Angle measurement device and angle measurement method

Abstract

Provided are: an angle measurement device having high angle measuring accuracy in a wide angle region and capable of calculating the direction in which radio waves arrive in all directions; and an angle measurement method.　This angle measurement device includes: a plurality of non-directional antennas; a directional antenna that is disposed on the same surface as the plurality of non-directional antennas and has directivity on a first side of the same surface; an arrival angle calculation unit that calculates the arrival angle of the radio waves on the basis of a phase difference between the radio waves received by at least two antennas among the plurality of non-directional antennas and the directional antenna; and a determination unit that determines, on the basis of the signal strength of the radio waves received by the directional antenna, whether the radio waves arrive from the first side or a second side opposite to the first side with respect to the same surface.

Description

Angle measurement device and angle measurement method

[0001] The present disclosure relates to an angle measurement device and an angle measurement method.

[0002] Conventionally, there has been a radio wave arrival angle measurement device that determines the direction of arrival of radio waves based on radio waves received by multiple antennas arranged in a plane. The arrival angle is determined based on the phase difference of the radio waves in two axial directions (see, for example, Patent Document 1).

[0003] Japanese Patent Application Publication No. 02-245683

[0004] However, when determining the arrival angle as with conventional radio wave arrival angle measurement devices, if a directional antenna with directivity, such as a patch antenna, is used, the angle measurement error tends to be large in a wide angle range. Also, if a directional antenna with directivity, such as a patch antenna, is used, it is not possible to calculate the arrival direction of radio waves arriving from a direction with no directivity.

[0005] Therefore, an object of the present invention is to provide an angle measuring device and an angle measuring method that have high angle measurement accuracy in a wide angle range and are capable of calculating the direction in which radio waves arrive in all directions.

[0006] An angle measuring device according to an embodiment of the present disclosure includes a plurality of omnidirectional antennas, a directional antenna arranged on the same plane as the plurality of omnidirectional antennas and having directionality toward a first side of the same plane, an arrival angle calculation unit that calculates the arrival angle of the radio waves based on a phase difference between radio waves received by at least two of the plurality of omnidirectional antennas and the directional antenna, and a determination unit that determines whether the radio waves arrive from the first side or from a second side opposite the first side of the same plane based on the signal strength of the radio waves received by the directional antenna.

[0007] It is possible to provide an angle measuring device and an angle measuring method that have high angle measurement accuracy in a wide angle range and are capable of calculating the direction in which radio waves arrive in all directions.

[0008] 1 is a diagram illustrating an example of the configuration of an angle measuring device of an embodiment. FIG. 1 is a diagram illustrating an example of a method for calculating an angle of arrival. FIG. 2 is a diagram illustrating an example of the characteristics of the phase difference of radio waves received by two inverted-F antennas versus the angle of arrival. FIG. 3 is a diagram illustrating a simulation model of the angle measuring device of an embodiment. FIG. 4 is a diagram illustrating an example of the characteristics of the phase difference of radio waves received by two inverted-F antennas versus the angle of arrival, and an example of the characteristics of the signal strength of a patch antenna and two inverted-F antennas versus the angle of arrival. FIG. 5 is a diagram illustrating an example of the operation of the angle measuring device of an embodiment. FIG. 6 is a diagram illustrating an example of the operation of the angle measuring device of an embodiment. FIG. 7 is a flowchart illustrating an example of processing executed by the angle-of-arrival calculation unit, determination unit, and angle-of-arrival determination unit of the angle measuring device of an embodiment. FIG. 6 is a diagram illustrating an example of the configuration of a comparative angle measuring device. FIG. 7 is a diagram illustrating an example of a simulation result of the angle of arrival of the comparative angle measuring device. FIG. 8 is a diagram illustrating an example of a simulation result of the angle measurement error of the comparative angle measuring device. FIG. 9 is a diagram illustrating an example of a simulation result of the angle of arrival of the angle measuring device of an embodiment.

[0009] Hereinafter, an embodiment to which the angle measuring device and angle measuring method of the present disclosure are applied will be described.

[0010] In the following description, the XYZ coordinate system is defined. The direction parallel to the X axis (X direction), the direction parallel to the Y axis (Y direction), and the direction parallel to the Z axis (Z direction) are perpendicular to each other. For ease of explanation, the -Z direction side may be referred to as the lower side or bottom, and the +Z direction side as the upper side or top, but this does not represent a universal vertical relationship. Furthermore, a planar view refers to a view from an XY plane.

[0011] In the following description, the length, width, thickness, etc. of each part may be exaggerated to make the configuration easier to understand. Furthermore, terms such as parallel, up and down, etc., may be misaligned to the extent that the effect of the embodiment is not impaired.

[0012] <Embodiment> Fig. 1 is a diagram showing an example of the configuration of an angle measuring device 100 according to an embodiment. In addition to the angle measuring device 100, Fig. 1 also shows a smartphone 50. The smartphone 50 is an example of a transmitter that transmits radio waves, and the angle measuring device 100 receives the radio waves transmitted from the smartphone 50 and calculates the direction of arrival of the radio waves. The method by which the angle measuring device 100 calculates the angle of arrival of the radio waves is an angle measuring method according to an embodiment.

[0013] The radio waves transmitted from the smartphone 50 are, for example, continuous waves (CW). The arrival direction of the radio waves indicates the direction in which the smartphone 50, which serves as a transmitter, is located. The arrival direction of the radio waves is represented by the arrival angle of the radio waves. The arrival angle may be an azimuth angle and an elevation angle. The angle measuring device 100 may further perform distance measurement and determine the position of the smartphone 50 from the determined distance and arrival angle. In this case, the angle measuring device 100 becomes a distance measuring device. Note that, although a form in which the smartphone 50 is used as an example of a transmitter will be described here, the transmitter is not limited to the smartphone 50 and may be a remote key for a vehicle or another electronic terminal.

[0014] <Angle measuring device 100> The angle measuring device 100 includes an antenna device 110 and a control device 120. The antenna device 110 has a substrate 110A, a patch antenna 111, and inverted-F antennas 112 and 113. The patch antenna 111 is an example of a directional antenna having directivity in the +Z direction. The inverted-F antennas 112 and 113 are examples of omnidirectional antennas.

[0015] <Substrate 110A> The substrate 110A is an insulating substrate, and may be, for example, a wiring substrate. A ground layer 110G, a patch element 111A of the patch antenna 111, and inverted-F antennas 112 and 113 are provided on the surface on the +Z direction side of the substrate 110A. By providing the patch element 111A and the inverted-F antennas 112 and 113 on the substrate 110A, a single packaged antenna device 110 is obtained.

[0016] The ground layer 110G has an opening 110G1 in the center in a plan view, and a notch 110G2 at the end on the ±X direction side that is cut out to provide the inverted-F antennas 112 and 113. A patch element 111A is provided inside the opening 110G1.

[0017] <Patch Antenna 111> The patch antenna 111 has a patch element 111A and a ground layer (not shown), and has directivity in the +Z direction. The +Z direction side is an example of a first side.

[0018] The patch element 111A is provided on the +Z direction surface of the substrate 110A, inside the opening 110G1 of the ground layer 110G, and is insulated from the ground layer 110G. The patch element 111A is arranged on the same surface (the surface on the +Z direction side of the substrate 110A) as the inverted-F antennas 112 and 113. Arranging the patch element 111A on the same surface as the inverted-F antennas 112 and 113 corresponds to arranging the patch antenna 111 on the same surface as the inverted-F antennas 112 and 113. Note that the length of the patch element 111A in the X direction is, for example, ¼ of the wavelength λ of the radio waves transmitted from the smartphone 50.

[0019] The ground layer of the patch antenna 111 is provided on the surface of the substrate 110A on the −Z direction side. The ground layer of the patch antenna 111 is larger than the patch element 111A in a planar view and contains the patch element 111A in a planar view. Note that while FIG. 1 shows the patch element 111A having a rectangular shape in a planar view as an example, the patch element 111A is not limited to a rectangular shape and may be circular, for example. The patch element 111A is connected to the control device 120 via wiring on the substrate 110A and is powered by the control device 120. The patch antenna 111 receives a CW signal transmitted from the smartphone 50, and the received CW signal is transmitted to the control device 120.

[0020] <Inverted-F Antennas 112 and 113> The inverted-F antennas 112 and 113 are provided on the surface of the substrate 110A on the +Z direction side, and more specifically, are provided in the notch 110G2 of the ground layer 110G. The inverted-F antennas 112 and 113 are an example of a monopole antenna. The inverted-F antennas 112 and 113 have feed points 112F and 113F, respectively. The feed points 112F and 113F are connected to the control device 120 via wiring on the substrate 110A. The inverted-F antennas 112 and 113 receive CW signals transmitted from the smartphone 50, and the received CW signals are transmitted to the control device 120.

[0021] The inverted-F antennas 112 and 113 are arranged on either side of the patch antenna 111. The inverted-F antenna 112 is arranged on the −X side of the patch antenna 111, and the inverted-F antenna 113 is arranged on the +X side of the patch antenna 111. The distance between the inverted-F antennas 112 and 113 can be made longer. By making the distance between the inverted-F antennas 112 and 113 longer, the resolution in angle measurement can be improved.

[0022] As an example, the inverted-F antennas 112 and 113 are arranged at positions equidistant from the patch antenna 111 in the X direction, and are arranged at positions symmetrical with respect to the patch antenna 111. More specifically, as an example, the inverted-F antennas 112 and 113 have an axisymmetric shape with a line A that passes through the center of the patch antenna 111 and is parallel to the Y axis as the axis of symmetry. By arranging the inverted-F antennas 112 and 113 in this manner, the radiation characteristics of the inverted-F antennas 112 and 113 are aligned, enabling the angle of arrival to be calculated with higher accuracy.

[0023] The distance between the center of the inverted-F antenna 112 in a planar view and the center of the patch element 111A in a planar view corresponds to the pitch between the inverted-F antenna 112 and the patch antenna 111, and is equal to or less than half the wavelength λ of the radio waves transmitted from the smartphone 50. Similarly, the distance between the center of the inverted-F antenna 113 in a planar view and the center of the patch element 111A in a planar view corresponds to the pitch between the inverted-F antenna 113 and the patch antenna 111, and is equal to or less than half the wavelength λ of the CW signal transmitted from the smartphone 50. The pitch between the inverted-F antenna 112 and the patch antenna 111 and the pitch between the inverted-F antenna 113 and the patch antenna 111 are, for example, equal. Furthermore, the lengths of the inverted-F antennas 112 and 113 are, for example, λ / 6.

[0024] As an example, the inverted-F antennas 112 and 113 are arranged such that the position in the Y direction of the center in a plan view of the patch element 111A of the patch antenna 111 coincides with the position in the Y direction of the center in a plan view of the inverted-F antennas 112 and 113. Note that the positions in the Y direction of the centers in a plan view of the inverted-F antennas 112 and 113 and the center in a plan view of the patch element 111A may be misaligned.

[0025] Here, as an example, the monopole antennas of the angle measuring device 100 are described as inverted-F antennas 112 and 113, but the monopole antennas may be L-shaped, linear, meandering, or other shaped monopole antennas. Monopole antennas have a simple configuration. Furthermore, any type of antenna other than a monopole antenna may be used as long as it is an omnidirectional antenna.

[0026] Here, as an example, a configuration will be described in which the antenna device 110 has one patch antenna 111 and two inverted-F antennas 112 and 113, but it is sufficient if there are multiple inverted-F antennas, and three or more inverted-F antennas may be used. All of the inverted-F antennas and the patch element 111A are required to be located on the same plane.

[0027] <Control device 120> The control device 120 has a communication unit 121, an arrival angle calculation unit 122, a determination unit 123, an arrival angle determination unit 124, and a memory 125. The communication unit 121 includes an AFE (Analog Front End), an AD (Analog to Digital) converter, etc., and outputs a signal obtained from a radio wave received from the smartphone 50 to the arrival angle calculation unit 122 and the determination unit 123. The signal obtained from the radio wave has a signal strength and a phase corresponding to the signal strength and phase of the received radio wave.

[0028] The arrival angle calculation unit 122, the determination unit 123, the arrival angle determination unit 124, and the memory 125 are realized, for example, by a microcomputer (computer) including a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), an internal bus, etc. The arrival angle calculation unit 122, the determination unit 123, and the arrival angle determination unit 124 are functional blocks representing the functions of a program executed by the microcomputer. The memory 125 is a functional representation of the memory of the microcomputer.

[0029] <Arrival angle calculation unit 122> The arrival angle calculation unit 122 is capable of calculating the arrival angle of the radio waves in the angle of arrival (AoA) format based on any one of the phase difference between the radio waves received by the inverted-F antennas 112 and 113, the phase difference between the radio waves received by the inverted-F antenna 112 and the patch antenna 111, and the phase difference between the radio waves received by the inverted-F antenna 113 and the patch antenna 111. In other words, the arrival angle calculation unit 122 is capable of calculating the arrival angle of the radio waves based on the phase difference between the radio waves received by at least two antennas, the inverted-F antennas 112 and 113 and the patch antenna 111. A method for calculating the arrival angle of the radio waves will be described later with reference to FIG. 2A .

[0030] However, angle measurement accuracy is improved by using the phase difference between the radio waves received by the inverted-F antennas 112 and 113. This is because the inverted-F antennas 112 and 113 have less angle error in the wide-angle range than the patch antenna 111. For this reason, as an example, a configuration will be described here in which the arrival angle calculation unit 122 uses the phase difference between the radio waves received by the inverted-F antennas 112 and 113 when calculating the arrival angle of the radio waves.

[0031] Furthermore, using two or more phase differences improves the angle measurement accuracy. For this reason, when calculating the arrival angle of the radio waves, the arrival angle calculation unit 122 may, for example, primarily use the phase difference between the radio waves received by the inverted-F antennas 112 and 113, and may also auxiliary use the phase difference between the radio waves received by the inverted-F antenna 112 and the patch antenna 111 and the phase difference between the radio waves received by the inverted-F antenna 113 and the patch antenna 111, in order to improve the angle measurement accuracy.

[0032] Furthermore, the antenna device 110 is arranged in the X direction in the following order: inverted-F antenna 112, patch antenna 111, and inverted-F antenna 113. In the antenna device 110, the inverted-F antennas 112 and 113 are positioned at both ends of the substrate 110A in the X direction, so that the distance between the inverted-F antennas 112 and 113 is the longest within the limited size of the substrate 110A. The greater the distance between the antennas, the higher the resolution in angle measurement, so the inverted-F antennas 112 and 113 are positioned at both ends of the substrate 110A in the X direction.

[0033] <Determination unit 123> Based on the signal strength of the radio waves received by the patch antenna 111, the determination unit 123 determines whether the radio waves are arriving from the +Z direction side (first side) or the -Z direction side (second side) opposite to the +Z direction side with respect to the +Z direction side surface of the substrate 110A.

[0034] If the arrival angle of the radio waves is calculated based solely on the phase difference between the radio waves received by inverted-F antennas 112 and 113, two arrival angles, one for the +Z direction and one for the -Z direction, are obtained, and it is not possible to determine whether the radio waves are arriving from the +Z direction or the -Z direction. Because patch antenna 111 has directivity in the +Z direction, by applying a predetermined threshold to the signal strength of the radio waves received by patch antenna 111, it is possible to determine whether the radio waves are arriving from the +Z direction or the -Z direction.

[0035] <Arrival angle determination unit 124> Of the two arrival angles calculated by the arrival angle calculation unit 122, the arrival angle determination unit 124 selects the arrival angle on the side determined by the determination unit 123 (either the +Z direction side or the −Z direction side with respect to the +Z direction side surface of the substrate 110A), and determines it as the arrival angle at which the radio wave arrives. The arrival angle determined by the arrival angle determination unit 124 is the final output of the angle measuring device 100.

[0036] <Memory 125> The memory 125 stores programs, data, and the like required for the arrival angle calculation unit 122 and the determination unit 123 to execute the above-mentioned processes and the processes described below.

[0037] <Method of calculating the angle of arrival> Figure 2A is a diagram illustrating an example of a method of calculating the angle of arrival. Figure 2A shows the inverted-F antennas 112 and 113 in an XZ plane view. Two dashed lines indicate straight lines that pass through the centers of the inverted-F antennas 112 and 113 in a plan view and are perpendicular to the surface on the +Z direction side of the substrate 110A (see Figure 1) on which the inverted-F antennas 112 and 113 are arranged.

[0038] The pitch of the inverted-F antennas 112 and 113 is d, and the incident angle (arrival angle) of the radio waves to the inverted-F antennas 112 and 113 in the XZ plane is θ. That is, the arrival angle θ represents an angle in two dimensions. In this case, the phase difference Δφ of the radio waves incident on the inverted-F antennas 112 and 113 is expressed by the following equation (1).

[0039]

[0040] The arrival angle θ is calculated from equation (1) as shown in the following equation (2).

[0041]

[0042] In this way, the arrival angle of the radio waves can be calculated based on the phase difference between the radio waves received by the inverted F antennas 112 and 113. Such calculations are performed by the arrival angle calculation unit 122.

[0043] 2B is a diagram showing an example of the characteristics of the phase difference between the radio waves received by the inverted-F antennas 112 and 113 versus the arrival angle. The characteristics shown in FIG. 2B were obtained by simulation.

[0044] 2B, the horizontal axis represents the arrival angle (incident angle) of the radio waves arriving at the inverted-F antennas 112 and 113, and the vertical axis represents the phase difference of the radio waves received by the inverted-F antennas 112 and 113. The arrival direction of the radio waves with an arrival angle of ±90 degrees is the arrival direction when the radio waves arrive along the surface on the +Z direction side of the substrate 110A relative to the inverted-F antennas 112 and 113. Furthermore, the wide-angle region is an angle region where the absolute value of the arrival angle is close to 90 degrees, and as an example, an angle region where the absolute value is 60 degrees or more.

[0045] As shown in Figure 2B, the phase difference between the radio waves received by the inverted-F antennas 112 and 113 changes continuously as the angle of arrival increases from 0 degrees to 90 degrees in absolute value, and it was confirmed that there is little error in the phase difference even in a wide angle range of 60 degrees or more in absolute value. Because the phase difference error is small, high angle measurement accuracy can be obtained.

[0046] 2A based on the phase difference between radio waves received by at least two of the inverted-F antennas 112 and 113 and the patch antenna 111. However, the arrival angle calculation unit 122 may calculate the azimuth angle and elevation angle in a polar coordinate system.

[0047] To calculate the azimuth angle and elevation angle, the patch antenna 111 and the inverted-F antenna 112 are arranged on a first axis of two mutually orthogonal axes, and the patch antenna 111 and the inverted-F antenna 113 are arranged on a second axis of the two mutually orthogonal axes. The arrival angle calculation unit 122 calculates the azimuth angle representing the position of the smartphone 50 relative to the angle measuring device 100 from the ratio between a first phase difference when the patch antenna 111 and the inverted-F antenna 112 located on the first axis receive radio waves and a second phase difference when the patch antenna 111 and the inverted-F antenna 113 located on the second axis receive radio waves. The arrival angle calculation unit 122 also calculates the elevation angle representing the position of the smartphone 50 relative to the angle measuring device 100 based on the azimuth angle and the first phase difference or the second phase difference. In this way, the elevation angle and the azimuth angle in the polar coordinate system can be measured.

[0048] 3A is a diagram showing a simulation model of the angle measuring device 100. As an example, the arrival angles in the XZ plane are set to 0 degrees in the +Z direction, 90 degrees in the +X direction, −90 degrees in the −X direction, and 180 (−180 degrees) degrees in the −Z direction.

[0049] Using such a simulation model, the phase difference of the radio waves received by the inverted-F antennas 112 and 113 and the signal strength of the radio waves received by the patch antenna 111 and the inverted-F antennas 112 and 113 were calculated.

[0050] <Phase difference of radio waves received by inverted-F antennas 112 and 113, and signal strength of radio waves received by patch antenna 111 and inverted-F antennas 112 and 113> Figure 3B is a diagram showing an example of the characteristics (upper side) of the phase difference of radio waves received by inverted-F antennas 112 and 113 versus the angle of arrival, and an example of the characteristics of signal strength of patch antenna 111 and inverted-F antennas 112 and 113 versus the angle of arrival. The signal strength is expressed in terms of realized gain (dBi). The phase difference and signal strength shown in Figure 3B are calculation results obtained by simulation.

[0051] 3B , when the phase difference between the radio waves received by inverted-F antennas 112 and 113 is 90 degrees, for example, arrival angle calculation unit 122 calculates two angles, −30 degrees and −135 degrees, as the arrival angles. −30 degrees is on the +Z side of patch antenna 111, and −135 degrees is on the −Z side of patch antenna 111.

[0052] Furthermore, as shown in the lower part of Figure 3B, because the inverted-F antennas 112 and 113 are omnidirectional antennas, the signal strength remains within a range of approximately -3 dBi to approximately +2 dBi even when the angle of arrival varies from -180 degrees to 180 degrees. In contrast, the signal strength of the patch antenna 111, which is a directional antenna, is approximately -8 dBi or greater in the range of -90 degrees to 90 degrees, which corresponds to the +Z direction side of the patch antenna 111, but is less than approximately -8 dBi in the range of -180 degrees to 90 degrees and the range of 90 degrees to 180 degrees, which correspond to the -Z direction side of the patch antenna 111. Therefore, by setting the predetermined threshold to -8 dBi, it is possible to determine whether the angle of arrival is on the +Z direction side or the -Z direction side of the patch antenna 111. This determination is performed by the determination unit 123.

[0053] <Explanation of Operation of Angle Measuring Device 100> FIGS. 4A, 4B, and 4C are diagrams for explaining an example of operation of the angle measuring device 100. FIG.

[0054] 4A shows smartphone 50 in the direction of the arrival angle calculated based only on the phase difference between the radio waves received by inverted-F antennas 112 and 113. Since two arrival angles representing two directions symmetrical with respect to the X axis are calculated, as an example, even if smartphone 50 is actually present on the −Z direction side of inverted-F antennas 112 and 113 as shown by the solid line, it is not possible to determine whether the actual arrival angle is on the −Z direction side or the +Z direction side of inverted-F antennas 112 and 113. Smartphone 50 shown by the dashed line does not actually exist.

[0055] In the angle measuring device 100, the determination unit 123 can determine whether the arrival direction is on the −Z side or the +Z side of the patch antenna 111 based on the signal strength of the patch antenna 111, so that the arrival angle can be narrowed down to either the −Z side or the +Z side, as shown in Figures 4B and 4C.

[0056] In addition, in Figure 4B, the arrival angle can be determined within a hemispherical area on the +Z direction side of patch antenna 111, and in Figure 4C, the arrival angle can be determined within a hemispherical area on the -Z direction side of patch antenna 111, so angle measuring device 100 can determine the arrival angle in all directions (a range of 360 degrees) within the XZ plane centered on patch antenna 111.

[0057] 5 is a flowchart showing an example of processing executed by the arrival angle calculation unit 122, the determination unit 123, and the arrival angle determination unit 124 of the angle measuring device 100. As a prerequisite, the arrival angle calculation unit 122 calculates the arrival angle based on radio waves simultaneously received by the communication unit 121 from the patch antenna 111 and the inverted-F antennas 112 and 113, and the determination unit 123 determines whether the angle is in the +Z direction or the −Z direction.

[0058] When the process starts, the arrival angle calculation unit 122 calculates the arrival angle based on the phase difference between the radio waves received by the inverted-F antennas 112 and 113, the phase difference between the radio waves received by the inverted-F antenna 112 and the patch antenna 111, and the phase difference between the radio waves received by the inverted-F antenna 113 and the patch antenna 111 (step S1). The arrival angle can be calculated based on, for example, equation (2), and two arrival angles are calculated in step S1.

[0059] The determination unit 123 determines whether the radio wave arrives from the +Z direction side or the −Z direction side of the patch antenna 111 based on the signal strength of the radio wave received by the patch antenna 111 (step S2).

[0060] The arrival angle determination unit 124 selects the arrival angle on the side determined by the determination unit 123 from the two arrival angles calculated by the arrival angle calculation unit 122, and determines it as the arrival angle at which the radio waves will arrive (step S3).

[0061] This completes the series of processes (END).

[0062] <Simulation Results of Angle Measurement Error and Arrival Angle> The arrival angle and angle measurement error were calculated by simulation for the angle measuring device 100 of the embodiment and a comparative angle measuring device. The simulation model of the angle measuring device 100 used was the one shown in FIG. 3A.

[0063] <Comparative Angle Measurement Device> FIG. 6A is a diagram showing an example of the configuration of a comparative angle measurement device. FIG. 6A shows the antenna device of the comparative angle measurement device in plan view. The antenna device of the comparative angle measurement device has a configuration in which five circular patch elements 1 to 5 are arranged on the surface on the +Z direction side of a substrate. Patch elements 1 to 5 are arranged such that patch element 1 is located in the center and patch elements 2 to 5 are located at equal intervals around patch element 1. The centers of patch elements 2 to 5 correspond to the four vertices of a square, and the center of patch element 1 coincides with the center of that square. Here, patch elements 2 and 4, which are arranged in the X direction, were used instead of the inverted-F antennas 112 and 113 of the angle measurement device 100 of the embodiment, and the angle of arrival and angle measurement error were calculated by simulation. The substrate is square in plan view, with the length of each side set to 120 mm. The pitch (the distance between the centers) between patch element 1 and patch elements 2 to 5 was set to 60 mm.

[0064] <Simulation Results of the Comparative Angle Measuring Device> Fig. 6B is a diagram showing an example of the simulation results of the arrival angle of the comparative angle measuring device. In Fig. 6B, the horizontal axis represents the arrival angle of the radio wave set in the simulation, and the vertical axis represents the arrival angle calculated by the comparative angle measuring device. The dashed line shows the relationship between the arrival angle of the radio wave set in the simulation and the calculated value of the ideal arrival angle that does not include error.

[0065] 6C is a diagram showing an example of the simulation results of the angle measurement error of a comparative angle measuring device. In FIG. 6C, the horizontal axis represents the arrival angle of the radio wave set in the simulation, and the vertical axis represents the error of the arrival angle calculated by the comparative angle measuring device. The error is the difference between the arrival angle of the radio wave set in the simulation and the calculated value of an ideal arrival angle that does not include any error.

[0066] The angle of arrival calculated by the comparative angle measuring device showed a significant deviation from the ideal angle of arrival when the absolute value of the angle of arrival of the radio waves set in the simulation was approximately 40 degrees or more, and when the absolute value of the angle of arrival of the radio waves set in the simulation was approximately 80 degrees or more, the calculated angle of arrival showed a characteristic of saturating at an absolute value of approximately 60 degrees. Thus, it was confirmed that with the comparative angle measuring device, the error was large in the wide-angle range where the absolute value of the angle of arrival of the radio waves set in the simulation was 60 degrees or more, and that the error became larger as the absolute value of the angle of arrival of the radio waves set in the simulation became larger. The maximum error was approximately 30 degrees.

[0067] <Simulation Results of Angle Measuring Device 100 of Embodiment> Fig. 6D is a diagram showing an example of a simulation result of the arrival angle of the angle measuring device 100 of the embodiment. In Fig. 6D, the horizontal axis represents the arrival angle of the radio wave set in the simulation, and the vertical axis represents the arrival angle calculated by the angle measuring device 100. The dashed straight line indicates the relationship between the arrival angle of the radio wave set in the simulation and the calculated value of the ideal arrival angle that does not include an error.

[0068] In the simulation, the arrival angle was calculated based on the phase difference between the radio waves received by the inverted-F antennas 112 and 113. The outer dimensions of the substrate 110A were set to 73 mm (X direction) × 53 mm (y direction). The pitch in the X direction between the inverted-F antenna 112 and the patch element 111A and the pitch in the X direction between the inverted-F antenna 113 and the patch element 111A were both set to 30 mm.

[0069] 6E is a diagram showing an example of a simulation result of the angle measurement error of the angle measuring device 100 according to the embodiment. In Fig. 6E, the horizontal axis represents the arrival angle of the radio wave set in the simulation, and the vertical axis represents the error in the arrival angle calculated by the angle measuring device 100.

[0070] The arrival angle calculated by the angle measuring device 100 exhibited a characteristic in which deviation from the ideal arrival angle was extremely small, even when the absolute value of the arrival angle of the radio wave set in the simulation approached 90 degrees. With the angle measuring device 100, the error was small even in wide-angle regions, with the maximum error being less than 10 degrees.

[0071] Thus, the reason why the error in the angle of arrival calculated by angle measuring device 100 is small is because the angle of arrival is calculated based on the phase difference between the radio waves received by the two inverted-F antennas 112 and 113. The phase difference between the radio waves received by inverted-F antennas 112 and 113 has a smaller error, particularly in the wide-angle range, compared to the phase difference between the radio waves received by patch elements 2 and 4 of the comparative angle measuring device. For this reason, the angle of arrival can be calculated with high accuracy both in the wide-angle range and in the range where the angle of arrival is smaller than the wide-angle range.

[0072] <Effects> The angle measuring device 100 includes inverted-F antennas 112 and 113 (plurality of omnidirectional antennas), a patch antenna 111 (omnidirectional antenna) that is arranged on the same plane as the inverted-F antennas 112 and 113 and has directivity toward a first side of the same plane, an arrival angle calculation unit 122 that calculates the arrival angle of the radio waves based on the phase difference of the radio waves received by at least two antennas out of the inverted-F antennas 112 and 113 and the patch antenna 111, and a determination unit 123 that determines whether the radio waves arrive from the +Z direction side (first side) or the −Z direction side (second side) opposite to the first side with respect to the same plane, based on the signal strength of the radio waves received by the patch antenna 111. By calculating the angle of arrival of radio waves based on the phase difference between radio waves received by two antennas including at least one of the inverted F antennas 112 and 113, the accuracy of calculating the angle of arrival is improved, and since the determination unit 123 determines whether the radio waves are arriving from the +Z direction side (first side) or the -Z direction side (second side), the angle of arrival can be identified in all directions.

[0073] Therefore, it is possible to provide an angle measuring device 100 that has high angle measurement accuracy in a wide angle range and is capable of calculating the direction in which radio waves arrive in all directions.

[0074] Furthermore, the arrival angle calculation unit 122 may calculate the arrival angle of the radio waves based on the phase difference between the radio waves received by the inverted F antennas 112 and 113. Since the phase difference between the radio waves received by the inverted F antennas 112 and 113 has a small error, particularly in the wide-angle range, the arrival angle can be calculated with high accuracy both in the wide-angle range and in the range where the arrival angle is smaller than the wide-angle range.

[0075] Furthermore, the inverted-F antennas 112 and 113 may be arranged on either side of the patch antenna 111. This allows the distance between the inverted-F antennas 112 and 113 to be increased, thereby improving the resolution in angle measurement.

[0076] The device may further include a substrate 110A, and the two omnidirectional antennas may be two inverted-F antennas 112 and 113, with the patch antenna 111 and the two inverted-F antennas 112 and 113 being disposed on the substrate 110A. When disposed on the substrate 110A, the distance between the inverted-F antennas 112 and 113 can be increased, improving the resolution in angle measurement and providing an angle measurement device 100 including a single packaged antenna device 110.

[0077] Furthermore, the two inverted-F antennas 112 and 113 may be disposed at equal distances from the patch antenna 111. By aligning the radiation characteristics of the two inverted-F antennas 112 and 113, the arrival angle can be calculated with higher accuracy.

[0078] The two inverted-F antennas 112 and 113 may be arranged at positions symmetrical to the patch antenna 111. When the radiation characteristics of the two inverted-F antennas 112 and 113 are aligned, the arrival angle can be calculated with higher accuracy.

[0079] The two inverted-F antennas 112 and 113 may have shapes that are symmetrical with respect to a line passing through the center of the patch antenna 111. By aligning the radiation characteristics of the two inverted-F antennas 112 and 113, the arrival angle can be calculated with higher accuracy.

[0080] The directional antenna may be a patch antenna, and the omnidirectional antenna may be a monopole antenna. The directional antenna and the omnidirectional antenna can be realized with simple antennas, and an angle measuring device 100 can be provided that has a simple configuration, has high angle measurement accuracy in a wide angle range, and is capable of calculating the direction in which radio waves arrive in all directions.

[0081] In addition, in the angle measuring device 100 including inverted-F antennas 112 and 113 (multiple omnidirectional antennas), a patch antenna 111 (omnidirectional antenna) arranged on the same plane as the inverted-F antennas 112 and 113 and having directivity on a first side of the same plane, and a computer, the computer calculates the arrival angle of the radio waves based on the phase difference of the radio waves received by at least two antennas out of the inverted-F antennas 112 and 113 and the patch antenna 111, and determines whether the radio waves arrive from the first side or from a second side opposite the first side on the same plane based on the signal strength of the radio waves received by the patch antenna 111. By calculating the arrival angle of the radio waves based on the phase difference of the radio waves received by two antennas including at least one of the inverted-F antennas 112 and 113, the accuracy of calculating the arrival angle is improved, and further, since the determination unit 123 determines whether the radio waves arrive from the +Z direction side (first side) or the −Z direction side (second side), the arrival angle can be identified in all directions.

[0082] Therefore, it is possible to provide an angle measurement method that has high angle measurement accuracy in a wide angle range and is capable of calculating the direction in which radio waves arrive in all directions.

[0083] The above describes an angle measurement device and an angle measurement method according to exemplary embodiments of the present disclosure. However, the present disclosure is not limited to the specifically disclosed embodiments, and various modifications and changes are possible without departing from the scope of the claims.

[0084] This international application claims priority based on Japanese Patent Application No. 2023-168407, filed on September 28, 2023, the entire contents of which are incorporated herein by reference.

[0085] 50 Smartphone 100 Angle measuring device 110 Antenna device 110A Substrate 110G Ground layer 110G1 Opening 110G2 Notch 111 Patch antenna 111A Patch element 112, 113 Inverted F antenna 112F, 113F Feeding point 120 Control device 121 Communication unit 122 Arrival angle calculation unit 123 Determination unit 124 Arrival angle determination unit 125 Memory

Claims

1. An angle measuring device comprising: a plurality of omnidirectional antennas; a directional antenna arranged on the same plane as the plurality of omnidirectional antennas and having directionality toward a first side of the same plane; an arrival angle calculation unit that calculates the arrival angle of the radio waves based on a phase difference between radio waves received by at least two antennas among the plurality of omnidirectional antennas and the directional antenna; and a determination unit that determines whether the radio waves arrive from the first side or from a second side opposite the first side of the same plane based on the signal strength of the radio waves received by the directional antenna.

2. The angle measuring device according to claim 1, wherein the arrival angle calculation unit calculates the arrival angle of the radio waves based on a phase difference between the radio waves received by the multiple omnidirectional antennas.

3. The angle measuring device according to claim 1, wherein the plurality of omnidirectional antennas are arranged on either side of the directional antenna.

4. The angle measuring device according to claim 3, further comprising a substrate, the plurality of omnidirectional antennas being two omnidirectional antennas, and the directional antenna and the two omnidirectional antennas being disposed on the substrate.

5. The angle measuring device according to claim 4, wherein the two omnidirectional antennas are arranged equidistantly with respect to the directional antenna.

6. The angle measuring device according to claim 4, wherein the two omnidirectional antennas are arranged at positions symmetrical to the directional antenna.

7. The angle measuring device according to claim 4, wherein the two omnidirectional antennas have shapes that are symmetrical with respect to a line passing through the center of the directional antenna.

8. An angle measuring device according to any one of claims 1 to 7, wherein the directional antenna is a patch antenna, and the omnidirectional antenna is a monopole antenna.

9. An angle measuring method in an angle measuring device including a plurality of omnidirectional antennas, a directional antenna arranged on the same plane as the plurality of omnidirectional antennas and having directionality toward a first side of the same plane, and a computer, wherein the computer executes the following steps: calculates the arrival angle of the radio waves based on a phase difference between the radio waves received by at least two antennas among the plurality of omnidirectional antennas and the directional antenna; and determines whether the radio waves arrive from the first side or from a second side opposite the first side of the same plane based on the signal strength of the radio waves received by the directional antenna.

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