Antenna far field test system and method based on weather radar base data

Abstract

The invention discloses an antenna far field test system and method based on weather radar base data, and relates to the technical field of weather radar test. The transmitting antenna is mounted on the first antenna turntable and rotates along azimuth, pitching and polarization axes; an antenna to be tested and a standard horn antenna are installed on a second antenna rotary table through a radar receiver, the aperture faces of the antenna to be tested and the standard horn antenna form an included angle of 180 degrees, mechanical axes are coaxial, and the antenna to be tested and the standard horn antenna rotate along azimuth and pitch axes. The data processing device is connected with the radar receiver. The testing process is simplified, and the equipment cost and the maintenance cost are remarkably reduced. The test time is shortened, and the test precision of gain, beam width, sidelobe level and the like of the to-be-tested antenna is improved. The whole system has wider adaptability in practical application and is not limited by specific climate conditions. The test process is accelerated, and errors caused by human factors are reduced. The method has the advantages of simplicity in operation, high automation degree, high adaptability and the like, and the measurement precision and the test efficiency of antenna performance parameters are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of weather radar testing, and in particular to an antenna far-field testing system and an antenna far-field testing method based on weather radar base data. Background Art

[0002] In modern radar systems, the performance of antennas directly affects the detection capability and accuracy of radars. Especially for weather radars, the accuracy and stability of their detection are crucial for weather forecasting and disaster warning. Weather radars detect targets in the atmosphere, such as precipitation, clouds, etc., by transmitting and receiving electromagnetic waves. Parameters such as antenna gain, beam width, and sidelobe level determine the detection capability of the radar system.

[0003] Traditional antenna testing methods usually involve complex test site layout, large turntables, and high-precision and expensive measurement equipment (such as spectrum analyzers, vector network analyzers, etc.). In addition, on-site testing of weather radar antennas often uses methods such as setting up signal sources and standard speakers to manually test antenna gain and antenna patterns to obtain antenna indicators. The test has poor accuracy and low efficiency, is easily affected by multipath, and has high technical requirements for operators.

[0004] In addition, in actual applications, the antenna test of the weather radar system is also affected by weather conditions. For example, environmental factors such as wind speed, humidity, temperature changes, and the antenna cover may affect the electrical performance of the antenna, thereby affecting the accuracy of the test. Summary of the invention

[0005] In view of the above problems, the present invention proposes an antenna far-field testing system and an antenna far-field testing method based on weather radar base data to overcome the shortcomings of the prior art.

[0006] The embodiment of the present invention provides an antenna far-field test system based on weather radar base data. The antenna far-field test system includes: a transmitting antenna, an antenna to be tested, a standard horn antenna, a first antenna turntable, a second antenna turntable, a radar receiver and a data processing device; The transmitting antenna is mounted on a first antenna turntable and rotates along the azimuth, elevation and polarization axes; The antenna to be tested and the standard horn antenna are both installed on the second antenna turntable through the radar receiver, with their mouth faces facing each other at an angle of 180°, and their mechanical axes being coaxial, and rotating along the azimuth and elevation axes; The data processing device is connected to the radar receiver; When the transmitting antenna transmits a signal, its azimuth and polarization axis are aligned with the antenna to be tested or the standard horn antenna, and the polarization axis of the transmitting antenna can be changed during the test to measure the polarization performance of the antenna to be tested.

[0007] Optionally, the transmitting antenna is connected to a signal source, and is used to transmit a radio frequency signal generated by the signal source, where the radio frequency signal is a signal with known characteristics; The antenna to be tested is connected to the radar receiver, and the antenna to be tested is used to receive the radio frequency signal to obtain a first received signal; The standard horn antenna is connected to the radar receiver, and the standard horn antenna is used to receive the radio frequency signal to obtain a second received signal; The radar receiver is used to collect the first received signal and the second received signal, and transmit them to the data processing device; The data processing device is used to analyze and process the first received signal and the second received signal, generate an antenna pattern, a first sidelobe level and a far-end sidelobe level parameter, and calculate the gain of the antenna to be tested; The gain of the standard horn antenna is known at the design frequency of the antenna to be tested, and the known gain is used to compare with the first received signal to measure the gain of the antenna to be tested.

[0008] Optionally, the first end of the standard horn antenna receives the radio frequency signal, and the second end is connected to the first end of the first waveguide coaxial converter; The second end of the first waveguide-to-coaxial converter is connected to the first end of the coaxial cable; The second end of the coaxial cable is connected to the first end of the second waveguide-to-coaxial converter; The second end of the second waveguide coaxial converter is connected to the first end of the radar receiver; The second end of the radar receiver is connected to the data processing device; Wherein, the coaxial cable is a low-loss ultra-flexible coaxial radio frequency cable, and its length is 3 to 4 meters.

[0009] An embodiment of the present invention provides an antenna far-field testing method based on weather radar base data, the antenna far-field testing method is implemented using any of the above-mentioned antenna far-field testing systems based on weather radar base data, and the antenna far-field testing method includes: Perform multiple scans using the antenna to be tested and the radar receiver in different scanning modes and different processing parameters; Using the antenna to be tested and the standard horn antenna to respectively receive the signal transmitted each time by the transmitting antenna; Using the radar receiver to collect a plurality of first received signals from the antenna to be tested and a plurality of second received signals from the standard horn antenna, and transmit them to the data processing device; The data processing device is used to process and analyze each of the first received signals and each of the second received signals to obtain the antenna pattern, the first sidelobe level and the far-end sidelobe level of the antenna to be tested, and the gain of the antenna to be tested is calculated.

[0010] Optionally, performing multiple scans using the antenna to be tested and the radar receiver in different scanning modes and different processing parameters includes: Using the antenna to be tested to scan in a PPI fan scanning mode and a RHI scanning mode respectively; The antenna to be tested and the radar receiver are used to perform scanning in the PPI sector scanning mode and the RHI scanning mode with different scanning angle ranges, different scanning speeds and processing parameters.

[0011] Optionally, using the data processing device to process and analyze each of the first received signals and each of the second received signals to obtain an antenna pattern, a first sidelobe level, and a far-end sidelobe level parameter of the antenna to be tested, and to calculate a gain of the antenna to be tested, includes: Preprocessing each of the first received signals and each of the second received signals using the data processing device to obtain respective corresponding stable and reliable first preprocessed signals and second preprocessed signals; Using the data processing device in combination with a fitting algorithm to fit the first preprocessed signal, to generate an antenna pattern of the antenna to be tested; Determine the beam width of the antenna to be tested from the antenna pattern of the antenna to be tested by using the data processing device in combination with the 3dB method; Analyzing the antenna pattern of the antenna to be tested by using the data processing device to calculate the first sidelobe level and the far-end sidelobe level of the antenna to be tested; The second preprocessed signal is processed by the data processing device to obtain the peak signal strength in the antenna pattern of the standard horn antenna, and compared with the peak signal strength in the first antenna pattern of the antenna under test to calculate the gain of the antenna under test.

[0012] Optionally, using the data processing device in combination with a fitting algorithm to fit the first preprocessed signal to generate an antenna pattern of the antenna to be tested includes: Using the data processing device, retain data whose received intensity has a difference of ≥-6 dB compared to the maximum intensity value, and based on the retained data combined with the least squares method, perform quadratic linear fitting on the first preprocessed signal to generate an antenna pattern of the antenna to be tested; Among them, the formula for quadratic linear fitting is:

[0013]

[0014]

[0015] In the above three formulas, Indicates the average azimuth or elevation angle. Indicates the average value of the echo at each position; The equation y corresponding to the antenna pattern of the antenna to be tested is calculated using the above three equations: y=ax 2 +bx+c In the above formula, x represents the antenna azimuth or elevation angle, a, b and c are constant terms obtained by quadratic linear fitting, and y represents the antenna receiving signal strength fitted at each position.

[0016] Optionally, using the data processing device in combination with a 3dB method to determine the beam width of the antenna to be tested from the antenna pattern of the antenna to be tested includes: Calculate the azimuth or elevation angle corresponding to the maximum value of the antenna pattern of the antenna to be tested, where the azimuth or elevation angle is the azimuth angle x where the main lobe is located. ML :

[0017] x ML The maximum value of the corresponding echo intensity is the main lobe intensity value of the antenna pattern of the antenna to be tested. ML for:

[0018] Obtain the main lobe intensity value y ML The difference with the 3dB level gives the corresponding x l With x r value, and get the 3dB beamwidth θ :

[0019]

[0020] In the above three equations, x l The angle where the level on the left side is 3dB lower than the main lobe level, x r Indicates the angle at which the level on the right side decreases by 3dB compared to the main lobe level.

[0021] Optionally, using the data processing device to analyze the antenna pattern of the antenna to be tested, and calculating a first sidelobe level and a far-end sidelobe level of the antenna to be tested, comprises: Analyzing the side lobe area of ​​the antenna pattern of the antenna to be tested by using the data processing device, and calculating the first side lobe level and the far-end side lobe level of the antenna to be tested; Among them, the first sidelobe level S FL for: S FL =max(A L , A R )-y ML In the above formula, A L With A R Respectively represent the left and right sides of the main lobe of the antenna pattern, and the side lobe level closest to the main lobe, max (A L , A R ) indicates A L With A R The maximum value in ; The far-end sidelobe level S SL for: S FL =max(A LD , A RD )-y ML In the above formula, A LD With A RD They represent the side lobe levels closest to the main lobe on the left and right sides of the maximum side lobe level value outside the main lobe ±10° in the antenna radiation pattern, max (A LD , A RD ) indicates A LD With A RD The maximum value in .

[0022] Optionally, using the data processing device to process the second preprocessed signal to obtain a peak signal strength in the antenna pattern of the standard horn antenna, and comparing it with the peak signal strength in the first antenna pattern of the antenna under test, to calculate the gain of the antenna under test, including: The formula for calculating the gain G of the antenna to be tested is: G=G hor +HH hor +LL hor =Ghor+ΔH+ΔL In the above formula, H and H hor represent the strength of the first received signal and the strength of the second received signal respectively; G hor represents the actual gain; L and L horThey respectively represent the receiving branch loss of the antenna under test and the cable loss from the standard horn antenna to the front end of the radar receiver in the frequency band of the antenna under test; ΔH represents the signal strength difference between the antenna under test and the standard horn antenna; ΔL represents the loss difference between the antenna under test and the standard horn antenna.

[0023] The antenna far-field test system based on weather radar basic data proposed in the present invention includes: a transmitting antenna, an antenna to be tested, a standard horn antenna, a first antenna turntable, a second antenna turntable, a radar receiver and a data processing device. The transmitting antenna is installed on the first antenna turntable and rotates along the azimuth, elevation and polarization axes; the antenna to be tested and the standard horn antenna are both installed on the second antenna turntable through the radar receiver, and the two faces are oriented at an angle of 180°, and the mechanical axes are coaxial, and rotate along the azimuth and elevation axes; the data processing device is connected to the radar receiver. Among them, when the transmitting antenna transmits a signal, its azimuth and polarization axis are aligned with the antenna to be tested or the standard horn antenna, and the polarization axis of the transmitting antenna can be changed during the test to measure the polarization performance of the antenna to be tested.

[0024] The present invention proposes a far-field antenna test system and method, creatively proposing a set of brand-new far-field antenna test system and test method based on the system. Only simple equipment such as an antenna turntable (the second antenna turntable can be replaced by a radar turntable), a transmitting antenna, and a standard horn antenna are needed to test the antenna to be tested in an open field or without particularly strict environmental requirements, which simplifies the test process, reduces the multipath effect, and makes the test process no longer dependent on special environments. This simplification significantly reduces equipment costs and maintenance costs, and also makes the test work more flexible and easy to operate.

[0025] The far-field signal is transmitted by the transmitting antenna, and the antenna under test quickly collects the signal. The signal is analyzed and processed based on the radar receiver and data processing device, which shortens the test time and improves the test accuracy of the antenna gain, beam width and sidelobe level under test.

[0026] And because of the radar fast scanning method, the test cycle is very short, each test can be completed within tens of seconds, and the radar receiver can also accumulate received signals (in the traditional test method, the turntable rotates at fixed intervals, and the antenna is stationary and the spectrum analyzer is used to analyze the received signal. The test time period is long and it is difficult to quickly accumulate signals). Therefore, it can meet the test under various environmental conditions, including the situation of large wind speed changes, especially when the wind speed is below 10m / s, the system can still operate stably and ensure measurement accuracy, reducing the impact of multipath and ensuring the accuracy and stability of measurement. This makes the entire system more adaptable in practical applications and is not limited to specific climatic conditions.

[0027] Through automated data acquisition, analysis, and processing, the need for manual intervention is greatly reduced. Operators can significantly reduce the time spent on data processing and analysis, improving the efficiency and consistency of test work. Data acquisition, analysis, and processing can automatically record and process received signals, generate antenna patterns for the antennas to be tested, and calculate parameters such as antenna gain, beam width, and sidelobe level. This automated process not only speeds up the test process, but also reduces errors caused by human factors. In addition, the detailed test reports generated by the system can quickly provide test results, providing engineers with a direct reference basis and further improving work efficiency.

[0028] The system and method proposed in the present invention have the advantages of simple operation, high degree of automation, strong adaptability, etc., and are particularly suitable for testing multi-band weather radar antennas such as S-band, C-band and X-band, meeting the needs of modern multi-band weather radar systems, and are also particularly suitable for testing and optimizing modern weather radar systems and other high-precision antenna systems. It can significantly improve the measurement accuracy and test efficiency of antenna performance parameters, provide strong support for the performance improvement of radar systems, and has broad application prospects and high practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings: Figure 1 This is a better architecture diagram of the antenna far-field test system in the embodiment of the present application; Figure 2 This is a diagram of a preferred connection method between a standard horn antenna and a radar receiver in an embodiment of the present application; Figure 3 It is a structural diagram from the perspective of signal flow in an embodiment of the present application; Figure 4 is a flow chart of an antenna far-field testing method based on weather radar base data according to an embodiment of the present application; Figure 5 It is the horizontal azimuth pattern (at 3 dB beam width) of the antenna to be tested obtained after actual measurement in the embodiment of the present application; Figure 6 It is the horizontal azimuth pattern (full scanning range) of the antenna to be tested obtained after actual measurement in the embodiment of the present application; Figure 7 It is the vertical azimuth pattern (at 3 dB beam width) of the antenna to be tested obtained after actual measurement in the embodiment of the present application; Figure 8It is the vertical azimuth pattern (full scanning range) of the antenna to be tested obtained after actual measurement in the embodiment of the present application; Fig. 9 is a schematic diagram of the signal strength received by the standard horn antenna obtained after actual measurement in an embodiment of the present application; Fig.10 It is a schematic diagram of the signal strength received by the antenna under test obtained after actual measurement in the embodiment of the present application. DETAILED DESCRIPTION

[0030] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, are only part of the embodiments of the present invention, not all of the embodiments, and are not used to limit the present invention.

[0031] The inventors have found that there are a series of problems in the current antenna testing methods, such as: 1) Traditional antenna testing usually requires complex equipment, complex testing processes and testing costs, such as microwave darkrooms, antenna turntables and sophisticated and expensive testing equipment (such as spectrum analyzers, vector network analyzers, etc.). The use of these devices not only increases the cost of testing, but also requires a lot of work to dismantle the built radar antenna and send it to the test site for testing. It also requires the operation of professional technicians, and the complex testing process also makes the testing process time-consuming.

[0032] 2) The existing outdoor testing methods for radar antennas have low accuracy, low testing efficiency and long testing cycles.

[0033] 3) The environmental conditions of antenna testing often affect the accuracy of the measurement results. Traditional testing methods are greatly affected by multipath interference and have high requirements for the test environment, such as being carried out under windless and dry conditions. In actual applications, the weather is unpredictable and the test accuracy cannot be well maintained under various weather conditions.

[0034] 4) The traditional antenna testing process usually requires a lot of manual operation and data recording, and the work efficiency is low.

[0035] In view of the above problems, the inventors have creatively proposed the antenna far-field testing system and antenna far-field testing method based on weather radar basic data after extensive research. The technical solution of the present invention is explained and illustrated in detail below.

[0036] The antenna far-field test system based on weather radar basic data of the present invention comprises: a transmitting antenna, an antenna to be tested, a standard horn antenna, a first antenna turntable, a second antenna turntable, a radar receiver and a data processing device. The transmitting antenna is installed on the first antenna turntable and rotates along the azimuth, elevation and polarization axes; the antenna to be tested and the standard horn antenna are both installed on the second antenna turntable through the radar receiver, and the two faces are oriented at an angle of 180°, and the mechanical axes are coaxial, and rotate along the azimuth and elevation axes. Preferably, the second antenna turntable can be replaced by a radar turntable, so that only one antenna turntable (i.e., the first antenna turntable) is actually used, which indirectly reduces the cost.

[0037] In order to better understand the antenna far-field test system of the present invention, refer to Figure 1 A better antenna far-field test system architecture diagram is shown, the first antenna turntable is located on a natural mountain, and the first antenna turntable and the second antenna turntable are in communication with the positioning control and attitude display device. The rotation of the two antenna turntables is controlled by the positioning control and attitude display device. The transmitting antenna is installed on the first antenna turntable, which is used to transmit the signal generated by the signal source and can rotate along the azimuth, elevation and polarization axes. The antenna to be tested and the standard horn antenna are both installed on the second antenna turntable through the radar receiver. The antenna to be tested and the standard horn antenna are facing at an angle of 180° (that is, the standard horn antenna is installed on the back of the antenna to be tested), and the mechanical axes of the two are coaxial, and both can rotate along the azimuth and elevation axes.

[0038] In actual testing, the distance between the transmitting antenna and the antenna under test is required to be R The antenna far-field condition is met, that is,

[0039] In the above formula, D Indicates the aperture diameter of the antenna under test, in meters (m). λ Indicates the operating wavelength in meters (m).

[0040] When the transmitting antenna transmits a signal, its azimuth and polarization axis are aligned with the antenna to be tested or the standard horn antenna, and the polarization axis of the transmitting antenna can be changed during the test to measure the polarization performance of the antenna to be tested.

[0041] The transmitting antenna is connected to a signal source, and the RF signal is a signal with known characteristics; the antenna to be tested is connected to a radar receiver, and the antenna to be tested is used to receive the RF signal to obtain a first received signal; similarly, the standard horn antenna is connected to the radar receiver, and the standard horn antenna is used to receive the RF signal to obtain a second received signal. The radar receiver is used to collect the first received signal and the second received signal, and transmit them to a data processing device; the data processing device is used to analyze and process the first received signal and the second received signal, generate an antenna radiation pattern, a first sidelobe level and a far-end sidelobe level parameter, and calculate the gain of the antenna to be tested. Among them, the gain of the standard horn antenna is known at the design frequency of the antenna to be tested, and the known gain is used to compare with the first received signal to measure the gain of the antenna to be tested.

[0042] Generally, the antenna to be tested and the radar receiver are already assembled as a whole device, while the standard horn antenna is a device temporarily added for far-field testing. Therefore, a temporary connection is required between the standard horn antenna and the radar receiver during far-field testing so that the radar receiver can receive the second receiving signal. Figure 2 As shown, the first end of the standard horn antenna receives the RF signal ( Figure 2 The second end of the radar receiver is connected to the first end of the radar receiver; the ... Figure 2 wherein the coaxial cable is a low-loss ultra-flexible coaxial RF cable, and its length is preferably 3 to 4 meters to ensure the accuracy of signal transmission.

[0043] From the perspective of signal flow, refer to Figure 3 As shown in the structural diagram, the signal source generates a signal, which is transmitted by the transmitting antenna, received by the antenna under test and the standard horn antenna, and then processed and analyzed by the data processing device to complete the antenna far-field test.

[0044] Based on the above-mentioned antenna far-field test system based on weather radar base data, the present invention also proposes an antenna far-field test method based on weather radar base data, referring to Figure 4 As shown in the flowchart, the antenna far-field testing method includes: Step 401: Use the antenna to be tested and the radar receiver to perform multiple scans in different scanning modes and different processing parameters.

[0045] The first choice is to use the antenna to be tested and the radar receiver to perform multiple scans in different scanning modes and with different processing parameters. The preferred method is: The antenna under test is scanned in PPI (Plan Position Indicator) sector scanning mode and RHI (Range Height Indicator) scanning mode respectively; PPI mode is used for all-round scanning in the horizontal plane, while RHI mode is used for vertical scanning at different elevation angles.

[0046] At the same time, the antenna to be tested and the radar receiver are used to scan in different scanning angle ranges, different scanning speeds and processing parameter modes in the PPI sector scanning mode and the RHI scanning mode. That is to say, the radar scanning angle range, scanning speed, polarization mode (horizontal polarization and vertical polarization), pulse accumulation number, pulse width, radial resolution, repetition frequency and other parameters are set. In order to ensure the accuracy of the data, it is preferred to store at least three sets of data in each mode. That is, three sets of received signal data correspond to each mode, and these data will be used for subsequent signal processing and analysis.

[0047] Step 402: Use the antenna to be tested and the standard horn antenna to receive the signal transmitted by the transmitting antenna each time.

[0048] After the transmitting antenna transmits the radio frequency signal, the antenna under test and the standard horn antenna can be used to receive the signal transmitted by the transmitting antenna each time respectively. After the antenna under test receives the signal, a first received signal is obtained, and after the standard horn antenna receives the signal, a second received signal is obtained.

[0049] Step 403: using a radar receiver to collect a plurality of first received signals from the antenna to be tested and a plurality of second received signals from the standard horn antenna, and transmit them to a data processing device.

[0050] After step 402, a plurality of first received signals from the antenna to be tested and a plurality of second received signals from the standard horn antenna are collected by a radar receiver and transmitted to a data processing device, which processes and analyzes the signals.

[0051] Step 404: Use a data processing device to process and analyze each first received signal and each second received signal to obtain the antenna pattern, the first sidelobe level and the far-end sidelobe level of the antenna to be tested, and calculate the gain of the antenna to be tested.

[0052] After step 401 to step 403, each first received signal and each second received signal are finally processed and analyzed by a data processing device to obtain the antenna pattern, the first side lobe level and the far-end side lobe level of the antenna to be tested, and the gain of the antenna to be tested is calculated. A preferred method for obtaining the antenna pattern, the first side lobe level and the far-end side lobe level of the antenna to be tested, and calculating the gain of the antenna to be tested includes: Step S1: preprocess each first received signal and each second received signal using a data processing device to obtain a first preprocessed signal and a second preprocessed signal that are stable and reliable and that correspond to each other.

[0053] After obtaining all the first received signals and the second received signals, these signals need to be preprocessed first, for example: ground clutter identification, automatic calculation of the optimal distance library selection, antenna received power inversion, etc. This can make the preprocessed data more stable and reliable, and lay a better and more accurate foundation for subsequent signal processing and analysis. After preprocessing the first received signal, the corresponding stable and reliable first preprocessed signal is obtained, and after preprocessing the second received signal, the second preprocessed signal is obtained. Step S2: Using a data processing device, retain the data of the antenna pattern data whose receiving intensity is ≥-6dB compared to the maximum intensity value, and fit the first preprocessed signal based on the retained data in combination with a fitting algorithm to generate the antenna pattern of the antenna to be tested.

[0054] The antenna pattern is a representation of the antenna radiation characteristics, which shows the gain distribution of the antenna in different directions. Since the antenna under test is affected by the test environment, the antenna pattern measured by the radar cannot represent the actual antenna pattern. Therefore, it is necessary to fit the first preprocessed signal in combination with the fitting algorithm to generate the fitting antenna pattern of the antenna under test.

[0055] Preferably, the least square method can be combined to perform quadratic linear fitting on the first preprocessed signal to generate the antenna pattern of the antenna to be tested; Among them, the formula for quadratic linear fitting is:

[0056]

[0057]

[0058] In the above three formulas, Indicates the average azimuth or elevation angle. Represents the average value of the echo in each azimuth; the equation y corresponding to the antenna pattern of the antenna to be tested is calculated using the above three equations: y=ax 2 +bx+c In the above formula, x represents the antenna or elevation angle, a, b and c represent the constant terms of the quadratic linear fitting, and y represents the antenna signal strength fitting value at the current position.

[0059] Step S3: using a data processing device in combination with a 3dB method, the beam width of the antenna to be tested is determined from the antenna radiation pattern of the antenna to be tested.

[0060] After obtaining the antenna pattern of the antenna to be tested, the data processing device is used to determine the beam width of the antenna to be tested from the antenna pattern of the antenna to be tested in combination with the 3 dB method. The beam width is determined from the antenna pattern by the 3 dB method. The beam width is an important indicator of antenna performance, which reflects the directivity and resolution of the antenna to be tested.

[0061] The better method is: first calculate the azimuth or elevation angle corresponding to the maximum value of the antenna pattern of the antenna to be tested, and the azimuth or elevation angle is the azimuth or elevation angle x where the main lobe is located. ML :

[0062] x ML The maximum value of the corresponding echo intensity is the main lobe intensity value of the antenna pattern of the antenna to be tested. The main lobe intensity value y ML for:

[0063] Calculate the main lobe strength value y ML is the difference from the 3dB level, and the corresponding x l With x r value, get 3dB beamwidth θ :

[0064]

[0065] In the above three equations, x l The angle where the level on the left side is 3dB lower than the main lobe level, x r Indicates the angle at which the level on the right side decreases by 3dB compared to the main lobe level.

[0066] Step S4: Analyze the antenna pattern of the antenna to be tested by using a data processing device, and calculate the first sidelobe level and the far-end sidelobe level of the antenna to be tested.

[0067] At the same time, the first sidelobe level and far-end sidelobe level of the antenna under test are calculated through the antenna pattern of the antenna under test. The sidelobe area of ​​the antenna pattern is analyzed to calculate the levels of the first sidelobe and far-end sidelobe. These sidelobe levels determine the ability of the antenna under test to receive or transmit signals in the non-main beam direction, which has an important impact on the anti-interference ability and detection sensitivity of the radar system.

[0068] Preferably, a data processing device is used to analyze the side lobe area of ​​the antenna pattern of the antenna to be tested, and a first side lobe level and a far-end side lobe level of the antenna to be tested are calculated; Among them, the first sidelobe level S FL for: SFL =max(A L , A R )-y ML In the above formula, A L With A R Respectively represent the left and right sides of the main lobe of the antenna pattern, and the side lobe level closest to the main lobe, max (A L , A R ) indicates A L With A R The maximum value in ; Far-end sidelobe level S SL for: S FL =max(A LD , A RD )-y ML In the above formula, A LD With A RD They represent the sidelobe levels closest to the main lobe on the left and right sides of the antenna radiation pattern, which are ±10° away from the main lobe, max (A LD , A RD ) indicates A LD With A RD The maximum value in .

[0069] Step S5: Using a data processing device to process the second preprocessed signal to obtain the peak signal strength in the antenna pattern of the standard horn antenna, and compare it with the peak signal strength in the first antenna pattern of the antenna under test to calculate the gain of the antenna under test.

[0070] The antenna pattern, first sidelobe level and far-end sidelobe level parameters of the antenna to be tested are obtained in the above method. As for the gain, it is necessary to use a data processing device to process the second preprocessed signal to obtain the peak signal strength in the antenna pattern of the standard horn antenna, and compare the peak signal strength in the first antenna pattern of the antenna to be tested to calculate the gain of the antenna to be tested (the actual gain is equal to or similar to the factory test gain of the antenna to be tested. If the difference between the two is large, it is considered that the standard horn antenna may have problems and needs to be tested or a new standard horn antenna is used).

[0071] The optimal formula for calculating the gain G of the antenna to be tested is: G=G hor +HH hor +LL hor =G hor +ΔH+ΔL In the above formula, H and H hor Respectively represent the strength of the first received signal and the strength of the second received signal; G horIndicates the actual gain of the standard horn antenna in the frequency band of the antenna to be tested; L and L hor They represent the receiving branch loss of the antenna under test and the cable loss from the standard horn antenna to the front end of the radar receiver in the frequency band of the antenna under test; ΔH represents the difference in signal strength between the antenna under test and the standard horn antenna; ΔL represents the difference in loss between the antenna under test and the standard horn antenna. In the actual test process, multiple measurements can be taken to get the average value, so that the test results are more accurate.

[0072] As for the data processing device, it can be configured as an automated data acquisition and analysis system, including specially developed software. The functions of this system include: Automatic data recording: Automatically record all collected data (all received signals) during the test process to reduce human operation errors.

[0073] Data analysis and report generation: Automatically analyze the collected data, generate the calculation results of the antenna pattern and various performance parameters, and generate a detailed test report.

[0074] User interface: Provides a friendly user interface to facilitate operators to set up tests, view data and export results.

[0075] Since the antenna far-field test system and method of the present invention are highly automated and standardized, operators do not need to have a deep technical background or professional skills to complete the test work. The friendly user interface and automated functions greatly simplify the operation process and reduce the difficulty of operation. This not only helps to reduce training costs, but also reduces test errors caused by improper operation. At the same time, using the antenna far-field test system and method to obtain more accurate antenna tests helps to improve the overall performance of the radar system, including detection accuracy and anti-interference capabilities. The more accurate antenna gain, beam width, sidelobe level and other parameters after the test enable the radar antenna system to more accurately detect and identify targets in practical applications, improving the accuracy and timeliness of weather forecasts and disaster warnings.

[0076] In order to verify the effectiveness of the antenna far-field test system and method proposed in the present invention, a certain S-band (2.7~3.0GHz) antenna to be tested was tested using the proposed antenna far-field test system and method. The test environment was selected in an open outdoor area to avoid interference from buildings and other objects to the signal. A standard gain speaker was used as the signal source, and the frequency range covered the S-band. The test adopted the PPI (Plan Position Indicator) fan scanning mode and the RHI (Range Height Indicator) scanning mode, which were used for all-round scanning in the horizontal and vertical directions, respectively. In PPI mode, the horizontal scanning range is 360 degrees, and the scanning speed is set to 1 degree / second. In RHI mode, the elevation angle range is set to 0 degrees to 60 degrees, and the scanning speed is 0.5 degrees / second. In each scanning mode, the received signal strength at each angle and polarization state is recorded. In order to ensure the accuracy and stability of the data, at least two independent acquisitions and records are performed in each mode.

[0077] Based on the obtained data, the antenna pattern of the antenna to be tested is obtained: the PPI mode can obtain the horizontal azimuth pattern of the antenna, and the RHI mode can obtain the vertical azimuth pattern of the antenna. Figure 5 The horizontal azimuth pattern of the antenna under test (at 3dB beam width) is shown below. Figure 5 The horizontal axis is the angle, unit is °, and the vertical axis is the intensity, unit is dB. Since the curves in the figure basically overlap, it is not possible to clearly express the meaning using all black lines, so they are shown in color view. Figure 5 The red dots represent the data received under horizontal polarization, the blue solid line represents the curve obtained by connecting the data received under horizontal polarization, the purple solid line represents the horizontal polarization direction fitting curve obtained by fitting the received data under horizontal polarization, the black dots represent the data received under vertical polarization, and the yellow solid line represents the curve obtained by connecting the data received under vertical polarization.

[0078] Reference Figure 6 The horizontal azimuth pattern of the antenna under test (full scanning range) is shown. Figure 6 The horizontal axis is the angle, unit is °, and the vertical axis is the intensity, unit is dB. As the curves in the figure are complex, it is not possible to clearly express the meaning using all black lines, so they are shown in color. Figure 6 The red dots represent the data received under horizontal polarization, the blue solid line represents the curve obtained by connecting the data received under horizontal polarization, the purple solid line represents the horizontal polarization direction fitting curve obtained by fitting the received data under horizontal polarization, the black dots represent the data received under vertical polarization, and the yellow solid line represents the curve obtained by connecting the data received under vertical polarization.

[0079] Reference Figure 7 The vertical azimuth pattern of the antenna under test (at 3dB beam width) is shown below. Figure 7 The horizontal axis is the angle, unit is °, and the vertical axis is the intensity, unit is dB. Since the curves in the figure basically overlap, it is not possible to clearly express the meaning using all black lines, so they are shown in color view. Figure 7 The red dots represent the data received under horizontal polarization, the blue solid line represents the curve obtained by connecting the data received under horizontal polarization, the purple solid line represents the fitting curve in the horizontal polarization direction obtained by fitting the received data under horizontal polarization, the black dots represent the data received under vertical polarization, and the yellow solid line represents the fitting curve in the vertical polarization direction obtained by fitting the data received under vertical polarization.

[0080] Reference Figure 8 The vertical azimuth pattern of the antenna under test (full scanning range) is shown. Figure 8 The horizontal axis is the angle, unit is °, and the vertical axis is the intensity, unit is dB. As the curves in the figure are complex, it is not possible to clearly express the meaning using all black lines, so they are shown in color. Figure 8 The red dots represent the data received under horizontal polarization, the blue solid line represents the curve obtained by connecting the data received under horizontal polarization, the purple solid line represents the horizontal polarization direction fitting curve obtained by fitting the received data under horizontal polarization, the black dots represent the data received under vertical polarization, and the yellow solid line represents the curve obtained by connecting the data received under vertical polarization.

[0081] The main beam width is extracted from the horizontal polarization pattern using the 3 dB method, and the levels of the first side lobe and the far side lobe are calculated to evaluate the directivity and anti-interference capability of the antenna under test. Figure 5 , 6 According to the results of , 7, and 8, the above formula can be used to calculate that the 3 dB beamwidth in azimuth is 0.910°, the first sidelobe level is -30.36 dB, and the far-end sidelobe level is -36.59 dB; the 3 dB beamwidth in elevation is 0.873°, the first sidelobe level is -29.89 dB, and the far-end sidelobe level is -40.15 dB.

[0082] By comparing the known gain of the standard horn antenna, the received signal strength and the received signal strength of the antenna under test, the actual gain of the antenna under test can be calculated. Taking horizontal polarization as an example, the actual measurement and calculation are combined. Fig. 9 , Fig.10 The figure shows the signal strength received by the standard horn antenna and the antenna under test in the far-field test. From the figure, we can get H=3dB, H hor= -26.22 dB. In addition, the gain of the standard horn antenna G hor At the working frequency of the antenna under test, it is 18.78 dB; the receiving branch loss L of the antenna under test is 0.57 dB; the cable loss L from the standard horn antenna to the receiver front end is hor Substituting the above result into the gain calculation formula, we can get the gain of the antenna to be tested G = 45.5 dB.

[0083] Through the above antenna radiation pattern, the main beam, the first side lobe, the far side lobe and other features are clearly marked, which proves that the antenna far-field test system and method proposed in the present invention can truly and effectively measure the antenna gain and beam width and other parameters. Then, according to the data analysis results, determine whether the performance parameters of the antenna to be tested meet the expected requirements. If not, adjust the mechanical structure or electrical parameters of the antenna to be tested to optimize its performance. After adjustment, re-collect and analyze the data to ensure that the performance of the antenna to be tested reaches the best state. The final test results show that the gain of the S-band antenna to be tested reaches the expected value, and the beam width and sidelobe level also meet the design requirements. This shows that the performance of the antenna to be tested after the far-field test has reached the expected standard, and has good directivity and anti-interference ability. The effectiveness and reliability of the antenna far-field test system and method proposed in the present invention in practical applications provide an effective solution for antenna testing of modern weather radar systems.

[0084] The above-mentioned actual measurement verification demonstrates the effectiveness and practicability of the antenna far-field testing method proposed in the present invention.

[0085] In summary, the antenna far-field test system based on weather radar basic data proposed in the present invention includes: a transmitting antenna, an antenna to be tested, a standard horn antenna, a first antenna turntable, a second antenna turntable, a radar receiver and a data processing device. The transmitting antenna is installed on the first antenna turntable and rotates along the azimuth, elevation and polarization axes; the antenna to be tested and the standard horn antenna are both installed on the second antenna turntable through the radar receiver, and the two faces are oriented at an angle of 180°, and the mechanical axes are coaxial, and rotate along the azimuth and elevation axes; the data processing device is connected to the radar receiver. Among them, when the transmitting antenna transmits a signal, its azimuth and polarization axis are aligned with the antenna to be tested or the standard horn antenna, and the polarization axis of the transmitting antenna can be changed during the test to measure the polarization performance of the antenna to be tested.

[0086] The present invention proposes a new antenna far-field test system and a test method based on the system. Only two antenna turntables, a transmitting antenna, a standard horn antenna and other simple equipment are needed to test the antenna to be tested in an open field or without particularly strict environmental requirements, which simplifies the test process, reduces the test cost, and makes the test process no longer dependent on special environments. This simplification significantly reduces equipment costs and maintenance costs, and also makes the test work more flexible and easy to operate.

[0087] The far-field signal is transmitted by the transmitting antenna, and the antenna under test quickly collects the signal. The signal is analyzed and processed based on the radar receiver and data processing device, which shortens the test time and improves the test accuracy of the antenna gain, beam width and sidelobe level under test.

[0088] And because the test cycle is very short, each test can be completed within tens of seconds, and the radar receiver can also accumulate received signals (in the traditional test method, the turntable rotates at fixed intervals, and the antenna is stationary and a spectrum analyzer is used to analyze the received signal. The test time is long and it is difficult to quickly accumulate signals). Therefore, it can meet the test under various environmental conditions, including situations where the wind speed changes greatly. In particular, when the wind speed is below 10m / s, the system can still operate stably and ensure measurement accuracy, reducing the impact of multipath and ensuring measurement accuracy and stability. This makes the entire system more adaptable in practical applications and is not limited to specific climatic conditions.

[0089] Through automated data acquisition, analysis, and processing, the need for manual intervention is greatly reduced. Operators can significantly reduce the time spent on data processing and analysis, improving the efficiency and consistency of test work. Data acquisition, analysis, and processing can automatically record and process received signals, generate antenna patterns for the antennas to be tested, and calculate parameters such as antenna gain, beam width, and sidelobe level. This automated process not only speeds up the test process, but also reduces errors caused by human factors. In addition, the detailed test reports generated by the system can quickly provide test results, providing engineers with a direct reference basis and further improving work efficiency.

[0090] In addition, the antenna far-field test system of the present invention also provides a user-friendly interface, which is convenient for operators to perform test settings, data viewing and result export. Since the antenna far-field test system of the present invention is highly automated and standardized, operators do not need to have a deep technical background or professional skills to complete the test work. The friendly user interface and automation functions greatly simplify the operation process and reduce the difficulty of operation. This not only helps to reduce training costs, but also reduces test errors caused by improper operation. At the same time, using the antenna far-field test method to obtain more accurate antenna tests helps to improve the overall performance of the radar system, including detection accuracy and anti-interference capabilities. The more accurate antenna gain, beam width, sidelobe level and other parameters after the test enable the radar antenna system to more accurately detect and identify targets in practical applications, improving the accuracy and timeliness of weather forecasts and disaster warnings.

[0091] The system and method proposed in the present invention have the advantages of simple operation, high degree of automation, strong adaptability, etc., and are particularly suitable for testing multi-band antennas such as S-band, C-band and X-band, meeting the needs of modern multi-band radar systems, and are also particularly suitable for testing and optimizing modern weather radar systems and other high-precision antenna systems. It can significantly improve the measurement accuracy and test efficiency of antenna performance parameters, provide strong support for the performance improvement of radar systems, and has broad application prospects and high practicality.

[0092] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present invention.

[0093] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or terminal device including the elements.

[0094] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation modes, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are within the protection of the present invention.

Claims

1. An antenna far-field test system based on weather radar base data, characterized in that: The antenna far-field test system comprises: a transmitting antenna, an antenna to be tested, a standard horn antenna, a first antenna turntable, a second antenna turntable, a radar receiver and a data processing device; The transmitting antenna is mounted on a first antenna turntable and rotates along the azimuth, elevation and polarization axes; The antenna to be tested and the standard horn antenna are both installed on the second antenna turntable through the radar receiver, with their mouth faces facing each other at an angle of 180°, and their mechanical axes being coaxial, and rotating along the azimuth and elevation axes; The data processing device is connected to the radar receiver; When the transmitting antenna transmits a signal, its azimuth and polarization axis are aligned with the antenna to be tested or the standard horn antenna, and the polarization axis of the transmitting antenna can be changed during the test to measure the polarization performance of the antenna to be tested.

2. The antenna far-field test system according to claim 1, characterized in that: The transmitting antenna is connected to the signal source and is used to transmit the radio frequency signal generated by the signal source, where the radio frequency signal is a signal with known characteristics; The antenna to be tested is connected to the radar receiver, and the antenna to be tested is used to receive the radio frequency signal to obtain a first received signal; The standard horn antenna is connected to the radar receiver, and the standard horn antenna is used to receive the radio frequency signal to obtain a second received signal; The radar receiver is used to collect the first received signal and the second received signal, and transmit them to the data processing device; The data processing device is used to analyze and process the first received signal and the second received signal, generate an antenna pattern, a first sidelobe level and a far-end sidelobe level parameter, and calculate the gain of the antenna to be tested; The gain of the standard horn antenna is known at the design frequency of the antenna to be tested, and the known gain is used to compare with the first received signal to measure the gain of the antenna to be tested.

3. The antenna far-field test system according to claim 2, characterized in that: The first end of the standard horn antenna receives the radio frequency signal, and the second end is connected to the first end of the first waveguide coaxial converter; The second end of the first waveguide-to-coaxial converter is connected to the first end of the coaxial cable; The second end of the coaxial cable is connected to the first end of the second waveguide-to-coaxial converter; The second end of the second waveguide coaxial converter is connected to the first end of the radar receiver; The second end of the radar receiver is connected to the data processing device; Wherein, the coaxial cable is a low-loss ultra-flexible coaxial radio frequency cable, and its length is 3 to 4 meters.

4. A method for antenna far-field testing based on weather radar base data, characterized in that: The antenna far-field testing method is implemented by using the antenna far-field testing system based on weather radar base data according to any one of claims 1 to 4, and the antenna far-field testing method comprises: Perform multiple scans using the antenna to be tested and the radar receiver in different scanning modes and different processing parameters; Using the antenna to be tested and the standard horn antenna to respectively receive the signal transmitted each time by the transmitting antenna; Using the radar receiver to collect a plurality of first receiving signals from the antenna to be tested and a plurality of second receiving signals from the standard horn antenna, and transmit them to the data processing device; The data processing device is used to process and analyze each of the first received signals and each of the second received signals to obtain the antenna pattern, the first sidelobe level and the far-end sidelobe level of the antenna to be tested, and the gain of the antenna to be tested is calculated.

5. The antenna far-field testing method according to claim 4, characterized in that: Performing multiple scans using the antenna to be tested and the radar receiver in different scanning modes and different processing parameters includes: Using the antenna to be tested to scan in a PPI fan scanning mode and a RHI scanning mode respectively; The antenna to be tested and the radar receiver are used to perform scanning in the PPI sector scanning mode and the RHI scanning mode with different scanning angle ranges, different scanning speeds and processing parameters.

6. The antenna far-field testing method according to claim 4, characterized in that: Using the data processing device to process and analyze each of the first received signals and each of the second received signals to obtain the antenna pattern, the first sidelobe level, and the far-end sidelobe level parameters of the antenna to be tested, and to calculate the gain of the antenna to be tested, including: Preprocessing each of the first received signals and each of the second received signals using the data processing device to obtain respective corresponding stable and reliable first preprocessed signals and second preprocessed signals; Using the data processing device in combination with a fitting algorithm to fit the first preprocessed signal, to generate an antenna pattern of the antenna to be tested; Determine the beam width of the antenna to be tested from the antenna pattern of the antenna to be tested by using the data processing device in combination with the 3dB method; Analyzing the antenna pattern of the antenna to be tested by using the data processing device to calculate the first sidelobe level and the far-end sidelobe level of the antenna to be tested; The second preprocessed signal is processed by the data processing device to obtain the peak signal strength in the antenna pattern of the standard horn antenna, and compared with the peak signal strength in the first antenna pattern of the antenna under test to calculate the gain of the antenna under test.

7. The antenna far-field testing method according to claim 6, characterized in that: Using the data processing device in combination with a fitting algorithm to fit the first preprocessed signal to generate an antenna pattern of the antenna to be tested includes: Using the data processing device, retain data whose received intensity has a difference of ≥-6 dB compared to the maximum intensity value, and based on the retained data combined with the least squares method, perform quadratic linear fitting on the first preprocessed signal to generate the antenna pattern of the antenna to be tested; Among them, the formula for quadratic linear fitting is: In the above three formulas, Indicates the average azimuth or elevation angle. Indicates the average value of the echo at each position; The equation y corresponding to the antenna pattern of the antenna to be tested is calculated using the above three equations: y=ax 2 +bx+c In the above formula, x represents the antenna azimuth or elevation angle, a, b and c are constant terms obtained by quadratic linear fitting, and y represents the antenna receiving signal strength fitted at each position.

8. The antenna far-field testing method according to claim 6, characterized in that: Determining the beam width of the antenna to be tested from the antenna pattern of the antenna to be tested by using the data processing device in combination with the 3dB method includes: Calculate the azimuth or elevation angle corresponding to the maximum value of the antenna pattern of the antenna to be tested, where the azimuth or elevation angle is the azimuth angle x where the main lobe is located. ML : x ML The maximum value of the corresponding echo intensity is the main lobe intensity value of the antenna pattern of the antenna to be tested. ML for: Obtain the main lobe intensity value y ML The difference with the 3dB level gives the corresponding x l With x r value, and get the 3dB beamwidth θ : In the above three equations, x l The angle where the level on the left side is 3dB lower than the main lobe level, x r Indicates the angle at which the level on the right side decreases by 3dB compared to the main lobe level.

9. The antenna far-field testing method according to claim 8, characterized in that: Analyzing the antenna pattern of the antenna to be tested by the data processing device to calculate the first sidelobe level and the far-end sidelobe level of the antenna to be tested includes: Analyzing the side lobe area of ​​the antenna pattern of the antenna to be tested by using the data processing device, and calculating the first side lobe level and the far-end side lobe level of the antenna to be tested; Among them, the first sidelobe level S FL for: S FL =max(A L ,A R )-y ML In the above formula, A L With A R Respectively represent the left and right sides of the main lobe of the antenna pattern, and the side lobe level closest to the main lobe, max (A L , A R ) indicates A L With A R The maximum value in ; The far-end sidelobe level S SL for: S FL =max(A LD ,A RD )-y ML In the above formula, A LD With A RD They represent the side lobe levels closest to the main lobe on the left and right sides of the maximum side lobe level value outside the main lobe ±10° in the antenna radiation pattern, max (A LD , A RD ) indicates A LD With A RD The maximum value in .

10. The antenna far-field testing method according to claim 6, characterized in that: Using the data processing device to process the second preprocessed signal to obtain a peak signal strength in the antenna pattern of the standard horn antenna, and comparing it with the peak signal strength in the first antenna pattern of the antenna under test, and calculating the gain of the antenna under test, including: The formula for calculating the gain G of the antenna to be tested is: G=G hor +H-H hor +L-L hor =Ghor+ΔH+ΔL In the above formula, H and H hor represent the strength of the first received signal and the strength of the second received signal respectively; G hor represents the actual gain; L and L hor They respectively represent the receiving branch loss of the antenna under test and the cable loss from the standard horn antenna to the front end of the radar receiver in the frequency band of the antenna under test; ΔH represents the signal strength difference between the antenna under test and the standard horn antenna; ΔL represents the loss difference between the antenna under test and the standard horn antenna.

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