Radio wave generation device, radio wave detection device, and radio wave transmission / reception system

Abstract

The objective is to provide an OAM radio wave transmission and reception system without increasing the size of the equipment by acquiring OAM radio wave information through localized measurement of OAM radio waves. [Solution] A radio wave generating device comprising a control unit and a radio wave transmitting unit, wherein the control unit includes an OAM radio wave information setting unit that generates a transmitted radio wave signal based on the OAM mode order, a phase change unit that linearly changes the phase of the transmitted radio wave signal with respect to time according to the OAM mode order, and a complex signal generating unit that generates a complex signal from the transmitted radio wave signal whose phase has been changed by the phase change unit and a reference signal, and the radio wave transmitting unit includes a complex signal conversion unit that decomposes the signal components of the complex signal into a real part and an imaginary part, a radio processing unit that generates a radio signal from the complex signal decomposed into a real part and an imaginary part, and an array antenna that transmits the radio signal as an OAM radio wave.

Description

Technical Field

[0001] The present invention relates to a radio wave generating device, a radio wave detecting device, and a radio wave transmission / reception system.

Background Art

[0002] Radio waves are emitted along with the acceleration motion of electrons, and in the process of propagation, they are absorbed and scattered by various atoms, or induce the emission of new radio waves. At that time, radio waves acquire various information through the exchange of momentum in the interaction between radiation and objects, and thus are used not only for communication but also for various applications such as radar imaging and object detection.

[0003] Here, radio waves have two types of angular momentum called spin angular momentum (SAM) and orbital angular momentum (OAM). OAM has theoretically an infinite number of bases regarding the clockwise / counterclockwise rotation direction of the spiral azimuthal phase and its rotation number (OAM mode). Since radio waves with different OAM modes are independent of each other, multiplexing is possible, and thus OAM has attracted attention. In the optical field, it is applied to high-speed high-capacity optical communication, rotating object detection, laser processing, etc., and in the radio wave field, applications to synthetic aperture radar (SAR) and object detection / recognition are being attempted.

[0004] Japanese Patent Publication No. 2018-67791 (Patent Document 1) describes an OAM multiplex receiving device that aims to improve the reception SNR of higher-order OAM modes by minimizing the area of ​​the receiving antenna required to receive signals of multiple OAM modes. The device includes a receiving antenna comprising: a plurality of antenna elements arranged in a pair of positions that are out of phase (phase difference of 180 degrees) with respect to odd-order OAM modes on a concentric ring where the radius increases as the signal strength of the OAM modes exceeds a predetermined value and the absolute value of the order increases; a plurality of antenna elements arranged in a pair of positions that are in phase (phase difference of 0 degrees) with respect to even-order OAM modes; and an antenna element arranged at the center of the ring with respect to the 0th-order OAM mode. The device also includes a combining means that combines the received signals of a pair of antenna elements for odd-order OAM modes in out of phase to output signals for odd-order OAM modes, and combines the received signals of a pair of antenna elements for even-order OAM modes in phase to output signals for even-order OAM modes. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2018-67791 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] Radio waves with OAM properties can be received and various information obtained (reconstructed) by using a receiver that can detect an OAM mode equal to or better than the one at the time of transmission. However, the OAM mode of the transmitter may be unknown to the receiver. In such cases, the receiver must first detect the OAM mode of the OAM radio wave and then process the received radio wave according to that OAM mode. One possible method for detecting the OAM mode of an OAM radio wave on the receiver side is to detect the vortex components of the OAM radio wave using antenna elements arranged around a circle and measure the OAM mode from there.

[0007] However, the intensity distribution of OAM radio waves propagates in a way that expands like a donut beam, and at long distances it has a large spread. Therefore, with this method, the diameter of the circle in the circumferential arrangement must correspond to the expanded beam diameter, which leads to a large device and is not always easy. Patent Document 1 measures long distances where the beam has propagated in a way that expands by controlling the phase of the signals of multiple antenna elements, but this requires multiple antennas and has the problem of making the device large.

[0008] The present invention aims to provide an OAM radio wave transmission and reception system without increasing the size of the device by acquiring OAM radio wave information through local measurement of OAM radio waves. [Means for solving the problem]

[0009] To solve the above-mentioned problems, the present invention provides a radio wave generation device comprising a control unit and a radio wave transmission unit, wherein the control unit includes an OAM radio wave information setting unit that generates a transmitted radio wave signal based on the OAM mode order, a phase change unit that linearly changes the phase of the transmitted radio wave signal with respect to time according to the OAM mode order, and a complex signal generation unit that generates a complex signal from the transmitted radio wave signal whose phase has been changed by the phase change unit and a reference signal, and the radio wave transmission unit includes a complex signal conversion unit that decomposes the signal components of the complex signal into a real part and an imaginary part, a radio processing unit that generates a radio signal from the complex signal decomposed into a real part and an imaginary part, and an array antenna that transmits the radio signal as an OAM radio wave. Furthermore, the radio wave detection device comprises a radio wave receiving unit and a calculation unit, wherein the radio wave receiving unit includes an antenna for receiving OAM radio waves, a radio processing unit for reproducing the received OAM radio waves as a radio signal, and a complex signal conversion unit for converting the reproduced radio signal into a complex signal, and the calculation unit includes an OAM radio wave information calculation unit that calculates the OAM mode order of the OAM radio wave from the frequency characteristics of the complex signal and a phase change coefficient which is the rate by which the phase is changed according to the OAM mode order when transmitting the OAM radio wave. [Effects of the Invention]

[0010] In this invention, by acquiring OAM radio wave information through local measurement of OAM radio waves, it is possible to provide an OAM radio wave transmission and reception system without increasing the size of the device.

[0011] Other issues, configurations, and effects not mentioned above will be clarified by the following description of embodiments for carrying out the invention. [Brief explanation of the drawing]

[0012] [Figure 1A] This figure shows an example of the transmitter configuration in an embodiment of the present invention. [Figure 1B] This figure illustrates the circumferential angle in an embodiment of the present invention. [Figure 2A] This figure illustrates the propagation image of OAM radio waves in an embodiment of the present invention. [Figure 2B] This figure illustrates the image of a receiver in an embodiment of the present invention. [Figure 3] This figure shows an example of the receiver configuration in an embodiment of the present invention. [Figure 4] This figure shows an example of the frequency spectrum in a receiver according to an embodiment of the present invention. [Figure 5] This is an example of a processing flowchart for a transmitter in an embodiment of the present invention. [Figure 6] This is an example of a processing flowchart for a receiver in an embodiment of the present invention. [Figure 7] This figure illustrates structured radio wave information in an embodiment of the present invention. [Figure 8] This figure shows an example of the transmitter configuration in an embodiment of the present invention. [Figure 9] This figure shows an example of the receiver configuration in an embodiment of the present invention. [Figure 10] This figure shows an example of the frequency spectrum in a receiver according to an embodiment of the present invention. [Figure 11] This is an example of a processing flowchart for a transmitter in an embodiment of the present invention. [Figure 12] This is an example of a processing flowchart for a receiver in an embodiment of the present invention. [Figure 13] This is an example of the combination of structured radio wave information and bit information in an embodiment of the present invention. [Figure 14] This is a diagram showing a configuration example of a transmitter in an embodiment of the present invention. [Figure 15] This is a diagram showing a configuration example of a receiver in an embodiment of the present invention. [Figure 16] This is a diagram showing an example of differential calculation of structured radio wave information in an embodiment of the present invention. [Figure 17] This is an example of the combination of structured radio wave information and bit information in an embodiment of the present invention. [Figure 18] This is a diagram for explaining a method of receiving structured radio waves in an embodiment of the present invention.

Mode for Carrying Out the Invention

[0013] Hereinafter, embodiments (examples) for carrying out the present invention will be described in detail with reference to the drawings as appropriate. The examples are illustrative for explaining the present invention, and for the sake of clarity of explanation, omissions and simplifications are made as appropriate. The present invention can be implemented in various other forms. Unless otherwise particularly limited, each component may be singular or plural. Also, components with the same name in each embodiment have the same function.

[0014] The positions, sizes, shapes, ranges, etc. of each component shown in the drawings may not represent the actual positions, sizes, shapes, ranges, etc. in order to facilitate understanding of the invention. For this reason, the present invention is not necessarily limited to the positions, sizes, shapes, ranges, etc. disclosed in the drawings.

[0015] In the following explanation, when describing processing by a program, the program or functional components may be described as the main focus. However, the main hardware component is the processor, or the information processing device (computer) that includes such a processor. The information processing device executes processing according to the program read into memory, using resources such as memory and communication interfaces as appropriate, through the processor. In addition to a CPU, a GPU (Graphical Processing Unit) may also be used as the processor. Furthermore, the processing to realize the function is not limited to software program processing; it can also be implemented using dedicated circuits. Applicable dedicated circuits include FPGAs (Field Programmable Gate Arrays) and ASICs (Application Specific Integrated Circuits). [Examples]

[0016] As shown in Figure 2A, the intensity distribution of radio waves with orbital angular momentum (OAM) propagates in a donut-beam-like shape, and over long distances, it exhibits a large spread. Conventionally, OAM radio wave information was measured by detecting the components of each vortex using antenna elements arranged around the circumference, but this becomes difficult over long distances because the diameter of the circumferential arrangement increases in accordance with the spread of the donut beam. Therefore, in this embodiment, as shown in Figure 2B, it is possible to obtain OAM radio wave information from localized measurements.

[0017] In this embodiment, the radio wave transmission and reception system is configured with a transmitter, which is a radio wave generation device that transmits OAM radio waves corresponding to a set OAM mode order, and a receiver, which is a radio wave detection device that acquires OAM radio wave information (OAM mode order) from the frequency of the received signal.

[0018] [Transmitter description] FIG. 1A is a diagram showing a configuration example of a transmitter 100 according to Embodiment 1 as an example. The transmitter 100 includes a control unit 110 and a radio wave transmission unit 120. The control unit 110 includes an OAM radio wave information setting unit 111 that sets an OAM mode order (±l) as OAM radio wave information and generates an OAM transmission signal, a phase change unit 112 that changes a transmission phase (angular frequency) corresponding to the set OAM mode order, and a complex signal generation unit 113 that generates a transmission complex signal from the phase-changed OAM transmission signal and a reference signal. The control unit 110 may be provided with an input device such as a keyboard, a mouse, or a touch panel (not shown) for setting OAM radio wave information, and a display device such as a display device (not shown) for an operator to confirm the content such as setting information.

[0019] The radio wave transmission unit 120 includes a complex signal conversion unit 121 that converts the phase-changed complex signal into a complex signal of the number of antenna elements, a radio processing unit 122 that converts the complex signal into a radio signal, and a circular array antenna (UCA: Uniform Circular Array) 123 including a plurality of antenna elements that outputs the radio signal as radio waves. In particular, the complex signal conversion unit 121 and the radio processing unit 122 are configured using a technology called software-defined radio (SDR) composed of an analog high-frequency circuit and a digital signal processing unit, but the detailed configuration and the like are omitted.

[0020] Next, the processing of each part of the control unit 110 (OAM radio wave information setting unit 111, phase change unit 112, complex signal generation unit 113) and the radio wave transmission unit 120 (complex signal conversion unit 121, radio processing unit 122) will be described. The processing in each of these parts may be realized by, for example, an arithmetic processing unit (CPU) of a computer device executing a predetermined program stored in a storage device (not shown), or may be configured by a dedicated CPU or hardware, respectively.

[0021] <OAM Radio Wave Information Setting Unit 111> The OAM radio wave information setting unit 111 receives the OAM mode order (±l) of the OAM radio wave to be transmitted and generates an OAM radio signal according to the following equation (Equation 1).

[0022]

number

[0023] Here, "l" in "±l" represents the OAM mode order, and the positive and negative signs indicate whether the OAM radio signal is left-handed or right-handed vortex, respectively. "φ" represents the circumferential angle of the OAM radio signal with respect to the beam axis, as shown in Figure 1B.

[0024] <Phase change section 112> The phase change unit 112 linearly changes the phase of the OAM radio signal (Equation 1) from the OAM radio signal information setting unit 111 with respect to time, according to the OAM mode order. That is, the phase component "lφ" of (Equation 1) is changed over time according to the following equation (Equation 2).

[0025]

number

[0026] Here, "Δω" is a phase change coefficient that indicates the rate at which the phase changes with respect to time, and it is assumed that the transmitter and receiver have the same value recognized in advance. Alternatively, the value of "Δω" may be transmitted from the transmitter to the receiver by other means before the receiver processes the received signal. As a result, the phase change unit 112 outputs a phase-changed OAM radio signal according to the following equation (Equation 3).

[0027]

number

[0028] <Complex signal generation unit 113> The complex signal generation unit 113 generates a complex signal based on the phase-shifted OAM radio wave signal (Equation 3) from the phase shifting unit 112 and a reference signal. The reference signal is given by the following equation (Equation 4).

[0029]

number

[0030] Here, the reference signal is the signal that serves as the reference for the radio wave signal to be transmitted, where "A" represents the amplitude, "ω" represents the angular frequency, and "θ" represents the initial phase. By multiplying the phase-shifted OAM radio wave signal (Equation 3) and the reference signal (Equation 4), a complex signal shown in the following equation (Equation 5) is generated.

[0031]

number

[0032] The reference signal may be received from outside the transmitter 100, or it may be generated within the transmitter 100 by a reference signal generation unit (not shown).

[0033] <Complex signal conversion unit 121> The complex signal conversion unit 121 decomposes the complex signal (Equation 5) from the complex signal generation unit 113 into a real part and an imaginary part (Equation 6).

[0034]

number

[0035] In other words, the real part of the complex signal becomes the I-axis signal of the l-th order (or -l-th order) OAM radio wave, and the imaginary part becomes the Q-axis signal of the l-th order (or -l-th order) OAM radio wave.

[0036] <Wireless processing unit 122> The wireless processing unit 122 generates a wireless signal shown in the following equation (Equation 7) from the I-axis signal and Q-axis signal of the OAM radio wave, which are decomposed by the complex signal conversion unit 121. Here, "fc" is the center frequency. The wireless signal processing unit 122 is composed of a general analog wireless circuit, and details are omitted. The wireless signal (Equation 7) is radiated into space as an OAM radio wave by the circular array antenna 123.

[0037]

number

[0038] [Receiver description] Figure 3 shows an example configuration of a receiver 300 according to Embodiment 1, and the receiver 300 consists of a radio wave receiving unit 310 and a calculation unit 320. The radio wave receiving unit 310 is further composed of an antenna 311, a wireless processing unit 312 and a complex signal conversion unit 313, and the calculation unit 320 has an OAM radio wave information calculation unit 321.

[0039] The antenna 311 can be a single-structure antenna, such as a patch antenna. The radio processing unit 312 and the complex signal conversion unit 313 are configured using SDR technology, similar to the radio wave transmission unit 120 of the transmitter 100, but the detailed configuration will be omitted. The OAM radio wave information calculation unit 321 performs the processing described later by having the calculation unit 320 execute a predetermined program.

[0040] Antenna 311 receives OAM radio waves, which are then regenerated as radio signals by the radio processing unit 312 using a known method, and subsequently converted into complex signals by the complex signal conversion unit 313 (Equation 8: for right-handed vortex, Equation 9: for left-handed vortex).

[0041]

number

[0042]

number

[0043] Here, "k" is the wavenumber and "r" is the propagation distance.

[0044] The OAM radio wave information calculation unit 321 analyzes the obtained complex signal and calculates the OAM mode order "±l" set during transmission by the transmitter 100. That is, the OAM radio wave information calculation unit 321 performs an FFT (Fast Fourier Transform) analysis on the obtained complex signal to obtain the frequency spectrum shown in Figure 4. In Figure 4, the horizontal axis represents frequency and the vertical axis represents spectral intensity.

[0045] Spectrum 400 is the spectrum when no phase change is applied by the phase change unit 112 of the transmitter 100, spectrum 401 is the spectrum when "+l", i.e., the OAM mode order "l" of the left vortex is set in the phase change unit 112, and spectrum 402 is the spectrum when "-l", i.e., the OAM mode order "l" of the right vortex is set.

[0046] Here, the frequency of spectrum 400 is the angular frequency (ω=2πf), and since the frequency of spectrum 401 and spectrum 402 obtained from the FFT analysis is "Δωl", by making the angular frequency (ω) and the phase change coefficient "Δω" known to the transmitter 100 in advance, it is possible to determine the OAM mode order "l" and whether it is a left vortex "+" or a right vortex "-".

[0047] By recognizing the OAM mode order, the receiver 300 can acquire various information contained in the received OAM radio waves, enabling wireless communication, etc. However, the specific methods and configurations are omitted here.

[0048] [Processing flowchart] Figure 5 shows an example of a processing flowchart for transmitter 100. In step S501, the OAM radio wave information setting unit 111 receives the OAM mode order of the OAM radio wave to be transmitted and generates an OAM radio signal based on it. In step S502, the phase change unit 112 linearly changes the phase of the OAM radio signal with respect to time and calculates the amount of phase change. In step S503, the complex signal generation unit 113 generates a complex signal based on the phase-shifted OAM radio wave signal and the reference signal. In step S504, the complex signal conversion unit 121 and the wireless processing unit 122 generate a wireless signal. In step S505, the circular array antenna 123 transmits a radio signal as an OAM radio wave.

[0049] Figure 6 shows an example of a processing flowchart for receiver 300. In step S601, antenna 311 receives the OAM signal. In step S602, the wireless processing unit 312 reproduces the received OAM radio wave as a wireless signal. In step S603, the complex signal conversion unit 313 converts the regenerated wireless signal into a complex signal. In step S604, the OAM radio wave information calculation unit 321 performs an FFT analysis and calculates the OAM mode order from the frequency information and phase change coefficient.

[0050] As explained above, in this embodiment, the transmitter changes the transmission phase in response to the OAM mode, and the receiver obtains the OAM mode order from the frequency of the received signal. Therefore, the receiver only needs to receive locally rather than over the entire spread of radio waves, making it possible to realize an OAM radio wave transmission and reception system without increasing the size of the device. [Examples]

[0051] Since radio waves with different OAM modes are independent of each other, multiplexing them is expected to be applicable to expanding the communication capacity of information communications. Therefore, it is effective to generate OAM radio waves with a geometric structure (referred to as structured radio waves) by combining different OAM modes. However, in order to receive structured radio waves and process them as meaningful signals, it is necessary to first obtain information about the geometric structure of the received structured radio waves (structured radio wave information).

[0052] On the other hand, structured radio waves are generated by mixing and controlling radio waves that have orbital angular momentum (OAM). Their intensity distribution propagates in a donut-beam-like manner, similar to Example 1. Therefore, this example aims to acquire structured radio wave information from local measurements.

[0053] In this embodiment, the structured radio wave is a superposition of a left-handed (left-vortex) OAM and a right-handed (right-vortex) OAM with OAM mode order "l" = ±1, and as shown in Figure 7, the azimuth angle (2τ) and elevation angle (2ε) of the Poincaré sphere are expressed as structured radio wave information. That is, the two modes "±l" of orbital angular momentum are used as the basis, and the azimuth angle and elevation angle represented by the Poincaré sphere with this basis as the pole are used as structured radio wave information.

[0054] The transmitter and receiver according to this embodiment will be described below, but some parts that are the same as in Embodiment 1 will be omitted or simplified.

[0055] [Transmitter description] Figure 8 shows an example configuration of a transmitter 800 according to Embodiment 2, which comprises a control unit 810 and a radio wave transmission unit 820. The control unit 810 includes a structured radio wave setting unit 811 that generates a structured radio wave signal by setting the azimuth angle (2τ) and elevation angle (2ε) as structured radio wave information and the OAM mode order (±l) as OAM radio wave information; a phase change unit 812 that changes the transmission phase (angular frequency) of the structured radio wave; and a complex signal generation unit 813 that generates a transmission complex signal from the phase-changed structured radio wave signal and a reference signal.

[0056] The radio wave transmission unit 820 includes a complex signal conversion unit 821 that converts a phase-shifted complex signal into a complex signal corresponding to the number of antenna elements, a radio processing unit 822 that converts the complex signal into a radio signal, and a circular array antenna (UCA) 823 equipped with multiple antenna elements that output the radio signal as radio waves. Similar to Embodiment 1, the complex signal conversion unit 821 and the radio processing unit 822 are configured as software-defined radio (SDR).

[0057] Next, the details of each part of the control unit 810 (structured radio wave setting unit 811, phase change unit 812, complex signal generation unit 813) and the radio wave transmission unit 820 (complex signal conversion unit 821, wireless processing unit 822) will be described. The processing in each of these parts may be realized, for example, by the arithmetic processing unit (CPU) of a computer device executing a predetermined program stored in a storage device (not shown), or each may be configured by a dedicated CPU or hardware.

[0058] <Structured radio wave setting section 811> The structured radio wave setting unit 811 uses the two modes "±l" of orbital angular momentum as a basis, and generates a structured radio wave signal shown by the following matrix (Equation 10) based on the azimuth angle (2τ) and elevation angle (2ε) represented by a Poincaré sphere with the basis as the pole.

[0059]

number

[0060] <Phase change section 812> In the phase change unit 812, the phase of the structured radio signal (Equation 10) from the structured radio setting unit 811 is changed linearly with respect to time according to the OAM mode order, as shown in the following equation (Equation 11).

[0061]

number

[0062] Here, "l" is the OAM mode, and "Δω" is the phase change coefficient, which indicates the rate at which the phase changes with respect to time, and it is assumed that the transmitter and receiver recognize the same value in advance. Alternatively, these values ​​may be transmitted from the transmitter to the receiver by other means before the receiver processes the received signal.

[0063] <Complex signal generation unit 813> The complex signal generation unit 813 generates a complex signal based on the phase-shifted structured radio signal (Equation 11) from the phase-shifting unit 812 and a reference signal. The reference signal is given by (Equation 4) as in Example 1, and by multiplying the phase-shifted structured radio signal (Equation 11) and the reference signal (Equation 4), the complex signal shown in the following equation (Equation 12) is generated.

[0064]

number

[0065] <Complex signal conversion unit 821> The complex signal conversion unit 821 decomposes the complex signal (Equation 12) from the complex signal generation unit 813 into a real part and an imaginary part (Equation 13).

[0066]

number

[0067] Here, "φ" is the circumferential angle of the structured radio wave with respect to the beam axis, and N is the number of antenna elements in the circular array antenna 823.

[0068] <Wireless Processing Unit 822> The wireless processing unit 822 generates a wireless signal shown in (Equation 7) from the I-axis signal and Q-axis signal of the structured radio wave, which are decomposed by the complex signal conversion unit 821. The wireless signal (Equation 7) is radiated into space as structured radio wave by the circular array antenna 823.

[0069] [Receiver description] Figure 9 shows an example configuration of a receiver 900 according to Embodiment 2, and the receiver 900 consists of a radio wave receiving unit 910 and a calculation unit 920. The radio wave receiving unit 910 is further composed of an antenna 911, a wireless processing unit 912 and a complex signal conversion unit 913, and the calculation unit 920 has a phase correction unit 921 and a structured information calculation unit 922.

[0070] The radio wave receiving unit 910 is the same as the radio wave receiving unit 310 in Embodiment 1, and the antenna 911, wireless processing unit 912, and complex signal conversion unit 913 correspond to the antenna 311, wireless processing unit 312, and complex signal conversion unit 313, respectively.

[0071] Similar to Embodiment 1, the antenna 911 receives structured radio waves, which are then regenerated as radio signals by the wireless processing unit 912 and subsequently converted into complex signals by the complex signal conversion unit 913.

[0072] The phase correction unit 921 changes the frequency of the complex signal from the complex signal conversion unit 913 according to the OAM mode order using the correction signals shown in the following equations (Equation 14: for right vortex, Equation 15: for left vortex).

[0073]

number

[0074]

number

[0075] In other words, the phase change unit 921 changes the frequency based on "Δω" in the phase change unit 812 of the transmitter 810. The phase correction unit 921 outputs a phase-corrected complex signal (Equation 16) as a signal for detecting the right vortex component, and a phase-corrected complex signal (Equation 17) as a signal for detecting the left vortex component.

[0076]

number

[0077]

number

[0078] The structured information calculation unit 922 calculates structured radio wave information (ε, τ) from the phase-corrected complex signal. That is, the structured information calculation unit 922 performs an FFT analysis on the phase-corrected complex signal to obtain a frequency spectrum as shown in Figure 10 (in the case of correction for left-handed vortex component detection). In Figure 10, the horizontal axis is frequency (phase) and the vertical axis is intensity. Spectrum 1000 is the spectrum when no phase change is applied by the phase change unit 812 of the transmitter 800, spectrum 1001 is the spectrum of the right vortex, and spectrum 1002 is the spectrum of the left vortex.

[0079] Here, the intensity of the structured radio waves (A R : Right-handed vortex, A L : left vortex) and phase (φ R :Right vortex, φ L The left vortex is given by the following equations (Equation 18: for right vortices, Equation 19: for left vortices).

[0080]

number

[0081]

number

[0082] From this, the structured radio wave information (ε, τ) can be calculated using the following equation (Equation 20).

[0083]

number

[0084] The structured information calculation unit 922 can calculate the elevation angle (ε) of the structured radio wave information by substituting the intensity and phase of the structured radio waves (right vortex, left vortex) obtained by the above-mentioned FFT analysis into (Equation 20). However, the angular frequency "ω" and the phase change coefficient "Δω" or OAM mode order "l" must be made known to the transmitter 800 in advance. This information may be transmitted from the transmitter 800 to the receiver 900 by other means. Furthermore, in order to calculate the azimuth angle (τ) of the structured radio wave information, the circumferential angle (φ) of the receiving element position must also be known (or the coordinate system may be set to "φ=0").

[0085] [Processing flowchart] Figure 11 shows an example of a processing flowchart for transmitter 800. In step S1101, the structured radio wave setting unit 811 accepts the setting of azimuth angle and elevation angle as structured radio wave information for the structured radio wave to be transmitted.

[0086] In step S1102, the structured radio wave setting unit 811 sets two OAM mode orders to be transmitted and generates a structured radio wave signal based on them. In step S1103, the phase change unit 812 linearly changes the phase of the structured radio signal with respect to time according to the OAM mode order and calculates the amount of phase change. In step S1104, the complex signal generation unit 813 generates a complex signal based on the phase-shifted structured radio signal and the reference signal. In step S1105, the complex signal conversion unit 821 and the wireless processing unit 822 generate a wireless signal. In step S1106, the circular array antenna 823 transmits the radio signal as structured radio waves.

[0087] Figure 12 shows an example of a processing flowchart for receiver 900. In step S1201, the OAM mode order set when transmitting structured radio waves from the transmitter is received from the transmitter and set in the structured information calculation unit 922. In step S1202, the circumferential angle (φ) of the receiving element position of the receiver 900 is set in the structured information calculation unit 922. In step S1203, antenna 911 receives structured radio waves. In step S1204, the wireless processing unit 912 reconstructs the received structured radio wave as a wireless signal. In step S1205, the complex signal conversion unit 913 converts the regenerated wireless signal into a complex signal. In step S1206, the phase correction unit 921 performs phase correction according to the OAM mode order. In step S1207, the structured information calculation unit 321 performs an FFT analysis and calculates the azimuth angle and elevation angle, which are structured information, from the obtained amplitude and phase information.

[0088] As explained above, according to this embodiment, when acquiring the geometric information of structured radio waves with a receiver, it is only necessary to receive it locally rather than across the entire spread of radio waves. Therefore, an OAM (structured radio wave) transmission and reception system can be realized without increasing the size of the equipment. [Examples]

[0089] This embodiment describes an application example of applying the structured radio wave transmission and reception system of Example 2 to information communication. Specifically, this embodiment utilizes the fact that the structured radio wave information (τ, ε) set on the transmitter side in Example 2 can be restored on the transmitter side, and performs information communication by transmitting and receiving the combination of structured radio wave information (τ, ε) as symbol information associated with the bit information to be transmitted.

[0090] For example, when the transmitter transmits one of the 2-bit pieces of information [00,01,10,11], as shown in Figure 13, it transmits structured radio waves containing symbol information that associates the combinations of structured radio wave information (τ,ε) with (0,0), (π / 2,0), (0,π / 4), and (0,-π / 4). Then, for example, if the receiver receives the combination of structured radio wave information (τ,ε) as (0,π / 4), it can recognize that the bit information

[10] has been transmitted.

[0091] Specifically, on the transmitter side, as shown in Figure 14, a symbol information setting unit 1401 is provided in front of the transmitter 800 (Figure 8) of Embodiment 2. The bit information to be transmitted is converted into structured radio wave information (τ,ε) according to a correspondence rule such as that shown in Figure 13, and input to the structured radio wave setting unit 811 as elevation angle (2ε) and azimuth angle (2τ). On the receiver side, as shown in Figure 15, a symbol information analysis unit 1501 is provided behind the receiver 900 of Embodiment 2. The elevation angle (ε) and azimuth angle (τ) output from the structured information calculation unit 922 are similarly converted into bit information according to a correspondence rule such as that shown in Figure 13, thereby making it possible to obtain the transmitted bit information as received bit information.

[0092] By the way, as explained in Example 2, in order to calculate the azimuth angle (τ) of the structured radio wave information on the receiver side, it was necessary that the circumferential angle (φ) of the receiving element position be known. That is, in (Equation 20), if the circumferential angle (φ) is unknown when calculating the azimuth angle (τ), the azimuth angle (τ) will be an offset value (a value with "+lφ"), and it will not be possible to accurately calculate the value of the azimuth angle (τ) at the time of transmission.

[0093] Therefore, instead of the receiver calculating the value of the azimuth angle (τ) itself, it may be possible to detect the change in the azimuth angle (τ) (Δτ) and associate (Δτ, ε) with the bit information. In other words, by calculating the change in the azimuth angle (τ) including the offset (difference), the offset is canceled out, so even if the circumferential angle (φ) is unknown to the receiver, the transmitted bit information can be restored as received bit information.

[0094] For example, as shown in Figure 16, if the transmitter changes the structured radio wave information (τ,ε) of the transmitted signal from (π / 8,0) to (5π / 8,0), the receiver calculates the difference (Δτ,ε) and the offset cancels out, resulting in (π / 2,0). In this case, if (Δτ,ε) is associated with bit information as shown in Figure 17, the receiver can detect that the bit information

[01] has been transmitted.

[0095] In this example as well, a symbol information setting unit 1401 and a symbol information analysis unit 1501, as shown in Figures 14 and 15, can be provided to convert the transmitted signal into symbol information and to restore the transmitted signal from the received symbol information.

[0096] As explained above, this embodiment transmits and receives symbol information by associating a combination of structured radio wave information (τ,ε) with the bit information to be transmitted, making it applicable to information communication. [Examples]

[0097] As described in Examples 2 and 3, in order to calculate the azimuth angle (τ) of structured radio wave information on the receiver side, the circumferential angle (φ) of the receiving element position must be known, and for this purpose, the axial direction of the beam axis must be detected on the receiver side. However, when the distance between the transmitter and receiver is long, it is not always easy to detect the axial direction of the beam axis at the receiver. Therefore, in this embodiment, as another application example of Examples 2 and 3, a configuration in which the axial direction of the beam axis is detected on the receiver side will be described.

[0098] As shown in (Equation 20), the azimuth angle (τ) depends on the circumferential angle (φ). Therefore, two receivers (receiver 1 and receiver 2) are prepared, and structured radio waves are received while receiver 2 is rotated around receiver 1, as shown in Figure 18. Receivers 1 and 2 reconstruct the azimuth angle (τ) and elevation angle (ε) of the received structured radio waves. When the reconstructed information (τ,ε) matches in both receiver 1 and receiver 2, their relative positions indicate that their circumferential angles (φ) are the same, and at this point, it can be estimated that the beam axis lies on the straight line connecting receiver 1 and receiver 2.

[0099] Alternatively, instead of rotating receiver 2 around receiver 1, multiple receivers 2 may be arranged around receiver 1, or receiver 2 may be moved in multiple directions near receiver 1.

[0100] Alternatively, receivers 1 and 2 may be equipped with self-position detection devices, etc., and the position information from receiver 2 and the structured radio wave information calculated by receiver 2 may be transmitted to receiver 1, and the calculations described above may be performed by the calculation unit 920, etc., of receiver 1. Alternatively, a separate calculation device may receive the calculation results of the structured radio wave information from receivers 1 and 2 and perform the calculations described above. Furthermore, a mobile device, etc., may be provided for receiver 2, and the position information of receiver 2 may be obtained from the mobile device, etc.

[0101] In this embodiment, the circumferential angle of receiver 1 can be detected by using receiver 2 during initial setup and adjustment, for example, when installing receiver 1. Therefore, during subsequent actual operation of receiver 1, the azimuth angle (τ) can be detected not only as a change but also in absolute coordinates (even without using receiver 2).

[0102] As explained above, according to this embodiment, the receiver can estimate the direction of the beam axis.

[0103] Furthermore, each configuration in the above-described embodiments can be modified as appropriate to the extent possible. For example, it is possible to implement the components of one embodiment in a different way, as long as it does not contradict the intent of the embodiment, or to add components of one embodiment to another embodiment, or to replace components of another embodiment. [Explanation of symbols]

[0104] 100: Transmitter 110: Control Unit 111: OAM Radio Wave Information Setting Section 112: Phase change section 113: Complex signal generation unit 120: Radio wave transmission unit 121: Complex signal conversion unit 122: Wireless Processing Unit 123: Circular array antenna 300: Receiver 310: Radio wave receiving unit 311: Antenna 312: Wireless Processing Unit 313: Complex signal conversion unit 320: Arithmetic section 321:OAM radio wave information calculation section

Claims

1. A radio wave generating device comprising a control unit and a radio wave transmitting unit, The control unit, An OAM radio wave information setting unit that generates a transmitted radio wave signal based on the OAM mode order, A phase change unit that linearly changes the phase of the transmitted radio signal with respect to time according to the OAM mode order, A complex signal generation unit generates a complex signal from a transmitted radio wave signal whose phase has been changed by the phase change unit and a reference signal. It has, The aforementioned radio wave transmitting unit is A complex signal conversion unit that decomposes the signal components of the complex signal into a real part and an imaginary part, A wireless processing unit that generates a wireless signal from the complex signal decomposed into a real part and an imaginary part, An array antenna that transmits the aforementioned wireless signal as an OAM radio wave, A radio wave generating device characterized by having the following features.

2. A radio wave detection device comprising a radio wave receiving unit and a calculation unit, The aforementioned radio wave receiving unit is An antenna for receiving OAM radio waves, A wireless processing unit that reproduces the received OAM radio waves as a wireless signal, A complex signal conversion unit that converts the regenerated wireless signal into a complex signal, It has, The aforementioned arithmetic unit, An OAM radio wave information calculation unit calculates the OAM mode order of the OAM radio wave from the frequency characteristics of the complex signal and the phase change coefficient, which is the ratio of the phase change according to the OAM mode order when the OAM radio wave is transmitted. A radio wave detection device characterized by having the following features.

3. A radio wave transmission and reception system comprising a radio wave generating device according to claim 1 and a radio wave detection device according to claim 2.

4. A radio wave transmission and reception system according to claim 3, The radio wave detection device receives the phase change coefficient from the radio wave generation device. A radio wave transmission and reception system characterized by the following features.

5. A radio wave generating device comprising a control unit and a radio wave transmitting unit, The control unit, A structured radio wave setting unit that generates a transmitted radio wave signal based on two OAM mode orders and the azimuth and elevation angles represented by a sphere with the base as the pole, A phase change unit that linearly changes the phase of the transmitted radio signal with respect to time according to the OAM mode order, A complex signal generation unit generates a complex signal from a transmitted radio wave signal whose phase has been changed by the phase change unit and a reference signal. It has, The aforementioned radio wave transmitting unit is A complex signal conversion unit that decomposes the signal components of the complex signal into a real part and an imaginary part, A wireless processing unit that generates a wireless signal from the complex signal decomposed into a real part and an imaginary part, An array antenna that transmits the aforementioned wireless signal as an OAM radio wave, A radio wave generating device characterized by having the following features.

6. A radio wave detection device comprising a radio wave receiving unit and a calculation unit, The aforementioned radio wave receiving unit is An antenna that receives OAM radio waves generated based on two OAM mode orders and the azimuth and elevation angles represented by a sphere with the base as the pole, A wireless processing unit that reproduces the received OAM radio waves as a wireless signal, A complex signal conversion unit that converts the regenerated wireless signal into a complex signal, It has, The aforementioned arithmetic unit, A phase correction unit that changes the frequency of the complex signal according to the OAM mode order, A structured information calculation unit calculates the azimuth angle and elevation angle from the phase and intensity of the phase-shifted complex signal, A radio wave detection device characterized by having the following features.

7. A radio wave detection device according to claim 6, The phase correction unit determines the amount by which to change the frequency based on a phase change coefficient, which is the ratio of the phase change according to the OAM mode order when transmitting the OAM radio wave. A radio wave detection device characterized by the following features.

8. A radio wave transmission and reception system comprising a radio wave generating device according to claim 5 and a radio wave detection device according to claim 7.

9. A radio wave transmission and reception system according to claim 8, The radio wave detection device receives the phase change coefficient or the OAM mode order from the radio wave generation device. A radio wave transmission and reception system characterized by the following features.

10. A radio wave transmission and reception system according to claim 8, The radio wave generation device has a symbol information setting unit that inputs symbol information corresponding to bit information to the combination of the azimuth angle and the elevation angle to the structured radio wave setting unit. The radio wave detection device has a symbol information analysis unit that acquires bit information from the combination of the azimuth angle and the elevation angle output from the structured information calculation unit. A radio wave transmission and reception system characterized by the following features.

11. A radio wave transmission and reception system according to claim 10, The symbol information setting unit and the symbol information analysis unit use the amount of change in the azimuth angle instead of the azimuth angle. A radio wave transmission and reception system characterized by the following features.

12. A radio wave transmission and reception system according to claim 8, The system further comprises a second radio wave detection device that receives the OAM radio waves while changing its position around the aforementioned radio wave detection device. A radio wave transmission and reception system characterized by estimating the direction of the beam axis of the OAM radio wave transmitted from the radio wave generator from the positional relationship between the radio wave detection device and the second radio wave detection device when the azimuth angle and elevation angle calculated in the first radio wave detection device and the second radio wave detection device match.

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