JP7810930B2 - Reception directivity control device and reception directivity control method - Google Patents

Description

The present invention relates to a receiving directivity control device and a receiving directivity control method.

In order to achieve faster and larger-capacity wireless communications, efforts are underway to utilize high-frequency bands above the millimeter wave band. 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. For this reason, high-gain antennas are often used in high-frequency bands. High-gain antennas have high directivity, making it necessary to align the antenna beam direction with the position of the other station in the wireless communication. When the other station moves, beam steering is also required, a means of dynamically controlling the beam direction to match the movement of the other station. Beam steering is required not only for wireless communications, but also for applications such as radar, imaging, and wireless power transmission.

Methods of beam steering have been proposed and are currently in use, including mechanically controlling the direction of the antenna and using movable lenses or reflectors to refract and reflect the radio waves emitted from the antenna. However, because these methods involve mechanical structures, there are problems with durability and ability to track movement. For this reason, phased array antennas, which do not involve mechanical structures and are suitable for making antennas smaller and lighter, have become more widely used in recent years.

In a phased array antenna, beam steering is performed, for example, as follows: Multiple antenna elements are arranged on a line or a surface, and variable delay circuits and variable attenuator circuits are connected to the multiple antenna elements. In addition to the variable delay circuits and variable attenuator circuits, digital signal processing and other techniques are used to control the phase and amplitude of the RF (Radio Frequency) signal fed to each of the multiple 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 use analog circuits for weighting are widely used in fifth-generation mobile communication systems and millimeter-wave wireless LAN (Local Area Network) systems that use millimeter-wave bands.

As the range of utilized high-frequency bands expands, even higher antenna gains will be required, and phased array antennas that weight a larger number of antenna elements are expected to be necessary. For example, Non-Patent Document 1 discloses a method for configuring a 256-element phased array antenna for use 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. If the radio frequency becomes about 10 times higher than the 28 GHz band, the free-space path loss will increase by 100 times. In other words, the free-space path loss will increase 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 using the base station's antenna gain.

To minimize power loss in antenna elements, for example, it is necessary to shorten the RF transmission line between the antenna element and the phase shifter circuit as much as possible. Therefore, particularly in high-frequency phased array antennas, such as those in the millimeter wave band, phase shifter circuits are configured to be located near each antenna element. However, as the radio frequency increases, the spacing between antenna elements becomes narrower, making it difficult to arrange multiple phase shifter circuits at spacings equivalent to the spacing between antenna elements. For example, at a radio frequency of 300 GHz, the free-space wavelength is 1 mm, so the spacing between antenna elements is typically half the wavelength, or 0.5 mm. Additionally, to create a circuit that forms multiple beams, i.e., a multi-beam forming circuit, it is necessary to arrange the same number of phase shifters in parallel as the number of beams, further complicating the arrangement.

For example, Non-Patent Document 2 proposes a method that applies 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 great potential for creating 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 in proportion to 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:

Patent Document 1 discloses an "optically controlled array antenna device" that performs two-dimensional multi-beam control using a wavelength dispersive line. FIGS. 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 tilt in the horizontal and vertical planes using a wavelength-tunable light source and a line using a waveguide with large wavelength dispersion. However, the number of one-dimensional phase shift circuits, i.e., wavelength dispersive optical fiber groups "EL ₁ " to "EL _P " and "AZ ₁ " to "AZ _N " in FIG. 1 of Patent Document 1, corresponds to 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.

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 overview of the configuration of a two-dimensional beam control device equipped with an array antenna with a vertical direction count × horizontal direction count of 5 × 13. As shown in Fig. 2, the light from wavelength-tunable light source #1, designated by the 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 the reference numeral 52. The light to which this phase tilt has been imparted is converted into an electrical signal train by a photodiode 54, and the converted electrical signal train is amplified by an amplifier 56.

Next, the light from wavelength-tunable light source #2, designated by the reference numeral 84, is distributed into a number equal to the number of vertical elements. Optical modulator 58 modulates each of the distributed light from wavelength-tunable light source #2 with the electrical signal sequence amplified by amplifier 56 to generate an optical signal sequence. Each of the optical signal sequences generated by optical modulator 58 is distributed into a number equal to the number of horizontal elements. A phase tilt in the horizontal plane is imparted to each of the distributed optical signal sequences by a second wavelength dispersion line sequence, designated by the reference numeral 62. In the above configuration, two-dimensional beam control becomes possible by changing the wavelengths of wavelength-tunable light source #1 and wavelength-tunable light source #2.

Referring to Fig. 3 of Patent Document 2, the operation during reception will be explained. 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 the optical modulator 104. The generated optical signal is split by the optical fiber splitter 112, and the split optical signal is given a phase tilt by a delay waveguide with large chromatic dispersion, indicated by the 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, indicated by the reference numeral 114.

The downconversion mixer 126 provided 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. Because the RF local oscillator signal is given a phase gradient according to the beam direction, the resulting IF signal is in phase across 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.

Japanese Patent Application Laid-Open No. 2004-023400 U.S. Patent No. 6,337,660

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. 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.

When constructing a larger-scale two-dimensional array antenna using the technologies disclosed in Patent Documents 1 and 2, 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, forming and receiving multiple beams would likely require a number of multiplexers equal to the number of beams 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's height and use a printed circuit manufacturing process for mass production, the three-dimensional circuit structure that uses wavelength dispersion lines to provide a phase tilt, as in the technologies disclosed in Patent Documents 1 and 2, is not suitable for mass production.

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

In light of the above circumstances, the present invention aims to provide 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 array antenna becomes large in size.

One aspect of the present invention is a receiving directivity control device that controls the receiving directivity of an array antenna in which an arbitrary straight line in a plane is defined as a row axis, a straight line perpendicular to the row axis in the plane is defined as a column axis, and multiple antenna elements are arranged along the row axis and the column axis. The receiving directivity control device includes a light source that generates an optical signal, an electro-optical converter that modulates the optical signal with each of the RF signals obtained by receiving incoming waves at each of the antenna elements and outputs a single sideband wave component of the modulated optical signal obtained by the modulation, and, for each combination of the single sideband wave components having the same column position, calculates a row direction phase gradient for each of the single sideband wave components included in each of the combinations in consideration of the difference in the row position corresponding to each of the single sideband wave components and each of the beam forming directions. a row direction scanning unit that generates a row direction combined optical signal corresponding to each of the row direction components in the beam forming direction by combining the row direction combined optical signals by performing a predetermined row direction phase scanning process that imparts a phase gradient that aligns the phase of each of the column direction components in the beam forming direction to each of the row direction combined optical signals generated 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, and that generates a column direction combined optical signal corresponding to each of the column direction components in the beam forming direction, and selects and outputs the column direction combined optical signal that corresponds to the column direction component in the beam forming direction that coincides with a specified desired direction.

One aspect of the present invention is a reception directivity control method for controlling the reception directivity of an array antenna in which an arbitrary straight line in a plane is defined as a row axis, a straight line perpendicular to the row axis in the plane is defined as a column axis, and multiple antenna elements are arranged along the row axis and the column axis. The method modulates an optical signal generated by a light source using each RF signal obtained by receiving an incoming wave at each of the antenna elements, and outputs a single sideband wave component of the modulated optical signal obtained by the modulation. For each combination of single sideband wave components having the same column position, the method controls the reception directivity of each of the single sideband wave components included in each combination based on the difference in the row position corresponding to each single sideband wave component and each beamforming direction. a predetermined column-direction phase scanning process for applying a phase gradient to each of the generated row-direction combined optical signals to align the phases of the respective column-direction components in the beam-forming direction, 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; and a receiving directivity control method for selecting and outputting the column-direction combined optical signal that corresponds to the column-direction component in the beam-forming direction that coincides with a specified desired direction.

The present invention makes it possible to control the receiving directivity of an array antenna by implementing a circuit with a simple structure that is suitable for miniaturization and mass production, even if the array antenna becomes large in size.

1 is a block diagram showing a configuration related to a reception directivity control device according to a first embodiment; 2A and 2B are diagrams illustrating the arrangement of antenna elements in the array antenna of the first embodiment and the beams formed. FIG. 4 is a diagram showing the direction of a beam formed in the first embodiment. 4 is a flowchart showing a flow of processing by the reception directivity control device of the first embodiment. FIG. 10 is a block diagram showing a configuration related to a reception directivity control device according to a second embodiment. 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. 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. 10 is a flowchart illustrating a usage scene of each configuration example of the second embodiment. FIG. 10 is a block diagram showing a configuration related to a receiving directivity control device used when a received signal cannot be obtained by each configuration example of the second embodiment. 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. FIG. 11 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. FIG. 10 is a diagram showing the arrangement of antenna elements in an array antenna of a configuration example (part 1) of the third embodiment. FIG. 10 is a diagram showing the direction of a beam formed in a configuration example (part 1) of the third embodiment. FIG. 13 is a block diagram showing a configuration related to a reception directivity control device according to a configuration example (part 2) of the third embodiment. FIG. 10 is a diagram illustrating the arrangement of antenna elements in an array antenna according to a second configuration example of the third embodiment. FIG. 10 is a diagram showing the direction of a beam formed in a configuration example (part 2) of the third embodiment.

(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.

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

By connecting the array antenna 80 to the receiving directivity control device 1, a so-called phased array antenna is formed. As shown in FIG. 2, the array antenna 80 is a 3x3 array antenna with three elements arranged vertically and three elements arranged horizontally, for a total of 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. Here, the vertical direction is the 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. Note that 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.

The arrangement will be explained in more detail. 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 column axis. Similarly, antenna elements 80-2-1, 80-2-2, and 80-2-3 in the second row and 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 column axis. Antenna elements 80-1-1, 80-1-2, and 80-1-3 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, and 80-2-3, and the distance between adjacent antenna elements in antenna elements 80-3-1, 80-3-2, and 80-3-3.

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

Therefore, the shape with vertices at the positions of antenna elements 80-1-1, 80-1-3, 80-3-3, and 80-3-1 is rectangular. In this case, the distance between adjacent antenna elements 80-1-1 and 80-1-2 in the column direction and the distance between adjacent antenna elements 80-1-1 and 80-2-1 in the row direction may be the same or different. If they are the same length, 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.

The reception directivity control device 1 includes a light source 5, an electro-optical conversion unit 10, a row scanning unit 20, and a column scanning unit 50. The reception directivity control device 1 controls the directivity so that incoming waves coming from the direction desired by the user (hereinafter referred to as the desired direction) are received. 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. 2.

Figure 3 is a diagram showing the relationship between the plane of array antenna 80 and the direction 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 Figure 2, i.e., from the side where reception directivity control device 1 is installed, as shown in Figure 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.

Beam 90-5 is formed so as to point 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 point 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 point 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").

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"). 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").

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."

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 represented by "φ _V ."

Beams 90-1, 90-4, and 90-7 are formed so that the inclinations of beams 90-1, 90-4, and 90-7 relative to the vertical plane, in other words, the horizontal components of the inclinations of beams 90-1, 90-4, and 90-7, are the same. The phase tilt, which is the phase difference caused by the horizontal components of the inclinations of beams 90-1, 90-4, and 90-7, is represented by "φ _H ". Note that "φ _V " and "φ _H " may be different values or may be the same value.

Here, the phase tilt will be explained in more detail. For example, suppose 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 is a difference in the arrival time 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 time, a phase difference _φV occurs in the RF signals obtained from adjacent antenna elements 80-1-1 and 80-2-1. Similarly, a phase difference _φV also occurs in the RF signals obtained from adjacent antenna elements 80-2-1 and 80-3-1. That is, the RF signal obtained by delaying the phase of the RF signal obtained from antenna element 80-1-1 _{by φV} becomes the RF signal obtained from antenna element 80-2-1, and the RF signal obtained by delaying the phase of the RF signal obtained from antenna element 80-1-1 _{by 2φV} becomes the RF signal obtained from antenna element 80-3-1.

As described above, the spacing between each of the antenna elements 80-1-2, 80-2-2, and 80-3-2 in the second row and the spacing 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 spacing between each of the antenna elements 80-1-1, 80-2-1, and 80-3-1 in the first row. Therefore, even when antenna elements 80-1-2, 80-2-2, and 80-3-2 receive an incoming wave from the direction of beam 90-1, the phase difference between the RF signals obtained from each of the adjacent antenna elements is _φV . Even when antenna elements 80-1-3, 80-2-3, and 80-3-3 receive an incoming wave from the direction of beam 90-1, the phase difference between the RF signals obtained from each of the adjacent antenna elements is _φV . This phase difference _φV becomes the phase gradient in the row direction of the beam 90-1 (hereinafter referred to as the row direction phase gradient).

Similarly, due to the inclination of beam 90-1 with respect to the vertical plane, even when three antenna elements 80-1-1, 80-1-2, and 80-1-3 in the same row receive an incoming wave from the direction of beam 90-1, there will be 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 _φH occurs between the RF signals obtained from antenna element 80-1-1 and antenna element 80-1-2. Similarly, a phase difference _φH also occurs between the RF signals obtained from antenna element 80-1-2 and antenna element 80-1-3. In other words, the RF signal obtained from antenna element 80-1-1 is delayed in phase by _φH , and becomes the RF signal obtained from antenna element 80-1-2. The RF signal obtained from the antenna element 80-1-3 is an RF signal obtained by delaying the phase of the RF signal obtained from the antenna element 80-1-1 by _2φH .

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. Therefore, this phase difference _φH becomes the phase tilt in the column direction of beam 90-1 (hereinafter referred to as the column-direction phase tilt).

Beams 90-7, 90-8, and 90-9 are formed so that the row-wise phase tilt is the exact opposite of the row-wise phase tilt of beams 90-1, 90-2, and 90-3. Therefore, the row-wise 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-wise phase tilt is the exact opposite of the column-wise phase tilt of beams 90-1, 90-4, and 90-7. Therefore, the column-wise phase tilt 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 that direction, no phase difference occurs in the RF signals obtained from all of antenna elements 80-1-1 to 80-3-3.

Therefore, the phase gradients of beams 90-1 to 90-9 can be expressed in the form of (row-wise phase gradient, column-wise phase gradient) as follows: Beam 90-1 is (φ _V , φ _H ), beam 90-2 is (φ _V , 0), and beam 90-3 is (φ _V , -φ _H ). Beam 90-4 is (0, φ _H ), beam 90-5 is (0, 0), and beam 90-6 is (0, -φ _H ). Beam 90-7 is (-φ _V , φ _H ), beam 90-8 is (-φ _V , 0), and beam 90-9 is (-φ _V , -φ _H ).

The light source 5 generates a single-frequency optical signal 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 provided in the electrical-to-optical conversion unit 10.

The electrical-to-optical conversion unit 10 has 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. Each of the optical modulators 11-1-1 to 11-3-3 is connected to a corresponding antenna element 80-1-1 to 80-3-3.

Of the two sub-numbers included in the symbols for antenna elements 80-1-1 to 80-3-3 and 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, antenna element 80-2-1 is located in the second row and first column. Each of optical modulators 11-1-1 to 11-3-3 is connected to antenna elements 80-1-1 to 80-3-3 that share the same combination of two sub-numbers. To minimize RF signal loss, each of optical modulators 11-1-1 to 11-3-3 should preferably be located near the antenna elements 80-1-1 to 80-3-3 to which it is connected.

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 to it with the RF signal supplied from the antenna elements 80-1-1 to 80-3-3 connected to it, and outputs the single sideband component of the modulated optical signal. Note that the single sideband component includes a USB (Upper Side Band) component and an LSB (Lower Side Band) component. However, the following explanation assumes that the optical modulators 11-1-1 to 11-3-3 output the USB component.

The row direction scanning unit 20 has circuit configurations in the same number as 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 and a switching SW unit 25-1 that connect to the optical modulators 11-1-1, 11-2-1, and 11-3-1 in the first column. The circuit configuration corresponding to the second column is a row direction scanning matrix circuit 21-2 and a switching SW unit 25-2 that connect to the optical modulators 11-1-2, 11-2-2, and 11-3-2 in the second column. The circuit configuration corresponding to the third column is a row direction scanning matrix circuit 21-3 and a switching SW unit 25-3 that connect to the optical modulators 11-1-3, 11-2-3, and 11-3-3 in the third column.

The three circuit configurations provided in the row direction scanning unit 20 are identical, and below, as an example, we will explain the row direction scanning matrix circuit 21-1 and switching SW unit 25-1, which are the circuit configurations corresponding to the first column. In the explanation of the circuit configuration corresponding to the first column below, the branch number "-1" of the symbol is replaced with "-2" to explain the circuit configuration corresponding to the second column, and the branch number "-1" of the symbol is replaced with "-3" to explain the circuit configuration corresponding to the third column. However, in the explanation 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 is replaced with "-2" or "-3."

The row-direction scanning matrix circuit 21-1 is a one-dimensional weighting circuit and has 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 the three optical modulators 11-1-1, 11-2-1, and 11-3-1 in the first column. More specifically, optical modulator 11-1-1 is connected to input port 31-1, optical modulator 11-2-1 is connected to input port 32-1, and optical modulator 11-3-1 is connected to input port 33-1.

The row-direction scanning matrix circuit 21-1 performs a process to change the phase 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, we will assume 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.

Assume that an optical signal is supplied to output port 35-1 of row-direction scanning matrix circuit 21-1. In this case, row-direction scanning matrix circuit 21-1 outputs the optical signal supplied from output port 35-1 as is from input port 31-1, outputs an optical signal obtained by delaying the phase of the supplied optical signal _{by φV} from input port 32-1, and outputs an optical signal obtained by delaying the phase of the supplied optical signal _{by 2φV} from input port 33-1. Therefore, the phase differences of the optical signals output from input ports 31-1, 32-1, and 33-1 are (0, _-φV , _-2φV ).

Suppose an optical signal is supplied to output port 36-1 of row-direction scanning matrix circuit 21-1. In this case, row-direction scanning matrix circuit 21-1 outputs the optical signal supplied from output port 36-1 as is from input ports 31-1, 32-1, and 33-1. Therefore, the phase difference between the optical signals output from input ports 31-1, 32-1, and 33-1 becomes (0,0,0), meaning there is no phase difference.

Assume that an optical signal is supplied to output port 37-1 of row-direction scanning matrix circuit 21-1. In this case, row-direction scanning matrix circuit 21-1 outputs the optical signal supplied from output port 37-1 as is from input port 33-1, outputs an optical signal obtained by delaying the phase of the supplied optical signal _{by φV} from input port 32-1, and outputs an optical signal obtained by delaying the phase of the supplied optical signal _{by 2φV} from input port 31-1. Therefore, the phase differences of the optical signals output from input ports 31-1, 32-1, and 33-1 are ( _-2φV , _-φV , 0).

Inversely to the above, 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. Hereinafter, this process will be referred to as the "predetermined row-direction phase scanning process" performed by the row-direction scanning matrix circuit 21-1.

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, these optical signals are referred to as row-direction combined optical signals). 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.

Assume that three optical signals with phase differences of (0, -φ _V , -2φ _V ) are supplied to each of input ports 31-1, 32-1, and 33-1. In other words, assume that an optical signal whose phase is delayed by φ _V from the optical signal supplied to input port 31-1 is supplied to input port 32-1, and an optical signal whose phase is delayed by 2φ _V from the optical signal supplied to input port 31-1 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 strength of the row direction combined optical signal at each of the output ports 36-1 and 37-1 is smaller than the signal strength of the row direction combined optical signal at the output port 35-1.

Let's 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 has a high signal intensity. In contrast, the three optical signals included in the row-direction combined optical signal 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 for each of the output ports 35-1 and 37-1 is lower than the signal intensity of the row-direction combined optical signal for output port 36-1.

Assume that three optical signals with phase differences of (-2φ _V , -φ _V , 0) are supplied to each of input ports 31-1, 32-1, and 33-1. In other words, assume that an optical signal whose phase is delayed by φ _V from the optical signal supplied to input port 33-1 is supplied to input port 32-1, and an optical signal whose phase is delayed by 2φ _V from the optical signal supplied to input port 33-1 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 strength of the row direction combined optical signal at each of the output ports 35-1 and 36-1 is smaller than the signal strength of the row direction combined optical signal at the output port 37-1.

The switching SW 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 output port 36-1, and the input port 43-1 is connected to the output port 37-1.

The switching SW unit 25-1 receives an operation by the user to specify a desired direction, selects one of the input ports 41-1, 42-1, 43-1 corresponding to the specified desired direction, and connects the selected one of the input ports 41-1, 42-1, 43-1 to the output port 45-1.

Each of the input ports 41-1, 42-1, and 43-1 of the switching SW unit 25-1 is pre-assigned to three row direction components in the direction of beams 90-1 to 90-9. Here, as mentioned above, the row direction is the vertical direction, so the row direction components are also vertical direction components.

Input port 41-1 is pre-assigned to the "upward direction," which is the row component of the direction 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 direction 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 direction of beams 90-7, 90-8, and 90-9.

The column scanning unit 50 comprises a column scanning matrix circuit 51 and a switching SW unit 52. The column scanning matrix circuit 51 is a one-dimensional weighting circuit and comprises 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 SW unit 25-1. The input port 51-2 is connected to the output port 45-2 of the switching SW unit 25-2. The input port 51-3 is connected to the output port 45-3 of the switching SW unit 25-3.

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, thereby generating 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, these optical signals are referred to as column-direction combined optical signals). 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.

The predetermined column-direction phase scanning process performed by the column-direction scanning matrix circuit 51 is the same as the predetermined row-direction phase scanning process performed by the row-direction scanning matrix circuit 21-1 under the input/output conditions shown below, where "φ _v " is replaced with "φ _H ". Here, the input/output conditions refer to the conditions that, on the input side, the input port 51-1 corresponds to the input port 31-1, the input port 51-2 corresponds to the input port 32-2, and the input port 51-3 corresponds to the input port 33-1. On the output side, the output port 51-5 corresponds to the output port 35-1, the output port 51-6 corresponds to the output port 36-1, and the output port 51-7 corresponds to the output port 37-1.

The switching SW unit 52 has three input ports 52-1, 52-2, and 52-3 and one output port 52-5. Input port 52-1 is connected to output port 51-5 of the column-direction scanning matrix circuit 51, input port 52-2 is connected to output port 51-6, and input port 52-3 is connected to output port 51-7.

The switching SW unit 52 receives an operation by the user to specify a desired direction, selects one of the input ports 52-1, 52-2, 52-3 corresponding to the specified desired direction, and connects the selected one of the input ports 52-1, 52-2, 52-3 to the output port 52-5.

Each of the input ports 52-1, 52-2, and 52-3 of the switching SW unit 52 is pre-assigned to three column direction components in the direction of each of the beams 90-1 to 90-9. Here, as mentioned above, the column direction is the horizontal direction, so the column direction components are also horizontal direction components.

Input port 52-1 is pre-assigned to the "rightward" direction, which is the column component of the direction of beams 90-1, 90-4, and 90-7. Input port 52-2 is pre-assigned to the "middle" direction, which is the column component of the direction of beams 90-2, 90-5, and 90-8. Input port 52-3 is pre-assigned to the "leftward" direction, which is the column component of the direction of beams 90-3, 90-6, and 90-9.

(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 description will be given assuming that the user's desired direction is the direction of the beam 90-1 formed in the upper right direction.

Beam 90-1 is formed in the upper right direction relative to the plane of array antenna 80. The row component of the upper right direction is "upward," and the column component is "rightward." Therefore, when the user operates switching SW unit 25-1 to specify the desired direction of beam 90-1, switching SW unit 25-1 connects input port 41-1, which corresponds to the "upward" row component of beam 90-1, to output port 45-1. The user then performs similar operations on switching SW units 25-2 and 25-3. As a result, switching SW unit 25-2 connects input port 41-2 to output port 45-2, and switching SW unit 25-3 connects input port 41-3 to output port 45-3.

When the user operates the switching SW unit 52 to specify the desired direction of beam 90-1, the switching SW unit 52 connects the input port 52-1 corresponding to the column direction component "rightward" of beam 90-1 to the output port 52-5 (S1).

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 powering the received 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 supplied to it by light source 5 with the RF signal supplied to it by antenna elements 80-1-1 to 80-3-3.

Here, the optical signal generated by light source 5 can be expressed as an equation, for example, as follows:

In equation (1), ω _C is the angular frequency of the optical signal generated by the light source 5, 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).

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

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

Note that "A" in equations (3) and (4) is the amplitude value of the sideband of the modulated optical signal. The row-direction phase tilt of beam 90-1 is "φ _V ." Therefore, in the case of an arriving 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, lags in phase by φ _V behind the RF signal obtained from antenna element 80-1-1. Therefore, the RF signal supplied by antenna element 80-2-1 to optical modulator 11-2-1 can be expressed as the following equation (5), as an RF signal whose phase lags by φ _V behind the RF signal expressed by equation (2).

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

The RF signal supplied from the antenna element 80-3-1 to the optical modulator 11-3-1 is further delayed in phase by φ _V from the RF signal supplied from the antenna element 80-2-1 to the optical modulator 11-2-1. Therefore, the output optical signal output from the optical modulator 11-3-1 is expressed by the following equation (7).

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).

As a result, the USB components of the three modulated optical signals expressed by equations (4), (6), and (7) 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, 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 are in phase, and the signal intensity increases due to in-phase combining. The row-direction combined optical signal obtained by combining the three optical signals output from the output port 35-1 is expressed, for example, by the following equation (8).

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 is also referred to as the "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 are not in phase. Therefore, the signal intensity of the row-direction combined optical signal output from each of output ports 36-1 and 37-1 by row-direction scanning matrix circuit 21-1 is smaller than the signal intensity of the in-phase combined row-direction combined optical signal output from output port 35-1, because it is not in-phase combined.

The phase difference occurring between the RF signals obtained from each of 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 each of 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 each of 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-directional 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-directional scanning matrix circuit 21-3 are (0, −φ _V , −2φ _V ), the same as in the case of the row-directional scanning matrix circuit 21-1.

As a result, the row-direction combined optical signals output from the output ports 35-2 and 35-3 of the row-direction scanning matrix circuits 21-2 and 21-3 are in-phase combined row-direction optical signals. In contrast, the row-direction combined optical signals output from the output ports 36-2 and 37-2 of the row-direction scanning matrix circuits 21-2 and 21-3 are not in-phase combined row-direction optical signals.

Each of the row-direction scanning matrix circuits 21-1, 21-2, and 21-3 outputs a row-direction combined optical signal from its respective output ports 35-1 to 37-1, 35-2 to 37-2, and 35-3 to 37-3 (S3).

As described above, the column-direction phase tilt of beam 90-1 is "φ _H ". Therefore, the RF signal of antenna element 80-1-2 in the second column lags in phase by φ _H behind the RF signal of antenna element 80-1-1 in the first column, which is in the same row and adjacent in the column direction. Similarly, the RF signal of antenna element 80-2-2 in the second column lags in phase by φ _H behind the RF signal of antenna element 80-2-1 in the first column, which is in the same row and adjacent in the column direction. The RF signal of 80-3-2 in the second column lags in phase by φ _H behind the RF signal of antenna element 80-3-1 in the first column, which is in the same row and adjacent in the column direction.

Therefore, the in-phase combined row-direction optical signal output from the output port 35-2 by the row-direction scanning matrix circuit 21-2 is delayed in phase by _φH from the in-phase combined row-direction optical signal output from the output port 35-1 by the row-direction scanning matrix circuit 21-1, and is expressed by the following equation (9).

The antenna elements 80-1-3, 80-2-3, and 80-3-3 in the third column are further delayed by _φH compared to the antenna elements 80-1-2, 80-2-2, and 80-3-2 in the second column. Therefore, the in-phase row-direction combined optical signal output from the output port 35-3 by the row-direction scanning matrix circuit 21-3 is expressed by the following equation (10).

By processing S1, the output ports 45-1, 45-2, and 45-3 of the switching SW units 25-1, 25-2, and 25-3 are connected to the input ports 41-1, 41-2, and 41-3, respectively. Therefore, the switching SW unit 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. In contrast, the switching SW 25-1 discards the row-direction combined optical signal output from the output ports 36-1 and 37-1 of the row-direction scanning matrix circuit 21-1 because the input ports 42-1 and 43-1 are not connected to the output port 45-1.

The switching SW unit 25-2 outputs the row-direction combined optical signal expressed by equation (9) output from the output port 35-2 by the row-direction scanning matrix circuit 21-2 to the input port 51-2 of the column-direction scanning matrix circuit. In contrast, the switching SW 25-2 discards the row-direction combined optical signal output from the output ports 36-2 and 37-2 by the row-direction scanning matrix circuit 21-2 because the input ports 42-2 and 43-2 are not connected to the output port 45-2.

The switching SW unit 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. In contrast, since the input ports 42-3 and 43-3 are not connected to the output port 45-3, the switching SW 25-3 discards the row-direction combined optical signal output from the output ports 36-3 and 37-3 of the row-direction scanning matrix circuit 21-3 (S4).

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 (0, -φ _H , -2φ _H ) from equations (8), (9), and (10). 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 51-5 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).

In equation (11), "C" is the amplitude value of the column-directional combined optical signal generated by in-phase combining (hereinafter, the column-directional combined optical signal generated by in-phase combining will also be referred to as the "in-phase combined column-directional combined optical signal"). Note that, in the case of an incoming wave from the direction of beam 90-1, the three optical signals contained in the column-directional combined optical signal output from each of output ports 51-6 and 51-7 by the column-directional scanning matrix circuit 51 will not be in phase. Therefore, the signal intensity of the column-directional combined optical signal output from each of output ports 51-6 and 51-7 by the column-directional scanning matrix circuit 51 will be lower than the signal intensity of the in-phase combined column-directional combined optical signal output from output port 51-5. The column-directional scanning matrix circuit 51 outputs the column-directional combined optical signal from each of output ports 51-5, 51-6, and 51-7 (S5).

By processing S1, output port 52-5 is connected to input port 52-1 in the switching SW unit 52. Therefore, the switching SW unit 52 outputs the row-direction combined optical signal expressed by equation (11) output from output port 51-5 by the column-direction scanning matrix circuit 51 from output port 51-5. In contrast, because input ports 52-2 and 52-3 are not connected to output port 52-5, the switching SW unit 52 discards the column-direction combined optical signals output from output ports 51-6 and 51-7 by the column-direction scanning matrix circuit 51 (S6), and processing ends.

The column-direction combined optical signal output from output port 52-5 by switching SW unit 52 becomes the received signal corresponding to the incoming wave arriving from the direction of beam 90-1. As described above, this received signal is a combination of in-phase optical signals, resulting in a high signal strength. Therefore, for example, by connecting a device that performs demodulation processing to reception directivity control device 1 and capturing and demodulating this received signal, it becomes possible to obtain data superimposed on the received signal.

When the connection state in switching SW units 25-1, 25-2, 25-3, and 52 is set to a connection state in which the direction of beam 90-1 is the desired direction, suppose that an incoming wave arrives from the direction of beams 90-2 to 90-9 other than the direction of beam 90-1.

In this case, the in-phase combined row-direction optical signals corresponding to the waves arriving from the directions of beams 90-4, 90-5, 90-6, 90-7, 90-8, and 90-9, which correspond to the row-direction components "middle direction" and "downward direction," are discarded by switching SW units 25-1, 25-2, and 25-3. This is because, when the direction of beam 90-1 is the desired direction, only the input ports 41-1, 41-2, and 41-3 are connected to the output ports 45-1, 45-2, and 45-3 in switching SW units 25-1, 25-2, and 25-3, respectively.

In contrast, in-phase combined row-direction optical signals corresponding to waves arriving from the direction of beams 90-2 and 90-3, which correspond to the row-direction component "upward," are output from output ports 35-1, 35-2, and 35-3 of row-direction scanning matrix circuits 21-1, 21-2, and 21-3. The row-direction combined optical signals output from output ports 35-1, 35-2, and 35-3 are then supplied to input ports 51-1, 51-2, and 51-3 of column-direction scanning matrix circuit 51 via switching SW units 25-1, 25-2, and 25-3.

The in-phase combined column-direction combined optical signal corresponding to the wave arriving from the direction of beam 90-2 is output from output port 51-6 of the column-direction scanning matrix circuit 51, and the in-phase combined column-direction combined optical signal corresponding to the wave arriving from the direction of beam 90-3 is output from output port 51-7. However, input ports 52-2 and 52-3 of the switching SW unit 52 are not connected to output port 52-5. Therefore, the in-phase combined column-direction combined optical signal corresponding to the wave arriving from the direction of beams 90-2 and 90-3 is discarded by the switching SW unit 52.

In this case, the column-direction scanning matrix circuit 51 outputs from output port 51-5 an in-phase combined column-direction optical signal, which is the received signal corresponding to the wave arriving from the direction of beam 90-1, and a non-in-phase combined column-direction optical signal corresponding to the wave arriving from the direction of beams 90-2 and 90-3. Therefore, the optical signal output from output port 52-5 of the switching SW unit 52 includes three column-direction combined optical signals. However, because the signal strength of the column-direction combined optical signals corresponding to the wave arriving from the direction of beams 90-2 and 90-3 is not in-phase combined, it is smaller than the signal strength of the in-phase combined column-direction optical signal corresponding to the wave arriving from the direction of beam 90-1, and does not have the signal strength required for demodulation processing. Therefore, the column-direction combined optical signals corresponding to the wave arriving from the direction of beams 90-2 and 90-3 are not demodulated, and only the received signal corresponding to the wave arriving from the direction of beam 90-1 is demodulated.

If the user specifies one of the directions of beams 90-2 to 90-9 other than beam 90-1 as the desired direction in processing S1, the same processing is performed as when the direction of beam 90-1 is specified as the desired direction. As a result, only the received signal corresponding to the incoming wave from the direction specified as the desired direction is output from output port 52-5 of switching SW unit 52.

(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 in which beams 90-1 to 90-9 are formed. Here, the phases of the row direction components in the beam forming direction, in the above example, are 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."

The row direction scanning unit 20 generates row direction optical signals corresponding to each row direction component of the beam formation direction through a predetermined row direction phase scanning process. The row direction scanning unit 20 selects a row direction composite optical signal corresponding to the row direction component of the beam formation direction that matches the specified desired direction and outputs it to the column direction scanning unit 50.

The column direction scanning unit 50 performs a predetermined column direction phase scanning process on each of the row direction combined optical signals output by the row direction scanning unit 20, applying a phase gradient that aligns the phase of each column direction component in the beam formation direction, taking into account the difference in the position of each 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 refers to, 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."

The column direction scanning unit 50 performs a predetermined column direction phase scanning process to generate column direction combined optical signals corresponding to each column direction component of the beam formation direction. The column direction scanning unit 50 selects and outputs column direction combined optical signals corresponding to the column direction component of the beam formation direction that matches the specified desired direction. This allows only received signals of incoming waves arriving from the specified desired direction to be obtained.

The array antenna 80 connected to the reception directivity control device 1 shown in Figure 1 is a 3x3 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 it equals 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 in accordance with 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, 21-3 and the column direction scanning matrix circuit 51, a configuration change is required to increase or decrease the logic that imparts a phase gradient in accordance with the increase or decrease in the number of ports.

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 impart the gradient using a single column-direction scanning matrix circuit 51, thereby reducing the circuit size. Therefore, even if the number of antenna elements in the reception directivity control device 1 is increased, only the above-described configuration change is made, and the size of the circuit that imparts the phase gradient does not increase significantly, as in Patent Documents 1 and 2.

In the reception directivity control device 1, the circuit configuration other than the optical modulators 11-1-1 to 11-3-3 is connected via optical lines, so it can be configured in a planar manner rather than a three-dimensional configuration like the technologies disclosed in Patent Documents 1 and 2. Even if the number of antenna elements in the array antenna 80 increases, the expansion is limited to a planar manner. Therefore, even if the number of antenna elements is increased, the number of components and wiring in the reception directivity control device 1 does not increase significantly, and the circuit structure does not become more complex.

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.

Second Embodiment
5 is a block diagram showing the internal configuration of the reception directivity control device 1a of the second embodiment and the array antenna 80 connected to the reception directivity control device 1a. Note that in the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals.

In the reception directivity control device 1 of the first embodiment, the user was required to specify one of the directions of beams 90-1 to 90-9 as the desired direction. In contrast, in the reception directivity control device 1a of the second embodiment, the user is allowed to specify multiple directions from the directions of beams 90-1 to 90-9 as the desired direction.

The reception directivity control device 1a includes an electro-optical conversion unit 10, a row direction scanning unit 20a, and a column direction scanning unit 50a. The row direction scanning unit 20a includes row direction scanning matrix circuits 21-1, 21-2, and 21-3, and switching SW units 25a-1, 25a-2, and 25a-3.

Switching SW units 25a-1, 25a-2, and 25a-3 have the same configuration, and the following describes switching SW unit 25a-1 as an example. In the following description of switching SW unit 25a-1, the subnumber "-1" is replaced with "-2" to describe switching SW unit 25a-2, and the subnumber "-1" is replaced with "-3" to describe switching SW unit 25a-3.

The switching SW unit 25a-1 has three input ports 41-1, 42-1, and 43-1 and one output port 45-1. The connection relationship between each of the input ports 41-1, 42-1, and 43-1 and each of the output ports 35-1, 36-1, and 37-1 of the row-direction scanning matrix circuit 21-1 is the same as that of the switching SW unit 25-1 in the first embodiment.

The assignment of the three row direction components in the direction of beams 90-1 to 90-9 to each of input ports 41-1, 42-1, and 43-1 of the switching SW unit 25a-1 is the same as that of the switching SW unit 25-1 in the first embodiment. Therefore, the "upward direction" is assigned to input port 41-1, the "middle direction" is assigned to input port 42-1, and the "downward direction" is assigned to input port 43-1.

The switching SW unit 25a-1 receives an operation by the user to specify a desired direction, 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 SW unit 25a-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 SW unit 25a-1.

The column scanning unit 50a includes a column scanning matrix circuit 51 and a switching SW unit 52a. The switching SW unit 52a includes three input ports 52-1, 52-2, and 52-3 and three output ports 52-5, 52-6, and 52-7. The connection relationship between each of the input ports 52-1, 52-2, and 52-3 and each of the output ports 51-5, 51-6, and 51-7 of the column scanning matrix circuit 51 is the same as that of the switching SW unit 52 in the first embodiment.

The way in which the three column direction components in the direction of beams 90-1 to 90-9 are assigned to each of input ports 52-1, 52-2, and 52-3 of the switching SW unit 52a is the same as in the switching SW unit 52 of the first embodiment. Therefore, input port 52-1 is assigned "rightward," input port 52-2 is assigned "inner," and input port 52-3 is assigned "leftward."

The switching SW unit 52a allows the user to specify the output ports 52-5, 52-6, and 52-7 to be used. Each of the input ports 52-1, 52-2, and 52-3 can be connected to any one of the output ports 52-5, 52-6, and 52-7 that the user has specified for use. When each of the output ports 52-5, 52-6, and 52-7 is connected to any one of the input ports 52-1, 52-2, and 52-3, it cannot be connected to any input port 52-1, 52-2, or 52-3 other than the one it is connected to. Therefore, the connections between each of the input ports 52-1, 52-2, and 52-3 and each of the output ports 52-5, 52-6, and 52-7 are one-to-one connections.

The switching SW unit 52a receives an operation by the user specifying a desired direction and selects an input port 52-1, 52-2, or 52-3 corresponding to the desired direction. The switching SW unit 52a connects the selected input port 52-1, 52-2, or 52-3 to an available output port among the output ports 52-5, 52-6, or 52-7 that the user has specified for use. Here, an available output port refers to a state in which none of the input ports 52-1, 52-2, or 52-3 are connected.

(Processing by the receiving directivity control device of the second embodiment)
The flow of processing by the reception directivity control device 1a of the second embodiment will be described with reference to the flowchart showing the flow of processing by the reception directivity control device 1 of the first embodiment shown in Fig. 4. Below, a case where the user's desired direction is two directions, the direction of beam 90-1 formed in the upper right direction and the direction of beam 90-9 formed in the lower left direction, and a case where the user's desired direction is three directions, the direction of beam 90-3 formed in the upper left direction, beam 90-5 formed in the center direction, and beam 90-7 formed in the lower right direction will be described.

(When the desired direction is the direction of beams 90-1 and 90-9)
The row component of beam 90-1 is "upward" and the column component is "rightward." The row component of beam 90-9 is "downward" and the column component is "leftward." Therefore, when the user operates switching SW unit 25a-1 to specify the direction of beam 90-1 as the desired direction, switching SW unit 25a-1 connects input port 41-1, which corresponds to the "upward" row component of beam 90-1, to output port 45-1. When the user operates switching SW unit 25a-1 to further specify the direction of beam 90-9 as the desired direction, switching SW unit 25a-1 connects input port 43-1, which corresponds to the "downward" row component of beam 90-9, to output port 45-1.

The user performs the same operation on switching SW units 25a-2 and 25a-3. As a result, switching SW unit 25a-2 connects input ports 41-2 and 43-2 to output port 45-2. Switching SW unit 25a-3 connects input ports 41-3 and 43-3 to output port 45-3. As a result, the connection states of switching SW units 25a-1, 25a-2, and 25a-3 become as shown in Figure 5.

Let's say the user operates the switching SW unit 52a to specify the desired direction of beams 90-1 and 90-9, and to specify output ports 52-5 and 52-6 as the output ports to be used. In this case, the switching SW unit 52a connects, for example, input port 52-1, which corresponds to the "rightward" column component of the direction of beam 90-1, to output port 52-5, which is one of the output ports to be used. The switching SW unit 52a connects input port 52-3, which corresponds to the "leftward" column component of the direction of beam 90-9, to output port 52-6, which is the other output port to be used. As a result, the connection state of the switching SW unit 52 becomes as shown in FIG. 5 (S1).

(Processing in the case of an incoming wave from the direction of beam 90-1)
As described above, in each of the switching SW units 25a-1, 25a-2, and 25a-3, the input ports 41-1, 41-2, and 41-3 are connected to the output ports 45-1, 45-2, and 45-3, respectively. Therefore, the processing from S2 to S5 corresponding to the wave arriving from the direction of the beam 90-1 is the same as the processing described in the first embodiment, except that the switching SW units 25-1, 25-2, and 25-3 are replaced with switching SW units 25a-1, 25a-2, and 25a-3, respectively.

Therefore, 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 beam 90-1 from output port 51-5. The switching SW unit 52a inputs the column-direction combined optical signal output from output port 51-5 at input port 52-1, and outputs the incorporated column-direction combined optical signal from output port 52-5 (S6). This column-direction combined optical signal output from output port 52-5 becomes the received signal of the wave arriving from the direction of beam 90-1.

(Processing in the case of an incoming wave from the direction of beam 90-9)
As described above, the row-direction phase tilt of beam 90-9 is "-φ _V ". Therefore, in the case of an arriving wave from the direction of beam 90-9, the RF signal obtained from antenna element 80-2-1, which is in the same column as antenna element 80-3-1 and adjacent in the row direction, lags in phase by φ _V from the RF signal obtained from antenna element 80-3-1. The RF signal obtained from antenna element 80-1-1 lags in phase by an additional φ _V from the RF signal obtained from antenna element 80-2-1. Therefore, the phase difference of the USB components of the modulated optical signals modulated and output by each of optical modulators 11-1-1, 11-2-1, and 11-3-1 is (-2φ _V , -φ _V , 0). Similarly, the phase difference of the USB components of the modulated optical signals output by each of 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 each of 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).

Therefore, the phase difference between the USB components of the modulated optical signals supplied to input ports 31-1, 32-1, and 33-1 of row-directional scanning matrix circuit 21-1, the phase difference between the USB components of the modulated optical signals supplied to input ports 31-2, 32-2, and 33-2 of row-directional scanning matrix circuit 21-2, and the phase difference between the USB components of the modulated optical signals supplied to input ports 31-3, 32-3, and 33-3 of row-directional scanning matrix circuit 21-3 are (-2φ _V , -φ _V , 0). Therefore, when row-directional scanning matrix circuits 21-1, 21-2, and 21-3 perform a predetermined row-directional 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 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 row-direction combined optical signal corresponding to the wave arriving from the direction of the beam 90-9 from each of the output ports 37-1, 37-2, and 37-3 (S3).

As explained in the processing of S1, in each of the switching SW units 25a-1, 25a-2, and 25a-3, the input ports 43-1, 43-2, and 43-3 are connected to the output ports 45-1, 45-2, and 45-3, respectively. Therefore, each of the switching SW units 25a-1, 25a-2, and 25a-3 receives the row-direction combined optical signals output from the output ports 37-1, 37-2, and 37-3 at its input port 43-1, 43-2, and 43-3, and outputs the received row-direction combined optical signals from the output ports 45-1, 45-2, and 45-3 (S4).

As described above, the column direction phase tilt of beam 90-9 is "-φ _H ". Therefore, the RF signal obtained from antenna element 80-1-2 in the second column, which is in the same row as antenna element 80-1-3 in the first row and adjacent in the column direction, lags in phase by φ _H behind the RF signal obtained from antenna element 80-1-3. The RF signal obtained from antenna element 80-1-1 lags in phase by an additional φ _H behind the RF signal obtained from antenna element 80-1-2. Therefore, the phase difference between the RF signals obtained from each of antenna elements 80-1-1, 80-1-2, 80-1-3 in the first row is (-2φ _H , -φ _H , 0). Similarly, the phase difference between the RF signals obtained from the antenna elements 80-2-1, 80-2-2, and 80-2-3 in the second row and the phase difference between the RF signals obtained from the antenna elements 80-3-1, 80-3-2, and 80-3-3 in the third row are (-2φ _H , -φ _H , 0).

Therefore, the phase difference between the in-phase combined row-direction optical signals corresponding to the waves arriving from the direction of beam 90-9 and supplied to each of 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. Therefore, the column-direction scanning matrix circuit 51 outputs, from the output port 51-7, an in-phase combined column-direction optical signal corresponding to the waves arriving from the direction of beam 90-9 (S5).

The switching SW unit 52a receives the column-directional combined optical signal output from the output port 51-7 at the input port 52-3 and outputs the received column-directional combined optical signal from the output port 52-6 (S6). This column-directional combined optical signal output from the output port 52-6 becomes the received signal of the incoming wave coming from the direction of the beam 90-9.

(When the desired direction is the direction of beams 90-3, 90-5, and 90-7)
The row component of beam 90-3 is "upward" and the column component is "leftward." The row component of beam 90-5 is "center" and the column component is "center." The row component of beam 90-7 is "downward" and the column component is "rightward." Therefore, when the user operates the switching SW unit 25a-1 to specify the desired directions of beams 90-3, 90-5, and 90-7, the switching SW unit 25a-1 connects the input port 41-1 corresponding to the row component "upward," the input port 42-1 corresponding to the row component "center," and the input port 43-1 corresponding to the row component "downward" to the output port 45-1. In other words, the switching SW unit 25a-1 connects all of the input ports 41-1, 42-1, and 43-1 to the output port 45-1.

The user performs the same operation on switching SW units 25a-2 and 25a-3. As a result, switching SW unit 25a-2 connects all input ports 41-2, 42-2, and 43-2 to output port 45-2. Switching SW unit 25a-3 connects all input ports 41-3, 42-3, and 43-3 to output port 45-3.

Let's say the user operates the switching SW unit 52a to specify the desired direction of beams 90-3, 90-5, and 90-7, and to specify output ports 52-5, 52-6, and 52-7 as the output ports to be used. In this case, the switching SW unit 52a connects, for example, input port 52-1, which corresponds to the "rightward" column component of the direction of beam 90-7, to output port 52-5, which is one of the output ports to be used. The switching SW unit 52a connects input port 52-2, which corresponds to the "centerward" column component of the direction of beam 90-5, to output port 52-6, which is one of the output ports to be used. The switching SW unit 52a connects input port 52-3, which corresponds to the "leftward" column component of the direction of beam 90-3, to output port 52-7, which is one of the output ports to be used (S1).

(Processing in the case of an incoming wave from the direction of beam 90-3)
The row component of beam 90-3 is "upward." Therefore, the processing from S2 to S4 corresponding to the wave arriving from the direction of beam 90-3 is the same as the processing from S2 to S4 corresponding to the wave arriving from the direction of beam 90-1 described above. The column component of beam 90-3 is "leftward." Therefore, the processing from S5 corresponding to the wave arriving from the direction of beam 90-3 is the same as the processing from S5 corresponding to the wave arriving from the direction of beam 90-9 described above.

As a result, 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 beam 90-3 from output port 51-7. The switching SW unit 52a, at input port 52-3, accepts the column-direction combined optical signal output from output port 51-7 and outputs the accepted column-direction combined optical signal from output port 52-7 (S6). This column-direction combined optical signal output from output port 52-7 becomes the received signal of the wave arriving from the direction of beam 90-3.

(Processing in the case of an incoming wave from the direction of beam 90-5)
The row-direction phase tilt of beam 90-5 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).

Therefore, the phase difference between 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 between 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 between 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 modulated optical signals supplied, the USB components of the modulated optical signals are in 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 90-5 from each of the output ports 36-1, 36-2, and 36-3 (S3).

In each of the switching SW units 25a-1, 25a-2, and 25a-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 SW units 25a-1, 25a-2, and 25a-3 outputs the row-direction combined optical signals output from the output ports 36-1, 36-2, and 36-3 to the input ports 51-1, 51-2, and 51-3 of the column-direction scanning matrix circuit 51, respectively (S4).

The column-direction phase tilt of beam 90-5 is "0." Therefore, the phase difference of the row-direction combined optical signals supplied to 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 supplied row-direction combined optical signals, the row-direction combined optical signals become in-phase at output port 51-6. 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 beam 90-5 from output port 51-6 (S5).

The switching SW unit 52a receives the column-directional combined optical signal output from the output port 51-6 at the input port 52-2 and outputs the received column-directional combined optical signal from the output port 52-6 (S6). This column-directional combined optical signal output from the output port 52-6 becomes the received signal of the incoming wave coming from the direction of the beam 90-5.

(Processing in the case of an incoming wave from the direction of beam 90-7)
The row component of beam 90-7 is "downward." Therefore, the processing from S2 to S4 corresponding to the wave arriving from the direction of beam 90-7 is the same as the processing from S2 to S4 corresponding to the wave arriving from the direction of beam 90-9 described above. The column component of beam 90-7 is "rightward." Therefore, the processing from S5 corresponding to the wave arriving from the direction of beam 90-7 is the same as the processing from S5 corresponding to the wave arriving from the direction of beam 90-1 described above.

As a result, 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 beam 90-7 from output port 51-5. The switching SW unit 52a inputs the column-direction combined optical signal output from output port 51-5 at input port 52-1, and outputs the combined column-direction combined optical signal from output port 52-5 (S6). This column-direction combined optical signal output from output port 52-5 becomes the received signal of the wave arriving from the direction of beam 90-7.

As a result, received signals corresponding to waves arriving from the directions of beams 90-3, 90-5, and 90-7 are obtained in parallel from output ports 52-7, 52-6, and 52-5 of switching SW unit 52a, respectively. As can be seen from these two examples, reception directivity control device 1a can obtain, in parallel, received signals of waves arriving from two or three of the directions of beams 90-1 to 90-9. However, reception directivity control device 1a cannot separate and receive waves arriving from any two or three of the directions of beams 90-1 to 90-9.

The directions of beams 90-1 to 90-9 that the reception directivity control device 1a can specify as multiple beams are limited to those in which the incoming waves arrive from directions with different horizontal components among the directions of beams 90-1 to 90-9. This is because, when incoming waves with the same horizontal component exist, in-phase combined column-direction optical signals corresponding to the multiple incoming waves are mixed together at any of output ports 51-5, 51-6, and 51-7 of the column-direction scanning matrix circuit 51, making it impossible to separate them.

Here, when an incoming wave arrives from a direction with a different horizontal component among the directions of beams 90-1 to 90-9, it means that the wave arrives from any two or three of the following three directions: any one of the "rightward" beams 90-1, 90-4, and 90-7; any one of the "middle" beams 90-2, 90-5, and 90-8; and any one of the "leftward" beams 90-3, 90-6, and 90-9.

Therefore, when using the receiving directivity control device 1a to receive incoming waves coming from the directions of beams 90-1 to 90-9 in parallel from two or three directions, it is necessary to install the receiving directivity control device 1a so that in the coordinate system of the row axis and column axis of the array antenna 80 connected to the receiving directivity control device 1a, the column component of the direction of the arriving waves is in a different direction.

(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 1a shown in Fig. 5. However, even if the horizontal component is the same, when 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 in parallel by using the reception directivity control device 1b according to another configuration example (part 1) of the second embodiment shown in Fig. 6.

Here, when an incoming wave arrives from a direction with a different vertical component among the directions of beams 90-1 to 90-9, it means that the wave arrives from any two or three of the following three directions: 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.

As shown in FIG. 6, the reception directivity control device 1b comprises 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 user operation. When the shaft 112 receives power from the rotation mechanism 111, it rotates around its central axis.

The main body 110 is, for example, the receiving directivity control device 1a shown in Figure 5. When the rotation mechanism 111 rotates the shaft 112, the shaft 112 rotates around its central axis, and in conjunction with this rotation, the main body 110 and the array antenna 80 connected to the main body 110 rotate. For example, assume a three-dimensional coordinate system in which the row axis on the plane of the array antenna 80 is the X-axis, the column axis is the Y-axis, and a line perpendicular to the plane of the array antenna 80 is the Z-axis. In this three-dimensional coordinate system, the plane of the array antenna 80 rotates while maintaining its position on the Z-axis and maintaining an orthogonal relationship between the X-axis and Y-axis.

When the plane of the array antenna 80 is rotated 90 degrees using the receiving directivity control device 1b shown in Figure 6, the row direction becomes horizontal and the column direction becomes vertical, as in the array antenna 80a shown in Figure 6. Beams 90-1 to 90-9 formed in the case of the array antenna 80 will rotate along with the array antenna 80, but here, the nine directional beams formed in the arrangement of the array antenna 80a are newly assigned the symbols 90-1 to 90-9, and the directions of beams 90-1 to 90-9 in the state of the array antenna 80a will be the directions shown in Figure 3.

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 1a of Figure 5 is used with the arrangement of array antenna 80a, the USB components of the modulated optical signals corresponding to the RF signals supplied by the horizontally arranged antenna elements 80-1-1, 80-2-1, and 80-3-1 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 the modulated optical signals corresponding to the RF signals supplied by the horizontally arranged antenna elements 80-1-2, 80-2-2, and 80-3-2 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.

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

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.

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

When using the reception directivity control device 1b, if incoming waves are arriving from directions with different horizontal components among the beams 90-1 to 90-9, the directional components extracted from the output ports 51-5, 51-6, and 51-7 of the column direction scanning matrix circuit 51 must be horizontal components of "rightward," "inward," or "leftward." Therefore, the column direction must be aligned with the horizontal direction, which is why the array antenna 80 must be positioned accordingly.

In contrast, if the incoming waves are coming from directions with different vertical components among the directions of beams 90-1 to 90-9, the directional components extracted at output ports 51-5, 51-6, and 51-7 of column-direction scanning matrix circuit 51 must be vertical components: "upward," "inward," and "downward." Therefore, the column direction must be aligned with the vertical direction, which is why array antenna 80a must be positioned accordingly.

Therefore, by rotating the plane of the 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 the array antenna 80, it becomes possible to separate and obtain the received signals of all the incoming waves in parallel.

In this case, when using the reception directivity control device 1a with the array antenna 80a positioned after being rotated 90 degrees, the row direction becomes horizontal and the column direction becomes vertical. Therefore, the user should note that input ports 41-1, 41-2, and 41-3 of switching SW units 25-1, 25-2, and 25-3 are assigned to face left, input ports 42-1, 42-2, and 42-3 are assigned to face center, and input ports 43-1, 43-2, and 43-3 are assigned to face right. It should also be noted that input ports 52-1, 52-2, and 52-3 of switching SW unit 52a are assigned to face up, center, and down, respectively.

In Figure 7, the entire main body 110 is rotated, but it is also possible to rotate only the portion of the electro-optical conversion unit 10, which is preferably located near the antenna elements 80-1-1 to 80-3-3, together with the antenna elements 80-1-1 to 80-3-3.

(Another configuration example (part 2) of the second embodiment)
7 is a diagram showing the internal configuration of a reception directivity control device 1c according to another configuration example (part 2) of the second embodiment, and an array antenna 80 connected to the reception directivity control device 1c. The reception directivity control device 1c has the same configuration as the reception directivity control device 1a shown in FIG. 5, and further includes a matrix rearrangement unit 15. The matrix rearrangement unit 15 includes SW circuits 15-1 to 15-6.

The SW circuit 15-1 is connected on the input side to the optical modulator 11-2-1, and on the output side to the input port 32-1 of the row direction scanning matrix circuit 21-1 and the input port 31-2 of the row direction scanning matrix circuit 21-2. In the first switching state, the SW circuit 15-1 connects the input side to the input port 32-1, and in the second switching state, it connects the input side to the input port 31-2.

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

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

The SW circuit 15-4 is connected on the input side to the optical modulator 11-3-2, and on the output side 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 the first switching state, the SW circuit 15-4 connects the input side to the input port 33-2, and in the second switching state, it connects the input side to the input port 32-3.

The SW circuit 15-5 is connected on the input side to the optical modulator 11-1-3, and on the output side 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 the first switching state, the SW circuit 15-5 connects the input side to the input port 31-3, and in the second switching state, it connects the input side to the input port 33-1.

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

The matrix permutation unit 15 can be switched between a first switching state and a second switching state by user operation. Therefore, when incoming waves are arriving 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 as shown by the dashed lines. In this case, the reception directivity control device 1c performs the same processing on incoming waves received by antenna elements 80-1-1 to 80-3-3 of the array antenna 80 as the reception directivity control device 1a shown in FIG. 5 performs. As a result, when incoming waves are arriving from directions with different horizontal components among the beams 90-1 to 90-9, it is possible to separate the received signals for each incoming wave and obtain them in parallel.

In contrast, when incoming waves are coming from a direction with a different vertical component than the directions of beams 90-1 to 90-9, the user switches the state of the matrix interchange unit 15 to the second switching state. In this case, SW circuits 15-1 to 15-6 are connected to 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 optical modulators 11-1-1 to 11-3-3 are interchanged.

Therefore, the input ports 31-1, 32-1, and 33-1 of the row scanning matrix circuit 21-1 are supplied with the USB components of the 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 the USB components of the 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 the USB components of the 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.

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

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.

Therefore, in the reception directivity control device 1c, when incoming waves are arriving from directions with different vertical components among the directions of beams 90-1 to 90-9, by switching 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 row and column coordinate system of the array antenna 80. This makes it possible to separate the received signals for each incoming wave and obtain them in parallel.

The reception directivity control device 1c has the same number of antenna elements in the row direction as 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 by the optical modulators 11-1-1 to 11-3-3 without changing the configuration of the row direction scanning unit 20a and the column direction scanning unit 50a. When 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 a "rightward orientation," the output ports 36-1, 36-2, and 36-3 correspond to a "center orientation," and the output ports 37-1, 37-2, and 37-3 correspond to a "leftward orientation." This is the opposite of the arrangement of the array antenna 80a 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.

However, when using the reception directivity control device 1c in the second switching state, the rows and columns are swapped, so the user needs to note that input ports 41-1, 41-2, and 41-3 of switching SW units 25a-1, 25a-2, and 25a-3 are assigned to face right, input ports 42-1, 42-2, and 42-3 are assigned to face center, and input ports 43-1, 43-2, and 43-3 are assigned to face left. It should also be noted that input ports 52-1, 52-2, and 52-3 of switching SW unit 52a are assigned to face up, center, and down, respectively.

(Use scenarios of each configuration example of the second embodiment)
The following describes the application scenarios of each configuration example of the second embodiment with reference to the flowchart shown in Fig. 8. When it is assumed that only incoming waves from directions with different horizontal components exist among the directions of beams 90-1 to 90-9 (Sa1, Yes), by using the reception directivity control device 1a shown in Fig. 5, it is possible to obtain, in parallel, received signals corresponding to incoming waves from directions with different horizontal components (Sa3).

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

In this case, as shown in another configuration example (part 1) of the second embodiment in Figure 6, the reception directivity control device 1a, which is the main body 110, and the array antenna 80 are rotated 90 degrees by the rotation mechanism 111, so that the arrangement of antenna elements 80-1-1 to 80-3-3 included in the array antenna 80 is aligned with that of the array antenna 80a. This makes it possible to obtain, in parallel, received signals whose vertical components correspond to waves arriving from different directions (Sa4).

When using the reception directivity control device 1c of another configuration example (part 2) of the second embodiment shown in Figure 7, in the situation Sa3, if the matrix interchange unit 15 is used in the first switching state, it is possible to obtain in parallel reception signals corresponding to arrival waves from directions with different horizontal components in the directions of beams 90-1 to 90-9. In contrast, in the situation Sa4, if the matrix interchange unit 15 is used in the second switching state, it is possible to obtain in parallel reception signals corresponding to arrival waves from directions with different vertical components in the directions of beams 90-1 to 90-9.

Let's 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, the configuration examples of the second embodiment cannot separate and obtain the received signal corresponding to the incoming wave. Therefore, another means is required, such as using the reception directivity control device 1d shown in Figure 9 (Sa5).

The reception directivity control device 1d shown in Figure 9 will now be described. Note that in Figure 9, the same components as those in the first and second embodiments are given the same reference numerals. The reception directivity control device 1d comprises a light source 5, an electro-optical conversion unit 10, a row direction scanning unit 20b, and a column direction scanning unit 50b. The light source 5 has the same configuration as the light source 5 provided in the reception directivity control devices 1, 1a, and 1c, but in this description, the frequency of the optical signal generated by the light source 5 will be described as frequency ch1.

The connection relationship between the optical modulators 11-1-1 to 11-3-3 provided in the electro-optical conversion unit 10 and the antenna elements 80-1-1 to 80-3-3 of the array antenna 80 is the same as in the case of the receiving directivity control devices 1, 1a, and 1c.

The row direction scanning unit 20b has the same configuration as the row direction scanning unit 20a provided in the reception directivity control devices 1a and 1c, and further includes frequency converters 22-1, 22-2, and 22-3, and frequency converters 23-1 and 23-2. Frequency converter 22-1 is connected between the output port 36-1 of the row direction scanning matrix circuit 21-1 and the input port 42-1 of the switching SW unit 25a-1. Frequency converter 23-1 is connected between the output port 37-1 of the row direction scanning matrix circuit 21-1 and the input port 43-1 of the switching SW unit 25a-1.

The connection relationship between frequency converters 22-2 and 23-2, row-direction scanning matrix circuit 21-2, and switching SW unit 25a-2 is the same as the connection relationship between frequency converters 22-1 and 23-1 described above, except that the branch number "-1" included in the symbols is replaced with "-2." The connection relationship between frequency converters 22-3 and 23-3, row-direction scanning matrix circuit 21-3, and switching SW unit 25a-3 is the same as the connection relationship between frequency converters 22-1 and 23-1 described above, except that the branch number "-1" included in the symbols is replaced with "-3."

Frequency converters 22-1, 22-2, and 22-3 convert the supplied optical signal of frequency ch1 into an optical signal of frequency ch2, which is a frequency different from frequency ch1, and output the converted signal. Frequency converters 23-1, 23-2, and 23-3 convert the supplied optical signal of frequency ch1 into an optical signal of frequency ch3, which is a frequency different from frequencies ch1 and ch2, and output the converted signal.

The column direction scanning unit 50b comprises a column direction scanning matrix circuit 51 and splitters 53-1, 53-2, and 53-3.

The input side of the splitter 53-1 is connected to output port 51-5 of the column-directional scanning matrix circuit 51. The splitter 53-1 has output port 55-1 corresponding to frequency ch1, output port 56-1 corresponding to frequency ch2, and output port 57-1 corresponding to frequency ch3. The input side of the splitter 53-2 is connected to output port 51-6 of the column-directional scanning matrix circuit 51. The splitter 53-2 has output port 55-2 corresponding to frequency ch1, output port 56-2 corresponding to frequency ch2, and output port 57-2 corresponding to frequency ch3. The input side of the splitter 53-3 is connected to output port 51-7 of the column-directional scanning matrix circuit 51. The splitter 53-3 has output port 55-3 corresponding to frequency ch1, output port 56-3 corresponding to frequency ch2, and output port 57-3 corresponding to frequency ch3.

Each of the demultiplexers 53-1, 53-2, and 53-3 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.

By using the reception directivity control device 1d having the above-described configuration, the in-phase combined row-direction optical signal corresponding to the row-direction component "middle direction" is converted to frequency channel 2. The in-phase combined row-direction optical signal corresponding to the row-direction component "downward" is converted to frequency channel 3. As a result, the in-phase combined row-direction optical signals corresponding to the row-direction components "upward," "middle," and "downward" become optical signals of different frequencies.

Let us assume that an in-phase combined column-direction optical signal corresponding to a "rightward" column-direction component is obtained at output port 51-5 of column-direction scanning matrix circuit 51. In this case, demultiplexer 53-1 can separate the in-phase combined column-direction optical signal corresponding to the "rightward" column-direction component supplied from output port 51-5 into a "rightward" and "upward" column-direction combined optical signal, a "rightward" and "middle" column-direction combined optical signal, and a "rightward" and "downward" column-direction combined optical signal.

Let us assume that an in-phase combined column-direction optical signal corresponding to the "inward" column direction component is obtained at output port 51-6 of column-direction scanning matrix circuit 51. In this case, demultiplexer 53-2 can separate the in-phase combined column-direction optical signal corresponding to the "inward" column direction component supplied from output port 51-6 into a "inward" and "upward" column direction combined optical signal, a "inward" and "inward" column direction combined optical signal, and a "inward" and "downward" column direction combined optical signal.

Let us assume that an in-phase combined column-direction optical signal corresponding to a "leftward" column direction component is obtained at output port 51-7 of column-direction scanning matrix circuit 51. In this case, demultiplexer 53-3 can separate the in-phase combined column-direction optical signal corresponding to the supplied "leftward" column direction component into a "leftward" and "upward" column direction combined optical signal, a "leftward" and "middle" column direction combined optical signal, and a "leftward" and "downward" column direction combined optical signal.

Therefore, as shown in Figure 9, at output ports 55-1 to 57-1, 55-2 to 57-2, and 55-3 to 57-3 of splitters 53-1, 53-2, and 53-3, it is possible to separate and obtain in parallel the received signals corresponding to each of the arriving waves from the nine directions of beams 90-1 to 90-9.

(Another configuration example (part 3) of the second embodiment)
In the receiving directivity control device 1a shown in FIG. 5, 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 25a-1, 25a-2, and 25a-3 are connected to the respective output ports 45-1, 45-2, and 45-3, the switching SW units 25a-1, 25a-2, and 25a-3 function as multiplexers that multiplex row-direction combined optical signals.

In this case, for example, the reception directivity control device 1e shown in Figure 10 may be applied, in which the switching SW units 25a-1, 25a-2, and 25a-3 of the reception directivity control device 1a 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 ports 35-1, 36-1, and 37-1 of the row scanning matrix circuit 21-1. The output port of the multiplexer 26-1 is connected to the input port 51-1 of the column scanning matrix circuit 51.

In the above description of the connection configuration for multiplexer 26-1, the connection configuration for multiplexer 26-2 is obtained by replacing the branch number "-1" with "-2," and the connection configuration for multiplexer 26-3 is obtained by replacing the branch number "-1" with "-3." Each of multiplexers 26-1, 26-2, and 26-3 combines row-direction combined optical signals supplied from three input ports and outputs the combined combined optical signal from an output port.

In the case of the reception directivity control device 1e shown in Figure 10, the user cannot specify the desired direction as with the reception directivity control device 1a, but there is no need to operate the switching SW units 25a-1, 25a-2, and 25a-3 that are required with the reception directivity control device 1a.

In addition, in the reception directivity control device 1c shown in Figure 7, multiplexers 26-1, 26-2, and 26-3 may be applied instead of the switching SW units 25a-1, 25a-2, and 25a-3.

When multiplexers 26-1, 26-2, and 26-3 are used instead of switching SW units 25a-1 to 25a-3 as described above, a determination circuit may be provided in front of each input port of multiplexers 26-1, 26-2, and 26-3 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 processing by the column-direction scanning matrix circuit 51 in the subsequent stage.

(Effects of the second embodiment)
By using the reception directivity control devices 1a, 1b, 1c, and 1e, it is possible to obtain in parallel received signals of waves arriving from up to three directions, which are any of the directions of beams 90-1 to 90-9.

As in the first embodiment, the reception directivity control devices 1a, 1b, 1c, and 1e apply phase gradients using row-direction scanning matrix circuits 21-1, 21-2, and 21-3 and column-direction 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.

(Third embodiment)
In the first and second embodiments described above, examples were shown in which the antenna elements 80-1-1 to 80-3-3 in the array antenna 80 were arranged with three elements in the row direction and three elements in the column direction. In contrast, 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 designated by the same reference numerals.

(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 4x2 array antenna with eight antenna elements: four elements arranged along the row direction and two elements arranged along the column direction, totaling 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.

The arrangement will be explained in more detail. The antenna elements 80-1-1, 80-2-1, 80-3-1, and 80-4-1 in the first column are arranged at equal intervals so as to be parallel to the row axis. Similarly, the antenna elements 80-1-2, 80-2-2, 80-3-2, and 80-4-2 in the second column are arranged at equal intervals so as to be parallel to the row axis. The 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 80-1-2, 80-2-2, 80-3-2, and 80-4-2.

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 adjacent antenna elements 80-1-1 and 80-2-1 in the row direction and the distance between adjacent antenna elements 80-1-1 and 80-1-2 in the column direction may be the same or different lengths. Each of the antenna elements 80-1-1 to 80-4-2 receives an incoming wave and is thereby fed with an electrical RF signal.

The beams formed by the receiving directivity control device 1f in the array antenna 80b are beams 90-1 to 90-8 oriented in eight directions, as shown in Figure 13. When viewed through the plane of the array antenna 80b in the observation direction indicated by the arrow in Figure 12, i.e., from the side where the receiving 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.

Beam 90-3 points in a direction that is tilted to the right from a line perpendicular to the surface of array antenna 80b, and then tilted 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 that is tilted to the left from a line perpendicular to the surface of array antenna 80b, and then tilted 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").

Beam 90-5 points in a direction that is tilted to the right from a line perpendicular to the surface of array antenna 80b, and then tilted 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 that is tilted to the left from a line perpendicular to the surface of array antenna 80b, and then tilted 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").

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."

If the phase gradients caused by each of beams 90-1 to 90-8 are written in the form of (row-direction phase gradient, column-direction phase gradient), for example, beam 90-1 is (φ _V2 , φ _H ), beam 90-2 is (φ _V2 , −φ _H ), beam 90-3 is (φ _V1 , φ _H ), beam 90-4 is (φ _V1 , −φ _H ), beam 90-5 is (−φ _V1 , φ _H ), beam 90-6 is (−φ _V1 , −φ _H ), beam 90-7 is (−φ _V2 , φ _H ), and beam 90-8 is (−φ _V2 , −φ _H ), where φ _V2 > φ _V1 .

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

The electrical-to-optical conversion unit 10a has optical modulators 11-1-1 to 11-4-2 in a number that matches 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 its corresponding antenna element 80-1-1 to 80-4-2.

The row direction scanning unit 20d has circuit configurations in the same number as the number of columns of the array antenna 80b. The circuit configuration corresponding to the first column is the row direction scanning matrix circuit 21a-1 and switching SW unit 25b-1, which connect to the optical modulators 11-1-1, 11-2-1, 11-3-1, and 11-4-1 in the first column. The circuit configuration corresponding to the second column is the row direction scanning matrix circuit 21a-2 and switching SW unit 25b-2, which connect to the optical modulators 11-1-2, 11-2-2, 11-3-2, and 11-4-2 in the second column.

The two circuit configurations provided in the row direction scanning unit 20d are identical, and below, as an example, we will explain the circuit configuration corresponding to the first column, namely, the row direction scanning matrix circuit 21a-1 and the switching SW unit 25b-1. In the explanation of the circuit configuration corresponding to the first column below, the branch number "-1" in the reference numerals will be replaced with "-2" to explain the circuit configuration corresponding to the second column. However, in the explanation of the optical modulators 11-1-1, 11-2-1, 11-3-1, and 11-4-1 and the SW circuits 16-1-1, 16-2-1, and 16-3-1 provided in the switching SW unit 25b-1, the last branch number "-1" in the reference numerals will be replaced with "-2."

The row-direction scanning matrix circuit 21a-1 is a one-dimensional weighting circuit and has 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 the four optical modulators 11-1-1, 11-2-1, 11-3-1, and 11-4-1 in the first column. More specifically, optical modulator 11-1-1 is connected to input port 31-1, optical modulator 11-2-1 is connected to input port 32-1, optical modulator 11-3-1 is connected to input port 33-1, and optical modulator 11-4-1 is connected to input port 34-1.

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, these optical signals are referred to as row-direction combined optical signals). 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.

To explain the specified row-direction phase scanning process performed by the row-direction scanning matrix circuit 21a-1, assume 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.

Assume that an optical signal is supplied to output port 35-1 of row-direction scanning matrix circuit 21a-1. In this case, row-direction scanning matrix circuit 21a-1 outputs the optical signal supplied from output port 35-1 as is from input port 31-1, outputs an optical signal obtained by delaying the phase of the supplied optical signal _{by φV2} from input port 32-1, outputs an optical signal obtained by delaying the phase of the supplied optical signal _{by 2φV2} from input port 33-1, and outputs an optical signal obtained by delaying the phase of the supplied optical signal by _3φV2 from input port 34-1. Therefore, the phase differences of the optical signals output from input ports 31-1, 32-1, 33-1, and 34-1 are (0, _-φV2 , _-2φV2 , _-3φV2 ).

Assume that an optical signal is supplied to output port 36-1 of row-direction scanning matrix circuit 21a-1. In this case, row-direction scanning matrix circuit 21a-1 outputs the optical signal supplied from output port 36-1 as is from input port 31-1, outputs an optical signal obtained by delaying the phase of the supplied optical signal _{by φV1} from input port 32-1, outputs an optical signal obtained by delaying the phase of the supplied optical signal _{by 2φV1} from input port 33-1, and outputs an optical signal obtained by delaying the phase of the supplied optical signal by _3φV1 from input port 34-1. Therefore, the phase differences of the optical signals output from input ports 31-1, 32-1, 33-1, and 34-1 are (0, _-φV1 , _-2φV1 , _-3φV1 ).

Assume that an optical signal is supplied to output port 37-1 of row-direction scanning matrix circuit 21a-1. In this case, row-direction scanning matrix circuit 21a-1 outputs the optical signal supplied from output port 37-1 as is from input port 34-1, outputs an optical signal obtained by delaying the phase of the supplied optical signal _{by φV1} from input port 33-1, outputs an optical signal obtained by delaying the phase of the supplied optical signal _{by 2φV1} from input port 32-1, and outputs an optical signal obtained by delaying the phase of the supplied optical signal by _3φV1 from input port 31-1. Therefore, the phase differences of the optical signals output from input ports 31-1, 32-1, 33-1, and 34-1 are ( _-3φV1 , _-2φV1 , _-φV1 , 0).

Assume that an optical signal is supplied to output port 38-1 of row-direction scanning matrix circuit 21a-1. In this case, row-direction scanning matrix circuit 21a-1 outputs the optical signal supplied from output port 38-1 as is from input port 34-1, outputs an optical signal obtained by delaying the phase of the supplied optical signal _{by φV2} from input port 33-1, outputs an optical signal obtained by delaying the phase of the supplied optical signal _{by 2φV2} from input port 32-1, and outputs an optical signal obtained by delaying the phase of the supplied optical signal by _3φV2 from input port 31-1. Therefore, the phase differences of the optical signals output from input ports 31-1, 32-1, 33-1, and 34-1 are ( _-3φV2 , _-2φV2 , _-φV2 , 0).

Inversely to the above, 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 21a-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 is the predetermined row-direction phase scanning process performed by the row-direction scanning matrix circuit 21a-1.

Suppose four optical signals with phase differences of (0, -φ _V2 , -2φ _V2 , -3φ _V2 ) are supplied to each of input ports 31-1, 32-1, 33-1, and 34-1. In this case, of the row-direction combined optical signals generated for each of 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 35-1 will be in phase, and the four optical signals included in the row-direction combined optical signal corresponding to output ports 36-1, 37-1, and 38-1 will not be in phase.

Suppose four optical signals with phase differences of (0, −φ _V1 , −2φ _V1 , −3φ _V1 ) are supplied to each of input ports 31-1, 32-1, 33-1, and 34-1. In this case, of the row-direction combined optical signals generated for each of 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 signal corresponding to output ports 35-1, 37-1, and 38-1 will not be in phase.

Suppose four optical signals with phase differences of (-3φ _V1 , -2φ _V1 , -φ _V1 , 0) are supplied to each of input ports 31-1, 32-1, 33-1, and 34-1. In this case, of the row direction combined optical signals generated for each of 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 37-1 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 38-1 will not be in phase.

Suppose four optical signals with phase differences of (-3φ _V2 , -2φ _V2 , -φ _V2 , 0) are supplied to each of input ports 31-1, 32-1, 33-1, and 34-1. In this case, of the row direction combined optical signals generated for each of 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.

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

[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.]

As an example of a two-input, two-output directional coupler, consider a hybrid coupler that 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 that 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 that advance the phase by 45 degrees with four hybrid couplers, a four-input, four-output matrix circuit can be constructed that generates four phase gradients: 135 degrees, 45 degrees, -45 degrees, and -135 degrees. This matrix circuit can also be used with the inputs and outputs swapped, which will result in a phase change opposite to that described above.

In other words, if the row-direction scanning matrix circuit 21a-1 is implemented using a Butler matrix circuit, four directional couplers (hereinafter referred to as directional couplers) are required. Therefore, as shown in Figure 11, the row-direction scanning matrix circuit 21a-1 has four directional couplers 61-1, 62-1, 63-1, and 64-1 internally. Note that the directional couplers 61-1, 62-1, 63-1, and 64-1 all have the same configuration.

The switching SW unit 25b-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 operations to connect one of the two input ports to the respective output port, or to not connect both of the two input ports to the respective output port. The SW circuit 16-3-1 performs switching operations to connect one of the two input ports to the output port.

The two input ports of SW circuit 16-1-1 are input ports 41-1 and 42-1 of switching SW unit 25b-1, and the two input ports of SW circuit 16-2-1 are input ports 43-1 and 44-1 of switching SW unit 25b-1. The output port of SW circuit 16-3-1 is output port 45-1 of switching SW unit 25b-1. In this case, switching SW unit 25b-1 becomes a four-input, one-output switch with four input ports 41-1, 42-1, 43-1, and 44-1 overall and one output port 45-1, and connects one of the four input ports 41-1, 42-1, 43-1, and 44-1 to output port 45-1 in response to a user operation specifying the desired direction. The input ports 41-1, 42-1, 43-1, and 44-1 are connected to the output ports 35-1, 36-1, 37-1, and 38-1 of the row-direction scanning matrix circuit 21a-1, respectively.

The four input ports 44-1, 42-1, 43-1, and 44-1 of the switching SW unit 25b-1 are pre-assigned to the four row direction components of each of the beams 90-1 to 90-8. Here, as mentioned above, the row direction is the vertical direction, so the row direction components are also vertical direction components.

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.

The column scanning unit 50b comprises a column scanning matrix circuit 51a and a switching SW unit 52b. The column scanning matrix circuit 51a is a one-dimensional weighting circuit and comprises 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 SW unit 25b-1. The input port 51-2 is connected to the output port 45-2 of the switching SW unit 25b-2.

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, thereby generating 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 is 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.

The column-direction scanning matrix circuit 51a performs the following processing as a predetermined column-direction phase scanning processing. The column-direction scanning matrix circuit 51a outputs an optical signal supplied from an input port 51-1 directly from an output port 51-5, and outputs an optical signal with the phase of the optical signal advanced by _φH from an output port 51-6. The column-direction scanning matrix circuit 51a outputs an optical signal supplied from an input port 51-2 directly from an output port 51-6, and outputs an optical signal with the phase advanced by _φH from an output port 51-5.

As a result, when the phase difference between the optical signals supplied to each of the input ports 51-1 and 51-2 is (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.

When the column-direction scanning matrix circuit 51a is implemented using, for example, a Butler matrix circuit, it can be implemented using a single two-input, two-output hybrid coupler. Therefore, as shown in Figure 11, the column-direction scanning matrix circuit 51a includes a single square coupler 65.

The switching SW unit 52b includes a SW circuit 17. The SW circuit 17 has the same configuration as the SW circuit 16-3-1. One input port of the SW circuit 17 becomes the input port 52-1 of the switching SW unit 52b, the other input port of the SW circuit 17 becomes the input port 52-2 of the switching SW unit 52b, and the output port of the SW circuit 17 becomes the output port 52-5 of the switching SW unit 52b. In response to a user operation specifying the desired direction, the switching SW unit 52b connects one of the two input ports 51-1 and 52-2 to the output port 52-5. The input ports 52-1 and 52-2 are connected to the output ports 51-5 and 51-6 of the column-direction scanning matrix circuit 51a, respectively.

The two input ports 52-1 and 52-2 of the switching SW unit 52b are pre-assigned to two column direction components of each of the beams 90-1 to 90-8. Here, as mentioned above, the column direction is the horizontal direction, so the column direction components are horizontal components. Input port 52-1 is pre-assigned to the "rightward" direction, which is the column direction component of the directions of beams 90-1, 90-3, 90-5, and 90-7. Input port 52-2 is pre-assigned to the "leftward" direction, which is the column direction component of the directions of beams 90-2, 90-4, 90-6, and 90-8.

(Processing of the receiving directivity control device according to the configuration example (part 1) of the third embodiment)
When waves arriving from the direction of beams 90-1 and 90-2 corresponding to the "upward 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 _V2 , -2φ _V2 , -3φ _V2 ) in the order of rows 1, 2, 3, and 4. Therefore, the USB components of the modulated optical signals have the same phase at the output ports 35-1 and 35-2.

When waves arriving from the directions 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 _V1 , -2φ _V1 , -3φ _V1 ) in the order of rows 1, 2, 3, and 4. Therefore, the USB components of the modulated optical signals are in phase at the output ports 36-1 and 36-2.

When waves arriving from the direction of beams 90-5 and 90-6 corresponding to the "bottom-center 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 (-3φ _V1 , -2φ _V1 , -φ _V1 , 0) in the order of the first, second, third, and fourth rows. Therefore, the USB components of the modulated optical signals have the same phase at the output ports 37-1 and 37-2.

When waves arriving from the direction of beams 90-7 and 90-8 corresponding to the "downward direction" are received, the phase difference between the USB components of the four modulated optical signals supplied to each of row-direction scanning matrix circuits 21a-1 and 21a-2 is (-3φ _V2 , -2φ _V2 , -φ _V2 , 0) in the order of the first, second, third, and fourth rows. Therefore, the USB components of the modulated optical signals are in phase at output ports 38-1 and 38-2. When the USB components of the modulated optical signals are in phase, a row-direction combined optical signal with high signal intensity is obtained.

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

When incoming waves are received from the direction of each of beams 90-1 to 90-9, an in-phase combined row-direction optical signal and an in-phase combined column-direction optical signal are obtained, as described above. Therefore, when a user operates switching units 25b-1, 25b-2, and 52b to specify one of the directions of beams 90-1 to 90-9 as the desired direction, the connection states of switching units 25b-1, 25b-2, and 52b are changed to a connection state according to the desired direction, and a received signal corresponding to the desired direction is obtained from output port 52-5 of switching unit 52b.

(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 configuration example (part 2) 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 2x4 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.

The arrangement will be explained 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 so as to be parallel to the column axis. 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 so as to be parallel to the column axis. 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 80-2-1, 80-2-2, 80-2-3, and 80-2-4.

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 adjacent antenna elements 80-1-1 and 80-2-1 in the row direction and the distance between adjacent antenna elements 80-1-1 and 80-1-2 in the column direction may be the same or different lengths. Each of the antenna elements 80-1-1 to 80-2-4 receives an incoming wave and is thereby fed with an electrical RF signal.

The beams formed by the receiving directivity control device 1g in the array antenna 80c are beams 90-1 to 90-8 oriented in eight directions, as shown in Figure 16. When viewed through the plane of the array antenna 80c in the observation direction indicated by the arrow in Figure 15, i.e., from the side where the receiving directivity control device 1g is installed, beam 90-1 is oriented in the upper right direction, beam 90-4 is oriented in the upper left direction, beam 90-5 is oriented in the lower right direction, and beam 90-8 is oriented in the lower left direction.

Beam 90-2 points in a direction that is tilted upward from a line perpendicular to the surface of array antenna 80c and further tilted 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 that is tilted downward from a line perpendicular to the surface of array antenna 80c and further tilted 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 between a vertical plane and the directions of beams 90-1 and 90-5.

Beam 90-3 points in a direction that is tilted upward from a line perpendicular to the surface of array antenna 80c and further tilted left 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 that is tilted downward from a line perpendicular to the surface of array antenna 80c and further tilted left 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 between a vertical plane and the directions of beams 90-4 and 90-8.

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."

If the phase gradients caused by each of beams 90-1 to 90-8 are written in the form of (row-direction phase gradient, column-direction phase gradient), for example, beam 90-1 is (φ _V , φ _H2 ), beam 90-2 is (φ _V , φ _H1 ), beam 90-3 is (φ _V , −φ _H1 ), beam 90-4 is (φ _V , −φ _H2 ), beam 90-5 is (−φ _V , φ _H2 ), beam _90-6 is (−φ _V , φ _H1 ), beam 90-7 is (−φ _V , −φ H1 ), and beam 90-8 is (−φ _V , −φ _H2 ), where φ _H2 > φ _H1 .

The receiving directivity control device 1g includes a light source 5, an electro-optical conversion unit 10b, a row direction scanning unit 20e, and a column direction scanning unit 50d. The light source 5 supplies the optical signal it generates to each of the optical modulators 11-1-1 to 11-2-4 included in the electro-optical conversion unit 10b.

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 its corresponding antenna element 80-1-1 to 80-2-4.

The row direction scanning unit 20e has circuit configurations in the same number as 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 and a switching SW unit 25c-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 and a switching SW unit 25c-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 and a switching SW unit 25c-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 and a switching SW unit 25c-4 connected to the optical modulators 11-1-4 and 11-2-4 in the fourth column.

The four circuit configurations provided in the row direction scanning unit 20e are identical, and below, as an example, we will explain the circuit configuration corresponding to the first column, namely, the row direction scanning matrix circuit 21b-1 and the switching SW unit 25c-1. In the explanation of the circuit configuration corresponding to the first column below, the branch number "-1" of the symbol is replaced with "-2" to explain the circuit configuration corresponding to the second column, "-3" to explain the circuit configuration corresponding to the third column, and "-4" to explain the circuit configuration corresponding to the fourth column. However, in the explanation of 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".

The row-direction scanning matrix circuit 21b-1 is a one-dimensional weighting circuit and has 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 the 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.

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, thereby generating 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 is 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.

The predetermined row-direction phase scanning process performed by the row-direction scanning matrix circuit 21b-1 is the 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 the same process as the process in which "φ _H " is read as "φ _V ". Here, the input/output conditions are a condition where, on the input side, the input port 31-1 corresponds to the input port 51-1 and the input port 32-1 corresponds to the input port 51-2. On the output side, the output port 35-1 corresponds to the output port 51-5 and the output port 36-1 corresponds to the output port 51-6.

If 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 square filter 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.

The switching SW unit 25c-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 becomes the input port 41-1 of the switching SW unit 25c-1, the other input port of the SW circuit 16-1 becomes the input port 42-1 of the switching SW unit 25c-1, and the output port of the SW circuit 16-1 becomes the output port 51-1 of the switching SW unit 25c-1. In response to a user operation specifying the desired direction, the switching SW unit 25c-1 connects one of the two input ports 41-1, 42-1 to the output port 45-1. The input ports 41-1 and 42-1 are connected to the output ports 35-1 and 36-1 of the row-direction scanning matrix circuit 21b-1, respectively.

The two input ports 41-1 and 42-1 of the switching SW unit 25c-1 are pre-assigned to the two row direction components of each of the beams 90-1 to 90-8. Here, as mentioned above, the row direction is the vertical direction, so the row direction components are also referred to as vertical direction components. Input port 41-1 is pre-assigned to the "upward direction," which is the row direction component of the directions of beams 90-1, 90-2, 90-3, and 90-4. Input port 42-1 is pre-assigned to the "downward direction," which is the row direction component of the directions of beams 90-5, 90-6, 90-7, and 90-8.

The column scanning unit 50d includes a column scanning matrix circuit 51b and a switching SW unit 52c. 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 SW unit 25c-1. The input port 51-2 is connected to the output port 45-2 of the switching SW unit 25c-2. The input port 51-3 is connected to the output port 45-3 of the switching SW unit 25c-3. The input port 51-4 is connected to the output port 45-4 of the switching SW unit 25c-4.

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, thereby generating 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, these optical signals are referred to as column-direction combined optical signals). 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.

The predetermined column-direction phase scanning process performed by the column-direction scanning matrix circuit 51b is the same as the 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, where "φ _V2 " is replaced with "φ _H2 " and "φ _V1 " is replaced with "φ _H1 ". Here, the input/output conditions are conditions where, on the input side, the input port 51-1 corresponds to the input port 31-1, the input port 51-2 corresponds to the input port 32-1, the input port 51-3 corresponds to the input port 33-1, and the input port 51-4 corresponds to the input port 34-1. On the output side, the output port 51-5 corresponds to the output port 35-1, the output port 51-6 corresponds to the output port 36-1, the output port 51-7 corresponds to the output port 37-1, and the output port 51-8 corresponds to the output port 38-1.

If the column scanning matrix circuit 51b is implemented using, for example, a Butler matrix circuit, the column scanning matrix circuit 51b will have four square filters 62, 63, 64, and 65, just like the row scanning matrix circuit 21a-1 provided 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.

The switching SW unit 52c has three SW circuits 17-1, 17-2, and 17-3. The SW circuits 17-1 and 17-2 have the same configuration as the SW circuits 16-1-1 and 16-2-1, respectively, provided in the reception directivity control device 1f of the configuration example (part 1) of the third embodiment. The SW circuit 17-3 has the same configuration as the SW circuit 16-3-1 provided in the reception directivity control device 1f. The connection relationship between the SW circuits 17-1, 17-2, and 17-3 is the same as the connection relationship between the SW circuits 16-1-1, 16-2-1, and 16-3-1. Therefore, the switching SW unit 52c has the same configuration as the switching SW unit 25b-1 provided in the reception directivity control device 1f.

The two input ports of SW circuit 17-1 are input ports 52-1 and 52-2 of switching SW unit 52c, and the two input ports of SW circuit 17-2 are input ports 52-3 and 52-4 of switching SW unit 52c. The output port of SW circuit 17-3 is output port 52-5 of switching SW unit 52c. In this case, switching SW unit 52c becomes a four-input, one-output switch with four input ports 52-1, 52-2, 52-3, and 52-4 overall and one output port 52-5, and connects one of the four input ports 52-1, 52-2, 52-3, and 52-4 to output port 52-5 in response to a user operation specifying the desired direction. The input ports 52-1, 52-2, 52-3, and 52-4 are connected to the output ports 51-5, 51-6, 51-7, and 51-8 of the column-direction scanning matrix circuit 51b, respectively.

The four input ports 52-1, 52-2, 52-3, and 52-4 of the switching SW unit 52c are pre-assigned to the four column direction components of each of the beams 90-1 to 90-8. Here, as mentioned above, the column direction is the horizontal direction, so the column direction components are also horizontal components.

Input port 52-1 is pre-assigned to "rightward," which is the column component of the direction of beams 90-1 and 90-5. Input port 52-2 is pre-assigned to "center-right," which is the column component of the direction of beams 90-2 and 90-6. Input port 52-3 is pre-assigned to "center-left," which is the column component of the direction of beams 90-3 and 90-7. Input port 52-4 is pre-assigned to "leftward," which is the row component of the direction of beams 90-4 and 90-9.

(Processing of the receiving directivity control device according to the configuration example (part 2) of the third embodiment)
When waves arriving from the direction of beams 90-1, 90-2, 90-3, and 90-4 corresponding to the "upward 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 (0, -φ _V ) when shown in the order of row 1 and row 2. Therefore, the USB components of the modulated optical signals have the same phase at the output ports 35-1, 35-2, 35-3, and 35-4.

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 row-direction scanning matrix circuits 21b-1 to 21b-4 is (-φ _V , 0) when shown in the order of the first row and the second row. Therefore, the USB components of the modulated optical signals are in phase at 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.

The column-direction combined optical signal obtained in the column-direction scanning matrix circuit 51b is as follows. When waves arriving from the direction of beams 90-1 and 90-5 corresponding to "rightward" are received, the phase differences of the row-direction combined optical signals supplied to the input ports 51-1, 51-2, 51-3, and 51-4 are (0, -φ _H2 , -2φ _H2 , -3φ _H3 ). Therefore, the row-direction combined optical signals have the same phase at the output port 51-5.

When incoming waves are received from the direction of beams 90-2 and 90-6 corresponding to "right center direction," the phase differences of the row-direction combined optical signals supplied to the input ports 51-1, 51-2, 51-3, and 51-4 are (0, -φ _H1 , -2φ _H1 , -3φ _H1 ). Therefore, the row-direction combined optical signals have the same phase at the output port 51-6.

When waves arriving from the directions of beams 90-3 and 90-7 corresponding to "left center direction" 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 (-3φ _H1 , -2φ _H1 , -φ _H1 , 0). Therefore, the row direction combined optical signals have the same phase at the output port 51-7.

When incoming waves are received 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 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 high signal intensity is obtained.

When incoming waves are received from the direction of each of beams 90-1 to 90-9, an in-phase combined row-direction combined optical signal and an in-phase combined column-direction combined optical signal are obtained, as described above. Therefore, when a user operates switching units 25c-1, 25c-2, 25c-3, 25c-4, and 52c to specify one of the directions of beams 90-1 to 90-9 as the desired direction, the connection states of switching units 25c-1, 25c-2, 25c-3, 25c-4, and 52c are changed to a connection state according to the desired direction, and a received signal corresponding to the desired direction is obtained from output port 52-5 of switching unit 52c.

(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 the number of beams formed 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 size 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.

In another configuration example (part 1) of the second embodiment, the reception directivity control device 1f shown in Figure 11 is used as the main body 110 of the reception directivity control device 1b described with reference to Figure 6, and the array antenna 80b is connected to the reception directivity control device 1f. In this state, the rotation mechanism 111 can be used to rotate the reception directivity control device 1f and the array antenna 80b by 90 degrees to achieve the arrangement of the array antenna 80c shown in Figure 15.

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

Here, a comparison of the internal configurations, excluding the electro-optical conversion units 10a and 10b, between the reception directivity control device 1f shown in Figure 11 and the reception directivity control device 1g shown in Figure 14 is shown below.

In terms of components, the reception directivity control device 1f shown in Figure 11 comprises three matrix circuits: row-direction scanning matrix circuits 21a-1 and 21a-2 and column-direction scanning matrix circuit 51a, and three switching SW units 25b-1, 25b-2, and 52b. Therefore, the number of components of the reception directivity control device 1f is six.

In contrast, the reception directivity control device 1g shown in FIG. 14 has, in terms of components, five matrix circuits: row scanning matrix circuits 21b-1 to 21b-4 and column scanning matrix circuit 51b, and five switching SW units 25c-1 to 25c-4, 52c. Therefore, the number of components of the reception directivity control device 1g is 10. Therefore, in terms of the number of components, the reception directivity control device 1f has fewer components than the reception directivity control device 1g.

In terms of components, the reception directivity control device 1f shown in Figure 11 comprises nine square couplers 61-1, 61-2, 62-1, 62-2, 63-1, 63-2, 64-1, 64-2, and 65, and seven two-input, one-output SW circuits 16-1-1, 16-1-2, 16-2-1, 16-2-2, 16-3-1, 16-3-2, and 17. Therefore, the number of components of the reception directivity control device 1f is 16.

In contrast, the reception directivity control device 1g shown in Figure 14 comprises eight square couplers 61-1, 61-2, 61-3, 61-4, 62, 63, 64, and 65, and seven two-input, one-output SW circuits 16-1, 16-2, 16-3, 16-4, 17-1-1, 17-2-1, and 17-3-1. Therefore, the number of components of the reception directivity control device 1g is 15. Therefore, in terms of the number of components, the reception directivity control device 1g has fewer components than the reception directivity control device 1f.

From the above, if a small number of components is a priority, the reception directivity control device 1f shown in Figure 11 should be used. On the other hand, if a small number of components is a priority, the reception directivity control device 1g shown in Figure 14 should be used.

The above-described reception directivity control devices 1f and 1g may also be configured to obtain, in parallel, received signals corresponding to incoming waves arriving from the directions of multiple beams 90-1 to 90-9, like the reception directivity control device 1a of the second embodiment. In this case, switching SW units 25b-1, 25b-2, and 25c-1 to 25c-4 must be replaced with switching SW units that connect to any input port and output port, like switching SW units 25a-1 and 25a-2 in the reception directivity control device 1a. Switching SW units 52b and 52c must be replaced with switching SW units that have the same number of output ports as the number of input ports, like switching SW unit 52a in the reception directivity control device 1a. However, even if the reception directivity control devices 1f and 1g are configured to obtain, in parallel, reception signals corresponding to incoming waves arriving from the directions of multiple beams 90-1 to 90-9, the reception directivity control devices 1f and 1g must be installed so that, in a coordinate system defined by the row and column axes of the array antennas 80b and 80c, the column components of the directions of the incoming waves are in different directions. Therefore, the reception directivity control device 1f can obtain, in parallel, reception signals corresponding to incoming waves from a maximum of two directions. In contrast, the reception directivity control device 1g can obtain, in parallel, reception signals corresponding to incoming waves from a maximum of four directions.

(Other configuration examples of each embodiment)
In the array antennas 80, 80b, and 80c shown in the first to third embodiments described above, the vertical direction is the row direction and the horizontal direction is the column direction, while in the array antenna 80a, which is 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.

In the first and second embodiments described above, an example is shown in which the number of antenna elements in array antennas 80 and 80a is nine, and in the third embodiment, an example is shown in which the number of antenna elements in array antennas 80b and 80c is eight. It has been explained that the number of antenna elements may be increased in these embodiments. The conditions for the number of antenna elements are more specifically stated, for example, as follows: 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 M or 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.

In each of the above embodiments, 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 they may also be configured to output the LSB component, which is the other component of the single sideband wave.

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, for example, SSB optical modulation. Because 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 the function of a filter that suppresses the carrier component and LSB component. Therefore, instead of optical modulators that perform SSB optical modulation, each of optical modulators 11-1-1 to 11-3-3, 11-4-1, 11-4-2, 11-1-4, and 11-2-4 may be optical modulators such as direct modulators or phase modulators, with a filter on the output side that suppresses the carrier component and LSB component. In this case, the components including the optical modulator and the filter are the electrical-to-optical conversion units 10, 10a, and 10b.

In the first to third embodiments described above, 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, and 21b-4 and the column-direction scanning matrix circuits 51, 51a, and 51b is, for example, a Butler matrix circuit, as described in the third embodiment. However, this is not limited to a Butler matrix circuit, and matrix circuits other than a Butler matrix circuit may also be applied.

The row 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 scanning matrix circuits 51, 51a, and 51b may be circuits that transmit spatial beam optical signals, i.e., optical signals propagating through space, through lenses and impart a phase tilt to the optical signals. In addition to optical lenses, the lenses may also be, for example, Rotman lenses, as described in Reference 2 below.

[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.]

In each of the above embodiments, the reception directivity control devices 1, 1a, 1b, 1c, 1d, 1e, 1f, and 1g do not include array antennas 80, 80a, 80b, and 80c, but are configured to be connected to 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 an array antenna 80, 80a, 80b, and 80c connected to it.

The above describes in detail an embodiment of the present invention with reference to the drawings, but the specific configuration is not limited to this embodiment and also includes designs that do not deviate from the gist of the present invention.

It can be applied to ultra-high-speed wireless transmission using radio waves in the millimeter wave and terahertz high-frequency bands, high-definition imaging, and receiving radio waves with sharp directionality formed in radar, etc.

1...receiving directivity control device, 10...electrical-optical conversion unit, 11-1-1 to 11-3-3...optical modulator, 20...row direction scanning unit, 21-1 to 21-3...row direction scanning matrix circuit, 25-1 to 25-3...switching SW unit, 50...column direction scanning unit, 51...column direction scanning matrix circuit, 52...switching SW unit, 80...array antenna, 80-1-1 to 80-3-3...antenna elements

Claims (8)

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 generates a row direction synthesized optical signal corresponding to each of the row direction components in the beam forming direction by synthesizing each of the single sideband wave components included in each combination of the single sideband wave components having the same column position by performing a predetermined row direction phase scanning process that imparts a phase gradient that aligns the phase of each row direction component in the beam forming direction 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 each of the beam forming directions;
a column direction scanning unit that performs a predetermined column direction phase scanning process on each of the row direction combined optical signals generated 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, and selects and outputs the column direction combined optical signal corresponding to the column direction component in the beam forming direction that coincides with a specified desired direction;
A receiving directivity control device comprising: As the desired direction, any one of the beam forming directions is designated, or a plurality of the beam forming directions are designated.
The receiving directivity control device according to claim 1 . The row direction scanning unit
selecting and outputting the row direction combined optical signal corresponding to a row direction component of the beam forming direction that coincides with the designated desired direction;
The receiving directivity control device according to claim 1 . The row direction scanning unit
generating a combined optical signal by combining the row-direction combined optical signals generated from the same combination of the single sideband wave components for each combination of the single sideband wave components, and outputting each of the combined optical signals;
The receiving directivity control device according to claim 1 . When incoming waves arrive from a plurality of directions, the antenna elements are arranged so that the column direction components of the directions from which the incoming waves arrive are in different directions.
The receiving directivity control device according to claim 1 . 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 incoming waves arrive from a plurality of directions, and when the incoming waves arrive from directions with different row direction components in the 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 waves arrive from directions with different column direction components.
The receiving directivity control device according to claim 1 . 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 incoming waves arrive from a plurality of directions and row direction components arrive from different directions, the matrix permutation unit permutes the rows and columns of the captured single sideband wave components to make the incoming waves arrive from different directions with column direction components .
The receiving directivity control device according to claim 1 . 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;
performing a predetermined column-direction phase scanning process on each of the generated row-direction combined optical signals, the process applying a phase gradient that aligns the phase of each column-direction component in the beam-forming direction, taking into account differences in the positions of the corresponding columns and column-direction phase gradients that occur depending on each of the beam-forming directions, to generate a column-direction combined optical signal corresponding to each of the column-direction components in the beam-forming direction;
selecting and outputting the column-direction combined optical signal corresponding to a column-direction component of the beam forming direction that coincides with a specified desired direction;
Reception directivity control method.