Measurement method, measurement system and program for measuring antenna radiation characteristic

Abstract

To make it possible to measure a radiation characteristic of a large-diameter antenna.SOLUTION: A measurement method has: a radio wave output step of causing a radio wave of prescribed output intensity to be output from a measured antenna of a measurement object; a flying object measurement step of causing measurement of a position of the flying object, a posture of the flying object, and intensity of the radio wave output from the measured antenna to be implemented, while causing the flying object to fly so as to pass through a plurality of measurement positions arrayed in a virtual plane facing the measured antenna in a direction where the measured antenna outputs the radio wave; and a calculation step of calculating a radiation characteristic of the measured antenna on the basis of position information, posture information, and radio wave intensity information.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present invention relates to a measurement method, a measurement system, and a program for measuring radiation characteristics of an antenna. [Background technology]

[0002] Known methods for determining the radiation characteristics of an antenna include a method in which another antenna is installed at a certain distance, and the radiation characteristics are measured while the installed antenna is moved to obtain the near-field characteristics by planar scanning (see, for example, Patent Documents 1 to 3), and a measurement method using total solid angle integration (see, for example, Non-Patent Documents 1 to 3). However, measuring the near-field and far-field characteristics of a reflector antenna with a diameter greater than a certain level requires large, special equipment (see, for example, Non-Patent Documents 4 and 5). Therefore, a method is known in which the radiation characteristics of a large-diameter antenna are confirmed by measuring partial components (see, for example, Patent Document 2). It is also known that measurement results such as reflector surface error are used to maintain antenna characteristics after installation (see, for example, Patent Document 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3658225 [Patent Document 2] Japanese Patent Application Laid-Open No. 2000-199773 [Patent Document 3] Patent No. 5168940 [Non-patent literature]

[0004] [Non-Patent Document 1] Gordon, Joshua A., et al. "Millimeter-wave near-field measurements using coordinated robotics." IEEE Transactions on Antennas and Propagation, vol.63, no.12, pp.5351-5362, 2015. [Non-patent document 2] Y. Tanaka et al., "Photonics-Based Near-Field Measurement and Far-Field Characterization for 300-GHz Band Antenna Testing," in IEEE Open Journal of Antennas and Propagation, vol. 3, pp. 24-31, 2022. [Non-patent document 3] Institute of Electronics, Information and Communication Engineers Knowledge Base, Antenna Measurement, https: / / www.ieice-hbkb.org / files / 04 / 04gun_02hen_09.pdf [Non-patent document 4] Teshirogi, "Current Status and Trends of Antenna Near-Field Measurements," Communications Research Laboratory Quarterly Report, vol. 34, no. 172, pp. 101-110, 1988. https: / / www.nict.go.jp / publication / kiho / 34 / 172 / Kiho_Vol34_No172_pp101-110.pdf [Non-Patent Document 5] Mitsuaki Orikasa, “Development and Current Status of Large Satellite Antennas”, 2015 VLBI Symposium. http: / / vlbi.sci.ibaraki.ac.jp / vcon15 / proc / Orikasa.pdf [Non-patent document 6] ITU-R SA.509-3<https: / / www.itu.int / dms_pubrec / itu-r / rec / sa / R-REC-SA.509-3-201312-I!!PDF-E.pdf> Summary of the Invention [Problem to be solved by the invention]

[0005] There are various challenges in measuring the radiation characteristics of large-diameter reflector antennas. Patent Document 1 proposes a device for quickly measuring the radiation characteristics of small antennas, but applying this to large-diameter reflector antennas is difficult due to the large size of the device. Patent Document 2 can measure the reflector characteristics of a large-diameter reflector antenna before assembly, but cannot measure the antenna characteristics after assembly and installation. Patent Document 3 proposes a method for minimizing reflector surface error for an installed reflector antenna using signals arriving from external sources such as satellites, but measuring the antenna characteristics themselves is difficult. Non-Patent Documents 4 and 5 describe methods for measuring the near-field characteristics of an antenna using large-scale, specialized equipment, but measuring the antenna after installation is difficult. Furthermore, far-field characteristics have only been confirmed by calculation, and actual measurement is difficult.

[0006] The present invention has been made in consideration of these points, and has as its object to make it possible to easily measure the radiation characteristics of a large-diameter antenna. [Means for solving the problem]

[0007] In a first aspect of the present invention, there is provided a measurement method for measuring the radiation characteristics of an antenna, the measurement method comprising: a radio wave output step of outputting radio waves of a predetermined output strength from a target antenna to be measured; an aircraft measurement step of flying an aircraft so that the aircraft passes through a plurality of measurement positions arranged on a virtual plane opposite the target antenna in the direction in which the antenna to be measured outputs radio waves, and measuring the position of the aircraft, the attitude of the aircraft, and the strength of the radio waves output from the target antenna; an information acquisition step of acquiring position information indicating the position of the aircraft, attitude information indicating the attitude of the aircraft, and radio wave strength information indicating the strength of the radio waves output from the target antenna, measured by the aircraft at the plurality of measurement positions; and a calculation step of calculating the radiation characteristics of the target antenna based on the position information, the attitude information, and the radio wave strength information.

[0008] In the flying object measurement step, the flying object performs measurements of the position of the flying object, the attitude of the flying object, and the strength of the radio waves output from the antenna to be measured multiple times while flying along a predetermined flight path, and the calculation step may further include an identification step of identifying a representative value of the radio wave strength measurement results at each of the measurement positions from among the multiple radio wave strength measurement results based on the position information, and a correction step of correcting the identified representative value of the radio wave strength measurement results based on the position information and the attitude information.

[0009] The plurality of measurement positions may be positions of intersections of a plurality of vertical lines and a plurality of horizontal lines when a grid having a plurality of vertical lines and a plurality of horizontal lines is virtually drawn on the virtual plane.

[0010] The plurality of measurement positions may be positions of the intersections when the grid is virtually drawn on a plurality of the imaginary planes at different distances from the antenna under test.

[0011] The imaginary plane may be farther away from the antenna under test than a first distance, and the first distance may be a distance at which a near field begins.

[0012] The first distance may be expressed by Z1 in the following equation, where D is the diameter of the antenna under test and λ is the wavelength of the radio wave output from the antenna under test. TIFF2025141705000002.tif2158

[0013] The imaginary plane may be located in a range farther from the antenna under test than the first distance and closer than a second distance, and the second distance may be a distance that is a boundary between a near field and a far field.

[0014] The second distance may be represented by Z2 in the following equation: TIFF2025141705000003.tif1344

[0015] The imaginary plane may be further located in an area farther away from the antenna under test than the second distance, and the multiple measurement positions may be positions of intersections of multiple vertical lines and multiple horizontal lines when a grid having multiple vertical lines and multiple horizontal lines is virtually drawn on multiple imaginary planes at different distances from the antenna under test.

[0016] In a second aspect of the present invention, a program is provided for causing a computer to execute the following steps: a radio wave output step for starting the output of radio waves of a predetermined output strength from a target antenna to be measured; an aircraft measurement step for, after executing the radio wave output step, flying an aircraft so that the target antenna passes through a plurality of measurement positions arranged on a virtual plane opposite the target antenna in the direction in which the target antenna outputs radio waves, and outputting data for measuring the position of the aircraft, the attitude of the aircraft, and the strength of the radio waves output from the target antenna; an information acquisition step for acquiring position information indicating the position of the aircraft, attitude information indicating the attitude of the aircraft, and radio wave strength information indicating the strength of the radio waves output from the target antenna, measured by the aircraft at the plurality of measurement positions; and a calculation step for calculating the radiation characteristics of the target antenna based on the position information, the attitude information, and the radio wave strength information.

[0017] In a third aspect of the present invention, there is provided a measurement system for measuring radiation characteristics of an antenna, comprising: Provided is a measurement system comprising: a transmitting unit that supplies a transmission signal to the antenna under test to cause the antenna under test to output radio waves of a predetermined output strength; an aircraft that passes through a plurality of measurement positions arranged on a virtual plane facing the antenna under test in the direction in which the antenna under test outputs radio waves; and a data processing device that communicates with the aircraft, wherein the aircraft has a position measuring unit that measures the position of the aircraft on a path that passes through the plurality of measurement positions, an attitude sensor that measures the attitude of the aircraft, and a radio wave receiving unit that measures the strength of the radio waves output from the antenna under test, and the data processing device has an acquiring unit that acquires position information indicating the position of the aircraft, attitude information indicating the attitude of the aircraft, and radio wave strength information that are measured by the aircraft at the plurality of measurement positions, and a calculating unit that calculates the radiation characteristics of the antenna under test based on the position information, the attitude information, and the radio wave strength information. [Effects of the Invention]

[0018] According to the present invention, it is possible to easily measure the radiation characteristics of a large-diameter antenna. [Brief explanation of the drawings]

[0019] [Figure 1] 1 shows an example of the schematic configuration of a measurement system S according to this embodiment. [Figure 2] 1 shows an example of the configuration of an aircraft 20 according to this embodiment. [Figure 3] FIG. 2 is a diagram schematically showing measurement positions of the flying object 20 according to the present embodiment. [Figure 4] FIG. 2 is a diagram schematically showing the height of the measurement position of the flying object 20 according to the present embodiment. [Figure 5] 3 is a schematic diagram showing a half-value width w on a virtual plane according to the present embodiment. FIG. [Figure 6] 1 shows an example of the configuration of a data processing device 30 according to this embodiment. [Figure 7] 10 shows an example of the radiation characteristics of the antenna A under measurement output by the data processing device 30 according to this embodiment. [Figure 8] 1 is a diagram showing measurement positions at two different heights of an aircraft 20 according to this embodiment. [Figure 9] 10 shows a modified example of the radiation characteristic of the antenna A under test output by the data processing device 30 according to this embodiment. [Figure 10] 1 shows an operation sequence of the measurement system S according to this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0020] <Outline of measurement system S> FIG. 1 shows an example of the schematic configuration of a measurement system S according to this embodiment. The measurement system S measures the radiation characteristics of an antenna A under test. In this embodiment, the three orthogonal directions are the X direction, the Y direction, and the Z direction. Here, the Z direction is set to be substantially the same as the vertical direction. The XY plane is set to be a plane substantially parallel to a plane horizontal to the ground. The antenna A under test is shown, for example, in its assembled and installed state. The measurement system S includes a transmitter 10, an aircraft 20, and a data processing device 30.

[0021] The transmitting unit 10 supplies a transmission signal to the antenna A under test to cause the antenna A under test to output radio waves of a predetermined output strength. The transmitting unit 10 supplies the transmission signal to the antenna A under test in response to a control signal received from the data processing device 30, for example. The transmitting unit 10 may also have a memory circuit for storing programs, data, etc., and supply the transmission signal to the antenna A under test in response to the stored programs, data, etc. Upon receiving the transmission signal, the antenna A under test radiates radio waves vertically upward.

[0022] The aircraft 20 measures its own position, its own attitude, and the strength of the radio waves output from the antenna A under test while passing through multiple measurement positions in the direction in which the antenna under test outputs radio waves. The multiple measurement positions through which the aircraft 20 passes will be described later. The aircraft 20 obtains its own position information by, for example, using a Global Navigation Satellite System (GNSS). The aircraft 20, for example, performs measurement operations continuously while passing through a predetermined route.

[0023] The data processing device 30 calculates and outputs the radiation characteristics of the antenna A under test based on the measurement results of the flying object 20. The data processing device 30 is connected to the transmitting unit 10, for example, via a network or the like, and supplies a control signal for controlling the transmitting unit 10. The data processing device 30 also communicates with the flying object 20 to acquire the measurement results of the flying object 20. The data processing device 30 may also acquire the measurement results of the flying object 20 from a data server or the like connected to the network or the like.

[0024] As described above, the measurement system S uses the flying object 20 to measure the radiation characteristics of the antenna A under test. The flying object 20 used by such a measurement system S will now be described.

[0025] <Configuration example of flying vehicle 20> FIG. 2 shows an example configuration of the aircraft 20 according to this embodiment. The aircraft 20 flies a predetermined route based on, for example, a preset program, data, etc. The aircraft 20 may receive a control signal and fly the predetermined route based on the received control signal. The aircraft 20 is, for example, an unmanned aerial vehicle such as a drone. The route taken by the aircraft 20 will be described later.

[0026] The flying object 20 has a receiving antenna 21, a radio wave receiving unit 22, a position measuring unit 23, an attitude sensor 24, an flying object communication unit 25, an flying object memory unit 26, and an flying object control unit 27. Note that the parts used by the flying object 20 to fly are known technologies, so they are not shown in Figure 2 and will not be described here.

[0027] The receiving antenna 21 receives the radio waves output from the antenna A under test. The receiving antenna 21 supplies the received signal to the radio wave receiving unit 22. The radio wave receiving unit 22 measures the intensity of the radio waves output from the antenna A under test based on the received signal received by the receiving antenna 21. The radio wave receiving unit 22 outputs the measurement result of the radio wave intensity as radio wave intensity information.

[0028] The position measurement unit 23 measures the position of the flying object 20. The position measurement unit 23 communicates with GNSS satellites such as GPS and Galileo to acquire position information including information such as the latitude, longitude, and altitude of the flying object 20. The position measurement unit 23 may also have a laser rangefinder and measure the distance from the target antenna A to identify the position of the flying object 20. The position measurement unit 23 outputs the measurement result of the position of the flying object 20 as position information.

[0029] The attitude sensor 24 measures the attitude of the flying object 20. The attitude sensor 24 has, for example, a three-axis acceleration sensor, and measures the angle that the flying object 20 is facing relative to the downward vertical direction as the attitude of the flying object 20. The attitude sensor 24 may have a gyro sensor, and measure the attitude of the flying object 20 using the gyro sensor. The attitude sensor 24 outputs the measurement result of the attitude of the flying object 20 as attitude information.

[0030] The air vehicle communication unit 25 communicates with the data processing device 30. The air vehicle communication unit 25 transmits, for example, position information, attitude information, and radio wave intensity information measured by the air vehicle 20 to the data processing device 30. The air vehicle communication unit 25 may receive programs, data, control signals, etc. for flying the air vehicle 20 from the data processing device 30.

[0031] The air vehicle storage unit 26 is a storage medium including a ROM (Read Only Memory) and a RAM (Random Access Memory). The air vehicle storage unit 26 may also include a large-capacity storage device such as an HDD (Hard Disk Drive) and / or an SSD (Solid State Drive). For example, when a CPU or the like functions as the air vehicle control unit 27, the air vehicle storage unit 26 may store information such as an OS (Operating System) that causes the CPU to function, programs, etc. The air vehicle storage unit 26 may also store various information including a database referenced when a program is executed.

[0032] The air vehicle memory unit 26 may store information about the flight path of the air vehicle 20. The air vehicle memory unit 26 may also store information about measurement positions. The air vehicle memory unit 26 may store position information, attitude information, and radio wave intensity information indicating the results of measurements taken by the air vehicle 20 at multiple measurement positions. The air vehicle memory unit 26 may supply the stored data to the requesting source in response to a request from each unit in the measurement system S.

[0033] The aircraft control unit 27 controls each part of the aircraft 20. For example, the aircraft control unit 27 reads out information about the route of the aircraft 20 stored in the aircraft memory unit 26, and controls the drive system of the aircraft 20 so that the aircraft 20 flies along the read-out route. The aircraft control unit 27 controls the radio wave receiving unit 22, the position measuring unit 23, and the attitude sensor 24 to perform measurements of each part.

[0034] The air vehicle control unit 27 receives the position information, attitude information, and radio wave intensity information of the measurement results, and stores the attitude information and radio wave intensity information in the air vehicle memory unit 26 in association with the position information. The air vehicle control unit 27 also controls the air vehicle communication unit 25 to transmit information on multiple measurement results to the data processing device 30. The air vehicle control unit 27 is, for example, a CPU (Central Processing Unit). The CPU functions as the air vehicle control unit 27 by executing a program stored in the air vehicle memory unit 26. The multiple measurement positions through which the air vehicle 20 passes will now be described.

[0035] <Measurement position of flying object 20> Fig. 3 is a diagram schematically showing the measurement position of the flying body 20 according to this embodiment. Fig. 3 shows an XY plane that is approximately parallel to the horizontal plane on the ground on which the antenna A under test is installed. The antenna A under test extends in the Z direction (vertical direction) and emits radio waves vertically upward, so the XY plane is an imaginary plane that faces the antenna A under test and is perpendicular to the output direction of the radio waves.

[0036] The multiple measurement positions are the positions of the intersections of the multiple vertical lines and multiple horizontal lines when a grid having multiple vertical lines and multiple horizontal lines is drawn imaginarily on such a virtual plane. For example, the spacing between the multiple vertical lines aligned in the X direction approximately matches the spacing between the multiple horizontal lines aligned in the Y direction, and is shown as spacing h in Figure 2. Furthermore, one measurement point is approximately the same as the position where the antenna A under test is installed (directly above the antenna A under test) in a planar view. In Figure 2, the position where the antenna A under test outputs radio waves is shown as the center 100 of the grid.

[0037] 4 is a diagram schematically showing the height of the measurement position of the flying object 20 according to this embodiment. The imaginary plane is assumed to be a predetermined distance away from the antenna A under test. For example, when measuring the near-field radiation characteristics of the antenna A under test, the predetermined distance is set to be equal to or greater than the first distance at which the near field begins and equal to or less than the second distance at which the near field and the far field border. When measuring the far-field radiation characteristics of the antenna A under test, the predetermined distance is set to be equal to or greater than the second distance.

[0038] Here, the near field and far field can be defined by considering an infinitesimal loop and an infinitesimal dipole. For example, the magnetic field strength H of a radio wave in the near field is H=(IS) / (4πD 3 ) where I is the loop current, S is the loop area, and D is the distance between the transmitting and receiving antennas. The electric field strength E of the radio wave in the near field is E=(z0IS) / (4λD 2 ) where z0 is the free space impedance and λ is the wavelength of the transmitted radio wave. In other words, the near field is an area where the magnetic field strength of the radio wave can be approximated by a curve inversely proportional to the cube of the distance, and the electric field strength of the radio wave can be approximated by a curve inversely proportional to the square of the distance.

[0039] The magnetic field strength H of the radio wave in the far field is H=(πIS) / (λ 2 D), and the electric field strength E of radio waves in the far field is E = (z0πIS) / (λ 2In other words, the far field is a region where the magnetic field strength and electric field strength of radio waves can be approximated by curves that are inversely proportional to the reciprocal of the distance, and where the wave impedance, which is the electric field strength divided by the magnetic field strength, can be approximated as being approximately constant.

[0040] One or more imaginary planes may be set in the near field, and alternatively or additionally, one or more imaginary planes may be set in the far field. For example, the multiple measurement positions are the positions of intersections when a grid is virtually drawn on multiple imaginary planes at different distances from the antenna A under test.

[0041] 4, an imaginary plane that is a first distance away from the antenna A under test is designated as a first imaginary plane 101, and an imaginary plane that is a second distance away from the antenna A under test is designated as a second imaginary plane 102. For example, if the diameter of the antenna A under test is D and the wavelength of the radio waves output by the antenna A under test is λ, the first distance is expressed by the following equation, Z1:

number

[0042] The second distance is expressed as Z2 in the following equation.

number

[0043] For example, if the frequency of the radio waves output by the antenna A under test is 10 GHz and the diameter of the antenna A under test is 1.0 m, then Z1 = 11 m and Z2 = 667 m. Multiple imaginary planes may be set between the first distance Z1 and the second distance Z2. For example, a predetermined distance may be set for one of the multiple set imaginary planes so that the radio wave intensity received at all measurement points set on the plane is greater than the noise level. Furthermore, a predetermined distance may be set for one of the multiple set imaginary planes so that the radio wave intensity only at the center 100 of the grid is greater than the noise level.

[0044] <Half width on the imaginary plane w> In such a virtual plane, the grid spacing h may be set based on the half-width w, which corresponds to the distance at which the radio wave strength is halved. Fig. 5 is a schematic diagram showing the half-width w on the virtual plane according to this embodiment. For example, it is desirable to set the grid so that when the radio wave strength detected at one measurement point is the peak value of the radio wave, the radio wave strength detected at a measurement point adjacent to the measurement point (a distance h from the measurement point) is a received power that is approximately 3 dB lower.

[0045] For example, for radio waves emitted from the antenna A under test, the angle at which the radio wave intensity reaches its peak is taken as the reference (0 degrees), and the angle θ at which the radio wave intensity drops by Δp from the peak value is determined. Here, Δp is 3 dB. The angle θ is the angular expression of the half-width, which may be referred to as the half-width θ in this embodiment. FIG. 5 shows an example in which, on an imaginary plane 103 located a distance Z3 away from the antenna A under test, the position at which the radio wave intensity reaches its peak is taken as the grid center 100, and the distance from the grid center 100 to the position at which the radio wave intensity drops by Δp from the peak value is taken as w. The distance w is the length expression of the half-width, which may be referred to as the half-width w in this embodiment.

[0046] The half-width θ is a typical index representing antenna characteristics, and according to Non-Patent Document 6, it can be estimated as follows:

number

[0047] Further, the half-value width w on the imaginary plane 103 that is separated by Z3 from the antenna A under test is calculated as follows using the half-value width θ in the above equation.

number

[0048] For example, if the frequency of the radio waves output by antenna A under test is 100 GHz and the diameter of antenna A under test is 0.3 m, the half-width θ will be approximately 0.3 degrees. If Z3 is 100 m, the half-width w will be approximately 0.5 m. When measuring the received power of radio waves, for example, it is desirable that the grid spacing h be set to less than the half-width w, and in this case it is set to 0.5 m, for example.

[0049] Furthermore, if the frequency of the radio waves output by the antenna A under test is 100 GHz and the diameter of the antenna A under test is 1 m, the half-width θ will be approximately 0.9 degrees. If Z3 is 10 m, the half-width w will be approximately 15 mm. In this case, the grid spacing h is set to 15 mm, for example.

[0050] In this way, the grid spacing h may be set to different values ​​depending on the diameter D of the target antenna A and the frequency (wavelength λ) of the radio waves output by the target antenna A. Measurement accuracy of the order of the grid spacing h may be required for measuring the position of the aircraft 20. Therefore, the position measurement unit 23 of the aircraft 20 may select the GNSS to use in accordance with the set grid spacing h.

[0051] For example, when the grid interval h is about 10 m, the position measurement unit 23 acquires position information from a global positioning system (GPS) with a measurement accuracy of about 10 m. When the grid interval h is about 10 m to several tens of cm, the position measurement unit 23 may acquire position information from the Quasi-Zenith Satellite System (Michibiki), with a measurement accuracy of about 10 m to several tens of cm. Furthermore, when the grid interval h is about 10 cm to several cm, the position measurement unit 23 may acquire position information from a real-time kinematic GPS (RTK-GPS), with a measurement accuracy of about 1 cm.

[0052] As described above, the measurement system S according to this embodiment has multiple measurement points set at positions higher than the installed antenna A under test. Unlike conventional measurement devices, it has been difficult to install multiple receiving devices at positions a predetermined distance away from the antenna A under test at the location where the antenna A is installed. However, the measurement system S according to this embodiment can easily perform measurements at such measurement points on a virtual plane by using the flying object 20.

[0053] For example, the flying object 20 flies in the direction in which the antenna A under test outputs radio waves, passing through a plurality of measurement positions arranged on an imaginary plane facing the antenna A under test, and measures the position of the flying object 20, the attitude of the flying object 20, and the intensity of the radio waves output from the antenna A under test. The flying object 20 may perform the measurement operation while flying through a plurality of measurement positions arranged on a plurality of imaginary planes.

[0054] The aircraft 20 performs a measurement operation multiple times while flying a predetermined flight path. The aircraft 20 may, for example, perform the measurement operation continuously at a predetermined cycle. The aircraft 20 may also perform one or multiple measurement operations in response to being positioned near a measurement position. In this case, the aircraft control unit 27 causes the position measurement unit 23 to continuously perform position measurements, and causes the radio wave receiving unit 22 and the attitude sensor 24 to perform measurements in response to the position indicated by the position information output by the position measurement unit 23 being within a predetermined range from any one of the multiple measurement positions. The aircraft 20 supplies the measurement results to the data processing device 30.

[0055] <Configuration example of data processing device 30> FIG. 6 shows an example of the configuration of a data processing device 30 according to this embodiment. The data processing device 30 is a computer such as a server. The data processing device 30 communicates with the flying object 20 to acquire position information, attitude information, and radio wave intensity information, which are measurement results of the flying object 20. Based on the acquired measurement results, the data processing device 30 calculates and outputs the radiation characteristics of the antenna A under test. The data processing device 30 includes a communication unit 31, a memory unit 32, a display unit 33, and a control unit 34.

[0056] The communication unit 31 communicates with the aircraft 20. The communication unit 31 may function as an interface for connecting to a communication network such as a wireless LAN or a mobile phone network.

[0057] The storage unit 32 is a storage medium including a read-only memory (ROM) and a random access memory (RAM). The storage unit 32 may also include a large-capacity storage device such as a hard disk drive (HDD) and / or a solid state drive (SSD). For example, when a computer functions as the data processing device 30, the storage unit 32 may store information such as an operating system (OS) that causes the computer to function, and programs. The storage unit 32 may also store various information including a database that is referenced when a program is executed.

[0058] The storage unit 32 may also store intermediate data, calculation results, thresholds, reference values, parameters, etc. that are generated (or used) during the operation of the data processing device 30. The storage unit 32 may also supply the stored data to a request source in response to a request from each unit within the data processing device 30.

[0059] The display unit 33 displays the measurement results of the measurement system S. The display unit 33 may also function as a display for displaying the communication status of the data processing device 30, the OS, the execution status of applications, etc. The display unit 33 may also have a touch panel function and operate as an input unit. The data processing device 30 may also have input devices separate from the display unit 33, such as a keyboard, mouse, or voice input device.

[0060] The control unit 34 controls each unit of the data processing device 30. For example, the control unit 34 controls the communication unit 31 to transmit flight path information to the flying object 20. The control unit 34 also controls the communication unit 31 to receive measurement result information from the flying object 20. The control unit 34 may control the display unit 33 to display the measurement results of the measurement system S.

[0061] The control unit 34 is, for example, a CPU (Central Processing Unit). The control unit 34 has an acquisition unit 41, a calculation unit 42, and a measurement result output unit 45. In other words, the CPU executes a program stored in the storage unit 32 to function as the control unit 34 having the acquisition unit 41, the calculation unit 42, and the measurement result output unit 45.

[0062] The acquisition unit 41 acquires position information indicating the position of the aircraft 20, which are measured at multiple measurement positions by the aircraft 20, attitude information indicating the attitude of the aircraft 20, and radio wave intensity information indicating the intensity of the radio waves output from the antenna A to be measured. As described above, the information acquired by the acquisition unit 41 is such that one piece of attitude information and one piece of radio wave intensity information are associated with one piece of position information.

[0063] The acquisition unit 41 may acquire the measurement results each time the flying object 20 performs a measurement operation, or alternatively, may acquire the measurement results after the flying object 20 has completed a predetermined number of measurement operations. Alternatively, the acquisition unit 41 may acquire the measurement results after the flying object 20 has completed all measurement operations on the flight path.

[0064] The calculation unit 42 calculates the radiation characteristics of the antenna A under measurement based on the position information, attitude information, and radio wave intensity information acquired by the acquisition unit 41. The calculation unit 42 includes an identification unit 43 and a correction unit 44.

[0065] The identifying unit 43 identifies a representative value of the measurement results of radio wave strength at each measurement position from among the multiple measurement results of radio wave strength based on the location information. The identifying unit 43 identifies multiple representative values ​​corresponding to the multiple measurement positions for each measurement position. For example, the identifying unit 43 identifies a measurement value indicated by radio wave strength information associated with location information indicating the position closest to a measurement position as the representative value for the measurement position.

[0066] Alternatively, the identification unit 43 may extract location information indicating locations within a predetermined distance from the one measurement location. The identification unit 43 may, for example, identify the average value of the measurement values ​​indicated by the radio wave intensity information associated with the extracted location information as the representative value of the one measurement location. Alternatively, the identification unit 43 may identify the median value of the measurement values ​​indicated by the radio wave intensity information associated with the extracted location information as the representative value of the one measurement location.

[0067] For example, even if the flying object 20 is stably floating at a certain measurement position, the attitude of the flying object 20 may fluctuate. In this case, the measurement result of the radio wave intensity when the attitude of the flying object 20 fluctuates will fluctuate so that the measured value decreases compared to the measurement result of the radio wave intensity measured when the flying object 20 is in the correct attitude. Therefore, it is desirable to adopt the maximum measured value among the multiple measurement results of the radio wave intensity as the measurement result for the certain measurement position. Therefore, the identification unit 43 may identify the largest value among the measured values ​​indicated by the radio wave intensity information associated with the extracted position information as the representative value for the certain measurement position.

[0068] Based on the position information and the attitude information, the correction unit 44 corrects the representative value of the measurement results of the radio wave intensity identified by the identification unit 43. For example, when the height indicated by the position information associated with the representative value of one measurement position deviates from the set value of the height of a virtual plane including the one measurement position by more than a threshold, the correction unit 44 corrects the representative value.

[0069] The correction unit 44 calculates a correction value Δrssi for correcting the representative value using the following equation: where z is the height indicated by the position information associated with the representative value, z0 is the set value for the height of the virtual plane, and λ is the wavelength of the received radio wave. The correction unit 44 corrects the representative value by adding the correction value Δrssi to the representative value.

number

[0070] Furthermore, if the attitude indicated by the attitude information associated with the representative value of one measurement position exceeds a threshold angle, the correction unit 44 corrects the representative value. The correction unit 44 corrects the representative value based on the directional characteristics of the receiving antenna 21 of the flying object 20. It is desirable that the directional characteristics of the receiving antenna 21 be measured in advance. Furthermore, the directional characteristics of the receiving antenna 21 may be specified from the design values, specifications, etc. of the receiving antenna 21.

[0071] The storage unit 32 preferably stores a table that contains the relationship between the angle indicated by the attitude information and the amount of attenuation of the received signal due to the directional characteristics of the receiving antenna 21. The correction unit 44, for example, reads out the table stored in the storage unit 32 and corrects the representative value by adding the amount of attenuation corresponding to the attitude indicated by the attitude information as a correction value to the representative value. The correction unit 44 supplies the corrected representative value to the measurement result output unit 45 as the measurement result calculated by the calculation unit 42.

[0072] <Radiation characteristics 1 of antenna A under test> The measurement result output unit 45 converts the measurement results of the multiple measurement positions received from the calculation unit 42 into antenna characteristics and outputs them as radiation characteristics. Fig. 7 shows an example of the radiation characteristics of the antenna A under measurement output by the data processing device 30 according to this embodiment. Fig. 7 shows the radiation characteristics of the antenna A under measurement corresponding to the measurement positions of the aircraft 20 shown in Fig. 3.

[0073] The numerical values ​​shown in Fig. 7 are, for example, numerical values ​​in units of decibel values ​​(dBm). As the radiation characteristics of the antenna, it is desirable that the grid spacing h shown in Fig. 3 is expressed as the angle at which radio waves are emitted within the grid. Therefore, the measurement result output unit 45 may output the horizontal and vertical directions as angles based on the height at which the grid is set. The measurement result output unit 45 controls the display unit 33 to output the measurement results shown in Fig. 7 to the display unit 33.

[0074] <Radiation characteristics of antenna A under test 2> Fig. 8 is a diagram showing measurement positions at two different heights of the flying body 20 according to this embodiment. Fig. 8 shows an imaginary plane 104 that is separated by Z1 from the antenna A under test, and an imaginary plane 105 that is separated by Z2 from the antenna A under test. The measurement positions are the positions of the intersections of grids that are virtually drawn on the imaginary planes 104 and 105.

[0075] 8, the virtual planes 104 and 105 are indicated by dotted lines. The interval between two adjacent measurement positions (grid interval h) on the virtual planes 104 and 105 is indicated by solid lines. The grid interval on the virtual plane 104 is assumed to be equal to the grid interval on the virtual plane 105.

[0076] In this case, the grid spacing h of imaginary plane 104, which is farther from antenna A under test than imaginary plane 105, receives radio waves in an angular range narrower than the grid spacing h of imaginary plane 105. Here, the angular range of radio waves received by the grid spacing h of imaginary plane 104 is set to α1, and the angular range of radio waves received by the grid spacing h of imaginary plane 105 is set to α2.

[0077] In other words, even if a grid with the same distance interval h is set on the virtual plane, the angular range of radio waves received will be larger for the grid interval h of the virtual plane closer to the antenna A under test. Therefore, the measurement results of radio wave intensity using a virtual plane closer to the antenna A under test have a greater measurement resolution (angular resolution).

[0078] Fig. 9 shows a modified example of the radiation characteristics of the antenna A under measurement output by the data processing device 30 according to this embodiment. Fig. 9 shows an example in which the radiation characteristics of the antenna A under measurement shown in Fig. 7 are superimposed with the results of measuring the radiation characteristics of the antenna A under measurement using a virtual plane that is closer to the antenna A under measurement than the virtual plane used in Fig. 7.

[0079] In Fig. 9, the radiation characteristics of the area near the center are the radiation characteristics of the antenna A under test shown in Fig. 7, and are measurement results with high measurement resolution. In Fig. 9, the radiation characteristics of the surrounding area have a wider measurement range than the central area, and are measurement results with lower measurement resolution. Note that the measurement results shown in Fig. 9 are obtained using measurement results on two imaginary planes of the aircraft 20, but instead, for example, they can also be calculated from measurement results on one of the imaginary planes.

[0080] For example, the radiation characteristics of the antenna A under test shown in Fig. 7 are taken as the measurement results for the central region. Note that these radiation characteristics are the results obtained using the measurement results for the measurement position on imaginary plane A of the aircraft 20. Then, by using the radiation characteristics of the antenna A under test shown in Fig. 7 and equation (5) and setting the value of z0 to a height different from the height of imaginary plane A, it is possible to convert the radiation characteristics into measurement results obtained using a measurement position on imaginary plane B at a height different from that of imaginary plane A.

[0081] This allows measurements that require high measurement resolution to use the measurement results of the central region (e.g., measurement results using a virtual plane that is farther away from the antenna A under test), and measurements that do not require high measurement resolution to use the measurement results of the peripheral region (e.g., measurement results using a virtual plane that is closer to the antenna A under test), thereby making it possible to efficiently utilize the radiation characteristics of the antenna A under test.

[0082] <Operation sequence of measurement system S> 10 shows the operation sequence of the measurement system S according to this embodiment. First, the measurement target antenna A starts outputting radio waves at a predetermined output strength (S51). The data processing device 30 transmits a control signal to the transmitting unit 10 to start outputting radio waves. In response to the control signal received from the data processing device 30, the transmitting unit 10 supplies the measurement target antenna A with a transmission signal to output radio waves (S52). As a result, the measurement target antenna A outputs radio waves at a predetermined output strength.

[0083] Next, the flight of the aircraft 20 is started (S53). The data processing device 30 transmits a control signal to the aircraft 20 to cause the aircraft 20 to start flying. The data processing device 30 may transmit information about the flight path of the aircraft 20 to the aircraft 20. Alternatively, the data processing device 30 may transmit information about the flight path of the aircraft 20 to the aircraft 20 before measurement.

[0084] As a result, the aircraft 20 flies in the direction in which the antenna A to be measured outputs radio waves, passing through multiple measurement positions arranged on a virtual plane opposite the antenna A to be measured, and measures the position of the aircraft 20, the attitude of the aircraft 20, and the strength of the radio waves output from the antenna A to be measured (S54).

[0085] Next, the data processing device 30 acquires position information indicating the position of the aircraft 20, attitude information indicating the attitude of the aircraft 20, and radio wave intensity information indicating the intensity of the radio wave output from the antenna A to be measured, all of which are measured by the aircraft 20 at multiple measurement positions (S55). The data processing device 30 may acquire these pieces of information while the aircraft 20 is flying.

[0086] Next, the data processing device 30 calculates the radiation characteristics of the antenna A under measurement based on the position information, attitude information, and radio wave intensity information (S56). The data processing device 30 displays the calculated radiation characteristics of the antenna A under measurement on the display unit 33 (S57). As described above, the measurement system S according to this embodiment can easily measure the radiation characteristics of a large-diameter antenna A under measurement. Furthermore, the radiation characteristics can be easily measured even for a large-diameter antenna A under measurement after installation.

[0087] The present invention has been described above using embodiments, but the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. For example, all or part of the device can be configured by functionally or physically distributing or integrating any unit. Furthermore, new embodiments resulting from any combination of multiple embodiments are also included in the embodiments of the present invention. The effects of the new embodiments resulting from the combination also have the effects of the original embodiments. [Explanation of symbols]

[0088] 10 Transmitter 20 Flying Objects 21 Receiving antenna 22 Radio wave receiving unit 23 Position measurement section 24 Attitude Sensor 25 Aircraft Communications Department 26 Aircraft Memory Unit 27 Aircraft control unit 30 Data processing device 31 Communications Department 32 Storage section 33 Display section 34 Control Unit 41 Acquisition Department 42 Calculation section 43 Specific part 44 Correction unit 45 Measurement result output section 100 center 101 First virtual plane 102 Second virtual plane 103 Virtual Plane 104 Virtual Plane 105 Virtual Plane

Claims

1. A method for measuring radiation characteristics of an antenna, comprising: a radio wave output step of outputting radio waves of a predetermined output intensity from an antenna under test that is the object of measurement; an aircraft measurement step of flying an aircraft so that the aircraft passes through a plurality of measurement positions arranged on a virtual plane facing the antenna under test in a direction in which the antenna under test outputs radio waves, and measuring the position of the aircraft, the attitude of the aircraft, and the intensity of the radio waves output from the antenna under test; an information acquisition step in which a computer acquires position information indicating the position of the aircraft, attitude information indicating the attitude of the aircraft, and radio wave intensity information indicating the intensity of the radio wave output from the antenna to be measured, which are measured by the aircraft at multiple measurement positions; a calculation step in which the computer calculates a radiation characteristic of the antenna under test based on the position information, the attitude information, and the radio wave intensity information; A measurement method comprising:

2. In the aircraft measurement step, the aircraft performs measurements of the position of the aircraft, the attitude of the aircraft, and the intensity of the radio wave output from the antenna to be measured multiple times while flying a predetermined flight path; The calculation step a specifying step of specifying a representative value of the measurement results of radio wave intensity at each of the measurement positions from among a plurality of measurement results of radio wave intensity based on the location information; a correction step of correcting the specified representative value of the measurement results of radio wave intensity based on the position information and the attitude information; Further comprising: The measurement method according to claim 1.

3. 2. The measurement method according to claim 1, wherein the plurality of measurement positions are positions of intersections of a plurality of vertical lines and a plurality of horizontal lines when a grid having a plurality of vertical lines and a plurality of horizontal lines is virtually drawn on the virtual plane.

4. 4. The measurement method according to claim 3, wherein the plurality of measurement positions are positions of the intersections when the grid is virtually drawn on a plurality of the imaginary planes at different distances from the antenna under test.

5. The measurement method according to claim 1 , wherein the imaginary plane is located at a distance greater than a first distance from the antenna under test, the first distance being a distance at which a near field begins.

6. The first distance is expressed by Z1 in the following equation, where D is the diameter of the antenna under test and λ is the wavelength of the radio wave output from the antenna under test: The measurement method according to claim 5.

7. 6. The measurement method according to claim 5, wherein the imaginary plane is located in a range that is farther from the antenna under test than the first distance and closer than a second distance, and the second distance is a distance that is a boundary between the near field and the far field.

8. The second distance is represented by Z2 in the following equation: The measurement method according to claim 7.

9. 8. The measurement method according to claim 7, wherein the imaginary plane is further located in an area farther away from the antenna under test than the second distance, and the plurality of measurement positions are positions of intersections of a plurality of vertical lines and a plurality of horizontal lines when a grid having a plurality of vertical lines and a plurality of horizontal lines is virtually drawn on a plurality of the imaginary planes at different distances from the antenna under test.

10. On the computer, a radio wave output step of starting to output radio waves of a predetermined output strength from an antenna under test that is the object of measurement; an aircraft measurement step of, after the radio wave output step has been performed, flying an aircraft so that the aircraft passes through a plurality of measurement positions arranged on a virtual plane facing the antenna under test in the direction in which the antenna under test outputs radio waves, and outputting data for measuring the position of the aircraft, the attitude of the aircraft, and the intensity of the radio waves output from the antenna under test; an information acquisition step of acquiring position information indicating the position of the aircraft, attitude information indicating the attitude of the aircraft, and radio wave intensity information indicating the intensity of the radio wave output from the antenna to be measured, the position information being measured at the plurality of measurement positions; a calculation step of calculating a radiation characteristic of the antenna under test based on the position information, the attitude information, and the radio wave intensity information; A program to execute.

11. A measurement system for measuring radiation characteristics of an antenna, comprising: a transmitting unit that supplies a transmission signal to the antenna under test to cause the antenna under test to output radio waves of a predetermined output strength; an aircraft passing through a plurality of measurement positions arranged on a virtual plane facing the antenna under test in a direction in which the antenna under test outputs radio waves; a data processing device in communication with the air vehicle; Equipped with The flying object is traveling along a path that passes through the plurality of measurement positions. a position measurement unit that measures the position of the aircraft; an attitude sensor for measuring the attitude of the aircraft; a radio wave receiving unit for measuring the intensity of the radio wave output from the antenna under test; and The data processing device includes: an acquisition unit that acquires position information indicating the position of the aircraft measured at a plurality of the measurement positions, attitude information indicating the attitude of the aircraft, and radio wave intensity information indicating the intensity of the radio wave output from the antenna to be measured; a calculation unit that calculates a radiation characteristic of the antenna under test based on the position information, the attitude information, and the radio wave intensity information; having Measurement system.

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