Radio frequency field characteristic testing apparatus and method

Abstract

This invention provides a radio frequency field characteristic testing device and method. A linear slide bar, a magnetic scale, and a motor are all fixed on a scanning chassis. The linear slide bar and the magnetic scale are placed side by side. A slider slides on the linear slide bar, and a receiving antenna is mounted on the slider via an adapter. The magnetic head of the magnetic scale is mounted on the slider, and the magnetic scale measures the displacement of the receiving antenna. The motor drives the receiving antenna to move. One end of a cylinder is located on the bottom surface of the scanning chassis away from the linear slide bar, and the cylinder has the function of extending and retracting in a direction perpendicular to the normal of the scanning chassis. The other end of the cylinder is located on a connecting flange, which is fixed to the inner frame of the turntable. This invention differs from the standard gain horn of the scanning bracket. This invention uses a small circularly polarized antenna and makes full use of the turntable's own rolling axis structure. The linear guide bar and the rotation of the turntable form a planar scan. The structure is relatively simple and compact, and it is suitable for measuring the electromagnetic field characteristics in the quiet zone of a hardware-in-the-loop simulation system.

Description

Technical Field

[0001] This invention relates to the technical field of radio frequency field characteristic testing, and more specifically, to a radio frequency field characteristic testing apparatus and method. Background Technology

[0002] The amplitude and phase characteristics of the field in the quiet zone are typically measured using the scanning method. The test system consists of a vector network analyzer, signal source, amplitude and phase measurement equipment, antenna, scanning frame, calibration sphere, and cables. The antenna is a linearly polarized antenna, generally a standard gain horn antenna. Measurements are performed under both horizontal and vertical polarization conditions. The antenna on the scanning frame is moved along the horizontal and vertical lines respectively, and the received signals are recorded. The amplitude and phase changes are directly obtained from the difference between the maximum and minimum values.

[0003] The scanning rig is generally a two-dimensional translational structure, which is a test system fixed on the ground and cannot be applied in a hardware-in-the-loop simulation system; the tilt error of the scanning rig may cause the measurement data to not be in a single static plane; and the phase distribution error caused by the near-field spherical wave itself is not considered.

[0004] Another type of hardware-in-the-loop simulation system commonly used in RF anechoic chambers is the large-diameter standard gain horn measurement system. Due to the large diameter of the antenna itself, it is suitable for characteristic testing at the center point of the quiet zone, but not for characteristic testing at various points within the quiet zone plane. It cannot accurately obtain the amplitude and phase distribution at various points within the quiet zone.

[0005] Chinese invention patent document CN103780314A discloses a radio frequency (RF) characteristic testing device for testing the RF characteristics of multiple communication circuit boards. The device includes: multiple clamping devices for fixing the multiple communication circuit boards; a network analyzer; a switching box; and a result display device. The switching box is electrically connected between the clamping devices and the network analyzer, and is used to sequentially switch the multiple communication circuit boards to the network analyzer. The network analyzer is used to sequentially test the communication circuit boards within the clamping devices after switching. The result display device is electrically connected to the network analyzer and is used to simultaneously display the test results of the multiple communication circuit boards.

[0006] Regarding the aforementioned technologies, the inventors believe that the measurement accuracy of the radio frequency quiet zone amplitude and phase distribution of the hardware-in-the-loop simulation system is low. Summary of the Invention

[0007] In view of the deficiencies in the prior art, the purpose of this invention is to provide a radio frequency field characteristic testing device and method.

[0008] According to the present invention, a radio frequency field characteristic testing device includes a turntable connection structure, a receiving antenna, an adapter, a linear slide bar, a magnetic scale, and a motor.

[0009] The structure connecting to the turntable includes a scanning chassis, a cylinder, and a connecting flange;

[0010] The linear slide bar, magnetic scale, and motor are all fixed on the scanning chassis;

[0011] The linear slide bar and the magnetic scale are placed side by side;

[0012] A slider slides on the linear slide bar, and the receiving antenna is mounted on the slider via an adapter.

[0013] The magnetic head of the magnetic scale is mounted on the slider, and the magnetic scale measures the displacement of the receiving antenna;

[0014] The motor drives the receiving antenna to move;

[0015] One end of the cylinder is located on the bottom surface of the scanning chassis away from the linear slide bar, and the cylinder has the function of extending and retracting along the normal direction perpendicular to the scanning chassis.

[0016] The other end of the cylinder is mounted on the connecting flange;

[0017] The connecting flange is fixed to the inner frame of the turntable.

[0018] Preferably, the receiving antenna includes a circularly polarized antenna, the diameter of the receiving port of the circularly polarized antenna is less than 20mm, and the antenna gain is 2dB;

[0019] The magnetic grating ruler has a reading resolution of 5μm and an accuracy of ±50μm / m.

[0020] Preferably, the testing apparatus also includes a dial indicator;

[0021] The dial indicator is fixed outside the inner frame of the turntable;

[0022] The receiving antenna end face is checked with a dial indicator to ensure that the zero position of the receiving antenna is at the rotation center of the turntable.

[0023] Preferably, the testing device also includes a microwave absorbing material;

[0024] The absorbing material covers the turntable connection structure, receiving antenna, adapter, linear slide bar, magnetic scale, and motor;

[0025] The receiving antenna end face is located outside the absorbing material.

[0026] Preferably, the testing apparatus further includes a first signal source, a second signal source, a mixer, an amplifier, a vector network analyzer, and a computer located under the turntable;

[0027] The first signal source is connected to the transmitting antenna of the measurement target system;

[0028] The second signal source is connected to the receiving antenna on the turntable;

[0029] The output signals of the first signal source and the second signal source are used to generate an intermediate frequency signal through a mixer;

[0030] The amplifier amplifies the intermediate frequency signal;

[0031] The vector network analyzer converts the amplified intermediate frequency signal into a vector network measurement signal;

[0032] The computer acquires vector network measurement signals.

[0033] Preferably, the testing device also includes a magnetic scale digital display and a motor controller;

[0034] The magnetic scale digital display and the motor controller are respectively connected to the computer.

[0035] According to the present invention, a radio frequency field characteristic testing method is provided, which uses a radio frequency field characteristic testing device. The testing device is equipped with a turntable, a dial indicator is set, and the test is started. Measurements are taken within 0° to (180-N)° of the inner frame of the turntable, and within 180° to (360-N)° of the inner frame of the turntable. The measured values ​​are averaged, and the phase value of the center point rotating with the inner frame of the turntable is subtracted. Spherical fitting is performed to obtain the amplitude and phase distribution. The variance of the amplitude and phase distribution is calculated, and the angular simulation error is calculated.

[0036] Preferably, before installing the testing device onto the turntable, the height from the turntable connecting flange surface to the turntable rotation center is measured, and the height of the measuring device cylinder is adjusted to ensure that the phase center of the receiving antenna is at the turntable rotation center. After installation on the inner frame of the turntable, the dial indicator is fixed outside the inner frame of the turntable, and the end face of the receiving antenna is used to ensure that the zero position of the receiving antenna is at the turntable rotation center, and the zero position of the receiving antenna is taken as the center zero point of the measurement plane.

[0037] Preferably, when the inner frame of the turntable rotates to a certain angle, the receiving antenna moves from one end to the other on the linear slide bar; when the inner frame of the turntable rotates from 0° at intervals of N° to (360-N)°, the receiving antenna completes the measurement of a quiet zone plane;

[0038] When the height of the measuring device changes, the position of the quiet zone plane measured by the receiving antenna changes, thus obtaining the electromagnetic field measurement data of the quiet zone plane at different positions in the quiet zone three-dimensional space.

[0039] Preferably, the test method includes the following steps:

[0040] Step 1: Connect all components correctly, install the upper turntable part on the inner frame of the turntable, rotate the inner frame of the turntable to confirm the measuring device;

[0041] Step 2: Adjust the receiving antenna to the middle position of the magnetic scale, fix the dial indicator outside the inner frame of the turntable, rotate the microwave antenna one full turn and press the dial indicator to ensure that the initial position of the receiving antenna is at the center of the inner frame rotation with an error of less than 0.02mm, and mark this position as zero point 0;

[0042] Step 3: Turn on the signal source and vector network analyzer, set the measurement frequency, and perform the test after it stabilizes;

[0043] Step 4: Set the turntable to position control mode. When the inner frame of the turntable is at 0°, the receiving antenna starts from L / 2 at one end of the magnetic scale and performs point-by-point testing at intervals of Mmm until the other end -L / 2. Where L represents the distance that the receiving antenna can move on the linear slide bar.

[0044] Step 5: At N° intervals, the receiving antenna scans from one end to the other within the inner frame of the turntable; the inner frame rotates from 0° to (180-N)°, and the amplitude, phase measurement, and reference values ​​at each point in the quiet zone plane are recorded.

[0045] Step 6: Continue to rotate the inner frame of the turntable from 180° to (360-N)°, and record the amplitude, phase measurement value and reference value of each point in the quiet zone plane again;

[0046] Step 7: Perform matrix transformation on the amplitude and phase distribution test data to obtain the amplitude and phase measurements at the same physical point; average the amplitude and phase values ​​at the same location to obtain the calibrated amplitude distribution E and phase distribution Q in the quiet zone plane;

[0047] Step 8: Subtract the phase value of the center point from the phase value of each point on each scan line to obtain the phase distribution Q1 after removing the influence of the receiving antenna;

[0048] Step 9: Perform spherical wave fitting on the measured phase value Q1 to obtain the fitted phase value Q2;

[0049] Step 10: Subtract the measured value Q1 from the fitted value Q2 to obtain the phase fluctuation φ in the measured plane;

[0050] Step 11: Calculate the variance σ1 of the phase ripples in the plane;

[0051]

[0052] In the formula: φ represents the average value of the phase fluctuations within the measurement plane; n represents the number of points within the measurement plane; φ i This represents the phase fluctuation at the i-th point in the measurement plane;

[0053] Step 12: Calculate the variance σ² of the amplitude fluctuations within the plane;

[0054]

[0055] In the formula: E represents the average amplitude within the measurement plane. i This represents the amplitude at the i-th point in the measurement plane;

[0056] Step 13: Based on the phase-to-angle measurement formula, substitute the phase variance to calculate the angle simulation error Δθ;

[0057]

[0058] In the formula: λ represents the antenna wavelength; D represents the distance between the two antennas being measured.

[0059] Step Fourteen: Adjust the height of the receiving antenna and the turntable rotation center, and repeat steps four to thirteen to obtain the amplitude variance, phase fluctuation variance and angular simulation error of different planes in the quiet zone three-dimensional space.

[0060] Compared with the prior art, the present invention has the following beneficial effects:

[0061] 1. This invention differs from the standard gain horn of the scanning bracket. This invention uses a small circularly polarized antenna and makes full use of the turntable's own rolling axis structure. The linear guide rod plus the rotation of the turntable forms a planar scan. The structure is relatively simple and compact, and it is suitable for measuring the electromagnetic field characteristics in the quiet zone of a hardware-in-the-loop simulation system.

[0062] 2. This invention utilizes data processing to eliminate measurement errors and spherical wave errors by receiving the field distribution within a 360° range of the antenna twice in a plane. Compared to a single-plane scanning test system, this invention only suffers from errors that may be introduced during the movement of the RF cable interface, thus resulting in smaller measurement errors and higher accuracy.

[0063] 3. This invention allows for on-site testing directly on the turntable of a hardware-in-the-loop simulation system, directly obtaining the static field characteristics within the three-dimensional space of the simulation test environment, resulting in more realistic and reliable measurement results. Attached Figure Description

[0064] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0065] Figure 1 This is a schematic diagram of the composition of a radio frequency field characteristic testing device based on turntable spin according to the present invention.

[0066] Figure 2 This is a schematic diagram of the quiet zone radio frequency field characteristic testing process of the present invention;

[0067] Figure 3 Example diagram of the amplitude distribution in the quiet zone plane;

[0068] Figure 4 Example diagram of the phase distribution in the plane of the quiet zone;

[0069] Figure 5 The phase distribution diagram of the fitted ideal sphere in the still plane;

[0070] Figure 6 Example diagram for measuring phase ripples in the quiet zone plane. Detailed Implementation

[0071] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0072] This invention discloses a radio frequency field characteristic testing device, such as... Figure 1 As shown, Figure 1 This is a schematic diagram of a radio frequency field characteristic testing device based on turntable spin, according to the present invention. The device mainly includes the following components: a receiving antenna, an adapter, a linear slide bar, a magnetic scale, a motor, a connection structure to the turntable, a magnetic scale digital display, a motor controller, two signal sources (a first signal source and a second signal source), a mixer, an amplifier, a vector network analyzer, a computer, measurement software, cables, a dial indicator, and absorbing materials. The connection structure to the turntable consists of a scanning chassis, a cylinder, and a connecting flange. The magnetic scale digital display provides feedback and displays the current position of the receiving antenna. The motor controller manually or via software controls the direction and magnitude of the receiving antenna's movement on the linear slide bar. All instruments are connected by cables, including optical fibers, radio frequency cables, and electrical wires.

[0073] The linear slide bar, magnetic scale, and motor are all fixed on the scanning chassis; the linear slide bar and magnetic scale are placed side by side; a slider slides on the linear slide bar, and the receiving antenna is mounted on the slider via an adapter; the magnetic head of the magnetic scale is mounted on the slider, and the magnetic scale measures the displacement of the receiving antenna; the motor drives the receiving antenna to move; one end of the cylinder is located on the bottom surface of the scanning chassis away from the linear slide bar, and the cylinder has the function of telescoping in a direction perpendicular to the normal of the scanning chassis; the other end of the cylinder is located on the connecting flange; the connecting flange is fixed on the inner frame of the turntable.

[0074] The receiving antenna, adapter, magnetic scale, linear slide bar, and motor are fixed to the scanning chassis. The magnetic scale and linear slide bar are placed side by side. Receiving antenna 1 is a small circularly polarized antenna, fixed to the slider of the linear slide bar via the adapter. The receiving antenna can move a distance L = 240 mm on the linear slide bar. The magnetic head of the magnetic scale is also fixed to the slider of the linear slide bar, and the displacement of the receiving antenna on the slide bar is measured by the magnetic scale. The cylinder adopts a two-layer structure, with a certain range of telescopic function in the direction perpendicular to the normal of the scanning chassis. That is, in addition to moving along the one-dimensional direction of the linear slide bar, the receiving antenna can also move in the radial direction of the cylinder. The connecting flange is the structure for installing the test device to the inner frame of the turntable. It is fixed to the inner frame of the turntable by a ring of screws around its perimeter.

[0075] The receiving antenna includes a circularly polarized antenna with a receiving port diameter of less than 20 mm and an antenna gain of 2 dB; the magnetic grating ruler has a reading resolution of 5 μm and an accuracy of ±50 μm / m.

[0076] When the measuring device is fixed inside the turntable frame, everything except the receiving antenna end face is covered by absorbing material. The trajectory of the receiving antenna is symmetrical along the center of the turntable's rotation axis. The absorbing material covers the turntable connection structure, receiving antenna, adapter, linear slide bar, magnetic scale, and motor; the receiving antenna end face is outside the absorbing material.

[0077] Other equipment operates below the turntable. One signal source (first signal source, labeled 11 in the diagram) is connected to the transmitting antenna of the measurement target system, and another signal source (second signal source, labeled 12 in the diagram) is connected to the receiving antenna on the turntable. The output signals from both signal sources are converted into intermediate frequency (IF) signals by two mixers, then amplified and connected to an IF vector network analyzer. The computer acquires the vector network measurement signals. The magnetic scale digital display and motor control are connected to the computer. The turntable, receiving antenna movement motor, and magnetic scale remain connected to the computer.

[0078] Specifically, the output signals from the first and second signal sources are mixed to generate an intermediate frequency (IF) signal; an amplifier amplifies the IF signal; a vector network analyzer converts the amplified IF signal into a vector network measurement signal; and a computer acquires the vector network measurement signal. The magnetic scale digital display and motor controller are connected to the computer; the turntable, motor, and magnetic scale are also connected to the computer. The turntable controller is integrated into the turntable equipment.

[0079] The measurement software includes a turntable and antenna motion control module, a network analyzer data acquisition module, and a data storage and processing module.

[0080] This invention relates to a testing device and method for the characteristics of a hardware-in-the-loop (HIL) system for radio frequency (RF) guidance and control, or a hardware-in-the-loop (HIL) system for RF / infrared composite guidance and control. Specifically, this invention provides a testing device and method for RF field characteristics based on turntable spin for HIL systems, solving the problem of high-precision measurement of the RF quiet zone field amplitude and phase distribution in HIL systems.

[0081] This invention also discloses a method for testing radio frequency field characteristics. The method includes installing the equipment on a turntable, setting up a dial indicator, preparing the system, starting the test, measuring within 0° to (180-N)° of the turntable's inner frame, measuring within 180° to (360-N)° of the turntable's inner frame, averaging the two measurements, subtracting the phase value of the center point rotating with the inner frame, spherical fitting, obtaining the amplitude and phase distribution, calculating the variance of the amplitude and phase distribution, and calculating the angular simulation error. N is the measurement angle interval, such as 10°.

[0082] Before installing the testing equipment onto the turntable, first measure the height from the turntable connecting flange surface to the turntable's rotation center, and adjust the height of the measuring device cylinder to ensure that the phase center of the receiving antenna is at the turntable's rotation center. After installing it onto the turntable's inner frame, fix the dial indicator at a suitable position outside the turntable's inner frame, and use the dial indicator to ensure that the antenna's zero point is at the turntable's rotation center, and use this point as the zero point of the measurement plane center.

[0083] As the inner frame of the turntable rotates to a certain angle, the receiving antenna moves from one end to the other on a linear slide bar. When the inner frame of the turntable rotates from 0° at intervals of N° to (360-N)°, the receiving antenna completes two measurements in one quiet zone plane.

[0084] When the height of the measuring device changes, the position of the quiet zone plane measured by the receiving antenna changes, thus obtaining the electromagnetic field measurement data of the quiet zone plane at different positions in the quiet zone three-dimensional space.

[0085] This invention enables the measurement of the quiet zone radio frequency field characteristics of a radio frequency hardware-in-the-loop system or a radio frequency / infrared composite hardware-in-the-loop system, and the calculation of the quiet zone simulation angle error, thereby evaluating the radio frequency field simulation characteristics.

[0086] Figure 2 This is a schematic diagram of the quiet zone RF field characteristic testing process. It mainly includes:

[0087] Step 1: Connect all components correctly. Install the upper turntable part into the inner frame of the turntable. Rotate the inner frame of the turntable to ensure that the measuring device can rotate with it without structural interference or cable pulling.

[0088] Step 2: Adjust the receiving antenna to the middle position of the magnetic scale, fix the dial indicator at a suitable position outside the inner frame of the turntable, rotate the microwave antenna one full turn and dial the indicator to ensure that the initial position of the receiving antenna is at the center of the inner frame rotation with an error of less than 0.02mm, and mark this position as zero point 0.

[0089] Step 3: Turn on the signal source, network analyzer, and other equipment placed on the ground, set the measurement frequency, and conduct the test after the equipment stabilizes.

[0090] Step 4: Set all axes of the turntable, except for the inner frame, to the zero position. Set the turntable to position control mode. When the inner frame is at 0°, start the receiving antenna from one end of the magnetic scale (L / 2) and test point by point at intervals of Mmm until the other end (-L / 2).

[0091] Step 5: At N° intervals, the receiving antenna scans from one end to the other within the inner frame of the turntable; the inner frame rotates from 0° to (180-N)°, and the amplitude and phase measurements and reference values ​​at each point in the quiet zone plane are recorded.

[0092] Step 6: Continue to rotate the inner frame from 180° to (360-N)°, and record the amplitude and phase measurements and reference values ​​at each point in the quiet zone plane again.

[0093] Step 7: Perform matrix transformation on the two amplitude and phase distribution test data to obtain two sets of amplitude and phase measurements at the same physical point; average the amplitude and phase values ​​at the same location to obtain the self-calibrated amplitude distribution E and phase distribution Q in the quiet zone plane, as shown in the figure. Figure 3 .

[0094] Step 8: Considering the characteristics of the circularly polarized antenna, subtract the phase value of the center point from the phase value of each point on each scan line to obtain the phase distribution Q1 after removing the influence of the circularly polarized receiving antenna. The phase distribution is as follows: Figure 4 .

[0095] Step nine: Perform spherical wave fitting on the measured phase value Q1 to obtain the fitted phase value Q2, as follows. Figure 5 .

[0096] Step 10: Subtract the measured value Q1 from the fitted value Q2 to obtain the phase fluctuation φ in the measured plane, as follows. Figure 6 .

[0097] Step 11: Calculate the variance σ1 of the phase fluctuations in the plane according to equation (1);

[0098]

[0099] In the formula:

[0100] —Measures the average value of phase fluctuations within a plane, in °;

[0101] n — the number of points in the measurement plane;

[0102] i — the i-th point in the measurement plane;

[0103] φ i —Measure the phase fluctuation of the current i-th point in the plane.

[0104] Step 12: Calculate the variance σ2 of the amplitude fluctuation in the plane according to equation (2);

[0105]

[0106] In the formula:

[0107] —Measure the average amplitude within the plane, in dB;

[0108] n — the number of points in the measurement plane;

[0109] E i —Measure the amplitude at the i-th point in the plane.

[0110] Step 13: According to the phase-to-angle measurement formula (3), substitute the phase variance to calculate the angle simulation error Δθ.

[0111]

[0112] In the formula:

[0113] △θ — Simulated angle, °;

[0114] σ1 — Phase difference, °;

[0115] λ — Antenna wavelength, mm;

[0116] d——The distance between the two phase angle measuring lines, in mm.

[0117] Step fourteen: Adjust the height of the receiving antenna and the turntable rotation center, and repeat steps four to thirteen to obtain the amplitude variance, phase fluctuation variance, and angular simulation error of different planes in the quiet zone three-dimensional space.

[0118] The measurement software is installed in the computer. The turntable and antenna motion control module controls the movement of the turntable and the receiving antenna respectively. It is used to control the rotation of the inner frame of the turntable and the movement of the receiving antenna on the slide rod in real time during the measurement process. It continuously and automatically controls the turntable and the receiving antenna according to the pre-set configuration file, corresponding to steps four to six.

[0119] After the receiving antenna moves to the set point, the network analyzer's data acquisition module directly reads the amplitude and phase at that point from the network analyzer. This corresponds to the recorded measurement and reference values ​​in steps five and six.

[0120] The data storage and processing module saves the amplitude and phase of each point and performs steps seven through fourteen.

[0121] This invention can realize the static zone radio frequency field characteristics of a radio frequency guidance and control hardware-in-the-loop simulation system or a radio frequency / infrared composite guidance and control hardware-in-the-loop simulation system, calculate the static zone simulation angle error, and thus evaluate the simulation characteristics of radio frequency targets.

[0122] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0123] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A radio frequency field characteristic testing device, characterized in that, This includes the connection structure with the turntable, receiving antenna, adapter, linear slide bar, magnetic scale, and motor; The structure connecting to the turntable includes a scanning chassis, a cylinder, and a connecting flange; The linear slide bar, magnetic scale, and motor are all fixed on the scanning chassis; The linear slide bar and the magnetic scale are placed side by side; A slider slides on the linear slide bar, and the receiving antenna is mounted on the slider via an adapter. The magnetic head of the magnetic scale is mounted on the slider, and the magnetic scale measures the displacement of the receiving antenna; The motor drives the receiving antenna to move; One end of the cylinder is located on the bottom surface of the scanning chassis away from the linear slide bar, and the cylinder has the function of extending and retracting along the normal direction perpendicular to the scanning chassis. The other end of the cylinder is mounted on the connecting flange; The connecting flange is fixed to the inner frame of the turntable; The field distribution in the plane is obtained by rotating the receiving antenna twice within a 360° range, and measurement errors and spherical wave errors are eliminated by data processing; The testing method includes the following steps: Step 1: Connect all components correctly, install the upper turntable part on the inner frame of the turntable, rotate the inner frame of the turntable, and confirm the measuring device; Step 2: Adjust the receiving antenna to the middle position of the magnetic scale, fix the dial indicator outside the inner frame of the turntable, rotate the microwave antenna one full turn and press the dial indicator to ensure that the initial position of the receiving antenna is at the center of the inner frame rotation with an error of less than 0.02mm, and mark this position as zero point 0; Step 3: Turn on the signal source and vector network analyzer, set the measurement frequency, and perform the test after it stabilizes; Step 4: Set the turntable to position control mode. When the inner frame of the turntable is at 0°, the receiving antenna starts from L / 2 at one end of the magnetic scale and performs point-by-point testing at intervals of Mmm until the other end -L / 2. Where L represents the distance that the receiving antenna can move on the linear slide bar. Step 5: At N° intervals, the receiving antenna scans from one end to the other within the inner frame of the turntable; the inner frame rotates from 0° to (180-N)°, and the amplitude, phase measurement, and reference values ​​at each point in the quiet zone plane are recorded. Step 6: Continue to rotate the inner frame of the turntable from 180° to (360-N)°, and record the amplitude, phase measurement value and reference value of each point in the quiet zone plane again; Step 7: Perform matrix transformation on the amplitude and phase distribution test data to obtain the amplitude and phase measurements at the same physical point; average the amplitude and phase values ​​at the same location to obtain the calibrated amplitude distribution E and phase distribution Q in the quiet zone plane; Step 8: Subtract the phase value of the center point from the phase value of each point on each scan line to obtain the measured phase value Q1; Step 9: Perform spherical wave fitting on the measured phase value Q1 to obtain the fitted phase value Q2; Step 10: Subtract the measured phase value Q1 from the fitted phase value Q2 to obtain the phase fluctuation in the measured plane. ; Step 11: Calculate the variance of phase ripples in the plane. ; In the formula: It represents the average value of the phase fluctuations within the measurement plane; Indicates the number of points within the measurement plane; Indicates the first in the measurement plane i Phase fluctuations at each point; Step 12: Calculate the variance of amplitude fluctuations within the plane. ; In the formula: This represents the average amplitude within the measurement plane; Indicates the first in the measurement plane i The amplitude at each point; Step 13: Based on the phase-to-angle measurement formula, substitute the phase variance to calculate the angular simulation error Δ. ; In the formula: λ represents the antenna wavelength; d represents the distance between the two antennas being measured. Step Fourteen: Adjust the height of the receiving antenna and the turntable rotation center, and repeat steps four to thirteen to obtain the amplitude variance, phase fluctuation variance and angular simulation error of different planes in the quiet zone three-dimensional space.

2. The radio frequency field characteristic testing device according to claim 1, characterized in that, The receiving antenna includes a circularly polarized antenna, the diameter of the receiving port of the circularly polarized antenna is less than 20mm, and the antenna gain is 2dB; The magnetic grating ruler has a reading resolution of 5μm and an accuracy of ±50μm / m.

3. The radio frequency field characteristic testing device according to claim 1, characterized in that, The testing apparatus also includes a dial indicator; The dial indicator is fixed outside the inner frame of the turntable; The receiving antenna end face is checked with a dial indicator to ensure that the zero position of the receiving antenna is at the rotation center of the turntable.

4. The radio frequency field characteristic testing device according to claim 1, characterized in that, The testing device also includes microwave absorbing materials; The absorbing material covers the turntable connection structure, receiving antenna, adapter, linear slide bar, magnetic scale, and motor; The receiving antenna end face is located outside the absorbing material.

5. The radio frequency field characteristic testing device according to claim 1, characterized in that, The test setup also includes a first signal source, a second signal source, a mixer, an amplifier, a vector network analyzer, and a computer, all located under the turntable. The first signal source is connected to the transmitting antenna of the measurement target system; The second signal source is connected to the receiving antenna on the turntable; The output signals of the first signal source and the second signal source are used to generate an intermediate frequency signal through a mixer; The amplifier amplifies the intermediate frequency signal; The vector network analyzer converts the amplified intermediate frequency signal into a vector network measurement signal; The computer acquires vector network measurement signals.

6. The radio frequency field characteristic testing device according to claim 5, characterized in that, The testing device also includes a magnetic scale digital display and a motor controller; The magnetic scale digital display and the motor controller are respectively connected to the computer.

7. A method for testing radio frequency field characteristics, characterized in that, Using the RF field characteristic testing device according to any one of claims 1-6, the testing device is equipped with a turntable, a dial indicator is set, and the test begins. Measurements are taken within 0°~(180-N)° of the inner frame of the turntable, and within 180°~(360-N)° of the inner frame of the turntable. The average of the measured values ​​is taken, and the phase value of the center point rotating with the inner frame of the turntable is subtracted. Spherical fitting is performed to obtain the amplitude and phase distribution. The variance of the amplitude and phase distribution is calculated, and the angular simulation error is calculated.

8. The radio frequency field characteristic testing method according to claim 7, characterized in that, Before installing the testing device onto the turntable, first measure the height from the turntable connecting flange surface to the turntable's rotation center, and adjust the height of the measuring device cylinder to ensure that the phase center of the receiving antenna is at the turntable's rotation center. After installation on the turntable's inner frame, fix the dial indicator outside the turntable's inner frame, and use the dial indicator to ensure that the zero point of the receiving antenna is at the turntable's rotation center, and use the zero point of the receiving antenna as the center zero point of the measurement plane.

9. The radio frequency field characteristic testing method according to claim 7, characterized in that, When the inner frame of the turntable rotates to a certain angle, the receiving antenna moves from one end to the other on the linear slide bar; when the inner frame of the turntable rotates from 0° at intervals of N° to (360-N)°, the receiving antenna completes the measurement of a quiet zone plane; When the height of the measuring device changes, the position of the quiet zone plane measured by the receiving antenna changes, thus obtaining the electromagnetic field measurement data of the quiet zone plane at different positions in the quiet zone three-dimensional space.

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