JP7824638B2 - Radio wave transmitter/receiver, distributed phased array antenna system, distributed electromagnetic wave observation data collection system, and distributed synthetic aperture radar system - Google Patents

Description

The present invention relates to a radio wave transceiver capable of acquiring its own space-time differential information, a distributed phased array antenna system using multiple radio wave transceivers, a distributed electromagnetic wave observation data collection system using multiple radio wave transceivers, and a distributed synthetic aperture radar system using multiple radio wave transceivers.

Among array antennas, which are made up of an array of multiple small antennas, there is a phased array antenna, in which each antenna element is connected to a phase shifter and beamforming is performed by controlling the relative phase shift between the antennas. Compared to conventional mechanically driven scanning beam control, the beam control of a phased array antenna has advantages such as improved speed and controllability, and a reduced failure rate due to fewer moving parts. Phased array antennas have a wide range of uses, including adaptively directing the main lobe toward a specific destination to improve data transfer efficiency, and being used as intelligence gathering radar.

Synthetic aperture radar (SAR) is also available, in which radar mounted on a flying object such as a satellite or aircraft emits radio waves to the ground as it moves, receives and combines the reflected waves, and effectively synthesizes a large-aperture antenna using a relatively small aperture antenna. SAR is suitable for all weather conditions and can obtain high-resolution images of terrain, day or night, so it is used for Earth observation and planetary exploration. There are also SARs that use phased arrays (for example, PALSAR: Phased Array Type L-band Synthetic Aperture Radar).

In phased array antennas like those described above and SARs that utilize them, relative phase control between antenna elements is important in order to combine the radio waves emitted by each antenna element to obtain the desired beam characteristics. Therefore, multiple antenna elements and phase shifters are typically individually wired, and the relative phase of the radio waves emitted from each antenna element is centrally controlled to obtain the desired beam characteristics.

Furthermore, in phased array antennas and the SAR that utilizes them, there is distributed antenna/distributed SAR technology, in which each antenna element that makes up the array antenna has its own reference signal generator and amplifier, and independently controls its own phase. With such distributed antennas/distributed SAR, as long as the placement of each antenna element is maintained stably, the desired beam characteristics can be achieved by adjusting the phase according to the arrangement of each antenna element. However, if the placement of each antenna element changes, autonomous control is required, taking into account the relative phase of the radio waves between each antenna element.

For example, if a satellite launched into orbit with its antenna panels folded unfolds them, mechanical or thermal distortion occurs, preventing the ideal phased array antenna radiation surface shape and achieving ideal characteristics. A technology has been proposed that uses optical technology to detect phase errors induced by such antenna shape distortion, calculates the phase correction values necessary to compensate for these errors, and performs real-time shape compensation (see, for example, Patent Document 1). In the phased array antenna described in Patent Document 1, each antenna panel is divided into a module (a unit consisting of an antenna element, amplifier, phase shifter, and controller). Therefore, by miniaturizing the individual modules and folding them in a stacked manner, they can be easily stored within the launch vehicle's payload fairing.

A distributed aperture system has also been proposed in which multiple small satellites are each equipped with an antenna element and maintain their relative positions in cooperation with each other or with the assistance of a control satellite, forming a phased array antenna (see, for example, Patent Document 2). The distributed aperture system described in Patent Document 2 employs technology that uses electromagnetic coils to change the relative distance between each satellite to maintain distance x and angle y, in order to maintain constant relative positions between the small satellites and between the small satellites and the control satellite.

Patent No. 4951622 Patent No. 6506365

However, the phased array antenna described in Patent Document 1 has antenna modules that perform independent phase control connected by wire and mounted on the same mobile object (satellite), so as the number of modules increases, the overall size increases, making it difficult to store in a small space. Furthermore, because the phased array antenna described in Patent Document 1 does not allow for arbitrary rearrangement of the antenna modules, it lacks the flexibility to replace a faulty antenna module with a working one and operate it, nor the scalability to increase or decrease the number of antenna modules or change the antenna module arrangement as needed.

On the other hand, the distributed aperture system described in Patent Document 2 has antenna elements mounted on multiple mobile objects (satellites), which collectively form an array antenna. This allows for flexibility, such as replacing a faulty mobile object with one equipped with a functioning antenna element, and allows for the number of mobile objects and the layout of the mobile objects to be increased or decreased as needed, resulting in excellent scalability. However, the distributed aperture system described in Patent Document 2 requires each mobile object to maintain its relative position to form an array. Since the positioning accuracy depends on the means of movement of the mobile object and external disturbances, deviations from the ideal layout due to misalignment can result in significant errors. In other words, if the ideal layout of the antenna elements cannot be maintained, the quality of the beam emitted by the entire array antenna will deteriorate. This issue is not limited to cases where antenna elements are mounted on mobile objects; it also applies to portable, fixed distributed antennas, where misalignment when installing each antenna will deteriorate the quality of the beam emitted by the entire array antenna. Furthermore, because the distributed aperture system described in Patent Document 2 uses an array of independent small satellites, it is not possible to achieve high-precision time synchronization using a common clock, as is the case with known phased array antennas. Therefore, time differences between the small satellites will deteriorate the quality of the beam emitted by the entire array antenna. Furthermore, even in beamforming antennas, which can form receiving beams with various directions by appropriately weighting and combining received signals from multiple antenna elements, phase shifts in the received signals degrade the quality of the formed beam. Similarly, in synthetic aperture radars, which move in the azimuth direction above an image acquisition area and repeatedly transmit and receive pulses from multiple antenna elements, and then process the received signals obtained by the synthetic aperture radar signal processing device to generate two-dimensional images, phase shifts in the transmitted and received signals degrade the quality of the two-dimensional images.

The present invention therefore aims to provide a radio wave transmitter/receiver that can acquire phase shift information that can be used as correction information to prevent degradation of beam quality, a distributed phased array antenna system using multiple radio wave transmitters/receivers, a distributed electromagnetic wave observation data collection system using multiple radio wave transmitters/receivers, and a distributed synthetic aperture radar system using multiple radio wave transmitters/receivers.

To solve the above problem, the first radio wave transceiver is a radio wave transceiver that can be used as an antenna element in a phased array antenna system in which multiple antenna elements are arranged to obtain a desired directivity, and is equipped with N communication antennas (N is any natural number), a space-time difference information acquisition unit, a phase shift adjustment unit, and a reference oscillator that generates a reference frequency signal. The space-time difference information acquisition unit transmits and receives codes to and from other radio wave transceivers via wireless communication using a synchronization antenna separate from the communication antenna, and measures temporal difference information, which is the temporal error between the reference radio wave transceiver and the radio wave transceiver itself, and spatial difference information, which is the spatial error between the appropriate position of the radio wave transceiver and its current position relative to the reference radio wave transceiver, based on the time difference between the reference oscillators and the propagation delay time associated with the code transmission and reception, and acquires space-time difference information including the temporal difference information and the spatial difference information. The phase shift adjustment unit adjusts the phase shift of the radio waves radiated from the communication antenna based on the space-time difference information to correct the temporal error and/or the spatial error.

Furthermore, the distributed phased array antenna system according to the present invention is characterized in that it is configured using a plurality of first radio wave transceivers, and the phased array antenna system has a specific directivity due to the superposition of radio waves radiated from the communication antennas of each radio wave transceiver.

In order to solve the above problem, the second radio wave transceiver is a radio wave transceiver that can be used as each antenna element in a beamforming antenna that can form reception beams with various directions by arranging multiple antenna elements and combining the received signals received by each antenna element with appropriate phase shift processing and appropriate weighting (amplitude amplification/attenuation), and is equipped with N communication antennas (N is any natural number), a space-time difference information acquisition unit, N signal receiving units corresponding to each communication antenna, a received data transmission unit, and a reference oscillator that generates a reference frequency signal, and the space-time difference information acquisition unit is configured to acquire the signal by wireless communication using a synchronization antenna separate from the communication antenna. The radio wave transmitter/receiver transmits and receives codes with the other radio wave transmitter/receiver, and measures temporal difference information, which is the time difference between the reference radio wave transmitter/receiver and the radio wave transmitter/receiver itself, and spatial difference information, which is the current position of the radio wave transmitter/receiver relative to the reference radio wave transmitter/receiver, based on the time difference between the reference oscillators and the propagation delay time associated with the code transmission and reception, and obtains spatiotemporal difference information including the temporal difference information and the spatial difference information. The received data transmitter transmits received data linked to the received signal received by the signal receiver, the spatiotemporal difference information at the time of reception, and unique information of the radio wave transmitter/receiver itself that is set to enable identification of the radio wave transmitter/receiver from the other radio wave transmitter/receiver.

Furthermore, the distributed electromagnetic wave observation data collection system of the present invention includes a plurality of slave mobility units each equipped with a second radio wave transmitter/receiver mounted on a mobile body, and a master mobility unit each equipped with a data relay unit that collects the received data transmitted from the plurality of slave mobility units and transfers the collected received data to a predetermined data collection center; the plurality of slave mobility units and the master mobility unit are arranged in an arbitrarily set electromagnetic wave observation area, and only the master mobility unit that collects the received data from each slave mobility unit transfers the collected received data to the data collection center as electromagnetic wave observation data.

In order to solve the above-mentioned problems, the third radio wave transmitter/receiver is a radio wave transmitter/receiver that can be used as each antenna element in a synthetic aperture radar that arranges multiple antenna elements and generates a two-dimensional image by processing the received signals obtained by repeatedly transmitting and receiving pulses while moving in the azimuth direction above an image acquisition area using a synthetic aperture radar signal processing device, and is equipped with N communication antennas (N is any natural number), N pulse transmission/reception units corresponding to each communication antenna, a space-time difference information acquisition unit, a received data transmission unit, and a reference oscillator that generates a reference frequency signal, and the space-time difference information acquisition unit transmits the received data to other radio wave transmitters/receivers via wireless communication using a synchronization antenna separate from the communication antenna. The synthetic aperture radar signal processing device transmits and receives codes to and from the reference radio wave transmitter and receiver, and measures temporal difference information, which is the time difference between the reference radio wave transmitter and receiver and its own device, and spatial difference information, which is its current relative position with respect to the reference radio wave transmitter and receiver, based on the time difference between the respective reference oscillators and the propagation delay time associated with the code transmission and reception, and acquires spatiotemporal difference information including the temporal difference information and the spatial difference information. The received data transmission unit transmits the reflected signal received by the pulse transmission and reception unit, the spatiotemporal difference information acquired by the spatiotemporal difference information acquisition unit, and its own device's unique information, which is set to enable it to distinguish its own device from other radio wave transmitters and receivers, as received data to the synthetic aperture radar signal processing device.

Furthermore, the distributed synthetic aperture radar system according to the present invention includes a master synthetic aperture radar device that is mounted on a mobile body and that transmits pulse signals to the image acquisition area and receives reflected signals from the master synthetic aperture radar device, M slave synthetic aperture radar devices (M is any natural number) that are mounted on a mobile body and that transmit pulse signals to the same image acquisition area as the master synthetic aperture radar device and receive reflected signals from the master synthetic aperture radar device, and a synthetic aperture radar signal processing device that processes the received data from the master synthetic aperture radar device and the slave synthetic aperture radar device to generate a two-dimensional image, and The synthetic aperture radar device acquires the spatiotemporal difference information using the master synthetic aperture radar device as the reference radio wave transceiver, and transmits pulse signals synchronized with the pulse transmission of the master synthetic aperture radar device by performing phase adjustment to correct the temporal error based at least on the temporal difference information, and the synthetic aperture radar signal processing device performs phase adjustment to correct the spatial error for the reflected signals in the received data from the master synthetic aperture radar device and/or the slave synthetic aperture radar device based at least on the spatial difference information in the spatiotemporal difference information.

The first to third radio wave transceivers according to the present invention can acquire spatiotemporal difference information between the first and third radio wave transceivers. Therefore, a distributed phased array antenna system using multiple first radio wave transceivers can suppress degradation of beam quality by using the spatiotemporal difference information acquired by each radio wave transceiver as correction information. A distributed electromagnetic wave observation data collection system using multiple second radio wave transceivers can suppress degradation of beam quality by using the spatiotemporal difference information acquired by each radio wave transceiver as correction information. A distributed synthetic aperture radar system using multiple third radio wave transceivers can suppress degradation of two-dimensional image quality by using the spatiotemporal difference information acquired by each radio wave transceiver as correction information.

1A is a schematic configuration diagram of a distributed phased array antenna system according to an embodiment of the present invention, and FIG. 1B is a schematic configuration diagram of a radio wave transmitter/receiver according to a first configuration example used in the distributed phased array antenna system. 1A and 1B are conceptual diagrams showing a first example of radiation characteristics of a distributed phased array antenna system in which radio wave transmitters and receivers are arranged at equal intervals in a straight line so as to function as a linear array antenna, respectively. (A) is a conceptual diagram showing radiation characteristics when there is no time error in the reference oscillator of each radio wave transmitter and receiver used in the distributed phased array antenna system, (B) is a conceptual diagram showing radiation characteristics when there is a time error in the reference oscillator of each radio wave transmitter and receiver used in the distributed phased array antenna system, and (C) is a conceptual diagram showing radiation characteristics when the time error contained in the reference oscillator of each radio wave transmitter and receiver used in the distributed phased array antenna system is corrected based on time difference information. FIG. 1 is an explanatory diagram of a correction operation performed by each radio wave transmitter/receiver used in a distributed phased array antenna system to detect a phase difference between them and achieve phase synchronization. FIG. 10 is a schematic diagram illustrating the configuration of a radio wave transmitter/receiver according to a second configuration example. FIG. 10 is a schematic diagram of a radio wave transmitter/receiver according to a third configuration example. (A) is a conceptual diagram of a distributed phased array antenna system using radio wave transmitters and receivers mounted on multiple vehicles, and (B) is a conceptual diagram of a distributed phased array antenna system using radio wave transmitters and receivers mounted on multiple unmanned aerial vehicles. This is a schematic diagram of a distributed electromagnetic wave observation data collection system consisting of multiple slave mobility units and one master mobility unit. 1A is a schematic diagram of a radio wave transmitter and receiver used for slave mobility, and FIG. 1B is a schematic diagram of a radio wave transmitter and receiver used for master mobility. FIG. 1 is a schematic diagram of a distributed synthetic aperture radar system configured with one master synthetic aperture radar device, multiple slave synthetic aperture radar devices, and one mobile control device. FIG. 1 is a schematic diagram of a distributed synthetic aperture radar system in which pulse signals are transmitted from one master synthetic aperture radar device and M slave synthetic aperture radar devices to an object to be observed, and reflected signals are received by one master synthetic aperture radar device and M slave synthetic aperture radar devices. FIG. 1 is a schematic diagram of a distributed synthetic aperture radar system in which one master synthetic aperture radar device transmits a pulse signal to an object to be observed, and one master synthetic aperture radar device and M slave synthetic aperture radar devices receive the reflected signal.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Figure 1(A) shows a distributed phased array antenna system 1, which comprises four radio wave transceivers 2 (e.g., a first radio wave transceiver 2A, a second radio wave transceiver 2B, a third radio wave transceiver 2C, and a fourth radio wave transceiver 2D) arranged on a substantially flat surface facing the communication direction, and a system control device 11. The first through fourth radio wave transceivers 2A through 2D, which are arranged in appropriate distributed locations, all have common functions (see, for example, Figure 1(B)). When there is no need to distinguish between the first through fourth radio wave transceivers 2A through 2D, they will be simply referred to as radio wave transceivers 2. Furthermore, the number of radio wave transceivers 2 used in the distributed phased array antenna system 1 is not limited to four, but may be two, three, or five or more.

The radio wave transmitter/receiver 2 can be used as an antenna element that constitutes a "phased array antenna system in which multiple antenna elements are arranged to obtain the desired directivity." That is, in the distributed phased array antenna system 1, multiple radio wave transmitters/receivers 2 are arranged, and in response to instructions from the system control device 11, all or some of the antennas of these radio wave transmitters/receivers 2 are excited, and the desired directivity is obtained by superimposing the radio waves obtained by controlling the excitation amplitude and excitation phase.

Array antennas are classified into linear arrays, planar arrays, circular arrays, conformal arrays, etc. depending on the arrangement method. Furthermore, an array antenna that controls the beam direction and radiation pattern by the relative phase of each radiating element is specifically called a phased array antenna. An antenna in which the radiating elements are separated and not electrically connected, and each radiating element controls itself independently, is called a distributed array antenna. Based on these existing technologies, the present invention, which is a system that controls the beam direction and radiation pattern by the relative phase of radio wave transmitters and receivers 2, which are independent radiating elements, is called a distributed phased array antenna system 1.

Furthermore, for the distributed phased array antenna system 1 to function as a phased array antenna, the system control device 11 must issue directional pattern control instructions to the first to fourth radio wave transceivers 2A to 2D, and the first to fourth radio wave transceivers 2A to 2D must transmit received signals to the system control device 11. Therefore, the system control device 11 and the first to fourth radio wave transceivers 2A to 2D must have bidirectional signal transmission capabilities. While FIG. 1(A) shows an example in which the system control device 11 and the first to fourth radio wave transceivers 2A to 2D are connected by wire, wireless connections are also acceptable. Furthermore, if the functionality of the system control device 11 is added to any one of the first to fourth radio wave transceivers 2A to 2D that make up the distributed phased array antenna system 1, there is no need to provide a separate system control device 11.

Each radio wave transmitter/receiver 2 is housed in an independent housing and can be handled individually. Therefore, if the size and weight of the radio wave transmitter/receiver 2 are sufficiently reduced, the radio wave transmitter/receiver 2 can be highly portable. Furthermore, the number and arrangement of the radio wave transmitters/receivers 2 used in the distributed phased array antenna system 1 can be freely changed to control the radiation characteristics, thereby increasing the degree of flexibility of the system. However, a downside of distributing the radiation elements is that it is difficult to precisely align the radio wave transmitters/receivers 2 for ideal placement, which can lead to errors. In addition, because each radio wave transmitter/receiver 2 is independent, the generation of a reference clock, etc., must be performed for each radio wave transmitter/receiver 2. This prevents highly accurate synchronization using a common clock, as with known phased array antennas, and can lead to errors. Therefore, the radio wave transmitter/receiver 2 of this embodiment is equipped with a function that can correct temporal and spatial errors, thereby minimizing degradation of the beam quality obtained by the distributed phased array antenna system 1.

The error correction function of the radio wave transceiver 2 shown as the first configuration example will be described in detail below with reference to Figure 1(B). Note that the signal communication function and processing operations performed by the radio wave transceiver 2 with the system control device 11 are omitted from Figure 1(B) because various technologies used in known phased array antennas can be applied.

The radio wave transceiver 2 is composed of a communication antenna 21, a transmission/reception module 22, a radiation control unit 23, a phase adjustment unit 24, a transmission/reception control unit 25, a reference oscillator 26, a synchronization antenna 27, and a time-space difference information acquisition unit 28. The communication antenna 21 is preferably a dipole antenna, a slot antenna, or a microstrip antenna. The communication antenna 21, the transmission/reception module 22, the radiation control unit 23, and the phase adjustment unit 24 function as a single radiation element constituting a phased array. The radiation control unit 23 controls the frequency and intensity of the high-frequency wave supplied to the antenna, and the phase adjustment unit 24 controls the phase of the high-frequency wave. The transmission/reception module 22 includes a phase shifter 221 and an amplifier circuit (e.g., a transmission amplifier 222 and a reception low-noise amplifier 223) that can arbitrarily adjust the phase of each of the transmission and reception paths. The transmission/reception module 22 switches between transmitting the high-frequency wave supplied via the radiation control unit 23 and the phase shifter 221 to the communication antenna 21 or phase-shifting the high-frequency wave received by the communication antenna 21 and then demodulating it. That is, the radio wave transceiver 2 can radiate and receive radio waves with arbitrarily controlled phases from the communication antenna 21. Note that the following explanation of the radio wave transceiver 2 focuses on an example of operation for radiating radio waves, but similar effects can also be achieved when receiving.

Figure 2(A) shows a distributed phased array antenna system 1 with a linear array configuration in which first to fourth radio wave transmitters and receivers 2A to 2D are aligned in a straight line at a distance d from each other. The clocks of the first to fourth radio wave transmitters and receivers 2A to 2D are synchronized with ideal accuracy. Therefore, when high-frequency waves synchronized with an excitation phase Φ are transmitted from the transmitting antennas 21 of the first to fourth radio wave receivers 2A to 2D, a composite wave wavefront WF is generated whose direction is perpendicular to the arrangement direction of the first to fourth radio wave transmitters and receivers 2A to 2D. On the other hand, Figure 2(B) shows a case in which a high frequency wave with an excitation phase Φ is transmitted from the transmitting antenna 21 of the first radio wave transceiver 2A, a high frequency wave with an excitation phase Φ+Δφ is transmitted from the transmitting antenna 21 of the second radio wave transceiver 2B, a high frequency wave with an excitation phase Φ+2Δφ is transmitted from the transmitting antenna 21 of the third radio wave transceiver 2C, and a high frequency wave with an excitation phase Φ+3Δφ is transmitted from the transmitting antenna 21 of the fourth radio wave transceiver 2D. In this way, when high frequency waves with phase adjustments according to the arrangement positions of the first to fourth radio wave transceivers 2A to 2D are transmitted, a wavefront WF of a composite wave is generated whose direction is tilted by an angle θ with respect to the direction of direction shown in Figure 2(A).

However, unlike known array antennas, each radio wave transceiver 2 used in a distributed phased array antenna system 1 is not centrally managed and operates independently of other radio wave transceivers 2. Therefore, the state of its own high-frequency signal, such as its excitation amplitude and phase, must be individually monitored and controlled. The challenge here is to align the phase with other radio wave transceivers 2 according to a set rule. To achieve this, it is essential to monitor the time difference information, which is the time error between the reference radio wave transceiver 2 and the own radio wave transceiver, and the spatial difference information, which is the spatial error between the own radio wave transceiver's appropriate position relative to the reference radio wave transceiver 2 and its current position, and to control the high-frequency state to correct the phase shift required to obtain the desired composite wave. The time difference information may be the error between the reference oscillator 26 of the reference radio wave transceiver 2 and the own radio wave transceiver's own reference oscillator 26, or the error between the clock counting the reference frequency signal (e.g., a reference clock signal) generated by the reference oscillator 26 of the reference radio wave transceiver 2 and the own radio wave transceiver's own clock. Furthermore, the spatial difference information is obtained based on the position of a reference radio wave transmitter/receiver 2 (hereinafter referred to as the reference device) to determine the spatial error between the ideally positioned position (appropriate position) assigned to the device in the distributed phased array antenna system 1 and the device's current position. Even if the position of the reference device is slightly off from the appropriate position, as long as the other radio wave transmitters/receivers 2 are placed in appropriate positions relative to the reference device, the distributed phased array antenna system 1 can achieve the intended directivity.

Therefore, in addition to the reference oscillator 26, the radio wave transceiver 2 is equipped with a synchronization antenna 27 and a spatiotemporal difference information acquisition unit 28. The spatiotemporal difference information acquisition unit 28 acquires spatiotemporal difference information, including both temporal difference information with other radio wave transceivers 2 and spatial difference information with other radio wave transceivers 2. Based on this spatiotemporal difference information, the phase adjustment unit 24 controls the phase shifter 221 of the transceiver module 22 to control the phase shift amount of the high-frequency signal emitted from the communication antenna 21. In this way, by grasping the spatiotemporal difference information, including the above-mentioned temporal difference information and spatial difference information, and correcting temporal and spatial errors, it is possible to cooperatively obtain a desired composite wave even when multiple radio wave transceivers 2 are used, operating independently. For example, the spatiotemporal difference information acquisition unit 28 transmits and receives codes with other radio wave transceivers 2 via wireless communication via the synchronization antenna 27, and measures the temporal difference information and the spatial difference information based on the time difference between the mutual reference oscillators 26 and the propagation delay time associated with the code transmission and reception. Alternatively, the phase shift may be measured by communicating with another wired radio wave transmitter/receiver 2 without using the synchronization antenna 27.

The spatiotemporal difference information, including the temporal difference information and spatial difference information, acquired by the spatiotemporal difference information acquisition unit 28 is supplied to the phase adjustment unit 24 via the transmission/reception control unit 25 and used to control phase shift correction. That is, the emission control unit 23 excites the high-frequency signal based on the clock source provided by the reference oscillator 26, and the phase adjustment unit 24 controls the phase amount provided by the phase shifter 221 based on the spatiotemporal difference information to correct spatiotemporal errors in the high-frequency signal, and transmits the high-frequency signal from the communication antenna 21 with reduced degradation in beam quality. This makes it possible to obtain the desired composite wave as a distributed phased array antenna system 1 using multiple independently operating radio wave transceivers 2. This phase correction operation will be explained with reference to Figure 3. For simplicity's sake, Figure 3 shows a linear array structure in which the first to third radio wave transceivers 2A to 2C are arranged in a row at equal intervals.

For example, as shown in Figure 3(A), if the reference oscillators 26 of the first through third radio wave transceivers 2A through 2C are synchronized with high precision and there is no time error in the time TM, no time error will occur in the high-frequency signal supplied to the transceiver module 22. First, if the phase shift amount Φa0 used for phase adjustment in the transceiver module 22 of the first radio wave transceiver 2A is set to 0 (zero) as instructed by the system control device 11, the high-frequency signal emitted from the communication antenna 21 will have the specified phase. Similarly, if the phase shift amount Φb0 used for phase adjustment in the transceiver module 22 of the second radio wave transceiver 2B is set to π/6 as instructed by the system control device 11, the high-frequency signal emitted from the communication antenna 21 will have the specified phase. Similarly, if the phase shift amount Φc0 used for phase adjustment in the transceiver module 22 of the third radio wave transceiver 2C is set to π/3 (= 2π/6) as instructed by the system control device 11, the high-frequency signal emitted from the communication antenna 21 will have the specified phase. In this way, if there is no time error in the times TM of the first to third radio wave transmitters/receivers 2A to 2C, the wavefronts will be aligned in the direction corresponding to the phase difference of the high-frequency signals emitted from each communication antenna 21, resulting in desirable directivity.

However, as shown in Figure 3(B), if the times of the first through third radio wave transmitters and receivers 2A through 2C are not synchronized with the master clock, a time error will occur in the high-frequency signal supplied to the transmitter/receiver module 22. First, because the clock of the first radio wave transmitter/receiver 2A is synchronized with the master clock (matching time TM), the high-frequency signal phase-adjusted within the transmitter/receiver module 22 (phase shift Φa0 = 0) will have the specified phase. However, because the clock of the second radio wave transmitter/receiver 2B is ahead of the master clock by Δtb, time TM + Δtb becomes the oscillation reference for the high-frequency signal, and the high-frequency signal phase-adjusted within the transmitter/receiver module 22 (phase shift Φb0 = π/6) will have a phase shift from the originally specified phase. Furthermore, because the clock of the third radio wave transmitter/receiver 2C is ahead of the master clock by Δtc, time TM + Δtc becomes the oscillation reference for the high-frequency signal, and the high-frequency signal phase-adjusted within the transmitter/receiver module 22 (phase shift Φc0 = π/3) will have a phase shift from the originally specified phase. As a result, the wavefronts of the high-frequency signals emitted from each communication antenna 21 in Figure 3(B) do not align in the direction corresponding to the phase difference, and suitable directivity cannot be obtained.

On the other hand, as shown in Figure 3(C), even if the time of the first to third radio wave transceivers 2A to 2C is not synchronized with the master clock, the time error that occurs in the high frequency signal can be eliminated by adjusting the phase amount using the phase adjustment unit 24 to correct the time discrepancy. In the following, the period of the transmitted high frequency signal is assumed to be P. First, since the clock of the first radio wave transceiver 2A is synchronized with the master clock (matching time TM), the correction phase adjustment amount ΦaC that the phase adjustment unit 24 instructs the transceiver module 22 to remain Φa0 (= 0), and the high frequency signal emitted from the communication antenna 21 has the phase as instructed. However, because the clock of the second radio wave transceiver 2B is ahead of the master clock by Δtb, the phase adjustment unit 24 instructs the transceiver module 22 to use a corrected phase adjustment amount ΦbC = Φb0 - 2πΔtb/P (= π/6 - 2πΔtb/P) that takes into account the phase shift (2πΔtb/P) caused by Δtb, and the high-frequency signal emitted from the communication antenna 21 has the instructed phase. Also, because the clock of the third radio wave transceiver 2C is ahead of the master clock by Δtc, the phase adjustment unit 24 instructs the transceiver module 22 to use a corrected phase adjustment amount ΦcC = Φc0 - 2πΔtc/P (= π/3 - 2πΔtc/P) that takes into account the phase shift (2πΔtc/P) caused by Δtc, and the high-frequency signal emitted from the communication antenna 21 has the instructed phase. In this way, even if there is a time error in the time TM of the first to third radio wave transmitters/receivers 2A to 2C, by adjusting the phase amount to correct the time discrepancy, the wavefronts will be aligned in the direction corresponding to the phase difference of the high-frequency signals emitted from each communication antenna 21, and suitable directivity can be obtained.

As described above, by acquiring spatiotemporal difference information between independently operating radio wave transmitters and receivers 2 and correcting the phase shift of the high-frequency signals, unintended phase shifts in the wave sources that form the composite wave can be reduced, improving the beam quality of the distributed phased array antenna system 1. Note that while Figure 3 only shows a method for correcting temporal errors, the same method applies to correcting spatial errors. By acquiring spatiotemporal difference information between radio wave transmitters and receivers 2 and correcting the phase shift of the high-frequency signals, unintended phase shifts in the wave sources that form the composite wave can be reduced. Of course, when both temporal and spatial errors occur, unintended phase shifts in the wave sources that form the composite wave can be reduced by correcting the phase of the high-frequency signals taking into account both the temporal and spatial error amounts.

The method for acquiring the temporal difference information and the spatial difference information by the time-space difference information acquisition unit 28 is not particularly limited, and any suitable known existing method may be used. For example, when using GNSS (Global Navigation Satellite System), a GNSS satellite can be used as the master clock, and each radio wave transmitter/receiver 2 can perform a correction operation to synchronize with that time. The method of performing time synchronization using GNSS is effective on the ground and in the sky where GNSS signals can reach. Various time synchronization methods, such as IEEE 802.1AS-2011, which uses the propagation delay time between each radio wave transmitter/receiver 2, may also be used. In this case, one of the multiple radio wave transmitters/receivers 2 constituting the distributed phased array antenna system 1 functions as the master clock, or is capable of detecting the relative time deviation from the reference radio wave transmitter/receiver 2. For example, as shown in FIG. 4, the first radio wave transceiver 2A is assumed to have a master clock, and the second radio wave transceiver 2B corrects its internal clock with an error φAB based on the propagation delay time with the first radio wave transceiver 2A. Similarly, the third radio wave transceiver 2C corrects its internal clock with an error φAC based on the propagation delay time with the first radio wave transceiver 2A. Note that the third radio wave transceiver 2C may correct its internal clock with an error φBC based on the propagation delay time with the second radio wave transceiver 2B after clock correction, or may correct its clock with the average value of the errors φAC and φBC. The fourth radio wave transceiver 2D may correct its internal clock with an error φBD based on the propagation delay time with the second radio wave transceiver 2B after clock correction or an error φCD based on the propagation delay time with the third radio wave transceiver 2C after clock correction, or may correct its clock with the average value of the errors φBD and φCD. This method using propagation delay time (RTT) achieves high synchronization accuracy, making it desirable from the perspective of improving beam quality.

Alternatively, rather than correcting the temporal phase shift, the phase shift of the reference oscillator 26 may be adjusted to cancel (i.e., synchronize) the detected phase shift. For example, the radio wave transceiver 2' shown in FIG. 5 includes a frequency-adjustable reference oscillator 26' such as a VCO or OCXO, and the spatiotemporal difference information acquisition unit 28' includes a spatial difference information detector 281 and a temporal difference information detector 282. The temporal difference information detector 282 receives the master clock or information indicating its phase from the synchronization antenna 27 and aligns the excitation phase of the reference oscillator 26' with the master clock based on the received information. More specifically, radio waves of a specific frequency transmitted from the master clock are received by the synchronization antenna 27, and the phase shift between the radio waves and the clock of the reference oscillator 26' is detected by the temporal difference information detector 282. By feeding back the temporal error obtained by the temporal difference information detector 282 to the reference oscillator 26', the reference oscillator 26' can be excited in phase with the master clock. In this way, by synchronizing the oscillation clock of the reference oscillator 26' with the master clock at the phase level, phase deviation can be minimized, improving beam quality. Furthermore, the master clock does not have to be global; local synchronization established only between the multiple radio wave transceivers 2 that make up the distributed phased array antenna system 1 is also acceptable. In this case, it is sufficient to arbitrarily select a radio wave transceiver 2 to serve as the master clock from the multiple radio wave transceivers 2 that make up the distributed phased array antenna system 1.

On the other hand, spatial difference information, i.e., the positional relationship between multiple radio wave transmitters and receivers 2, can be detected using wireless positioning techniques such as distance estimation using GNSS, AoA (Angle of Arrival), AoD (Angle of Departure), and RSSI (Received Signal Strength Indicator). GNSS is particularly effective when placing radio wave transmitters and receivers 2 in locations where GNSS signals can reach, such as on the ground or in the air. Furthermore, when acquiring spatial difference information, rather than using global positions such as latitude, longitude, and altitude, local information that allows the relative positional relationship to be determined only between the multiple radio wave transmitters and receivers 2 that make up the distributed phased array antenna system 1 may also be used. Therefore, positioning techniques that allow the multiple radio wave transmitters and receivers 2 to determine their respective positions using AoA, AoD, RSSI, or the like may also be used. Furthermore, the positional relationship may be determined by measuring the distance between them using the propagation delay time of radio waves. In this case, it is sufficient to know the distance between multiple radio wave transmitters and receivers 2.

The spatial difference information obtained in this way is used to determine the amount of phase shift determined by the transmission/reception control unit 25. For example, if the device is misaligned from the ideal array antenna position, the phase shift due to this spatial error is determined, and the amount of phase shift is adjusted to minimize the impact on beam quality. This phase shift is preferably calculated using methods such as Maxwell's equations, Fresnel-Kirchhoff diffraction theory, and ray tracing, and a value that results in an optimal beam overall is used. Even more simply, the phase shift can be calculated from the distance representing the deviation from the ideal position and the propagation wavelength of the radio waves, and the phase of the high-frequency signal can be adjusted to correct this spatial error.

Furthermore, the radio wave transceiver 2 is not limited to having one radiating element function, and may have N (N is any natural number) communication antennas 21 and transceiver modules 22 corresponding to each transmitting antenna 21. The radio wave transceiver 2" shown in Figure 6 has two sets (N = 2) of radiating element functions, including a first communication antenna 21A and a second communication antenna 21B, and a first transceiver module 22A and a second transceiver module 22B corresponding to the first and second transmitting antennas 21A and 21B, respectively. Furthermore, since the high-frequency signal radiated from the first communication antenna 21A and the high-frequency signal radiated from the second communication antenna 21B are controlled independently, a first radiation control unit 23A and a first phase adjustment unit 24A corresponding to the first transceiver module 22A are provided, and a second radiation control unit 23B and a second phase adjustment unit 24B corresponding to the second transceiver module 22B are provided. In this way, in a radio wave transceiver 2" having multiple radiating element functions, the radiating element functions can be arranged with narrow spacing. For example, if the element spacing is d, the signal wavelength is λ, and the maximum scanning angle is θ, then d/λ = 1/(1 + sin θ), and therefore, by adjusting the element spacing d so that d≦λ/(1 + sin θ), the occurrence of grating lobes can be suppressed.

As described above, the radio wave transmitter/receiver 2, which can acquire temporal difference information and spatial difference information and adjust the phase of the high-frequency signal to correct the spatiotemporal error, can not only use the radiating elements of the array antenna independently, but can also be mounted on a vehicle to form a mobile distributed phased array antenna system. Examples of mobile objects that can be equipped with the radio wave transmitter/receiver 2 include vehicles 3 traveling on the ground (see Figure 7(A)), ships sailing on the sea, aircraft and UAVs (Unmanned Aerial Vehicles) 4 flying in the airspace (see Figure 7(B)), and artificial satellites in orbit. The mobile object and the radio wave transmitter/receiver 2 do not have to be separate entities, but may instead be integrated into one structure.

The mobile distributed phased array antenna system 1' shown in Figure 7(A) has first to eighth radio wave transceivers 2A to 2H mounted on first to eighth vehicles 3A to 3H, respectively. For example, the first radio wave transceiver 2A has the functions of a system control device 11. In this distributed phased array antenna system 1', unlike the distributed phased array antenna system 1 described above, the radio wave transceivers 2 are not fixedly located. Therefore, as the first to eighth vehicles 3A to 3H move, the relative positions of the first to eighth radio wave transceivers 2A to 2H change from moment to moment. However, each radio wave transceiver 2 is provided with a spatiotemporal difference information acquisition unit 28, which can acquire temporal difference information and spatial difference information and emit high-frequency signals with the spatiotemporal error corrected, thereby tracking changes in the spatiotemporal error as the first to eighth vehicles 3A to 3H move. Therefore, even in a mobile distributed phased array antenna system 1' using a moving vehicle 3, it is possible to form a composite wave with a main lobe directed in a specific direction.

If the first through eighth vehicles 3A-3H are autonomous vehicles, the first through eighth vehicles 3A-3H can move in formation so that the first through eighth radio wave transmitters and receivers 2A-2H are ideally positioned as array antennas, thereby maintaining the beam quality of the distributed phased array antenna system 1'. Furthermore, the first through eighth radio wave transmitters and receivers 2A-2H can determine each other's positions from the time-space difference information acquired by the time-space difference information acquisition unit 28, allowing each radio wave transmitter and receiver 2 to determine how to move to achieve the ideal position as an array antenna. Therefore, by providing each radio wave transmitter and receiver 2 with a movement correction instruction means and transmitting movement correction information from the movement correction instruction means to the movement control device of each moving object (e.g., the autonomous driving control device of vehicle 3), the movement control device of each moving object can correct the movement direction and movement speed based on the movement correction information, allowing each moving object to move its radio wave transmitter and receiver 2 to its optimal position. Even if optimal placement of each radio wave transmitter/receiver 2 cannot be achieved by simply correcting the movement of each moving object, each radio wave transmitter/receiver 2 performs phase correction of the high-frequency signal based on the spatiotemporal difference information detected at that time, so the distributed phased array antenna system 1' can minimize degradation of beam quality. Of course, even if proper correction of the movement of the moving object cannot be performed (for example, when a person is driving a vehicle), it may be possible to suppress degradation of the quality of the composite wave by correcting the phase of the high-frequency signal by each radio wave transmitter/receiver 2.

The mobile distributed phased array antenna system 1" shown in Figure 7(B) has first to ninth radio wave transceivers 2A to 2I mounted on first to ninth UAVs 4A to 4I, respectively. For example, the first radio wave transceiver 2A has the functions of a system control device 11. In this distributed phased array antenna system 1", each radio wave transceiver 2 is mounted on a UAV 4, which is a flyable mobile object, making it possible to realize an array arrangement that utilizes space three-dimensionally. For example, the distributed phased array antenna system 1" can easily realize the function of an array antenna with a three-dimensional curved surface, which is difficult to achieve with a large aperture. Furthermore, if the gain of the power amplifiers in the transceiver modules 22 of each radio wave transceiver 2 is not variable, the three-dimensional arrangement of each radio wave transceiver 2 can be fine-tuned to reduce individual variations, thereby suppressing degradation of beam quality.

Furthermore, if the UAV4 is an autonomous flight type, a movement correction instruction means can be provided in each radio wave transceiver 2, and movement correction information can be sent from the movement correction instruction means to the movement control device of each moving body (for example, the autonomous flight control device of the UAV4).If the movement control device of each moving body corrects the movement direction and movement speed based on the movement correction information, each radio wave transceiver 2 can be moved to an optimal position by each moving body.In addition, if each UAV4 is an unmanned aircraft that can be remotely controlled wirelessly, a movement control unit that controls the movement of the moving body can be provided in each radio wave transceiver 2, and the movement control unit of each radio wave transceiver 2 can directly control each UAV4. In this case, in addition to controlling the relative movement of each radio wave transceiver 2 that constitutes the distributed phased array antenna system 1", the movement control unit also performs movement control to correct phase shifts based on the time-space difference information acquired by the time-space difference information acquisition unit 28. Note that until each radio wave transceiver 2 moves to its ideal position through movement control of each UAV 4 by the movement control unit of each radio wave transceiver 2, degradation of beam quality can be suppressed by phase correction of the high-frequency signal by each radio wave transceiver 2.

Furthermore, in the distributed phased array antenna system 1", taking advantage of the ability of each UAV4 to freely form a formation, the radio wave transceivers 2 can be arranged so that, as a whole, they form an unequally spaced array. By adopting an unequally spaced array arrangement, the elements can be arranged with wider spacing than the normal conditions for grating lobe occurrence, making it possible to reduce the number of elements (the number of radio wave transceivers 2 used). Moreover, in an unequally spaced array, an equivalent amplitude distribution can be achieved depending on the element arrangement density, so low side lobes can be achieved even if the amplitude distribution of each radio wave transceiver 2 is constant, thereby further improving the directivity of the distributed phased array antenna system 1".

As described above, mounting radio wave transceivers 2 on a mobile object such as a vehicle 3 or UAV 4 provides a means of transportation for the distributed phased array antenna system 1', 1" as a whole, making it highly convenient. Furthermore, the arrangement of each radio wave transceiver 2 can be changed by moving the mobile object depending on the intended use of the distributed phased array antenna system 1', 1", providing a high degree of flexibility. In addition, mounting radio wave transceivers 2 on a mobile object and adding mobility functionality achieves scalability that can flexibly accommodate changes in the scale of the distributed phased array antenna system 1', 1", making the most of the benefits of a distributed system.

For example, each radio wave transceiver 2 may be equipped with a self-diagnosis unit capable of diagnosing any malfunctions within itself and an autonomous movement control unit capable of arbitrarily controlling the movement of the mobile vehicle on which it is mounted. When a radio wave transceiver 2 constituting the distributed phased array antenna system 1', 1" is determined to have failed by its self-diagnosis unit, it is autonomously moved out of the array configuration by the autonomous movement control unit. If the other radio wave transceivers 2 autonomously adjust their arrangement to fill the gap, the impact of a malfunction in one radio wave transceiver 2 can be minimized and the distributed phased array antenna system 1', 1" can continue to operate. If a standby radio wave transceiver 2 is available, the standby radio wave transceiver 2 may autonomously move to an appropriate position in place of the failed radio wave transceiver 2, thereby quickly restoring the appropriate array configuration. Furthermore, if the self-diagnosis unit of the radio wave transceiver 2 determines that it cannot emit radio waves at its original output but can emit weak radio waves, the impact of the malfunction can be reduced by relocating the radio wave transceiver 2 with weaker radiation capabilities to the outermost position of the array configuration. Furthermore, the arrangement of the radio wave transmitters and receivers 2 may be arranged to form an optimal unevenly spaced array, taking into account variations in the radiation characteristics of each radio wave transmitter and receiver 2. Furthermore, if the autonomous mobile control unit of each radio wave transmitter and receiver 2 has a self-learning function using reinforcement learning, the autonomous mobile control unit of each radio wave transmitter and receiver 2 can self-learn an optimal solution that enables the desired composite wave to be obtained as the distributed phased array antenna system 1', 1" and autonomously rearrange the arrangement taking into account the radiation characteristics of each radio wave transmitter and receiver 2. By providing each radio wave transmitter and receiver 2 with such a self-learning function, degradation of the composite wave of the distributed phased array antenna system 1', 1" can be minimized even when the radiation characteristics of each radio wave transmitter and receiver 2 change due to aging or other reasons.

The distributed phased array antenna systems 1, 1', 1" described above use radio wave transmitters and receivers 2, 2', 2" that can acquire spatiotemporal differential information to suppress degradation in the quality of transmitted beams. Radio wave transmitters and receivers that can acquire spatiotemporal differential information can also be applied to beamforming, which can form receive beams with various directions by combining received signals with appropriate phase shift processing and appropriate weighting (amplitude amplification and attenuation). Figure 8 shows a distributed electromagnetic wave observation data collection system 5 that uses beamforming technology to collect data for observing incoming electromagnetic waves. This distributed electromagnetic wave observation data collection system 5 can be used on its own for radio wave observations, and can also be used as a distributed antenna (e.g., a radio telescope) for observations using Very Long Baseline Interferometry (VLBI).

This distributed electromagnetic wave observation data collection system 5 is composed, for example, of one master mobility 51M and first to eighth slave mobility 51S1 to 51S8 (simply referred to as slave mobility 51S when no particular distinction is needed) located above an arbitrarily set radio wave observation area OA. The first to eighth slave mobility 51S1 to 51S8 and the master mobility 51M each receive radio waves arriving in the radio wave observation area OA, and the first to eighth slave mobility 51S1 to 51S8 transmit the received data (observation data) to the master mobility 51M. After collecting the observation data, the master mobility 51M moves to low altitude at a predetermined data transfer timing (for example, every fixed time or when the accumulated capacity of observation data reaches a predetermined value) and transmits the observation data from a relatively short distance to an observation data collection station CP, which serves as an observation data collection point. In this way, if the master mobility 51M moves to a low altitude to transmit observation data, it is possible to reduce transmission power and perform high-volume communications compared to transmitting directly from the sky to the observation data collection station CP.

The observation data collection station CP that receives the observation data can generate a receive beam by combining the received signals of the observation data collected by the master mobility 51M and the first to eighth slave mobilities 51S1 to 51S8 through appropriate phase shift processing and weighting processing. By varying the combination of phase shift processing and weighting for each received signal, it is possible to generate receive beams with different patterns. In other words, various beam pattern outputs can be obtained from the electromagnetic wave observation data received in a predetermined arrangement by the master mobility 51M and the first to eighth slave mobilities 51S1 to 51S8.

The method for transferring the observation data collected by the master mobility 51M to the observation data collection station is not particularly limited. For example, a data collection vehicle CV that receives the observation data may be kept waiting within the electromagnetic wave observation area OA, and the data may be transmitted directly from the master mobility 51M to the data collection vehicle CV. Alternatively, the master mobility 51M may store the observation data on a recording medium, and when the time for data transfer arrives, an investigator or the like may remove the recording medium containing the stored observation data from the master mobility 51M that has descended to the ground, replace it with a recording medium with sufficient free space, and quickly return the master mobility 51M to its designated position in the sky. Alternatively, the master mobility 51M and the first to eighth slave mobility 51S1 to 51S8 may move to the electromagnetic wave observation area OA, conduct electromagnetic wave observations on the ground, and when the time for data transfer arrives, only the master mobility 51M may move to an observation data collection station CP or the like and transfer the stored observation data.

The master mobility 51M is a UAV4 equipped with a radio transmitter/receiver 52M. On the other hand, the first slave mobility 51S1 is a UAV4 equipped with a radio transmitter/receiver 52S. Similarly, the second slave mobility 51S2, third slave mobility 51S3, fourth slave mobility 51S4, fifth slave mobility 51S5, sixth slave mobility 51S6, seventh slave mobility 51S7, and eighth slave mobility 51S8 are also UAV4 equipped with a radio transmitter/receiver 52S. Below, the slave radio transmitter/receiver 52S and the master radio transmitter/receiver 52M are described with reference to Figure 9.

Figure 9(A) shows the schematic configuration of the radio wave transceiver 52S for the slave mobility 51S. The radio wave transceiver 52S for the slave mobility 51S does not need to be able to emit a beam itself, so Figure 9(A) only shows its receiving function. However, it may also have a phase-correctable transmitting function similar to the radio wave transceivers 2, 2', and 2" described above. A radio wave transceiver that combines a transmitting function that uses spatiotemporal difference information for phase correction during transmission and a receiving function that enables spatiotemporal difference information to be used for phase correction of received signals can be used as both a distributed phased array antenna system 1, 1', and 1" and a distributed electromagnetic wave observation data collection system 5, making it highly versatile. Note that in Figures 9(A) and (B), the same functions as the radio wave transceiver 2 in Figure 1(B), the radio wave transceiver 2' in Figure 5, and the radio wave transceiver 2" in Figure 6 are designated by the same reference numerals and will not be described again.

The radio wave transceiver 52S comprises one communication antenna 21, a time-space difference information acquisition unit 28, a transmission/reception module 22 as a signal receiving unit corresponding to the communication antenna 21, a received data transmission unit 524, and a reference oscillator 26 that generates a reference frequency signal. The signal received by the transmission/reception module 22 is converted to an easy-to-handle intermediate frequency by a downconverter 521, and then converted to a digital signal by an A/D conversion unit 522 and input to the transmission/reception control unit 523S. Note that while beamforming processing using received signals obtained from multiple antennas can be achieved using analog circuits, digital signal processing is more flexible and practical.

Meanwhile, the time-space difference information acquisition unit 28 transmits and receives codes to and from another radio wave transceiver 52S or radio wave transceiver 52M via wireless communication using a synchronization antenna 27 separate from the communication antenna 21, and measures temporal difference information, which is the temporal error between the reference radio wave transceiver 52S, 52M and the radio wave transceiver itself, and spatial difference information, which is the spatial error between the radio wave transceiver's appropriate position relative to the reference radio wave transceiver 52S, 52M and its current position, based on the time difference between the two reference oscillators 26 and the propagation delay time associated with the code transmission and reception, and acquires time-space difference information including the temporal difference information and spatial difference information. This time-space difference information is input to the transmission/reception control unit 523S. Furthermore, if a reference device is selected from the radio wave transceiver 52M in the master mobility 51M and the radio wave transceivers 52S in all slave mobility 51S, and the reference oscillator 26 of the selected reference device is used as the master clock, and the reference oscillators 26 of the other radio wave transceivers 52M, 52S are synchronized, no time error will occur in the received signal, so only spatial difference information may be obtained as spatiotemporal difference information.

The transmission/reception control unit 523S receives the received signal and the spatiotemporal difference information in the manner described above, and passes the digitized received signal and the spatiotemporal difference information at the time of reception as a set to the received data transmission unit 524. The received data transmission unit 524 links the received signal received by the transmission/reception module 22 acting as a receiver, the spatiotemporal difference information at the time of reception, and its own unique information (e.g., an arbitrarily set ID number or a chip ID unique to the transmission/reception module 22) that is set to distinguish itself from the other radio transmitter/receivers 52S and 52M, and transmits this received data to the radio transmitter/receiver 52M of the master mobility 51M via the received data transmission antenna 525.

In addition, if multiple communication antennas 21 and corresponding receiving units (transmission/reception modules 22, downconverter 521, A/D conversion unit 522) are provided, the received data transmission unit 524 may include information that identifies each receiving unit in the radio wave transceiver 52S in the received data. Furthermore, a mobile object position control unit 523a may be provided in the transmission/reception control unit 523, and the UAV4 as a mobile object may be moved to correct its own position based on the spatial difference information of the time-space difference information, thereby controlling the own object to approach the appropriate position.

Figure 9(B) shows the schematic configuration of the radio wave transceiver 52M of the master mobility 51M, to which received data is transmitted from the radio wave transceiver 52S of the slave mobility 51S described above.

The received data received from each radio transmitter/receiver 52S via the observation data receiving antenna 526 and observation data receiving unit is stored as observation data in the observation data storage unit 523b. While it is sufficient for the master mobility 51M to have the function of collecting observation data and transferring it to a data collection point, the radio transmitter/receiver 52S is equipped with a receiving unit (transmit/receive module 22, downconverter 521, A/D conversion unit 522) so that the master mobility 51M can also perform electromagnetic wave observations. Therefore, the received signal received by the radio transmitter/receiver 52M, the time-space difference information, and the unique information of the radio transmitter/receiver 52M are also stored as observation data in the observation data storage unit 523b.

Then, when the transmission/reception control unit 523M determines that the specified data transfer timing has arrived, the mobile unit position control unit 523a instructs the UAV4 as a mobile unit to move to low altitude and transfer the observation data to the data collection station via the observation data transmission unit 528 and observation data transmission antenna 529. Once the observation data transfer is complete, the master mobility 51M returns to the specified observation position and resumes radio wave observation.

In this way, a distributed electromagnetic wave observation data collection system 5 using a master mobility 51M equipped with a radio wave transceiver 52M on a UAV 4 and first through eighth slave mobility 51S1-51S8 equipped with a radio wave transceiver 52S on a UAV 4 can mitigate degradation of beam quality by using the spatiotemporal difference information acquired by each radio wave transceiver 52M, 52S as correction information. That is, the observation data collection station CP that receives the observation data corrects the phase of the received signals of the observation data collected by the master mobility 51M and the first through eighth slave mobility 51S1-51S8 based on the respective spatiotemporal difference information, thereby improving the accuracy of the received signals. By combining the highly accurate received signals through appropriate phase shift processing and appropriate weighting processing, a high-quality receiving beam can be generated. The spatiotemporal difference information acquisition unit 28 provided in the radio wave transceivers 52S, 52M may also acquire the current relative position of the vehicle relative to the reference radio wave transceiver 52S, 52M as spatial difference information. If the observation data collection station CP that receives observation data from the master mobility 51M can determine the relative positions of the other radio wave transmitters and receivers 52S, 52S to the reference radio wave transmitters and receivers 52S, 52S in the observation data for each radio wave reception, it can perform appropriate phase shift processing and appropriate weighting processing that takes into account the relative positional deviation of the radio wave transmitters and receivers 52S, 52M.

Furthermore, while examples have been shown in which the radio wave transmitters and receivers 2, 2', 2", 52M, and 52S capable of acquiring time-space difference information are used in distributed phased array antenna systems 1, 1', and 1" and distributed electromagnetic wave observation data collection systems 5, they can also be used as passive radars or active radars. The larger the aperture diameter of a radar, the higher the resolution, but manufacturing and operating large aperture radars is not easy. However, distributed radars such as the radio wave transmitters and receivers 2, 2', 2", 52M, and 52S described above are easier to manufacture and operate. As an example, Figure 10 shows a distributed synthetic aperture radar system 6 applied to a synthetic aperture radar (SAR) that can generate two-dimensional images by processing the received signals obtained by repeatedly transmitting and receiving pulses while moving in the azimuth direction above an image acquisition area.

The distributed synthetic aperture radar system 6 is composed of, for example, a master synthetic aperture radar device 61M, a first slave synthetic aperture radar device 61S1, a second slave synthetic aperture radar device 61S2, and a phase control device 64. The master synthetic aperture radar device 61M is configured by mounting a radio wave transceiver 62M on a UAV4 as a mobile body. The first slave synthetic aperture radar device 61S1 and the second slave synthetic aperture radar device 61S2 are configured by mounting a radio wave transceiver 62S on a UAV4 as a mobile body. The phase control device 64 is configured by mounting a synthetic aperture radar signal processing device 63 on a UAV4 as a mobile body.

The flight direction of the master synthetic aperture radar device 61M is the azimuth direction, and the master synthetic aperture radar device 61M repeatedly transmits observation pulse signals and receives reflected signals so that an observation area OA serving as an image acquisition area is formed in the ground range direction perpendicular to the azimuth direction. The first slave synthetic aperture radar device 61S1 and the second slave synthetic aperture radar device 61S2 are arranged in a line with the master synthetic aperture radar device 61M in an arrangement direction parallel to the ground range direction, and repeatedly transmit pulse signals and receive reflected signals from the same observation area OA as the master synthetic aperture radar device 61M. In other words, the emitted beam BM of the master synthetic aperture radar device 61M, the emitted beam BS1 of the first slave synthetic aperture radar device 61S1, and the emitted beam MS2 of the second slave synthetic aperture radar device 61S2 are equally emitted toward the observation area OA, gradually shifting the observation area OA in the azimuth direction (slip mapping). Furthermore, the separation distance between the master synthetic aperture radar device 61M, the first slave synthetic aperture radar device 61S1, and the second slave synthetic aperture radar device 61S2 is approximately several tens of centimeters to several meters, and when flying at an altitude of several hundred meters, it can be considered that a pulse signal is being transmitted from a single radiation source from the observation area OA. The number of slave synthetic aperture radar devices 61S is not limited to two, and can be one, or three or more.

The movement control device 64 flies following the master synthetic aperture radar device 61M and the first and second slave synthetic aperture radar devices 61S1 and 61S2, and receives received data from the master synthetic aperture radar device 61M and the first and second slave synthetic aperture radar devices 61S1 and 61S2. The synthetic aperture radar signal processing device 63 receives the received data from the master synthetic aperture radar device 61M and the first and second slave synthetic aperture radar devices 61S1 and 61S2, processes the received data, and generates a two-dimensional image. In addition, as processing performed by the synthetic aperture radar signal processing device 63, for example, the ground range direction is resolved by performing correlation processing between the reflected signal obtained by transmitting a frequency-modulated chirp signal to the observation area OA and the reference signal (a partial section of the chirp pulse), and the azimuth direction is resolved by performing correlation processing between the received signal and a reference wave calculated taking into account the Doppler effect due to the flight speed of the master synthetic aperture radar device 61M and the first and second slave synthetic aperture radar devices 61S1, 61S2.

Next, the detailed functions of the master synthetic aperture radar device 61M, the first to Mth slave synthetic aperture radar devices 61S1 to 61Sm, and the phase control device 64 that make up the distributed synthetic aperture radar system 6 will be explained with reference to Figure 11.

For example, the radio wave transceiver 62M of the master synthetic aperture radar device 61M is equipped with a pulse transceiver unit 622 that transmits and receives pulse signals via a communication antenna 621. It also transmits and receives codes with another radio wave transceiver 62S via wireless communication using a synchronization antenna 6231, which is separate from the communication antenna 621. It is equipped with a spatiotemporal difference information acquisition unit 6232 that measures temporal difference information, which is the temporal error with the reference radio wave transceiver 62S, and spatial difference information, which is the spatial error between the appropriate position of the radio wave transceiver 62M relative to the reference radio wave transceiver 62S and its current position, based on the time difference between the two reference oscillators 624 and the propagation delay time associated with code transmission and reception, and acquires spatiotemporal difference information including the temporal difference information and spatial difference information.

However, in the distributed synthetic aperture radar system 6 of this embodiment, the reference oscillator 624 of the radio wave transceiver 62M in the master synthetic aperture radar device 61M is selected as the master clock, and the reference oscillators 624 of the radio wave transceivers 62S of the first through Mth slave synthetic aperture radar devices 61S1 through 61Sm are synchronized. Therefore, the synchronization control unit 6233 controls the spatiotemporal difference information acquisition unit 6232 to perform phase shift detection using the reference oscillator 624 as the master clock. Therefore, the spatiotemporal difference information acquisition unit 6232 of the radio wave transceiver 62M does not acquire temporal difference information, and only spatial difference information is stored in the spatiotemporal difference information storage unit 625. Furthermore, when spatial difference information of other radio wave transceivers 62S is detected based on the flight position of the master synthetic aperture radar device 61M, the spatiotemporal difference information acquisition unit 6232 of the radio wave transceiver 62M will no longer detect spatial difference information. When storing spatiotemporal difference information in the spatiotemporal difference information storage unit 625, a timestamp is also stored to clarify the timing of storage.

The pulse transmitter/receiver 622 generates a frequency-modulated chirp signal using the chirp pulse generator 6221, and emits the pulse signal from the communication antenna 621, which has been driven to the appropriate emission position by the antenna driver 6222. The reflected signal reflected by the object of observation is received by the reflected signal receiver 6223 and stored in the reflected signal storage unit 626. At this time, a timestamp is added to the reflected signal so that the timing of its storage is clear.

Then, the received data transmission unit 6271 transmits the reflected signal received by the pulse transmission/reception unit 622 and stored in the reflected signal storage unit 626, the space-time difference information stored in the space-time difference information storage unit 625, and the unique information of the radio wave transmitter/receiver 62M as received data to the synthetic aperture radar signal processing device 63 of the movement control device 64. Note that the correspondence between the reflected signal and the space-time difference information can be determined by the synthetic aperture radar signal processing device 63 from their respective timestamps.

Meanwhile, the radio wave transceivers 62S of the first through Mth slave synthetic aperture radar devices 61S1 through 61Sm have substantially the same configuration as the radio wave transceiver 62M in the master synthetic aperture radar device 61M described above. Therefore, the same functions will be assigned the same reference numerals and their explanations will be omitted, with only the differences being described below.

The time-space difference information acquisition unit 6232 of the radio wave transceiver 62S acquires time difference information using the reference oscillator 624 of the radio wave transceiver 62M as the master clock via wireless communication using the synchronization antenna 6231, and the synchronization control unit 6233 controls the reference oscillator 624 to correct the time error. This synchronizes the reference oscillator 624 of the radio wave transceiver 62S with the reference oscillator 624 of the radio wave transceiver 62M. Therefore, the phases of the chirp pulses generated by the chirp pulse generation units 6221 of the radio wave transceivers 62S of the first through Mth slave synthetic aperture radar devices 61S1 through 61Sm can be aligned with high precision. In other words, when pulse signals are simultaneously emitted from the master synthetic aperture radar device 61M and the first through Mth slave synthetic aperture radar devices 61S1 through 61Sm toward the observation area OA, it appears as if a high-power chirp pulse is being emitted from an apparent single antenna, increasing the reception level of the reflected signal from the observation target and reducing the effects of noise. In addition, the reflected signal from the observation target is received simultaneously by the master synthetic aperture radar device 61M and the first through Mth slave synthetic aperture radar devices 61S1 through 61Sm, making it appear as if the reflected signal is received by a large-diameter antenna.

The control functions of the distributed synthetic aperture radar system 6 (such as flight speed and direction control of the communication antenna 621) may be provided by the master synthetic aperture radar device 61M or by the movement control device 64.

The synthetic aperture radar signal processing device 63 of the mobile control device 64 acquires received data from the master synthetic aperture radar device 61M and the first to Mth slave synthetic aperture radar devices 61S1 to 61Sm via the data receiving antenna 631 and wireless communication unit 632. The phase adjustment unit 633 performs phase adjustment on the reflected signals in the received data from the master synthetic aperture radar device 61M to correct spatial errors based on the spatial difference information in the spatiotemporal difference information. This results in received data from the master synthetic aperture radar device 61M with spatial errors corrected based on the spatiotemporal difference information. Similarly, the phase adjustment unit 633 performs phase adjustment on the reflected signals in the received data from the first to Mth slave synthetic aperture radar devices 61S1 to 61Sm to correct spatial errors based on the spatial difference information in the spatiotemporal difference information. This results in received data from the first to Mth slave synthetic aperture radar devices 61S1 to 61Sm with phase shifts corrected based on the spatiotemporal difference information.

As mentioned above, the reflected signals received simultaneously by the master synthetic aperture radar device 61M and the first through Mth slave synthetic aperture radar devices 61S1 through 61Sm are considered to be data from the same observation area OA. By adjusting the phase of these simultaneously acquired reflected signals and combining them to create composite received data, the effects of irregular noise can be reduced. Therefore, if the correlation processing execution unit 634 performs correlation processing on the composite received data and resolves it, it becomes possible to obtain a highly accurate two-dimensional image.

In addition, as shown in Figure 12, a distributed synthetic aperture radar system 6' may be configured in which only the master synthetic aperture radar device 61M emits chirp pulses, and the radio wave transceivers 62S' of the first through Mth slave synthetic aperture radar devices 61S1' through 61Sm' only receive pulses. In this case, the radio wave transceiver 62S' does not need to synchronize the reference oscillator 624 with the master clock, and the pulse transmission function of the pulse transceiver unit 622 need not be used. Alternatively, a pulse receiver 628 may be provided in place of the pulse transceiver unit 622, and the configuration may include only an antenna driver 6281 that drives the communication antenna 621 and a reflected signal resin unit 6282. In this distributed synthetic aperture radar system 6', highly accurate two-dimensional images can be obtained by combining and correlating the reflected signals simultaneously received by the master synthetic aperture radar device 61M and the first through Mth slave synthetic aperture radar devices 61S1' through 61Sm'.

The above describes embodiments of the radio wave transceiver, distributed phased array antenna system, distributed electromagnetic wave observation data collection system, and distributed synthetic aperture radar system according to the present invention, based on the accompanying drawings. However, the present invention is not limited to these embodiments, and may be implemented by adapting publicly known, existing equivalent technical means, provided that the configuration described in the claims is not changed.

REFERENCE SIGNS LIST 1 Distributed phased array antenna system 2 Radio wave transmitter/receiver 21 Communication antenna 24 Phase adjustment unit 26 Reference oscillator 28 Space-time difference information acquisition unit

Claims (6)

A radio wave transceiver usable as an antenna element constituting a phased array antenna system in which a plurality of antenna elements are arranged to obtain a desired directivity,
The system includes N communication antennas (N is any natural number), a space-time difference information acquisition unit, a phase adjustment unit, and a reference oscillator that generates a reference frequency signal,
the time-space difference information acquisition unit transmits and receives codes to and from another radio wave transceiver by wireless communication using a synchronization antenna separate from the communication antenna, and measures temporal difference information, which is a temporal error between the radio wave transceiver serving as a reference and its own device, and spatial difference information, which is a spatial error between its own device's appropriate position and its own device's current position relative to the radio wave transceiver serving as a reference, based on a time difference between the respective reference oscillators and a propagation delay time associated with the code transmission and reception, and acquires time-space difference information including the temporal difference information and the spatial difference information;
the phase-shift adjusting unit adjusts the amount of phase shift of the radio wave radiated from the communication antenna so as to correct the temporal error and/or the spatial error based on the time-space difference information.
A radio wave transmitter/receiver characterized by: A distributed phased array antenna system comprising a plurality of the radio wave transceivers described in claim 1, wherein the phased array antenna system has a specific directivity due to the superposition of radio waves radiated from the communication antennas of each radio wave transceiver. A radio wave transceiver that can be used as each antenna element in a beamforming antenna that can form reception beams with various directions by arranging multiple antenna elements and performing appropriate phase shift processing and appropriate weighting (amplitude amplification/attenuation) processing on the reception signals received by each antenna element and combining the received signals,
The system includes N communication antennas (N is any natural number), a time-space difference information acquisition unit, N signal receiving units corresponding to the respective communication antennas, a received data transmitting unit, and a reference oscillator that generates a reference frequency signal,
the time-space difference information acquisition unit transmits and receives codes to and from another radio wave transceiver by wireless communication using a synchronization antenna separate from the communication antenna, and measures time difference information, which is a time error between the radio wave transceiver serving as a reference and its own device, and spatial difference information, which is a relative position of its own device with respect to the radio wave transceiver serving as a reference, based on a time difference between the mutual reference oscillators and a propagation delay time associated with the code transmission and reception, and acquires time-space difference information including the time difference information and the spatial difference information;
the received data transmitting unit transmits to the outside of the device received data that is linked to the received signal received by the signal receiving unit, the time-space difference information at the reception timing of the signal, and unique information of the device that is set so as to be able to distinguish the device from the other radio wave transceivers;
A radio wave transmitter/receiver characterized by: a plurality of slave mobilities each having the radio wave transceiver according to claim 3 mounted thereon;
a master mobility having a data relay device mounted on a moving body that collects at least the received data transmitted from the plurality of slave mobility devices and transfers the collected received data to a predetermined data collection point;
Including,
A distributed electromagnetic wave observation data collection system characterized in that multiple slave mobilities and the master mobility are placed in an arbitrarily set electromagnetic wave observation area, and only the master mobility that collects the received data from each slave mobility forwards the collected received data to the data collection center as electromagnetic wave observation data. A radio wave transmitter/receiver that can be used as each antenna element in a synthetic aperture radar that has a plurality of antenna elements arranged, and that can generate a two-dimensional image by processing received signals obtained by repeatedly transmitting and receiving pulses while moving in an azimuth direction above an image acquisition area using a synthetic aperture radar signal processing device,
The system includes N communication antennas (N is any natural number), N pulse transmitting/receiving units corresponding to the respective communication antennas, a space-time difference information acquiring unit, a received data transmitting unit, and a reference oscillator that generates a reference frequency signal,
the time-space difference information acquisition unit transmits and receives codes to and from another radio wave transceiver by wireless communication using a synchronization antenna separate from the communication antenna, and measures temporal difference information, which is a temporal error between the radio wave transceiver serving as a reference and its own device, and spatial difference information, which is a spatial error between its own device's appropriate position and its own device's current position relative to the radio wave transceiver serving as a reference, based on a time difference between the respective reference oscillators and a propagation delay time associated with the code transmission and reception, and acquires time-space difference information including the temporal difference information and the spatial difference information;
the received data transmitting unit transmits, as received data, to the synthetic aperture radar signal processing device, the reflected signal received by the pulse transmitting/receiving unit, the time-space difference information acquired by the time-space difference information acquiring unit, and unique information of the own device set to be able to distinguish between the own device and the other radio wave transceivers;
A radio wave transmitter/receiver characterized by: a master synthetic aperture radar device that is mounted on a moving body and that transmits pulse signals to the image acquisition area and receives reflected signals;
M slave synthetic aperture radar devices (M is any natural number) each equipped with the radio wave transmitter/receiver according to claim 5 and configured to transmit pulse signals and receive reflected signals from the same image acquisition area as the master synthetic aperture radar device;
a synthetic aperture radar signal processing device that processes received data from the master synthetic aperture radar device and the slave synthetic aperture radar device to generate a two-dimensional image;
Including,
the slave synthetic aperture radar device acquires the spatiotemporal difference information using the master synthetic aperture radar device as the reference radio wave transceiver, and performs phase adjustment to correct the temporal error based on at least the temporal difference information, thereby transmitting a pulse signal synchronized with the pulse transmission of the master synthetic aperture radar device;
the synthetic aperture radar signal processing device performs phase adjustment on the reflected signals in the received data from the master synthetic aperture radar device and/or the slave synthetic aperture radar device to correct the spatial error based on at least the spatial difference information in the spatiotemporal difference information;
A distributed synthetic aperture radar system comprising: