Reception directivity control device and reception directivity control method

Abstract

For each combination of single-sideband components for which the column positions are the same, the present invention imparts phase inclination for aligning phases for each row-direction component in a beam formation direction to each of the single-sideband components included in each of the combinations and carries out synthesis, in consideration of a difference in row position corresponding to each of the row-direction components and a row-direction phase inclination that occurs in accordance with each beam formation direction, to thereby generate a row-direction combined optical signal that corresponds to each of the row-direction components in the beam formation direction. The present invention also converts the frequency of the generated row-direction combined optical signal so that the frequency is differentiated for each of the row-direction components in the beam formation direction. The present invention additionally imparts phase inclination for aligning phases for each column-direction component in the beam formation direction to each of the converted row-direction combined optical signals and carries out synthesis, in consideration of a difference in column position corresponding to each of the column-direction components and a column-direction phase inclination that occurs in accordance with each beam formation direction, to thereby generate a column-direction combined optical signal that corresponds to each of the column-direction components in the beam formation direction.

Description

[Technical Field]

[0001] The present invention relates to a receiving directivity control device and a receiving directivity control method. [Background technology]

[0002] To achieve faster and larger capacity wireless communications, the use of high-frequency bands, such as millimeter waves, is being promoted. However, the spatial propagation loss of radio waves increases as the frequency increases. For example, free-space propagation loss increases in proportion to the square of the frequency. Therefore, high-gain antennas are often used in high-frequency bands. Because high-gain antennas have high directivity, it is necessary to align the antenna beam with the location of the other station in the wireless communication. When the other station moves, beam steering, a method for dynamically adjusting the beam direction to match the movement of the other station, is also required. Beam steering is required not only for wireless communications but also for applications such as radar, imaging, and wireless power transmission.

[0003] As beam steering means, various methods have been proposed and are currently in use, including mechanical control of the antenna direction and control of the radio waves emitted from the antenna by refracting or reflecting them using movable lenses or reflectors. However, these methods involve mechanical structures, which pose problems in terms of durability and tracking ability. For this reason, phased array antennas, which do not involve mechanical structures and are suitable for reducing the size and weight of antennas, have come into widespread use in recent years.

[0004] In a phased array antenna, beam steering is performed, for example, as follows: A plurality of antenna elements are arranged on a line or a plane, and variable delay circuits and variable attenuator circuits are connected to the plurality of antenna elements. In addition to the variable delay circuits and variable attenuator circuits, digital signal processing and the like are further used to control the phase and amplitude of the RF (Radio Frequency) signal fed to each of the plurality of antenna elements, thereby weighting the RF signal. This makes it possible to perform electronic beam steering in a phased array antenna. Note that phased array antennas that perform weighting using analog circuits are widely used in fifth-generation mobile communication systems and millimeter-wave wireless LAN (Local Area Network) systems that use millimeter-wave bands.

[0005] As the range of utilized high-frequency bands expands, higher antenna gains are required, and phased array antennas that weight a larger number of antenna elements are expected to be needed. For example, Non-Patent Document 1 discloses a configuration method for a 256-element phased array antenna used in fifth-generation mobile communication base stations in the 28 GHz band. For sixth-generation mobile communications, which aim to provide even faster transmission rates, the use of the 300 GHz band, or the so-called terahertz band, is being considered. When radio frequencies become about 10 times higher than those in the 28 GHz band, free-space path loss increases by 100 times. In other words, free-space path loss increases by 20 dB. In this case, it is expected that more than 10,000 antenna elements will be required to compensate for the 20 dB increase in free-space path loss with the base station's antenna gain.

[0006] To minimize the power loss in antenna elements, it is necessary to minimize the RF transmission line between the antenna element and the phase shifter circuit. Therefore, particularly in high-frequency phased array antennas, such as those in the millimeter-wave band, phase shifter circuits are typically placed near each antenna element. However, as the radio frequency increases, the antenna element spacing narrows, making it difficult to place multiple phase shifter circuits at the same spacing as the antenna element spacing. For example, at a radio frequency of 300 GHz, the free-space wavelength is 1 mm, so the antenna element spacing is typically half the wavelength, or 0.5 mm. Furthermore, to create a circuit that forms multiple beams, i.e., a multi-beam forming circuit, the same number of phase shifters as the number of beams must be arranged in parallel, further complicating the placement.

[0007] Therefore, for example, Non-Patent Document 2 proposes a method of applying optical circuit manufacturing technology that can implement low-loss waveguides in a compact form, converting signals into light, and then performing weighting using an optical circuit. This method has a high potential for configuring a two-dimensional weighting circuit for a multi-element phased array antenna. However, with this method, the number of components in the weighting circuit increases depending on the number of antenna elements. Therefore, measures are needed to suppress the increase in the number of components even when the number of antenna elements increases. For example, the following means have been disclosed as existing technologies for performing weighting using optical circuits.

[0008] Patent Document 1 discloses an "optically controlled array antenna device" that controls two-dimensional multi-beams using a wavelength dispersion line. Figures 1 and 2 of Patent Document 1 show the configuration of an optically controlled array antenna according to a first embodiment and the configuration of a second multi-beam forming means according to a second embodiment, respectively. The technology disclosed in Patent Document 1 provides phase tilts in the horizontal and vertical planes by using a wavelength tunable light source and a line that uses a waveguide with large wavelength dispersion. However, the one-dimensional phase shift circuit, i.e., "EL1" to "EL2" in Figure 1 of Patent Document 1, which is a group of wavelength dispersion optical fibers, P " and "AZ1" to "AZ NThe number of " depends on the number of antenna elements in the vertical direction and the number of antenna elements in the horizontal direction. Therefore, the technology of Patent Document 1 has a problem in that as the number of antenna elements increases, more one-dimensional phase shift circuits are required.

[0009] Patent Document 2 discloses a technology for two-dimensional beam control using a wavelength-tunable light source and wavelength dispersion lines. Fig. 2 of Patent Document 2 shows an outline of the configuration of a two-dimensional beam control device equipped with an array antenna with a vertical direction count × horizontal direction count = 5 × 13. As shown in Fig. 2, light from wavelength-tunable light source #1, designated by reference numeral 42, is distributed into a number equal to the number of vertical direction elements. A phase tilt in the vertical plane is imparted to each of the distributed wavelength-tunable light sources #1 by a first array of wavelength dispersion lines, designated by reference numeral 52. The light to which the phase tilt has been imparted is converted into an electric signal train by a photodiode 54, and the converted electric signal train is amplified by an amplifier 56.

[0010] Next, the light from tunable light source #2, denoted by reference numeral 84, is distributed into a number equal to the number of vertical elements. The optical modulator 58 modulates each of the distributed light from tunable light source #2 with the electrical signal train amplified by the amplifier 56 to generate an optical signal train. Each of the optical signal trains generated by the optical modulator 58 is distributed into a number equal to the number of horizontal elements. A second array of wavelength dispersion lines, denoted by reference numeral 62, imparts a phase tilt in the horizontal plane to each of the distributed optical signal trains. In the above configuration, two-dimensional beam control is possible by changing the wavelength of tunable light source #1 and the wavelength of tunable light source #2.

[0011] The operation during reception will be described with reference to Fig. 3 of Patent Document 2. An optical signal is generated by intensity-modulating the light from the wavelength-tunable light source 98 with a CW (Carrier Wave) at the frequency of an RF local signal, or so-called LO (Local Signal), by an optical modulator 104. The generated optical signal is split by an optical fiber splitter 112, and the split optical signal is given a phase tilt by a delay waveguide with large chromatic dispersion, denoted by reference numeral 114. A photodiode 116 generates an electrical RF local signal with a phase tilt from the optical signal obtained from the delay waveguide denoted by reference numeral 114.

[0012] The down-conversion mixer 126 included in the transmit / receive module 94 generates an intermediate frequency (IF) signal by mixing the RF local oscillator signal with a phase gradient generated by the photodiode 116 with the received RF signal with a phase gradient obtained from the antenna element 96. Here, the RF local oscillator signal is given a phase gradient according to the beam direction, so the resulting IF signals are in phase in all branches. Therefore, when the IF combiner 106 combines the resulting IF signals, only the received signals in the desired beam direction are combined in phase, resulting in a received signal. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-023400 [Patent Document 2] U.S. Patent No. 6,337,660 [Non-patent literature]

[0014] [Non-Patent Document 1] H. Watanabe, S. Uga, H. Nakamizo, T. Tsutsumi, S. Shinjo, and Y. Kuriyama, "Millimeter-Wave Antenna and RF Front-End Technology for 5th Generation Mobile Communication Base Stations," IEICE Communications Society Magazine, Vol. 14, No. 3, 2020, pp. 222-231. [Non-patent document 2] C. Tsokos et al., “Analysis of a Multibeam Optical Beamforming Network Based on Blass Matrix Architecture”, Journal of Lightwave Technology, vol.36, no.16, 15 Aug., 2018, pp.3354-3372. Summary of the Invention [Problem to be solved by the invention]

[0015] In the technologies disclosed in Patent Documents 1 and 2, when constructing a larger-scale two-dimensional array antenna, the number of wavelength dispersion lines required increases. The technology described in Patent Document 2 does not disclose a means for forming and receiving multiple beams. However, when forming and receiving multiple beams, it is considered that a number of multiplexers corresponding to the number of beams is required in the IF signal processing stage. This increases the circuit scale, resulting in a problem of increased circuit size, i.e., circuit area and volume. Considering the need to reduce the device profile and use a printed circuit manufacturing process for mass production, the three-dimensional circuit structure that provides a phase tilt using wavelength dispersion lines, as in the technologies disclosed in Patent Documents 1 and 2, is not suitable for mass production.

[0016] Therefore, the techniques disclosed in Patent Documents 1 and 2 have the problem that as the scale of the array antenna increases, the number of components and wiring that make up the circuit that performs beam formation increases, resulting in an increase in circuit size, and furthermore, the circuit structure that performs beam formation becomes complex, making it unsuitable for mass production.

[0017] In view of the above circumstances, an object of the present invention is to provide a technology that enables control of the receiving directivity of an array antenna to be implemented using a circuit with a simple structure that is suitable for miniaturization and mass production, even if the size of the array antenna increases. [Means for solving the problem]

[0018] According to one aspect of the present invention, there is provided a receiving directivity control device for controlling the receiving directivity of an array antenna in which an arbitrary straight line in a plane is defined as a row-direction axis, a straight line perpendicular to the row-direction axis in the plane is defined as a column-direction axis, and a plurality of antenna elements are arranged along the row-direction axis and the column-direction axis, the receiving directivity control device comprising: a light source for generating an optical signal; an electro-optical converter for modulating the optical signal with each of RF signals obtained by receiving an incoming wave at each of the antenna elements, and outputting a single sideband wave component of a modulated optical signal obtained by the modulation; and a control unit for controlling the receiving directivity of each of the row-direction components in the beamforming direction, for each combination of the single sideband wave components having the same column position, taking into account differences in the positions of the corresponding rows and each of the single sideband wave components included in the combination, and a row direction scanning unit that generates row direction synthesized optical signals corresponding to each of the row direction components in the beam forming direction by synthesizing the signals by performing a predetermined row direction phase scanning process that imparts a phase gradient that aligns phases to the row direction components in the beam forming direction, and converts the frequencies of the generated row direction synthesized optical signals so that they have different frequencies for each row direction component in the beam forming direction, and outputs the converted optical signals; and a column direction scanning unit that generates column direction synthesized optical signals corresponding to each of the column direction components in the beam forming direction by synthesizing the signals by performing a predetermined column direction phase scanning process that imparts a phase gradient that aligns phases to each of the row direction synthesized optical signals output by the row direction scanning unit, taking into account differences in the positions of the corresponding columns and a column direction phase gradient that occurs depending on each of the beam forming directions.

[0019] One aspect of the present invention is a reception directivity control method for controlling reception directivity of an array antenna in which an arbitrary straight line in a plane is defined as a row-direction axis, a straight line perpendicular to the row-direction axis in the plane is defined as a column-direction axis, and a plurality of antenna elements are arranged along the row-direction axis and the column-direction axis, the method comprising: modulating an optical signal generated by a light source with each of RF signals obtained by receiving an incoming wave at each of the antenna elements; outputting a single sideband wave component of a modulated optical signal obtained by the modulation; and for each combination of the single sideband wave components having the same column position, adjusting the beamforming direction for each of the single sideband wave components included in each of the combinations in consideration of a difference in the row position corresponding to each of the single sideband wave components and each of the beamforming directions. a predetermined column-direction phase scanning process that applies a phase gradient that aligns the phases of the row-direction components of the row-direction components in the beam-forming direction to generate row-direction synthesized optical signals corresponding to each of the row-direction components in the beam-forming direction, converting the frequencies of the generated row-direction synthesized optical signals so that they have different frequencies for the row-direction components in the beam-forming direction, and combining the converted row-direction synthesized optical signals by performing a predetermined column-direction phase scanning process that applies a phase gradient that aligns the phases of the column-direction components in the beam-forming direction to each of the converted row-direction synthesized optical signals, taking into account differences in the positions of the corresponding columns and a column-direction phase gradient that occurs depending on each of the beam-forming directions, thereby generating column-direction synthesized optical signals corresponding to each of the column-direction components in the beam-forming direction. [Effects of the Invention]

[0020] According to the present invention, when controlling the receiving directivity of an array antenna, even if the size of the array antenna becomes large, it is possible to realize implementation using a circuit with a simple structure that is suitable for miniaturization and mass production. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a block diagram showing a configuration related to a reception directivity control device of a first embodiment. [Figure 2] 2A and 2B are diagrams illustrating the arrangement of antenna elements in the array antenna of the first embodiment and the beams formed therein. [Figure 3] FIG. 3 is a diagram showing the direction of a beam formed in the first embodiment. [Figure 4] 4 is a flowchart showing a flow of processing by the reception directivity control device of the first embodiment. [Figure 5] FIG. 10 is a block diagram showing a configuration related to a reception directivity control device according to another configuration example of the first embodiment. [Figure 6] FIG. 10 is a block diagram showing a configuration related to a reception directivity control device of a second embodiment. [Figure 7] FIG. 10 is a block diagram showing a configuration related to a reception directivity control device according to another configuration example (part 1) of the second embodiment. [Figure 8] FIG. 10 is a block diagram showing a configuration related to a reception directivity control device according to another configuration example (part 2) of the second embodiment. [Figure 9] FIG. 10 is a block diagram showing a configuration related to a reception directivity control device according to another configuration example (part 3) of the second embodiment. [Figure 10] 10 is a flowchart showing a usage scene of each configuration example of the second embodiment. [Figure 11] FIG. 10 is a block diagram showing a configuration related to a reception directivity control device according to a configuration example (part 1) of the third embodiment. [Figure 12] FIG. 10 is a diagram illustrating the arrangement of antenna elements in an array antenna according to a configuration example (part 1) of the third embodiment. [Figure 13] FIG. 10 is a diagram showing the direction of a beam formed in a configuration example (part 1) of the third embodiment. [Figure 14] FIG. 11 is a block diagram showing a configuration related to a reception directivity control device according to a second configuration example of the third embodiment. [Figure 15] FIG. 10 is a diagram illustrating the arrangement of antenna elements in an array antenna in a configuration example (part 2) of the third embodiment. [Figure 16] FIG. 10 is a diagram showing the direction of a beam formed in a configuration example (part 2) of the third embodiment. [Figure 17]FIG. 13 is a diagram illustrating an example of optical frequency channels set in a frequency converter in the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0022] (First embodiment) DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings, in which: FIG. 1 is a block diagram showing the internal configuration of a reception directivity control device 1 according to a first embodiment, and an array antenna 80 connected to the reception directivity control device 1.

[0023] The reception directivity control device 1 is a device incorporated into, for example, a receiving device that demodulates a received signal. The reception directivity control device 1 is used to control the reception directivity of radio waves with sharp directionality required for, for example, ultra-high speed wireless transmission using radio waves in the millimeter wave band or terahertz band, high-frequency band, high-definition imaging, radar, etc.

[0024] Connecting the array antenna 80 to the reception directivity control device 1 forms a so-called phased array antenna. As shown in FIG. 2 , the array antenna 80 is a 3×3 array antenna having nine antenna elements 80-1-1, 80-1-2, 80-1-3, 80-2-1, 80-2-2, 80-2-3, 80-3-1, 80-3-2, and 80-3-3, with three elements arranged vertically and three elements arranged horizontally. Here, the vertical direction is a direction perpendicular to the horizontal direction, or the so-called vertical direction. Hereinafter, in the arrangement of the array antenna 80, the vertical direction is also referred to as the row direction, and the horizontal direction is also referred to as the column direction. The antenna elements 80-1-1 to 80-3-3 are arranged on a plane, i.e., on the surface of the array antenna 80.

[0025] The arrangement will be described in more detail. The antenna elements 80-1-1, 80-1-2, and 80-1-3 in the first row are arranged at equal intervals so as to be parallel to the axis in the column direction. Similarly, the antenna elements 80-2-1, 80-2-2, and 80-2-3 in the second row and the antenna elements 80-3-1, 80-3-2, and 80-3-3 in the third row are also arranged at equal intervals so as to be parallel to the axis in the column direction. The antenna elements are arranged so that the distance between adjacent antenna elements in the antenna elements 80-1-1, 80-1-2, and 80-1-3 is the same as the distance between adjacent antenna elements in the antenna elements 80-2-1, 80-2-2, and 80-2-3, and the distance between adjacent antenna elements in the antenna elements 80-3-1, 80-3-2, and 80-3-3.

[0026] The antenna elements 80-1-1, 80-2-1, and 80-3-1 in the first column are arranged at equal intervals and parallel to the row axis. Similarly, the antenna elements 80-1-2, 80-2-2, and 80-3-2 in the second column and the antenna elements 80-1-3, 80-2-3, and 80-3-3 in the third column are also arranged at equal intervals and parallel to the row axis. The antenna elements 80-1-1, 80-2-1, and 80-3-1 are arranged so that the distance between adjacent antenna elements is the same as the distance between adjacent antenna elements in the antenna elements 80-1-2, 80-2-2, and 80-3-2, and the distance between adjacent antenna elements in the antenna elements 80-1-3, 80-2-3, and 80-3-3.

[0027] Therefore, the shape with vertices at the positions of each of antenna elements 80-1-1, 80-1-3, 80-3-3, and 80-3-1 is rectangular. In this case, the distance between antenna elements 80-1-1 and 80-1-2 adjacent to each other in the column direction and the distance between antenna elements 80-1-1 and 80-2-1 adjacent to each other in the row direction may be the same or different. If the distances are the same, the rectangular shape with vertices at the positions of antenna elements 80-1-1, 80-1-3, 80-3-3, and 80-3-1 is square. Each of antenna elements 80-1-1 to 80-3-3 receives incoming radio frequency radio waves, i.e., RF radio waves, and is thereby supplied with an electrical RF signal. Hereinafter, the incoming RF radio waves will be referred to as an incoming wave.

[0028] The reception directivity control device 1 includes a light source 5, an electro-optical conversion unit 10, a row direction scanning unit 20, and a column direction scanning unit 50. The reception directivity control device 1 controls the directivity so as to receive an incoming wave coming from a direction desired by the user (hereinafter referred to as a desired direction). The reception directivity control device 1 forms nine directional beams 90-1, 90-2, 90-3, 90-4, 90-5, 90-6, 90-7, 90-8, and 90-9 in the array antenna 80, as shown in FIG.

[0029] Fig. 3 is a diagram showing the relationship between the plane of array antenna 80 and the directions in which beams 90-1 to 90-9 are formed. When viewed through the plane of array antenna 80 in the observation direction indicated by the arrow in Fig. 2, that is, from the side where reception directivity control device 1 is installed, as shown in Fig. 3, beam 90-1 is formed to point in the upper right direction, beam 90-3 is formed to point in the upper left direction, beam 90-7 is formed to point in the lower right direction, and beam 90-9 is formed to point in the lower left direction.

[0030] Beam 90-5 is formed so as to face in the direction of a straight line perpendicular to the surface of array antenna 80 (hereinafter, this direction will be referred to as the "middle direction"). Beam 90-2 is formed so as to face in the direction obtained by tilting a straight line perpendicular to the surface of array antenna 80 upward (hereinafter, this direction will be referred to as the "middle-upper direction"). Beam 90-8 is formed so as to face in the direction obtained by tilting a straight line perpendicular to the surface of array antenna 80 downward (hereinafter, this direction will be referred to as the "middle-lower direction").

[0031] Beam 90-4 is formed so as to point in a direction obtained by tilting a line perpendicular to the surface of array antenna 80 to the right (hereinafter, this direction will be referred to as the "center right direction"), and beam 90-6 is formed so as to point in a direction obtained by tilting a line perpendicular to the surface of array antenna 80 to the left (hereinafter, this direction will be referred to as the "center left direction").

[0032] Hereinafter, the vertical component of the direction of beams 90-1, 90-2, and 90-3 will be referred to as the "upward direction," the vertical component of the direction of beams 90-4, 90-5, and 90-6 will be referred to as the "middle direction," and the vertical component of the direction of beams 90-7, 90-8, and 90-9 will be referred to as the "downward direction." The horizontal component of the direction of beams 90-1, 90-4, and 90-7 will be referred to as the "rightward direction," the horizontal component of the direction of beams 90-2, 90-5, and 90-8 will be referred to as the "middle direction," and the horizontal component of the direction of beams 90-3, 90-6, and 90-9 will be referred to as the "leftward direction."

[0033] The beams 90-1, 90-2, and 90-3 are formed so that the tilts of the beams 90-1, 90-2, and 90-3 relative to the horizontal plane, in other words, the vertical components of the tilts of the beams 90-1, 90-2, and 90-3, are the same. The phase tilt, which is the phase difference caused by the vertical components of the tilts of the beams 90-1, 90-2, and 90-3, is defined as "φ V " is expressed as

[0034] The beams 90-1, 90-4, and 90-7 are formed so that the inclinations of the beams 90-1, 90-4, and 90-7 with respect to the vertical plane, in other words, the horizontal components of the inclinations of the beams 90-1, 90-4, and 90-7, are the same. The phase inclination, which is the phase difference caused by the horizontal components of the inclinations of the beams 90-1, 90-4, and 90-7, is defined as "φ H ". Note that "φ V " and "φ H " may be different values ​​or may be the same value.

[0035] Here, the phase tilt will be explained in more detail. For example, assume that an incoming wave from the direction of beam 90-1 is received by three antenna elements 80-1-1, 80-2-1, and 80-3-1 in the first row. In this case, due to the tilt of beam 90-1 with respect to the horizontal plane and the differences in the positions of antenna elements 80-1-1, 80-2-1, and 80-3-1, there will be differences in the arrival times required for the incoming wave to reach antenna element 80-1-1, antenna element 80-2-1, and antenna element 80-3-1. Due to this difference in arrival times, a phase difference φ is introduced into the RF signals obtained from each of the adjacent antenna elements 80-1-1 and 80-2-1. V Similarly, the RF signals obtained from the adjacent antenna elements 80-2-1 and 80-3-1 each have a phase difference φ V That is, the phase of the RF signal obtained from the antenna element 80-1-1 is changed to φ V The delayed RF signal is the RF signal obtained from the antenna element 80-2-1. The phase of the RF signal obtained from the antenna element 80-1-1 is set to 2φ V The delayed RF signal becomes the RF signal obtained from antenna element 80-3-1.

[0036] As described above, the distance between each of the antenna elements 80-1-2, 80-2-2, and 80-3-2 in the second row and the distance between each of the antenna elements 80-1-3, 80-2-3, and 80-3-3 in the third row are the same as the distance between each of the antenna elements 80-1-1, 80-2-1, and 80-3-1 in the first row. Therefore, even when the antenna elements 80-1-2, 80-2-2, and 80-3-2 receive an incoming wave from the direction of the beam 90-1, the phase difference between the RF signals obtained from each of the adjacent antenna elements is φ V Even when the antenna elements 80-1-3, 80-2-3, and 80-3-3 receive waves arriving from the direction of the beam 90-1, the phase difference between the RF signals obtained from the adjacent antenna elements is φ V This phase difference φ V is the phase gradient in the row direction of the beam 90-1 (hereinafter referred to as the row direction phase gradient).

[0037] Similarly, due to the inclination of beam 90-1 with respect to the vertical plane, even when an incoming wave from the direction of beam 90-1 is received by three antenna elements 80-1-1, 80-1-2, and 80-1-3 in the same row, there is a difference in the arrival time required for the incoming wave to reach antenna element 80-1-1, antenna element 80-1-2, and antenna element 80-1-3. Due to this difference in arrival time, a phase difference φ is generated in the RF signals obtained from antenna element 80-1-1 and antenna element 80-1-2. H Similarly, the RF signals obtained from the antenna elements 80-1-2 and 80-1-3 have a phase difference φ H That is, the phase of the RF signal obtained from the antenna element 80-1-1 is changed to φ H The delayed RF signal is the RF signal obtained from the antenna element 80-1-2. The phase of the RF signal obtained from the antenna element 80-1-1 is set to 2φ H The delayed RF signal becomes the RF signal obtained from antenna element 80-1-3.

[0038] This is also true for the combination of antenna elements 80-2-1, 80-2-2, and 80-2-3 in the second row and the combination of antenna elements 80-3-1, 80-3-2, and 80-3-3 in the third row. H is the phase gradient in the column direction of the beam 90-1 (hereinafter referred to as the column-direction phase gradient).

[0039] Beams 90-7, 90-8, and 90-9 are formed so that the row phase tilt is the opposite of the row phase tilt of beams 90-1, 90-2, and 90-3. Therefore, the row phase tilt of beams 90-7, 90-8, and 90-9 is "-φ V Beams 90-3, 90-6, and 90-9 are formed so that the column phase gradient is the opposite of the column phase gradient of beams 90-1, 90-4, and 90-7. Therefore, the column phase gradient of beams 90-3, 90-6, and 90-9 is "-φ H Beam 90-5 is in the center direction, and when receiving an incoming wave from this direction, no phase difference occurs among the RF signals obtained from all of antenna elements 80-1-1 to 80-3-3.

[0040] Therefore, the phase gradients of the beams 90-1 to 90-9 can be expressed in the form of (phase gradient in the row direction, phase gradient in the column direction) as follows: V ,φ H ), and the beam 90-2 is (φ V ,0), and beam 90-3 is (φ V ,-φ H ) and the beam 90-4 is (0,φ H ), beam 90-5 is at (0,0), and beam 90-6 is at (0,-φ H ) and the beam 90-7 is (-φ V ,φ H ), and beam 90-8 is (-φ V ,0), and beam 90-9 is (-φ V ,-φ H )

[0041] The light source 5 generates an optical signal of frequency ch1 that serves as a carrier wave, and supplies the generated optical signal to each of the optical modulators 11-1-1 to 11-3-3 that the electrical-to-optical conversion unit 10 includes.

[0042] The electrical-to-optical conversion unit 10 includes optical modulators 11-1-1 to 11-3-3, the number of which corresponds to the number of antenna elements 80-1-1 to 80-3-3. The optical modulators 11-1-1 to 11-3-3 are connected to the corresponding antenna elements 80-1-1 to 80-3-3, respectively.

[0043] Of the two sub-numbers included in the reference numerals of the antenna elements 80-1-1 to 80-3-3 and the optical modulators 11-1-1 to 11-3-3, the former number corresponds to the row number, and the latter number corresponds to the column number. The same sub-numbering system will be used in subsequent drawings. For example, the antenna element 80-2-1 is located in the second row and first column. Each of the optical modulators 11-1-1 to 11-3-3 is connected to an antenna element 80-1-1 to 80-3-3 that has the same combination of two sub-numbers. To minimize RF signal loss, each of the optical modulators 11-1-1 to 11-3-3 is preferably located near the antenna element 80-1-1 to 80-3-3 to which it is connected.

[0044] Each of the optical modulators 11-1-1 to 11-3-3 has the same configuration. That is, each of the optical modulators 11-1-1 to 11-3-3 is an optical modulator that performs, for example, SSB (Single Side-Band) optical modulation with the same characteristics, standards, specifications, and method. Each of the optical modulators 11-1-1 to 11-3-3 modulates the optical signal supplied thereto with an RF signal supplied from the antenna elements 80-1-1 to 80-3-3 connected thereto, and outputs a single sideband component of the modulated optical signal. Note that the single sideband component includes an USB (Upper Side Band) component and an LSB (Lower Side Band) component, but the following description will be given assuming that the optical modulators 11-1-1 to 11-3-3 output the USB component.

[0045] The row direction scanning unit 20 has circuit configurations whose number matches the number of columns of the array antenna 80. The circuit configuration corresponding to the first column is a row direction scanning matrix circuit 21-1, frequency converters 22-1 and 23-1, and a switching SW unit 25-1 connected to the optical modulators 11-1-1, 11-2-1, and 11-3-1 of the first column. The circuit configuration corresponding to the second column is a row direction scanning matrix circuit 21-2, frequency converters 22-2 and 23-2, and a switching SW unit 25-2 connected to the optical modulators 11-1-2, 11-2-2, and 11-3-2 of the second column. The circuit configuration corresponding to the third column is a row direction scanning matrix circuit 21-3, frequency converters 22-3 and 23-3, and a switching SW unit 25-3 connected to the optical modulators 11-1-3, 11-2-3, and 11-3-3 of the third column.

[0046] The three circuit configurations included in the row direction scanning unit 20 are identical, and below, as an example, the row direction scanning matrix circuit 21-1, frequency converters 22-1 and 23-1, and switching switch unit 25-1, which are circuit configurations corresponding to the first column, will be described. In the following description of the circuit configurations corresponding to the first column, the branch number "-1" of the symbol will be replaced with "-2" to describe the circuit configuration corresponding to the second column, and the branch number "-1" of the symbol will be replaced with "-3" to describe the circuit configuration corresponding to the third column. However, in the description of optical modulators 11-1-1, 11-2-1, and 11-3-1, the last branch number "-1" of the two branch numbers included in the symbol will be replaced with "-2" or "-3".

[0047] The row-direction scanning matrix circuit 21-1 is a one-dimensional weighting circuit and includes three input ports 31-1, 32-1, and 33-1 and three output ports 35-1, 36-1, and 37-1. The row-direction scanning matrix circuit 21-1 is connected to three optical modulators 11-1-1, 11-2-1, and 11-3-1 in the first column. More specifically, the optical modulator 11-1-1 is connected to the input port 31-1, the optical modulator 11-2-1 is connected to the input port 32-1, and the optical modulator 11-3-1 is connected to the input port 33-1.

[0048] The row-direction scanning matrix circuit 21-1 performs a process of changing the phases of the optical signals supplied from the input ports 31-1, 32-1, and 33-1 by applying a phase gradient to them. To explain this process, it is assumed that the input and output relationships in the row-direction scanning matrix circuit 21-1 are reversed and optical signals are supplied to each of the output ports 35-1, 36-1, and 37-1.

[0049] Assume that an optical signal is supplied to the output port 35-1 of the row-direction scanning matrix circuit 21-1. In this case, the row-direction scanning matrix circuit 21-1 outputs the optical signal supplied from the output port 35-1 as is from the input port 31-1, and changes the phase of the supplied optical signal to φ V The delayed optical signal is output from the input port 32-1, and the phase of the supplied optical signal is changed by 2φ V The delayed optical signal is output from input port 33-1. Therefore, the phase difference between the optical signals output from input ports 31-1, 32-1, and 33-1 is (0, -φ V ,-2φ V ) becomes.

[0050] Assume that an optical signal is supplied to the output port 36-1 of the row-direction scanning matrix circuit 21-1. In this case, the row-direction scanning matrix circuit 21-1 outputs the optical signal supplied from the output port 36-1 as is from the input ports 31-1, 32-1, and 33-1. Therefore, the phase differences of the optical signals output from the input ports 31-1, 32-1, and 33-1 become (0,0,0), i.e., there is no phase difference.

[0051] Assume that an optical signal is supplied to the output port 37-1 of the row-direction scanning matrix circuit 21-1. In this case, the row-direction scanning matrix circuit 21-1 outputs the optical signal supplied from the output port 37-1 as is from the input port 33-1, and changes the phase of the supplied optical signal to φ V The delayed optical signal is output from the input port 32-1, and the phase of the supplied optical signal is changed by 2φ V The delayed optical signal is output from input port 31-1. Therefore, the phase difference between the optical signals output from input ports 31-1, 32-1, and 33-1 is (-2φ V ,-φ V,0).

[0052] Conversely, when optical signals are supplied from each of the input ports 31-1, 32-1, and 33-1, the row-direction scanning matrix circuit 21-1 performs a process of imparting a phase gradient of the opposite sign to the phase gradient imparting process described above to each of the supplied optical signals. This process will be hereinafter referred to as the predetermined row-direction phase scanning process performed by the row-direction scanning matrix circuit 21-1.

[0053] The row-direction scanning matrix circuit 21-1 performs a predetermined row-direction phase scanning process on the optical signals supplied from each of the input ports 31-1, 32-1, and 33-1, thereby generating three optical signals for each of the output ports 35-1, 36-1, and 37-1. The row-direction scanning matrix circuit 21-1 combines the three optical signals generated for each of the output ports 35-1, 36-1, and 37-1 to generate an optical signal for each of the output ports 35-1, 36-1, and 37-1 (hereinafter, this optical signal will be referred to as a row-direction combined optical signal). The row-direction scanning matrix circuit 21-1 outputs each of the row-direction combined optical signals generated for each of the output ports 35-1, 36-1, and 37-1 from the corresponding output ports 35-1, 36-1, and 37-1.

[0054] For each of the input ports 31-1, 32-1, and 33-1, the phase difference is (0, -φ V ,-2φ V In other words, the three optical signals having a phase difference φ are input to the input port 31-1. V The delayed optical signal is supplied to input port 32-1 and has a phase difference of 2φ from the optical signal supplied to input port 31-1. VSuppose a delayed optical signal is supplied to input port 33-1. In this case, of the row direction combined optical signals generated for each of output ports 35-1, 36-1, and 37-1, the three optical signals included in the row direction combined optical signal corresponding to output port 35-1 are in phase. Therefore, the row direction combined optical signal corresponding to output port 35-1 is an in-phase combined signal, and therefore its signal intensity is high. In contrast, the three optical signals included in the row direction combined optical signals generated for each of output ports 36-1 and 37-1 are not in phase. Therefore, the signal intensity of the row direction combined optical signals at each of output ports 36-1 and 37-1 is lower than the signal intensity of the row direction combined optical signal at output port 35-1.

[0055] Assume that three optical signals with a phase difference of (0,0,0) are supplied to each of the input ports 31-1, 32-1, and 33-1 of the row direction scanning matrix circuit 21-1. In this case, of the row direction combined optical signals generated for each of the output ports 35-1, 36-1, and 37-1, the three optical signals included in the row direction combined optical signal corresponding to output port 36-1 are in phase. Therefore, the row direction combined optical signal corresponding to output port 36-1 is an in-phase combined signal, and therefore its signal intensity is high. In contrast, the three optical signals included in the row direction combined optical signals generated for each of the output ports 35-1 and 37-1 are not in phase. Therefore, the signal intensity of the row direction combined optical signal at each of the output ports 35-1 and 37-1 is lower than the signal intensity of the row direction combined optical signal at output port 36-1.

[0056] For each of the input ports 31-1, 32-1, and 33-1, the phase difference is (-2φ V ,-φ V In other words, the optical signal having a phase φ is input to the input port 33-1. V The delayed optical signal is supplied to the input port 32-1 and has a phase difference of 2φ with respect to the optical signal supplied to the input port 33-1. VSuppose a delayed optical signal is supplied to input port 31-1. In this case, of the row direction combined optical signals generated for each of output ports 35-1, 36-1, and 37-1, the three optical signals included in the row direction combined optical signal corresponding to output port 37-1 are in phase. Therefore, the row direction combined optical signal corresponding to output port 37-1 is an in-phase combined signal, and therefore its signal intensity is high. In contrast, the three optical signals included in the row direction combined optical signals generated for each of output ports 35-1 and 36-1 are not in phase. Therefore, the signal intensity of the row direction combined optical signals at each of output ports 35-1 and 36-1 is lower than the signal intensity of the row direction combined optical signal at output port 37-1.

[0057] The frequency converter 22-1 is connected to the output port 36-1 of the row-direction scanning matrix circuit 21-1. The frequency converter 22-1 converts the supplied optical signal of frequency ch1 into an optical signal of frequency ch2, which is a different frequency from frequency ch1.

[0058] The frequency converter 23-1 is connected to the output port 37-1 of the row-direction scanning matrix circuit 21-1. The frequency converter 23-1 converts the supplied optical signal of frequency ch1 into an optical signal of frequency ch3, which is a frequency different from frequencies ch1 and ch2.

[0059] The switching switch unit 25-1 has three input ports 41-1, 42-1, and 43-1 and one output port 45-1. The input port 41-1 is connected to the output port 35-1 of the row-direction scanning matrix circuit 21-1, the input port 42-1 is connected to the frequency converter 22-1, and the input port 43-1 is connected to the frequency converter 23-1.

[0060] In response to a user's operation to specify a desired direction, the switching switch unit 25-1 selects input ports 41-1, 42-1, and 43-1 corresponding to the desired direction and connects the selected input ports 41-1, 42-1, and 43-1 to the output port 45-1. The switching switch unit 25-1 is configured so that one or more of the input ports 41-1, 42-1, and 43-1 can be connected to the output port 45-1. This allows the user to specify one or more desired directions for the switching switch unit 25-1.

[0061] Input ports 41-1, 42-1, and 43-1 of switching SW unit 25-1 are assigned in advance to three row direction components in the directions of beams 90-1 to 90-9. Here, as described above, the row direction is the vertical direction, so the row direction components are also vertical direction components.

[0062] Input port 41-1 is pre-assigned to the "upward direction," which is the row component of the directions of beams 90-1, 90-2, and 90-3. Input port 42-1 is pre-assigned to the "middle direction," which is the row component of the directions of beams 90-4, 90-5, and 90-6. Input port 43-1 is pre-assigned to the "downward direction," which is the row component of the directions of beams 90-7, 90-8, and 90-9.

[0063] The column scanning unit 50 includes a column scanning matrix circuit 51 and demultiplexers 52-1, 52-2, and 52-3. The column scanning matrix circuit 51 is a one-dimensional weighting circuit and includes three input ports 51-1, 51-2, and 51-3 and three output ports 51-5, 51-6, and 51-7. The input port 51-1 is connected to the output port 45-1 of the switching switch unit 25-1. The input port 51-2 is connected to the output port 45-2 of the switching switch unit 25-2. The input port 51-3 is connected to the output port 45-3 of the switching switch unit 25-3.

[0064] The column-direction scanning matrix circuit 51 performs a predetermined column-direction phase scanning process on the optical signals supplied from each of the input ports 51-1, 51-2, and 51-3 to generate three optical signals for each of the output ports 51-5, 51-6, and 51-7. The column-direction scanning matrix circuit 51 combines the three optical signals generated for each of the output ports 51-5, 51-6, and 51-7 to generate an optical signal for each of the output ports 51-5, 51-6, and 51-7 (hereinafter, this optical signal will be referred to as a column-direction combined optical signal). The column-direction scanning matrix circuit 51 outputs each of the column-direction combined optical signals generated for each of the output ports 51-5, 51-6, and 51-7 from the corresponding output ports 51-5, 51-6, and 51-7.

[0065] The predetermined column-direction phase scanning process performed by the column-direction scanning matrix circuit 51 is a predetermined row-direction phase scanning process performed by the row-direction scanning matrix circuit 21-1 under the following input / output conditions: v " to "φ H " is the same processing as that in which " is replaced with ". The input / output conditions here are conditions where, on the input side, input port 51-1 corresponds to input port 31-1, input port 51-2 corresponds to input port 32-2, and input port 51-3 corresponds to input port 33-1. On the output side, output port 51-5 corresponds to output port 35-1, output port 51-6 corresponds to output port 36-1, and output port 51-7 corresponds to output port 37-1.

[0066] The input side of the demultiplexer 52-1 is connected to the output port 51-5 of the column-directional scanning matrix circuit 51. The demultiplexer 52-1 has an output port 55-1 corresponding to frequency ch1, an output port 56-1 corresponding to frequency ch2, and an output port 57-1 corresponding to frequency ch3. The input side of the demultiplexer 52-2 is connected to the output port 51-6 of the column-directional scanning matrix circuit 51. The demultiplexer 52-2 has an output port 55-2 corresponding to frequency ch1, an output port 56-2 corresponding to frequency ch2, and an output port 57-2 corresponding to frequency ch3. The input side of the demultiplexer 52-3 is connected to the output port 51-7 of the column-directional scanning matrix circuit 51. The demultiplexer 52-3 has an output port 55-3 corresponding to frequency ch1, an output port 56-3 corresponding to frequency ch2, and an output port 57-3 corresponding to frequency ch3.

[0067] Each of the demultiplexers 52-1, 52-2, and 52-3 demultiplexes the supplied optical signal into optical signals of frequencies ch1, ch2, and ch3, and outputs each of the demultiplexed optical signals from output ports 55-1, 55-2, 55-3, 56-1, 56-2, 56-3, 57-1, 57-2, and 57-3 corresponding to each frequency ch1, ch2, and ch3.

[0068] (Processing by the reception directivity control device of the first embodiment) 4 is a flowchart showing the flow of processing by the reception directivity control device 1 of the first embodiment. Here, the following explanation will be given assuming that the user's desired direction is the direction of beam 90-1 formed in the upper right direction, beam 90-8 formed in the lower center direction, and beam 90-6 formed in the center left direction. Below, the explanation will be divided into cases where an incoming wave is received from the direction of beam 90-1, where an incoming wave is received from the direction of beam 90-8, and where an incoming wave is received from the direction of beam 90-6, and then a case where incoming waves from the directions of beams 90-1, 90-8, and 90-6 are received in parallel will be explained.

[0069] (When receiving an incoming wave from the direction of beam 90-1) Beam 90-1 is formed in the upper right direction with respect to the plane of array antenna 80. The row direction component of the upper right direction is the "upward direction." Therefore, when the user operates switching switch unit 25-1 to specify the direction of beam 90-1 as the desired direction, switching switch unit 25-1 connects input port 41-1, which corresponds to the "upward direction" row direction component of beam 90-1, to output port 45-1. The user performs similar operations on switching switch units 25-2 and 25-3. As a result, switching switch unit 25-2 connects input port 41-2 to output port 45-2, and switching switch unit 25-3 connects input port 41-3 to output port 45-3 (S1).

[0070] When antenna elements 80-1-1 to 80-3-3 receive an incoming wave from the direction of beam 90-1, they supply the RF signal obtained by power supply upon receiving the incoming wave to optical modulators 11-1-1 to 11-3-3 connected to them. Each of optical modulators 11-1-1 to 11-3-3 modulates the optical signal of frequency ch1 supplied to it by light source 5 with the RF signal supplied to it by antenna elements 80-1-1 to 80-3-3.

[0071] Here, the optical signal of frequency ch1 generated by the light source 5 can be expressed by the following equation (1), for example.

[0072]

number

[0073] In equation (1), ω C is the angular frequency of the optical signal of frequency ch1, and t is the time. The RF signal supplied from the antenna element 80-1-1 to the optical modulator 11-1-1 can be expressed, for example, as the following equation (2).

[0074]

number

[0075] In equation (2), ωRF is the angular frequency of the RF signal. The modulated optical signal generated by the optical modulator 11-1-1 through modulation is an intensity-modulated signal, that is, an amplitude-modulated signal, and is therefore expressed as the following equation (3).

[0076]

number

[0077] The equation representing the output optical signal output by the optical modulator 11-1-1, that is, the USB component of the modulated optical signal, is given by the following equation (4) from equation (3).

[0078]

number

[0079] In addition, "A" in the equations (3) and (4) is the amplitude value of the sideband of the modulated optical signal. The phase tilt in the row direction of the beam 90-1 is "φ V Therefore, in the case of an incoming wave from the direction of beam 90-1, the RF signal obtained from antenna element 80-2-1, which is in the same column as antenna element 80-1-1 and adjacent in the row direction, has a phase φ V Therefore, the RF signal supplied to the optical modulator 11-2-1 by the antenna element 80-2-1 has a phase delay φ V The delayed RF signal can be expressed as the following equation (5).

[0080]

number

[0081] Therefore, the output optical signal output from the optical modulator 11-2-1 is expressed by the following equation (6).

[0082]

number

[0083] The RF signal supplied from the antenna element 80-3-1 to the optical modulator 11-3-1 has a phase φ V Therefore, the output optical signal output from the optical modulator 11-3-1 is expressed by the following equation (7).

[0084]

number

[0085] Each of the optical modulators 11-1-1, 11-2-1, and 11-3-1 outputs the USB component of the modulated optical signal generated by modulation to the row-direction scanning matrix circuit 21-1. Similarly, each of the optical modulators 11-1-2, 11-2-2, and 11-3-2 outputs the USB component of the modulated optical signal generated by modulation to the row-direction scanning matrix circuit 21-2. Each of the optical modulators 11-1-3, 11-2-3, and 11-3-3 outputs the USB component of the modulated optical signal generated by modulation to the row-direction scanning matrix circuit 21-3 (S2).

[0086] As a result, the USB components of the three modulated optical signals expressed by equations (4), (6), and (7) are supplied to the input ports 31-1, 32-1, and 33-1 of the row-direction scanning matrix circuit 21-1, respectively. In this case, the phase differences of the USB components of the modulated optical signals supplied to the input ports 31-1, 32-1, and 33-1 are (0, -φ V ,-2φ V ). Therefore, when the row-direction scanning matrix circuit 21-1 performs a predetermined row-direction phase scanning process on the USB components of the modulated optical signals supplied to each of the input ports 31-1, 32-1, and 33-1, the three optical signals output from the output port 35-1 become in phase, and the signal intensity increases due to in-phase synthesis. The row-direction synthesized optical signal obtained by synthesizing the three optical signals output from the output port 35-1 is expressed, for example, by the following equation (8).

[0087]

number

[0088] In equation (8), "B" is the amplitude value of the row-direction combined optical signal generated by in-phase combining (hereinafter, the row-direction combined optical signal generated by in-phase combining will also be referred to as "in-phase combined row-direction combined optical signal"). Note that in the case of an incoming wave from the direction of beam 90-1, the three optical signals output from each of output ports 36-1 and 37-1 by row-direction scanning matrix circuit 21-1 will not be in phase. Therefore, the signal intensity of the optical signals output from output ports 36-1 and 37-1 will be smaller than the signal intensity of the row-direction combined optical signal output from output port 35-1.

[0089] The phase difference occurring between the RF signals obtained from the antenna elements 80-1-2, 80-2-2, and 80-3-2 in the second column and the phase difference occurring between the RF signals obtained from the antenna elements 80-1-3, 80-2-3, and 80-3-3 in the third column are the same as the phase difference occurring between the RF signals obtained from the antenna elements 80-1-1, 80-2-1, and 80-3-1 in the first column. Therefore, the phase difference of the USB components of the modulated optical signals supplied to the input ports 31-2, 32-2, and 33-2 of the row-direction scanning matrix circuit 21-2 and the phase difference of the USB components of the modulated optical signals supplied to the input ports 31-3, 32-3, and 33-3 of the row-direction scanning matrix circuit 21-3 are (0, -φ) in the same manner as in the case of the row-direction scanning matrix circuit 21-1. V ,-2φ V ) Therefore, each of the row-direction scanning matrix circuits 21-2 and 21-3 outputs an in-phase row-direction combined optical signal corresponding to the wave arriving from the direction of the beam 90-1 from each of the output ports 35-2 and 35-3 (S3).

[0090] Note that the row direction combined optical signals that are not in-phase combined and output from the output ports 36-1 and 37-1 of the row direction scanning matrix circuit 21-1 are discarded by the switching switch unit 25-1 because the input ports 42-1 and 43-1 of the switching switch unit 25-1 are not connected to the output port 45-1. Similarly, the row direction combined optical signals that are output from the output ports 36-2 and 37-2 of the row direction scanning matrix circuit 21-2 and the row direction combined optical signals that are output from the output ports 36-3 and 37-3 of the row direction scanning matrix circuit 21-3 are also discarded by the switching switch units 25-2 and 25-3. Therefore, hereinafter, a description of the processing of the row direction combined optical signals that are output from the output ports 36-1, 37-1, 36-2, and 37-2 will be omitted.

[0091] As mentioned above, the column-wise phase gradient of the beam 90-1 is "φ H Therefore, the RF signal of the antenna element 80-1-2 in the second column has a phase difference φ with respect to the RF signal of the antenna element 80-1-1 in the first column that is adjacent in the column direction and in the same row. H Similarly, the RF signal of the antenna element 80-2-2 in the second column has a phase delay of φ with respect to the RF signal of the antenna element 80-2-1 in the first column that is adjacent in the column direction and in the same row. H The RF signal of the antenna element 80-3-2 in the second column has a phase difference of φ with respect to the RF signal of the antenna element 80-3-1 in the first column that is adjacent in the column direction and in the same row. H Be late.

[0092] Therefore, the row direction combined optical signal output from the output port 35-2 by the row direction scanning matrix circuit 21-2 has a phase difference φ H This delay is expressed by the following equation (9).

[0093]

number

[0094] The antenna elements 80-1-3, 80-2-3, and 80-3-3 in the third row are further φ H Therefore, the row-direction combined optical signal output from the output port 35-3 of the row-direction scanning matrix circuit 21-3 is expressed by the following equation (10).

[0095]

number

[0096] The output ports 35-1, 35-2, and 35-3 of the row-direction scanning matrix circuits 21-1, 21-2, and 21-3 are directly connected to the input ports 41-1, 41-2, and 41-3 of the switching switches 25-1, 25-2, and 25-3. Therefore, the process of S4 is not performed on the row-direction combined optical signals output from the output ports 35-1, 35-2, and 35-3.

[0097] As described in the process of S1, in each of the switching switches 25-1, 25-2, and 25-3, the output ports 45-1, 45-2, and 45-3 are connected to the input ports 41-1, 41-2, and 41-3, respectively. Therefore, the switching switch 25-1 outputs the row-direction combined optical signal expressed by equation (8) output from the output port 35-1 of the row-direction scanning matrix circuit 21-1 to the input port 51-1 of the column-direction scanning matrix circuit. The switching switch 25-2 outputs the row-direction combined optical signal expressed by equation (9) output from the output port 35-2 of the row-direction scanning matrix circuit 21-2 to the input port 51-2 of the column-direction scanning matrix circuit. The switching switch 25-3 outputs the row-direction combined optical signal expressed by equation (10) output from the output port 35-3 of the row-direction scanning matrix circuit 21-3 to the input port 51-3 of the column-direction scanning matrix circuit (S5).

[0098] The phase difference of the row-direction combined optical signals supplied to the input ports 51-1, 51-2, and 51-3 of the column-direction scanning matrix circuit 51 is expressed as (0, -φ H ,-2φ H) As a result, when the column-direction scanning matrix circuit 51 performs a predetermined column-direction phase scanning process on the row-direction combined optical signals supplied to each of the input ports 51-1, 51-2, and 51-3, the three optical signals output from the output port 51-5 have the same phase, and the signal intensity increases due to in-phase combining. The column-direction combined optical signal obtained by combining the three optical signals output from the output port 51-5 can be expressed, for example, as the following equation (11).

[0099]

number

[0100] In equation (11), "C" is the amplitude value of the column-direction combined optical signal generated by in-phase combining (hereinafter, the column-direction combined optical signal generated by in-phase combining will also be referred to as "in-phase combined column-direction combined optical signal"). In the case of an incoming wave from the direction of beam 90-1, the three optical signals included in the column-direction combined optical signal output from each of the output ports 51-6 and 51-7 by the column-direction scanning matrix circuit 51 are not in phase. Therefore, the signal intensity of the column-direction combined optical signal output from each of the output ports 51-6 and 51-7 by the column-direction scanning matrix circuit 51 is smaller than the signal intensity of the column-direction combined optical signal output from the output port 51-5. The column-direction scanning matrix circuit 51 outputs the column-direction combined optical signal from each of the output ports 51-5, 51-6, and 51-7 (S6).

[0101] The column-direction combined optical signal output from the column-direction scanning matrix circuit 51 through the output port 51-5 is supplied to the demultiplexer 52-1. The demultiplexer 52-1 demultiplexes the supplied column-direction combined optical signal into optical signals of frequencies ch1, ch2, and ch3. The demultiplexer 52-1 outputs the demultiplexed optical signal of frequency ch1 to the output port 55-1, the demultiplexed optical signal of frequency ch2 to the output port 56-1, and the demultiplexed optical signal of frequency ch3 to the output port 57-1 (S7), thereby completing the process.

[0102] When only waves arriving from the direction of beam 90-1 are present, the column-direction combined optical signal supplied to demultiplexer 52-1 includes an optical signal of frequency ch1, which has a high signal intensity. Therefore, the optical signal output from output port 55-1 corresponding to frequency ch1 is the received signal corresponding to the wave arriving from the direction of beam 90-1. Since this received signal is composed of in-phase optical signals combined as described above and has a high signal intensity, for example, a device performing demodulation processing can be connected to reception directivity control device 1 and can capture and demodulate this received signal to obtain data superimposed on the received signal.

[0103] The column-direction combined optical signal of frequency ch1 is also supplied to the demultiplexers 52-2 and 52-3 from the column-direction scanning matrix circuit 51, but the signal strength of these column-direction combined optical signals is smaller than the signal strength of the in-phase combined column-direction combined optical signal, as described above. Therefore, the optical signal output from the output port 55-2 of the demultiplexer 52-2 and the optical signal output from the output port 55-3 of the demultiplexer 52-3 do not have the signal strength required for demodulation processing, and are therefore not demodulated.

[0104] (When receiving an incoming wave from the direction of beam 90-8) Next, a process for receiving an incoming wave from the direction of beam 90-8 will be described. Beam 90-8 is formed in a center-down direction relative to the plane of array antenna 80. The row component of the center-down direction is the "downward direction." Therefore, when a user operates switching switch unit 25-1 to specify the direction of beam 90-8 as the desired direction, switching switch unit 25-1 connects input port 43-1, which corresponds to the "downward direction" row component of beam 90-8, to output port 45-1. The user also performs a similar operation on switching switches 25-2 and 25-3. As a result, switching switch unit 25-2 connects input port 43-2 to output port 45-2, and switching switch unit 25-3 connects input port 43-3 to output port 45-3 (S1).

[0105] As mentioned above, the row phase tilt of the beam 90-8 is "-φV Therefore, in the case of an incoming wave from the direction of the beam 90-8, the RF signal obtained from the antenna element 80-2-1, which is in the same column as the antenna element 80-3-1 and adjacent in the row direction, has a phase φ V The RF signal obtained from the antenna element 80-1-1 has a phase delay of φ compared to the RF signal obtained from the antenna element 80-2-1. V Therefore, the phase difference between the USB components of the modulated optical signals modulated and output by the optical modulators 11-1-1, 11-2-1, and 11-3-1 is (-2φ V ,-φ V Similarly, the phase difference of the USB components of the modulated optical signals output by the optical modulators 11-1-2, 11-2-2, and 11-3-2 in the second column and the phase difference of the USB components of the modulated optical signals output by the optical modulators 11-1-3, 11-2-3, and 11-3-3 in the third column are also (-2φ V ,-φ V ,0) (S2).

[0106] Therefore, the phase difference of the USB components of the modulated optical signals supplied to the input ports 31-1, 32-1, and 33-1 of the row-direction scanning matrix circuit 21-1, the phase difference of the USB components of the modulated optical signals supplied to the input ports 31-2, 32-2, and 33-2 of the row-direction scanning matrix circuit 21-2, and the phase difference of the USB components of the modulated optical signals supplied to the input ports 31-3, 32-3, and 33-3 of the row-direction scanning matrix circuit 21-3 are (-2φ V ,-φ V , 0). Therefore, when the row-direction scanning matrix circuits 21-1, 21-2, and 21-3 perform a predetermined row-direction phase scanning process on the USB components of the supplied modulated optical signals, the USB components of the modulated optical signals become in-phase at each of the output ports 37-1, 37-2, and 37-3. Therefore, each of the row-direction scanning matrix circuits 21-1, 21-2, and 21-3 outputs an in-phase combined row-direction optical signal corresponding to the wave arriving from the direction of beam 90-8 from each of the output ports 37-1, 37-2, and 37-3 (S3).

[0107] Each of the frequency converters 23-1, 23-2, and 23-3 receives the row-direction combined optical signal of frequency ch1 output from the output ports 37-1, 37-2, and 37-3 connected to the frequency converters 23-1, 23-2, and 23-3, and converts the frequency of the received row-direction combined optical signal to frequency ch3. Each of the frequency converters 23-1, 23-2, and 23-3 outputs the row-direction combined optical signal converted to frequency ch3 to the input ports 43-1, 43-2, and 43-3 of the switching SW unit 25-1 connected to the frequency converters 23-1, 23-2, and 23-3 (S4).

[0108] As described in the process of S1, in each of the switching switch units 25-1, 25-2, and 25-3, the output ports 45-1, 45-2, and 45-3 are connected to the input ports 43-1, 43-2, and 43-3, respectively. Therefore, each of the switching switch units 25-1, 25-2, and 25-3 outputs the row-direction combined optical signals of frequency ch3 output by the frequency converters 23-1, 23-2, and 23-3 connected to it to the input ports 51-1, 51-2, and 51-3 of the column-direction scanning matrix circuit 51, respectively (S5).

[0109] As described above, the column-direction phase tilt of the beam 90-8 is “0.” Therefore, there is no phase difference between the three row-direction combined optical signals output from the output ports 37-1, 37-2, and 37-3 of the row-direction scanning matrix circuits 21-1, 21-2, and 21-3, respectively. Therefore, the phase difference between the row-direction combined optical signals supplied to the input ports 51-1, 51-2, and 51-3 of the column-direction scanning matrix circuit 51 is (0,0,0). Therefore, when the column-direction scanning matrix circuit 51 performs a predetermined column-direction phase scanning process on the row-direction combined optical signals supplied to the input ports 51-1, 51-2, and 51-3, respectively, the three optical signals output from the output port 51-6 have the same phase. The column-direction scanning matrix circuit 51 outputs an in-phase combined column-direction optical signal corresponding to the wave arriving from the direction of the beam 90-8 from the output port 51-6 (S6).

[0110] The column-direction combined optical signal output from the column-direction scanning matrix circuit 51 via output port 51-6 is supplied to demultiplexer 52-2. Demultiplexer 52-2 demultiplexes the supplied column-direction combined optical signal into optical signals of frequencies ch1, ch2, and ch3. Demultiplexer 52-2 outputs the demultiplexed optical signal of frequency ch1 to output port 55-2, the demultiplexed optical signal of frequency ch2 to output port 56-2, and the demultiplexed optical signal of frequency ch3 to output port 57-2 (S7), thereby completing the process.

[0111] When only the wave arriving from the direction of beam 90-8 is present, the column-direction combined optical signal supplied to demultiplexer 52-2 includes an optical signal of frequency ch3, which has a high signal intensity. Therefore, the optical signal output from output port 57-2 corresponding to frequency ch3 becomes the received signal corresponding to the wave arriving from the direction of beam 90-8.

[0112] (When receiving an incoming wave from the direction of beam 90-6) Next, a process for receiving an incoming wave from the direction of beam 90-6 will be described. Beam 90-6 is formed in the center left direction relative to the plane of array antenna 80. The row component of the center left direction is the "center direction." Therefore, when a user operates switching switch unit 25-1 to specify the direction of beam 90-6 as the desired direction, switching switch unit 25-1 connects input port 42-1, which corresponds to the "center direction" row component of beam 90-1, to output port 45-1. The user also performs a similar operation on switching switches 25-2 and 25-3. As a result, switching switch unit 25-2 connects input port 42-2 to output port 45-2, and switching switch unit 25-3 connects input port 42-3 to output port 45-3 (S1).

[0113] As described above, the row-direction phase tilt of beam 90-6 is "0." Therefore, the USB components of the modulated optical signals output by each of optical modulators 11-1-1, 11-2-1, and 11-3-1 are in phase. Similarly, the USB components of the modulated optical signals output by each of optical modulators 11-1-2, 11-2-2, and 11-3-2 are in phase. The USB components of the modulated optical signals output by each of optical modulators 11-1-3, 11-2-3, and 11-3-3 are in phase (S2).

[0114] Therefore, the phase difference of the USB components of the modulated optical signals supplied to input ports 31-1, 32-1, and 33-1 of row-direction scanning matrix circuit 21-1, the phase difference of the USB components of the modulated optical signals supplied to input ports 31-2, 32-2, and 33-2 of row-direction scanning matrix circuit 21-2, and the phase difference of the USB components of the modulated optical signals supplied to input ports 31-3, 32-3, and 33-3 of row-direction scanning matrix circuit 21-3 are (0,0,0). Therefore, when row-direction scanning matrix circuits 21-1, 21-2, and 21-3 perform a predetermined row-direction phase scanning process on the USB components of the supplied modulated optical signals, the USB components of the modulated optical signals have the same phase at each of output ports 36-1, 36-2, and 36-3. Therefore, each of the row-direction scanning matrix circuits 21-1, 21-2, and 21-3 outputs an in-phase row-direction combined optical signal corresponding to the wave arriving from the direction of the beam 90-6 from each of the output ports 36-1, 36-2, and 36-3 (S3).

[0115] Each of the frequency converters 22-1, 22-2, and 22-3 receives the row-direction combined optical signal of frequency ch1 output from the output ports 36-1, 36-2, and 36-3 connected to the frequency converter 22-1, 22-2, and 22-3, and converts the frequency of the received row-direction combined optical signal to frequency ch2. Each of the frequency converters 22-1, 22-2, and 22-3 outputs the row-direction combined optical signal converted to frequency ch2 to the input ports 42-1, 42-2, and 42-3 of the switching SW unit 25-1 connected to the frequency converter 22-1, 22-2, and 22-3 (S4).

[0116] As described in the process of S1, in each of the switching switch units 25-1, 25-2, and 25-3, the output ports 45-1, 45-2, and 45-3 are connected to the input ports 42-1, 42-2, and 42-3, respectively. Therefore, each of the switching switch units 25-1, 25-2, and 25-3 outputs the row-direction combined optical signals of frequency ch2 output by the frequency converters 22-1, 22-2, and 22-3 connected to it to the input ports 51-1, 51-2, and 51-3 of the column-direction scanning matrix circuit 51, respectively (S5).

[0117] As mentioned above, the column-wise phase gradient of the beam 90-6 is "-φ H Therefore, the RF signal obtained from the antenna element 80-1-2 in the second column, which is in the same row as the antenna element 80-1-3 in the first row and adjacent in the column direction, has a phase φ H The RF signal obtained from the antenna element 80-1-1 has a phase delay of φ, which is greater than that of the RF signal obtained from the antenna element 80-1-2. H Therefore, the phase difference between the RF signals obtained from each of the antenna elements 80-1-1, 80-1-2, and 80-1-3 in the first row is (-2φ H ,-φ H Similarly, the phase difference of the RF signals obtained from each of the antenna elements 80-2-1, 80-2-2, and 80-2-3 in the second row and the phase difference of the RF signals obtained from each of the antenna elements 80-3-1, 80-3-2, and 80-3-3 in the third row are (-2φ H ,-φ H ,0).

[0118] Therefore, the phase difference between the row-direction combined optical signals supplied to the input ports 51-1, 51-2, and 51-3 of the column-direction scanning matrix circuit 51 is (-2φ H ,-φ H, 0). Therefore, when the column-direction scanning matrix circuit 51 performs a predetermined column-direction phase scanning process on the row-direction combined optical signals supplied to each of the input ports 51-1, 51-2, and 51-3, the three optical signals output from the output port 51-7 have the same phase. The column-direction scanning matrix circuit 51 outputs an in-phase column-direction combined optical signal corresponding to the wave arriving from the direction of the beam 90-6 from the output port 51-7 (S6).

[0119] The column-direction combined optical signal output from the column-direction scanning matrix circuit 51 via output port 51-7 is supplied to demultiplexer 52-3. Demultiplexer 52-3 demultiplexes the supplied column-direction combined optical signal into optical signals of frequencies ch1, ch2, and ch3. Demultiplexer 52-3 outputs the demultiplexed optical signal of frequency ch1 to output port 55-3, the demultiplexed optical signal of frequency ch2 to output port 56-3, and the demultiplexed optical signal of frequency ch3 to output port 57-3 (S7), thereby completing the process.

[0120] When only the wave arriving from the direction of beam 90-6 is present, the column-direction combined optical signal supplied to demultiplexer 52-3 includes an optical signal of frequency ch2, which has a high signal intensity. Therefore, the optical signal output from output port 56-3 corresponding to frequency ch2 becomes the received signal corresponding to the wave arriving from the direction of beam 90-6.

[0121] (When receiving waves arriving from multiple directions) When receiving an incoming wave from the direction of beam 90-1, an incoming wave from the direction of beam 90-8, and an incoming wave from the direction of beam 90-6 in parallel, the user performs the following operations on switching switches 25-1, 25-2, and 25-3. That is, when the user operates switching switches 25-1, 25-2, and 25-3 to specify beams 90-1, 90-8, and 90-6 as the desired directions, switching switch 25-1 connects input ports 41-1, 42-1, and 43-1 to output port 45-1. Switching switch 25-2 connects input ports 41-2, 42-2, and 43-2 to output port 45-2. Switching switch 25-3 connects input ports 41-3, 42-3, and 43-3 to output port 45-3. As a result, the above-mentioned processing for the beam 90-1, processing for the beam 90-8, and processing for the beam 90-6 are performed in parallel.

[0122] As a result, the reception signal corresponding to the wave arriving from the direction of beam 90-1, the reception signal corresponding to the wave arriving from the direction of beam 90-8, and the reception signal corresponding to the wave arriving from the direction of beam 90-6 are obtained in parallel in the reception directivity control device 1. In other words, the reception directivity control device 1 can form multiple beams, beams 90-1, 90-8, and 90-6, and receive the waves arriving from the directions of the formed multiple beams in parallel.

[0123] (Effects of the first embodiment) In the reception directivity control device 1 of the first embodiment, the row direction scanning unit 20 performs a predetermined row direction phase scanning process for each combination of USB components of modulated optical signals in the same column, in which a phase gradient is applied to each of the USB components of the modulated optical signals included in each combination to align the phases of the row direction components in the beam forming direction, taking into account the difference in the position of the corresponding row and the row direction phase gradient that occurs depending on the beam forming direction. Here, the phases of the row direction components in the beam forming direction in the above example refer to the phases of the USB components of the modulated optical signals corresponding to the directions of beams 90-1, 90-2, and 90-3 corresponding to the "upward direction," the phases of the USB components of the modulated optical signals corresponding to beams 90-4, 90-5, and 90-6 corresponding to the "middle direction," and the phases of the USB components of the modulated optical signals corresponding to beams 90-7, 90-8, and 90-9 corresponding to the "downward direction."

[0124] The row direction scanning unit 20 generates row direction combined optical signals corresponding to each row direction component of the beam forming direction by a predetermined row direction phase scanning process, and converts the frequencies of the generated row direction combined optical signals so that each row direction component of the beam forming direction has a different frequency. After conversion, the row direction scanning unit 20 selects row direction combined optical signals corresponding to the row direction component of the beam forming direction that matches the specified desired direction, and outputs them to the column direction scanning unit 50.

[0125] The column direction scanning unit 50 performs a predetermined column direction phase scanning process to impart a phase gradient to align the phase of each column direction component in the beam formation direction to each row direction combined optical signal output by the row direction scanning unit 20, taking into account the difference in the position of the corresponding column and the column direction phase gradient that occurs depending on the beam formation direction. Here, the phase of the column direction component in the beam formation direction is, in the above example, the phase of the row direction combined optical signal corresponding to the direction of beams 90-1, 90-4, and 90-7 corresponding to "rightward," the phase of the row direction combined optical signal corresponding to beams 90-2, 90-5, and 90-8 corresponding to "centerward," and the phase of the row direction combined optical signal corresponding to beams 90-3, 90-6, and 90-9 corresponding to "leftward."

[0126] The column direction scanning unit 50 generates a column direction combined optical signal for each beam forming direction by a predetermined column direction phase scanning process. The column direction scanning unit 50 demultiplexes each of the generated column direction combined optical signals into optical signals of frequencies ch1, ch2, and ch3, and outputs the demultiplexed optical signals. This allows only received signals of incoming waves arriving from the beam forming direction that matches the specified desired direction to be obtained. If multiple desired directions are specified, received signals corresponding to each of the incoming waves arriving from the beam forming directions that match each of the specified desired directions can be obtained in parallel.

[0127] The array antenna 80 connected to the reception directivity control device 1 shown in FIG. 1 is a 3×3 array antenna with nine antenna elements, but the number of antenna elements may be increased or decreased. If the number of antenna elements is increased or decreased, a configuration change is required to increase or decrease the number of optical modulators 11-1-1 to 11-3-3 so that the number is equal to the number of antenna elements. In the row direction scanning unit 20 and the column direction scanning unit 50, a configuration change is required to increase or decrease the number of components and ports according to the increased or decreased number of rows and columns in the array antenna 80. Furthermore, in the row direction scanning matrix circuits 21-1, 21-2, and 21-3 and the column direction scanning matrix circuit 51, a configuration change is required to increase or decrease the logic for applying a phase gradient according to the increase or decrease in the number of ports.

[0128] However, unlike Patent Documents 1 and 2, in which the column-direction phase gradient is directly imparted by a wavelength dispersion line, the reception directivity control device 1 is configured to reduce the circuit size by making it possible to impart the phase gradient using a single column-direction scanning matrix circuit 51. Therefore, even if the number of antenna elements is increased in the reception directivity control device 1, only the above-described configuration change is made, and there is no significant increase in the size of the circuit that imparts the phase gradient, as in Patent Documents 1 and 2.

[0129] In the reception directivity control device 1, the circuit configuration other than the optical modulators 11-1-1 to 11-3-3 is connected by optical lines, so it can be configured in a planar manner rather than a three-dimensional configuration as in the techniques disclosed in Patent Documents 1 and 2, and even if the number of antenna elements in the array antenna 80 increases, it is only expanded in a planar manner. Therefore, even if the number of antenna elements is increased, the number of parts and wiring in the reception directivity control device 1 does not increase significantly, and the circuit structure does not become complicated.

[0130] Therefore, when controlling the reception directivity of the array antenna 80 using the reception directivity control device 1 of the first embodiment, even if the size of the array antenna 80 becomes large, it is possible to implement it using a circuit with a simple structure that is suitable for miniaturization and mass production.

[0131] (Another configuration example of the first embodiment) In the reception directivity control device 1 shown in FIG. 1, when all of the input ports 41-1 to 43-1, 41-2 to 43-2, 41-3 to 43-3 of the switching SW units 25-1, 25-2, and 25-3 are connected to the output ports 45-1, 45-2, and 45-3, respectively, the switching SW units 25-1, 25-2, and 25-3 function as multiplexers that multiplex row-direction combined optical signals of frequencies ch1, ch2, and ch3.

[0132] In this case, for example, the reception directivity control device 1a shown in FIG. 5 may be applied, in which the switching switches 25-1, 25-2, and 25-3 of the reception directivity control device 1 are replaced with multiplexers 26-1, 26-2, and 26-3, respectively. The multiplexer 26-1 has three input ports and one output port. The three input ports of the multiplexer 26-1 are connected to the output port 35-1 of the row scanning matrix circuit 21-1, the frequency converter 22-1, and the frequency converter 23-1. The output port of the multiplexer 26-1 is connected to the input port 51-1 of the column scanning matrix circuit 51.

[0133] In the above description of the connection configuration for multiplexer 26-1, the connection configuration obtained by replacing the branch number "-1" with "-2" is the connection configuration for multiplexer 26-2, and the connection configuration obtained by replacing the branch number "-1" with "-3" is the connection configuration for multiplexer 26-3. Multiplexers 26-1, 26-2, and 26-3 multiplex a row-direction combined optical signal of frequency ch1, a row-direction combined optical signal of frequency ch2, and a row-direction combined optical signal of frequency ch3, which are supplied from three input ports. Multiplexers 26-1, 26-2, and 26-3 output the combined optical signals from their output ports.

[0134] 5, the reception directivity control device 1a does not allow the user to specify a desired direction as with the reception directivity control device 1, but it does not require the operation of switching switches 25-1, 25-2, and 25-3 that is required with the reception directivity control device 1. When the reception directivity control device 1a receives waves arriving from all directions of beams 90-1 to 90-9, the received signals corresponding to the waves arriving from each of the directions of beams 90-1 to 90-9 are obtained from output ports 55-1 to 57-1, 55-2 to 57-2, and 55-3 to 57-3 of branching filters 52-1, 52-2, and 52-3, respectively, in the pattern shown in FIG.

[0135] (Second embodiment) In the reception directivity control device 1 of the first embodiment shown in Fig. 1, it is assumed that incoming waves arrive from directions with different horizontal components among the directions of beams 90-1 to 90-9. The horizontal components in the directions of beams 90-1 to 90-9 are three components: a "rightward" horizontal component in the directions of beams 90-1, 90-4, and 90-7, a "middle" horizontal component in the directions of beams 90-2, 90-5, and 90-8, and a "leftward" horizontal component in the directions of beams 90-3, 90-6, and 90-9.

[0136] If there are three directions, namely, any one of the directions of "rightward" beams 90-1, 90-4, 90-7, any one of the directions of "inner" beams 90-2, 90-5, 90-8, and any one of the directions of "leftward" beams 90-3, 90-6, 90-9, these directions fall under the above-mentioned "directions of beams 90-1 to 90-9 with different horizontal components."

[0137] When incoming waves arrive from only three directions with different horizontal components among the directions of beams 90-1 to 90-9, the column scanning matrix circuit 51 outputs in-phase column combined optical signals corresponding to the incoming waves from each of the three directions from different output ports 51-5, 51-6, and 57-1. That is, an in-phase column combined optical signal corresponding to an incoming wave from any one direction among the "rightward" directions is output from output port 51-1, an in-phase column combined optical signal corresponding to an incoming wave from any one direction among the "middle" directions is output from output port 51-6, and an in-phase column combined optical signal corresponding to an incoming wave from any one direction among the "leftward" directions is output from output port 51-7.

[0138] In this case, the column-direction combined optical signals output from the output ports 51-5, 51-6, and 51-7 can be used as received signals corresponding to the incoming waves without being demultiplexed using the demultiplexers 52-1, 52-2, and 52-3.

[0139] Therefore, when incoming waves arrive from directions with different horizontal components among the directions of beams 90-1 to 90-9, received signals can be obtained in parallel using a reception directivity control device 1b shown in Figure 6, which is obtained by removing the branching filters 52-1, 52-2, and 52-3 from the reception directivity control device 1 of Figure 1. As shown in Figure 6, the reception directivity control device 1b according to the second embodiment is configured to include the electro-optical conversion unit 10 and row direction scanning unit 20 included in the reception directivity control device 1, and a column direction scanning unit 50a, which is obtained by removing the branching filters 52-1, 52-2, and 52-3 from the column direction scanning unit 50.

[0140] For example, suppose that there are incoming waves from the directions of beams 90-1, 90-8, and 90-6. In this case, the directions of beams 90-1, 90-8, and 90-6 correspond to directions with different horizontal components. Therefore, if the switching SW units 25-1, 25-2, and 25-3 each receive an operation from a user to specify the direction of beams 90-1, 90-8, and 90-6 as a desired direction and connect all of the input ports 41-1 to 43-1, 41-2 to 43-2, and 41-3 to 43-3, respectively, to the output ports 45-1, 45-2, and 45-3, respectively, then received signals corresponding to the incoming waves from the directions of beams 90-1, 90-8, and 90-6 can be individually obtained from the output ports 51-5, 51-6, and 51-7 of the column-direction scanning matrix circuit 51, as shown in FIG. 6 .

[0141] (Another configuration example (part 1) of the second embodiment) When there are incoming waves from directions with the same horizontal component among the directions of beams 90-1 to 90-9, it is not possible to obtain a received signal for each incoming wave with the reception directivity control device 1b shown in Fig. 6. However, even if the horizontal component is the same, when the incoming waves arrive from directions with different vertical components among the directions of beams 90-1 to 90-9, it is possible to obtain a received signal for each incoming wave by using the reception directivity control device 1c according to another configuration example (part 1) of the second embodiment shown in Fig. 7.

[0142] If there are three directions, namely, any one of the "upward" directions of beams 90-1, 90-2, and 90-3, any one of the "middle" directions of beams 90-4, 90-5, and 90-6, and any one of the "downward" directions of beams 90-7, 90-8, and 90-9, these directions fall under the above-mentioned "directions of beams 90-1 to 90-9 with different vertical components."

[0143] As shown in Fig. 7, the reception directivity control device 1c includes a main body 110, a rotation mechanism 111, and a shaft 112. The rotation mechanism 111 is connected to one end of the shaft 112, and the main body 110 is connected to the other end of the shaft 112, so that a plane perpendicular to the central axis of rotation of the shaft 112 is parallel to the surface of the array antenna 80. The rotation mechanism 111 supplies power to the shaft 112 in response to a user's operation. When the shaft 112 receives power from the rotation mechanism 111, it rotates around its central axis.

[0144] Main body 110 is, for example, reception directivity control device 1b shown in Fig. 6. Rotation mechanism 111 rotates shaft 112, causing shaft 112 to rotate about its central axis, and accompanying this rotation, main body 110 and array antenna 80 connected to main body 110 rotate. For example, assume a three-dimensional coordinate system in which the row axis on the plane of array antenna 80 is the X axis, the column axis is the Y axis, and a straight line perpendicular to the plane of array antenna 80 is the Z axis. In this three-dimensional coordinate system, the plane of array antenna 80 rotates while maintaining the position of the Z axis and while maintaining the orthogonal relationship between the X axis and the Y axis.

[0145] When the plane of array antenna 80 is rotated 90 degrees using reception directivity control device 1c shown in Fig. 7, the row direction becomes horizontal and the column direction becomes vertical, as in array antenna 80a shown in Fig. 7. Beams 90-1 to 90-9 formed in the case of array antenna 80 will rotate together with array antenna 80, but here, the nine-directional beams formed in the arrangement of array antenna 80a are newly assigned reference numerals 90-1 to 90-9, and the directions of beams 90-1 to 90-9 in the state of array antenna 80a are assumed to be the directions shown in Fig. 3.

[0146] In the arrangement of array antenna 80a, the row direction is horizontal and the column direction is vertical. Therefore, when the reception directivity control device 1b of Fig. 6 is used with the arrangement of array antenna 80a, the USB components of modulated optical signals corresponding to the RF signals supplied by antenna elements 80-1-1, 80-2-1, and 80-3-1 arranged in the horizontal direction are supplied to input ports 31-1, 32-1, and 33-1 of row direction scanning matrix circuit 21-1. Similarly, the USB components of modulated optical signals corresponding to the RF signals supplied by antenna elements 80-1-2, 80-2-2, and 80-3-2 arranged in the horizontal direction are supplied to input ports 31-2, 32-2, and 33-2 of row direction scanning matrix circuit 21-2. The input ports 31-3, 32-3, and 33-3 of the row-direction scanning matrix circuit 21-3 are supplied with the USB components of modulated optical signals corresponding to the RF signals supplied by the antenna elements 80-1-3, 80-2-3, and 80-3-3 arranged in the horizontal direction.

[0147] Therefore, the USB components of modulated optical signals corresponding to "leftward" are in phase at the output ports 35-1, 35-2, and 35-3 of the row direction scanning matrix circuits 21-1, 21-2, and 21-3. The USB components of modulated optical signals corresponding to "centerward" are in phase at the output ports 36-1, 36-2, and 36-3. The USB components of modulated optical signals corresponding to "rightward" are in phase at the output ports 37-1, 37-2, and 37-3.

[0148] Furthermore, an in-phase combined column-direction optical signal corresponding to the "upward direction" is obtained at output port 51-5 of the column-direction scanning matrix circuit 51. An in-phase combined column-direction optical signal corresponding to the "middle direction" is obtained at output port 51-6. An in-phase combined column-direction optical signal corresponding to the "downward direction" is obtained at output port 51-7.

[0149] Therefore, when incoming waves arrive from directions in which the vertical components of beams 90-1 to 90-9 are different, the receiving directivity control device 1c can be used to rotate the plane of array antenna 80 by 90 degrees, so that the arrangement of antenna elements 80-1-1 to 80-3-3 becomes the arrangement of array antenna 80a, thereby making it possible to separate the received signals for each arriving wave and obtain them in parallel.

[0150] In a usage mode of the reception directivity control device 1c, when the incoming waves arrive from directions with different horizontal components among the directions of the beams 90-1 to 90-9, the directional components extracted at the output ports 51-5, 51-6, and 51-7 of the column direction scanning matrix circuit 51 must be set to the horizontal components of "rightward," "inward," and "leftward." Therefore, the column direction must be aligned with the horizontal direction, and therefore the array antenna 80 must be positioned accordingly.

[0151] On the other hand, when the incoming waves are coming from directions with different vertical components among the directions of the beams 90-1 to 90-9, the directional components extracted at the output ports 51-5, 51-6, and 51-7 of the column-direction scanning matrix circuit 51 must be the vertical components "upward," "inward," and "downward." Therefore, the column direction must be aligned with the vertical direction, and therefore the array antenna 80a must be positioned accordingly.

[0152] Therefore, by rotating the plane of array antenna 80 so that the incoming waves arrive from directions in which the column direction components of beams 90-1 to 90-9 are different in the row and column direction coordinate system of array antenna 80, it becomes possible to separate and obtain the received signals of all the incoming waves in parallel without using splitters 52-1, 52-2, and 52-3.

[0153] In this case, when using the reception directivity control device 1b with the array antenna 80a rotated by 90 degrees, the row direction becomes horizontal and the column direction becomes vertical. Therefore, the user should note that the input ports 41-1, 41-2, and 41-3 of the switching SW units 25-1, 25-2, and 25-3 are assigned to face left, the input ports 42-1, 42-2, and 42-3 are assigned to face center, and the input ports 43-1, 43-2, and 43-3 are assigned to face right.

[0154] Although the entire main body 110 is rotated in FIG. 7, only the portion of the electro-optical conversion unit 10, which is preferably disposed near the antenna elements 80-1-1 to 80-3-3, may be rotated together with the antenna elements 80-1-1 to 80-3-3.

[0155] (Another configuration example (part 2) of the second embodiment) Fig. 8 is a diagram showing the internal configuration of a reception directivity control device 1d according to another configuration example (part 2) of the second embodiment, and an array antenna 80 connected to the reception directivity control device 1d. The reception directivity control device 1d has the same configuration as the reception directivity control device 1b shown in Fig. 6, and further includes a matrix rearrangement unit 15. The matrix rearrangement unit 15 includes SW circuits 15-1 to 15-6.

[0156] The SW circuit 15-1 has an input side connected to the optical modulator 11-2-1 and an output side connected to an input port 32-1 of the row direction scanning matrix circuit 21-1 and an input port 31-2 of the row direction scanning matrix circuit 21-2. In a first switching state, the SW circuit 15-1 connects the input side to the input port 32-1, and in a second switching state, connects the input side to the input port 31-2.

[0157] The SW circuit 15-2 has an input side connected to the optical modulator 11-3-1 and an output side connected to an input port 33-1 of the row direction scanning matrix circuit 21-1 and an input port 31-3 of the row direction scanning matrix circuit 21-3. In a first switching state, the SW circuit 15-2 connects the input side to the input port 33-1, and in a second switching state, connects the input side to the input port 31-3.

[0158] The SW circuit 15-3 has an input side connected to the optical modulator 11-1-2 and an output side connected to an input port 31-2 of the row direction scanning matrix circuit 21-2 and an input port 32-1 of the row direction scanning matrix circuit 21-1. In a first switching state, the SW circuit 15-3 connects the input side to the input port 31-2, and in a second switching state, connects the input side to the input port 32-1.

[0159] The SW circuit 15-4 has an input side connected to the optical modulator 11-3-2 and an output side connected to the input port 33-2 of the row direction scanning matrix circuit 21-2 and the input port 32-3 of the row direction scanning matrix circuit 21-3. In a first switching state, the SW circuit 15-4 connects the input side to the input port 33-2, and in a second switching state, connects the input side to the input port 32-3.

[0160] The SW circuit 15-5 has an input side connected to the optical modulator 11-1-3 and an output side connected to the input port 31-3 of the row direction scanning matrix circuit 21-3 and the input port 33-1 of the row direction scanning matrix circuit 21-1. In a first switching state, the SW circuit 15-5 connects the input side to the input port 31-3, and in a second switching state, connects the input side to the input port 33-1.

[0161] The SW circuit 15-6 has an input side connected to the optical modulator 11-2-3 and an output side connected to an input port 32-3 of the row direction scanning matrix circuit 21-3 and an input port 33-2 of the row direction scanning matrix circuit 21-2. In a first switching state, the SW circuit 15-6 connects the input side to the input port 32-3, and in a second switching state, connects the input side to the input port 33-2.

[0162] The matrix permutation unit 15 can be switched between a first switching state and a second switching state by a user operation. Therefore, when incoming waves arrive from directions with different horizontal components among the beams 90-1 to 90-9, the user sets the matrix permutation unit 15 to the first switching state. In this case, the SW circuits 15-1 to 15-6 are connected to the row scanning matrix circuits 21-1, 21-2, and 21-3 in the connection relationships shown by the dashed lines. In this case, the reception directivity control device 1d performs the same processing as that performed by the reception directivity control device 1b shown in FIG. 6 on the incoming waves received by the antenna elements 80-1-1 to 80-3-3 of the array antenna 80. As a result, when incoming waves arrive from directions with different horizontal components among the beams 90-1 to 90-9, it is possible to separate the received signals of the incoming waves and obtain them in parallel.

[0163] On the other hand, when the incoming waves are coming from directions with different vertical components among the beams 90-1 to 90-9, the user sets the state of the matrix permutation unit 15 to the second switching state. In this case, the SW circuits 15-1 to 15-6 are connected to the row-direction scanning matrix circuits 21-1, 21-2, and 21-3 in the connection relationships shown by solid lines. In this case, the rows and columns of the optical modulators 11-1-1 to 11-3-3 are permuted.

[0164] Therefore, the input ports 31-1, 32-1, and 33-1 of the row scanning matrix circuit 21-1 are supplied with USB components of modulated optical signals corresponding to the RF signals supplied by the horizontally arranged antenna elements 80-1-1, 80-1-2, and 80-1-3. Similarly, the input ports 31-2, 32-2, and 33-2 of the row scanning matrix circuit 21-2 are supplied with USB components of modulated optical signals corresponding to the RF signals supplied by the horizontally arranged antenna elements 80-2-1, 80-2-2, and 80-2-3. The input ports 31-3, 32-3, and 33-3 of the row scanning matrix circuit 21-3 are supplied with USB components of modulated optical signals corresponding to the RF signals supplied by the horizontally arranged antenna elements 80-3-1, 80-3-2, and 80-3-3.

[0165] Therefore, the USB components of modulated optical signals corresponding to "rightward" are in phase at the output ports 35-1, 35-2, and 35-3 of the row direction scanning matrix circuits 21-1, 21-2, and 21-3. The USB components of modulated optical signals corresponding to "middle" are in phase at the output ports 36-1, 36-2, and 36-3. The USB components of modulated optical signals corresponding to "leftward" are in phase at the output ports 37-1, 37-2, and 37-3.

[0166] Furthermore, an in-phase combined column-direction optical signal corresponding to the "upward direction" is obtained at output port 51-5 of the column-direction scanning matrix circuit 51. An in-phase combined column-direction optical signal corresponding to the "middle direction" is obtained at output port 51-6. An in-phase combined column-direction optical signal corresponding to the "downward direction" is obtained at output port 51-7.

[0167] Therefore, in the reception directivity control device 1d, when incoming waves arrive from directions with different vertical components among the directions of beams 90-1 to 90-9, by setting the matrix shuffling unit 15 to the second switching state, it is possible to make the incoming waves arrive from directions with different column components among the directions of beams 90-1 to 90-9 in the coordinate system of the row and column directions of the array antenna 80. This makes it possible to separate the received signals for each incoming wave and obtain them in parallel.

[0168] In the reception directivity control device 1d, the number of antenna elements in the row direction is the same as the number of antenna elements in the column direction. Therefore, by using the matrix permutation unit 15, it is possible to permute the rows and columns of the USB components of the modulated optical signals output from the optical modulators 11-1-1 to 11-3-3 without changing the configurations of the row direction scanner 20 and the column direction scanner 50a. In the second switching state, the output ports 35-1, 35-2, and 35-3 of the row direction scanning matrix circuits 21-1, 21-2, and 21-3 correspond to the "rightward direction," the output ports 36-1, 36-2, and 36-3 correspond to the "inward direction," and the output ports 37-1, 37-2, and 37-3 correspond to the "leftward direction." This is the opposite of the case where the arrangement of the array antenna 80a is used in the other configuration example (part 1) of the second embodiment. However, the output port 51-5 of the column direction scanning matrix circuit 51 corresponds to the "upward direction," the output port 51-6 corresponds to the "middle direction," and the output port 51-7 corresponds to the "downward direction," which is the same as when the arrangement of the array antenna 80a is used in the other configuration example (part 1) of the second embodiment. Therefore, by using the reception directivity control device 1d, it is possible to obtain the same effect as when the reception directivity control device 1c according to the other configuration example (part 1) of the second embodiment is used.

[0169] However, when using the receiving directivity control device 1d in the second switching state, the rows and columns are swapped, so the user needs to note that the input ports 41-1, 41-2, 41-3 of the switching SW units 25-1, 25-2, 25-3 are assigned to face right, the input ports 42-1, 42-2, 42-3 are assigned to face inwards, and the input ports 43-1, 43-2, 43-3 are assigned to face left.

[0170] (Another configuration example (part 3) of the second embodiment) 9 is a diagram showing the internal configuration of a reception directivity control device 1e according to another configuration example (part 3) of the second embodiment, and an array antenna 80 connected to the reception directivity control device 1e. The reception directivity control device 1e includes the electro-optical conversion unit 10 and column direction scanning unit 50a included in the reception directivity control device 1b shown in FIG. 6, and further includes a row direction scanning unit 20b in which a device selection unit 27 is added to the row direction scanning unit 20.

[0171] The device-to-be-used selection unit 27 is connected to the frequency converters 22-1, 22-2, 22-3, 23-1, 23-2, and 23-3 and, for example, a power supply (not shown). In response to a user's operation, the device-to-be-used selection unit 27 selects whether or not to supply power from the power supply to each of the frequency converters 22-1, 22-2, 22-3, 23-1, 23-2, and 23-3. When the device-to-be-used selection unit 27 selects to supply power, the frequency converters 22-1, 22-2, 22-3, 23-1, 23-2, and 23-3 are supplied with power, and thus convert the frequency of the supplied optical signal and output the converted signal. When the device-to-be-used selection unit 27 selects not to supply power, the power supply is stopped, and thus the frequency converters 22-1, 22-2, 22-3, 23-1, 23-2, and 23-3 do not convert the frequency of the supplied optical signal and output the supplied optical signal as is.

[0172] By using the reception directivity control device 1e, the following becomes possible. When incoming waves arrive from directions with different horizontal components among the directions of beams 90-1 to 90-9, the column-direction combined optical signals output from the output ports 51-5, 51-6, and 51-7 of the column-direction scanning matrix circuit 51 can be used as reception signals corresponding to the incoming waves, without using demultiplexers 52-1, 52-2, and 52-3, as described with reference to the reception directivity control device 1b shown in Fig. 6. The fact that demultiplexers 52-1, 52-2, and 52-3 are not required means that reception signals corresponding to incoming waves from directions with different horizontal components can be obtained without performing frequency conversion using frequency converters 22-1, 22-2, 22-3, 23-1, 23-2, and 23-3.

[0173] Therefore, when incoming waves arrive from directions with different horizontal components among the directions of beams 90-1 to 90-9, the user can operate device selection unit 27 to stop the supply of power to all frequency converters 22-1, 22-2, 22-3, 23-1, 23-2, and 23-3, thereby reducing power consumption and obtaining received signals in parallel corresponding to incoming waves from directions with different horizontal components.

[0174] (Use scenarios of each configuration example of the second embodiment) A description will be given of application scenarios of each configuration example of the second embodiment with reference to the flowchart shown in Fig. 10. When there are only incoming waves from directions with different horizontal components among the directions of beams 90-1 to 90-9 (Sa1, Yes), the reception directivity control device 1e shown in Fig. 9 is used to stop the supply of power to frequency converters 22-1, 22-2, 22-3, 23-1, 23-2, and 23-3 (Sa4). This makes it possible to obtain received signals corresponding to the incoming waves in parallel while reducing power consumption.

[0175] There are waves arriving from directions with the same horizontal component in the direction of beams 90-1 to 90-9 (Sa1, No), but the arriving waves are waves arriving from directions with different vertical components in the direction of beams 90-1 to 90-9 (Sa2, Yes).

[0176] In this case, a reception directivity control device 1e is applied to main body 110 of another configuration example (part 1) of the second embodiment shown in Fig. 7, and rotation mechanism 111 is used to rotate it 90 degrees, so that antenna elements 80-1-1 to 80-3-3 included in array antenna 80 are arranged in the same manner as array antenna 80a (Sa3). Then, the user operates device selection unit 27 to stop the supply of power to all frequency converters 22-1, 22-2, 22-3, 23-1, 23-2, and 23-3 (Sa4). This makes it possible to obtain, in parallel, reception signals whose vertical components correspond to waves arriving from different directions while reducing power consumption.

[0177] As an alternative to the use mode Sa3, the matrix rearrangement unit 15 included in the reception directivity control device 1d shown in Fig. 8 may be applied to the reception directivity control device 1e. In this case, the user operates the matrix rearrangement unit 15 to set the state of the matrix rearrangement unit 15 to the second switching state. Then, the user operates the device-in-use selection unit 27 to stop the supply of power to all frequency converters 22-1, 22-2, 22-3, 23-1, 23-2, and 23-3 (Sa4). This makes it possible to obtain, in parallel, received signals whose vertical components correspond to waves arriving from different directions while reducing power consumption.

[0178] Assume that the direction from which the incoming wave arrives corresponds to the same horizontal component of the directions of beams 90-1 to 90-9 (Sa1, No), and also corresponds to the same vertical component of the directions of beams 90-1 to 90-9 (Sa2, No). In this case, since the configuration examples of the second embodiment cannot separate and obtain received signals corresponding to the arriving waves, it is necessary to use the reception directivity control device 1 shown in Fig. 1 of the first embodiment or the reception directivity control device 1a shown in Fig. 5 (Sa5).

[0179] (Effects of the second embodiment) Although the number of desired directions that can be received in parallel is limited in the reception directivity control devices 1b, 1c, 1d, and 1e compared to when the reception directivity control device 1 of the first embodiment is used, the number of components of the branching filters 52-1, 52-2, and 52-3 can be reduced, simplifying the device configuration. Furthermore, the reception directivity control device 1e can stop the supply of power to the frequency converters 22-1, 22-2, 22-3, 23-1, 23-2, and 23-3, thereby reducing power consumption.

[0180] As in the first embodiment, the reception directivity control devices 1b, 1c, 1d, and 1e impart phase gradients using the row scanning matrix circuits 21-1, 21-2, and 21-3 and the column scanning matrix circuit 51. Therefore, when controlling the reception directivity of the array antenna 80, even if the size of the array antenna 80 increases, it is possible to implement it using a circuit with a simple structure that is suitable for miniaturization and mass production.

[0181] (Third embodiment) In the first and second embodiments described above, examples have been shown in which antenna elements 80-1-1 to 80-3-3 in the array antenna 80 are arranged with three elements in the row direction and three elements in the column direction. In contrast to this, in the third embodiment, two configuration examples will be described in which the number of antenna elements in the row direction is different from the number of antenna elements in the column direction, and further the number of beams formed in the row direction is different from that in the column direction. As a configuration example (part 1) of the third embodiment, a reception directivity control device 1f shown in FIG. 11 will be described, and as a configuration example (part 2) of the third embodiment, a reception directivity control device 1g shown in FIG. 14 will be described. Note that in the third embodiment, the same components as those in the first and second embodiments are denoted by the same reference numerals.

[0182] (Configuration Example (Part 1) of the Third Embodiment) FIG. 11 is a block diagram showing the internal configuration of a reception directivity control device 1f according to a configuration example (part 1) of the third embodiment, and an array antenna 80b connected to the reception directivity control device 1f. Connecting the array antenna 80b to the reception directivity control device 1f forms a so-called phased array antenna. As shown in FIG. 12, the array antenna 80b is a 4×2 array antenna having eight antenna elements: four elements arranged along the row direction and two elements arranged along the column direction, for a total of eight antenna elements: 80-1-1, 80-1-2, 80-2-1, 80-2-2, 80-3-1, 80-3-2, 80-4-1, and 80-4-2. Hereinafter, in the arrangement of the array antenna 80b, the vertical direction is also referred to as the row direction, and the horizontal direction is also referred to as the column direction. The antenna elements 80-1-1 to 80-4-2 are arranged on a plane, i.e., on the surface of the array antenna 80b.

[0183] The arrangement will be described in more detail. Antenna elements 80-1-1, 80-2-1, 80-3-1, and 80-4-1 in the first column are arranged at equal intervals and parallel to the axis in the row direction. Similarly, antenna elements 80-1-2, 80-2-2, 80-3-2, and 80-4-2 in the second column are arranged at equal intervals and parallel to the axis in the row direction. Antenna elements 80-1-1, 80-2-1, 80-3-1, and 80-4-1 are arranged so that the distance between adjacent antenna elements is the same as the distance between adjacent antenna elements in antenna elements 80-1-2, 80-2-2, 80-3-2, and 80-4-2.

[0184] The line segment connecting antenna elements 80-1-1 and 80-1-2 in the same row, the line segment connecting antenna elements 80-2-1 and 80-2-2, the line segment connecting antenna elements 80-3-1 and 80-3-2, and the line segment connecting antenna elements 80-4-1 and 80-4-2 are all parallel to the column axis and are all the same length. Therefore, the shape with vertices at the positions of antenna elements 80-1-1, 80-1-2, 80-4-2, and 80-4-1 forms a rectangle. In this case, the distance between antenna elements 80-1-1 and 80-2-1 adjacent to each other in the row direction and the distance between antenna elements 80-1-1 and 80-1-2 adjacent to each other in the column direction may be the same or different. Each of the antenna elements 80-1-1 to 80-3-2 receives an incoming wave and is thereby fed with an electric RF signal.

[0185] The beams formed by the reception directivity control device 1f in the array antenna 80b are beams 90-1 to 90-8 oriented in eight directions as shown in Fig. 13. When viewed through the plane of the array antenna 80b in the observation direction indicated by the arrow in Fig. 12, that is, from the side where the reception directivity control device 1f is installed, beam 90-1 is oriented in the upper right direction, beam 90-2 is oriented in the upper left direction, beam 90-7 is oriented in the lower right direction, and beam 90-8 is oriented in the lower left direction.

[0186] Beam 90-3 points in a direction obtained by tilting a line perpendicular to the surface of array antenna 80b to the right and then tilting upward at an angle smaller than the elevation angles of beams 90-1 and 90-2 (hereinafter, this direction will be referred to as the "upper right-center direction"). Beam 90-4 points in a direction obtained by tilting a line perpendicular to the surface of array antenna 80b to the left and then tilting upward at an angle smaller than the elevation angles of beams 90-1 and 90-2 (hereinafter, this direction will be referred to as the "upper left-center direction").

[0187] Beam 90-5 points in a direction obtained by tilting a line perpendicular to the surface of array antenna 80b to the right and then tilting downward at an angle smaller than the depression angles of beams 90-7 and 90-8 (hereinafter, this direction will be referred to as the "lower-center-right direction"). Beam 90-6 points in a direction obtained by tilting a line perpendicular to the surface of array antenna 80b to the left and then tilting downward at an angle smaller than the depression angles of beams 90-7 and 90-8 (hereinafter, this direction will be referred to as the "lower-center-left direction").

[0188] Hereinafter, the vertical component of the direction of beams 90-1 and 90-2 will be referred to as the "upper direction," the vertical component of the direction of beams 90-3 and 90-4 will be referred to as the "upper-middle direction," the vertical component of the direction of beams 90-5 and 90-6 will be referred to as the "lower-middle direction," and the vertical component of the direction of beams 90-7 and 90-8 will be referred to as the "lower direction." The horizontal component of the direction of beams 90-1, 90-3, 90-5, and 90-7 will be referred to as the "rightward direction," and the horizontal component of the direction of beams 90-2, 90-4, 90-6, and 90-8 will be referred to as the "leftward direction."

[0189] When the phase gradients caused by each of the beams 90-1 to 90-8 are written in the form of (row-direction phase gradient, column-direction phase gradient), for example, the beam 90-1 has a phase gradient of (φ V2 ,φ H ), and the beam 90-2 is (φ V2 ,-φ H ), and the beam 90-3 is (φ V1 ,φ H ), and the beam 90-4 is (φ V1 ,-φH ), and beam 90-5 is (-φ V1 ,φ H ), and beam 90-6 is (-φ V1 ,-φ H ), and beam 90-7 is (-φ V2 ,φ H ), and beam 90-8 is (-φ V2 ,-φ H ) where φ V2 >φ V1 is.

[0190] The reception directivity control device 1f includes a light source 5, an electro-optical conversion unit 10a, a row direction scanning unit 20c, and a column direction scanning unit 50b. The light source 5 supplies an optical signal of frequency ch1 that it generates to each of the optical modulators 11-1-1 to 11-4-2 that the electro-optical conversion unit 10a includes.

[0191] The electrical-to-optical conversion unit 10a includes optical modulators 11-1-1 to 11-4-2, the number of which corresponds to the number of antenna elements 80-1-1 to 80-4-2. Each of the optical modulators 11-4-1 and 11-4-2 newly added to the reception directivity control device 1f has the same configuration as the optical modulator 11-1-1 shown in the first and second embodiments. Each of the optical modulators 11-1-1 to 11-4-2 is connected to a corresponding antenna element 80-1-1 to 80-4-2.

[0192] The row direction scanning unit 20c has circuit configurations whose number matches the number of columns of the array antenna 80b. The circuit configuration corresponding to the first column is a row direction scanning matrix circuit 21a-1, frequency converters 22-1, 23-1, 24-1, and switching switch unit 25a-1, which are connected to the optical modulators 11-1-1, 11-2-1, 11-3-1, and 11-4-1 of the first column. The circuit configuration corresponding to the second column is a row direction scanning matrix circuit 21a-2, frequency converters 22-2, 23-2, and 24-2, and switching switch unit 25a-2, which are connected to the optical modulators 11-1-2, 11-2-2, 11-3-2, and 11-4-2 of the second column.

[0193] The two circuit configurations included in the row-direction scanning unit 20c are identical, and the following describes, as an example, the circuit configuration corresponding to the first column: the row-direction scanning matrix circuit 21a-1, frequency converters 22-1, 23-1, 24-1, and switching switch unit 25a-1. In the following description of the circuit configuration corresponding to the first column, the branch number "-1" of the reference numeral is replaced with "-2" to describe the circuit configuration corresponding to the second column. However, in the description of the optical modulators 11-1-1, 11-2-1, 11-3-1, and 11-4-1 and the switching circuits 16-1-1, 16-2-1, and 16-3-1 included in the switching switch unit 25a-1, the last branch number "-1" of the two branch numbers included in the reference numerals is replaced with "-2."

[0194] The row-direction scanning matrix circuit 21a-1 is a one-dimensional weighting circuit and includes four input ports 31-1, 32-1, 33-1, and 34-1 and four output ports 35-1, 36-1, 37-1, and 38-1. The row-direction scanning matrix circuit 21a-1 is connected to four optical modulators 11-1-1, 11-2-1, 11-3-1, and 11-4-1 in the first column. More specifically, the optical modulator 11-1-1 is connected to the input port 31-1, the optical modulator 11-2-1 is connected to the input port 32-1, the optical modulator 11-3-1 is connected to the input port 33-1, and the optical modulator 11-4-1 is connected to the input port 34-1.

[0195] The row-direction scanning matrix circuit 21a-1 performs a predetermined row-direction phase scanning process on the USB components of the modulated optical signals supplied from each of the input ports 31-1, 32-1, 33-1, and 34-1, thereby generating four optical signals for each of the output ports 35-1, 36-1, 37-1, and 38-1. The row-direction scanning matrix circuit 21a-1 combines the four optical signals generated for each of the output ports 35-1, 36-1, 37-1, and 38-1 to generate an optical signal for each of the output ports 35-1, 36-1, 37-1, and 38-1 (hereinafter, this optical signal will be referred to as a row-direction combined optical signal). The row-direction scanning matrix circuit 21a-1 outputs each of the row-direction combined optical signals generated for each of the output ports 35-1, 36-1, 37-1, and 38-1 from the corresponding output ports 35-1, 36-1, 37-1, and 38-1.

[0196] The predetermined row-direction phase scanning process performed by the row-direction scanning matrix circuit 21a-1 is as follows: Here, it is assumed that the input / output relationship in the row-direction scanning matrix circuit 21a-1 is reversed and optical signals are supplied to each of the output ports 35-1, 36-1, 37-1, and 38-1.

[0197] Assume that an optical signal is supplied to the output port 35-1 of the row-direction scanning matrix circuit 21a-1. In this case, the row-direction scanning matrix circuit 21a-1 outputs the optical signal supplied from the output port 35-1 as is from the input port 31-1, and changes the phase of the supplied optical signal to φ V2 The delayed optical signal is output from the input port 32-1, and the phase of the supplied optical signal is changed by 2φ V2 The delayed optical signal is output from input port 33-1, and the phase of the supplied optical signal is changed to 3φ. V2 The delayed optical signal is output from input port 34-1. Therefore, the phase difference between the optical signals output from input ports 31-1, 32-1, 33-1, and 34-1 is (0, -φ V2 ,-2φ V2 ,-3φ V2 ) becomes.

[0198] Assume that an optical signal is supplied to the output port 36-1 of the row-direction scanning matrix circuit 21a-1. In this case, the row-direction scanning matrix circuit 21a-1 outputs the optical signal supplied from the output port 36-1 as is from the input port 31-1, and changes the phase of the supplied optical signal to φ V1 The delayed optical signal is output from the input port 32-1, and the phase of the supplied optical signal is changed by 2φ V1 The delayed optical signal is output from input port 33-1, and the phase of the supplied optical signal is changed to 3φ. V1 The delayed optical signal is output from input port 34-1. Therefore, the phase difference between the optical signals output from input ports 31-1, 32-1, 33-1, and 34-1 is (0, -φ V1 ,-2φ V1 ,-3φ V1 ) becomes.

[0199] Assume that an optical signal is supplied to the output port 37-1 of the row-direction scanning matrix circuit 21a-1. In this case, the row-direction scanning matrix circuit 21a-1 outputs the optical signal supplied from the output port 37-1 as is from the input port 34-1, and changes the phase of the supplied optical signal to φ V1 The delayed optical signal is output from the input port 33-1, and the phase of the supplied optical signal is changed by 2φ V1 The delayed optical signal is output from input port 32-1, and the phase of the supplied optical signal is changed to 3φ. V1 The delayed optical signal is output from input port 31-1. Therefore, the phase difference between the optical signals output from input ports 31-1, 32-1, 33-1, and 34-1 is (-3φ V1 ,-2φ V1 ,-φ V1 ,0).

[0200] Assume that an optical signal is supplied to the output port 38-1 of the row-direction scanning matrix circuit 21a-1. In this case, the row-direction scanning matrix circuit 21a-1 outputs the optical signal supplied from the output port 38-1 as is from the input port 34-1, and changes the phase of the supplied optical signal to φ V2 The delayed optical signal is output from the input port 33-1, and the phase of the supplied optical signal is changed by 2φ V2 The delayed optical signal is output from input port 32-1, and the phase of the supplied optical signal is changed to 3φ. V2 The delayed optical signal is output from input port 31-1. Therefore, the phase difference between the optical signals output from input ports 31-1, 32-1, 33-1, and 34-1 is (-3φ V2 ,-2φ V2 ,-φ V2 ,0).

[0201] Conversely, when optical signals are supplied from each of the input ports 31-1, 32-1, 33-1, and 34-1, the row-direction scanning matrix circuit 21 a-1 applies a phase gradient of the opposite sign to the phase gradient applied in the above-described process to each of the supplied optical signals. This process is the predetermined row-direction phase scanning process performed by the row-direction scanning matrix circuit 21 a-1.

[0202] For each of the input ports 31-1, 32-1, 33-1, and 34-1, the phase difference is (0, -φ V2 ,-2φ V2 ,-3φ V2 ) are supplied. In this case, of the row direction combined optical signals generated for each of the output ports 35-1, 36-1, 37-1, and 38-1, the four optical signals included in the row direction combined optical signal corresponding to the output port 35-1 will be in phase, and the four optical signals included in the row direction combined optical signals corresponding to the output ports 36-1, 37-1, and 38-1 will not be in phase.

[0203] For each of the input ports 31-1, 32-1, 33-1, and 34-1, the phase difference is (0, -φ V1 ,-2φ V1 ,-3φ V1 ) are supplied. In this case, of the row direction combined optical signals generated for each of the output ports 35-1, 36-1, 37-1, and 38-1, the four optical signals included in the row direction combined optical signal corresponding to output port 36-1 will be in phase, and the four optical signals included in the row direction combined optical signals corresponding to output ports 35-1, 37-1, and 38-1 will not be in phase.

[0204] For each of the input ports 31-1, 32-1, 33-1, and 34-1, the phase difference is (-3φ V1 ,-2φ V1 ,-φ V1 , 0) are supplied. In this case, of the row direction combined optical signals generated for each of the output ports 35-1, 36-1, 37-1, and 38-1, the four optical signals included in the row direction combined optical signal corresponding to the output port 37-1 will be in phase, and the four optical signals included in the row direction combined optical signals corresponding to the output ports 35-1, 36-1, and 38-1 will not be in phase.

[0205] For each of the input ports 31-1, 32-1, 33-1, and 34-1, the phase difference is (-3φ V2 ,-2φ V2 ,-φ V2, 0) are supplied. In this case, of the row direction combined optical signals generated for each of the output ports 35-1, 36-1, 37-1, and 38-1, the four optical signals included in the row direction combined optical signal corresponding to output port 38-1 will be in phase, and the four optical signals included in the row direction combined optical signals corresponding to output ports 35-1, 36-1, and 37-1 will not be in phase.

[0206] When the 4-input, 4-output row-direction scanning matrix circuit 21a-1 that performs the predetermined row-direction phase scanning process as described above is realized by, for example, a Butler matrix circuit, it can be realized by using a 2-input, 2-output directional coupler as shown in Figure 1 of Reference 1 below.

[0207] [Reference 1: Soyeon Kim et al., “A Miniaturized Butler Matrix Based Switched Beamforming Antenna System in a Two-Layer Hybrid Stackup Substrate for 5G Applications”, Electronics 2019, Vol.8, no. 11, 1232.]

[0208] For example, a hybrid coupler is used as a two-input, two-output directional coupler. The hybrid coupler outputs an optical signal supplied from a first input port unchanged from a first output port while advancing the phase of the optical signal by 90 degrees and outputting it from a second output port, and outputs an optical signal supplied from a second input port unchanged from a second output port while advancing the phase of the optical signal by 90 degrees and outputting it from a first output port. In this case, as shown in Figure 1 of Reference 1, by combining two phase shifters with a 45-degree phase advance and four hybrid couplers, a four-input, four-output matrix circuit can be constructed that generates four phase tilts: 135 degrees, 45 degrees, -45 degrees, and -135 degrees. This matrix circuit can also be used with the inputs and outputs swapped, which results in a phase change opposite to that described above.

[0209] That is, when the row-direction scanning matrix circuit 21a-1 is realized by a Butler matrix circuit, four directional couplers (hereinafter referred to as "directional couplers") are required. Therefore, as shown in Fig. 11, the row-direction scanning matrix circuit 21a-1 is internally provided with four directional couplers 61-1, 62-1, 63-1, and 64-1. The directional couplers 61-1, 62-1, 63-1, and 64-1 all have the same configuration.

[0210] The frequency converter 22-1 is connected to an output port 36-1 of the row-direction scanning matrix circuit 21a-1. The frequency converter 23-1 is connected to an output port 37-1 of the row-direction scanning matrix circuit 21a-1. The frequency converter 24-1 is connected to an output port 38-1 of the row-direction scanning matrix circuit 21a-1. The frequency converter 24-1 converts the optical signal of frequency ch1 supplied from output port 38-1 into an optical signal of frequency ch4, which is a frequency different from frequencies ch1, ch2, and ch3.

[0211] The switching SW unit 25a-1 includes three SW circuits 16-1-1, 16-2-1, and 16-3-1. Each of the SW circuits 16-1-1, 16-2-1, and 16-3-1 is a two-input, one-output switch having two input ports and one output port. The output ports of the SW circuits 16-1-1 and 16-2-1 are connected to the two input ports of the SW circuit 16-3-1. Each of the SW circuits 16-1-1 and 16-2-1 performs switching to connect one or both of its two input ports to its respective output port, or to connect neither to its respective output port. The SW circuit 16-3-1 performs switching to connect one or both of its two input ports to its respective output port.

[0212] The two input ports of SW circuit 16-1-1 are input ports 41-1 and 42-1 of switching SW unit 25a-1, and the two input ports of SW circuit 16-2-1 are input ports 43-1 and 44-1 of switching SW unit 25a-1. The output port of SW circuit 16-3-1 is output port 45-1 of switching SW unit 25a-1. In this case, switching SW unit 25a-1 becomes a four-input, one-output switch having four input ports 41-1, 42-1, 43-1, and 44-1 as a whole and one output port 45-1. In response to a user's operation to specify a desired direction, any of the four input ports 41-1, 42-1, 43-1, and 44-1 is connected to output port 45-1.

[0213] The input port 41-1 is connected to the output port 35-1 of the row-direction scanning matrix circuit 21a-1. The input port 42-1 is connected to the frequency converter 22-1. The input port 43-1 is connected to the frequency converter 23-1. The input port 44-1 is connected to the frequency converter 24-1.

[0214] The four input ports 44-1, 42-1, 43-1, and 44-1 of the switching switch unit 25a-1 are assigned in advance to the four row direction components of the directions of the beams 90-1 to 90-8. Here, as described above, the row direction is the vertical direction, so the row direction components are also vertical direction components.

[0215] Input port 41-1 is pre-assigned to the "upward direction," which is the row component of the direction of beams 90-1 and 90-2. Input port 42-1 is pre-assigned to the "upper-middle direction," which is the row component of the direction of beams 90-3 and 90-4. Input port 43-1 is pre-assigned to the "lower-middle direction," which is the row component of the direction of beams 90-5 and 90-6. Input port 44-1 is pre-assigned to the "downward direction," which is the row component of the direction of beams 90-7 and 90-8.

[0216] The column scanning unit 50b includes a column scanning matrix circuit 51a and demultiplexers 52a-1 and 52a-2. The column scanning matrix circuit 51a is a one-dimensional weighting circuit and includes two input ports 51-1 and 51-2 and two output ports 51-5 and 51-6. The input port 51-1 is connected to the output port 45-1 of the switching switch unit 25a-1. The input port 51-2 is connected to the output port 45-2 of the switching switch unit 25a-2.

[0217] The column-direction scanning matrix circuit 51a performs a predetermined column-direction phase scanning process on the optical signals supplied from each of the input ports 51-1 and 51-2 to generate two optical signals for each of the output ports 51-5 and 51-6. The column-direction scanning matrix circuit 51a combines the two optical signals generated for each of the output ports 51-5 and 51-6 to generate an optical signal for each of the output ports 51-5 and 51-6 (hereinafter, this optical signal will be referred to as a column-direction combined optical signal). The column-direction scanning matrix circuit 51a outputs each of the column-direction combined optical signals generated for each of the output ports 51-5 and 51-6 from the corresponding output ports 51-5 and 51-6.

[0218] The column-direction scanning matrix circuit 51a performs the following process as a predetermined column-direction phase scanning process: The column-direction scanning matrix circuit 51a outputs the optical signal supplied from the input port 51-1 as is from the output port 51-5, and changes the phase of the optical signal by φ H The column-direction scanning matrix circuit 51a outputs the optical signal supplied from the input port 51-2 as is from the output port 51-6, and also shifts the phase of the optical signal by φ H The forwarded optical signal is output from the output port 51-5.

[0219] As a result, the phase difference between the optical signals supplied to the input ports 51-1 and 51-2 becomes (0, -φ H ), the two optical signals corresponding to the output port 51-5 will be in phase, and the two optical signals corresponding to the output port 51-6 will not be in phase. On the other hand, when the phase difference between the optical signals supplied to each of the input ports 51-1 and 51-2 is (-φ H, 0), the two optical signals corresponding to the output port 51-6 will be in phase, and the two optical signals corresponding to the output port 51-5 will not be in phase.

[0220] When the column-direction scanning matrix circuit 51a is realized by, for example, a Butler matrix circuit, it can be realized by one two-input, two-output hybrid coupler. Therefore, as shown in Fig. 11, the column-direction scanning matrix circuit 51a includes one square coupler 65.

[0221] The input side of the demultiplexer 52a-1 is connected to the output port 51-5 of the column-direction scanning matrix circuit 51a, and the input side of the demultiplexer 52a-2 is connected to the output port 51-6 of the column-direction scanning matrix circuit 51a.

[0222] The duplexers 52a-1 and 52a-2 have the same configuration, and the following description will be given of duplexer 52a-1 as an example. In the following description of duplexer 52a-1, the branch number "-1" in the reference numeral is replaced with "-2", and the description of duplexer 52a-2 will be given. However, in the description of couplers 17-1-1, 17-2-1, and 17-3-1, the last branch number "-1" of the two branch numbers included in the reference numeral is replaced with "-2".

[0223] The duplexer 52a-1 includes three couplers 17-1-1, 17-2-1, and 17-3-1. The couplers 17-1-1, 17-2-1, and 17-3-1 are one-input, two-output duplexers with one input port and two output ports. One of the two output ports of the coupler 17-1-1 is connected to the input port of the coupler 17-2-1, and the other is connected to the input port of the coupler 17-3-1.

[0224] The coupler 17-1-1 demultiplexes the optical signal supplied from the input port into an optical signal of frequency ch1, 2 and an optical signal of frequency ch3, 4. The coupler 17-1-1 outputs the demultiplexed optical signal of frequency ch1, 2 to the coupler 17-2-1, and outputs the demultiplexed optical signal of frequency ch3, 4 to the coupler 17-3-1.

[0225] The coupler 17-2-1 demultiplexes the optical signals of frequencies ch1 and ch2 supplied from its input port into an optical signal of frequency ch1 and an optical signal of frequency ch2. The coupler 17-2-1 outputs the demultiplexed optical signal of frequency ch1 from one output port and outputs the demultiplexed optical signal of frequency ch2 from the other output port.

[0226] The coupler 17-3-1 demultiplexes the optical signals of frequencies ch3 and ch4 supplied from the input port into an optical signal of frequency ch3 and an optical signal of frequency ch4. The coupler 17-3-1 outputs the demultiplexed optical signal of frequency ch3 from one output port and outputs the demultiplexed optical signal of frequency ch4 from the other output port.

[0227] The input port of coupler 17-1-1 is the input port of demultiplexer 52a-1, the output port from which the optical signal of frequency ch1 of coupler 17-2-1 is output is output port 55-1 of demultiplexer 52a-1, the output port from which the optical signal of frequency ch2 of coupler 17-2-1 is output port 56-1 of demultiplexer 52a-1, the output port from which the optical signal of frequency ch3 of coupler 17-3-1 is output port 57-1 of demultiplexer 52a-1, and the output port from which the optical signal of frequency ch4 of coupler 17-3-1 is output port 58-1 of demultiplexer 52a-1.

[0228] In this case, the demultiplexer 52a-1 has one input port and four output ports 55-1, 56-1, 57-1, and 58-1 as a whole, and is a one-input, four-output demultiplexer that demultiplexes the optical signal supplied from the input port into optical signals of frequencies ch1, ch2, ch3, and ch4.

[0229] (Processing of the Receiving Directivity Control Device According to Configuration Example (Part 1) of the Third Embodiment) For example, suppose that the switching switches 25a-1 and 25a-2 are operated by a user to specify a desired direction and connect all of the input ports 41-1 to 44-1 and 41-2 to 44-2 and the output ports 45-1 and 45-2, respectively. In this state, if there are incoming waves of the beams 90-1 to 90-8 from all directions, the row-direction scanning matrix circuits 21a-1 and 21a-2 will produce the following row-direction combined optical signals:

[0230] When receiving waves arriving from the direction of beams 90-1 and 90-2 corresponding to the "upward direction," the phase differences of the USB components of the four modulated optical signals supplied to each of the row-direction scanning matrix circuits 21a-1 and 21a-2 are (0, -φ V2 ,-2φ V2 ,-3φ V2 ) Therefore, the USB components of the modulated optical signal are in phase at the output ports 35-1 and 35-2.

[0231] When waves arriving from the direction of beams 90-3 and 90-4 corresponding to the "upper-middle direction" are received, the phase differences of the USB components of the four modulated optical signals supplied to each of the row-direction scanning matrix circuits 21a-1 and 21a-2 are (0, -φ) when shown in the order of the first, second, third, and fourth rows. V1 ,-2φ V1 ,-3φ V1 ) Therefore, the USB components of the modulated optical signal are in phase at the output ports 36-1 and 36-2.

[0232] When receiving waves arriving from the direction of beams 90-5 and 90-6 corresponding to the "bottom-center direction," the phase difference between the USB components of the four modulated optical signals supplied to each of the row-direction scanning matrix circuits 21a-1 and 21a-2 is (-3φ) when shown in the order of the first, second, third, and fourth rows. V1 ,-2φ V1 ,-φ V1 , 0). Therefore, the USB components of the modulated optical signal are in phase at the output ports 37-1 and 37-2.

[0233] When receiving waves arriving from the direction of beams 90-7 and 90-8 corresponding to the "downward direction," the phase difference between the USB components of the four modulated optical signals supplied to each of the row-direction scanning matrix circuits 21a-1 and 21a-2 is (-3φ) when shown in the order of the first, second, third, and fourth rows. V2 ,-2φ V2 ,-φ V2 , 0). Therefore, the USB components of the modulated optical signal are in phase at the output ports 38-1 and 38-2. When the USB components of the modulated optical signal are in phase, a row-direction combined optical signal with high signal intensity is obtained.

[0234] In the column-direction scanning matrix circuit 51a, the following column-direction combined optical signal is obtained. When waves arriving from the directions of beams 90-1, 90-3, 90-5, and 90-7 corresponding to "rightward" are received, the phase difference between the row-direction combined optical signals supplied to the input ports 51-1 and 51-2 is (0, -φ H ) is obtained. Therefore, the row-direction combined optical signals are in phase at the output port 51-5. When the incoming waves are received from the directions of the beams 90-2, 90-4, 90-6, and 90-8 corresponding to "leftward," the phase difference between the row-direction combined optical signals supplied to each of the input ports 51-1 and 51-2 is (-φ H , 0). Therefore, the row direction combined optical signals have the same phase at the output port 51-6. When the row direction combined optical signals have the same phase, a column direction combined optical signal with a large signal intensity is obtained.

[0235] As a result, at output ports 55-1, 56-1, 57-1, 58-1, 55-2, 56-2, 57-2, and 58-2 of demultiplexers 52a-1 and 52a-2, it is possible to separate and obtain in parallel received signals of waves arriving from the directions of beams 90-1 to 90-8, as shown in FIG.

[0236] For example, suppose a user wishes to select and receive incoming waves from the "upward" direction of beams 90-1 and 90-2. In this case, when the user operates switching units 25a-1 and 25a-2 to specify either or both of beams 90-1 and 90-2 as the desired direction, switching unit 25a-1 connects input port 41-1 to output port 45-1. Switching unit 25a-2 connects input port 41-2 to output port 45-2. As a result, only received signals corresponding to incoming waves from the directions of beams 90-1 and 90-2 are output from output port 55-1 of duplexer 52a-1 and output port 55-2 of duplexer 52a-2.

[0237] Similarly, the user can specify the desired direction and change the connection state of the switching SW units 25a-1 and 25a-2 to a state corresponding to the desired direction, thereby selecting and obtaining received signals corresponding to incoming waves from each of the "upper-middle direction," "lower-middle direction," and "lower direction."

[0238] (Configuration Example (Part 2) of the Third Embodiment) FIG. 14 is a block diagram showing the internal configuration of a reception directivity control device 1g according to a second configuration example of the third embodiment, and an array antenna 80c connected to the reception directivity control device 1g. Connecting the array antenna 80c to the reception directivity control device 1g forms a so-called phased array antenna. As shown in FIG. 15, the array antenna 80c is a 2×4 array antenna with eight antenna elements: two elements arranged along the row direction and four elements arranged along the column direction, totaling eight antenna elements: 80-1-1, 80-1-2, 80-1-3, 80-1-4, 80-2-1, 80-2-2, 80-2-3, and 80-2-4. Hereinafter, in the arrangement of the array antenna 80c, the vertical direction is also referred to as the row direction, and the horizontal direction is also referred to as the column direction. The antenna elements 80-1-1 to 80-2-4 are arranged on a plane, i.e., on the surface of the array antenna 80c.

[0239] The arrangement will be described in more detail. Antenna elements 80-1-1, 80-1-2, 80-1-3, and 80-1-4 in the first row are arranged at equal intervals and parallel to the axis in the column direction. Similarly, antenna elements 80-2-1, 80-2-2, 80-2-3, and 80-2-4 in the second row are arranged at equal intervals and parallel to the axis in the column direction. Antenna elements 80-1-1, 80-1-2, 80-1-3, and 80-1-4 are arranged so that the distance between adjacent antenna elements is the same as the distance between adjacent antenna elements in antenna elements 80-2-1, 80-2-2, 80-2-3, and 80-2-4.

[0240] The line segment connecting antenna element 80-1-1 and antenna element 80-2-1 in the same column, the line segment connecting antenna element 80-1-2 and antenna element 80-2-2, the line segment connecting antenna element 80-1-3 and antenna element 80-2-3, and the line segment connecting antenna element 80-1-4 and antenna element 80-2-4 are all parallel to the row axis and are all the same length. Therefore, the shape with vertices at the positions of antenna elements 80-1-1, 80-2-1, 80-2-4, and 80-1-4 forms a rectangle. In this case, the distance between antenna element 80-1-1 and antenna element 80-2-1 adjacent to each other in the row direction and the distance between antenna element 80-1-1 and antenna element 80-1-2 adjacent to each other in the column direction may be the same or different. Each of the antenna elements 80-1-1 to 80-2-4 receives an incoming wave and is thereby fed with an electric RF signal.

[0241] The beams formed by the reception directivity control device 1g in the array antenna 80c are beams 90-1 to 90-8 facing in eight directions as shown in Fig. 16. When viewed through the plane of the array antenna 80c in the observation direction indicated by the arrow in Fig. 15, that is, from the side where the reception directivity control device 1g is installed, beam 90-1 faces in the upper right direction, beam 90-4 faces in the upper left direction, beam 90-5 faces in the lower right direction, and beam 90-8 faces in the lower left direction.

[0242] Beam 90-2 points in a direction obtained by tilting a line perpendicular to the surface of array antenna 80c upward and then tilting to the right at an angle smaller than the rightward azimuth angles of beams 90-1 and 90-5 (hereinafter, this direction will be referred to as the "upper-right center direction"). Beam 90-6 points in a direction obtained by tilting a line perpendicular to the surface of array antenna 80c downward and then tilting to the right at an angle smaller than the rightward azimuth angles of beams 90-1 and 90-5 (hereinafter, this direction will be referred to as the "lower-right center direction"). Here, the rightward azimuth angles of beams 90-1 and 90-5 are the angles formed between a vertical plane and the directions of beams 90-1 and 90-5.

[0243] Beam 90-3 points in a direction obtained by tilting a line perpendicular to the surface of array antenna 80c upward and then tilting leftward at an angle smaller than the leftward azimuth angles of beams 90-4 and 90-8 (hereinafter, this direction will be referred to as the "upper-left center direction"). Beam 90-7 points in a direction obtained by tilting a line perpendicular to the surface of array antenna 80c downward and then tilting leftward at an angle smaller than the leftward azimuth angles of beams 90-4 and 90-8 (hereinafter, this direction will be referred to as the "lower-left center direction"). Here, the leftward azimuth angles of beams 90-4 and 90-8 are the angles formed between a vertical plane and the directions of beams 90-4 and 90-8.

[0244] Hereinafter, the vertical component of the direction of beams 90-1, 90-2, 90-3, and 90-4 will be referred to as the "upward direction," and the vertical component of the direction of beams 90-5, 90-6, 90-7, and 90-8 will be referred to as the "downward direction." The horizontal component of the direction of beams 90-1 and 90-5 will be referred to as the "rightward direction," the horizontal component of the direction of beams 90-2 and 90-6 will be referred to as the "center-right direction," the horizontal component of the direction of beams 90-3 and 90-7 will be referred to as the "center-left direction," and the horizontal component of the direction of beams 90-4 and 90-8 will be referred to as the "leftward direction."

[0245] When the phase gradients caused by each of the beams 90-1 to 90-8 are written in the form of (row-direction phase gradient, column-direction phase gradient), for example, the beam 90-1 has a phase gradient of (φ V ,φ H2 ), and the beam 90-2 is (φV ,φ H1 ), and the beam 90-3 is (φ V ,-φ H1 ), and the beam 90-4 is (φ V ,-φ H2 ), and beam 90-5 is (-φ V ,φ H2 ), and beam 90-6 is (-φ V ,φ H1 ), and beam 90-7 is (-φ V ,-φ H1 ), and beam 90-8 is (-φ V ,-φ H2 ) where φ H2 >φ H1 is.

[0246] The reception directivity control device 1g includes a light source 5, an electro-optical conversion unit 10b, a row direction scanning unit 20d, and a column direction scanning unit 50c. The light source 5 supplies an optical signal of frequency ch1 that it generates to each of the optical modulators 11-1-1 to 11-2-4 that the electro-optical conversion unit 10b includes.

[0247] The electrical-to-optical conversion unit 10b includes optical modulators 11-1-1 to 11-2-4, the number of which corresponds to the number of antenna elements 80-1-1 to 80-2-4. Each of the optical modulators 11-1-4 and 11-2-4 newly added to the reception directivity control device 1g has the same configuration as the optical modulator 11-1-1 shown in the first and second embodiments. Each of the optical modulators 11-1-1 to 11-2-4 is connected to a corresponding antenna element 80-1-1 to 80-2-4.

[0248] The row direction scanning unit 20d has circuit configurations whose number matches the number of columns of the array antenna 80c. The circuit configuration corresponding to the first column is a row direction scanning matrix circuit 21b-1, a frequency converter 22-1, and a switching switch unit 25b-1 connected to the optical modulators 11-1-1 and 11-2-1 in the first column. The circuit configuration corresponding to the second column is a row direction scanning matrix circuit 21b-2, a frequency converter 22-2, and a switching switch unit 25b-2 connected to the optical modulators 11-1-2 and 11-2-2 in the second column. The circuit configuration corresponding to the third column is a row direction scanning matrix circuit 21b-3, a frequency converter 22-3, and a switching switch unit 25b-3 connected to the optical modulators 11-1-3 and 11-2-3 in the third column. The circuit configuration corresponding to the fourth column is a row-direction scanning matrix circuit 21b-4, a frequency converter 22-4, and a switching switch unit 25b-4 connected to the optical modulators 11-1-4 and 11-2-4 in the fourth column.

[0249] The four circuit configurations included in the row-direction scanning unit 20d are identical, and below, as an example, the row-direction scanning matrix circuit 21b-1, frequency converter 22-1, and switching switch unit 25b-1, which are circuit configurations corresponding to the first column, will be described. In the following description of the circuit configurations corresponding to the first column, the branch number "-1" of the symbol is replaced with "-2" to describe the circuit configuration corresponding to the second column, the branch number "-3" is replaced with "-4" to describe the circuit configuration corresponding to the third column, and the branch number "-4" is replaced with "-4" to describe the circuit configuration corresponding to the fourth column. However, in the description of the optical modulators 11-1-1 and 11-2-1, the last branch number "-1" of the two branch numbers included in the symbol is replaced with "-2," "-3," or "-4."

[0250] The row-direction scanning matrix circuit 21b-1 is a one-dimensional weighting circuit and includes two input ports 31-1 and 32-1 and two output ports 35-1 and 36-1. The row-direction scanning matrix circuit 21b-1 is connected to two optical modulators 11-1-1 and 11-2-1 in the first column. More specifically, the optical modulator 11-1-1 is connected to the input port 31-1, and the optical modulator 11-2-1 is connected to the input port 32-1.

[0251] The row-direction scanning matrix circuit 21b-1 performs a predetermined row-direction phase scanning process on the optical signals supplied from each of the input ports 31-1 and 32-1 to generate two optical signals for each of the output ports 35-1 and 36-1. The row-direction scanning matrix circuit 21b-1 combines the two optical signals generated for each of the output ports 35-1 and 36-1 to generate an optical signal for each of the output ports 35-1 and 36-1 (hereinafter, this optical signal will be referred to as a row-direction combined optical signal). The row-direction scanning matrix circuit 21b-1 outputs each of the row-direction combined optical signals generated for each of the output ports 35-1 and 36-1 from the corresponding output ports 35-1 and 36-1.

[0252] The predetermined row-direction phase scanning process performed by the row-direction scanning matrix circuit 21b-1 is a predetermined column-direction phase scanning process performed by the column-direction scanning matrix circuit 51a included in the reception directivity control device 1f of the configuration example (part 1) of the third embodiment under the input / output conditions shown below, and is a process of "φ H " to "φ V " is the same processing as that in which " is replaced with ". The input / output conditions here are conditions where, on the input side, input port 31-1 corresponds to input port 51-1, and input port 32-1 corresponds to input port 51-2. On the output side, output port 35-1 corresponds to output port 51-5, and output port 36-1 corresponds to output port 51-6.

[0253] When the row-direction scanning matrix circuit 21b-1 is realized, for example, by a Butler matrix circuit, the row-direction scanning matrix circuit 21b-1 will have one matrix coupler 61-1, similar to the column-direction scanning matrix circuit 51a provided in the reception directivity control device 1f of the configuration example (part 1) of the third embodiment.

[0254] The frequency converter 22-1 is connected to the output port 36-1 of the row-direction scanning matrix circuit 21b-1.

[0255] The switching SW unit 25b-1 includes a SW circuit 16-1. The SW circuit 16-1 has the same configuration as the SW circuit 16-3-1 included in the reception directivity control device 1f of the configuration example (part 1) of the third embodiment. One input port of the SW circuit 16-1 serves as an input port 41-1 of the switching SW unit 25b-1, the other input port of the SW circuit 16-1 serves as an input port 42-1 of the switching SW unit 25b-1, and the output port of the SW circuit 16-1 serves as an output port 45-1 of the switching SW unit 25b-1. In response to a user's operation to specify a desired direction, the switching SW unit 25b-1 connects any one of the two input ports 41-1 and 42-1 to the output port 45-1. The input port 41-1 is connected to the output port 35-1 of the row direction scanning matrix circuit 21b-1. The input port 42-1 is connected to the frequency converter 22-1.

[0256] The two input ports 41-1 and 42-1 of the switching switch unit 25b-1 are pre-assigned to two row direction components of the directions of the beams 90-1 to 90-8. Here, as described above, the row direction is the vertical direction, so the row direction components are vertical direction components. The input port 41-1 is pre-assigned to the "upward direction," which is the row direction component of the directions of the beams 90-1, 90-2, 90-3, and 90-4. The input port 42-1 is pre-assigned to the "downward direction," which is the row direction component of the directions of the beams 90-5, 90-6, 90-7, and 90-8.

[0257] The column scanning unit 50c includes a column scanning matrix circuit 51b and demultiplexers 52b-1, 52b-2, 52b-3, and 52b-4. The column scanning matrix circuit 51b is a one-dimensional weighting circuit and includes four input ports 51-1, 51-2, 51-3, and 51-4 and four output ports 51-5, 51-6, 57-1, and 58-1. The input port 51-1 is connected to the output port 45-1 of the switching switch unit 25b-1. The input port 51-2 is connected to the output port 45-2 of the switching switch unit 25b-2. The input port 51-3 is connected to the output port 45-3 of the switching switch unit 25b-3. The input port 51-4 is connected to the output port 45-4 of the switching switch unit 25b-4.

[0258] The column-direction scanning matrix circuit 51b performs a predetermined column-direction phase scanning process on the optical signals supplied from each of the input ports 51-1, 51-2, 51-3, and 51-4 to generate four optical signals for each of the output ports 51-5, 51-6, 51-7, and 51-8. The column-direction scanning matrix circuit 51b combines the four optical signals generated for each of the output ports 51-5, 51-6, 51-7, and 51-8 to generate an optical signal for each of the output ports 51-5, 51-6, 51-7, and 51-8 (hereinafter, this optical signal will be referred to as a column-direction combined optical signal). The column-direction scanning matrix circuit 51b outputs each of the column-direction combined optical signals generated for each of the output ports 51-5, 51-6, 51-7, and 51-8 from the corresponding output ports 51-5, 51-6, 51-7, and 51-8.

[0259] The predetermined column-direction phase scanning process performed by the column-direction scanning matrix circuit 51b is a predetermined row-direction phase scanning process performed by the row-direction scanning matrix circuit 21a-1 included in the reception directivity control device 1f of the configuration example (part 1) of the third embodiment under the input / output conditions shown below, and is a process of "φ V2 " to "φ H2 " and "φ V1 " to "φ H1 " is the same processing as that in which " is replaced with ". The input / output conditions here are conditions that, on the input side, input port 51-1 corresponds to input port 31-1, input port 51-2 corresponds to input port 32-1, input port 51-3 corresponds to input port 33-1, and input port 51-4 corresponds to input port 34-1. On the output side, output port 51-5 corresponds to output port 35-1, output port 51-6 corresponds to output port 36-1, output port 51-7 corresponds to output port 37-1, and output port 51-8 corresponds to output port 38-1.

[0260] When the column-direction scanning matrix circuit 51b is realized by, for example, a Butler matrix circuit, the column-direction scanning matrix circuit 51b includes four square filters 62, 63, 64, and 65, similar to the row-direction scanning matrix circuit 21a-1 included in the reception directivity control device 1f of the configuration example (part 1) of the third embodiment. Note that the square filters 62, 63, 64, and 65 all have the same configuration.

[0261] The input side of the demultiplexer 52b-1 is connected to the output port 51-5 of the column-directional scanning matrix circuit 51b. The input side of the demultiplexer 52a-2 is connected to the output port 51-6 of the column-directional scanning matrix circuit 51b. The input side of the demultiplexer 52b-3 is connected to the output port 51-7 of the column-directional scanning matrix circuit 51b. The input side of the demultiplexer 52a-4 is connected to the output port 51-8 of the column-directional scanning matrix circuit 51b.

[0262] Each of the duplexers 52b-1, 52b-2, 52b-3, and 52b-4 has the same configuration, and the following description will focus on duplexer 52b-1 as an example. In the following description of duplexer 52b-1, the branch number "-1" in the symbol is replaced with "-2" to describe duplexer 52a-2, "-3" to describe duplexer 52a-3, and "-4" to describe duplexer 52a-4.

[0263] The demultiplexer 52b-1 includes a coupler 17-1. The coupler 17-1 has the same configuration as the coupler 17-2-1 included in the reception directivity control device 1f of the configuration example (part 1) of the third embodiment, which demultiplexes a supplied optical signal into optical signals of frequency ch1 and frequency ch2. The input port of the coupler 17-1 becomes the input port of the demultiplexer 52b-1, the port of the coupler 17-1 that outputs the optical signal of frequency ch1 becomes the output port 55-1 of the demultiplexer 52b-1, and the port of the coupler 17-1 that outputs the optical signal of frequency ch2 becomes the output port 56-1 of the demultiplexer 52b-1.

[0264] (Processing of the Receiving Directivity Control Device According to Configuration Example (Part 2) of the Third Embodiment) For example, suppose that the switching switches 25b-1, 25b-2, 25b-3, and 25b-4 are operated by a user to specify a desired direction, and all of the input ports 41-1, 42-1, 41-2, 42-2, 41-3, 42-3, 41-4, and 42-4 are connected to the output ports 45-1, 45-2, 45-3, and 45-4, respectively. In this state, if there are incoming waves from all directions of the beams 90-1 to 90-8, the row-direction combined optical signals shown below are obtained in the row-direction scanning matrix circuits 21b-1, 21b-2, 21b-3, and 21b-4.

[0265] When receiving waves arriving from the direction of beams 90-1, 90-2, 90-3, and 90-4 corresponding to the "upward direction," the phase difference between the USB components of the two modulated optical signals supplied to each of the row-direction scanning matrix circuits 21b-1 to 21b-4 is (0, -φ H ) Therefore, the USB components of the modulated optical signal are in phase at the output ports 35-1, 35-2, 35-3, and 35-4.

[0266] When waves arriving from the direction of beams 90-5, 90-6, 90-7, and 90-8 corresponding to the "downward direction" are received, the phase difference between the USB components of the two modulated optical signals supplied to each of the row-direction scanning matrix circuits 21b-1 to 21b-4 is (-φ H , 0). Therefore, the USB components of the modulated optical signals are in phase at the output ports 36-1, 36-2, 36-3, and 36-4. When the USB components of the modulated optical signals are in phase, a row-direction combined optical signal with high signal intensity is obtained.

[0267] In the column-direction scanning matrix circuit 51b, the following column-direction combined optical signal is obtained. When waves arriving from the direction of beams 90-1 and 90-5 corresponding to "rightward" are received, the phase difference between the row-direction combined optical signals supplied to the input ports 51-1, 51-2, 51-3, and 51-4 is (0, -φ H2 ,-2φ H2 ,-3φ H3) Therefore, the row-direction combined optical signals are in phase at the output port 51-5.

[0268] When receiving waves coming from the direction of beams 90-2 and 90-6 corresponding to "right center direction," the phase difference of the row-direction combined optical signals supplied to each of the input ports 51-1, 51-2, 51-3, and 51-4 is (0, -φ H1 ,-2φ H1 ,-3φ H1 ) Therefore, the row-direction combined optical signals are in phase at the output port 51-6.

[0269] When receiving waves arriving from the direction of beams 90-3 and 90-7 corresponding to "left center direction," the phase difference of the row-direction combined optical signals supplied to each of the input ports 51-1, 51-2, 51-3, and 51-4 is (-3φ H1 ,-2φ H1 ,-φ H1 , 0). Therefore, the row-direction combined optical signals are in phase at the output port 51-7.

[0270] When receiving waves coming from the direction of beams 90-4 and 90-8 corresponding to "leftward," the phase difference of the row-direction combined optical signals supplied to each of the input ports 51-1, 51-2, 51-3, and 51-4 is (-3φ H2 ,-2φ H2 ,-φ H2 , 0). Therefore, the row direction combined optical signals have the same phase at the output port 51-8. When the row direction combined optical signals have the same phase, a column direction combined optical signal with a large signal intensity is obtained.

[0271] As a result, at output ports 55-1, 56-1, 55-2, 56-2, 55-3, 56-3, 55-4, and 56-4 of demultiplexers 52b-1, 52b-2, 52b-3, and 52b-4, it becomes possible to separate and obtain in parallel the received signals of the waves arriving from each of the directions of beams 90-1 to 90-8, as shown in FIG. 14.

[0272] For example, suppose a user wishes to select and receive incoming waves from the "upward" direction of beams 90-1, 90-2, 90-3, and 90-4. In this case, the user performs an operation on switching switches 25b-1, 25b-2, 25b-3, and 25b-4 to specify one or more of beams 90-1, 90-2, 90-3, and 90-4 as the desired direction. Upon receiving this operation, switching switches 25b-1, 25b-2, 25b-3, and 25b-4 connect input ports 41-1, 41-2, 41-3, and 41-4 to output ports 45-1, 45-2, 45-3, and 45-4, respectively. As a result, only received signals corresponding to waves arriving from the directions of beams 90-1, 90-2, 90-3, and 90-4 corresponding to the "upward direction" are output from output ports 55-1, 55-2, 55-3, and 55-4 of demultiplexers 52b-1, 52b-2, 52b-3, and 52b-4.

[0273] Similarly, the user can select and obtain a received signal corresponding to an incoming wave from the "downward direction" by specifying one or more of beams 90-5, 90-6, 90-7, and 90-8 as the desired direction and changing the connection state of switching SW units 25b-1, 25b-2, 25b-3, and 25b-4 to a state corresponding to the desired direction.

[0274] (Effects of the third embodiment) As shown in the third embodiment, by making the number of antenna elements in the row direction different from the number of antenna elements in the column direction and further making the number of beams formed in the row direction different from that in the column direction, a change in the arrangement of antenna elements 80-1-1 to 80-4-2 and 80-1-1 to 80-2-4 is required. However, in the configuration examples (part 1) and (part 2) of the third embodiment, even if the number of antenna elements is increased, the number of components and wiring does not increase significantly, and the circuit structure does not become more complex, compared to the techniques disclosed in Patent Documents 1 and 2. Therefore, when controlling the reception directivity of array antennas 80b and 80c using the reception directivity control devices 1f and 1g of the third embodiment, even if the scale of array antennas 80b and 80c increases, it is possible to implement the control using a circuit with a simple structure suitable for miniaturization and mass production.

[0275] In another configuration example (part 1) of the second embodiment, the reception directivity control device 1f shown in Fig. 11 is used as the main body 110 of the reception directivity control device 1c described with reference to Fig. 7, and the array antenna 80b is connected to the reception directivity control device 1f. In this state, the reception directivity control device 1f and the array antenna 80b can be rotated 90 degrees by the rotation mechanism 111 to achieve the arrangement of the array antenna 80c shown in Fig. 15.

[0276] In contrast to this, by applying the reception directivity control device 1g shown in Fig. 14 as the main body 110, connecting the array antenna 80c to the reception directivity control device 1g, and rotating it by 90 degrees, it is possible to achieve the arrangement of the array antenna 80b shown in Fig. 12. Therefore, if either the reception directivity control device 1f or the reception directivity control device 1g, the rotation mechanism 111, and the shaft 112 are available, it is possible to use the arrangements of both the array antennas 80b and 80c.

[0277] Here, a comparison of the internal configurations of the reception directivity control device 1f shown in FIG. 11 and the reception directivity control device 1g shown in FIG. 14, other than the electro-optical conversion units 10a and 10b, will be shown below.

[0278] 11 includes three matrix circuits, namely, row scanning matrix circuits 21a-1 and 21a-2 and a column scanning matrix circuit 51a, six frequency converters 22-1, 22-2, 23-1, 23-2, 24-1, and 24-2, two switching SW units 25a-1 and 25a-2, and two demultiplexers 52a-1 and 52a-2. Therefore, the total number of components of the reception directivity control device 1f is 13.

[0279] In contrast, the reception directivity control device 1g shown in Fig. 14 includes five matrix circuits, namely, row scanning matrix circuits 21b-1 to 21b-4 and column scanning matrix circuit 51b, four frequency converters 22-1 to 22-4, four switching switch units 25b-1 to 25b-4, and four demultiplexers 52b-1 to 52b-4. Therefore, the reception directivity control device 1g has 17 components. Therefore, in terms of the number of components, the reception directivity control device 1f has fewer components than the reception directivity control device 1g.

[0280] 11 includes nine square couplers 61-1, 61-2, 62-1, 62-2, 63-1, 63-2, 64-1, 64-2, and 65, six frequency converters 22-1, 22-2, 23-1, 23-2, 24-1, and 24-2, six two-input, one-output SW circuits 16-1-1, 16-1-2, 16-2-1, 16-2-2, 16-3-1, and 16-3-2, and six one-input, two-output couplers 17-1-1, 17-1-2, 17-2-1, 17-2-2, 17-3-1, and 17-3-2. Therefore, the total number of components of the reception directivity control device 1f is 27.

[0281] In contrast, the reception directivity control device 1g shown in Fig. 14 includes eight frequency converters 61-1, 61-2, 61-3, 61-4, 62, 63, 64, and 65, four frequency converters 22-1, 22-2, 22-3, and 22-4, four two-input, one-output SW circuits 16-1, 16-2, 16-3, and 16-4, and four one-input, two-output couplers 17-1, 17-2, 17-3, and 17-4. Therefore, the number of components of the reception directivity control device 1g is 20. Therefore, in terms of the number of components, the reception directivity control device 1g has fewer components than the reception directivity control device 1f.

[0282] The reception directivity control device 1f shown in Fig. 11 uses four frequency channels, frequency ch1 to ch4. The reception directivity control device 1g shown in Fig. 14 uses two frequency channels, frequency ch1 and ch2. Therefore, in terms of the number of frequency channels used, the reception directivity control device 1g has fewer channels than the reception directivity control device 1f, and the number of multiplexed optical signals within the device is also reduced, making it possible to conserve the frequency bandwidth used.

[0283] From the above, if priority is given to a small number of components, it is sufficient to use the reception directivity control device 1f shown in Fig. 11. On the other hand, if priority is given to a small number of components or a small number of frequency channels to be used, it is sufficient to use the reception directivity control device 1g shown in Fig. 14.

[0284] (Fourth embodiment) In the reception directivity control devices 1, 1a, 1b, 1c, 1d, 1e, 1f, and 1g of the first to third embodiments, optical signals of different frequencies are multiplexed in the row-direction combined optical signals supplied to the column-direction scanning matrix circuits 51, 51a, and 51b. In the reception directivity control devices 1, 1a, 1f, and 1g of the first and third embodiments, optical signals of different frequencies are multiplexed in the column-direction combined optical signals output from the column-direction scanning matrix circuits 51, 51a, and 51b.

[0285] Therefore, when determining the spacing between frequency channels (hereinafter referred to as optical frequency channels) of a propagating optical signal, it is important to avoid the adverse effects of unnecessary components, i.e., spurious components, that occur during optical modulation by optical modulators 11-1-1 to 11-3-3, 11-4-1, 11-4-2, 11-1-4, and 11-2-4, and to make maximum use of the optical frequency bandwidth.

[0286] The modulated optical signal generated by each of the optical modulators 11-1-1 to 11-3-3, 11-4-1, 11-4-2, 11-1-4, and 11-2-4 includes a carrier wave and two sideband waves. The frequency component of the carrier wave is the frequency component of the optical signal of frequency ch1 generated by the light source 5. The frequency components of the two sideband waves are the frequency components of the optical signal of sideband waves generated by modulating the carrier wave with the RF signals supplied by the antenna elements 80-1-1 to 80-3-3, 80-4-1, 80-4-2, 80-1-4, and 80-2-4. As described above, the optical modulators 11-1-1 to 11-3-3, 11-4-1, 11-4-2, 11-1-4, and 11-2-4 suppress the unnecessary carrier wave component and the LSB component of the sideband waves, and output only the USB component of the sideband waves. Ideally, the optical modulators 11-1-1 to 11-3-3, 11-4-1, 11-4-2, 11-1-4, and 11-2-4 would completely suppress the unnecessary components, but in reality, there are cases where the unnecessary components remain to some extent.

[0287] If the optical modulators 11-1-1 to 11-3-3, 11-4-1, 11-4-2, 11-1-4, and 11-2-4 can sufficiently suppress the unwanted carrier components and LSB components of the sideband waves, then the spacing of the optical frequency channels can be determined so that the frequency bands containing the USB components of the sideband waves do not overlap with each other.

[0288] For example, in the reception directivity control device 1 shown in Fig. 1, it is assumed that the in-phase combined row-direction optical signals output from each of the output ports 35-1 and 36-1 of the row-direction scanning matrix circuit 21-1 have the frequency components shown in Fig. 17(a-1). In Fig. 17(a-1), reference numeral 101 denotes the frequency component of the carrier wave (hereinafter referred to as carrier frequency component 101). Reference numeral 101-U denotes the frequency component of the USB component of the sideband wave (hereinafter referred to as upper sideband wave frequency component 101-U). Reference numeral 101-L denotes the frequency component of the LSB component of the sideband wave (hereinafter referred to as lower sideband wave frequency component 101-L). c is the center frequency of the carrier frequency component 101, i.e., frequency ch1. The double sidebands are c The RF signal frequency f RF The upper sideband frequency component 101-U appears at positions separated in the positive and negative directions. Therefore, the center frequency of the upper sideband frequency component 101-U is f c +f RF The center frequency of the lower sideband frequency component 101-L is f c -f RF The bandwidth of the upper sideband frequency component 101-U and the lower sideband frequency component 101-L is f BW Then, the bandwidth of the row-direction combined optical signal is f BW +2f RF becomes.

[0289] The case shown in Figure 17(a-1) shows a case where the carrier frequency component 101 and the lower sideband frequency component 101-L are suppressed. In this case, as shown in Figure 17(a-2), the optical frequency channel interval Δf1, which is the interval between frequency ch1 and frequency ch2, which is the frequency of the frequency converter 22-1, can be determined so that the upper sideband frequency component 101-U of frequency ch1 and the upper sideband frequency component 102-U of frequency ch2 do not overlap each other. In this case, the condition for Δf1 can be set as Δf1 ≧ f BW In FIG. 17(a-2), reference numeral 102 denotes a carrier frequency component after frequency conversion by the frequency converter 22-1, and its center frequency f c+Δf1 becomes the frequency ch2. Reference numeral 102-L denotes the lower sideband frequency component after frequency conversion by the frequency converter 22-1.

[0290] As shown in FIG. 17(b-1), it is assumed that the optical modulators 11-1-1 to 11-3-3, 11-4-1, 11-4-2, 11-1-4, and 11-2-4 cannot sufficiently suppress the carrier frequency component 101, but can sufficiently suppress the lower sideband frequency component 101-L. In this case, as shown in FIG. 17(b-2), the optical frequency channel spacing Δf2, which is the spacing between frequency ch1 and frequency ch2, which is the frequency of the frequency converter 22-1, can be determined so that the frequency band including the carrier frequency component 101 and the upper sideband frequency component 101-U and the frequency band including the carrier frequency component 102 and the upper sideband frequency component 102-U do not overlap each other. In this case, the condition for Δf2 is set to Δf2≧0.5f BW +f RF It can be expressed as:

[0291] As shown in FIG. 17(c-1), it is assumed that the optical modulators 11-1-1 to 11-3-3, 11-4-1, 11-4-2, 11-1-4, and 11-2-4 can sufficiently suppress only the carrier frequency component 101. In this case, as shown in FIG. 17(c-2), the optical frequency channel interval Δf3, which is the interval between frequency ch1 and frequency ch2, which is the frequency of the frequency converter 22-1, can be determined so that the frequency bands including both sidebands, i.e., the frequency band including the entire range from the lower sideband frequency component 101-L to the upper sideband frequency component 101-U corresponding to frequency ch1, and the frequency band including the entire range from the lower sideband frequency component 102-L to the upper sideband frequency component 102-U corresponding to frequency ch2, do not overlap with each other. In this case, the condition for Δf3 can be set to Δf3≧f BW +2f RF It should be noted that even when it is not possible to sufficiently suppress both the carrier frequency component 101 and the lower sideband frequency component 101-L, the spacing Δf3 between the optical frequency channels can be determined in the same manner as in the example shown in FIG.

[0292] The same frequency ch2 as that of frequency converter 22-1 is also set in frequency converters 22-2 and 22-3 other than frequency converter 22-1. A method similar to that for setting the optical frequency channel of frequency ch2 between frequency ch1 and frequency ch2 described above is applied between frequency ch2 and frequency ch3 to determine the optical frequency channel of frequency ch3 to be set in frequency converters 23-1, 23-2, and 23-3. In the case of the reception directivity control device 1f shown in Fig. 11, a method similar to that for setting the optical frequency channel of frequency ch2 between frequency ch1 and frequency ch2 described above is further applied between frequency ch3 and frequency ch4 to determine the optical frequency channel of frequency ch4 to be set in frequency converters 24-1 and 24-2.

[0293] However, the optical frequency channels do not necessarily have to be equally spaced, and the spacing can be changed as appropriate to prevent unwanted components that cannot be sufficiently suppressed from interfering with other USB components or to minimize the optical frequency bandwidth used.

[0294] The RF signals supplied by the antenna elements 80-1-1 to 80-3-3, 80-4-1, 80-4-2, 80-1-4, and 80-2-4 may have different bandwidths for each of the beams 90-1 to 90-9. In this case, the spacing between the optical frequency channels may be determined according to the bandwidth of the RF signal with the widest bandwidth among the RF signals supplied by the antenna elements 80-1-1 to 80-3-3, 80-4-1, 80-4-2, 80-1-4, and 80-2-4.

[0295] (Other configuration examples of each embodiment) In the array antennas 80, 80b, and 80c shown in the first to third embodiments, the vertical direction is the row direction and the horizontal direction is the column direction, while in the array antenna 80a obtained by rotating the array antenna 80 by 90 degrees, the vertical direction is the column direction and the horizontal direction is the row direction. In contrast, any straight line on the surface of the array antennas 80, 80b, and 80c is defined as the row direction axis, and a straight line on the surface of the array antennas 80, 80b, and 80c that is perpendicular to the row direction axis is defined as the column direction axis. Antenna elements 80-1-1 to 80-3-3, 80-4-1, 80-4-2, 80-1-4, and 80-2-4 may be arranged along the row direction axis and column direction axis defined in this manner.

[0296] In the above-described first and second embodiments, an example is shown in which the number of antenna elements in the array antennas 80 and 80a is nine, and in the third embodiment, an example is shown in which the number of antenna elements in the array antennas 80b and 80c is eight. It has been explained that the number of antenna elements may be increased in these embodiments. The condition for the number of antenna elements is more specifically stated as follows, for example. Let M be the number of antenna elements in the row direction and N be the number of antenna elements in the column direction. As long as M and N are positive integers and satisfy the condition M×N≧2, any values ​​of M and N may be selected. In this case, either one of M and N may be 1. However, the spacing between adjacent antenna elements does not necessarily have to be equal; the antenna elements may be thinned out by removing some of the antenna elements that are arranged at equal intervals.

[0297] In the above embodiments, the optical modulators 11-1-1 to 11-3-3, 11-4-1, 11-4-2, 11-1-4, and 11-2-4 are configured to output the USB component of the modulated optical signal, but may also be configured to output the LSB component, which is the other component of the single sideband wave.

[0298] The optical modulators 11-1-1 to 11-3-3, 11-4-1, 11-4-2, 11-1-4, and 11-2-4 shown in the above embodiments have been described as optical modulators that perform SSB optical modulation, for example. Since the optical modulators 11-1-1 to 11-3-3, 11-4-1, 11-4-2, 11-1-4, and 11-2-4 output only the USB component of the modulated optical signal, they also have a filter function that suppresses the carrier component and the LSB component. Therefore, instead of an optical modulator that performs SSB optical modulation, each of the optical modulators 11-1-1 to 11-3-3, 11-4-1, 11-4-2, 11-1-4, and 11-2-4 may be an optical modulator such as a direct modulator or a phase modulator, and may be provided with a filter on the output side that suppresses the carrier component and the LSB component. In this case, the components including the optical modulator and the filter are the electrical-optical conversion units 10, 10a, and 10b.

[0299] In the reception directivity control devices 1b, 1c, 1d, and 1e of the second embodiment, multiplexers 26-1, 26-2, and 26-3 may be used instead of the switching switches 25-1, 25-2, and 25-3, as in the reception directivity control device 1a of the first embodiment shown in Fig. 5. A four-input, one-output multiplexer may be used instead of the switching switches 25a-1 and 25a-2 of the reception directivity control device 1f of the third embodiment, and a two-input, one-output multiplexer may be used instead of the switching switches 25b-1, 25b-2, 25b-3, and 25b-4 of the reception directivity control device 1g.

[0300] When multiplexers are used instead of the switching switches 25-1 to 25-3, 25a-1, 25a-2, and 25b-1 to 25b-4 as described above, a determination circuit may be provided in front of each input port of the multiplexer to determine whether the received row-direction combined optical signal is an in-phase combined row-direction combined optical signal or a non-in-phase combined row-direction combined optical signal, for example, based on a predetermined threshold. If the determination circuit determines that the received row-direction combined optical signal is an in-phase combined row-direction combined optical signal, it outputs the received row-direction combined optical signal to the multiplexer. On the other hand, if the determination circuit determines that the received row-direction combined optical signal is not an in-phase combined row-direction combined optical signal, it discards the received row-direction combined optical signal. This makes it possible to remove optical signals that are unnecessary for the processing performed by the column-direction scanning matrix circuits 51, 51a, and 51b in the subsequent stages.

[0301] The reception directivity control devices 1, 1a, 1f, and 1g may each include a determination circuit at a stage preceding each of the input ports of the demultiplexers 52-1 to 52-3, 52a-1, 52a-2, and 52b-1 to 52b-4 that determines, for example, based on a predetermined threshold, whether the received column-direction combined optical signal is an in-phase combined column-direction combined optical signal. If the determination circuit determines that the received column-direction combined optical signal is an in-phase combined column-direction combined optical signal, it outputs the received column-direction combined optical signal to the demultiplexers 52-1 to 52-3, 52a-1, 52a-2, and 52b-1 to 52b-4. On the other hand, if the determination circuit determines that the received column-direction combined optical signal is not an in-phase combined column-direction combined optical signal, it discards the received column-direction combined optical signal. This makes it possible to remove unnecessary optical signals and obtain a received signal.

[0302] A device-to-be-used selection unit 27 shown in FIG. 9 may be connected to frequency converters 22-1, 22-2, 22-3, 23-1, 23-2, and 23-3 provided in row direction scanning unit 20 of reception directivity control device 1 of the first embodiment, frequency converters 22-1, 22-2, 23-1, 23-2, 24-1, and 24-2 provided in row direction scanning unit 20c of reception directivity control device 1f of configuration example (part 1) of the third embodiment, and frequency converters 22-1, 22-2, 22-3, and 22-4 provided in row direction scanning unit 20d of reception directivity control device 1g of configuration example (part 2) of the third embodiment.

[0303] For example, in the case of the receiving directivity control device 1 of the first embodiment, if the user wants to avoid receiving incoming waves from the direction of beams 90-4, 90-5, and 90-6 corresponding to the "middle direction," the user can operate the switching SW units 25-1, 25-2, and 25-3 to specify a desired direction that does not include the direction of beams 90-4, 90-5, and 90-6, and also operate the equipment selection unit 27 to select not to supply power to the frequency converters 22-1, 22-2, and 22-3, thereby reducing the power consumed by the frequency converters 22-1, 22-2, and 22-3.

[0304] On the other hand, if the user wishes to avoid receiving incoming waves from the direction of beams 90-7, 90-8, and 90-9 corresponding to the "downward direction," the user can operate switching SW units 25-1, 25-2, and 25-3 to specify a desired direction that does not include the direction of beams 90-7, 90-8, and 90-9, and also operate equipment selection unit 27 to select not to supply power to frequency converters 23-1, 23-2, and 23-3, thereby reducing the power consumed by frequency converters 23-1, 23-2, and 23-3.

[0305] Similarly, by selecting not to supply power to the frequency converters 22-1, 22-2, 23-1, 23-2, 24-1, 24-2 of the reception directivity control device 1f of the third embodiment and the frequency converters 22-1, 22-2, 22-3, 22-4 of the reception directivity control device 1g, which correspond to directions in which no incoming waves are received, the power consumed can be reduced.

[0306] In the first to third embodiments, a specific example of the row-direction scanning matrix circuits 21-1, 21-2, 21-3, 21a-1, 21a-2, 21b-1, 21b-2, 21b-3, 21b-4 and the column-direction scanning matrix circuits 51, 51a, 51b is, for example, a Butler matrix circuit, as described in the third embodiment. However, the present invention is not limited to the Butler matrix circuit, and a matrix circuit other than the Butler matrix circuit may also be applied.

[0307] The row-direction scanning matrix circuits 21-1, 21-2, 21-3, 21a-1, 21a-2, 21b-1, 21b-2, 21b-3, and 21b-4 and the column-direction scanning matrix circuits 51, 51a, and 51b may be circuits that transmit a spatial beam optical signal, i.e., an optical signal propagating through space, through a lens and impart a phase tilt to the optical signal. Note that, in addition to optical lenses, the lens may also be, for example, a Rotman lens described in Reference 2 below.

[0308] [Reference 2: Z. Zalevsky et al., “A Novel Photonic Rotman-Lens Design for Radar Phased Array Antennas” 2009 IEEE International Conference on Microwaves, Communications, Antennas and Electronics Systems, 9 Nov., 2009.]

[0309] In each of the above embodiments, the reception directivity control devices 1, 1a, 1b, 1c, 1d, 1e, 1f, and 1g do not include the array antennas 80, 80a, 80b, and 80c, but are connected to the array antennas 80, 80a, 80b, and 80c. In contrast, each of the reception directivity control devices 1, 1a, 1b, 1c, 1d, 1e, 1f, and 1g may be configured to include the array antennas 80, 80a, 80b, and 80c connected thereto.

[0310] Although an embodiment of the present invention has been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes designs within the scope of the gist of the present invention. [Industrial Applicability]

[0311] The present invention can be applied to ultra-high speed wireless transmission using radio waves in the millimeter wave band or terahertz band, high definition imaging, and reception of radio waves with sharp directionality formed in radar, etc. [Explanation of symbols]

[0312] REFERENCE SIGNS LIST 1...receiving directivity control device, 10...electrical-optical conversion section, 11-1-1 to 11-3-3...optical modulators, 20...row direction scanning section, 21-1 to 21-3...row direction scanning matrix circuit, 22-1 to 22-3, 23-1 to 23-3...frequency converters, 25-1 to 25-3...switching switch section, 50...column direction scanning section, 51...column direction scanning matrix circuit, 52-1 to 52-3...branching filter, 80...array antenna, 80-1-1 to 80-3-3...antenna elements

Claims

1. A reception directivity control device that controls reception directivity of an array antenna in which an arbitrary straight line in a plane is defined as a row-direction axis, a straight line in the plane that is orthogonal to the row-direction axis is defined as a column-direction axis, and a plurality of antenna elements are arranged along the row-direction axis and the column-direction axis, a light source for generating an optical signal; an electro-optical converter that modulates the optical signal with each RF signal obtained by receiving the incoming wave at each of the antenna elements, and outputs a single sideband component of the modulated optical signal obtained by the modulation; a row direction scanning unit that performs a predetermined row direction phase scanning process for each combination of single sideband wave components having the same column position, in which a phase gradient is applied to each of the single sideband wave components included in each of the combinations to align the phases of the row direction components in the beam forming direction, taking into account differences in the row positions corresponding to each of the single sideband wave components and a row direction phase gradient that occurs depending on each of the beam forming directions, to generate a row direction synthesized optical signal corresponding to each of the row direction components in the beam forming direction, and converts the frequency of the generated row direction synthesized optical signal to a frequency that differs for each of the row direction components in the beam forming direction, and outputs the converted signal; a column direction scanning unit that performs a predetermined column direction phase scanning process on each of the row direction combined optical signals output by the row direction scanning unit, the process applying a phase gradient that aligns the phase of each column direction component in the beam forming direction based on a difference in the position of each corresponding column and a column direction phase gradient that occurs depending on each of the beam forming directions, to generate a column direction combined optical signal corresponding to each column direction component in the beam forming direction; A receiving directivity control device comprising:

2. The row direction scanning unit outputting the row direction combined optical signal corresponding to the row direction component of the beam forming direction that coincides with the specified desired direction from among the row direction combined optical signals converted to different frequencies; The receiving directivity control device according to claim 1 .

3. The column direction scanning unit demultiplexing the column-direction combined optical signal into signals for each frequency, and outputting the demultiplexed optical signals; The receiving directivity control device according to claim 1 .

4. The row direction scanning unit the row-direction combined optical signals converted into different frequencies are combined and output; The receiving directivity control device according to claim 1 .

5. a rotation mechanism that rotates the array antenna and at least the electro-optical converter so that an axis in the column direction before rotation overlaps an axis in the row direction after rotation, When an incoming wave arrives from a direction having a different row direction component in a state of the array antenna before rotation, the rotation mechanism unit rotates the array antenna and at least the electro-optical converter unit so that the column direction axis before rotation overlaps with the row direction axis after rotation, thereby creating a state in which the incoming wave arrives from a direction having a different column direction component. The receiving directivity control device according to claim 1 .

6. a row and column permutation unit that, when the number of antenna elements in the row direction is the same as the number of antenna elements in the column direction, captures the single sideband wave component output from the electro-optical conversion unit, permutes the row and column positions of the captured single sideband wave component, and outputs the permuted single sideband wave component to the row direction scanning unit; When the row direction components of the incoming waves arrive from different directions, the matrix permutation unit permutes the rows and columns of the captured single sideband wave components to make the column direction components arrive from different directions. The receiving directivity control device according to claim 1 .

7. When the incoming waves come from different directions with different column components, The row direction scanning unit outputting the generated row direction combined optical signals corresponding to each of the row direction components in the beam forming direction while maintaining the frequencies of the row direction combined optical signals; The receiving directivity control device according to any one of claims 1, 5 and 6.

8. A reception directivity control method for controlling reception directivity of an array antenna in which an arbitrary straight line in a plane is defined as a row-direction axis, a straight line in the plane that is orthogonal to the row-direction axis is defined as a column-direction axis, and a plurality of antenna elements are arranged along the row-direction axis and the column-direction axis, comprising: modulating an optical signal generated by a light source with each of the RF signals obtained by receiving the incoming waves at each of the antenna elements, and outputting a single sideband wave component of the modulated optical signal obtained by the modulation; for each combination of the single sideband wave components having the same column position, performing a predetermined row direction phase scanning process to impart a phase gradient to each of the single sideband wave components included in each of the combinations, taking into account differences in the row positions corresponding to each of the single sideband wave components and row direction phase gradients that occur depending on each of the beam forming directions, to align the phases of the row direction components in the beam forming direction, thereby generating a row direction synthesized optical signal corresponding to each of the row direction components in the beam forming direction; converting the frequency of the generated row direction combined optical signal so that each row direction component in the beam forming direction has a different frequency; and performing a predetermined column-direction phase scanning process on each of the converted row-direction combined optical signals, which applies a phase gradient that aligns the phase of each column-direction component in the beam-forming direction, taking into account a difference in the position of each corresponding column and a column-direction phase gradient that occurs depending on each of the beam-forming directions, to combine the converted row-direction combined optical signals, thereby generating a column-direction combined optical signal corresponding to each of the column-direction components in the beam-forming direction. Reception directivity control method.

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