Meteorological radar radiation beam simulation method

Abstract

The invention relates to a meteorological radar radiation beam simulation method, which belongs to the field of radio and comprises the following steps: detecting whether the current position meets the minimum working distance of a system according to the position of a target radar and the erection position of the system; importing data of an original antenna pattern or a simulation antenna pattern actually measured by a radar, and converting the data of the original antenna pattern or the simulation antenna pattern into an attenuator-angle control quantity; performing corresponding angle matching and quantification on the attenuator-angle control quantity according to the geographical location information used by the user; and when the system scans, the quantized and matched angle and attenuator control data are read out to control the signal intensity of a system waveform generation unit, so that the waveform characteristics output when the system runs accord with the directional diagram characteristics of the expected waveform. According to the invention, the signal power is controlled according to the corresponding angle information generated according to the position relationship between the target radar and the waveform simulation equipment, so that the purpose of narrow beam output of weather radar interference is achieved.

Description

Technical Field

[0001] The invention relates to the field of radio, and in particular to a method for simulating a radiation beam of a weather radar. Background Art

[0002] At present, more than 300 meteorological radars of various types have been built across the country, covering most parts of the country. All provinces and cities have started to build meteorological radar information networks and coordinated observations. Due to the popularity of various radars and the networking of weather radars, multiple radars of the same or similar models are turned on and working at the same time. The signals emitted by each radar enter other radar receivers through the main lobe or side lobe of the radar antenna, thus forming co-frequency asynchronous interference, which seriously affects the normal detection of targets by the radar system.

[0003] According to the meteorological application requirements of the China Meteorological Administration, a small scanning portable device with narrow beam width characteristics is needed to conduct anti-co-frequency and anti-interference tests on meteorological radars in various places, and to test the anti-co-frequency interference capabilities of radar meteorological radars. Since there is currently no rapid detection and testing equipment dedicated to meteorological radar co-frequency interference, in actual applications, only drones can be used to carry signal sources and transmitting antennas to conduct interference tests on meteorological radar systems. However, due to the constraints of drone payload, it cannot withstand overly large transmitting antennas, and there are defects such as small-caliber antennas with wide beam widths, and the generated signal pattern is very different from the actual radar beam interference characteristics. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for simulating the radiation beam of a weather radar, thereby solving the deficiencies of the prior art.

[0005] The object of the present invention is achieved by the following technical scheme: a method for simulating a weather radar radiation beam, the simulation method comprising:

[0006] Step 1: Check whether the current position meets the minimum working distance of the system according to the target radar position and the system installation position;

[0007] Step 2: importing the original antenna pattern or simulated antenna pattern data measured by the radar, and converting the original antenna pattern or simulated antenna pattern data into an attenuator-angle control amount;

[0008] Step 3: Match and quantify the attenuator-angle control amount to the corresponding angle according to the user's geographical location information;

[0009] Step 4: When the system is scanning, the signal strength of the system waveform generating unit is controlled by reading the quantized matched angle and attenuator control data, so that the waveform characteristics output during system operation meet the directional pattern characteristics of the expected waveform.

[0010] The step 1 specifically includes the following contents:

[0011] Determine whether the current test conditions meet the far-field test conditions. If the far-field test conditions are met, the antenna radiation far-field radius L=2d 2 / λ and the relationship between electromagnetic wavelength and frequencyλ=speed of light / frequency. It can be seen that when the working band frequency of the weather radar being measured is known, the minimum working distance of the system is proportional to the antenna diameter. Therefore, the far-field radius L of the antenna radiation, that is, the minimum working distance of the system, is determined according to the antenna diameter. d is the antenna diameter and λ is the wavelength of the electromagnetic wave.

[0012] Determining whether the current test condition meets the far-field test condition includes:

[0013] Approximate the earth as a sphere, and regard the radiation source position A and the measured weather radar position B as two points on the earth's surface. Determine the longitude and latitude information of the two points as (Aw, Aj) and (Bw, Bj), where Aw represents the latitude of point A, Bw represents the latitude of point B, Aj represents the longitude of point A, and Bj represents the longitude of point B;

[0014] According to the trihedral cosine formula cos(c)=cos(a)×cos(b)+sin(a)×sin(b)×cos(c), substitute the longitude and latitude of points A and B, and we get cos(c)=cos(90-Bw)×cos(90-Aw)+sin(90-Bw)×sin(90-Aw)×cos(Bj-Aj), a=∠BOC, b=∠AOC, c=∠AOB, O is the center of the sphere, and C is the due north point;

[0015] After obtaining the cosine value of c, the inverse cosine function can be used to obtain the angle c. ;

[0016] After converting the angle to radians and substituting it into the radius of the earth, we can calculate the arc length between points A and B as ;

[0017] If the arc length distance is greater than or equal to the antenna far-field distance, it means that the distance between the current radiation source and the radar meets the application requirements of the meteorological radar radiation beam simulation technology. Otherwise, it means that the technical application requirements are not met and the test distance should be increased.

[0018] The step 2 specifically includes the following contents:

[0019] Using the decibel formula The signal amplitude of the radiation source device and the attenuation of the attenuator are linked, where P1 and P2 are the strength values ​​before and after the signal changes. When the value is negative, it means starting to reduce the signal or increase the attenuation, and when the value is positive, it means increasing the signal amplitude or removing the attenuator.

[0020] Find the maximum amplitude in the entered raw data as the 0° reference point, draw a vertical line at the maximum signal amplitude as the signal amplitude axis, and draw a horizontal axis at the maximum signal amplitude. The left side of the signal amplitude axis is a negative angle, and the right side of the signal amplitude axis is a positive angle. Store the raw data according to the corresponding relationship between angle and amplitude.

[0021] The step three specifically includes the following contents:

[0022] Coordinate system information conversion: Taking the radiation source as the origin, confirm the azimuth and elevation angle between the weather radar under test and the radiation source;

[0023] Angle and attenuation quantitative matching: When the radiation source is used as the origin coordinate, the weather radar under test has a minimum measurable distance range relative to the radiation source, and there are azimuth and elevation angles, and the azimuth and elevation angles are introduced into the original data.

[0024] The confirmation of the azimuth and elevation angle between the weather radar under test and the radiation source comprises:

[0025] Assume that the coordinates of the mounting base of the radiation source position A are (X A , Y A , H A ) and the coordinates of the installation base of the weather radar position B under test are (X B , Y B , H B ), the height of the radiation source antenna is h A , the height of the weather radar antenna under test is h B , the distance from the radiation source antenna to the center of the weather radar antenna under test is h AB , the azimuth is α, and the elevation is β;

[0026] Then the coordinates of the radiation source antenna are (X A , Y A , H A +h A ), the coordinates of the weather radar antenna under test are (X B , Y B , H B +h B ), then the horizontal projection distance between the radiation source and the weather radar being measured is , the height difference between the radiation source antenna and the center of the measured weather radar antenna is ;

[0027] The height angle between the radiation source antenna and the center of the measured weather radar antenna is , according to the Pythagorean theorem, the center distance between the radiation source antenna and the measured weather radar antenna is calculated ;

[0028] Since the azimuth angle between the radiation source antenna and the center of the weather radar antenna under test has nothing to do with the altitude, it is the angle projected on the horizontal plane. Therefore, the azimuth angle α is the azimuth angle A of the line connecting points A and B. θ .

[0029] The present invention has the following advantages: a method for simulating the radiation beam of a weather radar, which not only retains the advantages of a small-size antenna of a system device and a short far-field distance, does not affect the system test distance, and the device can operate at a relatively close distance, but also combines the characteristics of convenient and rapid power control of a linear attenuator sampling digital circuit, and controls the signal power according to the corresponding angle information generated according to the positional relationship between the target radar and the waveform simulation device, thereby achieving the purpose of narrow beam output of weather radar interference; only the output power of the linear attenuator sampling digital circuit is required to realize the simulation of the narrow beam radar antenna irradiation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the process of the present invention; Figure 2 This is a schematic diagram of the earth model; Figure 3 Control relationship diagram for imported data (angle-amplitude); Figure 4 It is a schematic diagram of the position relationship between the radiation source and the weather radar being measured; Figure 5 This is a real diagram of the relationship between the radiation source and the altitude of the weather radar being measured; Figure 6 This is the control relationship diagram after the scanning angle and attenuator are matched; Figure 7 Schematic diagram of radar radiation beam pattern control effect. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of the present application provided below in conjunction with the drawings is not intended to limit the scope of protection of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application. The present invention is further described below in conjunction with the drawings.

[0032] like Figure 1As shown, the present invention specifically relates to a method for simulating the radiation beam of a meteorological radar, which first detects whether the current position meets the minimum working distance of the system based on the target radar position and the system installation position; secondly, imports the original antenna pattern or simulated antenna pattern data measured by the radar, and converts the original antenna pattern or simulated antenna pattern data into an attenuator-angle control amount; then, the attenuator-angle control amount is matched and quantized according to the user's geographical location information; finally, when the system is scanned, the quantized matched angle is read out from the attenuator control data to control the signal strength of the system waveform generating unit, so that the waveform characteristics output during system operation meet the directional pattern characteristics of the expected waveform.

[0033] Furthermore, determining the minimum working distance includes:

[0034] It can be seen from the system characteristics that the system's radiation device and the weather radar under test both use antennas to transfer energy. Therefore, the system's minimum working distance is related to the antenna characteristics.

[0035] Because the field around the antenna is divided into three areas: non-radiation field area (induction field), radiation near field area and radiation far field area. After the RF signal is loaded onto the antenna, the first is the non-radiation field (induction field). This field is inversely proportional to the high-order power of the distance and decreases rapidly as the distance from the antenna increases. In this area, the reactance field is dominant, and its outer periphery is about one wavelength. Since this area is very close and small, the radar radiation beam simulation system no longer tests the radar system at this distance. In the radiation near field area, the electric field has an obvious longitudinal (or radial) component, and the power flow is not completely radial. The antenna directional characteristics are not good. In the radiation far field, the measured field components are on the radial cross section centered on the antenna, and all power flows are radially outward. In the far field, the shape of the field lobe diagram is independent of the distance to the antenna, and the antenna directional characteristics are good, so it is usually tested in the antenna radiation far field.

[0036] Since the far field of antenna radiation is radius L=2d 2 / λ (where the unit is meter, d is the diameter of the antenna, and λ is the wavelength of the electromagnetic wave), and the relationship between the wavelength of the electromagnetic wave and the frequency is: λ = speed of light / frequency. Therefore, according to the formula, when the working band frequency of the weather radar under test is known, the minimum working distance of the radar radiation beam simulation system is proportional to the antenna diameter, so the system does not need to be equipped with an antenna with too large a diameter to obtain the ideal far-field distance. Since the antenna diameter of a weather radar is usually as high as several meters, the minimum working distance of the system is only affected by the antenna size of the weather radar under test.

[0037] When it is not possible to directly determine whether the current test conditions meet the far-field test, it can be determined based on the radar radiation beam simulation system and the latitude and longitude information of the weather radar site being tested. The method is as follows:

[0038] like Figure 2 As shown in the figure, the basic principle of calculating the distance between two places is to use the spherical geometric properties of the earth, regard the true north point as C, and regard the position of the radiation source and the position of the weather radar to be measured as two points on the surface of the sphere (set as point A and point B respectively). Although the earth is an ellipse, the earth model is regarded as a sphere with a radius of R. Therefore, the distance Lab on the sphere can be calculated to get the distance between the two places. The specific method is as follows:

[0039] Determine the longitude and latitude information of the two points as (Aw, Aj) and (Bw, Bj), where Aw represents the latitude of point A, Bw represents the latitude of point B, Aj represents the longitude of point A, and Bj represents the longitude of point B; a, b, c represent the arc angles of the three points A, B, and C, a=∠BOC, b=∠AOC, c=∠AOB; O is the center of the sphere; Lab represents the arc length distance on the spherical surface between the radiation source A and the radar station B under test.

[0040] According to the trihedral angle cosine formula cos(c)=cos(a)×cos(b)+sin(a)×sin(b)×cos(c), angle C is equal to angle A~OC~B, that is, the dihedral angle between faces AOC and BOC, that is, Bj-Aj; Substituting the longitude and latitude of points A and B, we get cos(c)=cos(90-Bw)×cos(90-Aw)+sin(90-Bw)×sin(90-Aw)×cos(Bj-Aj);

[0041] After obtaining the cosine value of c, the inverse cosine function can be used to obtain the angle c (the angle between points A and B and the center of the sphere O): ;

[0042] After converting the angle to radians and substituting it into the radius of the earth, we can calculate the arc length between points A and B as .

[0043] Finally, the arc length distance at the current position is used to determine whether the current distance meets the minimum operating distance requirement of the system. If the arc length distance is greater than or equal to the antenna far field distance, it indicates that the distance between the current radiation source and the radar meets the application requirements of the meteorological radar radiation beam simulation technology. Otherwise, it indicates that the technical application requirements are not met and the test distance should be increased.

[0044] Furthermore, importing radar antenna pattern data specifically includes:

[0045] When the device terminal used for user interaction and status monitoring sends the ideal antenna pattern data or simulation data to the FPGA of the radar radiation beam simulation system using the communication unit, the FPGA stores the simulated antenna pattern data or the collected antenna pattern and other raw data. The process of importing the raw pattern data is as follows:

[0046] (1) Convert signal strength to decibels (dB):

[0047] Since decibel (dB) is a logarithmic unit, it can represent the ratio of power and signal strength gain. Since antenna gain and signal attenuation are also often measured in dB, decibel (dB) can be used to relate the signal amplitude of the radiation source device and the attenuation of the attenuator. The formula is: Where P1 and P2 are the strength values ​​before and after the signal changes. When the value is negative, it means starting to reduce the signal or increase the attenuation. When the value is positive, it means increasing the signal amplitude (gain) or removing the attenuator.

[0048] (2) Data import and conversion:

[0049] Find the maximum amplitude in the input raw data as the 0° reference point. Draw a vertical line (signal amplitude axis) at the maximum signal amplitude, and draw a horizontal axis (indicating angle) at the maximum signal amplitude. The left side of the signal amplitude axis is a negative angle, and the right side of the signal amplitude axis is a positive angle. The data is stored in the "angle-amplitude correspondence" format, that is, "store the source data as the original data according to the angle and amplitude correspondence". After the angle and amplitude of the original data are sorted and entered, the following is obtained. Figure 3 The relationship diagram shown.

[0050] Furthermore, the sampled quantized data specifically includes:

[0051] The main task of the radar radiation beam simulation system's sampling quantization data is to convert the relationship between the system scanning angle and the signal strength into a corresponding relationship table between the system scanning angle and the attenuator control value after the test target radar's relative azimuth angle relationship with the system is clear, and then send it to the digital frequency storage component for storage. The specific process is:

[0052] Since the weather radar being measured is usually not in the due north (0°) direction of the radiation source and the radiation source antenna height is not the same as the weather radar antenna altitude, the radiation source is usually used as the coordinate origin for coordinate information conversion during data conversion. The process is as follows:

[0053] Taking the radiation source as the origin, confirm the angle information of the weather radar being measured: Figure 4 and Figure 5 As shown, if the radiation source installation base coordinate A is (X A , Y A , H A ) and the coordinate B of the installation base of the weather radar under test is (X B , Y B , H B ), the height of the radiation source antenna is h A , the height of the weather radar antenna is h B, the distance from the radiation source antenna to the center of the radar antenna is h AB And azimuth angle α, elevation angle β. It can be known that the coordinate information of the radiation source antenna is (X A , Y A , H A +h A ) and the coordinate information of the weather radar antenna under test is (X B , Y B , H B +h B ), according to the above conditions:

[0054] The horizontal projection distance between the radiation source and the weather radar being measured is , the height difference between the radiation source antenna and the center of the measured weather radar antenna is , the elevation angle (pitch angle) between the radiation source antenna and the center of the weather radar antenna being measured is , using the Pythagorean theorem, we can get the center distance between the radiation source antenna and the measured weather radar antenna as .

[0055] Since the azimuth angle between the radiation source antenna and the center of the weather radar antenna under test has nothing to do with the altitude, it is the angle projected on the horizontal plane. Therefore, the azimuth angle α is the azimuth angle A of the line connecting points A and B. θ .

[0056] Angle and attenuator quantization matching:

[0057] If the radiation source antenna is used as the origin of the coordinate system, the weather radar antenna under test has a minimum measurable distance range relative to the radiation source's radiation antenna, and also has an azimuth angle α and a height angle (elevation angle) β, the original data can be converted into the form of Table 1.

[0058] Table 1. Comparison table of scanning angle attenuator matching before and after conversion

[0059] Specifically, the azimuth angle α and the elevation angle β are added to the original data angle. Since the radar antenna and the radiation source antenna are at different altitudes, different elevation angles exist during the test. Figure 5 As shown, when the original data is imported again, it is stored in an ideal state (the elevation angle and azimuth angle of the radiation source antenna and the radar antenna are in the same direction, but in actual operation, the radar site is generally located on the top of a mountain or on the roof, and the radiation source can only be installed on the ground. Therefore, there is an angle difference, and the data needs to be converted before it can be used. That is, let the radar antenna and the radiation source antenna be on the same straight line, and the radiation beam enters from the main lobe of the antenna instead of the side lobe). When the original data is imported, the default elevation angle is 0, so 0+β is still equal to β.

[0060] As can be seen from the table above, before the relationship between azimuth angle α and elevation angle (elevation angle) is introduced, the radiation source cannot be effectively positioned at an angle when the signal radiation range is very wide. Only after the relationship between azimuth angle α and elevation angle (elevation angle) β is introduced, rapid positioning can be performed (signal output is performed only after reaching the corresponding angle range). It has the benefit of strengthening the management of radiation source radiation signals, effectively reducing the radiation of surrounding operators during radiation source testing, while reducing the pollution of the electromagnetic environment caused by interference signals irradiating non-desired areas. The relationship between the attenuator and the radiation source scanning angle after sampling and quantization is as follows: Figure 6 shown.

[0061] Furthermore, the scanning control includes:

[0062] like Figure 7 As shown in the figure, due to the wide beam width of the radiation source, when simulating the 1° antenna pattern, the antenna gain of the radiation source itself will not change much within the range of ±5°. If the attenuator is highly controlled by FPGA according to the attenuator (angle-amplitude) control relationship diagram when the radiation source is scanned at an angle, a relatively ideal radiation pattern can still be obtained. The specific working principle is:

[0063] When the system is scanning, the system (radiation source) equipped with radar radiation beam simulation technology, FPGA reads the zero intermediate frequency digital signal and attenuator control table from ROM and stores them in RAM. The zero intermediate frequency digital signal is converted to intermediate frequency by DAC and then sent to the radiation source signal source module unit. Since the interface of the digital controlled attenuator is directly connected to the FPGA and the attenuation information and angle information are stored correspondingly, the digital controlled attenuator can be quickly controlled according to the radiation source scanning angle information. In order to ensure good antenna characteristics, the directional pattern of arbitrary beam width is not unlimited. It is usually ideal that the simulated beam width does not exceed half of the radiation source's own antenna beam width.

[0064] The significant difference from traditional radar is that the attenuation of the digital controlled attenuator of signal strength is not directly controlled by the computer terminal, but by the FPGA, so it can respond quickly and meet the needs of controlling signal strength while scanning, thus realizing the pattern simulation function. Since the radiation source antenna beam is very wide, this kind of wide beam antenna can radiate a scanning pattern of any beam width.

[0065] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used for various other combinations, modifications and improvements, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art do not deviate from the spirit and scope of the present invention, and should be within the scope of protection of the claims attached to the present invention.

Claims

1. A method for simulating a weather radar radiation beam, characterized in that: The simulation method comprises: Step 1: Check whether the current position meets the minimum working distance of the system according to the target radar position and the system installation position; Step 2: importing the original antenna pattern or simulated antenna pattern data measured by the radar, and converting the original antenna pattern or simulated antenna pattern data into an attenuator-angle control amount; Step 3: Match and quantify the attenuator-angle control amount to the corresponding angle according to the user's geographical location information; Step 4: When the system is scanning, the signal strength of the system waveform generating unit is controlled by reading the quantized matched angle and attenuator control data, so that the waveform characteristics output during system operation meet the directional pattern characteristics of the expected waveform.

2. The method for simulating a weather radar radiation beam according to claim 1, characterized in that: The step 1 specifically includes the following contents: Determine whether the current test conditions meet the far-field test conditions. If the far-field test conditions are met, the antenna radiation far-field radius L=2d 2 / λ and the relationship between electromagnetic wavelength and frequencyλ=speed of light / frequency. When the working band frequency of the weather radar being measured is known, the minimum working distance of the system is proportional to the antenna diameter. Therefore, the far-field radius L of the antenna radiation, that is, the minimum working distance of the system, is determined according to the antenna diameter. d is the antenna diameter and λ is the wavelength of the electromagnetic wave.

3. A weather radar radiation beam simulation method according to claim 2, characterized in that: Determining whether the current test condition meets the far-field test condition includes: Approximate the earth as a sphere, and regard the radiation source position A and the measured weather radar position B as two points on the earth's surface. Determine the longitude and latitude information of the two points as (Aw, Aj) and (Bw, Bj), where Aw represents the latitude of point A, Bw represents the latitude of point B, Aj represents the longitude of point A, and Bj represents the longitude of point B; According to the trihedral cosine formula cos(c)=cos(a)×cos(b)+sin(a)×sin(b)×cos(c), substitute the longitude and latitude of points A and B, and we get cos(c)=cos(90-Bw)×cos(90-Aw)+sin(90-Bw)×sin(90-Aw)×cos(Bj-Aj), a=∠BOC, b=∠AOC, c=∠AOB, O is the center of the sphere, and C is the due north point; After obtaining the cosine value of c, the inverse cosine function is used to obtain the angle c: ; After converting the angle to radians, substitute the radius of the earth to calculate the arc length between points A and B: ; If the arc length distance is greater than or equal to the antenna far-field distance, it means that the distance between the current radiation source and the radar meets the application requirements of the meteorological radar radiation beam simulation technology. Otherwise, it means that the technical application requirements are not met and the test distance should be increased.

4. The method for simulating a weather radar radiation beam according to claim 1, characterized in that: The step 2 specifically includes the following contents: Using the decibel formula The signal amplitude of the radiation source device and the attenuation of the attenuator are linked, where P1 and P2 are the strength values ​​before and after the signal changes. When the value is negative, it means starting to reduce the signal or increase the attenuation, and when the value is positive, it means increasing the signal amplitude or removing the attenuator. Find the maximum amplitude in the entered raw data as the 0° reference point, draw a vertical line at the maximum signal amplitude as the signal amplitude axis, and draw a horizontal axis at the maximum signal amplitude. The left side of the signal amplitude axis is a negative angle, and the right side of the signal amplitude axis is a positive angle. Store the raw data according to the corresponding relationship between angle and amplitude.

5. The method for simulating a weather radar radiation beam according to claim 3, characterized in that: The step three specifically includes the following contents: Coordinate system information conversion: Taking the radiation source as the origin, confirm the azimuth and elevation angle between the weather radar under test and the radiation source; Angle and attenuation quantitative matching: When the radiation source is used as the origin coordinate, the weather radar under test has a minimum measurement distance range relative to the radiation source, and there are azimuth and elevation angles, and the azimuth and elevation angles are introduced into the original data.

6. A method for simulating a weather radar radiation beam according to claim 5, characterized in that: The confirmation of the azimuth and elevation angle between the weather radar under test and the radiation source comprises: Assume that the coordinates of the mounting base of the radiation source position A are (X A , Y A , H A ) and the coordinates of the installation base of the weather radar position B under test are (X B , Y B , H B ), the height of the radiation source antenna is h A , the height of the weather radar antenna under test is h B , the distance from the radiation source antenna to the center of the weather radar antenna under test is h AB , the azimuth is α, and the elevation is β; Then the coordinates of the radiation source antenna are (X A , Y A , H A +h A ), the coordinates of the weather radar antenna under test are (X B , Y B , H B +h B ), then the horizontal projection distance between the radiation source and the weather radar being measured is , the height difference between the radiation source antenna and the center of the measured weather radar antenna is ; The height angle between the radiation source antenna and the center of the measured weather radar antenna is , according to the Pythagorean theorem, the center distance between the radiation source antenna and the measured weather radar antenna is calculated ; Since the azimuth angle between the radiation source antenna and the center of the weather radar antenna under test has nothing to do with the altitude, it is the angle projected on the horizontal plane. Therefore, the azimuth angle α is the azimuth angle A of the line connecting points A and B. θ .

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