Method for testing and calibrating amplitude-phase consistency of receiving and transmitting channels of spherical phased array

Abstract

The invention mainly relates to a method for testing and calibrating amplitude-phase consistency of receiving and transmitting channels of a spherical phased array in the field of radar and communication. Comprising the following steps: constructing an amplitude-phase consistency wireless test network by using external measurement antennas distributed on an antenna housing of a spherical phased array, a measurement antenna switching unit, a duplexer, a local oscillator module, a frequency converter, test switch equipment, a vector network analyzer and the like, and dividing an array plane according to the measurement antennas; amplitude and phase testing is carried out on full-array-plane transmitting-receiving channels in a regional mode, amplitude and phase values of all transmitting-receiving channels are obtained, the first amplitude and phase measurement result serves as a zero value reference to be stored, an array plane is measured regularly and compared with amplitude and phase initial zero value reference, and according to the amplitude and phase relative change difference value, the amplitude and phase values of all transmitting-receiving channels are obtained. And correcting and calibrating the consistency of the transmitting and receiving channels. The method is suitable for daily test calibration and stability monitoring of consistency of transmitting and receiving channels of a three-dimensional array plane phased array system such as a spherical surface.

Description

A method for testing and calibrating the amplitude and phase consistency of a spherical phased array transceiver channel. Technical Field

[0001] This invention primarily relates to a method for testing and calibrating the amplitude and phase consistency of the transceiver channels of a spherical phased array in the fields of radar and communications. This invention is applicable to amplitude and phase consistency testing, calibration, and long-term monitoring during the daily operation of spherical phased array systems. Background Technology

[0002] A phased array antenna system consists of numerous transmit and receive channels. Channel amplitude-phase consistency is one of the most critical performance indicators of the system, directly affecting the beamforming performance. Inconsistent amplitude-phase consistency can lead to decreased beam gain, increased sidelobe levels, and reduced beam pointing accuracy. Therefore, during equipment development and manufacturing, the consistency of all transmit and receive channels is rigorously screened and calibrated on a wired planar test platform to ensure that all channels meet certain amplitude-phase consistency design requirements, thereby guaranteeing the overall beamforming performance of the phased array antenna system. Furthermore, after the phased array system is installed and put into use, periodic online testing and monitoring of the amplitude-phase consistency of each channel are necessary. Since all equipment is installed and fixed in place at this stage, the wired planar test environment or platform is no longer suitable for large-scale testing. Therefore, it is necessary to design an amplitude-phase consistency testing and calibration method suitable for field use environments.

[0003] In typical field applications, amplitude and phase consistency testing of phased array antenna systems is conducted using two methods: internal monitoring and external monitoring. Internal monitoring requires adding a calibration signal test link to each transmit / receive channel during the initial design phase. Furthermore, the system needs a large-scale signal distribution and transmission network, resulting in relatively complex circuit design and additional errors in the test link. External monitoring, on the other hand, is generally implemented using external calibration test equipment. Since it does not require adding a calibration signal link to each channel, it is relatively simple to implement and can reduce the design difficulty and cost of the phased array system. Therefore, this invention will adopt the external monitoring method.

[0004] External monitoring methods are further divided into two test scenarios: far-field testing and near-field testing. Far-field testing refers to the distance between the external measurement antenna and the phased array antenna array that meets the far-field condition. Taking reception as an example, the wavefront of the microwave signal emitted by the measurement antenna received by the antenna array is a plane wave or approximately a plane wave. Near-field testing refers to the distance between the external measurement antenna and the phased array antenna array that does not meet the far-field condition. Taking reception as an example, the wavefront of the microwave signal emitted by the measurement antenna received by the antenna array is a spherical wave.

[0005] In far-field testing scenarios, for planar phased array antenna systems, a fixed measurement antenna can typically be erected at the far-field location. Calibration ensures the measurement antenna is directly facing the normal to the planar array, and its beam covers the entire array. Taking reception as an example, the electromagnetic waves emitted by the measurement antenna arrive at the array as approximately plane waves, meaning that each antenna element receives the signal with equal time delay and phase. A wireless testing system, consisting of the measurement antenna, transceiver test link, and testing instruments, is then used to calibrate the amplitude and phase performance of each transceiver channel of the antenna array. However, for spherical phased array antenna systems, due to their three-dimensional structure, testing antenna element channels in all directions using the above method would require constructing multiple far-field calibration towers. Furthermore, to achieve a certain elevation angle in the far field, the towers would need to be very tall, significantly increasing construction costs and the difficulty of daily calibration testing. Therefore, this approach is not feasible.

[0006] In near-field testing scenarios, regardless of whether it's a planar or spherical array, the distance between the external measurement antenna and each antenna element is different. Taking reception as an example, the electromagnetic wave emitted by the measurement antenna reaches the array surface as a spherical wave. For each antenna element, the received signal transmission delay and phase are different. Therefore, the test results will include amplitude differences (the amplitude difference between channels is generally very small at close range) and phase differences due to the different spatial distances. Precise calibration of the measurement antenna's coordinate position relative to the phased array surface is necessary. This is especially important for high-frequency microwave and millimeter-wave arrays, where the signal wavelength is very small, and precise positional accuracy can lead to significant phase testing errors. Therefore, to obtain accurate phase consistency test results, the calibration accuracy of the near-field measurement antenna's coordinate position is crucial. Typically, to achieve high phase testing accuracy, the positional error needs to be on the order of millimeters, which greatly increases the difficulty of coordinate measurement. Summary of the Invention

[0007] The purpose of this invention is to avoid the shortcomings of the above-mentioned background technology and provide an external monitoring and testing method that satisfies the amplitude and phase consistency of the transceiver channels in all directions of the entire space of a spherical phased array. This method solves the problems of high construction cost and high complexity caused by far-field calibration of spherical phased arrays, while avoiding the problem of high-precision calibration of the coordinate position of the measurement antenna under near-field conditions. This achieves the purpose of amplitude and phase consistency testing, calibration and stability monitoring of the spherical phased array system.

[0008] The technical solution adopted in this invention is as follows: a method for testing and calibrating the amplitude and phase consistency of the transceiver channel of a spherical phased array, comprising the following steps: (1) multiple measurement antennas are arranged in different directions on the inner wall of the hemispherical radome of the full-space spherical phased array antenna, and the spherical array surface is divided into several regions according to the coverage of the measurement antennas; (2) an amplitude and phase consistency wireless test network is constructed, including a measurement antenna switching unit, a duplexer, a frequency converter, a local oscillator module, a test switch device and a vector network analyzer; using the amplitude and phase consistency wireless test network, the transceiver channel of the full-space spherical phased array antenna is tested for amplitude and phase consistency in different regions, and the amplitude and phase measurement values ​​of all transceiver channels on the full-space spherical phased array antenna are obtained; (3) the first amplitude and phase measurement results are used as the zero value reference, the transceiver channel of the full-space spherical phased array antenna is periodically tested for amplitude and phase consistency, and the test results are compared with the zero value reference, and the amplitude and phase characteristics of the transceiver channel are corrected according to the relative change difference of amplitude and phase.

[0009] Furthermore, in step (1), the beamwidth of a single measurement antenna covers a local array, and all measurement antennas achieve beam coverage of the entire spherical space.

[0010] Furthermore, in step (2), the process of performing amplitude and phase consistency testing on the transmission channel is as follows: the vector network analyzer is parameter-set and initialized, and the test switch device is set. The intermediate frequency test signal output by the vector network analyzer is sequentially switched to the transmission channel under test of the full-space spherical phased array antenna. The transmission channel under test processes the intermediate frequency test signal and converts it into a radio frequency signal, which is then radiated into space by the corresponding antenna array element. The measurement antenna corresponding to the transmission channel under test receives the radio frequency test signal transmitted through space, and by setting the measurement antenna switching unit, the signal received by the measurement antenna is transmitted to the frequency converter via a duplexer. The frequency converter converts the received signal into an intermediate frequency test signal, and then transmits the intermediate frequency test signal to the vector network analyzer via the test switch device. The vector network analyzer measures the amplitude and phase values ​​of the corresponding transmission channel. The transmission channels under test are changed one by one to complete the amplitude and phase value testing of all transmission channels of the full-space spherical phased array antenna.

[0011] Further, in step (2), the process of performing amplitude and phase consistency testing on the receiving channel is as follows: the vector network analyzer is parameter-set and initialized, and the intermediate frequency test signal output by the vector network analyzer is output to the frequency converter by setting the test switch device. The frequency converter converts the intermediate frequency test signal into an RF test signal, which is then transmitted to the measurement antenna switching unit via a duplexer. The measurement antenna switching unit is set according to the selected receiving channel under test, and the RF test signal is transmitted to the corresponding measurement antenna, which radiates the signal into space. The receiving channel under test of the full-space spherical phased array antenna is selected, and the antenna array element corresponding to the receiving channel under test receives the RF test signal transmitted by the measurement antenna. The receiving channel under test processes the signal and converts it into an intermediate frequency test signal, which is then transmitted to the vector network analyzer via the test switch device. The vector network analyzer measures the amplitude and phase values ​​of the corresponding receiving channel. The receiving channels under test are changed one by one to complete the amplitude and phase value testing of all receiving channels of the full-space spherical phased array antenna.

[0012] Compared with the prior art, the present invention has the following advantages: 1. The present invention avoids the problems of high construction cost and difficulty in daily calibration and testing of spherical phased arrays under far-field calibration and testing conditions.

[0013] 2. This invention solves the problem of amplitude and phase consistency calibration of array element channels in all directions of a spherical phased array, and is suitable for routine testing and calibration after system installation.

[0014] 3. This invention avoids the problem of needing to precisely calibrate the coordinate position of the measuring antenna under near-field conditions. Attached Figure Description

[0015] Figure 1 is a schematic diagram of the layout of the external measurement antenna of the spherical phased array system of the present invention.

[0016] Figure 2 is a schematic diagram of the wireless test network composition for the amplitude and phase consistency of the transceiver channel of the full-space spherical phased array antenna of the present invention. Detailed Implementation

[0017] The present invention will be further explained and described below with reference to the accompanying drawings and embodiments.

[0018] A method for testing and calibrating the amplitude and phase consistency of a spherical phased array transceiver channel includes the following steps: (1) The layout of the external measurement antenna is shown in Figure 1. The external measurement antenna is installed at fixed positions in different directions on the inner wall of the hemispherical radome of the full-space spherical phased array antenna. The operating frequency band of the measurement antenna covers the transceiver operating frequency of the phased array system and can be used to transmit and receive signals within the operating frequency. With the cooperation of the duplexer, bidirectional transmission of the transceiver signal can be realized. By adjusting so that each measurement antenna faces the array surface of the full-space spherical phased array antenna, the beamwidth of a single measurement antenna covers a local array surface, and finally ensures that all array elements on the array surface can fall within the 3dB beamwidth range of at least one measurement antenna, that is, the measurement antenna achieves beam coverage of the entire array surface.

[0019] Based on the coverage area of ​​the measurement antennas, the array is divided into several array test areas. Assuming there are Tc(i) measurement antennas (i=1, 2...M, where M is the number of measurement antennas), each measurement antenna corresponds to one test area, and each test area contains a set of array transmission channels T. T (i, j) and receiving channel T R (i, j) (j = 1, 2, ..., N, where N is the number of transmit and receive channels corresponding to the measurement antenna Tc(i).

[0020] (2) Construct an amplitude-phase consistency wireless test network, including a measurement antenna switching unit, a duplexer, a frequency converter, a local oscillator module, test switching equipment, and a vector network analyzer; as shown in Figure 2. The equipment connection relationship of the amplitude-phase consistency wireless test network is as follows: all external measurement antennas are connected to the branch ports of the measurement antenna switching unit through amplitude- and phase-stabilized cable assemblies. The attenuation (amplitude) and phase between each cable assembly need to be calibrated to ensure that the signal transmission attenuation and phase characteristics between each cable are the same. During operation, the measurement antenna switching unit is responsible for selecting one of the measurement antennas to its common selection port and connecting it to the common port of the duplexer through a cable.

[0021] The TX (transmit) port of the duplexer is connected to the RF input port of the lower frequency conversion module in the inverter, and the RX (receive) port of the duplexer is connected to the RF output port of the upper frequency conversion module in the inverter. The input selection port 1 of the test switch is connected to the intermediate frequency (IF) output port of the lower frequency conversion module in the inverter. The input selection port 2 of the test switch is connected to the IF output port of the receiving switch matrix. The input selection port 3 of the test switch is connected to the output port of the vector network analyzer. The output selection port 1 of the test switch is connected to the IF input port of the upper frequency conversion module in the inverter. The output selection port 2 of the test switch is connected to the IF input port of the transmitting switch matrix. The output selection port 3 of the test switch is connected to the input port of the vector network analyzer. The output of the local oscillator module is connected to the local oscillator input port of the inverter, providing the inverter with the necessary local oscillator signal.

[0022] The spherical phased array system to be measured in this invention mainly consists of a transmit switch matrix, a receive switch matrix, a transmit beamforming unit, a receive beamforming unit, an active T / R assembly, and antenna elements. A single receive channel link mainly includes the antenna elements, the receive link in the active T / R assembly, the receive beam processing link in the receive beamforming unit, and the transmission link in the receive switch matrix; a single transmit channel link mainly includes the antenna elements, the transmit link in the active T / R assembly, the transmit beam processing link in the receive beamforming unit, and the transmission link in the transmit switch matrix.

[0023] After the overall installation of the spherical phased array system is completed, the performance of the synthesized beam of the phased array antenna can first be tested using conventional antenna testing methods such as UAVs and far-field calibration. After the system performance, such as antenna gain and main lobe ratio, meets the requirements (which indirectly indicates that the amplitude and phase consistency of the system channels meets the design requirements and can guarantee the overall performance of the system), the amplitude and phase consistency of the transceiver channels of the full-space spherical phased array antenna can be tested through an amplitude and phase consistency wireless test network to obtain the amplitude and phase measurement values ​​of all transceiver channels on the full-space spherical phased array antenna.

[0024] The process of conducting amplitude and phase consistency testing on the transmission channel is as follows: First, the vector network analyzer is parameter-set and initialized. Based on the system operating frequency, the corresponding intermediate frequency (IF) signal frequency and bandwidth of the vector network analyzer are set, and the measurement mode (S21) and measurement parameters (amplitude and phase) of the vector network analyzer are configured. Through-state calibration is then performed on the vector network analyzer. After calibration, the output port of the vector network analyzer is connected to the test switch device, and the vector network analyzer outputs an IF test signal. Then, by setting the test switch device, the IF test signal output by the vector network analyzer is switched to the transmit switch matrix. The transmit switch matrix then switches the signal and sends it to the corresponding transmit beamforming unit. Finally, by setting the transmit beamforming unit, the transmission channel T under test is selected. T (i, j) transmits the signal to the transmission channel T. T In (i, j), there is no signal in the other transmission channels; after the signal is up-converted and filtered in the transmission channel, it becomes an uplink RF test signal, and after being amplified by power, it is sent to the antenna array element, which then radiates the signal into space.

[0025] Uplink RF test signal via transmit channel T T After transmission (i, j), the signal is transmitted through space and then received by the corresponding measurement antenna Tc(i) of the transmission channel. By setting up a measurement antenna switching unit, the measurement antenna Tc(i) is selected to connect with the duplexer. The signal is transmitted through the measurement antenna switching unit and the duplexer to the downconversion module of the frequency converter and converted into an intermediate frequency test signal. Finally, the intermediate frequency test signal is switched to the input port of the vector network analyzer by the test switching equipment to form a signal closed loop.

[0026] Finally, the amplitude and phase values ​​of the transmission channel are measured by a vector network analyzer and denoted as A. T (i, j) and P T If (i, j), then the amplitude and phase performance test of that transmission channel is complete. Repeat the above test by changing each transmission channel and switching the measurement antenna according to the corresponding relationship, completing the amplitude and phase value tests for all transmission channels of the full-space spherical phased array antenna. The amplitude and phase measurement results of the system are denoted as set {A}. T (i, j), P T (i, j)}, (i = 1, 2, ..., M, where M is the number of measurement antennas, j = 1, 2, ..., N, where N is the number of channels corresponding to measurement antenna Tc(i).

[0027] The process of performing amplitude and phase consistency testing on the receiving channel is as follows: First, the vector network analyzer is parameter-set and initialized. Based on the system operating frequency, the corresponding intermediate frequency (IF) signal frequency and bandwidth of the vector network analyzer are set, and the measurement mode (S21) and measurement parameters (amplitude and phase) of the vector network analyzer are configured. A pass-through calibration is then performed on the vector network analyzer. After calibration, the output port of the vector network analyzer is connected to the test switch, and the vector network analyzer outputs an IF test signal. Then, the IF test signal output by the vector network analyzer is switched to the up-conversion module of the frequency converter via the test switch to become an RF test signal. This signal is then transmitted to the measurement antenna switching unit via a duplexer, and the signal is processed according to the selected receiving channel T. R (i, j) Set up a measurement antenna switching unit to switch the radio frequency signal to the corresponding measurement antenna Tc(i), and the measurement antenna will radiate the signal into space.

[0028] By setting up the receiving beamforming unit, the receiving channel T to be tested is selected. R (i, j), received by the receiving channel T under test R (i, j) receives the RF test signal transmitted by the measurement antenna Tc(i), while the other receiving channels have no signal. After the signal is amplified, filtered and down-converted in the receiving channel, it becomes an intermediate frequency signal. Then, after the signal is switched by the receiving switch matrix, it is sent to the corresponding test switch device. By setting the test switch device, the intermediate frequency signal is switched to the input port of the vector network analyzer to form a signal closed loop.

[0029] Finally, the amplitude and phase values ​​of the receiving channel are measured by a vector network analyzer and denoted as A. R (i, j) and P R If (i, j), then the amplitude and phase performance test of that receiving channel is complete. Repeat the above test by changing each receiving channel and switching the measurement antenna according to the corresponding relationship, completing the absolute amplitude and absolute phase value tests for all receiving channels of the full-space spherical phased array antenna. The amplitude and phase measurement results of the system are denoted as set {A}. R (i, j), P R (i, j)}, (i = 1, 2, ..., M, where M is the number of measurement antennas, j = 1, 2, ..., N, where N is the number of channels corresponding to measurement antenna Tc(i).

[0030] (3) Using the initial amplitude and phase measurement results as the zero-value reference, periodically test the amplitude and phase consistency of the transceiver channel of the full-space spherical phased array antenna, compare the test results with the zero-value reference, and correct the amplitude and phase characteristics of the transceiver channel based on the relative change difference of amplitude and phase.

[0031] For the first time, the initial amplitude and phase measurement results are used as the zero-value reference. The initial amplitude zero-value reference and phase zero-value reference of the transmission channel are denoted as: AT0 (i, j) and P T0 (i, j), the initial amplitude zero reference and phase zero reference of the receiving channel are denoted as: A R0 (i, j) and P R0 (i, j). The amplitude and phase zero-value references for all transmission channels are denoted as the set {A}. T0 (i, j), P T0 (i, j)}, the amplitude and phase zero references for all receiving channels are denoted as the set {A}. R0 (i, j), P R0 (i, j)}.

[0032] During the system's daily operation, amplitude and phase consistency tests are periodically performed on the transmit and receive channels of the full-space spherical phased array antenna to obtain the amplitude and phase consistency results of all transmit channels {A}. T (i, j), P T (i, j)} and the amplitude-phase consistency results of all received channels {A R (i, j), P R (i, j)}. The amplitude and phase measurement results of this transmission channel are subtracted from the zero-value reference, and the amplitude difference is ▽A. T (i, j) = A T (i,j)-A T0 (i, j), the phase difference is ▽P T (i, j) = P T (i,j)-P T0 (i, j), the amplitude difference and phase difference result {▽A T (i, j), ▽P T (i, j)} is used as the amplitude and phase correction value to compensate all channels, thereby achieving the purpose of consistent amplitude and phase calibration and long-term monitoring of the transmitting channel. Similarly, the amplitude and phase measurement results of all receiving channels are subtracted from the zero reference to obtain the amplitude and phase correction value {▽A} of the receiving channel. R (i, j), ▽P R (i, j)} and compensate for all channels, thereby achieving the purpose of consistent amplitude and phase calibration and long-term monitoring of the receiving channels.

Claims

1. A method for testing and calibrating the amplitude and phase consistency of a spherical phased array transceiver channel, characterized in that, The steps include: (1) Deploying multiple measurement antennas in different directions on the inner wall of the hemispherical radome of the full-space spherical phased array antenna, and dividing the spherical array into several regions according to the coverage of the measurement antennas; (2) Constructing an amplitude and phase consistency wireless test network, including a measurement antenna switching unit, duplexer, frequency converter, local oscillator module, test switch equipment and vector network analyzer; using the amplitude and phase consistency wireless test network, performing amplitude and phase consistency tests on the transceiver channels of the full-space spherical phased array antenna in different regions, and obtaining the amplitude and phase measurement values ​​of all transceiver channels on the full-space spherical phased array antenna; (3) Using the initial amplitude and phase measurement results as the zero value reference, periodically performing amplitude and phase consistency tests on the transceiver channels of the full-space spherical phased array antenna, and comparing the test results with the zero value reference, and correcting the amplitude and phase characteristics of the transceiver channels according to the relative change difference of amplitude and phase.

2. The method for testing and calibrating the amplitude and phase consistency of a spherical phased array transceiver channel according to claim 1, characterized in that, In step (1), the beamwidth of a single measurement antenna covers a local array, and all measurement antennas achieve beam coverage of the entire spherical space.

3. The method for testing and calibrating the amplitude and phase consistency of a spherical phased array transceiver channel according to claim 1, characterized in that, In step (2), the process of performing amplitude and phase consistency test on the transmission channel is as follows: set and initialize the parameters of the vector network analyzer, set the test switch device, and switch the intermediate frequency test signal output by the vector network analyzer to the transmission channel under test of the full-space spherical phased array antenna in sequence. The transmission channel under test processes the intermediate frequency test signal and converts it into a radio frequency signal, which is then radiated into space by the corresponding antenna array element. The measurement antenna corresponding to the transmission channel under test receives the radio frequency test signal transmitted through space. By setting up a measurement antenna switching unit, the signal received by the measurement antenna is transmitted to the frequency converter via a duplexer. The frequency converter converts the received signal into an intermediate frequency test signal. Then, the intermediate frequency test signal is transmitted to the vector network analyzer via the test switching equipment. The vector network analyzer measures the amplitude and phase values ​​of the corresponding transmission channel. One by one, the transmission channels under test were replaced to complete the amplitude and phase value tests of all transmission channels of the full-space spherical phased array antenna.

4. The method for testing and calibrating the amplitude and phase consistency of a spherical phased array transceiver channel according to claim 1, characterized in that, In step (2), the process of performing amplitude and phase consistency test on the receiving channel is as follows: the vector network analyzer is parameter-set and initialized, and the intermediate frequency test signal output by the vector network analyzer is output to the frequency converter by setting the test switch device. The frequency converter converts the intermediate frequency test signal into an radio frequency test signal, which is then transmitted to the measurement antenna switching unit via a duplexer. The measurement antenna switching unit is set according to the selected receiving channel under test, and the radio frequency test signal is transmitted to the corresponding measurement antenna, which then radiates the signal into space. The test receiving channel of the full-space spherical phased array antenna is selected. The antenna array element corresponding to the test receiving channel receives the radio frequency test signal transmitted by the measurement antenna. The test receiving channel processes the signal and converts it into an intermediate frequency test signal. Then, it is transmitted to the vector network analyzer through the test switching equipment. The vector network analyzer measures the amplitude and phase values ​​of the corresponding receiving channel. One by one, the receiving channels under test were replaced to complete the amplitude and phase value tests of all receiving channels of the full-space spherical phased array antenna.

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