A pointing calibration method for phased array antennas with radomes of arbitrary shapes

Abstract

The present invention belongs to the technical field of phased array antennas, and more specifically, relates to a pointing calibration method for phased array antennas with radomes of arbitrary shapes. The present invention can realize high-precision automatic pointing calibration of phased array antennas with radomes of arbitrary shapes, and realize automatic iteration of the calibration area through the four-area iterative grid proposed by the present invention, and finally realize the pointing calibration of any angle of the phased array antenna with radome according to the specified calibration accuracy. The present invention can effectively solve the problem of poor confirmation of the stepping of the test wave position grid points in the traditional single-frequency point single-wave position calibration method of phased array antennas with radomes (if the wave position grid points are divided too densely, the test time will increase linearly, and if the wave position grid points are divided too little, it will cause a large error in the calibration result, affecting the product pointing accuracy.), and low test efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of phased array antennas, and in particular relates to a pointing calibration method for a phased array antenna with an antenna cover of any shape. Background Art

[0002] Due to the different shapes and thicknesses of the radome, the reflection and refraction of the electromagnetic wave will be different, which will affect the amplitude, phase and even polarization direction of the electromagnetic wave. The multipath effect of the electromagnetic wave is different when it is incident at different positions of the radome. For example, the reflection and refraction paths of the electromagnetic wave are the same when the electromagnetic wave is incident from the normal direction and 45 degrees. Figure 1 As shown in the figure, 1 is an antenna product, which is used to transmit and receive electromagnetic waves; 2 is the product antenna cover, 11 is the normal incident electromagnetic wave, 12 is the refracted electromagnetic wave after passing through the antenna cover, and 13 is the refracted wave after passing through the antenna cover. The path of the electromagnetic wave incident on the antenna cover at 45° is as follows: Figure 2 As shown, 14 is the incident electromagnetic wave at 45 degrees, 15 is the refracted electromagnetic wave after the incident electromagnetic wave at 45 degrees passes through the antenna cover, and 13 is the refracted wave after the incident electromagnetic wave at 45 degrees passes through the antenna cover.

[0003] Since the radome has different effects on the phased array scanning at different angles, the phased array antenna with radome needs to be calibrated at different angles. The traditional calibration test of the phased array antenna with radome adopts single-frequency point single-wavelength position test, and different radomes, due to the factor of processing consistency, cause the same set of calibration data to be not applicable to different radomes, and the wavelength position grid point stepping of the radome antenna is difficult to confirm. If the wavelength position grid point is divided too densely, the test time will increase linearly. If the wavelength position grid point is divided too little, it will cause a large error in the calibration result, affecting the product pointing accuracy, and the test efficiency is very low. Summary of the invention

[0004] In view of the above problems, the present invention proposes a pointing calibration method for a phased array antenna with an radome of any shape.

[0005] The technical solution of the present invention is:

[0006] A method for calibrating the pointing of a phased array antenna with an arbor of any shape comprises the following steps:

[0007] S1. The beam electronic scanning coverage area of ​​the phased array product to be tested is divided into regions for the first time according to the azimuth angle and the elevation angle according to the set angles, which is defined as the initial grid region division, and a single grid region is defined as the initial single grid region;

[0008] S2. On the basis of step S1, the azimuth is used as the x-axis and the elevation is used as the y-axis, and the entire array is symmetrically divided into four quadrants, and each quadrant is phase-calibrated to maximize the energy of the entire quadrant antenna. The specific method is as follows: the four quadrants are numbered as A, B, C, and D; the antenna unit channels in quadrant A are numbered A1, A2, A3...AN-1, AN (N is the total number of channels for each unit). Quadrant B is B1, B2 to BN; and quadrants C and D are analogous. The phase calibration of quadrant A is taken as an example to illustrate the phase calibration method of each quadrant.

[0009] During measurement, the transmitter horn is directly aimed at the center of the product to be tested in the far field, and the vector network analyzer is used to connect the test horn and the two ends of the product to be tested. The S12 or S21 data on the vector network analyzer is read, which is the received energy of the antenna product to be tested. During calibration testing, the single-channel test method is adopted: during testing, the channel of one antenna unit is opened, and the channels of the other units are closed. In general, there is an attenuator on each channel of the phased array antenna, and the attenuation value of the attenuator can reach more than 30dB (30dB attenuation is equivalent to 0.001 times the original energy). When the attenuator is set to 0dB attenuation (i.e. no attenuation), the antenna unit is in the open state, and when the attenuator is set to the maximum attenuation value, the channel is closed. The antenna unit in each quadrant is tested through a single channel to obtain N amplitude and N phase test values ​​of the corresponding antenna channel. With 0° absolute phase as the reference phase, each channel in quadrants A, B, C, and D is phase compensated according to the actual test single channel absolute phase plus a negative phase value, and then the received energy tested by opening all channels in quadrant A is the maximum energy of quadrant A. By opening the B, C, and D quadrant channels in sequence, you can get the maximum energy value of the four quadrants working independently.

[0010] S3, comparing the energy values ​​of the four quadrants, and attenuating the three quadrants with large energies to ensure that the energy values ​​of the quadrants are consistent;

[0011] S4. Using the same set of calibration data for each divided area, testing each angle difference pattern, and recording the scanning zero point position;

[0012] For each initial single grid area divided by the initial grid area in S1, the center of the corresponding initial single grid area is used as the reference point for single-channel calibration, and the phase compensation data obtained is the calibration data of the single grid area. During the test, the azimuth and pitch angle of the center point of the single grid area are used as the target angles of the mechanical arm movement. The antenna product is moved to the corresponding test angle by the mechanical arm to perform single-channel calibration, and the phase calibration data of the single grid area is obtained. Then, the amplitude compensation data of the area can be obtained by performing steps S2 and S3. Then, the corresponding azimuth and pitch angle of the divided area are tested with the obtained amplitude and phase compensation data, and the scanning zero point position of the test is recorded.

[0013] Note: Single-channel phase compensation calibration is to obtain the maximum value of multiple antenna units superimposed. S2 and S3 make the energy of A, B, C, and D quadrants consistent through phenomenon attenuation in order to obtain better azimuth and elevation pointing accuracy.

[0014] S5. Determine in turn whether the difference between the angle test pointing in each partition (record the azimuth and pitch angle values ​​of the scanning zero point position as the zero point angle value obtained by the test) and the theoretical angle is less than the threshold value. If so, end the calibration of the area (after the sub-area is less than the threshold value, end the calibration of the area, and store the amplitude and phase calibration values ​​of the area calibration as the calibration values ​​of the final product in the grid area); otherwise, re-divide the partition into 4 sub-areas, and then recalibrate with the sub-area center as the reference calibration, and retest until all areas meet the calibration accuracy requirements.

[0015] The beneficial effects of the present invention are as follows: the present invention proposes to regard the antenna cover and the antenna as a whole, and adopts a four-region iterative grid method to realize automatic iteration of the calibration area. This scheme stops automatic iteration when the product pointing accuracy requirement threshold is met, which solves the problem that the traditional calibration scheme is difficult to confirm the calibration grid points, and achieves the premise of meeting the product pointing requirements while minimizing the calibration test points, thereby greatly improving the calibration efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the path of electromagnetic waves normally incident on the radome.

[0017] Figure 2 This is a schematic diagram of the path of electromagnetic waves entering the radome at 45°.

[0018] Figure 3 It is a flow chart of regional calibration of the present invention.

[0019] Figure 4 is a schematic diagram of the calibration test scenario.

[0020] Figure 5 Figure 2 is a schematic diagram of the calibration test area grid initialization.

[0021] Figure 6 It is a schematic diagram of the grid after one iteration of the calibration test area grid. DETAILED DESCRIPTION

[0022] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0023] Example

[0024] Step 1: Before the calibration test, you need to prepare for the product test before you can start the test in process 21. The calibration test scenario is as follows: Figure 4 As shown, in a microwave darkroom, first install the antenna product 2 on the six-axis robot 4, then install the antenna cover 1 on the robot, and install the standard test horn 6 on the turntable 5. Align the center of the antenna product with the center of the standard horn;

[0025] Step 2: Process 22 initializes the test area for partitioning. If the test area is ±50° in azimuth and ±50° in elevation, the initial area is divided into 10° increments, such as Figure 5 As shown, 31 is an initial single grid area. The test area is divided symmetrically according to the azimuth pitch and elevation axes. Optionally, the initial area can also be divided according to other angle steps.

[0026] Step 3: Process 23 represents dividing the entire array into four quadrants symmetrically according to the azimuth and elevation axes, such as Figure 5 The four quadrants A, B, C, and D are shown. The phase of each quadrant is calibrated using the rotating vector method (optionally, other calibration methods that can achieve phase calibration, such as the phase switching method or the mutual coupling calibration method, etc.) to maximize the antenna energy in each quadrant.

[0027] Step 4: Process 24 compares the energy values ​​of the four quadrants and attenuates the three quadrants with large energies to ensure that the energy values ​​of each quadrant are as close as possible, because the azimuth difference is: A+DBC, and the pitch difference is: A+BCD. When the energy values ​​of the four quadrants are close, a better azimuth difference and pitch difference zero depth can be obtained.

[0028] Step 5: Each divided area of ​​process 25, such as a single initial grid area 31, uses the same set of calibration data to test each angle difference pattern and record the scanning zero point position;

[0029] Step 6: Go to process 26 to determine whether the difference between the test pointing angle and the theoretical angle in each partition is less than the threshold value (the smaller the threshold value, the more areas need to be divided, and the longer the calibration time is required. Generally, the pointing accuracy can be set to 0.05°). If it meets the requirement of being less than the threshold value, the calibration of this area is ended in process 29; if the pointing accuracy of each point in the calibration of this area does not meet the threshold value requirement, the area is re-divided into 4 sub-areas (such as Figure 6 As shown in 32, a grid of 31 is evenly divided into 4 grids), and then process 28 recalibrates with the center of the sub-area as the reference calibration and retests, and the tests are cyclically repeated until all areas meet the calibration accuracy requirements, and the entire test process ends.

Claims

1. A method for calibrating the pointing of a phased array antenna with an arbor of any shape, characterized in that: The following steps are involved: S1. Divide the test area into initial grid areas according to the azimuth and elevation angles at set angles to obtain an initial single grid area; S2. On the basis of step S1, the azimuth is used as the x-axis and the elevation is used as the y-axis, and the entire array is symmetrically divided into four quadrants, and each quadrant is phase-calibrated to maximize the energy of the entire quadrant antenna. The specific method is as follows: the four quadrants are numbered as A, B, C, and D, the antenna unit channels of quadrant A are numbered as A1, A2, A3...AN-1, AN, N is the total number of channels of each unit, the antenna unit channels of quadrant B are numbered as B1, B2 to BN, and so on for quadrants C and D. The antenna unit of each quadrant obtains N amplitude and N phase test values ​​of the corresponding antenna channel through a single-channel test, and takes 0° absolute phase as the reference phase. Each channel of quadrants A, B, C, and D performs phase compensation according to the actual tested single-channel absolute phase plus a negative phase value, and then the received energy tested by opening all channels of each quadrant in turn is the maximum energy of the quadrant, thereby obtaining the maximum energy of the four quadrants when working alone, and realizing phase calibration for each quadrant. S3, comparing the energy values ​​of the four quadrants, and attenuating the three quadrants with large energies to ensure that the energy values ​​of the quadrants are consistent; S4, using the same set of calibration data for each divided area, testing each angle difference pattern, and recording the scanning zero point position; specifically: for each initial single grid area divided from the initial grid area in S1, use the corresponding initial single grid area center as the reference point for single-channel calibration, and the obtained phase compensation data is the calibration data of the single grid area; during the test, use the azimuth and pitch angle of the center point of the single grid area as the target angle of the mechanical arm movement, move the antenna product to the corresponding test angle by the mechanical arm, perform single-channel calibration, obtain the phase calibration data of the single grid area, and perform steps S2 and S3 to obtain the amplitude compensation data of the area; then use the obtained amplitude and phase compensation data to test the corresponding azimuth and pitch angle of the divided area, and record the scanning zero point position of the test; S5. Based on the recorded scanning zero point position, determine in turn whether the difference between the test angle and the theoretical angle in each partition is less than the threshold value. If so, end the calibration of the area, and store the amplitude and phase calibration values ​​of the area calibration as the calibration values ​​of the final product in the grid area. Otherwise, the partition is re-divided into 4 sub-areas equally, and the calibration is re-performed using the sub-area center as the reference calibration, and re-testing is performed until all areas meet the calibration accuracy requirements.

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