first embodiment in that the communication circuit board 4 has a metal plate 24.

[0047] In addition to the circuit board main body 14 and the ground conductor plate 16, the communication circuit board 4 of this embodiment also includes a metal plate 24. The metal plate 24 is a plate-shaped member formed of an electrical conductor such as copper, a copper alloy, or an aluminum alloy. The metal plate 24 is superimposed on the circuit board main body 14 via the ground conductor plate 16. The fifth surface 24a of the metal plate 24 abuts against the outer surface 16a of the ground conductor plate 16. Therefore, if the metal plate 24 is grounded, there is no need to connect the ground conductor plate 16 to a ground wire. Alternatively, the ground conductor plate 16 may be omitted and the fifth surface 24a may be abutted against the fourth surface 14b, allowing the metal plate 24 to function as the ground conductor plate.

[0048] Furthermore, the metal plate 24 functions as a heat sink for dissipating heat generated in the communication circuit board 4. A large number of heat dissipation fins 26 are provided on the sixth surface 24b of the metal plate 24. Therefore, the metal plate 24 can efficiently dissipate heat propagating to the metal plate 24.

[0049] The two support posts 6 in this embodiment are formed from the same material as the metal plate 24. In other words, the two support posts 6 are made of metal. By being inserted into the through-passages 17, the two support posts 6 penetrate the circuit board main body 14 and the ground conductor plate 16 and are connected to the fifth surface 24a of the metal plate 24. The two support posts 6 and the metal plate 24 are formed integrally.

[0050] The inclined surfaces 20 of the two pillars 6 each hold the antenna substrate 10 so as to allow thermal conduction between them. Therefore, heat generated in the array antenna 2 is conducted to the pillars 6. Furthermore, since the pillars 6 are connected to the metal plate 24, the heat conducted to the pillars 6 is further conducted to the metal plate 24. In this manner, in this embodiment, since the pillars 6 are connected to the metal plate 24, the heat generated in the array antenna 2 is also conducted to the metal plate 24 and can be dissipated by the metal plate 24. This makes it possible to suppress a rise in temperature of the array antenna 2.

[0051] [Verification Test] Next, a verification test conducted on the effects of the wireless communication device 1 will be described. As a test method, a model of the wireless communication device 1 according to the first embodiment (two array antennas 2) and the second embodiment (four array antennas 2) was constructed, and the spherical coverage gain and the gain in the front direction (X1 direction) of the wireless communication device 1 were calculated by computer simulation using the model. Furthermore, when calculating the spherical coverage gain and the gain in the front direction, the angle θ in the model was changed to determine the relationship between the spherical coverage gain, the gain in the front direction, and the tilt angle. The model was constructed to satisfy the condition that the plane including the antenna surface does not intersect with the ground conductor plate, regardless of changes in the tilt angle.

[0052] Please refer to Figures 7A and 7B. The beam pattern shown in Figure 7A is a beam pattern when the beam is directed in a direction along a virtual vertical line of the array antenna 2. In Figure 7A, it can be seen that beams are formed in two directions.

[0053] Please refer to Figures 8A and 8B. The beam pattern shown in Figure 8A is a beam pattern when the beam is directed in a direction along a virtual vertical line of the array antenna 2. It can be seen from Figure 8A that beams are formed in four directions. Such three-dimensional beam patterns were obtained for each of the model of the first embodiment and the model of the second embodiment, and the spherical coverage gain and the gain in the front direction of the wireless communication device 1 were obtained.

[0054] Please refer to FIG. 9A. In FIG. 9A, the horizontal axis represents the tilt angle (unit: degrees). The vertical axis represents EIRP (Equivalent Isotropic Radiation Power). Also, in FIG. 9A, a line G1 (dashed line) represents the EIRP in the front direction. A line G2 (solid line) represents the EIRP when the CDF (Cumulative Distribution Function) is 50%. The EIRP when the CDF is 50% represents the EIRP (dBm) when the CDF is 50% when the EIRP is expressed as a CDF. Therefore, it can be said that the EIRP when the CDF is 50% (line G2) represents the gain when the spherical coverage is 50%.

[0055] In Figure 9A, in line G1, the EIRP is maximized when the tilt angle is 0 degrees and gradually decreases as the tilt angle increases. This is because, at a tilt angle of 0 degrees, the antenna surface 10a is parallel to the first surface 4a and faces forward. In line G2, conversely, the EIRP is minimized when the tilt angle is 0 degrees and gradually increases as the tilt angle increases. Furthermore, the EIRP converges to a constant value (approximately 17 dBm) when the tilt angle is around 60 degrees. The decrease in EIRP in the tilt angle range from 0 degrees to 60 degrees is likely due to the overlapping of the beams of the two array antennas 2, resulting in signal loss. The EIRP converges to a constant value when the tilt angle is 60 degrees or greater is likely due to the beams of the two array antennas 2 being formed to their maximum extent without any interference. When the plane including the antenna surface intersects with the ground conductor plate, as the inclination angle of the line G2 increases and the EIRP exceeds a predetermined value, the EIRP gradually decreases as shown by the two-dot chain line G21 in Fig. 7A. This is because the beam (radio wave) is blocked by the ground conductor plate 16.

[0056] Please refer to Figure 9B. In Figure 9B, line G3 shows the EIRP in the front direction. Line G4 shows the EIRP when the CDF is 50%. In Figure 9B, line G3 shows the maximum value when the angle θ is 0 degrees, and the value gradually decreases as the angle θ increases. Conversely, line G4 shows the minimum EIRP when the angle θ is 0 degrees, and the value gradually increases as the angle θ increases. Furthermore, the EIRP converges to a constant value (approximately 20 dBm) when the angle θ is around 60 degrees. Figure 9B also shows approximately the same trend as Figure 9A.

[0057] 9A and 9B, it can be seen that the tilt angle range in which both the EIRP in the front direction and the EIRP when the CDF is 50% are balanced and high is 40 degrees or more and 60 degrees or less. Note that the EIRP when the CDF is 50% in the tilt angle range of 40 degrees or more and 60 degrees or less satisfies the spherical coverage requirements of 3GPP, and the EIRP in the front direction has a gain sufficient for wireless communication. Thus, it can be seen that even with a small number of array antennas 2, such as two or four, the required transmission and reception performance can be maintained according to this embodiment.

[0058] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the meaning described above, and is intended to include meanings equivalent to the claims and all modifications within the scope thereof.

[0059] REFERENCE SIGNS LIST 1 wireless communication device 2 array antenna 3 communication circuit board 4 communication circuit board with antenna 4a first surface 4b second surface 6 support 6a tip portion 6b bottom end surface 8 housing 10 antenna board 10a antenna surface 10b back surface 12 radiating element 14 circuit board body 14a third surface 14b fourth surface 16 ground conductor plate (conductor) 16a outer surface 17 through passage 18 tip surface 18a edge portion 20 inclined surface 24 metal plate 24a fifth surface 24b sixth surface 26 heat dissipation fin

Claims

1. An antenna substrate and a plurality of array antennas having a plurality of radiating elements mounted on the antenna surface of the antenna substrate, The device comprises a circuit board body including a first surface, and a communication circuit board that includes a flat conductor provided on the surface of the circuit board body opposite to the first surface, and performs wireless communication using the plurality of array antennas, Each of the plurality of array antennas is provided on the first surface such that the plane containing the antenna surface does not intersect the conductor, the antenna surface has an inclination angle with respect to the first surface, and the surface of the antenna substrate opposite to the antenna surface is closer to the first surface than the antenna surface. Wireless communication device.

2. The wireless communication device according to claim 1, wherein the normals of each of the multiple antenna surfaces are in different directions from each other.

3. The wireless communication device according to claim 1 or claim 2, wherein the inclination angle is 40 degrees or more and 60 degrees or less.

4. The multiple tilt angles in the multiple array antennas are equal. A wireless communication device according to claim 1 or claim 2.

5. The system further comprises a plurality of support columns that protrude from the first surface and support the plurality of array antennas on the first surface, Each of the aforementioned plurality of support columns is provided on the side opposite to the antenna surface and has an inclined surface for holding the array antenna. A wireless communication device according to claim 1 or claim 2.

6. Furthermore, the conductor has a metal plate that includes the plurality of support columns, The plurality of support columns penetrate the circuit board body. The wireless communication device according to claim 5.

7. The aforementioned metal plate has heat dissipation fins. The wireless communication device according to claim 6.

8. An antenna substrate and a plurality of array antennas having a plurality of radiating elements mounted on the antenna surface of the antenna substrate, The circuit board body includes a flat conductor provided on the substrate surface and on the surface opposite to the substrate surface, and performs wireless communication using the plurality of array antennas, Each of the plurality of array antennas is provided on the substrate surface such that the plane including the antenna surface does not intersect the conductor, the antenna surface has an inclination angle with respect to the substrate surface of the circuit board body, and the surface of the antenna substrate opposite to the antenna surface is closer to the substrate surface than the antenna surface. Communication circuit board.