Array antenna device and method for arranging array antenna device

Abstract

To determine the placements of phase shifters by considering the placement positions of antenna elements of an array antenna device.SOLUTION: According to an embodiment, an array antenna device 10 includes an array part including a plurality of antenna elements a1 to a8 arranged from one end to the other end, continuous variable phase shifters 16 connected to the plurality of antennas, respectively to control the directivity of the array part, and step phase shifters 15 for adding a phase of 2π×n (n is 0 or a positive integer) so as to give a larger phase to a radio signal to be outputted from the antenna elements arranged at the ends than a radio signal to be outputted from the antenna element arranged at the center.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an array antenna device and an arrangement method thereof. [Background technology]

[0002] Beamforming is one technology that effectively utilizes frequency bands. Beamforming is a technology that emits directional radio waves to maintain signal quality while suppressing interference with other wireless systems, enabling wireless communication with a specified communication target.

[0003] A typical method for achieving beamforming is phased array technology, which adjusts the phase of radio signals fed to multiple antenna elements at the transmitter and combines the radio waves radiated from each antenna element in space to strengthen the signal in the desired direction.

[0004] A phased array antenna device includes multiple antenna elements spaced at equal intervals from one end to the other. Such antenna devices use phase shifters to adjust the phase of the signal, thereby changing the beam direction of the radio waves emitted from the antenna elements. Phase shifters are relatively expensive, so providing a phase shifter for each of the multiple antenna elements increases the cost of the antenna device itself.

[0005] Therefore, Patent Documents 1 and 2 disclose techniques for reducing the number of phase shifters. In the antenna device of Patent Document 1, a first phase shifter is shared by at least two adjacent antenna elements at one end of the antenna array to control the signal phase in a first group consisting of these antenna elements. Also, a second phase shifter is shared by at least two adjacent antenna elements at the other end of the antenna array to control the signal phase in a second group consisting of these antenna elements. Also, for at least several central antenna elements between the first and second groups, individual phase shifters are connected to the central antenna elements, respectively.

[0006] Patent Document 2 describes an antenna device including a power distribution phase adjuster consisting of a divider that divides a signal from a signal generator into two and a phase shifter that adjusts the phase of one of the two output signals of the divider, and a plurality of antenna elements provided corresponding to each of the two outputs of the power distribution phase adjuster.

[0007] Furthermore, Patent Documents 3 and 4 describe antenna devices that have digital phase shifters connected to all antenna elements and analog phase shifters connected to only a limited number of antenna elements, thereby achieving precise beam control. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-100257 [Patent Document 2] Japanese Utility Model Application Publication No. 04-038102 [Patent Document 3] Japanese Patent Application Publication No. 03-165105 [Patent Document 4] Japanese Patent Application Publication No. 02-090804 Summary of the Invention [Problem to be solved by the invention]

[0009] With phased array technology, when receiving, the radio signals received by each antenna element are given a phase difference using a phase shifter before being combined. When transmitting, the radio signal is divided, and each divided radio signal is given a phase difference using a phase shifter before being supplied to each antenna element. The value of the phase difference of the radio signal for each antenna element before combination or after division is determined by the beam direction. For this reason, depending on the beam direction, the phase to be given to the radio signal may exceed 360°.

[0010] However, the range of the phase imparted by a phase shifter is 0 to 360°. Therefore, when the phase to be imparted to a radio signal exceeds 360°, the phase imparted to the radio signal is offset by 360°. Usually, the phase imparted to a radio signal varies depending on the arrangement position of the antenna elements. For example, when antenna elements are arranged linearly from one end to the other, the outer antenna elements, i.e., the antenna elements at both ends, require a greater 360° offset. In the above-mentioned patent documents, the arrangement position of the antenna elements is not taken into consideration when determining the arrangement of the phase shifters.

[0011] An object of the present disclosure is to provide an array antenna device and a method for determining the layout of an array antenna device in which the layout positions of antenna elements are taken into consideration when determining the layout of phase shifters. [Means for solving the problem]

[0012] An array antenna device according to one embodiment includes an array section including a plurality of antenna elements arranged from one end to the other end, variable phase shifters connected to each of the antenna elements to control the directivity of the array section, and a step phase shifter that adds a phase of 2π×n (n is 0 or a positive integer) so that a radio signal output from an antenna element arranged at the end has a larger phase than a radio signal output from an antenna element arranged in the center.

[0013] One embodiment of an array antenna device arrangement method includes a plurality of antenna elements arranged from one end to the other end, and is capable of controlling the directivity of a radio signal. Step phase shifters are arranged to add a phase of 2π×n (n is 0 or a positive integer) so that a larger phase is imparted to the radio signal output from the antenna elements arranged at the end than to the radio signal output from the antenna element arranged in the center. [Effects of the Invention]

[0014] According to the above aspect, the layout of the phase shifter can be determined in consideration of the layout position of the antenna element. [Brief explanation of the drawings]

[0015] [Figure 1] 10A and 10B are diagrams illustrating a flow for determining the phase control amount to be set in each phase adjustment unit based on the beam radiation direction in an array antenna device. [Figure 2] 1 is a diagram illustrating a portion of the configuration of an array antenna device according to a first embodiment. [Figure 3] 10 is a table showing a phase control amount to be set in a step phase shifter when the phase control amount is changed. [Figure 4] FIG. 10 is a diagram illustrating a part of the configuration of an array antenna device according to a second embodiment. [Figure 5] FIG. 10 is a diagram illustrating another example of the array antenna device according to the second embodiment. [Figure 6] FIG. 10 is a diagram illustrating another example of the array antenna device according to the second embodiment. [Figure 7] FIG. 1 is a diagram illustrating a related art. [Figure 8] FIG. 1 is a simplified conceptual diagram showing the waveform of individual beams radiated from each antenna element and the overall beam synthesized from these beams in the related art. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In each drawing, the same or corresponding elements are designated by the same reference numerals, and for clarity of explanation, duplicate explanations will be omitted as necessary.

[0017] The present invention relates to an array antenna device having an adjustable direction of beamforming, which includes a plurality of array sections each including an antenna element and a phase adjustment section. In such an array antenna device, by providing a predetermined phase difference between signals transmitted and received by a plurality of equally spaced antenna elements, it is possible to specify the intensities at which the signals are mutually enhanced in any direction.

[0018] The phases to be imparted to the radio signals output from the antenna elements are determined based on overall radio signal information transmitted and received by the array antenna device, as well as phase control information for controlling the phases of individual radio signals transmitted and received by each antenna element. Hereinafter, the beam radiated by the array antenna device may be referred to as an overall beam, and the beams radiated by each of the multiple antenna elements may be referred to as individual beams.

[0019] First, the related art will be described with reference to Fig. 7. In the example shown in Fig. 7, antenna elements a1 to a4 are arranged at equal intervals d. Phase adjustment units p1 to p4 are connected to the antenna elements a1 to a4, respectively. The phase control amount of the phase adjustment units p1 to p4 is set to any value within the range of 0° to 360°. The phase adjustment units p1 to p4 gradually delay the signal for each of the antenna elements a1 to a4 to align the phase of the signal output from each antenna element. This allows the array antenna device to radiate a directional beam in which signals enhance each other in a predetermined beam radiation direction.

[0020] The angle between the front direction of the array antenna device and the beam radiation direction is defined as θ (hereinafter referred to as the beam radiation angle θ). The phase difference Δφ of the signals output from adjacent antenna elements is expressed as 2πd / λ×sinθ. For example, when the antenna spacing d is λ / 2 (λ is the wavelength) and the beam radiation angle θ is to be set to 60°, phase adjustment units p1 to p4 delay the phase of the signals output from each antenna by approximately 155.9° from antenna element a1 toward antenna element a4.

[0021] Here, as the number of antenna elements increases, the amount of phase delay applied to the signal may exceed 360°. For antenna element a4 in Figure 7, the delay is approximately 467.7°, which is three times the approximately 155.9°. However, since phase adjustment units p1 to p4 can only apply phases between 0 and 360°, the amount of delay applied to the individual beam radiated from antenna element a4 is offset by 360°, making it approximately 107.7°.

[0022] In this case, the delay of the individual beam emitted from antenna element a4 is insufficient by 2π, so it is output 1 / fc (fc is the carrier frequency) earlier. Figure 8 shows the signals output from each of antenna elements a1 to a4 and the waveform of the signal obtained by combining these. Figure 8 is an image diagram that shows a simplified representation of signal changes in order to explain how phase delay affects signals. As shown in Figure 8, the overall beam is a composite wave of the individual beams of each of antenna elements a1 to a4, so the waveform of the overall beam changes as a result of the offset individual beams being superimposed.

[0023] Typically, data is judged based on the signal state for each symbol length. The sampling timing for data judgment is the time when the signal trajectory (eye pattern) is most open. As mentioned above, when the signal waveform changes due to a phase offset, the eye pattern is distorted, affecting the bit error rate. If the frequency at which the symbols are changed is high relative to the carrier frequency, the symbol rate increases, and bit errors due to deterioration of the eye pattern become more pronounced. Furthermore, if the frequency at which the symbols are changed is increased in order to increase signal transmission capacity, the above problems arise, creating a dilemma.

[0024] In an array antenna device in which multiple antenna elements are arranged in a straight line from one end to the other, the antenna elements located at both ends require a larger 360° offset than the antenna elements located in the center, so multiple continuously variable amplifiers are required. However, providing many continuously variable amplifiers increases the size of the array antenna device 10, resulting in increased costs. Therefore, in the embodiment described below, the placement of the phase shifters is determined taking into account the placement positions of the antenna elements.

[0025] First, with reference to Fig. 1, a flow for determining the phase control amount (amount of phase delay) of each phase adjustment unit based on the beam radiation direction in an array antenna device 10 will be described. As shown in Fig. 1, the array antenna device 10 includes antenna elements a1 to a4, phase adjustment units p1 to p4, a beam control unit 11, a branching circuit 14, an RF (Radio Frequency) processing unit 13, and a signal processing unit 12. Here, a transmission system will be described that modulates a transmission signal, distributes it to each of the antenna elements a1 to a4, and outputs beams.

[0026] The signal processing unit 12 includes a modulator, a DAC, etc. The signal processing unit 12 modulates the transmission signal into a radio wave format that can be demodulated by the communication partner, and transmits it to the RF processing unit 13. The RF processing unit 13 performs analog processing such as frequency conversion of an IF (Intermediate Frequency) signal into an RF signal and removal of unnecessary waves by filtering, and inputs the processed signal to a branching circuit 14.

[0027] The branching circuit 14 is equipped with a distributor at each branching point. At each branching point, the branching circuit 14 branches the input signal into two and distributes them to each of the phase adjustment units p1 to p4. The beam control unit 11 generates the above-mentioned phase control information and transmits it to each of the phase adjustment units p1 to p4. Here, the phase control information is information for controlling the phase of the individual beam received by each of the antenna elements a1 to a4 in accordance with the direction of the received overall beam. The beam control unit 11 may be, for example, a single digital IC such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit), or may be an analog IC including various active elements.

[0028] The phase adjustment units p1 to p4 set the phase of each received signal to a phase value specified by the phase control information in accordance with the phase control information transmitted from the beam control unit 11. That is, the phase adjustment units p1 to p4 impart a predetermined phase difference to the signals from the corresponding antenna elements a1 to a4. As will be described later, the phase adjustment units p1 to p4 each include a step phase shifter 15 and a continuously variable phase shifter 16.

[0029] The antenna elements a1 to a4 radiate the signals input from the phase adjustment units p1 to p4 into space at a predetermined beam radiation angle. Each of the antenna elements a1 to a4 may include an amplifier such as a low-noise amplifier.

[0030] In the array antenna device 10 shown in Fig. 1, first, the beam radiation direction is determined, and then a beam direction instruction is generated. For example, when the array antenna device 10 is applied to an artificial satellite or a ground station, the beam radiation direction of the entire beam can be determined based on angle information of the communication partner using its own tracking function, etc. The beam direction instruction is input to the beam control unit 11.

[0031] Upon receiving a beam direction instruction, the beam control unit 11 calculates the phase control amount for each phase adjustment unit p1 to p4, generates phase control information, and outputs it to each phase adjustment unit p1 to p4. The phase adjustment units include a step phase shifter, a continuously variable phase shifter, a variable attenuator, etc. Each component of the phase adjustment unit imparts a predetermined phase value to the transmission signal based on the phase control information. This causes individual beams to be emitted from the antenna elements at specified beam emission angles. In this way, the phase control amount for each phase adjustment unit is determined according to the beam emission direction.

[0032] <Embodiment 1> FIG. 2 is a diagram showing a part of the configuration of the array antenna apparatus according to the first embodiment. In the first embodiment, 16 antenna elements are arranged in a line from one end to the other. In the following explanation, eight antenna elements a1 to a8, which are half the total from the center, will be explained as representatives. Antenna elements a1 to a8 are shown in FIG. 2. Antenna element a1 is the element arranged in the center, and antenna element a8 is the element arranged on the outside. Similarly, to the left of antenna element a1 in FIG. 2, eight antenna elements are arranged in order, with antenna element a1 on the center and antenna element a8 on the outside. Similarly, the other components are arranged symmetrically with respect to the center line passing through the center of the row in which the multiple antenna elements ANT are arranged.

[0033] The array antenna device 10 includes antenna elements, a phase adjustment unit, and a branching circuit 14. The phase adjustment unit includes a step phase shifter 15 and a continuously variable phase shifter 16. In the first embodiment, one continuously variable phase shifter 16 is connected to each of the multiple antenna elements. Furthermore, a step phase shifter 15 is connected to each of the multiple continuously variable phase shifters 16. A divider is disposed at each branch point of the branching circuit 14, and the signal is branched into two at each divider and input to each step phase shifter 15.

[0034] As described above, the step phase shifter 15 connected to the outer antenna element a8 requires a larger phase control amount. Therefore, the step phase shifter 15 adds a phase delay of 2π×n (n is 0 or a positive integer) to the transmission signal so as to impart a larger phase to the radio signal output from the antenna element a8 located at the edge than to the radio signal output from the antenna element a1 located in the center. The step phase shifter 15 can set a 360°×n (n is 0 or a positive integer) phase control amount of 0°, 360°, 720°, and so on. In other words, the step phase shifter 15 can select n+1 states of 1, 2π, 2π×2, 2π×3, and so on.

[0035] This step phase shifter 15 has a simpler structure and is easier to control than the continuously variable phase shifter 16. For example, when setting either 0° or 360°, the phase control amount of the step phase shifter 15 can be set with a 1-bit signal.

[0036] For example, when the phase control amount is changed so that the beams output from antenna elements a1 to a8 are delayed by 155° each, the phase control amount to be set in step phase shifter 15 in 2π steps is counted as shown in Fig. 3. As mentioned above, the phase control amount set in step phase shifter 15 is expressed as 2π × n (n is 0 or a positive integer). The value of n is shown in Fig. 3. As shown in Fig. 3, when considering the cases where the beam is swung to the right and the left, the required maximum phase control amount is smaller closer to the center of the antenna element, and becomes larger toward the outside.

[0037] 3, the phase delay amounts given to the signal are 3θ, 3θ, 4θ, 4θ, 5θ, 5θ, 6θ, and 6θ (θ=2π) in order from the center to the outside (antenna elements a1 to a8). Therefore, the phase control amounts set in each step phase shifter 15 are 3θ, 3θ, 4θ, 4θ, 5θ, 5θ, 6θ, and 6θ (θ=2π) in order from the center to the outside.

[0038] The continuously variable phase shifter 16 can continuously control the phase from 0 to 360°. The continuously variable phase shifter 16 controls the directivity of the array section, thereby controlling the directivity of the beam output from the antenna element. In this way, by arranging the step phase shifters 15 in consideration of the maximum phase control amount required for each antenna element, the number of continuously variable phase shifters can be reduced, and an increase in costs can be suppressed.

[0039] <Embodiment 2> Fig. 4 is a diagram showing the configuration of an array antenna device according to a second embodiment. In Fig. 4, the same components as those in the above-described embodiments are given the same reference numerals, and description thereof will be omitted. In the second embodiment, a step phase shifter 15 is arranged in one branch path at each branch point of the branch circuit 14. As in Fig. 2, in Fig. 4 as well, of the 16 antenna elements ANT arranged linearly from one end to the other, eight antenna elements a1 to a8 in the central half (one side of the center line) will be described as representatives.

[0040] As shown in FIG. 4, the branch circuit 14 includes a first branch point b1 that distributes a radio signal to the two antenna elements of each pair when the antenna elements adjacent to the center line are divided into pairs of two, a second branch point b2 that distributes a radio signal to the two first branch points, and a third branch point b3 that distributes a radio signal to the two second branch points.

[0041] At each of the branch points b1 to b3, a step phase shifter 15 is placed on the side farther from the center line in accordance with the phase control amount determined based on the phase control information. At the first branch point b1, a step phase shifter 15 is placed on the side farther from the center line, where the step phase shifter 15 is placed.n1 (n1 is 0 or a positive integer) is placed on the side farther from the center line of the first branch point b1. In the example of Fig. 4, a step phase shifter 15a set to a phase control amount of θ(2π) is placed on the side farther from the center line of the first branch point b1.

[0042] The second branch point b2 is located on the far side of the center line, 2π × 2 n2 In the example of FIG. 4, a step phase shifter 15b set to a phase control amount of 2θ (4π) is arranged on the side farther from the center line of the second branch point b2. Then, a step phase shifter 15b set to a phase control amount of 2θ (4π) is arranged on the side farther from the center line of the second branch point b2. Then, a step phase shifter 15b set to a phase control amount of 2π × 2 n3 A third step phase shifter that imparts a phase (integer n3>n2) is disposed. In the example of Fig. 4, a step phase shifter 15c that is set to a phase control amount of 4θ (8π) is disposed on the side farther from the center line of the third branch point b3.

[0043] In this way, the phase control amount for each branch is θ, 2θ, . n θ, ..., the signal delay amount for each antenna element a can be increased by θ. Note that it is also possible to change the signal delay amount for each antenna element a by adjusting the phase control amount of the step phase shifter 15 arranged on only one side of each branch.

[0044] 5, step phase shifter 15a with a phase control amount of θ(2π) is arranged on the side farther from the center line of first branch point b1, step phase shifter 15b with a phase control amount of θ(2π) is arranged on the side farther from the center line of second branch point b2, and step phase shifter 15c with a phase control amount of 2θ(4π) is arranged on the side farther from the center line of third branch point b3. By arranging in this manner, the signal delay amount for each antenna element a can be set to 0, θ, θ, 2θ, 2θ, 3θ, 3θ, and 3θ.

[0045] 6, step phase shifter 15a with a phase control amount of 0 is arranged on the side farther from the center line of first branch point b1, step phase shifter 15b with a phase control amount of θ (2π) is arranged on the side farther from the center line of second branch point b2, and step phase shifter 15c with a phase control amount of 2θ (4π) is arranged on the side farther from the center line of third branch point b3. By arranging in this manner, the signal delay amount for each antenna element a can be set to 0, 0, θ, θ, 2θ, 2θ, 3θ, and 3θ.

[0046] In this way, by arranging the step phase shifter 15 on only one side of each branch, the amount of signal delay can be increased as the step phase shifter 15 approaches the branch on the side where it is located.

[0047] As described above, by arranging the two-step 0 / 360° step phase shifter 15 in addition to the continuously variable phase shifter 16 so as to impart a larger phase to the radio signal output from the antenna element arranged at the end than to the radio signal output from the antenna element arranged in the center, the number of phase shifters required can be reduced, and the cost of the array antenna device 10 can be reduced.

[0048] In the embodiment, an example in which a plurality of antenna elements are arranged in a line has been described, but the present invention is not limited to this. For example, the above technology can be applied to a case in which a plurality of antenna elements are arranged in a matrix. The above technology can also be applied to an example of a receiving system in which beams are received by each antenna element and the received beams are combined and demodulated.

[0049] The present disclosure is not limited to the above-described embodiments, and may be modified as appropriate without departing from the spirit and scope of the present disclosure. In addition, the present disclosure may be implemented by appropriately combining the respective embodiments. [Explanation of symbols]

[0050] 10 Array antenna device 11 Beam control section 12 Signal Processing Section 13 RF processing section 14 Branch Circuit 15-step phase shifter 16 Continuously variable phase shifter a Antenna element p Phase adjustment section b1 First branch point b2 Second branch point b3 Third branch point

Claims

1. an array unit including a plurality of antenna elements arranged from one end to the other end; a variable phase shifter connected to each of the plurality of antenna elements to control the directivity of the array unit; a step phase shifter that adds a phase of 2π×n (n is 0 or a positive integer) so that a radio signal output from an antenna element arranged at an end has a phase greater than that of a radio signal output from an antenna element arranged at the center; Including, Array antenna device.

2. the phases to be imparted to the radio signals output from the antenna elements are determined based on phase control information for controlling the phases of individual radio signals transmitted and received by each antenna element, based on information on all radio signals transmitted and received by the array antenna device.

2. The array antenna device according to claim 1.

3. The plurality of antenna elements are arranged symmetrically with respect to a center line, a first branch point that distributes a radio signal to two antenna elements of each pair when the antenna elements are divided into pairs in order starting from adjacent to the center line on one side of the center line, and a second branch point that distributes a radio signal to the two first branch points; In accordance with the phase determined based on the phase control information, the step phase shifter is disposed on a side farther from the center line at the first branch point; The step phase shifter is disposed on a side farther from the center line at the second branch point.

3. The array antenna device according to claim 2.

4. The plurality of antenna elements are arranged symmetrically with respect to a center line, a first branch point that distributes a radio signal to two antenna elements of each pair when the antenna elements are divided into pairs in order starting from adjacent to the center line on one side of the center line, and a second branch point that distributes a radio signal to the two first branch points; In accordance with the phase determined based on the phase control information, At the first branch point, 2π×2 ｎ１ a first step phase shifter for imparting a phase of n (n is 0 or a positive integer); At the second branch point, 2π×2 ｎ２ A second step phase shifter is provided to impart a phase (integer n2>n1).

3. The array antenna device according to claim 2.

5. At a third branch point that distributes the radio signal to the two second branch points, 2π×2 ｎ３ A third step phase shifter is further provided to impart a phase of (an integer n3>n2).

5. The array antenna device according to claim 4.

6. A method for arranging an array antenna device including a plurality of antenna elements arranged from one end to the other end, the array antenna device being capable of controlling the directivity of a radio signal by variable phase shifters connected to the plurality of antenna elements, the method comprising: Step phase shifters that add a phase of 2π×n (n is 0 or a positive integer) are arranged so as to impart a larger phase to the radio signal output from the antenna elements arranged at the end than to the radio signal output from the antenna element arranged in the center. A method for arranging an array antenna device.

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