Antenna device

Abstract

To form a wide communication area in a midair-floating type communication device.SOLUTION: An antenna device mounted on a midair-floating type communication device includes: a first array antenna that has a plurality of annularly arranged antenna elements and forms a first communication area on the ground; and a second array antenna that has a plurality of annularly arranged antenna elements and forms a second communication area outside the first communication area.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to an antenna device.

Background Art

[0002] An airborne relay device such as a High Altitude Platform Station (HAPS) is known.

[0003] As an antenna device mounted on an airborne relay device, a phased array antenna capable of beamforming is known. Further, FIG. 30 of Patent Document 1 discloses a hexagonal pyramid-shaped antenna device including a plurality of planar array antennas.

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In an airborne relay device such as HAPS, it is desired to form a wider communication area.

[0006] Non-limiting examples of the present disclosure contribute to providing an antenna device that forms a wide communication area in an airborne communication device.

Means for Solving the Problems

[0007] One embodiment of the present disclosure is an antenna device mounted on an airborne communication device, including a first array antenna arranged annularly to form a first communication area on the ground, and a second array antenna arranged annularly to form a second communication area outside the first communication area.

[0008] These general or specific aspects may be implemented in a system, apparatus, method, integrated circuit, computer program, or recording medium, or may be implemented in any combination of a system, apparatus, method, integrated circuit, computer program, and recording medium.

Advantages of the Invention

[0009] According to an embodiment of the present disclosure, in an airborne relay device, a wide communication area can be formed.

[0010] Further advantages and effects in an embodiment of the present disclosure will be clarified from the specification and drawings. Such advantages and / or effects are provided by some embodiments and the features described in the specification and drawings respectively, but not all of them are necessarily provided in order to obtain one or more identical features.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8A

Figure 8B

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Mode for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present disclosure will be described in detail with appropriate reference to the drawings. However, a more detailed description than necessary may be omitted. For example, detailed descriptions of well-known matters and redundant descriptions of substantially the same configurations may be omitted. This is to avoid making the following description unnecessarily redundant and to facilitate understanding by those skilled in the art.

[0013] Note that the accompanying drawings and the following description are provided for those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0014] (First Embodiment) FIG. 1 is a diagram showing a configuration example of a communication system 1 according to the first embodiment. As shown in FIG. 1, the communication system 1 includes a HAPS 11 and ground stations 12 and 13.

[0015] The HAPS 11 is an aircraft such as a UAV (unmanned aerial vehicle) or an unmanned balloon equipped with a relay device. The HAPS 11 relays communication between the ground station 12 fixed to the ground and the ground station 13.

[0016] Service area A11 indicates the communicable area of HAPS11. HAPS11 stays in the air while flying along a circular HAPS route R11 at an altitude of about 20 km, for example, and forms service area A11 on the ground. HAPS route R11 is determined so that ground stations 12 and 13 are located within service area A11, for example.

[0017] While flying along HAPS route R11, HAPS11 constantly establishes link L11 with ground station 12 and link L12 with ground station 13 within service area A11, and provides (relays) a wireless communication line between ground station 12 and ground station 13.

[0018] Note that HAPS may also be referred to as an airborne relay device, relay station, wireless station, or communication device. The ground station may also be referred to as a base station, wireless station, or communication device. The service area may also be referred to as a communication area or area.

[0019] Also, HAPS route R11 does not have to be circular. For example, HAPS route R11 may be in the shape of an 8.

[0020] Figure 2 is a perspective view of antenna device 20 mounted on HAPS11. As shown in Figure 2, antenna device 20 has planar array antennas 21 to 24 (second array antennas) and planar array antennas 31 to 34 (first array antennas). Antenna device 20 is disposed, for example, at the bottom of an unmanned aerial vehicle.

[0021] Planar array antennas 21 to 24 and 31 to 34 are arranged in a ring. Planar array antennas 21 to 24 and 31 to 34 are arranged such that the normal of the antenna plane (the plane in which antenna element 41 shown in Figure 4 is formed) faces downward with respect to the horizontal direction. That is, the antenna planes of planar array antennas 21 to 24 and 31 to 34 face the ground when HAPS11 is floating in the air. By arranging planar array antennas 21 to 24 and 31 to 34 in a ring, the antenna elements formed on the antenna planes of planar array antennas 21 to 24 and 31 to 34 are also arranged in a ring.

[0022] The depression angles of the antenna surfaces of each of the planar array antennas 21 to 24 are the same. The depression angles of the antenna surfaces of each of the planar array antennas 31 to 34 are the same. Here, "the same" includes "substantially the same" unless otherwise specified. Also, hereinafter, "the depression angle of the antenna surface of a planar array antenna" may be expressed as "the depression angle of a planar array antenna". Also, hereinafter, the depression angle is referred to as the tilt angle.

[0023] FIG. 3A is a side view of the planar array antenna 21. FIG. 3B is a side view of the planar array antenna 31.

[0024] The dotted line X1 in FIG. 3A indicates the normal line of the planar array antenna 21. The normal line of the planar array antenna 21 faces downward with respect to the horizontal direction. As shown in FIG. 3A, the planar array antenna 21 has a tilt angle TA1.

[0025] As described above, the planar array antennas 21 to 24 have the same tilt angle. Therefore, the planar array antennas 22 to 24 also have the tilt angle TA1.

[0026] The dotted line X2 in FIG. 3B indicates the normal line of the planar array antenna 31. The normal line of the planar array antenna 31 faces downward with respect to the horizontal direction. As shown in FIG. 3B, the planar array antenna 31 has a tilt angle TA2. The tilt angle TA2 is larger than the tilt angle TA1 of the planar array antenna 21.

[0027] As described above, the planar array antennas 31 to 34 have the same tilt angle. Therefore, the planar array antennas 32 to 34 also have the tilt angle TA2.

[0028] The tilt angle TA2 is less than 90 degrees. Therefore, the antenna surfaces of the planar array antennas 31 to 34 do not face directly downward. The antenna surfaces of the planar array antennas 31 to 34 having a tilt angle TA1 smaller than the tilt angle TA2 also do not face directly downward.

[0029] Hereinafter, the planar array antennas 21 to 24 having the same tilt angle TA1 may be referred to as antenna group G1. The planar array antennas 31 to 34 having the same tilt angle TA2 may be referred to as antenna group G2.

[0030] Returning to the description of FIG. 2. The planar array antennas 21 to 24, 31 to 34 are arranged such that the tilt angles of adjacent planar array antennas 21 to 24, 31 to 34 are different from each other.

[0031] For example, when looking at the antenna device 20 of FIG. 2 from above, a planar array antenna 31 having a tilt angle TA2 is arranged to the left of the planar array antenna 21 having a tilt angle TA1. To the left of the planar array antenna 31 having a tilt angle TA2, a planar array antenna 22 having a tilt angle TA1 is arranged. That is, the planar array antennas 21 to 24 of antenna group G1 and the planar array antennas 31 to 34 of antenna group G2 are arranged alternately in a ring shape.

[0032] FIG. 4 is a front view of the planar array antenna 21. As shown in FIG. 4, the planar array antenna 21 has a plurality of antenna elements 41 arranged in the vertical and horizontal directions. The antenna element 41 is, for example, a polarization - sharing patch antenna corresponding to vertical polarization and horizontal polarization.

[0033] Hereinafter, the coordinates (positions) of the antenna elements 41 in the planar array antenna 21 are denoted as P(m,n). m indicates the position of the antenna element 41 in the vertical direction. n indicates the position of the antenna element 41 in the horizontal direction. m is an integer from 1 to M. n is an integer from 1 to N.

[0034] Note that in the example of the planar array antenna 21 shown in FIG. 4, M = N = 8 for P(M,N) shown in FIG. 4.

[0035] Also, in FIG. 4, although the configuration example of the planar array antenna 21 has been described, the planar array antennas 22 to 24, 31 to 34 also have the same configuration as the planar array antenna 21 shown in FIG. 4.

[0036] FIG. 5 is a diagram showing an example of the block configuration of the planar array antenna 21. As shown in FIG. 5, the planar array antenna 21 includes M×N RF (Radio Frequency) units 51-1, 51-2, …, 5M-N, a baseband (BB) unit 63, and an I / F (Interface) unit 64.

[0037] The RF unit 51-1 includes the antenna element 41 of P(1,1) shown in FIG. 4, and transceivers 61 and 62.

[0038] The transceiver 61 up-converts the signal in the H polarization (vertical polarization) output from the baseband unit 63 to a radio frequency and outputs it to the antenna element 41 of P(1,1). Also, the transceiver 61 down-converts the signal in the H polarization received by the antenna element 41 of P(1,1) and outputs it to the baseband unit 63.

[0039] The transceiver 62 up-converts the signal in the V polarization (horizontal polarization) output from the baseband unit 63 to a radio frequency and outputs it to the antenna element 41 of P(1,1). Also, the transceiver 62 down-converts the signal in the V polarization received by the antenna element 41 of P(1,1) and outputs it to the baseband unit 63.

[0040] The RF units 51-2, …, 5M-N also have the same configuration as the RF unit 51-1. However, the unit of the RF unit 5m-n has the antenna element 41 of P(m,n).

[0041] The baseband unit 63 is connected to the RF units 51-1, 51-2, …, 5M-N via the interfaces of TRXBB-V / H(1,1), TRXBB-V / H(1,2), …, TRXBB-V / H(M,N) that transmit and receive digital baseband signals. The baseband unit 63 performs baseband processing on the signals received from the I / F unit 64 and outputs them to the RF units 51-1, 51-2, …, 5M-N. Also, the baseband unit 63 performs baseband processing on the signals output from the RF units 51-1, 51-2, …, 5M-N and outputs them to the I / F unit 64.

[0042] In FIG. 5, a block configuration example of the planar array antenna 21 was described. However, the planar array antennas 22 to 24 and 31 to 34 also have the same block configuration as the planar array antenna 21 shown in FIG. 5.

[0043] FIG. 6 is a diagram showing a block configuration example of the HAPS 11. As shown in FIG. 6, the HAPS 11 includes the antenna device 20 shown in FIG. 2, a signal processing unit 72, and an I / F unit 73.

[0044] The antenna device 20 includes the planar array antennas 21 to 24 and 31 to 34 shown in FIG. 2. The planar array antennas 21 to 24 are arranged at the tilt angle TA1 and belong to the antenna group G1 as shown in FIG. 6. The planar array antennas 31 to 34 are arranged at the tilt angle TA2 and belong to the antenna group G2 as shown in FIG. 6. Also, the antenna device 20 includes a control unit 71 not shown in FIG. 2.

[0045] The control unit 71 is connected to the I / F unit 64 of the planar array antenna 21 described in FIG. 5. The planar array antennas 22 to 24 and 31 to 34 also have the same I / F unit as the I / F unit 64 of the planar array antenna 21 as described in FIG. 5 and are connected to the control unit 71.

[0046] Based on the position information and attitude information of the antenna device 20 and the position information of the ground station 12, the control unit 71 determines whether to communicate with the ground station 12 using the antenna group G1 or to communicate with the ground station 12 using the antenna group G2.

[0047] When the control unit 71 determines to communicate with the ground station 12 using the antenna group G1, it communicates with the ground station 12 using any one of the planar array antennas 21 to 24 of the antenna group G1. When the control unit 71 determines to communicate with the ground station 12 using the antenna group G2, it communicates with the ground station 12 using the planar array antennas 31 to 34 of the antenna group G2. The control unit 71 performs the same determination and control as above also in the communication with the ground station 13.

[0048] The signal processing unit 72 includes a ground station processing unit 72a and a ground station processing unit 72b, and performs signal reproduction and relay processing.

[0049] For example, the ground station processing unit 72a outputs the signal received from the ground station 12 from the TX terminal of the ground station processing unit 72a and outputs it to the RX terminal of the ground station processing unit 72b. The ground station processing unit 72b transmits the signal of the ground station 12 input to the RX terminal to the ground station 13. The ground station processing unit 72b outputs the signal received from the ground station 13 from the TX terminal of the ground station processing unit 72b and outputs it to the RX terminal of the ground station processing unit 72a. The ground station processing unit 72a transmits the signal of the ground station 13 input to the RX terminal to the ground station 12.

[0050] Note that the control signal shown in FIG. 6 indicates the control signal transmitted and received between the antenna device 20 and the signal processing unit 72. Channel 1TRX indicates the signal received from the ground station 12 and the signal transmitted to the ground station 12. Channel 2TRX indicates the signal received from the ground station 13 and the signal transmitted to the ground station 13.

[0051] The position information and attitude information of the HAPS 11 are input to the I / F unit 73. For example, a GNSS (Global Navigation Satellite System) device is connected to the I / F unit 73, and GNSS signals are input thereto. Also, for example, an inertial sensor is connected to the I / F unit 73, and attitude signals such as acceleration signals and angular velocity signals are input thereto. As will be described later, the position information and attitude information of the HAPS 11 are used, together with the position information of the ground stations 12 and 13, for the control of the antenna groups G1 and G2.

[0052] FIG. 7 is a diagram for explaining the areas formed by the antenna group G1 and the antenna group G2. The service area A11 described in FIG. 1 is shown in FIG. 7.

[0053] An area A21 sandwiched between the solid circle C1 and the solid circle C2 shown in FIG. 7 indicates a communication area formed (provided) by the planar array antennas 21 to 24 of the antenna group G1.

[0054] An area A22 sandwiched between the solid circle C1 and the solid circle C3 shown in FIG. 7 indicates a communication area formed by the planar array antennas 31 to 34 of the antenna group G2.

[0055] Therefore, the service area A11 provided by the HAPS 11 is composed of the area A21 and the area A22.

[0056] Note that, as described in FIGS. 3A and 3B, the tilt angle TA1 of the planar array antennas 21 to 24 of the antenna group G1 is smaller (shallower) than the tilt angle TA2 of the planar array antennas 31 to 34 of the antenna group G2. Therefore, the area A21 is formed outside the area A22.

[0057] The planar array antennas 21 to 24 of the antenna group G1 are arranged, for example, such that the normal of the antenna surface faces the boundary X11 that equally divides the area A21. Thereby, the area (area A21) covered by the swing width (the upper limit angle and the lower limit angle in the tilt angle direction of BF) in the tilt angle direction of BF can be substantially equally divided at the boundary X11.

[0058] The planar array antennas 31 to 34 of the antenna group G2 are arranged, for example, such that the normal of the antenna surface faces the boundary X12 that equally divides the area A22. Thereby, the area (area A22) covered by the swing width in the tilt angle direction of BF can be substantially equally divided at the boundary X12.

[0059] In this way, when the planar array antennas 21 to 24 and 31 to 34 are arranged so as to equally divide the areas A21 and A22, the antenna device 20 can suppress the deterioration of the BF performance.

[0060] Note that the planar array antennas 21 to 24 of the antenna group G1 and the planar array antennas 31 to 34 of the antenna group G2 are not limited to the arrangement that equally divides the areas A21 and A22.

[0061] Also, since the area A22 has a shorter centrifugal distance from the rotation of the HAPS11 and a smaller free space loss than the area A21, the area may be relatively widened. Thereby, the distribution of the transmission power for each area is equalized.

[0062] FIGS. 8A and 8B are diagrams for explaining control examples of the antenna group G1 and the antenna group G2. In FIGS. 8A and 8B, the same components as those in FIG. 7 are denoted by the same reference numerals.

[0063] As shown in FIG. 8A, when the ground station 12 is located within the area A21, the HAPS11 selects, among the planar array antennas 21 to 24 of the antenna group G1 that form the area A21, the planar array antenna that faces the ground station 12 in the azimuth direction.

[0064] For example, HAPS11 selects a planar array antenna among the planar array antennas 21 to 24 of the antenna group G1, in which the normal of the antenna plane faces a direction within a range of ±45 degrees in the azimuth direction with respect to the terrestrial station 12. HAPS11 performs BF control on the selected planar array antenna and directs the beam toward the terrestrial station 12.

[0065] As shown in FIG. 8B, when the terrestrial station 12 is located within the area A22, HAPS11 selects a planar array antenna among the planar array antennas 31 to 34 of the antenna group G2 that forms the area A22 and that faces the terrestrial station 12 in the azimuth direction.

[0066] For example, HAPS11 selects a planar array antenna among the planar array antennas 31 to 34 of the antenna group G2, in which the normal of the antenna plane faces a direction within a range of ±45 degrees in the azimuth direction with respect to the terrestrial station 12. HAPS11 performs BF control on the selected planar array antenna and directs the beam toward the terrestrial station 12.

[0067] Note that, in the above, control examples of the antenna group G1 and the antenna group G2 with respect to the terrestrial station 12 have been described, but HAPS11 performs similar control also at the terrestrial station 13.

[0068] Also, the angular range in the azimuth direction with respect to the terrestrial station 12 is not limited to ±45 degrees. The angular range in the azimuth direction with respect to the terrestrial station 12 may be changed according to the number of planar array antennas. For example, if the number of planar array antennas is large, the angular range in the azimuth direction with respect to the terrestrial station 12 becomes small.

[0069] FIG. 9 is a flowchart for explaining an operation example of the antenna device 20. The control unit 71 of the antenna device 20 starts the processing of the flowchart shown in FIG. 9, for example, when HAPS11 starts turning at the target location where it hovers in the air.

[0070] The control unit 71 acquires the position information of HAPS 11, the position information of the terrestrial stations 12 and 13, and the attitude information of HAPS 11 (S1).

[0071] Note that the control unit 71 acquires the position information and attitude information of HAPS 11 via the I / F unit 73. The position information of the terrestrial stations 12 and 13 is stored in advance in a storage device such as a memory included in the control unit 71, for example, before HAPS 11 starts flying. The position information includes, for example, latitude, longitude, and altitude.

[0072] Based on the position information and attitude information of HAPS 11 acquired in S1 and the position information of the terrestrial stations 12 and 13, the control unit 71 determines whether the terrestrial station 12 is located in area A21 or area A22 (S2).

[0073] That is, the control unit 71 determines whether the terrestrial station 12 is located in area A21 formed by the planar array antennas 21 to 24 of the antenna group G1, or whether the terrestrial station 12 is located in area A22 formed by the planar array antennas 31 to 34 of the antenna group G2.

[0074] When the control unit 71 determines that the terrestrial station 12 is located in area A21 formed by the planar array antennas 21 to 24 of the antenna group G1 (''area A21'' in S2), it executes BF control directed at the terrestrial station 12 using the planar array antennas 21 to 24 (S3a to S7a). Also, when the control unit 71 determines that the terrestrial station 12 is located in area A22 formed by the planar array antennas 31 to 34 of the antenna group G2 (''area A22'' in S2), it executes BF control directed at the terrestrial station 12 using the planar array antennas 31 to 34 (S3b to S7b).

[0075] Hereinafter, the processing (S3a to S7a) when the control unit 71 determines that the terrestrial station 12 is located in area A21 formed by the planar array antennas 21 to 24 of the antenna group G1 will be described.

[0076] The control unit 71 acquires the position information of HAPS 11, the position information of the terrestrial stations 12 and 13, and the attitude information of HAPS 11 (S3a). Note that the control unit 71 acquires the position information of HAPS 11, the position information of the terrestrial stations 12 and 13, and the attitude information of HAPS 11 by the same process as the process of S1.

[0077] Based on the position information and attitude information of HAPS 11 acquired in S3a and the position information of the terrestrial stations 12 and 13, the control unit 71 selects, from among the planar array antennas 21 to 24 of the antenna group G1, a planar array antenna whose antenna plane normal faces within a predetermined angular range from the azimuth direction with respect to the terrestrial station 12 (S4a).

[0078] The control unit 71 calculates the weights for BF to face the terrestrial station 12 using the planar array antenna selected in S4a (S5a). Note that the control unit 71 calculates the direction of BF toward the terrestrial station 12 based on the position information and attitude information of HAPS 11 acquired in S3a and the position information of the terrestrial stations 12 and 13.

[0079] The control unit 71 controls (forms) BF using the weights calculated in S5a in the planar array antenna selected in S4a (S6a).

[0080] The control unit 71 determines whether or not a predetermined time has elapsed (S7a).

[0081] If the control unit 71 determines that the predetermined time has not elapsed (''No'' in S7a), the process proceeds to S3a. That is, the control unit 71 performs BF control using the planar array antennas 21 to 24 of the antenna group G1.

[0082] On the other hand, if the control unit 71 determines that the predetermined time has elapsed (''Yes'' in S7a), the process proceeds to S1. Then, in S2, the control unit 71 determines whether the terrestrial station 12 is located in area A21 or area A22.

[0083] That is, the frequency of determining whether the terrestrial station 12 is located in the area A21 or the area A22 in the tilt angle direction (the process of S2) is less than the frequency of the BF control (S3a to S6a). This is because even when the HAPS 11 rotates in the air, the variation of the terrestrial station 12 in the tilt angle direction with respect to the HAPS 11 is small.

[0084] Note that S3b to S7b are the processes of BF control in the planar array antennas 31 to 34 of the antenna group G2, and are the same as the processes of S3a to 37a, so the description thereof is omitted.

[0085] Also, the control unit 71 also executes the process of the flowchart in FIG. 9 for the terrestrial station 13.

[0086] An example of the weight calculation in S5a will be described. The control unit 71 calculates the direction of the terrestrial station 12 with respect to the antenna surface of the planar array antenna selected in S4a based on the position information and attitude information of the HAPS 11 and the position information of the terrestrial station 12. That is, the control unit 71 calculates the beam direction "r0" formed by the planar array antenna selected in S4a. Then, the control unit 71 performs BF control using the weight "w0" at which the beam is directed in the calculated beam direction "r0" for each of the M×N RF units (for example, refer to the RF units 51-1, 51-2,..., 5M-N in FIG. 5) of the planar array antenna selected in S4a.

[0087] The weight w0(m,n) used in the RF unit of P(m,n) is calculated using the value of Equation (1). Here, p(m,n) represents the vector from the center of the antenna surface to the antenna element P(m,n). j represents the imaginary unit. k represents the wave number at the frequency to be used. r0 is a vector indicating the beam direction. ur0 is the unit vector in the r0 direction.

[0088] w0(m,n)=exp(-j×k×(ur0·p(m,n))) (1)

[0089] Through the above processing, the antenna device 20 can perform BF control following the position and attitude changes of the HAPS 11.

[0090] As described above, the antenna device 20 mounted on the HAPS 11 includes planar array antennas 31 to 34 that are arranged annularly and form an area A22 on the ground, and planar array antennas 21 to 24 that are arranged annularly and form an area A21 outside the area A22.

[0091] In this way, since the antenna device 20 forms the area A22 with the planar array antennas 31 to 34 and forms the area A21 with the planar array antennas 31 to 34 outside thereof, a wide communication area can be formed.

[0092] Also, the antenna device 20 does not have a planar array antenna whose antenna surface faces directly downward. That is, the antenna device 20 does not have antenna elements on the bottom surface (the surface facing the ground). Thereby, the antenna device 20 does not require polarization control due to the yaw rotation of the HAPS 11.

[0093] For example, a planar array antenna whose antenna surface faces directly downward rotates at the same angle as the yaw rotation of the HAPS 11. Therefore, the polarization of the communication path with the ground stations 12 and 13 rotates according to the yaw rotation of the HAPS 11. In a planar array antenna whose antenna surface faces directly downward, in order to form a stable communication path, polarization control following the rotating polarization is required, and the BF control becomes complicated.

[0094] In contrast, the antenna device 20 does not have a planar array antenna whose antenna surface faces directly downward. The antenna device 20 covers, for example, the area formed by a planar array antenna whose antenna surface faces directly downward with the planar array antennas 31 to 34 of the antenna group G2. Thereby, the antenna device 20 does not require polarization control due to the yaw rotation of the HAPS 11.

[0095] In Fig. 4, an example of a planar array antenna with 8×8 antenna elements is shown as an example, but the number of antenna elements is not limited to this. The number of antenna elements (M×N) may be determined according to the line design between HAPS11 and the ground station.

[0096] Also, a planar array antenna with different numbers of vertical and horizontal elements (M≠N) may be used for the antenna device 20. The control unit 71 can perform BF control following the position and attitude changes of HAPS11 by calculating weights according to the position P(m, n) of the antenna elements using Equation (1).

[0097] Also, the planar array antennas 21 to 24, 31 to 34 may be configured as digital phased arrays. Thereby, the antenna device 20 can control BF with higher precision than when the planar array antennas 21 to 24, 31 to 34 are configured as analog phased arrays.

[0098] Also, the planar array antennas 21 to 24, 31 to 34 may be configured as analog phased arrays. Thereby, the antenna device 20 can reduce power consumption compared to the case where the planar array antennas 21 to 24, 31 to 34 are configured as digital phased arrays.

[0099] Also, the planar array antennas 21 to 24, 31 to 34 may be configured as a combination of analog phased arrays and digital phased arrays. Thereby, the antenna device 20 can reduce power consumption with the analog phased array while compensating for BF that cannot be controlled with high precision by the analog phased array using the digital phased array.

[0100] Also, the array antenna does not have to be a planar array antenna. The antenna surface of the array antenna may be a curved surface.

[0101] Further, the antenna device 20 divides the service area A11 into concentric areas A21 and A22 by the planar array antennas 21 to 24 and 31 to 34 of antenna groups G1 and G2 with different inclination angles of the antenna surface. The antenna device 20 is set such that the orientations of the antenna surfaces of the planar array antennas 21 to 24 of the antenna group G1 equally divide the area A21 in the inclination angle direction. The antenna device 20 is set such that the orientations of the antenna surfaces of the planar array antennas 31 to 34 of the antenna group G2 equally divide the area A22 in the inclination angle direction. The antenna device 20 selects the antenna groups G1 and G2 for BF based on the areas A21 and A22 where the terrestrial stations 12 and 13 are located. The antenna device 20 calculates the beam direction and weights based on the coordinates (position) and attitude of the HAPS and the positions of the terrestrial stations, and performs BF control using the planar array antennas of the selected antenna groups.

[0102] Thereby, the antenna device 20 can perform BF control following the position and attitude changes of the HAPS11. Further, the antenna device 20 divides the service area A11 into areas A21 and A22 using the planar array antennas 21 to 24 and 31 to 34 of the antenna groups G1 and G2 with different inclination angles, thereby reducing the swing angle width of BF in the inclination angle direction and suppressing the gain deviation due to the angular difference of the antenna surface with respect to the terrestrial stations 12 and 13. Also, the antenna device 20 can reduce the dynamic range of BF and reduce the power consumption. Note that in the HAPS11, since the mounted devices are driven with a limited power capacity such as the mounted battery or solar cell, reducing the power consumption is important.

[0103] (Modification Example 1) In Modification 1, when the ground station 12 is located near the boundary of areas A21 and A22 (for example, near the circle C1 in FIG. 7), the antenna device 20 does not perform BF control using the planar array antenna based on the determination of antenna groups G1 and G2. That is, when the ground station 12 is located near the boundary of areas A21 and A22, the antenna device 20 does not distinguish between antenna groups G1 and G2, and selects the planar array antenna for BF control among the planar array antennas 21 to 24 and 31 to 34.

[0104] FIG. 10 is a top view of the antenna device 20 shown in FIG. 2. In FIG. 10, the same components as those in FIG. 2 are denoted by the same reference numerals.

[0105] The control unit 71 of the antenna device 20 determines, for example, whether the ground station 12 is located within a predetermined distance from the boundary of areas A21 and A22 (for example, the circle C1 in FIG. 7) after the process of S1 described in FIG. 9.

[0106] When the control unit 71 determines that the ground station 12 is not located within a predetermined distance from the boundary of areas A21 and A22, the control unit 71 executes the processes after S2 described in FIG. 9.

[0107] On the other hand, when the control unit 71 determines that the ground station 12 is located within a predetermined distance from the boundary of areas A21 and A22, the control unit 71 acquires the position information of the HAPS 11, the position information of the ground stations 12 and 13, and the attitude information of the HAPS 11.

[0108] Based on the acquired position information and attitude information of the HAPS 11 and the position information of the ground stations 12 and 13, the control unit 71 selects a planar array antenna among the planar array antennas 21 to 24 and the planar array antennas 31 to 34, in which the normal of the antenna surface faces within a predetermined angular range in the azimuth direction with respect to the ground station 12.

[0109] That is, without distinguishing between antenna groups G1 and G2, the control unit 71 selects a planar array antenna from among the planar array antennas 21 to 24 and the planar array antennas 31 to 34, in which the normal line of the antenna surface faces within a predetermined angular range (angular ranges AZ21 to AZ24, AZ31 to AZ34 shown in FIG. 10) in the azimuth direction with respect to the ground station 12.

[0110] For example, assume that the ground station 12 is located within a predetermined distance from the boundary between areas A21 and A22 and is located within the angular range shown by the angular range AZ23 shown in FIG. 10. In this case, the control unit 71 selects the planar array antenna 23.

[0111] The control unit 71 calculates the BF weights for pointing in the direction of the ground station 12 using the selected planar array antenna.

[0112] The control unit 71 controls the BF using the calculated weights in the selected planar array antenna.

[0113] The control unit 71 determines whether or not a predetermined time has elapsed. If the predetermined time has not elapsed, the control unit 71 executes the selection process of the planar array antenna without distinguishing between antenna groups G1 and G2. If the predetermined time has elapsed, the control unit 71 determines whether or not the ground station 12 is located within a predetermined distance from the boundary between areas A21 and A22.

[0114] The antenna device 20 can suppress an increase in power consumption by the above processing. Also, the antenna device 20 can perform efficient BF control.

[0115] For example, in the vicinity of the boundary between areas A21 and A21, due to the attitude change of HAPS11, while the gainful antenna groups G1 and G2 frequently fluctuate, the difference in antenna gain between antenna group G1 and antenna group G2 is not large. Therefore, as described above, when the ground stations 12 are located near the boundary between areas A21 and A21, the antenna device 20 does not distinguish between antenna groups G1 and G2, and selects a planar array antenna for BF control from among the planar array antennas 21 to 24 and 31 to 34. Thereby, the antenna device 20 prevents a state in which a group antenna with low antenna gain is selected for a predetermined time (see S7a and S7b in FIG. 9), and suppresses an increase in power consumption. Also, the antenna device 20 can perform efficient BF control.

[0116] As described above, the control unit 71 determines whether or not the ground stations 12 and 13 are located within a predetermined distance from the boundary between area A21 and area A22. When it is determined that the ground stations 12 and 13 are located within the predetermined distance, the control unit 71 selects an array antenna facing the ground stations 12 and 13 from among the planar array antennas 21 to 24 and 31 to 34. Then, the control unit 71 performs BF control directed at the ground stations 12 and 13 using the selected planar array antenna. Thereby, the antenna device 20 can reduce power consumption and perform efficient BF control.

[0117] (Second Embodiment) FIG. 11 is a perspective view of an antenna device 80 according to the second embodiment. As shown in FIG. 11, the antenna device 80 includes planar array antennas 81 to 84 and 86 to 89.

[0118] The planar array antennas 81 to 84 have, for example, the inclination angle TA1 shown in FIG. 3A. The planar array antennas 81 to 84 form an antenna group G1.

[0119] The planar array antennas 86 to 89 have, for example, the inclination angle TA2 shown in FIG. 3B. The planar array antennas 86 to 89 form an antenna group G2.

[0120] The planar array antennas 81 to 84 of the antenna group G1 are arranged above the planar array antennas 86 to 89 of the antenna group G2.

[0121] By arranging the planar array antennas of antenna groups with different tilt angles in the vertical direction, the antenna device 80 can suppress the occupied area in the horizontal direction. Also, when the occupied area in the horizontal direction is limited under the mounting conditions of the HAPS 11, the antenna device 80 can be easily mounted on the HAPS 11.

[0122] The control unit of the antenna device 80 executes the same processing as the flowchart of FIG. 9. The control unit of the antenna device 80 performs BF control following the position and attitude changes of the HAPS 11 by using the weights of Equation (1) corresponding to the positions of the antenna elements.

[0123] As described above, the planar array antennas 81 to 84 are arranged above the planar array antennas 86 to 89. Thereby, the antenna device 80 can perform BF control following the position and attitude changes of the HAPS 11 and can suppress the occupied area in the horizontal direction.

[0124] Note that the planar array antennas 81 to 84 may be arranged below the planar array antennas 86 to 89.

[0125] Also, the number of planar array antennas 81 to 84 of the antenna group G1 and the number of planar array antennas 86 to 89 of the antenna group G2 do not have to be the same.

[0126] For example, in FIG. 11, one planar array antenna having a tilt angle TA1 may be arranged between each of the planar array antennas 81 to 84 of the antenna group G1. For example, the number of planar array antennas of the antenna group G1 may be 8 and the number of planar array antennas of the antenna group G2 may be 4.

[0127] (Third Embodiment) FIG. 12 is a perspective view of the antenna device 90 according to the third embodiment. As shown in FIG. 12, the antenna device 90 includes array antennas 91 to 94.

[0128] As shown in FIG. 12, the array antenna 91 includes planar sub-array antennas 91a to 91d. For example, the same number of antenna elements are formed in each of the sub-array antennas 91a to 91d.

[0129] The inclination angle of the lowermost sub-array antenna 91a is the largest. The inclination angle of the second sub-array antenna 91b from the bottom is the second largest. The inclination angle of the third sub-array antenna 91c from the bottom is the third largest. The inclination angle of the uppermost sub-array antenna 91d is the smallest. That is, the inclination angles of the sub-array antennas 91a to 91d become smaller as the sub-array antennas are higher.

[0130] The array antennas 92 to 94 also have sub-array antennas, similar to the array antenna 91.

[0131] The lowermost sub-array antennas of each of the array antennas 91 to 94 constitute an antenna group G1 and form a first communication area. The second sub-array antennas from the bottom of each of the array antennas 91 to 94 constitute an antenna group G2 and form a second communication area outside the first communication area. The third sub-array antennas from the bottom of each of the array antennas 91 to 94 constitute an antenna group G3 and form a third communication area outside the second communication area. The fourth sub-array antennas from the bottom of each of the array antennas 91 to 94 constitute an antenna group G4 and form a fourth communication area outside the third communication area.

[0132] The control unit of the antenna device 90 selects an antenna group corresponding to the positions of the ground stations 12 and 13 in the inclination angle direction. The control unit performs BF control using the weights of Equation (1) in the sub-array antennas of the selected antenna group.

[0133] As described above, each of the array antennas 91 to 94 has sub-array antennas that form different communication areas on the ground. Thereby, the antenna device 90 can reduce the number of operating RF units (for example, refer to the RF units 51-1, 51-2, …, 5M-N in FIG. 5), and can reduce power consumption.

[0134] In FIG. 12, a configuration example in which the tilt angles of the sub-array antennas increase in order from the top is shown, but the sub-array antennas may be configured such that the tilt angles increase in order from the bottom.

[0135] (Fourth Embodiment) FIG. 13 is a diagram showing a block configuration example of an antenna device 20 according to the fourth embodiment. As shown in FIG. 13, the antenna device 20 includes an RF unit 101, SW (switches) 103a and 103b, a TX-H line (H-polarization transmission line) 104a, an RX-H line (H-polarization reception line) 104b, a TX-V (V-polarization transmission line) line 105a, an RX-V (V-polarization reception line) line 105b, an RF-BB conversion unit 106, and a baseband unit 111.

[0136] The RF unit 101 includes antenna elements 41 of P(m,n) and RF units 102a and 102b. Each of the RF units 102a and 102b includes a transceiver, a PA (power amplifier), and an LNA (low noise amplifier).

[0137] The transceiver of the RF unit 102a is connected to the H-polarization terminal of the antenna element 41. The PA of the RF unit 102a is connected to the TX-H line 104a when SW103a is turned on. The LNA of the RF unit 102a is connected to the RX-H line 104b when SW103a is turned on.

[0138] The transceiver of the RF unit 102b is connected to the V-polarization terminal of the antenna element 41. The PA of the RF unit 102b is connected to the TX-V line 105a when SW103b is turned on. The LNA of the RF unit 102b is connected to the RX-V line 105b when SW103b is turned on.

[0139] The RF-BB conversion unit 106 includes an upconverter 107a, a DAC (Digital to Analog Converter) 108a, a downconverter 109a, and an ADC (Analog-to-Digital Converter) 110a. The RF-BB conversion unit 106 also includes an upconverter 107b, a DAC 108b, a downconverter 109b, and an ADC 110b.

[0140] The upconverter 107a is connected to the TX-H line 104a when SW103a is turned on. Therefore, the PA of the RF unit 102a is connected to the upconverter 107a and disconnected from the upconverter 107a depending on the on and off states of SW103a.

[0141] The downconverter 109a is connected to the RX-H line 104b when SW103a is turned on. Therefore, the LNA of the RF unit 102a is connected to the downconverter 109a and disconnected from the downconverter 109a depending on the on and off states of SW103a.

[0142] The upconverter 107b is connected to the TX-V line 105a when SW103b is turned on. Therefore, the PA of the RF unit 102b is connected to the upconverter 107b and disconnected from the upconverter 107b depending on the on and off states of SW103b.

[0143] The downconverter 109b is connected to the RX-V line 105b when SW103b is turned on. Therefore, the LNA of the RF unit 102b is connected to the downconverter 109b and disconnected from the downconverter 109b depending on the on and off states of SW103b.

[0144] The H-polarization transmission digital signal output from the baseband unit 111 is converted into an analog signal by the DAC 108a. The analog signal is converted into an RF frequency band signal by the upconverter 107a.

[0145] The V-polarization transmission digital signal output from the baseband unit 111 is converted into an analog signal by the DAC 108b. The analog signal is converted into a signal in the RF frequency band by the upconverter 107b.

[0146] The H-polarization reception signal transmitted through the RX-H line 104b is converted into a baseband signal by the downconverter 109a. The baseband signal is converted into an H-polarization reception digital signal by the ADC 110a. The H-polarization reception digital signal is output to the baseband unit 111.

[0147] The H-polarization reception signal transmitted through the RX-H line 105b is converted into a baseband signal by the downconverter 109b. The baseband signal is converted into an H-polarization reception digital signal by the ADC 110b. The H-polarization reception digital signal is output to the baseband unit 111.

[0148] The baseband unit 111 performs baseband processing on the signals transmitted to the terrestrial stations 12 and 13. The baseband unit 111 also performs baseband processing on the signals received from the terrestrial stations 12 and 13.

[0149] The antenna device 20 has M×N RF-BB conversion units 106. That is, the antenna device 20 has RF-BB conversion units 106 corresponding to the number of antenna elements of one planar array antenna. To each of the RF-BB conversion units 106 corresponding to the number of antenna elements of one planar array antenna, an RF unit 101 having an antenna element with a corresponding position in each of the planar array antennas 21 to 24 and 31 to 34 is connected via an SW.

[0150] For example, an RF unit 101 having the P(1,1) antenna elements of the planar array antennas 21 to 24 and 31 to 34 is connected to the first RF-BB conversion unit 106 via an SW. An RF unit 101 having the P(1,2) antenna elements of the planar array antennas 21 to 24 and 31 to 34 is connected to the second RF-BB conversion unit 106 via an SW. An RF unit 101 having the P(1,3) antenna elements of the planar array antennas 21 to 24 and 31 to 34 is connected to the third RF-BB conversion unit 106 via an SW. Similarly hereinafter, an RF unit 101 having the P(M,N) antenna elements of the planar array antennas 21 to 24 and 31 to 34 is connected to the M-Nth RF-BB conversion unit 106 via an SW.

[0151] Then, for example, the M×N RF units of the planar array antennas selected in S4a and S4b of FIG. 9 are connected to the M×N RF-BB conversion units 106 by on and off control of the SW.

[0152] That is, the M×N RF-BB conversion units 106 are connected via an SW to the M×N antenna elements (RF units) in the selected planar array antenna among the planar array antennas 21 to 24 and 31 to 34.

[0153] The control unit 71 selects the planar array antennas 21 to 24 and 31 to 34 in BF control. The control unit 71 switches the connection of the TX signal and the RX signal to the RF units corresponding to the selected planar array antennas by the SWs 103a and 103b. For example, the control unit 71 switches the on and off of the SWs 103a and 103b according to the selection of the planar array antennas in S4a and 4b of FIG. 9. Thereby, a beam in the directions of the ground stations 12 and 13 is formed.

[0154] As described above, in the antenna device 20, the RF-BB conversion units 106 that convert the frequency of the signal are shared in each of the antenna elements of the planar array antennas 21 to 24 and 31 to 34. Thereby, the antenna device 20 can reduce the power consumption.

[0155] In the above description, the block configuration example of the antenna device 20 has been described. However, the block configuration example in FIG. 13 can also be applied to the antenna devices 80 and 90.

[0156] In the above-described embodiments, the notation "··· section" used for each component may be replaced with other notations such as "··· circuitry", "··· assembly", "··· device", "··· unit", or "··· module".

[0157] As described above, the embodiments have been described with reference to the drawings. However, the present disclosure is not limited to such examples. It is obvious that those skilled in the art can conceive of various modification examples or correction examples within the scope described in the claims. Such modification examples or correction examples are also understood to belong to the technical scope of the present disclosure. Also, within the scope not departing from the gist of the present disclosure, the components in the embodiments may be arbitrarily combined.

[0158] The present disclosure can be realized by software, hardware, or software in cooperation with hardware. Each functional block used in the description of the above embodiments is realized as an LSI which is an integrated circuit, partially or entirely, and each process described in the above embodiments may be controlled partially or entirely by one LSI or a combination of LSIs. The LSI may be composed of individual chips, or may be composed of one chip so as to include a part or all of the functional blocks. The LSI may be provided with data input and output. Depending on the degree of integration, the LSI may also be referred to as an IC, a system LSI, a super LSI, or an ultra LSI.

[0159] The method of integrating circuits is not limited to LSIs, and it may also be realized by dedicated circuits, general-purpose processors, or dedicated processors. Further, after manufacturing the LSIs, FPGAs (Field Programmable Gate Arrays) that can be programmed, or reconfigurable processors that can reconfigure the connections and settings of circuit cells inside the LSIs may be used. This disclosure may be realized as digital processing or analog processing.

[0160] Furthermore, if a technology for integrating circuits that replaces LSIs appears due to the progress of semiconductor technology or another derived technology, naturally, the integration of functional blocks may be performed using that technology. The application of biotechnology, etc. is a possible example.

Industrial Applicability

[0161] This disclosure can be applied to a relay device that floats in the air and relays communication between terrestrial wireless stations.

Explanation of Signs

[0162] 1 Communication system 11 HAPS 12, 13 Terrestrial stations 20 Antenna device 21~24, 31~34 Planar array antennas 41 Antenna element 51-1, 51-2, …, 5M-N RF units 61, 62 Transceivers 63 Baseband section 64 I / F section 71 Control section 72 Signal processing section 72a, 72b Terrestrial station processing sections 73 I / F section 80 Antenna device 81~84, 86~89 Planar array antennas 90 Antenna device 91~94 Array antennas 91a~91d Sub-array antennas

Claims

1. An antenna device mounted on an airborne communication device, a first array antenna arranged in a ring shape to form a first communication area on the ground; a second array antenna arranged in a ring shape to form a second communication area different from the first communication area; a control unit that determines whether the ground station is located in the first communication area or the second communication area based on position information and attitude information of the antenna device and position information of a ground station; An antenna device having the above configuration.

2. the first array antenna includes a plurality of first planar array antennas having a first depression angle; the second array antenna includes a plurality of second planar array antennas having a second depression angle; 2. The antenna device according to claim 1.

3. The plurality of first planar array antennas and the plurality of second planar array antennas are arranged alternately in a circular shape.

3. The antenna device according to claim 2.

4. the second planar array antennas are disposed above or below the first planar array antennas; 3. The antenna device according to claim 2.

5. The control unit is When it is determined that the ground station is located in the first communication area, performing beamforming control toward the ground station using the first array antenna; When it is determined that the ground station is located in the second communication area, the second array antenna is used to perform beamforming control toward the ground station.

2. The antenna device according to claim 1.

6. The control unit is determining whether the ground station is located within a predetermined distance from a boundary between the first communication area and the second communication area; When it is determined that the ground station is located within the predetermined distance, an array antenna that faces the ground station is selected from the first array antenna and the second array antenna; Using the selected array antenna, perform beamforming control toward the ground station.

2. The antenna device according to claim 1.

7. a frequency converter that converts a frequency of a signal is shared between antenna elements in each of the plurality of first planar array antennas and antenna elements in each of the plurality of second planar array antennas; 3. The antenna device according to claim 2.

8. The first array antenna and the second array antenna are configured as digital phased arrays.

2. The antenna device according to claim 1.

9. The first array antenna and the second array antenna are configured as analog phased arrays.

2. The antenna device according to claim 1.

10. The first array antenna and the second array antenna are configured as an analog phased array and a digital phased array.

2. The antenna device according to claim 1.

11. An antenna device mounted on an airborne communication device, a first subarray antenna arranged in a ring shape to form a first communication area on the ground; an array antenna having a second subarray antenna arranged in a ring shape and forming a second communication area different from the first communication area; a control unit that determines whether the ground station is located in the first communication area or the second communication area based on position information and attitude information of the antenna device and position information of a ground station; An antenna device having the above configuration.

Images